Post on 04-Jun-2018
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ext oo
from ro rammin to NetworkinS. C. J. Lin, Delmar
1994
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actions are controlled by the direct insertion of
numerical data at some oint. The s stem must
automatically interpret at least some portion of this
data. The coded instructions are converted into two
types of control signals.
pluses of electric output: positioning of the machine
s indle relative to the work iece and its s eed. on/off control signals: spindle rotation control, coolant
su l selection of cuttin tool sto clam in and
unclamping.
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1947 - John Parsons (Michigan UAS): Three-axis
curvature data to control machine tool motion for thecomp ex mac n ng o a rcra componen s.
1949 - Parsons joined MIT.
1951 - First numerically controlled machine tool was
developed in MIT.
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Programming Languages
Development
Automatically Programmed Tool (APT) was
developed in MIT to define part geometry and
cutter aths for work ieces. The ma orit of toda s
computer-aided design/computer-aided
manufacturing (CAD/CAM) NC systems are APT-
based. Other ATP-based lan ua es are
ADAPT(IBM), IFAPT(France), FAPT(Japan).
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Computer Numerical Control (CNC)
and Distributive Numerical Control
A dedicated computer
is built into the MCUto control one
machine tool.
1980 - a network of
computers is used to
coordinate theoperation of a number
of CNC machines.
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Basic Element of
a CNC System
Machine Control Unit
It reads and interprets the
machining a particularwork iece and eneratin
electric output signals. It
also acts as a feedbackcontrollerfor precise
positioning of machine table
or spindle. MCU consists oftwo main units.
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MCU consists of two main units.
Data-processing unit (DPU)
reads coded instructions
processes coded instructions
axis to the CLU.
executes linear or circular interpolations based
and generates control signals
implement auxiliary control function
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Computer Numerical Control
(CNC)CNC is a self-contained NC system for a single
machine tool that uses a dedicated computer con ro e y s ore ns ruc ons n e memory o
implement some or all of the basic NC functions. It is
- .
Monitoring display and graphic representation of the
Data entry: manual data input (MDI) and RS-232-C
ontro er memory: e execut on program res es n
Read only memory (ROM). The part programs are
- .
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Program editing: After part programs are downloaded
to the CNC memory, changes or updates can bema e a e mac ne.
Program verification: Simulation programs allow the
cu er pa o e sp aye an ver e grap ca y ona display unit before the part program is run on the
.
Error diagnostics: program error, operation error and
.
Communication facility. CNC control units have the
microprocessor-based devices.
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Management information: on-line parameter and
information display Coordinate system (absolute vs. Incremental)
Unit system ( inch vs. Metric)
Code format (EIA vs. ASCII) Macro and com utin ca abilit
Cutter compensation for size and length
Advanced programming features
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Increased productivity
High accuracy and repeatability Reduced production costs
Reduced indirect o eration costs
Facilitation of complex machining operations
Improved production planning and control
Facilitation of flexible automation
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Accuracy: agreement between the actual
value of the measured variable and themeasurement as it is output by the sensor.
epeaa y recson : vara on over
repeated measurement.
variable to which the sensor will respond
with a like change in the measurement
Range: the upper and lower limits of the
measured variable for which
measurement can be made.
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Machine control unitTooling system
Three-axis vertical machinin
centre
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Cooling system
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Calibrated by laser equipment
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ra g ness easuremen
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--CNC,,
T e sp n e suspen e y "Act ve Magnet
Bearings". It also uses HSK50 tooling system and
increases the rigidity of the tool clamping. Thisa ows or ex reme g spee cu ng w ra es
up to 40 m/min. The machine employs noiseless
slide covers, oilless guide ways and precision ball
.
Travel___________ __800x500x550mmTable working surface_____900x465mm
______
Spindle speed______Max.10,000-
160,000rpm
____OPT(60x60x30m/min)