《機械專業(yè)英語》課件第5章

TEXT

LEARNTOSPEAKNEWWORDSANDPHRASESNOTESEXERCISES

READINGMATERIALPROFESSIONALWORDSANDPHRASESUnit5

FiveBasicTechniquesofMachiningMetal

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

Largeorsmall，simpleorcomplicated，machinetoolscanbecategorizedintofivemajorclassifications，identifiedasthefivebasictechniquesofshapingmetal.

(1)?Drilling．Drillingistheoperationofproducingholesinsolidmetal．Arotatingdrillcalledatwistdrillisused．Machinetoolsfordrillingholesarecalleddrillingmachines．Therearemanytypesandsizesofdrillingmachines．Thesemachinescanperformotheroperationsbesidesdrilling．Thework-pieceisheldstationary，thatis，clampedinposition，andasthedrillrotates，itisfedintothework-piece(asshowninFig.5-1).

(2)?TurningandBoring．Theenginelatheisthemostcommontypeofmachinetoolforturningwork．Turningistheoperationofcuttingorremovingmetalfromawok-piece．Acuttingtoolisfedintooralongtheworkwhilethework-piecerevolves(asshowninFig.5-2).Fig.5-1DrillingFig.5-2Turning

(3)?Milling．Millingistheoperationofremovingmetalbymeansofarotatingcuttingtool，whichhasmultiplecuttingedgesandiscalledamillingcutter(asshowninFig.5-4)．Fig.5-3BoringFig.5-4Milling

(4)?Grinding．Grindingistheoperationofcuttingorremovingmetalbymeansofanabrasivewheelcalledagrindingwheel．Grindingfinishesworkveryaccuratelyandsmoothly．Whengrindingroundwork，thework-piecerevolvesasitisfedagainsttheturningwheel．Whengrindingflatwork，thework-pieceispassedbackandforthundertheturningwheel(asshowninFig.5-5)．Thegrindingprocessisoftenusedforthefinalfinishingtoclosedimensionsofapartthathasbeenheat-treatedtomakeitveryhard．

(5)?Shaping，PlaningandSlotting．Theseoperationsaredonetoproduceormachineflat，accuratesurfaceusingsingle-pointcuttingtools．WeshouldunderstandthedifferencebetweentheShaper，thePlanerandtheslottingmachines．OnaShaper，thecuttingtoolmovesbackandforthovertheworkwhiletheworkisfedagainstthecuttingtool(asshowninFig.5-6)．Fig.5-5GrindingFig.5-6Shaping

OnaPlaner,theworkmovesbackandforthunderthecuttingtoolwhilethecuttingtoolisfedintooragainstthework-piece(asshowninFig.5-7)．

SlottingisanoperationsimilartotheoperationperformedonaShaper．AslottingmachineisreallyaverticalShaper，thecuttingtoolofwhichmovesupanddown．Inthiscase，theworkisfedagainstthecuttingtoolinastraightlineorinacircle，dependinguponthetypeofworkbeingmachined．Slotter，orverticalShaper，areusedprincipallytocutcertaintypesofgears．Fig.5-7Planing LEARNTOSPEAKMr.Yang: Morning!Mr.Smith: Morning!Mr.Yang: Doyouknowaboutthebasictechniquesofmachinemetal?Mr.Smith: Yes,therearefivemajorclassifications.Mr.Yang: Couldyoudescribeitindetail?Mr.Smith: OK.Therearedrilling,turningandboring,milling,grindingandshaping.Mr.Yang: Whatisdrillingoperation?Mr.Smith: Drillingistheoperationofproducingholesinsolidmetal．Mr.Yang: Whatisturningoperation?Mr.Smith: Turningistheoperationofcuttingorremovingmetalfromawok-piece．Mr.Yang: Andaboutmilling?

NOTES

1.?Thevarietyofmachinetoolstodayisalmostunlimited．Somearesmallenoughtobemountedonabench．Othersaresolargethattheyrequirespecialbuildingtohousethem．現(xiàn)在機床的種類太多了，一些機床小到可以安裝到工作臺上，另一些又大到需要用專門的廠房來安放它?！?sothat引導(dǎo)結(jié)果狀語從句。

2.Thework-pieceisheldstationary，thatis，clampedinposition，andasthedrillrotates，itisfedintothework-piece．工件被固定，也就是說，被夾緊在適當(dāng)位置上，鉆頭一邊旋轉(zhuǎn)一邊向工件進(jìn)給。●?thatis為一插入語，意思是：也就是說，即?！窬渲衋s為連詞，引導(dǎo)狀語從句。

3.?Boringinalatheisdonebyfeedingasingle-pointcuttingtoolintotheworkasitrevolves．在車床上鏜孔是用一把單刃刀具向旋轉(zhuǎn)的工件進(jìn)刀完成的?！窬渲衎y引導(dǎo)的介詞短語作方式狀語。

