《数控应用专业英语》课件第4章

4INTERPOLATIONFUNCTIONS4.1POSITIONING(G00)4.2LINEARINTERPOLATION(G01)4.3CIRCULARINTERPOLATION(G02,G03)4.4HELICALINTERPOLATION(G02,G03)4.5HYPOTHETICALAXISINTERPOLATION(G07)4.6THREADCUTTING(G33)4.1POSITIONING(G00)

TheG00commandmovesatooltothepositionintheworkpiecesystemspecifiedwithanabsoluteoranincrementalcommandatarapidtraverserate.

Intheabsolutecommand,coordinatevalueoftheendpointisprogrammed.

Intheincrementalcommand，thedistancethetoolmovesisprogrammed.FormatG00IP-;

IP-:foranabsolutecommand,thecoordinatesofanendposition,andforanincrementalcommand,thedistancethetoolmoves.Explanations

Eitherofthefollowingtoolpathscanbeselectedaccordingtobit1ofparameterLRPNo.1401.·Nonlinearinterpolationpositioning

Thetoolispositionedwiththerapidtraverserateforeachaxisseparately.Thetoolpathisnormallystraight.·Linearinterpolationpositioning

Thetoolpathisthesameasinlinearinterpolation(G01).Thetoolispositionedwithintheshortestpossibletimeataspeedthatisnotmorethantherapidtraverserateforeachaxis.

TherapidtraverserateinG00commandissettotheparameterNo.1420foreachaxisindependentlybythemachinetoolbuilder.InthepositioningmodeactuatedbyG00,thetoolisacceleratedtoapredeterminedspeedatthestartofablockandisdeceleratedattheendofablock.Executionproceedstothenextblockafterconfirmingtheinposition.Fig.4.1LinearandNonlinearinterpolationpositioning“Inposition”meansthatthefeedmotoriswithinthespecifiedrange.

Thisrangeisdeterminedbythemachinetoolbuilderbysettingtoparameter(No.1826).

Inpositioncheckforeachblockcanbedisabledbysettingbit5(NCI)ofparameterNo.1601accordingly.Limitations

TherapidtraverseratecannotbespecifiedintheaddressF.

Eveniflinearinterpolationpositioningisspecified,nonlinearinterpolationpositioningisusedinthefollowingcases.Therefore,becarefultoensurethatthetooldoesnotfoultheworkpiece.

G28specifyingpositioningbetweenthereferenceandintermediatepositions.4.2LINEARINTERPOLATION(G01)

Toolscanmovealongaline.FormatG01IP-F-;

F-:speedoftoolfeed(feedrate)

IP-:foranabsolutecommand,thecoordinatesofanendpoint,andforanincrementalcommand,thedistancethetoolmoves.Explanations

AtoolmovesalongalinetothespecifiedpositionatthefederatespecifiedinF.

ThefeedratespecifiedinFiseffectiveuntilanewvalueisspecified.Itneednotbespecifiedforeachblock.

ThefeedratecommandedbytheFcodeismeasuredalongthetoolpath.

IftheFcodeisnotcommanded,thefeedrateisregardedaszero.

Thefeedrateofeachaxisdirectionisasfollows:G01ααββγγζζFf;Feedrateofαaxisdirection:Fα=

×fFeedrateofβaxisdirection:Fβ=

×fFeedrateofγaxisdirection:Fγ=

×fFeedrateofζaxisdirection:Fζ=

×f

Thefeedrateoftherotaryaxisiscommandedintheunitofdeg/min(theunitisdecimalpointposition).

Whenthestraightlineaxisα(suchasX,Y,orZ)andtherotatingaxisβ(suchasA,B,orC)arelinearlyinterpolated,thefeedrateisthatinwhichthetangentialfeedrateintheαandβcartesiancoordinatesystemiscommandedbyF(mm/min).

βaxisfeedrateisobtained;atfirst,thetimerequiredfordistributioniscalculatedbyusingtheaboveformula,thentheβaxisfeedrateunitischangedtodeg/min.

