Micro-hole Maching of Copper Using the Electro-discharge Machining Process with a Tungsten Carbide Electrode Compared with a Copper Electrode

This paper describes micro-hole machining of a copper plate using the electro-discharge machining (EDM) process. Tungsten carbide was selected as the material for the electrode and compared with a copper-electrode. A precision centreless grinding process was employed to grind the electrode down to the desired diameter. A series of experiments were performed on a traditional EDM machine to investigate the effects of electrode material polarity setting and of a rotating electrode. Results have shown that electrode wear and hole enlargement are both smaller when positive polarity machining is selected; whereas electrode wear is larger and machining speed is higher when negative polarity machining is selected. High-quality micro-hole machining in copper can be achieved by the proposed method.     

微细电火花加工设备技术研究

微细电火花加工的关键设备技术涉及电极的微进给伺服机构、电极和工件的附加树对运动机构、微小能量放电电源以及加工状态检测与控制系统等。文章围绕微细电火花加工系统的设计系统，介绍基于压电致动原理以及摩擦传动的微进给机构、工具电极的线放电磨削机构和旋转主轴、以及微小能量放电电源的设计等，并指出需要进一步研究的课题。     

An investigation of tube and rod electrode wear in micro EDM drilling

This paper studies the influence of various factors contributing to micro electrode wear during electrical discharge machining (EDM) drilling with micro rod and micro tube electrodes. In this paper, a simple method for calculating volumetric wear ratios is proposed based only on geometrical information obtained from the process. The objective of the research is to investigate the wear behaviour of electrodes and the suitability of electrode wear compensation methods. Electrode shape deformation and random variation of the volumetric wear are studied as the main factors affecting the applicability of wear compensation methods and as an indicator of the accuracy achievable with the micro EDM process.     

两种超声加工与放电加工的复合加工方法研究

以比较两种复合加工方法为主要目的,在实验的基础上对两种超声加工和放电加工的复合加工方法进行了研究。     

扭杆弧形槽精密微细电火花加工工艺研究

针对扭杆弧形槽的加工要求,分析了机械误差对加工精度的影响,设计了合理的装夹方案,降低了机械误差对制造精度的影响;通过正交试验法分析了电加工参数对弧形槽表面粗糙度的影响,采用最优加工参数,可得到Ra=0.1μm的弧形槽表面;研制了扭杆电火花加工刚度在位测量装置,该装置能解决扭杆加工中既要满足面形精度又要满足加工刚度的要求。     

微细电火花加工中微细电极的制作与检测技术研究

分析了微细电火花加工技术中各种微细电极制作方法的特点,提出了一种加工效率与尺寸精度相兼顾的微细电极在线制作方法.充分利用微细电火花加工机床的数控和接触感知功能,探索并提出了一种微细电极的在线检测方法,并对检测误差进行了分析.实验表明,该方法具有广泛的实用性.     

混粉电火花镜面加工技术的研究及进展

混粉电火花镜面加工技术能够显著改善加工表面粗糙度,提高表面质量,使电火花加工作为精密模具制造的最终工序成为可能。从混粉电火花镜面加工技术的机理性研究和工艺性研究两方面,详细论述了有关研究内容和研究进展,可为今后的深入研究提供参考。     

新型蠕动式微细电火花加工装置的设计开发

首先概括阐述了小型化微细电火花加工机构的研究现状。在此基础上,针对现在遇到的主要问题,设计开发了一种新型的管状结构蠕动式微细电火花加工机构,能够对微细电极进行较为有效精确的夹持和定位,响应速度较高。介绍了该新型机构的原理和实现方式,并对其主要部件进行了理论建模和有限元分析。该机构可以实现从任意方位任意角度进行加工,结构对称,紧凑可靠,有较高的实用价值。     

喷油嘴微孔电火花加工机床机电控制系统设计

喷油嘴喷孔加工质量直接影响发动机的燃料喷射和燃烧性能。喷油嘴喷孔机械钻削加工已难以适应高压力、微细喷孔喷油嘴发展的需要。微细电火花加工喷油嘴喷孔具有无宏观加工力、无毛刺、可加工微细喷孔以及可在热处理后加工等优点。文章结合自主设计研发的喷油嘴微细孔电火花加工机床,设计了机床的机电伺服控制系统,并进行了控制系统性能优化,进行了喷油嘴微细喷孔的电火花加工实验和工业应用,较好地满足了喷油嘴微细喷孔加工的工业需求。     

混粉电火花加工中极性效应的研究

为研究极性效应对混粉电火花加工的影响规律．采用钢对钢加工、铜对钢加工两种电极组合在添加硅粉的煤油工作液及普通煤油工作液中进行实验，并更换不同的极性，考察了两极材料的去除率和表面粗糙度，结果表明负极总能得到更高的材料去除率，而正极总能得到更低的表面粗糙度值。此现象可从两极表面能量密度差异的角度予以解释。     

整体叶环成组电极电火花高效加工技术研究

为提高整体叶环电火花加工总体效率,针对整体叶环结构特点,提出了一种成组电极多流道同时加工方案。以典型整体叶环为例,详细论述了该方案中的关键技术,包括成组电极型面、进给轨迹及展成运动轨迹设计等。基于关键技术的解决,通过工艺试验对方案进行验证,并试制加工出合格的试验件。研究表明,采用成组电极对整体叶环进行电火花加工,能够提高脉冲利用率,有效缩短带冠叶环制造周期。     

高精度微型零件批量加工工艺创新

针对小型特殊棱镜,长度和理高比在30：1以上的细、长型棱镜的加工提出了工艺创新方案：通过改变黏结方式,有效保证了产品的高精度要求,实现了特殊棱镜的高效抛光;通过改变清洗工艺,实现了产品的节能和环保,并使该类产品得以量产。     

