| 摘要 |
An object of the present invention is to provide a method of manufacturing a rotational shaft having a worm, wherein a worm portion has a small bending amount. According to the method of the invention, a worm portion is formed at a worm forming portion by a rolling process with rolling dies, and a small diameter portion is formed at least at one axial end of the worm forming portion, wherein a diameter of the small diameter portion is smaller than a diameter of a bottom of a worm tooth to be formed at the worm forming portion, so that surplus material portion of the worm forming portion can flow toward the small diameter portion.
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