An oil film bearing for supporting a roll neck in a rolling mill, suitable in particular for transmitting high bearing forces when the bearing partners are slightly and slowly moved with respect to each other, has a bearing surface into which are incorporated rods made of a friction-reducing material (e.g., low friction compounds), which extend in a substantially perpendicular direction to the bearing surface. The rods are deformed during heat processing to define a bearing surface. The bearing partner, such as a roll sleeve, rests on the free face of the deformed rods.

A cage includes: an annular body having pocket holes for receiving balls; and a resin portion formed through injection molding of a resin containing a solid lubricant with the body being set as an insert component. The resin portion includes: first parts formed along inner peripheral surfaces of the pocket holes of the body to form pocket surfaces to be held in sliding contact respectively with the balls; and a second part formed along an outer peripheral surface (or inner peripheral surface) of the body to form a guide surface to be held in sliding contact with an outer ring (or inner ring). The first parts and the second part are formed integrally with each other. Weld lines of the resin portion are formed at positions of avoiding exposure of the weld lines at both end portions of the pocket surfaces in a cage circumferential direction.

Gates (G) are uniformly arranged in a circumferential direction only in a large annular section (2). The gates (G) are equal in number to a number of pockets (4). The gates (G) are arranged only at sites positioned on planes (Pa) passing circumferential centers of the respective pockets (4). Weld lines (W) are thus formed only in the vicinity of the planes (Pa) of a small annular section (1).

A cage made of synthetic resin includes an annular body, a plurality of prongs, a plurality of gate marks formed away from each other in a circumferential direction, a weld formed between the gate marks adjacent to each other in the circumferential direction, and a plurality of pocket forming portions that is each disposed between the gate marks and in which pockets are formed. Each of the pocket forming portions has a through hole formed through a bottom of the pocket in an axial direction. The weld is formed between the gate marks only in a region on one circumferential side of the through hole or only in a region on the other circumferential side of the through hole.