| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a wheel bearing device having high-degree anti-cracking strength and size stability and being excellent in a rolling fatigue durability. <P>SOLUTION: The wheel bearing device 10 consists of an external member 4 provided on an inner circumference with a double row comprising rolling surfaces 4a and 4b, an internal member 1 having rolling surfaces 7a and 7b opposed to a double row comprising the rolling surfaces 4a and 4b, respectively, and a plurality of tapered rollers 5a and 5b situated between the external member 4 and the internal member 1. A wheel mounting flange 8 is situated at one of the external member 4 and the internal member 1. At least one member of the inner rings 3a, 3b, and the tapered rollers 5a and 5b has a nitrogen enriched layer. The particle size number of the old austenite crystal grain of the member is numbered in a range exceeding No.10. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
