电火花加工技术

电火花加工又称为放电JJUF（Electrical Discharge MachiniIN,简称为EDM）,是一种直接利用电能和热能进行加工的新工艺。电火花加工技术作为特种加工领域的一门重要技术,本文从电火花加工的基本原理、特点、加工规律等三方面人手加以论述。     

可切削加工陶瓷材料研究进展

从玻璃陶瓷、氧化物陶瓷和非氧化物陶瓷三个方面比较全面地回顾了可加工陶瓷的研究进展,介绍了其制备工艺、可加工机制及强韧化机制,评述了国内外研究现状．并对可加工陶瓷研究的发展趋势提出了作者的观点．     

电火花加工技术在模具制造的应用

模具是制造业的一种基础工艺装备,模具生产技术水平的高低,己成为衡量一个国家产品制造水平高低的重要标志之一。电火花加工技术是模具成形加工中的重要方法。     

电火花加工机床主轴头振动测试

对国产电火花加工机床主轴头振动进行了测试，并与进口精密电火花加工机床主轴头的振动进行了比较，给出了多种振动波形。     

提高电火花加工效率的方法研究

由于电火花加工有其独特的优点,加上电火花加工工艺技术水平的不断提高,数控电火花机床的普及,其应用领域日益扩大。利用电火花可以加工各种高熔点、高硬度、高强度、高纯度、高韧性的材料,并在生产中显示出很多优越性,在模具制造中被用于凹模型孔和型腔的加工,改进电火花加工工艺,提高电火花加工生产率成为当前一个重要课题。     

三维微细电火花伺服扫描加工工艺

为提高三维微细电火花加工的加工效率,从而达到工业应用目的,采用放电间隙伺服控制实时补偿电极损耗的技术路线,提出了三维微细电火花伺服扫描加工方法．基础实验验证了伺服扫描加工每层加工深度的一致性,研究了横向扫描加工速度对加工深度的影响规律．在小于1mm2加工区域内的三维结构加工实验结果显示,伺服扫描加工可以便捷地实现三维微小结构的加工成型．进一步在工件与电极之间附加激振,可大幅度地提高放电脉冲的有效利用率以及加工效率．采用φ100μm的钨丝电极,在铜试件上加工深度300μm的典型三维形状,加工时间小于50min．     

电火花加工工件表面粗糙度的评定与测试

电火花加工的加工表面与切削加工表面有很大的区别。但是,目前电火花加工工件的表面粗糙度仍然沿用切削加工表面粗糙度的评定方法和测试手段,这样不能准确地反映火花加工后工件表面的真实形貌。本文根据电火花加工的特点,提出电火花加工工件表面粗糙度的评定参数和测试方法。     

粗、精电火花混合加工研究

某型机柱塞为重要件,表面上异形槽尺寸精度高,孔形复杂,一直依靠外委加工,严重影响零件的生产交付以及科研生产能力,成为制约工厂科研生产的瓶颈!现利用我厂新引进的电火花设备,将粗精加工工序混合在一起,实现自主加工。不仅提高我厂的加工能力,而且也提高了加工效率。     

对电火花加工工艺表面耐磨性的实验研究

根据电火花加工和传统加工工艺去除材料的不同机理,利用自行研制的耐磨损实验机具,进行电火花加工和传统加工工艺表面磨损实验研究,获得了零件表面的形貌特征和变质层金相组织.分析实验结果后认为,实验研究对改善电火花加工的零件表面质量和机械物理性能具有意义.     

提高电火花成型及小孔加工质量的措施

本文简述电火花加工的特点及加工中提高加工质量的方法、措施,并针对这些方法、措施作了具体的阐述。     

纳米SiO2多孔陶瓷的绝热性能

本文制备了纳米SiO2多孔陶瓷材料,并引入红外遮光剂提高其在高温下的绝热性能。利用场发射扫描电镜、比表面积及孔隙度分析仪、傅里叶红外分析仪和背温试验等方法对该材料的微观结构及绝热性能进行分析,并重点研究了红外遮光剂的作用机理。当添加质量分数为20%、平均粒径为1.07μm的六钛酸钾(K2Ti6O13)作为遮光剂时,试样的最大有效消光系数从19.5m2/Kg提高到60.6m2/Kg,热面温度为600℃的试样的背面温度从252℃降低到148.9℃。红外遮光剂的加入能有效散射和反射红外辐射,显著提高试样的有效消光系数,改善该材料的高温绝热性能。     

基于凝胶注模技术制备TiN-Cu电火花电极可行性研究

本文主要探索凝胶注模技术制备TiN-Cu电火花加工用 (EDM) 电极的可行性。本文以TiN粉末和Cu粉末作为原料、海藻酸钠作为分散剂、明胶作为粘结剂, 经过浆料制备、干燥、烧结成EDM电极。研究了pH值、分散剂、粘结剂对浆料流动性的影响和TiN-Cu EDM电极电加工性能。试验结果表明:当pH值为7、海藻酸钠质量分数为1%、明胶质量分数为1%时, 30%TiN-Cu EDM电极相对损耗率为11.625%, 比商用紫铜电极相对损耗率低, 从而得出凝胶注模技术制备TiN-Cu EDM电极是可行的。     

Experimental Investigations of Hot Forging Die Surface Layer of Skd61 Steel in Die Sinking Electrical Discharge Machining

Electrical discharge machining is an important manufacturing process for tool mould and die industries. The results of the research about EDM show that the performance of die sink reduced due to a change in the material quality of the surface layer than the base material. The article presents the result of the study on the hot forging die surface layer of the SKD61 hot die steel （surface roughness, surface microscopic hardness, microscopic structure of the surface layer, EDS analysis of the surface layer） after die sinking electrical discharge machining using a tool of titanium and copper in oil dielectric.     

