《数控应用专业英语》课件第5章

5FEEDFUNCTIONS

5.1GENERAL5.2RAPIDTRAVERSE5.3CUTTINGFEED5.4DWELL(G04)5.1GENERAL

Thefeedfunctionscontrolthefeedrateofthetool.Thefollowingtwofeedfunctionsareavailable:rapidtraverseandcuttingfeed.·Feedfunctions

(ⅰ)Rapidtraverse.

Whenthepositioningcommand(G00)isspecified,thetoolmovesatarapidtraversefeedratesetintheCNC.

(ⅱ)Cuttingfeed.

Thetoolmovesataprogrammedcuttingfeedrate.

·Override

Overridecanbeappliedtoarapidtraverserateorcuttingfeedrateusingtheswitchonthemachineoperator’spanel.·Automaticacceleration/deceleration

Topreventamechanicalshock,acceleration/decelerationisautomaticallyappliedwhenthetoolstartsandendsitsmovement(Fig.5.1(a)).Fig.5.1(a)Automaticacceleration/deceleration(example)·Toolpathinacuttingfeed

Ifthedirectionofmovementchangesbetweenspecifiedblocksduringcuttingfeed,aroundedcornerpathmayresult(Fig.5.1(b)).Fig.5.1(b)ExampleoftoolpathbetweentwoblocksIncircularinterpolation,aradialerroroccurs(Fig.5.1(c)).Fig.5.1(c)Exampleofradialerrorincircularinterpolation

TheroundedcornerpathshowninFig.5.1(b)andtheerrorshowninFig.5.1(c)dependonthefeedrate.So,thefeedrateneedstobecontrolledforthetooltomoveasprogrammed.5.2RAPIDTRAVERSEFormatG00IP-;

G00:Gcode(group01)forpositioning(rapidtraverse);

IP-:dimensionwordfortheendpoint.Explanations

Thepositioningcommand(G00)positionsthetoolbyrapidtraverse.Inrapidtraverse,thenextblockisexecutedafterthespecifiedfeedratebecomes0andtheservomotorreachesacertainrangesetbythemachinetoolbuilder(inpositioncheck).

ArapidtraverserateissetforeachaxisbyparameterNo.1420,sonorapidtraversefeedrateneedbeprogrammed.

Thefollowingoverridescanbeappliedtoarapidtraverseratewiththeswitchonthemachineoperator’spanel:

F0,25,50,100%

F0:allowsafixedfeedratetobesetforeachaxisbyparameterNo.1421.

Fordetailedinformation,refertotheappropriatemanualofthemachinetoolbuilder.5.3CUTTINGFEED

Feedrateoflinearinterpolation(G01),circularinterpolation(G02,G03),etc.arecommandedwithnumbersaftertheFcode.

Incuttingfeed,thenextblockisexecutedsothatthefeedratechangefromthepreviousblockisminimized.Fourmodesofspecificationareavailable:

(ⅰ)Feedperminute(G94).

AfterF,specifytheamountoffeedofthetoolperminute.

(ⅱ)Feedperrevolution(G95).

AfterF,specifytheamountoffeedofthetoolperspindlerevolution.

(ⅲ)Inversetimefeed(G93).

Specifytheinversetime(FRN)afterF.

(ⅳ)F1digitfeed.

SpecifyadesiredonedigitnumberafterF.Then,thefeedratesetwiththeCNCforthatnumberisset.Format

Feedperminute

G94;Gcode(group05)forfeedperminute

F-;

Feedratecommand(mm/minorinch/min)

Feedperrevolution

G95;

Gcode(group05)forfeedperrevolution

F-;

Feedratecommand(mm/revorinch/rev)

F1

digitfeed

FN;

N:

Numberfrom1to9

Inversetimefeed(G93)

G93;

Inversetimefeedcommand

Gcode(05group)

F-;

Feedratecommand(1/min)Explanations·Tangentialspeedconstantcontrol

Cuttingfeediscontrolledsothatthetangentialfeedrateisalwayssetataspecifiedfeedrate.Fig.5.3(a)Tangentialfeedrate(F)·Feedperminute(G94)

AfterspecifyingG94(inthefeedperminutemode),theamountoffeedofthetoolperminuteistobedirectlyspecifiedbysettinganumberafterF.G94isamodalcode.OnceaG94isspecified,itisvaliduntilG95(feedperrevolution)isspecified.Atpoweron,thefeedperminutemodeisset.

Anoverridefrom0%to254%(in1%steps)canbeappliedtofeedperminutewiththeswitchonthemachineoperator’spanel.Fordetailedinformation,seetheappropriatemanualofthemachinetoolbuilder.Fig.5.3(b)FeedperminuteWARNING

Nooverridecanbeusedforsomecommandssuchasforthreading.

·Feedperrevolution(G95)

AfterspecifyingG95(inthefeedperrevolutionmode),theamountoffeedofthetoolperspindlerevolutionistobedirectlyspecifiedbysettinganumberafterF.G95isamodalcode.OnceaG95isspecified,itisvaliduntilG94(feedperminute)isspecified.

Anoverridefrom0%to254%(in1%steps)canbeappliedtofeedperrevolutionwiththeswitchonthemachineoperator’spanel.Fordetailedinformation,seetheappropriatemanualofthemachinetoolbuilder.Fig.5.3(c)FeedperrevolutionCAUTION

Whenthespeedofthespindleislow,feedratefluctuationmayoccur.Theslowerthespindlerotates,themorefrequentlyfeedratefluctuationoccurs.5.4DWELL(G04)FormatDwellG04X-;orG04P-;

X-:specifyatime(decimalpointpermitted)；

P-:specifyatime(decimalpointnotpermitted).Explanations

Byspecifyingadwell,theexecutionofthenextblockisdelayedbythespecifiedtime.Inaddition,adwellcanbespecifiedtomakeanexactcheck