电子教案统一模板(数控)Unit.ppt

Unit5NCProgramming,5.1Lesson9BasicRequirementsofNCMachineControl,Tocontrolamachine,itisnecessarytobeginbydefiningthecoordinateofthetoolmotion.Itisnecessarytospecifywhetherthemotionisapositioningmotion(rapidtraverse)orafeedmotion(cutting).Thefeedmotionincludeslinearmotionandcircularmotion.Thesecontrolfunctionsanddatarequirementsaresummarizedinwhatfollows:Preparatoryfunctionsthewordsspecifywhichunit,whichinterpolator,absoluteorincrementalprogramming,whichcircularinterpolationplane,cuttercompensation,andsoon.,Coordinatesdefinethreedimensional(andthreerotational)axes.Machiningparametersspecifyfeedandspeed.Toolcontrolspecifiestooldiameter,nexttoolnumber,toolchange,andsoon.Cyclefunctionsspecifydrillcycle,reamcycle,borncycle,millcycle,andclearanceplane.Coolantcontrolspecifythecoolantcondition,thatis,coolanton/off,flood,andmist.Miscellaneouscontrolspecifiesallothercontrol,spindleon/off,spindlerotationdirection,palletchange,clampcontrol,andsoon.Interpolatorslinear,circularinterpolation,circlecenter,andsoon.,Thesecontrolfunctionsareprogrammedthroughprogramwords(codes).G-codeTheG-codeisalsocalledpreparatorycodeorword.ItisusedtopreparetheMCUforcontrolfunctions.Modalfunctionsarethosethatdonotchangeaftertheyhavebeenspecifiedonce,suchasunitselection.Non-modalfunctionsareactiveintheblockwheretheyarespecifiedF-codeTheF-codespecifiesthefeedspeedofthetoolmotion.Itistherelativespeedbetweenthecuttingtoolandthework-piece.Feedspeedcanbechangedfrequentlyinaprogram,asneeded.WhenanF-codeispresentinablock,ittakeseffectimmediately.,S-codeTheS-codeisthecuttingspeedcode.Cuttingspeedisthespecificationoftherelativesurfacespeedofthecuttingedgewithrespecttothework-piece.Itistheresultofthetoolrotation.Therefore,itisprogrammedinrpm.TheMachineAbilityDataHandbookgivesthesevaluesinsurfacefeetperminute(sfpm),andconversionisrequiredbeforeprogrammingisdone.1TheS-codeisspecifiedbeforethespindleisturnedon.TheS-codedoesnotturnonthespindle.ThespindleisturnedonbyanM-code.Tospecifya1000rpmspindlespeed,theprogramblockis：N0010S1000M03.,T-codeTheT-codeisusedtospecifythetoolnumber.Itisusedonlywhenanautomatictoolchangerispresent.Itspecifiestheslotnumberonthetoolmagazineinwhichthenexttoolislocated.ActualtoolchangedoesnotoccuruntilatoolchangeM-codeisspecified.R-codeTheR-codeisusedforcycleparameters.Whenadrillcycleisspecified,onemustgiveaclearanceheight.M-codeTheM-codeiscalledthemiscellaneouswordandisusedtocontrolmiscellaneousfunctionsofthemachine.Suchfunctionsincludeturnthespindleon/off,start/stopthemachine,turnon/offthecoolant,changethetool(Table5-1).,5.2Lesson10InterpolationCommandsofCNCLathes,Interpolationcommandsincludelinear,circularinterpolation,circlecenterinterpolation,andsoon.LinearinterpolationcommandsForCNClathes,linearinterpolationinvolvesmovingthetoolalongastraightlineprogrammedatthespecifiedfeedrate.1Linearinterpolationisusedtoexecutesuchoperationsasturning,facing,taperturning,andtaperboring.2Inthediscussiontofollowitisassumedthatthecenteroftoolnoseradiusisprogrammed.,GeneralsyntaxG01X1Z1FnX2Z2X3Z3XnZnInwhichG01Specifiesthelinearinterpolationmodes.X1andZ1specifytheabsolutecoordinatesofthecenterofthetoolnoseradiusattheendofthefirstlinecut,secondlinecut,thirdlinecut,andsoon.,Fnspecifiesthefeedrateofthetool.Ifnotprogrammed,thesystemwillusethelastfeedrateprogrammed.Ifnotspecifiedatthebeginningoftheprogram,thesystemwillissueanalarm.3CircularinterpolationcommandsCircularinterpolationforlatheoperationsinvolvescuttingacirculararcineitheraclockwiseoracounterclockwisedirection.Thecommandsaresimilartothoseusedinmilling.Assume,again,thatthecenterofthetoolnoseisprogrammed.GeneralsyntaxG02XnZnInKnFn,InwhichG02specifiescircularinterpolationintheclockwisedirection.XnandZnspecifytheXandZabsolutecoordinatesofthecenterofthetoolnoseradiusattheendofthearccut.InandKnspecifytheincrementalXandZdistanceswithordirectionfromthecenterofthetoolnoseradiusatthestartofthearctothecenterofthearc.4Fnspecifiesthefeedrateofthetool.Ifnotprogrammed,thesystemwillusethelastprogrammedfeedrate.,5.3ReadingMaterials9SetupProcedure,Thesetupoperationcanbeginafterthefixtures,tooling,programtape,setupsheets,andpartblankarriveattheCNCmachine.Usuallythesetuppersonstartsbysecuringthecuttingtoolsinthetoolholders.Thetoolingassembliesareloadedintothetoolmagazineaccordingtotheorderoutlinedinthesetupsheet.Thework-holdingdeviceisputinplaceonthemachinetable.,Thepartblankislocatedintothework-holdingdeviceasrequestedbytheprogrammer.AfterloadingtheprogramintotheMCU,thesetuppersonthenproceedstoenteranotherimportantpieceofinformationleftblankbytheprogrammer:thelocationofthepartoriginorpartXoYowithrespecttomachinehome.Themachinehomepositionormachinezeroisalocationsetoncebythemachinemanufacturer.TheCNCmachineishomedatthestartofthepartprogramsetup.Whenhomed,themachineretractsthespindletoitsmaximumheightabovethetable(machineZo)andmovesthetabletoapresetmachinezeroposition(machineXoYo).,Thepartoriginisthe（0，0，0）locationofthepartXYZcoordinatesystem.Inabsolutecoordinateprogrammingalltoolmovementsaretakenwithrespecttothisorigin.SeeFigure5-1foranillustrationofthesepositions.Thepointfromwhichdimensionsaretakenonthepartprintisusual1yconsideredthepartorigin.Thiscouldbethecenterofahole,theedgeofthepartoracertainpredetermineddistancefromtheedge.ThesetuppersonmustdeterminetheXYZlocationsofthepartoriginfrommachinehome.ThisisaccomplishedbyplacinganedgefinderorendmillwithknowndiameterinthespindleandusingtheMCUsjogbuttonstomoveor“tram”theedgefinderprobefrommachinehometothepartedgeorholecenter.SeeFigure5-2.,TherearetwomainmethodsofprogrammingthislocationintotheMCU.Thefirstiscalledthefixtureoffsetmethod.ThisinvolvesusingtheMCUkeypadtoentertheXYZvaluesdirectlyintotheMCUunit.TheMLUsfixtureoffsetstorageareaisopenedandthevaluesareplacedhere.Later,whenthepartprogramisrun,afixtureoffsetcodeintheprogramdirectstheMCUtousetheXYZvaluespreviouslyplacedinitsoffsetstoragearea.,5.4ReadingMaterials10DebuggingtheProgram,Thedebuggingprocessbeginsafterthepartprogramhasbeensuccessfullyloaded.First,thesetuppersonlocksthemachineandrunstheprogramusingonlytheoutputfromtheMCU.Thisisdonetocheckifthecontrollerrecognizesallthecodesintheprogram.Ifthistestissuccessful,theprogramcanberunwiththemachineZ-axislocked.Thiswillguardagainstanypossiblecollisionsbetweenthetoolandtheworkholdingorpartitself.Nextistheso-called“dry”runwiththepartremoved.,Duringthistestthesetuppersonslowsdowntherapidfeedsandspeedsuptheactualfeeds.Thesetestswillindicatewhethertheprogramrunsandifthereareanyextraordinarymoveswhichcouldcauseacollisionoftheworkand/orworkholdingwith