平行矫正辊的数量对矫正过程的影响设计外文文献翻译中英文翻译外文翻译.docx
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平行矫正辊的数量对矫正过程的影响设计外文文献翻译中英文翻译外文翻译.docx
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平行矫正辊的数量对矫正过程的影响设计外文文献翻译中英文翻译外文翻译
原文
TheEffectoftheNumberofLevelingRollsontheStraighteningProcess
CurvatureAnalysis
Theoutputofthestrainmodelcanbeusedtoformulateafundamentalunderstandingofthelevelingprocess.Aseriesofsimulationswasrunfor3/8-inch-gaugematerialwithayieldstrengthof50ksi.Thesimulationswereperformedforan11-rolllevelerwithfivetoprollsandsixbottomrolls,whichhas6-inch-diameterrollsspacedon10-inchcenter.
Twoparameterswerevariedduringthestudy:
theextentofplasticdeformationandthemagnitudeoftheinitialflatnessdefects.Themodelwasrunforlevelsofplasticdeformationrangingfrom20%tomorethan90%ofthematerial’scross-section.Forexample,afractionplasticallydeformedof0.50representsabendthatcreatesyieldingin50%ofthecross-section—theoutermost25%atthetopandbottomsurfaces.Theincludestressesintheinnermost50%ofthecross-sectionneverexceedtheyieldstress.
Foreachlevelofplastification,themodeltracksthestrainhistoryforeachinitialconditionthrougheverybendintheleveler,andpredictstheexitingflatnesscondition.Theexitingflatnessconditionrepresentsthepredicteddeviationoftheplatefromahorizontalflatsurfaceovera12-footlength,asprescribedintheASTMA6standardforplate.TheoutputofthestudyisshowninFigures10~13.
Figure10showsthemannerinwhichthepredictedcurvaturevariesastheextentofplasticdeformationchangesformaterialwithaninitialradiusofcurvatureof15inches.Thiscurvaturerepresentstheconditionoftheinsidewrapofacoilwitha30-inchinsidediameter.Threeinitiallongitudinalflatnessconditionaresimulated:
aninitialpositiveradiusofcurvatureof15inches(bowedup);aninitialnegativeradiusofcurvatureof15inch(boweddown);andaninitiallyflatregion.Threeinitialconditionsareincludedtoexaminetheirinfluenceontheexitingflatnessprediction.Intheanalysisofcoilprocessing,theinitiallyflatconditionservesasacontrolcondition.However,itisusefulintheanalysisofdiscreteplatelevelingbecausetheincomingflatnessdefectsvaryfromonelocationtoanother,andadiscreteplategenerallyhassomeareasthatareinitiallyflat.
Figure10
ThemodelpredictionsdisplayedinFigure10showthat,atlowlevelsofplasticdeformation,thethreeinitialconditionsresultinthreedistinctlydifferentexitingconditions.Themagnitudesoftheinitialflatnessdefectsarereduced,buttheyarestilllarge.Theinitiallybowed-updefectexitsthelevelerwithanupwardbowofapproximately5.5inchesovera12-footlength,evenwhentherollgapofthelevelerissettogenerateaplasticfractionofonly0.20.Theinitiallybowed-downdefectalsoexitsthelevelerwithcurvatureinthesamedirectionastheincomingdefect(adownwardbow),butthemagnitudeofthedefectisreducedto3.60inches.Theinitiallyflatconditionexitsthelevelerwithadefectthatisbowedupwardalmost1inch,reflectingtheapplicationofthepositivebendingcurvatureduringthefirstbendintheleveler,Thelowlevelofplasticdeformationimpartsapositivecurvatureisretainedaftertheeffectofspringback.Theremainingbendsinthelevelerdonotapplysufficientplasticdeformationtoreducethemagnitudeofthecurvature.
Astheextentofplasticdeformationincreases,thepredictedexitingflatnessdefectsdecreaseinmagnitude,andtheexitingconditionsforthethreedifferentinitialcurvatureseventuallyconvergetothesamevalueatafractionplasticdeformationof0.62.Thepointbeyondwhichthecurvesthedifferentincomingconditionsidenticallycoincideistermedtheconvergencepoint.
Theexitingflatnessconditiondisplaysanoscillatorywithplastificationratesgreaterthan50%.Thepredictedexitingconditionisabowupforplastificationratesbelow53%.Theexitingflatnessconditionisperfectlyflatatafractionplasticof0.53,withentryrollgapofthelevelerissettogenerateplastificationratesbetween53%and64%,thepredictedexitingflatnessconditionisabowdown.Themaximumpredictedbowin12feetis5/8inch,andoccursatafractionplasticof0.58.Theexitingflatnessconditionagaincrossesthehorizontalaxisat0.64,andanupwardcurvatureisproducedforsettingsbetween0.64and0.75.Themaximumbowupis1.2inches,whichcorrespondstoafractionplasticof0.70.Athirdcrossoverpointoccursat0.75,whereperfectflatnessisagainpredicted.Downwardcurvaturesareproducedbetweenplastificationratesof75%and85%,withapeakbowof2.25inchesoccurringat80%plasticdeformation.Thefourthcrossoverpointoccursat0.85,andpositivecurvatureresultsforentrylevelersettingscorrespondingtoplastificationratesbetween85%and94%.Thepeakcurvatureoccursatafractionplasticof0.90,andresultsinabowofmagnitude6.1inches.Thefinalcrossoverpointoccursat0.94,andhigherplastificationratesproducenegativecurvaturesofincreasingmagnitude.Forexample,arollgapsettingthatresultsinaplastificationrateof96%producesadownwardbowof6.2inches.
