外文翻译--提高级进模性能.doc

英文原文ImprovingPerformanceofProgressiveDiesProgressivediestampingisacost-effectiveandsafemethodofproducingcomponents.Carefuldesignandconstructionofdieswillensureoptimumperformance.Aprogressivedieperformsaseriesoffundamentalsheetmetaloperationsattwoormorestationsinthedieduringeachpressstroke.Thesesimultaneousoperationsproduceapartfromastripofmaterialthatmovesthroughthedie.Eachworkingstationperformsoneormoredieoperations,butthestripmustmovefromthefirststationthrougheachsucceedingstationtoproduceacompletepart.Carriers,consistingofoneormorestripsofmaterialleftbetweentheparts,providemovementofthepartsfromonediestationtothenext.Thesecarrierstripsareseparatedfromthepartsinthelastdiestation.Therearesixelementsthatshouldbeaddressedwhendesigningandbuildingaprogressivedietomaximizeitsperformance:Interpretingthepartprint,Startingmaterialintothedie,Partliftersandpartfeeding,Flexiblepartcarriers,Upperpressurepads,andDrawnshells.InterpretingthePartPrintThefirststepintheproperdesignofaprogressivedieistocorrectlyanalyzethepartprint.Thetooldesignermustinterprettheprinttodeterminethefunctionofthepartbylookingforsuchthingsasthetypeofmaterial,criticalsurfaces,holesizeandlocation,burrlocation,graindirectionrequirements,surfacefinishandotherfactors.Thediedesignermustunderstandthepartwell,particularlyifithasirregularshapesandcontours.However,moderncomputer-drawnprintsmakethismoredifficultbecausecomputer-drawnpartdatacanbedownloadeddirectlytothedie-designcomputer.Asaresult,thedesignermaynotbecomethoroughlyfamiliarwithimportantpartfeatures.Also,manycomputer-drawnpartsaremoredifficulttounderstand,becauseoften,onlyonesurfaceisshownanditmaybetheinsideoroutsidesurface.Computerdrawingsoftenshowalllines,includinghiddenfeatures,assolidlinesinsteadofdottedlines.Thisleadstointerpretationerrors,whichinturnleadstoerrorsinthebuildingofthedie.Tobetterunderstandcomplexpartshapes,itishelpfultobuildasightmodelofthepartusingsheetwax,rubberskinsorwoodmodels.Dimensionalaccuracyisnotcriticalforthesemodels,astheyareusedprimarilytovisualizethepart.Rubberskinsandsheetwaxalsocanbeusedtodeveloppreformshapesandtodevelopthebestpositionsforthepartasitpassesthrougheachdieoperationintheprogressivedie.StartingMaterialintheDieCaremustbetakentoensurethatthestripisstartedcorrectlyintothedie.Improperlocationoftheleadendofthestripwilldomoredamagetothedieinthefirst10strokesofthepressthanthenext100,000strokes.Lead-ingaugesmusthavelargeleadsandaledgetosupporttheleadendofthecoilstripwhenitisinsertedintothedie.Largeleadsonthegaugesareimportantsothatthediesetuppersondoesnothavetoreachintothedie,aswellasforminimizingthetimerequiredtostartanewstripintothedie.Also,onegaugeshouldbeadjustabletocompensateforvariationinstripwidth,.Thepositionoftheleadedgeofthestripiscriticalforthefirstpressstroke,andmustbedeterminedforeverydiestationtoensurethatpiercingpunchesdonotcutpartialholesintheleadedge.Thiscouldcausepunchdeflectionorresultinapartialcutwithtrimmingpunches,whichcanresultinanunbalancedsideloadasthestrippassesthroughthedie.Anyoftheseconditionscanresultinashiftofthepunch-to-dierelationshipthatmaycauseshearingofthepunches.Improperlocationoftheleadedgeofthestripalsocanresultinanunbalancedformingorflangingconditionthatcanshifttheupperdieinrelationtothelowerdie.Heelsshouldberequiredtoabsorbthissideload,particularlywhenformingthickmaterials.Apitchnotchandpitchstopcanprovideaphysicalpointtolocateandcontroltheleadedgeofthestrip.Brasstagsormarkergroovesalsocanprovideavisuallocation,butthesearenotasaccurateoraseffectiveasapitchnotchstop.Thepresscanbepreventedfromoperatingwitheitherashortfeedoroverfeedbymountingthepitchstoponapivotandmonitoringitwithalimitswitch.PartLiftersandPartFeedingProgressivediesoftenrequirethestriptobeliftedfromthenormaldieworkleveltothefeedlevelbeforestripfeedingtakesplace.Thiscanvaryfromasmallamount-tocleartrimandpunchingburrs-toseveralinchestoallowpartshapestoclearthedie.Normally,allliftersshouldrisetothesameheightsothatthestripissupportedinalevelplaneduringforwardfeed.Thestripmustnotsagbetweenlifters；otherwisepartswillbepulledoutoftheircorrectstationlocationspacing.Barliftersprovidegoodsupportandarebetterthanspringpinsorroundliftersnotchedononesideofthestrip.Often,agoodbarliftersystemallowshigherpressspeedsbecausefeedproblemsareeliminated.Althoughtheinitialcostismorethanroundlifters,performanceisbetterandsetuptimeisreduced.Asthestripisstartedintothelead-ingauges,thestripshouldbeabletofeedautomaticallythroughallthefollowingdiestationswithoutrequiringmanualalignmentineachsetofgaugesandlifters.Thestripalsomustbebalancedonthelifterssothatitdoesnotfalltoonesideduringfeed.Aretainercapcanbemountedonthetopoftheoutsidebarlifters.Thisproducesagroovethatcapturesthestripduringfeedandpreventsstripbuckling.Gaugingandlifterconditionscanbesimulatedduringdiedesignbycuttingapieceoftransparentpapertothewidthofthestrip.Theleadedgeofthepaperisplacedovertheplanviewofthediedesignatthelocationthestripwillbeforthefirstpressstroke.Thenthepaperismarkedwithalloftheoperationsthatwillbeperformedatthefirstdiestation-forexample,notchingandpunching.Thepaperstripthenismovedtothesecondstationonthedrawingandtheoperationsforboththefirstandsecondstationsaremarked.Thisprocessisrepeatedthroughallthediestationstoillustratewhattherealpartstripwilllooklikewhenitisstartedintothedieandhelpsdeterminetheadequacyofgaugesandlifters.Totransportthestripfromonestationtothenextinaprogressivedie,somematerialmustbeleftbetweenthepartsonthestrip.Thiscarriermaterialmaybesolidacrossthewidthofthestrip,ormaybeoneormorenarrowribbonsofmaterial,seepartcarrierssidebar.Manypartsrequiretheedgeoftheblanktoflowinwardduringflanging,formingordrawingoperations.Thismayrequirethecarriertomovesidewaysorflexvertically,orboth,duringthedieoperation.Aflexibleloopmustbeprovidedinthecarriertoallowflexingandmovementoftheblankwithoutpullingtheadjacentpartsoutofposition,Fig.2.Anotherconcernistheverticalbreathingofpartsindiestationsduringtheclosingandopeningofthedieinthepressstroke.Forexample,verticalbreathingtakesplacebetweenthedrawstationsofpartsrequiringmorethanonedrawtocompletethepart,Fig.3.Verticalbreathingalsooccurswhenaflangeisformedupinaprogressivediestationthatisadjacenttostationsthatuseupperpressurepadstoholdtheadjacentpartsdown.Itisimportanttoconsidertheflexingofthecarrierduringtheupstrokeofthepressaswellasduringthedownstrokebecausetheactionmaybedifferent.Thiscanbesimulatedinthedesignstagebymakinganoutlineofthecross-sectionofthepart,thepressurepadsandthestationary-mountedsteelsonseparatesheetsofpaperandthenplacingthesesheetsontopofeachotherinlayersoverthediesectionviews.ThiswillshowtherelativepositionofthepartasthedieclosesandduringthereverseactionasthedieramopensPartCarriersAcommonfeatureinallprogressivestampingdiesisthematerialthattransportsthepartsfromstation-to-stationasitpassesthroughthedie.Thismaterialisknownbyvariousterms,suchascarrier,web,strip,tie,attachment,etc.Inthisinstance,wewillusethetermcarrier,ofwhichtherearefivebasicstyles:Solidcarrier-Allrequiredworkcanbeaccomplishedonthepartwithoutpreliminarytrimming.Thepartiscutofforblankedinthefinaloperation.Centercarrier-Theperipheryofthepartistrimmed；leavingonlyanarrowtienearthemiddleofthepart.Thispermitsworktobeperformedallaroundthepart.Awidecentercarrierpermitstrimmingonlyatthesidesofthepart.Lanceandcarryatthecenter-Thestripislancedbetweenparts,leavinganarrowareanearthecentertocarrytheparts.Thiseliminatesscrapmaterialbetweenparts.Outsidecarriers-Thecarriersareattachedtothesidesofthepartsothatworkcanbedonetothecenterofthepart.Onesidecarrier-Thepartiscarriedallthewayorpartofthewaythroughthediewiththecarrierononesideonly.Thispermitsworkonthreesidesofthepart.Thetypeorshapeofthecarrierwillvarydependingonwhatthepartrequiresasitprogressesfromstationtostationinthedie.Thestockwidthmaybeleftsolidifnopartmaterialmotionisrequiredduringdieclosureoritcanbenotchedtocreateone,twooreventhreecarriersbetweenthepartsThecarrierscanbestraight,formazig-zagpatternorhaveloopsbetweenthepartsdependingonwhereattachmentpointstothepartareavailableortoaccommodatewhateverclearancemayberequiredbythedietooling.Asthepartisformed,flangedordrawnintoashell,thecarriermayhavetomovesidewaysorupanddownasthedieclosesandopens.Whendieoperationscausethecarriertomove,itusuallywi