Research On The Servo Control And Electrode Moving Path Planning In Micro-EDM Milling

Micro-electrical discharge machining(Micro-EDM) milling technology plays an irreplaceable role in processing precision parts and has many advantages:non-macroscopic mechanical force, unlimited material hardness, etc. But its disadvantages, to a certain extent, restricted the development and application of micro-EDM milling technology, which include low processing efficiency,uncontrollable precision, etc. Researches on the servo control and path planning which directly affect the accuracy and efficiency of the micro-components machining have important significance in micro-EDM milling.The model of AC servo control system of micro-EDM was established by Simulink in MATLAB. By simulation methods, the system was adjusted to processing demand by using PID control algorithm. The rise time is 24.2ms, the overshoot is 12.5% and the setting time is 84.6ms. On the basis of the different characteristics of micro-EDM, the servo feed speed of block electrical discharge grinding varies in proportion to the detected frequency, and the electrode moving speed of micro-EDM milling layered is controlled by fuzzy control algorithm.Experimental researches were conducted to obtain optimum process parameters.Based on programming of VC++, the fuzzy logic controller was integrated into the CNC system for improvement.Researches were conducted on the measurement of the discharge gap and its influencing factors to determine the offset of electrode in cavity machining. Based on the bottom morphology of electrodes and grooves, the optimum path overlapping ratio was determined to reduce the residual raised on cavity bottom surface. Based on the researches of the layer thickness, electrode moving speed and single-pulse discharge energy, the conclusions was obtained that the actual machining depth was influenced by layer thickness, single pulse discharge energy and electrode movement speed and existed an ideal electrode moving speed to make the actual machining depth and layer thickness equal. And the obtained conclusions can be used to guide the path planning in cavity machining.A concave square pyramid which boundary dimension deviation is less than1.5μm and the depth dimension deviation is less than 3μm was fabricated using the method of servo control and wreathed snake type path proposed in this dissertation.The results show that the proposed servo method and the improved wreathed snake type path can improve the dimensional accuracy, which verify the feasibility of improved servo control system and optimized milling path planning methods of micro-EDM.