机械专业英语(第三版)771

Unit1TEXTLEARNTOSPEAKNEWWORDSANDEXPRESSIONSNOTESEXERCISESREADINGMATERIALPROFESSIONALWORDSANDPHRASESTEXTBroadlyspeaking,twokindsofrelativemotionmustbeprovidedbyamachinetool—theprimarymotionandthefeedmotion．Combinationofthesetwomotionswillleadtoachipremovalandthecreationofmachinedsurfacewithdesiredgeometry.Asarule,theprimarymotionabsorbsmostoftotalpowerwhichisrequiredtoperformamachiningoperation.Thefeedmotionmayproceedbystepsorcontinuouslyandabsorbasmallproportionofthetotalpower．PrimaryMotionandFeedMotionTurningmeansmachiningapieceofrotatingmetalbypressingahardenedcuttingtoolagainstit.Theworkisgiventheprimarymotionwhilethetoolisfedcontinuously.Theprocessofplaningandshapingisremovingmetalinaseriesofstraightcuts.Inplaning,theworkisgivenalinearmotionwhilethetoolremainsmotionlessduringthecuttingstrokeandisprovidedwithalateralfeedingmovementduringthereturnstroke.Inthecaseoftheshaper,thekinematicrelationshipbetweenworkandtoolisreversed;however,thecuttingactionprincipleisthesame.Drillingconsistsofrotatingacuttingtoolandadvancingthetoolalongitsownaxisintoastationarywork-piecetoproducearoundhole.Ofthetwofunctions，advancingthetoolalongitsaxisisthemajorconsiderationinthedesignofdrillingmachines.Rotatingthedrillis,bycomparison,asimplematter.

LEARNTOSPEAKJohn： Howdoyoudo!MynameisJohn.MissLi: Howdoyoudo!John： Arethereanyvacanciesinyourfactory?MissLi: Yes.Weneedsomenewworkers.Whatsubjectwasyourmajor?John： Imajoredinmechanicalmanufacturing,andIthinkIamgoodatoperatingmillingmachine.MissLi: Whatsortofjobdoyouliketodo?John： Iwouldliketobemillingworker.IthinkIcandomybesttoit.MissLi: Great!Whattimecanyoustarttowork?John： Anytime.MissLi: Verynice.Howmuchdoyouexpectinsalary?

John： 800yuan.MissLi: OK!Pleasefillinthisform.Ifanythingturns,I’llcontactwithyou.John： Thankyou!MissLi: You’rewelcome.

NEWWORDSANDEXPRESSIONSprimarymotion 主运动broadlyspeaking 概括地讲leadto 导致asarule 通常，照例bysteps 逐步地asmallproportionof 小部分linearmotion 线性运动lateralfeedingmovement 横向进给运动returnstoke 返回行程take…intoconsideration 对……加以考虑，考虑到bycomparison 比较起来NOTES1. Broadlyspeaking，twokindsofrelativemotionmustbeprovidedbyamachinetool— the primarymotionandthefeedmotion．概括地讲，机床必须提供两种相对运动——主运动与进给运动。

“Broadlyspeaking”是插入语，这里可译为“一般讲”。破折号后面的内容“theprimarymotionandthefeedmotion”实际上是解释“twokindsofrelativemotion”，不要因为破折号在“amachinetool”后面，就误以为“theprimarymotionandthefeedmotion”是解释“amachinetool”的。在英语中，很多场合使用被动语态，宾语放在了前面，而主语放在了后面，造成了中心词与解释中心词的内容从形式上看被分开了，因而在翻译时要特别引起注意。

2. Asarule，theprimarymotionabsorbsmostoftotalpowerwhichisrequiredtoperformamachiningoperation.通常，主运动要消耗切削加工所需要的总功率中的大部分。

“Asarule”作为一个整体，其含义为“通常”。“which”引导的是定语从句，用来进一步解释“totalpower”是用来干什么的。

3.Theworkisgiventheprimarymotionwhilethetoolisfedcontinuously.

车削时，工件获得主运动，而刀具则获得连续进给运动。

“begiven”(被给)常可译成“得到”、“获得”。例如：

Iamgivenabook.

我得到一本书。

Inturning,theworkisgiventheprimarymotion.

