>> P.210
QuickGuidetoPrecisionMeasuringInstrumentsMicrometerHeadsMountedonmeasuringinstrumentsandprecisioninstruments,micrometerheadsareusedforvariouspurposesincludingmeasurement,feedingandpositioning.Recentdevelopmentsintechnologyhaveseenthemicrometerheadwidelyutilizedinprecisefeedingdevicesandcross-travelstagesonlaserinstrumentsandmanipulators,inadditiontotheusualdutiesonmeasurementjigs.Inparallelwiththeapplicationexpansion,thecustomer’sneedshaveincreased.Tomeetcustomerdemands,Mitutoyoprovidesstandardmicrometerheadswithdifferentmeasuringranges,stemtypeandbodysize.Furthermore,high-performancetypesofDigimaticMicrometerHead,0.1mmspindle-pitchmodels(standard0.5mm),etc.,arenowavailableforthenewapplications.Mitutoyoalsoprovidescustomizationservicesforspecialapplications.Micrometerheadswithcustomizedspindletipsandprecisionleadscrewsmanufacturedtocustomerspecicationcanbeoffered,eveninone-offquantities.KeyFactorsinSelectionKeyfactorsinselectingamicrometerheadarethemeasuringrange,spindleface,stem,graduations,thimblediameter.StemPlainstemStemlocknuttypeNon-rotatingSpindle•Anon-rotatingspindletypeheaddoesnotexertatwistingactiononaworkpiece,whichmaybeanimportantfactorinsomeapplications.•Thestemusedtomountamicrometerheadisclassiedasa"plaintype"or"clampnuttype"asillustratedabove.ThestemdiameterismanufacturedtoanominalMetricorImperialsizewithanh6tolerance.•Theclampnutstemallowsfastandsecureclampingofthemicrometerhead.Theplainstemhastheadvantageofwiderapplicationandslightpositionaladjustmentintheaxialdirectiononnalinstallation,althoughitdoesrequiresasplit-xtureclampingarrangementoradhesivexing.•General-purposemountingxturesareavailableasoptionalaccessories.MeasuringFaceFlatfaceSphericalfaceAnti-rotationdevice•Aatmeasuringfaceisoftenspeciedwhereamicrometerheadisusedinmeasurementapplications.•Whenamicrometerheadisusedasafeeddevice,asphericalfacecanminimizeerrorsduetomisalignment(FigureA).Alternatively,aatfaceonthespindlecanbearagainstasphere,suchasacarbideball(FigureB).•Anon-rotatingspindletypemicrometerheadoronettedwithananti-rotationdeviceonthespindle(FigureC)canbeusedifatwistingactionontheworkpiecemustbeavoided.•Ifamicrometerheadisusedasastop,thenaatfaceonboththespindleandthefaceitcontactsprovidesdurability.SpindleThreadPitch•Thestandardtypeheadhas0.5mmpitch.•1mm-pitchtype:quickertosetthanstandardtypeandavoidsthepossibilityofa0.5mmreadingerror.Excellentload-bearingcharacteristicsduetolargerscrewthread.•0.25mmor0.1mm-pitchtypeThistypeisthebestforne-feedorne-positioningapplications.Constant-forceDevice•Amicrometerheadttedwithaconstant-forcedevice(ratchetorfrictionthimble)isrecommendedformeasurementapplications.•Ifusingamicrometerheadasastop,orwheresavingspaceisapriority,aheadwithoutaratchetisprobablythebestchoice.Micrometerheadwithconstant-forcedeviceMicrometerheadwithoutconstant-forcedevice(noratchet)SpindleLock•Ifamicrometerheadisusedasastop,itisdesirabletouseaheadttedwithaspindlelocksothatthesettingwillnotchangeevenunderrepeatedshockloading.FigureCFigureAFigureB03-47
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