《机械专业英语》课件第5章

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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．现在机床的种类太多了，一些机床小到可以安装到工作台上，另一些又大到需要用专门的厂房来安放它。● sothat引导结果状语从句。

2.Thework-pieceisheldstationary，thatis，clampedinposition，andasthedrillrotates，itisfedintothework-piece．工件被固定，也就是说，被夹紧在适当位置上，钻头一边旋转一边向工件进给。● thatis为一插入语，意思是：也就是说，即。●句中as为连词，引导状语从句。

3. Boringinalatheisdonebyfeedingasingle-pointcuttingtoolintotheworkasitrevolves．在车床上镗孔是用一把单刃刀具向旋转的工件进刀完成的。●句中by引导的介词短语作方式状语。

4. AslottingmachineisreallyaverticalShaper，thecuttingtoolofwhichmovesupanddown．插床实际上是立式刨床，插床的刀具上下往复运动。● which指Aslottingmachine。

5. Inthiscase，theworkisfedagainstthecuttingtoolinastraightlineorinacircle，dependinguponthetypeofworkbeingmachined．这时，工件向刀具对直或沿圆周进给，这取决于被加工的工件的种类。● againstthecuttingtool…inacircle作方式状语，修饰动词fed。● beingmachined是现在分词的被动语态，做定语，修饰work。EXERCISES1. DiscussthefollowingquestionsinEnglish:(1) Whatisthebasictechniquesofmachiningmetal?(2) Whatisdrillingoperation?(3) WhatisthedifferencebetweentheShaperandthePlaner.2. UseEnglishreplaceChineseoruseChinesereplaceEnglish.(1)车削(2)镗削(3)铣削(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.

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