专业夹具设计全英文介绍.ppt

专业夹具设计全英文介绍思诚机电2Good Fixture DesignGood fixtures position, clamp and support workpieces in the most effective way possible3Fixture design, workpiece Example 14Fixture design, process5DatumFixture design, workpiece datums6Fixture design, supporting7Fixture design, positioning8Fixture design, clamping9Fixture design, additional support and clamping10Fixture, positioning, supporting and clamping11Fixture design, workpiece, Example 212Fixture design, process13Fixture design, supporting14Fixture design, clampingXX15Fixture design, clampingDatum16Fixture design, positioning and clamping17Fixture design, positioning, supporting & clamping18Friction clampingIf clamping using friction only it must be remembered that the coefficient of friction (µ) is normally calculated at 0.1Clamping force FReaction forceTotal clamping force= F x µClamping force FReaction forceTotal clamping force= FClamping force F @2-30 from horizontalPreferable19Friction clampingIf clamping using friction only it must be remembered that the coefficient of friction (µ) is normally calculated at 0.1This can be improved on soft materials (eg. Al) if the clamping piston has enough force to penetrate the workpiece20Fixture designDEFINITION OF A CLAMPING FORCEThe force acting on a workpiece to be clamped, is large enough to hold the workpiece firmly in its given position relative to the cutting tool, against the action of the machining forces21Fixture designCLAMPING FORCESnMechanicalnlow cost, relatively low forcesnPneumaticnhigher cost, relatively low forces, large componentsnHydraulicnhigher initial cost, high forces, reliable, small components 22Mechanical ForcesMaximum clamping forceusing standard wrenchClamping force (kN)Clamping force with extension piecesas shown, 500N torque, µ = 0.123Standard clamping strapM20 threadMax. recommended torque 223NmMax. clamping force 28kN Hydraulic swing clamp 6951F-11-21(page 63, metric catalogue)Ø22 rod, 76mm long armMax. oil pressure 23 MPaClamping force 7.3kN Force comparison24Force comparisonStandard clamping strapM20 threadMax. recommended torque 223NmMax. clamping force 28kN Hydraulic swing clamp 6951F-11-21(page 63, metric catalogue)Ø22 rod, clamping strapMax. oil pressure 35 MPaClamping force 13.7kN 25Standard clamping strapM24 threadMax. recommended torque 383NmMax. clamping force 40kN Hydraulic swing clamp 6951FN-33-21(page 71, metric catalogue) Ø38 rod, clamping strapMax. oil pressure 35 MPaClamping force 35kN Force comparison26Standard clamping strapM24 threadMax. recommended torque 383NmMax. clamping force 40kN Hollow piston cylinder 6921-100x10(page 26, metric catalogue) M24 threadMax. oil pressure 400 barClamping force 101kN Force comparison27Mechanical or Hydraulic ?28Mechanical or Hydraulic ?50 MPaSequence Valve 47-0440-02 (J-3)Set at 30 MPaCartridge Mount Cylinder (x8)42-1010-04 (page F-12)2.5 kN each @ 50MPaThreaded Cylinder42-0010-06 (page F-4)3.4 kN @ 30 MPa5.7 kN @ 50 MPa29Force diagram30 MPa50 MPaSequence valve opensWorkpiecesMovement of cylinderOil pressure30Component & Fixture designSENSIBLE USE OF FORCESensible introduction of positioning, clamping and supporting forces will enhance the quality of a workpiece31Oil supply to fixturesn2 basic methodsnthrough pipesnthrough gun drilled channelsnMethod depends onncost targetncomplexity of fixturenproducts being used32Oil supply to fixtures, cost comparisonnA:Through pipes using flange type clampsnB:Through pipes using threaded type clampsnC:Through gun drilled channels & manifold mounted type clampsnD:Through gun drilled channels & threaded body type clamps33Oil supply to fixtures, cost comparisonA: Through pipes usingflange type clampsnRelatively easy to manufacturenFittings weakest part of systemnChip trapsControl fixtureCOST 100%34Oil supply to fixtures, cost comparisonB: Through pipes usingthreaded type clampsnLess swarf traps nReduces machining areanFittings weakest part of systemCOST ?%against control fixture35Oil supply to fixtures, cost comparisonC: Through gun drilled channels & manifold mounted type clampsnMaximum component density nMinimum swarf trapsCOST ?%against control fixture36Oil supply to fixtures, cost comparisonD: Through gun drilled channels & threaded body type clampsnMaximum component density nMinimum swarf trapsCOST ?