Abstract: This invention relates to a multi-cavity injection molding system in which a number of nozzles are fixed to a common manifold, and valve gating is provided by actuating the manifold and the nozzles together. A pair of hydraulically actuated pistons are mounted to drive the manifold and nozzles between a retracted open position and a forward closed position. Each nozzle has a truncated tip on the forward end portion which seats in a gate in the closed position. Pressurized melt flows through a melt passage which branches in the manifold and extends through each nozzle to a melt receiving space around the forward end portion. A circumferential sealing and locating flange prevents the leakage of melt from this space as the nozzle reciprocates.

Abstract: An integral heated probe for an injection molding system. The hoop has an insulation and locating hoop portion which bridges an insulative air space and abuts against a circumferential shoulder to accurately locate the probe in a well in the cavity plate. The hoop portion encloses a number of adjacent insulative air chambers which extend circumferentially in the steel body. The hoop portion is brazed in place in a vacuum furnace to be an integral part of the probe. Thus, it provides additional hoop or bursting strength and the air chambers reduce the heat loss through the hoop portion to the cooled cavity plate.

Abstract: This invention relates to an improved method of making an improved injection molding nozzle having an integral electrical heating element which is grounded adjacent the corrosion and wear resistant pointed tip. A main body is made of steel with a cylindrical central portion and a tapered portion adjacent a forward recessed end. The heating element is inserted through a heating element bore drilled diagonally through the tapered portion and wound in a spiral channel machined in the surface of the central portion. A high speed steel tapered tip portion is mounted on the forward end of the main body with the exposed forward end of the heating element extending into a central heating element bore therethrough. The surfaces of the assembly are sprayed with sticky acrylic lacquer and it is then dipped in a nickel powder bath. Beads of nickel brazing paste are applied to the joints. A high speed steel insert portion is dropped into the mouth of the bore, followed by a quantity of nickel brazing powder.

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 and a method of making it. The nozzle has an electric heating element integrally vacuum cast in copper in spiral channels set in the outer surface of the tool steel nozzle body. The heating element has a cold terminal at one end which projects out through a hole in a head plate which is rotatable prior to casting to ensure the nozzle has a consistent length of heating element cast in. A sleeve is located over the spiral channel prior to casting to ensure the heating element in the channel is covered with a minimum depth of copper to dissipate the heat from the heating element. The spiral channel can be cut with a varying pitch according to a predetermined profile to provide more heat where there is more heat loss.

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 an improved injection molding nozzle and method of making it. The components are assembled and dipped in lacquer and powdered nickel prior to brazing in a vacuum furnace. This integrally brazes the components together, embeds an electrical heating element in a spiral channel, and provides the surfaces with a protective nickel coating. In one embodiment, the forward end has an integral high speed steel insert and the remote end of the heating element extends into the forward end of the nozzle. In addition to providing the protective coating, carrying out the method with a single vacuum brazing step considerably reduces manufacturing costs.

Abstract: This invention relates to an improved manifold system for a multi-cavity injection molding system. The manifold system has one elongated bridging manifold which extends transversely across a number of spaced elongated support manifolds. Each of the support manifolds, in turn, extend across a number of heated probes or nozzles, each of which leads to a gate to a cavity. The bridging manifold has a portion of the hot runner passage extending through it from a single inlet to receive melt from the molding machine to a number of spaced outlets. Each of the support manifolds also has an inlet which is in alignment with one of the outlets from the bridging manifold and a number of spaced outlets. Each of the outlets of the support manifolds is in alignment with an inlet to one of the probes or nozzles. Each of the manifold has two way junctions at which a larger diameter portion of the hot runner passage joins two smaller diameter downstream portions.

Abstract: This invention relates to an elongated heating manifold member for injection molding and a method of making it. Channels are cut into the steel body to run parallel to a hot runner passage extending through the body. An electric heating element is centrally located in the channels using small spacer clips to provide a space around the heating element, and the channels are sealed at the ends. A highly conductive material such as a copper alloy is cast into the space around the heating element in a vacuum furnace. This forms an integral unit with the copper alloy fused to both the heating element and the steel body which substantially improve heat transfer in the manifold member. This avoids the creation of "hot spots" which otherwise may result in the heating element burning out, and maintains an even temperature along the hot runner passage which reduces deterioration of the melt due to overheating.

Abstract: This invention relates to an injection molding system in which melt flows in channels in the outer surface of a heated probe seated in the cavity plate on its way to the gate leading to the cavity. The probe has a tip end in alignment with the gate and the probe is reciprocated between open and closed positions to valve gate the flow of melt to the cavity. According to a preferred embodiment, in a multi-cavity system a number of probes are fixed to a manifold which is actuated to valve gate all of the cavities simultaneously. Hydraulic cylinders are provided to drive the manifold to the closed position, and injection melt pressure acting on the tip ends of the probes is utilized to return them to the open position. Valve gating the heated probes provides the advantage of improved temperature control of the melt in the immediate gate area.

Abstract: This invention relates to an improved method of making nozzles for injection molding. The nozzles are heated by an electrical heating element which is cast in a copper portion between inner and outer stainless steel portions. The method includes making a main rear portion and a steel nose cap portion separately, brazing them together in a vacuum furnace to form an integral unit, and then finishing it by drilling and machining to provide it with a central bore and a particular gating configuration. This method has the advantage that a single inventory of unfinished nozzles can be maintained, from which a requirement for one of several gating configurations can be quickly supplied by finishing the nozzles according to that configuration.

