Welcome to the Session on HYDRAULIC CIRCUITS 1

Welcome to the Session on : HYDRAULIC CIRCUITS 1

HYDRAULIC CIRCUITS MOTOR & PUMP PRESSURE CONTROL VALVES HYDRAULIC ACTUATORS ACCESSORIES POWER UNIT FLOW CONTROL VALVES DIRECTION CONTROL VALVES 2

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. 3

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Variable displacement pump circuit M 4

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Meter – in Circuit M 5

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Meter – out Circuit M 6

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Bleed – off Circuit M 7

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Deceleration Circuit M 8

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Feed speed varying circuit M 9

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Multi Speed Circuit Q 1 : High Flow Q 1 Q 2 : Low Flow Q 2 M 10

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Multi Speed Circuit 1 : Rapid Advance 2 : Medium Advance 1 2 UCF 2 -04 3 : Slow Advance 3 M 11

HYDRAULIC CIRCUITS SPEED CONTROL CIRCUIT Multi Speed Circuit Sol. 1 ON Low speed forward Sol. 3 ON High speed forward Sol. 3 OFF Speed decrease Sol. 1 OFF Stop. Sol. 1 Sol. 2 Sol. 3 Sol. 4 Sol. 2 ON Low speed reverse Sol. 4 ON High speed reverse M Sol. 4 OFF Speed decrease Sol. 2 OFF Stop. 12

HYDRAULIC CIRCUITS PRESSURE CONTROL CIRCUIT 2 Operating Pressure Circuit 1 2 13

HYDRAULIC CIRCUITS PRESSURE CONTROL CIRCUIT Low Pressure Return Circuit 2 Pilot Relief Valve Main Relief Valve 1 14

HYDRAULIC CIRCUITS PRESSURE CONTROL CIRCUIT Decompression Circuit M 15

HYDRAULIC CIRCUITS UNLOADING CIRCUIT Manual Unloading To Circuit M 16

HYDRAULIC CIRCUITS UNLOADING CIRCUIT Circuit using Accumulator Detection of Pressure by Pressure Switch 17

HYDRAULIC CIRCUITS UNLOADING CIRCUIT Circuit using Accumulator Detection of Pressure by Pilot Op. Relief Valve M 18

HYDRAULIC CIRCUITS UNLOADING CIRCUIT ( Hi-Low Circuit ) Low Pressure Operation 19

HYDRAULIC CIRCUITS UNLOADING CIRCUIT ( Hi-Low Circuit ) High Pressure Operation 20

HYDRAULIC CIRCUITS SYNCHRONIZING CIRCUIT Series coupling circuit M 21

HYDRAULIC CIRCUITS SYNCHRONIZING CIRCUIT Mechanical Coupling M 22

HYDRAULIC CIRCUITS REGENERATIVE CIRCUIT - I Idle Condition 23

HYDRAULIC CIRCUITS REGENERATIVE CIRCUIT - I Regenerative Advance 24

HYDRAULIC CIRCUITS REGENERATIVE CIRCUIT - I Retraction 25

HYDRAULIC CIRCUITS SEQUENCE CIRCUITS Electrically controlled circuit 1 Cylinder 1 3 a 2 Cylinder 2 LS-1 b 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 4 LS-2 c LS-3 d M 26

HYDRAULIC CIRCUITS SEQUENCE CIRCUITS Automatic control circuit Small Load Large Load M 27

