Abstract: A hot sprue valve assembly is provided for controlling flow of molten material through a hot sprue bushing of an injection molding machine. The valve assembly is particularly designed for use with an injection molding machine for molding centrally apertured record discs, such as video information discs. The valve assembly includes a poppet valve movable between an open position to allow flow of molten disc-forming material into a mold cavity, and a closed position to prevent flow of the disc-forming material into the mold cavity. The poppet valve is designed to mold a central aperture in the disc upon movement to the closed position, and the valve assembly is designed to accommodate air ejector apparatus for removing a solidified record disc from the machine.

Abstract: This invention is an improved injection molding nozzle whereby the shut-off plunger is operated by a fluid and the opening of the nozzle is accomplished by the flow of plasticized material through the nozzle. A control rod internal to the nozzle controls the movement of the plunger shut-off member and is adjustable so that the amount of plasticized resin flowing through the nozzle can be accurately controlled.

Abstract: A mechanism for locking together two mold sections includes one or more lock elements rotatably mounted on one of the mold sections, and a respective cylindrical tie rod for each lock element mounted on the other mold section. Each lock element has a cylindrical opening therethrough along its axis of rotation, and a plurality of lock balls disposed in recesses in the surface of the opening so as to form radially inwardly extending hemispherical projections on said surface. Each tie rod is of a diameter slightly less than that of the corresponding cylindrical opening in the lock element, such that the tie rod is axially slidably receivable within the opening. The surface of each tie rod has a plurality of longitudinal guide grooves radially aligned with the lock balls in the surface of the opening, and each lock ball is slidingly received in a guide groove when the tire rod is slidably disposed in the opening. Intersecting each guide groove at substantially a right angle is a lock groove.

Abstract: A valve nozzle is used at an end of a hot runner or an injection molding machine for an injection molding. The valve nozzle comprises a cylinder as a body of the nozzle, and a piston. The cylinder has a gate and has a larger inner diameter at the rear end and a smaller inner diameter at the front end. The piston has a passage in the piston and has a large outer diameter at the rear end and a smaller outer diameter at the front end.

Abstract: An improved nozzle feed assembly is described. The assembly includes temperature-controlled member, preferably cylindrical in shape, having a closed end and an open end. The open end is fitted with standard threads to facilitate attachment of the nozzle member to the feed barrel of a conventional screw-type molding machine. The nozzle member has an internal temperature controlling means and a plurality of feed outlets positioned on the periphery of the nozzle member near the closed end. The temperature maintained in the nozzle member is sufficiently high to maintain the thermosetting molding material within the nozzle member in a plasticized state and sufficiently low that no substantial curing of the thermosetting molding material takes place. In an alternate mode, the assembly includes a sleeve member positioned around the periphery of the nozzle member and moveable to cover and uncover the feed outlets in the periphery of the nozzle member.

Abstract: A mold suitable for use in simultaneous molding of a large number of articles at a time by hot-runner molding technique. The mold has a hot-runner block in which disposed are a plurality of gates through which the molten resin is delivered to the molding cavities formed in a cavity block which is usually kept at a low temperature. The gate area of the hot-runner block is kept in contact with the cavity block, for the safe deliver of the resin to the molding cavities, in the injection step and, therefore, is cooled by the cavity block. Consequently, when the injection is completed, the gate area has been cooled to such a low temperature as to cause a solidification of the resin in the gate area. The hot-runner block is then separated from the cavity block and brought into contact with a hot gate-temperature recovering block, so that the gates are heated to remelt the solidified resin, before the next batch of injection is performed, so as to recover the fluidity of the resin.

Abstract: The instant invention relates to a method and an apparatus for the production of a foam-forming reaction mixture or homogeneous material-forming reaction mixture from at least two liquid reactants and for the subsequent introduction thereof into a cavity, and in particular into the cavity of a mold. The reactants are introduced into a mixing zone where they are mixed together. The mixture is subsequently fed through an outlet of controlled cross-section and charged into a cavity. In order to carry out the method, an apparatus is provided which comprises a mixing chamber arranged in a housing and having inlet openings for the reactants and an outlet opening for the reaction mixture, wherein an adjustable baffle plate is arranged opposite the outlet opening axially of the outlet opening.

Abstract: A gate of a mold for an injection molding machine comprises a valve cone having a circular cone shape or a pyramid shape and a valve seat corresponding to the valve cone wherein the valve cone is pushed toward the valve seat by a spring in the direction reverse to the injecting direction.

Abstract: A nozzle shut-off valve for placing between the injection apparatus and the mold cavity uses two pins of different lengths for the valve elements and switches air pressure back and forth between pistons on opposite (outer) ends of the pins. The pistons have no fixed connection to the pins. Each pin is actuated either by force from the piston on its outer end or pressure by the plastic melt on its innermost other end. The longer pin has a length sufficient to extend completely across the injection passage and block it to prevent any flow. The shorter pin is deliberately made short enough that it cannot block the passage. The valve is actuated by air pressure on the two pistons in timed relation to injection molding events. Pressure on the piston engaging the longer pin compels blocking of the injection passage during plastication. Switching of pressure to the other pin during injection permits the pressure of molten plastic to spread the pins apart whereupon injection proceeds in the ususal manner.

Abstract: An improvement is provided for plastic molding machinery of the type comprising a plastic melt injection apparatus and a mold. A shut-off valve which provides communication between the injection apparatus and the mold, includes a single elongate passageway and an elongate shut-off piston oriented generally parallel to the flow path and mounted in the passageway by a housing, which housing is supported by a single, streamlined leg so that the plastic melt flows therethrough in a single, undivided flow path. The melt flow path, as defined by the passageway and housing mounted therein has a generally circular transverse cross-section at an upstream station and a generally U-shaped transverse cross-section at a station downstream of the circular station. An aspect of the improvement is a plug-shaped tip formed integrally on the downstream end of the piston for expelling residue and cleaning the outlet port especially in structural foam molding applications.

Abstract: A hot runner mold provided with a runner pipe instead of a runner block wherein the walls of both end portions of the runner pipe are formed progressively thinner toward the tip of both end portions so as to cause the inner diameter of the walls to approximate to the outer diameter. One end portion of the runner pipe is made engageable with a hole formed in one side wall of a nozzle assembly and the other end portion is made engageable with a hole bored in a sprue bush. The runner pipe is laid between the nozzle assembly and sprue bush in a state inserted at both ends into said holes with a clearance provided therein in the axial directon of the runner pipe. Upon application of injection pressure, the thin walls of both end portions of the runner pipe expand outward in the radial direction for tight attachment to the inner walls of the holes, thereby presenting a sealing effect.