A novel method to switch machining mode between Micro-ECM and Micro-EDM using oxide film on surface of tungsten electrode
A novel method to switch machining mode between Micro-ECM and Micro-EDM using oxide film on surface of tungsten electrode
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DOI：
10.1016/j.precisioneng.2019.02.002
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发表时间：
2019-03
期刊：
影响因子：
--
通讯作者：
W. Han;M. Kunieda
中科院分区：
文献类型：
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作者：
W. Han;M. Kunieda
提出了一种利用同一工具电极和脉冲发生电路在同一电解液中实现微细电火花加工和微细电解加工模式切换的新方法。该方法使用静电感应馈电方法，其中脉冲电压通过电容耦合到工作间隙。利用钨电极表面形成的氧化膜实现了电火花加工和电解加工模式的切换。为了将ECM模式切换到EDM模式，改变与工作间隙并联连接的二极管的极性以控制氧化膜的产生。在ECM模式中，连接二极管，使得当工具电极的极性为正时，二极管被正向偏置，从而在钨电极上不形成氧化膜。在EDM模式中，由于二极管的极性被反转，形成氧化膜，从而可以点燃放电。从间隙电流和电压的波形中验证了开关能力，这表明在EDM模式中发生放电，而在ECM模式中没有观察到放电波形。在电解加工模式下，研究了脉冲电压的总幅值和上升/下降时间对电解加工的影响。在电火花加工模式下，首先研究了不同电解液浓度下的放电概率。研究了进给电容C1对电火花加工模式的影响。最后，通孔加工进行电火花和电解加工模式，以获得较高的材料去除率在粗加工和良好的表面粗糙度没有残余应力在精加工。
A novel method to switch the machining mode between micro-EDM and micro-ECM in the same electrolyte using the same tool electrode and pulse generator circuit was proposed in this research. This method uses the electrostatic induction feeding method where a pulse voltage is coupled to the working gap through a capacitance. The switch between the EDM and ECM modes was realized by utilizing the oxide film formed on the surface of the tungsten electrode. To switch the ECM mode to the EDM mode, the polarity of the diode attached in parallel to the working gap was changed to control the generation of the oxide film. In the ECM mode, the diode was connected so that it is forwardly biased when the polarity of the tool electrode is positive, thereby the oxide film was not formed on the tungsten electrode. In the EDM mode, since the polarity of the diode was reversed, the oxide film was formed, thereby discharge could be ignited. The switching ability was verified from the waveforms of gap current and voltage which showed that discharge occurred in the EDM mode, whereas there was no discharge waveform observed in the ECM mode. In the ECM mode, the influences of total amplitude and rise/fall time of pulse voltage were investigated. In the EDM mode, the discharge probability with different concentrations of electrolyte was researched first. Then, the influence of the feeding capacitanceC1on the EDM mode was investigated. Finally, through-holes were machined by conducting the EDM and ECM modes in this order to obtain higher material removal rate in rough machining and better surface roughness without residual stress in finish machining.