Study On Electrical Discharge Milling Technique With Wire Electrode

Comparing with conventional Electrical Discharge Milling (EDM Milling) using cylindrical electrode, EDM Milling with wire electrode appears to be a novel kind of EDM Milling technology that has the distinct advantage of electrode compensation via the wire electrode slow traveling. In this thesis, the discharge characteristics, mechanical structural design, process rules have been studied. It's anticipated that this developed skill could overcome the difficulty of electrode compensation in traditional EDM Milling, promote the popularization of EDM Milling, and enrich the variety of EDM. Furthermore, the technology has the potential significant influence on the development of EDM and mechanical manufacturing technology.To begin with, the discharge characteristics in EDM Milling with wire electrode have been analyzed. It's found that the technology has the characteristics of periodicity of revolving and discharge localization through the mathematical model of the gap states. It's also believed that the normal discharge and arc are both effective discharge for the revolving of wire electrode. Furthermore, it's found that the breakdown time is random.In order to further research this technology, the machining device of EDM Milling with wire electrode is designed. According to the discharge characteristics, the servo control strategies are established. Then the x-axis master-slave servo system is designed to drive the x-axis movement. In this system, the RS232 serial communication is adopted between the master and slave system, which the master one is personal computer (PC) programming by Visual Basic, while the slave one is single-chip programming by assemble language. During the machining period, the system controls the machining process by overall information getting from the discharge gap in a servo period with the help of pre-defined rules.Finally, the EDM Milling process with wire electrode is studied using the designed machine setup above. It's worked out the effects of the machining parameters including electrical parameters and non-electrical parameters on the performance characteristics such as material removal rate (MRR) and surface roughness (SR). Then process optimization is carried out by choosing the apt input factors, a new approach for the process optimization based on the orthogonal array coupled with the grey relational analysis is studied. Optimal machining parameters can be determined by the grey relational grade as the performance characteristics, a confirmation experiment of the optimal process shows that the targeted multiple performance characteristics are improved to achieve more desirable levels. In this study, the machining parameters, namely, electrical parameters such as pulse duration, pulse interval, peak current, non-electrical parameters such as wire electrode feed speed and wire guiding pole rotating speed are optimized with considerations of multiple performance characteristics including MRR and SR. Herein, The study also compares EDM Milling using rotating electrode without compensation and EDM Milling with wire electrode that compensated through wire electrode slow traveling. It's found that the wire compensation can achieve better machining accuracy through wire traveling.