Investigation of Revolute Joint Clearances Created by an In-Mold Assembly Process的翻译.doc
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Proceedingsofthe2007IEEEMoC1.3InternationalSymposiumonAssemblyandManufacturingAnnArbor,Michigan,USA,July22-25,2007InvestigationofRevoluteJointClearancesCreatedbyanIn-MoldAssemblyProcessArvindAnanthanarayanan,ChandrasekharThamire,andSatyandraK.GuptaAbstract-Revolutejointsarefrequentlyusedinarticulatedthisjointarethefollowing:structures.Traditionally,suchajointisformedbyassembling1)Theframeisfirstmoldedinthefirststagemoldusingatwocomponents.Asanalternative,revolutejointscanbecreatedhighmelting-pointpolymer.insidethemoldusinganin-moldassemblyprocess.Thisprocess2)Theframeisinsertedintothesecondstagemoldnext.eliminatestheneedforpost-moldingassembly,thussignificantly3)Thesecondstagepartisthenmoldedinthecavityreducingthecycletimeandpartcount.Thefunctionalfomdrmthfissagprtndheecdsaeperformanceofarevolutejointdependsontheclearanceinthefomdrmthfissagprtndheecdsaejoint.Theclearanceinturndependsonthepartshrinkageandmold,usingalowermelting-pointpolymer.themolddeformationduringthemoldingprocess.Thepresence4)Uponcooling,thein-moldassembledpartwithaofapolymerpartduringthesecondmoldingstagemakesanin-revolutejointisejectedfromthemold.moldassemblyprocesssignificantlydifferentfromthetraditionalmoldingprocessduetothedifferenceinheattransferandFisstgdeformationcharacteristics.ThispaperpresentsexperimentalFisstgdataandapreliminarymodeltoexplainthedifferencesinclearanceproducedbyanAluminummoldandanAluminummoldwithanAcrylonitrilebutadienestyrene(ABS)insert.Our0tgdataindicatesthatthereisasignificantdifferencebetweentheScntgclearancesobservedfromthesetwodifferenttypesofmolds.Webelievethatclearancesproduceddependstronglyonthethermalhistoryoftheparts.Fig.1.Arevolutejointproducedusinganin-moldassemblyprocess1.INTRODUCTIONPolymersusedinthesecondstagearetypicallyofalowerI.INTRODUCTIONmeltingpointcomparedtothoseusedinthefirststage.ThisisINJECTIONmoldingisapopularmanufacturingprocessfortoensurethatthefirststagepolymerdoesnotmeltduringthemassproducingplasticparts.Usingthismethod,partsofinjectionofthesecondstagepart,whichwillpromoteanreasonablemechanicalstrength,surfacefinish,andcomplexadhesion-freerevolutejoint.Sincetheperformanceofthejointgeometrycanbeeasilyproduced.Moreover,partsproducedreliesheavilyontheclearancebetweentheconstituentparts,itdonotnormallyrequiresecondaryprocessing.Whenrelativeisimportanttoachievethedesignclearances.motionbetweensuchpartswarrantsassembly,theyareFigure2presentsasimplifiedillustrationofjointmanuallyassembledtocreatearticulatedjoints.TheassemblyclearancesformedinIn-MoldAssemblyprocesses.Thefirstprocess,however,canbetimeconsumingandlaborintensive,stagepartactsasamoldinsertduringthemoldingoftheIn-moldassemblyprocesspresentsanalternativewayofsecondstagepartandundergoesdeformationduetothecreatingarticulatedjoints.Inthisprocess,moldingoperationsprocesspressureandtemperatureinthesecondstage.Thisareperformedinmultiplemoldingstagesandassembledpartschangesthe