Si_3N_4基复合陶瓷刀具切削温度场及热应力的有限元分析

应用有限元法对Si3N4基复合陶瓷刀具温度场和热应力进行了分析计算。通过建立Si3N4基复合陶瓷刀具三维温度场和热应力的有限元模型,确定边界条件,分析求解得到Si3N4复合陶瓷刀具的温度场和热应力。结果表明:普通单质陶瓷刀具随着切削速度的提高,其由切削温度引起的最大热Mises应力、最大热切应力以及最大热拉应力的增长幅度大于Si3N4基复合陶瓷刀具。说明Si3N4基复合陶瓷刀具由热应力引起的破坏比单质陶瓷刀具小,寿命长,更适合于高速切削。     

高速车削条件下复合陶瓷刀具的寿命试验研究

为研究新型复合陶瓷刀具干切削高强度钢的切削性能,在切削用量范围:vc=90~314 m/min,f=0.02~0.4 mm/r,ap=0.2~3 mm范围内,应用析因统计试验设计与单因素试验设计,使用Al2O3+Ti C和Al2O3+Ti C+Si3N4复合陶瓷刀具对高强度钢35Cr Mn Si A进行了高速干式车削试验。在分析了刀具寿命显著性影响因素的基础上,研究了后刀面磨损量VB值与切削速度、进给量和背吃刀量之间的变化规律。试验研究表明:复合陶瓷高速切削高强度钢工件材料时,选择VB=0.2 mm作为刀具的磨钝标准较为合理;在保证刀具破损可靠度和加工质量的前提下,应选取尽可能大的进给量与背吃刀量;对于35Cr Mn Si A材料而言,Al2O3+Ti C陶瓷刀具较Al2O3+Ti C+Si3N4陶瓷刀具的切削性能好。     

TiCN基硬质合金刀具切削性能与切削机理研究

通过系统地切削试验，研究了TiCN基新型硬质合金刀具在耐磨性、抗冲击性、切削力、刀一屑摩擦系数、加工表面质量等方面的切削性能特点；并通过一定的理论分析，探讨了TiCN基硬质合金综合性能优越的切削机理。研究所得大量切削试验数据及回归经验公式等，可供TiCN基硬质合金刀具推广应用时参考。     

煤矿大型高锰钢托轮的切削试验研究

采用新型复合SiC、复合Si3N4和TiN涂层刀具对用于露天煤矿大型拖轮的高锰钢进行了切削加工对比研究，测量了切削温度、后刀面磨损量与切削时间或切削速度的关系曲线，以及刀具前、后刀面显微磨损、破损形貌和化学变化。试验表明，复合SiC是切削高锰钢的较理想的刀具，在切削效率和经济效益上均优于TiN涂层刀具和复合Si2N4刀具。     

脉冲高能量密度等离子体陶瓷刀具表面改性研究进展

对刀具涂层技术的发展现状与趋势进行了综述,提出了提高涂层刀具性能的"五化"措施:沉积工艺复合化、薄膜组成多元化、薄膜结构多层化、薄膜组成和显微结构梯度化、薄膜晶粒纳米化.基于这个思想,提出了用高能量密度脉冲等离子体技术进行陶瓷刀具表面改性,并在最近几年用高能量密度脉冲等离子体同轴枪对硬质合金和氮化硅陶瓷刀具进行了镀膜改性尝试.使用该复合表面改性技术,所制备涂层刀具结构独特,很好地满足了"五化"思想,材料性能得到显著提高.在优化的工艺条件下,所得TiN、TiCN和TiAlN涂层刀具硬度高,纳米硬度分别为26～28 Gpa、50～53 Gpa和38～40 Gpa;膜基结合力强,纳米划痕临界载荷达80～110 Mn.所得TiN、TiCN和(Ti,Al)N涂层硬质合金刀具能够在工业条件下对硬度高达HRC 58～62 的淬硬CrWMn钢进行干切削,实用切削速度可提高2～10倍,且刀具磨损较小;涂层氮化硅陶瓷刀具加工淬硬钢和灰铸铁(HB 2200～2300 Mpa)工件时,比未涂层刀具后面磨损降低6～10倍.预示该技术是一种非常有前途的陶瓷刀具改性技术.     

