| 摘要 |
PROBLEM TO BE SOLVED: To provide thread rolling dies, with which a male screw, etc., can be thread rolled on the outer peripheral surface of a blank to be thread rolled, provided with a groove, notching, etc., along the axial direction of the blank to be thread rolled. SOLUTION: A stepped part 21b in a work 20 is interposed with the starting edge side of biting surface 3a of a liner member 3 and the starting edge side of flat surface 5a of a liner member 5 according to the shifting of the one side of thread rolling flat dies 1. When the shifting of the thread rolling flat dies 1 is continued, the stepped part 21b is rolled between the biting surface 3a and the flat surface 5a, and the part 21a to be thread rolled in the work 20 is rotated between inclining parts 2b and 2b in the dies 2 and 2 with this rolling. According to this rotation, the outer peripheral surface of the part 21a to be thread rolled, is gradually plastic-deformed. Thereafter, the flat surfaces 3b and 5a in the liner members 3 and 5 reach the work 20, and the work is thread rolled while interposing the stepped part 21b with the flat surface 3b and 5a and the male screw part 31 is finished on the outer peripheral surface of the part 21a to be thread rolled to manufacture screw parts 30 with the groove.
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