effectivesizeofthecavityfromdtodin.Duringaredirectlyproducedinsidethemold,eliminatingtheneedforsolidification,shrinkageoccursinthesecondstagepartpost-moldingassemblyoperations.Theexpectedbenefitscausingitsfinaldimensiondptobedifferentfromdord,.includereducedcycletimeandpartcount,thelatterduetoFurther,astheinjectionpressureisremovedandcoolingeliminationoffasteners.occurs,thefirststagepartmayrecoversomeoftheFigure1showsarevolutejointthatcanbeproducedusingdmdpanin-moldassemblyprocess.ThestepsinvolvedinmoldinganuscriptreceivedDecember16,2006.rvindnanthanarayananisiththeechanicalEngineeringail:arvinda).authorphone:301-405-5306;e-mail:kuntaded)mechanicaldeformationandexpansionithasundergoneAuthorized licensed use limited to: GUILIN UNIVERSITY OF ELECTRONIC TECHNOLOGY. Downloaded on May 06,2010 at 04:22:46 UTC from IEEE Xplore. Restrictions apply. MoC1.3earlier.Thefinalclearancebetweenthetwopartsisthenprocessingconditionsonshrinkageoffouramorphousresinsdeterminedbythedeformationretainedbythefirst-stagepartandtwosemicrystallinematerialswasinvestigatedinastudyandtheshrinkageproducedinthesecond-stagepart.byJansenetal.1.AthermoelasticmodelwaspresentedthatThepresenceofapolymerduringthesecondmoldingstagedescribedtheshrinkageofamorphousmaterialswell,butmakesanin-moldassemblyprocesssignificantlydifferentoverpredictedthatofcrystallinematerials.Amodeldescribingfromasingle-stagemoldingprocess.Fortoolsteelortheanisotropicshrinkageofamorphous7andsemicrystallinealuminummolds,molddeformationcanbeconsideredtobe8polymerswasproposedbyKwonetal.7,8,basedonthenegligible,comparedtotheshrinkagevalues.Ontheotherfrozen-inorientationfunctionandelasticrecoverydeterminedhand,inIn-MoldAssemblies,thefirststageparthasastiffnessfromanon-linearviscoelasticconstitutiveequation.Theirlowerthantoolsteelandaluminumandhencemayundergopredictedresultswereinfairagreementwiththeexperimentalconsiderabledeformation,whichshouldbeconsideredinresults.Delaunayetal9examinedthepossibilityofmoldassessingclearances.Further,thermalbehaviorofpolymersisdeflectionduetoinjectionandpackingpressurechangingthedifferentfromthoseofmetalsandalloys,whichcanaffectbasicshapeofthecavityandhenceaffectingtheoverallcoolingofthesecond-stagepartssignificantly.Thisinturnshrinkage.BushkoandStokes10,11modeledthemechanicsmayaffecttheshrinkageandhenceneedstobeconsideredforofpartshrinkageandwarpageandresidualstressesandstrainsestimatingtheclearances.forthesolidificationofamoltenlayerofamorphousInthisstudy,clearancesformedduringthein-moldthermoplasticmaterialbetweencooledplates,assumingassemblyofaninjection-moldedrevolutejointcomprisingathermo-viscoelasticbehaviorforthematerial.Similarly,acylindricalsleeveandpinareexamined,withthesleevenumberofotherstudiesinvolvingshrinkage-predictionmodelsmoldedinthefirststageandthepininthesecond.Tobetterbasedonprocessparametersandmaterialvariableshavebeenunderstandtheprocess,pinsofsimilarsizewerealsomoldedreported.Thereaderisreferredto3-11foranelaborateinAluminummoldsdirectly,withoutthepolymersleeves.reviewofsuchstudies.WhileseveralimportantresultswereExperimentaldataispresentedforthreejointsizes.Aproducedfromtheseinvestigations,mostofthepublishedpreliminarytheoreticalmodelisproposedtounderstandthestudieswerefocusedonshrinkageofpolymersintoolsteeldifferencesobservedinclearanceswithanAluminummoldandAluminumorotherhardmetallicmolds.NoworkappearsandAluminummoldwiththepolymersleeve.tohavebeenreportedaddressingtheshrinkageofpolymersinsoftmolds.Thecurrentstudyattemptstoinitiatesuchastudy,II.RELATEDWORKinthecontextofin-moldassemblyprocessesforUsingin-moldassemblyforarticulateddevicesisamanufacturingrigid-bodyjoints.relativelynewtechnologyandtherearefewstudiesthatoutlineasystematicmethodologyfordesigningpartsandIII.EXPERIMENTALSETUPmolds.Priyadarshietal.1havepresentedamodelforAsdescribedearlier,anin-moldassemblytypicallyinvolvesdesigningIn-MoldAssembliesandmoldingprocessthatthepartmoldedinthefirststageasamoldinsertfortheenablesonetodesignthejointclearanceandvariationinthesecondstage(Fig.1).Toexamineclearancesobtainedinanjointclearancetomeetthefunctionalgoals.TheyoutlinedaIn-MoldAssembledjoint,wehaveutilizedcomponentssystematicapproachtoaidproductdesignersdeterminepartfeaturingcylindricalgeometrybecauseofaxisymmetrydimensionsandmaterialproperties,providingprovenmoldconsiderations.ThustomanufactureanIn-MoldAssembleddesigntemplatesforrealizingrevolute,prismatic,andrevolutejoint,acylindricalsleevewasfirstmoldedinthefirstsphericaljoints.Banerjeeetal.2haverecentlypresentedastage.Thispartwassubsequentlyusedasamoldinsertforthecomprehensivereviewofmulti-materialinjectionmoldingpininthesecondstage.Uponcooling,anIn-MoldAssembled(MMM)processes.Theypresentedanapproachforrevolutejointwasproduced.Themethodologyofmoldingthesystematicallyidentifyingpotentialmanufacturabilityissuespinintotheholeemployedinthestudyenabledustoexaminethatareuniquetosuchprocessesandproposeddesignrulestosituationswhererunningclearancesweredesired.avoidsuchproblems.TheiranalysisshowsthattherulesThepartstestedweremadefromlow-densityPolyethyleneapplicablefortraditionalsinglematerialmoldingneedtobe(LDPE).InordertocomparetheshrinkagebetweenhardandsuppressedormodifiedsometimesfortheMMMprocesses.softmolds,partsofdifferentsizesweremoldedinaluminumSeveralstudieshaveexaminedmodelingofin-moldaswellassleevesmadefromAcrylonitrilebutadienestyreneshrinkageofthermoplasticsinmetallicmolds.Asimplemodel(ABS).ThepartswereinjectionmoldedinMilacronsdescribingtheshrinkagebyfollowingthePressure-Volume-BabyplastInjectionmoldingmachine.ThemoldassemblyTemperature(PVT)diagramfromglasstransitiontoambientconsistedofanABSsleeveandanLDPEpinwithinanconditionsandobtainingthefinalproductvolumewasAluminumhousingforthein-moldassembliesandanLDPEconsideredinearlystudies3.JansenandTitomanlio4,5pininanAluminummoldforthesingle-stagemolding.ForexaminedtheeffectsofpressureandPoissonexpansiononthelattercase,AluminummoldsweremachinedandtheLDPEthicknessshrinkagethroughathermoelasticmodel.Effectofpartsweremoldedusingmoldsthuscreated.113Authorized licensed use limited to: GUILIN UNIVERSITY OF ELECTRONIC TECHNOLOGY. Downloaded on May 06,2010 at 04:22:46 UTC from IEEE Xplore. Restrictions