完整版毕业设计机械外文翻译.docx

完整版毕业设计机械外文翻译.docx

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完整版毕业设计机械外文翻译

附录1：

外文原文

Themachinabilityofmaterial

Themachinabilityofamaterialusuallydefinedintermsoffourfactors:

（1）.Surfacefinishandintegrityofthemachinedpart;

（2）.Toollifeobtained;

（3）.Forceandpowerrequirements;

（4）.Chipcontrol.

Thus,goodmachinabilitygoodsurfacefinishandintegrity,longtoollife,andlowforceAndpowerrequirements.Asforchipcontrol,longandthin（stringy）curedchips,ifnotbrokenup,canseverelyinterferewiththecuttingoperationbybecomingentangledinthecuttingzone.

Becauseofthecomplexnatureofcuttingoperations,itisdifficulttoestablishrelationshipsthatquantitativelydefinethemachinabilityofamaterial.Inmanufacturingplants,toollifeandsurfaceroughnessaregenerallyconsideredtobethemostimportantfactorsinmachinability.Althoughnotusedmuchanymore,approximatemachinabilityratingsareavailableintheexamplebelow.

1.MachinabilityOfSteels

Becausesteelsareamongthemostimportantengineeringmaterials,theirmachinabilitystudiedextensively.Themachinabilityofsteelsmainlyimprovedbyaddingleadandsulfurtoobtainso-calledfree-machiningsteels.

ResulfurizedandRephosphorizedsteels.Sulfurinsteelsformsmanganesesulfideinclusions（second-phaseparticles）,whichactasstressraisersintheprimaryshearzone.Asaresult,thechipsproducedbreakupeasilyandaresmall;thisimprovesmachinability.Thesize,shape,distribution,andconcentrationoftheseinclusionssignificantlyinfluencemachinability.Elementssuchastelluriumandselenium,whicharebothchemicallysimilartosulfur,actasinclusionmodifiersinresulfurizedsteels.

Phosphorusinsteelsbetterchipformationandsurfacefinish.Notethatsoftsteelscanbedifficulttomachine,withbuilt-upedgeformationandpoorsurfacefinish.Thesecondeffectisthatincreasedofshortchipsinsteadofcontinuousstringyones,therebyimprovingmachinability.

LeadedSteels.Asteelssolidifiesatthetipofmanganesesulfideinclusions.Innon-resulfurizedgradesofsteel,leadtakestheformofdispersedfineparticles.Leadisinsolubleiniron,copper,andaluminumandtheiralloys.Becauseofitslowshearstrength,therefore,leadactsasasolidlubricantandissmearedoverthetool-chipinterfaceduringcutting.Thisbehaviorverifiedbythepresenceofthetool-sidefaceofchipswhenmachiningleadedsteels.

Whenthetemperatureissufficientlyfrontofthetool,actingasaliquidlubricant.Inadditiontothiseffect,leadlowerstheshearstressintheprimaryshearzone,reducingcuttingforcesandpowerconsumption.Leadcanbeusedineverygradeofsteel,suchas10xx,11xx,12xx,41xx,etc.LeadedsteelsareidentifiedbytheletterLbetweenthesecondandthirdnumerals（forexample,10L45）.（Notethatinstainlesssteels,similaruseoftheletterLmeans“lowcarbon,”aconditionthatimprovestheircorrosionresistance.）

However,becauseleadisawell-knowntoxinandapollutant,thereareseriousenvironmentalconcernsaboutitsuseinsteels（estimatedat4500tonsofleadconsumptioneveryyearintheproductionofsteels）.Consequently,thereisacontinuingtrendtowardeliminatingtheuseofleadinsteels（lead-freesteels）.Bismuthandtinarenowbeinginvestigatedaspossiblesubstitutesforleadinsteels.

Calcium-DeoxidizedSteels.Animportantdevelopmentiscalcium-deoxidizedsteels,inwhichoxideflakesofcalciumsilicates（CaSo）areformed.Theseflakes,inturn,reducethestrengthofthesecondaryshearzone,decreasingtool-chipinterfaceandwear.Temperatureiscorrespondinglyreduced.Consequently,thesesteelsproducelesscraterwear,especiallyatbesproblem,necessitatingmachinetoolswith--resistanttoolmaterials.

