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1、1CharacteristicsofStampingandPropertiesofSheetMetalForming1overviewStampingisakindofplasticformingprocessinwhichapartisproducedbymeansoftheplasticformingthematerialundertheactionofadie.Stampingisusuallycarriedoutundercoldstate,soitisalsocalledstamping.Heatstampingisusedonlywhentheblankthicknessisgre
2、aterthan8100mm.Theblankmaterialforstampingisusuallyintheformofsheetorstrip,andthereforeitisalsocalledsheetmetalforming.Somenon-metalsheets(suchasplywood,micasheet,asbestos,leather)canalsobeformedbystamping.Stampingiswidelyusedinvariousfieldsofthemetalworkingindustry,anditplaysacrucialroleintheindust
3、riesformanufacturingautomobiles,instruments,militarypartsandhouseholdelectricalappliances,etc.Theprocess,equipmentanddiearethethreefoundationalproblemsthatneededtobestudiedinstamping.Thecharacteristicsofthesheetmetalformingareasfollows:(1)Highmaterialutilization(2)Capacitytoproducethin-walledpartsof
4、complexshape.(3)Goodinterchangeabilitybetweenstampingpartsduetoprecisioninshapeanddimension.(4)Partswithlightweight,high-strengthandfinerigiditycanbeobtained.(5)Highproductivity,easytooperateandtorealizemechanizationandautomatization.Themanufactureofthestampingdieiscostly,andthereforeitonlyfitstomas
5、sproduction.Forthemanufactureofproductsinsmallbatchandrichvariety,thesimplestampingdieandthenewequipmentsuchasastampingmachiningcenter,areusuallyadoptedtomeetthemarketdemands.Thematerialsforsheetmetalstampingincludemildsteel,copper,aluminum,magnesiumalloyandhigh-plasticityalloy-steel,etc.Stampingequ
6、ipmentincludesplateshearpunchingpress.Theformershearsplateinto2stripswithadefinitewidth,whichwouldbepressedlater.Thelatercanbeusedbothinshearingandforming.2CharacteristicsofstampingformingTherearevariousprocessesofstampingformingwithdifferentworkingpatternsandnames.Buttheseprocessesaresimilartoeacho
7、therinplasticdeformation.Therearefollowingconspicuouscharacteristicsinstamping:（1）Theforceperunitareaperpendiculartotheblanksurfaceisnotlargebutisenoughtocausethematerialplasticdeformation.Itismuchlessthantheinnerstressesontheplateplanedirections.Inmostcasesstampingformingcanbetreatedapproximatelyas
8、thatoftheplanestressstatetosimplifyvastlythetheoreticalanalysisandthecalculationoftheprocessparameters.（2）Duetothesmallrelativethickness,theanti-instabilitycapabilityoftheblankisweakundercompressivestress.Asaresult,thestampingprocessisdifficulttoproceedsuccessfullywithoutusingtheanti-instabilitydevi
9、ce(suchasblankholder).Thereforethevarietiesofthestampingprocessesdominatedbytensilestressaremorethandominatedbycompressivestress.（3）Duringstampingforming,theinnerstressoftheblankisequaltoorsometimeslessthantheyieldstressofthematerial.Inthispoint,thestampingisdifferentfromthebulkforming.Duringstampin
10、gforming,theinfluenceofthehydrostaticpressureofthestressstateinthedeformationzonetotheforminglimitandthedeformationresistanceisnotsoimportantastothebulkforming.Insomecircumstances,suchinfluencemaybeneglected.Eveninthecasewhenthisinfluenceshouldbeconsidered,thetreatingmethodisalsodifferentfromthatofb
11、ulkforming.（4）Instampingforming,therestrainactionofthedietotheblankisnotseversasinthecaseofthebulkforming(suchasdieforging).Inbulkforming,theconstraintformingisproceededbythediewithexactlythesameshapeofthepart.Whereasinstamping,inmostcases,theblankhasacertaindegreeoffreedom,onlyonesurfaceoftheblankc
12、ontactswiththedie.Insomeextracases,suchastheformingoftheblankonthe3deformingzonecontactwiththedie.Thedeformationintheseregionsarecausedandcontrolledbythedieapplyinganexternalforcetoitsadjacentarea.Duetothecharacteristicsofstampingdeformationandmechanicsmentionedabove,thestampingtechniqueisdifferentf