基于真空冷冻干燥和高真空微波烧结方法制备TiN-Cu电火花电极

探索真空冷冻干燥和高真空微波烧结方法对TiN-Cu电火花加工用 (EDM) 电极性能的影响。经过高能球磨混合TiN粉末和Cu粉末、浆料制备、干燥、烧结等工艺制备出电火花加工用电极。对比了真空干燥与真空冷冻干燥、真空管式烧结与高真空微波烧结等工艺性能, 采用正交实验方法探索高真空微波烧结最佳工艺参数组合, 并且通过电子扫描电镜观察EDM电极形貌。试验表明:真空冷冻干燥制备坯体收缩率较小;在微波烧结在烧结温度1200℃、保温时间20 min、升温速率15℃/min工艺参数下, 制备出TiN-Cu EDM电极相对损耗率为3.55%, 比商业上应用的紫铜EDM电极相对损耗率低。     

Study of Electrical Discharge Machining Performance in Water-Based Working Fluid

In this study, the role of working fluid in electrical discharge machining (EDM) was investigated based on its electrical conductivity. The function of gas bubble in material removal process was studied by comparing the crater that formed in water discharge with that formed in air discharge. The mechanism of material removal for EDM in water-based working fluid was proposed by analyzing the discharge voltage. Experiments were conducted to learn the influence of discharge parameters and working fluid conductivity on the crater forming process. The detected discharge waveform demonstrated that the effect of electrolytic reaction in the discharge process could be controlled by changing the conductivity of the working fluid. This study shows that water-based working fluid has good application prospects in EDM machining.     

空气介质微细电火花沉积加工微结构机理

对微细电火花沉积加工中沉积所得不同微细结构的成形机理进行了研究．在电火花成形机床上，通过合理选择工艺参数，用黄铜电极在高速钢工件表面稳定沉积出外径约0．20mm、线径约0．09mm的微螺旋结构和直径约0．20mm微圆柱体．通过有限元法对工具电极放电点的瞬态温度场进行了模拟，分析结果表明，不同的放电能量密度影响材料的蚀除形式，继而影响蚀除电极材料在放电通道中的运动，最终影响微细结构的成形过程．对沉积材料微观组织结构分析表明，沉积材料与基体结合层为冶金结合方式，结合紧密，并由于凝固过程极大的冷却速率，使沉积材料在凝固过程中发生了晶粒细化现象．     

Electrical Discharge Machining of MMCs Reinforced with Very Small Particles

This paper investigates material removal rate (MRR), kerf width, surface finish, and electrode wire wear for different pule-on-times as well as wire tensions during EDM of 6061 aluminum alloy reinforced with 10 vol % 700 nm SiCp MMC. Effects of pulse-on-time on output variables at lower and higher wire tensions were investigated. Similarly, effects of the wire tensions on output variables at shorter and longer pulse-on-times were also investigated. Longer pule-on-time increases the MRR though the higher wire tension reduces the MMR. The effect of wire tension on MRR is much more significant at longer pule-on-time compare to that at shorter pule-on-time. There is an optimum pule-on-time for which best surface finish is achieved. The surface finish deteriorates when the pulse-on-time is higher or lower than the optimum pule-on-time. With the rise of tension in wire, the surface roughness increases and decreases at shorter and longer pule-on-times, respectively. The machined surface contains solidified molten material, splash of materials, and blisters. Generation of the tapered slot with higher kerf width at the top indicates the wear of wire electrode. Significant variation of the electrode wire diameter was due to coating of the matrix, wear, and clogging of small reinforced particles in the electrode gap.     

Electrical Discharge Machining (EDM) Characteristics Associated with Electrical Discharge Energy on Machining of Cemented Tungsten Carbide

In this investigation, cemented tungsten carbides graded K10 and P10 were machined by electrical discharge machining (EDM) using an electrolytic copper electrode. The machining parameters of EDM were varied to explore the effects of electrical discharge energy on the machining characteristics, such as material removal rate (MRR), electrode wear rate (EWR), and surface roughness. Moreover, the effects of the electrical discharge energy on heat-affected layers, surface cracks and machining debris were also determined. The experimental results show that the MRR increased with the density of the electrical discharge energy; the EWR and diameter of the machining debris were also related to the density of the electrical discharge energy. When the amount of electrical discharge energy was set to a high level, serious surface cracks on the machined surface of the cemented tungsten carbides caused by EDM were evident.     

多孔陶瓷的直写成型工艺研究进展

多孔陶瓷内部含有大量三维孔隙,具有轻质、高强、高比表面积、低导热系数等特性,但是多孔陶瓷的传统制备工艺对结构和性能的可控性较低,很难满足先进能源、航空航天、电子信息等领域的发展对多功能高性能材料的需求。直写成型工艺是一种制造成本低、材料使用性广、技术可拓展性高的3D打印工艺,不仅可以直接制备具有轻量化特点的多孔陶瓷,而且结合其他工艺可以实现多孔陶瓷的层级结构和多功能化,有望实现设计与制造、材料与器件、结构与功能的一体化。介绍了直写成型法3D打印多孔陶瓷的工艺原理,综述了直写成型法直接制备多孔陶瓷、直写成型结合乳液/泡沫法和冷冻干燥法制备层级多孔陶瓷的研究进展。由于工艺柔性高,直写成型法能够与其他方法良好融合,以制备具有特殊结构和性能的多孔材料,尤其是兼顾高强度、高孔隙率和形状可控性的层级多孔陶瓷。最后,总结了目前直写成型工艺制备多孔陶瓷的优势和不足,并对打印材料性能、打印设备和主要应用领域的发展进行了展望。