Abstract: An apparatus and method for injection molding includes a first melt passage for the flow of a first material, and a second melt passage in communication with the first melt passage for the flow of a second material. The apparatus and method for injection molding also includes a valve pin that passes through the second melt passage. The valve pin has a first portion allowing the flow of the second material, but not the first material, through the second melt passage, and a second portion restricting the flow of the first material and the second material through the second melt passage. The valve pin may also be used to restrict material flow from a melt channel into a cavity. In addition, a back-flow control valve may be combined with a melt passage of the apparatus and method for injection molding. The back-flow control valve has a first portion for permitting flow of material through the melt passage, and a second portion for restricting flow of material through the melt passage.

Abstract: The present invention provides improved heated manifolds, heaters and nozzles for injection molding, having a high strength metal skeleton infiltrated with a second phase metal having higher thermal conductivity. Also disclosed is method of forming a manifold, heater or nozzle preform and infiltrating the preform with a highly thermally conductive material. The invention also provides a method of simultaneously infiltrating and brazing injection molding components of similar or dissimilar materials together.

Abstract: The present invention provides an electrically heated nozzle for injection molding which is insulated to prevent conduction of electricity and loss of thermal transmission to the casing, wherein at least a part of the electrical insulation comprises a layer of dielectric insulator material with an electrical resistance wire wound spirally thereabout and another dielectric insulator layer thereover. Also disclosed is a method for making such a nozzle which includes the steps of applying a first insulator layer, winding electrical resistance wire about the first insulator layer, applying a second insulator layer, and applying a casing layer thereover. The first and second insulating layers may be provided by spraying or through telescoping, self-supporting sleeves.

Abstract: The present invention provides an electrically heated nozzle for injection molding which is insulated to prevent conduction of electricity and loss of thermal transmission to the casing, with first and second thermocouples for sensing temperature of the nozzle, the two thermocouples are independent so they can act either independently or simultaneously to sense temperature conditions in the melt channel of the nozzle.

Abstract: The present invention provides an electrically heated nozzle for injection molding which is insulated to prevent conduction of electricity and loss of thermal transmission to the casing, with first and second electric heaters which can operate independently or simultaneously to heat the melt channel of the nozzle.

Abstract: An externally heated hot-runner nozzle for producing injection molded parts has a resistance wire which is composed of an inner electric heating conductor, a ceramic insulating intermediate layer and an outer metal sheath and comprises two end portions to which a heating voltage can be applied, as well as an intermediate section which in the form of a heating coil is assigned to the circumference of the hot-runner nozzle. The resistance wire is characterized in that the two end portions having an outer diameter of 1.5 mm to 2.5 mm are dimensioned to be larger than the intermediate section having an outer diameter of 1.0 mm to 1.8 mm.

Abstract: A seepage system for an injection molding apparatus includes a manifold plate with a first portion and a second portion abutting the first portion, and a seepage passage positioned between the first and second portions. The second portion may have at least a portion of a melt passage, and the seepage passage may have an outlet. The seepage system also has one or more seepage channels, with each seepage channel being connected to and in communication with the seepage passage. Moreover, the seepage system includes one or more seepage bores for receiving the flow of excess material, with each seepage bore being connected to and in communication with one of the seepage channels. Gravity is used to assist the flow of excess material from the one or more seepage bores through the seepage channels and the seepage passage.

Abstract: An injection molding nozzle with an outer collar portion extending around the rear end of an inner core portion. The nozzle has an electrical heating element with a helical portion extending in a spiral groove in the outer surface of the inner core portion. An integral one-piece construction is provided without having to overheat the heating element by the combination of the helical portion of the heating element being press fitted and reshaped into the groove and the outer collar portion and the inner core portion being secured together by a thermosetting ceramic sealant.

Abstract: Thread split inserts used in injection molding bottle preforms of polyethylene terephthalate (PET). Each insert has a curved inner surface. A pair of inserts are mounted in the mold facing each other so the inner surfaces combine to form an opening therethrough. The opening provides the portion of the cavity which forms the neck portion of the preform. Each of the thread split inserts has an enclosed conduit through which cooling fluid circulates to improve cooling and reduce molding cycle time. The cooling fluid conduit has three curved portions which extend around the curved inner surface. Two of the curved portions extend in one plane and the other curved portion of the cooling fluid conduit extends in a second parallel plane.

Abstract: Injection molding apparatus having several side gate seals extending radially from a heated nozzle. The nozzle has a locating flange portion which is received in an opening in the mold. This laterally locates the nozzle while allowing it to be advanced for mounting of the side gate seals and then retracted to an assembled position where it is longitudinally located by the side gate seals being received in the mold. Thus, the nozzle is longitudinally located in the same plane as the gates and in one embodiment a melt distribution manifold is free to float with the rear ends of the nozzles. This also provides for differences in the thermal expansion due to possible different operating temperatures.

Abstract: An injection molding nozzle with an elongated body removably seated in a one-piece outer collar. The outer collar has a circular insulation flange which seats in the mold to locate the nozzle. The elongated body has an electrical heating element coiled around a central melt channel. Terminal portions of the heating element extend outwardly through a U-shaped opening in the outer collar into a ceramic connector. The connector is secured in place by an inner lip which slides into a groove around the U-shaped opening.

