It can be seen from Fig. 1 that the stress distribution near the bevel of the extrusion die is also close to the bevel of the extrusion process. By observing the B ~ C diagram, it can be found that in the process of forming the shaft, the stress value is mainly distributed in the severe deformation area. Before entering or after leaving the area, the equivalent stress value is close to zero, the maximum value is distributed near the horizontal position of the fillet on the working face, and extends from this position along the axis to both ends, and the equivalent stress value gradually decreases. In a small area of the inner layer of the blank at the horizontal position of the fillet under the working zone, the equivalent stress has a local minimum, while the equivalent stress around it increases. According to Fig. C, at the initial stage of extruding the 38.5mm shaft, the equivalent stress in the central and local area of the unformed part is small due to the initial action of the punch. The maximum equivalent stress during hot extrusion is distributed between 120 ~ 170mp.
Comparative analysis of Figure 2 shows that the distribution of equivalent stress during cold extrusion is basically similar to that of hot extrusion. The equivalent stress value is mainly distributed in the severe deformation area. Before entering and after leaving the area, the equivalent stress value is close to zero. In the inner layer of the blank at the horizontal position of the fillet under the working zone, there is a local area with small equivalent stress value, while the surrounding equivalent stress value is slightly larger. Due to the large deformation resistance of metal in cold state, the maximum equivalent stress value is distributed between 900 ~ 920mp.
