【英语翻译2.Materialflowoptimisationincoldandwarmforging2.1.AvoidinglapsIncertainconditionsofdeformationthematerialcanbucklecausingcollapseoffreesurfaceresultinginlapsandfolds.Lapsarethedefectsthatappearwhenfrees】

　　英语翻译

　　2.Materialflowoptimisationincoldandwarmforging

　　2.1.Avoidinglaps

　　Incertainconditionsofdeformationthematerialcanbucklecausingcollapseoffreesurface

　　resultinginlapsandfolds.Lapsarethedefectsthatappearwhenfreesurfaceofmaterial

　　foldsoveritself.Frompracticalpointofviewthelapsareveryannoyingkindofdefects

　　becausetheytendtoappeareachtimewhenwewanttointensifydeformationforcost

　　reduction,forexample,whenwetrytoskippreformingoperation.Thelapcanoccurinrib-

　　webforgingatavarietyoflocationswheretheribmaybuckle.Sometimeslapscanappear

　　whenwetrytoupsetabilletwithdiametertoheightratiowithinadmissiblelimitbutdueto

　　smalldeviationsfromidealshapeornon-parallelcutsthebilletmaybuckle.

　　ThefullyautomaticfiniteelementmeshgenerationimplementedinQFormensuressimulationofsurface-to-surfacecontactthathappensinalaparea.Itisveryimportantforreliablepredictionofthisdefect.Theprogramautomaticallyincreasesmeshdensityincriticalareawhenthesurfacestartstocollapse.

　　Thisfeatureisillustratedbypracticalexampleofwarmforgingofthecamofovalshapewithtworoundoff-centrecavitiesofdifferentdepth.Thisis3Dproblem.Whenusingcylindricalbilletthematerialfirstfillstheshorter“arm”ofthecamandthenflowsincircumferentialdirectiontowardsitslong“arm”andthelapsoccuronitsupperandlowersurfaces(Fig1b).Thepinonthelowerdieishigherthanontheupperdieandlowerlapismoredevelopedthenupperone.Theprogramautomaticallydetectsthezoneswherethelappotentiallymayoccurandautomaticallyincreasesthemeshdensitythere(Fig2.b).Thustheprogramisabletodetectthefinestpeculiaritiesofthematerialflowandisverysensitive.