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外文翻译对聚氨酯反应注射成型(RIM)工艺的分析和优化.pdf

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外文翻译对聚氨酯反应注射成型(RIM)工艺的分析和优化.pdf

AnalysisandoptimizationofapolyurethanereactioninjectionmoldingRIMprocessusingmultivariateprojectionmethodsF.Yacoub,J.F.MacGregorChemicalEngineeringDepartment,McMasterUniversity,1280MainStreetWest,JHE374,Hamilton,ON,CanadaL8S4L7Received13April2002receivedinrevisedform20August2002accepted25August2002AbstractPrincipalcomponentanalysisPCAandprojectiontolatentstructurePLSmethodsareusedwithindustrialdatatosuccessfullydiagnoseseveraldifferentproblemsarisinginthemanufacturingofrigidpolyurethanefoaminsulationpanels.ThePCAandPLSmodelsareusedtorevealthespatialvariationofqualityvariablesthroughoutthefoamedproduct,andtheirrelationswiththeprocessvariables.DesignedexperimentsareperformedinthekeyprocessvariablesidentifiedfromthePCAstudiesandtheresultsareusedtooptimizetheprocess.D2002ElsevierScienceB.V.Allrightsreserved.KeywordsPolyurethaneReactioninjectionmoldingProjectionmethod1.IntroductionInthelasttwodecades,chemicalprocesses,likemanyotherindustries,havebeengoingthrougharevolutionintheirdatacollectionsystems.Machineintelligence,immensedatastoragecapacity,andhighthroughputdataacquisitionsystemshavedriventhecostperdatapointdowntoaverylowlevel.Massesofdataarenowavailablebymeasuringprocessvariablesaswellasqualityvariableseitheronlineorinqualitycontrollabs.ProjectionmethodssuchasprincipalcomponentanalysisPCAandprojectiontolatentstructurePLSprovideawaytohandlethehighlycorrelateddatacollectedbythesesystems.Inaddition,theydealeffectivelywithmultipleresponsevariablesandwithmissingdata,andtheyprovideagoodtooltoextractandhighlightthesystematicvariationinthesemultivariatedatasets.Themostimportantpropertyofprojectionmethodsisthecapabilitytoreducethemultivariatedimensionofaproblemintoalowdimensionalspace,usuallyconsistingofthreetofourdimensions.TheSIMCA_P8.0softwareofUmetricswasusedforthePCA/PLSanalysesperformedinthiswork.Thefocusofthisstudyistheapplicationofthemultivariateprojectionmethodsforthediagnosisandanalysisofapolyurethanereactioninjectionprocess.Themainobjectivesofthisresearcharetounderstandthespatialvariationintheprocess,correctthecausesofthisvariation,andoptimizethequalityvariables.01697439/02/seefrontmatterD2002ElsevierScienceB.V.Allrightsreserved.PIIS0169743902000886Correspondingauthor.Tel.19055259140fax19055211350.Emailaddressmacgregmcmaster.caJ.F.MacGregor.www.elsevier.com/locate/chemometricsChemometricsandIntelligentLaboratorySystems65200317–332.ThemechanismofpolyurethaneformationTheprocessofinsulatingrefrigeratorsinvolvesreactioninjectionmoldingRIMtoformpolyurethanefoam.Eachrefrigeratorcavityservesasachemicalreactorwheretwodifferentsetsofreactionstakeplacesimultaneously.Oneisthepolymerizationreaction,inwhichsuchbondsasurethaneandureamaybeformed.Theotheristhefoamingreaction,whichinvolvestheevolutionofcarbondioxideandthevaporizationofblowingagent.Chemicalsflowfromdaytanksthroughheatexchangerstocontrolthetemperatureandthenintothemixheadunderhighpressuretoinsuregoodmixingandthenthemixtureisinjectedinsidethemold1.Inanyreactingpolyurethanefoam,manyphysicalandchemicalchangesoccur,andthesevarywithtimeandextentofreactionasshowninFig.1.Thetemperaturewithinthefoamrisesasthereactionproceedsand,becausethefoamisagoodthermalinsulator,temperaturegradientsariseandcanresultinmanyproblemsasdiscussedlaterinthepaper.Ingeneral,themanufactureofpolyurethanerigidfoamcanbecharacterizedbythefollowingfourstages2.IMixingstep,wheretheMasterbatchwhichcontainthepolyol,acatalyst,asurfactantandablowingagentismixedunderhighpressurewiththeisocyanateinthemixhead.IICreamperiod,inwhichthetemperatureincreasecausedbytheexothermicchemicalreaction,issufficienttopromotetheactivityoftheblowingagent.IIIRiseperiod,inwhichtheblowingagentevaporatesraisingthefoamuntilasufficientrigidityisreachedbyeitherfreerisingorwhenthemoldisfilled.IVPostcuringstep,inwhichthepolymeristreatedbyahightemperatureforacertaintime.Themechanicalsystemconsistsofarotarydrumunitthathasasixstationrotaryframe.Foamfixturesareplacedineachframestation.Refrigeratordoorsorothercavitiestobefoamedareplacedinsidethefixtureswheretheyarepreheated,theninjectedwiththereactionmixtureinonepositiononthedrumunit.Oncefoamed,thedrumunitrotatesthefixturethroughfiveotherpositionsforcuring,whiletheotherpositionsarefoamed,andeventuallyreturnsthefixturetothefoamposition.EachdrumunithastwoFig.1.Polyurethanefoamformation.F.Yacoub,J.F.MacGregor/ChemometricsandIntelligentLaboratorySystems65200317–3318polyurethanefoammixheadcarriages.Eachcarriagefoamsadifferentdoor.2.1.ProblemdescriptionTheinstabilityofthefoamingprocessandthecomplexityofcontrollingthequalityvariablescreatedtheneedandmotivationforthiswork.Twoproblemsonthisprocessarediscussedseparatelyastheyaroseatdifferenttimes.Thefirstprojectwastooptimizethefunctionalityofthepolyurethanefoampanelsexpressedbythespatialvariationofitsthermalconductivityanddensity.Theinsulationfunctionofthefoam,measuredbythermalconductivitykfactor,isconsideredasavitalvariabletobecontrolled.Ithasadirecteffectontherefrigeratorperformanceandenergyconsumption.Intheory,whenthemasterbatchismixedwiththeisocyanateatacertaintemperature,theblowingagentboils,andcreatesavaporthatblowsthefoamandreducesthedensity.Inrigidfoam,thecellsformedbytheblowingagentreducethetransmissionofheat.Thelowerthekfactoris,thebettertheinsulationandtherefrigeratorperformance.Density,whichisanindicationoffoamstrength,isimportantinkeepingthestructuralrigidityoftherefrigerator.Itisaresultofthepressurethatthevaporfromtheblowingagentsexertsinthecell.Thecellgaspressurecausesthefoamtoresistshrinkage.Inordertoreducethescraprateofthisprocess,unacceptablevoidsandleakshavetobeminimized.TheobjectiveofthesecondprojecttreatedinthispaperistominimizethedistortionphenomenainthefoamedpanelsknownasOuterBowOB.OuterBowismainlycausedbythemovementrestrictionofthesteelandABSplasticpanels.Thepanelsareunabletoexpandorcontractrelativetoeachothersincethedistanceseparatingthemisrelativelysmall.Ifmovementistooccur,itwillresultinthewarpingofthepanelsorsheardeformation.2.2.QualitymeasurementsQualityvariablesaremeasuredofflineonaweeklybasisinqualitycontrollabs.Theupperspecificationlimitofthethermalconductivityisbasedonenergycalculations,andthelowerspecificationlimitofdensityisdefinedastheminimumdensitytomaintainstructuralstrength.Allmeasurementsareperformedateightlocationsaroundthefoamedpanels.Thecriterionistohaveallsampleswithinthespecifiedcontrollimits.ThermaldistortionismeasuredusingaCoordinateMeasuringMachineCMMbydefiningaplanethatpassesthroughpointslocatedinthecornersofthepanelandmeasuresthedeviationfromthisplaneatseveralpointsacrossthepanelsurfacetodeterminetheshapeandmagnitudeofsurfacebow.Thefollowingqualityvariablesaremeasured2.3.ProcessvariablesProcessvariableswereselectedandretrievedfromthedatabase.Theanalysiswasperformedonsixdifferentfixturesfromproductiontounderstandthevariationbetweenfixturesandtheeffectofchangesintheprocessvariables.AsummaryofprocessvariablesusedintheanalysisandthecorrespondingnomenclaturepresentedinthepaperisgivenasfollowsTimetotestT_TAmbienttemperatureA_TMasterbatchdensityMB_DMasterbatchflowMB_FIsocyanateflowI_FRatiobetweenMasterbatchandisocyanateMB/IIsocyanatepressureI_PMasterbatchpressureMB_PMixheadpressureMH_PShotsizeSSIsocyanatetemperatureI_TMasterbatchtemperatureMB_TIsocyanatetemperatureatmixheadI_T_MHMasterbatchtemperatureatmixheadMB_T_MHSurfactanttypeSBlowingagenttypeBFixturecoretemperatureCore_TFixturesidewalltemperatureSidewall_TFixturepreheattemperaturePreheat_TKKfactorvaluesatvariousspatiallocations1–8DDensityvaluesatvariousspatiallocations1–8VoidsIdentifiedbysinkmarksintheoutersteelLeaksIdentifiedvisuallyFacebowMaximumwarpageofthefacefoamedobjectsSidebowMaximumwarpageofthesidefoamedobjectsF.Yacoub,J.F.MacGregor/ChemometricsandIntelligentLaboratorySystems65200317–33193.Problem1eliminatingspatialvariationinthermalconductivityanddensity3.1.PrincipalcomponentanalysisonqualityvariablesYsThemainobjectivesbehindfittingaPCAmodelontheYsaretounderstandthespatialpatternsandthecorrelationstructureamongthevariables.Measurementsmadeonatotalof64setsofpanels.Threeprincipalcomponentsaresignificantbycrossvalidation3andtheyexplain76ofthevariation.SomeoutliersareevidentinthescoreplotsandresidualDmodXplotsshowninFigs.2and3,respectively.Outliersareconsideredveryinterestingobservationsthatholdvaluableinformationthatcanbeunderstoodusingcontributionplots.Furtheranalysisandinterpretationsoftheseoutlierswillbediscussedinalatersection.Theloadingplot,showninFig.4,revealsthattherearetwomaingroups.Thermalconductivityispositivelycorrelatedwithleaksandnegativelycorrelatedwithbothdensityandvoids.Furthermore,fromtheloadingplotFig.4,apatterndistributionofdensityandthermalconductivityvariationinsidethecavityandinrelationtotheaveragevalueisevident.Itisworthnotingthatattheinjectionsidelocations1and8thedensitywashigherandthekfactorwaslowerthanaroundtheedgesofthemold.3.2.ProjectiontolatentstructurePLSbetweenfixturesandqualityvariablesInordertounderstandtheeffectofthesixfixturesusedinproduction,aPLSmodelisbuilttorelatetheeventofusingaspecificfixturetothequalityvariables.TheXmatrixconsistedofsixindicator0,1variablesindicatingthepresenceorabsenceofanyparticularfixtureduringaninjection.TheYmatrixconsistedoftheaverageKfactor,theaveragedensity,voids,andleaksforeachofthe64panels.ThePLSmodelexplained72.5thevariationRy2intheYsusingonlytheinformationonwhichfixturewasusedforthemoldingprocess,implyingthattheFig.2.t1–t2scoresfromPCAonthequalityvariablesYs.F.Yacoub,J.F.MacGregor/ChemometricsandIntelligentLaboratorySystems65200317–3320

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