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ID:239048
大小:81.00 KB
页数:12页
时间:2017-07-12
《毕业论文外文翻译-齿轮和齿轮传动》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、兰州交通大学毕业设计(论文)GearsandgeardriveGearsarethemostdurableandruggedofallmechanicaldrives.Theycantransmithighpoweratefficienciesupto98%andwithlongservicelives.Forthisreason,gearsratherthanbeltsorchainsarefoundinautomotivetransmissionsandmostheavy-dutymachinedrives.Ontheotherhand,
2、gearsaremoreexpensivethanotherdrives,especiallyiftheyaremachinedandnotmadefrompowermetalorplastic.Gearcostincreasessharplywithdemandsforhighprecisionandaccuracy.Soitisimportanttoestablishtolerancerequirementsappropriatefortheapplication.Gearsthattransmitheavyloadsorthanoper
3、ateathighspeedsarenotparticularlyexpensive,butgearsthatmustdobotharecostly.Silentgearsalsoareexpensive.Instrumentandcomputergearstendtobecostlybecausespeedordisplacementratiosmustbeexact.Attheotherextreme,gearsoperatingatlowspeedinexposedlocationsarenormallytermednocritical
4、andaremadetominimumqualitystandards.Fortoothforms,size,andquality,industrialpracticeistofollowstandardssetupbytheAmericanGearManufacturesAssociation(AGMA).ToothformStandardspublishedbyAGMAestablishgearproportionsandtoothprofiles.Toothgeometryisdeterminedprimarilybypitch,dep
5、th,andpressureangle.Pitch:StandardspitchesareusuallywholenumberswhenmeasuredasdiametralpitchP.Coarse-pitchgearinghasteethlargerthan20diametralpitch–usually0.5to19.99.Fine-pitchgearingusuallyhasteethofdiametralpitch20to200.Depth:Standardizedintermsofpitch.Standardfull-depthh
6、aveworkingdepthof2/p.Iftheteethhaveequaladdenda(asinstandardinterchangeablegears)theaddendumis1/p.Stubteethhaveaworkingdepthusually20%lessthanfull-depthteeth.Full-depthteethhavealargercontractratiothanstubteeth.Gearswithsmallnumbersofteethmayhaveundercutsothantheydonotinter
7、ferewithoneanotherduringengagement.Undercuttingreduceactiveprofileandweakensthetooth.Matinggearswithlongandshortaddendumhavelargerload-carryingcapacitythanstandardgears.Theaddendumofthesmallergear(pinion)isincreasedwhilethatoflarger12兰州交通大学毕业设计(论文)gearisdecreased,leavingthe
8、wholedepththesame.Thisformisknowasrecess-actiongearing.PressureAngle:Standardangle
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