| 摘要 |
PROBLEM TO BE SOLVED: To provide a retainer for a needle roller bearing and a needle bearing with improved strength of a root of a pole of the retainer especially and excellent durability. SOLUTION: A position P in which a roller 11 is brought into contact with the pole 12b is on a side near an axis of the retainer 12 away from the middle of a circumferential side surface 12d of the pole 12b. Namely, when the position P on which the roller 11 abuts is projected parallel to the axis of the retainer 12 (namely, an annular part 12a) toward a curved surface 12e, a curvature radius R1 of a radial innermost part of the curved surface 12e, which is away from a projected point P' by a distance L1 and is nearer to the projected position P', is made larger than a curvature radius R2 of a radial outermost part of the curved surface 12e, which is away from the projected point P' by a distance L2 (>L1) and is farther from the projected position P'. Since the most fragile part in the curved surface 12e which is the root of the pole 12b is the part having the curvature radius R2 where a stress concentration is most apt to occur, the stress in the part is suppressed by separating the part from the position P on which the roller 11 abuts, so that fatigue strength can be improved as the whole retainer. COPYRIGHT: (C)2004,JPO&NCIPI
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