Surface Burnout And Control In High-speed Grinding Of Particulate Reinforced Titanium Matrix Composites

Particulate reinforced titanium matrix composites(PTMCs)has excellent physical and mechanical properties,such as high strength,temperature resistance and corrosion resistance,which makes it have broad application prospects in aerospace and aviation industry.However,PTMCs is a late-model hard-to-machine material with high strength,toughness and hardness.At present,although a series of theoretical and experimental studies have been carried out on the high-speed grinding technology of PTMCs with CBN abrasive wheel,there are still a lot of technical challenges to overcome such as low machining efficiency and surface burnout.In particular,due to the lack of quantitative evaluation system of grinding burnout and effective prediction method of grinding temperature in high-speed grinding of PTMCs,the basic data and theoretical support are inefficient to develop the grinding parameters.In view of this,surface burnout and control in high-speed grinding of particulate reinforced titanium matrix composites was investigated by combining grinding experiment and the finite element simulation.Based on this,a quantitative characterization method of surface burnout was developed,the relationship between grinding temperature and surface burnout was established and the influence of grinding parameters on grinding temperature and surface burnout was expounded.Finally,the grinding parameters were optimized and the control of surface burnout was achieved to a certain extent,which had great significance for realizing high-quality and precision machining of PTMCs.The main research work and achievements are as follows:(1)The surface color characterization method for burnout of PTMCs was developed.The color of ground surface was described digitally by using the HSV color space model.On this basis,the classification and evaluation method of surface burnout was established.Accordingly,the relationship between grinding temperature and surface burnout were established.Finally,a prediction model of grinding force based on neural network was established.The results show that the influence of grinding temperature on surface burnout was in accordance with Boltzmann distribution equation.And the variation of burnout with the increase of temperature can be divided into three stages:slow rising stage without burnout,rapid rising stage with light/moderate burnout,slowly increasing and eventually stabilizing with severe burnout.(2)A three-dimensional finite element simulation model of temperature field in high-speed grinding of PTMCs was established and verified experimentally.Based on this,the characteristics and evolution of temperature field were revealed and the effects of process parameters on grinding temperature and grinding burnout were clarified.Results indicated that the degree of surface burnout increases slowly with the increase of grinding speed,workpiece infeed speed and depth of cut when grinding burnout does not occur.However after burnout occurs,the increasing rate of surface burnout increases obviously with the increase of process parameters.(3)The prediction models of surface burnout,specific grinding energy and material removal rate were established as evaluation criteria of grinding parameters optimization.Based on this,the optimum grinding parameters without grinding burnout,high machining efficiency and low energy consumption were obtained through the multi-index fuzzy evaluation criterion analysis method.That is grinding wheel speed v_s=94m/s,workpiece infeed speed v_w=4m/min,depth of cut a_p=35um.And the finished machining surface was evaluated when using the optimum parameters,and the ground surface was found with free defects.