HYDRAULIC CIRCUITS CLAMPING & SEQUENCING CIRCUIT Extending Clamp Cylinder 28

HYDRAULIC CIRCUITS CLAMPING & SEQUENCING CIRCUIT Extending Work Cylinder 29

HYDRAULIC CIRCUITS CLAMPING & SEQUENCING CIRCUIT Limiting Max. Clamping Pr. 30

HYDRAULIC CIRCUITS CLAMPING & SEQUENCING CIRCUIT Retracting Work Cylinder 31

HYDRAULIC CIRCUITS CLAMPING & SEQUENCING CIRCUIT Retracting Clamp Cylinder 32

HYDRAULIC CIRCUITS ACCUMULATOR UNLOADING CIRCUIT Charging 33

HYDRAULIC CIRCUITS ACCUMULATOR UNLOADING CIRCUIT Unloading 34

HYDRAULIC CIRCUITS ACCUMULATOR UNLOADING CIRCUIT Supply from Accumulator 35

HYDRAULIC CIRCUITS ACCUMULATOR CIRCUITS Power saving circuit Starter motor Starting circuit for a diesel engine. M 36

HYDRAULIC CIRCUITS ACCUMULATOR CIRCUITS Pressure holding ( leakage compensation ) Vice M 37

HYDRAULIC CIRCUITS ACCUMULATOR CIRCUITS Safety Device Safety device in a Rolling Mill M 38

HYDRAULIC CIRCUITS ACCUMULATOR CIRCUITS Surge pressure reducing circuit M 39

HYDRAULIC CIRCUITS ACCUMULATOR CIRCUITS Low Pressure Pump capacity reducing circuit M High Pressure Pump 40

HYDRAULIC CIRCUITS COLLECTION OF DATA FOR CIRCUIT DESIGN Ø 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 41

HYDRAULIC CIRCUITS COLLECTION OF DATA FOR CIRCUIT DESIGN Ø 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 42

HYDRAULIC CIRCUITS UNDERSTANDING HYDRAULIC CIRCUITS & HYDRAULIC POWER PACKS BEGIN WITH THE END ACTUATORS HYDRAULIC CYLINDERS ( LINEAR ACTUATORS ) HYDRAULIC MOTORS ( ROTARY ACTUATORS ) 43

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 44

HYDRAULIC CIRCUITS NORMAL WORKING PRESSURES FOR VARIOUS SYSTEMS FIELD OF APPLICATION Pressure ( Kg / Cm 2 ) RANGE AVERAGE MOBILE 70 ~ 300 150 SHIPS ( MARINE ) MACHINE TOOL 40 ~ 250 90 20 ~ 70 33 FORGES 140 ~ 250 195 INJECTION MOULDING M/c 70 ~ 210 130 INDUSTRIAL ROBOT 5 ~ 140 64 45

HYDRAULIC CYLINDERS SELECTION OF AN ACTUATOR F 1 d D AREA A 1 F 2 PRESSURE = AREA A 2 OUTPUT FORCE EFFECTIVE PISTON AREA P= F Kg A Cm 2 46

HYDRAULIC CIRCUITS SELECTION OF AN ACTUATOR Eg. : Pressure = 50 Kg / Cm 2 Force required = 4000 Kgs. ( 4 Ton ) P= F Or A A= F P = 4000 Kg 50 A = x D 2 = 80 Cm 2 Kg / Cm 2 ( In this Example A = 80 Cm 2 ) 4 80 = x D 2 4 D = 100 mm Use 100 mm Bore Cylinder 47

HYDRAULIC CIRCUITS SELECTION OF AN ACTUATOR STANDARD BORE SIZES OF CYLINDERS ( mm ) 32 40 50 63 80 100 125 140 150 160 180 200 220 250 300 TO CALCULATE THE FLOW “ Q” Q=Ax. V Q = Flow in Cm 3 / min. ( Divide by 1000 to get flow in LPM ) A = Area in Cm 2 V = Velocity in Cm / min 48

HYDRAULIC CIRCUITS TO CALCULATE THE MOTOR POWER (KW) = Px. Q 612 x O P = Pressure in Kg / Cm 2 Q = Flow in LPM O = Pumps Overall Efficiency ( Eg. 85 % 0. 85 ) 49

HYDRAULIC CIRCUITS Heat Generation in a Hydraulic System SOURCE : Oil Pump 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. H 1 = Li x ( 100 - O ) x 860 100 H 1 = Heat generated from the Pump ( Kcal / Hr ) Li = Pump input power ( KW ) O = Pump overall efficiency ( % ) 50