Abstract: This invention relates to a novel method of manufacturing an integral manifold for a multi-cavity injection molding system. The manifold has a melt passage which follows a tortuous path and is formed by milling matching grooves without any sharp bends in opposite surfaces of two plates which are then secured together. The manifold is formed of tool steel and also has an electrical heating element which is cast into a channel in its upper surface. The two plates are brazed together and the heating element is cast in the channel in a common heating step under a partial vacuum in a vacuum furnace. A highly conductive copper alloy flows around the heating element and diffuses by capillary action between the opposed surfaces of the plates to form a metallurgical bond with them to improve heat transfer away from the heating element and avoid leakage from the melt passage.

Abstract: This invention relates to a method of manufacturing integral melt conveying nozzle probes for injection molding. The generic term nozzle probe is used herein to include both nozzles through which the melt flows centrally and probes which it flows along the outside of. The method includes forming a stainless steel outer member to receive an electrical heater member therein with a longitudinal space therein. A long thin thermocouple sleeve having a closed forward end is located in the space, which is then sealed against leakage by applying a nickel brazing paste to the joints and brazing them in a vacuum furnace. Copper is then cast into the space in a vacuum furnace to provide a metallurgical bond between the highly conductive copper and the heating element, the thermocouple sleeve and the other parts of the nozzle probe. After casting, a long thin drill is inserted into the sleeve to drill through the closed forward end and a predetermined distance into the copper.

Abstract: This invention relates to an improved heated nozzle probe for injection molding and an improved stack molding system in which it is used. Each nozzle probe has an inner helical shaped heating element which extends into the pointed tip, and a separate outer one which does not. In addition to providing more heat to the pointed tip, this has the advantage that a standard unit can be used for various applications. In the stack molding system, two heated nozzles are arranged in alignment to bridge the parting line and the pointed tip of only the downstream one is heated. Combined with tapering the aligned gates to gradually increase in diameter in a downstream direction, this has been found to considerably reduce stringing and drooling problems as the mold opens for ejection.

Abstract: This invention relates to an improved heated nozzle for injection molding and an improved method of manufacturing it. The nozzle has an elongated body with a melt bore extending generally centrally through it. The cylindrical outer surface of the body has a variable pitched spiral channel extending around it along its length. A helical electric heating element is embedded in the channel to form an integral structure by which the temperature of the hot melt can be maintained within a narrow range as it flows through the bore. The nozzle is manufactured by forming the body with the channel and bore either by investment casting or machining. The heating element is wound in the channel and a bead of nickel brazing paste is run along the top of it. The nozzle is then heated in a vacuum furnace to braze the heating element in the channel. The highly conductive nickel completely covers the heating element and is fused to both the heating element and the walls of the channel.

Abstract: This invention relates to an improved valve gated injection molding system in which the heated nozzle has a nose portion which extends through a cylindrical opening in the cavity plate to the cavity. The valve gate extends through the nose portion and is tapered so that the forward face of the nose portion can be machined to a predetermined length to provide a gate of a particular size. This has the advantage of improving heat transfer to the gate area and reducing the accuracy required of the moldmaker in that both the valve pin and the matching seat in the gate are provided by the manufacturer. Furthermore, each size of nozzle can be adapted for several different gate sizes which reduces manufacturing and inventory costs.

Abstract: This invention relates to an injection molding system of the type wherein a heated probe is centrally located in the hot runner passage. The probe has a pair of circumferentially spaced melt channels, each with an upstream portion which branch out from a common central inlet to a downstream portion along the outer surface of the probe. The probe is seated in a well in the cavity plate and a hollow cylindrical insulating sleeve is located between the downstream portion of the probe and the wall of the well. The outer surface of the probe and the inner surface of the insulating sleeve have longitudinally extending grooves which are aligned to form the downstream portions of the melt channels. The insulating sleeve is formed of a thermoplastic material with low thermal conductivity and a high melting temperature.

Abstract: This invention relates to an improved heated nozzle for injection molding and an improved method of manufacturing it. The nozzle has an elongated body with a melt bore extending generally centrally through it. The cylindrical outer surface of the body has a variable pitched spiral channel extending around it along its length. A helical electric heating element is embedded in the channel to form an integral structure by which the temperature of the hot melt can be maintained within a narrow range as it flows through the bore. The nozzle is manufactured by forming the body with the channel and bore either by investment casting or machining. The heating element is wound in the channel and a bead of nickel brazing paste is run along the top of it. The nozzle is then heated in a vacuum furnace to braze the heating element in the channel. The highly conductive nickel completely covers the heating element and is fused to both the heating element and the walls of the channel.

Abstract: This invention relates to a movel core ring gated injection molding system. Pressurized melt from a molding machine flows through the system and into a cavity. A gate leading to the cavity and a bore in the movable mold platen are in alignment and of the same size to receive the head portion of the valve pin which extends from a reduced neck portion. Actuating mechanism drives the valve pin between a retracted closed position to an open position in which the reduced neck portion extends into the cavity. In the closed position, the head portion of the valve pin extends a considerable distance into the bore in the mold platen to provide sufficient cooling to rapidly cool the melt in the cavity adjacent the pin. In one embodiment, the valve pin has a hollow portion adjacent the neck portion to provide the valve pin with thermal separation between the hot melt and the cool mold platen.

Abstract: This invention relates to an injection molding system having a valve pin which is hydraulically actuated between an open and a closed position in which its tip end is seated in a gate leading to the cavity. The actuating mechanism includes a piston secured to the driven end of the valve pin which reciprocates in a cylinder. The cylinder has an inner cylindrical member which is brazed in an outer member with a flanged portion. Separate hydraulic fluid ducts extend from the flanged portion through the outer member, along grooves in the outer wall of the inner member and then through holes through the inner member to conduct hydraulic fluid to opposite sides of the piston. The flanged portion of the outer member has a pair of passages extending through it, each connected to one of the ducts. Alternate ends of the passages are sealed off so that hydraulic fluid may be received either from supply lines drilled through the back plate in which the cylinder is seated or an abutting top plate.