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外文翻译--单一的塑料注塑模具浇口的优化.doc

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外文翻译--单一的塑料注塑模具浇口的优化.doc

SinglegateoptimizationforplasticinjectionmoldLIJiquan,LIDequn,GUOZhiying,LVHaiyuanDepartmentofPlasticityTechnology,ShanghaiJiaoTongUniversity,Shanghai200030,ChinaEmailhutli163.comReceivedNov.22,2006revisionacceptedMar.19,2007AbstractThispaperdealswithamethodologyforsinglegatelocationoptimizationforplasticinjectionmold.Theobjectiveofthegateoptimizationistominimizethewarpageofinjectionmoldedparts,becausewarpageisacrucialqualityissueformostinjectionmoldedpartswhileitisinfluencedgreatlybythegatelocation.Featurewarpageisdefinedastheratioofmaximumdisplacementonthefeaturesurfacetotheprojectedlengthofthefeaturesurfacetodescribepartwarpage.Theoptimizationiscombinedwiththenumericalsimulationtechnologytofindtheoptimalgatelocation,inwhichthesimulatedannealingalgorithmisusedtosearchfortheoptimum.Finally,anexampleisdiscussedinthepaperanditcanbeconcludedthattheproposedmethodiseffective.KeywordsInjectionmold,Gatelocation,Optimization,Featurewarpagedoi10.1631/jzus.2007.A1077DocumentcodeACLCnumberTQ320.66INTRODUCTIONPlasticinjectionmoldingisawidelyused,complexbuthighlyefficienttechniqueforproducingalargevarietyofplasticproducts,particularlythosewithhighproductionrequirement,tighttolerance,andcomplexshapes.Thequalityofinjectionmoldedpartsisafunctionofplasticmaterial,partgeometry,moldstructureandprocessconditions.Themostimportantpartofaninjectionmoldbasicallyisthefollowingthreesetsofcomponentscavities,gatesandrunners,andcoolingsystem.LamandSeow2000andJinandLam2002achievedcavitybalancingbyvaryingthewallthicknessofthepart.Abalancefillingprocesswithinthecavitygivesanevenlydistributedpressureandtemperaturewhichcandrasticallyreducethewarpageofthepart.Butthecavitybalancingisonlyoneoftheimportantinfluencingfactorsofpartqualities.Especially,theparthasitsfunctionalrequirements,anditsthicknessesshouldnotbevariedusually.Fromthepointviewoftheinjectionmolddesign,agateischaracterizedbyitssizeandlocation,andtherunnersystembythesizeandlayout.Thegatesizeandrunnerlayoutareusuallydeterminedasconstants.Relatively,gatelocationsandrunnersizesaremoreflexible,whichcanbevariedtoinfluencethequalityofthepart.Asaresult,theyareoftenthedesignparametersforoptimization.LeeandKim1996aoptimizedthesizesofrunnersandgatestobalancerunnersystemformultipleinjectioncavities.Therunnerbalancingwasdescribedasthedifferencesofentrancepressuresforamulticavitymoldwithidenticalcavities,andasdifferencesofpressuresattheendofthemeltflowpathineachcavityforafamilymoldwithdifferentcavityvolumesandgeometries.Themethodologyhasshownuniformpressuredistributionsamongthecavitiesduringtheentiremoldingcycleofmultiplecavitiesmold.Zhaietal.2005apresentedthetwogatelocationoptimizationofonemoldingcavitybyanefficientsearchmethodbasedonpressuregradientPGSS,andsubsequentlypositionedweldlinestothedesiredlocationsbyvaryingrunnersizesformultigatepartsZhaietal.,2006.Aslargevolumepart,multiplegatesareneededtoshortenthemaximumflowpath,withacorrespondingdecreaseininjectionpressure.Themethodispromisingfordesignofgatesandrunnersforasinglecavitywithmultiplegates.Manyofinjectionmoldedpartsareproducedwithonegate,whetherinsinglecavitymoldorinmultiplecavitiesmold.Therefore,thegatelocationofasinglegateisthemostcommondesignparameterforoptimization.AshapeanalysisapproachwaspresentedbyCourbebaisseandGarcia2002,bywhichthebestgatelocationofinjectionmoldingwasestimated.Subsequently,theydevelopedthismethodologyfurtherandappliedittosinglegatelocationoptimizationofanLshapeexampleCourbebaisse,2005.Itiseasytouseandnottimeconsuming,whileitonlyservestheturningofsimpleflatpartswithuniformthickness.PandelidisandZou1990presentedtheoptimizationofgatelocation,byindirectqualitymeasuresrelevanttowarpageandmaterialdegradation,whichisrepresentedasweightedsumofatemperaturedifferentialterm,anoverpackterm,andafrictionaloverheatingterm.Warpageisinfluencedbytheabovefactors,buttherelationshipbetweenthemisnotclear.Therefore,theoptimizationeffectisrestrictedbythedeterminationoftheweightingfactors.LeeandKim1996bdevelopedanautomatedelectionmethodofgatelocation,inwhichasetofinitialgatelocationswereproposedbyadesignerandhentheoptimalgatewaslocatedbytheadjacentnodeevaluationmethod.Theconclusiontoagreatextentdependsmuchonthehumandesignersintuition,becausethefirststepofthemethodisbasedonthedesignersproposition.Sotheresultistoalargeextentlimitedtothedesignersexperience.DefinitionoffeaturewarpageToapplyoptimizationtheorytothegatedesign,qualitymeasuresofthepartmustbespecifiedinthefirstinstance.Thetermqualitymaybereferredtomanyproductproperties,suchasmechanical,thermal,electrical,optical,ergonomicalorgeometricalproperties.Therearetwotypesofpartqualitymeasuresdirectandindirect.Amodelthatpredictsthepropertiesfromnumericalsimulationresultswouldbecharacterizedasadirectqualitymeasure.Incontrast,anindirectmeasureofpartqualityiscorrelatedwithtargetquality,butitcannotprovideadirectestimateofthatquality.Forwarpage,theindirectqualitymeasuresinrelatedworksareoneofperformancesofinjectionmoldingflowingbehaviororweightedsumofthose.Theperformancesarepresentedasfillingtimedifferentialalongdifferentflowpaths,temperaturedifferential,overpackpercentage,andsoon.Itisobviousthatwarpageisinfluencedbytheseperformances,buttherelationshipbetweenwarpageandtheseperformancesisnotclearandthedeterminationoftheseweightingfactorsisratherdifficult.Therefore,theoptimizationwiththeaboveobjectivefunctionprobablywillnotminimizepartwarpageevenwithperfectoptimizationtechnique.Sometimes,improperweightingfactorswillresultinabsolutelywrongresults.Inindustry,designersandmanufacturersusuallypaymoreattentiontothedegreeofpartwarpageonsomespecificfeaturesthanthewholedeformationoftheinjectionmoldedparts.Inthisstudy,featurewarpageisdefinedtodescribethedeformationoftheinjectionparts.ThefeaturewarpageistheratioofthemaximumdisplacementofthefeaturesurfacetotheprojectedlengthofthefeaturesurfaceFig.1γLh1001whereγisthefeaturewarpage,histhemaximumdisplacementonthefeaturesurfacedeviatingfromthereferenceplatform,andListheprojectedlengthofthefeaturesurfaceonareferencedirectionparallelingthereferenceplatform.EvaluationoffeaturewarpageAfterthedeterminationoftargetfeaturecombinedwithcorrespondingreferenceplaneandprojectiondirection,thevalueofLcanbecalculatedimmediatelyfromthepartwiththecalculatingmethodofanalyticgeometryFig.2.Lisaconstantforanypartonthespecifiedfeaturesurfaceandprojecteddirection.ButtheevaluationofhismorecomplicatedthanthatofL.Simulationofinjectionmoldingprocessisacommontechniquetoforecastthequalityofpartdesign,molddesignandprocesssettings.TheresultsofwarpagesimulationareexpressedasthenodaldeflectionsonX,Y,ZcomponentWx,Wy,Wz,andthenodaldisplacementW.WisthevectorlengthofvectorsumofWxi,Wyj,andWzk,wherei,j,karetheunitvectorsonX,Y,Zcomponent.Thehisthemaximumdisplacementofthenodesonthefeaturesurface,whichiscorrelatedwiththenormalorientationofthereferenceplane,andcanbederivedfromtheresultsofwarpagesimulation.Tocalculateh,thedeflectionofIthnodeisevaluatedfirstlyasfollowswhereWiisthedeflectioninthenormaldirectionofthereferenceplaneofithnodeWix,Wiy,WizarethedeflectionsonX,Y,Zcomponentofithnodeα,β,γaretheanglesofnormalvectorofthereferenceAandBaretheterminalnodesofthefeaturetoprojectingdirectionFig.2WAandWBarethedeflectionsofnodesAandB.APPLICATIONANDDISCUSSIONTheapplicationtoacomplexindustrialpartispresentedinthissectiontoillustratetheproposedqualitymeasureandoptimizationmethodology.Thepartisprovidedbyamanufacturer,asshowninFig4.Inthispart,theflatnessofbasalsurfaceisthemostimportantprofileprecisionrequirement.Therefore,thefeaturewarpageisdiscussedonbasalsurface,inwhichreferenceplatformisspecifiedasahorizontalplaneattachedtothebasalsurface,andthelongitudinaldirectionisspecifiedasprojectedreferencedirection.Theparameterhisthemaximumbasalsurfacedeflectiononthenormaldirection,namelytheverticaldirection,andtheparameterListheprojectedlengthofthebasalsurfacetothelongitudinaldirection.ThematerialofthepartisNylonZytel101L30EGF,DuPontEngineeringPolymer.ThemoldingconditionsinthesimulationarelistedinTable1.Fig.5showsthefiniteelementmeshmodelofthepartemployedinthenumericalsimulation.Ithas1469nodesand2492elements.MPIisthemostextensivesoftwarefortheinjectionmoldingsimulation,whichcanrecommendthebestgatelocationbasedonbalancedflow.Gatelocationanalysisisaneffectivetoolforgatelocationdesignbesidesempiricalmethod.Forthispart,thegatelocationanalysisofMPIrecommendsthatthebestgatelocationisnearnodeN7459,asshowninFig.5.Thepartwarpageissimulatedbasedonthisrecommendedgateandthusthefeaturewarpageisevaluatedγ5.15,whichisagreatvalue.Intrialmanufacturing,partwarpageisvisibleonthesampleworkpiece.Thisisunacceptableforthemanufacturer.Thegreatwarpageonbasalsurfaceiscausedbytheunevenorientation

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