TheEffectsofOtherElementsinSteelsonMachinability.Thepresenceofaluminumandsiliconinsteelsisalwaystoformaluminumoxideandsilicates,whicharesteels.

Carbonandmanganesethemachinabilityofsteels,dependingontheircomposition.Plainlow-carbonsteels（lessthan0.15%C）canproducepoorsurfacefinishbyformingabuilt-upedge.Caststeelsaremoreabrasive,althoughtheirmachinabilityissimilartothatofwroughtsteels.Toolanddiesteelsareverydifficulttomachineandusuallyrequireannealingpriortomachining.Machinabilityofmoststeelsisimprovedbycoldworking,which.

Otheralloyingelements,suchasnickel,chromium,molybdenum,andvanadium,whichimprovethepropertiesofsteels,generallyreducemachinability.Theeffectofboronisnegligible.Gaseouselementssuchasandnitrogencanthepropertiesofsteel.Oxygenshowntotheaspectratioofthemanganesesulfideinclusions;thecontent,thelowertheaspectratioandtheselectingvariouselementstoimprovemachinability,weshouldconsiderthepossibledetrimentaleffectsoftheseelementsonthepropertiesandstrengthofthemachinedpartinservice.Atelevatedtemperatures,forexample,leadcausesembrittlementofsteels（liquid-metalembrittlement,mechanicalproperties.

Sulfurcanseverelyreducetheofironsulfide,unlesssufficientmanganeseispresenttopreventsuchformation.Atroomtemperature,themechanicalpropertiesofresulfurizedsteelsdependontheorientationofthedeformedmanganesesulfideinclusions（anisotropy）.Rephosphorizedsteelsaresignificantlylessductile,andareproducedsolelytoimprovemachinability.

2.MachinabilityofVariousOtherMetals

Aluminumisgenerallyveryeasytomachine,althoughthesoftergradestendtoformabuilt-upedge,resultinginpoorsurfacefinish.Highcuttingspeeds,contentandcastaluminumalloysmaybeabrasive;theyrequiremachiningaluminum,sinceitandarelativelylowelasticmodulus.

Berylliumissimilartocastirons.Becauseitismoreabrasiveandtoxic,though,itrequiresmachininginacontrolledenvironment.

Castgrayironsaregenerallymachinablebutare.Freecarbidesincastingsreducetheirmachinabilityandcausetoolchippingorfracture,necessitatingtoolswith-resistanttoolmaterialsandlowfeedsandspeeds.

Wroughtcoppercanbedifficulttomachinebecauseofbuilt-upedgeformation,althoughcastcopperalloysareeasytomachine.Brassesareeasytomachine,especiallywiththeadditionpflead（leadedfree-machiningbrass）.Bronzesaremoredifficulttomachinethanbrass.

Magnesiumisveryeasytomachine,withgoodsurfacefinishandprolongedtoollife.Howevercareshouldbeexercisedbecauseofitsandthedangeroffire（theelementispyrophoric）.

Molybdenumisductileandwork-producepoorsurfacefinish.Sharptoolsarenecessary.

Nickel-basedalloysarework-bedifficulttomachine.

Tungstenisbrittle,strong,andveryabrasive,soitsmachinabilityislow,althoughitgreatlyimprovesatelevatedtemperatures.

Zirconiumandfire.

3.MachinabilityofVariousMaterials

Graphiteisabrasive;itrequires-resistant,sharptools.

Thermoplasticsgenerallyusuallybeachievedwithajetofair,vapormist,orwater-solubleoils.Residualstressesmaydevelopduringmachining.Torelievethesestresses,machinedpartscanbeannealedforaperiodoftimeattemperaturesrangingfromto（to）,andthencooledslowlyanduniformlytoroomtemperature.

Thermosettingplasticsarebrittleandsensitivetothermalgradientsduringcutting.Theirmachinabilityisgenerallysimilartothatofthermoplastics.

