《數(shù)控應(yīng)用專業(yè)英語》課件第7章

7COORDINATESYSTEM

7.1MACHINECOORDINATESYSTEM7.2WORKPIECECOORDINATESYSTEM7.3LOCALCOORDINATESYSTEM7.4PLANESELECTION

ByteachingtheCNCadesiredtoolposition,thetoolcanbemovedtotheposition.Suchatoolpositionisrepresentedbycoordinatesinacoordinatesystem.Coordinatesarespecifiedusingprogramaxes.

Whenthreeprogramaxes,theXaxis,Yaxis,andZaxis,areused,coordinatesarespecifiedasfollows:X-Y-Z-.Thiscommandisreferredtoasadimensionword.Fig.7.0ToolPositionSpecifiedbyX40.0Y50.0Z25.0

Coordinatesarespecifiedinoneoffollowingthreecoordinatesystems:

(ⅰ)Machinecoordinatesystem.

(ⅱ)Workpiececoordinatesystem.

(ⅲ)Localcoordinatesystem.

Thenumberoftheaxesofacoordinatesystemvariesfromonemachinetoanother.So,inthisbook,adimensionwordisrepresentedasIP-.7.1MACHINECOORDINATESYSTEM

Thepointthatisspecifictoamachineandservesasthereferenceofthemachineisreferredtoasthemachinezeropoint.Amachinetoolbuildersetsamachinezeropointforeachmachine.

Acoordinatesystemwithamachinezeropointsetasitsoriginisreferredtoasamachinecoordinatesystem.

Amachinecoordinatesystemissetbyperformingmanualreferencepositionreturnafterpoweron.Amachinecoordinatesystem,onceset,remainsunchangeduntilthepoweristurnedoff.Format(G90)G53IP-;

IP-：absolutedimensionword.Explanations·Selectingamachinecoordinatesystem(G53)

Whenacommandisspecifiedthepositiononamachinecoordinatesystem,thetoolmovestothepositionbyrapidtraverse.G53,whichisusedtoselectamachinecoordinatesystem,isaoneshotGcode;thatis,itisvalidonlyintheblockinwhichitisspecifiedonamachinecoordinatesystem.Specifyanabsolutecommand(G90)forG53.Whenanincrementalcommand(G91)isspecified,theG53commandisignored.

Whenthetoolistobemovedtoamachinespecificpositionsuchasatoolchangeposition,programthemovementinamachinecoordinatesystembasedonG53.Restrictions·Cancelofthecompensationfunction

WhentheG53commandisspecified,cancelthecuttercompensation,toollengthoffset,andtooloffset.·G53specificationimmediatelyafterpoweron

SincethemachinecoordinatesystemmustbesetbeforetheG53commandisspecified,atleastonemanualreferencepositionreturnorautomaticreferencepositionreturnbytheG28commandmustbeperformedafterthepoweristurnedon.Thisisnotnecessarywhenanabsolutepositiondetectorisattached.Reference

Whenmanualreferencepositionreturnisperformedafterpoweron,amachinecoordinatesystemissetsothatthereferencepositionisatthecoordinatevaluesof(α,β)setusingparameterNo.1240.Fig.7.1Referenceposition7.2

WORKPIECECOORDINATESYSTEM

Acoordinatesystemusedformachiningaworkpieceisreferredtoasaworkpiececoordinatesystem.AworkpiececoordinatesystemistobesetwiththeCNCbeforehand(settingaworkpiececoordinatesystem).

Amachiningprogramsetsaworkpiececoordinatesystem(selectingaworkpiececoordinatesystem).Asetworkpiececoordinatesystemcanbechangedbyshiftingitsorigin(changingaworkpiececoordinatesystem).7.2.1SettingaWorkpieceCoordinateSystem

Aworkpiececoordinatesystemcanbesetusingoneofthreemethods:

(ⅰ)MethodusingG92.

AworkpiececoordinatesystemissetbyspecifyingavalueafterG92intheprogram.

(ⅱ)Automaticsetting.

Ifbit0ofparameterSPRNo.1201issetbeforehand,aworkpiececoordinatesystemisautomaticallysetwhenmanualreferencepositionreturnisperformed.

(ⅲ)InputusingtheCRT/MDIpanel.

SixworkpiececoordinatesystemscanbesetbeforehandusingtheCRT/MDIpanel.

Whenusinganabsolutecommand,establishtheworkpiececoordinatesysteminanyoftheaboveways.

Format·SettingaworkpiececoordinatesystembyG92(G90)G92IP-;Explanations

Aworkpiececoordinatesystemissetsothatapointonthetool,suchasthetooltip,isatspecifiedcoordinates.IfacoordinatesystemissetusingG92duringtoollengthoffset,acoordinatesysteminwhichthepositionbeforeoffsetmatchesthepositionspecifiedinG92isset.

CuttercompensationiscancelledtemporarilywithG92.ExamplesFig.7.2(a)SettingaWorkpieceCoordinateSystem7.2.2SelectingaWorkpieceCoordinateSystem

Theusercanchoosefromsetworkpiececoordinatesystemsasdescribedbelow.(Forinformationaboutthemethodsofsetting.)

(ⅰ)OnceaworkpiececoordinatesystemisselectedbyG92orautomaticworkpiececoordinatesystemsetting,absolutecommandsworkwiththeworkpiececoordinatesystem.

(ⅱ)ChoosingfromsixworkpiececoordinatesystemssetusingtheCRT/MDIpanel.

