Cage, rolling bearing, and method for molding cage
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.
1 . A cage made of synthetic resin and including an annular body and a plurality of prongs spaced away from each other in a circumferential direction of the annular body and protruding from the annular body to one axial side, the cage having a plurality of pockets for holding a plurality of rolling elements of a rolling bearing in a freely rollable manner, each of the pockets being formed between the prongs adjacent to each other in the circumferential direction, the cage comprising:
a plurality of gate marks formed away from each other in the 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 the pockets are formed, wherein
each of the pocket forming portions has a through hole formed through a bottom of the pocket forming portions 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 another circumferential side of the through hole, and
the weld includes:
a first weld portion extending entirely in a radial direction in an axial view; and
a second weld portion extending in the circumferential direction from a radial midpoint of the first weld portion to the through hole in the axial view.
2 . The cage according to claim 1 , further comprising a plurality of prong forming portions in which the prongs are formed, wherein one of the gate marks is formed in each of all the prong forming portions.
3 . A method for molding the cage according to claim 2 using a mold including a plurality of runners, a plurality of gates connected to the runners, and an annular cavity to which the plurality of gates is connected away from each other in the circumferential direction, wherein
in the cavity, a plurality of pocket molding spaces in which the pocket forming portions are molded and a plurality of prong molding spaces in which the prong forming portions are molded are formed alternately in the circumferential direction,
one of the gates is connected to each of all the prong molding spaces, and
when molten resin is poured into the cavity from the runners through the gates, a volume of the molten resin poured from one of the two gates adjacent to each other in the circumferential direction is made larger than a volume of the molten resin poured from the other of the two gates.
4 . The cage according to claim 1 , wherein:
a pair of annular components each including the annular body and the plurality of prongs is connected in the axial direction; and
the cage includes cage bars structured by connecting the prongs of the pair of annular components.
5 . A rolling bearing comprising an inner ring, an outer ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and the cage according to claim 1 .