Patent ID: 6772615
Filing Date: 2004-08-10
Classification: B21J,B21K,F16C,Y10T

Abstract:
A method of manufacturing a hub unit for supporting a wheel, the hub unit including: a hub body having one end face on which a flange for supporting a wheel is formed; a first inner ring raceway formed on an outer circumferential face of an intermediate portion of the hub body directly or via a first inner ring provided differently from the hub body; a step portion formed in the other end portion of the hub body, and having an outer diameter being smaller than an outer diameter of a portion in which the first inner ring raceway is formed; a second inner ring externally engaged with the step portion, a second inner ring raceway being formed on an outer circumferential face of the second inner ring; an outer ring having an inner circumferential face on which a first outer ring raceway opposing to the first inner ring raceway and a second outer ring raceway opposing to the second inner ring raceway are formed; a plurality of rolling elements provided between the first inner ring raceway and the first outer ring raceway and between the second inner ring raceway and the second outer ring raceway; and a calking portion fixing the second inner ring to the hub body while pressing the second inner ring against a step face of the step portion, the method of manufacturing the hub unit comprising the steps of:preparing a cylindrical portion formed in the other end portion of the hub body, the cylindrical portion being formed to protrude from the second inner ring externally engaged with the step portion; and applying a force in the axial direction and a force in the radial outward direction to the cylindrical portion by a die, while pressing the die against a forward end face of the cylindrical portion, so as to plastically deform a forward end portion of the cylindrical portion outwardly in the radial direction while compressing the cylindrical portion in the axial direction, to thereby form the calking portion, wherein an average compressive stress is continuously generated in an inner circumferential portion of the cylindrical portion during the period of working the calking portion.