外文翻译自动化的介绍.doc外文翻译自动化的介绍.doc

收藏

编号:201311171432396598    类型:共享资源    大小:48.50KB    格式:DOC    上传时间:2013-11-17
  
5
关 键 词:
专业文献 学术论文 精品文档 外文翻译
资源描述:
附录A:英文资料IntroductiontoAutomationAutomationisthetechnologybywhichaprocessorprocedureisaccomplishedwithouthumanassistance.Itisimplementedusingaprogramofinstructionscombinedwithacontrolsystemthatexecutestheinstructions.Toautomateaprocess,powerisrequired,bothtodrivetheprocessitselfandtooperatetheprogramandcontrolsystem.Althoughautomationcanbeappliedinawidevarietyofareas,itismostcloselyassociatedwiththemanufacturingindustries.ItwasinthecontextofmanufacturingthatthetermwasoriginallycoinedbyanengineeringmanageratFordMotorCompanyin1946todescribethevarietyofautomatictransferdevicesandfeedmechanismsthathadbeeninstalledinFord’sproductionplants.Itisironicthatnearlyallmodernapplicationsofautomationarecontrolledbycomputertechnologiesthatwerenotavailablein1964.Weexaminetechnologiesthathavebeendevelopedtoautomatemanufacturingoperations.ThepositionofautomationandcontroltechnologiesinthelargerproductionsystemisshowninFigure3.1.Inthepresentchapter,weprovideanoverviewofautomation:Whataretheelementsofanautomatedsystem?Whataresomeoftheadvancedfeaturebeyondthebasicelements?Andwhatarethelevelsinanenterprisewhereautomationcanbeapplied?Inthefollowingtwochapters,wediscussindustrialcontrolsystemsandthehardwarecomponentsofthesesystems.Thesetwochaptersserveasafoundationfortheremainingchaptersinourcoverageofautomationandcontroltechnologies.Thesetechnologiesare:(1)numericalcontrol,(2)industrialrobotics,and(3)programmablelogiccontrollers.BasicelementsofanautomatedsystemAnautomatedsystemconsistsofthreebasicelements:(1)powertoaccomplishtheprocessandoperatethesystem,(2)aprogramofinstructionstodirecttheprocess,and(3)acontrolsystemtoactuatetheinstructions.TherelationshipamongsttheseelementisillustratedinFigure3.2.Allsystemthatqualifyasbeingautomatedincludethesethreebasicelementsinoneformoranother.PowertoAccomplishtheAutomatedProcessAnautomatedsystemisusedtooperatesomeprocess,andpowerisrequiredtodrivetheprocessaswellasthecontrols.Theprincipalsourceofpowerinautomatedsystemsiselectricity.Electricpowerhasmanyadvantagesinautomatedaswellasnonautomatedprocesses:Electricalpoweriswidelyavailableatmoderatecost.Itisanimportantpartofourindustrialinfrastructure.Electricalpowercanbereadilyconvertedtoalternativeenergyforms:mechanical,thermal,light,acoustic,hydraulic,andpneumatic.Electricalpoweratlowlevelscanbeusedtoaccomplishfunctionssuchassignaltransmission,informationprocessing,anddatastorageandcommunication.Electricalenergycanbestoredinlong-lifebatteriesforuseinlocationswhereanexternalsourceofelectricalpowerisnotconvenientlyavailable.Alternativepowersourcesincludefossilfuels,solarenergy,water,andwind.However,theirexclusiveuseisrareinautomatedsystems.Inmanycaseswhenalternativepowersourcesareusedtodrivetheprocessitself,electricalpowerisusedforthecontrolsthatautomatetooperation.Forexample,incastingorheattreatment,thefurnacemaybeheartedbyfossilfuels,butthecontrolsystemtoregulatetemperatureandtimecycleiselectrical.Inothercases,theenergyfromthesealternativesourcesisconvertedtoelectricpowertooperateboththeprocessanditsautomation.Whensolarenergyisusedasapowersourceforanautomatedsystem,itisgenerallyconcertedinthisway.PowerfortheProcessInproduction,thetermprocessreferstothemanufacturingoperationthatisperformedonworkunit.Inadditiontodrivingthemanufacturingprocessitself,powerisalsorequiredforthefollowingmaterialhandlingfunctions:Loadingandunloadingtheworkunit.Thesepartsmustbemovedintotheproperpositionandorientationfortheprocesstobeperformed,andpowerisrequiredforthistransportandplacementfunction.Attheconclusionoftheprocess,theworkunitmustsimilarlyberemoved.Iftheprocessiscompletelyautomated,thensomeformofmechanizedpowermaybeusedtopositionandlocatetheworkunit.Materialtransportbetweenoperations.Inadditiontoloadingandunloadingatagivenoperation,theworkunitsmustbemovedbetweenoperations.Weconsiderthematerialhandlingtechnologiesassociatedwiththistransportfunction.PowerforAutomationAboveandbeyondthebasicpowerrequirementsforthemanufacturingoperation,additionalpowerisrequiredforautomation.Theadditionalpowerisusedforthefollowingfunctions:Controllerunit.Modernindustrialcontrollersarebasedondigitalcomputers,whichrequireelectricalpowertoreadtheprogramofinstructions,makethecontrolcalculations,andexecutetheinstructionsbytransmittingthepropercommandstotheactuationdevices.Powertoactuatethecontrolsignals.Thecommandssentbythecontrollerunitarecarriedoutbymeansofelectromechanicaldevices,suchasswitchesandmotors,calledactuators.Thecommandsaregenerallytransmittedbymeansoflow-voltagecontrolsignals.Toaccomplishthecommands,theactuatorsrequiremorepower,andsothecontrolsignalsmustbeamplifiedtoprovidetheproperpowerlevelforactuatingdevice.Dataacquisitionandinformationprocessing.Inmostcontrolsystems,datamustbecollectedfromtheprocessandusedasinputtothecontrolalgorithms.Inaddition,arequirementoftheprocessmayincludekeepingrecordsofprocessperformanceorproductquality.Thesedataacquisitionandrecordkeepingfunctionsrequirepower,althoughinmodestamounts.ProgramofInstructionsTheactionsperformedbyanautomatedprocessaredefinedbyaprogramofinstructions.Whetherthemanufacturingoperationinvolveslow,medium,orhighproduction,eachpartofproductstylemadeintheoperationrequiresoneormoreprocessingstepsthatareuniquetothatstyle.Theseprocessingstepsareperformedduringaworkcycle.Anewpartiscompletedduringeachworkcycle(insomemanufacturingoperations,morethanonepartisproducedmultiplepartseachcycleusingamultiplecavitymold).Theparticularprocessingstepsfortheworkcyclearespecifiedinaworkcycleprogram.Workcycleprogramsarecalledpartprogramsinnumericalcontrol.Otherprocesscontrolapplicationsusedifferentnamesofthistypeofprogram.WorkCycleProgramsInthesimplestautomatedprocesses,theworkcycleconsistsofessentiallyonestep,whichistomaintainasingleprocessparameteratadefinedlevel,forexample,maintainthetemperatureoffurnaceatadesignatedvalueforthedurationofaheattreatmentcycle.