Forming speed is also an important factor affecting the precision forging of spiral bevel gear. Because the process of plastic deformation is very complex, when the forming speed is large, the plastic deformation does not have enough time to expand and complete in the deformation body, resulting in the increase of deformation resistance. However, due to the existence of thermal effect and temperature effect during plastic deformation, when the forming speed is large, the metal temperature will rise. From the analysis, it can be known that this will lead to the decrease of deformation resistance. Therefore, the forming speed not only improves the metal plasticity, but also reduces the metal plasticity.
Under the condition that the initial forging temperature is 1150 ℃ and the shear friction coefficient is 0.3, three finite element models with forming speeds of 50mm / s, 150mm / s and 200mm / s are selected to investigate the influence of forming speed on the precision forging of spiral bevel gear, and the load stroke curve is obtained as shown in the figure.
The simulation results show that for the precision forging of spiral bevel gear, the forming load increases with the increase of forming speed. When the forming speed is 150mm / s, the forming load increases by 6.25% compared with 50mm / s, and when the forming speed is 200mm / s, it increases by 17.8% compared with 50mm / s. When the forming speed is 50mm / s, the forming load is not significantly lower than 200mm / s, but in terms of forming efficiency, the former is only 1 / 4 of the latter. In addition, the lower the forming speed, the longer the contact time between the hot blank and the die bore, and the easier the die is to fail due to thermal fatigue. Therefore, considering the above aspects, the optimal forming speed of precision forging of spiral bevel gear is 200mm / s.