>> P.23
ABCDEFGHIJKLMLifeadjustmentfactorforoperatingconditionsa3islifelimitedbyThisfactorhelpstakeintoaccounttheeffectsofoper-atingconditions,especiallylubricationonthebearing.thephenomenonofThebearingfatiguewhichoccurs,ingeneral,beneathsurfacessubjectedtorepeatedstresses.Undergoodlubrica-tionconditionswheretherollingelementandracewaysurfacesarecompletelyseparatedbyanoilfilmandsurfacedamagecanbedisregarded,a3issettobe1.However,whenconditionsoflubricationarenotgood,namely,whentheviscosityofthelubricatingoilisloworisespeciallylow,andsoon,a3<1isused.Onlubricationisespeciallygood,avalueofa3>1canbeused.Whenlubrica-tionisnotgoodanda3<1isused,thelifeadjustmentfactora2cannotgenerallyexceed1.theperipheralspeedoftheotherhand,whentherollingelementsthebasicWhenselectingabearingaccordingdynamicloadrating,itisrecommendedthatasuitablevalueforreliabilityfactora1ischosenforeachappli-thecation.Theselectionshouldbemadeusingto(C/P)orfhvaluesdeterminedbymachinetypeandbasedupontheactualconditionsoflubrication,tem-perature,mounting,etc.,whichhavealreadybeenexperiencedandobservedtypeofmachines.thesameinLimitingconditionsThesebearinglifeequationsareapplicableonlywhenthebearingismountedandlubricatednormallywith-outintrusionofforeignmaterialsandnotusedunderextremeoperatingconditions.Unlesstheseconditionsaresatisfied,thelifemaybeshortened.Forexample,itisnecessarytoseparatelyconsidertheeffectsofbearingmountingerrors,exces-sivedeformationofhousingandshaft,centrifugalforceactingonrollingelementsathigh-speedrevolu-tion,excessivepreload,especiallylargeradialinternalclearanceofradialbearings,etc.Whenthedynamicequivalentloadexceeds1/2ofthebasicdynamicloadrating,thelifeequationsmaynotbeapplicable.CorrectionofbasicdynamicfortemperatureandhardnessloadratingTemperaturefactortemperatureshigherTheoperatingtemperatureforeachbearingisdeter-minedaccordingtoitsmaterialandstructure.Ifspe-cialheattreatmentisperformed,bearingscanbeusedattheallowablecontactstressgraduallydecreaseswhenthebearingtemperatureexceeds150°C,thebasicdynamicloadratingisloweredandcanbeobtainedbythefollowingequation:than+150°C.AsC…………………………………… (7)Ct= fwhere,Ct: Basicdynamicloadratingtconsideringtemperaturerise, N : Temperaturefactor(SeeFig.4.)ftC: Basicdynamicloadrating,NTemperature°Cft1501.02000.90.950.850.82500.75Fig.4TemperaturefactorFurther,ifthebearingisusedathightemperature,i.e.120°Corabove,theamountofdimensionaldisplace-mentgetslarger.Sospecialheattreatmentisneces-sary.Ifneeded,pleasecontactIKO.HardnessfactorWhentheshaftorhousingisusedastheracewaysur-faceinsteadoftheinnerorouterring,thesurfacehardnessofthepartusedastheracewaysurfaceshouldbe58〜64HRC.Ifitislessthan58HRC,thebasicdynamicloadratingisloweredandcanbeobtainedbythefollowingequation:CH= fHC…………………………………… (8)where, CH: Basicdynamicloadratingconsideringhardness, N Hardnessfactor(SeeFig.5.) BasicdynamicloadratingN::fHCHardnessofracewaysurfaceHRC6050403020fH10.80.60.40.20.1Fig.5HardnessfactorA20
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