초록 ▼

A mold for use in heat expanding prefoamed polystyrene beads to form a part of a predetermined shape is disclosed. The mold comprises a cavity defined by separable mold wall portions. Each mold wall portion has on its exterior a chamber into which a heating medium is introduced to heat the mold wall

A mold for use in heat expanding prefoamed polystyrene beads to form a part of a predetermined shape is disclosed. The mold comprises a cavity defined by separable mold wall portions. Each mold wall portion has on its exterior a chamber into which a heating medium is introduced to heat the mold walls and also into which cooling medium is introduced to cool the walls. A plurality of nozzles are provided in the mold walls and a corresponding plurality of tubes interconnect the nozzles to a manifold located in the corresponding chamber. A pressurized heating medium is introduced to the manifold whereby the heating medium is injected into the cavity to expand prefoamed polystyrene beads in the cavity. A device is provided on the manifold for the selective removal of condensate from the manifold. The mold construction provides for an economical, readily manufactured unit.

대표청구항 ▼

A method of forming an expanded plastic part of a predetermined shape from prefoamed resin beads comprising introducing prefoamed resin beads into a partially open mold cavity of said predetermined shape, said cavity being defined by inner surface of separable mold wall portions, said mold having a

A method of forming an expanded plastic part of a predetermined shape from prefoamed resin beads comprising introducing prefoamed resin beads into a partially open mold cavity of said predetermined shape, said cavity being defined by inner surface of separable mold wall portions, said mold having a chamber defined exterior of and associated with each of said wall portions, a plurality of nozzles provided in at least one of said wall portions and a corresponding plurality of tubes interconnecting said nozzles to a manifold located in the corresponding chamber for fluid communication between the respective nozzle and manifold, said manifold being spaced from a corresponding said wall portion, each of said nozzles having an opening of cross-sectional area which is sufficiently small to preclude formation of evident surface marks on the formed part in the vicinity of each nozzle opening, introducing into said chamber a heating medium to heat said wall portions to a desired molding temperature with said cavity closed and filled with resin beads, injecting a pressurized steam from said manifold through said nozzles into said cavity to expand said resin beads until they fuse and form the desired part, said injection of said steam continuously removing from said manifold any condensate formed in said manifold through means in fluid communication with said manifold for providing a controlled continuous discharge of steam and condensate from said manifold, said manifold discharge means being provided on said manifold at its lowermost position when in use, removing said heating medium from said chambers and introducing into said chambers a cooling medium to cool said wall portions at least until said formed part has cooled sufficiently for removal, and opening said mold and removing the formed part from said cavity by separating said mold wall portions.