機械工程

專業英語機械工程

1課程介紹學習專業英語的重要性學習目的為何在大三開設這門課程專業英語的英文名稱“專業英語”-----EnglishforSpecialPurposeSpecifiedEnglishfor…….“機械工程專業英語”SpecifiedEnglishforMechanicalEngineering專業英語和普通英語的區別一.詞義特點1.根據詞類辨明詞義課程介紹學習專業英語的重要性2

e.g:(1)Round(adj.)surfacereflectorisakeyunitforthesolarenergydevice.曲面反射器是太陽能裝置的關鍵元件。(2)Thisisthewholeround(n.)ofknowledge.這是全部知識范圍。2.區分場合確定詞義（不同的場合，詞義也不一樣。要根據上下文和語言環境來確定詞義）e.g:(1)pig:豬~iron生鐵(機械專業)~metal金屬錠~copper生銅(2)dog:狗(機械專業)~雞心夾頭,擋塊

e.g:(1)Round(adj.3

3.按照習慣搭配詞義e.g:(1)Ihaveashortmemory.(2)Thisbiscuiteatsshort.(3)Indeedhehasashorttemper.4.聯系上下文活用詞義e.g:(1)Thereisnophysicalcontactbetweentoolandworkpiece.工具和工件之間沒有有形（直接）的接觸。(2)High-speedgrindingdoesnotknowthisdisadvantage高速磨削不知道（存在）這個缺點。3.按照習慣搭配詞義4二.句子結構特點

1.句子長2.被動語態多e.g:Therateatwhichworkisdoneiscalledpower.3.后置定語多4.名詞化結構多e.g:tocontrolthemachine----thecontrolofthemachine

二.句子結構特點5學習方法與教學方法工具書的介紹

1.收詞不足,收詞量有限2.收詞面廣3.例證豐富4.釋義地道,全面5.詞的用法說明較詳細學習方法與教學方法6Lesson1IntroductionforMaterialsDesignersandengineersareusuallymore

interestedinthebehaviorofmaterialsunderloadorwheninamagneticfieldthaninwhytheybehaveastheydo.1.are….moreinterestedin….thanin

對…..比對…..更興趣2.underload：承載時Yetthebetteroneunderstandsthenatureofmaterialsandthereasonsfortheirphysicalandmechanicalpropertiesthemorequicklyandwiselywillhe/shebeabletochoosethepropermaterialforagivendesign.

1.thebetter….themorequicklyandwisely:越….越…..2.agivendesign:某個設計

Lesson1IntroductionforMa7Generally,amaterialpropertyisthemeasuredmagnitudeofitsresponsetoastandardtestperformedaccordingtoastandardprocedureinagivenenvironment.1.themeasuredmagnitude:測定的大小2.responseto:對…..的反應Inengineeringmaterialsthepropertiesarerecordedinhandbooksor,fornewmaterials,aremadeavailablebythesupplier.

makesth.+形容詞(sth.bemake=形容詞):使….怎么樣thepropertiesaremadeavailable:使……可獲得Generally,amaterialproperty8Frequentlysuchinformationistabulatedforroom-temperatureconditionsonly,sowhentheactualserviceconditionsareatsubfreezingorelevatedtemperatures,moreinformationisneeded.

1.room-temperatureconditions:室溫狀態2.theactualserviceconditions：實際工作狀態3.elevatedtemperatures：高溫Frequentlysuchinformationis9Thepropertiesofmaterialsaresometimesreferredtoasstructuresensitive,ascomparedtostructure-insensitiveproperties.1.bereferredtoas,beknownas:稱為2.(as)comparedto(with):

與…相比,同….比較起來,與…相對應

3.structuresensitive,structure-insensitiveproperties

結構敏感性,結構不敏感性Inthiscasestructure-insensitivepropertiesincludethetraditionalphysicalproperties:electricalandthermalconductivity,specificheat,density,andmagneticandopticalproperties.electricalandthermalconductivity:導熱性與導電性specificheat:比熱specificweight:比重Thepropertiesofmaterialsar10Thestructure-sensitivepropertiesincludethetensileandyieldstrength,hardness,andimpact,creep,andfatigueresistance.1.thetensile(strength)andyieldstrength:拉伸強度和屈服強度2.impact,creep,andfatigueresistance:抗沖擊性,抗蠕性,抗疲勞性Itisrecognizedthatsomesourcesmaintainthathardnessisnotatruemechanicalproperty,becauseitvariessomewhatwiththecharacteristicsoftheindenterandthereforeisatechnologicaltest.Itisrecognizedthat….認出,識別,考慮(認識)到somesourcesmaintain:一些資料(文件)Thestructure-sensitiveproper11

Itiswellknownthatothermechanicalpropertiesvarysignificantlywithrateofloading,temperature,geometryofnotchinimpacttesting,andthesizeandgeometryofthetestspecimen.