apply. MoC1.3DimensionsofABSinsertsandAluminummoldsweremeasuredbeforeandaftermolding.TheLDPEpartsweremeasuredaftermoldingandsubsequentcoolingtoconstantscaledcoolingtimes.TemperaturesatlocationsindicatedinFig.4andFig.5weremeasuredforthreesetsof3/8andparts,usingaNationalInstrumentsdataacquisitionsystemthatincludedaPCI-4221dataacquisitioncard,SCXI1000and1102modules,andaTC-2095thermocouplepanel.FourK-typethermocoupleswereusedtomeasuretemperaturesforconfigurationsinvolvingABS,whilethreewereusedforthoseFig.3.MoldassemblyshownwiththeABSsleevenotinvolvingABS.Twowereattachedtothemoldsurfaces,TheprocessforobtainingtheABSsleevesinvolvedtheoneatapointcentrallylocatedwithinthemoldformeasuringfollowingsteps:MoldsformakingtheABSmoldinsertswerethetemperaturehistoryoftheparts,andafourthone,iffirstmachined.ABSsleeveswerethenmadeusingtheseapplicable,atthebaseoftheABSinsertforevaluationofheatmolds.Aluminummoldhousingsweremachinednext.Finallytransferthroughtheinsert.ThethermocoupleatthecentralmoldassembliesconsistingofABSmoldsandtheAluminumpointinthemoldwasheldinpositionusingarigidcopperhousingswereassembled(Fig.3).LDPEpartswerenexttubethroughwhichthethermocouplewaspassed.moldedusingthesemoldassemblies.Threesizesofpinswereusedintheexperiments,withIV.THEORYnominaldiametersof1/4,3/8,and/2.SinceclearancesAssemblyclearanceinin-moldassembliesisaffectedbyaobtainedusingdifferentmoldmaterialswereofprimaryvarietyofparameters,includingtheclearancebetweentheinterest,mostoftheothervariableswereheldconstantthroughmoldandtheinsert,physicalpropertiesofthematerials,scaling.Lengthswerekeptthesameasdiameterstoretainantemperatureandpressurehistories,geometry,andprocessaspectratioofunityfortheparts.Injectionpressureandparameters.Inthemodelproposedhere,weassumethatsuchtemperaturewerekeptconstantat700barsand1300C.Partanassemblyclearanceoccursduetothedeformationofthediameterwasusedasthescalinglengthandthediametertopolymerinsertattheelevatedpressureandtemperatureitisinjection-timeratioasthescalingvelocity.Coolingtimesweresubjectedto,thermalexpansionofthepolymerinsert,scaledbytheratioofthesquareofthediametertothethermalvolumetricshrinkageduetoenhancedcrystallizationfromdiffusivityofthepartmaterial.Thisresultedinconstantscaledreducedheattransfer,andvolumetricexpansionduetopressuresandcoolingtimesforallsizesused.Scaledthicknesssolidificationunderpressure.Forsimplicity,creepandforABSinserts,however,couldnotbemaintainedconstantrelaxationeffectsarenotincluded.Incylindricalgeometry,theduetomachiningconstraints.diametricalclearanceatanytimetafterthesolidificationhasendedmaythenbeexpressedasRC(0,Z,t)=,5(0,z,t)+fca(T,-T(O,z,t)+,r,-A,BP-PWA)ir.(1)_RIntheaboveexpression,Cisthediametricalclearance,Tistheinstantaneoustemperatureatthelocationofinterest,P,isthepressureduringsolidification,PistheinstantaneousFig.4PositionsofthermocouplesforAlmoldpressureinthepolymerpart,and5IisthepermanentdeformationretainedbytheABSinsert.TheremainingparameterspertaintoLDPE:aisthelinearthermalexpansioncoefficient,T,isthesolidificationtemperature,5,isthecrystallinityfactor,and/8isthecompressibility.Ristheradiusofthepinand8 