外文翻译带自由面压铸模具冷却系统的最优设计.docx

外文翻译带自由面压铸模具冷却系统的最优设计.docx

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外文翻译带自由面压铸模具冷却系统的最优设计

附录

TheOptimalDesignofaCoolingSystemforaDie-CastingDieWithaFreeFormSurface

Abstract

Thisstudyisonthefiniteelementandabductivenetworkmethodapplicationtodie-castingdieswithfree-formsurfaces.Thestudyaimstofindtheoptimalcoolingsystemparametersanddecreaseindeformationofadie-castingdie.Inordertoavoidthenumerousinfluencingfactors,thefree-formsurfaceofadie-castingdieiscreatedasanon-linearEq.ofapolynomialfunction.Theparametersofthecoolingsystem,includingthechannelspaceandchanneldiameter,areadjustedaccordingtothenon-linearEq..

Anabductivenetworkhasbeenbuiltformodellingthediecastingcoolingparameters.Theabductivenetworkiscomposedofanumberoffunctionalnodes.Oncethecoolingsystemparametersaregiven,thisnetworkcanpredictthedeformationofthedie-castingaccurately.Asimulatedannealingoptimizationalgorithmwithaperformanceindexisthenappliedtotheneuralnetworkforsearchingfortheoptimalcoolingsystemparametersandtoobtainasatisfactoryresult.

Keywords：

Die-castingdie；Free-form；Neuralnetwork；Simulatedannealing

1.Introduction

Thetypical,traditionaldie-castingprocessincludeshigh-pressurefilling,cooling,solidificationandejectionstages.Thecoolingstageisofgreatimportancebecauseitsignificantlyaffectsboththeproductivityandthequalityofthedie-castpart.Itiswellknownthatabout80%ofthecycletimeofdie-castingisspentincoolingthehotmeltsufficientlysothatthecastpartcanbeejectedwithoutwarp.Thedesignofasuccessfuldiecanbeconsiderablyaffectedbyperfectfilling,whichreducesthecoolingtime,reduceswarpandinturnincreasesthequalityofthepart.Themainaimofthecoolingprocessistomaintainauniformtemperatureofthefillingandcoolingcycle.Accordingly,thereareatleasttwoimportantconceptsforthedesignerwhenconsideringthecoolingsystemandinestablishingcoolingprocessingconditions:

（1）achievinguniformtemperatureand.

（2）mini-misingthecycletime.

Toachievethesetwoaims,thedesignermayneedanoptimalcomputer-aideddesignsystemtoachievearapidanduniformcoolingsystem.Thedesignofanoptimalsystemneedsanalysisof3Dheattransferduringthefillingandcoolingprocesses.Thethermalanalysistoolshouldpredictthetemperaturegradientanddeformationofthedie-body.

Generallyspeaking,traditionaldiedesignstilldependsonexperience,duetothelackofanalyticabilityinmouldflowandheattransfer,sothedesignerisunabletoevaluateandhandlethedeformationresultingfrommaterialandthermalexpansionandshrinkageofthedie.Theparametersofdifferentcoolingsystemscancauselargetemperaturegradients,anddifferentdeformations.

AlthoughFEMsoftwareiscapableofanalysingthefillingflowandcoolingconditionsofpressure-injectedmetalandtheheatstress,heatstrainandtemperaturedistributionconditionsofadie-castingdieundervariouscoolingsystems,theestablishmentofananalyticmodelisverydifficult,especiallyfor3Dfree-formgeometry.Besidesunderstandingtherequirementsofmulti-cavitydies,andthemetalflowandsolidificationprocess,thedesignershouldbefullyacquaintantedwiththebasicfiniteelementsoftware.Integrationcanbeachievedandcansavealotofmoneyandtimeonlyifacompleteunderstandingoftheprocessofdiemanufacturingisavailableandeliminatetheannoyancecausedbymovingofpersonnel.

Initially,considerthedesignoftheventgateandoverflowgateintheprocessofinjectionandflowtofillthediecavityduringcoldroomdie-castingasinvestigatedbysimulationbyGarber[2].Whenmetalcastingusingaplungerintoacavity,heconsideredthechangeoccurringinthemetal,andthereplacementoftheairinthecavitybymoltenmetal.Subsequently,Garber[3,4]showedthattoolargeortoosmallaplungerspeedwillaffectthecastquality.GroeneveltandKaiser[5]studiedanddiscussedtheinfluenceofthespeedofinjectionofthemoltenmetalintothecavity,andflowdistanceandcavitytemperatureonthequalityofproductaftercasting.Accordingtotheexperiment,thedistanceofmoltenmetalflowincreaseslinearlyasthedie-castingspeedincreases,asdoesthedietemperature.Therangeoftemperatureisapproximately121–288ºC.Otherstudies[6,7]proposedtheimportanceofinitialtemperature（pre-heattemperature）ofthedie,andpointedoutthattoolowapre-heattemperaturewouldtendtocausefailureinfillingupthecavityinsidethediebythedie-castingliquid,andresultinformationfailure.Ahighertemperaturemayincreasethecoolingtimeandreduceproductivity.Truelove[8]usedacoolingsystemtocontroltheoveralltemperatureofthedie,inordertoobtainanoptimalheattransmissioncharacteristic,andreducetheoccur