>> P.430
ParallelismintablemotionBReferstoparallelism(indicatortravel)oftheslidetablemotionandflatsurface(tablemountingsurface).Fixtheindicatoratthecenteroftheslidetable,applythetestindicatoronthestoolonwhichtheprecisionpositioningtableismounted,makeameasurementacrossalmostwholeareaofthestrokelengthinXandYdirections,andtakethemaximumreadingdifferenceasameasurementvalue.StraightnessReferstoanextentofdeviationfromtheidealstraightlineoftheslidetablemotion,whichshouldbelinear.・Straightnessinhorizontal:Motionoftheslidetabletravel・Straightnessinvertical:axisinleftandright(horizontal)direction.Motionoftheslidetabletravelaxisinupanddown(vertical)direction.Thesearemeasuredbyatestbarandindicatororlaserrunningstraightnessmeasurementsystem.Themeasurementvalueisrepresentedbytheintervalbetweentwostraightlinesinparallelwitheachother,whenplacedsothattheintervalbecomesminimal.SquarenessofXYmotionReferstosquarenessofX-andY-axismotions.Fixasquarescaleontheslidetabletakingeithertravelaxisdirectionasareference,applythetestindicatorperpendiculartothereferencetravelaxisandtakethemaximumreadingdifferencewithinthestrokelengthoftheaxisasameasurementvalue.BacklashFeedtotheslidetableandtakereadingofthetestindicatorwhenitismovedslightlyasareference.Then,movetheslidetableinthesamedirectionwiththegivenloadfromsuchconditionwithoutthefeedgearandreleasetheload.Obtainthedifferencefromthereferencevalueatthispoint.Performthismeasurementatthecenterandeachendofthestrokelengthandtakethemaximumobtainedvalueasthemeasurementvalue.LostmotionPerformpositioningintheforwarddirectionforonepositionandmeasuretheposition(ℓ1inthefigure).Thengiveacommandtomoveitinthesamedirectionandgivethesamecommandinthebackwarddirectionfromthepositiontoperformpositioninginthebackwarddirection.Measuretheposition(ℓ1'inthefigure).Further,giveacommandtomoveitinthebackwarddirectionandgivethesamecommandintheforwarddirectionfromthepositiontoperformpositioningintheforwarddirection.Measuretheposition(ℓ2inthefigure).Subsequently,repeatthesemotionsandmeasurementsandobtainthedifferencebetweenaveragevaluesofstoppositionofthe7positioningsinforwardandbackwarddirections.Performthismeasurementatthecenterandeachendofthemotionandtakethemaximumobtainedvalueasthemeasurementvalue.⊿StraightnessSquareYXℓ1ℓ2ℓ3ℓ1′ℓ2′ℓ3′Measurementvalueoflostmotion=|17(R1+R2+…R7)-17(R1′+R2′+…+R7′)|maxⅢ14
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