机械毕业设计英文外文翻译30薄板冲压件焊装夹具设计方法副本.docx

机械毕业设计英文外文翻译30薄板冲压件焊装夹具设计方法副本.docx

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机械毕业设计英文外文翻译30薄板冲压件焊装夹具设计方法副本

附录

附录A英文文献

OnWelding-InstallationFixturesDesignofSheetStamping

Abstract:

Duetoformingerrorandcomplianceofstamp-ing,thefixturedesignofsheetstampingassemblyisdifferentfromthefixturedesignofcommonmachiningcomponent.Inrecentyears,thenewprinciplesandalgorithmsoffixturedesignofsheetstampinghavebeendeveloped.Inthepaper,theconceptofshapeclosureandforceclosure,screwtheorywerefirstlyintroduced.Secondly,thedeterministiclocatingandtotalfixturingconditionswerederived.Thirdly,an“N-2-1”locatingprincipleandoptimaldesignmethodforsheetstampingweredescribed.Finally,thevaria-tionalmethodofrobustfixtureconfigurationdesignfor3-Dworkpieceswasdiscussed.Itcanbepredicatedthatthelocatingerrorcanbereducedbythismethod.

KeyWords:

Fixture;SheetStamping;OptimalDesign;Ro-BustDesign

Duetoitshighproductivityandmaterialutilization,stampingiswidelyusedinautomobiles,aircraft,andvarioushouseholdappliancesmanufacturingindustry.Theweldingassemblyofstampingbecomesthekeyprocessofthoseproductsmanufacturing,becauseweldingfixturenotonlyaffectstheperformanceofproductivity,butalsoisdirectlyrelatedtothequalityoftheproduct.StatisticsfromtheU.S.autoindustryshowthat72%ofthebodymanufacturingerrorsarefromthepositionerrorofweldingfixture,sohowtoeffectivelyreduceandcontrolthepositioningerrorisessentialtoimprovetheweldingquality.Sheetstampingassemblyissignificantlydifferentfromgeneralmachining,whichnotonlymeetsthecommonrequirementsofprecisepositioning,butalsogivesfullconsiderationtotheeasydeformationofsheetmetalpartsandstampingmanufacturingcharacteristicsoflargedeviationstoadapttheproducts’qualityrequirements.Overthelastdecade,manyscholarsworkinginthedesignofsheetstampingassemblyhaveproposeddesigntheoriesandmethodsofsomenewsheetstampingassembly,andachievedremarkableresults.Atfirst,thispaperintroducestheresearchprogressoffixturedesign,andthensystematicallyelaboratestheN-2-1locatingprincipleoffixtureandthemethodsofoptimaldesignandrobustdesign,finallymakestheconclusion.

Manufacturingprocess（suchasmachining,welding,assemblyandtesting,etc.）,thefixtureisusedinthree-dimensionalpositioningandclampingdevice.Thecentralproblemoffixturedesignistochoosetheoptimalpositioningpointsanddeterminetheirbestpositiontoachievethedetermineconstraintspositioningofworkpiece.Iftheworkpiececanbefullrestrictiondependingonthegeometryofcontactareawill,wecalledit"shapeclosed";Ifitalsohavetobefullyboundwithfriction,wecalledit"forceclosure."Generally,shapeclosurestressesdynamicanalysis,butforceclosurefocusesontheworkpieceofstaticstability.In1885,Reuleauxfirststudiedthemechanismoftwo-dimensionalobjects’shapeclosure,andprovedthattheformationoftwo-dimensionalobjects’shapeclosureneedfouranchorpoints[2].AfterthatSomoffprovedtheformationofthree-dimensionalobjects’shapeclosureneedsevenanchorpoints.In1978,Lakshminarayana[3]furtherprovedtheformationofthree-dimensionalobjects’shapeclosureneedatleastsevenanchorpointsintheperspectiveofstaticequilibriumusingalgebraictheoryIn1988,Nguyenresearchedthemechanismofthemachinehand’sforceclosure[4],andin1989AsadaandKitagawa[5]researchedthemachinehand’sshapeclosurewhichusedforconvexandconcavepartsGenerallysixpositioningprinciplesrequiresclampingforcetomakeworkpiecefullyconstrained,sousuallyitisforceclosure.

