液压夹具设计手册.ppt

1、液压夹具设计手册,思诚机电,2,Good Fixture Design,Good fixtures position, clamp and support workpieces in the most effective way possible,3,Fixture design, workpiece Example 1,4,Fixture design, process,5,Datum,Fixture design, workpiece datums,6,Fixture design, supporting,7,Fixture design, positioning,8,Fixture de

2、sign, clamping,9,Fixture design, additional support and clamping,10,Fixture, positioning, supporting and clamping,11,Fixture design, workpiece, Example 2,12,Fixture design, process,13,Fixture design, supporting,14,Fixture design, clamping,X,X,15,Fixture design, clamping,16,Fixture design, positionin

3、g and clamping,17,Fixture design, positioning, supporting & clamping,18,Friction clamping,If clamping using friction only it must be remembered that the coefficient of friction () is normally calculated at 0.1,Total clamping force = F,19,Friction clamping,If clamping using friction only it must be r

4、emembered that the coefficient of friction () is normally calculated at 0.1 This can be improved on soft materials (eg. Al) if the clamping piston has enough force to penetrate the workpiece,20,Fixture design,DEFINITION OF A CLAMPING FORCE The force acting on a workpiece to be clamped, is large enou

5、gh to hold the workpiece firmly in its given position relative to the cutting tool, against the action of the machining forces,21,Fixture design,CLAMPING FORCES Mechanical low cost, relatively low forces Pneumatic higher cost, relatively low forces, large components Hydraulic higher initial cost, hi

6、gh forces, reliable, small components,22,Mechanical Forces,Maximum clamping force using standard wrench,Clamping force (kN),Clamping force with extension pieces as shown, 500N torque, = 0.1,23,Standard clamping strap M20 thread Max. recommended torque 223Nm Max. clamping force 28kN,Hydraulic swing c

7、lamp 6951F-11-21 (page 63, metric catalogue) 22 rod, 76mm long arm Max. oil pressure 23 MPa Clamping force 7.3kN,Force comparison,24,Force comparison,Standard clamping strap M20 thread Max. recommended torque 223Nm Max. clamping force 28kN,Hydraulic swing clamp 6951F-11-21 (page 63, metric catalogue

8、) 22 rod, clamping strap Max. oil pressure 35 MPa Clamping force 13.7kN,25,Standard clamping strap M24 thread Max. recommended torque 383Nm Max. clamping force 40kN,Hydraulic swing clamp 6951FN-33-21 (page 71, metric catalogue) 38 rod, clamping strap Max. oil pressure 35 MPa Clamping force 35kN,Forc

9、e comparison,26,Standard clamping strap M24 thread Max. recommended torque 383Nm Max. clamping force 40kN,Hollow piston cylinder 6921-100 x10 (page 26, metric catalogue) M24 thread Max. oil pressure 400 bar Clamping force 101kN,Force comparison,27,Mechanical or Hydraulic ?,28,Mechanical or Hydraulic

10、 ?,29,Force diagram,30,Component & Fixture design,SENSIBLE USE OF FORCE Sensible introduction of positioning, clamping and supporting forces will enhance the quality of a workpiece,31,Oil supply to fixtures,2 basic methods through pipes through gun drilled channels Method depends on cost target comp

11、lexity of fixture products being used,32,Oil supply to fixtures, cost comparison,A:Through pipes using flange type clamps B:Through pipes using threaded type clamps C:Through gun drilled channels & manifold mounted type clamps D:Through gun drilled channels & threaded body type clamps,33,Oil supply

12、to fixtures, cost comparison,A: Through pipes using flange type clamps Relatively easy to manufacture Fittings weakest part of system Chip traps Control fixture COST 100%,34,Oil supply to fixtures, cost comparison,B: Through pipes using threaded type clamps Less swarf traps Reduces machining area Fi

13、ttings weakest part of system COST ?% against control fixture,35,Oil supply to fixtures, cost comparison,C: Through gun drilled channels & manifold mounted type clamps Maximum component density Minimum swarf traps COST ?% against control fixture,36,Oil supply to fixtures, cost comparison,D: Through

14、gun drilled channels & threaded body type clamps Maximum component density Minimum swarf traps COST ?% against control fixture,37,Oil supply to fixtures, cost comparison,C: Through gun drilled channels & manifold mounted type clamps 98%,Hydraulic circuit design,39,Circuit design,40,Cam Cover fixture

15、 example,41,Circuit design,42,http:/www.ec-,43,Barrel fixture example,44,Circuit design,45,Getting the oil to the fixture,47,Rotary & Rotary Valve Couplings,48,Rotary Couplings,Used when free passage of oil is required to be distributed on rotary table arrangements Standard versions of single, twin,

16、 four and six passages with/without leakage port Maximum operating pressure 250/500 bar When specifying include data on rotation speed, pressure, temperature, media and cycle time Special designs available on request,49,Twin passage rotary coupling,Use on rotary table with two single acting cylinder

17、s,50,Four passage rotary coupling,Use on rotary table with 4 single acting or 2 double acting cylinders,51,Six passage rotary coupling,Use on rotary tables with combination of up to 6 oil feeds ie. 6 s/a, 3 d/a, 2 d/a & 2 s/a cylinders,52,Rotary Coupling circuit,Single acting circuit,Double acting c

18、ircuit,53,Application example,54,Rotary Valve Couplings,Used on rotary table arrangements when loading/unloading of stations is required whilst maintaining clamping pressure on remaining stations Versions include 5,6,7,8,9 &10 stations. Applications requiring 2, 3 or 4 stations use 6 & 8 stations wi

19、th unused ports plugged. Special designs available Up to 200 bar an accumulator is recommended, above 200 bar it is essential due to internal leakage within the oil return cavity of the unit,55,Rotary valve coupling function,56,Rotary Valve Coupling circuit,Single acting,Double acting,57,Application

20、 example,58,Coupling units,Quick disconnect couplings One-hand operation quick disconnect Coupling units Automatic coupling systems Threaded coupling elements,59,Quick Disconnect Couplings Max operating pressure 500 bar One hand operation Always use dustcaps,Coupling units,60,Coupling Units Single o

21、r double acting Integral accumulator and pressure gauge Multi-coupler units available,Coupling units & accumulators,61,Coupling Systems Always use accumulators on static systems 10 temperature difference relates to 10 bar pressure difference,Coupling units & accumulators,62,Threaded coupling element

22、s,Breathing,64,What is breathing?,Breathing is the action of single acting cylinders during the spring return part of the component cycle,65,Why breathing has to be made,Excess pressure or vacuum in the spring area changes the spring forces which leads to malfunction Formation of condensation water

23、promotes rust formation and can lead to a complete failure of the elements Leakage of hydraulic seals must drain off to exterior without pressure otherwise there will be malfunctions Dust and chips are retained by sintered metal air filters Liquids can be drawn through the sintered metal filter, thu

24、s the breathing spring area is reduced, a higher excess pressure or vacuum is caused and the function is impaired,66,What is breathing?,What happens during breathing,67,Precautions,Cover Clamping elements without breather ports can be covered. Due to high coolant pressure and flow this is not always

25、 successful Consider using double acting elements wherever possible,68,Precautions,Breather hose Connection of a breather hose is approved if the outlet is sited at a point where no liquid can penetrate Ensure no fluid traps in hose,69,Precautions,Closed breather system Spring area is increased by connection of additional closed area. Electrical die cast boxes are ideal Volume of additional area should be 10 times the stroke volume of all connected components,70,System blee