冲裁件的工艺设计毕业课程设计外文文献翻译文档格式.docx
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冲裁件的工艺设计毕业课程设计外文文献翻译文档格式.docx
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Thetechnologicaldesignoftheblankingworkpiececonsistsoftheanalysisofthetechnologicalpropertiesandthedeterminationofthetechnologyscheme.Theexcellenttechnologicalpropertiesoftheworkpieceandreasonabletechnologyschemewouldcutdownthematerialexhausted,operationnumberandproductiontime.Itwouldalsosimplifythedieconstructionandincreasethedielife,thusresultinginreducingthemanuallabourandthecostoftheworkpiece.Thelattertwofactorsarethemainindexesforjudgingthedesignoftheblankingprocess.
1.Calulationofblankingforceandmethodstodecreaseblankingforce
(1)calculationofblankingforce
Thepurposeofthecalculationoftheblankingforceistochooseasuitablepressmachine,todesignthedie,andtocheckthediestrength.thetoncapacityofthepressmachineshouldbehigherthantheblankingforce.
(2)hodstodecreaseblankingforce
Inpractice,inordertomeetthedemandoftheequipmentcondition,andtoreducevibrationandnoise,followingmethodsareusedtodecreasetheblankingforce.
1)Blankingwithheatin.Theshearingstrengthofmaterialcanbesignificantlydecreasedwhenheated,sotodecreasetheblankingforce.Thedisadvantageofthismethodisthatalayerofoxidewouldbeproducedonthesurfaceofthematerialafterheating,andtheworkingconditiongettingworse.Consequently,thismethodisonlyusedwiththickplateortheworkpiecewithouthighdeamandsonsufacequalityandtolerancegrage.
2)Multi-punchsteppedblanking.Ifthereismorethanonepunchinblanking,thebottomsurfaceoftheplunchedgecanbearrangedinsteps.Whileblankingbymulti-punchwithoutstep,totalblankingforceisthesumofeachpunchforce;
ifthepunchesarearrangedinsteps,theblankisprocessedinsequence,thusthetotalshearingareaandthetotalblankingforceatarbitrarymomentisdeceased.
Whenthepunchesarearrangedinsteps,thefollowingdemandsshouldbetakinginmind.
Thesteppedpunchmustbearrangedsymmetricallyinordertoavoideccentricload.Toavoidextrusionforceinfluencecausedbymaterialflowingonsmallpunchwhenpunchinglargehole,itisbettertopunchlargeholefirst,andthenthesmallone.Itisalsoconducivetodecreasethelengthofthesmallpunch.
3)Blankingwithinclinededgedie.Thebottomsurfaceoftheordinarydieisaplane,whichisperpendiculartothedieaxis.Whenthebottomsurfaceofdieisdesignedinslantwithcertainincludedangletothedieaixs,thediedegepenetratesintotheblankgradually,sotheshearingareaandtheblankingforceascomparedwiththeflatedgeblankingisreducedatanyarbitrarytime.Theblankingforcecanbedecreasedfrom50%to75%.
Inordertogetaflatworkpiece,thedieedgeisdesignedasaninclinedplaneforblanking.Onontrary,thepunchedgeisdesignedasaninclinedplaneforpunching.Forblankingacurvedshapepart,aroundheadpunchisusuallyused.Blankingwithone-sidedinclinededgeisonlyapplicableforthelancingwithbending.Whenthepunchanddieisdesignedwithinclinedblankingedge,theinclinededgeshouldbearrangedsymmetricallyinordertopreventtheedgedamagecausedbytheoffsetofthepunchordieduetothesidepressureinone-sidedirection.Theinclinededgeisinconvenientforworkpiecewithcomplexshape.Theforcereductiondependsontheheightoftheinclinededgeandtheangles.
Themaindisadvantagesoftheinclinededgeblankingincludethedifficultiesinthedieedgemanufacturingandrepairing,thequickwearingofthedieedge,andtheunflantnessoftheworkpiece.Therefore,thismethodisonlysuitableforblankinglargepartorthickplate.
(3)Calculationofstripping,pushingandejectingforces
Afterblanking,theworkpieceorwawteseparatedformtheblankmayjaminthediecavityduetoelasticexpansioninradialdiorection.Meanwhile,theholeremainingintheblankmayhooponthepunchduetoelasticshrinkinginradialdirection.Theforcetostripthesheetmetalhooparoundthepunchiscalledstrippingforceandtheforcethatpushesdownorejectupthesheetmetaljammedinthediecavityiscalledpushingorejectingforce,respectively.
Thestripping,pushingandejectingforcesareobtainedbyutilizingthepushingandejectingdevicesofthepressaswellasthatofthepunchanddie.Itisnecessarytocalculatethestripping,pushingandejectingforcesbyconsideringthediestructurewhenselectingthepressanddesigningthepunchanddie.Therearemanyfactorsinfluencetheseforces,includingthemechanicpropertiesandthicknessoftheblank,theshapeanddimensionoftheworkpiece,theclearancebetweenthepunchanddie,thescrapsizeandthelubricationcondition.
2. Technologicalpropertiesanalysisofblankingworkpiece
Theanalysisofthetechnologicalpropertiesofblankingworkpieceistheadaptabilityoftheblankingworkpiecetoblankingprocess,namely,whethertheshape,thedimensionandthetoleranceoftheblankingworkpiecemeetthedemandoftheblankingprocessornot.Whetherthetechnologicalpropertiesoftheblankingworkpieceisreasonableornot,hasagreatinfluenceonthequalityoftheblankingworkpiece,thedielifeandtheproductivity.
Theblankingworkpiecemustmeetthefollowingdemands:
(1)shapeoftheblankingworkpiece
Theshapeoftheblankingworkpiecemustbesimpleandsymmetrical,withlesswasteinblanklayout.Ifonlythedistancebetweenthethreeholesshouldbekept,andtheoutershapeoftheworkpieceisnotsoimportant,theworkpiececanberedesignedtoadoptblanklayoutwithoutwastewithsucharrangement,thematerialutilizationratiomayincreaseby40%.Moreover,therearetwoworkpiecesproducedinoneblanking,sotheblankingproductivityisdoubledandtheproductioncostisdecreased.Obviouslythetechnologypropertyoftheimprovedblankingworkpieceisbetterthanthatoftheoriginalone.
(2)Roundnessradiusoftheblankingworkpiece
Sharpcornershouldbeavoidedintheblankingworkpieceexceptwhenadoptinglesswastearrangementorusinginsertdie.Asuitableroundnessradiusshouldbeadopted.
(3)Widthanddepthofthelocalprotrusiveorincurvateregionoftheblankingworkpiece
Thewidthoftheprotrusiveorincurvateregionoftheblankingworkpieceshouldnotbetoosmall.Thelancingandgroove,shouldnotbetoonarrowandtoolong,otherwisethedielifeandtheworkpiecequalitywouldbedecreased.
(4)Aperturedimensionoftheblankingworkpiece
Iftheaperturedimensionistoosmall,thepunchwouldfractureorbendeasilyundercompression.Theminimumdimensionoftheaperturepuncheddependsonthemechanicalpropertiesofthematerial,thepunchstrengthandthediestructure.Inthecaseofpunchingsmallaperture,ifaprotectingjacketisused,thepunchwouldnotbedamagedeasilyanditsstabilitycanalsobeimproved;
therefore,theminimumdimensionoftheaperturepunchedcanbedecreased.
(5)Distancebetweenholesintheblankingworkpiece
Thedistancesbetweenholesorbetweentheholeandedgeshouldnotbetoosmall.Otherwise,thematerialbetweentheholesmaytwist.Inthecaseofcompoundblankingprocess,thediemaybreakeasilyduetothematerialispulledintodieeasily;
inthecaseofblankingsmallholeswithsmalldistancebetweenthem,thephenomenathatthepunchjammedindiealwayshappensduetothebendingofthepunch.Iftheedgeofthepunhedholedoesnotparalleltotheedgeoftheworkpieceoutline,thedistancebetweenthemshouldbelangerthant;
onthecontrary,thedistancebetweenthemshouldbelangerthan1.5t.
3.Determinationoftechnologyschemeinblanking
Accordingtothecharacteristicsoftheblankingworkpiece,thetechnologyschemeoftheblankingisdeterminedbasedontheanalysisoftheblankingprocess
(1)Combinationoftheblankingprocess
Blankingprocesscanbedividedintosingleblanking,compoundblankingandprogressiveblanking.
Thecompoundblankingisthattwoormorethantwoprocessesaredoneinthesamediepositioninonepressstroke.Theprogressiveblankingisthatseveralblankingprocessesaredoneatdifferentdiepositionsinonepressstroke.Onworkpiceccanbeproduceineachpressstrokebuttheinitialstrokeistheexceptional.Theproductivityofthecompoundblankingishigherthanthatofthesingleblanking,andthetolerancegradeofworkpieceofthecompoundblankingisalsohigherthanthatofthesingleblanking.
Thecompoundmodeoftheblankingprocessisdeterminedbyfollowingfactors:
1)Productionbatch.
Generally,thesingleblankingissuitableforsmallbatchortrialproduction,thecompoundorprogressiveblankingissuitableformediumandlargebatchproduction.
2)Dimensiontolerancegradeoftheblankingworkpiece.
Thetolerancegradeoftheworkpieceproducedthroughthecompoundblankingishigh,becausemulti-timelocatingerrorcanbeavoidedinthisprocess.Ascomparedwithcompoundblanking,thetolerancegradeoftheworkpieceproducedthroughprogressiveblankingislow.
3)Dimensionandshapeoftheworkpiece.
Whenthedimensionoftheworkpieceissmall,thecompoundorprogressiveblankingisusuallyadoptedinviewofinconvenienceandlowproductivityofthesingleblanking.Forworkpieceofmediumdimension,thecombinedblankingisalsousedbecausetomanufactureseveralsimplediesismoreexpensivethanacombineddie.Butifthedistancebetweentheholesorbetweenholeandedgeistoosmall,itisbettertousepropressiveblankingthancompoundandsingleblanking.Sotheprogressiveblankingcanusedtoproduceabnormalworkpieceswithcomplexshapeandsmallwidth,andtheblankingmaterialthicknessinp
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