13、ormthebulkmetalforming:（1）Theimportanceorthestrengthandrigidityofthedieinstampingformingislessthanthatinbulkformingbecausetheblankcanbeformedwithoutapplyinglargepressureperunitareaonitssurface.Instead,thetechniquesofthesimpledieandthepneumaticandhydraulicformingaredeveloped.（2）Duetotheplanestressors
14、implestrainstateincomparisonwithbulkforming,moreresearchondeformationorforceandpowerparametershasbeendone.Stampingformingcanbeperformedbymorereasonablescientificmethods.Basedontherealtimemeasurementandanalysisonthesheetmetalpropertiesandstampingparameters,bymeansofcomputerandsomemoderntestingapparat
15、us,researchontheintellectualizedcontrolofstampingprocessisalsoinproceeding.（3）Itisshownthatthereisacloserelationshipbetweenstampingformingandrawmaterial.Theresearchonthepropertiesofthestampingforming,thatis,formingabilityandshapestability,hasbecomeakeypointinstampingtechnologydevelopment,butalsoenha
16、ncesthemanufacturingtechniqueofironandsteelindustry,andprovidesareliablefoundationforincreasingsheetmetalquality.3CategoriesofstampingformingManydeformationprocessescanbedonebystamping,thebasicprocessesofthestampingcanbedividedintotwokinds:cuttingandforming.Cuttingisashearingprocessthatonepartoftheb
17、lankiscutfromtheother.Itmainlyincludesblanking,punching,trimming,partingandshaving,wherepunchingandblankingarethemostwidelyused.Formingisaprocessthatonepartoftheblankhassomedisplacementfromtheother.Itmainlyincludesdeepdrawing,bending,localforming,bulging,flanging,necking,sizingandspinning.Insubstanc
18、e,stampingformingissuchthattheplasticdeformationoccursinthe4deformationzoneofthestampingblankcausedbytheexternalforce.Thestressstateanddeformationcharacteristicofthedeformationzonearethebasicfactorstodecidethepropertiesofthestampingforming.Basedonthestressstateanddeformationcharacteristicsofthedefor
19、mationzone,theformingmethodscanbedividedintoseveralcategorieswiththesameformingpropertiesandbestudiedsystematically.Thedeformationzoneinalmostalltypesofstampingformingisintheplanestressstate.Usuallythereisnoforceoronlysmallforceappliedontheblanksurface.Whenisassumedthatthestressperpendiculartothebla
20、nksurfaceequalstozero,twoprincipalstressesperpendiculartoeachotherandactontheblanksurfaceproducetheplasticdeformationofthematerial.Duetothesmallthicknessoftheblank,itisassumedapproximatelythetwoprincipalstressesdistributeuniformlyalongthethicknessdirection.Basedonthisanalysis,thestressstateandthedef
21、ormationcharacteristicsofthedeformationzoneinallkindsofstampingformingcanbedenotedbythepointsinthecoordinatesoftheplaneprincipalstressesandthecoordinatesofthecorrespondingplaneprincipalstrains.4RawmaterialsforstampingformingTherearealotofrawmaterialsusedinstampingforming,andthepropertiesofthesemater
22、ialsmayhavelargedifference.Thestampingformingcanbesucceededonlybydeterminingthestampingmethod,theformingparametersandthediestructuresaccordingtothepropertiesandcharacteristicsoftherawmaterials.Thedeformationoftheblankduringstampingforminghasbeeninvestigatedquitethoroughly.Therelationshipsbetweenthem
23、aterialpropertiesdecidedbythechemistrycomponentandstructureofthematerialandthestampingforminghasbeenestablishedclearly.Notonlythepropermaterialcanbeselectedbasedontheworkingconditionandusagedemand,butalsothenewmaterialcanbedevelopedaccordingtothedemandsoftheblankpropertiesduringprocessingthestampingpart.Thisisanimportantdomaininstampingformingresearch.Theresearchonthematerialpropertiesforstampingformingisasfollows:（1）Definitionofthestampingpropertyofthematerial.
中英文翻譯---沖壓成形的特點(diǎn)與板材沖壓成形性能.doc
