数控车床自动回转刀架英文文献以及翻译专业研究.docx

数控车床自动回转刀架英文文献以及翻译专业研究.docx

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数控车床自动回转刀架英文文献以及翻译专业研究

Booleanoperationsfor3DsimulationofCNCmachining

ofdrillingtools

DaniTost*,AnnaPuig,Lluı´sPe´rez-Vidal

SoftwareDepartment,PolytechnicalUniversityofCatalonia,SpainAccepted25April2003

Abstract

ThispaperaddressesthesimulationofdrillingtoolsCNCmachining.Itdescribesanovelapproachforthecomputationoftheboundaryrepresentationofthemachinedtools.MachiningconsistsofasequenceofBooleanoperationsofdifferencebetweenthetoolandthegrindingwheelsthroughtime.TheproposedmethodperformsthedynamicBooleanoperationsoncrosssectionsofthetoolanditreconstructsthe3Dmodelbytilingbetweenthecrosssections.Themethodisbasedonclassicalcomputationalgeometryalgorithmssuchasintersectiontests,hullcomputations,2DBooleanoperationsandsurfacetiling.Thisapproachisefficientanditprovidesusercontrolontheresolutionoftheoperations.AbstractThispaperaddressesthesimulationofdrillingtoolsCNCmachining.Itdescribesanovelapproachforthecomputationoftheboundaryrepresentationofthemachinedtools.MachiningconsistsofasequenceofBooleanoperationsofdifferencebetweenthetoolandthegrindingwheelsthroughtime.TheproposedmethodperformsthedynamicBooleanoperationsoncrosssectionsofthetoolanditreconstructsthe3Dmodelbytilingbetweenthecrosssections.Themethodisbasedonclassicalcomputationalgeometryalgorithmssuchasintersectiontests,hullcomputations,2DBooleanoperationsandsurfacetiling.Thisapproachisefficientanditprovidesusercontrolontheresolutionoftheoperations.

q2003ElsevierLtd.Allrightsreserved.

Keywords:

CNCsimulations;Boresmachining;Computationalgeometry;Booleanoperations;Surfacetiling

1.Introduction

MostoftheresearchonCNCinCADiscenteredontheautomaticcomputationoftoolpaths[5,13].Givenafinaltooldesign,theoptimaltrajectoriesofthetoolandthegrindingwheelsmustbecomputedyieldingasfinalresulttheCNCcode.Machiningsimulationandverificationhasexactlytheoppositegoal:

tocalculatethetoolstartingfromtheCNCcodeandfromageometricalmodelofthemachine,thewheelsandthetoolbeforemachining.Thissimulationhasthreemainapplications[6].First,itdetectseventualcollisionsbetweenthetooloranyofthegrindingwheelsandtherestofthemachine.Itisimportanttoavoidcollisionsbecauseseriousdamagestothemachinescanfollow.Next,simulationprovidesameansofvisuallyverifyingtheefficiencyofthetrajectories,whichmayresultinfasterandcheaperprocesses.Finally,thesimulationallowsuserstocheckifthesurfaceoftheresultingtooliseffectivelythedesiredone.Intheroutinepracticeofmachining,experiencedoperatorshaveenoughskillstoimaginethetoolfinalshapebyonlyreadingtheCNCcode.

However,theyaregenerallynotabletodosowithnewornon-standarddesigns.Therefore,theuseofasimulationsystemdecreasesconsiderablythetoolproductioncostbecauseitavoidsthetrialanderrorprocessontherealmachinewithcostlymaterialsthatisotherwisenecessary.

ThispaperaddressesaparticulartypeofCNCmachiningsimulation:

thegrindingofboresandcutters.ConventionalCADsystemsdonotprovideameansofrealizingthistypeofsimulationsandspecificapplicationsareneeded.Untilrecently,mostofthesimulationapplicationsdealtonlywiththemachiningof2Dcross-sectionsofthetoolsandtheywererestrictedtothemainflutingoperation[3].Threedimensionalapplicationsareratherrecent[4,23].Theyprovideamachiningsimulationforspecific5-axesmachinesandtheyarenotapplicabletogeneralmovements.Thispaperpresentsanovelapproachforthecomputationoftheexternalshapeofthetoolsthroughasequenceofcoordinatedmovementsofthetoolandthewheelsonmachinesofupto6-axes.Theproposedmethodreducesthe3Dproblemto2DdynamicBooleanoperationsfollowedbyasurfacetiling.The2Dsolutioninvolvesdifferenttechniquesofplanarcomputationalgeometry:

fromintersectionstohullcomputations.

Thepaperisstructuredasfollows.InSection2wereviewpreviousapproachesonmachiningsimulations.Section3describesbrieflythecontourconditionsofthesimulation.Finally,Section4describesthecomputationofBooleanoperationsandtheresultsoftheimplementationareshowninSection5.

2.Previouswork

MachiningcanbeconsideredadynamicBooleanoperationofdifferencebetweenthegrindingwheelandthetool.Itisdynamic,becauseboththetoolandthewheelsmovealongtimethroughrotationsandtranslations.

TheVectorCut[8,10],isprobablythemostreferencednumericalcontrolsimulationmethod.Itisanapproximatesolutionthatrepresentsthefrontierasasetofpointsandnormalvectorsthatwillbecutalongthepathofthegrindingwheel.Thism