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1、Lesson13StampingandPunchingDies CompoundDieDesignAcompounddieperformsonlycuttingoperations(usuallyblankingandpiercing)whicharecompletedduringasinglepressstroke.Acharacteristicofcompounddiesistheinvertedpositionoftheblankingdieandblankingpunchwhichalsofunctionsasthepi
2、ercingdie.AsshowninFigure13-1,thedieisfastenedtotheuppershoeandtheblankingpunchhavingataperedholeinitandinthelowershoeforslugdisposalismountedonthelowershoe.Figure13-1AblankingandpiercingcompounddieTheguidepins,orposts,aremountedinthelowershoe.Theuppershoecontainsbus
3、hingwhichslideontheguidepins.Theassemblyoftheloweranduppershoeswithguidepinsandbushingisadieset.Diesetsinmanysizesanddesignsarecommerciallyavailable.Ontheupstrokeofthepressslide,theknockoutrodofthepressstrikestheejectorplate,forcingtheejectortierodandshedderdownward,
4、thuspushingthefinishedworkpieceoutoftheblankingdie①.Fourspecialshoulderscrews(stripperbolts),commerciallyavailable,guidethestripperinitstravelandretainitagainstthepreloadofitssprings.Theblankingdieaswellasthepunchpadisscrewedanddoweledtotheuppershoe.BendingdiesBendin
5、gistheuniformstrainingofmaterial,usuallyflatsheetorstripmetal,aroundastraightaxiswhichliesintheneutralplaneandnormaltothelengthwisedirectionofthesheetorstrip.Metalflowtakesplacewithintheplasticrangeofthemetal,sothatthebendretainsapermanentsetafterremovaloftheapplieds
6、tress②.Theinnersurfaceofabendisincompression;theoutersurfaceisintension.Apurebendingactiondoesnotreproducetheexactshapeofthepunchanddieinthemetal;suchareproductionisoneofforming.Theneutralaxisistheplaneareainbendmetalwhereallstrainiszero.BendingmethodsMetalsheetorstr
7、ip,supportedbyaVblock,isforcedbyawedge-shapedpunchintotheblock.ThismethodTermedVbending(Figure13-2),producesabendhavinganincludedanglewhichmaybeacute,obtuse,orof90°.Frictionbetweenaspring-loadedknurledpinintheveeofadieandthepartwillpreventorreducesidecreepofthepartdu
8、ringitsbending③.OthermethodsareZ-bending(Figure13-3),edgebendingandU-bendingetc.Figure13-2V-bendingdieFigure13-3Z-bendingdieDrawing
