镁合金低温切削性能及工艺参数优化

To improve the machinability and surface integrity of magnesium alloys, and optimize the machining parameters, a set of orthogonal experiment with four factors and four levels were carried out based on the method of pseudo-level. Comparative study involved in the influence of three different cooling strategies, namely, dry cutting, liquid carbon and liquid nitrogen coolants, as well as the cutting parameters on the surface integrity of ZK61M magnesium alloy during turning were conducted. The experimental results show that the effect of cutting depth on cutting force is the most significant factor, the feed quantity is the second significant factor, the effect of cutting speed on cutting force is ignorable. Although the effect of cryogenic cutting on cutting force is not significant, it can reduce the cutting force in some extents. The feed rate has a significant effect on the surface roughness and surface residual stress. As the feed rate increasing, the surface roughness increases and the residual stress is introduced on the machined surface. The cooling medium has a sub-significant effect on the surface roughness and surface residual stress. Compared with dry turning, The cryogenic coolants can effectively reduce the surface roughness, refine the surface grain and increase the surface compressive residual stress during cutting. As a cooling medium, the liquid carbon dioxide is more effective than liquid nitrogen in improving the machining-induced surface integrity. Grey relational analysis is used to obtain the optimal process parameters for cryogenic cutting of ZK61M magnesium alloy: v_c= 100 m/min, f= 0.05 mm/r, a_p= 0.4 mm, liquid carbon dioxide is used as the cooling medium. The response prediction model between the process parameters and the machined surface quality was established through the results of the relational analysis, the average error was 7.93%.