>> P.199
Ⅱ-191❶FittingBGseriesisgenerallyusedwithaslightradialinternalclearancefit.RecommendedfitsareshowninTable2.Whenitisusedforaguidepostofthepressdiesetorhighoperationaccuracyisrequired,apreloadisgenerallygiven.ThetolerancesofdimensionsoftheshaftandhousingboreinthiscaseareshowninTable3.However,sinceexcessivepreloadshortensthelifeofStrokeRotaryCage,itissuggestedthatthelowerlimitofradialclearanceisnotsmallerthanthevalueshowninTable4.Table2GeneralfitToleranceclassShaftHousingholeh5,h6H6,H7Table3olerancesofdimensionsforshaftandhousingholeunit:μmShaftHousingholeNominaldimensionsmmh5NominaldimensionsmmK5HLHL190-925+1-8220-928+1-8250-931+2-9280-936+2-9320-1140+2-9380-1148+2-9Table4Lowerlimitofradialinternalclearanceunit:μmNominaldimensionsofshaftmmLowerlimitofradialinternalclearance19-522-525-528-732-738-7❷RacewayBGseriesisusedwithashaftandhousingholeasracewaysurfaces.RecommendedvaluesforsurfacehardnessandroughnessofmatingracewayareshowninTable5andtherecommendedvaluesfortheminimumeffectivehardeningdepthareshowninTable6.Whensomeoftheballsheldintheretainerescapethehousingracewayandoperateinlinearmotion,itisrecommendedthatthehousingracewayendsshouldbeslightlychamferedsothattheballsenterorexitsmoothly.Table5SurfacehardnessandroughnessofracewayItemRecommendedvalueRemarkSurfacehardness58～64HRCWhenthesurfacehardnessislow,multiplytheloadratingbyhardnessfactor(1).Surfaceroughness0.2μmRaorlower(0.8μmRyorlower)Whereaccuracystandardislow,around0.8μmRa(3.2μmRy)isalsoallowed.Note(1)Forhardnessfactor,refertoFig.3inpageⅢ-5.Table6Minimumeffectivehardeningdepthofracewayunit:mmNominaldimensionsofshaftandhousingholeRecommendedvalueforminimumeffectivehardeningdepthOverIncl.-280.828501.0PrecautionforUse
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