英文翻译 液压传动系统设计与计算.docx

英文翻译 液压传动系统设计与计算.docx

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英文翻译液压传动系统设计与计算

河南农业大学毕业论文（设计）

英文翻译

翻译题目：

液压传动系统设计与计算

学院机电工程学院

专业班级06机制（3）班

学生姓名陈重

指导教师魏宗信

2010年5月3日

Hydraulicactuationsystemdesignandcomputation

1isclearaboutthedesignrequesttocarryontheoperatingmodeanalysis.

Whendesignhydraulicsystembelow,firstshouldbeclearaboutthequestion,andtakesitasthedesignbasis.

Mainengineuse,technologicalprocess,overalllayoutaswellastohydraulicgearpositionandspatialsizerequest;Themainenginetothehydraulicsystemperformancerequirement,liketheautomaticity,thevelocitymodulationscope,themovementstability,thecommutationpointingaccuracyaswellastherequestwhichtothesystemefficiency,warmpromotes;Hydraulicsystemworkingconditions,liketemperature,humidity,vibrationimpactaswellaswhetherhassituationandsooncorrosivenessandheat-sensitivematerialexistence.

Inintheaboveworkfoundation,shouldcarryontheoperatingmodeanalysistothemainengine,theoperatingmodeanalysisincludingthemovementanalysisandthemechanicalanalysis,alsomustestablishtheloadandtheoperatingcyclecharttothecomplexsystem,fromthisunderstoodthehydrauliccylinderortheoilmotorloadandthespeedchangeasnecessarytherule,belowmakestheconcreteintroductiontotheoperatingmodeanalysiscontent

1.1movementsanalyses

Themainenginefunctionalelementaccordingtothetechnologicalrequirementmovementsituation,mayusethedisplacementcirculationchart（L—t）,thespeedcirculationchart（v—t）,orthespeedandthedisplacementcirculationchartindicated,fromthiscarriesontheanalysistothemovementrule.

1.1.1displacementscirculationattemptsL—t

Thechart1.1isthehydraulicpresshydrauliccylindermovesthecirculationchart,they-coordinateLexpressionpistonmoves,thex-coordinatetexpressionstartsfromthepistontotherepositiontime,therateofcurveexpressionmovementofplungerspeed.

Chart1.1displacementscirculationchart

1.1.2speedscirculationchartv—t（orv—L）

Intheprojectthehydrauliccylindermovementcharacteristicmayinduceisthreekindoftypes.Thechart1.2isthreekindoftypeshydrauliccylindersv—tchart,thefirstkindoflikechart1.2centersolidlinesshow,thehydrauliccylinderstartstomaketheuniformacceleratedmotion,thenuniformmotion,

Chart1.2speedscirculationchart

Finallyuniformretardedmotiontoendpoint;Thesecondkind,thehydrauliccylinderprecedingpartlymakestheuniformacceleratedmotionintheoveralltravellingschedule,inanotheronepartlymakestheuniformretardedmotion,alsotheaccelerationvalueisequal;Thethirdkind,thehydrauliccylinderonemostabovemakestheuniformacceleratedmotionintheoveralltravellingschedulebyasmalleracceleration,thenuniformdeceleratestothetravellingscheduleendpoint.V—tchartthreevelocitycurve,notonlyclearlyhasindicatedthreekindoftypeshydrauliccylindersmovementrule,alsoindirectlyhasindicatedthreekindofoperatingmodesdynamicperformance.

1.2mechanicalanalyses

1.2.1hydrauliccylindersloadsanddutycyclechart

1.2.1.1hydrauliccylindersloadstrengthcomputations

Whentheoperatingmechanismmakesthestraightreciprocatingmotion,thehydrauliccylindermustovercometheloadiscomposedbysixparts

（1.1）

Intheformula:

FcInordertoresistancetocutting;FfInordertofrictiondrag;FiForinertiaresistance;FgForgravity;FmInordertosealtheresistance;FbInordertodraintheoiltheresistance.

1.2.1.2hydrauliccylinderscycleofmotionvariousstagesoverallloadstrength

Thehydrauliccylindercycleofmotionvariousstagesoverallloadstrengthcomputation,generallyincludesthestartacceleration,quicklyenters,thelaborenters,quicklydrawsback,deceleratesappliesthebrakeandsoonseveralstages,eachstageoverallloadstrengthhasthedifference.

（1）startstheaccelerationperiod:

Bynowthehydrauliccylinderorthepistonwereinfromstaticenoughtostartsandacceleratestothecertainspeed,itsoverallloadstrengthincludingguiderailfrictionforce,packingassemblyfrictionforce（accordingtocylindermechanicalefficiencyηm=0.9computation）,gravityandsoonitem,namely:

　　　　（1.2）

（2）faststage:

（1.3）

（3）thelaborentersthestage:

　　　　　　　　　（1.4）（4）decelerates:

（1.5）

Tothesimplehydraulicsystem,theabovecomputationprocessmaysimplify.Forexampleusesthesingleproportioningpumptosupplytheoil,onlymustcalculatethelabortoenterthestagetheoverallloadstrength,ifthesimplesystemusesthelimitingpressuretypevariabledisplacementpumporapairofassociationpumpsfortheoil,thenonlymustcalculatethefaststageandthelaborentersthestagetheoverallloadstrength.

