文献翻译原文在冲压过程模拟产品和工艺设计最新应用.docx

文献翻译原文在冲压过程模拟产品和工艺设计最新应用.docx

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文献翻译原文在冲压过程模拟产品和工艺设计最新应用

模具工业现状Processsimulationinstamping–recent

applicationsforproductandprocessdesign

Abstract

Processsimulationforproductandprocessdesigniscurrentlybeingpracticedinindustry.However,anumberofinputvariableshaveasignificanteffectontheaccuracyandreliabilityofcomputerpredictions.AstudywasconductedtoevaluatethecapabilityofFE-simulationsforpredictingpartcharacteristicsandprocessconditionsinformingcomplex-shaped,industrialparts.

Inindustrialapplications,therearetwoobjectivesforconductingFE-simulationsofthestampingprocess;

（1）tooptimizetheproductdesignbyanalyzingformabilityattheproductdesignstageand

（2）toreducethetryouttimeandcostinprocessdesignbypredictingthedeformationprocessinadvanceduringthediedesignstage.Foreachoftheseobjectives,twokindsofFE-simulationsareapplied.Pam-Stamp,anincrementaldynamic-explicitFEMcodereleasedbyEngineeringSystemsInt'l,matchesthesecondobjectivewellbecauseitcandealwithmostofthepracticalstampingparameters.FAST_FORM3D,aone-stepFEMcodereleasedbyFormingTechnologies,matchesthefirstobjectivebecauseitonlyrequiresthepartgeometryandnotthecomplexprocessinformation.

Inapreviousstudy,thesetwoFEcodeswereappliedtocomplex-shapedpartsusedinmanufacturingautomobilesandconstructionmachinery.Theircapabilitiesinpredictingformabilityissuesinstampingwereevaluated.ThispaperreviewstheresultsofthisstudyandsummarizestherecommendedproceduresforobtainingaccurateandreliableresultsfromFEsimulations.

Inanotherstudy,theeffectofcontrollingtheblankholderforce（BHF）duringthedeepdrawingofhemispherical,dome-bottomedcupswasinvestigated.Thestandardautomotivealuminum-killed,drawing-quality（AKDQ）steelwasusedaswellashighperformancematerialssuchashighstrengthsteel,bakehardsteel,andaluminum6111.ItwasdeterminedthatvaryingtheBHFasafunctionofstrokeimprovedthestraindistributionsinthedomedcups.

Keywords:

Stamping;Process;stimulation;Processdesign

1.Introduction

Thedesignprocessofcomplexshapedsheetmetalstampingssuchasautomotivepanels,consistsofmanystagesofdecisionmakingandisaveryexpensiveandtimeconsumingprocess.Currentlyinindustry,manyengineeringdecisionsaremadebasedontheknowledgeofexperiencedpersonnelandthesedecisionsaretypicallyvalidatedduringthesofttoolingandprototypingstageandduringharddietryouts.Veryoftenthesoftandhardtoolsmustbereworkedorevenredesignedandremanufacturedtoprovidepartswithacceptablelevelsofquality.

ThebestcasescenariowouldconsistoftheprocessoutlinedinFig.1.Inthisdesignprocess,theexperiencedproductdesignerwouldhaveimmediatefeedbackusingaspeciallydesignsoftwarecalledone-stepFEMtoestimatetheformabilityoftheirdesign.Thiswouldallowtheproductdesignertomakenecessarychangesupfrontasopposedtodownthelineafterexpensivetoolinghasbeenmanufactured.One-stepFEMisparticularlysuitedforproductanalysissinceitdoesnotrequirebinder,addendum,orevenmostprocessconditions.Typicallythisinformationisnotavailableduringtheproductdesignphase.One-stepFEMisalsoeasytouseandcomputationallyfast,whichallowsthedesignertoplay“whatif”withoutmuchtimeinvestment.

Fig.1.Proposeddesignprocessforsheetmetalstampings.

Oncetheproducthasbeendesignedandvalidated,thedevelopmentprojectwouldenterthe“timezero”phaseandbepassedontothediedesigner.Thediedesignerwouldvalidatehis/herdesignwithanincrementalFEMcodeandmakenecessarydesignchangesandperhapsevenoptimizetheprocessparameterstoensurenotjustminimumacceptabilityofpartquality,butmaximumachievablequality.Thisincreasesproductqualitybutalsoincreaseprocessrobustness.IncrementalFEMisparticularlysuitedfordiedesignanalysissinceitdoesrequirebinder,addendum,andprocessconditionswhichareeitherknownduringdiedesignordesiredtobeknown.

Thevalidateddiedesignwouldthenbemanufactureddirectlyintothehardproductiontoolingandbevalidatedwithphysicaltryoutsduringwhichtheprototypepartswouldbemade.Tryouttimeshouldbedecreasedduetotheearliernumericalvalidations.Redesignandremanufacturingofthetoolingduetounforeseenformingproblemsshouldbeathingofthepast.Thedecreaseintryouttimeandeliminationofredesign/remanufacturingshouldmorethanmakeupforthetimeusedtonumericallyvalidatethepart,die,andprocess.

Optimizationofthestampingprocessisalsoofgreatimportancetoproducersofsheetstampings.Bymodestlyincreasingone'sinvestmentinpresses,equipment,andtoolingusedinsheetforming,onemayincreaseone'scontroloverthestampingprocesstremendously.Ithasbeenwelldocumentedthatblankholderforceisoneofthemostsensitiveprocessparametersinsheetformingandthereforecanbeusedtopreciselycontrolthedeformationprocess.

