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外文翻译--提高级进模性能.doc

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外文翻译--提高级进模性能.doc

英文原文ImprovingPerformanceofProgressiveDiesProgressivediestampingisacosteffectiveandsafemethodofproducingcomponents.Carefuldesignandconstructionofdieswillensureoptimumperformance.Aprogressivedieperformsaseriesoffundamentalsheetmetaloperationsattwoormorestationsinthedieduringeachpressstroke.Thesesimultaneousoperationsproduceapartfromastripofmaterialthatmovesthroughthedie.Eachworkingstationperformsoneormoredieoperations,butthestripmustmovefromthefirststationthrougheachsucceedingstationtoproduceacompletepart.Carriers,consistingofoneormorestripsofmaterialleftbetweentheparts,providemovementofthepartsfromonediestationtothenext.Thesecarrierstripsareseparatedfromthepartsinthelastdiestation.TherearesixelementsthatshouldbeaddressedwhendesigningandbuildingaprogressivedietomaximizeitsperformanceInterpretingthepartprint,Startingmaterialintothedie,Partliftersandpartfeeding,Flexiblepartcarriers,Upperpressurepads,andDrawnshells.InterpretingthePartPrintThefirststepintheproperdesignofaprogressivedieistocorrectlyanalyzethepartprint.Thetooldesignermustinterprettheprinttodeterminethefunctionofthepartbylookingforsuchthingsasthetypeofmaterial,criticalsurfaces,holesizeandlocation,burrlocation,graindirectionrequirements,surfacefinishandotherfactors.Thediedesignermustunderstandthepartwell,particularlyifithasirregularshapesandcontours.However,moderncomputerdrawnprintsmakethismoredifficultbecausecomputerdrawnpartdatacanbedownloadeddirectlytothediedesigncomputer.Asaresult,thedesignermaynotbecomethoroughlyfamiliarwithimportantpartfeatures.Also,manycomputerdrawnpartsaremoredifficulttounderstand,becauseoften,onlyonesurfaceisshownanditmaybetheinsideoroutsidesurface.Computerdrawingsoftenshowalllines,includinghiddenfeatures,assolidlinesinsteadofdottedlines.Thisleadstointerpretationerrors,whichinturnleadstoerrorsinthebuildingofthedie.Tobetterunderstandcomplexpartshapes,itishelpfultobuildasightmodelofthepartusingsheetwax,rubberskinsorwoodmodels.Dimensionalaccuracyisnotcriticalforthesemodels,astheyareusedprimarilytovisualizethepart.Rubberskinsandsheetwaxalsocanbeusedtodeveloppreformshapesandtodevelopthebestpositionsforthepartasitpassesthrougheachdieoperationintheprogressivedie.StartingMaterialintheDieCaremustbetakentoensurethatthestripisstartedcorrectlyintothedie.Improperlocationoftheleadendofthestripwilldomoredamagetothedieinthefirst10strokesofthepressthanthenext100,000strokes.Leadingaugesmusthavelargeleadsandaledgetosupporttheleadendofthecoilstripwhenitisinsertedintothedie.Largeleadsonthegaugesareimportantsothatthediesetuppersondoesnothavetoreachintothedie,aswellasforminimizingthetimerequiredtostartanewstripintothedie.Also,onegaugeshouldbeadjustabletocompensateforvariationinstripwidth,.Thepositionoftheleadedgeofthestripiscriticalforthefirstpressstroke,andmustbedeterminedforeverydiestationtoensurethatpiercingpunchesdonotcutpartialholesintheleadedge.Thiscouldcausepunchdeflectionorresultinapartialcutwithtrimmingpunches,whichcanresultinanunbalancedsideloadasthestrippassesthroughthedie.Anyoftheseconditionscanresultinashiftofthepunchtodierelationshipthatmaycauseshearingofthepunches.Improperlocationoftheleadedgeofthestripalsocanresultinanunbalancedformingorflangingconditionthatcanshifttheupperdieinrelationtothelowerdie.Heelsshouldberequiredtoabsorbthissideload,particularlywhenformingthickmaterials.Apitchnotchandpitchstopcanprovideaphysicalpointtolocateandcontroltheleadedgeofthestrip.Brasstagsormarkergroovesalsocanprovideavisuallocation,butthesearenotasaccurateoraseffectiveasapitchnotchstop.Thepresscanbepreventedfromoperatingwitheitherashortfeedoroverfeedbymountingthepitchstoponapivotandmonitoringitwithalimitswitch.PartLiftersandPartFeedingProgressivediesoftenrequirethestriptobeliftedfromthenormaldieworkleveltothefeedlevelbeforestripfeedingtakesplace.Thiscanvaryfromasmallamounttocleartrimandpunchingburrstoseveralinchestoallowpartshapestoclearthedie.Normally,allliftersshouldrisetothesameheightsothatthestripissupportedinalevelplaneduringforwardfeed.Thestripmustnotsagbetweenliftersotherwisepartswillbepulledoutoftheircorrectstationlocationspacing.Barliftersprovidegoodsupportandarebetterthanspringpinsorroundliftersnotchedononesideofthestrip.Often,agoodbarliftersystemallowshigherpressspeedsbecausefeedproblemsareeliminated.Althoughtheinitialcostismorethanroundlifters,performanceisbetterandsetuptimeisreduced.Asthestripisstartedintotheleadingauges,thestripshouldbeabletofeedautomaticallythroughallthefollowingdiestationswithoutrequiringmanualalignmentineachsetofgaugesandlifters.Thestripalsomustbebalancedonthelifterssothatitdoesnotfalltoonesideduringfeed.Aretainercapcanbemountedonthetopoftheoutsidebarlifters.Thisproducesagroovethatcapturesthestripduringfeedandpreventsstripbuckling.Gaugingandlifterconditionscanbesimulatedduringdiedesignbycuttingapieceoftransparentpapertothewidthofthestrip.Theleadedgeofthepaperisplacedovertheplanviewofthediedesignatthelocationthestripwillbeforthefirstpressstroke.Thenthepaperismarkedwithalloftheoperationsthatwillbeperformedatthefirstdiestationforexample,notchingandpunching.Thepaperstripthenismovedtothesecondstationonthedrawingandtheoperationsforboththefirstandsecondstationsaremarked.Thisprocessisrepeatedthroughallthediestationstoillustratewhattherealpartstripwilllooklikewhenitisstartedintothedieandhelpsdeterminetheadequacyofgaugesandlifters.Totransportthestripfromonestationtothenextinaprogressivedie,somematerialmustbeleftbetweenthepartsonthestrip.Thiscarriermaterialmaybesolidacrossthewidthofthestrip,ormaybeoneormorenarrowribbonsofmaterial,seepartcarrierssidebar.Manypartsrequiretheedgeoftheblanktoflowinwardduringflanging,formingordrawingoperations.Thismayrequirethecarriertomovesidewaysorflexvertically,orboth,duringthedieoperation.Aflexibleloopmustbeprovidedinthecarriertoallowflexingandmovementoftheblankwithoutpullingtheadjacentpartsoutofposition,Fig.2.Anotherconcernistheverticalbreathingofpartsindiestationsduringtheclosingandopeningofthedieinthepressstroke.Forexample,verticalbreathingtakesplacebetweenthedrawstationsofpartsrequiringmorethanonedrawtocompletethepart,Fig.3.Verticalbreathingalsooccurswhenaflangeisformedupinaprogressivediestationthatisadjacenttostationsthatuseupperpressurepadstoholdtheadjacentpartsdown.Itisimportanttoconsidertheflexingofthecarrierduringtheupstrokeofthepressaswellasduringthedownstrokebecausetheactionmaybedifferent.Thiscanbesimulatedinthedesignstagebymakinganoutlineofthecrosssectionofthepart,thepressurepadsandthestationarymountedsteelsonseparatesheetsofpaperandthenplacingthesesheetsontopofeachotherinlayersoverthediesectionviews.ThiswillshowtherelativepositionofthepartasthedieclosesandduringthereverseactionasthedieramopensPartCarriersAcommonfeatureinallprogressivestampingdiesisthematerialthattransportsthepartsfromstationtostationasitpassesthroughthedie.Thismaterialisknownbyvariousterms,suchascarrier,web,strip,tie,attachment,etc.Inthisinstance,wewillusethetermcarrier,ofwhichtherearefivebasicstylesSolidcarrierAllrequiredworkcanbeaccomplishedonthepartwithoutpreliminarytrimming.Thepartiscutofforblankedinthefinaloperation.CentercarrierTheperipheryofthepartistrimmedleavingonlyanarrowtienearthemiddleofthepart.Thispermitsworktobeperformedallaroundthepart.Awidecentercarrierpermitstrimmingonlyatthesidesofthepart.LanceandcarryatthecenterThestripislancedbetweenparts,leavinganarrowareanearthecentertocarrytheparts.Thiseliminatesscrapmaterialbetweenparts.OutsidecarriersThecarriersareattachedtothesidesofthepartsothatworkcanbedonetothecenterofthepart.OnesidecarrierThepartiscarriedallthewayorpartofthewaythroughthediewiththecarrierononesideonly.Thispermitsworkonthreesidesofthepart.Thetypeorshapeofthecarrierwillvarydependingonwhatthepartrequiresasitprogressesfromstationtostationinthedie.Thestockwidthmaybeleftsolidifnopartmaterialmotionisrequiredduringdieclosureoritcanbenotchedtocreateone,twooreventhreecarriersbetweenthepartsThecarrierscanbestraight,formazigzagpatternorhaveloopsbetweenthepartsdependingonwhereattachmentpointstothepartareavailableortoaccommodatewhateverclearancemayberequiredbythedietooling.Asthepartisformed,flangedordrawnintoashell,thecarriermayhavetomovesidewaysorupanddownasthedieclosesandopens.Whendieoperationscausethecarriertomove,itusuallywillberequiredtoflexorstretch.Regardlessofcarrierflexing,theirkeyfunctionistomovethepartscloseenoughtothenextstationsothatpilots,gaugesandlocatorscanputthepartsintotheirpreciselocationasthediecloses.Ifthecarrieracquiresapermanentstretch,thepartsmayprogresstoofartofitonthenextstation,orinthecasethatthediehastwocarriers,onecarriermaydeveloppermanentstretchwithnostretchintheothercarrier.Thiswillcreateedgecamberinthestrip,causingittoveertooneside.Thisresultsinpoorpartlocation.Astretchedcarriercanbeshortenedtoitscorrectlengthbyputtingadimpleinthecarrier.Ifacentercarrieroronesidedcarrierdevelopscamber,thestripcanbestraightenedbydimplingorscoringonesideofthecarrier.Constructthedimpleandscoringpunchessothattheyareeasilyadjustedsidewaysforpositionandverticallyfordepth.asitisdeliveredfromthecoilcancausethestriptobindintherunninggaugesthatguidethematerialduringthefeedcycle.Thisbindingmaycausethecarrierstobuckle,

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