Prof.Dr.LiandongYuProf.Dr.WeishiLiHEFEIUNIVERSITYOFTECHNOLOGY

FUNDAMENTALSOFCOORDINATEMEASURINGTECHNOLOGYContentsChap.1EvolutionofDimensionalMeasurementChap.2FundamentalsofCMMsChap.3ProbeSystemsChap.4CMMSoftwareChap.5ErrorCompensation&ApplicationConsiderationsChap.6Non-CartesianCMMsDefinitionProbeisa

sensor

whichprovidestheconnectionbetween

thesurfaceofthemeasuredobject

andthe

lengthmeasuringsystem

ofthecoordinatemeasuringmachine.ProbeProbeSystemsTactileProbingSystemsOpticalProbingSystemsCMMProbeManufacturers&RenishawProbeSystemsProbingSystemSelectionTrendsProbeSystemsTactileProbingSystemsOpticalProbingSystemsCMMProbeManufacturers&RenishawProbeSystemsProbingSystemSelectionTrendsTactileProbingSystemsBasicPrincipleofProbingTactileProbingSystemDesign:ABriefIntroductionDirectionalResponseTipCompensationEffectiveProbingTechniquesTactileProbingSystemsBasicPrincipleofProbing

rm=rr+rp+bTactileProbingSystemsClassificationofTactileProbes

hardprobetouchtriggerprobemeasuringprobeTactileProbingSystemsClassificationofTactileProbes

hardprobetouchtriggerprobemeasuringprobeTactileProbingSystemsTouchTriggerProbeDesignAtouchtriggerprobingsystemhastohaveatleast:atouchingelement(e.g.tipball)atransmittingdevice(e.g.stylusshaft)aforcegeneratingelement(e.g.spring)asensor(e.g.electricswitch)anoutputTactileProbingSystemsTouchTriggerProbeDesignModularDesignProbeheadProbebodyStylusTactileProbingSystemsModernTouchTriggerProbesStrainGauges

Stylusforce:0.1to0.4NPiezoSensorsStylusforce:0.01NToosensitive…Repeatability<1.00μmRepeatabilityofTP200:0.40

μm~0.50

μmTactileProbingSystemsDouble-TouchTriggerProbesDetectworkpiececontactataverylowforce.Toavoidfalsetriggering,akinematicresistivemechanismisusedtoconfirmtriggering.Betweenthetwotriggering,thevaluesofthelengthmeasurementsystemsoftheCMMarelatched;bytriggeringofthekinematicmechanismtheyarefinallyrecorded.TactileProbingSystemsDirectional

ResponseThedistancetravelledbyaprobebetweentouchingasurfaceandthetriggereventisreferredtoaspre-travel.Thevaryingdirectionalsensitivitycanbecausedbythesuspensionofthestylus,asymmetricmomentofinertiaofstylus,arrangementofsensorsindifferentdirections,directiondependentsensitivityofsensors,set-upoftheaxes,directiondependentprobingforce,tipballformdeviationandthedirectiondependentdynamicbehaviouroftheprobingsystemincludingstylicombinations.Reference:A.Wozniak,M.Dobosz,MetrologicalfeasibilitiesofCMMtouchtriggerprobesI&II,34(2003):273-299.TactileProbingSystems

2DDirectionalResponse

LobingEffectTactileProbingSystemsCompareFLandFH

TactileProbingSystems3DDirectionalResponseTP6TP200TactileProbingSystemsTipCompensationCMMsgenerallygathertheirdatabytouchingtheworkpiecewithaprobeattachedthemachine'smeasuringaxis.

Sinceit'sthetip'scircumferencethattouchesthepart,theprobe'scenterandradiusaredeterminedbymeasuringaveryaccuratesphere.TactileProbingSystemsProbeCalibrationThepositionofthetipballcenterrelatedtothereferencepointoftheprobingsystemTheradiusofthetipballHomeWorkWhatkindofgaugesareneededtocalibrateastyluswithacylindertip?Why?Whatkindofgaugesareneededtocalibrateastyluswithadisctip?Why?TactileProbingSystemsEffectiveProbingTechniquesProbemeasurementsshouldbetakenperpendiculartotheworkpiecesurfacewheneverpossible.

Ideally,theusershouldtakehitswithin±30°ofperpendiculartoavoidskiddingtheprobetip.

TactileProbingSystemsEffectiveProbingTechniquesShankingisanothercauseofmeasurementerror.TactileprobingsystemsEffectiveProbingTechniquesGenerally,thelargerthetipdiameter,thedeeperthestyluscangobeforeittouchestheworkpiecefeature.

Thisiscalledthe

effectiveworkinglength

oftheprobe.Thelongertheprobetipextension,thelargerthepre-travelerrorandthemoreresidualerrorisleftafterprobequalification.ProbeSystemsTactileProbingSystemsOpticalProbingSystemsCMMProbeManufacturers&RenishawProbeSystemsProbingSystemSelectionTrendsOpticalProbingSystemsTimeofFlightTriangulationStructuredlightCCDCamerasOpticalProbingSystemsTimeofFlightThelaserrangefinderfindsthedistanceofasurfacebytimingtheround-triptimeofapulseoflight.Alaserisusedtoemitapulseoflightandtheamountoftimebeforethereflectedlightisseenbyadetectoristimed.

OpticalProbingSystemsLaserTriangulationThedistancebetweenthecameraandthelaseremitterisknown.Theangleofthelaseremittercornerisalsoknown.Theangleofthecameracornercanbedeterminedbylookingatthelocationofthelaserdotinthecamera’sfieldofview.OpticalProbingSystemsStructuredlightStructured-light3Dscannersprojecta1D/2Dpatternoflightontheworkpieceandlookatthedeformationofthepatternonthesubject.Anexampleofaonedimensionalpatternisaline.Thelineisprojectedontotheworkpiece.Acamera,offsetslightlyfromthepatternprojector,looksattheshapeofthelineandusesatechniquesimilartotriangulationtocalculatethedistanceofeverypointontheline.OpticalProbingSystemsStructuredlight1DpatternoflightOpticalProbingSystemsCCDCameras2DmeasurementHybridProbesProbeSystemsTactileprobingsystemsOpticalprobingsystemsCMMProbeManufacturers&RenishawProbeSystemsProbingSystemSelectionTrendsCMMProbeManufacturersRenishawdominantindependentsupplierOtherCMMmanufacturersZeissLeitz…RenishawProbeSystemsTouchTriggerProbesScanning/measuringProbesStyli&ExtensionBarsManualProbeHeadsMotorisedProbeHeadsFive-AxisProbeSystemsStylusChangerRacksProbeChangerRacksRenishawProbeSystemsTouchTriggerProbe

TP6/7TP20TP200

RenishawProbeSystemsOpticalTriggerProbesOTP6Mcanbeusedtomeasure

pliable

or

delicate

materialsasthesensingbeamcausesnodistortionofthesurface.

OperationgPrinciple:Co-axialopticaltriangulationAlaserbeamisprojectedonothecomponentsurfaceandatriggersignalsenttotheCMMcontrollerwhenthelaserspotreachesitsfocalpoint.RenishawProbeSystemsTactileScanningProbes

SP25MSP600SP80RenishawProbeSystemsStyli&ExtensionBarsRenishawProbeSystemsManualProbeSystems

MH8MIHPH1MH20RenishawProbeSystemsMotorisedProbeHead

PH10PHS1servohead

RenishawProbeSystemsFive-AxisProbeSystemsMeasurementpointsaretakenbymovingonlytheheadratherthantheCMMstructure.RenishawProbeSystemsBen