Lesson4ShaftsandCouplings•Terminology•Texttour25/1/11《机械工程专业英语教程》Terminology25/1/12《机械工程专业英语教程》•Coupling•Acouplingisadeviceforconnectingtheendsofadjacentshafts.•联轴器:联轴器是用来把相邻的两个轴的轴端联接起来的装置《机械工程专业英语教程》25/1/1SocketwrenchAwrenchwithausuallyinterchangeablesockettofitoveranutorbolt3套筒扳手:通常带有可替换套筒以适于螺帽或螺栓的扳手《机械工程专业英语教程》25/1/1KeywayAslotforakeyinthehuborshaftofawheel键槽:轮毂里或轴上装键的沟槽Bolt螺栓,螺杆4《机械工程专业英语教程》25/1/1screw:螺钉Screwdriver:螺丝刀socket:插座,插口,套筒扳手wrench:扳手,拧,扳紧,扭转5《机械工程专业英语教程》25/1/1stem:杆,棒,柄,柱,轴clutch:抓住,捏紧,离合器Cold-roll:冷轧,冷轧机forge:锻造,打制,锻工车间key:键Keyway:键槽,销座6《机械工程专业英语教程》25/1/1propeller:螺旋桨,推进器flange:凸缘,法兰盘hub:衬套,轮毂Flexiblecoupling:弹性联轴器,挠性联轴器7Virtually(infact)allmachinescontainshafts.Themostcommonshapeforshaftsiscircularandthecrosssection(截面)canbeeithersolidorhollow(hollowshaftscanresultinweightsavings减轻重量).《机械工程专业英语教程》25/1/1Texttour8Rectangularshaftsaresometimesused,asinscrewdriverblades,socketwrenchesandcontrolknobstems(螺丝刀的头、套筒扳手和控制旋扭的杆).Ashaftmusthaveadequatetorsionalstrength(抗扭强度)totransmittorqueandnotbeoverstressed.《机械工程专业英语教程》25/1/19Generallyspeaking,theangleoftwist(扭转角)shouldnotexceedonedegreeinashaftlengthequalto20diameters.Itmustalsobetorsionallystiff(刚度)enoughsothatonemountedcomponentdoesnotdeviateexcessivelyfromitsoriginalangularpositionrelativetoasecondcomponentmountedonthesameshaft.Shaftsaremountedinbearingsandtransmitpowerthroughsuchdevicesasgears,pulleys,camsandclutches(齿轮、皮带轮、凸轮和离合器).《机械工程专业英语教程》25/1/110Thesedevicesintroduceforceswhichattempttobendtheshaft;hence,theshaftmustberigidenoughtopreventoverloadingofthesupportingbearings.Ingeneral,thebendingdeflectionofashaftshouldnotexceed0.01in.perftoflengthbetweenbearingssupports.Inaddition,theshaftmustbeabletosustainacombinationofbendingandtorsionalloads(弯矩和扭矩).Thusanequivalent(等效的,当量的)loadmustbeconsideredwhichtakesintoaccountbothtorsionandbending.《机械工程专业英语教程》25/1/111Also,theallowablestressmustcontainafactorofsafetywhichincludesfatigue,sincetorsionalandbendingstressreversals(交变)occur.Fordiameterslessthan3in.,theusualshaftmaterialiscold-rolledsteelcontainingabout0.4percentcarbon.《机械工程专业英语教程》25/1/112Shaftsareeithercold-rolledorforge(锻造)insizesfrom3in.to5in.Forsizesaboutover5in.,shaftsareforgedandmachinedtosize.《机械工程专业英语教程》25/1/113Plasticshaftsarewidelyusedforlightloadapplications.Oneadvantageofusingplasticissafetyinelectricalapplications,sinceplasticisapoorconductor(导体)ofelectricity.Componentssuchasgearsandpulleysaremountedonshaftsbymeansofkey.《机械工程专业英语教程》25/1/114Thedesignofthekeyandthecorrespondingkeyway(键槽)intheshaftmustbeproperlyevaluated(分析,判断).Forexample,stressconcentrations(应力集中)occurinshaftsduetokeyways,andthematerialremovedtoformthekeywayfurtherweakenstheshaft.Ifshaftsarerunatcritical(临界的)speeds,severe(严重的,强烈的)vibrationscanoccurwhichcanseriouslydamageamachine.《机械工程专业英语教程》25/1/115Itisimportanttoknowthemagnitudeoft...