機械專業(yè)英語董建國第4章

Unit4TEXT

READINGMATERIALTEXTConventionalMillingVSClimbMillingTherearetwomethodsofmilling，i.e.conventionalorupmillingandclimbordownmilling．Inconventionalmilling，thecutterrotatesagainstthedirectionoffeed．Thismethodhaslongbeenregardedastheonlypracticalwaytousemillingcutters.Notlongago,climbmillingwasrecognizedasanacceptablemethodofoperation.

Inclimbmilling，thecutterrotatesinthedirectionoffeed．Theadvantagesofclimbmillingareasfollows:(1)?Feedcanfrequentlybedoubledoverconventionalmilling.(2)?Metalscanberemovedfastwithoutvibration.(3)?Finishcanbeconsiderablyimproved．(4)

Toollifemaybeprolonged．Fig.4-1Twomethodsofmilling(a)?Conventional(Up)milling；(b)?Climb(Down)millingBothconventionalmillingandclimbmillingarebeingemployed，becauseclimbmillingisnotapplicabletoanymillingjob．Climbmillingcanbeappliedonlywhenthemachineisofaheavy-dutytypeandbacklashhasbeeneliminated．Climbmillingisnotrecommendedforuseoncastironorforgings.Therefore,conventionalmillingremainsusefulinmillingwork．LEARNTOSPEAKMr.Liu: Goodafternoon,Mr.Xiong.Mr.Xiong: Goodafternoon,Mr.Liu.Mr.Liu: Ihavesometroublewithheattreatment.Couldyoutellme?Mr.Xiong: Whataretheproblems?Mr.Liu: Doyouknowwhatisthefunctionofheattreatment?Mr.Xiong: Yes.IthinkIsee.Heattreatmentisamethodbywhichtheheattreatercanchangethephysicalpropertiesofamaterial.Mr.Liu: Howmanytypesofheattreatmentarethere?Mr.Xiong: Therearethreemainoperationsintheheattreatmentofsteel:hardening,temperingandannealing.Mr.Liu: Howishardeningoperationdone?Mr.Xiong: Thehardeningoperationconsistsofheatingthesteelaboveitscriticalrangeandthenquenchingitinasuitablemediumsuchaswater,brine,oil,orsomeotherliquid.Havingbeenhardened,themetalmustbegivenatemperingtreatmentwhichconsistsofreheatingthehardenedsteeltoatemperaturebelowthecriticalrange,thusproducingtherequiredphysicalproperties.Mr.Liu: Andwhatiscriticaltemperature?Mr.Xiong: Itisthetemperatureatwhichacertainchangetakesplaceinthephysicalconditionofthesteel.Mr.Liu: Whatisthepurposeofannealing?Mr.Xiong: Itcansoftenawork-pieceandrelieveinternalstressesproducedbymachining.Mr.Liu: Thankyoutellingmeaboutthese.Mr.Xiong: I’mgladtohavebeenofsomeservice.NEWWORDSANDEXPRESSIONSconventional [kEn5venFEn(E)l] adj.一般的，常規(guī)的VS=versus [5vз:sEs] prep.對，與…相對climb [klaIm] v.&n.攀登，爬i.e.=thatis 即，就是regard [rI5^B:d] v.&n.認為，考慮recognize [5rekE^naIz] vt.承認，認識acceptable [Ek5septEb(E)l] adj.可接受的frequent [5fri:kwEnt] adj.時常發(fā)生的，頻繁的frequently adv.常常，屢次double [5dQb(E)l] n.兩倍 adj.兩倍的 vt.使加倍 vi.加倍vibration [vaI5breIF(E)n] n.振動，搖動considerable[kEn5sIdErEb(E)l] adj.相當大(或多)的，重要的considerablely 相當大地prolong [prE5lBN;(?@)prEJ5lC:N] vt.延長，拖延applicable [5AplIkEb(E)l] adj.可適用的，合適的duty [5dju:tI;(?@)5du:tI]n.責(zé)任，功率，稅backlash [5bAklAF] n.間隙，輪齒隙eliminate [I5lImIneIt] vt.排除，消除recommend [rekE5mend] vt.推薦，介紹cast [kB:st;(?@)kAst] n.鑄件 v.鑄造casting n.鑄造，鑄件forge [fC:dV] n.鍛工車間 v.鍛造forging鍛造，鍛件tempering v.回火annealing v.退火quenching n.淬火brine [braIn] n.鹽水reheating [ri:5hi:tIN] n.