Acalculationexampleisasfollows:

G91G01X20.0B40.0F300.0;

ThischangestheunitoftheCaxisfrom40.0degto40mmwithmetricinput.Thetimerequiredfordistributioniscalculatedasfollows:ThefeedratefortheCaxisis

Insimultaneous3or4axescontrol,thefeedrateiscalculatedthesamewayasin2axescontrol.Examples·LinearinterpolationFig.4.2(a)Linearinterpolation·FeedratefortherotationaxisFig.4.2(b)Feedratefortherotationaxis4.3CIRCULARINTERPOLATION(G02,G03)

Thecommandbelowwillmoveatoolalongacirculararc.Format

ArcintheXpYpplaneArcintheZpXpplaneArcintheYpZpplaneExplanations·Directionofthecircularinterpolation“Clockwise”(G02)and“Counterclockwise”(G03)ontheXpYpplane(ZpXpplaneorYpZpplane)aredefinedwhentheXpYpplaneisviewedinthepositivetonegativedirectionoftheZpaxis(YpaxisorXpaxis,respectively)intheCartesiancoordinatesystem.Seethefigurebelow.Fig.4.3(a)Feedratefortherotationaxis·Distancemovedonanarc

TheendpointofanarcisspecifiedbyaddressXp,YporZp,andisexpressedasanabsoluteorincrementalvalueaccordingtoG90orG91.

Fortheincrementalvalue,thedistanceoftheendpointwhichisviewedfromthestartpointofthearcisspecified.·Distancefromthestartpointtothecenterofarc

ThearccenterisspecifiedbyaddressesI,J,andKfortheXp,Yp,andZpaxes,respectively.ThenumericalvaluefollowingI,J,orK,however,isavectorcomponentinwhichthearccenterisseenfromthestartpoint,andisalwaysspecifiedasanincrementalvalueirrespectiveofG90andG91,asshownbelow.I,J,andKmustbesignedaccordingtothedirection.Fig.4.3(b)Distancefromthestartpointtothecenterofarc

I0,J0,andK0canbeomitted.WhenXp,Yp,andZpareomitted(theendpointisthesameasthestartpoint)andthecenterisspecifiedwithI,J,andK,a360°arc(circle)isspecified.G021;Commandforacircle.

Ifthedifferencebetweentheradiusatthestartpointandthatattheendpointexceedsthepermittedvalueinaparameter,anP/Salarmoccurs.·Arcradius

Thedistancebetweenanarcandthecenterofacirclethatcontainsthearccanbespecifiedusingtheradius,R,ofthecircleinsteadofI,J,andK.Inthiscase,onearcislessthan180°,andtheotherismorethan180°areconsidered.Whenanarcexceeding180°iscommanded,theradiusmustbespecifiedwithanegativevalue.IfXp,Yp,andZpareallomitted,iftheendpointislocatedatthesamepositionasthestartpointandwhenRisused,anarcof0°isprogrammedG02R;(Thecutterdoesnotmove.)Fig.4.3(c)Arcradius·Feedrate

ThefeedrateincircularinterpolationisequaltothefeedratespecifiedbytheFcode,andthefeedratealongthearc(thetangentialfeedrateofthearc)iscontrolledtobethespecifiedfeedrate.

Theerrorbetweenthespecifiedfeedrateandtheactualtoolfeedrateis±2%orless.However,thisfeedrateismeasuredalongthearcafterthecuttercompensationisapplied.Restrictions

IfI,J,K,andRaddressesarespecifiedsimultaneously,thearcspecifiedbyaddressRtakesprecedenceandtheotherareignored.

Ifanaxisnotcomprisingthespecifiedplaneiscommanded,analarmisdisplayed.

Forexample,ifaxisUisspecifiedasaparallelaxistoXaxiswhenplaneXYisspecified,anP/Salarm(No.028)isdisplayed.

Whenanarchavingacenterangleapproaching180°isspecified,thecalculatedcentercoordinatesmaycontainanerror.Insuchacase,specifythecenterofthearcwithI,J,andK.ExamplesFig.4.3(d)ProgrammingexamplesTheabovetoolpathcanbeprogrammedasfollows:·InabsoluteprogrammingG92X200.0Y40.0Z0;

G90G03X140.0Y100.0R60.0F300.;G02X120.0Y60.0R50.0;

ORG92X200.0Y40.0Z0;G90G03X140.0Y100.0I-60.0F300.;G02X120.0Y60.0I-50.0;·Inincrementalprogramming

G91G03X-60.0Y60.0R60.0F300.;G02X-20.0Y-40.0R50.0;

ORG91G03X-60.0Y60.0I-60.0F300.;G02X-20.0Y-40.0I-50.0;4.4HELICALINTERPOLATION(G02,G03)

Helicalinterpolationwhichmovedhelicallyisenabledbyspecifyinguptotwootheraxeswhichmovesynchronouslywiththecircularinterpolationbycircularcommands.Format

SynchronouslywitharcofXpYpplaneSynchronouslywitharcofZpXpplaneSynchronouslywitharcofYpZpplane

α,β:Anyoneaxiswherecircularinterpolationisnotapplied.