车削时，工件获得主运动。

4. Ofthetwofunctions，advancingthetoolalongitsaxisisthemajorconsiderationinthedesignofdrillingmachines.

在加工出一个圆孔的两种功用中，使钻头沿自身的轴线进给是设计钻床时主要考虑的问题。

“Of”放在句首表示：“在…中”，例如：

Ofallmachinetools,thelatheisthemostcommonone.

在所有的机床中，车床是最普通的一种。

Ofallmetals,steelisthemostwidelyusedinengineering.

在所有的金属中，钢在工程上用得最普遍。EXERCISESDiscussthefollowingquestionsinEnglish:Whatistheprimarymotion?Whatisthefeedmotion?Whatisturning?Whatisdrilling?EXERCISESUseEnglishreplaceChineseoruseChinesereplaceEnglish:相对运动加工表面机械制造DesiredgeometryAmachiningoperationRotatingacuttingtoolREADINGMATERIAL

PowerintheWorkshop

Theprocessesofcuttingmetalgenerallyrequiresomepowersothattheapplicationofpowertoworkshopprocessesisimportant．Energyisrequiredinvariousformsbymachinetools，forexample，reciprocatingmotiontoaplanertable，longitudinalfeedtoalathecarriage,rotationalmotiontoadrill，etc.,butitisnearlyalwayssuppliedtothemachineintheformofrotationalenergyatthepulley．Oneofthefunctionsofthemachineistoconverttherotationalenergyintotherequiredform．Energyissuppliedtomostofourworkshopsintheformofelectricity，anditisconvertedtorotationalenergybymeansofanelectricmotor.Earlymachinetoolsweredrivenbyareciprocatingsteamenginethroughasystemofpulleys,belts，andclutches．Usually，asinglesteamengineprovidedthepowerforseveralmachinetoolsintheworkshop．Later,asingleelectricmotorreplacedthesteamenginetodriveagroupofmachinetools．Inmodernworkshops，mostofthemachinetoolsareprovidedwithindividualmotordrive．Eachmachinehasitsownelectricmotorwhichdrivesthroughbelt，gearing,orbydirectcoupling．PROFESSIONALWORDSANDPHRASESnearto接近supply…with(for,to)…

把…供给…intheformof以…形式convert…into把…变成steamengine蒸汽机bymeansof依靠Unit2TEXTLEARNTOSPEAKNEWWORDSANDEXPRESSIONSNOTES

EXERCISES

READINGMATERIALPROFESSIONALWORDSANDPHRASESTEXT Three-jawChuckandFour-jawChuck

Inlathework,work-piecesareheldeitherbetweencentersorinachuck.Sometimesthework-piecesareheldinachuckatoneendandsupportedbyacenterattheother.

Severaltypesofchucksareavailableinmetalmachining.Thethree-jawuniversalandfour-jawindependenttypesaremostcommonlyusedinlathework.Theyaredesignedtoholdandrevolvethework-pieces.

Thethree-jawuniversalchuckisusedtoholdcylindricalwork.Thechuckingisdonequickly,asthethreejawsmoveinandouttogetherandautomaticallycenterthework.Thistypeofchuckisaccuratewhennew.Itlosesitsaccuracyasthejawsbecomeworn.

Toholdwork-piecesofirregularshapes,weoftenuseafour-jawchuckinsteadofathree-jawchuck.Itsaccuracyisnotaffectedbywear,becauseeachjawcanbeadjustedindependently.Thejawsdonotmovesimultaneously.

LEARNTOSPEAKMr.Cheng：Goodmorning,Mr.Zhang.Mr.Zhang：Goodmorning,Mr.Cheng.Mr.Cheng：Couldyouhelpme?Mr.Zhang：WhatcanIdoforyou?Mr.Cheng：Thethree-jawuniversalchuckdoesnotworkwell,andIcan’tmakeitlikebefore.Perhaps,youcanfixit.Mr.Zhang：Letmetry.(Afterawhile)That’snottoodifficulttome.Mr.Cheng：What’swrongwithit?

