Three-dimensional Shaping by Dot-matrix Electrical Discharge Machining with Miniaturized Electrode Feeding Devices

提出了一种新的基于扫描运动的点阵电火花加工（EDM）方法，并利用该方法开发了一个加工单元的原型。点阵法的加工过程类似于点阵式打印机的打印运动。该方法不仅适用于电火花加工，而且适用于电化学加工和成形。加工单元的原型有六个用于细线电极的进给装置。直径为300 μ m的电极以760 μ m的节距布置。尺寸为55*55* 80mm。为了获得光滑的表面，在加工单元的z向进给中加入在xy平面上的行星运动，重复加工同一区域或加工单元以精细进给移动。通过补偿电极在扫描电火花加工过程中的磨损，可以在不成形工具电极的情况下获得精度为微米级的各种形状。放电浓度高导致加工表面出现裂纹。放电电流单独供给各丝电极，实现放电完全分散，从而获得无裂纹表面。在点阵电火花加工中，放电分散不依赖于工件的电阻率。研究了细线电极电火花加工的表面改性。

A new prototyping method called a dot-matrix electrical discharge machining (EDM) with scanning motion is proposed, and a prototype of a machining unit by the dot-matrix method is developed. The machining process by the dot-matrix method is similar to printing motion with a dot impact printer. This method can be applied to not only EDM but also electrochemical machining and forming. A prototype of the machining unit has six feeding devices for thin wire electrodes. The electrodes of 300 mum in diameter are arranged with the pitches of 760 mum. It measures 55*55*80 mm. To obtain a smooth surface, a planetary motion in the xy plane is added to the feeding of the machining unit in the zdirection, the same area is machined repeatedly or the machining unit is moved with fine feed. By compensating the wear of the electrode during the scanning EDM,various shapes with the accuracy of micrometers order can be obtained without a formed tool electrode.Discharge concentration causes cracks on the machined surface. Discharge current is supplied to each wire electrode independently to realize complete discharge dispersion so that a crack-less surface can be obtained. The discharge dispersion does not depend on the resisitivity of a workpiece by divided supplying in the dot-matrix EDM.The surface modification by EDM with thin wire electrodes is also investigated.