Method for manufacturing a bearing raceway member
At least a race ( 1 c ) of a blank (B) for forming a bearing raceway member is hardened by heating and is finished to predetermined precisions. Subsequently, the race ( 1 c ) is roller burnished for additional hardening. The blank (B) is formed from a steel for bearing manufacture and is subjected to the roller burnishing, thereby achieving a hardness of HRC65 or more at a surface of the race ( 1 c ), and a center-line average roughness Ra of 0.1 μm or less at the surface of the race ( 1 c ) and achieving a hardness of HRC60 or more at the depth of at least 0.2 mm from the surface of ( 1 c ).
1. A method for manufacturing an inner ring of a roller bearing, comprising the steps of:
working a material formed from a steel for bearing manufacture into predetermined shapes to form at least a race of the inner ring of the roller bearing in order to produce a blank for forming the inner ring;
hardening by heating at least the race of said blank;
finishing the race of said blank hardened by heating to predetermined precisions; and
roller burnishing said finished race by holding a ball in rolling contact therewith, as the ball is pressed against the race with high pressure, thereby hardening the race,
wherein a steel for bearing manufacture is used as said material, and
wherein the race is subjected to said roller burnishing, thereby achieving a hardness of HRC65 or more at a surface thereof and a center-line average roughness Ra of 0.1 μm or less at the surface thereof and achieving a hardness of HRC60 or more at a depth of at least 0.2 mm from the surface thereof.
2. A method for manufacturing according to claim 1 , wherein the race of the inner ring has a compressive residual stress of 1000 MPa or more at depth of at least 0.15 mm from the surface thereof.