| 摘要 |
PROBLEM TO BE SOLVED: To realize structure having light weight, a low cost, and moreover excellent durability. SOLUTION: A cylindrical part 18b formed on the end part of a hub 2c is caulkedly expanded outward in a diameter direction to fix an inner wheel 3, in the condition wherein the wheel 3 is externally fitted to a step part 8 formed on the end part of the hub 2c. A different level part 27 is formed on the outer peripheral surface of the base end part of the part 18b, to be adopted as a starting point. A part shown by an oblique grating is hardened by heat treating, to prevent the deformation and abrasion of the part. The part 27 is not hardened to prevent damage such as a crack in a portion corresponding to the part 27 at the time of caulking work. |
