Research On Surface Quality Of Cylindrical Gear Ultrasonic Form Grinding

As an important part of transmitting motion and power,gears are widely used in various processing and manufacturing fields due to their various transmission forms,stable transmission processes and high transmission efficiency.With the continuous development of science and technology,gear manufacturing technology is developing with the new goal of surface integrity to the direction of "anti-fatigue manufacture" with synergistic shape and performance.Gear surface micro-profile geometric features,surface residual stress and micro hardness and other parameters are important characterization parameters for gear anti-fatigue manufacture and surface integrity research.Therefore,how to obtain better grinding surface quality through new processing methods or solutions has become an urgent problem.Relevant research shows that the high-energy impact of abrasive grains and high-frequency intermittent machining mode under ultrasonic-assisted grinding have significant effects on improving the quality of the ground surface.Therefore,in this paper,through the theoretical analysis of the gear ultrasonic form grinding acoustic system and the establishment of an experimental platform,the law between the tooth surface quality characterization parameters and the grinding processing parameters after the cylindrical gear ultrasonic form grinding process was explored.The specific research content and conclusions are as follows.(1)The gear ultrasonic form grinding acoustic system was designed by the integral non-resonant design method,and then the acoustic vibration characteristics such as resonance frequency and vibration mode of the acoustic system were verified by finite element analysis and ultrasonic vibration resonance test.The results showed that the gear ultrasonic form grinding acoustic system had good vibration effect,stable and controllable amplitude output.(2)By setting up a gear ultrasonic form grinding experimental platform,a cylindrical gear with a material of 12Cr2Ni4 A,a modulus of 3mm,and a tooth number of 21 was subjected to orthogonal and single-factor tests under ultrasonic grinding and traditional grinding.Then,based on the above experiments,the changes of grinding force and grinding heat under different grinding parameters during gear grinding were analyzed.The results showed that the high-frequency intermittent machining mode can reduce the contact time between the abrasive particles and the workpiece,which was conducive to the diffusion of grinding temperature,so it can effectively reduce the grinding force and grinding heat.(3)Based on the theoretical analysis of the geometric characteristics of gear form grinding,the variation of grinding parameters with the involute rolling angle on the tooth surface was studied.At the same time,the grinding heat during the grinding process and the distribution of the surface micro-morphology and surface residual stress along the involute of the gear were measured.The results showed that under the same processing parameters,the local normal grinding depth on the tooth surface and the local linear velocity of the grinding wheel gradually increased with the increase of the involute rolling angle.After grinding,the depth and width of grinding groove increased with the increase of involute rolling angle.At the same time,the grinding heat and surface residual stress were increasing and decreasing with the increase of the involute rolling angle,respectively.(4)The changes of surface quality characterization parameters such as surface micromorphology,surface roughness,residual stress and micro-hardness of the tooth surface after grinding were studied.The results showed that ultrasonic grinding was helpful for cutting and removing gear materials,reducing the occurrence of grinding surface defects,and expanding the plastic processing ratio of gear materials to a certain extent,so as to obtain the ideal surface micromorphology and roughness.At the same time,ultrasonic grinding can enhance the plastic deformation of the gear material,reduce the softening effect of thermal stress,increase the residual compressive stress of the tooth surface between 17.8%-24.2%,and the micro-hardness between 1.1%-7.1%,so as to obtain better quality of the ground surface.