Study on the servo control system of MWEDM

An ultra-precision servo control system for MWEDM ( micro wire electrical discharge machining) based on piezoelectric ceramic motor drivers was developed. The servo discharge detection adopts an average voltage detection method, utilizes statistical methods to analyze the measured data, then controls discharge gap and makes the process more stable. The servo feed system based on DSP microprocessors applies a PID controller with incomplete derivation to reduce overshoot to improve machining accuracy, and also adopts adaptive dead-zone inverse compensation to eliminate dead-zone caused by piezoelectric ceramic motions in low servo feed speed. The simulation results show that the methods proposed in this paper can make the system recover its linearity and converge the dead-zone parameters. It is proved that the method proposed is efficient in solving this problem. Cooperating with a micro energy pulse generator, this equipment's machining accuracy is smaller than ±0. 2 micron, and surface roughness Ra is less than 0. 1 micron. Punch die and cavity die (micro gear die, module 100 micron, thickness 3.5 millimeter) have been machined independently in two die steel workpieces. These pieces can mate very well to work, which shows that the servo control system satisfies the need of MWEDM for high precision micro fabrication.