重新加熱conventionalmilling逆銑climbmilling順銑upmilling 逆銑downmilling 順銑regard…as 認為……是inasimilarway 同樣inthisway 這樣berecognizedas 被認為是toollife 刀具壽命，刀具耐用度heavy-duty 重型的castiron 鑄鐵asfollows 如下twistdrill 麻花鉆high-speedsteel高速鋼heattreatment熱處理heattreater 熱處理工作者physicalpropertiesofamaterial材料的物理性能hardenedsteel 淬硬鋼criticalrange 臨界點internalstress 內(nèi)應(yīng)力criticaltemperature 臨界溫度NOTES1．Therearetwomethodsofmilling，i.e.conventionalorupmillingandclimbordownmilling．銑削方法有兩種：逆銑(即反向銑削)與順銑(即同向銑削)?！皁r”可以表示“即”的意義，引出一個同位語。例如:Thecuttingspeedmustbereducedinthefirst,orroughingcut．在初切(即粗切)時，切削速度必須降低。2．Inconventionalmilling，thecutterrotatesagainstthedirectionoffeed．逆銑時，銑刀旋轉(zhuǎn)方向與進給方向相反?！癮gainstthedirectionof……”的含義是“與……的方向相反”。3．Thismethodhaslongbeenregardedastheonlypracticalwaytousemillingcutters.這種銑削方法長期以來一直被認為是使用銑刀的惟一切實可行的方法。?tov短語可以用來修飾名詞。這里的“touse”用來修飾前面的“way”。又例如:Conventionalmillingisnottheonlywaytousemillingcutters.逆銑不是使用銑刀的惟一方法。4．Inclimbmilling，thecutterrotatesinthedirectionoffeed．順銑時，銑刀順著進給方向旋轉(zhuǎn)。“inthedirectionof…”的含義是“沿著……的方向”。5．Climbmillingcanbeappliedonlywhenthemachineisofaheavy-dutytypeandbacklashhasbeeneliminated．只有在機床具有相當?shù)膭傂郧议g隙也已消除的情況下，才能使用順銑。“be+of+抽象名詞”可以表示“具有”或“屬于”等意義。句中“isofaheavy-dutytype”的含義是“是重型的(剛性好的)”。再看下面兩個句子：Thesesupportsareofgreatrigidity.這些支架具有很大的剛性。Thismachineisnotofaheavy-dutytype.這臺機器不屬于重型的。EXERCISES1．DiscussthefollowingquestionsinEnglish:(1)?Whatistheconventionalmilling?(2)?Whatistheclimbmilling?(3)?Whatarethedifferencesbetweentheconventionalmillingandtheclimbmilling?2．UseEnglishforreplacingChineseoruseChineseforreplacingEnglish.(1)進給方向(2)銑刀(3)粗切(4)?Methodofoperation(5)?Thedirectionoffeed(6)?PracticalwayREADINGMATERIALRoughingandFinishingCutItiscustomary，inshoppractice,totakeatleasttwocutsmakeajobsmoothandaccurate．Thefirstcuttotakeistoremoveexcessmetalfromthesurfaceofthework-pieceasrapidlyaspossible．Todothis，thecutshouldbeasdeepandthefeedascoarseasthework-pieceandthemachinetoolwillstand．Cuttingspeedshouldbeadjusteddownward,ifnecessary，topermitthis．Thefirst，orroughing，cutshouldbedeepenoughtosizethejob,withasuitableallowanceforafinishingcut,inonepasswheneverpossible．Whenyouintendtoadjustthecuttingspeedorthefeedtoincreasetherateoftheoftheproductiononamachinetool,itisadvisabletoincreasethefeedeventhoughthespeedmustbereducedsomewhat．Toincreasethefeedratherthanthecuttingspeedwillincreaseproductionwithoutacorrespondingincreaseinpowerconsumptionandtoolwear．Thepurposeofthelast，orfinishing，cutistofinishawork-piecesmoothandaccurate.Toaccomplishthis，thecutshouldbeshallowandthefeedfineandcuttingspeedshouldbeincreasedmuchhigherthanfortheroughingcut.Roughingandfinishingoperationsareusuallynotperformedonthesamemachine.Itisacommonpractice，forexample，torough-turnwork-piecesonalathe,andtofinishthemonagrinder．Somemachines,abrasivemachinesforinstance,areknowntoperformbothroughingandfinishingoperations．PROFESSIONALWORDSANDPHRASEScustomary [5kQstEmErI;(?@)5kQstEmerI] adj.習(xí)慣的，通常的least [li:st] adj.最小的，最少的adv.最少，最小excess [5ekses]n.過度，超過 adj.過度的，額外的deep [di:p] adj.深的coarse [kC:s] adj.粗糙的stand [stAnd] v.站，經(jīng)受downward [5daJnwEd]adj.向下的permit [pE5mIt] v.許可，允許enough [I5nQf]adj.足夠的 n.充足 adv.足夠地allowance [E5laJEns] n.(加工)余量，容差intend [In5tend] vt.想要，打算advisable [Ed5vaIzEbl] adj.可取的，明智的somewhat [5sQmwBt;(?@)-hwBt] adv.稍微，有點correspond [kBrI5spBnd;(?@)kC:rE5spBnd] vi.符合，