1 HYDRAULIC CIRCUITS Welcome to the Session on :.

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HYDRAULIC CIRCUITS

Welcome to the Session on :

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HYDRAULIC

POWER

UNIT

HYDRAULIC CIRCUITS

MOTOR & PUMP

PRESSURE CONTROL VALVES

FLOW CONTROL VALVES

DIRECTION CONTROL VALVES

ACCESSORIES

ACTUATORS

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HYDRAULIC CIRCUITS

A GOOD HYDRAULIC SYSTEM REQUIREMENT - SATISFY THE SPECIFICATIONS OF THE OPERATION WITH

SAFETY

PERFORM SMOOTH OPERATION

LOW ENERGY CONSUMPTION – LOW HEAT GENERATION

REDUCE INITIAL COST & RUNNING COST

MAKE MAINTENANCE EASY

HYDRAULIC CIRCUITS ARE GRAPHICAL DIAGRAMS OF THE HYDRAULIC SYSTEMS.

IT ALSO INDICATES EACH OPERATION OF THE COMPONENTS.

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUITVariable displacement pump circuit

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUIT Meter – in Circuit

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUIT Meter – out Circuit

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUIT Bleed – off Circuit

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUIT Deceleration Circuit

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUITFeed speed varying circuit

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUITMulti Speed Circuit

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Q1 : High Flow

Q2 : Low FlowQ1

Q2

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUITMulti Speed Circuit

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2 3

1 : Rapid Advance

2 : Medium Advance

3 : Slow Advance

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UCF2-04

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HYDRAULIC CIRCUITS

SPEED CONTROL CIRCUITMulti Speed CircuitSol. 1 ON Low speed forward

Sol. 3 ON High speed forward

Sol. 3 OFF Speed decrease

Sol. 1 OFF Stop.

Sol. 2 ON Low speed reverse

Sol. 4 ON High speed reverse

Sol. 4 OFF Speed decrease

Sol. 2 OFF Stop.

Sol. 1 Sol. 2 Sol. 3 Sol. 4

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HYDRAULIC CIRCUITS

PRESSURE CONTROL CIRCUIT2 Operating Pressure Circuit

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HYDRAULIC CIRCUITS

PRESSURE CONTROL CIRCUITLow Pressure Return Circuit

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2

Main Relief Valve

Pilot Relief Valve

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HYDRAULIC CIRCUITS

PRESSURE CONTROL CIRCUITDecompression Circuit

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HYDRAULIC CIRCUITS

UNLOADING CIRCUIT

Manual Unloading

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To Circuit

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HYDRAULIC CIRCUITS

UNLOADING CIRCUIT

Circuit using Accumulator

Detection of Pressure by Pressure Switch

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HYDRAULIC CIRCUITS

UNLOADING CIRCUIT

Circuit using Accumulator

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Detection of Pressure by Pilot Op. Relief Valve

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HYDRAULIC CIRCUITS

UNLOADING CIRCUIT ( Hi-Low Circuit )Low Pressure Operation

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HYDRAULIC CIRCUITS

UNLOADING CIRCUIT ( Hi-Low Circuit )High Pressure Operation

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HYDRAULIC CIRCUITS

SYNCHRONIZING CIRCUITSeries coupling circuit

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HYDRAULIC CIRCUITS

SYNCHRONIZING CIRCUITMechanical Coupling

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HYDRAULIC CIRCUITS

REGENERATIVE CIRCUIT - I Idle Condition

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HYDRAULIC CIRCUITS

REGENERATIVE CIRCUIT - I Regenerative Advance

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HYDRAULIC CIRCUITS

REGENERATIVE CIRCUIT - I Retraction

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HYDRAULIC CIRCUITS

SEQUENCE CIRCUITS Electrically controlled circuit

Seq. Operation Signal Movement

1 Push – ON Sol a Cyl. 1

2 LS - 2 ON Sol c Cyl. 2

3 LS - 3 ON Sol b Cyl. 1

4 LS - 1 ON Sol d Cyl. 2

Cylinder 1 Cylinder 2

a b c dLS-1 LS-2 LS-3

1 2

3 4

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HYDRAULIC CIRCUITS

SEQUENCE CIRCUITS Automatic control circuit

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Small Load

Large Load

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HYDRAULIC CIRCUITS

CLAMPING & SEQUENCING CIRCUITExtending Clamp Cylinder

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HYDRAULIC CIRCUITS

CLAMPING & SEQUENCING CIRCUITExtending Work Cylinder

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HYDRAULIC CIRCUITS

CLAMPING & SEQUENCING CIRCUITLimiting Max. Clamping Pr.

