Helical gears will produce vibration, noise, stress concentration and other phenomena in the meshing process. In order to improve the service performance of helical gears in the transmission process, the modification of helical gears is a very important part. Helical gear modification includes tooth profile modification and tooth direction modification. Since walker Since H first proposed the concept of helical gear modification, people began to explore the helical gear modification technology. In recent years, many scholars at home and abroad have deeply studied the modification of helical gears and have been widely used. Oswald F B and Lin h studied the influence of helical gear modification on the static and dynamic deformation of helical gear after force. Kousaku Ohno et al. Used the finite element method to conduct static analysis on the contact stress of gear teeth during meshing, and compared and analyzed the contact stress of helical gear at different meshing positions before and after tooth profile modification. Tavakoli has also done relevant research on the error of helical gear transmission, and put forward the method of tooth profile modification. Hoyashita Shigeru also conducted in-depth research on the tooth profile modification of helical gears. Yoshino Hidehiro and others studied the modification method of helical gear and helical gear. At the same time, they made a new design of hob and processed the modified helical gear without transmission error.

At home, many scholars have also done a lot of research on helical gear modification, and achieved some results. After considering the deformation of helical gear shaft and the elastic deformation of gear teeth under load, song Lemin designed drum teeth for the tooth surface indentation and spalling of high-speed and heavy-duty helical gears, which proved that it is more comprehensive than other methods in minimizing the load concentration of drum teeth. Based on the theoretical analysis of contact finite element, Li Shaobin studied the deformation stiffness of gear teeth in the meshing process, obtained the modification curve and maximum modification amount of gear teeth, and finally obtained the design method of tooth profile modification of involute helical gear. Sun Jianguo and others used the explicit dynamic calculation method of ANSYS / LS-DYNA to analyze the dynamic contact stress of helical gear pair at different speeds, came to the conclusion that the standard involute helical gear produces large meshing impact due to elastic deformation, and proposed that the meshing impact of helical gear will be significantly improved after modification. Lin zenian modified the helical angle of the helical gear in the tooth direction modification, compared and analyzed the contact stress of the helical gear before and after the modification by using ANSYS Workbench software, and confirmed that the helical angle can greatly improve the uneven distribution of the load in the tooth direction of the helical gear. Through experiments, Zhang Yongzhong and others studied the transmission performance of helical gears before and after modification, and came to the conclusion that modification can effectively improve the transmission performance of helical gears.

Zhan Dongan and others studied the transmission characteristics of high-speed helical gears and the reasons for the need for tooth modification. At the same time, they further studied the design principle of spur high-speed helical gear tooth modification, and gave the empirical formula for calculating the modification amount. Li Shaobin studied the tooth profile modification of helical gear by using the contact finite element method, obtained the maximum modification amount and modification curve of gear teeth, pointed out that the accurate calculation of tooth profile modification is relatively complex, and put forward the simplified formula of tooth profile modification. Cheng Guoyu put forward the design principle of tooth direction modification of high-speed helical gear and the empirical formula for calculating the modification amount. Xie Jiafeng studied the tooth profile modification of helical gear by chemical and mechanical methods, deduced the calculation formula of corresponding modification amount, and came to the conclusion that high-precision modification of helical gear can be realized by grinding method. Zhang Hongli used ANSYS software to simulate the stress of helical gear pair before and after modification under loading conditions based on finite element analysis theory, compared and analyzed the bending strength and contact strength stress distribution diagram of helical gear before and after modification, verified the tooth profile modification theory, and obtained the range of tooth profile modification.

To sum up, a large number of studies on helical gear modification at home and abroad have confirmed that helical gear modification can effectively improve the working condition of helical gear. Most of them first calculate the modification curve and deformation range, and then determine the required modification amount according to the working condition of helical gear.