| 摘要 |
PURPOSE:To reduce the deformation after grinding due to a difference in residual stress by forming at least one of an inner ring, outer ring and rolling element from alloy steel for rolling parts and cementing and hardening the alloy steel so that a difference in hardness between a surface portion and a core portion may be within + or -HR C5. CONSTITUTION:At least one of an inner ring, outer ring and rolling element is formed from alloy steel for rolling parts containing at least two elements of 0.2-1.7 Mn, 0.2-1.2 Si, 0.2-1.7 Cr, 0.1-0.3 Mo and 0.1-1.0 Ni; 0.4-0.7 C (% by weight) and Fe as balance. The alloy steel is cemented and hardened so that a cemented quantity at a surface portion be 0.35-0.6 %; a carbon quantity in solid solution at the surface portion be 0.75-1.1 %; the hardness of a core portion be HR C57-64; and a difference in hardness between the surface portion and the core portion be within + or -HR C5. Thus, a difference in residual stress between the surface portion and the core portion may be reduced, and the deformation after grinding is accordingly reduced. Accordingly, a high roundness can be obtained. |
