| 摘要 |
PROBLEM TO BE SOLVED: To provide a bearing device for a vehicle wheel capable of enhancing the strength and fatigue strength of the area around the bearing surface of a hub bolt hole formed in a flange for mounting the vehicle wheel against a high tension or repeated stresses for example when a vehicle is turning, reducing the wear of the bolt bearing surface, and suppressing a drop in the productivity owing to an increase in processes. SOLUTION: An inner member 1 and an outer member 2 are provided rotatable relatively through rollers 3 in rows. Either of these members 1 and 2 has the wheel mounting flange 17, which has the bolt hole 18 to admit insertion of a hub bolt 9. A member having this wheel mounting flange is formed through hot forging from a steel material whose parent material part is in the standard structure, while the bearing surface 18b of the bolt hole 18 formed in the side face of the flange 17 and the area around the bearing surface 18b are made a part 30 in the non-standard structure. The non-standard structure is either of a fine ferrite pearlite structure, an upper bainite structure, a lower bainite structure, and tempered martensite structure, or a hybrid structure including at least two of them. COPYRIGHT: (C)2007,JPO&INPIT |