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HYDRAULIC CIRCUITS

CLAMPING & SEQUENCING CIRCUITRetracting Work Cylinder

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HYDRAULIC CIRCUITS

CLAMPING & SEQUENCING CIRCUITRetracting Clamp Cylinder

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HYDRAULIC CIRCUITS

ACCUMULATOR UNLOADING CIRCUITCharging

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HYDRAULIC CIRCUITS

ACCUMULATOR UNLOADING CIRCUITUnloading

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HYDRAULIC CIRCUITS

ACCUMULATOR UNLOADING CIRCUITSupply from Accumulator

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HYDRAULIC CIRCUITS

ACCUMULATOR CIRCUITS Power saving circuit

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Starter motor

Starting circuit for a diesel engine.

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HYDRAULIC CIRCUITS

ACCUMULATOR CIRCUITSPressure holding ( leakage compensation )

Vice

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38

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HYDRAULIC CIRCUITS

ACCUMULATOR CIRCUITSSafety Device

Safety device in a Rolling Mill

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HYDRAULIC CIRCUITS

ACCUMULATOR CIRCUITSSurge pressure reducing circuit

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40

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HYDRAULIC CIRCUITS

ACCUMULATOR CIRCUITSPump capacity reducing circuit

Low Pressure Pump

High Pressure Pump

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HYDRAULIC CIRCUITS

COLLECTION OF DATA FOR CIRCUIT DESIGN CYLINDER DETAILS

SINGLE ACTING OR DOUBLE ACTING ?

HOW MANY CYLINDERS ?

SEQUENCE OF CYLINDER MOVEMENT

( ONE AFTER OTHER OR ALMOST TOGETHER )

FUNCTION OF THE CYLINDER ( Eg., Clamping, Drilling )

MACHINE TO WHICH THESE CYLINDERS GO ( Eg., Grinding M/c. )

BORE SIZE & ROD SIZE OF THE CYLINDER

STROKE LENGTH OF THE CYLINDER

MANUAL OR SOLENOID OPERATED MOVEMENT ?

FORCE ACTING ON THE CYLINDER

SPEED OF MOVEMENT REQUIRED

SINGLE SPEED / DOUBLE SPEED / MULTI SPEED ?

LOAD REQUIREMENTS

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HYDRAULIC CIRCUITS

COLLECTION OF DATA FOR CIRCUIT DESIGN

OTHER DETAILS

LOCATION OF SYSTEM / EQUIPMENT / ACTUATOR

( Eg. Distance between Power Unit to the Actuator )

LIMITATIONS OF OPERATION ( Eg. Medium, Environment, Space )

AVAILABILITY OF POWER SOURCE & DETAILS ( Eg. AC / DC )

TYPE OF COOLING REQUIRED

SAFETY MEASURES NEEDED

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HYDRAULIC CIRCUITS

UNDERSTANDING HYDRAULIC CIRCUITS & HYDRAULIC

POWER PACKS

BEGIN WITH THE END

HYDRAULIC CYLINDERS

( LINEAR ACTUATORS )

HYDRAULIC MOTORS ( ROTARY ACTUATORS )

ACTUATORS

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HYDRAULIC CIRCUITS

A good hydraulic circuit design can be made only when the parameters influencing the feed drive are clearly understood.

TYPES OF SLIDE

• VERTICAL

• HORIZONTAL

• INCLINED

TYPES OF MACHINING

• ROUGH MACHINING

• FINE MACHINING

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HYDRAULIC CIRCUITS

FIELD OFAPPLICATION

Pressure ( Kg / Cm2 )

RANGEAVERAGE

MOBILE 70 ~ 300 150

SHIPS ( MARINE ) 40 ~ 250 90MACHINE TOOL 20 ~ 70 33

FORGES 140 ~ 250

195

INJECTION MOULDING M/c

70 ~ 210 130

INDUSTRIAL ROBOT 5 ~ 140 64

NORMAL WORKING PRESSURES FOR VARIOUS SYSTEMS

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HYDRAULIC CYLINDERS

D

d

AREA A1 AREA A2

F1

F2

PRESSURE = OUTPUT FORCE

EFFECTIVE PISTON AREA

P = F Kg

A Cm2

SELECTION OF AN ACTUATOR

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HYDRAULIC CIRCUITS


Eg. : Pressure = 50 Kg / Cm2

Force required = 4000 Kgs. ( 4 Ton )

