《机械专业英语》课件第18章

Unit18TEXTLEARNTOSPEAKNEWWORDSANDEXPRESSIONSNOTESEXERClSES

READINGMATERIALPROFESSIONALWORDSANDPHRASES

DrillsandDrillingMachines

Thetwistdrillisaveryefficienttool.Itisgenerallyformedbyforgingandtwistinggroovesinaflatstripofsteelorbymillingacylindricalpieceofsteel,high-speedsteelbeingcommonlyused.High-speedsteelcostsmorebuttoolsmadeofitwithstandheatmuchbetterthanthosemadeofordinarytoolsteel.

Thetwistdrillmaybedividedintothreeprincipalparts:body,shank,andpoint.Theflutesarethespiralgroovesthatareformedonthesideofadrill,drillsbeingmadewithtwo,three,orfourflutes.Thosehavingthreeorfourflutesareusedforfollowingsmallerdrillsorforenlargingholesalreadydrilled,andarenotsuitedfordrillingintosolidstock.Fig.18-1Thetwistdrill

Spiralfluteshavefourmainadvantages:

(1) Theygivethecorrectraketothelipofadrill.

(2) Theycausethechiptocurlsotightlythatitoccupiestheminimumamountofspace.

(3) Theyformchannelsthroughwhichchipsescapefromthehole.

(4) Theyallowthelubricanttofloweasilydowntothecuttingedge.

Themarginisthenarrowstriponthecuttingedgeoftheflute.Itispracticallythefulldiameterofthedrillandextendstheentirelengthoftheflute,itssurfacebeingapartofacylinder.Theportionofthebodynexttothemarginisoflessdiameterthanthemargin.Thislesseneddiameter,calledbodyclearance,reducesthefrictionbetweenthedrillandthewallsofthehole,whilethemargininsurestheholebeingofaccuratesize.

Theshankistheendofthedrillwhichfitsintothesocket,spindle,orchuckofthedrillpress.Thetangisusuallyfoundonlyontaperedshanktools.。

Thedrillingmachineisthesecondoldestmachinetools,havingbeeninventedshortlyafterthelathe,andisoneofthemostcommonandusefulmachines.Thedrillingmachinesmaybeclassifiedintothreegeneraltypes:verticalspindle,multiplespindle,andradialspindlemachine.Theverticalspindledrillingmachinecomesinthreetypes:heavyduty,plain,andsensitive.

Besidesthedrillingofholes,suchoperationsmaybeperformedonthedrillingmachine:drilling,tapping(internalthreading),reaming(finishingtheholewithareamer),countersinking,counterboring,boringandspot-facing.Fig.18-2Drillingmachineoperations

LEARNTOSPEAK

LiYing: Goodmorning,TeacherWang.

TeacherWang: Goodmorning,LiYing.

LiYing: Whatareyoudoing?

TeacherWang: Iamdrillingaholeinthiswork-piece.

LiYing: What’sthis?

TeacherWang: Itisadrillingmachine.

LiYing: Whatcanwedowiththedrillingmachine?

TeacherWang: Itcanbeusedformachiningholes.

LiYing: Isthetwistdrillaveryefficienttool?TeacherWang: Yes.Itis.LiYing: Whatmaterialisthetwistdrillgenerallymade of?TeacherWang: Itisusuallymadeofhigh-speedsteel.LiYing: Howmanypartsmaythetwistdrillbedividedinto?TeacherWang: Itmaybedividedintothreeprincipalparts:body, shankandpoint.LiYing: Howmanyflutesarethereonthetwistdrill?TeacherWang: Therearetwo,three,orfourflutes.LiYing: Couldyoutellmeaboutthehistoryofdrilling machine.TeacherWang: Ofcourse!Thedrillingmachineisthesecondoldestmachine,havingbeeninventedshortlyafterthelathe,andisoneofthemostcommonandusefulmachines.LiYing: Oh,Isee.Thankyou,TeacherWang.Bye-bye.TeacherWang: Bye!

