Post on 21-Mar-2018
CNC MACHINE
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
N0005(FADAL VMC 6030 - VH65)N0010G90G40G80N0015T1M6N0020S500M3N0025G0X-11958Y4N0030G43Z20H1N0035Z25N0040G1Z-5F50N0045X-4N0050Y8923N0055X-11958N0060Y13846N0065X-4N0070Y18769N0075X-11958N0080Y23692N0085X-4N0090Y28615N0095X-11958N0100Y33538N0105X-4
3
ISO MACHINE TOOL AXES DEFINITIONS
AXIS MACHINE TOOL WITH SPINDLE MACHINE TOOL WITH
NO SPINDLE
Z axis of spindle
(+Z) as tool goes away from the work piece
perpendicular to work
holding surface (+Z) as
tool goes away from the
workpiece
MACHINE
TOOL WITH
ROTATING
WORKPIECE
MACHINE TOOL WITH
ROTATING TOOL
HORIZONT
AL AXIS
VERTICAL
AXIS
X radial and
parallel to
cross slide
(+X) when
tool goes away
from the axis
of spindle
horizontal
and parallel
to work
holding
surface
(+X) to the
right when
viewed
from
spindle
towards
work piece
horizontal
and parallel
to the work
holding
surface
(+X) to the
right when
viewed
from
spindle
towards
column
parallel to and positive in
the principal direction of
cutting (primary motion)
Y apply right hand rules
4
RIGHT HAND RULEVertical Machine Horizontal Machine
5
STANDARD LATHE COORDINATE SYSTEM
6
STANDARD MILLING MACHINECOORDINATE SYSTEM
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
N0005(FADAL VMC 6030 - VH65)N0010G90G40G80N0015T1M6N0020S500M3N0025G0X-11958Y4N0030G43Z20H1N0035Z25N0040G1Z-5F50N0045X-4N0050Y8923N0055X-11958N0060Y13846N0065X-4N0070Y18769N0075X-11958N0080Y23692N0085X-4N0090Y28615N0095X-11958N0100Y33538N0105X-4
3
ISO MACHINE TOOL AXES DEFINITIONS
AXIS MACHINE TOOL WITH SPINDLE MACHINE TOOL WITH
NO SPINDLE
Z axis of spindle
(+Z) as tool goes away from the work piece
perpendicular to work
holding surface (+Z) as
tool goes away from the
workpiece
MACHINE
TOOL WITH
ROTATING
WORKPIECE
MACHINE TOOL WITH
ROTATING TOOL
HORIZONT
AL AXIS
VERTICAL
AXIS
X radial and
parallel to
cross slide
(+X) when
tool goes away
from the axis
of spindle
horizontal
and parallel
to work
holding
surface
(+X) to the
right when
viewed
from
spindle
towards
work piece
horizontal
and parallel
to the work
holding
surface
(+X) to the
right when
viewed
from
spindle
towards
column
parallel to and positive in
the principal direction of
cutting (primary motion)
Y apply right hand rules
4
RIGHT HAND RULEVertical Machine Horizontal Machine
5
STANDARD LATHE COORDINATE SYSTEM
6
STANDARD MILLING MACHINECOORDINATE SYSTEM
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
3
ISO MACHINE TOOL AXES DEFINITIONS
AXIS MACHINE TOOL WITH SPINDLE MACHINE TOOL WITH
NO SPINDLE
Z axis of spindle
(+Z) as tool goes away from the work piece
perpendicular to work
holding surface (+Z) as
tool goes away from the
workpiece
MACHINE
TOOL WITH
ROTATING
WORKPIECE
MACHINE TOOL WITH
ROTATING TOOL
HORIZONT
AL AXIS
VERTICAL
AXIS
X radial and
parallel to
cross slide
(+X) when
tool goes away
from the axis
of spindle
horizontal
and parallel
to work
holding
surface
(+X) to the
right when
viewed
from
spindle
towards
work piece
horizontal
and parallel
to the work
holding
surface
(+X) to the
right when
viewed
from
spindle
towards
column
parallel to and positive in
the principal direction of
cutting (primary motion)
Y apply right hand rules
4
RIGHT HAND RULEVertical Machine Horizontal Machine
5
STANDARD LATHE COORDINATE SYSTEM
6
STANDARD MILLING MACHINECOORDINATE SYSTEM
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
4
RIGHT HAND RULEVertical Machine Horizontal Machine
5
STANDARD LATHE COORDINATE SYSTEM
6
STANDARD MILLING MACHINECOORDINATE SYSTEM
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
5
STANDARD LATHE COORDINATE SYSTEM
6
STANDARD MILLING MACHINECOORDINATE SYSTEM
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
6
STANDARD MILLING MACHINECOORDINATE SYSTEM
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Motion control in CNC machine
Point to Point control
bull Objective of the machine tool control system is to move the cutting tool to a predefined location
bull Once the tool reaches to the desired position machining is performed
bull Drilling is the example of this kind of control
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Straight cut control
bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining
bull It is not possible to have combine motion in more than a single axis direction
bull Angular cuts are not possible
bull Milling operations to fabricate work piece of rectangular configurations is the example
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Countouring control
bull Most complex
bull Most flexible
bull Most expensive
bull Simultaneous control of more than one axis movement
bull Milling and turning operations are the examples
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
25 axis and 3 axis machines
