| 摘要 |
PROBLEM TO BE SOLVED: To provide a crown shaped retainer having an excellent high temperature rigidity while securing releasability and assemblability of a ball in injection molding. SOLUTION: In a crown shaped retainer of a ball bearing which is molded by a resin material and which freely rollably retains a plurality of balls in a plurality of pockets, an opening diameter kD of an opening for inserting a ball of the pocket is set to be 89±1% of the diameter D of the ball when the flexural modulus of the resin material is less than 4,000MPa. When the flexural modulus of the resin material is≥4,000MPa and <8,000MPa, the opening diameter kD of the opening for inserting a ball of the pocket is set to be 91.5±1% of the diameter D of the ball. When the flexural modulus of the resin material is 8,000MPa or more, the opening diameter kD of the opening for inserting a ball of the pocket is set to be 94±1% of the diameter D of the ball. When the tensile breaking elongation in a tensile test piece of the resin material is 2.5% or less, the opening diameter kD of the opening for inserting a ball of the pocket is set to be 94±1% of the diameter D of the ball. COPYRIGHT: (C)2004,JPO
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