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1、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
2、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
3、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
4、_(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
5、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
6、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5000 MPa，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(T i , 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，
7、 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。Tool And FirtureCutting operation and cutting tools is both the basis of manufacturing industry and the critical technique that influences the development of th
8、e important fields of manufacturing industry such as automobiles, household appliances, aerospace, energy and die-making. After around 100 years rapid development with the advancement in CNC machine.CNC system, tool materials and coating technology, etc., modern cutting techniques has entered into a
9、 new stage of high-speed cutting which is characterized by 510 times increase of cutting speed. With the introduction of high-speed cutting, the higher requirements for manufacturing industry is presented. First is high rigidity and accuracy of the machine itself; Second the high rigidity and accura
10、cy of the clamping system; Third the good properties of tool materials and high machining accuracy; and the last, good cooling effect. With the development of cutting technique, the requirements for tool material is increasing. The traditional tends to be replaced by material by material with better
11、 performace and to be widely used. For example, high-speed steel is to be replaced by fine-grain cemented carbide, cemented carbide to be replaced by ceramic. This is practical even for mass production. The application of PCD, CBEsuper-hard is continously increased. Coating technology is widely used
12、 to improve the performance of tools. In material industry new composite material is applied relative to different cutting operations to get better performance. Thanks to the development in both tool material and cutting technology, the efficiency of different fields os cutting operation and differe
13、nt working procedure of cutting operation and the general cutting technology as well are substantially improved; the cuttingoperation has entered into a new stage; a solidfoundation has been laid for the development as manufacturing industry and manufacturing technique. Solid cemented carbide high-a
14、ccuracy surface broaching tool is developed for machining the grooves on the vanes of air-condetioner compressor in this study, which representing the developing orientation of current tool materials and tools. Ti(C,N)-based cermets have been widely used as the tool materials because of its higher r
15、ed hardness, better resistance to oxidation, and better resistance to creep at high temperature. The key alloying element used in Ti(C,N)-based cermets tool materials is titanium that has about 70 times storage in the earth than tungsten, hence Ti(C,N)-based cermets show great advantage in cost and
16、resources more than that of the traditional WC-based cemented carbide and become one of the new and main tool materials which have being developed in the globe.Based on a review of the ultra-fine VtC-based cemented carbide being used in cutting tool materials, and development and progress of Ti(C,N)
17、-based cermets tool materials, a high-performance ultra-fine Ti(C,N)-based cemented carbide has been studied systematically in this dissertation using all kinds of apparatus such as X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), electron probe
18、 (EPMA), hot isostatic press machine(HIP), low-pressure sintering machine (SH), etc. At first, the reason why oxygen content is high in raw material has been deeply analyzed in order to surmount the crux that high-performance cermets containing ultra-fine particles Ti(C,N) is hard to obtain due to t
19、he high content of oxygen in raw materials, then a high-performance raw Ti(C,N) powder which average size of particle TiCo.7N0.3 is less than 0.2um and oxygen content is lower than 0.3wt% has been prepared adopting the conventional TiCo.7 powder which average size is 0.13),m by means of a treatment
20、in vacuum furnace or in hydrogen-deoxidization furnace.On the basis of common production process of cermet, the effect of addition such as MoZC, WC, TaC on the properties of the ultra-fine cermet has been further investigated.Considering that the ultra-fine particle features high specific surface, h
21、ighactivity and being easy to pileup, the technology of wet ball milling for the ultra-fine powder has been optimized and a certain dispersant is adopted to improve the stickiness of the slurry so that the ultra-fine grains can be covered by a layer of active material, thus leading to excellent mill
22、ing behavior. The results investigated indicate that the ultra-fine cermet would have much more ability to occur solid diffusion reaction than common certnet at the lower temperature of 9000C. It is one of the reasons that makes the core-rim structure of ultra-fine become rather complicated. It seem
23、s that the reaction became milder at 900-12300C, but the degree of reaction should be higher than the common cennet according to the changes of the lattice parameter. However, the reaction would become intense again at the temperature above 12300C, and it could be deduced that the reaction between l
24、iquid phases occurs in advance while the denitrogenization reaction appears. Compared with the result obtained in the ultra-fine powder without binder-phase, it is shown that the binder-phase definitely has very important role in the evolvement of phases, and the phase evolvement provides a basis fo
25、r optimization of technology. Based on the evolvement rule for the phases in the ultra-fine cermet, the conventional sintering technology for the common cermet has been optimized. As the liquid phase appears in advance, the sintering time has to be kept longer to remove the harmful adhesive and vola
26、tile, which have lower melt point. Certain NZ gas has to be supplemented in the sintering process to avoid appearance of the denitrogenization reaction. As it is difficult for the liquid phase to flow in the ultra-fine cennet pressure sintering is used to eliminate the porosity to upgrade the proper
27、ties of ultra-fine cermet.The fracture of the ultra-fine cermet has been analyzed systematically. The results show that rupture usually occurs can be attributed to the porosities or some very small Ni-lakes. Using Mr. Hisashi Suzukis strength theory, the essential strength of ultra-fine cermet is ca
28、lculated to be 5000 MPa much higher than thetesting data, the reason that the testing data is more Lower than the calculated value is closely related to some faults such as porosities. So, the strength of ultra-fin cermet would be highly improved with decreasing the amount of faults like porosities
29、and Ni-lakes, etc.TEM analysis of the microstructure for both cermets shows that cermet is made up of hard phase, which is (Ti, Mo, Ta, W) (C, N)，and binder phase, which i s Co (Ni)，while a newly nano-precipitate coherent with matrix appears in the binder phase. There exist not only dislocations but
30、 also twins in the hard phase of ultra-fine cermet.At last, a performance comparison test between the ultra-fine cermet tips made by the new process and the common cermet tips sold in the market and Japanese ultra-fine cermet tips and WC-based cemented carbide tips of grade P10 has been made. The te
31、st results show that the ultra-fine cermet NT6B has the longest lifetime in use, even longer than the Japanese NX2525, 2 to 3 times lifetime than the common cermet tips sold in the market and the WC-based tips, and has the lowest cutting obstruction and best smooth surface on the manufactured materials.
