| 摘要 |
PROBLEM TO BE SOLVED: To provide a wheel supporting rolling bearing unit capable of sufficiently achieving miniaturization and weight reduction while suppressing an amount of cost, and to provide a method for manufacturing the same.SOLUTION: A hub body 10 is made of a steel containing 0.5 mass% or more of C. A high hardness martensite layer 18 with a hardness of 600-800 Hv is provided in a range from a part adjacent to a side of an axial inner side surface of a rotation side flange 7 to a part close to an inner side surface proximal end of the rotation side flange 7 in an outer peripheral surface of the hub body 10. A low hardness martensite layer 19 with a hardness of 200-400 Hv is provided in a peripheral part of the high hardness martensite layer 18 on the axial inner side surface of the rotation side flange 7. The rest part of the hub body 10 is made of a ferrite pearlite layer 20 with a hardness of 150-300 Hv. The high hardness martensite layer 18 is prevented from generation of damages such as cracks and the like. |
