《机械专业英语》课件第17章

Unit17TEXT

LEARNTOSPEAKNEWWORDSANDEXPRESSIONSNOTES

EXERCISES

READINGMATERIALPROFESSIONALWORDSANDPHRASES Lathe Alatheisamachinetoolforcuttingmetalfromthesurfaceofaroundworkfastenedbetweenthetwolathecentersandturningarounditsaxis.Inturningtheworkacuttermovesinthedirectionparalleltotheaxisofrotationoftheworkoratanangletothisaxis,cuttingoffthemetalfromthesurfaceofthework.Thismovementofthecutteriscalledthefeed.Thecutterisclampedinthetoolpostwhichismountedonthecarriage.Thecarriageisthemechanismfeedingthecutterintheneededdirection.Thelathehandmayfeedthecutterbyhandormaymakeitbefedautomaticallybymeansofspecialgears.

Thelargestpartofthelatheiscalledthebedonwhichtheheadstockandthetailstockarefastenedatoppositeends.Ontheupperpartofthebedtherearespecialwaysuponwhichthecarriageandthetailstockslide.

Thetwolathecentersaremountedintwospindles:one(thelivecenter)isheldintheheadstockspindle,whiletheother(thedeadcenter)inthetailstockspindle.Fig.17-1Anenginelathe

Thelathechuckisusedforchuckingthework,whichisforclampingitsothatitwillrotatewithoutwobblingwhileturning.Thechuck,usually,mountedontheheadstockspindle,mayhavedifferentsizesandconstruction.Iftheworkisperfectlyround,itmaybechuckedintheso-calledthree-jawuniversalchuck,allthejawsofwhicharemovedtothecenterbyturningthescrew.Butiftheworkisnotperfectlyround,thefour-jawindependentchuckshouldbeused.

Inturningdifferentmaterialsandworksofdifferentdiameters,lathesmustberunatdifferentspeeds.Thegearboxcontainedintheheadstockmakesitpossibletorunthelatheatvariousspeeds.

Beforeturningaworkinthelathe,thelathecentersaretobealigned;thatmeansthattheaxesofbothcentersmustbeononeline.

Thealignmentofthelathecentersmaybetestedbytakingacutandthenmeasuringbothendsofthecutwithamicrometer.Notallworksshouldbefastenedbetweenthetwocentersofthelathe.Ashortworkmaybeturnedwithoutusingthedeadcenter,bysimplychuckingitproperlyatthespindleoftheheadstock.

LEARNTOSPEAKMr.Li: Excuseme,mayIaskyouaquestion?Bob.Bob: Ofcourse!Mr.Li: Doyouknowaboutthestructureofthelathe?Bob: Yes.Iknowsomeofthem.Mr.Li: What’sthis?Bob: It’saheadstock.Sometimespeoplecallitastheheartofalathe.Mr.Li: What’sthisthen?Bob: It’sachuckandawork-piececanbemountedonit.Mr.Li: What’sthat?Bob: It’stoolpostandcarriage.Thecuttingtoolsareputhere.Mr.Li: What’sthat?Bob: It’scenterandtailstock.Mr.Li:What’sthat?Bob: It’sabed.Theseareallthemainstructureofthelathe.Arethosecleartoyou?Mr.Li:Yes.Youareverykind.Bob: Delightedtohavebeenofassistance.machinetool 机床，工具机millingmachine 铣床toolpost 刀座，刀架livecenter 主轴顶尖deadcenter 尾架顶尖

NOTES

1．Inturningtheworkacuttermovesinthedirectionparalleltotheaxisofrotationoftheworkoratanangletothisaxis,cuttingoffthemetalfromthesurfaceofthework.车削工件时，车刀沿着工件的旋转轴线平行移动或者是与工件的旋转轴线成一斜角移动，将工件表面的金属切除。

“parallel”为形容词，“paralleltotheaxisofrotationofwork”做后置定语修饰名词“direction”。

“cuttingoffthemetalfromthesurfaceofthework”为分词短语作状语，表示伴随情况。这种状语往往放在句末，常用逗号与句子的其它成分隔开。

