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1、刀具與夾具切削加工及刀具是裝備制造業(yè)的基礎(chǔ)工藝, 是制造業(yè)重要工業(yè)部門如汽車工 業(yè)、家電制造業(yè)、航空航天、能源工業(yè)、模具工業(yè)等發(fā)展的關(guān)鍵技術(shù)。 現(xiàn)代切 削技術(shù)經(jīng)過近百年的快速發(fā)展,到 20 世紀(jì)末,隨著數(shù)控機床、數(shù)控系統(tǒng)、刀具 材料、涂層技術(shù)等制造技術(shù)的全面進步, 達到了新的水平, 使切削加工進入了高 速切削的新階段,其主要技術(shù)特征表現(xiàn)為切削速度有510倍的提高。高速切削技術(shù)的出現(xiàn),對制造領(lǐng)域又提出了高要求。一是機床本身剛性、精度高,二是 裝夾系統(tǒng)剛性、 精度高。 三是刀具的材料性能和加工精度要高。 四是冷卻效果要 好。 隨著切削技術(shù)的發(fā)展,對刀具材料的要求在不斷提高,以高性能刀具材料 取代低
2、性能刀具材料, 且應(yīng)用領(lǐng)域擴大已成為趨勢。 如細(xì)顆粒硬質(zhì)合金代替高速 鋼,陶瓷、金屬陶瓷等又取代硬質(zhì)合金,甚至用于流水線生產(chǎn)。PCD 、CBN 超硬材料的應(yīng)用范圍進一步擴大。 采用涂層技術(shù)改變刀具性能的應(yīng)用越來越廣。 材 料行業(yè)通過新的復(fù)合材料,適應(yīng)不同的加工條件,體現(xiàn)出更好的性能。正是各種刀具材料和切削技術(shù)的全面發(fā)展,使切削加工的不同領(lǐng)域 ,不同工序的效率和 總體切削水平有了顯著提高, 開創(chuàng)了切削加工的新階段, 為制造業(yè)的發(fā)展和制造 技術(shù)的進步奠定了基礎(chǔ)。由于Ti(C, N)金屬陶瓷具有更高的熱硬度、更好的抗氧化性和抗高溫蠕變能 力,因此被廣泛用做刀具材料。Ti(C,N)金屬陶瓷刀具材料的主
3、要原料是鈦,鈦 在地球上的貯量為傳統(tǒng)的 WC 基硬質(zhì)合金刀具材料的主要原料 W 的 70 倍,具 有極大的成本和資源優(yōu)勢。因此,Ti(C,N)金屬陶瓷成為近期各國研究的主要刀 具新材料之一。 基于超細(xì)WC基硬質(zhì)合金的使用現(xiàn)狀及 Ti(C,N)基金屬陶瓷刀 具材料的發(fā)展概況、 研究進展, 本文采用 X 射線衍射儀 (XRD) 、掃描電鏡 (SEM)、 透射電鏡(TEM)、電子探針(EPMA)、熱等靜壓燒結(jié)爐(HIP)、低壓燒結(jié)爐(SH)等 對高性能超細(xì)Ti(C,N)金屬陶瓷刀具材料進行了系統(tǒng)研究。首先針對國內(nèi)外在研究細(xì)顆粒Ti(C,N)金屬陶瓷遇到的原料氧含量高,難以獲得優(yōu)質(zhì)細(xì)顆粒Ti(C,N)
4、金屬陶瓷的現(xiàn)狀,分析了超細(xì)原料中氧含量高的原因。用市購平均粒度0.13卩m的TiC_(0.7)N_(0.3)粉末,通過H_2還原爐處理或真空爐處理,獲得了平均粒 度小于0.2 pm、氧含量低于0.3wt %的優(yōu)質(zhì)超細(xì)TiCa.No.3原料。在普通金屬陶瓷的工藝的基礎(chǔ)上,進一步研究了 MoZC, WC, TaC 等添加 成分對 TiCa_No.3 超細(xì)合金性能的影響。針對超細(xì)原料比表面積大、活性高、易于團聚等特點,優(yōu)化了制備超細(xì)金 屬陶瓷混合料的球磨工藝參數(shù) ;采用合適的分散劑改善料漿的粘滯性,使超細(xì) 顆粒表面為活性分子層包圍,獲得好的研磨效果。研究表明,超細(xì)金屬陶瓷在9000C 以下的低溫狀態(tài)
5、發(fā)生了較普通金屬陶瓷激烈得多的固相擴散反應(yīng),這是 使超細(xì)金屬陶瓷芯、環(huán)結(jié)構(gòu)變得復(fù)雜的原因之一 ;在 9000C-12300C 之間的反應(yīng) 較平緩,但從晶格常數(shù)的變化看,其反應(yīng)的程度卻比普通金屬陶瓷的高;在12300C 以后,反應(yīng)又開始激烈,并出現(xiàn)了脫氮反應(yīng)。與不加粘結(jié)相的超細(xì)混合 料的對比研究發(fā)現(xiàn), 在較高溫度時粘結(jié)相對物相的演變起了重要作用, 這些研究 結(jié)果為制定有效的燒結(jié)工藝提供了依據(jù)。根據(jù)超細(xì)金屬陶瓷物相的演變規(guī)律, 修改了常規(guī)燒結(jié)普通金屬陶瓷的工藝路線。由于超細(xì)金屬陶瓷液相的提前出現(xiàn), 必須在較低的溫度下延長燒結(jié)時間以脫除有害的吸附物和低熔點揮發(fā)物。在未 發(fā)生脫氮反應(yīng)之前,采取充氮氣的
6、辦法進行燒結(jié)。由于金屬陶瓷中液相的流動 變得困難,必須采取加壓燒結(jié),以消除孔隙,提高超細(xì)金屬陶瓷的性能。對超細(xì)金屬陶瓷的斷口進行了分析。 統(tǒng)計分析表明, 超細(xì)金屬陶瓷的斷裂源 主要為孔隙,同時還有少量的 Ni 池等。應(yīng)用鈴木壽的強度理論,計算出超細(xì)金 屬陶瓷的本征強度為 5000 MPa ,比實測值高得多。分析表明,主要是孔隙等缺 陷造成了強度下降,并指出,降低孔隙、 Ni 池等缺陷將有利于金屬陶瓷強度的用高分辨率透射電鏡分析了超細(xì)金屬陶瓷和普通金屬陶瓷的微觀組織結(jié) 構(gòu)。兩種金屬陶瓷的組成相是一樣的,主要由 (T i , Mo, Ta, W) (C, N) 固溶體和 Co (Ni)固溶體構(gòu)成,
7、(Ti, Mo, Ta, W) (C, N)固溶體是硬質(zhì)相,Co (Ni)固溶體是粘 結(jié)相。Co (Ni)粘結(jié)相中有納米硬質(zhì)相析出。超細(xì)金屬陶瓷的硬質(zhì)相中有位錯也 有孿晶,最后,將制得的超細(xì)金屬陶瓷刀具同市售的普通金屬陶瓷、日本超細(xì)金屬 陶瓷及 WC 基硬質(zhì)合金 P10 作了對比切削試驗。結(jié)果表明,超細(xì) NT6B 金屬陶 瓷的切削壽命最長,其壽命超過了日本 NX2525 ,是普通市售金屬陶瓷壽命和 WC 基硬質(zhì)合的 2-3 倍。刀具的切削力最小,被加工材料的表面光潔度最高。Tool And FirtureCutting operation and cutting tools is both t
8、he basis of manufacturing industry and the critical technique that influences the development of the important fields of manufacturing industry such as automobiles, household appliances, aerospace, energy and die-making. After around 100 year's rapid development with the advancement in CNC machi
9、ne.CNC system, tool materials and coating technology, etc., modern cutting techniques has entered into a 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 p