金属陶瓷刀具切削淬火钢的磨损机理研究

利用真空烧结工艺制备了纳米复合TI(C,N)基金属陶瓷刀片.进行淬火态45#钢的单因素切削试验,并利用SEM,EPMA对金属陶瓷刀具的磨损失效机理进行了研究.结果表明纳米复合TI(C,N)基金属陶瓷刀片在切削淬火态45#钢时表现出较高的耐磨性和切削性能,其主要的磨损失效机理是压应力下的挤压变形和粘附磨损,同时伴随一定的氧化磨损和扩散磨损.     

切削刀具表面TiCN涂层的研究现状与发展

近年来,我国汽车产业迅猛发展,汽车机械零部件的需求给我国切削加工业带来了发展机遇和挑战.汽车安全性和舒适性的要求,国家节能减排、绿色制造的发展战略,指引切削技术向高速、高效、高精、绿色、智能方向发展,对刀具材料的使用性能也提出了更高要求.TiCN涂层刀具因具有高硬度和高耐磨性被大量应用,尤其是在有色金属及合金的切削加工上具有明显优势.综述了TiCN涂层的微观结构,指出C原子具有细化晶粒和抑制柱状晶形成的作用,涂层的结晶度和择优取向随C含量的改变而变化.总结了TiCN涂层的主要性能特点,包括硬度和致硬机理、耐磨性和减摩机理、热稳定性和热失效机制.介绍了TiCN涂层的沉积原理,指出各种制备方法的优缺点和关键工艺参数.分析了以TiCN为基进行改性获得的涂层的国内外最新研究现状,提出对TiCN涂层进行多层化、多元化以及纳米多层化,是进一步提高该涂层在高温条件下综合性能的方法,也是该涂层为适应高速切削、干式切削等新切削技术要求的发展方向.     

TiAlN涂层与Al_2O_3复合涂层刀具高温合金切削性能研究

为提升高温合金加工刀具的加工质量与效率,设计制备了用于金属陶瓷刀具的TiN/Al_2O_3/TiC/TiCN复合涂层(Al_2O_3复合涂层)与用于硬质合金刀具的TiAlN涂层。开展了进给量为单因素变量的切削实验,并从切削力变化、刀具磨损情况及被加工表面质量三方面验证对比刀具的切削性能。试验表明,涂层刀具的刃口钝化处理导致了其加工过程切削力的升高,其中TiAlN涂层硬质合金刀具切削力变化较平稳;Al_2O_3复合涂层刀具加工过程中出现了涂层剥落现象,而TiAlN涂层刀具磨损较小;TiAlN涂层硬质合金刀具获得的加工表面质量优于Al_2O_3复合涂层刀具。TiAlN涂层硬质合金刀具在耐磨性、涂层粘着力及加工质量三方面均优于Al_2O_3复合涂层金属陶瓷刀具。     

ST系列新型复合陶瓷刀具推出

全国高技术产业化协作组织 (ＣＨＣ)推出了ＳＴ系列新型复合陶瓷刀具 ,它具有国内外领先水平。该系列刀具由于采用了特殊的配方和生产工艺 ,因而具有高强度、高韧性、高耐磨性及红硬性、抗热震性等高温性能和抗冲击性、化学稳定性等其它综合性能。这些优异的性能使ＳＴ系列新型复合陶瓷刀具具有国内领先地位 ,与国外同类陶瓷刀片相比 ,其抗弯强度、断裂韧性、耐磨性、抗氧化性和化学稳定性等主要性能指标优于国外产品。使用ＳＴ系列新型复合陶瓷刀具加工高硬度合金铸铁和淬硬钢等难切削材料 ,不但能用于精加工和半精加工 ,而且能用于粗加工…     

选用最佳硬质合金进行难加工材料的高效切削

在工业生产中,各种机械零件、部件采用高强度钢、淬火钢、耐热铁、高温合金、高硬铸铁、钛合金等材料日益增多。加工这些材料,刀具不仅磨损快而且易打刀,切削效率很低,因此这些材料被称为难加工材料。研究这些材料的加工性,发展新型刀具材料,合理选取切削用量,提高这些难加工材料的切削效率有重大现实意义。近年来自贡和株州硬质合金厂等发展了多种新牌号的硬质合金并已在生产中推广使用。用硬质合金加工钢时,低速切削时刀具的磨损是以磨料磨损和粘结磨损为主;而在高速切削时刀具以扩散磨损和氧化磨损为主,还会     

