微盒形件拉深成形中尺度效应的研究

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1、万方数据微盒形件拉深成形中尺度效应的研究万方数据江苏大学专业硕士学位论文ABSTRACTAsthemicro-electromechanicalsystemdevelopsrapidly，thedemandformicropartsisalsogrowing．Microformingisconsideredthebestandmostsuitableprocessformassproductionofmicropartsformingbecauseofhighefficiencyandlowcostformassproductionofmicro—pr

2、oducts．Undermicroscale，material’Sstress—straincurve，yieldratio，theplasticstrainratio，elongationetc．aredifferentfromthematerialatregularsize，namelythescaleeffectwhichmakesimpactofscaleeffectsbeconsideredaboutthetechnologyparametersandnumericalsimulationofmicro—plasticformingproce

3、ss．Inthispaper，thescaleeffectofrectangularboxdeepdrawingmaterials，diesize，processconditionswerestudied．Themainresearchresultsobtainedareasfollows：1)Inthispaper，O．02mm，O．05mm，0．1mm，0．2mm，0．4mmofSUS304werequenchedtoobtaindifferentgrainsizesofdifferentthicknesssheet．Theuniaxialtens

4、iletestwasconducted．Theyieldstrengthoftheexperimentalresultedthatsheetquenchedshoweda”smallerweaker”phenomenonatlessthanO．1mmandthesheetshowedthe”smallerisstronger”phenomenonwithoutbeingquenched．Itwasalsofoundthatitmadetheplasticstrainratiodecreasetoreducethethickness．Elongation

5、firstdecreasedandthenincreasedasthicknessdecreased．2)ThemicrodrawingsimulationofboxpartswasconductedwithDYNAFORMbyusingdataobtainedfromuniaxialtensiontest．Thestressandstraindistributionandthicknessvariationoftheboxpartswasanalyzed．Theresultsshowedthatthemicro—punchflletofrectang

6、ularboxnotonlydistributedthemostcomplicatedstressandstraindistributionarea，butalsowasthelargestthinningrateofregion．Itwasfoundthattheeffectsofpunchanddieradius，clearancebetweenpunchanddie，thediecomerradiusonthemicrodrawingweresimilarwiththemacroforming．Theresultsshowedthateffect

7、sofdrawingspeedonwasnotobvious．Frictioninfluencedsignificantonthemicrodeepdrawingofrectangularboxparts．Theformulaofblankholderforceinthemacrorectangularboxpartswasnotapplicabletodrawing．3)Accordingtotheresultsofsimulation，microrectangularboxdieswasdesigned．Differentthicknessandd

8、ifferentquenchingsheetswereconductedexperiments