建模与优化为20H的冷连轧外文文献翻译中英文翻译外文翻译.docx

建模与优化为20H的冷连轧外文文献翻译中英文翻译外文翻译.docx

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建模与优化为20H的冷连轧外文文献翻译中英文翻译外文翻译

附录-外文翻译

Modelingandoptimizationfora20-hcoldrollingmill

QUALITYanditsreproducibilityaredominantcriteriaforcoldrolledproducts.Inparticular,highstripsurfacequalitycanbeachievedwithspecialmillarrangementssuchasthe20-hmill.Thistypeofmillusessmallworkrollsincontactwiththestrip,thatarekeptinplacewithavarietyofintermediateandbackuprolls.Theuseofdifferentactuatorswhich,inpart,onlyactindirectlytoaffecttherollbitegeometry,makesthepresettingofthemillwithregardtostripthicknessandflatnessacomplextask.

Thisarticledescribesamodeltheobjectiveofwhichisoptimizingtheentirerollingprocessina20-hmill.Resultsobtainedfromseveralon-lineapplicationsarediscussed.

Aclosedsendzimirmillarrangement,showninFig.1,illustratesthemainactuatorsthataffectrollbitegeometrywithregardtostripthicknessandglatness.Sideeccentricslocatedatthebackuprollsareusedtoadjusttheoverallpositionofthecorrespondingrollaxisoverawiderangewhich,indirectly,adjuststherollgapgeometrywithregardtothemillpasslineandstripthickness.Sideeccentricsmaybemechanicallyorelectricallycoupled.Crowneccentricsareavailableatseverallocationsoverthebarrellength.Those,typicallyonupperbackuprolls,arecapableofprovidingspecialrollgapcontours.Theymatchthegaptotheprofileofthestripenteringthemill.Crowneccentricsarethemajoractuatorsforachievingstripflatness.Shiftable,firstintermediaterollsarealsoshapeactuators;theymainlyserveformodificationsinthestripedgeareausingataperedrollprofile.

Measurementofmillgeometryisavailableonlyindirectlythroughtherotationofthesideandcrowneccentricsandthroughthepositionofthefirstintermediaterolls.

Considerationofmillspringandelasticdeformationeffectsinthestackleadstotherollgapgeometry.Accountingformillspringandelasticdeformationrequiresknowledgeoftherollseparatingforcewhich,inaclosed20-hmill,ismeasuredindirectlythroughtheadjustmentpressureneededforthemainsideeccentrics.Apartfromhysteresiseffects,theeffectsofthevariablegeometrymakethisindirectmeasurementcritical.

Besidesrollgapgeometry,thetaskofpresettingthemillalsoincludesthedesignofpassschedulestailoredtomeetrequirementsofaproductandthecurrentmillcondition.Whileoptimalutilizationofthemillisamajorobjective,thepassschedulemustachievetherequiredproducequality.Generationofpassschedulestocoverthestatisticalaverageandstoringthemindatabasesrelatedtosteelgrade,surfaceandcoilgeometryisstateofthearttechnology,Inparticular,millparameterssuchasrollgeometryorthethermalconditionoftheworkrollsrequiredynamiccorrectionofthepassschedulestoobtainareproduciblefinalproduct.Thesameappliestovariationsinthematerialcharacteristicsofthecoilsrolled.

Becauseofthecomplexityof20-hmills,achievingreproducibilityofthefinalproductqualityandtheoptimumuseofavailablemillresourcestoincreaseproductivityrepresentsanextremelydifficulttask.Thistaskcanbeaccomplishedwithacomprehensivemodelapproachthattakesallrelevantmillandprocessparametersintoaccount.

Tooptimizetheporcess,variousmathematicalmodelsareneededtodescribetheelasticstandbehaviorandtheelastic/plasticcharacteristicsofthematerialtotherolledbecauseneitherdirectgeometricalinformationnoraccuraterollforcemeasurementsexist.

1、Force,torqueandpower

Therollforce,rolltorqueanddrivepowernecessarytoformthematerialaresomeofthemostimportantitemsofprocessinformation.Whilepowerrequirementsaffectthedesignofapassscheduleforoptimaluseoftheavailablemillresources,rollforceismandatoryforpresettingthegeometricalactuators.Bothforceandtorque,ontheotherhand,needtobeknownformillpresettingsothatmechanicalorpracticallimitsarenotexceeded.

Theapproachselectedtodescribetheeffectsintherollgapwithregardtopower,torqueandforce,isbasedonastripfibermodelusingthebasictheorydevelopedbyKarmanandSiebel.Therollgapmodelprovidesbothverticalandtangentialstresscomponentsactingontheworkroll.Therollseparatingforceresultsfromtheintegrationoftheverticalpressurecomponents.Torqueanddrivepowerarederivedfromthetangentialstress.

Therollgapmodelsimultaneouslyprovidesaccurateinformationabouttheverticalandtangentialstresscomponentsactingontherolland,thus,thedrivepowerandrollforce.

Theabilitytoevaluatetherollingprocess,basedonaccuratecalculationoftherollseparatingforceandmaindrivepower,enhances,inparticular,thematerialyieldstressevaluation.Thisisbeneficialsincetherollforcemeasurementisaffected,toalargeextent,bymeasurementhysteresispresentinaclosed20-hmill.