Cutting performance of solid ceramic end milling tools in machining hardened AISI H13 steel

Ceramic tools have been widely used in the cutting of hard-to-machine materials, but the applications of solid ceramic milling cutters are limited due to their design and manufacturing restrictions. This research investigates the cutting performances of four solid ceramic end milling tools including Si₃N₄, Ti(C,N), SG4 and LT55 in machining hardened AISI H13 steel (HRC 60-62). The results show that the cutting forces of ceramic end milling tools are less than that of the referenced cemented carbide tool, and such ceramic tools of Si₃N₄, Ti(C,N) and LT55 produce better surface qualities and have longer tool lives. With excellent mechanical peoperties including hardness, bending srength and fracture toughness, the ceramic tool of Ti(C,N) presents the best cutting performance taking the cutting force, machined surface quality and tool life in consideration simultaneously. The research has proven the application feasibility of ceramic materials in the manufacture of solid tools. The solid ceramic end milling tools are geometric extensions for traditional ceramic tools and they can be used in machining hardened steels.     

淬火钢的车削加工研究

淬火钢硬度较高,使用常规刀具加工时难以达到理想效果。现根据工件不同的硬度要求,提出了采用不同牌号的刀具材料,选择合理的切削用量,可获得较好的加工质量和经济效益。     

DESIGN AND PREPARATION OF SILICON NITRIDE COMPOSITE WITH HIGH FRACTURE TOUGHNESS AND NACRE STRUCTURE

ＤＥＳＩＧＮＡＮＤＰＲＥＰＡＲＡＴＩＯＮＯＦＳＩＬＩＣＯＮＮＩＴＲＩＤＥＣＯＭＰＯＳＩＴＥＷＩＴＨＨＩＧＨＦＲＡＣＴＵＲＥＴＯＵＧＨＮＥＳＳＡＮＤＮＡＣＲＥＳＴＲＵＣＴＵＲＥＹＨｕａｎｇ；Ｈ．ＮＨａｏ；Ｙ．Ｌ．ＣｈｅｎａｎｄＢ．Ｌ．Ｚｈｏｕ（１）Ｄｅ...     

SiO_2-BN-Si_3N_4系复相陶瓷制备及性能

以Y_2O_3和Al_2O_3陶瓷粉体作为烧结助剂,对不同含量BN原料配比无压烧结制备SiO_2-BN-Si_3N_4系复相陶瓷,生坯采用注凝成型制备,然后在1780 ℃保温2 h烧结,烧结体主要由板条状的Si_2N_2O及长柱状的β-Si_3N_4晶粒构成,BN晶粒弥散在各晶粒之间.Si_2N_2O相通过反应SiO_2+Si_3N_4=2Si_2N_2O原位生成.Si_2N_2O具有优异的抗氧化性,Si_3N_4具有高的强度,而BN的加入大大提高了材料的可加工性能,材料结合了各相的优异性能.实验结果表明:材料热冲击性能优异,热冲击温差在800 ℃时,材料的弯曲强度还略有提高,1200 ℃时,材料的残余弯曲强度保持不变.     

超硬纳微米 PVD 涂层技术在刀具领域的应用及研究进展

介绍了物理气相沉积(PVD)技术的原理、特点和真空蒸镀、溅射镀和离子镀之间的优缺点,从二元涂层、多元涂层、多层涂层和纳米多层复合涂层等4种类别上介绍了PVD涂层技术在切削刀具上的广泛应用。在查阅和整理大量文献资料的基础上,也结合笔者多年从事PVD技术的研究与应用心得,从提高切削刀具的寿命这一重要角度出发,阐述了国内外超硬纳微米PVD涂层技术在切削刀具应用领域的研究进展,并对多元涂层、多层涂层及涂层的纳米化也进行了较为详细地论述。切削刀具表面采用物理气相沉积涂层技术能使刀具获得优异的综合性能,从而显著提高切削刀具的使用寿命,降低生产成本,大幅提高机械加工效率。最后展望了物理气相沉积涂层技术未来将在超硬切削(包括模具钢、淬硬钢等硬度超过HRC55以上的铣削加工)、难加工材料切削(包括高温合金、钛合金、不锈钢等)、石墨和碳纤维等复合材料加工和有色金属的高速切削加工(包括铝合金、铜合金、镍等)的广泛应用。     