1.rateofloading:載荷大小2.geometryofnotchinimpacttesting:

試驗中缺口的幾何形狀Itiswellknownthatotherm12Furthermore,sincereportedtestvaluesofmaterialpropertiesarestatisticalaverages,acommercialmaterialfrequentlyhasatolerancebandof±5percentormoredeviationfrom

agivenpublishedvalue.1.reportedtestvalues:所報道的測量值2.statisticalaverages:統計平均值3.commercialmaterial:商用材料4.toleranceband:公差帶5.deviationfrom:與….的偏差6.agivenpublishedvalue:某個公布的值Furthermore,sincereportedte13Thepropertiesofmaterialsaresometimesreferredtoasstructuresensitive,ascomparedtostructure-insensitiveproperties.

bereferredtoas:指的是….;叫做;beknownas:稱為;叫做Inthiscasestructure-insensitivepropertiesincludethetraditionalphysicalproperties:electricalandthermalconductivity,specificheat,density,andmagneticandopticalproperties.

1.electricalandthermalconductivity:導熱性與導電性2.specificheat:比熱specificweight:比重Thepropertiesofmaterialsar14

Thestructure-sensitivepropertiesincludethetensileandyieldstrength,hardness,andimpact,creep,andfatigueresistance.

1.tensileandyieldstrengthtensile(strength)andyieldstrength2.impact,creep,andfatigueresistanceimpact(resistance),creep(resistance),andfatigueresistance

抗沖擊性,抗蠕變性和抗疲勞性

Itisrecognizedthatsomesourcesmaintainthathardnessisnotatruemechanicalproperty,becauseitvariessomewhat

withthecharacteristicsoftheindenterandthereforeisatechnologicaltest.

1.Itisrecognizedthat…..Itisknownthat…..Itissaidthat…..2.….varywith……Thestructure-sensitivepro15Furthermore,sincereportedtestvaluesofmaterialpropertiesarestatisticalaverages,acommercialmaterialfrequentlyhasatolerancebandof±5percentormoredeviationfromagivenpublishedvalue.…..hasatolerancebandof±5percentormoredeviationfrom……

Anyparticularmaterialcanbedescribedbyitsbehavior

whensubjectedtoexternalconditions.….describedbybehaviorwhen(anyparticularmaterial)subjectedtoexternalcondition(外力作用)Thus,whenitisloadedunderknownconditionsof

direction,magnitude,rate,andenvironment,theresultingresponsesarecalledmechanicalproperties.Whenitisloadedunderknownconditionsofdirection,magnitude,rate,andenvironment….Furthermore,sincereportedte16Mechanicalpropertiessuchasyieldstrength,impactstrength,hardness,creepandfatigueresistancearestronglystructure-sensitive,i.e.,theydependuponthearrangementoftheatomsinthecrystallatticeandonanyimperfectionsinthatarrangement,whereasthephysicalpropertiesarelessstructure-sensitive.

arrangementoftheatoms:原子排列Mechanicalpropertiessuchas17Theseincludeelectrical,thermal,magnetic,andopticalpropertiesanddodependinpartuponstructure;forexample,theresistivityofametalincreaseswiththeamountofcoldwork.1.inpart:部分2.increaseswith:隨著….而提高3.coldwork:冷作;冷成型,冷加工Physicalpropertiesdependprimarilyupontherelativeexcessordeficiencyoftheelectronsthatestablishstructuralbondsandupontheiravailabilityandmobility.

1.excessordeficiency:超過或不足2.structuralbonds:結構鍵Theseincludeelectrical,ther18Betweentheconductorswithhighelectronmobilityandtheinsulatorswithnofreeelectrons,precisecontroloftheatomicarchitecturehascreatedsemiconductorsthatcanhaveaplannedmodificationoftheirelectronmobility.

