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外文翻译---笔记本上盖外壳的镁合金薄板冲压模具设计 英文版.doc

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外文翻译---笔记本上盖外壳的镁合金薄板冲压模具设计 英文版.doc

1DiedesignforstampinganotebookcasewithmagnesiumalloysheetsContentSummaryInthepresentstudy,thestampingprocessformanufacturinganotebooktopcovercasewithLZ91magnesium–lithiumalloysheetatroomtemperaturewasexaminedusingboththeexperimentalapproachandthefiniteelementanalysis.Afouroperationstampingprocesswasdevelopedtoeliminateboththefractureandwrinkledefectsoccurredinthestampingprocessofthetopcovercase.Inordertovalidatethefiniteelementanalysis,anactuafouroperationstampingprocesswasconductedwiththeuseof0.6mmthickLZ91sheetastheblank.Agoodagreementinthethicknessdistributionatvariouslocationsbetweentheexperimentaldataandthefiniteelementresultsconfirmedconfirmedtheaccuracyandefficiencyoftheementanalysis.ThesuperorformabilityofLZ91sheetatroomtemperaturewasalsodemonstratedinthepresentstudybysuccessfulmanufacturingofthenotebooktopcovercase.Theproposedfouroperationprocesslendsitselftoanefficientapproachtoformthehingeinthenotebookwithlessnumberofoperationalproceduresthanthatrequiredinthecurrentpractice.ItalsoconfirmsthatthenotebookcovercasescanbeproducedwithLZ91magnesiumalloysheetbythestampingprocess.Itprovidesanalternativetotheelectronicsindustryintheapplicationofmagnesiumalloys.KeywordsNotebookcaseLZ91magnesium–lithiumalloysheetstampingMultioperationFormability21.IntroductionDuetoItslightweightandgoodperformanceinEMIresistance,magnesiumalloyhasbeenwidelyusedforstructuralcomponentsintheelectronicsindustry,suchascellularphonesandnotebookcases.Althoughtheprevailingmanufacturingprocessofmagnesiumalloyproductshasbeendiecasting,thestampingofmagnesiumallsheethasdrawninterestsfromindustrybecauseofitscompetitiveproductivityandperformanceintheeffectiveproductionofthinwalledstructuralcomponents.Asforstampingprocess,AZ31magnesiumalloyaluminum3,zinc1sheethasbeencommonlyusedfortheformingprocessatthepresenttime,eventhoughitneedstobeformedatelevatedtemperatureduetoitshexagonalclosedpackedHCPcrystalstructureRecently,themagnesium–lithiumLZalloyhasalsobeensuccessfullydevelopedtoimprovetheformabilityofmagnesiumalloyatroomtemperature.TheductilityofmagnesiumalloycanbeimprovedwiththeadditionoflithiumthatdevelopstheformationofbodycenteredcubicBCCcrystalstructureTakudaetal.,1999a,bDrozdetal,2004.Inthepresentstudy,thestampingprocessofanotebooktopcovercasewiththeuseofLZsheetwasexamined.Theformingofthetwohingesinthetopcoverofanotebook,asshowninFig.1aandb,isthemostdifficultoperationinthestampingprocessduetothesmalldistancebetweentheflangesandthesmallcornerradiiattheflanges,asdisplayedinFig.1c.Thisgeometricomplexitywascausedbyadramaticchangeinthecornerradiuswhentheflangeofgetstooclosetthenotebook,whichwouldeasilycausefracturedefectaroundtheflangeofhingeandrequireamultioperationstampingprocesstoovercomethisproblem.Inthepresentstudy,theformabilityofLZmagnesiumalloysheetswasinvestigatedandanoptimummultioperationstampingprocesswasdevelopedtoreducethenumberofoperationallprocedusingboththeexperimentapproachandthefiniteelementanalysis.3Fig.1–Flangeofhingesatnotebooktopcovercase.aHinge,btopcovercaseandcflangesofhinge.2.Mechanicalpropertiesofmagnesiumcontentoflithiumincreases.ItisalsoobservfromFig.2athatthecurvesofLZ91sheetatroomtemperatureandAZ31sheetat200,Careclosetoeachother.LZ101sheetatroomtemperatureexhibitsevenbetterductilitythanLZ91andAZ31doat200,C.Sincethecostoflithiumisveryexpensive,LZ91sheet,insteadofLZ101sheet,canbeconsideredasasuitableLZmagnesiumalloysheettorenderfavorableformabilityatroomtemperature.Forthisreason,thepresentstudyadoptedLZ91sheetastheblankforthenotebooktopcovercaseandattemptedtoexaminetheformabilityofLZ91atroomtemperature.Inordertodetermineifthefracturewouldoccurinthefiniteelementanalysis,theforminglimitdiagramforthe0.6mmthickLZ91sheetwasalsoestablishedasshowninFig.2b.alloysheetsThetensiletestswereperformedformagnesium–lithiumalloysheetsofLZ61lithium6,zinc1,LZ91,andLZ101atroomtemperaturetocomparetheirmechanicalpropertiestothoseofAZ31sheetsatelevatedtemperatures.Fig.2ashowsthestress–strainrelationsofLZsheetsatroomtemperatureandthoseofAZ31sheetsatbothroomtemperatureand200C.Itisnotedthatthestress–straincurvetendstobelower.4Fig.2–Mechanicalpropertiesofmagnesiumalloy.aThestress–strainrelationsofmagnesiumalloybforminglimitdiagramFLDofLZ91sheet.3.ThefiniteelementmodelThetoolinggeometrieswereconstructedbyaCADsoftware,PRO/E,andwereconvertedintothefiniteelementmesh,asshowninFig.3a,usingthesoftwareDELTAMESH.Thetoolingwastreatedasrigidbodies,andthefournodeshellelementwasadoptedtoconstructthemeshforblank.Themateriallpropertiesandforminglimitdiagramsobtainedfromtheexperimentswereusedinthefiniteelementsimulations.Theothersimulationparametersusedintheinitialrunwerepunchvelocityof5mm/s,blankholderforceof3kN,andCoulombfrictioncoefficientof0.1.ThefiniteelementsoftwarePAMSTAMPwasemployedtoperformtheanalysis,andthesimulationswereperformedonadesktopPC.Afiniteelementmodelwasfirstconstructedtoexaminetheoneoperationformingprocessofthehinge.Duetosymmetry,onlyonehalfofthetopcover

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