NEWWORDSANDEXPRESSIONSefficient [I5fIFEnt] adj.有效率的，能干的principle [5prInsIp(E)l] adj.主要的，首要的body [5bBdI] n.体，钻体shank [FANk] n.钻柄point [pCInt] n.点，刀尖，钻尖flute [flu:t] n.凹槽，螺旋槽spiral [5spaIEr(E)l] adj.螺旋形的，螺纹的rake [reIk] n.前角lip [lIp] n.缘，刀刃，切削刃chip [5tFIp] n.碎屑，切屑curl [k

:l] v.使卷曲，使卷边channel [5tFAnEl] n.通道，沟槽

lubricant [5lu:brIkEnt] n.滑润剂

margin [5mB:dVIn] n.刃带，边界，界限

lessen [5les(E)n] v.减少，减轻

socket [5sBkIt] n.钻套，插口

tang [tAN] n.柄舌

sensitive [5sensItIv] adj.敏感的

tapping [5tApIN] n.攻丝，攻螺纹，穿孔

threading [WredIN] n.车丝，车螺纹

countersinking [5kaJntE(r)sINkIN] n.尖底锪钻

counterboring [5kaJntE(r)5bR:rIN] n.平底锪钻

boring [5bR:rIN] n.镗孔

spiralgroove螺旋槽

bodyclearance钻体间隙

spotfacing 锪端面

NOTES

1．Itisgenerallyformedbyforgingandtwistinggroovesinaflatstripofsteelorbymillingacylindricalpieceofsteel,high-speedsteelbeingcommonlyused.它通常由扁钢锻造后扭转出凹槽，或由圆柱形棒料铣削而成，一般由高速钢制作。

“…，high-speedsteelbeingcommonlyused”是被动形式的分词独立结构，它用来对句子的意思加以补充，可直接译成相当于汉语的一个句子。本句结构为“名词+being+过去分词”。

在本课中类似的结构还有“…，drillsbeingmadewithtwo,three,orfourflutes.”

2．High-speedsteelcostsmorebuttoolsmadeofitwithstandheatmuchbetterthanthosemadeofordinarytoolsteel.高速钢的成本虽然较高，但用它制作的刀具在耐热性方面要比用普通工具钢好得多。

3．Theycausethechiptocurlsotightlythatitoccupiestheminimumamountofspace.

(螺旋槽)卷紧切屑,使其占有最小空间。

4．Itispracticallythefulldiameterofthedrillandextendstheentirelengthoftheflute,itssurfacebeingapartofacylinder.

(刃带部分)实际上是钻头的最大直径处，它伸展到螺旋槽的全长，刃带的表面是圆柱体的一部分。

5．Thedrillingmachineisthesecondoldestmachinetool,havingbeeninventedshortlyafterthelathe,…钻床是仅次于车床的最古老的机床，它的发明略晚于车床(它在车床发明之后不久就被发明了)。

6．Theverticalspindledrillingmachinecomesinthreetypes:heavyduty,plain,andsensitive.立式钻床有三种类型：重型钻床、普通钻床和高速手压台钻。 EXERClSES

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

(1) Thedrillingmachineisthesecondoldestmachinetool,havingbeeninventedshortlybeforethelathe.()

(2) Thespiralfluteofadrillcausethechiptocurlsotightlythatitoccupiesthemaximumamountofspace.()

(3) Inadditiontodrills,othertoolssuchasreamers,countersinks,counterboresandboringheadscanalsobeused.()

(4) Spiralflutesallowthelubricanttofloweasilydowntothecuttingedge.()

(5)Toolsmadeofordinarytoolsteelwithstandheatmuchbetterthanthosemadeofhigh-speedsteel.()

(6) Ataperkeyisusedtoremovethetapershankfromthetaperhole.Donotuseanythingbutataperkeyforthispurpose.()

2．Filltheblankswiththewordsgivenbelow:

Socket,pocket,lightduty,plain,spotfacing,tapping,efficient,effective,holes,slots,less.

(1) Theend-cuttingtoolthatisusedtooriginate____________inmetaliscalleda“twistdrill”.

(2) Thetwistdrillisvery_________tool.

(3) Theportionofthebodynexttothemarginisof______diameterthanthemargin.

(4) ________istheoperationofsmoothingandsquaringthesurfacearoundtheendofahole,asfortheseatforanutortheheadofacapscrew.

(5) Theshankistheendofthedrillwhichfitsintothe_______,spindle,orchuckofthedrillpress.

(6) TheVerticalSpindleDrillingmachinecomesinthreetypes:Heavyduty,_________,andSensitive. 3．Answerthefollowingquestions:

(1) Whatsteelsaretwistdrillsgenerallymadeof?

(2) Whataretheprinciplepartofatwistdrill?

(3) Whatisthemargin?

(4) Whyisthebodyclearancemadeonadrill?

(5) Whatistheshankofadrill?READINGMATERIAL

RadialDrillingMachine

Theradialdrillingmachineisdesignedforhandlinglargework-piecesthatcannotbeeasilymoved．Thedrillingm