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。

Influences of Powder on the Surface of Workpiece in Powder-Mixed EDM

Comparative measurements of percentage of silicon on the surface of workpiece by powder-mixed electrical discharge machining (EDM) were carried out. The experimental results indicate that: with small peak current less than 4A, the percentage of silicon decreases sharply while peak current increases by powder-mixed EDM. However, with greater peak current higher than 4A, it increases gently. It also increases with the increase of pulse duration by powder-mixed EDM. Under the same other experimental conditions, the content curve of silicon can be achieved near to conic by powder-mixed EDM with the same single discharge energy under conditions of different peak current. The entropy is introduced to explain the reasons for aforementioned conclusions. And the mechanism that surface quality of workpiece is improved by powder-mixed EDM is analyzed.