Abstract: Multi-cavity injection molding apparatus having two heated manifolds interconnected by a connector bushing all extending in a common plane. A threaded portion of the connector bushing is screwed into a threaded opening in one manifold and a nonthreaded portion of the connector bushing is received in a nonthreaded opening in the other manifold. The nonthreaded portion of the connector bushing fits in the nonthreaded hole in the other manifold tightly enough to prevent melt leakage, but is still able to slide sufficiently in the opening to accommodate thermal expansion and contraction of the heated nozzles relative to the cooled mold in which they are mounted and located. In one embodiment, the connector bushing is made of a material such as a beryllium copper alloy having a greater coefficient of expansion than the steel manifolds so it can be easily installed and then expand to produce this fit when heated to the operating temperature.

Abstract: Edge gated injection molding apparatus wherein each heated nozzle has the combination of a circular sealing ring extending around it and several gate inserts, each extending radially outward from the nozzle in alignment with a gate. The sealing ring bridges an insulative air space between the heated nozzle and the surrounding wall of a well in the cooled mold to provide a sealed portion of the space around the gate inserts. The outer end of each gate insert is spaced a predetermined distance "D" from the wall of the well in which the nozzle is seated to form an opening therebetween. The opening is large enough to allow pressurized melt to flow outwardly therethrough into the sealed front portion of the space between the nozzle and the surrounding wall of the well and small enough to prevent the partially solidified melt in the sealed front portion of the space being sucked back into the melt stream during subsequent injection cycles.

Abstract: Injection molding apparatus with a guide and sealing ring mounted around the front end of a heated nozzle. The stainless steel ring fits around the nozzle and has fingers which are bent over the front end of the nozzle to hold it in place. A thermocouple element extends through a groove in the ring and is bent into a hole in the front end of the nozzle. One of the fingers is bent over the thermocouple element to hold it in place. The outer surface of the ring has a circumferential beveled surface leading to a ridge which guides the nozzle into place during insertion and provides a secondary seal against melt leakage. A number of rearwardly extending fingers have notches to receive a wire wound around the nozzle to hold the thermocouple element and the ring itself in place.

Abstract: Multi-cavity injection molding apparatus having several melt distribution manifolds interconnected by elongated connector bushings. Each connector bushing has an outer sleeve which fits over a nonthreaded cylindrical portion of the main body. The main body is made of a material such as steel with sufficient strength that thermal expansion pushes the manifolds into operating positions slightly further apart without damaging the connector bushings. The outer sleeve of each connector bushing is made of a material such as copper having a coefficient of expansion sufficiently greater than the main body whereby thermal expansion results in the connector bushing forming a seal against melt leakage.

Abstract: Multi-cavity injection molding apparatus having two heated manifolds interconnected by a connector bushing all extending in a common plane. A threaded portion of the connector bushing is screwed into a threaded opening in one manifold and a nonthreaded portion of the connector bushing is received in a nonthreaded opening in the other manifold. The nonthreaded portion of the connector bushing fits in the nonthreaded hole in the other manifold tightly enough to prevent melt leakage, but is still able to slide sufficiently in the opening to accommodate thermal expansion and contraction of the heated nozzles relative to the cooled mold in which they are mounted and located. In one embodiment, the connector bushing is made of a material such as a beryllium copper alloy having a greater coefficient of expansion than the steel manifolds so it can be easily installed and then expand to produce this fit when heated to the operating temperature.

Abstract: Multi-cavity injection molding apparatus having four nozzle manifolds mounted in a common plane with a central inlet manifold having two arms extending in opposite directions. The central manifold has a longitudinal axis extending in a first direction through the two arms. Each nozzle manifold is offset from the central manifold in a second direction that is substantially perpendicular to the longitudinal axis. Each nozzle manifold has a locating pin to locate it in a second direction perpendicular to the first direction. The locating pin allows thermal expansion to slide the nozzle manifold in the first direction into a position wherein each branch of the melt passage is aligned with the melt bore through one of the nozzles extending from the nozzle manifold. A pair of the nozzle manifolds are connected on opposite sides of each arm of the central manifold by connector bushings.

Abstract: An injection molding torpedo which can itself be injection molded by a M/M process of a carbide alloy to have high resistance to corrosion and wear. The torpedo has a conical front surface which forms a pointed tip and a melt channel extending to an outlet on the conical front surface. The melt channel has a central rear portion extending from an inlet on the surface of the torpedo and a diagonal front portion extending from the rear portion to the outlet. The diagonal front portion of the melt channel is tapered inwardly enough to offset the diagonal at which it extends to allow for free ejection of the molded torpedo from its mold. This requires that the taper be enough that the shortest longitudinal line along the inner surface forming the melt channel does not diverge outwardly anywhere along its length.