Becauseofthefiberspresent,reinforcedplasticsareveryabrasiveandaredifficulttomachine.Fibertearing,pulling,andedgedelaminationaresignificantproblems;theycanleadtoseverereductionintheload-carryingcapacityofthecomponent.Furthermore,machiningofthesematerialsrequirescarefulremovalofmachiningdebristoavoidcontactwithandinhalingofthefibers.

Themachinabilityofceramicsofappropriateprocessingparameters,suchasductile-regimecutting.

Metal-matrixandceramic-matrixcompositescanbedifficulttomachine,dependingonthepropertiesoftheindividualcomponents,i.e.,reinforcingorwhiskers,aswellasthematrixmaterial.

4.ThermallyAssistedMachining

Metalsandalloysthataredifficulttomachineatroomtemperaturecanbemachinedmoreeasilyatelevatedtemperatures.Inthermallyassistedmachining（coil,beam）,orplasmaarc—isforces,（b）increasedtoollife,（c）useofinexpensivecutting-toolmaterials,（d）andchatter.

Itmaybedifficulttoauniformtemperaturedistributionwithintheworkpiece.Also,theoriginalmicrostructureoftheworkpiecemaybeadverselyaffectedbyelevatedtemperatures.Mostapplicationsoftheturningofprogresstomachineceramicssuchassiliconnitride.

SUMMARY

Machinabilityisusuallydefinedintermsofsurfacefinish,toollife,forceandpowerrequirements,andchipcontrol.Machinabilityofmaterialsdependsnotonlyontheirintrinsicpropertiesandmicrostructure,butalsoonproperselectionandcontrolofprocessvariables.

附录2：

外文中文翻译

材料的可机加工性

一种材料的可机加工性通常以四种因素的方式定义：

（1）、分的表面光洁性和表面完整性。

（2）、刀具的寿命。

（3）、切削力和功率的需求。

（4）、切屑控制。

以这种方式，好的可机加工性指的是好的表面光洁性和完整性，长的刀具寿命，低的切削力和功率需求。

关于切屑控制，细长的卷曲切屑，如果没有被切割成小片，以在切屑区变的混乱，缠在一起的方式能够严重的介入剪切工序。

因为剪切工序的复杂属性，所以很难建立定量地释义材料的可机加工性的关系。

在制造厂里，刀具寿命和表面粗糙度通常被认为是可机加工性中最重要的因素。

尽管已不再大量的被使用，近乎准确的机加工率在以下的例子中能够被看到。

1.钢的可机加工性

因为钢是最重要的工程材料之一，所以他们的可机加工性已经被广泛地研究过。

通过宗教铅和硫磺，钢的可机加工性已经大大地提高了。

从而得到了所谓的易切削钢。

二次硫化钢和二次磷化钢硫在钢中形成硫化锰夹杂物（第二相粒子），这些夹杂物在第一剪切区引起应力。

其结果是使切屑容易断开而变小，从而改善了可加工性。

这些夹杂物的大小、形状、分布和集中程度显著的影响可加工性。

化学元素如碲和硒，其化学性质与硫类似，在二次硫化钢中起夹杂物改性作用。

钢中的磷有两个主要的影响。

它加强铁素体，增加硬度。

越硬的钢，形成更好的切屑形成和表面光洁性。

需要注意的是软钢不适合用于有积屑瘤形成和很差的表面光洁性的机器。

第二个影响是增加的硬度引起短切屑而不是不断的细长的切屑的形成，因此提高可加工性。

含铅的钢钢中高含量的铅在硫化锰夹杂物尖端析出。

在非二次硫化钢中，铅呈细小而分散的颗粒。

铅在铁、铜、铝和它们的合金中是不能溶解的。

因为它的低抗剪强度。

因此，铅充当固体润滑剂并且在切削时，被涂在刀具和切屑的接口处。

这一特性已经被在机加工铅钢时，在切屑的刀具面表面有高浓度的铅的存在所证实。

当温度足够高时—例如，在高的切削速度和进刀速度下—铅在刀具前直接熔化，并且充当液体润滑剂。

除了这个作用，铅降低第一剪切区中的剪应力，减小切削力和