畢業(yè)設計外文翻譯原文

Optimumblankdesignofanautomobilesub-frameJong-YopKima,NaksooKima,*,Man-SungHuhbaDepartmentofMechanicalEngineering,SogangUniversity,Shinsu-dong1,Mapo-ku,Seoul121-742,SouthKoreabHwa-shinCorporation,Young-chun,Kyung-buk,770-140,SouthKoreaReceived17July1998AbstractAroll-backmethodisproposedtopredicttheoptimuminitialblankshapeinthesheetmetalformingprocess.Themethodtakesthedifferencebetweenthe?naldeformedshapeandthetargetcontourshapeintoaccount.Basedonthemethod,acomputerprogramcomposedofablankdesignmodule,anFE-analysisprogramandameshgenerationmoduleisdeveloped.Theroll-backmethodisappliedtothedrawingofasquarecupwiththeˉangeofuniformsizearounditsperiphery,tocon?rmitsvalidity.Goodagreementisrecognizedbetweenthenumericalresultsandthepublishedresultsforinitialblankshapeandthicknessstraindistribution.Theoptimumblankshapesfortwopartsofanautomobilesub-framearedesigned.Boththethicknessdistributionandthelevelofpunchloadareimprovedwiththedesignedblank.Also,themethodisappliedtodesigntheweldlineinatailor-weldedblank.Itisconcludedthattheroll-backmethodisaneffectiveandconvenientmethodforanoptimumblankshapedesign.#2000ElsevierScienceS.A.Allrightsreserved.Keywords:Blankdesign;Sheetmetalforming;Finiteelementmethod;Roll-backmethod1.IntroductionItisimportanttodeterminetheoptimumblankshapeofasheetmetalpart.However,becauseitsdeformationduringtheformingprocessisverycomplicated,itisnoteasytodesigntheoptimumblankshapeevenbytheskilledlaborbasedontheexperienceofmanyyears.Recently,computa-tionalanalysisforacomplexautomobileparthasbeenabletobecarriedouteasilyduetoimprovedcomputerperfor-manceandthenumericalanalysistechnique.Intheanalysisprocess,allkindsofvariablesthataffectthedeformationshouldbeconsidered.Theoptimumblankshapeleadstothepreventionoftearing,uniformthicknessdistributionandtothereductionofthepressloadduringdrawing.Iftheblankshapeisdesignedoptimally,theformabilitywillbeincreasedandthe?nalproductwillrequiretheleastamountoftrimmingattheendoftheprocess.Therefore,itisdesirabletodesigntheblankshapewithauniformˉangeofitsperipheryafterdeepdrawing.Severalnumericalsolutionsforthedeepdrawingprocessofnon-circularcomponentshavebeenreported.HasekandLange[1]gaveananalyticalsolutiontothisproblemusingtheslip-line?eld-methodwiththeassumptionofplane-strainˉangedeformation.Also,Jimma[2]andKarima[3]usedthesamemethod.VogelandLee[4]andChenandSowerby[5]developedidealblankshapesbythemethodofplane-stresscharacteristics.Sowerbyetal.[6]developedageometricmappingmethodprovidingatrans-formationbetweenaˉatsheetandthe?nalsurface.MajlessiandLee[7,8]developedamulti-stagesheetmetalforminganalysismethod.ChungandRichmond[9±12]determinedidealcon?gurationsforboththeinitialandtheintermediatestagesthatarerequiredtoformaspeci?ed?nalshapeusingtheidealformingtheory.LeeandHuh[13]introducedathree-dimensionalmulti-stepinversemethodfortheoptimumdesignofblankshapes.TohandKobayashi[14]developedarigid±plastic?nite-elementmethodforthedrawingofgeneralshapesbasedonmembranetheoryand?nite-strainformulations.Zhaotao[15]usedtheboundaryelementmethodfora2Dpotentialproblemtodesignoptimumblankshapes.Thispaperpresentsanoptimumdesignmethodofblankshapesforthesquarecupdrawingprocessconsideringprocessvariables.Anoptimumblankshapeofsquarecupdrawingwasobtainedusingtheproposedmethod.Also,itwasappliedtothedeepdrawingofanautomobilesub-frame,andanoptimumblankshapewithauniformˉangeatitsperipheryweredetermined.JournalofMaterialsProcessingTechnology101(200031±43*Correspondingauthor.Tel.:82-2-705-8635;fax:82-2-712-0799.E-mailaddress:nskim@ccs.sogang.ac.kr(NaksooKim0924-0136/00/$±seefrontmatter#2000ElsevierScienceS.A.Allrightsreserved.PII:S0924-0136(9900436-72.DesignofoptimumblankshapeThede?nitionoftheoptimumblankshapeisthemini-mizationofthedifferencebetweentheoutercontourofthedeformedblankandthetargetcontourthatindicatestheresidualˉangeofuniformsizearoundtheperipheryoftheproduct.Thetargetcontourisgeneratedfromtheoutercontouroftheproductanddeterminesanoptimumblankshapeusingtheresultsof?nite-elementsimulationwiththeroll-backmethod.Intheprocessofblankdesignthesimula-tionisperformedusinganexplicit?nite-elementsoftwarePAM-STAMPandtheinterfaceprogramisdevelopedforcon-nectingtheblankdesignmodule,theremeshingmodule,thepost-processormoduleandtheFE-analysispackage.2.1.Roll-backmethod`Theroll-backmethodstartsbyde?ningthetargetcon-tour.Afterdeterminingthelengthoftheˉangethatremainsaroundtheperipheryoftheproduct,thepro?leofthetargetcontouriscreatedbyoffsettinganequaldistancefromtheoutercontouroftheproductanditsmeshsystemisgener-atedbybeamelements.TheprocessofblankdesignisillustratedinFig.1.ThemeshsystemofthepreparedsquareblankforinitialanalysisisshowninFig.1(a.Afterananalysis,themeshsystemofthedeformedblankandthetargetcontourareshowninFig.1(b.Attheˉangeofthedeformedblank,adistinctionismadebetweentheinteriorˉangewithinthetargetcontourandtheexteriorˉangeoutofthetargetcontour.Theˉangeoutofthetargetcontouristhepartthatwillbetrimmedandtheˉangewithinthetargetcontouristhepartwhichdoesnotkeepshapeisduetotheincompletionoftheblankshape.Thusthemodi?edblankshapeshouldbedesignedtotaketheshapeoftheoutercontouroftheproductcompletely.Thecontourofthemodi?edblankshapeusingtheroll-backmethodandtheinitialblankshapeisshowninFig.1(c.Themeshsystemofthemodi?edblankshapeforFE-analysisisshowninFig.1(d.Theblankdesignmethodwillbeintroducedindetail.ThequarterofthedeformedblankandthetargetcontourareshowninFig.2(a.Accordingtothepreviousexplanation,theremainedˉangecanbedividedintotheinteriorandtheexteriorˉange.ThedesignprocessofregionAisshowninFig.2(b.InthemeshofthedeformedblankasquaregridIJKLonthetargetcontourwillbeconsidered,andthentheinternaldividingpointQinwillbecalculatedattheratioofmtonFig.1.Illustratingtheprocessof?ndingtheoptimumblank:(ainitialblankshape;(bdeformedblankandtargetcontour;(croll-backblankandcontour;(dmodi?edblankshape.Fig.2.Theroll-backprocessofameshlocatedonthesurfaceoftheˉange:(aameshlocatedonthesurfaceoftheˉange;(bregionA:residualdrawingpartoutoftargetcontour;(cregionB:residualdrawingpartinsidethetargetcontour.32J.