%against control fixture37Oil supply to fixtures, cost comparisonC: Through gun drilled channels & manifold mounted type clamps98%B:130%D:104%A:100%Hydraulic circuit design39Circuit design40Cam Cover fixture example41Circuit design42http://www.ec- fixture example44Circuit design45Getting the oil to the fixture47Rotary & Rotary Valve Couplings48Rotary CouplingsnUsed when free passage of oil is required to be distributed on rotary table arrangementsnStandard versions of single, twin, four and six passages with/without leakage portnMaximum operating pressure 250/500 barnWhen specifying include data on rotation speed, pressure, temperature, media and cycle timenSpecial designs available on request49Twin passage rotary couplingnUse on rotary table with two single acting cylinders50Four passage rotary couplingnUse on rotary table with 4 single acting or 2 double acting cylinders51Six passage rotary couplingnUse 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52Rotary Coupling circuitSingle acting circuitDouble acting circuit53Application example54Rotary Valve CouplingsnUsed on rotary table arrangements when loading/unloading of stations is required whilst maintaining clamping pressure on remaining stationsnVersions include 5,6,7,8,9 &10 stations.nApplications requiring 2, 3 or 4 stations use 6 & 8 stations with unused ports plugged.nSpecial designs availablenUp 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55Rotary valve coupling functionLoad stationUnload stationRotary couplingWork stationClamping cylinder56Rotary Valve Coupling circuitSingleactingDoubleacting57Application example58Coupling unitsnQuick disconnect couplingsnOne-hand operation quick disconnectnCoupling unitsnAutomatic coupling systemsnThreaded coupling elements 59Quick DisconnectCouplingsnMax operating pressure 500 barnOne hand operationnAlways use dustcapsCoupling units60Coupling UnitsnSingle or double actingnIntegral accumulator and pressure gaugenMulti-coupler units availableCoupling units & accumulators61Coupling SystemsnAlways use accumulators on static systemsn10 temperature difference relates to 10 bar pressure differenceCoupling units & accumulators62Threaded coupling elementsBreathing64What is breathing?Breathing is the action of single acting cylinders during the spring return part of the component cycle65Why breathing has to be madenExcess pressure or vacuum in the spring area changes the spring forces which leads to malfunctionnFormation of condensation water promotes rust formation and can lead to a complete failure of the elementsnLeakage of hydraulic seals must drain off to exterior without pressure otherwise there will be malfunctionsnDust and chips are retained by sintered metal air filtersnLiquids can be drawn through the sintered metal filter, thus the breathing spring area is reduced, a higher excess pressure or vacuum is caused and the function is impaired66What is breathing?What happens during breathing67PrecautionsCovernClamping elements without breather ports can be covered.nDue to high coolant pressure and flow this is not always successfulnConsider using double acting elements wherever possible68PrecautionsBreather hosenConnection of a breather hose is approved if the outlet is sited at a point where no liquid can penetratenEnsure no fluid traps in hose69PrecautionsClosed breather systemnSpring area is increased by connection of additional closed area.nElectrical die cast boxes are idealnVolume of additional area should be 10 times the stroke volume of all connected components70System bleedingThe system must always be free from air71Component DesignnComponents can be of fixed design72Component DesignnClamping points can be incorporated into design of component73Designed for Clamping74Designed for Clamping75Inaccessible clamping positions76Indirect Clamping77Fixture DesignnStatic fixturenTombstonenHorizontal machining78Fixture Design79Fixture Design80RemembernFIXTURE DESIGNnGood fixtures position, clamp and support components in the most effective way possiblenDEFINITION OF A CLAMPING FORCEThe force acting on a workpiece to be clamped, is large enough to hold the workpiece firmly in its given position relative to the cutting tool, against the action of the machining forcesnSENSIBLE USE OF FORCESensible introduction of positioning, clamping and supporting forces will enhance the quality of a workpiece81Vektek China Rep. 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