微粒对放电通道生长的影响机理研究

Study on Mechanism of Discharge Channels’ Growth Effected by Particles

混粉电火花加工相对于普通电火花加工能够在小脉冲能量下稳定地进行加工并实现较好的加工质量,是因为悬浮在工作液中的微粒改变了放电通道形成的机制。分析了粉末颗粒对放电间隙电场、放电通道轨迹形成的影响,得出了混粉电火花加工放电过程稳定性提高的重要原因,即悬浮的微粒以及微粒之间的作用增大局部电场强度、改变放电通道的生长模式,从而减少击穿时间和能量消耗,因此在加工稳定性和加工质量上有明显提高。

Powder mixed electrical discharge machining （PMEDM）, using kerosene with suspended powder as the dielectric fluid, can work steadily at very low pulse energy with satisfying results and the powder particles is believed to play an important role in discharging. Considering the electric field aberration in the inter-electrode gap caused by the particles, the polarization of electric field is calculated and the influence of particle on electrical tree is analyzed in this paper. The results show that the local electric intensity of particles is very higher than that of the average electric field, and that the particles attract the electrical channel, so the growth of electrical channel is more quick and dispersive. Therefore, the discharge channel is apt to establish and increases much more in PMEDM than in conventional EDM, which accounts for the improvement in working stability of PMEDM.