数控技术双语吴瑞明习题参考答案.docx

数控技术双语吴瑞明习题参考答案.docx

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数控技术双语吴瑞明习题参考答案

Chapter1IntroductionofCNC

1.1NarratetheconceptofNC.

Numericalcontrol（NC）isaformofprogrammableautomationinwhichthemechanicalactionsofamachinetoolorotherequipmentarecontrolledbyaprogramcontainingcodedalphanumericdata.

1.2NarratetheconceptofCNC.

ACNCmachineisanNCmachinewiththeaddedfeatureofanonboardcomputer.TheonboardcomputerisoftenreferredtoasthemachinecontrolunitorMCU.ControlunitsforNCmachinesareusuallyhardwired,whichmeansthatallmachinefunctionsarecontrolledbythephysicalelectronicelementsthatarebuiltintothecontroller.

1.3WhatarethecomponentsofCNCmachinetool,andthefunctionofeachcomponent?

StructureofCNCmachinetool

CNCmachineiscomposedthefollowingparts.

（1）CNCdevice

TheCNCdeviceisthekerneloftheCNCsystem.Itsfunctionistohandletheinputpartmachiningprogramoroperationcommand,thenoutputcontrolcommandtotheappropriateexecutivepartsandfinishtheworkwhichthepartsmachiningprogramandoperationneed.

（2）ServoUnit,drivedeviceandmeasuredevice

Servounitanddrivedeviceincludespindleservodrivedevice,spindlemotor,feedservodrivedeviceandfeedmotor.Measuredevicemeanspositionandspeedmeasuredevice,itisanecessarydevicetofinishthespindlecontrol,closed-loopforthefeedspeedandforthefeedposition.

（3）Controlpanel

Controlpanel,calledoperationpanel,isatoolusedformutualinformationbetweentheoperatorandtheCNCmachine.

（4）Controlmediumandprograminputandoutputequipment

Thecontrolmediumisanagenttorecordthepartmachiningprogramanditisalsothemediumtosetupcontractionbetweenmanandmachine.PrograminputandoutputequipmentarethedevicesbywhichtheinformationexchangecanbedonebetweentheCNCsystemandexternalequipment.ItseffectistoinputthepartmachiningprogramrecordedonthecontrolmediumintotheCNCsystemandtostoreorrecordthedebuggedpartmachiningprogramontheappropriatemediumwiththeoutputdevice.

（5）Machinebody

TheobjectofCNCsystemistheexecutiveparttofulfillthemachiningparts.Itiscomposedofthemainmotionparts,feedmotionparts,bearingrackandspecialdevice,automaticplatformchangesystem,automatictoolchangersystemandaccessorydevice.

1.4WhatisthePoint-to-pointcontrol,Contouringcontrol?

Point-to-pointsystem,alsocalledPositingcontrolsystems,movestheworktabletoaprogrammedlocationwithoutregardforthepathtakentogettothelocation.

ThecontouringfacilityenablesaCNCmachinetofollowanypathatanyprescribedfeed-rate.Thecontouringcontrolsystem,alsocalledcontinuouspathcontrolsystems,managesthesimultaneousmotionofthecuttingtoolintwo,three,four,orfiveaxes（thefourthandfifthaxesareangularorientations）byinterpolatingtheproperpathbetweenprescribedpoints.

1.5Whatistheopen-loopcontrol,Half-closed-loopcontrolandClosed-loopcontrol?

Open-loopsystemshavenoaccesstotherealtimedataabouttheperformanceofthesystemandthereforenoimmediatecorrectiveactioncanbetakenincaseofsystemdisturbance.

Asemi-closed-loopcontrolCNCsystemusesfeedbackmeasurementstoensurethattheworktableismovedtothedesiredposition.Itischaracterizedasasystemthattheindirectfeedbackmonitorstheoutputofservomotor.

Inacloseloopsystem,feedbackdevicescloselymonitortheoutputandanydisturbancewillbecorrectedinthefirstinstance.

1.6WhataretheadvantagesanddisadvantagesofCNC?

CNCopensupnewpossibilitiesandadvantagesnotofferedbyolderNCmachines.

（1）Reductioninthehardwarenecessarytoaddamachinefunction.NewfunctionscanbeprogrammedintotheMCUassoftware.

（2）TheCNCprogramcanbewritten,stored,andexecuteddirectlyattheCNCmachine.

（3）AnyportionofanenteredCNCprogramcanbeplayedbackandeditedatwill.Toolmotionscanbeelectronicallydisplayeduponplayback.

（4）ManydifferentCNCprogramscanbestoredintheMCU.

（5）SeveralCNCmachinescanbelinkedtogethertoamaincomputer.ProgramswrittenviathemaincomputercanbedownloadedtoanyCNCmachineinthenetwork.ThisisknownasdirectnumericalcontrolorDNC.

（6）SeveralDNCsystemscanalsobenetworkedtoformalargedistributivenumericalcontrolsystem.

（7）TheCNCprogramcanbeinputfromflashorfloppydisksordownloadedfromlocalareanetworks.

CNCmachinescandramaticallyboostproductivity.TheCNCmanager,however,canonlyensuresuchgainsbyfirstaddressingseveralcriticalissues,suchasthefollowing:

（1）SufficientcapitalmustbeallocatedforpurchasingqualityCNCequipment.

（2）CNCequipmentmustbemaintainedonaregularbasisbyobtainingafull-servicecontractorbyhiringanin-housetechnician.

（3）PersonnelmustbethoroughlytrainedintheoperationofCNCmachines.Inparticular,manyjobsrequiresetupsformachiningpartstocomplywithtolerancesofformandfunction.

（4）CarefulproductionplanningmustbestudiedbecausethehourlycostofoperationofaCNCmachineisusuallyhigherthanthatforconventionalmachines.

