CNC数控机电一体化毕业设计英文资料翻译.docx
- 文档编号:11162984
- 上传时间:2023-02-25
- 格式:DOCX
- 页数:17
- 大小:45.55KB
CNC数控机电一体化毕业设计英文资料翻译.docx
《CNC数控机电一体化毕业设计英文资料翻译.docx》由会员分享,可在线阅读,更多相关《CNC数控机电一体化毕业设计英文资料翻译.docx(17页珍藏版)》请在冰豆网上搜索。
CNC数控机电一体化毕业设计英文资料翻译
英文资料翻译
题目CNC
2011年12月
CNC
CNCstandsforComputerizedNumericalControlandhasbeenaroundsincetheearly1970s.priortothis,itwascalledNC,fornumericalcontrol.Whilepeopleinmostwalksoflifehaveneverheardofthisterm,CNChastouchedalmosteveryformofmanufacturingprocessinonewayoranother.Ifyou'llbeworkinginmanufacturing,it'slikelythatyou'llbedealingwithCNConaregularbasis.
BeforeCNC
Whilethereareexceptionstothisstatement,CNCmachinestypicallyreplace(orworkinconjunctionwith)someexistingmanufacturingprocesses.Takeoneofthesimplestmanufacturingprocesses,drillingholes,forexample.
Adrillpresscanofcoursebeusedtomachineholes.Apersoncanplaceadrillinthedrillchuckthatissecuredinthespindleofthedrillpress.Theycanthen(manually)selectthedesiredspeedforrotation(commonlybyswitchingbeltpulleys),andactivatethespindle.Thentheymanuallypullonthequilllevertodrivethedrillintotheworkpiecebeingmachined.
Asyoucaneasilysee,thereisalotofmanualinterventionrequiredtouseadrillpresstoholes.Apersonisrequiredtodosomethingalmosteverystepalongtheway!
Whilethismanualinterventionmaybeacceptableformanufacturingcompaniesifbutasmallnumberofholesworkpiecesmustbemachined,asquantitiesgrow,sodoesthelikelihoodforfatigueduetothetediousnessoftheoperation.Anddonotethatwe'veusedoneofthesimplestmachiningoperations(drilling)forourexample.Therearemorecomplicatedmachiningoperationsthatwouldrequireamuchhigherskilllevel(andincreasethepotentialformistakesresultinginscrapworkpieces)ofthepersonrunningtheconventionalmachinetool.(WecommonlyrefertostyleofmachinethatCNCisreplacingastheconventionalmachine.)
Bycomparison,theCNCequivalentforadrillpress(possiblyaCNCmachiningcenterorCNCdrilling&tappingcenter)canbeprogrammedtoperformthisoperationinamuchmoreautomaticfashion.EverythingthatthedrillpressoperatorwasdoingmanuallywillnowbedonebytheCNCmachine,including:
placingthedrillinthespindle,activatingthespindle,positioningtheworkpieceunderthedrill,machiningthehole,andturningoffthespindle.
HowCNCworks
Asyoumightalreadyhaveguessed,everythingthatanoperatorwouldberequiredtodowithconventionalmachinetoolsisprogrammablewithCNCmachines.Oncethemachineissetupandrunning,aCNCmachineisquitesimpletokeeprunning.InfactCNCoperatorstendtogetquiteboredduringlengthyproductionrunsbecausethereissolittletodo.WithsomeCNCmachines,someofthespecificprogrammablefunctions.
Motioncontrol
AllCNCmachinetypessharethiscommonalty:
Theyallhavetwoormoreprogrammabledirectionsofmotioncalledaxes.Anaxisofmotioncanbelinear(alongastraightline)orrotary(alongacircularpath).OneofthefirstspecificationsthatimplyaCNCmachine'scomplexityishowmanyaxesithas.Generallyspeaking,themoreaxes,themorecomplexthemachine.
TheaxesofanyCNCmachinearerequiredforthepurposeofcausingthemotionsneededforthemanufacturingprocess.Inthedrillingexample,theseaxeswouldpositionthentoolovertheholetobemachined(intwoaxes)andmachinethehole(withthethirdaxis).Axesarenamedwithletters.CommonlinearaxisnamedX,Y,andZ.CommonrotarynamesareA,B,andC.Therearerelatedtothecoordinatesystem.
Programmableaccessories
ACNCmachinewouldn'tbeveryhelpfulifallitcouldonlymovetheworkpieceintwoormoreaxes.AlmostallCNCmachinesareprogrammableinseveralotherways.ThespecificCNCmachinetypehasalottodowithitsappropriateprogrammableaccessories.Again,anyrequiredfunctionwillbeprogrammableonfull-blownCNCmachinetools.Herearesomeexamplesforonemachinetype(machiningcenters).
Automatictoolchanger
Mostmachiningcenterscanholdmanytoolsinatoolmagazine.Whenrequired,therequiredtoolcanbeautomaticallyplacedinspindleformachining.
Spindlespeedandactivation
Thespindlespeed(inrevolutionsperminute)canbeeasilyspecifiedandthespindlecanbeturnedoninaforwardorreversedirection.Itcanalso,ofcourse,beturnedoff.
Coolant
Manymachiningoperationsrequirecoolantforlubricationandcoolingpurposes.Coolantcanbeturnedonandofffromwithinthemachinecycle.
TheCNCprogram
Thinkofgivinganyseriesofstep-by-stepinstructions.ACNCprogramisnothingmorethananotherkindofinstructionset.It'swritteninsentence-likeformatandthecontrolwillexecuteitinsequentialorder,stepbystep.
