液压与气压系统中英文对照学习资料.docx
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液压与气压系统中英文对照学习资料.docx
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液压与气压系统中英文对照学习资料
HydraulicSystem——液压与气压系统【中英文对照】
HydraulicSystem
Thereareonlythreebasicmethodsoftransmittingpower:
Electrical,mechanical.andfluidpower.Mostapplicationsactuallyuseacombinationofthethreemethodstoobtainthemostefficientoverallsystem.Toproperlydeterminewhichprinciplemethodtouse。
itisimportanttoknowthesalientfeaturesofeachtype.Forexample,fluidsystemscalltransmitpowermoreeconomicallyOvergreaterdistancesthanCanmechanicaltypes.However。
fluidsystemsare
restrictedtoshorterdistancesthanareelectricalsystems.
Hydraulicpowertransmissionsystemaleconcernedwiththegeneration,modulation,andcontrolofpressureandflowand,andingeneralsuchsystemsinclude:
1.Pumpswhichconvertavailablepowerfromtheprimemovertohydraulicpowerattheactuator.
2.Valveswhichcontrolthedirectionofpump--flow,thelevelofpowerproduced,andtheamountoffluid一一flowtotheactuators.Thepowerlevelisdeterminedbycontrollingboththeflowandpressurelevel.
3.ActuatorswhichconverthydraulicpowertousablemechanicalpowerOutputatthepointrequired.
4.Themedium,whichisaliquid,providesrigidtransmissionandcontrolaswellas1ubricationofcomponents,sealinginvalves.andcoolingofthesystem.
5.Connectorswhichlinkthevarioussystemcomponents,providepowerconductorsforthefluidunderpressure,andfluidflowreturntotank(reservoir)..
6、Fluidstorageandconditioningequipmentwhichensuresufficientqualityandquantityaswellascoolingofthefluid.
7、pneumaticssystemsrequiredalubricatortoinject。
averyfinemistofoilintotheairdischargingfromthepressureregulator.Thispreventswearofthecloselyfittingmovingpartsofpneumatic
Hydraulicsystemsaleusedinindustrialapplicationssuchasstampingpresses,steelmills,andgeneralmanufacturing,agriculturalmachines,miningindustry,aviation,spacetechnology,deep—seaexploration,transportation,marinetechnology,andoffshoregasandpetroleumexploration.Inshort,veryfewpeoplegetthroughadayoftheir1iveswithoutsomehowbenefitingfromthetechnologyofhydraulics2.
Theprincipleofelectrical-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.mountedonexhaustportsofairvalvesandactuatorstoreducenoiseandpreventoperatingpersonnelfrompossibleinjuryresultingnotonlyfromexposuretonoisebutalsofromhigh—speedairborneparticles.Thesignofthecoordinatesiszeroornegativebecausethetoolcannotmovefartherthanthemachineorigin.thusatpresent,thevaluesarezerosothetoolisatthehomeposition.Thevaluesinthearenormallyusedwhensettingupthetoolsinordertofindtherealtooldistancesfromthepartorigin.
Thevaluesintheabsolutepositionexpresstheabsolutetooldistancefromthepartorigin.Thisdistanceisshowninshowninabsolutecoordinates,xandz.thesignmaybepositiveornegative,dependingonthequadrantsinwhichthetoolismoving.becauseofthecompressibilityofair,
itisimpossibletoobtainprecisecontrolledactuatorvelocitieswithpneumaticsystems.also,precisepositioningcontrolisnotobtainable.Whilepneumaticpressuresarequitesofaristogood.Thisisanimportantpieceofinformationfortheoperatorwhenmaching,sinceanyvalueintheabsolutepositionisdirectlyrelatedtothepart.
Thesecretofhydraulicsystem’sSUCCESSandwidespreaduseisitsversatilityandmanageability.Fluidpowerisnothinderedbythegeometryoperationswhenthepotentialdifferencebetweenthetoolandtheworkpieceissufficientlyhigh,atransientsparkdischargesthroughthefluid,removingaverysmallamountofmetalfromtheworkpieceofthemachineasistheeaseinmechanicalsystems.Also,powercanbetransmittedinalmostlimitlessquantitiesbecausefluidsystemsarenotsolimitedbythephysical1imitationsofmaterialsasaretheelectricalsystems.Forexample,theperformanceofanelectromagnetislimitedbyThesaturationlimitofsteel.Ontheotherhand,thepowerlimitoffluidsystemsis1imitedonlybythestrengthcapacityofthematerial.
