Abstract: This invention relates to an injection molding system having a number of nozzles conveying melt from an elongated manifold to a common cavity. In the preferred embodiment, each heated nozzle has a melt channel which is offset from a central valve pin bore for conveying the melt to the gate. The melt channel extends through a side portion of the nozzle which is bolted to the side surface of the manifold. The bolts provide a seal against leakage of the pressurized melt, while at the same time allow slight lateral movement between the manifold and the nozzle. This provides for thermal expansion of the manifold relative to the nozzle which is accurately located in a well in the core. The system is used for large cavities which require large flow volumes and avoids the difficulty of accurate machining of the large molds to provide sealing.

Abstract: This invention relates to a valve gated injection molding system in which a number of melt conveying nozzles leading to a common cavity are releasably clamped to the side surface of an elongated manifold. A cylindrical collar around the inlet to each nozzle is received in a recessed seat around each outlet from the manifold. This structure facilitates assembly and ensures alignment of the inlets and outlets, while permitting for some rotational movement between the nozzles and the manifold due to thermal expansion. The integral nozzles are made by vacuum casting a heating element and vacuum brazing a side member with a sidewards projecting face into a steel main body.

Abstract: This invention relates to a method of providing an injection molding heated nozzle with an improved electrical terminal. A plug is seated in a radial opening in the collar portion with heating element extending through it and the rear end of the heating element projecting a minimum distance from the front surface of the plug. The insulation and casing are stripped from the projecting portion and the exposed resistance wire is welded to a flat surface on a larger diameter threaded conductive stud. A sleeve having a threaded and broached inner surface is mounted over the stud with the outer end of the stud projecting beyond the outer end of the sleeve. The plug and sleeve are integrally brazed in place during the brazing step forming the rest of the nozzle. A liquid ceramic insulating material is poured to fill the space between the stud and the surrounding sleeve.

Abstract: This invention relates to an improved injection molding nozzle having an integral electrical heating element. The nozzle has an elongated nose portion extending to a forward end from a cylindrical central portion. The heating element is brazed in a spiral channel around a central melt bore in the central portion of the nozzle, and extends into the nose portion to a forward end which is grounded by brazing it in nickel adjacent a high speed steel insert portion at the forward end of the nozzle. This forms a pointed tip at the forward end of the nozzle which is corrosion and wear resistant and can be heated to a predetermined temperature. In alternative embodiments, the forward end of the heating element can be brazed in nickel adjacent the forward end without the high speed steel insert portion and/or the nose portion can be inclined with the forward end of the heating element being grounded adjacent an end gate rather than a separate gate.

Abstract: This invention relates to a valve gated single cavity injection molding system wherein the valve pin actuating mechanism is cooled by circulating hydraulic fluid through it. The cylinder is mounted in a cylinder housing inside a dome portion of a heated manifold housing. The cylinder housing has a wing portion extending out openings in each side of the manifold housing. Each wing portion has an inlet duct and an outlet duct for hydraulic fluid across which a pressure differential is applied. The ducts connect to circumferential channels which extend around the outside of the cylinder and lead to respective openings into the cylinder. Thus, the application of hydraulic fluid pressure during operation circulates hydraulic fluid through the actuating mechanism. The cooling which results extends the operating life of the mechanism, particularly the seals and O-rings.

Abstract: This invention relates to a multi-cavity valve gated injection molding system wherein a continuous flow of hydraulic fluid through the actuating mechanism provides additional cooling. A pair of hydraulic fluid lines are drilled in the mold back plate to apply a minimum pressure differential across the cylinder chamber on one side of the piston. In the preferred embodiment, this pressure differential is also applied to opposite sides of a circular cooling chamber extending through the cylinder to provide additional cooling near a high pressure seal. Additional cooling is very advantageous to avoid system malfunctions and inferior product, particularly when molding high performance engineering resins at a high temperature.

Abstract: This invention relates to sealing and support bushings which are located between the manifold and the mold back plate to encircle each valve pin in a multi-cavity valve gated injection molding system. Each bushing is bolted through the manifold to a respective heated nozzle with central bores in alignment to receive the valve pin therethrough. The bushing has an outer flanged portion which extends to contact the mold back plate and forms a leakage containment chamber between them. Thus, the bushings retain the manifold in place, seal against substantial melt leakage around the reciprocating valve pins and collect any melt which does escape to prevent it entering the insulative air space between the hot manifold and the cooled mold back plate. Location of the bushing between the manifold and the mold back plate also enables the use of a standard manifold having longitudinal and transverse bores without requiring diagonal bores.