Multi-discharge EDM coring of single crystal SiC ingot by electrostatic induction feeding method

A new technique of EDM coring of single crystal silicon carbide (SiC) ingot was proposed in this paper. Currently single crystal SiC devices are still of high cost due to the high cost of bulk crystal SiC material and the difficulty in the fabrication process of SiC. In the manufacturing process of SiC ingot/wafer, localized cracks or defects occasionally occur due to thermal or mechanical causes resulted from fabrication processes which may waste the whole piece of material. To save the part of ingot without defects and maximize the material utilization, the authors proposed EDM coring method to cut out a no defect ingot from a larger diameter ingot which has localized defects. A special experimental setup was developed for EDM coring of SiC ingot in this study and its feasibility and machining performance were investigated. Meanwhile, in order to improve the machining rate, a novel multi-discharge EDM coring method by electrostatic induction feeding was established, which can realize multiple discharges in single pulse duration. Experimental results make it clear that EDM coring of SiC ingot can be carried out stably using the developed experimental setup. Taking advantage of the newly developed multi-discharge EDM method, both the machining speed and surface integrity can be improved.     

Development of an unconventional electro-hydraulic proportional valve with fuzzy-logic controller for hydraulic presses

A micro slit die easily manufactured using a micro electrical discharge machining (MEDM) is proposed for micro heat sink fabrication. In the investigations described in this paper, processed concave and rectangular shaped copper foils were combined piece by piece to form an assembled electrode. This electrode was used to fabricate a micro slit die. This die included 15 micro fins in a small tungsten carbide plate. The micro heat sink was made by applying a pressing or scraping method when the micro slit die was used. The experiments showed that debris, produced by the MEDM, might cause a discharge concentration effect because of the narrow gaps between the workpiece and electrode. Parts of the micro fin were seriously melted during this process. Flushing dielectric could effectively remove the debris from the narrow gap, generating an appropriate discharge dispersing effect. However, the discharge effect was unstable when large flushing pressure was applied, thus reducing the machining precision. The micro fins were formed into a rectangular shape using kerosene as the MEDM dielectric. Using distilled water as the MEDM dielectric produced a higher material removal rate and serious assembled electrode wear. Therefore, the micro fins formed as triangle profiles. The micro heat sink was higher even when the pressing method was used. The heat sink deviated and was full of burrs on the fin edge when the scraping method was used.     

螺旋电极电解扩孔工艺研究

介绍了螺旋电极电解扩孔，该方法兼有小间隙电解加工和脉冲电流电解加工的优点，用于硬质金属材料导孔的加工是一种行之有效的新的工艺方法，文对其中原理。加工实验研究和基本工艺规律作了综述。     

提高电火花加工效率和表面质量的研究

针对电火花加工中存在的不足,基于多年加工实践经验,给出了提高电火花成形机加工效率和表面质量的措施。研究了电火花成形机加工参数与加工效率和表面质量之间的关系,最后对几种优化组合电加工参数下的加工情况进行了分析研究,所得结论为提高电火花加工质量提供指导。     

小孔加工电火花脉冲电源实验研究

针对传统脉冲电源普遍存在的电能利用率低、电阻发热严重、散热设备庞大等问题,提出了一种取消限流电阻的电火花脉冲电源结构。电源由PWM控制器、DC/DC变换器、加工脉冲时序发生器等组成。电源本身具有自动调节输出电压的功能,可实现空载击穿电压、脉冲宽度、脉冲间隔独立可调,取消了体积庞大的工频变压器。通过多次小孔加工实验获得了脉冲电源加工过程中电极损耗率、小孔椭圆度以及单边放电间隙等和电源稳定性相关参数的数据曲线,所得数据表明电源具有较好的加工稳定性和可靠性。     

提高电火花加工效率和表面质量的研究

针对电火花加工中存在的不足,基于多年加工实践经验,给出了提高电火花成形机加工效率和表面质量的措施。研究了电火花成形机加工参数与加工效率和表面质量之间的关系,最后对几种优化组合电加工参数下的加工情况进行了分析研究,所得结论为提高电火花加工质量提供指导。     

A Feasibility Study on the Micro Eletro-Discharge Machining Process for Photomask Fabrication

A feasibility study of micro electro-discharge machining (micro-EDM) technology has been conducted for its possible contri-bution in the photomask industry. A series of experimental runs was performed on three specimens using a micro-EDM system with built-in wire electro-discharge grinding. Different thicknesses of chromium films were coated on borosilicate glass substrates. Unwanted chromium metal was machined through to the transparent glass substrate, leaving behind the desired pattern. In this study, lines were machined at different voltages, using electrodes of 20 _m in diameter, and no significant wear of electrodes was observed. The machined regions on the specimens were quantified in terms of linewidth deviation and light transmission. The experimental results showed that the linewidth deviations for all three specimens are below the 10% cut-off threshold. The best average light transmission obtained from this experiment was 75.8% at 90 V. The results gathered so far, suggests that the application of micro-EDM to produce a photomask is an acceptable process.     

混粉电火花加工中粉末对工件表面的影响

对不同加工条件下混粉电火花加工后工件表面的硅含量进行了对比测量。实验结果表明：当峰值电流小于4A时，混粉电火花加工后的工件表面硅含量随峰值电流的增大而急剧减小，而当峰值电流大于4A时，工件表面硅含量随峰值电流的增大而缓慢增加；混粉电火花加工后的工件表面硅含量随脉宽的增大而增加；在其他加工条件相同的情况下，对于相同的单次放电脉冲能量，混粉电火花加工获得的工件表面硅含量随峰值电流变化的关系呈近似二次曲线。引入熵的概念，对产生上述结论的原因进行了分析，并解释了混粉电火花加工可以改善工件表面质量的机理。