| 摘要 |
PROBLEM TO BE SOLVED: To prevent crack of a protruded portion.SOLUTION: In an anchor 10, when forming an insertion-through hole 44 and a protruded portion 46, a through-hole is formed by pressing a steel plate from below to form a recess and punching a recess formation part in the steel plate from above. As a result, drooped faces are formed at both axial edges on a peripheral face of the through-hole, respectively, and sheared faces are formed axially inside of each drooped face on the peripheral face of the through-hole. The whole periphery of the through-hole of the steel plate is then pushed and opened to form the insertion-through hole 44 and the protruded portion 46 in the steel plate, while the drooped faces and the sheared faces inferior in face roughness exist at both axial ends on the peripheral face of the through-hole. The crack around the through-hole of the steel plate can be prevented during pushing and opening the whole periphery of the through-hole of the steel plate even when thickness of the steel plate is thin, and the crack of the protruded portion 46 can be prevented. |
