外文翻译--刀具与夹具.doc

刀具与夹具切削加工及刀具是装备制造业的基础工艺，是制造业重要工业部门如汽车工业、家电制造业、航空航天、能源工业、模具工业等发展的关键技术。现代切削技术经过近百年的快速发展，到20世纪末，随着数控机床、数控系统、刀具材料、涂层技术等制造技术的全面进步，达到了新的水平，使切削加工进入了高速切削的新阶段，其主要技术特征表现为切削速度有510倍的提高。高速切削技术的出现，对制造领域又提出了高要求。一是机床本身刚性、精度高，二是装夹系统刚性、精度高。三是刀具的材料性能和加工精度要高。四是冷却效果要好。随着切削技术的发展，对刀具材料的要求在不断提高，以高性能刀具材料取代低性能刀具材料，且应用领域扩大已成为趋势。如细颗粒硬质合金代替高速钢，陶瓷、金属陶瓷等又取代硬质合金，甚至用于流水线生产。PCD、CBN超硬材料的应用范围进一步扩大。采用涂层技术改变刀具性能的应用越来越广。材料行业通过新的复合材料，适应不同的加工条件，体现出更好的性能。正是各种刀具材料和切削技术的全面发展，使切削加工的不同领域,不同工序的效率和总体切削水平有了显著提高，开创了切削加工的新阶段，为制造业的发展和制造技术的进步奠定了基础。由于Ti(C，N)金属陶瓷具有更高的热硬度、更好的抗氧化性和抗高温蠕变能力，因此被广泛用做刀具材料。Ti(C，N)金属陶瓷刀具材料的主要原料是钛，钛在地球上的贮量为传统的WC基硬质合金刀具材料的主要原料W的70倍，具有极大的成本和资源优势。因此，Ti(C，N)金属陶瓷成为近期各国研究的主要刀具新材料之一。基于超细WC基硬质合金的使用现状及Ti(C，N)基金属陶瓷刀具材料的发展概况、研究进展，本文采用X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、电子探针(EPMA)、热等静压烧结炉(HIP)、低压烧结炉(SH)等对高性能超细Ti(C，N)金属陶瓷刀具材料进行了系统研究。首先针对国内外在研究细颗粒Ti(C，N)金属陶瓷遇到的原料氧含量高，难以获得优质细颗粒Ti(C，N)金属陶瓷的现状，分析了超细原料中氧含量高的原因。用市购平均粒度0.13m的TiC_(0.7)N_(0.3)粉末，通过H_2还原炉处理或真空炉处理，获得了平均粒度小于0.2m、氧含量低于0.3wt的优质超细TiCa.No.3原料。在普通金属陶瓷的工艺的基础上，进一步研究了MoZC,WC,TaC等添加成分对TiCa_No.3超细合金性能的影响。针对超细原料比表面积大、活性高、易于团聚等特点，优化了制备超细金属陶瓷混合料的球磨工艺参数；采用合适的分散剂改善料浆的粘滞性，使超细颗粒表面为活性分子层包围，获得好的研磨效果。研究表明，超细金属陶瓷在9000C以下的低温状态发生了较普通金属陶瓷激烈得多的固相扩散反应，这是使超细金属陶瓷芯、环结构变得复杂的原因之一；在9000C-12300C之间的反应较平缓，但从晶格常数的变化看，其反应的程度却比普通金属陶瓷的高；在12300C以后，反应又开始激烈，并出现了脱氮反应。与不加粘结相的超细混合料的对比研究发现，在较高温度时粘结相对物相的演变起了重要作用，这些研究结果为制定有效的烧结工艺提供了依据。根据超细金属陶瓷物相的演变规律，修改了常规烧结普通金属陶瓷的工艺路线。由于超细金属陶瓷液相的提前出现，必须在较低的温度下延长烧结时间以脱除有害的吸附物和低熔点挥发物。在未发生脱氮反应之前，采取充氮气的办法进行烧结。由于金属陶瓷中液相的流动变得困难，必须采取加压烧结，以消除孔隙，提高超细金属陶瓷的性能。对超细金属陶瓷的断口进行了分析。统计分析表明，超细金属陶瓷的断裂源主要为孔隙，同时还有少量的Ni池等。应用铃木寿的强度理论，计算出超细金属陶瓷的本征强度为5000MPa，比实测值高得多。分析表明，主要是孔隙等缺陷造成了强度下降，并指出，降低孔隙、Ni池等缺陷将有利于金属陶瓷强度的提高。用高分辨率透射电镜分析了超细金属陶瓷和普通金属陶瓷的微观组织结构。两种金属陶瓷的组成相是一样的，主要由(Ti,Mo,Ta,W)(C,N)固溶体和Co(Ni)固溶体构成，(Ti,Mo,Ta,W)(C,N)固溶体是硬质相，Co(Ni)固溶体是粘结相。Co(Ni)粘结相中有纳米硬质相析出。超细金属陶瓷的硬质相中有位错也有孪晶，最后，将制得的超细金属陶瓷刀具同市售的普通金属陶瓷、日本超细金属陶瓷及WC基硬质合金P10作了对比切削试验。结果表明，超细NT6B金属陶瓷的切削寿命最长，其寿命超过了日本NX2525，是普通市售金属陶瓷寿命和WC基硬质合的2-3倍。刀具的切削力最小，被加工材料的表面光洁度最高。ToolAndFirtureCuttingoperationandcuttingtoolsisboththebasisofmanufacturingindustryandthecriticaltechniquethatinfluencesthedevelopmentoftheimportantfieldsofmanufacturingindustrysuchasautomobiles,householdappliances,aerospace,energyanddie-making.Afteraround100yearsrapiddevelopmentwiththeadvancementinCNCmachine.CNCsystem,toolmaterialsandcoatingtechnology,etc.,moderncuttingtechniqueshasenteredintoanewstageofhigh-speedcuttingwhichischaracterizedby510timesincreaseofcuttingspeed.Withtheintroductionofhigh-speedcutting,thehigherrequirementsformanufacturingindustryispresented.Firstishighrigidityandaccuracyofthemachineitself；Secondthehighrigidityandaccuracyoftheclampingsystem；Thirdthegoodpropertiesoftoolmaterialsandhighmachiningaccuracy；andthelast,goodcoolingeffect.Withthedevelopmentofcuttingtechnique,therequirementsfortoolmaterialisincreasing.Thetraditionaltendstobereplacedbymaterialbymaterialwithbetterperformaceandtobewidelyused.Forexample,high-speedsteelistobereplacedbyfine-graincementedcarbide,cementedcarbidetobereplacedbyceramic.Thisispracticalevenformassproduction.TheapplicationofPCD,CBEsuper-hardiscontinouslyincreased.Coatingtechnologyiswidelyusedtoimprovetheperformanceoftools.Inmaterialindustrynewcompositematerialisappliedrelativetodifferentcuttingoperationstogetbetterperformance.Thankstothedevelopmentinbothtoolmaterialandcuttingtechnology,theefficiencyofdifferentfieldsoscuttingoperationanddifferentworkingprocedureofcuttingoperationandthegeneralcuttingtechnologyaswellaresubstantiallyimproved；thecuttingoperationhasenteredintoanewstage；asolidfoundationhasbeenlaidforthedevelopmentasmanufacturingindustryandmanufacturingtechnique.Solidcementedcarbidehigh-accuracysurfacebroachingtoolisdevelopedformachiningthegroovesonthevanesofair-condetionercompressorinthisstudy,whichrepresentingthedevelopingorientationofcurrenttoolmaterialsandtools.Ti(C,N)-basedcermetshavebeenwidelyusedasthetoolmaterialsbecauseofitshigherredhardness,betterresistancetooxidation,andbetterresistancetocreepathightemperature.ThekeyalloyingelementusedinTi(C,N)-basedcermetstoolmaterialsistitaniumthathasabout70timesstorageintheearththantungsten,henceTi(C,N)-basedcermetsshowgreatadvantageincostandresourcesmorethanthatofthetraditionalWC-basedcementedcarbideandbecomeoneofthenewandmaintoolmaterialswhichhavebeingdevelopedintheglobe.Basedonareviewoftheultra-fineVtC-basedcementedcarbidebeingusedincuttingtoolmaterials,anddevelopmentandprogressofTi(C,N)-basedcermetstoolmaterials,ahigh-performanceultra-fineTi(C,N)-basedcementedcarbidehasbeenstudiedsystematicallyinthisdissertationusingallkindsofapparatussuchasX-raydiffractometer(XRD),scanningelectronmicroscope(SEM),transmissionelectronmicroscope(TEM),electronprobe(EPMA),hotisostaticpressmachine(HIP),low-pressuresinteringmachine(SH),etc.Atfirst,thereasonwhyoxygencontentishighinrawmaterialhasbeendeeplyanalyzedinordertosurmountthecruxthathigh-performancecermetscontainingultra-fineparticlesTi(C,N)ishardtoobtainduetothehighcontentofoxygeninrawmaterials,thenahigh-performancerawTi(C,N)powderwhichaveragesizeofparticleTiCo.7N0.3islessthan0.2umandoxygencontentislowerthan0.3wt%hasbeenpreparedadoptingtheconventionalTiCo.7powderwhichaveragesizeis0.13),mbymeansofatreatmentinvacuumfurnaceorinhydrogen-deoxidizationfurnace.Onthebasisofcommonproductionprocessofcermet,theeffectofadditionsuchasMoZC,WC,TaConthepropertiesoftheultra-finecermethasbeenfurtherinvestigated.Consideringthattheultra-fineparticlefeatureshighspecificsurface,highactivityandbeingeasytopileup,thetechnologyofwetballmillingfortheultra-finepowderhasbeenoptimizedandacertaindispersantisadoptedtoimprovethestickinessoftheslurrysothattheultra-finegrainscanbecoveredbyalayerofactivematerial,thusleadingtoexcellentmillingbehavior.Theresultsinvestigatedindicatethattheultra-finecermetwouldhavemuchmoreabilitytooccursoliddiffusionreactionthancommoncertnetatthelowertemperatureof9000C.Itisoneofthereasonsthatmakesthecore-rimstructureofultra-finebecomerathercomplicated.Itseemsthatthereactionbecamemilderat900-12300C,butthedegreeofreactionshouldbehigherthanthecommoncennetaccordingtothechangesofthelatticeparameter.However,thereactionwouldbecomeintenseagainatthetemperatureabove12300C,anditcouldbededucedthatthereactionbetweenliquidphasesoccursinadvancewhilethedenitrogenizationreactionappears.Comparedwiththeresultobtainedintheultra-finepowderwithoutbinder-phase,itisshownthatthebinder-phasedefinitelyhasveryimportantroleintheevolvementofphases,andthe