Abstract: An integral injection molding nozzle having a highly thermally conductive intermediate portion formed between an inner core portion and an outer shell portion. The inner core portion and outer shell portion are formed of materials having high strength which are wear and corrosion resistant. One of the inner core portion and outer shell portion has a plurality of spaced vanes extending radially across the highly conductive intermediate portion to provide more impact strength.

Abstract: Hot tip injection molding apparatus having a heated melt distribution manifold for conveying melt to a number of gates. A number of nozzle manifolds are closely mounted to the front surface of the heated manifold. Each nozzle manifold has a number of spaced nozzle portions extending from a rear manifold portion. A melt channel branches from an inlet on the rear surface of the rear manifold portion to an outlet on the conical surface of each nozzle portion. The rear surfaces of the nozzle manifolds are rectangular rather than round to improve the efficiency of heat transfer from the heated manifold to the nozzle manifolds.

Abstract: This invention relates to an improved heater cast used in multi-cavity hot runner edge gate injection molding. The improved heater cast enables products to be molded of considerably lower heights than was previously the case and as well facilitates the molding of difficult heat sensitive materials such as PVC, polycarbonate, polyester and acetal resins. The improved heater cast has a cylindrical mid portion with four spaced cylindrical lower nozzle portions extending downwardly around the periphery therefrom. The hot melt flows downwardly from the molding machine, through a central injection passage in the heater cast and branches into four injection passage extensions to the respective gates and cavities. The provision of the four lower nozzle portions enables the cavity plate to have a raised table portion therebetween which provides additional strength and cooling.

Abstract: This invention relates to an improved seal for injection molding mechanism. The lower nozzle portion of a heater with the reciprocal valve pin extending centrally therethrough extends downwardly to the gate in the mold. The generally cylindrical seal is horizontally located in an outward upward flare of the air space between the lower nozzle portion and the mold. The seal has a V-shaped lower surface which provides inner and outer circumferential lips which prevent the pressurized melt from flowing upward past the seal. The outer wall of the seal extends across the flare of the air space with only a portion of the outer lip abutting on the mold, thus substantially reducing heat loss from the heater through the seal to the cooled mold.

Abstract: This invention relates to an improved injection molding filter assembly to be located in a passage between the molding machine and the mold to remove contaminants such as wood, paper, or metal from the molten plastic material or melt. The filter assembly has an upstream circular plate located adjacent a downstream circular plate and the plates are secured against relative rotation by pins passing therethrough. The upstream and downstream plates each have a number of circular openings therethrough arranged in concentric circles with each of the openings in each plate partially overlapping at least two openings in the other plate, whereby a plurality of restricted eye-shaped openings are provided through the filter assembly in the abutment plane between the two plates. The filter assembly is securely retained in mating seats in the back plate and the adjoining manifold spreader plate nozzle.

Abstract: This invention relates to a nozzle seal to be used in multi-cavity valve-gated injection molding. A heater cast with a lower nozzle portion is spaced from a cavity plate by an insulating air space and the valve pin reciprocates vertically in the heater cast bore into a gate in the cavity plate. A hollow generally cylindrical nozzle seal is provided across the air space between the lower tip of the nozzle portion and the cavity plate around the gate. The cylindrical seal provides additional heat transfer from the heater to the area of the gate to facilitate operation of the valve pin, particularly seating of the valve pin in the gate, during molding of certain plastic materials with high temperature characteristics. The nozzle seal is formed of a high yield strength titanium alloy and structured to avoid leakage or breakage in this critical area due to high injection pressure and both vertical and lateral relative movement between the nozzle and the cavity plate due to thermal expansion and contraction.

Abstract: This invention relates to a bushing seal for a heater of a valve-gated injection mold. In a single cavity application, the heater is advantageously located directly between the molding machine and the cavity and a valve pin is reciprocated in a cylindrical bore through the bushing seal seated in the upper surface of the heater. The hot runner passage also extends through the bushing seal and joins the heater bore directly beneath the bushing seal. The cylindrical wall of the bore through the bushing seal is interrupted by a circumferential opening vented to atmosphere through a vent passage which relieves the build up of pressure between the valve pin and the wall of the bore and vents corrosive gases to substantially reduce corrosion and wear of the valve pin. A circular valve seat on the bottom face of the bushing seal receives an inclined shoulder on the valve pin to seal the bore of the bushing seal from the molten plastic material in the hot runner passage when the valve pin is in its uppermost position.

Abstract: This invention relates to an improved valve-gated injection molding mechanism illustrated in a multi-cavity arrangement. A vertical valve pin reciprocates in a central bore in a heater enclosed in the mold actuated by an air operated piston through a rocker arm to precisely control the opening and closing of a gate into a cavity through which pressurized molten plastic material is supplied from a molding machine. A titanium alloy seal is provided in an air space between the heater nozzle and the mold near the gate to reduce the quantity of molten plastic material flowing into the space thereby reducing the creation of cold slugs and problems on color changes. The lower portion of the valve pin is formed of a highly conductive material such as a beryllium-copper alloy to increase heat transfer to the lower tip of the valve pin.