Roller bearings, such as cylindrical roller bearings and needle roller bearings, include a plurality of rollers rolling between an outer raceway and an inner raceway and a cage for retaining these rollers at regular intervals in the circumferential direction. In manufacture of a cage which is used in a roller-and-cage assembly and holds rollers in pockets individually, forcible removal of a molding die from the pockets causes burrs to occur and therefore cage deformation and some other defects may take place. To solve the problem, the applicant of this application has already proposed a technique described in Japanese Unexamined Patent Publication No. 2000-145790 (PTL 1).
The technique in PTL 1 relates to a needle roller-and-cage assembly, and the cage thereof has roller retaining elongated projections formed on wall surfaces of pillars of the cage so as to extend in the axial direction, the wall surfaces facing pockets. The elongated projections are arranged on both the radially outer and inner sides of the cage to prevent the rollers from dropping out. Among these elongated projections, radially outer retaining elongated projections arranged on the outer side of the cage have ends rounded into an arc shape in cross section, and the radius of the arc-shaped ends is set to be 0.5 times greater than the height of the radially outer retaining elongated projections, but 1.5 times shorter than the height. In addition, limiting the angle range of an inner inclined surface of the radially outer retaining elongated projections within 15° to 25° can contribute to both easy forcible removal and roller dropout prevention effect. Furthermore, in assembly operation of the roller-and-cage assembly, the rollers can be easily inserted into the pockets from the radially outside of the cage.