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外文翻译--面向机床生命周期的发展 英文版.pdf

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外文翻译--面向机床生命周期的发展 英文版.pdf

LifecycleorienteddevelopmentofmachinetoolsB.Denkena1,A.Harms1,J.Jacobsen1,H.C.Möhring1,D.Lange2,H.Noske31UniversityofHannover,InstituteforProductionEngineeringandMachineTools,Germany2ArtisGmbH,Germany3IngenieurbüroDr.Noske,GermanyAbstractFortheinvestmentdecisionfornewproductionequipmentitbecomesmoreandmorecommontoguaranteethetotalamountoflifecyclecostsLCC.IntheresearchprojectLoeWe,fundedbytheGermanFederalMinistryofEducationandResearchBMBF,methodsaredevelopedtominimizelifecyclecostsinthedevelopment,operationandrecyclingphase.ExemplarilythedevelopmentofaninnovativeverticalturningmachinedemonstratesvariousstrategiestominimizeLCC.Exchangeabletechnologymodulesextendtheeconomiclifeandmonitoringofselectedmachinecomponentshelptoavoidunplannedservicestandstill.ALCCnavigatoroptimizesthebalanceofpurchasingandconsequentialcosts.KeywordsLifeCycle,Machine,Monitoring1INTRODUCTIONIntheautomotiveindustryageneraltendencytowardsalifecyclecostcalculationisobvious.Machinetoolmanufacturersareobligedtoforeseeandguaranteetheconsequentialcostsoftheirproductforapreviouslydefinedlifetime.Ifmoreserviceandmaintenanceisrequiredthanforecasted,theprofitofthemachinetoolproviderisreduced.Machineswithlessdowntimeandlongerserviceintervalsbecomemoreprofitable.Thereforeahighermachinetoolqualityandalongerandpredictablecomponentlifetimebecomemoreimportant.Consequently,automotiveindustryinvestorsdonottendtopreferthemachinetoolwiththelowestinvestmentcostsanymore.Themodifiedcalculationbasehasseveralconsequencesregardingthemachinetooldesign.Higherqualitycomponentscanbeapplied.Hydraulicsupply,normallyrequiredtodrivetheclampingsystemofthemainspindle,causeshighmaintenancecosts.AnapproachtoavoidthesecostsforanewmachinetoolseriesdevelopedwithintheresearchprojectLoeWe,whichisanacronymforlifecycleorientedmachinetool,istoabandonallhydrauliccomponents.Monitoringmechanicalpartsasforexampleballscrews,allowstoreplacethecomponentswhenitisnecessaryandnotatthecalculatedlifetime.Thisalsoenlargesserviceintervals.AnLCCnavigatorisbeingdevelopedwithintheproject.Thissoftwaretoolhelpstooptimizethechoiceofcomponentswithrespecttolowlifecyclecostsinthedesignstage.Italsocanbeusedinthedevelopmentofmachinetoolcomponentslikeclampingdevices.Asitofferstheopportunitytoclearlyidentifythemaincostfactorsincludinglifecyclecosts,itcanbederivedwhichcomponentsareworthtobemonitoredovertheirlifecycle.2CUSTOMERVS.MANUFACTURERDEMANDSEndusersofmachinetoolshavetoreactflexibleonchangingmarketdemandstoproducehighqualityproductsatagrowingvarietybutshrinkinglotsizes.Todaysmachinetoolsandproductionsystemshavealifetimeof10to15years.Theproductseriesthatarebeingmanufacturedontheseworkshopfacilitieshaveasignificantlowerlifetimeingeneral.Itmighthappenthatnewproductgenerationsthathavetobemanufacturedontheoldworkshopfacilitiesoverstraintheprocessfacilitiesoftheoldmachinetools.Toovercometheselimitations,companieswanttoinvestintoflexibleandreconfigurablemachinetoolsthatofferabroadvarietyofmachiningoperationsatminimumsetuptime.Theoperationofsuchmultifunctionalandflexiblemachinetoolsmightbeinefficientforfinancialaccountingpurposes,asmanysmallandmediummachinetooloperatingcompaniescannotpredicttheirfuturemanufacturingprocessesclearly.Thereforetheydonotknowiftheywouldeverneedoverqualifiedmachinetoolsfromtheiractualpointofview.Inconsequencetheaimoftheinvestmentplanningshouldbetoevaluatethemachinetoolstobeboughtregardingtheircapabilityandtheircosteffectiveness.Nexttothepureinvestmentcostsofaproductionfacility,moreandmorecompaniesalsoconsiderthetotallifecyclecostsastherecanbesignificantdifferencesregardingi.e.investmentcosts,maintenancecosts,energycostsandproductivity.Thisleadstodifferencesinthecostsperpieceofthemachinetoolstobecompared.Themachinetoolmanufacturerswanttoproducemachinesatlowmanufacturingcostswhilebeingabletoofferahighdiversityofmachinetooltypes.Furthermoretheywanttobemoreefficientindesignandproductionandwanttoreduceservicecostsandworkwithinthewarrantyperiodfigure1.Customerdemandslozenge4Productivity,quality,flexibilitylozenge4Processorientatedmachinetoolslozenge4Highavailabilityandreliabilitylozenge4Exploitationofthemachinesfullcapacitylozenge4CosttransparencyatpurchaseanduseCustomerorientationSalesconversationService/maintenanceMö/42622e©IFWMachinetoolmanufacturerdemandslozenge4Lowmanufacturingcostsatmax.diversitylozenge4Valueanalysisandcompliancewithcostslozenge4Moreefficiencyindesignandproductionlozenge4Reductionofservicecostsandworklozenge4TransparencyofcostsatdevelopmentFigure1Customerdemandsvs.manufacturerdemands693Asmoreandmorecompaniestendtobuymachinesonlywithguaranteedlifecyclecosts,themachinetoolmanufacturershavetoundertakethetaskofcreatingappropriateoffers.Acommondifficultywithlifecyclecostsoftechnicalequipmentistotransformtechnicalfeaturesandconditionsintoeconomicvalues.2.1ResultsofacustomersurveyInordertoevaluatetheneedsofmachinetoolusers,acustomersurveyamongseveralmachinetooluserswithdifferentcompanysizesandbrancheshasbeenaccomplished.Thenumberofmachinetoolsformetalcuttinginusevariedfrom5to1500.Twoimportantresultsfromthesurveyconcerningtheinvestmentdecisionandtheproductivityarepresentedhere.Forallcustomers,technologyandqualityhavethehighestpriorityforaninvestmentdecision.Ofminorimportancearelifecyclecostsandinvestmentcosts.Thesurveyrevealedthatonlysomeofthebiggercompaniestendtodecideontheirinvestmentsaccordingtoguaranteedlifecyclecosts.Asanexample,thedeveloperoftheTCOstandardTotalCostofOwnership,DaimlerChrysler,onlybuysmachinetoolsandproductionlinesaccordingtoaTCOcontractwherethetotallifecyclecostsareassuredbycontractfor10years1.Othercompanieswillfollowinthefuture.Regardingtheproductivity,theavailabilityandprocesssafetyofmachinetoolsareofhighestimportanceforthemachinetoolusers.Speedandaccelerationareofminorimportancefigure2.Ha/42623e©IFWunimportantratherunimportantminorimportantimportantveryimportantInvestmentdecisionProductivitySurveyfrom20040102030405060708090100ConditionsLifecyclecostsTechnologyServiceQualitySpeedAccelerationAvailabilityProcesssafetySetuptimeFigure2Resultsofacustomersurvey2.2CosttransparencywithlifecyclenavigatorDesigntoCostistheheadlineoverthemostdevelopmentsofmachinetoolstoday.Theresultofsuchadevelopmentprocessisapurchasepriceoptimisedmachinetool.ButisthisresulttheoptimumconcerningtheLifeCycleCostsofthemachinetoolandthereforethemoneybagofthecustomerIfanyLCCcalculationsofmachinetoolsaredonetodaytheyarerealisedafterthedevelopmentprocessofthemachine.HowwillthedesignofamachinetoolbemodifiedifaminimumoftheLifeCycleCostsisthebenchmarkofthedesignTargetoftheLoeWeresearchprojectwherealsocomponentsupplierslikeBergSpanntechnikGmbH,FranzKesslerGmbH,A.Mannesmann,ArtisGmbHandSiemensareinvolved,isthedevelopmentofaLCCoptimisedmachinetool.ThismainideaguidesthewholedevelopmentprocessofthemachinetoolsincethefirstreflectionoftheLoeWemachine.ItwasacceptedthatthepurchasecostsoftheLoeWemachineexceededthepurchasecostsofacomparableconventionalmachinetoolifonlytheLoeWemachinewillshowarigorousbetterLCCschedulecomparedtotheconventionalmachinetoolfigure3.Inthisresearchproject,anexistingsoftwaretool,theCostNavigatorwhicheffectsgoodresultsincommonDesigntoCostprojectsofmachinetoolsandothercapitalequipments2,isenhancedtotheLCCNavigator.©Dr.NosketLifecyclecosts€0AftersalescostsToolsServiceMaintenanceEnergyetc.10yearscommonmachinetoolLoeWemachinetoolInvestmentcosts5yearsLifecyclecosts€Figure3CostscheduleofLoeWemachinetoolvs.conventionalmachinetoolUsingtheLCCNavigatortheLifeCycleCostsofthemachinetool,includingmanufacturingandaftersalecosts,willbeextrapolatedduringthewholedevelopmentprocess.EachdecisionconcerningtheapplicationorthedesignofacomponentwillbemadeconsideringthecalculatedvaluesoftheLCCNavigatoralreadyintheearliestdesignphase.TheapplicationoftheLCCNavigatorwillbeexemplarilydemonstratedatthedesignoftheworkpiececlampingdeviceoftheLoeWeturninglathe.©Dr.Noske26,126,447,533,411,40,010,020,030,040,050,060,070,080,090,0100,0conventionalclampingdeviceLoeWeclampingdevicemaintenancecostswithin10yearsotheraftersalescostswithin10yearsinvestmentcostsFigure4LCCextrapolationoftheworkpiececlampingsystemofLoeWemachinetoolvs.conventionalmachine694PROCEEDINGSOFLCE2006Normallyahydraulicclampingdeviceisusedfortheworkpiececlampingfunctioninaturninglathe.ConsideringtheclampingfunctionfromthepointofviewofLCC,acompletenewsolutionfortheclampingoftheworkpiecehasbeenrealizedwithintheLoeWeproject.Themaincostcomponentsofahydraulicclampingdevicewithin10yearsaremaintenancecostsespeciallyforthehydraulicsupplyunitfigure4.Thismaintenancecostsriseevenabovethepurchasecostsofthewholeclampingdeviceduring10yearsofoperation.ThenewelectricalclampingdeviceoftheLoeWeturninglatheisfreeofmaintenanceandgeneratesthereforenomaintenancecostsduringitslifetime.RegardingonlythepurchasecoststheconventionalclampingdevicehasanadvantagecomparedtotheLoeWedevicebecauseoflowerpurchasecosts.ThebenefitforthecustomerbecomesapparentonlyaftertheextrapolationoftheentireLCC.OthercomponentsoftheLoeWemachinetoolareLCCoptimizede.g.theballscrews,thelinearbearingunitsandcomponentsofthecontrolunitbasedonLCCNavigatorcalculations.ItcanbesummarisedthatanLCCoptimizedmachinetooldesignDesigntoLCCcreatesasignificantlydifferentmachinecomparedtoadesignundertheaspectsofonlypurchasingcosts.3MODULARMACHINETOOLTheinvolvedmachinetoolmanufacturerGildemeisterfocusesonamodularconceptforthemachinetoolseriesthatallowstheusageofasmanystandardpartsaspossible.Themachinetoolserieswillbeavailableinseveralstagesofextensioni.e.thenumberofmainspindles,theirmaximumtorquesandrotationalspeeds,differentturretsandtoolingsystems,whereasthemachinebasisremainsthesameforalltypes.Amodeloftheverticallathewiththeintegratedfeaturesforreducingthelifecyclecostsispresentedinfigure5.Eventhoughthemachinetoolprototypeisdevelopedinamodulardesign,itisdifficulttoensureawidelyreconfigurablemachinetool.Ithastobedistinguishedbetweenareconfigurationtobeperformedbythemachinetoolmanufacturerandareconfigurationthatcanberealizedbythemachinetooloperator.MainspindlewithintegratedBaxisBallscrewwithwearmonitoringElectricclampingdeviceMachine/processmonitoringInterchangeabletechnologymodulesRFIDtechnologyforquicksetupLCCNavigator€Ha/42627e©IFWXAxisYAxisZAxisZAxisZAxisFigure5Modelofthelifecycleorientedmachinetool3.1ReconfigurationbymachinetoolmanufacturerTheverticallathewillbeavailableinseveralstagesofextension.ThebasicversionisequippedwithastandardspindlewithoutBaxis.ToreconfigurethismachinetooltoonewithBaxis,extensivechangeswouldbenecessary,thatcanberatherpracticableonlyforthemachinetoolmanufacturer.Thusthecrossslideforthexandzaxiswouldhavetobechanged.Thiswouldalsoimplyachangeoftheinnerenclosureofthemachinetool.Componentsthatremainthesameforallthemachinetypesarethemachinebed,thebedsaucer,theouterenclosure,theelectricalcontrolunitbox,thecoolingunitandtheoperatorpanel.3.2ReconfigurationbymachinetooloperatorTheLoeWemachinetoolincorporatesaplatformthatallowsthemachinetoolusertousespecializedtechnologymodulesinthemachinefigure5.Thisplatformincorporatesastandardizeddockingsystemthatallowsthereferencedpositioningandclampingofthesemodulesinsidethemachinetool.Bythistheoperatorcanusehismachinetooleasilyformanufacturingprocessesthatwouldnothavebeenpossiblewithinthestandardmachinetoolconfiguration.Theutilizationofaplatformtobeequippedwithpalletsystemsinsidetheworkspaceofthemachinetoolallowstheuseofagreatvarietyofadditionalmanufacturingprocessesthatcanbeeasilyinstalledbytheoperator.Thiscanbei.e.largediameterdrilling,grindingetc.Palletbasedtechnologymodules,likeforexamplegrindingspindles,havetobeequippedwithasupplyofenergyandcompressedairaswellaswithanappropriateelectricalconnectionformonitoringsensorsignals.Asolutionfortheintegrationoftheseconnectionsintothemechanicalinterfaceiscurrentlyinvestigated.4COMBININGINFORMATIONANDCOMPONENTRelevantcomponentsoftheLoeWemachinetoolprototypewillbeequippedwithdatastoragedevicesthatallowthestorageofspecificcomponentdataforidentificationpurposeslikemanufacturer,type,serialnumberaswellaslifecyclerelatedmaintenanceinformation.Fourselectedcomponentsliketheballscrewdrive,theelectricclampingdevice,thetechnologymodulesandthemainspindleareequippedwithRFIDbasedtransponderchips.TheelectricclampingsystemisequippedwithaRFIDchipthatstoresallrelevantinformationforanautomatedconfigurationofthemachinetoolcontrol.FurthermoretheintegratedRFIDchipwillbeusedtostorelifecyclerelateddata.Thisallowstoidentifythecomponentanditsactualstateevenifitisdetachedfromthemachinetool.Toreadthetransponderchip,anantennahastobeplacedclosetotheRFIDchipasdataandenergyaretransmittedviaaradiofrequencyfield.Dependingontherequireddatarate,differentsystemsoperatingatvarioustransmissionfrequenciesandrangescanbeused.Inordertoassureanacceptabletransmissionrangethatcanbeupto7mmforaRFIDchipwith2kBmemorycapacity,itneedstobeinsulatedfromthemetalsurfacegrounditismountedon.MachinetoolcomponentsthatwillbeoftenexchangedasforexampleapalettebasedclampingsystemareequippedwithahardwiredantennaintegratedintothestationarypartandanRFIDchipintegratedintotheexchangeablepart.OtherRFIDchipequippedmachinetoolcomponentslikeaballscrewdrivethathavetobeinstalledonlyonceortwiceduringthemachinetoollifecyclewillbeidentifiedwithahandheldantennaconnectedtothemachinetoolcontrolforinstallationandmaintenancepurposesfigure6.13thCIRPINTERNATIONALCONFERENCEONLIFECYCLEENGINEERING695MachinetoolcontrolwithcentraldatastorageRFIDbasedcomponentmemoryDemountedcomponentwithRFIDchipS.Vogeler©ITAFigure