Abstract: In a molding machine wherein in molding a molded article, the molded article is molded into a so-called sandwich shape in which the central portion of the molded article is molded with core layer resin and the outer surface of the core layer is wrapped with skin layer resin, a valve for changing over and injecting the resins from a first injection cylinder for injecting the core layer resin and a second injection cylinder for injecting the skin layer resin is substantially cylindrical, a cut-away portion for changing over and distributing the resins is formed in the central portion of the valve, and sandwich molding is accomplished with the opening-closing of the cut-away portion and each passageway being effected by rotation of the valve.

Abstract: Hot runner injection molding apparatus for coinjecting two thermoplastic materials sequentially through separate channels to form at least a two-layer sandwich material is provided. There is a valve means for instantaneously switching the flow of thermoplastic material from one channel to the other channel, the valve means preferably comprising a shuttle ball member.

Abstract: This device injects plastics material into a mould having a plurality of impressions. It comprises a distribution plate pierced with channels for the inlet of the plastics material to be injected and provided with heating means and an impression plate comprising a plurality of impression inserts into which the plastics material is to be injected. Injection nozzles are disposed between the distribution plate and the various impression inserts, each presenting an injection orifice opening into the impression insert associated therewith and being obturated by an obturator needle mounted to slide axially in the nozzle.

Abstract: An injection mold assembly wherein moldable material is delivered to a plurality of injection molds through a manifold runner and wherein flow into each mold is controlled by a gate valve. The gate valve is mounted independently of the manifold runner and has a valve stem which extends freely through a valve stem passage in the manifold runner with there being an actuator on the side of the manifold runner remote from the injection mold for reciprocating the valve stem to effect opening and closing of the gate valve.

Abstract: This invention relates to injection molding and particularly to a melt transfer system for stack molding. According to the invention, a novel combination of known melt flow control valve units are arranged and operated to control the flow of pressurized melt from the stationary platen adjacent the molding machine to a manifold in the center moving platen. One control valve unit is located in the stationary platen in alignment with another control valve unit located in the moving platen. When the moving platen is in the closed position adjacent the stationary platen, the gates of the two control valve units abut and when the valve pins of the two control valve units are actuated to the open position, pressurized melt will flow through the gates from the stationary platen to the moving platen. The hot runner passage extends from the molding machine through the control valve unit located in the stationary platen.

Abstract: A mold is provided with a pair of cavities interconnected by a runner to a common entry point. One of the cavities is gated whereby plastic may be injected into this cavity only by applying ultrasonic energy to the gate.

Abstract: A mold including a blind channel connected to the sprue runner so that the first material entering the mold will be trapped in the blind channel.

Abstract: An improvement in a method of applying plastic to a planar surface which comprises extruding the plastic through an annular orifice as a ring onto the planar surface. The improvement is particularly helpful in the manufacture of push button ends for beverage cans.

Abstract: The invention relates to a feedhead device for the moulding of plastics materials, especially foamable plastics, to be formed from a plurality of liquid constituents, the device having a mixing chamber charged with the pressurized constituents and a sprue runner adjoining the mixing chamber and leading to a mould cavity. The sprue runner flares toward the mould cavity. To create a uniform distribution of velocity over the cross-section of the sprue runner despite the widening thereof and to prevent the occurrence of evaporation prior to the plastics constituents inter-reacting, the invention proposes the forming of at least one restriction in the sprue runner.

Abstract: A balanced runner system for injection moulding apparatus is disclosed. The runner system has an inlet, a plurality of runners and five gates. One of the gates is centrally located, the remaining gates being symmetrically spaced about the centrally located gate. The runners are such that the runner system is capable of supplying molten polymer to each gate at substantially the same rate. The runner system may be used to obtain a more uniform flow of molten polymer to a mould.