| As a special machining method,EDM has the characteristics of non-contact machining,which is considered as one of the most effective machining methods for SiC_P/Al composites.However,there are still some problems to be solved in the process of EDM of SiC_P/Al composites,that is,there are many influence parameters of EDM and they are restricted by each other,so it is difficult to select a group of process parameters that best meet the production needs.Therefore,aiming at the problem of difficult selection of technological parameters in EDM of SiC_P/Al composites,this paper studied the influence law of main influencing parameters on EDM of SiC_P/Al composites through software simulation,and established a multi-objective genetic algorithm to obtain the process parameter combination with the highest processing efficiency and the lowest surface roughness.The main research work is as follows:(1)based on the multi-phase material properties of composite material and the theory of heat propagation,the physical properties of SiC_P/Al matrix material and reinforcing particles were distinguished,and a two-dimensional model of SiC_P/Al composite single pulse erosion process with the change of heat source and electrical parameters was established.Melting/solidification module in FLUENT software was used to simulate the model.The influences of pulse width,peak current and open circuit voltage on the size and machining efficiency of pits were obtained by using different combinations of electrical parameters as input.The average error between the predicted machining efficiency value and the actual machining efficiency value is 8.79%.(2)Using the fractal method,the Weierstras-Mandelbrot(W-M)fractal function was introduced to predict the surface roughness of the SiC_P/Al composites in EDM,and the random discharge model of the SiC_P/Al composites in EDM was established.The two-dimensional surface topography of random discharge pits was established by using MATLAB software,and the fractal dimension and scale coefficient were extracted by using wavelet transform.The fractal surface morphology of the macroscopic rough surface was simulated by using fractal parameters as input conditions.The corresponding relationship between the micro-surface morphology of machining discharge pits and the macroscopic surface quality was established.Then,the influence laws of pulse width,peak current and open circuit voltage on the machining surface quality were summarized.Experimental results show that the average error between the predicted surface roughness and the actual surface roughness is 4.71%.(3)Taking pulse width,peak current and open-circuit voltage as decision variables,taking machining efficiency and surface roughness as optimization objectives,the fitness function was established by using linear weighted combination method,and the multi-objective genetic algorithm(GA)program structure of SiC_P/Al composite EDM was written by using MATLAB software.The machining efficiency was the highest.Multi-objective parameter optimization was carried out for the lowest surface roughness.The optimized results showed that the open-circuit voltage was 77.07V,the peak current was 2.60A,the pulse width was 26.18μs,the material processing efficiency was 1.89mm3/min,and the surface roughness was 3.08μm.The research work in this paper can grasp the influence of electrical parameters on the EDM of SiC_P/Al composites,and put forward an improved computer optimization method for the machining quality of SiC_P/Al composites,which has important guiding significance for improving the machining capacity of SiC_P/Al composites. |
