| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method capable of: manufacturing a stepped columnar member to be used as a hub body of a wheel supporting roller bearing unit, for example, lightly while preventing the occurrence of a drop; and retaining the durability of a die.SOLUTION: Onto the upper face of a preliminary intermediate stock 27, there is pushed a coarsely shaping punch having an external diameter smaller than that of an upper end part of the preliminary intermediate stock 27, thereby to attain an intermediate stock 28 having a large diameter recess 29 and an outward flange part 30. A finish-molding punch having a smaller external diameter than that of the portion near the internal diameter of the large diameter recess 29 of that intermediate stock 28 is pushed into the bottom central part of that large diameter recess 29. As a result, a small-diameter recess 45 is formed in the bottom face of that large diameter recess 29, and the axial length of a small-diameter step part 12a is enlarged. |
