Abstract: A screw head device 1 for an injection molding machine includes a ring valve 3 set on a stem portion 2 of a screw head for movement in back and forth direction and for defining a rear side resin passage Rr between its own inner peripheral surface and the stem portion 2, a front side resin passage Rf extending axially and communicated with the rear side resin passage Rr, and a surge preventing mechanism, in which the front end of a screw main body Sm acts as a valve seat for mating with the rear end face of the ring valve 3. At a rear side of the head portion 4, a spacer guide 6 is provided. The outer peripheral surface 6s of the spacer guide 6 is located radially inside of the outer peripheral portion 4s of the head portions end racially outside of the bottom portion Rfd of the front side resin passage Rf.

Abstract: To provide a resin molding method and apparatus that may realize a sprue runnerless system with a very simple structure and at a low cost, a molten resin 4 is fed from a resin supply portion 1 into a pair of cavities 3 through a resin passages 2 such as a sprue portion 2A and a pair of runner portion 2B for molding the resin. The method includes the following steps of: moving a resin return member 5 toward the resin supply portion 1 after supplying the molten resin 4 into the cavities 3, the resin return member 5 being disposed so as to be projectable into the resin passage 2 and movable through the resin passage 2; and returning a waste molded resin 6 under a molten/solid condition within the resin passage 2 back into the resin supply portion 1 under a molten condition by a heat of the resin supply portion 1.

Abstract: The invention relates to an apparatus for injection molding the shells of a mini-disk cartridge or the like. More particularly, the device includes a main cavity having a shape of mini-disk shell. The mold contains various projections and indentations on the first and second surfaces, respectively, which are adapted to form a shutter recess near a first edge of the lower shell, a read/write port for a media disk in a vicinity of the first edge within the shutter recess, a shutter guide track on the outer surface of the lower shell close to and parallel to the first edge, a drive port for rotating a media disk, and various fastening bosses for fastening the upper and lower shells of the mini-disk cartridge together. A single hot-runner valve gate is placed in the mold close to one corner such that small cavities within the cavity are filled with polymer melt first.

Abstract: An injection molding ring valve assembly, having a concentrically disposed axially translatable center valve body member which when in a first axial position allows mass flow through the valve assembly and a separate front valve seat member in the shape of a torus in cooperation with a check ring, thereby providing smooth and unrestricted annular flow through the valve assembly during the priming process of the injection sequence. The check ring, formed from a cylindrical outer ring disposed about the center valve body member, sealingly engages an outer valve seat portion of the torus or front valve seat member. The torus further includes a center hub portion and at least one radially projecting web portion connecting the hub portion and the annular outer portion, resulting in one or more substantially axial semi-annular openings for the smooth and unrestricted passage of molding material.

Abstract: This invention concerns an injection molding nozzle device (25) provided with an operating valve (31) installed movably in the axial direction inside a nozzle body (4) possessed of a resin passage (12) and enclosing therewith a fluid passage (10) incorporating therein a check valve (11). This injection molding nozzle device is furnished with a fluid discharge open-shut device capable of opening or shutting a fluid discharge passage (17) formed separately of the fluid passage (10) or the check valve (11) of the fluid passage (10).

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: Disclosed herein is a hot nozzle for use with a mold for runnerless injection molding of plastic material. The hot nozzle includes a body formed of a conductive metal having a predetermined electrical resistance. The body has a nozzle portion and a base portion, and has a pair of diametrically disposed longitudinal slits extending substantially over the length thereof except at least a portion of the forward end of the nozzle portion in such a manner as to divide the nozzle portion substantially into two sections. The base portion has on opposite ends separated by the slits a pair of power receiving mechanisms for connection to an external source of power. With this arrangement, the nozzle portion itself, particularly at the front end thereof, is heated by voltage applied across the opposite ends of the base portion.

Abstract: An apparatus and method for molding plastic pipettes are disclosed, using an upper and lower mold plate that define a cavity which forms the outer surface of the pipette. The mold parting line of the upper and lower mold plates is located at a position between the ends of the cavity to prevent "radial" flash at the aperture of the pipette. "Axial" flash at the aperture of the pipette is prevented by a lower core pin in the lower mold plate. The lower core pin extends into the cavity and defines the dimensions of the aperture of the pipette. The extension of the lower core pin from the lower mold plate minimizes tool wear at the aperture and makes the alignment of the upper and lower mold plates at the orifice less critical.

Abstract: An improved check valve assembly which is mounted on the front end of a feedscrew of an injection molding machine having a check ring which is slidably mounted on the shank of a retainer within the heated barrel of the molding machine. An annular-shaped flow gap is formed between the inner periphery of the check ring and retainer shank for feeding cylindrical-shaped sleeves of heated material into a discharge chamber at the forward end of the barrel. The check ring is movable between a forward material feed position where it is engaged with a front valve seat and a rearward material blocking position where it is engaged with a rear valve seat.

Abstract: This invention relates to an improved core ring gated injection molding system. The valve pin has a tip portion which joins a larger diameter stem portion at a tapered shoulder and extends through the cavity into the mold platen on the other side. The tip portion of the valve pin is substantially smaller in diameter than the gate through the cavity plate, thus providing for the flow of melt through the gate around it when the valve pin is in the retracted open position. In the forward closed position, the tapered shoulder seats in the gate to provide a seal. By providing for operation in reverse directions to previous core ring gated systems, this increases cooling to the mold platen in the closed position and decreases it in the open position.

Abstract: This invention relates to improved mechanism for actuating injection molding valve pins. In one embodiment, the mechanism is located between two parallel rows of valve pins located in a common plane with their driven ends adjacent the mechanism. The mechanism includes a central elongated member which is longitudinally reciprocable and two parallel elongated transversely reciprocable side members, each located between the central member and one of the rows of valve pins. Each of the side members is connected to the central member by a number of spaced pairs of pivotally connected pins and the central member is secured against transverse motion, while the side members are secured against longitudinal motion. Therefore, the side members are reciprocated transversely when the central member is reciprocated longitudinally by a hydraulic cylinder.

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: 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: 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.