| 摘要 |
PURPOSE:To uniform inequality of projection of plural dowels formed on the end face of a material without causing under fill at the tip, and prevent wear of the die by connecting the bottom of a hole for dowel forming on the bottom of a lower die with an escape hole having diameter smaller than that of above- mentioned hole concentrically through a chamfered part. CONSTITUTION:The large diameter part 113 of the lower die 100 of a dowel forming forging die has larger axial length than a material 107a and inner diameter a little larger than the diameter of the material. The bottom of a recessed hole 105 for forming dowel is connected to an escape hole 111 having smaller diameter than the hole 105 through a chamfered part and further connected to an air vent 112 in the lower part. The hole 111 is formed concentrically with the hole 105. Accordingly, the chamfered part 130 becomes concentric with holes 111, 105, and the hole 112 is also formed concentrically with the hole 105. When the material 107a is inserted into the large diameter part 113 and a punch 104 is advanced, flow of excess material that flows in the flow cavity induces flow of the material and the material flows into the hole 105 without strain. As forming is performed in cold state wear of periphery 106 of the opening of the hole 105 is not accelerated by influence of heat. |