-Y.Kimetal./JournalofMaterialsProcessingTechnology101(200031±43betweenthenodeJandK.Thispointismappedbackintothemeshsystemoftheinitialblank.TheinternaldividingpointQHiniscalculatedattheratioofmtonbetweenthesamenodeJHandKH.Thefollowingprocessisperformedontheelementofthedeformedblankonthetargetcontour.Thedescribingpointoftheoutercontourofthemodi?edblankshapecanbecalculated.IfthecoordinatesofthenodesJandKareJ(x1,y1,K(x2,y2andthecoordinatesofthenodesJHandKHareJHxH1YyH1YKHxH2YyH2,theratioofmtonismXnJQJKXQKJK(1ThecoordinateoftheinternaldividingpointQHincanbeexpressedasQHinmxH2nxH1mnYmyH2nyH1mn(2ThedesignprocessofregionBisshowninFig.2(c.InthemeshofthedeformedblankasquaregridMNOPofwhichtheoutwardedgecrossesthetargetcontourshouldbeconsidered,andthentheexternaldividingpointQoutcanbecalculatedattheratioofmtonbetweennodesOandP.Thispointismappedbackintothemeshsystemoftheinitialblank.TheexternaldividingpointQHoutcanbecalculatedattheratioofmtonbetweenthesamenodesQHandPH.IfthecoordinatesofthenodesOandPareO(x1,y1,P(x2,y2andthecoordinatesoftheOHandPHareOHxH1YyH1YPHxH2YyH2,theratioofmtonismXnOQOPXQPOP(3ThecoordinateoftheexternaldividingpointQHoutcanbeexpressedasQHoutmxH2ànxH1YmyH2ànyH1(4Thefollowingprocessisperformedonalltheelementofthedeformedblankrelatedonthetargetcontour.Thepointsdescribingtheoutercontourofmodi?edblankshapecanbecalculated.Whenallpointsoftwocasesareconnectedbythespline,theoutercontourofmodi?edblankcanbedescribed.ThisprocessisshowninFig.3.2.2.ThedevelopmentoftheoptimumblankdesignprogramTooptimizetheinitialblankshape,adesignprogramwasdevelopedfollowingtheprescribingmethodandprocedures.Thisprogramconsistsoftheblankshaperdesignmodule,themeshgenerationmoduleandthepost-processormodule.ThewholeprocedureisillustratedinFig.4.Toperformthedesignprocessofablankshape,aninterfacemoduleisneeded.Thismoduleisdevelopedtoreadtheoutput?leof?nite-elementanalysisanddesigntheoptimumblankshapeandgeneratetheinput?le.3.Designsofblankshapeandapplication3.1.BlankdesignofasquarecupToverifythevalidityoftheroll-backmethod,itisappliedtotheprocessofsquarecupdeepdrawing.Severalnumericalsolutionsofthedeepdrawingprocessfornon-circularcomponentshavebeenreportedrecently.Thepub-lishedblankshapesbyLeeandcoworkers[16±18]arecomparedwiththeresultusingtheroll-backmethod.TheFig.3.Flowchartoftheblankdesignmodule.Fig.4.Flowchartofthemainprogram.J.-Y.Kimetal./JournalofMaterialsProcessingTechnology101(200031±4333dimensionsofthedieandpunchsetforananalysisareshowninFig.5.Thematerialofthesheetmetaliscold-rolledsteelforanautomobilepart.Thefollowingarethematerialpropertiesandprocessvariables.Stress±strainrelation:"s58X78?0X00003"e0X274kgfamm2;Lankfordvalue:"R1X679;initialblanksize:160mm?160mmsquareblank;initialthickness:t0.69mm;frictioncoef?cient:m0.123;andblank-holdingforce:4000kgf(1kgf9.81N.ThedeformedshapesofthesquarecupobtainedfromtheinitialblankandtheoptimumblankareshowninFig.6.Inthepresentworktheoptimumblankshapeforasquarecupthatisof40mmheightand5mmwidthofˉangewillbedetermined.Eachmodi?edblankshapeaftertheapplicationoftheroll-backmethodisillustratedinFig.7.Whenan160mm?160mmsquareblankisusedforaninitialblanktheoutercontourofdeformedblankisshowninFig.7(a.A?rstmodi?edblankshapecanbecalculatedwiththeresultoftheinitialsquareblank.AnanalysisresultisshowninFig.7(b.Thedifferencebetweenthedeformedshapeandthetargetcontourissigni?cant.Iftheblankdesignprocessisrepeatedseveraltimesthedifferencedecreasesandcon-vergestozero.Henceasquarecupwithauniformˉangeatitsperipherycanbemade.Thecomparisonbetweenthe?nalresultandapublishedresultisshowninFig.8.Inthetransversedirectiontheoptimumblankshapeusingtheroll-backmethodislargerthanthepublishedresult.Theload±displacementcurvesinsquarecupdrawingprocesswithvariousinitialblankshapesareshowninFig.9.Asthemodi?cationisrepeated,thegapoftheload±displacementcurvesbeforeandafteriterationdecreases.Thusafterthethirdmodi?cationthemaximumvalueoftheloadbecomesthemeanvaluebetweenthatofthe?rstandsecondmodi?cation.Afterthreemodi?cationstheoptimumblankshapeisdetermined,thentheresultwiththeoptimumblankshapeiscomparedwithresultsintheliterature.ThethicknessstraindistributioninthediagonaldirectionisshowninFig.10(a,whilstthethicknessstraindistributioninthetransversedirectionisshowninFig.10(b.Inthethicknessstraindistributiontheresultusingtheroll-backmethodisslightlydifferentfromthepublishedresult,buttheoverallstraindistributionsarequitesimilar.Itisthusveri?edthattheroll-backmethodisausefulapproachinthedesignofoptimumblankshapes.3.2.Blankdesignoftheleftmemberofafrontsub-frameAnanalysisformembersofabox-typefrontsub-frameisperformed.Theleftmemberisselectedasoneofthesubjectsforanalysisbecauseitsshapeisshallowbutcomplex.Fig.11showsthemanufacturingset-upasmodeledforthenumer-icalsimulation.Theleftmemberrequiresauniformˉangeforthespotweldingbetweentheupperandthelowerpartsbesidestheimprovementofformability.Itisrecommendedthatthelengthofuniformˉangeis30mm.Thetargetcontourisde?nedatthepositionwhichis30mmfromtheoutercontourofproductandisshowninFig.12.Itsmeshsystemisgeneratedbybeamelements.ThematerialofthesheetmetalisSAPH38P,ahot-rolledsteelforautomobileparts.Thefollowingarethematerialpropertiesandprocessvariables.Stress±strainrelationship:"s629?"e0X274(MPa;Lankfordvalue:"R1X030;initialthickness:t2.3mm;frictioncoef?cient:m0.1;blankholdingpressure:1MPa.Fig.5.Geometricaldescriptionofthetoolingforthedeepdrawingofasquarecup(dimensions:mm.Fig.6.ThedeformedshapeofsquarecupswithFE-meshgeometrywherethecupheightis40mm:(adeformedshapeofthesquarecupobtainedfromtheinitialblank;(bdeformedshapeofthesquarecupobtainedfromtheoptimumblank.34J.-Y.Kimetal./JournalofMaterialsProcessingTechnology101(200031±43Ahexagonalblankisusedastheinitialblank.Afterthreemodi?cationstheoptimumblankshapeisdetermined.Forthiscase,theload±displacementcurveswithvariousblankshapesareshowninFig.13.ThecomparisonoftheinitialˉangeandthedeformedˉangewithvariousblankshapesisshowninFig.14.Asthemodi?cationisrepeated,themaximumpunchloadisreducedandtheoutercontourmaybedrawntothetargetcontouratthesametime.Thethicknessdistributionisimprovedstepbystep;thethicknessdistributionwithvariousblankshapesbeingshowninFig.15.Thecomparisonbetweentheoptimumblankshapedesignedbytheroll-backmethodandtheblankshapeformassproductionisillustratedinFig.16.Theoptimumblankshapeshowscurvaturebecausetheoutercontouroftheproductandtheˉowrateofthesheetmetalareconsidered.However,theblankshapeformassproductionissimpleandstraightbecausetheconvenienceofcuttingisconsidered.Toverifytheresultaninitialblankcutbyalaser-cuttingmachinewasprepared.The?nalshapedrawnwiththeinitialblankinthepressshopisshownFig.7.Comparisonoftheinitialˉangeshapesandthedeformedˉangeshapes:(ainitialsquareblank;(b?rstmodi?edblank;(csecondmodi?edblank;(dthirdmodi?edblank.Fig.8.Comparisonoftheinitialblankcontourbetweentheroll-backmethodandHuh'smethod.J.