| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw member which prevents turning-in from occurring in a screw bottom part in a stress concentrated portion, even when rolled by a rolling die with one part lacked in a top part of a screw thread, in screw rolling work, and which enhancing fatigue resistant characteristic, a lagged breakage resistant characteristic and the like, and also to provide a manufacturing method therefor. SOLUTION: A large-diametric shaft part 4a is formed in a female screw part and a screwed portion in a connecting rod bolt 1, a small-diametric shaft part 5a is formed in the female screw part and a nonscrewed portion, then a complete screw part 4 is formed in the large-diametric shaft part 4a, by a screw rolling work, an incomplete screw part 5 is formed in the small-diametric shaft part 5a. The turned-in 55 is thereby prevented from occurring in the screw bottom part in the stress concentrated incomplete screw part 5, even when rolled by the rolling die with the one part lacked in the top part of the screw thread, in the screw rolling work. The fatigue resistant characteristic, the lagged breakage resistant characteristic and the like in the connecting rod bolt 1 of the present invention, are enhanced by this manner compared with those in a conventional connecting rod bolt. COPYRIGHT: (C)2008,JPO&INPIT |
