Bearing cage and manufacturing method therefor

Abstract

The resin injection gate is disposed at the pillar part. When the bearing cage is divided into first and second regions by an imaginary line connecting the resin injection gate and a weld to be formed at a position radially facing the resin injection gate, a resin reservoir that can store therein the melted resin is formed at the pillar part in only one of the regions. A circumferential distance between the resin reservoir and the weld is smaller than a circumferential distance between the resin reservoir and the resin injection gate. A cross-sectional area of a communicating part of the resin reservoir, which is configured to communicate with the pillar part, is equal to or less than a quarter of a cross-sectional area of the resin injection gate.

1 . A bearing cage comprising:
 a substantially circular ring-shaped base part;   a plurality and an odd or even number of pillar parts spaced with predetermined intervals in a circumferential direction and protruding axially from one axial end side surface of the base part; and   pockets whose number is equal to a number of the pillars formed by facing surfaces of a pair of the pillar parts adjacent to each other and one axial end side surface of the base part;   wherein a first cutting mark is disposed at the pillar part,   wherein a weld line is formed at a position radially facing the first cutting mark,   wherein when the bearing cage is divided into first and second regions by an imaginary line connecting the first cutting mark and the weld line, a second cutting mark is disposed at the pillar part in only one of the regions,   wherein a circumferential distance between the second cutting mark and the weld line is smaller than a circumferential distance between the second cutting mark and the first cutting mark, and   wherein a cross-sectional area of the second cutting mark is equal to or less than a quarter of a cross-sectional area of the first cutting mark.   
     
     
         2 . The bearing cage according to  claim 1 ,
 wherein a plurality and an odd number of the pillar parts is provided, and   wherein the second cutting mark is provided at a first pillar part in the circumferential direction from a position at which the weld line is formed.   
     
     
         3 . The bearing cage according to  claim 1 ,
 wherein a plurality and an even number of the pillar parts is provided, and   wherein the first cutting mark is arranged at a position deviating from a circumferentially central portion of the pillar part.   
     
     
         4 . The bearing cage according to  claim 3 ,
 wherein when a region including the pillar part, in which a bottom of the pocket does not exist between the pillar part and the weld line, of a pair of the pillar parts adjacent to the weld line in the circumferential direction is set as the first region, the second cutting mark is provided at the pillar part in only the first region.   
     
     
         5 . The bearing cage according to  claim 1 ,
 wherein the second cutting mark is provided at the pillar part adjacent to the weld line in the circumferential direction.   
     
     
         6 . The bearing cage according to  claim 3 ,
 wherein the second cutting mark is provided at the pillar part adjacent to the weld line in the circumferential direction.   
     
     
         7 . The bearing cage according to  claim 4 ,
 wherein the second cutting mark is provided at the pillar part adjacent to the weld line in the circumferential direction.