Abstract: This invention relates to a manifold housing for a valve gated single cavity injection molding system. The heated manifold housing has a dome portion and a base portion which is secured to a heated nozzle with aligned central bores through which the valve pin extends. Hydraulic actuating mechanism is mounted inside the manifold housing to reciprocate the valve pin between open and closed positions. The melt duct in the manifold branches from a central inlet into two separate arms with smoothly curved bends which extend to join the central bore on opposite sides of the valve pin. Providing two streams of melt which meet at the valve pin avoids the problem of streaking and slow melt flow on one side of the valve pin.

Abstract: This invention relates to a valve gated injection molding system having an improved rocker arm assembly connected between the valve pin and the actuating mechanism. The rocker arm assembly includes an elongated rocker arm which is pivotally mounted in a groove in a cylindrical support member. The rocker arm assembly is removably received in a bore in the mold bore and the rocker arm is disconnectable from the valve pin, whereby the rocker arm assembly is quickly and easily replaceable without disassembly of the mold.

Abstract: This invention relates to an improved valve pin bushing for a multi-cavity, injection molding system. The valve pin bushing has a central bore through which the valve pin extends. The melt duct extends through the bushing to join an enlarged portion of the central bore around the valve pin. In the bushing according to the invention, the melt duct branches into two arms with smoothly curved bends which lead to opposite sides of the valve pin. This avoids the problem of streaking and slow melt flow on the opposite side of the valve pin.

Abstract: This invention relates to a valve gated injection molding system in which melt flows through an elongated manifold to a number of spaced nozzles to fill a single non-linear cavity. Each nozzle is mounted against a manifold offset block which is bolted to the side of the manifold. Pressurized melt from the manifold flows through a melt duct in each manifold block and through the central bore of the respective nozzle to a gate into the cavity. Actuating mechanism is mounted to reciprocate a valve pin extending through each manifold block and nozzle. Each manifold offset block can be mounted with a different orientation on the side of the manifold to properly space the gates along the non-linear cavity to ensure it completely fills as quickly as possible. Slight lateral movement of each manifold block relative to the manifold is permitted to avoid melt leakage due to misalignment of the nozzles as a result of thermal expansion of the manifold.

Abstract: This invention relates to an improved method of manufacturing injection molding manifolds for multicavity molding. The method includes gun drilling a longitudinal duct through a steel manifold body, drilling a transverse inlet duct to connect to an inlet on one surface of the manifold, and drilling diagonal outlet ducts to connect to spaced outlets on the opposite surface of the manifold. The outlet ducts are smaller in diameter than the longitudinal duct to match the rest of the system. Before the outlet ducts are drilled, end portions of the longitudinal duct are drilled out to a larger diameter and steel plugs having a tapered well are securely welded into them with the mouth of the well in alignment with the longitudinal duct. The plugs are larger in diameter than the central portion of the longitudinal duct to avoid the formation of thin knife edge portions where the outlet ducts join the longitudinal duct which often break down during use.

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 an improved injection molding filter assembly to be located between the molding machine and the mold. The assembly has an elongated inner torpedo member with a generally cylindrical outer surface which is centrally located in a passage through a hollow outer member. The passage is defined by a generally cylindrical inner wall which is interrupted by an even number of inwardly opening longitudinally extending channels. Inlet channels extending from the inlet of the assembly and dead ending adjacent the outlet alternate with outlet channels extending from the outlet of the assembly and dead ending adjacent the inlet. Filtering apertures are formed between the outer surface of the torpedo member and the lands between the inlet and outlet channels through which the melt flows from the inlet channels to the outlet channels.

Abstract: This invention relates to an improved injection molding filter assembly to be located between the molding machine and the mold. The assembly has an elongated inner torpedo member with a generally cylindrical outer surface which is centrally located in a passage through a hollow outer member. The passage is defined by a generally cylindrical inner wall which is interrupted by an even number of inwardly opening longitudinally extending channels. Inlet channels extending from the inlet of the assembly and dead ending adjacent the outlet alternate with outlet channels extending from the outlet of the assembly and dead ending adjacent the inlet. Uniform width elongated filtering slits are thus formed between the outer surface of the torpedo member and the lands between the inlet and outlet channels. The melt flows into the inlet channels, through the adjacent filtering slits, and out the outlet channels.

Abstract: This invention relates to improved flow control mechanism for valve gated injection molding. The mechanism is of the type where movement of the valve pin is controlled by a pneumatically driven rocker arm. The back plate is cast with an integral pivot pin portion projecting from it and a pivot ball is fixed in a seat on the end of it. The rocker arm has a recess which receives the pivot ball for pivotal motion on the pivot pin portion of the back plate. The back plate is cast of a steel with sufficient strength and flexibility to withstand the repeated lateral loading on it due to the pivotal motion of the rocker arm, while the pivot ball is formed of a significantly harder material to avoid unacceptable wear where it is in moving contact with the rocker arm. Casting the back plate rather than machining it, enables bends in the runner passage extending through it to be smoothly curved, thus avoiding "dead spots".