Intheexpresstherelativetooldistancefromthehomeposition.Thisdistanceisshownintherelativeorincrementalcoordinates,UandW.whenreadingthevaluesinthenotpossibletoknowdirectlyhowfarthetoolisfromthepartorigin.
Justhowfaritisfromthehomeposition.Thesignofthecoordinatesiszeroornegativebecausethetoolcannotmovefartherthanthemachineorigin.thusatpresent,thevaluesarezerosothetoolisatthehomeposition.Thevaluesinthearenormallyusedwhensettingupthetoolsinordertofindtherealtooldistancesfromthepartorigin.
Industryisgoingtodependmoreandmoreonautomationinordertoincreaseproductivity.Thisincludesremoteanddirectcontrolofproductionoperations,manufacturingprocesses。
andmaterialshandling.
Fluidpoweristhemuscleofautomationbecauseofadvantagesinthefollowingfourmajorcategories.
1.Easeandaccuracyofcontr01.BytheuseofSimpleleversandpushbuttons,theoperatorofafluidpowersystemCallreadilystart,stop,speeduporslowdown,andpositionforceswhichprovideanydesiredhorsepowerWithtolerancesaspreciseasoneten—thousandthOfaninch.Fig.13—1showsafluidpowersystemwhichallowsallaircraftpilottoraiseandlowerhislandinggear.Whenthepilotmovesasmallcontr01valveinonedirection,oilunderpressureflowstooneendofthecylindertolowerthelandinggear.Toretractthelandinggear,thepilot
movesthevalveleverintheoppositedirection,a110wlng0iltoflowintotheotherendofthecylinder.
2.Multiplicationofforce.Afluidpowersystem(withoutusingcumbersomegears,pulleys,andlevers)CanmultiplyforcesSimplyandefficientlyfromafractionofanouncetoseveralhundredtonsofoutput.
3.Constantforceortorque.Onlyfluidpowersystemsarecapableofprovidingconstantforceortorqueregardlessofspeedchanges.Thisisaccomplishedwhethertheworkoutputmovesafewinchesperhour,severalhundredinchesperminute,afewrevolutionsperhour.orthousandsof
revolutionsperminute.
4.Simplicity,safety,economy.general,fluidpowersystemsusefewermovingpartsthan
comparablemechanicalorelectricalsystems.
Thus,theyalesimplertomaintainandoperate.This,inturn,maximizessafety,compactness,andreliability.Forexample,anewpowersteeringcontr01designedhasmadeallotherkindsofpowersystemsobsoleteonmany
off—highwayvehicles.TheSteeringunitconsistsofamanuallyoperateddirectional
controlvalveandmeterinasinglebody.transportation,marinetechnology,andoffshoregasandpetroleumexploration.Inshort,veryfewpeoplegetthroughadayoftheir1iveswithoutsomehowbenefitingfromthetechnologyofhydraulics2.Becausethesteeringunitisfullyfluid1inked,mechanicallinkages,universaljoints。
bearings,reductiongears,etc.areeliminated.Thisprovidesasimple,compactsystem.Inaddition,verylittleinputtorqueisrequiredtoproducethecontrolneededforthetoughestapplications.Thisisimportantwhere1imitationsofcontrolspacerequireasmallsteeringwheelanditbecomesnecessarytoreduceoperatorfatigue.
Thereareseveraltypesofshaftcouplings;theircharacteristicsdependonthepruposeforwhichtheyareused.Ifanexceptionallylongshaftisrequiredforalineshaftinthemanufacturingplantorapropellershaftonship,itismadeinsectionsthatarecoupledtogetherwithrigidcouplings.
Additionalbenefitsoffluidpowersystemsincludeinstantlyreversiblemotion。
automatic.protectionagainstoverloads,andinfinitelyvariablespeedcontr01.Fluidpowersystemsalsohavethehighesthorsepowerperweightrati0
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