The traditional and improved processes are used for experimental study. The typical deformation conditions of the blank during the deformation process under the two processes are shown in Fig. 1 and Fig. 2. It can be seen from the figure that in the forming process, both of the two processes show ideal effect, the tooth cavity can be filled, and the tooth shape is good.
Through comparison, it can be found that there are obvious differences between the two forming processes in the contact mode between the tooth shaped area of the blank end face and the punch. During the upsetting and extrusion process of the toothed punch, the above contact state always exists; during the upsetting and extrusion process of the toothless punch, the above contact only occurs after the forming (Fig. 2C) (Fig. 1c and Fig. 2c, i.e. No. 90) The difference between the two is very obvious. The area in the circle represents the contact area between the blank and the die, and the area under friction