4.?AslottingmachineisreallyaverticalShaper，thecuttingtoolofwhichmovesupanddown．插床實際上是立式刨床，插床的刀具上下往復(fù)運動。●?which指Aslottingmachine。

5.?Inthiscase，theworkisfedagainstthecuttingtoolinastraightlineorinacircle，dependinguponthetypeofworkbeingmachined．這時，工件向刀具對直或沿圓周進(jìn)給，這取決于被加工的工件的種類?！?againstthecuttingtool…inacircle作方式狀語，修飾動詞fed?！?beingmachined是現(xiàn)在分詞的被動語態(tài)，做定語，修飾work。EXERCISES1.?DiscussthefollowingquestionsinEnglish:(1)?Whatisthebasictechniquesofmachiningmetal?(2)?Whatisdrillingoperation?(3)?WhatisthedifferencebetweentheShaperandthePlaner.2.?UseEnglishreplaceChineseoruseChinesereplaceEnglish.(1)車削(2)鏜削(3)銑削(4)?slottingmachine (5)?cuttingtool(6)?agrindingwheel

3.?Placea“T”aftersentencesthataretrueandan“F”afterthosethatarefalse.

(1)?Theenginelatheisthemostcommontypeofmachinetoolforturningwork.()

(2)?Drillingistheoperationofproducingflatinsolidmetal.()

(3)?Millingisremovingmetalbyarotatingcuttingtool，whichhassinglecuttingedgesandiscalledamillingcutter.()READINGMATERIAL

PrincipleofMachining

Turning

Ahighproportionoftheworkmachinedinashopisturnedonalathe．Thework-pieceisheldsecurelyinachuckorbetweenlathecenters．Aturningtool，mountedinaholderandsettoagivendepthofcut，isfedparalleltotheaxisoftheworktoreducethediameterofthework-piece(asshowninFig.5-8)．

Asthework-piecerevolvesandthecuttingtoolisfedalongtheaxis，materialisseparatedbytheedgeofthecuttingtool．Achipformsandslidesalongthecuttingtool’suppersurfacecreatedbythesiderake．Theangleofkeenness(asshowninFig.5-9)，whichpermitsthetooltoremovethemetalasthetoolisfedalongthework-piece，isformedbythesidereliefangleandthesiderakegroundonthetoolbit．Let’sassumethatwearecuttingapieceofmachinesteel；iftherakeandreliefanglesarecorrectandtheproperspeedandfeedareused，acontinuouschipshouldbeformed．Iftheangleistoosmall，theedgeofthetoolwillbreakdowntoosoon．Iftheangleistoogreat(thatis，littleornosiderake)，themetalwillnotberemovedaseffectivelyandgreatertorquewillberequiredtoremoveit．Ineithercase，abuilt-upedgeandroughsurfacefinishwillresult．Fig.5-8Thecuttingactionofalathe

orturningcenterFig.5-9Anglesandclearancesforlathecuttingtools

Planing

Thecuttingtoolusedintheplanerisbasicallythesameshapeasthelathetoolformachiningsimilarmaterials．Itshouldhavetheproperrakeandclearanceanglesgroundonittomachinethework-pieceefficiently.ThecuttingactionoftheplanerisillustratedinFig.5-10.Thework-pieceismovedbackandforthunderthecuttingtool，whichisfedsidewaysasetamountattheendofeachtablereversal.Fig.5-10ThecuttingactionofthePlanerFig.5-11Thetypeofchipproducedbyahelicalmillingcutter

PlainMilling

Amillingcutterisamultitoothtoolhavingseveralequallyspacedcuttingedges(teeth)arounditsperiphery．Eachtoothmaybeconsideredtobeasingle-pointcuttingtoolandmusthaveproperrakeandclearanceanglestocuteffectively．Fig.5-11showsthechipformationproducedbyahelicalmillingcutter.

Thework-piece，heldinaviseorfastenedtothetable，isfedintothehorizontalrevolvingcutterbyhandorbyautomatictablefeed．Astheworkisfedintothecutter，eachtoothmakessuccessivecuts，whichproduceaflat，orprofiledsurface，dependingontheshapeofthecutterused(asshowninFig.5-12).ThenomenclatureofaplainmillingcutterisshowninFig.5-13.Fig.5-12Asthework-pieceisfedintotherevolvingcutter,eachtoothremovesmaterialformtheworkFig.5-13ThenomenclatureofaplainmillingcutterEndandFaceMilling

Endmills(asshowninFig.5-14)aremultitoothcuttersheldverticallyinaverticalmillingmachinespindleorattachment．Theyareusedprimarilyforcuttingslotsorgrooves，whereasshellendmillsandfacemillsareusedprimarilyforproducingflatsurfaces．Thework-pieceisheldinaviseorclampedtothetableandisfedintotherevolvingcutterbyhandorautomatically.Whenendmilling，thecuttingisdonebytheperipheryoftheteeth．ThenomenclatureofanendmillisshowninFig.5-15.

Theinsert