《数控应用专业英语》课件第8章

8COORDINATEVALUEANDDIMENSION

8.1ABSOLUTEANDINCREMENTAL

PROGRAMMING(G90,G91)8.2POLARCOORDINATECOMMAND(G15,G16)8.3INCH/METRICCONVERSION(G20,G21)8.4DECIMALPOINGPROGRAMMING8.1ABSOLUTEANDINCREMENTALPROGRAMMING(G90,G91)

Therearetwowaystocommandtravelsofthetool，theabsolutecommand,andtheincrementalcommand.Intheabsolutecommand,coordinatevalueoftheendpositionisprogrammed;intheincrementalcommand,movedistanceofthepositionitselfisprogrammed.G90andG91areusedtocommandabsoluteorincrementalcommand,respectively.Format

Absolutecommand:G90IP-;

Incrementalcommand:G91IP-;ExampleFig.8.1Absoluteandincrementalprogramming8.2POLARCOORDINATECOMMAND(G15,G16)

Theendpointcoordinatevaluecanbeinputinpolarcoordinates(radiusandangle).

Theplusdirectionoftheangleiscounterclockwiseoftheselectedplanefirstaxis+direction,andtheminusdirectionisclockwise.

Bothradiusandanglecanbecommandedineitherabsoluteorincrementalcommand(G90,G91).FormatG□□G○○G16;

Startingthepolarcoordinatecommand

(polarcoordinatemode)G○○_；G15;

Cancellingthepolarcoordinatecommand

(polarcoordinatemode)G16

PolarcoordinatecommandG15

PolarcoordinatecommandcancelG□□Planeselectionofthepolarcoordinatecommand(G17,G18orG19)Polarcoordinatecommand

G○○

G90specifiesthezeropointofthework

coordinatesystemastheoriginofthe

polarcoordinatesystem,fromwhicha

radiusismeasured

G91specifiesthecurrentpositionasthe

originofthepolarcoordinatesystem,

fromwhicharadiusismeasured

IP-:specifyingtheaddressesofaxesconstituting

theplaneselectedforthepolarcoordinate

system,andtheirvaluesFirstaxis:radius

ofpolarcoordinate;Secondaxis:radiusof

polarcoordinate.·Settingthezeropointoftheworkpiececoordinatesystemastheoriginofthepolarcoordinatesystem

Specifytheradius(thedistancebetweenthezeropointandthepoint)tobeprogrammedwithanabsolutecommand.Thezeropointoftheworkcoordinatesystemissetastheoriginofthepolarcoordinatesystem.

Whenalocalcoordinatesystem(G52)isused,theoriginofthelocalcoordinatesystembecomesthecenterofthepolarcoordinates.Fig.8.2(a)Settingtheoriginofthepolarcoordinatesystem

·Settingthecurrentpositionastheoriginofthepolar

coordinatesystem

Specifytheradius(thedistancebetweenthecurrentpositionandthepoint)tobeprogrammedwithanincrementalcommand.Thecurrentpositionissetastheoriginofthepolarcoordinatesystem.Fig.8.2(b)SettingthecurrentpositionastheoriginofthepolarcoordinatesystemBoltholecircleisshowninFig.8.2(c).Fig.8.2(c)Boltholecircle·Specifyinganglesandaradiuswithabsolutecommands

N1G17G90G16;

SpecifyingthepolarcoordinatecommandandselectingtheXYplane.

Settingthezeropointoftheworkcoordinatesystemastheoriginofthepolarcoordinatesystem.

N2G81X100.0Y30.0Z-20.0R-5.0F200.0;

Specifyingadistanceof100mmandanangleof30degrees.

N3Y150.0;

Specifyingadistanceof100mmandanangleof150degrees.

N4Y270.0;

Specifyingadistanceof100mmandanangleof270degrees.

N5G15G80;

Cancellingthepolarcoordinatecommand.·Specifyingangleswithincrementalcommandsandaradiuswithabsolutecommands

N1G17G90G16;

SpecifyingthepolarcoordinatecommandandselectingtheXYplane.

Settingthezeropointoftheworkcoordinatesystemastheoriginofthepolarcoordinatesystem.

N2G81X100.0Y30.0Z-20.0R-5.0F200.0;

Specifyingadistanceof100mmandanangleof30degrees.

