The magnitude of equivalent effect variation reflects the deformation degree of metal. As shown in the figure, the typical equivalent effect variation distribution during the forming of three kinds of spur bevel gear blanks is selected. It can be seen from the figure that the maximum deformation degree is concentrated in the metal at both ends of the spur bevel gear blank, the deformation in the middle part is very small or even no deformation, and the equivalent strain areas of the three kinds of spur bevel gear blanks are basically the same in the process of rotary forging.
Therefore, for drum shaped blank, although the deformation of the middle part is small, its middle shape is more prominent and there are more materials, which is conducive to the forming of the middle part of spur bevel gear. On the contrary, conical and cylindrical are not conducive to the forming of the middle part of spur bevel gear.