At present, many scholars at home and abroad have studied the gear precision forging technology to varying degrees, and achieved remarkable results. Most of the research focuses on process design and optimization, die structure improvement and tooth profile design.
The research on spiral bevel gear abroad is early, develops rapidly and is technologically advanced. For example, several industrial developed countries such as Germany, the United States and Japan have been in a leading position. Spiral bevel gears produced abroad are in the leading position in the world in terms of manufacturing accuracy, fatigue strength and wear resistance. In the early 1990s, the emergence of six axis five linkage NC gear milling machine replaced all transmission chains and adjustment links. It can process all kinds of spiral bevel gears without manual intervention, which greatly improved the production efficiency and product quality. Each country also has its own unique research and opinions on different processing technologies, so it presents its own unique development model.
With the development of computer science, simulation becomes possible. Russia and the United States use spatial meshing geometry and machining kinematics for mathematical modeling, realize the three-dimensional solid modeling of spiral bevel gear by finite element analysis, and use gap element method for non-linear contact analysis.
In the 1990s, Japan made some progress in the experimental research on the die forging of spiral bevel gear. After many tests, the steel sample of spiral bevel gear with small cone angle was forged. Ravikiran duggirala used the numerical simulation method to seek the flow law of metal forming in the forging process of driven spiral bevel gear, optimized the die, and analyzed the stress and stress distribution of the die by using the stress analysis software in the forging process; J. C. Choi et al. Analyzed the forming process of helical gear by using the upper bound method and compared it with the experimental results.
BLW company in Germany is the first manufacturer in the world to use friction press to produce precision forged gears. The processing technology is suitable for bevel gears with modulus of 2 ~ 12 and diameter of 25.4 ~ 300mm. The accuracy is grade 6. It is widely used in the production of spur bevel gears of construction machinery such as automobiles and tractors. The United States, Japan and Britain have all introduced its patents.
At the end of the 20th century, the school of mechanical engineering of Birmingham University, together with gear manufacturers, gear users and steel companies, jointly developed and completed the precision forging of cylindrical spur and helical gears. The project studied and tested cylindrical spur gear, cylindrical helical gear and synchronizer gear. The steel gear is forged at 850 ~ 900 ℃, the tooth profile error is 0.1mm, and the surface roughness is ra = 3 ~ 5 μ m. The dimensional error can be controlled within 0.1 ~ 0.2mm.