Abstract: Valve gated multi-cavity injection molding apparatus. A number of valve pins extend forwardly from a valve pin plate, each in alignment with a gate leading to a cavity in the mold. A pair of cam bars extend beside a pair of actuator bars attached to the valve pin plate. Rectangular slide blocks attached to each actuator bar fit in diagonal grooves in the adjacent cam bar, whereby longitudinal movement of the cam bars moves the valve pin plate and the valve pins forwardly and rearwardly. The cam bars are driven longitudinally by electromechanical or hydraulic actuating mechanism to simultaneously and accurately stop the valve pins in at least three different precise positions during each injection cycle.

Abstract: A method of multi-cavity valve gated three layer injection molding to form containers or preforms having a middle layer of a barrier material between inner and outer layers of a PET type material. The barrier material is injected through an annular channel in each heated nozzle simultaneously with the PET type material being injected through a central melt bore in each valve pin. This reduces cycle time and produces a thicker inner layer of PET.

Abstract: Injection molding apparatus and method wherein a number of cylindrical inserts or plugs each having a curved melt duct therethrough are accurately aligned and securely mounted in spaced cylindrical openings through a melt distribution manifold. An alignment and retaining pin made of a very strong material extends from a bore in the manifold into a bore in the insert. The manifold is heated and the inserts and pins are cooled prior to insertion into place to provide very tight fits when they are at the same temperature which very accurately aligns the melt ducts through the inserts. The combination of the inserts fitting tightly in the openings and the strength of the pins is sufficient to withstand the rearward forces from the pressurized melt being injected through the curved melt ducts to retain the inserts in place.

Abstract: Injection molding apparatus with each elongated cooled mold core (10) having a hollow elongated inner part (78) inside a hollow elongated outer part (80) and an integral dome shaped front cap (132). The outer surface (120) of the inner part (78) and the inner surface (126) of the outer part (80) each having cooling fluid conveying grooves (122, 128) which spiral in opposite direction. This provides very uniform cooling and forces the cooling fluid flow through the grooves (122, 128) to be very turbulent which increases cooling efficiency. It also gives the mold cores (10) additional structural strength to withstand higher injection pressures.

Abstract: Injection molding apparatus with each elongated cooled mold core (10) having a number of cooling fluid bores (118) or grooves (134) extending around a central cooling fluid duct (104). An integral dome shaped front cap (76) encloses the open front end (78). The inner surface (130) of the dome shaped cap (76) has curved ribs (132) which form curved cooling fluid grooves (134) aligned with the cooling fluid bores (118) or grooves (134). The curved ribs (132) give the dome shaped front cap (76) more strength which allows it to be thinner with the curved cooling fluid grooves (134) being closer to the cavity (66) to improve cooling efficiency.

Abstract: Valve gated multi-cavity injection molding apparatus for five layer molding having actuating mechanisms for reciprocating elongated valve members between four different positions. Each actuating mechanism has a front and a rear aligned cylinders, a first piston connected to the head of one of the valve members in the front cylinder and second and third pistons in the rear cylinder. The third piston has a stem portion which extends forwardly through the second piston into the front cylinder. Hydraulic pressure from four hydraulic lines connected to each actuating mechanism reciprocates each elongated valve member between the different positions. In the first closed position, the front end of the valve member is seated in the gate. In the second position, the front end of the valve member is retracted sufficiently to allow an initial amount of PET to flow from an outer annular melt channel through the gate.

Abstract: Sprue gated injection molding apparatus for molding preforms or other products having two layers of a barrier material such as EVOH or nylon alternating between three layers of another thermal plastic material such as PET. The PET is injected by one injection cylinder into first and third melt passages which branch in a front melt distribution manifold to extend to a number of heated nozzles. The first melt passage extends through a central melt channel in each heated nozzle and the third melt passage extends through an outer annular melt channel surrounding the central melt passage to an aligned gate leading to a cavity. The barrier material is injected by another injection cylinder into a second melt passage which branches in a rear melt distribution manifold to extend to an inner annular melt channel extending between the central melt passage and the outer annular melt channel in each heated nozzle.

Abstract: An injection molding one-piece gate and cavity insert with the gate extending therethrough which receives a heated nozzle and forms part of the cavity. The gate and cavity insert has a cooling fluid passage extending through it. The gate and cavity insert has an inner portion, an outer portion and a gate portion. The inner and outer portions which are in contact with the cooling fluid are made of a corrosion resistant material such as stainless steel. The gate portion which is not in contact with the cooling fluid is made of a more wear and heat-shock resistant material such as H13 tool steel or a tungsten carbide.

Abstract: An injection molding one-piece gate and cavity insert to be mounted between a heated nozzle and a cavity. The insert has cooling fluid passages extending through it around the gate and cavity. The passages alternately extend both forwardly and rearwardly and inwardly and outwardly to improve cooling.

Abstract: A method of making a heated injection molding nozzle with an integral tip insert. First, an inner portion, an outer collar portion, and an electrical heating element are made and integrally brazed together in a vacuum furnace using a first nickel alloy brazing material. Then a tip insert is made having a desired configuration and seated in the front end of the inner portion and a second nickel alloy brazing material is applied around it. The second brazing material has a melting temperature which is substantially below that of the first brazing material. The tip insert is then integrally brazed in place by heating them to a temperature above the melting temperature of the second brazing material and below the melting temperature of the first brazing material. In addition to not affecting the metallurgical bonding between the other components, this allows the tip insert to be easily removed for replacement by again heating the nozzle to this same temperature.