HYDRAULIC CIRCUITS Heat Generation in a Hydraulic System SOURCE : Orifices When pressurised fluid flows through throttle parts at a certain pressure, the pressure drop is converted into heat ( H 2). Especially considerable heat will be produced when the pressurised fluid is released to tank through the Relief valve. H 2 = 10 x 60 x P x Q 427 H 2 = Heat generated ( Kcal / Hr ) P = Differential pressure across an orifice. ( Kg / Cm 2 ). In case of relief valves the set pressure shall be the differential pressure. Q = Flow through the orifice ( Lpm ) 51

HYDRAULIC CIRCUITS HEAT GENERATION Normal Heat Rise Load Pr. 20 Kg/Cm 2 1 Kw = 860 Kcal / Hr 40 LPM PQ Kw = Set 612 Pr. 100 Kg/Cm 2 60 LPM PQ X 860 Kcal / Hr 612 = 100 x 60 x 860 612 = 8431 Kcal / Hr Pump 100 LPM M 52

HYDRAULIC CIRCUITS HEAT GENERATION With Load Sensing Heat Rise Load Pr. 20 Kg/Cm 2 1 Kw = 860 Kcal / Hr 40 LPM PQ Kw = 612 Set PQ X 860 Kcal / Hr Pr. 100 Kg/Cm 2 612 = 20 x 60 x 860 60 LPM 612 = 1686 Kcal / Hr Pump 100 LPM M 53

HYDRAULIC CIRCUITS HEAT GENERATION With Load Sensing Load Pr. 20 Kg/Cm 2 40 LPM Set Pr. 100 Kg/Cm 2 60 LPM M Pump 100 LPM 54

HYDRAULIC CIRCUITS Heat dissipation from a Hydraulic System SOURCES : Reservoir, Tubings, Components The dissipated heat ( H 3 ) from the surface of the reservoir - H 3 = K x A x ( t 1 – t 2 ) ( Kcal / Hr ) K = Coefficient of heat dissipation. ( 7 – 9 Kcal / Hr. c. m 2 ) A = Effective Area of the Reservoir. ( m 2 ) t 1 = Oil Temperature ( C ) t 2 = Room Temperature ( C ) In very well ventilated circumstances we can estimate the value of the Heat transfer coefficient “ K” around 15 Kcal / Hr. C. m 2 55

HYDRAULIC CIRCUITS Heat dissipation from a Hydraulic System A = Effective Area of the Reservoir. ( m 2 ) H L = 1000 A = = = = 450 B = 700 L 2 2 2 x B x H [Lx. H] + 2[Bx. H] + [Lx. B] [ 1000 x 450 ] + 2 [ 700 x 450 ] + [ 1000 x 700 ] [ 1 x 0. 45 ] + 2 [ 0. 7 x 0. 45 ] + [ 1 x 0. 7 ] 0. 9 + 0. 63 + 0. 7 2. 23 m 2 H 3 = K x A x ( t 1 – t 2 ) ( Kcal / Hr ) 56

HYDRAULIC CIRCUITS Oil Temperature At Equilibrium Condition The oil temperature accelerates the heat transfer as it rises, and reaches an equilibrium state of thermal relationship H 1 + H 2 = H 3 The equilibrium oil temperature - t 1 = H 1 + H 2 + t 2 KA 57

HYDRAULIC CIRCUITS Oil Temperature When the temperature is rising The thermal relationship H 1 + H 2 > H 3 then the oil temperature “t” at a time “ T” is given by – t = C = Where v = r = S = T = H 1 + H 2 KA - KA T C 1 – e + t 2 Heat capacity of the Reservoir ( Cm 3 ) v xrx. S Reservoir capacity. ( cm 3 ) Specific gravity of oil ( 0. 86 x 10 – 3 Kgf / Cm 3 ) Specific heat of oil ( 0. 45 Kcal / Kg C ) Time ( Hr. ) 58