1.highelectronmobility:高電子遷移率2.theconductorswithhighelectronmobility:高電子遷移率的導體3.theinsulatorswithnofreeelectrons:無自由電子的絕緣體4.semiconductorsthatcanhaveaplannedmodificationoftheirelectronmobility有計劃改變電子遷移的半導體Betweentheconductorswithhi19Similarly,advancesinsolid-stateopticshaveledtothedevelopmentofthestimulatedemissionofelectromagneticenergyinthemicrowavespectrum(masers)andinthevisiblespectrum(lasers).1.solid-stateoptics:固態光學器件2.thestimulatedemission:激射Similarly,advancesinsolid-s20Instudyingthegeneralstructureofmaterials,onemayconsiderthreegroupings;first,atomicstructure,electronicconfiguration,bondingforces,andthearrangementoftheaggregationsofatoms;second,thephysicalaspectofmaterials,includingpropertiessuchaselectricalandthermalconductivity,specificheat,andmagnetism;andthird,theirmacroscopicproperties,suchastheirmechanicalbehaviorunderload,whichcanbeexplainedintermsofimpuritiesandimperfectionsinthelatticestructureandtheproceduresusedtomodifythatbehavior.

1.bondingforces:結合力2.aggregationsofatoms:原子團3.intermsof:用….語言來….Instudyingthegeneralstruct21專業英語的特點專業英語（specifiedEnglish）是在自然科學和工程技術的專業領域中使用的一種英語文體。它是在專業技術的不斷發展中逐漸形成并與專業技術同步發展的。由于專業技術的要求語言表述能客觀、嚴謹地反映科學研究的內容，所以，專業英語的特點，除了包含一些實驗數據、公式推導和數學符號以外，在詞匯含義、語法結構、句型使用和修辭手法等方面與日常英語、文學英語有不同的特點。這誠如著名科學家錢三強指出的：專業英語“無論在語法結構或詞匯方面都逐漸形成它特有的習慣用法、特點與規律”。不學習和掌握這些特點與規律，就很難搞好專業英語的閱讀、翻譯和寫作。為了掌握這些特點和規律，本章及下一章節將主要介紹專業英語的語法特點和詞匯特點。專業英語的特點專業英語（specifiedEnglish）22一．專業英語的語法特點1．無人稱（Impersonal）（無生命的第三人稱語氣或非人稱語氣）

科技文體第一個顯著的特點就是較多地使用無生命的第三人稱語氣。例如：

Steppermotorsareusefulwhereveraccuratecontrolofmovementisrequired.Theyareusedextensivelyinroboticsandinprinters,plottersandcomputerdiskdrives,allofwhichrequireprecisepositioningorspeed.凡需要精確控制運動的地方,步進電機都非常有用。他們廣泛用于機器人技術,打印機,繪圖儀和計算機磁盤驅動器，這些需要精確的定位或速度。一．專業英語的語法特點1．無人稱（Impersonal）（232．被動語態(PassiveVoice)

由于專業英語文獻側重敘事和推理，陳述的對象是客觀事物。讀者重視的是作者的觀點和發明的內容，而不是作者本人。因此在語言表述中必然較多地使用以客觀事物為主體的被動語態。專業英語中的被動語句不一定要說出行為主體，特別當行為主體是人時。但有時也用“by”引出行為者。這些行為者除了人、機構、物質以外，還包括完成該動作的方法、原因或過程等。例如：Thetemperatureoftheliquidisraisedbytheapplicationofheat.加熱可以提高液體溫度。Therateatwhichworkisdoneiscalledpower.3．非謂語動詞動詞非謂語形式有：動名詞、分詞、動詞不定式及它們的復合結構。專業英語中，動詞的非謂語形式應用廣泛，這是因為專業英語要求準確、精煉，而動詞的非謂語形式可以很好地實現這些要求。比如采用這一形式能用擴展的成分對所修飾的詞進行嚴格的說明和限定。其中每一個分詞定語都能代替一個從句，從而可使很長的句子勻稱,避免復雜的主從符合結構，并省略動詞時態的配合，使句子即不累贅又語意明確。

