>> P.51
1N=0.102kgf=0.2248lbs.1mm=0.03937inchContacttypesealingmethodInthistypeofsealing,theshaftissealedbytheappli-cationofpressureresultingfromtheelasticityofthesealmaterialtothesealingsurfaceoftheshaft,whichrotates,reciprocatesoroscillates.Syntheticrubber,syntheticresinandfeltaregenerallyusedassealingmaterials.Table33PeripheralspeedandsurfaceroughnessofshaftPeripheralspeed m/sOver-510Incl.510-SurfaceroughnessμmRa(μmRy)0.8(3.2)0.4(1.6)0.2(0.8)2FeltsealBecauseoftheirsimplestructure,feltsealshavelongbeenusedtoprotectgreaselubricationfromdust.Sincefeltabsorbssomegreaseduringoperation,ithardlycausesheatgenerationandseizure,butitcan-notbeusedwhentheperipheralspeedoftheshaftishigh(morethan4m/s).Wherethereisahighcon-centrationofdirtanddust,theymaybecomeattachedtothecontactsurfaceoffelt,sometimesscratchingtheshaftsurface.Topreventthis,feltsealsareplacedapartfromeachother,orafeltsealisusedtogetherwithasyntheticrubberseal.twofluidlips.Table32showslubricationaremixed.1OilsealSyntheticrubberoilsealsarethemostgeneraltypeofsealingused.Thesealingeffectisobtainedwhentheelasticlipcomesintocontactwiththeshaft.Somelipsarespring-loadedtomaintainadequatepressingforce.Theslidingsurfacesofthelipandtheshaftalwaysshowfrictionalbehaviorsuchthattheboundarylubri-Ifthereisancationandinsufficientamountofoilbetweenthecontactsur-faces,itwillcauseheatgeneration,wearandseizure.Conversely,iftheoilfilmistoothick,itmaycauseoilleakage.inJISB2402-1~5.GeneraloilsealsarespecifiedIKOOilSealsforNeedleRollerBearings(SeepageL1.)havealowsectionalheighttomatchtheNeedleRollerBearings.Nitrilerubberisgenerallyusedasthematerialforoilsealtheiroperatingtemperatureranges.Thefinishedsurfaceoftheshaftwheretheseallipmakescontactmusthaveanappropriatesurfaceroughness,asshowninTable33,accordingtotheperipheralspeed.Itmustalsohaveaccuratecircular-ity,andtheshafteccentricityshouldbelessthan0.05mm.Toincreasewearresistance,thehardnessoftheslid-ingpartoftheshaftmustbemorethan40HRC.Thiscanbeachievedbyhard-chromeplatingorheattreat-ment.thematerialsandTable32SealmaterialsandoperatingtemperaturesSealmaterialOperatingtemperaturerange℃SyntheticrubberNitrilerubberAcrylicrubberSiliconrubberFluororubberTetrafluoethyleneresin-25〜+120-15〜+130-50〜+180-10〜+180-50〜+220A48ABCDEFGHIJKLM
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