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UnitTwoDieDesign模具与数控专业英语2.6DrawingDie模具与数控专业英语2.6.1DrawingDieProcessesDrawingisaprocessofchangingaflat，precutmetalblankintoahollowvesselwithoutexcessivewrinkling，thinning，orfracturing．Thevariousformsproducedmaybecylindricalorbox-shapedwithstraightortaperedsidesoracombinationofstraight，tapered，orcurvedsides．Manypartsmadeofsheetmetalarecylindricalorbox-shaped:forexample,potsandpans,containersforfoodandbeverages(Figure2-17),kitchensinks,andautomotivefueltanks.模具与数控专业英语Suchpartsareusuallymadebyaprocessinwhichapunchforcesaflatsheet-metalblankintoadiecavity(Figure2-18).Althoughtheprocessisgenerallycalleddeepdrawing,onaccountofitscapabilityofproducingdeepparts,itisalsousedtomakepartsthatareshalloworhavemoderatedepth.模具与数控专业英语Figure2-17Themetal-formingprocess模具与数控专业英语Figure2-18Drawingprocessonasheet-metalblank模具与数控专业英语Metalflow--Whenametalblankisdrawnintoadie，achangeinitsshapeisbroughtaboutbyforcingthemetaltoflowonaplaneparalleltothedieface，withtheresultthatitsthicknessandsurfacearearemainaboutthesameastheblank．Figure2-19showsschematicallytheflowofmetalincircularshells.Theunitswithinonepairofradialboundarieshavebeennumberedandeachunitmovedprogressivelytowardthecenterinthreesteps.模具与数控专业英语Iftheshellweredrawninthismanner,andacertainunitareaexaminedaftereachdepthshown,itwouldshow(a)asizechangeonlyasthemetalmovestowardthedieradius;(b)ashapechangeonlyasthemetalmovesoverthedieradius.Observethatnochangetakesplaceinareab,b1=b2=b3=……=b;andthemaximumchangeisnotedinareaa,a1a2a3…….a.Theouter-ringareaofflatsheetismainchangeandnochangeinthebottomtouchedwithpunch.模具与数控专业英语Figure2-19Astep-by-stepflowofmetal模具与数控专业英语2.6.2DrawingDieDesignSingle-actionDies--Thesimplesttypeofdieisonewithonlyapunchanddie．Eachcomponentmaybedesignedinonepiecewithoutashoebyincorporatingfeaturesforattachingthemtotheramandbolsterplateofthepress．Figure2-20ashowsasimpletypeofdrawdieinwhichtheprecutblankisplacedintherecessontopofthedie，andthepunchdescends，pushingthecupthroughthedie．Asthepunchascends，thecupisstrippedfromthepunchbythecounterboreinthebottomofthedie．模具与数控专业英语Thetopedgeoftheshellexpandsslightlytomakethispossible．Thepunchhasanairventtoeliminatesuctionwhichwouldholdthecuponthepunchanddamagethecupwhenitisstrippedfromthepunch．Themethodbywhichtheblankisheldinpositionisimportant，becausesuccessfuldrawingissomewhatdependentuponthepropercontrolofblankholderpressure．模具与数控专业英语Asimpleformofdrawingdiewitharigidflatblankholderforusewith13-gageandheavierstockisshowninFigure2-20b．Whenthepunchcomesincontactwiththestock，itwillbedrawnintothediewithoutallowingwinklestoform．模具与数控专业英语（a）(b)Figure2-20Drawdietypes模具与数控专业英语Anothertypeofdrawingdieforuseinasingle-actionpressisshowninFigure2-21.Thisdieisaplainsingle-actiontypewherethepunchpushesthemetalblankintothedie，usingasimple-loadedpressurepadtocontrolthemetaldisplacement．Thecupeitherdropsthroughthedieorisstrippedoffthepunchbythepressurepad．Thesketchshowsthepressurepadextendingoverthenest,whichactsasaspacerandisgroundtosuchthicknessthatanevenandproperpressureisexertedontheblankatalltimes．模具与数控专业英语Ifthespringpressurepadisusedwithoutthespacer，themorethespringaredepressedthegreaterthepressureexertedontheblank，therebylimitingthedepthofdraw．Becauseoflimitedpressuresobtainable，thistypeofdieshouldbeusedwithlight-gagestockandshallowdepths．Asingle-actiondiedrawingflangedparts，havingaspring-loadedpressurepadandstripper，isshowninFigure2-22．模具与数控专业英语Thestrippermayalsobeusedtoformslightindentationsorre-entrantcurvesinthebottomofacup,withorwithoutaflange．Drawtoolsinwhichthepressurepadisattachedtothepuncharesuitableonlyforshallowdraws，Thepressurecannotbeeasilyadjusted，andtheshortspringstendtobuilduppressuretooquicklyfordeepdraws．Thistypeofdieisoftenconstructedinaninvertedpositionwiththepunchfastenedtothelowerportionofthedie．模具与数控专业英语Figure2-21withspringpressurepadFigure2-22withspringpressurepadandstripper模具与数控专业英语Deepdrawsmaybemadeonsingle-actiondies，wherethepressureontheblankholderismoreevenlycontrolledbyadiecushionorpadattachedtothebedofthepress．ThetypicalconstructionofsuchadieisshowninFigure2-23．Thisisaninverteddiewiththepunchonthedie’slowerportion．模具与数控专业英语Here,weshouldalsomakecleartheconceptindrawingdiedesign:(a)Drawing—thegeneraltermforsheet-metalformingandmorespecificallythebehaviorofmaterialintheflangeofaproductthatgetsdrawnintothediewall.(b)Deep-drawing—essentiallythesameasdrawingbutoftenrelatedtoprocessesthatuseseveralrepeateddrawingoperationssothatlongproductscanbeformed.