機(jī)械工程專業(yè)英語

機(jī)械工程

專業(yè)英語課程介紹學(xué)習(xí)專業(yè)英語的重要性學(xué)習(xí)目的為何在大三開設(shè)這門課程專業(yè)英語的英文名稱“專業(yè)英語”-----EnglishforSpecialPurposeSpecifiedEnglishfor…….“機(jī)械工程專業(yè)英語”SpecifiedEnglishforMechanicalEngineering專業(yè)英語和普通英語的區(qū)別一.詞義特點(diǎn)1.根據(jù)詞類辨明詞義

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

3.按照習(xí)慣搭配詞義e.g:(1)Ihaveashortmemory.(2)Thisbiscuiteatsshort.(3)Indeedhehasashorttemper.4.聯(lián)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(gè)缺點(diǎn)。二.句子結(jié)構(gòu)特點(diǎn)

1.句子長2.被動(dòng)語態(tài)多e.g:Therateatwhichworkisdoneiscalledpower.3.后置定語多4.名詞化結(jié)構(gòu)多e.g:tocontrolthemachine----thecontrolofthemachine

學(xué)習(xí)方法與教學(xué)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(xì)Lesson1IntroductionforMaterialsDesignersandengineersareusuallymore

interestedinthebehaviorofmaterialsunderloadorwheninamagneticfieldthaninwhytheybehaveastheydo.1.are….moreinterestedin….thanin

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

1.thebetter….themorequicklyandwisely:越….越…..2.agivendesign:某個(gè)設(shè)計(jì)

Generally,amaterialpropertyisthemeasuredmagnitudeofitsresponsetoastandardtestperformedaccordingtoastandardprocedureinagivenenvironment.1.themeasuredmagnitude:測定的大小2.responseto:對…..的反應(yīng)Inengineeringmaterialsthepropertiesarerecordedinhandbooksor,fornewmaterials,aremadeavailablebythesupplier.

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

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

與…相比,同….比較起來,與…相對應(yīng)

3.structuresensitive,structure-insensitiveproperties

結(jié)構(gòu)敏感性,結(jié)構(gòu)不敏感性Inthiscasestructure-insensitivepropertiesincludethetraditionalphysicalproperties:electricalandthermalconductivity,specificheat,density,andmagneticandopticalproperties.electricalandthermalconductivity:導(dǎo)熱性與導(dǎo)電性specificheat:比熱specificweight:比重Thestructure-sensitivepropertiesincludethetensileandyieldstrength,hardness,andimpact,creep,andfatigueresistance.1.thetensile(strength)andyieldstrength:拉伸強(qiáng)度和屈服強(qiáng)度2.impact,creep,andfatigueresistance:抗沖擊性,抗蠕性,抗疲勞性Itisrecognizedthatsomesourcesmaintainthathardnessisnotatruemechanicalproperty,becauseitvariessomewhatwiththecharacteristicsoftheindenterandthereforeisatechnologicaltest.Itisrecognizedthat….認(rèn)出,識別,考慮(認(rèn)識)到somesourcesmaintain:一些資料(文件)

Itiswellknownthatothermechanicalpropertiesvarysignificantlywithrateofloading,temperature,geometryofnotchinimpacttesting,andthesizeandgeometryofthetestspecimen.

1.rateofloading:載荷大小2.geometryofnotchinimpacttesting:

試驗(yàn)中缺口的幾何形狀Furthermore,sincereportedtestvaluesofmaterialpropertiesarestatisticalaverages,acommercialmaterialfrequentlyhasatolerancebandof±5percentormoredeviationfrom

agivenpublishedvalue.1.reportedtestvalues:所報(bào)道的測量值2.statisticalaverages:統(tǒng)計(jì)平均值3.commercialmaterial:商用材料4.toleranceband:公差帶5.deviationfrom:與….的偏差6.agivenpublishedvalue:某個(gè)公布的值Thepropertiesofmaterialsaresometimesreferredtoasstructuresensitive,ascomparedtostructure-insensitiveproperties.

