| 摘要 |
PURPOSE:To efficiently manufacture a hollow stepped shaft-like product at a low cost, by putting a round bar-like blank material between rotary dies respectively equipped with stepped-section forming section on the outer surfaces, with the outer peripheral surface of the blank material being pushed by the dies, and pushing boring mandrels against the central core section of the blank material. CONSTITUTION:A round bar-like blank material 3 is put between a pair of rotary dies 1 and 1, respectively equipped with stepped-section forming sections 2 and 2 of prescribed shapes on the outer surfaces, and the blank material 3 is rotated in the same direction while the blank material is pressed by the dies 1 and 1. At the same time, a pair of boring mandrels 6 and 6 which are faced to each other on the axis of the blank material 3 are pushed against the blank material from both ends while the mandrels 6 and 6 are rotated in the same direction as that of the blank material 3. Therefore, a stepped section of accurate prescribed dimensions is formed on the outer peripheral surface of the blank material 3 and a hollow section is bored by one process. Thus a hollow stepped shaft-like product is obtained. |
