Abstract: Multiple nozzle injection molding apparatus wherein each heated nozzle is screwed into a socket in a mounting base secured in place adjacent a melt distribution manifold. Each heated nozzle extends through an opening in the manifold plate and has a nut-like engageable portion extending forwardly of the cavity plate. This allows each of the heated nozzles to be easily removed for cleaning or replacement without removing the cavity plate.

Abstract: Valve gated injection molding apparatus having several valve pins (62) extending through each heated nozzle (12) driven by a common actuating mechanism (70). A valve bushing (100) is seated in the front end (96) of each heated nozzle (12). A central melt bore (50) in each heated nozzle (12) splits in the valve bushing (100) near the front end of the heated nozzle (12) from where the melt flows around each of the valve pins (62) to the gates (66).

Abstract: Multi-layer injection molding apparatus having integral multi-layer melt dividing bushings seated in the melt distribution manifold for dividing a first melt passage extending to annular melt channels in heated nozzles. Matching melt channels machined in the front face of the first layer and the rear face of the second layer of each melt dividing bushing form a melt conduit which branches from an inlet to two spaced holes extending through the second layer. A pair of matching melt channels machined in the front face of the second layer and the rear face of the third layer of each melt dividing bushing form two melt conduits, each of which branch from one of the holes through the second layer to two of four spaced holes through the third layer. The four holes through the third layer align with four melt bores leading to the annular melt channel in one of the heated nozzles. A second melt passage may extend through a central bore in each melt dividing bushing to a central melt channel in the heated nozzle.

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: Multi-layer injection molding apparatus having integral melt transfer and dividing bushings extending from a rear melt distribution manifold through openings in a front melt distribution manifold to aligned heated nozzles. Each bushing has two or three integral layers which are drilled and machined to have melt holes through them connected to melt conduits between them which divides one melt flowing from the rear melt distribution manifold to several bores extending to an annular melt channel in the aligned heated nozzle. In some embodiments, the bushing can also divide a second melt flowing from the front melt distribution manifold to another annular channel in the aligned heated nozzle.

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: 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: 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.