>> P.42
∆δ=α∆tE…………………………………(29)where, ∆δ: Reductionofradialclearance, mmα Coefficientoflinearexpansionforbearingsteel: ≒12.5×10-61/ : Temperaturedifferencebetween°C∆ttheouterringandtheinnerringplusrollingelementsconsideredasoneunit, ° C Borediameterofouterring,mm E:Thetemperaturedifference∆tisconsideredtobe5〜10°Cundernormaloperatingconditionsand15〜 20°Cathighrotationalspeeds.Therefore,whenthetemperaturedifferenceisgreat,acorrespondinglylargerradialinternalclearancemustbeselected.FitPurposeoffitfitistoprovideToachievethebestperformanceofneedlerollerbearings,itisimportantthatthebearingringsarecor-rectlyfittedontotheshaftandintothehousing.theappropriateThepurposeofamountofinterferencerequiredbetweentheinnerringandtheshaftorbetweentheouterringandthehousing,topreventharmfulmutualslippage.Iftheinterferenceisinsufficient,itwillcauseaharmfulrelativedisplacement,knownascreep,betweenthefittedsurfacesinthecircumferentialdirection.Thismayintru-sionofwearparticlesintothebearing,generationofabnormalheat,vibration,etc.Therefore,asuitablefitmustbeselected.toabnormalwearoffittedsurfaces,leadTable20NatureofradialloadandfitNatureoftheloadRotatingconditionsInnerringOuterringFitInnerring:RotatingOuterring:StationaryLoaddirection:FixedInnerring:StationaryOuterring:RotatingLoaddirection:RotatingwithouterringInnerring:StationaryOuterring:RotatingLoaddirection:FixedInnerring:RotatingOuterring:StationaryLoaddirection:RotatingwithinnerringInterferencefitClearancefitClearancefitInterferencefitInnerring:RotatingorstationaryOuterring:RotatingorstationaryLoaddirection:NotfixedInterferencefitInterferencefitloaddirectionTheisnotfixed,includingcaseswheretheloaddirectionisfluctuat-ingorisanunbal-ancedload.thereRotatingloadoninnerringStationaryloadonouterringRotatingloadonouterringStationaryloadoninnerringDirectionallyindeterminateladA39
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