P = F

AOr

A = F

P

= 4000 Kg = 80 Cm2

50 Kg / Cm2

A = x D2

4

( In this Example A = 80 Cm2 )

80 = x D2

4D = 100 mm

Use 100 mm Bore Cylinder

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HYDRAULIC CIRCUITS


STANDARD BORE SIZES OF CYLINDERS ( mm )

32

40

50

63

80

100

125

140

150

160

180

200

220

250

300

Q = A x V

TO CALCULATE THE FLOW “ Q”

Q = Flow in Cm3 / min. ( Divide by 1000 to get flow in LPM )

A = Area in Cm2

V = Velocity in Cm / min

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HYDRAULIC CIRCUITS

TO CALCULATE THE MOTOR POWER

MOTOR POWER (KW) = P x Q

612 x O

P = Pressure in Kg / Cm2

Q = Flow in LPM

O = Pumps Overall Efficiency ( Eg. 85 % 0.85 )

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HYDRAULIC CIRCUITS

Heat Generation in a Hydraulic SystemSOURCE : Oil Pump

H1 = Li x ( 100 - O ) x 860

100

H1 = Heat generated from the Pump ( Kcal / Hr )

Li = Pump input power ( KW )

O = Pump overall efficiency ( % )

Oil pumps exhaust a large portion of its shaft-input power to perform an effective task ( Pump output pressure, pump output flow ), while the rest turns into heat without doing any work.

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H2 = 10 x 60 x P x Q

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HYDRAULIC CIRCUITS

Heat Generation in a Hydraulic SystemSOURCE : Orifices

H2 = Heat generated ( Kcal / Hr )

P = Differential pressure across an orifice. ( Kg / Cm2 ). In case of relief valves the set pressure shall be the differential pressure.

Q = Flow through the orifice ( Lpm )

When pressurised fluid flows through throttle parts at a certain pressure, the pressure drop is converted into heat ( H2) . Especially considerable heat will be produced when the pressurised fluid is released to tank through the Relief valve.

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Load

Pr. 20 Kg/Cm2

HYDRAULIC CIRCUITS

HEAT GENERATION

40 LPM

Set

Pr. 100 Kg/Cm2

60 LPM

Pump

100 LPM

1 Kw = 860 Kcal / Hr

PQ Kw =

612

PQ X 860 Kcal / Hr

612

= 100 x 60 x 860

612

= 8431 Kcal / Hr

Normal Heat Rise

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HYDRAULIC CIRCUITS

HEAT GENERATION

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Load

Pr. 20 Kg/Cm2

40 LPM

Set

Pr. 100 Kg/Cm2

60 LPM

Pump

100 LPM

1 Kw = 860 Kcal / Hr

PQ Kw =

612

PQ X 860 Kcal / Hr

612

= 20 x 60 x 860

612

= 1686 Kcal / Hr

With Load Sensing Heat Rise

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HYDRAULIC CIRCUITS

HEAT GENERATIONLoad

Pr. 20 Kg/Cm2

40 LPM

Set

Pr. 100 Kg/Cm2

60 LPM

Pump

100 LPM

With Load Sensing

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HYDRAULIC CIRCUITS

Heat dissipation from a Hydraulic SystemSOURCES : Reservoir, Tubings, Components

H3 = K x A x ( t1 – t2 )

K = Coefficient of heat dissipation. ( 7 – 9 Kcal / Hr.c.m2 )

A = Effective Area of the Reservoir. ( m2 )

t1 = Oil Temperature ( C )

t2 = Room Temperature ( C )

The dissipated heat ( H3 ) from the surface of the reservoir -

( Kcal / Hr )

In very well ventilated circumstances we can estimate the value of the Heat transfer coefficient “ K” around 15 Kcal / Hr. C.m2

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HYDRAULIC CIRCUITS

Heat dissipation from a Hydraulic System

H3 = K x A x ( t1 – t2 )

A = Effective Area of the Reservoir. ( m2 )

( Kcal / Hr )

L = 1000 B = 700

H = 450

A = L x B x H

= 2 [ L x H ] + 2 [ B x H ] + [ L x B ]

= 2 [ 1000 x 450 ] + 2 [ 700 x 450 ] + [ 1000 x 700 ]

= 2 [ 1 x 0.45 ] + 2 [ 0.7 x 0.45 ] + [ 1 x 0.7 ]

