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US 4,741,689 AGranted
Injection mold for an optical disk
AssigneeDaicel Chemical Industries, Ltd.
InventorsYoshio Onizawa, Yasushi Hiramatsu
Life of this patent
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Abstract
An injection mold for injection molding a plastic substrate for high-density information recording medium. An annular sliding member is axially slidably supported in the circumference of a disk-shaped cavity of a mold half. The annular sliding member is biased toward the surface of a disk-shaped cavity provided in another mold half so as to form the molding cavity and maintain contact with said surface during molding of said plastic substrate.
Claims3
An injection mold for injection molding a plastic substrate for a high-density information recording medium, comprising:
- (a) first and second half molds each having a disk-shaped cavity, said cavity of said first half mold facing said cavity of said second half mold, said half molds being movable relative to each other so as to form a disk-shaped molding cavity therebetween;
- (b) a means for injecting molten plastic into said disk-shaped molding cavity;
- (c) an annular sliding member axially slidably supported around the outer circumference of said disk-shaped cavity of said first half mold;
- (d) biasing means in said first half mold for biasing said annular sliding member toward the disk-shaped cavity surface of said second half mold;
- and
- (e) an annular outer ring and a stamper attached to said second half mold, said annular outer ring and said stamper maintaining a constant clearance with a portion of said annular sliding member to provide a gas vent when said molding cavity is formed.
3 more elements
Dependencies are inferred from the claim text.