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外文翻译--液压与气动系统.doc

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外文翻译--液压与气动系统.doc

1HydraulicSystemThereareonlyfollowingthreebasicmethodsoftransmittingpowerelectrical,mechanical,andfluidpower.Mostapplicationsactuallyuseacombinationofthethreemethodstoobtainthemostefficientoverallsystem.Toproperlydeterminewhichprinciplemethodtouse,itisimportanttounderstandthecharacteristicofeachmethod.Forexample,hydraulicsystemsonthelongdistanceeconomicallydeliverpowermorethanmechanicalsystems.However,fluidsystemsarerestrictedtoshorterdistancesthanelectricalsystems.Hydraulicpowertransmissionsystemsareconcernedwiththegeneration,modulation,andcontrolofsculptressandflow,andingeneralsuchsystemsincludel.Pumpsconvertavailablepowerfromtheprimemovertohydraulicpowerattheactuator.2.Valvescontrolthedirectionofpumpflow,thelevelofproducedpower,andtheamountoffluidflowtotheactuators.Thepowerlevelisdeterminedbycontrollingboththeflowandpressurelevel.3.Actuatorsconverthydraulicpowertousablemechanicalpoweroutputatthepointrequired.4.Themediumisaliquid,providesrigidtransmissionandcontrolaswellaslubricationofcomponents,sealinginvalves,andcoolingofthesystem.5.Connectorslinkthevarioussystemcomponents,providepowerconductorsforthefluidunderpressure,andfluidflowreturntotank(reservoir.6.Fluidstorageandconditioningequipmentensuresufficientqualityandquantityaswellascoolingofthefluid.Hydraulicsystemsareusedinindustrialapplicationssuchasstampingpresses,steelmillsandgeneralmanufacturing,agriculturalmachines,miningindustry,aviation,spacetechnology,deepseaexploration,transportation,Narinetechnology,andoffshoregasandpetroleumexploration.Inshort,manypeoplegetsomehowbenefitingfromthetechnologyofhydraulics.Thesecretofthesuccessandwidespreaduseofthehydraulicsystemisitsversatilityandmanageability.Fluidpowerisnothinderedbythegeometryofthemachineasisthecaseinmechanicalsystems.Also,powercanbetransmittedinalmostlimitlessquantitiesbecausefluidsystemsarenotsolimitedbythephysicallimitationsofmaterialsasaretheelectricalsystems.Forexample,theperformanceofanelectromagnetislimitedbythesaturationlimitofsteel.Ontheotherhand,thepowerlimitoffluidsystemsislimitedonlybythestrengthcapacityofthematerial.Industryisgoingtodependmoreandmoreonautomationinordertoincreaseproductivity.Thisincludesremotionanddirectcontrolofproductionoperations,manufacturingprocesses,andmaterialshandling.Fluidpoweristhemuscleofautomationbecauseoftheadvantagesinthefollowingfourmajorcategories.1.Easeandaccuracyofcontrol.Bytheuseofsimpleleversandpushbuttons,theoperatorofafluidpowersystemcanreadilystart,stop,speeduporslowdown,andprovideanydesired2horsepowerwithtolerancesaspreciseasonetenthousandthofaninch.2.Multiplicationofforce.Afluidpowersystemwithoutusingcumbersomegears,pulleys,andleverscanmultiplyforcesimplyandefficientlycreatetheoutputfromafractionofanouncetoseveralhundredtons.3.Constantforceortorque.Onlyfluidpowersystemsarecapableofprovidingconstantforceortorqueregardlessofspeedchanges.Itproducestheworkoutputmovingfromafewinchesperhourtoseveralhundredinchesperminute,orfromafewrevolutionsperhourtothousandsofrevolutionsperminute.4.Simplicity,safety,economy.Ingeneral,fluidpowersystemsusefewermovingpartsthancomparablemechanicalorelectricalsystems.Thus,theyaresimplertomaintainandoperate.This,inturn,maximizessafety,compactness,andreliability.Forexample,anewpowersteeringcontroldesignhasmadeallotherkindsofpowersystemsobsoleteonmanyoffhighwayvehicles.Thesteeringunitconsistsofamanuallyoperateddirectionalcontrolvalveandmeterinasinglebody.Becausethesteeringunitisfullyfluidlinked,withoutthelinkofmechanicallinkages,universaljoints,bearings,reductiongears,etc.Thisprovidesasimple,compactsystem.Inaddition,verylittleinputtorqueisrequiredtoproducethecontrolneededforthetoughestapplications.Thisisimportantwherelimitationsofcontrolspacerequireasmallsteeringwheelanditbecomesnecessarytoreduceoperatorfatigue.Additionalbenefitsoffluidpowersystemsincludeinstantlyreversiblemotion,automaticprotectionagainstoverloads,andinfinitelyvariablespeedcontrol.Fluidpowersystemsalsohavethehighesthorsepowerperweightratioofanyknownpowersource.Inspiteofallthesehighlydesirablefeaturesoffluidpower,itisnotapanaceaforallpowertransmissionproblems.Hydraulicsystemsalsohavesomedrawbacks.Hydraulicoilsaremessy,andleakageisimpossibletocompletelyeliminate.Also,mosthydraulicoilscancausetiresifanoilleakoccursinanareaofhotequipment.Now,aconcreteexampleisfollowingweusehydraulicstationstointroducetheadvantagesofthehydraulicsystem.HydraulicStationandthedevelopmentofhydrauliccomponentsProfilesHydraulicPumpStationalsoknownasthestationsisindependenthydraulicdevice.Itisrequestedbytheoilgraduallyandcontrolsthehydraulicoilflowdirection,pressureandflowrate,appliedtothemainframeandhydraulicdevicesabilityofhydraulicmachinery.Usersjustneedtoconnecthydraulicstationandhostofimplementingagenciesmotoroilorfueltankswithtubing.Hydraulicmachinerycanrealizethesespecifiedmovementsandtheworkcycle.HydraulicpumpstationisequippedwithPumpdevice,manifoldorvalveportfolio,tanks,electricalboxes.Pumpdeviceisequippedwithmotorsandpumps.Hydraulicstationisthesourceofpowerandcantranslatemechanicalenergyintohydraulicoilpressure.Manifoldisinstalledbyhydraulicvalveandassembledchannel.Ithasthefunctionofadjustingthedirectionforimplementationofhydraulicoil,pressureandflow.Valveportfolioplatevalveisinstalledinupboard,thebackboardconnectsandhasthe3samefunctionalwithIC.Tankplateweldingsemiclosedcontainers,alsoisloadedwithoilfilteringnetwork,airfiltersansisusedtosaveoil,oilfiltersandcooling.Electricalboxeshasthetwopatterns.Asetofexternalfuseterminalplateandafullrangeofcontrolelectrical.TheprincipleofthehydraulicStationthemotordrivespumprotation,pumpabsorbsoilfromtheoiltank,thentranslatesmechanicalenergyintohydraulicpressureofthestation.HydraulicoilthroughManifoldorvalvecombinationsrealizedthedirection,pressure.Afteradjustingflowpipe,itexternalflowstothecylinderhydraulicmachineryormotoroil,soastocontrolthedirectionofthemotivefluid,thesizeoftransformationforceandthespeedofthepace,finallyitpromoteshydraulicmachinerytothevariousacting.Firstly,AdevelopmentcourseChinaHydraulicincludinghydraulic,thesamebelow,pneumaticandsealsindustrialdevelopmentprocesscanbebroadlydividedintothreephases,namelytheearly1950stotheearly1960sistheinitialstage.The60sand70sisthegrowthstageforspecializedproductionsystem.The80s90sisthegrowthstagefortherapiddevelopment.Meanwhile,hydraulicindustrystartedintheearly1950sfromthemachinetoolindustryproductionoffakeusgrinder,broachingmachine,copyinglathe,andotherhydraulicdrive.HydraulicComponentsfromtheplanthydraulicmachineshopisselfoccupied.Afterenteringthel960s,theapplicationofhydraulictechnologyfromthemachinegraduallyextendedtotheagriculturalmachineryandmechanicalengineeringfields,attachedtotheoriginalvelocityofhydraulicshopsomestandoutaspiecesofhydraulicprofessionalproduction.Tothelate1960s,early1970s,withthedevelopmentofmechanizedproduction,especiallythesecondautomobilefactoryprovidesefficient,automatedequipment.TheHydraulicComponentsmanufacturinghasexperiencedrapidlydevelopmentofthesituation.GroupsofSMEhavebecomeprofessionalhydraulicpartsfactory.Chinaannualoutputofhydrauliccomponentshasnearly200.000in1968.Machinetools,agriculturalmachinery,mechanicalengineeringindustries,theproductionofhydraulicpartsfactoryhavebeentheprofessionaldevelopmentofmorethan100andanannualoutputmorethanonemillionin1973andanindependenthydraulicmanufacturingindustryhasbeguntotakeshape.Then,hydraulicpiecesoffakeproductshasdevelopedfromtheSovietUnionfortheintroductionoftheproductandcombiningtheproducts.Hypertensionhasdevelopedtomediumandhighpressureandthedevelopmentoftheelectrohydraulicservovalvesandsystems,hydraulicapplicationareasfurtherexpanded.Pneumaticindustrystartedlaterthantheindustrialhydraulicyears.Until1967professionalpneumaticcomponentsfactorybegantoestablish.PneumaticComponentslookedonlyascommodityproductionandsales.Itdealwithrubberandplastics,mechanicalsealsandsealingflexiblegraphite.Intheearly1950s,itproducedordinary0rings,rubberandplasticsextrusion,suchasoilsealsealingandsealasbestos.Untiltheearly1960s,itbeguntoproductionof4mechanicalsealsandflexiblegraphitesealingproducts.In1970s,undertheburningoftheformerMinistry,aMinistry,theMinistryofAgriculturalMechanizationSystem,agroupofprofessionalproductionplantshavebeenestablished,andtheofficialestablishmentofindustriestosealindustrialdevelopmenthaslaidthefoundationforgrowth.Sincethel980s,undertheguidelinesofcountrysreformandopeninguppolicy,withthedevelopmentofthemachineryindustry,basedmainframepiecesbehindtheconflictshavebecomeincreasinglyprominentandattractedtheattentionoftherelevantdepartments.Tothisend,theMinistryoriginatingin1982andformedthebasisofcommonpiecesofIndustry,willcentralizehydraulic,pneumaticandsealsspecializedfactoriesoriginalmachinetoolsscatteredinagriculturalmachinery,mechanicalengineeringindustriesandplacethemundercommonmanagementinfrastructurepiecesBureau,sothattheindustryintheplanning,investment,technologyandscientificresearchanddevelopmentinareasgottheguidanceandsupportofinfrastructurepiecesBureau.Sincethenitenteredaphaseofrapiddevelopmentandhasintroducedmorethan60itemsofadvancedtechnologyfromabroad,includingmorethan40itemsofhydraulic,pneumatic7.Afterdigestionandabsorptionandtransformation,nowtheyhavemassproduction,andindustryleadingproducts.Inrecentyears,theindustryhasincreasedthetechnologicaltransformationefforts.Fom1991to1998,state,LocalenterprisesandtheselfFinancinghavefundtotalinputofabout20billion,ofwhichHydraulicwasmorethanI.6billion.Throughtechnologicaltransformationandtechnologyresearch,anumberofmajorenterpriseshavefurtherimprovedtheleveloftechnology,techniqueandequipment,whichhaslaidagoodfoundationinordertoformahigherStartingpoint,specialization,andrunproduction.Inrecentyears,undertheguidelinesofdevelopmentofcommonownership,differentownershipSMErapidlyhaverisetoshowgreatvitality.Withthefurtheropeningup,threefundedenterprisesdevelopedrapidlywhichplayedanimportantroletothedevelopmentofindustrystandardsandexpandingexports.Today,ChinaandtheUnitedStates,Japan,Germanyandothercountriesfamousmanufacturershaveestablishedjointventuresorwhollyownedbyforeignmanufacturerswhichinvolvedinapistonpump/motor,planetaryreductiongears,steeringgear,hydrauliccontrolvalve,hydraulicsystem,hydrostatictransmission,hydraulicCasting,pneumaticcontrolvalve,cylinder,gasprocessingtriplepieces,mechanicalseals,rubberandsealproducts.Ithasmorethan50productionenterprisesandattractedforeigninvestmentover200millionU.S.dollars.Secondly,thecurrentsituation(1)BasicProfilesAfter40yearsofefforts,Chinahydraulic,pneumaticandsealingindustryhaveformedtheindustrialsystemwitharelativelycompletecategories,acertainleveloftechnicalcapacity.Accordingtothe1995,ThirdNationalIndustrialCensusstatisticssaidthatstateowned,villagerun,privateandcooperativeenterprises,individual,threecapitalenterpriseswithatotalofmorethan1,300engagedinhydraulicPneumaticandsealingpartsindustrywithannualsales

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