= 0.9 + 0.63 + 0.7

= 2.23 m2

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HYDRAULIC CIRCUITS

Oil Temperature

The oil temperature accelerates the heat transfer as it rises, and reaches an equilibrium state of thermal relationship H1 + H2 = H3

The equilibrium oil temperature -t1 = H1 + H2 + t2

KA

At Equilibrium Condition

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HYDRAULIC CIRCUITS

Oil Temperature

When the temperature is risingThe thermal relationship H1 + H2 > H3 then the oil temperature “t” at a time “ T” is given by –

- KA T

t = H1 + H2 C + t2

KA 1 – e

C = Heat capacity of the Reservoir ( Cm3 )C = v x r x S Wherev = Reservoir capacity. ( cm3 )

r = Specific gravity of oil ( 0.86 x 10 –3 Kgf / Cm3 )

S = Specific heat of oil ( 0.45 Kcal / Kg C )T = Time ( Hr. )

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MODULAR VALVES

Features

STACKABLE UNITS – MAINTENANCE AND SYSTEM CHECK UP MADE EASY.

INSTALLATION AND MOUNTING SPACE MINIMISED.

PIPING ELIMINATED - OIL LEAKS, VIBRATION AND NOISE CAUSED BY PIPING MINIMISED.

NO SPECIAL SKILL REQUIRED FOR ASSEMBLY AND ANY ADDITION OR ALTERATION OF THE HYDRAULIC CIRCUIT CAN BE MADE QUICKLY AND EASILY.

HYDRAULIC CIRCUITS

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HYDRAULIC CIRCUITS

S ol en oi d O p e ra te d D ire c ti on a l V a lv e

P T B A P T B A

Caution in the Selection of Valves and Circuit designing

Reducing Modular valve

( for “B” line )

Pilot Operated Check Modular valve (for “A” & “B” Lines)

Solenoid Operated Directional valve

( CORRECT )( INCORRECT )

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HYDRAULIC CIRCUITS



Throttle and Check Modular valve (for “A” & “B” Lines Meter-out )

Pilot Operated Check Modular valve (for “A” & “B” Lines)

S ol en oi d O p e ra te d D ire c ti on a l V a lv e

P T B A P T B A


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HYDRAULIC CIRCUITS



Throttle and Check Modular valve (for “A” & “B” Lines Meter-out )


Brake Modular valve

S o l e n oi d O p e ra te d D irec t io n a l V a lv e

P T B A P T B A

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HYDRAULIC CIRCUITS

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Hyd. Power unit for Multi Spindle Drilling M/c.

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Logic Valves

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HYDRAULIC CIRCUITS

Logic Valves - Features

MULTIFUNCTION PERFORMANCE IN TERMS OF DIRECTION, FLOW AND PRESSURE CAN BE OBTAINED BY COMBINING ELEMENTS AND COVERS.

POPPET TYPE ELEMENTS VIRTUALLY ELIMINATE INTERNAL LEAKAGE AND HYDRAULIC LOCKING. BECAUSE THERE ARE NO OVERLAPS, RESPONSE TIMES ARE VERY HIGH, PERMITTING HIGH-SPEED SHIFTING.

FOR HIGH PRESSURE, LARGE CAPACITY SYSTEMS, OPTIMUM PERFORMANCE IS ACHIEVED WITH LOW PRESSURE LOSSES.

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HYDRAULIC CIRCUITS


SINCE THE LOGIC VALVES ARE DIRECTLY INCORPORATED IN CAVITIES PROVIDED IN BLOCKS, THE SYSTEM IS FREE FROM PROBLEMS RELATED TO PIPING SUCH AS OIL LEAKAGE, VIBRATION AND NOISE, AND HIGHER RELIABILITY IS ACHIEVED.

MULTI-FUNCTION LOGIC VALVES PERMIT COMPACT INTEGRATED HYDRAULIC SYSTEMS WHICH REDUCE MANIFOLD DIMENSIONS AND MASS AND ACHIEVE LOWER COST CONVENTIONAL TYPES.

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HYDRAULIC CIRCUITS


A

XB

A

A

XB

A

X YB

F un c tio n G r ap hic S ym bo ls W ork ing ar ea ra tio (A : A )A B

F ea ture s

P o pp e t s hap e

N o leak ag e b etw een po rt A and B

F low A to B and B to A a re p ossible

Resp on se tim e and shock ca n be adju sted by o rif ice se lec tio n.

P o pp e t s hap e W ith cu shion ( LD ---S - 1/2/3 ) : f low con tr ol.

