Study On The Influence Of Tool Electrode Material And Shape On Short Arc Milling Machinability

Short arc milling(SEAM)is a new process that relies on electrical energy and thermal energy for thermal erosion processing.It is based on continuous arc plasma high energy beam between non-contact poles to melt or vaporize the surface material of the work-piece and the stripping removal is completed under the action of the water mist mixed medium,which belongs to non-contact electric discharge machining and is a kind of special processing technology.Based on the non-contact processing mechanism of SEAM,the change of electrode material,shape and electrical parameters will directly affect the processing performance and surface integrity.Therefore,the study on the influence of tool electrode and electrical parameters on processing performance is one of the focus of short arc milling.In this paper,the short arc milling machining mechanism in gas-liquid mixed medium environment is deeply analyzed through processing characteristics experiments.The experiments of short arc milling with tungsten-copper alloy,graphite and copper electrode show that the tungsten-copper electrode and graphite electrode can achieve better processing results.Then,based on the experimental analysis of processing performance and surface integrity of a drilled graphite and tungsten-copper electrodes,the suitable electrode materials for short arc milling with high efficiency and low loss are selected.By carrying out the experiment on the influence of the electrical parameter on short arc milling effect,the electrical parameters directly affecting the process index are obtained,which provides a theoretical basis for the subsequent optimization of the electrical parameters.In order to improve the flushing effect,the surface quality and removal efficiency of corrosion products in the discharge gap,the dielectric flow field in short arc milling machining is studied by theoretical analysis and simulation.The influence of electrode diameter on scouring effect is simulated and validated by actual processing.On the basis of the existing electrode structure,the electrode structure is improved to be an electrode in which the middle hole and the ring hole are matched.Through simulation analysis and experimental research,the structure improves the inter-prime flushing effect,improves the gap discharge stability,and solves the problem of no effective flushing between the poles in the initial stage of side milling.By establishing the temperature field model,the temperature distribution in the flushing environment and the influence on the working fluid flow rate on the inter-electrode temperature are studied.Based on the experimental data,the influence of electrical parameters of SEAM on machinability and surface integrity is analyzed.In this paper,the fast non-dominated NSGA-II genetic algorithm is used to optimize the electrical parameters directly affecting the process index to achieve high efficiency,low loss and high quality processing.Firstly,the BP neural network algorithm is used to establish the parameter model for short arc milling discharge data and verify the accuracy of the model.Secondly,the established neural network model is optimized by using NSGA-II algorithm to obtain the optimized discharge parameter model.Finally,the discharge parameters used as test data are compared with the prediction results,and the optimized parameter model has higher accuracy,which provides technical support for the setting of electrical parameters in short arc milling in the future.