通过立式六轴控制并应用超声振动加工锐角转角外文文献翻译.docx

通过立式六轴控制并应用超声振动加工锐角转角外文文献翻译.docx

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通过立式六轴控制并应用超声振动加工锐角转角外文文献翻译

ManufactureofOverhangingSharpCornerbyMeansof6-AxisControlMachiningwiththeApplicationofUltrasonicVibrations

felicianoH.JAPITANA**,koichiMORISHIGE**,shugoYASUDA**andyoshimiTAKEUCHI

Thestudyproposesanewmachinemethodtocreatancreateanoverhangingsharpcorner.Sharpcornersonoverhangingsurfacesaredifficulttomachineinconventionalwayorevenin3to5-aixsEDMespeciallyifthesurfaceshavedifferentangles.Thisisduetothelimitationofthefeeddirectionandthestructureoftheelectrodewhereinitmustbesymmetricalwiththetargetshape.Inpresentresearch,wetrytomachinethesharpcornerwithoverhangingsurfacesusingthenewmachiningmethod.The6-axiscontrolmachiningisappliedtosetanon-rotationaltoolatanarbitrarypositionwitharbitrarypositionwitharbitraryattitudeagainsttheworkpiece.Duringcutting,theultrasonicvibrationisappliedonthecuttingedgeofthetool,whilethetooltravelsalongthefeeddirection.Asthecuttingisperformed,the6-axis（X,Y,Z,A,B）movesimultaneously,dependingonthetoolattitudeatacertaincuttingpoint.Formtheexperimentalresults,itisshownthatthe6-axiscontrolultrasonicvibrationcuttingiscapableofproducingasharpoverhangingsurface.

KeyWords:

6-axisControlledCutting,CAD/CAMSystem,BoreByteTool,OverhangingSharpCorner,UltrasonicVibrationCuttingTool

1.introduction

Theflexibilityofproductsmaybeextendedgreatlyiftherestrictioninmanufacturingprocesscanbeminimizedoreliminated.Ifrotationaltoolssuchasballendmillsorsquareendmillsareusedintheproductionofamouldwithanoverhangingsharpcorner（OHSC）,itseemsdifficulttoclearlyobtainthetargetshapewithsharpedgelines.Thisisduetotheresultofprocessingwiththerotationaltools,Whicharesymmetricalwiththerotation.Thearc-likeradiusremainsareproducedonadjoiningsurfaces,asshowninFig.1

Conventionally,mostofoverhangingorinclinedsurfacecanbemachinedbysettingtheworkpieceatacertainangleinthevise,swivellingtheuniversalvise,orbysettingthetoolheadtoacertainangleandfeedingthecuttingtoolhead,asshowninFig.2（a）.Inthisprocess,theoverhangingsurfacesandthesharpedgesatthebottomareproduced.However,ifthetargetisanOHSCconsistingoftwooverhangingsidesurfaces,andtheinclinationangleofsurfaceisnotuniform,theprocessingofthetargetshapeisdifficulttoachievesincethecuttingdirectionintheprocessisfixedandlimitedonlytolinearcutting.Thus,itneedsalotofjigsandfixturestoholdaworkpiece,topositioncorrectlywithrespecttoamachinetoolandtosupportitduringmachining.

Fig.16-axiscontrolmachiningusingrotationaltool

Fig.2methodofproducingsharpcornerwithoverhangingsurfaces

Theotherpossiblemethodtoproducesuchashapeismulti-axisElectricDischargeMachining（EDM）,asshowninFig.2（b）.However,evenusingthismethod,itisdifficultorimpossibletoproduceanOHSCwithdifferentangle.Itneeds6degreesoffreedomtofullyexecutethemachiningoftherequiredshape.

Inthepreviousresearches,ultrasonicvibration（USV）wasappliedinturningofductilematerialandmillingofglassfiber-reinforcedplastic.ThecuttingforcewithUSVisconsiderablyreduced.However,intheformerprocess,theworkpieceisrotatedormovestotowardsthecuttingtool,andinthelatter,machiningislimitedonlyto2or3axiscontrolone.Intheotherfieldofresearch,multi-axiscontrolmachinetoolisusedtocompleteamachininginonesetup,whichleadstotheproductionofworkpiecewithhighaccuracyandqualityandtothereductioninmachiningtime.

Inthisstudy,6-axiscontrolcuttingusinganon-rotationalcuttingtoolwiththeapplicationofultrasonicvibration（USV）isused,asshowninFig.2（c）.ItisappliedtoscrutinizethevalidityofthemethodinthefabricationofOHSC,TheC-axisrotatesthenon-rotationaltoolsimultaneouslytogetherwithX,Y,Z,AorBaxisduringmachining.ThemovementoftheaxesisbasedonthetoolattitudeandthecuttingpointgeneratedbyadevelopedCAMsoftware.TheCAMprogramgeneratesacollisionfreetoolpathtoassurethesafetyoftheprocess.The6-axiscontrolmachinetoolprovideseasilythemachiningcapabilityofOHSC,since6degreesoffreedommakethemachiningexecutefullytherequiredproductshape.Also,withtheapplicationofUSV,aborebytetoolisutilizded,consideringitssizeandstiffnessduringmachiningoperationsincethecuttingforceisgreatlyreduced.