Uptotwootheraxescanbespecified.Explanations

Thecommandmethodistosimplyorsecondaryaddamovecommandaxiswhichisnotcircularinterpolationaxis.AnFcommandspecifiesafeedratealongacirculararc.Therefore,thefeedrateofthelinearaxisisasfollows:

Determinethefeedratesothelinearaxisfeedratedoesnotexceedanyofthevariouslimitvalues.Bit0(HFC)ofparameterNo.1404canbeusedtopreventthelinearaxisfeedratefromexceedingvariouslimitvalues.Fig.4.4HelicalinterpolationRestrictions

Cuttercompensationisappliedonlyforacirculararc.

Tooloffsetandtoollengthcompensationcannotbeusedinablockinwhichahelicalinterpolationiscommanded.4.5

HYPOTHETICALAXIS

INTERPOLATION(G07)

Inhelicalinterpolation,whenpulsesaredistributedwithoneofthecircularinterpolationaxessettoahypotheticalaxis,sineinterpolationisenabled.

Whenoneofthecircularinterpolationaxesissettoahypotheticalaxis,pulsedistributioncausesthespeedofmovementalongtheremainingaxistochangesinusoidally.Ifthemajoraxisforthreading(theaxisalongwhichthemachinetravelsthelongestdistance)issettoahypotheticalaxis,threadingwithafractionalleadisenabled.TheaxistobesetasthehypotheticalaxisisspecifiedwithG07.FormatG07_1;HypotheticalaxiscancelG07_0;Hypotheticalaxissetting

Where,-isanyoneoftheaddressesofthecontrolledaxes.Explanations·Sineinterpolation

The_axisisregardedasahypotheticalaxisfortheperiodoftimefromtheG07_0commanduntiltheG07_1commandappears.

SupposesineinterpolationisperformedforonecycleintheYZplane.

ThehypotheticalaxisisthentheXaxis.X2+Y2=r2(ristheradiusofanarc.)(listhedistancetraveledalongtheZaxisinonecycle.)Fig.4.5(a)Hypotheticalaxisinterpolation·Interlock,strokelimit,andexternaldeceleration

Interlock,strokelimit,andexternaldecelerationcanalsoapplytothehypotheticalaxis.·Handleinterrupt

Aninterruptcausedbythehandlealsoappliestothehypotheticalaxis.

Thismeansthatmovementforahandleinterruptisperformed.Limitations·Manualoperation

Thehypotheticalaxiscanbeusedonlyinautomaticoperation.·Movecommand

Specifyhypotheticalaxisinterpolationonlyintheincrementalmode.·Coordinaterotation

Hypotheticalaxisinterpolationdoesnotsupportcoordinaterotation.Examples·SineinterpolationFig.4.5(b)Sineinterpolation

N001G07X0;

N002G91G17G03X-20.2Y0.0I-10.0Z20.0F100;

N003G01X10.0;

N004G07X1;

FromtheN002toN003blocks,theXaxisissettoahypotheticalaxis.

TheN002blockspecifieshelicalcuttinginwhichtheZaxisisthelinearaxis.SincenomovementtakesplacealongtheXaxis,movementalongtheYaxisisperformedwhileperformingsineinterpolationalongtheZaxis.

IntheN003block,thereisnomovementalongtheXaxis,andsothemachinedwellsuntilinterpolationterminates.

·Changingthefeedratetoformasinecurve

(Sampleprogram)

G07Z0;TheZaxisissettoahypothetical

axis.

G02X0Z0I10.0F4.;ThefeedrateontheXaxis

changessinusoidally.

G07Z1;TheuseoftheZaxisasahypothetical

axisiscancelled.Fig.4.5(c)Changingthefeedratetoformasinecurve4.6THREADCUTTING(G33)

Straightthreadswithaconstantleadcanbecut.Thepositioncodermountedonthespindlereadsthespindlespeedinrealtime.Thereadspindlespeedisconvertedtothefeedrateperminutetofeedthetool.FormatFig.4.6ThreadcuttingExplanations

Ingeneral,threadcuttingisrepeatedalongthesametoolpathinroughcuttingthroughfinishcuttingforascrew.Sincethreadcuttingstartswhenthepositioncodermountedonthespindleoutputsa1turnsignal,threadingisstartedatafixedpointandthetoolpathontheworkpieceisunchangedforrepeatedthreadcutt