| 摘要 |
PROBLEM TO BE SOLVED: To prevent a fracture of a lower punch by avoiding stress concentration at a tip of the lower punch, in a powder molding die for sintered sprocket having two or more teeth.SOLUTION: A lower punch 2 has a first configuration section 5 that configures a small tooth side edge face of large teeth of raw sprocket and a second configuration section 6 that configures small teeth, and further includes a third configuration section 7 which is provided between the first configuration section 5 and the second configuration section 6, and forms a cylindrical section with a larger diameter than that of a tip diameter of small tooth in the outer circumference of a sprocket raw material. A tapered face 8 is interposed between a configured face 6a at a small tooth bottom in the second configuration section and the third configuration section 7, which enlarges its diameter toward the top of the lower punch. |