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

1.electricalandthermalconductivity:導(dǎo)熱性與導(dǎo)電性2.specificheat:比熱specificweight:比重

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……Furthermore,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….Mechanicalpropertiessuchasyieldstrength,impactstrength,hardness,creepandfatigueresistancearestronglystructure-sensitive,i.e.,theydependuponthearrangementoftheatomsinthecrystallatticeandonanyimperfectionsinthatarrangement,whereasthephysicalpropertiesarelessstructure-sensitive.

arrangementoftheatoms:原子排列Theseincludeelectrical,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(jié)構(gòu)鍵Betweentheconductorswithhighelectronmobilityandtheinsulatorswithnofreeelectrons,precisecontroloftheatomicarchitecturehascreatedsemiconductorsthatcanhaveaplannedmodificationoftheirelectronmobility.

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

1.bondingforces:結(jié)合力2.aggregationsofatoms:原子團(tuán)3.intermsof:用….語言來….專業(yè)英語的特點(diǎn)專業(yè)英語（specifiedEnglish）是在自然科學(xué)和工程技術(shù)的專業(yè)領(lǐng)域中使用的一種英語文體。它是在專業(yè)技術(shù)的不斷發(fā)展中逐漸形成并與專業(yè)技術(shù)同步發(fā)展的。由于專業(yè)技術(shù)的要求語言表述能客觀、嚴(yán)謹(jǐn)?shù)胤从晨茖W(xué)研究的內(nèi)容，所以，專業(yè)英語的特點(diǎn)，除了包含一些實(shí)驗(yàn)數(shù)據(jù)、公式推導(dǎo)和數(shù)學(xué)符號以外，在詞匯含義、語法結(jié)構(gòu)、句型使用和修辭手法等方面與日常英語、文學(xué)英語有不同的特點(diǎn)。這誠如著名科學(xué)家錢三強(qiáng)指出的：專業(yè)英語“無論在語法結(jié)構(gòu)或詞匯方面都逐漸形成它特有的習(xí)慣用法、特點(diǎn)與規(guī)律”。不學(xué)習(xí)和掌握這些特點(diǎn)與規(guī)律，就很難搞好專業(yè)英語的閱讀、翻譯和寫作。為了掌握這些特點(diǎn)和規(guī)律，本章及下一章節(jié)將主要介紹專業(yè)英語的語法特點(diǎn)和詞匯特點(diǎn)。一．專業(yè)英語的語法特點(diǎn)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(gè)顯著的特點(diǎn)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(yùn)動(dòng)的地方,步進(jìn)電機(jī)都非常有用。他們廣泛用于機(jī)器人技術(shù),打印機(jī),繪圖儀和計(jì)算機(jī)磁盤驅(qū)動(dòng)器，這些需要精確的定位或速度。2．被動(dòng)語態(tài)(PassiveVoice)

由于專業(yè)英語文獻(xiàn)側(cè)重?cái)⑹潞屯评恚愂龅膶ο笫强陀^事物。讀者重視的是作者的觀點(diǎn)和發(fā)明的內(nèi)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(dòng)語態(tài)。專業(yè)英語中的被動(dòng)語句不一定要說出行為主體，特別當(dāng)行為主體是人時(shí)。但有時(shí)也用“by”引出行為者。這些行為者除了人、機(jī)構(gòu)、物質(zhì)以外，還包括完成該動(dòng)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(dòng)詞動(dòng)詞非謂語形式有：動(dòng)名詞、分詞、動(dòng)詞不定式及它們的復(fù)合結(jié)構(gòu)。專業(yè)英語中，動(dòng)詞的非謂語形式應(yīng)用廣泛，這是因?yàn)閷I(yè)英語要求準(zhǔn)確、精煉，而動(dòng)詞的非謂語形式可以很好地實(shí)現(xiàn)這些要求。比如采用這一形式能用擴(kuò)展的成分對所修飾的詞進(jìn)行嚴(yán)格的說明和限定。其中每一個(gè)分詞定語都能代替一個(gè)從句，從而可使很長的句子勻稱,避免復(fù)雜的主從符合結(jié)構(gòu)，并省略動(dòng)詞時(shí)態(tài)的配合，使句子即不累贅又語意明確。

