电化学放电加工中气膜厚度及其影响研究

玻璃作为一种非导电硬脆材料，在光学、生物医学、微机电系统等领域应用广泛。电化学放电加工作为针对绝缘硬脆材料的有效微细加工技术，可以在玻璃上进行有效的微结构加工。在电化学放电加工中，放电现象通过击穿气膜产生，气膜作为加工过程中最重要的介质，其质量是形成良好的表面微结构的重要因素。文章研究的重点是气膜特性及其对放电能量分布的影响。研究采用三因子三水平的全因子试验方法，以电源、占空比、频率三种电源参数为影响因子，气膜厚度为响应进行试验研究，获得最佳气膜质量的工艺参数组合。此外，在石英玻璃和K9光学玻璃两种玻璃上进行了微小孔加工的实验。结果表明，最佳工艺参数组合下能获得更薄气膜，同时也是获得更小径向过切、大的深径比、圆度误差较小的微小孔的最佳条件。     

超微孔加工技术的工艺研究

主要介绍了超微孔加工工艺的技术特点，尤其是在对非导电超硬材料利用超声加工和研磨超微细孔的工艺研究上所取得的一些进展，作了分析归纳，以便超微孔的加工技术在该相关领域的推广和应用。     

微孔超精密加工研究进展

近年来,电子、医药、航空航天等行业对高质量微孔结构的需求量日益增加,但加工精度低、加工半径尺寸受限、在复杂零件上加工困难等问题限制了其应用.传统微孔加工方法已无法满足高加工质量要求,超精密微孔加工方式仍有许多问题亟待解决.因此,本文对电化学、微细电火花、超声波、飞秒激光、复合加工等超精密加工方式在微孔加工中存在的问题进行了总结,并对不同的超精密加工方法的特点和相应问题的研究进展进行了综述,最后对微孔加工方式未来的发展趋势进行了展望.     

脉冲激光电化学复合加工的试验研究

在所构建的激光电化学复合加工系统中,加入透光导电的氧化铟锡(indium tin oxide,ITO)导电玻璃作为工具阴极,使电场分布更加均匀,有利于工件表面形成均匀的钝化膜,保证了激光电化学的高效复合。采用该复合方法在浓度为0.5 mol/L的Na NO3溶液中对铝合金进行了加工试验,研究了不同的工艺参数对激光电化学定域性的影响。应用扫描电子显微镜、光学显微镜对工件的加工形貌进行检测。结果表明:随着激光的能量、频率、加工电流的增大,槽的宽度变大;随着进给速度的增大,槽的宽度变小。     

导电性工程陶瓷材料的放电加工研究

通过专用脉冲电源脉冲放电能量的控制,进行了导电性工程陶瓷材料的电火花放电加工试验研究,提供了一种稳定加工导电笥工程陶材料且能控制加工质量的电火花放电加工方法。     

超声频间隙脉冲放电加工研究

作者提出了超声频间隙脉冲放电加工新技术，并对该技术进行了理论分析和加工实验。本刊将从本期起分四次刊出超声频间隙脉冲放电加工的基本原理、工作液选择、理论分析和实验研究。     

印刷电路板微孔加工的问题及发展

随着电器产品小型、轻量、高密度和高可靠性的要求,印刷电路极微孔加工的难度越来越大。本文对其冲孔和钻孔中孔径超差、毛刺和污斑的产生、钻孔位置偏离等现象及原因进行了分析,介绍了目前印刷电路板微孔加工的发展概况,比较了不同加工方法的优缺点,并介绍了专用微孔加工机床的性能、空气轴承主轴部件的应用、专用钻头的结构形状、材料和适用范围等问题。     

气体放电加工基础工艺试验研究

采用单因素法进行了基本的工艺参数(电参数、伺服参考电压等)对气体介质放电加工性能影响的试验研究。试验结果表明:气体介质的放电加工适于采用正极性加工。在试验加工的范围内,工件的蚀除速度和表面粗糙度值随脉冲宽度和峰值电流的增加而增加,随脉冲间隔的增加而减小。极间并联合适的电容能够使加工速度和加工表面粗糙度有所改善,并对此现象进行了分析。对于某一确定的加工参数,存在一个较佳的伺服参考电压值,使加工性能较为稳定。工具电极具有较高的旋转速度能够使气体放电加工性能得到提高。使用氧气介质能够实现快速电火花加工,并根据不同气体的物理性能对不同气体介质的加工性能进行了分析。工件表面显微硬度测试结果表明:空气中放电加工的工件的表面硬度比基体硬度高,比煤油中加工的工件表面硬度低。     

