Tapered roller bearing

A tapered roller bearing' comprising:

• an outer ring including an outer-ring raceway surface around an inner circumferential surface;
• an inner ring arranged inside relative to the outer ring, the inner ring including an inner-ring raceway surface around an outer circumferential surface and a larger flange surface arranged on a larger diameter side relative to the inner-ring raceway surface;
• a plurality of tapered rollers disposed between the outer-ring raceway surface and the inner-ring raceway surface, the tapered roller including a rolling surface in contact with the outer-ring raceway surface and the inner-ring raceway surface and a larger end face in contact with the larger flange surface;
• and
• a cage including a plurality of pockets arranged at a prescribed interval in a circumferential direction, the cage accommodating and holding the plurality of tapered rollers in respective ones of the plurality of the pockets,
• the cage including a smaller annular portion continuous on a smaller diameter side of the plurality of tapered rollers, a larger annular portion continuous on a larger diameter side of the plurality of tapered rollers, and a plurality of posts that couple the smaller annular portion and the larger annular portion to each other, the smaller annular portion, the larger annular portion, and the plurality of posts serving as partitions among the plurality of pockets,
• the larger annular portion being provided with an oil retaining hole that faces the pocket and holds lubricating oil,
• at least any one of the outer ring, the inner ring, and the plurality of tapered rollers including a nitrogen enriched layer formed on a surface layer of the outer-ring raceway surface, the inner-ring raceway surface, or the rolling surface,
• a value of a ratio R/RBASE being not smaller than 0.75 and not greater than 0.87, where R represents a set radius of curvature of the larger end face of the tapered roller and RBASE represents a distance from an apex of a cone angle of the tapered roller to the larger flange surface of the inner ring,
• a ratio Rprocess/R being not lower than 0.5, where Rprocess represents an actual radius of curvature after grinding of the larger end face of the tapered roller and R represents the set radius of curvature.