Adopting the compound forming process of hot forging and cold finishing the tooth shape can eliminate the defects of oxidation and low precision in the tooth shape of bevel gear, and achieve the purpose of refining the tooth blank of bevel gear. The compound forming process scheme first uses the hot forging method to form the tooth blank similar to the bevel gear tooth shape, and then uses the cold extrusion method to finish the tooth part of the bevel gear tooth blank to reach or close to the required specification and size of the part. The quality of cold finishing, the forming force and the service life of the die depend on the finishing quantity and the way of metal deformation in the finishing process. Therefore, the reasonable formulation of finishing quantity and the structure of finishing die is the key to the cold finishing of bevel gear.
Based on the compound forming process of hot forging and cold finishing of bevel gear tooth profile, combined with the characteristics of cold finishing, two forming process schemes of closed cold finishing and open cold finishing are put forward. The forming process of the two process schemes is numerically simulated and analyzed by using DEFORM-3D finite element software, and the finishing quantity of bevel gear tooth blank is studied. The following conclusions are obtained:
1) Open type cold finishing shall be selected as the process scheme for forming tooth profile of bevel gear cold finishing. The bevel gear tooth blank with the same structure and volume is selected for numerical simulation of different schemes. The maximum forming force of open cold finishing scheme is 8220kn and that of closed cold finishing scheme is 8860kn, which is reduced by 7.22% and improves the service life of the die.
2) Under the condition of reaching the cold finishing accuracy of bevel gear tooth blank, the finishing amount of bevel gear tooth blank λ It should be as small as possible. With the amount of finishing λ The metal material flows more violently and the equivalent stress increases. The forming force at the end of finishing increases with the amount of finishing λ Gradually increase with the increase of.
3) The split flow finishing of bevel gear top can reduce the forming force. After the tooth root circle of the female die is expanded, the metal at each point on the tooth top of the bevel gear blank flows unrestrained. The forming force at the end of the forming is 7530kn, while the forming force at the constraint of the bevel gear tooth top is 8220kn, which is reduced by 8.39% and improves the service life of the die.