BycontrollingtheblankholderforceasafunctionofpressstrokeANDpositionaroundthebinderperiphery,onecanimprovethestraindistributionofthepanelprovidingincreasedpanelstrengthandstiffness,reducedspringbackandresidualstresses,increasedproductqualityandprocessrobustness.Aninexpensive,butindustrialqualitysystemiscurrentlybeingdevelopedattheERC/NSMusingacombinationofhydraulicsandnitrogenandisshowninFig.2.UsingBHFcontrolcanalsoallowengineerstodesignmoreaggressivepanelstotakeadvantagetheincreasedformabilitywindowprovidedbyBHFcontrol.

Fig.2.BlankholderforcecontrolsystemandtoolingbeingdevelopedattheERC/NSMlabs.

Threeseparatestudieswereundertakentostudythevariousstagesofthedesignprocess.Thenextsectiondescribesastudyoftheproductdesignphaseinwhichtheone-stepFEMcodeFAST_FORM3D（FormingTechnologies）wasvalidatedwithalaboratoryandindustrialpartandusedtopredictoptimalblankshapes.Section4summarizesastudyofthediedesignstageinwhichanactualindustrialpanelwasusedtovalidatetheincrementalFEMcodePam-Stamp（EngineeringSystemsInt'l）.Section5coversalaboratorystudyoftheeffectofblankholderforcecontrolonthestraindistributionsindeepdrawn,hemispherical,dome-bottomedcups.

2.Productsimulation–applications

TheobjectiveofthisinvestigationwastovalidateFAST_FORM3D,todetermineFAST_FORM3D'sblankshapepredictioncapability,andtodeterminehowone-stepFEMcanbeimplementedintotheproductdesignprocess.FormingTechnologieshasprovidedtheirone-stepFEMcodeFAST_FORM3DandtrainingtotheERC/NSMforthepurposeofbenchmarkingandresearch.FAST_FORM3Ddoesnotsimulatethedeformationhistory.Insteaditprojectsthefinalpartgeometryontoaflatplaneordevelopablesurfaceandrepositionsthenodesandelementsuntilaminimumenergystateisreached.ThisprocessiscomputationallyfasterthanincrementalsimulationslikePam-Stamp,butalsomakesmoreassumptions.FAST_FORM3Dcanevaluateformabilityandestimateoptimalblankgeometriesandisastrongtoolforproductdesignersduetoitsspeedandeaseofuseparticularlyduringthestagewhenthediegeometryisnotavailable.

InordertovalidateFAST_FORM3D,wecompareditsblankshapepredictionwithanalyticalblankshapepredictionmethods.Thepartgeometryusedwasa5 in.deep12 in.by15 in.rectangularpanwitha1 in.flangeasshowninFig.3.Table1liststheprocessconditionsused.Romanovski'sempiricalblankshapemethodandthesliplinefieldmethodwasusedtopredictblankshapesforthispartwhichareshowninFig.4.

Fig.3.RectangularpangeometryusedforFAST_FORM3Dvalidation.

Table1.ProcessparametersusedforFAST_FORM3Drectangularpanvalidation

Fig.4.Blankshapedesignforrectangularpansusinghandcalculations.

（a）Romanovski'sempiricalmethod;（b）sliplinefieldanalyticalmethod.

Fig.5（a）showsthepredictedblankgeometriesfromtheRomanovskimethod,sliplinefieldmethod,andFAST_FORM3D.Theblankshapesagreeinthecornerarea,butdiffergreatlyinthesideregions.Fig.5（b）–（c）showthedraw-inpatternafterthedrawing

process

oftherectangularpanassimulatedbyPam-Stampforeachofthepredictedblankshapes.Thedraw-inpatternsforallthreerectangularpansmatchedinthecornersregionsquitewell.Thesliplinefieldmethod,though,didnotachievetheobjective1 in.flangeinthesideregion,whiletheRomanovskiandFAST_FORM3Dmethodsachievedthe1 in.flangeinthesideregionsrelativelywell.Further,onlytheFAST_FORM3Dblankagreesinthecorner/sidetransitionregions.Moreover,theFAST_FORM3DblankhasabetterstraindistributionandlowerpeakstrainthanRomanovskiascanbeseeninFig.6.

Fig.5.VariousblankshapepredictionsandPam-Stampsimulationresultsfortherectangularpan.

（a）Threepredictedblankshapes;（b）deformedsliplinefieldblank;（c）deformedRomanovskiblank;（d）deformedFAST_FORM3Dblank.

Fig.6.ComparisonofstraindistributionofvariousblankshapesusingPam-Stampfortherectangularpan.

（a）DeformedRomanovskiblank;（b）deformedFAST_FORM3Dblank.

Tocontinuethisvalidationstudy,anindustrialpartfromtheKomatsuLtd.waschosenandisshowninFig.7（a）.WepredictedanoptimalblankgeometrywithFAST_FORM3DandcompareditwiththeexperimentallydevelopedblankshapeasshowninFig.7（b）.Asseen,theblanksaresimilarbuthavesomedifferences.

Fig.7.FAST_FORM3Dsimulationresultsforinstrumentcovervalidation.

（a）FAST_FORM3D'sfo