中英文翻译冲压成形的特点与板材冲压成形性能.doc
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邵阳学院毕业设计(论文)1CharacteristicsofStampingandPropertiesofSheetMetalForming1.overviewStampingisakindofplasticformingprocessinwhichapartisproducedbymeansoftheplasticformingthematerialundertheactionofadie.Stampingisusuallycarriedoutundercoldstate,soitisalsocalledstamping.Heatstampingisusedonlywhentheblankthicknessisgreaterthan8~100mm.Theblankmaterialforstampingisusuallyintheformofsheetorstrip,andthereforeitisalsocalledsheetmetalforming.Somenon-metalsheets(suchasplywood,micasheet,asbestos,leather)canalsobeformedbystamping.Stampingiswidelyusedinvariousfieldsofthemetalworkingindustry,anditplaysacrucialroleintheindustriesformanufacturingautomobiles,instruments,militarypartsandhouseholdelectricalappliances,etc.Theprocess,equipmentanddiearethethreefoundationalproblemsthatneededtobestudiedinstamping.Thecharacteristicsofthesheetmetalformingareasfollows:(1)Highmaterialutilization(2)Capacitytoproducethin-walledpartsofcomplexshape.(3)Goodinterchangeabilitybetweenstampingpartsduetoprecisioninshapeanddimension.(4)Partswithlightweight,high-strengthandfinerigiditycanbeobtained.(5)Highproductivity,easytooperateandtorealizemechanizationandautomatization.Themanufactureofthestampingdieiscostly,andthereforeitonlyfitstomassproduction.Forthemanufactureofproductsinsmallbatchandrichvariety,thesimplestampingdieandthenewequipmentsuchasastampingmachiningcenter,areusuallyadoptedtomeetthemarketdemands.Thematerialsforsheetmetalstampingincludemildsteel,copper,aluminum,magnesiumalloyandhigh-plasticityalloy-steel,etc.Stampingequipmentincludesplateshearpunchingpress.Theformershearsplateinto邵阳学院毕业设计(论文)2stripswithadefinitewidth,whichwouldbepressedlater.Thelatercanbeusedbothinshearingandforming.2.CharacteristicsofstampingformingTherearevariousprocessesofstampingformingwithdifferentworkingpatternsandnames.Buttheseprocessesaresimilartoeachotherinplasticdeformation.Therearefollowingconspicuouscharacteristicsinstamping:(1).Theforceperunitareaperpendiculartotheblanksurfaceisnotlargebutisenoughtocausethematerialplasticdeformation.Itismuchlessthantheinnerstressesontheplateplanedirections.Inmostcasesstampingformingcanbetreatedapproximatelyasthatoftheplanestressstatetosimplifyvastlythetheoreticalanalysisandthecalculationoftheprocessparameters.(2).Duetothesmallrelativethickness,theanti-instabilitycapabilityoftheblankisweakundercompressivestress.Asaresult,thestampingprocessisdifficulttoproceedsuccessfullywithoutusingtheanti-instabilitydevice(suchasblankholder).Thereforethevarietiesofthestampingprocessesdominatedbytensilestressaremorethandominatedbycompressivestress.(3).Duringstampingforming,theinnerstressoftheblankisequaltoorsometimeslessthantheyieldstressofthematerial.Inthispoint,thestampingisdifferentfromthebulkforming.Duringstampingforming,theinfluenceofthehydrostaticpressureofthestressstateinthedeformationzonetotheforminglimitandthedeformationresistanceisnotsoimportantastothebulkforming.Insomecircumstances,suchinfluencemaybeneglected.Eveninthecasewhenthisinfluenceshouldbeconsidered,thetreatingmethodisalsodifferentfromthatofbulkforming.(4).Instampingforming,therestrainactionofthedietotheblankisnotseversasinthecaseofthebulkforming(suchasdieforging).Inbulkforming,theconstraintformingisproceededbythediewithexactlythesameshapeofthepart.Whereasinstamping,inmostcases,theblankhasacertaindegreeoffreedom,onlyonesurfaceoftheblankcontactswiththedie.Insomeextracases,suchastheformingoftheblankonthe邵阳学院毕业设计(论文)3deformingzonecontactwiththedie.Thedeformationintheseregionsarecausedandcontrolledbythedieapplyinganexternalforcetoitsadjacentarea.Duetothecharacteristicsofstampingdeformationandmechanicsmentionedabove,thestampingtechniqueisdifferentformthebulkmetalforming:(1).Theimportanceorthestrengthandrigidityofthedieinstampingformingislessthanthatinbulkformingbecausetheblankcanbeformedwithoutapplyinglargepressureperunitareaonitssurface.Instead,thetechniquesofthesimpledieandthepneumaticandhydraulicformingaredeveloped.