Abstract: Injection molds suitable for use in injection molding, structural foam molding, low-pressure injection molding, and gas-assisted injection molding of plastic articles are described. The injection molds contain a thin metal layer contoured on its outer surface to the shape of the article to be molded, a rigid thermoset plastic material cast upon the inner surface of the metal layer and supporting the metal layer, and heat transfer elements cast within the plastic material and located adjacent to the metal layer to transfer heat for the metal layer and the plastic material. Preferably the thin metal layer is nickel, the plastic material is epoxy, and the heat transfer elements are metal chips and heat transfer tubing. The injection molds of the present invention can be prepared at considerable cost and time savings relative to conventional injection molds.

Abstract: An apparatus for gas assisted injection molding having a fluid forcing nozzle with a minimum of moving parts is shown. This apparatus produces an injected molded article by forcing a stream of molding material from a source of molten plastic through a fluid forcing nozzle into an article forming mold space. After the desired amount of material has been injected to fill the mold cavity, the flow through the fluid forcing nozzle is shut off, and replaced by a pressurized fluid or gas flow. The fluid forcing nozzle has an operable valve part operable between a first position and a second position. When the valve part is in its first position, a continuous flow channel from an injection molding machine to a mold sprue is provided for a molten plastic material. When the valve part is in its second position, a portion of the first flow channel is blocked, and a flow channel for an injection gas to the mold sprue is provided.

Abstract: An apparatus for gas assisted injection molding is shown including a source of injection gas and a source of molten plastic or synthetic resin material. The apparatus includes an injection nozzle with a minimum of moving parts. The injection nozzle includes a nozzle body portion having an axially extending bore therethrough for establishing a flow path. A valve chamber is provided in the axially extending bore, and a spherical valve is mounted in the valve chamber for rotation between a first position in which a first flow path is established, and a second position in which a second flow path is established. A sealing member sealingly mounts the spherical valve in the valve chamber, and means to activate the spherical valve are included.

Abstract: Injection molds suitable for use in injection molding, structural foam molding, low-pressure injection molding, and gas-assisted injection molding of plastic articles are described. The injection molds contain a thin metal layer contoured on its outer surface to the shape of the article to be molded, a rigid thermoset plastic material cast upon the inner surface of the metal layer and supporting the metal layer, and heat transfer elements cast within the plastic material and located adjacent to the metal layer to transfer heat for the metal layer and the plastic material. Preferably the thin metal layer is nickel, the plastic material is epoxy, and the heat transfer elements are metal chips and heat transfer tubing. The injection molds of the present invention can be prepared at considerable cost and time savings relative to conventional injection molds.

Abstract: Apparatus and methods suitable for controlling and metering thermoplastic material or resin to multiple cavities in a multi-cavity injection molding tool are described, whereby the amount of resin injected into each cavity can be individually controlled. This system minimize overfilling or underfilling of individual article cavities in such a multiple cavity tool and, therefore, allows for the production of more uniform plastic articles from a multiple cavity mold or tool. In practice, a spindle, which is designed to rotate in a reproducible manner as resin flows past it, is inserted into the resin stream feeding each cavity. The amount of resin fed to a particular cavity is determined by measuring the rotation of the spindle. When the amount of resin fed to a particular cavity is equal to the amount appropriate for that cavity (the target amount), the shut-off valve associated with that cavity is activated, thereby terminating the resin flow to that cavity without affecting resin flow to the other cavities.