注塑模具英文翻译.docx

注塑模具英文翻译.docx

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注塑模具英文翻译

Minimizingmanufacturingcostsforthininjectionmoldedplasticcomponents

1.Introduction

Inmostindustrialapplications,themanufacturingcostofaplasticpartismainlygovernedbytheamountofmaterialusedinthemoldingprocess.

Thus,currentapproachesforplasticpartdesignandmanufacturingfocusprimarilyonestablishingtheminimumpartthicknesstoreducematerialusage.

Theassumptionisthatdesigningthemoldandmoldingprocessestotheminimumthicknessrequirementshouldleadtotheminimummanufacturingcost.

Nowadays,electronicproductssuchasmobilephonesandmedicaldevicesarebecomingevermorecomplexandtheirsizesarecontinuallybeingreduced.

Thedemandforsmallandthinplasticcomponentsforminiaturizationassemblyhasconsiderablyincreasedinrecentyears.

Otherfactorsbesidesminimalmaterialusagemayalsobecomeimportantwhenmanufacturingthinplasticcomponents.

Inparticular,forthinparts,theinjectionmoldingpressuremaybecomesignificantandhastobeconsideredinthefirstphaseofmanufacturing.

Employingcurrentdesignapproachesforplasticpartswillfailtoproducethetrueminimummanufacturingcostinthesecases.

Thus,tacklingthinplasticpartsrequiresanewapproach,alongsideexistingmolddesignprinciplesandmoldingtechniques.

1.1Currentresearch

Today,computer-aidedsimulationsoftwareisessentialforthedesignofplasticpartsandmolds.Suchsoftwareincreasestheefficiencyofthedesignprocessbyreducingthedesigncostandleadtime[1].

Majorsystems,suchasMoldFlowandC-Flow,usefiniteelementanalysistosimulatethefillingphenomena,includingflowpatternsandfillingsequences.Thus,themoldingconditionscanbepredictedandvalidated,sothatearlydesignmodificationscanbeachieved.Althoughavailablesoftwareiscapableofanalyzingtheflowconditions,andthestressandthetemperaturedistributionconditionsofthecomponentundervariousmoldingscenarios,theydonotyielddesignparameterswithminimummanufacturingcost[2,3].

Theoutputdataofthesoftwareonlygiveparametervaluerangesforreferenceandleavesthedecisionmakingtothecomponentdesigner.Severalattemptshavealsobeenmadetooptimizetheparametersinfeeding[4–7],cooling[2,8,9],andejectionTheseattemptswerebasedonmaximizingtheflowabilityofmoltenmaterialduringthemoldingprocessbyusingempiricalrelationshipsbetweentheproductandmolddesignparameters.

SomeresearchershavemadeeffortstoimproveplasticpartqualitybyReducingthesinkmark[11]andthepartdeformationaftermolding[12],analyzingtheeffectsofwallthicknessandtheflowlengthofthepart[13],andanalyzingtheinternalstructureoftheplasticpartdesignandfillingmaterialsflowsofthemolddesign[14].Reifschneider[15]hascomparedthreetypesofmoldfillingsimulationprograms,includingPartAdviser,Fusion,andInsight,withactualexperimentaltesting.Alltheseapproacheshaveestablishedmethodsthatcansavealotoftimeandcost.However,theyjusttackledthedesignparametersoftheplasticpartandmoldindividuallyduringthedesignstage.Inaddition,theydidnotprovidethedesignparameterswithminimummanufacturingcost.

Studiesapplyingvariousartificialintelligencemethodsandtechniqueshavebeenfoundthatmainlyfocusonoptimizationanalysisofinjectionmoldingparameters[16,17].Forin-stanceHeetal.[3]introducedafuzzy-neuroapproachforautomaticresettingofmoldingprocessparameters.Bycontrast,Helpsetal.[18,19]adoptedartificialneuralnetworkstopredictthesettingofmoldingconditionsandplasticpartqualitycontrolinmolding.Clearly,thedevelopmentofcomprehensivemoldingprocessmodelsandcomputer-aidedmanufacturingprovidesabasisforrealizingmoldingparameteroptimization[3,16,17].Moketal.[20]proposeahybridneuralnetworkandgeneticalgorithmapproachincorporatingCase-BasedReasoning（CBR）toderiveinitialsettingsformoldingparametersforpartswithsimilardesignfeaturesquicklyandwithacceptableaccuracy.Mok’sapproachwasbasedonpastproductprocessingdata,andwaslimitedtodesignsthataresimilartopreviousproductdata.However,norealR&Defforthasbeenfoundthatconsidersminimizingmanufacturingcostsforthinplasticcomponents.

Generally,thecurrentpracticalapproachforminimizingthemanufacturingcostofplasticcomponentsistominimizethethicknessandthedimensionsofthepartattheproductdesignstage,andthentocalculatethecostsofthemolddesignandmoldingprocessforthepartaccordingly,asshowninFig.1.

Thecurrentapproachmaynotbeabletoobtaintherealminimummanufacturingcostwhenhandlingthinplasticcomponents.

1.2ManufacturingrequirementsforatypicalthinplasticcomponentAsatestexample,thetypicalmanufacturingrequirementsforathinsquareplasticpartwithacenterhole,asshowninFig.2,aregiveninTable1.

