Wheel-support rolling bearing unit and method of manufacturing the same

A method for manufacturing a wheel-support rolling bearing unit comprising:

• an outer ring having first and second outer raceways formed on its inner peripheral surface;
• a 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 stepped part and a cylindrical portion disposed at the other end of said hub, a step surface being defined on said hub by said stepped part;
• 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;
• said method comprising:
• fitting said inner ring to said stepped part of said hub by interference fitting while bringing an end surface of said inner ring into contact with the step surface of said hub, to thereby apply a pre-load to said rolling elements;
• forming a stepped part in the cylindrical portion;
• and forming a caulking portion by plastically deforming said cylindrical portion, wherein said cylindrical portion is expanded against the inner ring and said caulking portion is protruded beyond at least said inner ring thus fit to said hub.