Abstract: A method and apparatus for molding plastic materials, particularly foamed plastic materials, in which the materials are introduced into a mold cavity together with a foaming agent with the mold cavity being evacuated not later than immediately after the molding material is supplied thereto. The reduced pressure in the mold cavity causes the material to foam extremely quickly so as completely to fill the cavity while, at the same time, the mold is held closed by the pressure differential between the inside and outside thereof.

Abstract: A first thermoplastic resin for forming the shell of an article is charged into the front portion of an injection cylinder and a second thermoplastic resin for forming the core of the article is charged into the rear portion of the injection cylinder. Both resins are substantially separated, being in contact only a central area of the cross-sectional plane of the injection cylinder. These thermoplastic resins are injected in a mass into a mold cavity with the second resin enveloped by the first resin, and finally solidified in the mold cavity resulting in a molded article having sandwich construction. Various sandwich articles can be obtained easily by means of a single injection molding machine. The process also allows repeated injection operations without exposure of the core material on the surface of the molded article.

Abstract: This invention relates to the production of continuous lengths of polymeric foam by depositing a foam mix in a moving open topped trough shaped conveyor by which it is conveyed and in which the mix foams freely and in the region when foaming takes place, contacting each side surface of the rising foam with an upwardly moving surface, preferably a system of upwardly moving wires interposed between each side surface of the rising foam and its adjacent side wall of the trough conveyor, the speed and direction of travel of the system of wires being selected so that the foam emerging from the foaming region has a flat upper surface.

Abstract: An improved mass production assembly line is provided for fabricating building walls and similar structural members in molds by applying a hardenable polyester film to the cavity surfaces of mold halves, joining the mold halves and then introducing a mixture into the mold cavity to form a polyurethane foam.First and second rectangular fields of rollers, each mounted on a pedestal, are adapted to carry respective mating halves of each mold in a horizontal plane from a start end of the fields to the terminating end. The mold cavities face upwardly. The lower surface of each mold half has secured thereto elongated T-shaped bars. The bars are parallel with each other, and each bar is adapted to be carried by one line of rollers in a respective one of the fields. The parallel axes of the rollers are set to an exact height by means of a laser light source and photoresponsive means so that the upper edges of the rollers lie in the same horizontal plane.

Abstract: An apparatus for in situ preparing and applying foam to a surface, such as a roof, and at the same time applying a membrane onto the surface of the foam, produces a foam-membrane sandwich having an upper surface of controlled smoothness and thickness or pitch, which sandwich is firmly held to the treated surface. The apparatus is normally self-propelled and may be automatically controlled so as to be advanced across the surface to be coated with membrane-covered rigid polymeric foam, preferably of polyurethane foam, as the curing pre-foam and covering membrane are applied. In preferred embodiments of the invention the membrane is a roofing felt or fiberglass web, mat, treated paper or cloth fed from the apparatus from a roll thereon, producing with the roof or other surface to be coated, a form into which a curing pre-foam is deposited as the apparatus is advanced.

Abstract: Method and apparatus for the intermittent manufacture of multi-layer molded bodies of thermoplastic material with a foamed core and an unfoamed shell, wherein a strand of a nonfoaming plastic of ring-shaped cross-section enclosing a strand of plastic containing a foaming agent is injected into a mold.

Abstract: Injection molding apparatus for discontinuous fabrication of molded bodies consisting of a plurality of layers with a foaming core and an outer skin of non-foaming thermoplastic material, the apparatus consisting of an injection head connected to two extruders and equipped with a centrally-located jet surrounded by a ring jet.

Abstract: Molding apparatus for forming an article out of heat-softenable polymeric material, the molding apparatus comprising a mold including a mold cavity and a core insertable into said cavity to define a molding space of the configuration desired in a molded product for receiving the heat-softenable polymeric material, the core being made of heat-conducting material, means, normally including a steam chest in thermoconductive relationship to the mold, for heating the mold, means for admitting into the molding space heat-softenable polymeric material for forming the article and means for conducting steam from the steam chest into the mold cavity to aid in forming expanding and the heat-softenable polymeric material into an article having the shape of the molding space, the last mentioned means comprising at least one duct having a cross-sectional area not greater than 0.001 squre inch, preferably 0.

Abstract: A shuttle is mounted in a passage connecting ducts from injection barrels. An outlet in the passage wall connects to a common sprue channel. The shuttle isolates one duct from the opening at each end of its travel but at no time blocks the opening. The shuttle is preferably a ball and is preferably located in the spigot of a shut-off tap.

Abstract: An apparatus for fabricating foam pads having a generally flat inner surface with a depending peripheral edge, the flat inner surface including a dense outer crust. A spring assembly is adapted to be disposed so that the terminal face portions thereof contact the outer crust and with the depending edge of the pad confiningly receiving the spring assembly to prevent lateral displacement therebetween. The apparatus includes an open top mold, and a mold insert which is adapted to be floatingly positioned on the upper surface of the foaming material to level the same while permitting the formation of a dense outer crust thereon. The depending foam edge may then be formed by adding additional foamable material along the periphery of the pad between the border of the mold and mold insert, or by suitably attaching a preformed foam strip therealong.

Abstract: A foam cushion with a covering of an elastic textile sheet structure is produced in a vacuum deep-draw mould by holding the sheet structure down during the suction cycle with a hold-down plate, but allowing it to slip through locally.

Abstract: Heat-expandable beads of thermo-plastic material such as polystyrene are moulded by steam heating in a metal mould and venting the interior of the mould through apertures in plugs set into ports in the wall of the mould. The plugs are made of low heat conductivity material, for example nylon, to prevent the apertures being blocked by fusion of the beads in contact with the plugs due to heat conduction from the wall of the mould. The steam may be introduced into the mould through apertures in nylon plugs set in ports in the wall of the mould, the low heat conductivity of the nylon preventing the steam raising the plugs to a temperature at which the beads would burn onto the plugs. The same plugs may be used to introduce steam into the mould and then vent the interior of the mould.

Abstract: The method for blow molding foam walled plastic using a quadrisectional mold. A parison of foamed plastic may be blow molded to assume the contour of the closed mold, after which the molded shape is severed into two portions and ejected. Desirably, cellular plastic is blow molded to form hot drink cups.

Abstract: A gating arrangement for use in moulding plastics, particular foam plastics, formed from a plurality of fluid constituents comprises a plurality of nozzles for delivering the constituents under pressure into a mixing chamber. A nozzle needle is associated with each nozzle and is movable between positions which close and open the nozzles. The nozzle needles are moved from the closing position into the opening position by the pressure of the fluid constituents. A hydraulic piston is associated with each nozzle needle for retaining each nozzle needle in a definite position.