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.體，鉆體shank [FANk] n.鉆柄point [pCInt] n.點(diǎn)，刀尖，鉆尖flute [flu:t] n.凹槽，螺旋槽spiral [5spaIEr(E)l] adj.螺旋形的，螺紋的rake [reIk] n.前角lip [lIp] n.緣，刀刃，切削刃chip [5tFIp] n.碎屑，切屑curl [k

:l] v.使卷曲，使卷邊channel [5tFAnEl] n.通道，溝槽

lubricant [5lu:brIkEnt] n.滑潤(rùn)劑

margin [5mB:dVIn] n.刃帶，邊界，界限

lessen [5les(E)n] v.減少，減輕

socket [5sBkIt] n.鉆套，插口

tang [tAN] n.柄舌

sensitive [5sensItIv] adj.敏感的

tapping [5tApIN] n.攻絲，攻螺紋，穿孔

threading [WredIN] n.車(chē)絲，車(chē)螺紋

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

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

boring [5bR:rIN] n.鏜孔

spiralgroove螺旋槽

bodyclearance鉆體間隙

spotfacing 锪端面

NOTES

1．Itisgenerallyformedbyforgingandtwistinggroovesinaflatstripofsteelorbymillingacylindricalpieceofsteel,high-speedsteelbeingcommonlyused.它通常由扁鋼鍛造后扭轉(zhuǎn)出凹槽，或由圓柱形棒料銑削而成，一般由高速鋼制作。

“…，high-speedsteelbeingcommonlyused”是被動(dòng)形式的分詞獨(dú)立結(jié)構(gòu)，它用來(lái)對(duì)句子的意思加以補(bǔ)充，可直接譯成相當(dāng)于漢語(yǔ)的一個(gè)句子。本句結(jié)構(gòu)為“名詞+being+過(guò)去分詞”。

在本課中類(lèi)似的結(jié)構(gòu)還有“…，drillsbeingmadewithtwo,three,orfourflutes.”

2．High-speedsteelcostsmorebuttoolsmadeofitwithstandheatmuchbetterthanthosemadeofordinarytoolsteel.高速鋼的成本雖然較高，但用它制作的刀具在耐熱性方面要比用普通工具鋼好得多。

3．Theycausethechiptocurlsotightlythatitoccupiestheminimumamountofspace.

(螺旋槽)卷緊切屑,使其占有最小空間。

4．Itispracticallythefulldiameterofthedrillandextendstheentirelengthoftheflute,itssurfacebeingapartofacylinder.

(刃帶部分)實(shí)際上是鉆頭的最大直徑處，它伸展到螺旋槽的全長(zhǎng)，刃帶的表面是圓柱體的一部分。

5．Thedrillingmachineisthesecondoldestmachinetool,havingbeeninventedshortlyafterthelathe,…鉆床是僅次于車(chē)床的最古老的機(jī)床，它的發(fā)明略晚于車(chē)床(它在車(chē)床發(fā)明之后不久就被發(fā)明了)。

6．Theverticalspindledrillingmachinecomesinthreetypes:heavyduty,plain,andsensitive.立式鉆床有三種類(lèi)型：重型鉆床、普通鉆床和高速手壓臺(tái)鉆。 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