Overthelastdecade,the"spiraltheory”widelyusedinfixturedesign,whichdescribesthethree-dimensionalmotionastranslatingalongonedirectionandrotatingaroundthisaxis.OriginallyspiraltheoryproposedbyBall[6],anddevelopedbyliterature[7]and[8].Accordingtospiraltheory,literature[9]studiedsevendifferenttypesoffingercontact,andsuggestedusingfinger-likeshapetocompletelyfixobjects.Literature[10]usingtheextendedspiraltheoryanalyzedthatrigidbody’sfullorpartrestrictionexistfrictionalclamp.Literature[11]proposedmathematicaltheoryoffixture’sautomaticlayoutforprismaticworkpieces.Literature[12]discussedtheabilityofdifferentfixturespositioncontactpreventingworkpiecesfromspiralmovement,andproposedarestrictmethodofworkpiecemovementforthefixturedesign.Usingsmallspiralmodelliterature[13]discussedthepositioningerrorsoffixtureimpactworkpieces’geometryaccuracy.Literature[14]researchedsurfacecontactandfrictionproblemsintheanalysisoffixturerestriction.Consideringdynamicconstraints,completelyclamping,andtoolpatherrors,literature[15]developedfixturedesignandanalysissoftware.Itcanbesaidthatspiraltheoryoffixturedesignhasbeenusedfordeterminingposition,fullclamping,contacttype,andfrictionproblemsandachievedremarkableresults.

Lotsofliteraturesfocusonthefixturedesignofrigidpieces,butthefixturedesignofflexiblesheetpiecesisrarelyinvolved,especiallyconsideringthedeformationoftheworkpieceunderprocessingloadsisalmostnone.Infact,asintheaviationindustryandtheautomotiveindustry,thedeformationofsheetmayresultinseriousbias.Foreasilydeformedsheet,positioningfixturenotonlyhasbasicfunctionsthatlimitingrigidbodymotion,butalsomustbeabletolimitexcessivedeformationoftheworkpiece.Theresearchthatearlierconsideringtherigidityofworkpiecesorfixturepositingcellwillbefoundintheliterature[16]basedontheexperimentalresultstheystudiedfixturestiffnessandwear’seffectsonthesizeaccuracy.Literature[17]proposedafiniteelementmodelofthefixturesystemforflexiblepositioningfixture,andthepowerinprocessofprocessingcanbeseenastheforceactingonthenode.Basedonthismodel,youcancalculatethedeformationoftheworkpiece,theclampingforce,stressdistributionandfrictionbetweentheworkpieceandfixturepositioningunit’scontactpointscanbecalculatedbyCoulomb'slaw.Althoughbyconsideringthedeformationoftheworkpieceandthefiniteelementanalysisthisareahavebeenpromoted,butithasneitherproposedanyspecificpositingprinciple,norproposedpositioningschemeforflexiblesheet.Inaddition,thismodeldoesnotcombinethefiniteelementanalysisresultsoftheworkpiecewiththefixturedesign;itismorethantheanalysisoftheworkpieceotherthanfixturedesign.Literature[18]proposedaanalysismethodofsheetfixturepositing,theystudiedthefixturepositioningsystemusingthecaseandflatthree-pointandfour-pointtoposit,sothefixturelayoutmustmakethestressintheworkpiecesbelowtheyieldstress.However,thismethoddoesnotsolvetheessentialproblemofsheetfixture,becausereducingdeformationisthekeytothepositioningofsheet.Basedonliterature[17],literature[19]continuedfurtherstudy,thatusingthefiniteelementmodelingtochoosefixturelayoutmakesthedeformationminimuminthefirstbase-level.Todeterminetheoptimalfixturelayout,usingquasi-Newtonoptimizationalgorithmmakesthedeformationsquaresonthefiniteelementmeshofthekeynodesminimum.Designvariablesarethethreeanchorpointsonthefirstbaserequiredby"3-2-1"principle.

Sheetstampingassemblyfixturesarewidelyusedinautomobiles,aircraftandhouseholdappliancesindustries,whosedesignqualitydirectlyaffectstheentireproductmanufacturingdeviations.Duetosheetmetalstamping’scharacteristicofflexibilityandmanufacturingvariations,theprincipleoftraditionalfixturedesigncannotmeetthedesignrequirements,althoughtheresearchoffixturedesignisalreadyquitematureandthepositioningprincipleofrigidpartandthe"spiraltheory"hasbeenin-depthstudy."N-2-1"Locationprinciple,forthecharacteristicofeasydeformationonthehorizontalofSheetMetalStamping,presentsthatwhenthenumberofanchorpointsismorethan3inthefirstbasesurface,positioneffectdependsnotonlyonthenumberofanchorpoints,butalsoonthearrangementoftheanchorpoints.Apartfromthat,itproposesthefiniteelementanalysisandthedesignofnonlinearprogrammingmethodoftheanchor,whichprovidestheoreticalbasisanddesignmethodsforthedesignofsheetweldingfixture.Becauseofthelargermanufacturesizedeviationofsheetmetalpartsandtheremarkableeffectofthechoiceofanchorpositionforpositiondeviation,robustfixturedesigncansignificantlyimprovethepositioningerror.Therefore,duringthedesignofsheetweldingfixture,implementingthe"N-2-1"locationprincipleandrobustdesignmethodisextremelyimportant.Ithasbeenprovedtohaveamultipliereffect.

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