外文翻译--对于注塑模具钢研磨和抛光工序的自动化表面处理 英文版.pdf

DOI10.1007/s0017000423288ORIGINALARTICLEIntJAdvManufTechnol20062861–66FangJungShiouChaoChangA.ChenWenTuLiAutomatedsurfacefinishingofplasticinjectionmoldsteelwithsphericalgrindingandballburnishingprocessesReceived30March2004/Accepted5July2004/Publishedonline30March2005©SpringerVerlagLondonLimited2005AbstractThisstudyinvestigatesthepossibilitiesofautomatedsphericalgrindingandballburnishingsurfacefinishingprocessesinafreeformsurfaceplasticinjectionmoldsteelPDS5onaCNCmachiningcenter.Thedesignandmanufactureofagrindingtoolholderhasbeenaccomplishedinthisstudy.TheoptimalsurfacegrindingparametersweredeterminedusingTaguchisorthogonalarraymethodforplasticinjectionmoldingsteelPDS5onamachiningcenter.TheoptimalsurfacegrindingparametersfortheplasticinjectionmoldsteelPDS5werethecombinationofanabrasivematerialofPAAl2O3,agrindingspeedof18000rpm,agrindingdepthof20µm,andafeedof50mm/min.ThesurfaceroughnessRaofthespecimencanbeimprovedfromabout1.60µmto0.35µmbyusingtheoptimalparametersforsurfacegrinding.SurfaceroughnessRacanbefurtherimprovedfromabout0.343µmto0.06µmbyusingtheballburnishingprocesswiththeoptimalburnishingparameters.Applyingtheoptimalsurfacegrindingandburnishingparameterssequentiallytoafinemilledfreeformsurfacemoldinsert,thesurfaceroughnessRaoffreeformsurfaceregiononthetestedpartcanbeimprovedfromabout2.15µmto0.07µm.KeywordsAutomatedsurfacefinishingBallburnishingprocessGrindingprocessSurfaceroughnessTaguchismethod1IntroductionPlasticsareimportantengineeringmaterialsduetotheirspecificcharacteristics,suchascorrosionresistance,resistancetochemicals,lowdensity,andeaseofmanufacture,andhaveincreasinglyF.J.Shioua117C.C.A.ChenW.T.LiDepartmentofMechanicalEngineering,NationalTaiwanUniversityofScienceandTechnology,No.43,Section4,KeelungRoad,106Taipei,TaiwanR.O.C.Emailshioumail.ntust.edu.twTel.886227376543Fax886227376460replacedmetalliccomponentsinindustrialapplications.Injectionmoldingisoneoftheimportantformingprocessesforplasticproducts.Thesurfacefinishqualityoftheplasticinjectionmoldisanessentialrequirementduetoitsdirecteffectsontheappearanceoftheplasticproduct.Finishingprocessessuchasgrinding,polishingandlappingarecommonlyusedtoimprovethesurfacefinish.Themountedgrindingtoolswheelshavebeenwidelyusedinconventionalmoldanddiefinishingindustries.Thegeometricmodelofmountedgrindingtoolsforautomatedsurfacefinishingprocesseswasintroducedin1.Afinishingprocessmodelofsphericalgrindingtoolsforautomatedsurfacefinishingsystemswasdevelopedin2.Grindingspeed,depthofcut,feedrate,andwheelpropertiessuchasabrasivematerialandabrasivegrainsize,arethedominantparametersforthesphericalgrindingprocess,asshowninFig.1.Theoptimalsphericalgrindingparametersfortheinjectionmoldsteelhavenotyetbeeninvestigatedbasedintheliterature.Inrecentyears,someresearchhasbeencarriedoutindeterminingtheoptimalparametersoftheballburnishingprocessFig.2.Forinstance,ithasbeenfoundthatplasticdeformationontheworkpiecesurfacecanbereducedbyusingatungstencarbideballoraroller,thusimprovingthesurfaceroughness,surfacehardness,andfatigueresistance3–6.Theburnishingprocessisaccomplishedbymachiningcenters3,4andlathes5,6.Themainburnishingparametershavingsignificanteffectsonthesurfaceroughnessareballorrollermaterial,burnishingforce,feedrate,burnishingspeed,lubrication,andnumberofburnishingpasses,amongothers3.TheoptimalsurfaceburnishingparametersfortheplasticinjectionmoldsteelPDS5wereacombinationofgreaselubricant,thetungstencarbideball,aburnishingspeedof200mm/min,aburnishingforceof300N,andafeedof40µm7.Thedepthofpenetrationoftheburnishedsurfaceusingtheoptimalballburnishingparameterswasabout2.5microns.Theimprovementofthesurfaceroughnessthroughburnishingprocessgenerallyrangedbetween40and903–7.Theaimofthisstudywastodevelopsphericalgrindingandballburnishingsurfacefinishprocessesofafreeformsurface62plasticinjectionmoldonamachiningcenter.TheflowchartofautomatedsurfacefinishusingsphericalgrindingandballburnishingprocessesisshowninFig.3.Webeganbydesigningandmanufacturingthesphericalgrindingtoolanditsalignmentdeviceforuseonamachiningcenter.TheoptimalsurfacesphericalgrindingparametersweredeterminedbyutilizingaTaguchisorthogonalarraymethod.FourfactorsandthreecorrespondinglevelswerethenchosenfortheTaguchisL18matrixexperiment.Theoptimalmountedsphericalgrindingparametersforsurfacegrindingwerethenappliedtothesurfacefinishofafreeformsurfacecarrier.Toimprovethesurfaceroughness,thegroundsurfacewasfurtherburnished,usingtheoptimalballburnishingparameters.Fig.1.SchematicdiagramofthesphericalgrindingprocessFig.2.SchematicdiagramoftheballburnishingprocessFig.3.Flowchartofautomatedsurfacefinishusingsphericalgrindingandballburnishingprocesses2DesignofthesphericalgrindingtoolanditsalignmentdeviceTocarryoutthepossiblesphericalgrindingprocessofafreeformsurface,thecenteroftheballgrindershouldcoincidewiththezaxisofthemachiningcenter.Themountedsphericalgrindingtoolanditsadjustmentdevicewasdesigned,asshowninFig.4.Theelectricgrinderwasmountedinatoolholderwithtwoadjustablepivotscrews.Thecenterofthegrinderballwaswellalignedwiththehelpoftheconicgrooveofthealignmentcomponents.Havingalignedthegrinderball,twoadjustablepivotscrewsweretightenedafterwhich,thealignmentcomponentscouldberemoved.Thedeviationbetweenthecentercoordinatesoftheballgrinderandthatoftheshankwasabout5µm,whichwasmeasuredbyaCNCcoordinatemeasuringmachine.Theforceinducedbythevibrationofthemachinebedisabsorbedbyahelicalspring.Themanufacturedsphericalgrindingtoolandballburnishingtoolweremounted,asshowninFig.5.Thespindlewaslockedforboththesphericalgrindingprocessandtheballburnishingprocessbyaspindlelockingmechanism.63Fig.4.Schematicillustrationofthesphericalgrindingtoolanditsadjustmentdevice3Planningofthematrixexperiment3.1ConfigurationofTaguchisorthogonalarrayTheeffectsofseveralparameterscanbedeterminedefficientlybyconductingmatrixexperimentsusingTaguchisorthogonalarray8.Tomatchtheaforementionedsphericalgrindingparameters,theabrasivematerialofthegrinderballwiththediameterof10mm,thefeedrate,thedepthofgrinding,andtherevolutionoftheelectricgrinderwereselectedasthefourexperimentalfactorsparametersanddesignatedasfactorAtoDseeTable1inthisresearch.Threelevelssettingsforeachfactorwereconfiguredtocovertherangeofinterest,andwereidentiFig.5.aPhotoofthesphericalgrindingtoolbPhotooftheballburnishingtoolTable1.TheexperimentalfactorsandtheirlevelsFactorLevel123A.AbrasivematerialSiCAl2O3,WAAl2O3,PAB.Feedmm/min50100200C.Depthofgrindingµm205080D.Revolutionrpm120001800024000fiedbythedigits1,2,and3.Threetypesofabrasivematerials,namelysiliconcarbideSiC,whitealuminumoxideAl2O3,WA,andpinkaluminumoxideAl2O3,PA,wereselectedandstudied.Threenumericalvaluesofeachfactorweredeterminedbasedontheprestudyresults.TheL18orthogonalarraywasselectedtoconductthematrixexperimentforfour3levelfactorsofthesphericalgrindingprocess.3.2DefinitionofthedataanalysisEngineeringdesignproblemscanbedividedintosmallerthebettertypes,nominalthebesttypes,largerthebettertypes,signedtargettypes,amongothers8.ThesignaltonoiseS/Nratioisusedastheobjectivefunctionforoptimizingaproductorprocessdesign.Thesurfaceroughnessvalueofthegroundsurfaceviaanadequatecombinationofgrindingparametersshouldbesmallerthanthatoftheoriginalsurface.Consequently,thesphericalgrindingprocessisanexampleofasmallerthebettertypeproblem.TheS/Nratio,η,isdefinedbythefollowingequation8η−10log10meansquarequalitycharacteristic−10log10bracketleftBigg1nnsummationdisplayi1y2ibracketrightBigg.1whereyiobservationsofthequalitycharacteristicunderdifferentnoiseconditionsnnumberofexperimentAftertheS/NratiofromtheexperimentaldataofeachL18orthogonalarrayiscalculated,themaineffectofeachfactorwasdeterminedbyusingananalysisofvarianceANOVAtechniqueandanFratiotest8.Theoptimizationstrategyofthe64smallerthebetterproblemistomaximizeη,asdefinedbyEq.1.Levelsthatmaximizeηwillbeselectedforthefactorsthathaveasignificanteffectonη.Theoptimalconditionsforsphericalgrindingcanthenbedetermined.4ExperimentalworkandresultsThematerialusedinthisstudywasPDS5toolsteelequivalenttoAISIP209,whichiscommonlyusedforthemoldsoflargeplasticinjectionproductsinthefieldofautomobilecomponentsanddomesticappliances.ThehardnessofthismaterialisaboutHRC33HS469.Onespecificadvantageofthismaterialisthataftermachining,themoldcanbedirectlyusedforfurtherfinishingprocesseswithoutheattreatmentduetoitsspecialpretreatment.Thespecimensweredesignedandmanufacturedsothattheycouldbemountedonadynamometertomeasurethereactionforce.ThePDS5specimenwasroughlymachinedandthenmountedonthedynamometertocarryoutthefinemillingonathreeaxismachiningcentermadebyYangIronCompanytypeMV3A,equippedwithaFUNUCCompanyNCcontrollertype0M10.Thepremachinedsurfaceroughnesswasmeasured,usingHommelwerkeT4000equipment,tobeabout1.6µm.Figure6showstheexperimentalsetupofthesphericalgrindingprocess.AMP10touchtriggerprobemadebytheRenishawCompanywasalsointegratedwiththemachiningcentertoolmagazinetomeasureanddeterminethecoordinatedoriginofthespecimentobeground.TheNCcodesneededfortheballburnishingpathweregeneratedbyPowerMILLCAMsoftware.ThesecodescanbetransmittedtotheCNCcontrollerofthemachiningcenterviaRS232serialinterface.Table2summarizesthemeasuredgroundsurfaceroughnessvalueRaandthecalculatedS/NratioofeachL18orthogonalarrayusingEq.1,afterhavingexecutedthe18matrixexperiments.TheaverageS/Nratioforeachlevelofthefourfactorscanbeobtained,aslistedinTable3,bytakingthenumericalvaluesprovidedinTable2.TheaverageS/NratioforeachlevelofthefourfactorsisshowngraphicallyinFig.7.Fig.6.ExperimentalsetuptodeterminetheoptimalsphericalgrindingparametersTable2.GroundsurfaceroughnessofPDS5specimenExp.InnerarrayMeasuredsurfaceResponseno.controlfactorsroughnessvalueRaABCDy1y2y3S/NratioMeanµmµmµmηdByµm111110.350.350.359.1190.350212220.370.360.388.6340.370313330.410.440.407.5970.417421230.630.650.643.8760.640522310.730.770.782.3800.760623120.450.420.397.5200.420731320.340.310.329.8010.323832130.270.250.2811.4710.267933210.320.320.329.8970.3201011220.350.390.408.3900.3801112330.410.500.436.9680.4471213110.400.390.427.8830.4031321130.330.340.319.7120.3271422210.480.500.476.3120.4831523320.570.610.534.8680.5701631310.590.550.545.0300.5601732120.360.360.358.9540.3571833230.570.530.535.2930.543Table3.AverageS/NratiosbyfactorlevelsdBFactorABCDLevel18.0997.6559.1106.770Level25.7787.4537.0678.028Level38.4087.1766.1077.486Effect2.6300.4793.0031.258Rank2413Mean7.428Thegoalinthesphericalgrindingprocessistominimizethesurfaceroughnessvalueofthegroundspecimenbydeterminingtheoptimallevelofeachfactor.Since−logisamonotonedecreasingfunction,weshouldmaximizetheS/Nratio.Consequently,wecandeterminetheoptimallevelforeachfactorasbeingthelevelthathasthehighestvalueofη.Therefore,based