Mr.Zhang：Thejawshavebeencorrosive.Mr.Cheng：Oh,Isee.Mr.Zhang：Nowitworksverywell,butyoumustoftenoilitbeforeusing.Mr.Cheng：Iknowitnow.Manythanks.Mr.Zhang：It’sapleasure.three-jaw(universal)chuck三爪(万能)卡盘four-jaw(independent)chuck四爪(分动)卡盘either…or… 或……或……，不论……还是……

NOTES1．Inlathework,work-piecesareheldeitherbetweencentersorinachuck.车削加工时，工件可夹持在两顶尖之间或卡盘内。

“either…or…”是连接词，可译为：或……或……。

有些词，如句中的“in”，它既可作介词，也可作副词，但用作副词时后面没有受支配的名词。很明显，句中的两个“in”均为介词。例如：Theshaftsmustrestinbearings.轴必须装在轴承里。(介词)Thethreejawsmoveintogether．三个爪一起向内移动。(副词)Comein，please．请进来。(副词)

2.Thethree-jawuniversalandfour-jawindependenttypesaremostcommonlyusedinlathework.

三爪卡盘与四爪卡盘在车削加工中使用最为广泛。

“mostcommonly”是副词的最高级形式，意思是“最广泛地”，“areused”是被动语态，意思是“被使用”。

3.Thefour-jawchuckisdesignedtoholdworkpiecesofirregularshapes，

四爪卡盘设计用来夹持不规则形状的工件。

“bedesigned+toV”这种结构中的design有时不能简单地译成“设计”，而要译成“设计用来”。又如：

Theplanerisdesignedtomachinelargeworkpieces．

龙门刨床设计用来加工大工件。4．Thistypeofchuckisaccuratewhennew．

句中when后省略了itis,即:…whenitisnew．三爪卡盘在新的时候很精密。5．Itlosesitsaccuracyasthejawsbecomeworn．当卡爪磨损时，卡盘便会失去其精度。

句中become是连系动词，worn是wear的V-ed2形式，象形容词一样在become后作补语。

EXERCISES1．DiscussthefollowingquestionsinEnglish:(1) Howdoesthethree-jaw(universal)chuckwork?(2) Howdoesthefour-jaw(independent)chuckwork?(3) Whatarethedifferencesbetweenthethree-jaw(universal)chuckandthefour-jaw(independent)chuck?

2．UseEnglishforreplacingChineseoruseChineseforreplacingEnglish.

(1)车床

(2)顶尖

(3)工件

(4) Cylindricalwork

(5) Loseitsaccuracy

(6) Irregularshape

READINGMATERIAL

PlainCenter-typeCylindricalGrinder

Plaincenter-typecylindricalgrinderisusedtogrindtheoutsideofcylindricalparts．

Thetablethatisfastenedtothebedofthismachineiscapableofback-and-forth(reciprocating)movementandcanalsobeswiveledabout10degreesoneithersideofthecenterline.Boththeheadstockandthefootstockaremountedonthistable．Thework-pieceisheldbetweencentersandmusthavecenterholes．Adogisusedtodrivethework-piece．Thegrindingwheelismountedonaspindle．Itcanbemovedtoandfromthework-piece．Boththegrindingwheelandthework-piecerotateduringthemachiningoperations.Thegrindingwheelturnsrapidly—825to1,250rpm．Thework-pieceturnsatamuchslowerrate—100to400rpm．Also，thesurfacesofthegrindingwheelandthework-piecemoveinoppositedirectionsattheirlineofcontact．Thetableisusedtomovethework-pieceacrossthefrontofthewheel．Fig.2Operationofacenter-typegrindercapableof 能……的，可以……的centerline 中心线attherateof 按……速率(比率)inoppositedirection 朝相反方向inthedirectionof… 朝……方向rpm=revolutionperminute转/分

TEXT

LEARNTOSPEAKNEWWORDSANDEXPRESSIONSNOTES

EXERCISES

READINGMATERIALPROFESSIONALWORDSANDPHRASESUnit3TEXT ConventionalMillingVSClimbMillingTherearetwomethodsofmilling，i.e.conventionalorupmillingandclimbordownmilling．

Inconventionalmilling，thecutterrotatesagainstthedirectionoffeed．Thismethodhaslongbeenregardedastheonlypracticalwaytousemillingcutters.Notlongago,climbmillingwasrecognizedasanacceptablemethodofoperation.Inclimbmilling，thecutterrotatesinthedirectionoffeed．Theadvantagesofclimbmillingareasfollows:(1) Feedcanfrequentlybedoubledoverconventionalmilling.(2) Metalscanberemovedfastwithoutvibration.(3) Finishcanbeconsiderablyimproved．

(4)

Toollifemaybeprolonged．Fig.3Twomethodsofmilling(a) Conventional(up)milling；(b) Climb(down)milling