Theexistenceofseveral“zeropoints”isanunderlyingreasonwhysuccessfullevelingisachievedinpractice,andexplainswhyexperiencedoperatorsmayuseverydifferentsettingsandyetstillobtainthesamelevelingeffectforaparticularcombinationofthicknessandyieldstrength.
Figure11showsthevariationinthepredictedexitingflatnessconditionforthesamematerialwhentheincomingflatnessconditionhasaninitialradiusofcurvatureof50inches.Thisconditionrepresentstheouterwrapsofalargecoilhavinganoutsidediameterof100inches.Thethreeincomingconditionssimulatedareaninitialpositiveradiusofcurvatureof50inches(bowedup),aninitialnegativeradiusofcurvatureof50inches(boweddown),andtheinitiallyflatcontrolcondition.Themodeledresultsarevirtuallyidenticaltothosefortheinitialcurvatureof15inchesshowninFigure10.Noconvergenceinthedirectionoftheexitingflatnessconditionoccursforverylowlevelsofplasticdeformation.Thepredictedexitingdefectisexactlyidenticalfortheinitiallyflatregion(thecontrolconditions)becausethesamedeformationisappliestothesameinitialcondition.Thepredictedexitingvaluesforbothanincomingpositiveradiusofcurvatureof50inchesandanegativeradiusofcurvatureof50inchesareslightlysmallerinmagnitudethanthoseforthe15-inchradiusofcurvatureexample,reflectingthelesssevereinitialflatnessdefect.Thesameamountofflatnesscorrectionappliedtoalessincomingdefectresultsinanexitingdefectofsmallermagnitude.Thepredictedvaluesdecreaseinmagnitudeasthethreedifferentexitingconditionseventuallyconvergetotheexactsamevalue(theconvergencepoint)atafractionplasticof0.62.Thepredictedbehaviorisidenticaltothesimulatedinsidewrapforallplastificationratesgreaterthan62%.Crossoverpointsareagainseenatfractionsplasticallydeformedof0.53,0.64,0.75,0.85and0.94.
Figure11
Figure12displaysthepredictedexitingflatnessconditionforadiscreteplate,ratherthanacoiledproduct,ofthesamematerialprocessedonthesameleveler.Theincomingradiusofcurvatureis1000inches,whichsimulatesaninitialbowupof2.60inchesin12feet,abowdownof2.60inchesandaninitiallyflatregion.Thisrangeofflatnessdefectistypicalofaheattreatedplate.Themodeledresultsaregenerallysimilartothoseforthecoiledconditionsimulations.However,severalmajordifferencescanbenotedbetweenthecoiledanddiscretesimulations:
Figure12
Themagnitudeoftheexitingflatnesspredictionismarkedlysmalleratverylowlevelsofplasticdeformationandispositive(bowedup)forallincomingconditions.Theinitial2.60-inchbowed-updefectisreducedto1.74inches,andtheinitiallybowed-downdefectexitsasa0.28-inchupwardbow,evenwhenonly20%oftheplate’scross-sectionisplasticallydeformed.Thepositivecurvatureappliedduringthefirstbendreversestheincomingcurvaturefromboweddowntobowedup.
Thevariationinthepredictedexitingflatnessconditionissignificantlyreducedforthelesssevereinitialcondition.Therangeofexitingout-of-flatconditionsfortheplateatafractionplasticallydeformedof0.20isfrom0.28to1.74inches,comparedtorangeof-3.60to5.46inchesfortheinsidewrapofacoilprocessedatthesamelevelersettings.
Thepredictedexitingflatnessvalueislessthan0.50inchinmagnitudeforplastificationratesbetween36%and54%.
Theconvergencepointalsooccursatsignificantlyreducedlevelsofplasticdeformationfortheplatesimulation(0.48)comparedtothecoiledproduct(0.62),andtheoscillatorybehaviorbeginsearlier,atafractionplasticallydeformedof0.40.
Thepredictedbehaviorisidenticaltothesimulatedcoiledconditionsforallplastificationratesgreaterthan62%,andcrossoverpointsoccuratthesamelocations(0.53,0.64,0.75,0.85and0.94).
Figure13showsthevariationinthepredictedexitingflatnessconditionfor3/8-inch-gaugediscreteplatewhentheincomingflatnessconditionhasaninitialradiusofcurvatureof2000inches.Thisconditionsimulatesevensmallerincomingdefects,includinganinitialbowupof1.30inches,abowdownof1.30inchesandaninitiallyflatregion.Themagnitudeoftheseflatnessdefectsistypicalofthedistortionseeninanas-rolledandair-cooleddistortionsplate.Thepredictedexitingflatnessconditionsatlowplastificationratesforthiscaseareverysmall,areallbowedupward,andshowlittlevariationbetweenthethreedifferentincomingconditions.Theinitial1.30-inchbowed-updefecti
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