Research On Ultrasonic Rolling Hardening Of Gear

With the rapid development of high-speed trains, the aerospace and defense fields, gears are widely used, meanwhile, there should be a higher standard for the stability and the transmission performance of the gear under the conditions of high speed and heavy load. How to improve the strength and surface quality of the gear becomes an important research direction in the field of drive gear. Strength and surface quality of the gear directly impact the quality and longevity of the entire transmission system. So the research of high quality, low-cost method of surface hardening gear has important practical significance.This paper describes the present situation of the development of gear tooth surface enhancement technology; the advantages and disadvantages of various types of enhanced methods are summarized and compared. A set of ultrasonic strengthening device which can be used for involute spur gears is built combined with ultrasonic rolling processing technology and the involute generative principle, implements the strengthen of the irregular tooth surface. The specific research works are as follows:(1) Determine the overall program of ultrasonic rolling processing on gears according to the principle of ultrasonic rolling technology. Complete the design of the feeding device by Inventor.(2) Complete the structural design of the ultrasonic tool. First, complete virtual structural design of the ultrasonic tool using Pro/E. Second, using finite element analysis method, the key structure and dimensions of the tool were determined based on optimization design, realizing the optimization goal of the longitudinal vibration frequency of the tool coincided with the exciting frequency of the ultrasonic generator. Finally, the processing and assembling of the new tool are completed. Experimental results demonstrated that the new tool met the resonant vibration requirement, and the simulated resonant frequency is basically consistent with experimental data.(3) Complete the selection and displacement analysis of the ultrasonic horn, and complete the error analysis of the position deviation generated during the installation. With the principle of maximum amplification factor at the equal area factor N, stepped ultrasonic horn is selected, determine the zero displacement node of the horn by simulation analysis, and analysis the offset between the tool track and standard involute by Matlab.(4) Complete of the ultrasonic-enhanced experiments, analyzed and summarized the results. Different experimental program were implemented on different gear tooth to analysis the effect of static pressure and processing times on gear tooth profile deviation, tooth surface roughness and the distribution of the residual stress.After the ultrasonic rolling treatment, tooth surface roughness of the enhanced gear has a significant improvement; meanwhile, it becomes stable when the roughness decreases to a certain level. Residual stress at the surface manifests as residual compressive stress, and it becomes greater as the static pressure and processing times increases; for tooth profile deviation, ultrasonic rolling processing has little correction effect.