2．Thelathehandmayfeedthecutterbyhandormaymakeitbefedautomaticallybymeansofspecialgears.用手操纵手柄来使车刀实现进给，也可以借助于专门的传动装置实现自动进给。

有些动词如“make”、“hear”、“let”、“watch”后的不定式作宾语补语时，可不带不定式符号“to”。句中“befed”是不定式的被动式，作宾语it的补语。由于其谓语动词是“make”，故省略不定式符号“to”，而成为“…makeitbefed…”。这里“it”代表“thecutter”。

句中“thelathehand”为主语，带有两个并列的谓语“mayfed”和“maymake”。

3．Thegearboxcontainedintheheadstockmakesitpossibletorunthelatheatvariousspeeds.装入床头箱内的齿轮系统能使车床以不同的速度运转。

“it”在句中作形式宾语，而真正的宾语是不定式短语“torunthelatheatvariousspeeds”。它通常放在宾语补足语(possible)的后面。

“containedintheheadstock”作后置定语，修饰名词“thegearbox”。

4．Beforeturningaworkinthelathe,thelathecentersaretobealigned;thatmeansthattheaxesofbothcentersmustbeononeline.车床在车削工件前，它的顶尖要对准，即两个顶尖的轴线必须在一条直线上。

句中有两个“that”，前一个“that”是用作指示代词，它代表前面句子的内容，即代表“thelathecentersaretobealigned”。后一个“that”作连接词，无词义，引出宾语从句“…theaxesofbothcentersmustbeononeline”。

“tobealigned”是不定式的被动式在句中作宾语。

EXERCISES1．DiscussthefollowingquestionsinEnglish:(1) Whichpartsdoesanenginelatheconsistof?(2) Howtomountthework-piecewhenturning?(3) Howmanykindsofcuttingtoolsaretherewhenmachiningawork-pieceinthelathe?2．UseEnglishforreplacingChineseoruseChineseforreplacingEnglish.(1)车床的主轴(2)横拖板的运动(3)尾架顶尖(4) Thespeedofthemainspindle(5) Rotatingofthefeedrod(6) Railofbed

3．placea“T”aftersentencesthataretrueandan“F”afterthosethatarefalse.

(1) Latheisthemachinetoolforholdingandturningmetal,plasticorothermaterialagainstacuttingtoolformacylindricalproduct.()

(2) Iftheworkisnotperfectlyround,itmaybechuckedintheso-calledthree-jawuniversalchuck.()

(3) Thelatheisoneofthemostimportantmachinesinamachineshop.()

(4) Theheadstockwhichholdstheotherendofthework,movesalongthebed,andcanbeclampedinpositionatanypoint.()

(5) Themostimportantofmachinetoolsusedinindustryarelathes,drillingmachines,andmillingmachines.()

(6) Thesmallestpartofthelatheiscalledthebedonwhichtheheadstockandthetailstockarefastenedatoppositeends.()

4．Filltheblankswiththewordsandphrasesgivenbelow:springsandpulleys,gearsandpulleys,right,feeding,carrying,three-jaw,four-jaw,left,short,measurement,alignment,long.

(1) Theheadstockismountedatthe_______endofthelathe.

(2) Itcontainstheheadstockspindle,whichisrotatedbygearsorbyacombinationof________.

(3) Butiftheworkisnotperfectlyround,the_________independentchuckshouldbeused.

(4) Thecarriageisthemechanism________thecutterintheneededdirection.

(5) The______ofthelathecentersmaybetestedbytakingacutandthenmeasuringbothendsofthecutwithamicrometer.

(6) A________workmaybeturnedwithoutusingthedeadcenter,bysimplychuckingitproperlyatthespindleoftheheadstock.READINGMATERIAL

ThePlaner

Theplanerisoneofthebiggestmachinetoolsthatemployareciprocatingcuttingaction．Itgeneratesflatorcontouredsurfacesinaseriesofstraightcuts．Itsefficiencyishigherthanthatoftheshaper．

Theworkontheplanerisheldonthemachinetableandmovesunderthetoolwhichiscarriedontherail．Thebedmustbeapproximatelytwiceaslongasthetabletosupportitatallpositionsduringthestroke．Thedouble-housingplanerhastwohousingstosupporttherailateachend．Theopen-sideplanerhasthehousing