(2).Duetotheplanestressorsimplestrainstateincomparisonwithbulkforming,moreresearchondeformationorforceandpowerparametershasbeendone.Stampingformingcanbeperformedbymorereasonablescientificmethods.Basedontherealtimemeasurementandanalysisonthesheetmetalpropertiesandstampingparameters,bymeansofcomputerandsomemoderntestingapparatus,researchontheintellectualizedcontrolofstampingprocessisalsoinproceeding.(3).Itisshownthatthereisacloserelationshipbetweenstampingformingandrawmaterial.Theresearchonthepropertiesofthestampingforming,thatis,formingabilityandshapestability,hasbecomeakeypointinstampingtechnologydevelopment,butalsoenhancesthemanufacturingtechniqueofironandsteelindustry,andprovidesareliablefoundationforincreasingsheetmetalquality.3.CategoriesofstampingformingManydeformationprocessescanbedonebystamping,thebasicprocessesofthestampingcanbedividedintotwokinds:cuttingandforming.Cuttingisashearingprocessthatonepartoftheblankiscutfromtheother.Itmainlyincludesblanking,punching,trimming,partingandshaving,wherepunchingandblankingarethemostwidelyused.Formingisaprocessthatonepartoftheblankhassomedisplacementfromtheother.Itmainlyincludesdeepdrawing,bending,localforming,bulging,flanging,necking,sizingandspinning.Insubstance,stampingformingissuchthattheplasticdeformationoccursinthe邵阳学院毕业设计(论文)4deformationzoneofthestampingblankcausedbytheexternalforce.Thestressstateanddeformationcharacteristicofthedeformationzonearethebasicfactorstodecidethepropertiesofthestampingforming.Basedonthestressstateanddeformationcharacteristicsofthedeformationzone,theformingmethodscanbedividedintoseveralcategorieswiththesameformingpropertiesandbestudiedsystematically.Thedeformationzoneinalmostalltypesofstampingformingisintheplanestressstate.Usuallythereisnoforceoronlysmallforceappliedontheblanksurface.Whenisassumedthatthestressperpendiculartotheblanksurfaceequalstozero,twoprincipalstressesperpendiculartoeachotherandactontheblanksurfaceproducetheplasticdeformationofthematerial.Duetothesmallthicknessoftheblank,itisassumedapproximatelythetwoprincipalstressesdistributeuniformlyalongthethicknessdirection.Basedonthisanalysis,thestressstateandthedeformationcharacteristicsofthedeformationzoneinallkindsofstampingformingcanbedenotedbythepointsinthecoordinatesoftheplaneprincipalstressesandthecoordinatesofthecorrespondingplaneprincipalstrains.4.RawmaterialsforstampingformingTherearealotofrawmaterialsusedinstampingforming,andthepropertiesofthesematerialsmayhavelargedifference.Thestampingformingcanbesucceededonlybydeterminingthestampingmethod,theformingparametersandthediestructuresaccordingtothepropertiesandcharacteristicsoftherawmaterials.Thedeformationoftheblankduringstampingforminghasbeeninvestigatedquitethoroughly.Therelationshipsbetweenthematerialpropertiesdecidedbythechemistrycomponentandstructureofthematerialandthestampingforminghasbeenestablishedclearly.Notonlythepropermaterialcanbeselectedbasedontheworkingconditionandusagedemand,butalsothenewmaterialcanbedevelopedaccordingtothedemandsoftheblankpropertiesduringprocessingthestampingpart.Thisisanimportantdomaininstampingformingresearch.Theresearchonthematerialpropertiesforstampingformingisasfollows:(1).Definitionofthestampingpropertyofthematerial.
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