3.1分詞的使用在專業(yè)英語中，分詞短語被大量地用作定語、狀語和獨(dú)立分詞結(jié)構(gòu)，取代被動(dòng)態(tài)或主動(dòng)態(tài)的關(guān)系從句，使句子結(jié)構(gòu)得到簡化。例如：1.Rammers

drivenbycompressedaircanincreasetheproductionrates.壓縮空氣驅(qū)動(dòng)的舂砂器可以提高生產(chǎn)效率。2.Originallydesignedforrapid,automaticproductionofscrewsand

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

分詞獨(dú)立結(jié)構(gòu)前加with(without)變成起狀語作用的介詞短語，用于當(dāng)分詞的邏輯主語與句子主語不一致時(shí)。4.Intheheatexchangerofblastfurnacetheairflowsthroughtheoutsidepipe,thegasthroughtheinsidepipe,withheatexchangetakingplacethroughthewall.在高爐熱交換器中，空氣流過外管，燃?xì)饬鬟^內(nèi)管，熱交換通過管壁進(jìn)行。

3.2動(dòng)名詞的使用動(dòng)名詞構(gòu)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(yīng)用。例如：

Inredesigninganexperimentalpartforproduction,economicaltolerancesshouldbeused.為了生產(chǎn)而重新設(shè)計(jì)試件時(shí),必須使用經(jīng)濟(jì)公差。3.3不定式的使用不定式在專業(yè)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(jié)構(gòu)簡練。例如：1.Toinsuremanufacturequalityofelectrodes,theAmericanWeldingSocietyhassetupcertainrequirementsforelectrodes.為了確保電極的制造質(zhì)量，美國焊接學(xué)會規(guī)定了電極必須具備的一些條件。2.Thereishighrequirementofskillincarryingoutthisoperationto

produceproductswithhighperformances.進(jìn)行這項(xiàng)操作時(shí)需要很高的技巧，以生產(chǎn)出具有高性能的產(chǎn)品。4.名詞化結(jié)構(gòu)“表示動(dòng)作意義的名詞＋of＋名詞＋修飾語”叫做名詞化結(jié)構(gòu)。名詞化結(jié)構(gòu)具有文字明了、用詞簡潔、結(jié)構(gòu)緊湊、表意客觀、信息容量大等特點(diǎn)，在專業(yè)英語中經(jīng)常用它代替主、謂結(jié)構(gòu)作各種句子成分，使句子結(jié)構(gòu)簡化。例如:用普通英語表達(dá)這樣一句話：Theultrasonicmetalinspectionistoapplyultrasonicvibrationstomaterialswithelasticpropertiesandtoobservetheresultingactionofthevibrationsinthematerials.用名詞化結(jié)構(gòu)如下表述：Theultrasonicmetalinspectionistheapplicationofultrasonicvibrationstomaterialswithelasticpropertiesandtheobservationoftheresultingactionofthevibrationsinthematerials.金屬超聲波探傷是將超聲振動(dòng)施于具有彈性的材料，并觀察振動(dòng)在材料中產(chǎn)生的作用。二．專業(yè)英語的詞匯特點(diǎn)專業(yè)英語詞匯的組成專業(yè)技術(shù)詞匯：polymerization聚合作用diathermometer熱阻測定儀mechatronics機(jī)電一體化，機(jī)械電子學(xué)lathe車床半專業(yè)技術(shù)詞匯：power力量,權(quán)力（日常英語）動(dòng)力（機(jī)械專業(yè)）電力（電力專業(yè)）冪(數(shù)學(xué)專業(yè)）功率（物理專業(yè)）爆發(fā)力（體育專業(yè)）構(gòu)詞法

英語的構(gòu)詞法包括轉(zhuǎn)化、合成、派生三種形式。轉(zhuǎn)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(fù)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不精確詞匯縮略首字詞縮略:它是由原詞組的每個(gè)詞首字母組成，在閱讀中首字詞要逐字母讀.例如：

