外文翻译---液压与气压系统.doc_第1页
外文翻译---液压与气压系统.doc_第2页
外文翻译---液压与气压系统.doc_第3页
外文翻译---液压与气压系统.doc_第4页
外文翻译---液压与气压系统.doc_第5页
已阅读5页，还剩8页未读， 继续免费阅读

付费下载

下载本文档

版权说明：本文档由用户提供并上传，收益归属内容提供方，若内容存在侵权，请进行举报或认领

文档简介

HydraulicSystemThereareonlythreebasicmethodsoftransmittingpower：Electrical，mechanicalandfluidpowerMostapplicationsactuallyuseacombinationofthethreemethodstoobtainthemostefficientoverallsystemToproperlydeterminewhichprinciplemethodtouse。itisimportanttoknowthesalientfeaturesofeachtypeForexample，fluidsystemscalltransmitpowermoreeconomicallyOvergreaterdistancesthanCanmechanicaltypesHowever。fluidsystemsarerestrictedtoshorterdistancesthanareelectricalsystemsHydraulicpowertransmissionsystemaleconcernedwiththegeneration,modulation,andcontrolofpressureandflowand,andingeneralsuchsystemsinclude:1Pumpswhichconvertavailablepowerfromtheprimemovertohydraulicpowerattheactuator2Valveswhichcontrolthedirectionofpump-flow，thelevelofpowerproduced，andtheamountoffluid一一flowtotheactuatorsThepowerlevelisdeterminedbycontrollingboththeflowandpressurelevel3ActuatorswhichconverthydraulicpowertousablemechanicalpowerOutputatthepointrequired4Themedium，whichisaliquid，providesrigidtransmissionandcontrolaswellas1ubricationofcomponents，sealinginvalvesandcoolingofthesystem5Connectorswhichlinkthevarioussystemcomponents，providepowerconductorsforthefluidunderpressure，andfluidflowreturntotank(reservoir)6、Fluidstorageandconditioningequipmentwhichensuresufficientqualityandquantityaswellascoolingofthefluid7、pneumaticssystemsrequiredalubricatortoinject。averyfinemistofoilintotheairdischargingfromthepressureregulatorThispreventswearofthecloselyfittingmovingpartsofpneumaticHydraulicsystemsaleusedinindustrialapplicationssuchasstampingpresses，steelmills，andgeneralmanufacturing，agriculturalmachines，miningindustry，aviation，spacetechnology，deepseaexploration,transportation，marinetechnology，andoffshoregasandpetroleumexplorationInshort，veryfewpeoplegetthroughadayoftheir1iveswithoutsomehowbenefitingfromthetechnologyofhydraulics2Theprincipleofelectrical-dischargemachiningalsocalledelectroisorspark-erosionmachining,isbasedontheerosionofmetalsbysparkdischarges.Weknowthatwhentwocurrent-conductinwiresareallowedtotoucheachother,anarcisproduced.Ifwelookcloselyatthepointofcontactbetweenthetwowires,wenotethatasmallportionofthemetalhasbeenerodedaway,leavingasmallcrater.ThebasicEDMsystemconsistsofashapetoolandtheworkpiece,connectedtoadcpowersupplyandplacedinadielectricfluidthisisoneofthemostwidelyusedmachiningprocesses,particularlyfordie-sinkingoperationswhenthepotentialdifferencebetweenthetoolandtheworkpieceissufficientlyhigh,atransientsparkdischargesthroughthefluid,removingaverysmallamountofmetalfromtheworkpiecesurface.Thecapacitordischargeisrepeatedatratesofbetween50,withvoltagesusuallyrangingbetween50vand380vandcurrentsfrom0.1Ato500A.Mechanicalcontrolincludescamsandgovernors.Althoughtheyhavebeenusedforthecontrolofverycomplexmachines,tobecosteffectively,todaytheyareusedforsimpleandfixed-cycletaskcontrol.Someautomatedmachines,suchasscrewmachines,stillusecam-basedcontrol.Mechanicalcontrolisdifficulttomanufactureandissubjecttowear.Pneumaticcontrolisstillverypopularforcertainapplications.Itusescompressedair,valves,andswitchstoconstructsimplecontrollogic,butiseasilyslow.Becausestandardcompaonentsareusedtoconstructthelogic,itiseasiertobuildthanamechanicalcontrol.Pneumaticcontrolpartsaresubjecttowear.Asdoesamechanicalcontrol,anelectromechanicalcontrolusesswitches,relays,timescounters,andsoon,toconstructlogic,itisfasterandmoreflexible.Thecontrollersusingelectromechanicalcontrolarecalledrelaydevices.Thevaluesintheexpresstherelativetooldistancefromthehomeposition.Thisdistanceisshownintherelativeorincrementalcoordinates,UandW.whenreadingthevaluesinthenotpossibletoknowdirectlyhowfarthetoolisfromthepartorigin.Justhowfaritisfromthehomeposition.mountedonexhaustportsofairvalvesandactuatorstoreducenoiseandpreventoperatingpersonnelfrompossibleinjuryresultingnotonlyfromexposuretonoisebutalsofromhighspeedairborneparticles.Thesignofthecoordinatesiszeroornegativebecausethetoolcannotmovefartherthanthemachineorigin.thusatpresent,thevaluesarezerosothetoolisatthehomeposition.Thevaluesinthearenormallyusedwhensettingupthetoolsinordertofindtherealtooldistancesfromthepartorigin.Thevaluesintheabsolutepositionexpresstheabsolutetooldistancefromthepartorigin.Thisdistanceisshowninshowninabsolutecoordinates,xandz.thesignmaybepositiveornegative,dependingonthequadrantsinwhichthetoolismoving.becauseofthecompressibilityofair，itisimpossibletoobtainprecisecontrolledactuatorvelocitieswithpneumaticsystemsalso，precisepositioningcontrolisnotobtainableWhilepneumaticpressuresarequitesofaristogood.Thisisanimportantpieceofinformationfortheoperatorwhenmaching,sinceanyvalueintheabsolutepositionisdirectlyrelatedtothepart.ThesecretofhydraulicsystemsSUCCESSandwidespreaduseisitsversatilityandmanageabilityFluidpowerisnothinderedbythegeometryoperationswhenthepotentialdifferencebetweenthetoolandtheworkpieceissufficientlyhigh,atransientsparkdischargesthroughthefluid,removingaverysmallamountofmetalfromtheworkpieceofthemachineasistheeaseinmechanicalsystemsAlso，powercanbetransmittedinalmostlimitlessquantitiesbecausefluidsystemsarenotsolimitedbythephysical1imitationsofmaterialsasaretheelectricalsystemsForexample，theperformanceofanelectromagnetislimitedbyThesaturationlimitofsteelOntheotherhand，thepowerlimitoffluidsystemsis1imitedonlybythestrengthcapacityofthematerialIntheexpresstherelativetooldistancefromthehomeposition.Thisdistanceisshownintherelativeorincrementalcoordinates,UandW.whenreadingthevaluesinthenotpossibletoknowdirectlyhowfarthetoolisfromthepartorigin.Justhowfaritisfromthehomeposition.Thesignofthecoordinatesiszeroornegativebecausethetoolcannotmovefartherthanthemachineorigin.thusatpresent,thevaluesarezerosothetoolisatthehomeposition.Thevaluesinthearenormallyusedwhensettingupthetoolsinordertofindtherealtooldistancesfromthepartorigin.IndustryisgoingtodependmoreandmoreonautomationinordertoincreaseproductivityThisincludesremoteanddirectcontrolofproductionoperations，manufacturingprocesses。andmaterialshandlingFluidpoweristhemuscleofautomationbecauseofadvantagesinthefollowingfourmajorcategories1Easeandaccuracyofcontr01BytheuseofSimpleleversandpushbuttons，theoperatorofafluidpowersystemCallreadilystart，stop，speeduporslowdown，andpositionforceswhichprovideanydesiredhorsepowerWithtolerancesaspreciseasonetenthousandthOfaninchFig131showsafluidpowersystemwhichallowsallaircraftpilottoraiseandlowerhislandinggearWhenthepilotmovesasmallcontr01valveinonedirection，oilunderpressureflowstooneendofthecylindertolowerthelandinggearToretractthelandinggear，thepilotmovesthevalveleverintheoppositedirection，a110wlng0iltoflowintotheotherendofthecylinder2MultiplicationofforceAfluidpowersystem(withoutusingcumbersomegears，pulleys，andlevers)CanmultiplyforcesSimplyandefficientlyfromafractionofanouncetoseveralhundredtonsofoutput3ConstantforceortorqueOnlyfluidpowersystemsarecapableofprovidingconstantforceortorqueregardlessofspeedchangesThisisaccomplishedwhethertheworkoutputmovesafewinchesperhour，severalhundredinchesperminute，afewrevolutionsperhourorthousandsofrevolutionsperminute4Simplicity，safety，economygeneral，fluidpowersystemsusefewermovingpartsthancomparablemechanicalorelectricalsystemsThus，theyalesimplertomainta
人人文库> 全部分类> 教育资料 > 外文翻译

温馨提示

  • 1. 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
  • 2. 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
  • 3. 本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
  • 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
  • 5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
  • 6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
  • 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

最新文档

评论

0/150

提交评论