电源类型对短电弧-电化学复合加工放电凹坑影响研究

放电凹坑大小影响着加工表面形貌的一致性,放电凹坑的凸起高度及凹坑表面的重铸层对加工表面质量有重要影响。文章基于短电弧-电化学复合加工方法,在直流与脉冲两种常用电源类型下对钛合金TC4进行单次放电实验,分析两种电源类型下的短电弧-电化学复合加工单次放电凹坑尺寸及影响规律;结合单次放电凹坑实验所采集到的波形与电弧放电过程仿真模型对电弧放电过程的等离子体放电通道变化进行研究。研究结果发现,直流与脉冲放电凹坑的尺寸与影响规律差异与电弧的断弧方式有关,不同的断弧方式对等离子体放电通道产生影响,直流电弧倾向于通过流体介质运动和极间距离改变进行断弧,而脉冲电弧通过脉冲后沿电压变化和极间距离改变进行熄弧。这两种断弧方式不仅影响了凹坑的尺寸形貌,也影响了断弧后的电化学腐蚀效果。     

模糊控制系统在电化学放电线切割加工的 应用研究

针对电化学放电线切割加工方法,基于润湿的供液方式,搭建了基于力信号反馈控制进给的加工实验平台,设计了基于力信号反馈控制进给速度的模糊控制系统,并将模糊控制系统应用到力信号反馈控制进给的加工实验平台上,进行了微槽加工实验,发现与PID控制算法相比较,模糊控制系统有效改善了微槽两侧的过切现象,显著提高了加工效率,验证了模糊控制系统在电化学放电线切割加工过程中的实用性。     

旋转电极电解电火花切割玻璃微结构试验研究

针对高深宽比非导电硬脆材料(如石英玻璃和陶瓷)微结构的加工需求,对微细电解电火花切割加工方法进行了深入研究。首先,提出了使用旋转螺旋微工具电极的电化学放电切割方法,并对切割缝宽模型进行了讨论;其次,对旋转螺旋电极电解电火花切割加工工艺进行了深入的试验研究,试验研究了加工电压、脉冲频率、占空比和主轴转速这些关键工艺参数对切割加工精度的影响。实验结果表明,缝宽随着施加电压和占空比的增加而增加,随着频率、主轴转速和进给速率的增加而减小。最后,通过优化后的参数成功加工出缝宽为135μm的微缝阵列、复杂的封闭微结构以及深宽比达6∶1的微图形结构。由此表明该方法是一种可有效加工高深宽比绝缘硬脆材料微结构的新工艺。     

机械加工和电火花加工的组合技术在叶轮制造中的应用

介绍了机械加工和电火花加工的组合技术在窄流道闭式叶轮制造中的应用，通过对比试验可以充分征明，这种组合加工技术是电火花加工效率低、机械加工有干涉等问题的有效解决方法。     

影响电火花加工进程的因素分析

通过分析电火花加工机理,论述了电火花成型加工中电参数、工业速度、工作液、电极材料等主要过程影响因素,并探讨了EDM加工对工具钢的影响以及改善措施。     

电火花加工微缝筛管

阐述目前加工微缝筛管方法的缺陷,提出电火花加工微缝筛管的方法,研究该方法的设备组成、工具电极等,分析影响加工微缝筛管的因素。     

Experimental investigations into electrical discharge machining with a rotating disk electrode

In electrical discharge machining, when the provision of holes in the electrode is impracticable, flushing of the working gap poses a major problem. Use of a rotating disk electrode is proposed as a more productive and accurate technique than use of a conventional electrode. Material removal rate, tool wear rate, relative electrode wear, corner reproduction accuracy, and surface finish aspects of a rotary electrode are compared with those of a stationary one. The effective flushing of the working gap brought about by the rotation of the electrode remarkably improves material removal rate and machines surfaces with a better finish. Despite the prevalent high tool wear rate, the reproduction accuracy is least affected as the wear gets uniformly distributed over the entire circumference of the disk. Machining of a sharp corner is possible even with an aluminum electrode, whose relative electrode wear is greater than unity.     

