APPARATUS FOR CASTING AND THERMALLY CURING PLASTIC SHEETS

• US 3,579,738 A
• Filed: 11/08/1969
• Issued: 05/25/1971
• Est. Priority Date: 11/08/1969
• Status: Expired due to Term

• Current Assignee: PT Operating Company Incorporated
• Original Assignee: John O. Beattie
• Inventors: Beattie, John O.
• Application Number:
  US04/874,702
• Time in Patent Office: 563 Days
• US Class Current: 425/86
• CPC Class Codes: B29C 39/006 Monomers or prepolymers by reaction injection moulding B29C67/246
• CPC Class Codes: Y10S 425/20 Molding plants

Abstract

An apparatus for casting a plurality of plastic sheets is disclosed. It is comprised of an elevated support track having one or more temperature control cells suspended from it, the cells being enclosed chambers with inlet and outlet ports for the passage of U-shape fluid and at least one sidewall which is suitable as a mold surface of a plastic casting zone. A second mold surface is independently suspended from the elevated support track and is positioned in facing relationship with the first surface, a resilient sealing gasket between the two mold surfaces serving as an edge enclosure for a casting zone. A port in the gasket is provided for feeding casting fluid such as methyl methacrylate. Casting is carried out by applying a pressure to the exterior of the two mold surfaces thereby sealing them against the gasket, filling the casting zone, and effecting polymerization and cure by passing heated water through the temperature control cell. A liquid plastic feed system is mounted on the frame above the casting zones and includes a plurality of charge vessels connected to a common vacuum producing source and to a common source of liquid plastic, and manifolded to one another at their lower ends to equalize the plastic charge in each vessel. Each vessel is connected via tube to one of the casting zones.

Claims

2. The apparatus of claim 1 wherein the outer periphery of one of said mold surfaces includes a gasket holder, said holder including means for supporting said gasket in the desired position between mold surfaces.

3. The apparatus of claim 1 wherein said second mold surface is a sidewall of a second temperature control cell suspended from said elevated track, the casting zone thus having temperature control surfaces at both sides.

4. The apparatus of claim 1 wherein said second mold surface is one side of a first mold member suspended from said elevated support track.

5. The apparatus of claim 1 wherein a plurality of mold members form a plurality of casting zones in association with a temperature control cell, said temperature control cell and mold members being independently mounted on antifriction bearings positioned in said elevated track.

6. The apparatus of claim 1 wherein said resilient gasket is supported on a gasket frame independently suspended from said elevated support track.

7. An apparatus for casting a plurality of flat sheets of plastic comprising:

an elevated frame;

a track attached thereto;

a plurality of casting zones and temperature control cells suspended from and movable on said track, said casting zones including two vertically oriented, parallel glass surfaces in confronting relationship with a sealing gasket positioned between them as edge closure, said temperature control cells comprising vertically oriented, enclosed chambers having inlet and outlet ports for passage of heat transfer fluid anD at least one flat glass surface, there being at most two cells forming each casting zone and there being at most two cells forming each casting zone and there being at least one cell adjacent to a series of three casting zones;

a liquid plastic feed system mounted on said frame above said casting zones, said feed system comprising a plurality of charge vessels each connected to a common vacuum producing means and to a common source of liquid plastic, and manifolded to one another at their lower ends to equalize the plastic charges therein, each of said vessels being connected via tube to one of said casting zones through a port in the sealing gasket thereof; and

press means at the exterior surfaces of the endmost elements of said plurality of casting zones and temperature control cells to tightly seal said casting zones.

8. The apparatus of claim 7 wherein said casting zones and temperature control cells are rectangular in shape and are suspended from said elevated track with the top edge at an angle to the horizontal, the uppermost corner of saId casting zones providing an escape opening for gases trapped therein during filling, the lower corner providing a site for accumulations of inclusions in the plastic feed and the elevation of the outlet from said temperature control cell being placed at a height above said cell so that the hydrostatic pressure therein compensates the static pressure in an adjacent casting zone.