ByspecifyingaGcodefromG54toG59,oneoftheworkpiececoordinatesystems1to6canbeselected:

G54Workpiececoordinatesystem1

G55Workpiececoordinatesystem2

G56Workpiececoordinatesystem3

G57Workpiececoordinatesystem4

G58Workpiececoordinatesystem5

G59Workpiececoordinatesystem6

Workpiececoordinatesystem1to6areestablishedafterreferencepositionreturnafterthepoweristurnedon.Whenthepoweristurnedon,G54coordinatesystemisselected.ExamplesFig.7.2(b)SelectingaWorkpieceCoordinateSystem7.2.3ChangingWorkpieceCoordinateSystem

ThesixworkpiececoordinatesystemsspecifiedwithG54toG59canbechangedbychanginganexternalworkpiecezeropointoffsetvalueorworkpiecezeropointoffsetvalue.

Threemethodsareavailabletochangeanexternalworkpiecezeropointoffsetvalueorworkpiecezeropointoffsetvalue:Fig.7.2(c)Changinganexternalworkpiecezeropointoffsetvalueorworkpiecezeropointoffsetvalue

(ⅰ)InputtingfromtheCRT/MDIpanel.

(ⅱ)ProgrammingbyG10orG92.

(ⅲ)Usingtheexternaldatainputfunction.

AnexternalworkpiecezeropointoffsetvaluecanbechangedbyinputsignaltoCNC.Refertomachinetoolbuilder’smanualfordetails.Format·ChangingbyG10G10L2PpIP-;

p=0:externalworkpiecezeropointoffsetvalue.

p=1to6:workpiecezeropointoffsetvaluecorrespondtoworkpiececoordinatesystem1to6.

IP-:foranabsolutecommand(G90),workpiecezeropointoffsetforeachaxis.

Foranincrementalcommand(G91),valuetobeaddedtothesetworkpiecezeropointoffsetforeachaxis(theresultofadditionbecomesthenewworkpiecezeropointoffset).·ChangingbyG92G92IP-;Explanations·ChangingbyG10

WiththeG10command,eachworkpiececoordinatesystemcanbechangedseparately.·ChangingbyG92

ByspecifyingG92IP-;,aworkpiececoordinatesystem(selectedwithacodefromG54toG59)isshiftedtosetanewworkpiececoordinatesystemsothatthecurrenttoolpositionmatchesthespecifiedcoordinates(IP-).

Then,theamountofcoordinatesystemshiftisaddedtoalltheworkpiecezeropointoffsetvalues.Thismeansthatalltheworkpiececoordinatesystemsareshiftedbythesameamount.WARNING

WhenacoordinatesystemissetwithG92afteranexternalworkpiecezeropointoffsetvalueisset,thecoordinatesystemisnotaffectedbytheexternalworkpiecezeropointoffsetvalue.

WhenG92X100.0Z80.0;isspecified,forexample,thecoordinatesystemhavingitscurrenttoolreferencepositionatX=100.0andZ=80.0isset.ExamplesFig.7.2(d)ChangingthecoordinatesystemFig.7.2(e)Changingtheworkpiececoordinatesystem7.3LOCALCOORDINATESYSTEM

Whenaprogramiscreatedinaworkpiececoordinatesystem,achildworkpiececoordinatesystemcanbesetforeasierprogramming.Suchachildcoordinatesystemisreferredtoasalocalcoordinatesystem.Format

G52IP-;Settingthelocalcoordinatesystem

G52IP0;

Cancellingofthelocalcoordinatesystem

IP-:originofthelocalcoordinatesystem.Explanations

ByspecifyingG52IP-;,alocalcoordinatesystemcanbesetinalltheworkpiececoordinatesystems(G54toG59).TheoriginofeachlocalcoordinatesystemissetatthepositionspecifiedbyIP-intheworkpiececoordinatesystem.

Whenalocalcoordinatesystemisset,themovecommandsinabsolutemode(G90),whichissubsequentlycommanded,arethecoordinatevaluesinthelocalcoordinatesystem.ThelocalcoordinatesystemcanbechangedbyspecifyingtheG52commandwiththezeropointofanewlocalcoordinatesystemintheworkpiececoordinatesystem.

Tocancelthelocalcoordinatesystemandspecifythecoordinatevalueintheworkpiececoordinatesystem,matchthezeropointofthelocalcoordinatesystemwiththatoftheworkpiececoordinatesystem.Fig.7.3SettingthelocalcoordinatesystemWARNING

(ⅰ)Whenanaxisreturnstothereferencepointbythemanualreferencepointreturnfunction,thezeropointofthelocalcoordinatesystemoftheaxismatchesthatoftheworkcoordinatesystem.

Thesameistruewhenthefollowingcommandisissued:G52α0;

α:axiswhichreturnstothereferencepoint.

(ⅱ)Thelocalcoordinatesystemsettingdoesnotchangetheworkpieceandmachinecoordinatesystems.

(ⅲ)Whetherthelocalcoordinatesystemiscancelledatresetdependsontheparametersetting.

ThelocalcoordinatesystemiscanceledwheneitherCLR,bit6ofparameterNo.3402orRLC,bit3ofparameterNo.1202issetto1.

(ⅳ)IfcoordinatevaluesarenotspecifiedforallaxeswhensettingaworkpiececoordinatesystemwiththeG92command,thelocalcoordinatesystemsofaxesforwhichcoordinatevalueswerenotspecifiedarenotcancelled,butremainunchanged.

(ⅴ)G52cancelstheoffsettemporarilyincuttercompensation.

(ⅵ)CommandamovecommandimmediatelyaftertheG52blockintheabsolutemode.7.4PLANESELECTION

Selecttheplanesforcircularinterpolation,cuttercompensation,anddrillingbyGcode.

ThefollowingtablelistsGcodesandtheplanesselectedbythem.

Explanations

Xp,Yp,Zparedetermin