外文翻译--冲压成形与板材冲压.doc

1CharacteristicsandSheetMetalForming1.ThearticleoverviewStampingisakindofplasticformingprocessinwhichapartisproducedbymeansoftheplasticformingthematerialundertheactionofadie.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.Theformershearsplateintostripswithadefinitewidth,whichwouldbepressedlater.Thelatercanbeusedbothinshearingandforming.2Characteristicsofstampingforming2Therearevariousprocessesofstampingformingwithdifferentworkingpatternsandnames.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,suchastheformingoftheblankonthedeformingzonecontactwiththedie.Thedeformationintheseregionsarecausedandcontrolledbythedieapplyinganexternalforcetoitsadjacentarea.Duetothecharacteristicsofstampingdeformationandmechanicsmentionedabove,thestampingtechniqueisdifferentformthebulkmetalforming:（1）Theimportanceorthestrengthandrigidityofthedieinstampingformingislessthanthatinbulkformingbecausetheblankcanbeformedwithoutapplyinglargepressureperunitareaonitssurface.Instead,thetechniquesofthesimpledieandthepneumaticandhydraulicformingaredeveloped.3（2）Duetotheplanestressorsimplestrainstateincomparisonwithbulkforming,moreresearchondeformationorforceandpowerparametershasbeendone.Stampingformingcanbeperformedbymorereasonablescientificmethods.Basedontherealtimemeasurementandanalysisonthesheetmetalpropertiesandstampingparameters,bymeansofcomputerandsomemoderntestingapparatus,researchontheintellectualizedcontrolofstampingprocessisalsoinproceeding.（3）Itisshownthatthereisacloserelationshipbetweenstampingformingandrawmaterial.Theresearchonthepropertiesofthestampingforming,thatis,formingabilityandshapestability,hasbecomeakeypointinstampingtechnologydevelopment,butalsoenhancesthemanufacturingtechniqueofironandsteelindustry,andprovidesareliablefoundationforincreasingsheetmetalquality.3CategoriesofstampingformingManydeformationprocessescanbedonebystamping,thebasicprocessesofthestampingcanbedividedintotwokinds:cuttingandforming.Cuttingisashearingprocessthatonepartoftheblankiscutfromtheother.Itmainlyincludesblanking,punching,trimming,partingandshaving,wherepunchingandblankingarethemostwidelyused.Formingisaprocessthatonepartoftheblankhassomedisplacementfromtheother.Itmainlyincludesdeepdrawing,bending,localforming,bulging,flanging,necking,sizingandspinning.Insubstance,stampingformingissuchthattheplasticdeformationoccursinthedeformationzoneofthestampingblankcausedbytheexternalforce.Thestressstateanddeformationcharacteristicofthedeformationzonearethebasicfactorstodecidethepropertiesofthestampingforming.Basedonthestressstateanddeformationcharacteristicsofthedeformationzone,theformingmethodscanbedividedintoseveralcategorieswiththesameformingpropertiesandbestudiedsystematically.Thedeformationzoneinalmostalltypesofstampingformingisintheplanestressstate.Usuallythereisnoforceoronlysmallforceappliedontheblanksurface.Whenisassumedthatthestressperpendiculartotheblanksurfaceequalstozero,twoprincipalstressesperpendiculartoeachotherandactontheblanksurfaceproducetheplasticdeformationofthematerial.Duetothesmallthicknessoftheblank,itisassumedapproximatelythetwoprincipalstressesdistributeuniformlyalongthethicknessdirection.Basedonthisanalysis,thestressstateandthedeformationcharacteristicsofthedeformationzoneinallkindsofstampingformingcanbe4denotedbythepointsinthecoordinatesoftheplaneprincipalstressesandthecoordinatesofthecorrespondingplaneprincipalstrains.4RawmaterialsforstampingformingTherearealotofrawmaterialsusedinstampingforming,andthepropertiesofthesematerialsmayhavelargedifference.Thestampingformingcanbesucceededonlybydeterminingthestampingmethod,theformingparametersandthediestructuresaccordingtothepropertiesandcharacteristicsoftherawmaterials.Thedeformationoftheblankduringstampingforminghasbeeninvestigatedquitethoroughly.Therelationshipsbetweenthematerialpropertiesdecidedbythechemistrycomponentandstructureofthematerialandthestampingforminghasbeenestablishedclearly.Notonlythepropermaterialcanbeselectedbasedontheworkingconditionandusagedemand,butalsothenewmaterialcanbedevelopedaccordingtothedemandsoftheblankpropertiesduringprocessingthestampingpart.Thisisanimportantdomaininstampingformingresearch.Theresearchonthematerialpropertiesforstampingformingisasfollows:（1）Definitionofthestampingpropertyofthematerial.（2）Methodtojudgethestampingpropertyofthematerial,findparameterstoexpressthedefinitelymaterialpropertyofthestampingforming,establishtherelationshipbetweenthepropertyparametersandthepracticalstampingforming,andinvestigatethetestingmethodsofthepropertyparameters.（3）Establishtherelationshipamongthechemicalcomponent,structure,manufacturingprocessandstampingproperty