Bothconventionalmillingandclimbmillingarebeingemployed，becauseclimbmillingisnotapplicabletoanymillingjob．Climbmillingcanbeappliedonlywhenthemachineisofaheavy-dutytypeandbacklashhasbeeneliminated．Climbmillingisnotrecommendedforuseoncastironorforgings.Therefore,conventionalmillingremainsusefulinmillingwork． LEARNTOSPEAKMr.Liu: Goodafternoon,Mr.Xiong.Mr.Xiong: Goodafternoon,Mr.Liu.Mr.Liu: Ihavesometroublewithheattreatment.Couldyoutellme?Mr.Xiong: Whataretheproblems?Mr.Liu: Doyouknowwhatisthefunctionofheattreatment?Mr.Xiong: Yes.IthinkIsee.Heattreatmentisamethodbywhichtheheattreatercanchangethephysicalpropertiesofamaterial.Mr.Liu: Howmanytypesofheattreatmentarethere?

Mr.Xiong: Therearethreemainoperationsintheheattreatmentofsteel:hardening,temperingandannealing.

Mr.Liu: Howishardeningoperationdone?

Mr.Xiong: Thehardeningoperationconsistsofheatingthesteelaboveitscriticalrangeandthenquenchingitinasuitablemediumsuchaswater,brine,oil,orsomeotherliquid.Havingbeenhardened,themetalmustbegivenatemperingtreatmentwhichconsistsofreheatingthehardenedsteeltoatemperaturebelowthecriticalrange,thusproducingtherequiredphysicalproperties.Mr.Liu: Andwhatiscriticaltemperature?Mr.Xiong: Itisthetemperatureatwhichacertainchangetakesplaceinthephysical  conditionofthesteel.Mr.Liu: Whatisthepurposeofannealing?Mr.Xiong: Itcansoftenawork-pieceandrelieveinternalstressesproducedbymachining.Mr.Liu: Thankyoutellingmeaboutthese.Mr.Xiong: I’mgladtohavebeenofsomeservice.

conventionalmilling逆铣climbmilling 顺铣upmilling 逆铣downmilling 顺铣regard…as 认为……是inasimilarway 同样inthisway 这样berecognizedas 被认为是toollife 刀具寿命，刀具耐用度heavy-duty 重型的castiron 铸铁asfollows 如下heattreatment 热处理heattreater 热处理工作者physicalpropertiesofamaterial 材料的物理性能physicalpropertiesofamaterial 材料的物理性能hardenedsteel 淬硬钢criticalrange 临界点internalstress 内应力criticaltemperature 临界温度

1．Therearetwomethodsofmilling，i.e.conventionalorupmillingandclimbordownmilling．铣削方法有两种：逆铣(即反向铣削)与顺铣(即同向铣削)。

“or”可以表示“即”的意义，引出一个同位语。例如:Thecuttingspeedmustbereducedinthefirst,orroughingcut．在初切(即粗切)时，切削速度必须降低。

2．Inconventionalmilling，thecutterrotatesagainstthedirectionoffeed．逆铣时，铣刀旋转方向与进给方向相反。

“againstthedirectionof…”的含义是“与……的方向相反”。NOTES

3．Thismethodhaslongbeenregardedastheonlypracticalwaytousemillingcutters.这种铣削方法长期以来一直被认为是使用铣刀的唯一切实可行的方法。

tov.短语可以用来修饰名词。这里的“touse”用来修饰前面的“way”。又例如：

Conventionalmillingisnottheonlywaytousemillingcutters.逆铣不是使用铣刀的唯一方法。

4．Inclimbmilling，thecutterrotatesinthedirectionoffeed．顺铣时，铣刀顺着进给方向旋转。

“inthedirectionof…”的含义是“沿着……的方向”。

5．Climbmillingcanbeappliedonlywhenthemachineisofaheavy-dutytypeandbacklashhasbeeneliminated．只有在机床具有相当的刚性且间隙也已消除的情况下，才能使用顺铣。

“be+of+抽象名词”可以表示“具有”或“属于”等意义。句中“isofaheavy-dutytype”的含义是“是重型的(刚性好的)”。再看下面两个句子：

Thesesupportsareofgreatrigidity.这些支架具有很大的刚性。

Thismachineisnotofaheavy-dutytype.这台机器不属于重型的。

EXERCISES1．DiscussthefollowingquestionsinEnglish:(1) Whatistheconventionalmilling?(2) Whatistheclimbmilling?(3) Whatarethedifferencesbetweentheconventionalmillingandtheclimbmilling?2．UseEnglishforreplacingChineseoruseChineseforreplacingEnglish.(1)进给方向(2)铣刀(3)粗切(4) Methodofoperation(5) Thedirectionoffeed(6) PracticalwayREADINGMATERIAL RoughingandFinishingCut

