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外文翻译--建模与优化为20 - H的冷连轧.doc

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外文翻译--建模与优化为20 - H的冷连轧.doc

附录外文翻译Modelingandoptimizationfora20hcoldrollingmillQUALITYanditsreproducibilityaredominantcriteriaforcoldrolledproducts.Inparticular,highstripsurfacequalitycanbeachievedwithspecialmillarrangementssuchasthe20hmill.Thistypeofmillusessmallworkrollsincontactwiththestrip,thatarekeptinplacewithavarietyofintermediateandbackuprolls.Theuseofdifferentactuatorswhich,inpart,onlyactindirectlytoaffecttherollbitegeometry,makesthepresettingofthemillwithregardtostripthicknessandflatnessacomplextask.Thisarticledescribesamodeltheobjectiveofwhichisoptimizingtheentirerollingprocessina20hmill.Resultsobtainedfromseveralonlineapplicationsarediscussed.Aclosedsendzimirmillarrangement,showninFig.1,illustratesthemainactuatorsthataffectrollbitegeometrywithregardtostripthicknessandglatness.Sideeccentricslocatedatthebackuprollsareusedtoadjusttheoverallpositionofthecorrespondingrollaxisoverawiderangewhich,indirectly,adjuststherollgapgeometrywithregardtothemillpasslineandstripthickness.Sideeccentricsmaybemechanicallyorelectricallycoupled.Crowneccentricsareavailableatseverallocationsoverthebarrellength.Those,typicallyonupperbackuprolls,arecapableofprovidingspecialrollgapcontours.Theymatchthegaptotheprofileofthestripenteringthemill.Crowneccentricsarethemajoractuatorsforachievingstripflatness.Shiftable,firstintermediaterollsarealsoshapeactuatorstheymainlyserveformodificationsinthestripedgeareausingataperedrollprofile.Measurementofmillgeometryisavailableonlyindirectlythroughtherotationofthesideandcrowneccentricsandthroughthepositionofthefirstintermediaterolls.Considerationofmillspringandelasticdeformationeffectsinthestackleadstotherollgapgeometry.Accountingformillspringandelasticdeformationrequiresknowledgeoftherollseparatingforcewhich,inaclosed20hmill,ismeasuredindirectlythroughtheadjustmentpressureneededforthemainsideeccentrics.Apartfromhysteresiseffects,theeffectsofthevariablegeometrymakethisindirectmeasurementcritical.Besidesrollgapgeometry,thetaskofpresettingthemillalsoincludesthedesignofpassschedulestailoredtomeetrequirementsofaproductandthecurrentmillcondition.Whileoptimalutilizationofthemillisamajorobjective,thepassschedulemustachievetherequiredproducequality.Generationofpassschedulestocoverthestatisticalaverageandstoringthemindatabasesrelatedtosteelgrade,surfaceandcoilgeometryisstateofthearttechnology,Inparticular,millparameterssuchasrollgeometryorthethermalconditionoftheworkrollsrequiredynamiccorrectionofthepassschedulestoobtainareproduciblefinalproduct.Thesameappliestovariationsinthematerialcharacteristicsofthecoilsrolled.Becauseofthecomplexityof20hmills,achievingreproducibilityofthefinalproductqualityandtheoptimumuseofavailablemillresourcestoincreaseproductivityrepresentsanextremelydifficulttask.Thistaskcanbeaccomplishedwithacomprehensivemodelapproachthattakesallrelevantmillandprocessparametersintoaccount.Tooptimizetheporcess,variousmathematicalmodelsareneededtodescribetheelasticstandbehaviorandtheelastic/plasticcharacteristicsofthematerialtotherolledbecauseneitherdirectgeometricalinformationnoraccuraterollforcemeasurementsexist.1、Force,torqueandpowerTherollforce,rolltorqueanddrivepowernecessarytoformthematerialaresomeofthemostimportantitemsofprocessinformation.Whilepowerrequirementsaffectthedesignofapassscheduleforoptimaluseoftheavailablemillresources,rollforceismandatoryforpresettingthegeometricalactuators.Bothforceandtorque,ontheotherhand,needtobeknownformillpresettingsothatmechanicalorpracticallimitsarenotexceeded.Theapproachselectedtodescribetheeffectsintherollgapwithregardtopower,torqueandforce,isbasedonastripfibermodelusingthebasictheorydevelopedbyKarmanandSiebel.Therollgapmodelprovidesbothverticalandtangentialstresscomponentsactingontheworkroll.Therollseparatingforceresultsfromtheintegrationoftheverticalpressurecomponents.Torqueanddrivepowerarederivedfromthetangentialstress.Therollgapmodelsimultaneouslyprovidesaccurateinformationabouttheverticalandtangentialstresscomponentsactingontherolland,thus,thedrivepowerandrollforce.Theabilitytoevaluatetherollingprocess,basedonaccuratecalculationoftherollseparatingforceandmaindrivepower,enhances,inparticular,thematerialyieldstressevaluation.Thisisbeneficialsincetherollforcemeasurementisaffected,toalargeextent,bymeasurementhysteresispresentinaclosed20hmill.2、MaterialyieldstressadaptionMaterialyieldstressadaptionisrequiredinanycasewherethereistheneedtorollawiderangeofsteelgrades.Also,thedemandforselflearningmodelalgorithmsforcestheuseofadaptivemethodswithregardtotheyieldstress.Theyieldstressofthematerialisinitiallyevaluatedinofflinetestsusingtorsionbarsamples.Whileofflinetestsprovidegoodinitialinformation,eachprocessandproducthasitsownpersonality.Thismayresultfromtheannealingpracticesorvariationsinthechemicalcompositionofthesteelgrades.Theyieldstressadaptionisbrokendownintoashorttermadaptiontorapidlyadjusttheyieldstresscurve,andalongtermadaption,wherecomplexrelationshipsbetweenstrain,strainrateandtemperatureareevaluatedandrepresented.Statisticalyieldstressinformationisavailablebygradeandalsoonanindividualcoilbasisifneeded,whichimprovesqualityassurance.3、FrictionrepresentationBesidesobtainingarepresentationofthematerialyieldstress,itisalsomandatorytodescribethefrictionintherollgap.Inavarietyofapplications,thefrictioncoefficientisadjustedsothatduringlongtermanalysisthemostappropriatefrictioncoefficientie,,thecoefficientthatprovidesthebestmatchbetweencalculationandmeasurement,isapplied.Anotherapproachistocarryoutrollingtestsandanalyzetheresults.Whilerollingtestsaffectproduction,theanalysismethodistimeconsumingandmayoftenhavethedisadvantagethatnotallrelevantfactorsaffectingfrictionareadequatelyconsidered.Theapproachselectedinthecurrentstudyisbasedonanartificialneuralnetwork.Theentrylayeroftheneuralnetworkreceivesallrelevantinformationasithasbeengatheredandmayaffectfriction.Thisinformationisprocessedthroughthemultilayerperceptronfeedforwardnetworkinanofflineinvestigationusingthebackpropagationmethodfortrainingthat,finally,leadstothefrictioncoefficient.Witharepresentativework,evenphysicalrelationshipsbetweenthefrictioncoefficientandprocessinformationcanbeevaluated.Theresultsderivedfromtheneuralnetworkhavebeenusedasthebasisforananalyticalmodel,whichwasimplementedonline.Theaccuracyoftherepresentationhasbeenevaluatedinseveralonlinerollingtestsinindustrialfacilities.Sincemillspeedisoneofthemainvariablesaffectingfriction,onepasswasmadeduringthecommissioningphaseofthemodelwithdifferentmillspeeds.Boththemeasuredandcalculatedrollforcewererecorded.Apartfromthefrictioncoefficient,boththetemperatureofthestripapproachingtherollbiteandthestrainvariedinthetest.4、ElasticmillstandbehaviorInadditiontorollforce,powerandtorque,theelasticbehaviorofthemillstandmustalsobedescribedtoallowpropagationfromthemeasuredeccentricadjustmentstotherollbitecontour,whichisthetargetforfurtheroptimizationsteps.Onerequirementintheelasticmillstandmodelwasitsabilitytocoveravarietyofdifferentmillconfigurations,rollprofilesandrollmaterials.Thesevariableswere

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