US Patent 7104697 Bearing part and fabrication method therefor

In a heat treatment wherein a blank (intermediate material) formed with a lubrication hole is heated and quenched, the quenching of the blank is terminated at the point of time that a temperature at a portion corresponding to a depth from a raceway surface (surface of a bearing part) of an outer ring (the bearing part), to which depth the maximum shear stress affects, is lowered to an MS point.