andzaretheangularandaxialcoordinates,respectively.TheexpressionprovidedaboveissimilartothatdevelopedbyJansenandTitomanlio4,andTitomanlioandJansen5,andJansenetal.1,butdiffersfromtheirsduetothetermsrepresentingthedeformationoftheinsertandFig.5PositionsofthermocouplesforABSmoldtemperature-dependentcrystallinityduringcuring.FiveLDPEpartsweremoldedforeachsizewithandToevaluatedzandP,oneneedstoexaminetheflowwithouttheABSinserts.DOWPolyethylene722wasusedascharacteristicsofthemelt,whileheattransfershouldbethepartmaterial,HivalABSHG6NaturalXwasusedforABSexmndfrcluaigndTInteurntsdytheinserts,andanAluminum-basedalloywasusedforAluminum.wereperformedinthefollowingmanner.Firstthenon-moldpieces.isothermalflowproblemwassolvedtoevaluatethepressures114Authorized licensed use limited to: GUILIN UNIVERSITY OF ELECTRONIC TECHNOLOGY. Downloaded on May 06,2010 at 04:22:46 UTC from IEEE Xplore. Restrictions apply. MoC1.3occurringduringsolidificationandattheinsert.Heattransfernext.Thecoolingpolymer,surroundingABSsleeve,whenwasthenevaluatedtodeterminethethermalexpansionapplicable,andtheAlmoldwereconsidered.Incylindricalcomponentandshrinkageduetocrystallization.Fortheflowcoordinates,thegoverningequationforthisstepmaybeproblem,thegoverningequationsaregivenbywrittenas:(2a(pOcPT)=IadT1a3kaTakTd3at+V.(pV)=oat=rarKdrr2K)+aoaazKZXdt+(pv)(=V.-PI+/J(VV+VVT)+pb(3)(6)At+V.V(PV)=VJ_PI+,U(V)1+pbIntheaboveequation,;IisthemaximumpossiblepaT+V.VT=kV2T+k2+(4)crystallinityforthematerial,AHcistheexothermicheatofatcrystallizationperunitmass,and4istherelativecrystallinity.Whereyistherateofshearingstrain,4istherateofThegoverningequationsfortheABSsleeveandAluminumsolidification,cpisthespecificheatcapacity,kisthethermalmoldaresimilarto(6),withtheexceptionthattheheatconductivity,AHistheexothermicheatofpolymerization,uisgenerationtermduetochangeincrystallinityisassumedtobethedynamicviscosity,pisthedensity,andVisthevelocityabsent.Boundaryconditionsappliedwerenatural-convectionvector,bisthebody-forcevector.wasevaluatedusingaboundaryconditionsonallsidesofthemoldexceptatthemodelproposedbyKamalandRyan12becauseofitsabilitynozzlelocation,aperfectthermalcontactattheinterfacestomatchcloselywiththeexperimentaldata.Valuesforp,k,duringtheapplicationoftheholdingpressure,andaxisylmmetryattheaxis.Thermalcontactconductancewasandcpweretakenfromreferences13-15.,uwasassumedtoaxpsymetryathecais.Trcon.tactcnctnciwabeoftheollowingorm16:replacedbyaconvectionconditionwithconvectionbeofthefollowingform16:coefficientsapplicablefornaturalconvectionincylindricalA=ml8V,/i3r|)(5)annuli.ThiswasincludedtoaccountforthegapconductancemintheaboveequationrepresentstheNewtonianthatarisesonceshrinkagebegins.Aftertheejectiontime,viscosity,whereasnrepresentsthedeviationfromthenatural-convectionboundaryconditionwasappliedovertheNewtonianfluids,whichissmallerthanunityformostsurfaceofthepartandtheinnerdiameteroftheABSinsert.polymermelts14.0-dependencewaskeptintheequationtoexaminetheeffectThegoverningequationsweresolvedundertheassumptionofnon-uniformthermalcontactatthecontactregionforuseinofaxisymmetry.Bodyforceswereneglectedandafully-laterstudies.developedflowwasassumedattheflowfront.BoundaryThegoverningequationwasintegratednumericallyusingconditionsassumedwereno-slipconditionattheinterfacetheAlternatingDirectImplicit(ADI)method18subjecttobetweentheinsertandthepart,axisymmetryalongtheaxis,theboundaryandinitialconditions.Initially,zeropressurebeingatmosphericattheflowfront15,andacrystallizationwasassumedandthetemperatureswereconstantflowrateconditionatz=0,determinedfromcalculatedbasedonaninitialestimateoftheproperties.Afterexperimentalconditions.Convectionboundaryconditionseachtimestep,propertieswereadjustedtomatchthewereassumedforthetemperaturefieldoutsideofthetemperaturedistributioncalculated.ThisprocesscontinuedAluminummoldandatthemoldfront,whiletheprocessinguntilsteadystatewasreached.Steadystatesolutionsweretemperaturewasassumedtobehelduntilthegateshut-offconsideredconvergedwhenthemaximumchangeinthelocaloccursatz=0.valuesofTandineachoftheglobalenergyratesattheBecauseoftheenergydissipationtermintheenergyexteriorsurfacesbecamelessthan10-4percent.Gridsizewasequation,thevelocityprofileandpressureswereinitiallyrefinedwhenanyoftheaboverequirementswasnotsatisfied.guessedandthetemperaturefieldwascalculated.AnewGrid-independencewascheckedforallthreesizesusedintheviscosityprofilewasthencalculatedusingthenewexperiment.Spatialresolutionwasvariedfrom21to101intemperatureprofile.Thelinearmomentumequationwasthezdirection,from21to81intherdirection,andfrom17tosolvednexttocalculatethenewvelocityprofiles.Newton-97inthe0direction.GridindependencewasnotedforgridsRaphsonmethod17wasappliedforconvergenceoffinerthan51x41x41.Forthecalculationsconsideredhere,apressuresandthevelocityprofilesforthecalculatedgridsizeof61x61x49wasused.temperaturevalues.Withthenewvaluesforthevelocityfield,Temperaturehistoriescalculatedatthecenteroftheinjectedthetemperaturefieldwascalculatedagain,andtheprocedurepartwerecomparedwiththosemeasured.Curingkineticswerewasrepeateduntilconvergencecriteriaweremetforboththethenadjustedinanattempttomatchthetemperatureprofilestemperatureandvelocityfields.Thesolutionwasthenthroughaniterativeprocess.Oncetheprocesswasstabilized,marchedinthezdirectioninthemannerdescribedabove,tillpropertyvalueswereadjustedtoaccountforthechangeintheendofthecavitywasreached.Fillingtimesandpressurecrystallinityin(6),andthecrystallinityvaluesandpropertydistributionswerenotedforuseintheclearancecomputationsvalueswerebothreadjustediterativelyuntilthecalculatedatalaterstage.valuesmatchedthemeasuredvaluestowithin0.1%oftheToobtainthethermalhistory,energyequationwassolvedmeasuredvalues.115Authorized licensed use limited to: GUILIN UNIVERSITY OF ELECTRONIC TECHNOLOGY. Downloaded on May 06,2010 at 04:22:46 UTC from IEEE Xplore. Restrictions apply. MoC1.3Lastly,pressurehistoriescalculatedintheflowcalculationscoveredbyanABSinsert.HeatrejectionratesherearelowerandholdingpressureappliedwereusedtocomputethethantheformercaseduetotheinferiorthermalpropertiesofelastoplasticdeformationencounteredbythesurroundingABS,whichthensuggeststhatdensificationandahighermaterial.Ahollowaxisymmetriccylinderinplanestrainwasshrinkagecould occurwithintheLDPEpart.Thisinturnassumed,withtheendsassumedtoberestrained.AMohr-affectsthecoolingratesandthethermalpropertiesofLDPECoulombfailurecriterionwasassumedtobevalid.Intheduetodifferencesincrystallinity.Thus,thecalculationswouldelasticzone,thestrain-displacementandlinear-momentumnotmatchthemeasurements,unlesschangesinthermalequationsaregivenby:propertiesduetochangesincrystallinitywereincluded.durTABLE1AVERAGEABSOLUTEANDRELATIVECLEARANCESdu,E,11_r(7)MeasuredAverageFrIAbsoluteClearance(in)AverageRelativeClearance(%)rNominalMeasuredCalculatedDia.