NC數(shù)控AC自適應(yīng)控制PLC可編程控制器AIEEAmericanInstituteofElectrical(Electronic)Engineers美國電氣（電子）工程師學(xué)會首字詞拼音:把一個(gè)詞組中的首字母拼湊成一個(gè)詞.例如laser—lightamplificationbystimulatedemissionofradiation激光ROM——readonlymemory只讀存儲器AIDS——acquiredimmunedeficiencysyndrome愛滋病節(jié)略詞:某些詞使用頻率高,為了方便，在發(fā)展過程逐漸用它們的前幾個(gè)字母來表示。例如：

ref.——reference參考文獻(xiàn)lab.——laboratory實(shí)驗(yàn)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(fù)合詞的各個(gè)詞中各抽取一或兩個(gè)詞綴相拼合。例如：

transeiver(transistor＋receiver)收發(fā)機(jī)mechatronics(mechanics＋electronics)機(jī)電一體化distinguish區(qū)別；區(qū)分distort:變形bymeansof:借助于permanent:永久的coefficient:系數(shù)steelmill:鋼廠expansion：膨脹roll:軋錕reactto:對….起作用;對….的反應(yīng)crack:裂開,裂紋,破裂inconnectionwith:與…..有關(guān)gradually:逐漸地fivebroadcategories:五大類elasticity:彈性ductility:延展性toughness:韌性elevator:升降機(jī)cable:電纜beam:橫梁penetration:壓痕,凹痕abrasion:磨損elongate:延長，伸長Lesson2MetalsandFerrousMetalsferrousa.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(shù)量的Steelandcastironarethemostcommonferrousmetalsingeneraluse.

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.byfar:迄今Itistheamountofcarbonpresentwhichlargelydeterminesthemaximumhardnessobtainable.

Itis+強(qiáng)調(diào)部分+which……..Thehigherthecarboncontent,thehigherthetensilestrengthandthegreaterthehardnesstowhichthesteelmaybeheat-treated.

→Thesteelmaybeheat-treatedtothehardness.…….partsrequiringagreatdealofforming.

agreatdealof……:大量Medium-carbonsteelsareusedforforgingsandotherapplicationswhereincreasedstrengthandacertainamountofductilityarenecessary.Alloysteelshavespecialpropertiesdeterminedbythemixtureandtheamountofmetalsadded.mixture:混合物→金屬種類Tothemetallurgistwhoworksinmetalminingandmanufacturing,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.

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

usedtocutandformmetals.

Toolsteelswithcertainalloyingelementsaredesignedfor

specificuses.bedesignedto…..設(shè)計(jì)成能(做),用來…,目的是使…bedesignedfor…..用做…用途;為….而設(shè)計(jì)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

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

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

Asthesteelpassesthroughthelastrollers,hotwaterissprayedoverit,formingabluishscale.abluishscale淡藍(lán)色的氧化層Thissteelisfairlyuniforminqualityandisusedformanydifferentkindsofparts.uniforma.均勻

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

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

themostcommon(way):最常見的方法resultsin:導(dǎo)致,引起,產(chǎn)生whatiscalledcold-workedsteel:所謂的冷作鋼

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

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Lesson2MetalsandFerrousMetalsDrill-rodbarsaregenerallymadein3-ftlengthsandcome

inround,hexagonal,andsquareshapes.Castironisusedfortheheavypartsofmanymachines.Castironislowincostandwearswell.Itisverybrittle,however,andcannotbehammeredorformed.hammeredorformed.鍛壓成形Thebasickindsofcastironarewhiteiron,grayiron,andmalleableiron.Malleableironisaparticularkindofcastiron,mademoremalleablebyanannealingprocedure.anannealingprocedure退火工序Malleable-ironcastingsarenotsobrittleorhard.Theycanstandagreatdealhammering.Manyplumbingfixturesaremadeofmalleableiron.plumbingfixtures:管接頭Nodularironisakindofcastironthatisevenbetterforwithstandingshocks,blows,andjerks.nodulariron球墨鑄鐵Lesson3Gearsspur(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(dòng)力傳動(dòng)齒輪Thismeansthatonthepitchcirclesofamatingpair,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.Helicalgearshavecertainadvantages;forexample,whenconnectingparallelshaftstheyhaveahigherloadcarryingcapacitythanspurgearswiththesametoothnumbersandcutwiththesamecutter.withthesametoothnumbersspurgearscutwiththesamecutter.Becauseoftheoverlappingactionoftheteeth,theyaresmootherinactionandcanoperateathigherpitch-linevelocitiesthanspurgears.

