| 摘要 |
PROBLEM TO BE SOLVED: To improve the dimensional accuracy of a core for ejecting a molded product at the time of advance and retreat. SOLUTION: A cavity 15 for an optical part is formed between a first mold 20, to which a sprue 11 for allowing a molten resin to flow in is formed, and the second mold 30 opposed to the first mold 20 when the first and second molds 20 and 30 are abutted to be clamped and a core 33 having an optical part transfer surface 33c is allowed to face at least to the cavity 15 on the surface side of the second mold 30. When the core 33 is attached to the second mold 30 so as to be made possible to advance and retreat within the hole 30d bored in the second mold 30 with respect to the cavity 15, a plurality of ball bearings 35 supported by a cylindrical retainer 34 are interposed between the inside of the hole 30d bored in the second mold 30 and the shaft part 33a of the core 33 while pre-load is applied within elastic displacement and the shaft part 33a of the core 33 is made possible to advance and retreat with respect to the cavity 15 along a plurality of the ball bearings 35. COPYRIGHT: (C)2004,JPO
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