Itiscustomary，inshoppractice,totakeatleasttwocutsmakeajobsmoothandaccurate．

Thefirstcuttotakeistoremoveexcessmetalfromthesurfaceofthework-pieceasrapidlyaspossible．Todothis，thecutshouldbeasdeepandthefeedascoarseasthework-pieceandthemachinetoolwillstand．Cuttingspeedshouldbeadjusteddownward,ifnecessary，topermitthis．Thefirst，orroughing，cutshouldbedeepenoughtosizethejob,withasuitableallowanceforafinishingcut,inonepasswheneverpossible．

Whenyouintendtoadjustthecuttingspeedorthefeedtoincreasetherateoftheproductiononamachinetool,itisadvisabletoincreasethefeedeventhoughthespeedmustbereducedsomewhat．Toincreasethefeedratherthanthecuttingspeedwillincreaseproductionwithoutacorrespondingincreaseinpowerconsumptionandtoolwear．

Thepurposeofthelast，orfinishing，cutistofinishawork-piecesmoothandaccurate.Toaccomplishthis，thecutshouldbeshallowandthefeedfineandcuttingspeedshouldbeincreasedmuchhigherthanfortheroughingcut.

Roughingandfinishingoperationsareusuallynotperformedonthesamemachine.Itisacommonpractice，forexample，torough-turnwork-piecesonalathe,andtofinishthemonagrinder．Somemachines,abrasivemachinesforinstance,areknowntoperformbothroughingandfinishingoperations．PROFESSIONALWORDSANDPHRASESatleast 至少evenif 即使eventhough即使ratherthan而不atlast 终于roughturn 粗车Unit4TEXTLEARNTOSPEAKNEWWORDSANDPHRASESNOTESEXERCISESREADINGMATERIALPROFESSIONALWORDSANDPHRASESTEXT KindsofSteel

Therearetwogeneralkindsofsteels:carbonsteelandalloysteel.Carbonsteelcontainsonlyironandcarbon,whilealloysteelcontainssomeother“alloyingelements”suchasnickel,chromium,manganese,molybdenum,tungsten,vanadium,etc.

1．Carbonsteels

(1) Lowcarbonsteelcontainingfrom0.05to0.15percentcarbon;thissteelisalsoknownasmachinesteel.

(2) Mediumcarbonsteelcontainingfrom0.15to0.60percentcarbon.

(3) Highcarbonsteelcontainingfrom0.6to1.50percentcarbon;thissteelissometimescalled“toolsteel”.

2．Alloysteels

(1) Specialalloysteel,suchasnickel,chromiumsteel;

(2) High-speedsteelalsoknownasself-hardeningsteel.

Carbonsteelsarethemostcommonsteelsusedinindustry.Thepropertiesofthesesteelsdependonlyonthepercentageofcarbontheycontain.Lowcarbonsteelsareverysoftandcanbeusedforboltsandformachinepartsthatdonotneedstrength.Mediumcarbonsteelsareabettergradeandstrongerthanlowcarbonsteels.Itisalsomoredifficulttocutthanlowcarbonsteels.Highcarbonsteelsmaybehardenedbyheatingittoacertaintemperatureandthenquicklycoolinginwater.Themorecarbonthesteelscontainsandthequickerthecoolingis,theharderitbecomes.Becauseofitshighstrengthandhardnessthisgradeofsteelmaybeusedfortoolsandworkingpartsofmachines.

Butforsomespecialuses,forexample,forgears,bearings,springs,shaftsandwire,carbonsteelscannotbealwaysusedbecausetheyhavenopropertiesneededfortheseparts.

Somespecialalloysteelsshouldbeusedforsuchpartsbecausethealloyingelementsmakethemtougher,stronger,orharderthancarbonsteels.Somealloyingelementscausesteeltoresistcorrosion,andsuchsteelsarecalledstainlesssteels.Stainlesssteelscontainahighpercentageofchromium.Chromiumalsomakessteelharder.Nickelisusedinsteeltoincreasestrengthandtoughness.Somealloyingelements(suchaschromiumandtungsten)makethegrainofsteelfiner,thusincreasingthehardnessandstrengthofsteel,becausethefinerthegrainis,thestrongerthesteelbecomes.

