The forming process of closed type cold precision forging is shown in the figure. First, the upper and lower forming dies are closed and a certain working load P1 is applied to compress, and the blank produces a certain deformation in the closed die cavity. Then, the compound punch applies pressure P2 and P3 to make the blank produce multi-directional flow, so that the gear parts are cold precision plastic formed in one deformation process. The advantages of this forming scheme are low equipment investment, convenient use and maintenance, and wide process adaptation.
The numerical simulation of precision forging process of spur bevel gear and the precise design method of its forming die cavity were carried out by using this forming process scheme.
When the closed forging process is used for precision forging of spur bevel gears, the main factors affecting the smooth filling of the die cavity by metal are the shape and size of the blank, the dimension parameters of the die cavity, the movement speed of the punch and the friction factors. Reasonably designing the forging shape of bevel gear, selecting the appropriate blank size, and controlling the extrusion speed and friction conditions of upper and lower punches can effectively control the metal flow law, so as to ensure the smooth filling of the tooth cavity.