A superfinishing method for a bearing roller involves installation of a pair of parallel feed drums. The feed drums have guide thread surfaces each continuing in a spiral shape on an outer periphery, and each being driven to rotate about respective center axes. The feed drums through-feed a workpiece to be formed into a bearing roller while supporting and rotating the workpiece with the guide thread surfaces opposed to each other. The superfinishing method includes using a grinder to process an outer peripheral surface of the workpiece passing between the feed drums, varying a thread bottom angle of the guide thread surface based on positions along the feed drums in an axial direction, and superfinishing straight and logarithmic portions at both ends of the straight portion of a rolling surface of the bearing roller by one through-feed of the workpiece passing between the feed drums.

A machining apparatus is of an in-feed type configured to machine an outer peripheral surface of a rotating tapered roller, and includes a rotating mechanism having a lateral pair of rollers on which the tapered roller is mounted, the rotating mechanism rotating the pair of rollers, and a grinding stone that is brought into contact with the outer peripheral surface of the tapered roller mounted on the pair of rollers. Each roller of the pair of rollers is shaped like a truncated cone. Small-diameter portions of the pair of rollers come into contact with a small-diameter portion of the tapered roller. Large-diameter portions of the pair of rollers come into contact with a large-diameter portion of the tapered roller.

A method of processing a crowned portion of a roller includes disposing first and second feed drums so as to extend parallel to each other, each of the first and second feed drums having an outer periphery formed with respective spirally extending threaded guide surfaces, the first and second feed drums being driven to rotate to transport the roller from a first location towards a second location through between the first and second feed drums, and successively processing the crowned portion of the roller, by means of a through feed processing with the use of a grinding stone. The threaded guide surface of one of the first and second feed drums is formed so that an angle of inclination of an outer peripheral surface of the roller relative to a processing surface of the grinding stone is varied in dependence on a roller passing position of the feed drum.