Research on gear tooth forming control in the closed die hot forging of spiral bevel gear

Abstract

To improve the tooth forming quality of forging spiral bevel gear, a systematic hot forging method for spiral bevel gear is proposed in this paper, which helps to improve some defects in the traditional forging methods, such as the insufficient gear tooth corner filling, the high forming load, and the low die service life. With Deform-3D, the simulation analyses of the closed die structures are carried out to reveal the effects from the tooth forming process parameters, which are including the forging temperature, the strike speed, the die preheating temperature, and the friction coefficient. For further meliorating the addendum of tooth toe-end filling situation, an improved forging process with tooth preformed is presented. Thereinto, the excess material is reserved at the tooth toe-end position in preformed stage, so that the material flow velocity at the tooth toe-end area synchronizes with that at tooth heel-end area. Compared with the traditional process by the numerical analysis, the improved process can not only reduce more than 6% of the forming load but also relieve the sharp rising trend of finish forging load. Finally, the effectiveness of the improved process is verified through the forming experiments, and the results are in good agreement with the simulation ones, which can provide the theories foundation for enhancing the forging quality and decreasing the scrap rate of the forged spiral bevel gear.