1.2.2oilmotorsload

Whentheoperatingmechanismmakestherotarymotion,theoilmotormustovercometheoutsideloadis:

（1.6）

1.2.2.1operatingdutiesmomentofforceMe.Theoperatingdutymomentofforceispossiblyadefinitevalue,alsopossiblyasnecessarychanges,shouldcarryontheconcreteanalysisaccordingtothemachineworkingcondition.

1.2.2.2frictionmoments.Inordertorevolvethepartjournalplacefrictionmoment,itsformulais:

　（1.7）

Intheformula:

Gisrevolvesthepartweight（N）;Fistherubbingfactor,whenthestartforthefactor,afterthestartformovestherubbingfactor;Risthejournalradius（m）.

1.2.2.3momentofinertiaMi.Themomentofinertiawhichinordertorevolvethepartaccelerationordecelerateswhenproduces,itsformulais:

（1.8）

Intheformula:

εIstheangleacceleration（r/s2）;

istheaccelerationordeceleratesthetime（s）;Jisrevolvesthepartrotationinertia（

）,

Intheformula:

Inordertorotatetheparttheflywheeleffect（

）.

Eachkindmaylookup

Accordingtothetype（1.6）,separatelyfiguresouttheoilmotorinaoperatingcyclevariousstagesloadsize,thenmaydrawuptheoilmotorthedutycyclechart

2determinationshydraulicsystemmainparameter

2.1hydrauliccylindersdesigncalculations

2.1.1initiallydecidesthehydrauliccylinderworkingpressure

Inthehydrauliccylinderworkingpressuremainbasiscycleofmotionvariousstagesbiggestoverallloadstrengthdetermined,inadditionbelow,butalsoneedstoconsiderthefactor:

2.1.1.1eachkindofequipmentdifferentcharacteristicandusesituation.

2.1.1.2considerationseconomiesandtheweightfactor,thepressureelectslowly,thenpartsizebig,theweightisheavy;Thepressurechooseshighsomewhat,thenpartsizesmall,theweightislight,buttothepartmanufactureprecision,thesealingpropertyrequestshigh.

Therefore,thehydrauliccylinderworkingpressurechoicehastwoways:

One,electsaccordingtothemechanicaltype;Two,accordingtocutstheloadtoelect.

Ifthetable2.1,thetable2.2shows.

Thetable2.1pressestheloadtochoosetheexecutionfiletheworkingpressure

Load

/N

＜5000

500～10000

10000～20000

20000～30000

30000～50000

＞50000

Workingpressure

/MPa

≤0.8～1

1.5～2

2.5～3

3～4

4～5

＞5

Thetable2.2pressesthemechanicaltypetochoosetheexecutionfiletheworkingpressure

Mechanicaltype

Enginebed

Farmmachinery

Projectmachinery

Grinder

Aggregatemachine-tool

DragonGatedigsthebed

Broachingmachine

Workingpressure

/MPa

a≤2

3～5

≤8

8～10

10～16

20～32

2.2oilmotorsdesigncalculation

2.2.1computationsoilmotordisplacement

Underoilmotordisplacementaccordingtothetypedecidedthat,

（2.1）

Intheformula:

Tistheoilmotorloadmomentofforce（N·m）;

Foroilmotorimportandexportpressuredifference（n/m3）;istheoilmotormechanicalefficiency,thecommongearandtheplungermotortakes0.9~0.95,theleafblademotortakes0.8~0.9.

2.2.2computationsoilmotorneedsthecurrentcapacityoilmotorthemaximumcurrentcapacity

　　　（2.2）

Intheformula:

istheoilmotordisplacement（m3/r）;

istheoilmotorhighestrotationalspeed（r/s）.

3hydraulicpressurepartschoice

3.1hydraulicpumpsdeterminationswithneedthepowerthecomputation

3.1.1.1determinesthehydraulicpumpthebiggestworkingpressure.Thehydraulicpressurepumpingstationmusttheworkingpressuredetermination,mainlyactsaccordingtothehydrauliccylinderintheoperatingcyclevariousstagestohavemosttremendouspressurep1,inadditiontheoilpumplosesSigmaDeltaptheoilmouthtothecylinderplacealwayspressureΣΔp,namely

（3.1）

loses,thepipelineincludingtheoilaftertheflowvalveandotherpartslocalpressuresalongtheregulationlossandsoon,beforesystempipelinedesign,mayactaccordingtothesimilarsystemexperiencetoestimate,commonpipelinesimplethrottlevalvevelocitymodulationsystemΣΔpis（2~5）×105Pa,withthevelocitymodulationvalveandpipelinecomplexsystem

is（5~15）×105Pa,

alsomayonlyconsiderflowsaftervariouscontrolvalvespressureloss,butignoresthecircuitryalongtheregulationloss,variousvalvesratedpressurelosesmaysearchesfromthehydraulicpressureparthandbookortheproductsample,Alsomayrefertothetable1.3selections

Thetable3.1iscommonlyused,thelowpressureeachkindofvalvepressureloses（Δpn）

Valve

Δpn（×105Pa）

Valve

Δpn（×105Pa）

Valve

Δpn（×105Pa）

Valve

Δpn（×105Pa）

Cone-wayvalve

0.3～0.5

Cone-wayvalve

3～8

Cone-wayvalve

1.5～2

Cone-wayvalve

1.5～2

Crossvalve

1.5～3

Crossvalve

2～3

Crossvalve

1.5～3

Crossvalve

3～5

3.1.2determinesthehydraulicpumpcurrentcapacityqB

Pumpsthecurrentcapacity

basisfunctionalelementoperatingcyclemustthemaximumcurrentcapacity

andthes