Development Of Micro-EDM Control System

Micro Electro Mechanical System (MEMS) is recognized as one of the key developing subjects in the 21st century, and its development and requirements bring in new challenges to the modern fabrication, and the micro machining technologies has brought scholars around the world to pay attention on it more and more. As one of the important branches, the micro-EDM has revealed large potential in the fabrication of micro shafts, holes and 3D structures, with the advantages of easy to control, little machining unit and 3D fabrication.This paper adopts open system architecture, using Programmable Multi-Axis Controller (PMAC) as the core of the micro-EDM control system. As one of the most advanced and powerful controllers which are based on PC, PMAC runs its PLC programs and motion programs, to execute the fixed control policy which will persists inspecting the sparking states and driving the servo system to make sure the process goes well. The execution unit in this paper is composed by stepper motor and piezoelectric ceramic, with the advances of large range, small pace, high frequency response and so on, which can meet the need of frequently adjusting of the gap in micro-EDM.A power supply to piezoelectric ceramic is designed in this paper, consulting previous references of power supplies. This power supply follows the principle of DC amplifying mode, employing s a high-voltage DC amplifier and a power amplifier, with the advance of high dynamic response, which fulfills the requirement of servo control for electric system for micro-EDM.To meet the narrow width of pulses and high frequency in micro-EDM, this paper employs the method of average-voltage to detect the spark states, and adopts statistical manner to identify determine the spark states. According to the characters of the macro/micro execution unit and micro-EDM, this paper designs axial-vibration control policy, after satisfying the normal functions. This is of great benefits to debris removal, which leads to improve the machining status in gap between workpiece and electrode. The performance of the micro-EDM control system has been evaluated through micro EDM tests in this study.