1.7NarratethefinancialrewardsofCNCinvestmentusingReturnonInvestment.

Returnoninvestment（ROI）isusedtoestimateinvestmentefficiency.TheROIcalculationpredictswhatpercentofthenetcostoftheCNCwillberecoveredeachyear.TheROIcalculationaccountsfortheusefullifeoftheCNCmachinetool.

Chapter2CNCPartProgramming

2.1Readandmatchthepicturetothenameofthehandtool.

[13]hacksaw[8]benchvise[2]filecard[16]scraper[23]die

[4]handtaps[25]hammer[12]burnishingtool[6]adjustablewrench[3]tapextractor

[11]hexkey[18]arborpress[15]T-handletapwrench[20]handreamer[9]screwdriver

[1]pliers[17]externallap[14]rotaryfiles[19]Phillips[10]open-endwrench

screwdriver

[24]broaches[20]socketwrench[22]tumblingmachine[22]diestock[5]file

2.2Studythefollowingwords

Verniercalipersareprecisiontoolsusedtomakeaccuratemeasurementstowithin0.001inchor0.02mm.Theycanmeasuretheoutsidediameterorwidthofanobject.Theycanmeasuretheinsidediameterorwidthofanobject.Theycanalsomeasurethedepthofanobject.Verniercalipersareavailableininchandmetricgraduations.Sometypeshavebothinchandmetricgraduationsonthesamecaliper.TheverniercaliperconsistsofoneL-shapedframeandonemovablejaw.TheL-shapedframeconsistsofabarandthefixedjaw.Thebarshowsthemainscalegraduations.Themovablejawslidesalongthebarandcontainsthevernierscale.Anadjustingnutadjustsforsizeandthelockingorclampscrewslockreadingsintoplace.

Mostbarsaregraduatedonbothsidesoronbothedges.Onesidetakesoutsidemeasurementsandtheothertakesinsidemeasurements.Theinternaljawsmeasureinsidespaceslikeholes.Theexternaljawsmeasurethingsliketheoutsidediameterofapieceofpipe.

Lookatthetwofiguresbelowanddeterminethereadings.

Thisreads3.3mm

2.3Themicrometer

Sleevereadsfullmm=7mm

Sleevereads½mm=0.5mm

Thimblereads=26

Totalmeasurement=7.76mm

2.4NarrateCNCcoordinatesystems.

TheCartesian,orrectangular,coordinatesystemwasdevisedbytheFrenchmathematicianandphilosopherRene’Descartes.Withthissystem,anyspecificpointcanbedescribedinmathematicaltermsfromanyotherpointalongthreeperpendicularaxes.Thisconceptfitsmachinetoolsperfectlysincetheirconstructionisgenerallybasedonthreeaxesofmotion（X,Y,Z）plusanaxisofrotation.Onaplainverticalmillingmachine,theXaxisisthehorizontalmovement（rightorleft）ofthetable,theYaxisisthetablecrossmovement（towardorawayfromthecolumn）,andtheZaxisistheverticalmovementofthekneeorthespindle.CNCsystemsrelyheavilyontheuseofrectangularcoordinatesbecausetheprogrammercanlocateeverypointonajobprecisely.

Coordinatesystem

2.5GivetheCNCprogramoffollowingFigure2.50（units:

mm）.

φ40×100,45#

0-TC（FANUC）

O0001;

N10T0101;

N20S400M03;

N30G00X40.Z2.;

N40G71U1.5R1.;（U:

Depthofcut,R:

Escapingamount）

N50G71P60.Q150.U0.5W0.2F0.3;（P:

Sequencenumberofthefirstblock,

Q:

Sequencenumberofthelastblock,

U:

FinishingallowanceinXdirection,

W:

FinishingallowanceinZdirection）

N60G01X18.Z0.;（Startpoint）

N80X20.Z-1.;（1×45°）

N90G01Z-10.;（φ20）

N100X26.;

N110X28.Z-11.;（1×45°）

N120Z-25.;

N140X35.Z-31.;

N150Z-36.;（Endpoint）

N160G70P60Q150S1100F0.05;（N60--N150）

N170G00X50.Z60.;

N180T0202;（Toolchange）

N190S200M03;

N210G00X37.Z-40.;

N220G01X0.F0.03;（Cutoff,Cutterwidth4mm）

N230G00X50.;

N240G00Z0.;

N250M05;

N260M02;

2.6GivetheCNCprogramoffollowingFigure2.51（units:

mm）.

φ60×105,45#

%PM3333（Maho）

N3333

N1G54

N2G99X60Z105

N3G96S200D2500T1001M4（Constantsurfacespeedcontrol,

Linearvelocity（m/min）200,Maximumspeed（rpm）2500）

N4G0X65Z110

N5G1X65Z100F0.5M8

N6G1X-0.5F0.1（Facework）

N7G10X65Z110I0.5K0.5C2.5F0.5（FinishingallowanceX,Z0.5,cuttingdepth/P2.5,Startfrom60,110）

N8G42

N9G1X0Z100（Startpoint）

N10G3X20Z90R10

N11G1X48Z90

N12G1Z20（φ48）

N13G1X60

N14G1Z17（Endpoint）

N15G40

N20G13N1=8N2=15（Machiningcyclecall）

N21G0X200Z150M5

N22T2002M4

N23G12X60Z105S200（Finishingmachiningdefinition）

N24G13N1=8N2=15

N25G0X300Z200M5

N30T3003M4（Cutterwidth5mm）

N40S100

N42G0X65Z40（Cutterpoint:

left）

N43G0X50

N44G1X42

N47G0X65M5

N48T4004M4（Screwcuttingtool）

N51G97S1200

N52G0X48Z105（Screwcuttingstartpoi