Abstract: Injection molding apparatus having a number of heated nozzles extending in a row from an elongated heated melt distribution manifold. Each heated nozzle has a pair of mounting flanges extending outwardly in opposite directions adjacent its rear end. Hollow insulating and locating bushings extend forwardly from the mounting flanges to the cooled cavity plate. The combination of the mounting flanges and the insulating and locating bushings accurately locates the heated nozzles very closely together in a row and spaces the heated elongated melt distribution manifold rearwardly from the cooled cavity plate.

Abstract: Multi-cavity injection molding apparatus having a number of heated nozzles extending from a melt distribution manifold. Each nozzle is aligned with a tapered insert seated in an opening extending through the manifold. Each insert has a melt duct with a smoothly curved bend to connect the melt passage in the melt distribution manifold with the melt bore through the nozzle. Each insert has a flat disc portion abutting against the rear surface of the manifold. Screws extend through this disc portion and the manifold into an outer collar portion of the nozzle to secure the insert and the aligned nozzle directly to the manifold, while allowing the nozzle to be mounted with its electrical terminal having a selected orientation.

Abstract: Multi-cavity injection molding apparatus having several side gate seals seated around the front end of each heated nozzle. Actuating mechanism is provided to advance the melt distribution manifold and the attached nozzles to a forward position without removing the mold from the molding machine. In this position, the front ends of the heated nozzles protrude from the mold to facilitate removal of the side gate seals and hot tip torpedoes for cleaning or replacement.

Abstract: Valve gated injection molding apparatus having three position valve member actuating mechanism for multilayer molding. A first melt passage extends to the gate through an annular channel in a heated nozzle, while a second melt passage extends around an elongated valve member in a central melt channel. A rack member engaging the rear end of the valve member is driven by a pinion member connected to a front piston in a front cylinder. A rear piston in a shorter rear cylinder aligned with the front cylinder has a stem extending forwardly into the front cylinder. First, air pressure applied behind the rear piston retracts the valve member from a first closed position to a second partially open position wherein melt flows only through the annular channel. Then, air pressure applied behind the front piston retracts the valve member to a third fully open position wherein melt flows simultaneously through both melt channels to provide the three layers.

Abstract: Multi-cavity injection molding apparatus for three layer molding having elongated pins for fixed pin gating or valve gating. Each elongated pin has a central melt bore extending rearwardly from its front end to a number of laterally extending bores. A low viscosity barrier material such as EVOH or nylon flows through these bores to the gate leading to the cavity. This allows coinjection with fixed pins and sprue gating in one embodiment and by valve gating in another embodiment.

Abstract: Injection molding apparatus for multi-layer molding two materials with different injection temperatures having an insulative air space extending between front and rear heated melt distribution manifolds. Heated nozzles extending from the front manifold each have a central melt channel and one or more annular melt channels extending around it. Melt transfer bushings each having a central melt bore extend across the air space to convey melt from the rear manifold to one of the melt channels in each heated nozzle. In one embodiment, each melt transfer bushing has a head portion which provides a spacer between the two manifolds, and an elongated stem portion which extends through a bore through the front manifold to one of the heated nozzles. An air space around the stem portion provides thermal separation between the melt from the rear manifold and the front manifold which is at a higher temperature.

Abstract: Injection molding hot runner apparatus having a cooled mold core with an elongated body portion with a front portion or head. A cooling tube extends centrally in body portion of the mold core. A cooling fluid circuit extends from the open front end of the cooling tube outwardly through a number of spaced radial bores. Each radial bore connects to an L-shaped duct leading back to a cylindrical space around the cooling tube.

Abstract: A method of making pairs of thread splits inserts used to injection mold bottle preforms. Machining a hollow outer part of the pair of thread split inserts with an opening therethrough and outer portions of two cooling conduits extending from the opening therethrough to respective inlets and outlets. Making an inner part of the pair of thread split inserts by injection molding a ceramic core with the required shape and investment casting the inner part around the ceramic core. The outer surface of the inner part having grooves to partially form inner portions of the two cooling fluid conduits. Then machining the cast inner part to fit in the opening through the outer part. Mounting the outer part around the inner part with the inner and outer portions of the two cooling fluid conduits aligned. Applying brazing material between the inner and outer parts and heating them in a vacuum furnace to integrally braze them together.

Abstract: Apparatus for stack injection molding wherein a melt distribution manifold is mounted between two manifold retainer plates. A number of heated nozzles are seated in each plate with the nozzles in one plate extending in an opposite direction to the nozzles in the other plate. The nozzles in the one plate are held in place by the manifold being secured to that plate. The nozzles in the other plate each have retaining apparatus to hold them in place during assembly and disassembly. Each nozzle retaining apparatus has a main body with a screw opening therethrough and an elongated pin extending laterally therefrom. The pin extends into a hole in the nozzle and a screw extending through the screw opening in the main body is tightened into a hole in the manifold retainer plate to secure the nozzle in place during assembly and disassembly of the manifold retainer plates.

Abstract: Valve gated injection molding apparatus having a valve member with a cylindrical front end portion. A one-piece insert mounted at the front end of a nozzle has both a gate and locating blades extending inwardly from an outer body into a central opening leading to the gate. The inner surfaces of the blades fit around the front end portion of the reciprocating valve pin to guide and very accurately locate it in alignment with the gate. Very accurately maintaining the front end portion of the reciprocating valve pin in alignment with the gate allows it to be cylindrical rather than tapered which produces a much cleaner gate mark.