10、resented. First is high rigidity and accuracy of the machine itself; Second the high rigidity and accuracy 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 f
11、or tool material is increasing. The traditional tends to be replaced by material by material with better 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 produ
12、ction. The application of PCD, CBEsuper-hard is continously increased. Coating technology is widely used 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 t
13、ool material and cutting technology, the efficiency of different fields os cutting operation and different 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
14、for the development as manufacturing industry and manufacturing technique. Solid cemented carbide high-accuracy 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 materi
15、als and tools.Ti(C,N)-based cermets have been widely used as the tool materials because of its higher red 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
16、times storage in the earth than tungsten, hence Ti(C,N)-based cermets show great advantage in cost and 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 V
17、tC-based cemented carbide being used in cutting tool materials, and development and progress of Ti(C,N)-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 diffracto
18、meter (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), electron probe (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
19、 crux that high-performance cermets containing ultra-fine particles Ti(C,N) is hard to obtain due to the 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 p
20、repared adopting the conventional TiCo.7 powder which average size is 0.13),m by means of a treatment 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 ha
21、s been further investigated.Considering that the ultra-fine particle features high specific surface, high activity 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
22、that the ultra-fine grains can be covered by a layer of active material, thus leading to excellent milling 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 i
23、s one of the reasons that makes the core-rim structure of ultra-fine become rather complicated. It seemsthat 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 bec
24、ome intense again at the temperature above 12300C, and it could be deduced that the reaction between liquid 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 definit
25、ely has very important role in the evolvement of phases, and the phase evolvement provides a basis for optimization of technology. Based on the evolvement rule for the phasesin the ultra-fine cermet, the conventional sintering technology for the common cermet has been optimized. As the liquid phase
26、appears in advance, the sintering time has to be kept longer to remove the harmful adhesive and volatile, 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
27、 in the ultra-fine cennet pressure sintering is used to eliminate the porosity to upgrade the properties 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
28、-lakes. Using Mr. Hisashi Suzuki's strength theory, the essential strength of ultra-fine cermet is calculated 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 t
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