| 摘要 |
PROBLEM TO BE SOLVED: To provide a wheel bearing device and a process for manufacture of its outer member in which a circularity of an outer running surface of the outer member is kept constant even if a moment load is applied at the time of turning in a running state of a vehicle and a long life can be assured.SOLUTION: This invention relates to a wheel bearing device for second to fourth generation structures having an outer member 2 in which a vehicle body fixing flange 7 fixed to a knuckle is integrally arranged at its outer circumference and outer running surfaces 2a in plural rows are integrally formed at its inner circumference. A shape of each of the outer running surfaces 2a in plural rows of the outer member 2 is formed into an elliptical shape with a long diameter (a) in a horizontal direction and a short diameter (b) in a vertical direction, a relation between the long diameter (a) and the short diameter (b) is set to become a range of 0<2a-2b≤15 μm. With this arrangement as above, when a turning load is applied, it can be deformed into a proper circularity shape and a superior running state can be maintained, thereby providing a wheel bearing device with a long life. |