2．被動語態(PassiveVoice)243.1分詞的使用在專業英語中，分詞短語被大量地用作定語、狀語和獨立分詞結構，取代被動態或主動態的關系從句，使句子結構得到簡化。例如：1.Rammers

drivenbycompressedaircanincreasetheproductionrates.壓縮空氣驅動的舂砂器可以提高生產效率。2.Originallydesignedforrapid,automaticproductionofscrewsand

similarthreadedparts,theautomaticscrewmachinehaslongsinceexceededtheconfinesofthisnarrowfield,andtodayplaysavitalroleinthemassproductionofavarietyofprecisionparts.自動螺絲車床最初是用來對螺釘和類似的帶有螺紋的零件進行自動化快速加工的。但是，這種車床的用途早就超過了這個狹窄的范圍。現在，它在許多種類的精密零件的大批量生產中起著重要的作用。3.1分詞的使用25分詞獨立結構，即：名詞或代詞＋分詞短語，是一種主謂結構，在句中的作用相當于并列分句或從句。例如：3.Agitationiscritical,theaimbeingtodistributesiliconcarbideparticleshomogeneouslythroughoutthealuminummelt.攪拌至關重要，其目的是將碳化硅顆粒均勻地分布在整個鋁液中。

分詞獨立結構前加with(without)變成起狀語作用的介詞短語，用于當分詞的邏輯主語與句子主語不一致時。4.Intheheatexchangerofblastfurnacetheairflowsthroughtheoutsidepipe,thegasthroughtheinsidepipe,withheatexchangetakingplacethroughthewall.在高爐熱交換器中，空氣流過外管，燃氣流過內管，熱交換通過管壁進行。分詞獨立結構，即：名詞或代詞＋分詞短語，是26

3.2動名詞的使用動名詞構成的介詞短語可取代狀語從句或簡化陳述句，在英語中廣泛應用。例如：

Inredesigninganexperimentalpartforproduction,economicaltolerancesshouldbeused.為了生產而重新設計試件時,必須使用經濟公差。3.2動名詞的使用273.3不定式的使用不定式在專業英語中的使用也十分頻繁，在句中常用來替換表示目的功能的從句，使句子結構簡練。例如：1.Toinsuremanufacturequalityofelectrodes,theAmericanWeldingSocietyhassetupcertainrequirementsforelectrodes.為了確保電極的制造質量，美國焊接學會規定了電極必須具備的一些條件。2.Thereishighrequirementofskillincarryingoutthisoperationto

produceproductswithhighperformances.進行這項操作時需要很高的技巧，以生產出具有高性能的產品。3.3不定式的使用284.名詞化結構“表示動作意義的名詞＋of＋名詞＋修飾語”叫做名詞化結構。名詞化結構具有文字明了、用詞簡潔、結構緊湊、表意客觀、信息容量大等特點，在專業英語中經常用它代替主、謂結構作各種句子成分，使句子結構簡化。例如:用普通英語表達這樣一句話：Theultrasonicmetalinspectionistoapplyultrasonicvibrationstomaterialswithelasticpropertiesandtoobservetheresultingactionofthevibrationsinthematerials.用名詞化結構如下表述：Theultrasonicmetalinspectionistheapplicationofultrasonicvibrationstomaterialswithelasticpropertiesandtheobservationoftheresultingactionofthevibrationsinthematerials.金屬超聲波探傷是將超聲振動施于具有彈性的材料，并觀察振動在材料中產生的作用。4.名詞化結構29二．專業英語的詞匯特點專業英語詞匯的組成專業技術詞匯：polymerization聚合作用diathermometer熱阻測定儀mechatronics機電一體化，機械電子學lathe車床半專業技術詞匯：power力量,權力（日常英語）動力（機械專業）電力（電力專業）冪(數學專業）功率（物理專業）爆發力（體育專業）二．專業英語的詞匯特點30構詞法

