《机械专业英语》课件第19章

Unit19TEXT

LEARNTOSPEAKNEWWORDSANDPHRASESNOTES

EXERCISES

READINGMATERIALPROFESSIONALWORDSANDPHRASES MillingMachines

Themillingmachineisamachinethatremovesmetalfromtheworkwitharevolvingmillingcutterastheworkisfedagainstit.Themillingcutterismountedonanarborwhereitisheldinplacebyspacersorbushings.Thearborisfixedinthespindlewithoneend,whiletheotherendofthearborrotatesinthebearingmountedonthearboryoke.Fig.19-1Typeofmillingcutter

Themillingcuttersaregenerallymadefromhighspeedsteelandareavailableindifferentsizesandshapes.Therearesuchkindsofmillingcutters(asshowninFig.19-1)ascylindricalcutters,endmillingcutters(forfacemilling),formmillingcutters,angularcutters,sideandfacecutters,slittingsaw,etc.Thesecuttersmaydifferinthedirectionoftheiroperation,i.e.theymaycutrevolvingeitherclockwiseorcounter-clockwise.

Regularorirregularshapedworkmaybeproducedonamillingmachine,designsvaryingaccordingtotheparticularclassofworkwanted.Accordingtothepositionofthespindle,themillingmachinesmaybedividedintotwogroupsofverticalspindlemillingmachinesandhorizontalspindlemillingmachines.Millingmachinesmaybegroupedintovariousclasses.

Accordingtothevariationingeneraldesignasthe“columnandkneetype”,themanufacturingtypes,andtheplanertypeofmillingmachine.Accordingtothetabledesign,themillingmachinesmaybeclassifiedasuniversalandplainmillingmachines.

Themostimportantpartsofthemillingmachinearestartinglevers,spindle,column,knee,elevatingscrew,table,indexhead,speedlevers,feedlevers,tablemovementlevers,footstock,arboryoke.

Thespindleofthemillingmachineisdrivenbyanelectricmotorthroughatrainofgearsmountedinthecolumn.Thetableoftheplainmillingmachinemaytravelonlyatrightanglestothespindle,whiletheuniversalmillingmachine(asshowninFig.19-2)isprovidedwithatablethatmaybeswiveledonthetransverseslideformillinggearteeth,threads,etc.Fig.19-2Universalmillingmachine

Variousattachmentsareusedforincreasingtherangeofworkthatcanbeperformedonamillingmachine.

Thedividinghead(alsocalledanindexhead)isadeviceusedtodividetheperipheryofapieceofworkintoanynumberofequalparts,andtoholdtheworkintherequiredpositionwhilethecutsarebeingmade.

Variouskindsofvisesmaybeusedforholdingtheworkinamillingmachine,themostcommonbeingtheplainvise,andtheswivelvise.

LEARNTOSPEAK

MissLi:  Hi,Mr.Liu.

Mr.Liu:  Hi,MissLi.Howareyou?

MissLi:  Iamfine.Thankyou.ButIhavesomeproblemwiththemachinetools.Couldyou  givemeafavor?

Mr.Liu:  Yes,mypleasure.Whataretheseproblems?

MissLi:  Whatcanshaperandplanerdo?

Mr.Liu:  Theshaperandplaneraregenerallyusedformachiningflatsurfaces,whichare 

usuallypreformedbyacutterthatpeelthechipfromthework.

MissLi:  Whataretheshapeandplaner’smotionforms?

Mr.Liu:  Themainmotionisreciprocatingandthefeedaimsatthedirectionofthemain

motion.

MissLi:  Aretheshaperandplanerusedinmassproduction?

Mr.Liu:  No.

MissLi:  Why?

Mr.Liu:  Becausetheyareratherslowinoperation.

MissLi:  But,formassproduction,whatmethodsshouldweuse?

Mr.Liu:  Millingmachinesandgrindersaremorewidelyusedforproducingflatsurfacesin

massproduction.

MissLi:  Whatstructuresarethereonatypicalshaper?

Mr.Liu:  Therearetoolhead,ram,column,table,rockermechanism,etc.

MissLi:  Howisthefeedobtainedonashaper?

Mr.Liu:  Thefeedisobtainedbyapawlwhichengagesinanotchedwheelorratchet.

MissLi:  Iamreallyappreciatedyoufortellingmetheseknowledge.

Mr.Liu:  I

wasgladtobeofsomeservices.NEWWORDSANDPHRASES

removefrom 从……除去

accordingto 根据，视……而定，按照

bedividedinto 分成……

begroupedinto 分类为

beprovidedwith 装有，备有 NOTES

1．Themillingmachineisamachinethatremovesmetalfromtheworkwitharevolvingmillingcutterastheworkisfedagainstit.铣床是一种当工件向铣刀进给时，铣刀旋转着从工件上切除金属的机床。

“that”引导定语从句，修饰“machine”；“as”引导时间状语从句，意为“当……时候”。

2．Regularorirregularshapedworkmaybeproducedonamillingmachine,designsvaryingaccordingtotheparticularclassofworkwanted.在铣床上可以加工规则的或不规则的工件，铣床结构的不同取决于所要加工工件的类型特点。

“irregular”一词中，“ir-”为前缀，意为“不、非”。

3．Thetableoftheplainmillingmachinemaytravelonlyatrightanglestothespindle,whiletheuniversalmillingmachine(asshowninFig.19-2)isprovidedwithatablethatmaybeswiveledonthetransverseslideformillinggearteeth,threads,etc.普通铣床的工作台只能沿着垂直于主轴的方向运动，而万能铣床( 如图19-2所示)在铣削轮齿、螺纹等时，工作台可以在横向滑板上转动。

这句较长，它是由连词“while”连接的表示转折的并列句。在第二个句子中，“that”引导的从句作定语修饰“table”。 EXERCISES

1．Placea“T”aftersentencesthataretrueandan“F”afterthosethatarefalse.