bull A 25 axis machine really has three moving axes but only two axes can move together
bull Simple operations like drilling and most milling fall into this category
bull 3-axis machining requires that all three axes be moving at the same time
bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
25 axis milling
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
3 axis machining
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
5 axis machining
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Control system of CNC machine tool
bull MCU-Machine Control Unit
Rudresh MakwanaITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Adaptive Control
bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity
1 Adaptive Control Optimization(ACO)
2 Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
bull Adaptive Control Optimization(ACO)
Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
bull Adaptive Control with Constraints(ACC)
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Control systems of CNC machine tool(Cont)
Open loop control system
bull Feed back is not there
bull Corrective action can not be taken
bull This type of system may be used in a machine tool where output is constant
bull Cutting force and loading of a machine tool do not remain constant
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Closed loop control system
bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Components of CNC machine
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Structure of CNC machine toolRequirements Structure Design
bull CNC machines are designed for long hours of continuous production
bull High magnitudes-multi directional forces
bull Huge quantity of swarf is producedbull Thermal distortions may happen
due to hot chips
bull Heavier structure to provide adequate strength and rigidity
bull Overhangs of cutting forces motor forces and frictional forces are avoided
bull Structure having better swarfdisposle can be made by providing slant bed
bull Sources of heat are evenelylocated to distribute the heat
bull Air conditioning may have to be recommanded to eliminate the distortion of the structure
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Drive System
Two drives are use in CNC machines
1 Spindle drives to provide the main spindle power for cutting
2 Feed drives to drive the axis as per the program
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Spindle drives
bull Large power motors are used
bull Speed varies infinitely
bull DC motors are used speed is controlled by varying
the voltage infinitely
bull Controlled frequency converters-ac drives
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Feed drives
bull Stepper motors
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
bull Stepper motors (cont)
Low cost
simple construction
high reliability
low maintenance
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
bull Servomotors
It consists of a suitable motor coupled to a sensor for position feedback
Increases positional accuracy
Comparison of stepper motor and servomotor
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Recirculating ball screw
bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool
bull Normal machine tool comprises Lead screw having square thread for the purpose
bull High friction
bull Backlash
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Slidewaysbull Normal slideways-large amount of friction
bull Rolling friction elements-Linear Motion devices
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Feedback Devices
bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement
bull The common devices used presently are
1 Encoders
2 Linear scales
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Optical rotary encoder
bull Converts rotary motion into a sequence of digital pulses
bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery
bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured
Light sourceRotary disc
Light measuring deviceRudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Optical rotary encoder
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Absolute Encoder
bull The encoder disc is etched with distinct positions
four track encoder disc
bull It uses natural binary code
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
2 Incremental encoder
Consists one track and two sensors
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Feed back devices (cont)
Linear scalebull Direct measurement of the absolute position of the
slide
bull Finely graduated scale made of either glass or SS
bull Scaling unit
bull One is fixed to the stationary part of the machine tool and other to the moving part
bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University
Rudresh Makwana ITNirma University