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

continuous-toothherringbonevariety:連續(xù)人字形adouble-helicalgear:雙斜齒輪Double-helicalgearsarewellsuitedfortheefficienttransmissionofpowerathighspeeds.Helicalgearscanalsobeusedtoconnectnonparallel,non-intersectingshaftsatanyangletooneanother.Ninetydegreesisthecommonestangleatwhichsuchgearsareused.最常用的角度為90·wormandwormgears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(jié)果就形成一個(gè)柱形蝸桿和蝸輪Wormgearsprovidethesimplestmeansofobtaininglargeratiosinasinglepair.

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

anadditionalslidingmovement附加滑動(dòng)Becauseoftheirsimilarity,theefficiencyofawormandgeardependsonthesamefactorsastheefficiencyofascrew.Single-threadswormsoflargediameterhavesmallleadanglesandlowefficiencies.

single-threadsworm單頭蝸桿multiple-threadworm多頭蝸桿leadangle導(dǎo)角Fortransmittingrotarymotionandtorquearoundcorners,bevelgearsarecommonlyused.….transmittingrotarymotionandtorquearoundcorners…傳遞旋轉(zhuǎn)運(yùn)動(dòng)以及繞著一個(gè)角度傳遞扭距….Theconnectedshafts,whoseaxeswouldintersectifextended,areusuallybutnotnecessarilyatrightanglestooneanother.

axis(單數(shù)),axes(復(fù)數(shù))notnecessarily不一定tooneanother,totheother相互Whenadaptedforshaftsthatdonotintersect,spiralbevelgearsarecalledhypoidgears.

When(spiralbevelgears)adaptedforshafts…..Thepitchsurfacesofthesegearsarenotrollingcones,andtheratiooftheirmeandiametersisnotequaltothespeedratio.Consequently,thepinionmayhavefewteethandbemadeaslargeasnecessarytocarrytheload.Theprofilesoftheteethonbevelgearsarenotinvolutes;theyareofsuchashapethatthetoolsforcuttingtheteethareeasiertomakeandmaintainthaninvolutecuttingtools.

Sincebevelgearscomeinpairs,aslongastheyareconjugatetooneanothertheyneednotbeconjugatetoothergearswithdifferenttoothnumbers.CommentonExerciseoneOnematerialcanoftenbedistinguishedfromanotherbymeansofphysicalproperties,suchascolor,density,specificheat,coefficientofthermalexpansion,thermalandelectricalconductivity,magneticproperties,andmeltingpoint.一種材料與另一種材料的區(qū)別經(jīng)?？梢酝ㄟ^其物理性能，如…….一種材料經(jīng)?？梢酝ㄟ^其物理性能與另一種材料區(qū)別開來,如…..熱膨脹系數(shù),導(dǎo)熱性和導(dǎo)電性Someofthese,forexamplethermalconductivity,electricalconductivity,anddensity,maybeofprimeimportanceinselectingmaterialforcertainspecificuses.其中一些性能,如:………In+v.-ing:在…..時(shí)候………….在為某些特定用途選擇材料的時(shí)候……..Thosepropertiesthatdescribehowamaterialreacttomechanicalusageareoftenmoreimportanttotheengineerinselectingmaterialsinconnectionwithdesign.描述材料如何對機(jī)械使用起反應(yīng)的

那些性能對…..更重要.在選擇與設(shè)計(jì)有關(guān)的材料時(shí),….Thesemechanicalpropertiesrelateto

howthematerialwillreacttothevariousloadingduringservice.材料在使用中(如何)對各種載荷的反應(yīng)

relateto:與….有關(guān)

Mechanicalpropertiesarethecharacteristicresponsesofamaterialtoappliedforces.responsesofAtoB-----ArespondtoBA對B的反應(yīng)appliedforces外力thecharacteristicresponses特性的反應(yīng)

Thesepropertiesfallintofivebroadcategories:strength,hardness,elasticity,ductility,andtoughness.fallinto:變(分)成;分解fivebroad(main,major)categories:五大類1.Strengthistheabilityofamaterialwhichresistsa