HYDRAULIC CIRCUITS 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. 59

HYDRAULIC CIRCUITS Caution in the Selection of Valves and Circuit designing ( INCORRECT ) ( CORRECT ) Solenoid Operated Directional valve Pilot Operated Check Modular valve (for “A” & “B” Lines) Reducing Modular valve ( for “B” line ) 60

HYDRAULIC CIRCUITS Caution in the Selection of Valves and Circuit designing ( INCORRECT ) ( CORRECT ) Solenoid Operated Directional valve Throttle and Check Modular valve (for “A” & “B” Lines Meter-out ) Pilot Operated Check Modular valve (for “A” & “B” Lines) 61

HYDRAULIC CIRCUITS Caution in the Selection of Valves and Circuit designing ( INCORRECT ) ( CORRECT ) Solenoid Operated Directional valve Throttle and Check Modular valve (for “A” & “B” Lines Meter-out ) Brake Modular valve 62

HYDRAULIC CIRCUITS 63

HYDRAULIC CIRCUITS 64

HYDRAULIC CIRCUITS Hyd. Power unit for Multi Spindle Drilling M/c. 65

HYDRAULIC CIRCUITS Logic Valves 66

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. 67

HYDRAULIC CIRCUITS Logic Valves - Features 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. 68

HYDRAULIC CIRCUITS Logic Valves - Features 69

HYDRAULIC CIRCUITS 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: P 3 Kgf / Cm 2. (3) Min. operating pressure : P 2 Kgf / Cm 2. (4) Gas charge pressure : P 1 Kgf / Cm 2. P 1 P 2 (0. 85 ~ 0. 9) (5) Charging time, discharge time Especially for discharge time Incase T > 1 min: use isothermal change. T < 1 min: use adiabatic change. From these required specification we can calculate the required vol. of accumulator. 70

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. 71

HYDRAULIC CIRCUITS CASE STUDY – I : CNC Drilling Machine 1 ) Pressure required for clamping “ P 1 ” P 1 = F = 400 4 122. 7 A = 3. 3 Kg / A = x 12. 5 Cm 2 2 ) Pressure required for drilling “ P 2 ” P 2 = F A = 250 31. 2 = 8 Kg / A = x D 2 Cm 2 4 = 122. 7 Cm 2 A = x D 2 4 A = x 6. 3 4 = 31. 2 Cm 2 72

HYDRAULIC CIRCUITS CASE STUDY – I : CNC Drilling Machine 3 ) Flow required for clamping “ Q 1 ” Q 1= A x V 4 = 122. 7 x 1. 5 x 100 Cm 3 / min = 122. 7 Cm 2 = 18. 4 LPM 4 ) Flow required for drilling “ Q 2 ” Q 2= A x V = 312 Cm 3 / min = 0. 31 LPM A = x 12. 5 4 = 18405 Cm 3 / min = 31. 2 x 0. 1 x 100 A = x D 2 4 Cm 3 / min A = x 6. 3 4 = 31. 2 Cm 2 73

HYDRAULIC CIRCUITS CASE STUDY – I : CNC Drilling Machine 5 ) Electric Motor Power MOTOR POWER (KW) = Px. Q 8 x 18. 4 612 x O 612 x 0. 85 = 0. 28 KW (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 / Cm 2 Maximum Flow to be considered = 18. 4 LPM Electric Motor Power = 0. 38 say 0. 5 HP Tank Capacity = 73. 6 say 75 ltrs = 18. 4 x 4 74

HYDRAULIC CIRCUITS SEQUENCE CIRCUITS Circuit using Sequence Valve 4 1 3 2 Clamp Drill 1 3 SEQUENCE VALVE 2 4 SEQUENCE VALVE Sequence of Flow Sequence of Operation 1234 - CLAMPING DRILL RETURN DE CLAMP 1 2 3 4 M 75

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