Development Of Micro-EDM Servo Control System

Micro Electro Mechanical System (MEMS), recognized as one of the key developing subjects in the 21st century, 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 real 3D fabrication.On the basis of a great lot relevant literatures, control system has been designed and developed according to requirement of micro-EDM.A combined device with piezoelectric ceramic and step motor has been employed as servo control system in this study. With the advantage of large range, small pace, high frequency.The core of the control system is based on PMAC.which has strong control function and great flexibility.Driving circuit for piezoelectric ceramic is a important factor in performance of piezoelectric ceramic. Consulting previous references of driving circuit .A driving circuit for piezoelectric ceramic is designed in this study, which follows the principle of dc amplifying mode. This driving circuit with high dynamic response employs a high-voltage DC amplifier and a power amplifier, this driving circuit fulfills the requirement of servo control for micro-EDMSoftware and hardware of control system have been designed and developed. Making use of resource of PMAC, the connection of PMAC and peripheral circuit has been realized. The bus connection and DPRAM connection of PMAC and host are quick and reliable. So the control system is featured by compact construction and reliability. According to the characters of the macro/micro execution unit, the electrode in the study implements not only the normal forward-and backward electrode movement, but also axial-vibration electrode movement, this is of great benefit to debris removal, which leads to improve the machining status in the gap between work piece and electrode.The performance of micro-EDM system has been evaluated through micro- EDM tests in this study. A 17-micrometer-diameter shaft and 30--micrometer-diameter hole have been machined.