主轴式滚磨光整对齿轮表面完整性的影响及工艺参数优化

Gear parts are the core basic components in many different application areas, such as aviation, aerospace, shipbuilding, rail transportation and marine equipment. The surface integrity characteristics of gears are crucial for their long life, low noise, and high operational performance. Barrel finishing is widely used as the last process to improve the surface integrity of gear parts. Regarding the issue of the lack of basic data on surface integrity and unclear process control rules in spindle barrel finishing, the work aims to explore the effects of different spindle barrel finishing parameters on the surface integrity of gears, and optimize the process parameters. With single factor and response surface methodology, the spindle barrel finishing experiments were carried out to 8620RH cylindrical spur gears. Then, the surface roughness, surface topography, residual stress, microhardness, and microstructure of the tooth surface were measured and the effects of spindle barrel finishing parameters on the surface integrity characteristics were discussed. The relationship between the surface integrity characteristics and the spindle barrel finishing parameters was established through multiple linear regression analysis. Spindle barrel finishing parameters were optimized with improved grey correlation degree analysis method, and verified by experiments. The 3D surface roughness S_a of the tooth surface after spindle barrel finishing was reduced from 0.280 μm to 0.089 μm. The surface roughness decreased and tended to be stable with the increase of the embedding depth, spindle speed, and finishing time. The surface topography and surface texture were uniform and consistent after spindle barrel finishing process. The residual stress states of processed gears were compressive, with the maximum value on the surface. The compressive residual stress along the tooth height direction was larger than that along the tooth width direction, and the depth of the compressive residual stress affected layer was approximate 40 μm. The surface of gear was hardened and the maximum degree of hardening was 9.9%. The depth of the hardened layer and plastic deformation layer was appropriate 40 μm and 5 μm, respectively. Spindle barrel finishing could enlarge the compressive residual stress and microhardness values within a range of 20 μm below the surface, but had not significant effect on the depth of the affected layer. Prediction models of surface integrity characteristics were established through multiple linear regression analysis, the P value of these models was less than 0.000 1, and the coefficient of determination R² was more than 0.94. Based on the grey correlation analysis method, an improved model of the relationship between grey correlation and process parameters was established. The optimal combination of spindle barrel finishing parameters was obtained with the goal of maximizing grey correlation, which was the embedding depth of 166 mm, spindle speed of 130 r/min, and finishing time of 80 min. The optimized parameters were experimentally validated, and the prediction error of the surface integrity characteristics was less than 7%. It can be seen that spindle barrel finishing can remove the gear grinding traces, reduce the surface roughness and improve the compressive residual stress and microhardness in the range of 0~20 μm below the surface. The effects of spindle barrel finishing process parameters on the surface integrity characteristics and establishes the prediction models of surface integrity characteristics are clarified, which can provide basis data and process method for controlling high surface integrity of gears.