Study On EDM Forming Method Of Complex Surface Based On Multi-material Electrodes

As the number of difficult-to-machine material workpieces with surfaces of different complex structures and special machining processes increases,it is difficult to meet the machining requirements and ensure machining accuracy as well as machining efficiency.Some multi-material electrodes which have some special functions are regularly taking the place of traditional single material electrodes on some machining occasions and becoming widely used.In this paper,a method for machining complex surfaces by using EDM with multi-material electrode wear characteristics and shape change rules were studied.The complex surface was directly machined by the method based on the complicated shape of the formed electrode wear back end face.Comparing to EDM milling method,it could improve the processing efficiency and the quality of the surface.The studies are as follows:(1)The probability of multi-material electrode discharge breakdown was taken as the research goal.According to the field electron emission theory,the effect of electrode materials for discharge breakdown rule is studied.A comparison model where electrode material influences the discharge breakdown was established in the case of a single discharge and continuous discharge.The material properties that affect the discharge breakdown probability were analyzed and the probability of discharge breakdown of different electrode materials was compared by experimental methods.Repeated experiments with continuous discharges provided a relationship between the probability of discharge and the properties of different materials.The comparison between theory and experimental results validated the effectiveness of the comparison model.(2)The shape change rule of multi-material electrodes in EDM was taken as the research objective,a 2-D simulation model of electrode shape variation for multi-material electrodes and workpieces was established.Based on the MATLAB software,programs were compiled for the simulation process,the shape change simulation was predicted for different combinations of multi-material electrodes,the die steel is taken as the processing objective,different combinations of multi-material electrode machining were tested to study the changing rule of multi-material electrode shape.Compare the simulation results with the experimental results,the validity of the simulation model was verified,and the model had a better shape predictability.(3)In order to study the multi-material electrode forming complex surface according to the study of multi-material electrode wear and shape change law,a multi-material electrode was designed based on the complex curved surface processing requirements,and the multi-material electrodes were bonded by hot tinning method.The well-prepared multi-material electrodes were tested with various combinations.The results of the study showed that the multi-material forming electrodes are not likely to fall off or crack during the processing with hot tinning method.And it had good processing performance and was able to realize the forming of complex surfaces,and the complex surface after processing was smooth and change the uniform smooth surface.The feature of the machining surface is greatly influenced by the multi-material electrode material,the shape change and the arrangement order of the materials.The curvature of the transition surface formed by the electrode with a large difference in processing speed is larger.The curvature of the transition surface processed by the electrode with a small difference in processing speed is smaller.And the electrode arrangement order can be reasonably selected according to the requirements of the processing surface.