N3G91Y120.0;

Specifyingadistanceof100mmandanangleof+120degrees.

N4Y120.0;

Specifyingadistanceof100mmandanangleof+120degrees.

N5G15G80;

Cancellingthepolarcoordinatecommand.Limitations·Specifyingaradiusinthepolarcoordinatemode

Inthepolarcoordinatemode,specifyaradiusforcircularinterpolationorhelicalcutting(G02,G03)withR.·Axesthatarenotconsideredpartofapolarcoordinatecommandinthepolarcoordinatemode

Axesspecifiedforthefollowingcommandsarenotconsideredpartofthepolarcoordinatecommand:-Dwell(G04)-Programmabledatainput(G10)-Settingthelocalcoordinatesystem(G52)-Convertingtheworkpiececoordinatesystem(G92)-Selectingthemachinecoordinatesystem(G53)-Storedstrokecheck(G22)-Coordinatesystemrotation(G68)-Scaling(G51)8.3INCH/METRICCONVERSION(G20,G21)

EitherinchormetricinputcanbeselectedbyGcode.Format

inchinput：G20;

mminput：G21;

ThisGcodemustbespecifiedinanindependentblockbeforesettingthecoordinatesystematthebeginningoftheprogram.AftertheGcodeforinch/metricconversionisspecified,theunitofinputdataisswitchedtotheleastinchormetricinputincrementofincrementsystemIS-BorIS-C.Theunitofdatainputfordegreesremainsunchanged.Theunitsystemsforthefollowingvaluesarechangedafterinch/metricconversion:

-FeedratecommandedbyFcode

-Positionalcommand

-Workzeropointoffsetvalue

-Toolcompensationvalue

-Unitofscaleformanualpulsegenerator

-Movementdistanceinincrementalfeed

-Someparameters

Whenthepoweristurnedon,theGcodeisthesameasthatheldbeforethepoweristurnedoff.WARNING

(ⅰ)G20andG21mustnotbeswitchedduringaprogram.

(ⅱ)Whenswitchinginchinput(G20)tometricinput(G21)andviceversa,thetoolcompensationvaluemustberesetaccordingtotheleastinputincrement.

However,whenbit0(OIM)ofparameter5006is1,toolcompensationvaluesareautomaticallyconvertedandneednotbereset.CAUTION

ForthefirstG28commandafterswitchinginchinputtometricinputorviceversa,operationfromtheintermediatepointisthesameasthatformanualreferencepositionreturn.Thetoolmovesfromtheintermediatepointinthedirectionforreferencepositionreturn,specifiedwithbit5(ZMI)ofparameterNo.1006.NOTE

(ⅰ)Whentheleastinputincrementandtheleastcommandincrementsystemsaredifferent,themaximumerrorishalfoftheleastcommandincrement.Thiserrorisnotaccumulated.

(ⅱ)Theinchandmetricinputcanalsobeswitchedusingsettings.8.4DECIMALPOINTPROGRAMMING

Numericalvaluescanbeenteredwithadecimalpoint.Adecimalpointcanbeusedwhenenteringadistance,time,orspeed.Decimalpointscanbespecifiedwiththefollowingaddresses:

X,Y,Z,U,V,W,A,B,C,I,J,K,Q,R,andF.Explanations

Therearetwotypesofdecimalpointnotation:calculatortypenotationandstandardnotation.Whencalculatortypedecimalnotationisused,avaluewithoutdecimalpointisconsideredtobespecifiedinmillimeter,inch,ordegree.Whenstandarddecimalnotationisused,suchavalueisconsideredtobespecifiedinleastinputincrements.SelecteithercalculatortypeorstandarddecimalnotationbyusingtheDPIbit(bit0ofparameter3401).Valuescanbespecifiedbothwithandwithoutdecimalpointinasingleprogram.ExampleWARNING

Inasingleblock,specifyaGcodebeforeenteringavalue.Thepositionofdecimalpointmaydependonthecommand.Examples·Example1

G20;Inputininches

X1.0G04;X1.0isconsideredtobeadistanceand

processedasX10000.Thiscommandis

equivalenttoG04X10000.Thetooldwells

for10seconds

G04X1.0;EquivalenttoG04