英語的構詞法包括轉化、合成、派生三種形式。轉化(conversion)如：

melt熔液——tomelt熔化finish光潔度——tofinish精加工、拋光alloy合金——toalloy使成合金復合法(composition)如：

waveform波形ballbearing滾珠軸承workshop車間toolroom工具室派生或詞綴(derivation)如：

unavoidable不可避免的inaccuracy不精確構詞法31詞匯縮略首字詞縮略:它是由原詞組的每個詞首字母組成，在閱讀中首字詞要逐字母讀.例如：

NC數控AC自適應控制PLC可編程控制器AIEEAmericanInstituteofElectrical(Electronic)Engineers美國電氣（電子）工程師學會首字詞拼音:把一個詞組中的首字母拼湊成一個詞.例如laser—lightamplificationbystimulatedemissionofradiation激光ROM——readonlymemory只讀存儲器AIDS——acquiredimmunedeficiencysyndrome愛滋病詞匯縮略32節略詞:某些詞使用頻率高,為了方便，在發展過程逐漸用它們的前幾個字母來表示。例如：

ref.——reference參考文獻lab.——laboratory實驗室in.——inch英吋ft.——foot英呎縮寫詞

例如：

etc.—etcetera等等i.e—thatis即e.g.—forexample例如vs.—versus對…

拼綴:即以組成復合詞的各個詞中各抽取一或兩個詞綴相拼合。例如：

transeiver(transistor＋receiver)收發機mechatronics(mechanics＋electronics)機電一體化節略詞:某些詞使用頻率高,為了方便，在發展過程逐漸用33distinguish區別；區分distort:變形bymeansof:借助于permanent:永久的coefficient:系數steelmill:鋼廠expansion：膨脹roll:軋錕reactto:對….起作用;對….的反應crack:裂開,裂紋,破裂inconnectionwith:與…..有關gradually:逐漸地fivebroadcategories:五大類elasticity:彈性ductility:延展性toughness:韌性elevator:升降機cable:電纜beam:橫梁penetration:壓痕,凹痕abrasion:磨損elongate:延長，伸長distinguish區別；區分34Lesson2MetalsandFerrousMetalsferrousa.鐵類的，黑色的nonferrousa.有色的twogeneraltypes兩大類broadmain

However,somenonferrousmetalsmaycontainasmallamountofironasanimpurity.

asmallamountof:少量的alargeamountof:大量的

varyingamounts:不同數量的Lesson2MetalsandFerrou35Steelandcastironarethemostcommonferrousmetalsingeneraluse.

castiron鑄鐵

generaluse

普通的用途Steelisanalloycontainingchieflyiron,……andcertainotherelementsinvaryingamounts.Awiderangeofphysicalpropertiesmaybeobtainedinsteelbycontrollingtheamountofcarbonandotheralloyingelementsandbysubjectingthesteeltovariousheattreatment.

awiderangeof:各種各樣的，形形色色的besubjectedto:易受到，承受subjectsth.to……:使….承受…..Alloysteelsareformedbytheadditionofoneormoreofthefollowingelements.Steelandcastironarethemo36byfar:迄今Itistheamountofcarbonpresentwhichlargelydeterminesthemaximumhardnessobtainable.

Itis+強調部分+which……..Thehigherthecarboncontent,thehigherthetensilestrengthandthegreaterthehardnesstowhichthesteelmaybeheat-treated.

→Thesteelmaybeheat-treatedtothehardness.…….partsrequiringagreatdealofforming.

agreatdealof……:大量Medium-carbonsteelsareusedforforgingsandotherapplicationswhereincreasedstrengthandacertainamountofductilityarenecessary.Alloysteelshavespecialpropertiesdeterminedbythemixtureandtheamountofmetalsadded.mixture:混合物→金屬種類byfar:迄今37Tothemetallurgistwhoworksinmetalminingandmanufacturing,steelscontainingverysmallquantitiesofelementsotherthancarbon,phosphorus,sulphur,andsiliconareknownasalloysteels.workin：從事otherthan：除了……..beknownas……:叫做,稱為beknownfor….:因….而著名beknownto……:被知道Eachalloysteelhasapersonalityofitsown.機械工程專業英語課件38

Tool-and-diesteelsarealargegroupofsteelsusedwhencarefulheat-treatingmustbedone.Thesesteelsareusedforpartssuchaschisels,hammers,screwdrivers,springs,andtoolsanddies

usedtocutandformmetals.