2、Materialyieldstressadaption

Materialyieldstressadaptionisrequiredinanycasewherethereistheneedtorollawiderangeofsteelgrades.Also,thedemandforself-learningmodelalgorithmsforcestheuseofadaptivemethodswithregardtotheyieldstress.

Theyieldstressofthematerialisinitiallyevaluatedinoff-linetestsusingtorsionbarsamples.Whileoff-linetestsprovidegoodinitialinformation,eachprocessandproducthasitsownpersonality.Thismayresultfromtheannealingpracticesorvariationsinthechemicalcompositionofthesteelgrades.

Theyieldstressadaptionisbrokendownintoashort-termadaptiontorapidlyadjusttheyieldstresscurve,andalong-termadaption,wherecomplexrelationshipsbetweenstrain,strainrateandtemperatureareevaluatedandrepresented.Statisticalyieldstressinformationisavailablebygradeandalsoonanindividualcoilbasisifneeded,whichimprovesqualityassurance.

3、Frictionrepresentation

Besidesobtainingarepresentationofthematerialyieldstress,itisalsomandatorytodescribethefrictionintherollgap.Inavarietyofapplications,thefrictioncoefficientisadjustedsothatduringlong-termanalysisthemostappropriatefrictioncoefficient;ie,,thecoefficientthatprovidesthebestmatchbetweencalculationandmeasurement,isapplied.

Anotherapproachistocarryoutrollingtestsandanalyzetheresults.Whilerollingtestsaffectproduction,theanalysismethodistime-consumingandmayoftenhavethedisadvantagethatnotallrelevantfactorsaffectingfrictionareadequatelyconsidered.Theapproachselectedinthecurrentstudyisbasedonanartificialneuralnetwork.

Theentrylayeroftheneuralnetworkreceivesallrelevantinformationasithasbeengatheredandmayaffectfriction.Thisinformationisprocessedthroughthemultilayerperceptronfeedforwardnetworkinanoff-lineinvestigationusingthebackpropagationmethodfortrainingthat,finally,leadstothefrictioncoefficient.Witharepresentativework,evenphysicalrelationshipsbetweenthefrictioncoefficientandprocessinformationcanbeevaluated.

Theresultsderivedfromtheneuralnetworkhavebeenusedasthebasisforananalyticalmodel,whichwasimplementedon-line.

Theaccuracyoftherepresentationhasbeenevaluatedinseveralon-linerollingtestsinindustrialfacilities.Sincemillspeedisoneofthemainvariablesaffectingfriction,onepasswasmadeduringthecommissioningphaseofthemodelwithdifferentmillspeeds.Boththemeasuredandcalculatedrollforcewererecorded.

Apartfromthefrictioncoefficient,boththetemperatureofthestripapproachingtherollbiteandthestrainvariedinthetest.

4、Elasticmillstandbehavior

Inadditiontorollforce,powerandtorque,theelasticbehaviorofthemillstandmustalsobedescribedtoallowpropagationfromthemeasuredeccentricadjustmentstotherollbitecontour,whichisthetargetforfurtheroptimizationsteps.

Onerequirementintheelasticmillstandmodelwasitsabilitytocoveravarietyofdifferentmillconfigurations,rollprofilesandrollmaterials.Thesevariableswerealsospecifiedwithrespecttoeachindividualrollinthestacktocoversituationswhereunusualrollcombinationsareselectedandtoallowthemodeltobeusedduringdesignphases.

Toprovidemaximumflexibility,thedescriptionoftheelasticmillstandbehaviorisbasedonanumericalsolutionapproachfortherollstack.Thedifferenteffects,suchasflatteningbetweentherolls,flatteningbetweenthestripandtheworkrolls,anddeflectionoftheseveralrolls,arederivedfrommultipleiterations.

Theelasticmillstandmodelforthe20-hcoldrollingmillcan,generally,bedividedintotwoparts.Theinitialphaseinvolvesarapiddeterminationoftheloadshareinthesecondphase.Theinitialloadsharederivedisthentaken,inthesecondphase,asbasisfortheiterativedeterminationoftheinteractionbetweenloaddistribution,flatteninganddeflection.

Thedeflectionofeachrollisderivedfromtheloaddistributiondeterminedineachiterationstep.Thegeometricaldifferencesbetweenneighboringrollsareinterpretedasflatteningoftherollsforwhichacertainloaddistributionmustbepresent.Thisleadstoanewloadalongthecontactareaofthevariousrolls.Thisnewloaddistributionleads,again,toanewdeflection.

Thetotaleffectofelasticdeformationbetweentherollsproducesanewloadatthesaddlesegmentsofthebackuprolls.Thus,themillspringappearstobedifferent,andanewiterationneedstobeperformed.Theiterationiscarriedoutuntilasolutionhasbeenreached,wheretheentireload,thedeflectionandflatteningmatch.

5、Summary

Theaccuracyofforcemeasurementinaclosedsendzimirmillisinadequateforhigh-precisionprocesscontrol.Tosolvethisproblem,specialmodelfordeterminationofrollfor