| 摘要 |
PURPOSE: To make it possible to erect a shaft having a sufficient height while enhancing productivity by specifying the diameter of an extrusion punch, the length of the straight part of a hole for forming and the volume pressed by this extruction punch. CONSTITUTION: The front end face 4a of the extrusion punch 4 is formed flat and the corner part at its peripheral edge is subjected to line chamfering to about 0.1 radius. The diameter ϕ1 of the extrusion punch 4 is so set as to be the diameter of 1.5 to 2.5 times the diameter ϕ2 of a projecting shaft 3 to be formed. The stroke S of the extrusion punch 4 to press a flat plate member 2 is so set that the volumetric part to be pressed of the flat plate member 2 attains 1.5 to 4.0 times the volume of the projecting shaft 3. On the other hand, the hole 5 for forming to be bored at a die 6 consists of the straight part 5a formed on the extrusion punch 4 side and a tapered part 5b formed to diverge therefrom. The length L1 of the straight part 5a is set longer than half the height of the projecting shaft 3 to be implanted and shorter than the height of the projecting shaft 3. |