(in)MoldMoldandwithwithdO*r+Ur(c8AlMoldwithAlABSAlABS+=0(8)MoldABSInsertMoldInsertMoldInsertdrrTodeterminetheextentoftheplasticzonethatmayoccur0250.0070.010247402-asaresultofyielding,theMohr-Coulombfailurecriterionfor0.3750.0110.0132.833.613.094.17themaximumprincipalstressisinitiallysubstitutedintothe0.50.0150.0172.933.463.444.53linear-momentumbalanceequation,andintegrated.TheOncechangesinspecificvolumeweremadeaccountingforboundaryconditionofaveragedinternalpressureattheinnerthechangesinpackingandincorporatedintoequation(1),radiuswasappliedtodeterminetheradialstressdistributioninincludingtheothercomponentscontributingtotheclearanceplasticzone.UsingtheMohr-Coulombcriterionagain,thementionedthere,clearancescalculatedforthe0.375and0.5circumferentialstressdistributionintheplasticzonewasnextsizeswerecomparedtothemeasuredvalues.Computedvaluesdetermined.Todeterminetheboundarybetweentheelasticcomparedfavorablywiththemeasuredvaluesforthe0.375andplasticzones,theelasticstresseswereequatedtothesize,withmeasuredaveragesbeing2.83%(Almolds)andstressesintheplasticzoneandsolvedfortheradiusonthe3.61%(ABSmolds),againstthecalculatedaveragesof3.09%boundary.Usingthestrain-displacementrelationships,radialand4.17%,respectively.Clearancevaluescomputedfor0.5displacementsattheinnersurfacewerefinallyobtained.Allsize,however,exhibitedlargedeviationsfromthemeasuredtheindividualcomponentsinvolvedinthecalculationofvalues.clearancewerethenaddedusing(1)andcomparedwiththeClearancescomputedexhibitthesametrendasthemeasuredvalues.measuredvalues,predictinghigherclearancesforassembliesmadeusingABSinserts.WhilethemodeloverpredictstheV.RESULTSANDDISCUSSIONclearancesbyvaluesupto31%(about18%forAlmolds),itpromisestobeausefultool,oncemoreparametricstudiesareAveragerelativeclearancesmeasuredandcalculatedareshowninTable1.Relativeclearanceconsideredhereistheperformedtoevaluatethefunctionalformofthefinalpncorrelationandthusenhanceitspredictivecapability.physicalclearancescaledbythemeasuredvalueofthepinPlationoftheinsertsdenotardiameter,expressedasapercentage.Relativeclearanceswere.analyzedusinga2-wayANOVAprocedure19.Resultsasignificantfactor,accountingtolessthan7%ofthetotalclearancesobserved.Sincethemodeldoesnotassumeansigndficanteybethatntheratieclaresmeasured.dutifferinterferencefitattheouterdiameter,thisresultmaynotbesignificantlybetweenthetwocases(p0.05).Multiplevaifolhaenedobutexmndovalidforallthecasesandneedstobefurtherexamined.ForcomparisonsusingaTukey-Kramerprocedure19shownosignficatdffernceetwenszeswithneahmteril,eometrieswhereouterdiameteroftheinsertsiSconstrained,significantdifferencebetweensizeswithineachmaterial,threutninefcaprsuewlctanetratheresultinginterfacialpressurewillactasanexternalwhichmaybeattributedtothescalingincorporatedintothe.oexperimentaldesign.Comparisonofmeansbetweenthetwopeuonheinsertcandiasraninthemoldandwillhavetobeconsideredinthecalculations.moldsforindividualsizesindicateasignificantdifferenceinmeasuredrelativeclearancesforallthreesizes.Fromesinperspective,cstaieintheSampeteperaurehistriesmeasredalontheaxisforexperimentsinthisstudyappearattractive,astheyareintherangeofrunningfits.Forexample,ANSIB4.220providestwopinsofsize0.375areshowninFig.6andFig.7.HeatthelimitsofaclearanceorrunningfitforanominalsizeofdissipationoccursrelativelyquicklyfortheLDPEspecimen0.375tobe-40.003,0.00ComparingthiswiththemeanmdedirectlyintheAluminummold(fig.6).Heattransferclearancevaluesof0.013measuredin0.375ABSLPcalculationsperformedforpinsmadeinAluminummoldsasebisitiseietta.hnmodasmlrcsepredictthetemperaturehistorywell,withoutrequiringmanyappeartobecapabl3of0prducingooaruingfitsthoughA-4-1-appeartobe-lcapablof,V-rdulngooTunisThoughiterationstoaccountforchangesincrystallinity.Incontrast,thprdcin.rmtemdlapaoboprnFig.7showsamuchslowercoolingrateforaLDPEpinfvrbywthxeietlosrain,mn116Authorized licensed use limited to: GUILIN UNIVERSITY OF ELECTRONIC TECHNOLOGY. Downloaded on May 06,2010 at 04:22:46 UTC from IEEE Xplore. Restrictions apply. MoC1.3improvementsarepossible.Inthemodel,flow-inducedACKNOWLEDGEMENTScrystallization,elasticrecovery,andmorerealisticthermalThisresearchhasbeensupportedinpartbyNSFgrantcontactconductancevaluesneedtobeincorporated.DMI0457058andtheArmyResearchOfficethroughMAVAxisymmetryandplanestrainassumptionsneedtoberelaxedMURIProgram(GrantNo.ARMYW91lNF0410176).formoreaccurateclearancepredictions.ThermalcontactOpinionsexpressedinthispaperarethoseoftheauthorsandresistance,whichisbasedonjointclearance,needstobedonotnecessarilyreflectopinionsofthe sponsors.evaluatedmoreaccurately,bymeasuringtemperaturesatmorelocationsandaccountingfornon-uniformcontact.ThiscanbeREFERENCESanimportantparameter,asindicatedinthestudybySridharet1A.K.Priyadarshi,S.K.Gupta,R.Gouker,F.Krebs,M.Shroeder,andS.al.21.MoreexperimentalresultsarethusneededtofurtherWarth.Manufacturingmulti-materialarticulatedplasticproductsusingvalidatetheproposedmodel.in-moldassembly.InternationalJournalofAdvancedManufacturing100Technology,32(3-4):350-365,March,2007.902A.G.Banerjee,X.Li,G.Fowler,andS.K.Gupta,Incorporating80manufacturabilityconsiderationsduringdesignofinjectionmoldedo70multi-materialobjects,ResEngDesign,inprint.o603A.I.IsayevandT.Hariharan,Volumetriceffectsintheinjection50moldingofpolymers,Pol.Engg.andSci.,April1985,Vol.25,No.5X404K.M.B.JansenandG.Titomanlio,EffectofPressureHistoryonE30ShrinkageandResidualstresses-InjectionMoldingwithconstrained20Shrinkage,Pol.Engg.andSci.Mid-August1996,Vol.36,NO.15105G.TitomanlioandK.M.B.Jansen,In-MoldShrinkageandStress10.PredictioninInjectionMolding,Pol.Engg.andSci.Mid-August1996,0.0110.0120.0130.0140.0150.0160.0170.0180.01Vol.36,NO.15.Time(sec)6K.M.B.Jansen,D.J.VanDijk,andM.H.Husselman,EffectofFig.6TemperatureHistoryfora0.375LDPEspecimenmoldeddirectlyinprocessingconditionsonshrinkageininjectionmolding,Pol.Engg.anAluminummoldandSci.,May1998,Vol.38,No.51207KeehaeKwon,A.I.Isayev,K.H.Kim,TowardaViscoelasticModeling100ofAnisotropicShrinkageinInjectionMoldingofAmorphousPolymers,JournalofAppliedPolymerScience,Vol.98,2300-2313,2005a808KeehaeKwon,A.I.Isayev,K.H.Kim,TheoreticalandExperimentalStudiesofAnisotropicShrinkageinInjectionMoldingofX60-SemicrystallinePolymers,Pol.Engg.andS
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