Heat-resistantsteelismadebyaddingsometungstenandmolybdenum,whilemanganeseincreasesthewearresistanceofsteel.Vanadiumsteelsresistcorrosionandcanstandshocksandvibration.

Toolsmadeofhigh-speedsteelcontainingtungsten,chromium,vanadium,andcarbon,maydotheworkatmuchhigherspeedsthancarbontoolsteels.

LEARNTOSPEAKMr.Yang: Morning!Mr.Smith: Morning!Mr.Yang: Doyouknowaboutthekindsofsteels?Mr.Smith: Yes,therearetwogeneralkindsofsteels:carbonsteelandalloysteel.Mr.Yang: Couldyoudescribeitindetail?Mr.Smith: OK.Carbonsteelcontainsonlyironandcarbon,whilealloysteelcontainssomeother“alloyingelements”suchasnickel,chromium,etc.

Mr.Yang: Whatcanthecarbonsteelbeusedfor?Mr.Smith: Thecarbonsteelcontainslow,mediumandhighcarbonsteel,andcanbeusedforbolts,toolsandworkingpartsofmachines.Mr.Yang:Then,whatcanthealloysteelbeusedfor?Mr.Smith: Alloysteelcanbeusedforgears,bearings,springsandwires,etc.Becausethealloyingelementsmakethemtougher,stronger,orharderthancarbonsteel.Mr.Yang: Howaboutthetoolswhichmadeofhighspeedsteel?Mr.Smith: Thetoolsmadeofhigh-speedsteelofalloysteelcontainingtungsten,chromium,vanadiumandcarbon,maydotheworkatmuchhigherspeedsthancarbontoolsteels.

NOTES

1.high-speedsteelalsoknownasself-hardeningsteel还有通称为自硬钢的高速钢“alsoknownasself-hardeningsteel”为分词短语作定语，修饰“high-speedsteel”。

高速钢是一种含有钨、铬、钒等合金元素的高合金工具钢，它可以在空气中自行淬硬，因而又称“self-hardeningsteel”，故又称做风钢。

2．Themorecarbonthesteelcontainsandthequickerthecoolingis,theharderitbecomes.钢的含碳量越高，冷却速度越快，钢就变得越硬。

“the+比较级…(从句)+the+比较级…(主句)”结构表示“越……越……”之意。

本句中的比较状语从句为“Themorecarbonthesteelcontainandthequickerthecoolingis”，主句为“theharderitbecomes”。句中第一个“the”和第二个“the”均为副词，分别引出两个并列的比较状语从句。在这种情况下，第一个“the”相当于“bysomuch”，第二个“the”相当于“bythatmuch”。

3．becausethealloyingelementsmakethemtougher,strongerorharderthancarbonsteels.Somealloyingelementscausesteeltoresistcorrosion,andsuchsteelarecalledstainlesssteels.因为合金元素能提高钢的韧性、强度和硬度(在碳钢的基础上)。有些合金元素能提高钢的耐蚀性，这种钢称做不锈钢。

句中的“make”和“cause”均为及物动词，它们的宾语分别为“them”和“steel”。宾语“them”的补足语是形容词比较级“tougher,stronger,harder”等，而宾语“steel”的补足语是不定式短语“toresistcorrosion”。“stainlesssteels”是主语“suchsteel”的补足语。

4．Toolsmadeofhigh-speedsteelcontainingtungsten,chromium,vanadiumandcarbon,maydotheworkatmuchhigherspeedsthancarbontoolsteels.用含有钨、铬、钒、碳的高速钢制成的刀具能以比碳素工具钢(制成的刀具)高得多的速度进行切削加工。

“madeofhigh-speedsteel”作为分词短语，修饰“Tools”，而“containingtungsten,chromium,chromium,vanadiumandcarbon”是另一分词短语作后置短语，修饰“high-speedsteel”。 EXERCISES1．DiscussthefollowingquestionsinEnglish:(1)Whatmethodsareavailableforimprovingthehardnessofhighcarbonsteel?(2)Whatarethemachinepartsmadeof,thatdonotneedstrength?(3)Howdothealloyingelementssuchaschromiumandtungstenincreasethehardnessandstrengthofsteel?

