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...
