>> P.414
Ⅲ14ParallelismintablemotionBReferstoparallelism(indicatortravel)oftheslidetablemotionandflatsurface(tablemountingsurface).Fixtheindicatoratthecenteroftheslidetable,applythetestindicatoronthestoolonwhichtheprecisionpositioningtableismounted,makeameasurementacrossalmostwholeareaofthestrokelengthinXandYdirections,andtakethemaximumreadingdifferenceasameasurementvalue.StraightnessReferstoanextentofdeviationfromtheidealstraightlineoftheslidetablemotion,whichshouldbelinear.・Straightnessinhorizontal:otionoftheslidetabletravelaxisinleftandright(horizontal)direction.・Straightnessinvertical:otionoftheslidetabletravelaxisinupanddown(vertical)direction.Thesearemeasuredbyatestbarandindicatororlaserrunningstraightnessmeasurementsystem.Themeasurementvalueisrepresentedbytheintervalbetweentwostraightlinesinparallelwitheachother,whenplacedsothattheintervalbecomesminimal.SquarenessofXYmotionReferstosquarenessofX-andY-axismotions.Fixasquarescaleontheslidetabletakingeithertravelaxisdirectionasareference,applythetestindicatorperpendiculartothereferencetravelaxisandtakethemaximumreadingdifferencewithinthestrokelengthoftheaxisasameasurementvalue.BacklashFeedtotheslidetableandtakereadingofthetestindicatorwhenitismovedslightlyasareference.Then,movetheslidetableinthesamedirectionwiththegivenloadfromsuchconditionwithoutthefeedgearandreleasetheload.Obtainthedifferencefromthereferencevalueatthispoint.Performthismeasurementatthecenterandeachendofthestrokelengthandtakethemaximumobtainedvalueasthemeasurementvalue.LostmotionMeasurementvalueoflostmotion=|17(R1+R2+…R7)-17(R1′+R2′+…+R7′)|maxPerformpositioningintheforwarddirectionforonepositionandmeasuretheposition(ℓ1inthefigure).Thengiveacommandtomoveitinthesamedirectionandgivethesamecommandinthebackwarddirectionfromthepositiontoperformpositioninginthebackwarddirection.Measuretheposition(ℓ1'inthefigure).Further,giveacommandtomoveitinthebackwarddirectionandgivethesamecommandintheforwarddirectionfromthepositiontoperformpositioningintheforwarddirection.Measuretheposition(ℓ2inthefigure).Subsequently,repeatthesemotionsandmeasurementsandobtainthedifferencebetweenaveragevaluesofstoppositionofthe7positioningsinforwardandbackwarddirections.Performthismeasurementatthecenterandeachendofthemotionandtakethemaximumobtainedvalueasthemeasurementvalue.Straightness⊿SquareXYℓ1′ℓ2′ℓ3′ℓ1ℓ2ℓ3
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