纳米Si3N4对ZrO2-Y2O3陶瓷涂层耐磨性及耐腐蚀性能的影响

通过在ZrO2-Y2O3为基的陶瓷粉体中添加不同质量分数的纳米SirN4,采用哑音速氧乙炔火焰喷涂制备陶瓷涂层.探讨纳米Si3N4对涂层耐磨性及耐腐蚀性能的影响.结果表明,纳米Si3N4的加入使涂层的显微组织得到改善,减小涂层中的孔隙率,提高涂层的致密度;随着纳米SiN4加入量的增加,涂层的耐磨性、耐碱腐蚀能力呈先上升后下降的趋势;纳米Si3N4添加量为6%时,涂层中品粒细化效果、耐磨性、耐碱腐蚀性最好.     

Failure mechanisms of TiB2 particle and SiC whisker reinforced Al2O3 ceramic cutting tools when machining nickel-based alloys

In this paper, Al₂O₃/TiB₂/SiC_w ceramic cutting tools with different volume fraction of TiB₂ particles and SiC whiskers were produced by hot pressing. The fundamental properties of these composite tool materials were examined. Machining tests with these ceramic tools were carried out on the Inconel718 nickel-based alloys. The tool wear rates and the cutting temperature were measured. The failure mechanisms of these ceramic tools were investigated and correlated to their mechanical properties. Results showed that the fracture toughness and hardness of the composite tool materials continuously increased with increasing SiC whisker content up to 30 vol.%. The relative density decreased with increasing SiC whisker content, the trend of the flexural strength being the same as that of the relative density. Cutting speeds were found to have a profound effect on the wear behaviors of these ceramic tools. The ceramic tools exhibited relative small flank and crater wear at cutting speed lower than 100 m/min, within further increasing of the cutting speed the flank and crater wear increased greatly. Cutting speeds less than 100 m/min were proved to be the best range for this kind of ceramic tool when machining Inconel718 nickel-based alloys. The composite tool materials with higher SiC whisker content showed more wear resistance. Abrasive wear was found to be the predominant flank wear mechanism. While the mechanisms responsible for the crater wear were determined to be adhesion and diffusion due to the high cutting temperature.     

Active brazed ceramic cemented carbide compound drills for machining lamellar graphite cast iron

The optimum and efficient way of machining is linked to the choice of the most appropriate cutting tool and cutting tool material. High performance cutting ceramics are characterized by excellent hardness properties at elevated temperatures. For this reason, cutting ceramics meet the requirements for machining with high cutting speeds to increase process productivity. Whereas cutting ceramics are widely used in turning and milling operations, their use in drilling processes, using ceramic insert tipped tools, is limited to larger diameter applications due to design restrictions. Beyond small diameters, solid ceramic tools were of negligible interest for industrial applications owing to their excessive tool manufacturing costs. This paper presents a new tool concept which addresses this challenge and permits a more productive machining process for drilling small diameter holes using ceramics as the cutting material. An active brazed compound drill combines the advantageous properties of ceramics and cemented carbide as the cutting tool material and basic holder material, respectively. The investigations presented here describe the manufacturing chain as well as the application of a compound drill, and compares it to a widely used industrial reference tool.     

金属陶瓷刀具切削铸铁的磨损机理研究

利用真空烧结工艺制备了纳米复合Ti(C,N)基金属陶瓷刀片。进行铸铁的单因素切削试验,并利用SEM、EPMA对金属陶瓷刀具的磨损失效机理进行了详细的研究。结果表明:纳米复合Ti(C,N)基金属陶瓷刀片只适宜小切削用量下铸铁的切削加工,切削铸铁时主要以磨损的形式失效,其主要的磨损失效机理是冲击磨损和崩碎切屑的研磨。