| 摘要 |
PURPOSE: A piercing method for forming a hardened layer on materials and a punch using the same are provided to improve durability by securing strength in a stress concentration part, and to secure stable workability without crumbling. CONSTITUTION: A piercing method for forming a hardened layer on materials is as follows. An edge ring(120) is formed on the outer surface of a punch(100). Punching holes are formed in materials(500) by punching the materials using a fine blanking method. The punching holes is penetrated through the edge ring to be finished. A hardened layer is formed in the punching holes. |
