摘要 |
In a retaining piece interposed between the adjacent rolling balls, a concave surface of each of both side surfaces of the retaining piece where it contacts with the spherical surfaces of the balls is configured to partly contact with the spherical surface of the ball. The concave surface includes a linear contact portion to be in contact with the ball and an approximate curved surface having the radius of curvature approximate to that of the ball, which is located on the inner side of the linear contact portion. In addition, recesses which are joined to the gate portion and the ejector pin in a molding process are formed in the concave surfaces. A recess is formed at the joining portion or near a parting line. Fins formed in the molding process are capable to be put into the recess.
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