Temperature Modeling Single Spark Discharge And Process Optimization In WEDM

Wire electrical discharge machining(WEDM) belonging to non-contact processing technology, and the material removed by a large amount of heat energy produced by discharge between tool electrode and workpiece. It has been widely used in the processing of hard-to-machine materials with high hardness, high brittleness difficult and manufacturing of fractures with complex shape, small size or high precision demand, which greatly cover the shortage of traditional processing technologies. Because there is no one theory can explain the complexity of discharge machining process, process optimization has become a hot issue. Therefore, this paper focuses on the computer simulation and process optimization of precise WEDM.Considering the change of energy distribution coefficient, latent heat and Gauss heat source distribution, the temperature field model of electric spark pulse discharge is established and solved based on the finite element method. The calculating results were compared with the previous model and experiment, the comparison results show that our model is more close to the experiment, and can provide a reliable theoretical basis for WEDM. After the end of single pulse discharge, regional distribution of temperature field, and the radius and depth of the crater effected by the current, pulse width and voltage are studied.Process optimization is studied based on the single pulse temperature field model. The experiment is designed by BBD method, the MRR and Ra with different parameters by finite element is obtained. The analysis of variance is gained using RSM, and the regression model of MRR and Ra are received. The influence of process parameter on MRR and Ra is studied by signal to noise ratio(S/N) method. NSGA-II algorithm is used to optimize the MRR and Ra, the uniformly distributed Pareto front is got. The optimal process parameters combination is verified by the experiment.The 3D topography characteristic of the workpiece surface is described by using the fractal method. The experiment is designed by Taguchi method. The surface texture of workpiece is measured by 3D interferometer, and the fractal dimension was conducted to identify 3D micron-scale surface topography. The relationship of FD and Sq, the influence of each parameter on the FD, and the effect of interaction between process parameters are studied. Using the signal to noise ratio(S/N) method to obtain the optimal process parameters combination of FD, and the experiment is done to verify the optimal results, and compared to the initial parameter combination, the FD obtained from the optimal parameter combination increases 11%.Finally, the research results achieved in the dissertation is summarized and future work is generalized and looked forward.