Experimental and numerical investigations of material removal process in electrochemical discharge machining of glass in discharge regime

Electrochemical discharge machining (ECDM) can be applied as a non-traditional processing technology for machining non-conductive materials such as glass and ceramics, based on the phenomena of evoked electrochemical discharges around the tool electrode. The material removal mechanism of ECDM is noticeably complex and difficult to experimentally characterize. In this paper, finite element models were proposed to predict the material removal in the ECDM discharge regime. First, the single-pulse discharge on a tapered electrode was modeled. It was found that about 30.5% of the discharge energy is transferred to the workpiece. The continuous discharge on a cylindrical electrode was thereafter modeled according to this phenomenon, in which the removal of a layer of the workpiece material starts from the projected contour of the edge of the electrode end and extends inward during the ECDM processing. The effective discharge ratio for material removal was calculated to be 10.1%. The drilling depths of holes at different applied voltages were predicted by the proposed finite element method. It was found that the predicted values were consistent with the experimental results.     

Electrical discharge machining with ultralow discharge energy

The possibility of electrical discharge machining (EDM) with ultralow discharge energy has been investigated. EDM using an RC discharge circuit was performed at low open-circuit voltages and a capacitance of approximately 30 pF. Workpieces were ultrasonically vibrated to remove debris and bubbles from the discharge gap, thus preventing short-circuiting. The machining proceeded at voltages lower than 15 V at a vibration amplitude of 0.4 μm. The maximum discharge energy per pulse is as small as approximately 3 nJ under these conditions. The volumetric electrode wear ratio can be 0.2% at voltages lower than 40 V, while it is normally more than 1% for EDM using an RC discharge circuit. Workpiece surfaces processed at voltages of 20 V or lower are smooth and free of observable discharge craters, and show no typical features of surfaces machined by EDM.     

Monitoring of the electrical discharge machining process by abductive networks

The paper describes the use of abductive networks to monitor the electrical discharge machining (EDM) process. The voltage and current across the gap between the tool and workpiece are fed into the developed networks for the recognition of various pulse types in EDM in a winner-take-all fashion. Experimental results have shown that EDM pulses can be clearly classified even with different machining conditions. Hence, a reliable technique has been developed to monitor the EDM process.     

基于多工位的微细长槽电解加工的试验研究

针对如何提高微细长槽批量加工的成型精度和效率问题,将电解加工的技术应用到微细长槽的批量加工中.依据电解加工原理,以微细长槽加工的复制精度为评价指标,建立了微细长槽成型精度的模型分析,得出了影响成型精度的主要因素有：底面间隙、侧面间隙和间隙内流场均匀性,并以此为基础,分别进行了不同加工方式和阴极刀具进给速度的试验.研究结果表明,采用群电极倾斜并沿槽纵向移动的加工方式,以及在保证加工稳定的前提下通过提高阴极刀具的移动速度,可以提高微细长槽的成型精度和加工效率;该方法对于微细长槽的批量加工具有一定的指导意义.     

Electrochemical machining analysis on grid cathode composed of square cells

During the electrochemical machining (ECM), the cathodes designed by the existing methods are mainly unitary cathodes, which can be only used to produce the workpieces with the same shapes. However, there are few researches on designing cathodes for machining the different workpieces with the different surfaces. This paper presents the grid cathode composed of the square cells to produce the workpieces with different shapes. Three types of the square cells, 2.5 mm′2.5 mm, 3 mm′3 mm, and 4 mm′4 mm, are utilized to construct the plane, the slant, and the blade cathode. The material of the cathode and the anode is CrNi 18 Ti 9 , and the ingredient of electrolyte is 15% NaCl and 15% NaNO 3 . The machining equilibrium machining current and time are acquired and analyzed, the machining process and the workpiece quality are compared between using the grid cathode and the unitary cathode. Moreover, the machining errors on the workpiece surface are measured and analyzed, and the error reasons are traced and discussed to obtain the better surface quality of the workpiece. The experiment and analysis results show that the grid cathode can be used to manufacture the workpieces with complex shapes in certain range of the error. The workpiece quality improves with the size of the square cell being reduced, and if the square element is small enough, the workpiece quality is almost equal to the one machined by the unitary cathode. The proposed research realizes a single cathode machining the different workpieces with the different surfaces.