-Y.Kimetal./JournalofMaterialsProcessingTechnology101(200031±4335inFig.17.Ithadaˉangeofuniformsizearounditsperiphery.Thethicknessdistributionatthepositionoffoursectionsinthelongitudinaldirectionoftheleftmemberwasmea-sured.Fig.18showsacomparisonofthicknessbetweenthecomputedresultsandtheexperimentalresultsineachsec-tion.InsectionA,thethicknessdistributionhassomeerrorattheendoftheˉange,whilstinsectionsBandC,thecomputedresultsarecompatiblewiththeexperimentalresults.InsectionD,thecomputedresultspredictedthatasplitmighthappen,buttheexperimentalcupdidnotsplit.Fig.9.Load±displacementcurvesinthesquarecupdrawingprocesswithvariousinitialblankshapes.Fig.10.Thicknessstraindistributioninasquarecup:(adiagonaldirection;(btransversedirection.Fig.11.FE-modelforasub-frameleftmember.Iftheinitialblankshape,the?nalshapeandthicknessdistributionareconsidered,theresultspredictedbytheroll-backmethodhasagoodagreementwiththeexperimentalvalues.Therefore,aswellastheroll-backmethodbeingapplicabletoasimpleshape,itcanbeappliedtoacomplexandlargeshape.3.3.BlankdesignofNo.2memberoffrontsub-frameAnanalysisofNo.2memberisperformed,withitsdeepandcomplexshape.Itsoptimumblankshapeisdesignedusingtheroll-backmethod.Fig.19showsthemanufacturingset-upasmodeledforthenumericalsimulation.Becauseitsdrawingdepthisverydeep,eccentricitymayoccurduetotheblankinitialpositionorshape.Thusthetargetcontourisde?nedatthepositionthatis40mmfromtheoutercontourofproductanditisshowninFig.20.Asquareblankisusedastheinitialblank.Afterthreemodi?cationstheoptimumblankshapeisdetermined.Fig.12.Targetcontourfortheleftmember.Fig.13.Load±displacementcurvesintheleftmemberdrawingprocesswithvariousblankshapes.Fig.14.Comparisonoftheinitialˉangeshapesandthedeformedˉangeshapes:(ainitialblank;(b?rstmodi?edblank;(csecondmodi?edblank;(dthirdmodi?edblank.Fig.15.Thicknessdistributionwithvariousblankshapes(unit:mm:(ainitialblank;(b?rstmodi?edblank;(csecondmodi?edblank;(dthirdmodi?edblank.Fig.16.Comparisonoftheinitialblankshapespredictedbytheroll-backmethodandthosedesignedbyskilledlabor.Forthiscase,load±displacementcurvesforvariousblankshapesareshowninFig.21,whilstacomparisonoftheinitialˉangeandthedeformedˉangewithvariousblankshapesinshowninFig.22.ThethicknessdistributionwiththeinitialshapeisshowninFig.23,whilstthethicknessdistributionwiththeoptimumblankshapeisshowninFig.24.Thethicknessdistributionoftheside-wallandofthe?lletconnectingtheside-walltothetopisimproved.Fig.17.Leftmemberdrawninthepressshopwiththeinitialblankpredictedbytheroll-backmethod.Fig.18.(aSectionsformeasuringthethicknessdistribution.(b±eThicknessdistributionsatsectionsA±D,respectively.3.4.DesignoftheweldinglinewithTWBanalysisofNo.2memberAfterdesigningtheoptimumblankshapeofNo.2member,atailor-weldedblankisappliedtothismember.Toreducetheweightofthesub-frame,structuralanalysisisperformed.Ontheareawherethestressintensitylevelislow,itisproposedtoreducethethicknesslocally.Therefore,itisrequiredtodesignatailor-weldedblankthatmakesaspeci?edshapeafterdeformation.Whentwosheetmetalsofdifferentthicknessareweldedtogether