Mold for producing molded discs

• US 5,297,951 A
• Filed: 05/13/1992
• Issued: 03/29/1994
• Est. Priority Date: 05/13/1992
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Meiki Seisakusho
• Original Assignee: Kabushiki Kaisha Meiki Seisakusho
• Inventors: Asai, Ikuo
• Primary Examiner(s): Bushey, Charles S.
• Application Number:
  US07/882,012
• Time in Patent Office: 685 Days
• Field of Search: 264/106, 264/107, 264/328.1, 425/556, 425/405.1, 425/437, 425/444, 425/810, 425/812
• US Class Current: 425/556
• CPC Class Codes: B29C 45/263 with mould wall parts provided with fine grooves or impressions, e.g. for record discs
• CPC Class Codes: B29C 45/43 using fluid under pressure
• CPC Class Codes: Y10S 425/81 Sound record
• CPC Class Codes: Y10S 425/812 Venting

Abstract

In a mold for producing a disc having a stationary mold half and a movable mold half, an air passageway is provided in the stationary mold half to feed air into a cavity between the mold halves approximate the center of the disc being molded. Further, two air passageways are provided in the movable mold half to feed air into the cavity between the mold halves. One of the air passageways in the movable mold half feeds air into the cavity proximate the center of the molded disc while the second air passageway feeds air into the cavity proximate the outer periphery of the disc on the side toward the stationary disc. The air fed from the second air passageway of the movable mold half flows around the outer periphery of the disc and behind the disc to assist in separating the disc from the movable mold half. Further, a vacuum passageway is provided in the movable mold half leading to the backside of a stamper, mounted to the face of the movable mold half, to prevent air from the second air passageway of the movable mold half from also flowing around the peripheral edge of the stamper and behind the stamper.

Claims

1. A mold for molding discs, comprising:

a stationary mold half having a stationary-side air hole opening into a central portion of a cavity for molding a disk;

a movable mold half having a first movable-side air hole opening toward the central portion of the cavity;

a second movable side air hole opening through said movable mold half and an outer peripheral ring toward an outer peripheral surface of a stamper fixed onto a mirror surface of the movable mold half;

an annular vacuum groove opening at an outer peripheral reverse side of said stamper; and

ejection means provided in said movable mold half for ejecting a disc molded in said cavity, wherein said annular vacuum groove opening holds said stamper in close contact with said movable mold half thereby preventing air from said second movable side air hole from flowing to a reverse side of said stamper.

4. The mold as claimed in claim 1, wherein air blown from said second movable side air hold flows around an outer periphery of the molded disc to separate the outer periphery of said molded disc from said stamper.

2. A mold for producing a molded disc, comprising:

a stationary mold half having a central opening for the injection of moldable material;

a movable mold half opposing said stationary mold half and having inserted therethrough, at a central position, a hold punch and an ejector; and

a stamper mounted to an inner face of said movable mold half, wherein said stationary mold half has a first air passageway for blowing air into a mold cavity near a center of the molded disc; and

said movable mold half has a second air passageway for blowing air from a plurality of openings into a mold cavity near a center of the molded disc on a side opposite to the air blown from said first air passageway, a third air passageway for blowing air near an outer periphery of the molded disc, and a vacuum passageway for holding an outer periphery of said stamper to said inner face of said movable mold half such that blown air from said third air passageway cannot enter between said stamper and said inner face of said movable mold half.

3. The mold as claimed in claim 2, wherein said third air passageway opens toward a side of said stamper facing said stationary mold half at the outer periphery of said stamper so that air blown from said third air passageway passes between said stamper and the molded disc to separate the molded disc from said stamper.