Ball roller bearings are rolling contact bearings with special rolling elements designed as ball rollers, which, starting from a basic ball shape, each have two side faces, which are formed as flats on said basic ball shape, which are arranged parallel to one another and between which the running surfaces of the ball rollers are in each case arranged. Ball roller bearings of this kind are widely known in many different versions in the form of single-row, two-row, three-row or even four-row radial or angular contact ball roller bearings and, owing to the special shape of the rolling elements, they also require special cage designs in order, on the one hand, to limit a maximum angular position of the ball rollers relative to the longitudinal axis of the bearing and, on the other hand, to avoid wobbling of the ball rollers transversely to the direction of revolution thereof.
A single-row ball roller bearing of the type in question is already known, for example, from the German patent application with the official file reference 10 2008 016 977.3, which had not yet been published on the filing date of the present patent application, and essentially comprises an outer bearing ring, an inner bearing ring and a multiplicity of ball rollers arranged between said bearing rings, which ball rollers roll on the running surfaces thereof in two groove-shaped races machined into the inner side of the outer bearing ring and into the outer side of the inner bearing ring and are held at uniform distances from one another in the circumferential direction by a bearing cage. This bearing cage is expediently designed as a window cage having two lateral cage flanges, which are bent around two encircling flanging edges toward the inner bearing ring and are intended to guide the ball rollers axially, said flanging edges being interconnected by a plurality of pocket webs. The individual cage pockets of the bearing cage, which are separated from one another by the pocket webs, each have a cross-hole shape, which is formed from a cross-sectional contour of a ball roller, said contour being arranged longitudinally with respect to the circumferential direction, and from a free contour, which is integrated therein, is arranged transversely to the circumferential direction and is intended for the insertion of a ball roller into the bearing cage. The cross-sectional contour of the cage pockets, which is arranged longitudinally with respect to the circumferential direction, corresponds to the shape of a section plane arranged above the transverse axis of a ball roller, while the free contour of the cage pockets, which is arranged transversely to the circumferential direction, has the shape of a section plane arranged directly on the transverse axis of a ball roller. To produce a bearing cage of this kind, use is generally made of a sheet-metal strip, which is finished by profiling the cage flanges, punching the cage pockets, cutting to length to give the dimension of the circumference, rolling into a ring and welding the ends of the ring.
It has been found in practice, however, that the production of the bearing cage in the form described is subject to special technical problems, and furthermore the bearing cage does not fully meet the specified requirements in terms of quality. This is connected especially with the cage flanges formed as a profile on the sheet-metal strip, which lead to constrictions of the material as the cage is rolled into a ring, the effect of said constrictions being that the cage flanges do not have a smooth and flat surface but a wavy surface. It has likewise proven extremely difficult to flange these cage flanges further in the direction of the side faces of the ball rollers after the filling of the ball roller bearing with the ball rollers in order to produce an axial guide for said rollers, since the flanging edges have a high stiffness and, as a result, there are further deformations in the bearing cage during the flanging of the cage flanges on the filled bearing. Moreover, the pocket webs of the bearing cage, which are of relatively wide and thus very stiff configuration at the transitions thereof to the cage flanges, owing to the round cross hole shape of the cage pockets, also contribute to said cage being more polygonal than round in the final form thereof.