N o leak ag e b etw een po rt A and B

F lo w A to B o nly is p ossible .

Resp on se tim e and shock ca n be adju sted by o rif ice se lec tio n.

R em o te and un lo ading contr ol is pos sible w ith ven t c ir cu it (LB --).

T w o or th ree p re ssu re co ntro ls a re p ossib le in com bina tio n of soleno id op er a ted dir ec tio nal va lve and pilot re lie f va lve (L B S--).

(2 : 1 )

(2 4 : 1)

D ire c tio n

D ire c tio n and F lo w

R e lie f

W ith ou t cu shio n (L D /LD S --): high- sp eed s hiftW ith cu shion (LD /L D S---S ) : S hoc kle ss s hift/

F unc t ion s, w o r k ing a r e a r at ios a nd fe a t ur e s

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Selection of accumulator capacity.

There are many chances to use accumulator as a source of energy.

To select the capacity of accumulator, We must know: (1) Required oil discharge amount: liters. (2) Max. operating pressure: P3 Kgf / Cm2.

(3) Min. operating pressure : P2 Kgf / Cm2.

(4) Gas charge pressure : P1 Kgf / Cm2.

P1 P2 (0.85 ~ 0.9)

(5) Charging time, discharge timeEspecially for discharge timeIncase T > 1 min: use isothermal change. T < 1 min: use adiabatic change.From these required specification we can calculate the

required vol. of accumulator.

HYDRAULIC CIRCUITS

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HYDRAULIC CIRCUITS

CASE STUDY - I : CNC Drilling Machine

Data Available :

1. CYLINDER SPECIFICATION :

Clamping - 125 x 50 x 20 Stroke

Drilling - 63 x 35 x 100 Stroke

2. LOAD OR FORCE ACTING ON THE CYLINDER

Clamping - 400 Kgf

Drilling - 250 Kgf

3. SPEED OF ACTUATORS

Clamping - 1.5 M / min.

Drilling - 0.1 M / min.

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HYDRAULIC CIRCUITS

CASE STUDY – I : CNC Drilling Machine1 ) Pressure required for clamping “ P1 ”

P1 = F

A

= 400

122.7

A = x D2

4

A = x 12.5 x 12.5

4 = 122.7 Cm2

= 3.3 Kg / Cm2

2 ) Pressure required for drilling “ P2 ”

P2 = F

A

= 250

31.2

A = x D2

4

A = x 6.3 x 6.3

4 = 31.2 Cm2

= 8 Kg / Cm2

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HYDRAULIC CIRCUITS

CASE STUDY – I : CNC Drilling Machine3 ) Flow required for clamping “ Q1 ”

4 ) Flow required for drilling “ Q2 ”

A = x D2

4

A = x 12.5 x 12.5

4 = 122.7 Cm2

Q 1 = A x V

= 122.7 x 1.5 x 100 Cm3 / min

= 18405 Cm3 / min

= 18.4 LPM

A = x D2

4

A = x 6.3 x 6.3

4 = 31.2 Cm2

Q 2 = A x V

= 31.2 x 0.1 x 100 Cm3 / min

= 312 Cm3 / min

= 0.31 LPM

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HYDRAULIC CIRCUITS

CASE STUDY – I : CNC Drilling Machine5 ) Electric Motor Power

MOTOR POWER (KW) = P x Q

612 x O

8 x 18.4 = 0.28 KW

612 x 0.85 (0.38 HP)1 hp = 0.746 KW

6 ) Tank Size - ( General Thumb Rule )

For Vane & Gear Pumps = 4 ~ 5 times of System Flow

For Piston Pumps = 2 ~ 3 times of System Flow

7 ) Maximum Pressure to be considered = 8 Kg / Cm2

Maximum Flow to be considered = 18.4 LPM

Electric Motor Power = 0.38 say 0.5 HP

Tank Capacity = 18.4 x 4 = 73.6 say 75 ltrs

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HYDRAULIC CIRCUITS

SEQUENCE CIRCUITS

Circuit using Sequence Valve

Clamp

Drill

14

23

1 - CLAMPING 2 - DRILLING 3 - DRILL RETURN 4 - DE CLAMP

Sequence of Operation

1

2

3

4

Sequence of Flow1 2 3 4

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SEQUENCE VALVE

SEQUENCE VALVE

1 HYDRAULIC CIRCUITS Welcome to the Session on :.

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Transcript of 1 HYDRAULIC CIRCUITS Welcome to the Session on :.