Toolsteelswithcertainalloyingelementsaredesignedfor

specificuses.bedesignedto…..設計成能(做),用來…,目的是使…bedesignedfor…..用做…用途;為….而設計specific:a.1.比率，單位的e.g:specificheat,specificweight2.特殊(定,有,種)的;專門的;具體的,明確的

Tool-and-diesteelsarealar39

Themostcommonkindsoftoolsteelsincludehigh-speedtoolsteels,hotworktoolsteels,coldworktoolsteelsandspecial-purposetoolsteels.hotworktoolsteels熱加工工具鋼

coldworktoolsteels

冷加工工具鋼special-purpose專用的special-purposemachinesgeneral-purpose通用的general-purposemachines

Themostcommonkindsoftool40

Rolledsteel,whichincludesbar,rod,andstructuralsteels,isproducedbyrollingthesteelintoshape.bar扁鋼rod圓鋼byrollingthesteelintoshape軋制成形的方法….Hot-rolledsteelsareformedintoshapewhilethemetalisred-hot.

areformedintoshape成形Themetalpassesthroughaseriesofrollers,eachalittleclosertothenextone.

roller:軋錕each,one----aseriesofrollers

Rolledsteel,whichincludes41

Asthesteelpassesthroughthelastrollers,hotwaterissprayedoverit,formingabluishscale.abluishscale淡藍色的氧化層Thissteelisfairlyuniforminqualityandisusedformanydifferentkindsofparts.uniforma.均勻

Hot-rolledbarsofthebestqualityareusedtoproducecold-finishedsteels.cold-finishedsteels冷精軋鋼

Asthesteelpassesthrought42

Cold-finishedsteelsareusedwhengreataccuracy,bettersurfacefinish,andcertainmechanicalpropertiesareneeded.surfacefinish表面光潔度Themostcommonresultsinwhatiscalledcold-workedsteel.

themostcommon(way):最常見的方法resultsin:導致,引起,產生whatiscalledcold-workedsteel:所謂的冷作鋼

Cold-finishedsteelsareuse43

Afterthescalefromthehot-rolledbarsisremoved,oneoftwotechniquesisemployed.(1)Thebarsarecold-drawn,thatis,drawnthroughdiesa

fewthousandths

smallerthantheoriginalbar.cold-drawn：冷拔die：拉模(2)Thesteeliscold-rolled,thatis,rolledcoldtotheexactsize.cold-rolled:冷軋

Afterthescalefromthehot-44

Drillrodisagradeofhigh-carbontoolsteelorhigh-speedsteel.

drillrod：鉆桿agradeof：一種Itisfinishedbygrindingandpolishingsothattheoutsideissmoothandveryaccurateinsize.

it:指drillrodfinish:v.精加工n.光潔度Youcanidentifydrillrodbyitsshinysurface,whichismuchsmootherthananyoftheothersteelsusedintheshop.identify……by….通過(用)……來識別shop:車間Lesson2MetalsandFerrousMetals

Drillrodisagradeofhigh-45Drill-rodbarsaregenerallymadein3-ftlengthsandcome

inround,hexagonal,andsquareshapes.Castironisusedfortheheavypartsofmanymachines.Castironislowincostandwearswell.Itisverybrittle,however,andcannotbehammeredorformed.hammeredorformed.鍛壓成形Thebasickindsofcastironarewhiteiron,grayiron,andmalleableiron.Drill-rodbarsaregenerallym46Malleableironisaparticularkindofcastiron,mademoremalleablebyanannealingprocedure.anannealingprocedure退火工序Malleable-ironcastingsarenotsobrittleorhard.Theycanstandagreatdealhammering.Manyplumbingfixturesaremadeofmalleableiron.plumbingfixtures:管接頭Nodularironisakindofcastironthatisevenbetterforwithstandingshocks,blows,andjerks.nodulariron球墨鑄鐵Malleableironisaparticular47Lesson3Gearsspur(gears)andhelicalgears直齒輪與斜齒輪Agearhavingtoothelements

thatarestraightandparalleltoitsaxisisknownasaspurgear.Aspurpaircanbeusedtoconnectparallelshaftsonly.Parallelshaft,however,canalsobeconnectedbygearsofanothertype,andaspurgearcanbematedwithagearofadifferenttype(Fig.3-1).mate,mesh:嚙合Topreventjammingasaresultofthermalexpansion,toaidlubrication,andtocompensateforunavoidableinaccuraciesinmanufacture,allpower-transmittinggearsmusthavebacklash.

