| 摘要 |
PROBLEM TO BE SOLVED: To provide a wheel bearing device, which improves the strength of a hub in the neighborhood of an inner race contact surface of the hub to be brought into contact with the end face of the inner race on an outboard side, reduces the wear of that portion, and suppresses the drop of the productivity. SOLUTION: The hub 14 comprises a stem portion 14a for fitting the inner race 15 of the bearing 1 thereon, and a flange 17 for mounting the wheel thereon. The end face of the inner race 15 on the outboard side is brought into contact with the inner race contact surface 40 elongating from an end portion of the external surface of the stem portion on the wheel mounting flange 17 side of the hub 14. The hub 14 is made of a steel material by hot forging, and has a standard structure in its base material. A region from at least the neighborhood of the inner race contact surface 40 in the external surface of the stem portion 14a of the hub 14 to the inner race contact surface 40 has a non-standard structure portion 30. The non-standard structure is any one of a fine ferrite-pearite structure, an upper bainite structure, a lower bainite structure, and a tempered martensite structure, or a mixed structure of at least two or more kinds of these structures. COPYRIGHT: (C)2007,JPO&INPIT |
