| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a bolt with a locking projection capable of being manufactured with cold forging and extremely superior in strength, and to provide its manufacturing method and device. <P>SOLUTION: The manufacturing method mainly comprises semi-close upsetting work with cold forging. In primary work, a thick portion is formed on one side face of the upper part of a blank P to provide for the locking projection 3. In second work, a thick portion is formed to provide for a bolt head 2. In third work, a molded recessed portion 4 is formed in the center at the upper end of the blank P to be recessed in a concentrically circular shape. Together with the molded recessed portion 4, the bolt head 2 is formed at the thick portion around the molded recessed portion 4. The locking projection 3 is molded together with the bolt head 2 at the same time. In fourth work, the bolt head 2 and the locking projection 3 are re-shaped. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
