| 摘要 |
PROBLEM TO BE SOLVED: To provide a male screw member (bolt) which hardly results in insufficient assembling with a female member (nut) in fastening work. SOLUTION: In a bolt 1, a thread ridge 5 on the leading side 4 is started at a stepped part 25 rising so as to intersect the circumferential direction of the ridge 5, and the thread height of the ridge 5 is set at a range of 60 to 100% the thread height of a thread ridge (complete ridge) 6 on the following side. The bolt 1 like this hardly results in insufficient assembly due to mutual catching among fellow thread ridges, which is used to occur when a bolt 1 is assembled with a nut. The bolt 1 is manufactured as follows. As for the base material for the bolt 1, an end part in the axial direction of a male-screw- formed position of the base material, which will become an end part on the leading side at the completion of the bolt 1, is formed into a shape notching a portion for almost one pitch of the screw forming part, mating with the lead angle. Then, the base material having the shape notching one portion is rolled for forming the thread.
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