Fig.1.Thecurrentpracticalapproach

Fig.2.Testexampleofasmall

plasticcomponent

Table1.Customerrequirementsfortheexamplecomponent

2.Thecurrentpracticalapproach

AsshowninFig.1,thecurrentapproachconsistsofthreephases:

productdesign,molddesignandmoldingprocessparametersetting.Amainobjectiveintheproductdesignistoestablishthephysicaldimensionsofthepartsuchasitsthickness,widthandlength.Thephasesofmoldedsignandmoldingsubsequentlytreattheestablishedphysicaldimensionsasgiveninputstocalculatetherequireddetailsformoldmakingandmoldingoperations.

Whenapplyingthecurrentpracticalapproachfortacklingthegivenexample,thekeyvariablesarehandledbythethreephasesasfollows:

Productdesign

*Establishtheminimumthickness（height）HP,andthencalculatethematerialcost.HPisthentreatedasapredeterminedinputforthecalculationofthecostsofmold

designandmoldingoperations.HP

Molddesign

*Calculatethecoolingtimeforthedeterminedminimum

thicknessHPinordertoobtainthenumberofmoldcavitiesrequired.Themoldmakingcostisthenthesumofthecoststomachinethe:

–Depthofcutting（thickness）HP

–Numberofcavities

–RunnerdiameterDR

–GatethicknessHG

Moldingprocess

*DeterminetheinjectionpressurePin,andthenthecostofpowerconsumption

●Determinethecoolingtimetco,andthenthecostofmachineoperations.Theoverallmoldingcostisthesumofthepowerconsumptioncostandmachineoperatingcost.

Thetotalmanufacturingcostisthesumofthecostsofplasticmaterial,moldmakingandmoldingoperations.Notethat,inaccordancewithtypicalindustrypractice,allofthefollowingcalculationsareintermsofunitcosts.

2.1Productdesign

Thisisthefirstmanufacturingphaseofthecurrentpracticalapproach.ThedesignminimizesthethicknessHPoftheplasticcomponenttomeetthecreeploadingdeflectionconstraint,Y（<1.47mmafter1yearofusage）,andtominimizeplasticmaterialusagecostCm.MinimizingHPrequires[21]:

Figure3plotschangesinHPthroughEqs.1and2.Thegraphsshowthatthesmallestthicknessthatmeetsthe1.47mmmaximumcreepdeflectionconstraintis0.75mm,withaplasticmaterialcostof$0.000483558/unitandabatchsizeof200000units.

Thisthicknesswillbetreatedasagiveninputforthesubsequentmoldedsignandmoldingprocessanalysisphases.

2.2Molddesign

2.2.1Determinationofcoolingtime

Thedesiredmoldtemperatureis25C.Thedeterminedthicknessis0.75mm.Figure4showsthecoolingchannelslayoutfollowingstandardindustrypractices.Thecoolingchanneldiameterischosentobe3mmforthisexample.

From[22],thecoolingtimetco:

Andthelocationfactor,

BysolvingEqs.3and4,andsubstitutingHP=0.75mmandthegivenvaluesofthecoolingchanneldesignparameters,thecoolingtime（3.1s）isobtained.

Thecycletimetcycle,givenbyEq.5,isproportionaltothemoldingmachineoperatingcosts,andconsistsofinjectiontime（tin）,ejectiontime（tej）,drycycletime（tdc）,andcoolingtime（tco）.

2.2.2DeterminationofthenumberofmoldcavitiesIngeneral,thecostofmoldmakingdependsontheamountofmachiningworktoformtherequirednumberofcores/cavities,runners,andgates.Thegivenexamplecallsforatwo-platemold

Fig.3.

DeflectionandplasticmaterialscostsversuspartthicknessFig.4.Coolingchannellayoutthatdoesnotrequireundercutmachining.Therefore,themachiningworkforcuttingtherunnersandgatesisproportionaltotheworkinvolvedinformingthecores/cavitiesandneednotbeconsidered.Intheexample,moldmakingcostCmmisgovernedby（n,HP）.

Generally,theminimumnumberofcavities,Nmin,ischosentoallowfordeliveryofthebatchofplasticpartsontime图3。

Aftersubstitution

whichisroundedTon=3,sincethemoldcannotcontain2.64cavities.Themachineoperationcapacityandthelead-timeofproductionintheexamplearegivenas21.5h/dand21d,respectively.Moreover,asmentionedintheprevioussection,thecycletimeisdirectlyproportionaltothepartthicknessHP.AcurveofbatchsizeagainstthicknessisplottedinFig.5.Asshown,atHP=0.75mm,theproductioncapability（batchsize）is242470units.Thustheproductioncapabilityofn=3islargerthantherequiredlotsize（200000units）.

Forsimplicity,thetimetakenformachiningthedepthofathincomponentistreatedasagivenconstantandaddedtotherequiredtimetCCformakingacavityinsert.TheCmmcanthenbecalculatedbynasexpressed[1]

2.3Moldingprocess

Inthemoldingprocess,thecyclecostandpowerconsumptioncostareusedtoestablishthemoldingoperationscostasdescribedinthefollowingsections.

Fig.5