power-transmittinggears：動力傳動齒輪Lesson3Gearsspur(gears)a48Thismeansthatonthepitchcirclesofamatingpair,thespacewidthonthepinionmustbeslightlygreaterthanthetooththicknessonthegear,andviceversa.amatingpair：一對嚙合齒輪viceversa：反之亦然Oninstrumentgears,backlashcanbeeliminatedbyusingagearsplitdownitsmiddle,onehalfbeingratablerelativetotheother.eliminate：消除split：裂開relativeto：相對于Aspringforcesthesplitgearteethtooccupythefullwidthofthepinionspace.Thismeansthatonthepitch49Helicalgearshavecertainadvantages;forexample,whenconnectingparallelshaftstheyhaveahigherloadcarryingcapacitythanspurgearswiththesametoothnumbersandcutwiththesamecutter.withthesametoothnumbersspurgearscutwiththesamecutter.Becauseoftheoverlappingactionoftheteeth,theyaresmootherinactionandcanoperateathigherpitch-linevelocitiesthanspurgears.

theoverlappingaction:交錯重疊作用at……velocities:以….的速度Sincetheteethareinclinedtotheaxisofrotation,helicalgearscreateanaxialthrust.beinclinedto:向…..傾斜Helicalgearshavecertainadv50Ifusedsingly,thisthrustmustbeabsorbedintheshaftbearings.Ifusedsingly:ifthesinglehelicalgearisused,absorb:吸收承受Thethrustproblemcanbeovercomebycuttingtwosetsofopposedhelicalteethonthesameblank.twosetsofopposedhelicalteethonthesameblank.在同一個坯件上切削兩組相反的斜齒Dependingonthemethodofmanufacture,thegearmaybeofthecontinuous-toothherringbonevarietyoradouble-helicalgearwithaspacebetweenthetwohalvestopermitthecuttingtooltorunout.

continuous-toothherringbonevariety:連續人字形adouble-helicalgear:雙斜齒輪Ifusedsingly,thisthrustmu51Double-helicalgearsarewellsuitedfortheefficienttransmissionofpowerathighspeeds.Helicalgearscanalsobeusedtoconnectnonparallel,non-intersectingshaftsatanyangletooneanother.Ninetydegreesisthecommonestangleatwhichsuchgearsareused.最常用的角度為90·Double-helicalgearsarewell52wormandwormgears蝸桿蝸輪Inordertoachievelinecontactandimprovetheloadcarryingcapacityofthecrossed-axishelicalgears,thegearcanbemadetocurvepartiallyaroundthepinion,insomewhatthesamewaythatanutenvelopsascrew.

為了使交叉軸斜齒輪獲得線接觸和提高承載能力,可以把大齒輪作成部分繞小齒輪彎曲,就象螺母套在螺桿上一樣.Theresultwouldbeacylindricalwormandgear.

結果就形成一個柱形蝸桿和蝸輪wormandwormgears蝸桿蝸輪53Wormgearsprovidethesimplestmeansofobtaininglargeratiosinasinglepair.

means:方法,手段largeratiosinasinglepair一對大速比齒輪Theyareusuallylessefficientthanparallel-shaftgears,however,becauseofanadditionalslidingmovementalongtheteeth.

anadditionalslidingmovement附加滑動Becauseoftheirsimilarity,theefficiencyofawormandgeardependsonthesamefactorsastheefficiencyofascrew.Wormgearsprovidethesimples54Single-threadswormsoflargediameterhavesmallleadanglesandlowefficiencies.

single-threadsworm單頭蝸桿multiple-threadworm多頭蝸桿leadangle導角Fortransmittingrotarymotionandtorquearoundcorners,bevelgearsarecommonlyused.….transmittingrotarymotionandtorquearoundcorners…傳遞旋轉運動以及繞著一個角度傳遞扭距….Single-threadswormsoflarge55Theconnectedshafts,whoseaxeswouldintersectifextended,areusuallybutnotnecessarilyatrightanglestooneanother.

axis(單數),axes(復數)notnecessarily不一定tooneanother,totheother相互Whenadaptedforshaftsthatdonotintersect,spiralbevelgearsarecalledhypoidgears.

When(spiralbevelgears)adaptedforshafts…..Thepitchsurfacesofthesegearsarenotrollingcones,andtheratiooftheirmeandiametersisnotequaltothespeedratio.Theconnectedshafts,whoseax56Consequently,thepinionmayhavefewteethandbemadeaslargeasnecessarytocarrytheload.Theprofilesoftheteethonbevelgearsarenotinvolutes;theyareofsuchashapethatthetoolsforcutting