| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method by which a stepped columnar member to be used as a hub body of a rolling bearing unit for wheel support for instance can be manufactured, while occurrence of a chevron crack is prevented and increase in weight of the member is suppressed.SOLUTION: Material 28 formed by internally fitting core material 26 made of a light alloy such as an aluminum alloy in bottomed cylindrical surface layer material 27 by tight fit is utilized. Then, by inserting the material 28 into a cavity of a die and forming cold forging of pushing the material 28 into the cavity by a pressing punch, the stepped columnar member is formed.SELECTED DRAWING: Figure 1 |
