>> P.22
A19LifeofoscillatingbearingThelifeofanoscillatingbearingcanbeobtainedfromequation(5).LOC= ………………………………(5)where, LOC: Basicratinglifeofoscillatingbearing,106cycles 2θ: Oscillatingangle,deg.(SeeFig.3) P: Dynamicequivalentload,NTherefore,whentheoscillatingfrequencyn1min-1isgiven,thebasicratinglifeasrepresentedbytotaloscillatinghourscanbeobtainedbysubstitutingn1forninequation(2)onpageA17.When2θissmall,anoilfilmcannotbeformedeasilybetweenthecontactsurfacesoftheracewayandtherollingelements.Thismaycausefrettingcorrosion.Inthiscase,pleaseconsultIKO.2θFig.3OscillatingmotionCorrectedratinglifeWhenarollingbearingisusedinordinaryapplica-tions,thebasicratinglifecanbecalculatedbyequa-tions(1)and(2)mentionedpreviously.Thisbasicratinglifeappliestobearingswhichrequireareliabilityof90%,haveordinarybearingpropertiesbeingmadeofmaterialsofordinaryqualityforrollingbearings,andareusedunderordinaryoperatingcon-ditions.Insomeapplications,however,itisnecessarytoobtainaratinglifethatappliestobearingswhichrequirehighreliability,havespecialbearingpropertiesorareusedunderspecialoperatingconditions.Thecorrectedratinglifeforthesespecialcasescanbeobtainedfromthefollowingequationbyusingthebearinglifeadjustmentfactorsa1,a2anda3,respec-tively.Lna=a1a2a3L10…………………………… (6)where,Lna:Correctedratinglife,106rev. a1: Lifeadjustmentfactorforreliability a2: Lifeadjustmentfactorforspecialbearingproperties a3: Lifeadjustmentfactorforoperat-ingconditionsLifeadjustmentfactorforreliabilitya1Thereliabilityofrollingbearingsisdefinedasthepro-portionofbearingshavingalifeequaltoorgreaterthanacertainspecifiedvaluewhenagroupofidenti-calbearingsareoperatedunderidenticalconditions.Withrespecttoindividualbearings,itreferstotheprobabilityofthelifeofabearingbeingequaltoorgreaterthanacertainspecifiedvalue.Thecorrectedratinglifeforareliabilityof(100-n)%canbeobtainedusingequation(6).Table2showsthevaluesofthelifeadjustmentfactora1forvariousreliabilities.Table2Lifeadjustmentfactorforreliability a1909596979899L10L5L4L3L2L110.620.530.440.330.21Reliability%Lna1Lifeadjustmentfactorforspecialbearingpropertiesa2Thebearinglifeisextendedorshortenedaccordingtothequalityofthematerial,themanufacturingtechnol-ogyofthebearinganditsinternaldesign.Forthesespecialbearinglifeproperties,thelifeiscorrectedbythelifeadjustmentfactorforspecialbearingpropertiesa2.ThetableofdimensionsforIKOBearingsshowsthevaluesofthebasicdynamicloadratingwhicharedeterminedtakingintoconsiderationthefactthatbearinglifehasbeenextendedbyimprovedqualityofmaterialsandadvancesinmanufacturingtechnolo-gies.Therefore,thebearinglifeiscalculatedusingequation(6)usuallyassuminga2=1.CP()p90θ
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