(1) Themillingmachineisamachinethatremovesmetalfromtheworkwithastationarymillingcuttersastheworkisfedagainstit.()

(2) Alargeproportionofmillingmachinesareofthetypehavingtheworktableadjustableforheight.()

(3) Theworktablemaybemovedlongitudinallybyhandorautomatically,inonedirection.()

(4) Thedividinghead(alsocalledanindexhead)isadeviceusedtodividethediameterofapieceofworkintoanynumberofrequiredpositionwhilethecutsarebeingmade.()

(5) Theverticalspindlemillingmachineissocalledbecausetheaxisofrotationofthespindleishorizontal.()

2．Filltheblankswiththewordsandexpressionsgivenbelow:

swivel(ed),most,highspeedsteel,verticallyorhorizontally,least,fixed,ordinarytoolsteel,clockwiseorcounter-clockwise,dividing,putting.

(1) Themillingcuttersaregenerallymadefrom_______andareavailableindifferentsizesandshapes.

(2) Theuniversalmillingmachineisprovidedwithatablethatmaybe_______onthetransverseslideformillinggearteeth,threads,etc.

(3) Thesecuttersmaydifferinthedirectionoftheiroperation,i.e.theymaycutrevolvingeither_______or_______.

(4) Indexingistheprocessof_______theperipheryorfaceofawork-pieceintoanynumberofequallyspaceddivisions.

(5)Variouskindsofvisesmaybeusedforholdingtheworkinamillingmachine,the_______commonbeingtheplainvise,andtheswivelvise.

3．Answerthefollowingquestions:

(1) Definethemetal-cuttingoperationcalled“milling”.

(2) Whatisamillingcutter?

(3) Namethethreeprincipaltypesofmillingmachines.

(4) Howdoesauniversalmillingmachinedifferfromaplainmillingmachine?READINGMATERIAL

GrindingMachines

Agrindingmachineisamachinewhichemploysagrindingwheelforproducingcylindrical,conicalorplanesurfacesaccuratelyandeconomicallyandtothepropershape,size,andfinish.Thesurplusstockisremovedbyfeedingtheworkagainsttherevolvingwheelorbyforcingtherevolvingwheelagainstthework.

Thereisagreatvarietyofgrindingmachines.Themachinesthataregenerallyusedarecuttergrinder,surfacegrinder,centerlessgrinder,externalgrinder,internalgrinder,andtoolgrinder.Thesemachinesareusuallyclassifiedastosizebythelargestpieceofworkwhichtheycancompletelymachine(as6×18inchExternalgrinder).

Fivetypesofgrindingoperationsareperformedongrindingmachines,asshowninFig.19-3.Fig.19-3Fivetypesofgrindingoperations

(1) Cylindricalgrinding.Exteriorcylindersandtapersaregroundonplaingrindingmachinesandoncenterlessgrinders.

Theconstructionofuniversalgrindingmachinesissimilartothatofplaingrinders.Theyareequippedwithaninternalgrindingattachment,however,nothattheycandobothcylindricalandinternalgrinding.

(2) Internalgrinding.Interiorcylindersandtapersaregroundoninternalgrindingmachinesandoncenterlessgrinders.

(3)Surfacegrinding.Planesurfacesaregroundonseveraltypesofsurface-grindingmachines.

(4) Toolandcuttergrinding.Reamers,millingcuttersandothertoolsaresharpenedontoolandcuttergrindingmachines.

(5) Formgrinding.Somemachinetoolssuchasthread,andgeargrindersaredesignedespeciallyforformgrinding.

Plaingrindingmachine.AplaingrindingmachineillustratedinFig.19-4isessentiallyalatheonwhichagrindingwheelhasbeensubstitutedforthesingle-pointtool.Fig.19-4Plaingrindingmachine

Principalpartsofaplaingrindingmachineareasfollows:

(1) Base.Themaincastingofaplaingrindingmachineisabasethatrestsonthefloor.

(2) Tables.Aslidingtable,whichismountedonwaysatthefrontandtopofthebase,maybemovedlongitudinallybyhandorpowertofeedwork-piecespastthefaceofthegrindingwheel.Ifthecenterlineoftheswiveltableissetatanangle,ataperwillbeground.

(3) Headstockandtailstock.Amotor-driverheadstockandatailstockaremountedontheleftandrightends,respectively,oftheswiveltableforholdingwork-piecesoncenters.Theheadstockcen