微小间隙火花放电的伺服控制特性实验研究

Experimental Research on Servo Control Characteristics of Electrical Discharge in Micro Gap

为探索微小间隙火花放电的伺服控制特性,利用高速示波器和非接触式电涡流位移传感器,采用门槛电压阈值控制方法,实验研究了微小间隙火花放电规律与主轴伺服运动特性之间的关系,得出了主轴频响和运动速度对放电率的影响规律。并利用频响达200 Hz的直线电机主轴,验证了高频响主轴伺服控制微小放电间隙的优越性。研究发现:开短路交替频率、主轴跳动幅值、开短路率大小及比例可作为放电效果的评价指标;深度效应将造成一个特定深度的加工状态破坏点。这些结果为优化主轴机构和伺服控制策略提供了依据。

In order to explore the servo-control characteristics of electrical discharge in micro gap, several basic experiments had been carried out to study the relations between electrical discharge and spindle movement in micro EDM. By using a high-speed oscillograph and an eddy-current displacement sensor, we gained the effects of response frequency and velocity of spindle on discharge ratio based on threshold-control method. The machining experiment was also made by applying a linear-motor spindle with a frequency response up to 200Hz to verify the advantage of high-frequency-response spindle in controlling micro discharge gap. The study results show that the parameters including the alternating frequency between short-circuit and open-circuit, the amplitude of spindle jump, and the proportion of open-circuit ratio and short-circuit ratio, can be used to evaluate discharge effectiveness. Moreover, Depth Effect results in a damage point of machining state at a certain depth. These results provide the theoretical basis for optimizing the mechanism design and the servo-control strategy of spindle in micro EDM.