2.Experimentalprocedure

TheexperimentsteupisshowninFig.3,whereintheworkpieceismountedonthetableofthe6-axiscontrolmachiningcenter.TheborebytetoolismountedintheUSVtoolusinganadaptor.TheUSVtoolisturnmountedonthemainspindleofthe6-axiscontrolmachiningcenter.

Multi-axiscontrolmachinetoolandborebytetool

The6-axiscontrolmachiningcenterusedinthestudyisshownin

Fig.4.Themachiningcenterprovidesmulti-axisCNCmachinetools.The6-axiscontrolmachinetoolhas3rotationalaxesA,BandC.ItisconstructedbyaddingtherotationalfunctionConthemainspindleofa6-axiscontrolmachiningcenterwhichhas2rotationalaxes,namely;A,whichisarotarytiltingtableandB,whichistherotaryindextable.TheminimumunitfortranslationmovementX,YandZis1

andthatofrotationaloneA,BandCis0.36arcsecond.InthecaseofcuttingofOHSC,Aaxisisusedfordeterminationofsidesurfaceandtheinclinationangleofsharpcorner,Baxisforworkpiecerotation,Caxisfordeterminationofcuttingtooldirection,XandYaxisforthedeterminationoffeeddirectionoffeeddirectionwhilethedepthofcutisdeterminedbyZaxis.Fig6showsthenon-rotationalcuttingtool（borebytetool）usedinthestudy.Itismadeoftungstencarbideusuallyusedherein6-axiscontrolcutting.Thetotallengthanddiameterofthetoolare70mmand6mmrespectively.

Ultrasonicvibrationtool

Fif.6isacommerciallyavailableUSVtool（SB-160:

TagaElectricCo）.usedinthestudy.TheUSVisappliedonthecuttingedgeofthetool.Inordertoperformanefficientandeffectivevibrationcutting,thevibrationdirectionmustbesetparalleltothecuttingdirection.Sincethevibrationdirectionisnotalwaysparallelwiththefeeddirection,thetoolattitudeoftheborebytetoolissubjectedtoarrangement.Asillustratedinfig.7（a）,thetoolaxisvextorTandthetooldirectionvectorDandmodifiedbyarrangingtherollingandtheinclinationanglerespectively.TheseareconvertedintomodifiedtoolaxisvectorTandmodifiedtooldirectionvectorD,asshowninfig.7（b）.Thetransformationofthetoolaxisvectorandthetooldirectionvectorarecarriedoutincutterlocation（CL）conversion.

CAD/CAMsystem

Theconfigurationof6-axisCAD/CAMsystemisshowninfig.8,where3D-CADdataofthetargetshapeisgenerated.Thetypeofborebytetoolmustbeselected,basedonthetargetshape.ThemainprocessorgeneratesthecollisionfreeCLdataonthebasesoftoolinformationandtoolorientationaswellas3D-CADdataofthetargetshape.

ThepostprocessorconvertsCLdatageneratedbythemainprocessorinto6-axiscontrolNCdatasuitableforthecoordinatesystemofthemachiningcenterwithreferencetothestructureinformationofthemachiningcenter,settinginformation,cuttingconditionandvibrationcondition.Inaddition,so-calledlinearizationoperationisdineinordertokeepthefeedratetothemachiningcenterstructureconstantandtominimizethetoolpathdeviation.Itleadstoassurethesmoothnessoftheproductsurfaceespeciallyindealingwithcurvesurfaces.

BeforeconvertingCLdataintoNCdata,CLdatamustbefirstlycheckedforcollisiontoassurethesafetyofthemachiningprocess.Ifthecollisionisdetectedinthisstage,themodificationofCLdataiscarriedout,usingthemainprocessor.

3.ManufactureofSharpCornerwithOverhangingSurface

3.1Determinationoftoolattitude

Inordertoexpressheentiretoolattitudefor9-axiscontrolultrasonicvibrationcutting,thetoolattitudeoftheborebytetool,asshowninFig.9,isappointedbythecoordinatesPforcuttingpoint,thetoolaxisvectorTandthetooldirectionvectorD.ThesePTDcoordinatesareconvertedtoNCdata,andareinturnusedinmachiningoperation.In6-axiscontrolcuttingwithapplicationofultrasonicvibration,themovementandtheattitudeofthetoolmustbedeterminedinconsiderationofthevibrationdirection.Sincethecuttingdirectionchangesrapidly,thetoolattitudechangesalottokeepthetoolangleconstanttothesurfaceshape.

3.2Generationoftoolpath

ThetoolpathgeneratingmethodforOHSCcanbedescribedasfollows;theOHSCiscomposedwithtworidgelines,asillustratedinFig.10.Theintersectinglineiscalledasabottomridgelineandthecrosssectionlineiscalledasasideridgeline.Finishingthesideridgelineaswellasthebottomridgelineisrequiredtomakeasharpcorner.

3.2.1Generationoftoolpathforsidesurface

Thesurfacethatmakesasideridgelineiscomposedwithleftandrightsurfacesrespectively.Inproducingasideridgelineofthesharpcorner,machiningofleftandrightsurfacesisnecessary.TheoutlineofthetoolpathgenerationmethodforsidesurfacesoftheOHSCisdescribedinFig.11.Thesidetobemachinedandthetoolfeeddirectionmustbeselectedatfirst,basedonthetypeofborebytetoolandthetargetshape.Theadjoiningsurfacesthatmakeasideridgeline,isexpressedwithparametersuandv.Thefixcurve,whichisequaltoparameterv,isgeneratedonthesidefromtheupperp