6Combininginformationandcomponent5COMPONENTMONITORING5.1EstimationofremaininglifetimeofballscrewsOftenthemachinetoolutilizationtimeexceedstheballscrewlifetime.Whenthereisnoextraordinaryincidence,theyareexchangedafteracertaincumulatedtraversepathregardlessoftheirwearstate.Thisisthestateofthearttominimizetheriskofunplannedfailure.Whenaballscrewfailsduetoitswear,theaxisbecomeslesspreciseinparticular,theclearancebecomesmuchhigher.Thereforeitisnotpossibletochoosehardlongtermstablecontrolparameter.Dirtorchipsontheballscrewcanleadtoabreakdownoranenlargedwearoftheballsortheballtrackbeforereachingthenominallifetime.Thisalsodemandsanunplannedexchangeduetotheexceedingofworkpiecetolerances.Especiallyinautomaticlineoperations,adowntimeofseveralhoursorevendayscausessubstantiallosses.Thereforeareliablemonitoringstrategyofballscrewsisimportanttoavoidtheseadditionalcostsforthemachinetooluser.Aweardetectionandpredictionoftheremaininglifetimeallowstoplantheexchangeoftheballscrewinadvancetoavoidunplanneddowntime.LossofpreloadAutomaticwearmeasurementsshouldbedoneatthemostloadedlocationofthespindle.Becausesomespaceisrequiredforthemeasurementtraversepath,thetestcannotbeexecutedatthemarginsofthespindle.Experiencesfromballscrewmanufacturersshowthatwearofballscrewtrailsalsoreproduceswearontheballs.Therefore,analternativewearmeasurementatanotherpositionofthemachinetoolaxisrepresentsthemeanwearofthescrew.Inthefollowing,twopossiblemethodsofwearmeasurementarepresented.Botharebasedonpreloadlossdetection,duetoareducedballdiameterbypittingeffects.TheybaseoninvestigationsofhorizontallyarrangedballscrewswithinaprojectfundedbyDFGGermanResearchFoundation3.Anaimoftheinvestigationsistouseaslesssensorsaspossible.Thebestwouldbetouseonlycontrolintegratedsignalssuchaslinearandrotaryencoderandnominaltorque.NaturalfrequencyThenaturalfrequencyofanaxisisinfluencedbytheslidemass,thestiffnessofthepartoftheballscrewparticipatingintheforcefluxandthestiffnessofthenut.Thereforethenaturalfrequencydependsontheslidepositionandonthewearoftheballsrespectivelytheirdecreaseofdiameter.Figure7showsthepreloaddependantfrequencyresponses.Alossofpreloadleadstoalowereigenfrequencyofthespringmasslikeballscrewsystemasshownbythesmoothedlineinthegreyplaneinthediagram.Theanalysisofverticalaxeswithinmachinesismorecomplicatedbecauseseveralmodalfrequenciessuperposetheballscrewfrequency.Areliableextractionoftheweardependentfrequencymightbedifficult.50100150200Hz3001001000N200500Ja/43321©IFWFrequencyresponseFrequencyPreloadFigure7Eigenfrequencyvs.preloadNonlinearspringcharacteristicofballscrewsAnunwornballscrewhasanearlylinearspringcharacteristic.Thedeflectioncanbemeasuredcomparingthelinearandtherotatoryencoder,compensatingthepositiondependingballscrewstiffness.Whentheballsareworn,thescrewgetsaclearanceastransmissioncharacteristic.Thisisindicatedbylessstiffnessintherangeoflowforces.TheformerlinearspringcharacteristicbecomesshapedlikeanS.Thefirstdiagramoffigure8presentsthedependenceofmeasuredspringcurvesvs.preloadofahorizontallymountedballscrew.32101kN300,51,0kN2,0604020020µm60modelleddeflectionpreloadinfeedforce32101kN300,51,0kN2,0604020020µm60measureddeflectionpreloadinfeedforceIm/38813©IFWFigure8MeasuredandmodelledspringcharacteristicTheMorganMercerFlodingrowthmodelformulapossessesasimilarshapelikeanonlineardifferential696PROCEEDINGSOFLCE2006

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