The stress reflects the stress on the blank of spur bevel gear and is the internal force per unit area.
Figure 1, figure 2 and figure 3 respectively show the stress distribution at the end of the first, second and third stages of the selected scheme.
Because the spur bevel gear is formed by closed cold die forging, a large area presents a high stress state during the whole deformation process, especially at the punch fillet and the tooth root fillet.
During the cold precision forging of spur bevel gears, the upper and lower surfaces of the workpiece are in contact with the upper and lower punch. In the upsetting process, the workpiece first contacts with the tooth die of the small end tooth root, then fills the small end tooth top, and finally the filling part is the large end tooth top. Due to the closed die forging process, the whole gear is fully formed, the metal filling is smooth, and there is no corner collapse defect. The fillet of the tooth root is smooth without folding.