2．UseEnglishforreplacingChineseoruseChineseforreplacingEnglish. (1)碳钢和合金钢

(2)材料的性能

(3)高速钢

(4) heat-resistantsteel (5) self-hardeningsteel (6) nickelsteel3．Placea“T”aftersentencesthataretrueandan“F”afterthosethatarefalse.(1) Alloyshavingmorethan0.6%carbonarecalledhighcarbonsteels.()(2) Alloyscontaining0.15%(orless)carbonarecalledlowcarbonsteels.()(3) Highspeedsteelissometimescalledself-hardeningsteel.()(4) Thepropertiesofcarbonsteelsdependnotonlyonthepercentageofcarbontheycontain,butalsoonthealloyingelements.()(5) Steelscontainmorecarbonthancastirons.()(6) Lowcarbonsteelisharderthanhighcarbonsteel.()(7) Toolsmadeofhigh-speedsteeldotheworkatmuchlowerspeedsthancarbonsteels.()(8) Stainlesssteelscontainsomealloyingelementswhichcausesteelstoresistcorrosion.()

READINGMATERIAL

MechanicalPropertiesofMetals

Mechanicalpropertiesarethecharacteristicresponsesofamaterialtoappliedforces.Theknowledgeofmechanicalpropertiesofmaterialsisveryessentialinordertoconstructamechanicallysoundstructuresuchasabridgeontheriver.Mechanicalpropertiescanbedeterminedbyconductingexperimentaltestsonthematerialspecimen.Someimportantmechanicalpropertiesofmaterialsare:(1)Strength,(2)Stiffness,(3)Ductility,(4)Impactstrength,(5)Hardness,(6)Toughness.

Strength.StrengthorMechanicalStrengthofamaterialmaybedefinedastheabilityofthematerialtosustainloadswithoutunduedistortionorfailure.Materialshouldhaveadequatestrengthwhensubjectedtotension,compression,shear,bendingortorsionaspertheintendeduse.

Stiffness.Stiffnessistheabilityofamaterialorshapetoresistelasticdeflection.Foridenticalshapes,thestiffnessisproportionaltothemodulusofelasticity.

Ductility.Ductilityreferstothecapacityofamaterialtoundergodeformationundertensionwithoutruptureasinawiredrawingoperation.

Impactstrength.Itisthestrengthofamaterialwhensubjectedtohighratesofloading,usuallyinbending,tensionortorsion.TheamountofenergyrequiredtofracturethematerialbyasingleblowismeasuredbymeansofaCharpytest.

Hardness.Hardnessistheresistanceofamaterialtoplasticdeformationusuallybyindentation.However,thetermmayrefertostiffnessorrefertoresistancetoscratching,abrasionorcutting.TestssuchasVickers,BrinellandRockwellaregenerallyemployedtomeasurehardness.

Toughness.Toughnessreferstotheabilityofamaterialtowithstandbendingortheapplicationofshearstresseswithoutfracture.Fig.4Tensiletestspecimen(a) Specimenbeforepulling；(b) SpecimenafterpullingPROFESSIONALWORDSANDPHRASESbendingstrength 抗弯强度besubjectedto ……易受到……elasticdeflection 弹性(挠曲)变形modulusofelasticity 弹性模量wiredrawing 拉丝plasticdeformation 塑性变形singleblow 一击，一下子Charpyimpacttest (摆锤式)冲击试验Vickerstest 维氏硬度试验Brinelltest 布氏硬度试验Rockwelltest 洛氏硬度试验TEXTLEARNTOSPEAKNEWWORDSANDPHRASESNOTESEXERCISES

READINGMATERIALPROFESSIONALWORDSANDPHRASESUnit5

FiveBasicTechniquesofMachiningMetal

Machinetoolsaremadeinagreatmanytypesandsizes．Thevarietyofmachinetoolstodayisalmostunlimited．Somearesmallenoughtobemountedonabench．Othersaresolargethattheyrequirespecialbuildingtohousethem.Somearerathersimple，whileothersareverycomplicatedinconstructionandtheircontrols.

Largeorsmall，simpleorcomplicated，machinetoolscanbecategorizedintofivemajorclassifications，identifiedasthefivebasictechniquesofshapingmetal.

(1) Drilling．Drillingistheoperationofproducingholesinsolidmetal．Arotatingdrillcalledatwistdrillisused．Machinetoolsfordrillingholesarecalleddr