Abstract: Injection molding apparatus having a number of side gate seals extending outwardly from a heated central nozzle to convey melt to cavities spaced around the nozzle. Each side gate seal has an inner end seated in a front portion of the nozzle and extends outwardly across an insulative air space into a radial opening in a cooled mold leading to a gate to a respective cavity. Each side gate seal has a pointed tip in alignment with the gate and a cylindrical sealing rim which fits in a matching cylindrical portion of the radial opening in the mold. This seal around the side gate seal locates the nozzle longitudinally while allowing the cylindrical sealing rim to slide slightly inwardly and outwardly to allow for thermal expansion and contraction of the side gate seal.

Abstract: An injection molding nozzle to be seated in an opening in a mold with an outer collar extending around an elongated central body. The outer collar is made up of two removable semicircular segments which interlock with the central body. Each of the semicircular segments of the collar have a pair of spaced locating and retaining lug portions which extend outwardly to a longitudinal ridge. This provides sufficient thickness for a threaded hole at each lug portion to receive a screw to tighten the rear end of the nozzle securely against a melt distribution manifold. The ridges of the lug portions fit in contact in the opening in the mold to precisely locate the rear end of the nozzle and retain the two semicircular segments in the interlocking position.

Abstract: Valve gated stack injection molding apparatus with an upstream heated nozzle seated in a fixed mold platen and a downstream heated nozzle seated in a movable mold platen. The melt flows through a melt passage across a parting line from an upstream gate to an aligned downstream gate. A first elongated valve member is reciprocated between a retracted open position and a closed position in which the tip of the valve member is seated in the upstream gate. A second elongated valve member is similarly reciprocated between a retracted open position and a closed position in which the tip of the valve member is seated in the downstream gate. In the closed position, the faces of the tips of the valve members abut against each other along the parting line. One of the valve members has a vent bore extending diagonally from its face to avoid a piece of plastic film being formed from melt trapped between them in the closed position.

Abstract: An injection molding one-piece gate and cavity insert to be mounted between a heated nozzle and a cavity. The insert has a cooling fluid chamber extending around the central gate with a thin cavity wall portion extending between the cooling fluid chamber and a convex portion of the cavity. Alternating frontwardly and rearwardly projecting rib portions extend radially into the cooling fluid chamber to form a pair of tortuous passages between them for cooling fluid flowing each way around the insert from an inlet to an outlet. In addition to providing more cooling because of turbulent flow of the cooling fluid and their increased surface area, these rib portions also substantially increase the strength of the insert to withstand repetitive injection pressure in the cavity.

Abstract: A method of making an injection molding melt distribution manifold wherein the melt passage branches through a number of elbows leading to different gates. Each elbow is preformed in a cylindrical plug which fits in a bore in an outer end of the manifold in alignment with a lateral portion of the melt channel. A brazing hole with an upward mouth is drilled in the outer surface of the plug and nickel alloy brazing powder is poured into it. After insertion into the bore in the manifold, the plug is rotated with a suitable tool to a predetermined position with the mouth of the brazing hole pointed downward. The manifold is then heated in a vacuum furnace to integrally braze the plugs in place simultaneously with brazing an electrical heating element in a channel in the manifold. The melt passage is then completed by drilling an outlet bore from the front face of the manifold to the outlet of each elbow.

Abstract: A method of manufacturing an injection molding nozzle having an integral electrical heating element. The heating element is mounted in a space formed between an inner core, an outer rear collar and an outer sleeve. The space is first sealed by brazing with a nickel alloy brazing material and a copper conductive material is then cast into the space. Both the brazing and casting are done in a single controlled cycle of a vacuum furnace. An insulative cap is placed over the assembly so a supply of inert gas to the vacuum furnace cools the copper conductive material from the bottom up. This produces unidirectional solidification to avoid the formation of voids in the copper conductive material and improve thermal conductivity.

Abstract: An injection molding nozzle with a hollow inner portion and a separate removable outer collar portion which sits on a seat in the mold. The outer collar portion has two separate semicircular segments which extend around and interlock with the inner portion with sufficient strength to prevent longitudinal movement of the inner portion when sealing pressure is applied. A resilient split retaining ring clamps the two semicircular segments together in the interlocking position. In one embodiment, the nozzle has an integral electrical heating element with lead portions which extend radially outward to a ceramic insulator. The ceramic insulator has an inner end portion which is also secured in place in an opening between the two semicircular segments.

Abstract: An injection molding nozzle for cold runner molding thermosetting molding material in a heated mold. A bore extends centrally through the nozzle to convey liquid molding material from a cooled distribution manifold to a gate leading to a cavity. An integral cooling fluid conduit has a helical portion extending concentrically around the molding material bore. Cooling fluid circulates from a radial inlet portion to a radial outlet portion of the cooling fluid conduit to cool the liquid molding material flowing through the central bore.

Abstract: An injection molding nozzle seal around the gate which bridges the insulative air space between the front end of the heated nozzle and the cooled mold. The nozzle seal is provided by two removable inserts mounted in alignment with the central melt bore through the nozzle to convey the melt therethrough forwardly to the gate leading to the cavity. The first insert is screwed into a threaded seat in the front end of the nozzle and the second insert is screwed onto the first insert. The inserts each have a hexagonal portion for engagement by a wrench. Both of the engagement portions extend in the air space around the nozzle which facilitates removal of the inserts for cleaning or replacement without disassembling the mold.