《PrecisionMeasurementTechnology》主講人：趙慧、楊國(guó)星TianjinLightIndustryVocationalTechnicalCollegeI

IIIIIIVVVIFundamentalsofCoordinateMeasurementApplication

DimensionalErrorDetectionShapeErrorDetection

DirectionalErrorDetection

PositionalErrorDetection

RunoutErrorDetectionVII

CurveandSurfaceDetectionVIII

ExtendedContentTaskIII:EstablishingtheBasicCoordinateSystemandSafetyPlane[TaskIntroduction][RelatedKnowledge]I.FundamentalsofCoordinateSystemGeometryCommonlyusedcoordinatesystemsinclude:theCartesiancoordinatesystem(planerectangularcoordinatesystem),thespatialCartesiancoordinatesystem(3DCartesiancoordinatesystem),thepolarcoordinatesystem,thecylindricalcoordinatesystem(alsoknownasthecylindricalcoordinatesystem),andthesphericalcoordinatesystem(alsoknownasthesphericalcoordinatesystem).Inthemeasurementprocess,thespatialCartesiancoordinatesystemandthecylindricalcoordinatesystemarecommonlyused.[RelatedKnowledge]II.IntroductiontoCommonCoordinateSystemsinCoordinateMeasuringMachines(1)MachineCoordinateSystemThemachinecoordinatesystemistheinherentcoordinatesystemofthemeasuringmachine.Eachcoordinatemeasuringmachinehasonlyonemachinecoordinatesystem.Itservesasthebasisformovementcommandsandmeasurementsofthecoordinatemeasuringmachine.However,forthemeasurementofconventionalworkpieces,themachinecoordinatesystemisinconvenienttouse.Typically,forameasurementprogram,theuserneedstodefineacoordinatesystemreferencedtotheworkpiece.(2)BaseWorkpieceCoordinateSystemThereisonlyonebaseworkpiececoordinatesystem,whichisusedforlocatingandaligningtheworkpiece.FortheCALYPSOsoftwareandthecoordinatemeasuringmachine,itdeterminesthepositionoftheworkpieceontheworktable.Byestablishingthebasecoordinatesystem,therelationshipbetweenthemachine'szeropointandtheworkpiece'soffsetiscreated,linkingthebaseworkpiececoordinatesystemtothemachinecoordinatesystem.Inameasurementprogram,allotherauxiliaryworkpiececoordinatesystemscanbetransformedintocalculationsrelativetothebaseworkpiececoordinatesystem.(3)AuxiliaryWorkpieceCoordinateSystemMultipleauxiliaryworkpiececoordinatesystemscanbeestablishedwithinameasurementprogram.Thesesystemsareusedforauxiliaryoutputcharacteristics,auxiliarypositioningofotherelements,andothercoordinatesystem-relatedoperations.[RelatedKnowledge]II.IntroductiontoCommonCoordinateSystemsinCoordinateMeasuringMachines(4)ElementCoordinateSystemTheelementcoordinatesystemisalocalcoordinatesystemintrinsictoasingleelement.Itsoriginandorientationaredeterminedbytheelementitself.Generally,theelementcoordinatesystemisnotfrequentlyused,exceptwheneditingtheelementstrategywherethe"startingangleofthepath"isrelativetotheelement'scoordinatesystem.(5)InitialPositioningCoordinateSystemWhenelementsusedtoestablishthebasiccoordinate,systemaredifficulttoprobemanuallyorarerelativelycomplex,aninitialpositioningcoordinatesystemcanbeestablishedafterthebasiccoordinatesystemiscreated.Thiscansimplifythequickpositioningoperationsoftheworkpiecebeforestartingtheautomaticmeasurementprogram.

[RelatedKnowledge]III.PrinciplesofCoordinateSystemEstablishment(1)Right-HandRuleAccordingtotheright-handrule,thethumbrepresentsthe+Xaxis,theindexfingerrepresentsthe+Yaxis,andthemiddlefingerrepresentsthe+Zaxis.ThesethreemutuallyperpendicularandorthogonalcoordinateaxesformaspatialCartesiancoordinatesystem.Theestablishmentofacoordinatesystemmustcomplywiththeright-handrule,asillustratedinFigure2-3-1.(2)ProcessofEstablishingaCoordinateSystemTheprocessofestablishingacoordinatesystemisgenerallyconsideredtobetheprocessofconstrainingthedegreesoffreedomofaworkpiece.Aworkpiecehassixdegreesoffreedominspace:threetranslationalandthreerotational.Byconstrainingthesedegreesoffreedom,thepositionoftheworkpiececanbedetermined,therebydefiningacoordinatesystem.[RelatedKnowledge]IV.MethodsforEstablishingaBasicCoordinateSystemForconventionalmachinedparts,abasiccoordinatesystemistypicallyestablishedusingaplane/plane/planereferenceorasingle-planewithtwo-holereferencemethod.Inthemoldindustry,thebasiccoordinatesystemisgenerallyestablishedusingthefour-surfacecenteringmethod.yxz(1)EstablishingaCoordinateSystemUsingthePlane/Plane/PlaneMethodAsshowninFigure2-3-2,thebasiccoordinatesystemisestablishedusingtheplane/plane/planemethod.Theleftdiagramrepresentsthedefaultmodelcoordinatesystem,whiletherightdiagramillustratesthebasiccoordinatesystemconstructedusingthismethod.Inthe"BasicCoordinateSystem"dialogbox,sequentiallyselectPlane1,Plane2,andPlane3elementsintheirrespectivepositions.Atthispoint,anewcoordinatesystem(displayedwiththinlines)willappearintheCADwindow,asshowninFigure2-3-5.Verifywhethertheorientationandpositionofthenewcoordinatesystemarecorrect.Clicktheconfirmbuttontofinalizetheestablishmentofthecoordinatesystem,asillustratedinFigure2-3-6.(2)EstablishingaBasicCoordinateSystemUsingPlane/Line/CircleMethod(2)EstablishingaBasicCoordinateSystemUsingPlane/Line/CircleMethod(3)EstablishingaBasicCoordinateSystemUsingthePlane/Circle/CircleMethod(3)EstablishingaBasicCoordinateSystemUsingthePlane/Circle/CircleMethodV.TranslationandRotationoftheCoordinateSystemInthe"BasicCoordinateSystem"dialoginterface,clickthe"CoordinateTransformation"buttontoopenthe"CoordinateTransformation"dialogbox.Therearethreetransformationmethods:translation,rotationbyangle,androtationbydistance.Thecoordinatesystemcanbetransformedbyclickingthecorrespondingicon,asshowninFigure2-3-15.

VI.PerformingManualOperationThroughthe"PerformManualOperation"featureinthebasiccoordinatesystem,alignmentbetweenthedigitalmodelandthephysicalmodelcanbeachieved.Inthe"BasicCoordinateSystem"interface,click"ManualOperation,"andthen,followingthesystemprompts,manuallycollecttheelementsusedtoestablishthebasiccoordinatesystembyoperatingthehandle.Notethatthecollectionpointsshouldbereasonablydistributed,andthenumberofpointsshouldexceedtheminimumrequiredfortheelements.Oncethecollectioniscompleted,themachinecaninitiallyperformorientationandpositioningoftheworkpiece.VII.CreatingaSafetyPlaneAsafetyplaneisaprotectivezonecomposedofsixfaces,surroundingtheworkpieceandrelatedfix