微细电火花加工中的放电能量分布研究

Study on the discharge energy distribution in micro EDM

微细电火花加工技术已经广泛应用于精密制造领域,然而由于尺度效应的存在,其加工机理特别复杂,对于放电蚀除过程中的放电能量分布尚未明确。开展了微细电火花单脉冲放电实验,并考虑到熔化潜热和汽化潜热的影响,对传统的电热模型进行了修正,基于微细电火花的放电持续时间,计算了分布到工件中的能量分布比。结果发现,由于放电初期有相当一部分的放电能消耗于放电通道的形成,所以传入工件中的能量分数随着放电持续时间的增加而增大,在放电持续时间0.63~20.5μs时,分布到工件上的放电能量分数为7.1%~16.3%。伴随着放电持续时间的持续增加放电等离子体通道半径将会一定程度增大,放电等离子体通道半径随放电持续时间的变化范围是5.9~23.2μm。

Micro EDM technology has been widely used in the field of precision manufacturing.However,due to the existence of scale effect,its machining mechanism is particularly complex.The distribution of discharge energy during the EDM process has not been clarified.The micro single pulse electrical discharge experiment was carried out,and the traditional electrical heating model was modified considering the influence of the melting latent heat and the vaporization latent heat.Based on the discharge duration of the micro EDM,the energy ratio distributed to the workpiece was calculated.The results show that the energy fraction distributed to the workpiece increases with the increase of the discharge duration because a considerable part of the discharge energy is consumed by the formation of the discharge channel at the initial stage of spark discharge.When the discharge duration is 0.63—20.5μs,the discharge energy fraction distributed to the workpiece is 7.1%—16.3%.With the continuous increase of the discharge duration,the discharge plasma channel radius would increase to a certain extent,and the variation range of the discharge plasma channel radius with the discharge duration is 5.9—23.2μm。