AspecialseriesofCNCwordsareusedtocommunicatewhatthemachineisintendedtodo.CNCwordsbeginwithletteraddress(likeFforfeedrate,Sforspindlespeed,andX,Y,andZforaxismotion).Whenplacedtogetherinalogicalmethod,agroupofCNCwordsmakeupacommandthatresembleasentence.
TheCNCcontrol
TheCNCcontrolwillinterpretaCNCprogramandactivetheseriesofcommandsinsequentialorder.Asitreadstheprogram,theCNCcontrolwillactivatetheappropriatemachinefunctions,causeaxismotion,andingeneral,followtheinstructionsgivenintheprogram.
AlongwithinterpretingtheCNCprogram,theCNCcontrolhasseveralotherpurposes.AllcurrentmodelCNCcontrolsallowprogramstobemodified(edited)ifmistakesarefound.TheCNCcontrolallowsspecialverificationfunctions(likedryrun)toconfirmthecorrectnessoftheCNCprogram.TheCNCcontrolallowscertainimportantoperatorinputstobespecifiedseparatefromtheprogram,liketoollengthvalues.Ingeneral,theCNCcontrolallowsfunctionsofthemachinetobemanipulated.
WhatisaCAMsystem?
Forsimpleapplications(likedrillingholes),theCNCprogramcandevelopedmanually.Thatis,aprogrammerwillsitdowntowritetheprogramarmedonlywithpencil,paper,andcalculator.Again,forsimpleapplications,thismaybetheverybestwaytodevelopCNCprograms.
Asapplicationsgetmorecomplicated,andespeciallywhennewprogramsarerequiredonaregularbasis,writingprogramsmanuallybecomesmuchmoredifficult.Tosimplifytheprogrammingprocess,acomputeraidedmanufacturing(CAM)systemcanbeused.ACAMsystemisasoftwareprogramthatrunsonacomputer(commonlyaPC)thathelpstheCNCprogrammerwiththeprogrammingprocess.Generallyspeaking,aCAMsystemwilltakethetediousnessanddrudgeryoutofprogramming.
InmanycompaniestheCAMsystemwillworkwiththecomputeraideddesign(CAD)drawingdevelopedbythecomputer'sdesignengineeringdepartment.ThiseliminatestheneedforredefiningtheworkpiececonfigurationtotheCAMsystem.TheCNCprogrammerwillsimplyspecifythemachiningoperationstobeperformedandtheCAMsystemwillcreatetheCNCprogram(muchlikethemanualprogrammerwouldhavewritten)automatically.
WhatisaDNCsystem?
Oncetheprogramisdeveloped(eithermanuallyorwithaCAMsystem),itmustbeloadedintotheCNCcontrol.Toughthesetuppersoncouldtypetheprogramrightintothecontrol,thiswouldbelikeusingtheCNCmachineasaveryexpensivetypewrite.IftheCNCprogramisdevelopedwiththehelpofaCAMsystem,thenitisalreadyintheformofatextfile.Iftheprogramiswrittenmanually,itcanbetypedintoanycomputerusingacommonwordprocessor(thoughmostcompaniesuseaspecialCNCtexteditorforthispurpose).Eitherway,theprogramisintheformofatextfilethatcanbetransferredrightintotheCNCmachine.Adistributivenumericalcontrol(DNC)systemisusedforthispurpose.
ADNCsystemisnothingmorethanacomputerthatisnetworkedwithoneormoreCNCmachines.Untilonlyrecently,rathercrudeserialcommunicationsprotocol(RS-232C)hadtobeusedfortransferringprograms.Newercontrolshavemorecurrentcommunicationscapabilitiesandcanbenetworkedinmoreconventionalways(Ethernet,etc.).Regardlessofmethods,theCNCprogrammustofcoursebeloadedintotheCNCmachinebeforeitcanberun.
WhenNumericalControlisperformedundercomputersupervision,itiscalledComputerNumericalControl(CNC).ComputersarethecontrolunitsofCNCmachines.Theyarebuiltinorlinkedtothemachinesviacommunicationschannels.Whenaprogrammerinputssomeinformationintheprogrambytapeandsoon,thecomputercalculatesallnecessarydatatogetthejobdone.
Today’ssystemshavecomputerscontroldata,sotheyarecalledComputerNumericallyControlledMachines.ForbothNCandCNCsystems,workprinciplesarethesame.Onlythewayinwhichtheexecutioniscontrolledisdifferent.Normally,newsystemsarefaster,morepowerful,andmoreversatileunit.
TheConstructionofCNCMachines
CNCmachinetoolsarecomplexassemblies.However,ingeneral,anyCNCmachinetoolconsistsofthefollowingunits:
computers,controlsystems,drivemotorsandtoolchangers.
AccordingtotheconstructionofCNCmachinetools,CNCmachinesworkinthefollowingmanner:
(1)TheCNCmachinelanguage,whichisaprogramminglanguageofbinarynotationusedoncomputers,isnotusedonCNCmachines.
(2)Whentheoperatorstartstheexecutioncycle,thecomputertranslatesbinarycodesintoelectronicpulsesthatareautomaticallysenttothemachine’spowerunits.Thecontrolunitscomparethenumberofpulsessentandreceived.
(3)Whenthemotorsreceiveeachpulse,theyautomaticallytransformthepulsesintorotationsthatdrivethespindleandleadscrew,causingthespindlerotationandslideortablemovement.Thepartonthemillingmachinetableorthetoolinthelatheturretisdriventothepositionspecifiedbytheprogram.
1.Computers
Aswithallcomputers,theCNCmachinecomputer
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- CNC 数控 机电 一体化 毕业设计 英文 资料 翻译