机械类文献翻译冲压成形的特点与板材冲压成形性能.docx
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机械类文献翻译冲压成形的特点与板材冲压成形性能
CharacteristicsofStampingandPropertiesof
SheetMetalForming
1.overview
Stampingisakindofplasticformingprocessinwhichapartisproducedbymeansoftheplasticformingthematerialundertheactionofadie.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)Goodinterchangeabilitybetweenstampingpartsduetoprecisioninshape
anddimension.
(4)Partswithlightweight,high-strengthandfinerigiditycanbeobtained.
(5)Highproductivity,easytooperateandtorealizemechanizationandautomatization.
Themanufactureofthestampingdieiscostly,andthereforeitonlyfitstomassproduction.Forthemanufactureofproductsinsmallbatchandrichvariety,thesimplestampingdieandthenewequipmentsuchasastampingmachiningcenter,areusuallyadoptedtomeetthemarketdemands.
Thematerialsforsheetmetalstampingincludemildsteel,copper,aluminum,magnesiumalloyandhigh-plasticityalloy-steel,etc.
Stampingequipmentincludesplateshearpunchingpress.Theformershearsplateintostripswithadefinitewidth,whichwouldbepressedlater.Thelatercanbeusedbothinshearingandforming.
2.Characteristicsofstampingforming
Therearevariousprocessesofstampingformingwithdifferentworkingpatternsandnames.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.
(2).Duetotheplanestressorsimplestrainstateincomparisonwithbulkforming,moreresearchondeformationorforceandpowerparametershasbeendone.Stampingformingcanbeperformedbymorereasonablescientificmethods.Basedontherealtimemeasurementandanalysisonthesheetmetalpropertiesandstampingpa