,theirmetalˉowisdifferentfromthatofsheetmetalofthesamethickness.Thusitisdif?culttodesignthelocationoftheweldline.Inthissimulationtheweldlineisdesignedbytheuseoftheroll-backmethodandtheweldinglineshouldbelocatedatthespeci?edpositionafterdeformation:thespeci?edpositionis120mmonbothsidesofthecenterline.Thusthetargetlineisde?nedandmeshedbybeamelements.TheoutercontourofTWBandtheweldinglineareshowninFig.25,andtheresultsareshowninFigs.26and27.Theweldinglinescanbereachedtothetargetlinebut,onthetopoftheblankthathasthelowerthickness,fracturemayoccur.Thisisthesameastheresultthatinthedeepdrawingofatailor-weldedblankwithdifferentthickness,failureoccurredattheˉatbottomofthepunchparalleltotheweldline.Thisisduetothedeformationnotbeingdis-Fig.19.FE-modelforthesub-frameleftmember.Fig.20.TargetcontourfortheNo.2member.Fig.21.Load±displacementcurvesintheNo.2memberdrawingprocesswithvariousblankshapes.J.-Y.Kimetal./JournalofMaterialsProcessingTechnology101(200031±4341Fig.23.Thicknessdistributionwiththeinitialblankshape(unit:mm:(afrontview;(brearview.Fig.24.Thicknessdistributionwiththeoptimumblankshape(unit:mm:(afrontview;(brearview.Fig.22.Comparisonoftheinitialˉangeshapesandthedeformedˉangeshapes:(ainitialblank;(b?rstmodi?edblank;(csecondmodi?edblank;(dthirdmodi?edblank.Fig.25.Comparisonoftheweldlinebetweentheinitialblankshapeandthedeformedblankshape.42J.-Y.Kimetal./JournalofMaterialsProcessingTechnology101(200031±434.ConclusionsInthispapertheroll-backmethodthatdesignsanoptimumblankshapeisproposed.Basedonthemethod,acomputerprogramcomposedofablankdesignmodule,anFE-analysisprogramandameshgenerationmoduleisdevelopedanditisappliedtothedeepdrawingofafrontsub-frame.Theresultsofthepresentpaperaresummarizedasfollows:1.Toverifythevalidityoftheproposedmethoditisappliedtothedeepdrawingofasquarecup.Theoutercontourmaybedrawntothetargetcontour.2.Theroll-backmethodisappliedtotheoptimumblankdesignofaleftmemberofanautomobilesub-frame.Thethicknessdistributionandtheloadlevelareimproved.Whentheinitialblankshape,the?nalshapeandthicknessdistributionarecompared,theresultspredictedbytheroll-backmethodhaveagoodagreementwiththeexperimentalresults.Itisconcludedthatthismethodcanbeappliedtothedeepdrawingofthecomplexautomobileparts.3.TheanalysisofNo.2memberwithatailor-weldedblankisperformed.Thepositionofweldinglinesontheinitialblankisdesigned.Theroll-backmethodcanbeappliedtothedesignoftheweldinglineposition.4.Inmostcases,theedgeofblanktakestheshapeofthetargetcontourwithinafewiterations,whichshowsthattheroll-backmethodisaneffectiveandconvenientmethodforanoptimumblankshapedesign.Fig.26.DeformedshapeofNo.2memberwiththetailor-weldedblank.Fig.27.DeformedshapeofNo.2memberwiththetailor-weldedblank:(afrontview;(brearview.tributeduniformly,mostofthestretchingbeingconcentratedonthesideoftheblankwithlowerstrength.TheprocessconditionwithoutfractureshouldbedeterminedforthecombinationofthedrawingdepthandthetwodifferentthicknessasshowninFig.28.References[1]V.V.Hasek,K.Lange,Useofslipline?eldmethodindeepdrawingoflargeirregularshapedcomponents,ProceedingsoftheSeventhNAMRC,AnnArbor,MI,1979,pp.65±71.[2]T.Jimma,Deepdrawingconvexpolygonshellresearchesonthedeepdrawingofsheetmetalbytheslip