Patent ID: 6478471
Filing Date: 2002-11-12
Classification: B21J,B21K,B23P,B60B,F16C,Y10S,Y10T

Abstract:
A wheel-support rolling bearing unit comprising:an outer ring having first and second outer raceways formed on its inner peripheral surface; a hub made of carbon steel, said hub having a flange formed on the outer peripheral surface of one end thereof, said hub having a first inner raceway which is disposed on its middle portion in an axial direction thereof and is confronted with said first outer raceway of said outer ring, said hub having a cylindrical portion which is disposed at the other end of said hub and has first and second portions, wherein an average cross sectional area of crystal particle in said second portion is less than 0.030 mm2; an inner ring provided at the other end of said hub, said inner ring having a second inner raceway which is formed on its outer peripheral surface and is confronted with said second outer raceway of said outer ring; a plurality of first rolling elements located between said first inner raceway and said first outer raceway; and a plurality of second rolling elements located between said second inner raceway and said second outer raceway; wherein a caulking portion, which is formed by plastically deforming said second portion of said cylindrical portion, is protruded beyond at least the inner ring fit to said hub, whereby said inner ring fit to said hub is firmly coupled to said hub.