外文翻译--在钻孔中偏心距对切削力的影响 英文版.pdf -- 10 元

EffectofmisalignmentonthecuttingforcesignatureindrillingA.AlHamdanMechanicalEngineeringDepartment,MutahUniversity,Mutah,Karak,JordanReceived27June2000accepted2January2002AbstractThispaperpresentsastudywhichinvestigatestheeffectofmisalignmentbetweentheaxesofrotationofdrillandtheworkpieceonthesteadystateanddynamicoftheaxialcuttingforceandtorque.Anovelmethodologyhasbeenproposedtomeasurethemisalignmentbetweentheaxesofrotationofthedrillandtheworkpiece.Thisusesalaserbasedsystemtomeasurethismisalignment,whereareferencebeamhasbeengeneratedbyalasertube,whichisheldinthechuckofthemachineusingaspecialenclosure.Thelaserbeamiscapturedbyaphotosensorcamerahavingavideocapturecard.Tostudytheeffectofthemisalignment,thestartingbushwasintentionallymisalignedbymovingthepressureheadoverthecarriageusingtheleadscrewofthecrossslide.KeywordsMetalcuttingDrillingDeepholemachiningImageprocessingMisalignmentCuttingforces1.IntroductionTherelativepositionandmotionbetweenthetoolandworkpiecemayaffectboththesteadystateanddynamiccuttingforcesdramatically.Thusitbecomesdifficulttodistinguishbetweenthecuttingsignatureduetothedynamicresponseofthecuttingprocessandthatduetothenoiseoriginatingfromanyinaccuracyinthepositionoftheworkpiecerelativetothecuttingtool.Surprisingly,therehasbeenlittleattentionpaidtothiseffectinpreviousstudies.Someofthescatterinthecuttingforcemeasurementsreportedintheliteraturemaybepartiallyexplainedbythementionedinaccuracy.Thisbecomesparticularlyimportantifanewmodelofchipformationhastobeverifiedbyexperiments.IndeepholedrillingBTA,therelativelocationofthetoolandtheworkpieceisdefinedbytherelativelocationoftheaxesofrotationofthetool,workpieceandstartingbushasshowninFig.1.Sakumaetal.1–3investigatedrunoutindeepholesdrilledunderdifferentmisalignmentconditions.TheauthorskeptchangingbetweengundrillsandBTAdrillswhenrunningexperimentswithdifferentsetups.Thustheworkhasnoclearreferencetoaparticulartypeoftoolortoolgeometry.Furthertothisnoinformationwasprovidedontherigidityoftheboringtheyusedintheexperiments.Intoolrotatingsystemsthemisalignmentofthepilotbushoratoolshanksupportmakesthepathofthetooldeviateandcausestheaxestodeviatefromastraightpath4.Beingaselfguidedmachiningprocess,thestraightnesserrorontheholeaxisisfurtheraffectedbytherigidityofthetool–work–machinesystem.ThestraightnessoftheholeaxesproducedbyBTAdrillingisusuallymeasuredastherunoutmeasurementsareinfluencedbythesettingerrorswhiledrilling,namelyoffsetandnonparallelismofaxesoftoolandworkpiece.Therefore,adifferentapproachisnecessarytostudytheerroronthestraightnessoftheaxis,eliminatingthesettingerrors5.Katsukietal.6studiedtheinfluenceoftheshapeofthecuttingedgeonaxialholedeviationindeepdrilling.Sofar,therehasbeennosystematicstudyoftheoveralleffectofmisalignmentontoolwearandtoolperformance,exceptforthestudyonitseffectonrunout3.Ingeneral,authorsattributeavarietyofundesirableeffectstomisalignmentbutmostlyasexperiencebasedguesswork.Commonproblemsincludethecuttingedgeflakingorchipping,leadingpadwear,poorsurfacefinish,straightnessandroundness.Also,literaturesourcescitethatmisalignmentrelatedproblemsmayandmaynotbeaccompaniedbyexcessivevibration7.Thesectiontofollowpresentstheexperimentalsetupandtheprocedureusedtomeasurethecuttingforcesindeepholemachining.Thisencompassestheelementsofthesetupsuchasthemachine,theworkpiecematerial,thecuttingtoolandthedynamometer.Thissectioncoversalsothemeasuringsetupanditscalibration.Thenextsectionpresentstheproposedmethodologyandthespeciallydesignedsetupformisalignmentassurance,whichisfollowedbythecalibrationJournalofMaterialsProcessingTechnology124200283–91Emailaddresshayajnehmutah.edu.joA.AlHamdan.ofthemisalignmentassurancesetup.Thisfollowedbythepresentationanddiscussionoftheexperimentalresults.Thelastsectionoutlinestheconclusionsofthisstudy.2.Cuttingforcesmeasurement2.1.Experimentalsetup1.Machine.Fig.1showsthedrillingmachineinstallationusedintheexperiments.Theinstallationconsistsofadriveunit,apressurehead,aboringbarandthedrillhead.Thestationaryworkpiecerotatingtoolworkingmethodwasusedintheexperiments.2.Dynamometer.A2componentpiezoelectricloadwasherModel9065wasusedtomeasurethecuttingforces.Thetransducerincorporatestwodisks,eachwitharingofquartzcrystalspreciselyorientedinthecircumferentialandaxialdirections.Theloadwasherwasintegratedintoadynamometertobeheldinthechuck.BasedonthestandardmountingasspecifiedbythesupplierKistler,theloadwasherwaspreloadedbytwoflangesto120kN.Atthispreload,therangefortheaxialforcemeasurementswasC020toþ20kNandtherangefortorquewasfromC0200toþ200Nm.Fig.1showstheschematicarrangementofcuttingforcemeasurementsetup.TheloadwasherwasconnectedtoachargeamplifierKistlermodel5004andinturntoadualchannelFFTspectrumanalyserBKAnalyserType2032.Thesetupwascalibratedstaticallyanddynamically.Thedynamiccalibrationofthedynamometer–workpiece–machine–toolsystemwascarriedouttoavoidmeasuringthevibrationofthetoolinsteadoftheforcefluctuationsanddeterminethefrequencyband,overwhichthedynamometercouldbeusedforreliablemeasurements.Also,thefrequencyresponsewasmeasuredtodeterminetherangeoffrequenciesofthecuttingforces,whichcouldbemeasuredaccuratelywithoutdistortion.TheloadwasherwithalliedchargepreamplifiersandtheFFTanalyserwascalibratedbyFig.1.Theschematicarrangementofthecuttingforcesexperimentalsetup.84A.AlHamdan/JournalofMaterialsProcessingTechnology124200283–91strikingthedynamometerwithKistlerhammerModel912.Toexaminethevalidityofthemeasurement,thecoherencefunctionwascalculatedforthethrustforceandthetorque.2.2.CuttingtoolBTASsystempartionedboringheadsof1in.diameterSandvikdesignwereused.AdetaileddiagraminFig.2showsthedrilldesignandthegeometry.Thecuttingedgeisdividedintothreesections.ThegeometryparametersofthedrillswerecontrolledaccordingtheAmericanNationalStandardB94.501975.Eachcuttingedgewasexaminedatmagnificationof20C2forvisualdefectssuchaschiporcracks.2.3.WorkpiecematerialStainlesssteelAISI303wasusedasworkpiecematerial.Thecomposition,theelementlimitsandthedeoxidisationpracticewerechosenaccordingtotherequirementsofANSI/ASMEB94.55M1985andwererequestedfromthesteeldealer.3.MisalignmentmeasurementsetupTheschematicarrangementoftheexperimentalsetuponthedeepholemachineisshowninFig.3.AphotographoftheexperimentalsetupisshowninFig.4.Alaserbasedmeasurementsystemwasdevelopedtomeasurethemisalignmentbetweentheaxesofrotationofspindlenoseandthatofthestartingbushofthedeepholemachine.Areferencelaserbeamwasgeneratedbyalasertube,whichwasheldinthechuckofthemachineusingaspecialenclosure.Thelaserbeamwascapturedbyaphotosensorcamerahavingavideocapturecard.Theoutputimagesweresenttoimageprocessingsoftwaretotrackthelaserbeampositionbyprocessingtheseimages.TheoutputfromtheimageprocessingsoftwareprovidedthepositionoftheFig.2.BTAStoolsofpartionedcuttingedgesSandvikdesign.A.AlHamdan/JournalofMaterialsProcessingTechnology124200283–9185centroidofthelaserbeamonthephotosensorinacertainpositionalongtheaxisofrotationofthemachine.Themisalignmentswerecalculatedbycomparingtheaveragecentroidofthecapturedimageswhenthephotosensorcameraandstartingbushaxescoincideandwhenthecameraandnosespindleaxiscoincide.Toalignthemachine,thiscentroidhadtobebroughttocoincidewiththezeroreferencepoint.Thezeroreferencepointwasestablishedontheaxisofthecylindricalcamerahousingwithinareasonabletolerance0.5mm.Aspecialaccessorywasdesignedtoholdthecameraindifferentpositionsalongtheaxisofrotationofthemachine.Tostudytheeffectofmisalignment,thestartingbushwasintentionallymisalignedbymovingthepressureheadoverthecarriageusingtheleadscrewofthecrossslide.Fig.5showsaphotographoftheprincipalelementsofthemisalignmentmeasurementsetupasfollows1.LaserLTT4Hadjustablealignmenttool,EmergingTechnologies,LaseraimToolDivision,LittleRock,AR,Fig.3.Theschematicarrangementofmisalignmentexperimentalsetup.Fig.4.Aphotographoftheexperimentalsetupformisalignmentmeasurement.Fig.5.Photographoftheprincipalelementsofmisalignmentsetup.86A.AlHamdan/JournalofMaterialsProcessingTechnology124200283–91