(Weassumethatloadingandunloadingoftheworkunitsintoandfromthefurnaceisperformedmanuallyandisthereforenotpartoftheautomaticcycle.)Inthiscase,programmingsimplyinvolvessettingthetemperaturedialonthefurnace.Tochangetheprogram,theoperatorsimplychangesthetemperaturesetting.Anextensionofthissimplecaseiswhenthesingle-stepprocessisdefinedbymorethenoneprocessparameter,forexample,afurnaceinwhichbothtemperatureandatmospherearecontrolled.Inmorecomplicatedsystems,theprocessinvolvesaworkcycleconsistingofmultiplestepsthatarerepeatedwithnodeviationfromonecycletothenext.Mostdiscretepartmanufacturingoperationsareinthiscategory.Atypicalsequenceofsteps(simplified)is:(1)loadthepartintotheproductionmachine,(2)performtheprocess,and(3)unloadthepart.Duringeachstep,thereareoneormoreactivitiesthatinvolvechangesinoneormoreprocessparameters.Processparametersareinputstotheprocess,suchastemperaturesettingofafurnace,coordinateaxisvalueinapositioningsystem,valveopenedorclosedinafluidflowsystem,andmotoronoroff.Processparametersaredistinguishedfromprocessvariables,whichareoutputsfromtheprocess;forexample,theactualtemperatureofthefurnace,theactualpositionoftheaxis,theactualflowrateofthefluidinthepipe,andtherotationalspeedofthemotor.Asourlistofexamplessuggests,thechangesinprocessparametervaluesmaybecontinuous(\gradualchangesduringtheprocessingstep;forexample,graduallyincreasingtemperatureduringaheattreatmentcycle)ordiscrete(stepwisechanges;forexample,on/off).Differentprocessparametersmaybeinvolvedineachstep.AnAutomatedTurningOperationConsideranautomatedturningoperationinwhichacone-shapedgeometryisgenerated.Assumethesystemisautomatedandthatarobotisusedtoloadandunloadtheworkunit.Theworkcycleconsistsofthefollowingsteps:(1)loadstartingworkpiece,(2)positioncuttingtoolpriortoturning,(3)turn,(4)repositiontooltoasafelocationatendofturning,and(5)unloadfinishedworkpiece.Identifytheactivityandprocessparameterineachstepoftheoperation.Solution:Instep(1),theactivitiesconsistoftherobotmanipulatorreachingfortherawworkpart,liftingandpositioningthepartintothechuckjawsofthelathe,thenparametersfortheseactivitiesaretheaxisvaluesoftherobotmanipulator,thegrippervalue,andthechuckjawvalue.Instep(2),theactivityinvolvesthemovementofthecuttingtooltoa“ready”position.Theprocessparametersassociatedwiththisactivityarethex-andz-axispositionofthetool.Step(3)istheturningoperation.Itrequiresthesimultaneouscontrolofthreeprocessparameters:rotationalspeedoftheworkpiece,feed,andradialdistanceofthecuttingtoolfromtheaxisofrotation.Tocuttheconicalshape,radialdistancemustbechangedcontinuouslyataconstantrateofeachrevolutionoftheworkpiece.Foraconsistentfinishonthesurface,therotationalspeedmustbecontinuouslyadjustedtomaintainaconstantsurfacespeed,andforequalfeedmarksonthesurface,thefeedmustbesetaconstantvalue.Dependingontheangleofthecone,multipleturningpassesmayberequiredtograduallygeneratethedesiredcontour.Eachpassrepresentsanadditionalstepinthesequence.Step(4)and(5)involvethereverseactivitiesassteps(2)and(1),respectively,andtheprocessparametersarethesame.Manyproductionoperationsconsistofmultiplesteps,sometimesmorecomplicatedthanourtruingexample.Examplesoftheseoperationsincludeautomaticscrewmachinecycles,sheet
  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
关于本文
本文标题:外文翻译自动化的介绍.doc
链接地址:http://www.renrendoc.com/p-96598.html

当前资源信息

4.0
 
(2人评价)
浏览:29次
淘宝运营上传于2013-11-17

官方联系方式

客服手机:17625900360   
2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   

精品推荐

相关阅读

人人文库
关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服客服 - 联系我们

网站客服QQ:2846424093    人人文库上传用户QQ群:460291265   

[email protected] 2016-2018  renrendoc.com 网站版权所有   南天在线技术支持

经营许可证编号:苏ICP备12009002号-5