| 摘要 |
PROBLEM TO BE SOLVED: To provide a wheel bearing device improving strength, fatigue strength, and wear resistance of a serration or a spline of an inner diameter face to be coupled with a constant velocity joint of a hub, and suppressing deterioration of productivity due to increase of processes. SOLUTION: An inward member 1 of the wheel bearing device having plural rows of rolling elements 3 comprises an inner ring 15 and the hub 14 having a wheel attachment flange 17. The hub has a through-hole 21 for inserting a stem part 42a of an outer ring of the constant velocity joint 41 in a center part, and it has the serration or the spline in the inner diameter face of the through-hole. The hub is produced by carrying out hot forging of steel, and a matrix is a normal structure. A formed portion of the serration or the spline in the inner diameter face of the through-hole of the hub is a portion 30 of a non-normal structure. The non-normal structure is any one of a fine ferrite-pearlite structure, an upper bainite structure, a lower bainite structure, or a tempered martensite structure, or a mixed structure of at least two types of the structures. COPYRIGHT: (C)2007,JPO&INPIT |
