>> P.64
(5)Gentlyoverlaythefacesofthegaugeblockstobewrungtogether.Therearethreemethodstouse(a,bandcasshownbelow)accordingtothesizeofblocksbeingwrung:a.Wringingthickgaugeblocksb.Wringingathickgaugeblocktoathingaugeblockc.WringingthingaugeblocksApplyanopticalattothesurfaceofonethingaugeblocktocheckthewringingstate.Crossthegaugeblocksat90˚inthemiddleofthemeasuringfaces.Overlaponesideofathingaugeblockononesideofathickgaugeblock.Topreventthingaugeblocksfrombending,rstwringathingaugeblockontoathickgaugeblock.230153423015mm23mm14Rotatethegaugeblockswhileapplyingslightforcetothem.Youwillgetasenseofwringingbyslidingtheblocks.Slidethethingaugeblockwhilepressingtheentireoverlappedareatoalignthemeasuringfaceswitheachother.Then,wringtheotherthingaugeblockontotherstthingaugeblock.23mm14mm13769012376Alignthemeasuringfaceswitheachother.Finally,removethethickgaugeblockfromthestack.Selection,PreparationandAssemblyofaGaugeBlockStackSelectgaugeblockstobecombinedtomakeupthesizerequiredforthestack.(1)Takethefollowingthingsintoaccountwhenselectinggaugeblocks.a.Usetheminimumnumberofblockswheneverpossible.b.Selectthickgaugeblockswheneverpossible.c.Selectthesizefromtheonethathastheleastsignicantdigitrequired,andthenworkbackthroughthemoresignicantdigits.(2)Cleanthegaugeblockswithanappropriatecleaningagent.(3)Checkthemeasuringfacesforburrsbyusinganopticalatasfollows:Figure1Figure2a.Wipeeachmeasuringfaceclean.b.Gentlyplacetheopticalatonthegaugeblockmeasuringface.c.Lightlyslidetheopticalatuntilinterferencefringesappear.Judgment1:Ifnointerferencefringesappear,itisassumedthatthereisalargeburrorcontaminantonthemeasuringface.d.Lightlypresstheopticalattocheckthattheinterferencefringesdisappear.Judgment2:Iftheinterferencefringesdisappear,noburrexistsonthemeasuringface.Judgment3:Ifsomeinterferencefringesremainlocallywhiletheatisgentlymovedbackandforth,aburrexistsonthemeasuringface.Ifthefringesmovealongwiththeopticalat,thereisaburrontheopticalat.e.Toremoveburrs,followthedirectionsonpage01-33.(4)Applyaverysmallamountofoiltothemeasuringfaceandspreaditevenlyacrosstheface.(Wipethefaceuntiltheoillmisalmostremoved.)Grease,spindleoil,vaseline,etc.,arecommonlyused.ThermalStabilizationTimeThefollowinggureshowsthedegreeofdimensionalchangewhenhandlinga100mmsteelgaugeblockwithbarehands.IrregularinterferencefringesTimefingersarereleasedThegaugeblockisheldwithfivefingers.Thegaugeblockisheldwiththreefingers.23mm09673214030Lapseoftime(minutes)506070Wipetheexposedmeasuringface(s)andcontinuebuildingupthestack,inthesamemannerasabove,untilcomplete.01-3751020123456789Elongation(µm)QuickGuidetoPrecisionMeasuringInstrumentsGaugeBlocksDenitionoftheMeterThe17thGeneralConferenceofWeightsandMeasuresin1983decidedonanewdenitionofthemeterunitasthelengthofthepathtraveledbylightinavacuumduringatimeintervalof1/299792458ofasecond.Thegaugeblockisthepracticalrealizationofthisunitandassuchisusedwidelythroughoutindustry.
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