Abstract: A triple stack mold which is operated by a standard mold press and which presents three molding interfaces. Molten plastic is supplied to all molding cavities in equal amounts through a distribution system that includes manifolds in the mold components which receive the plastic and distribute it through passages leading to the mold cavities. The main passages leading to the manifolds are equipped with special nozzles constructed to compensate for differential thermal expansion of the mold parts.

Abstract: A pre-plasticization type injection molding machine is equipped with a plasticizing part for plasticizing synthetic resin material by turning a screw in a heating cylinder and an injection part for injecting the plasticized material through a nozzle by advancing and retreating an injection plunger into and from an injection cylinder. A conduit connects the tip of a plasticizing chamber, consisting of the heating cylinder, with the tip of an injection chamber consisting of the injection cylinder. The screw advances at the time of injection, closes the conduit with its tip. The opening of the conduit in the injection chamber is arranged on the periphery of a nozzle side-wall. An injection passage extends from the injection chamber toward the nozzle, the passage being open to the center of the nozzle side-wall.

Abstract: A molding apparatus includes a rotatable sprue bushing mounted in mold halves and formed with a sprue therein for introducing material into a mold cavity. The sprue communicates with a gate, as an outlet of the sprue, located at a position radially displaced from a center axis of the sprue bushing. Since the sprue bushing is rotated by a ring gear driven by a motor provided in or beside the mold half, the gate of the sprue rotates around the center axis when molten resin is introduced into the mold cavity, and therefore, the molding apparatus can eliminate localization of stress in molded articles, thereby improving quality of the molded articles.

Abstract: A triple stack mold which is operated by a standard mold press and which presents three molding interfaces. Molten plastic is supplied to all molding cavities in equal amounts through a distribution system that includes manifolds in the mold components which receive the plastic and distribute it through passages leading to the mold cavities. The main passages leading to the manifolds are equipped with special nozzles constructed to compensate for differential thermal expansion of the mold parts.

Abstract: A multi-functional mold which is used for encapsulating chips placed on lead frames is characterized by a chamber arranged in one of the mold halves in which an insert can be replaceably arranged. Depending on the use of the mold in the context of the so-called transfer molding method or injection molding method a different insert is placed in the chamber. In the application as transfer mold the insert includes an elongate member with a bore for guiding a plunger which makes encapsulating material liquid due to the pressure applied thereto and the increasing in temperature. In the application as injection mold the insert includes a member with a through-channel allowing a plasticized encapsulating material coming from a nozzle of an injection molding device to flow into the mold.

Abstract: A heated injection molding nozzle having a melt channel which branches outwardly to several spaced edge gates. The nozzle has alternate thermocouple element receiving bores spaced longitudinally along a temperature gradient extending between the heating element and the front end of the nozzle. The nozzle facilitates the temperature control of materials having different thermal characteristics. When molding an amorphous material, a temperature somewhat lower than the prescribed operating temperature is desirable so the thermocouple element is mounted in the rearward bore closer to the heating element. If it is critical to maintain the temperature of the melt near the prescribed operating temperature for a material such as a crystalline material, the thermocouple element is received in the forward bore further along the temperature gradient from the heating element.

Abstract: The present invention relates to a hot runner sealed edge gated injection molding system. The system includes a mold cavity plate with at least one injection gate and a nozzle assembly having a tip end and at least one melt channel for transporting molten plastic material. The system further includes an annular seal ring which fits snugly over the tip end of the nozzle assembly. The seal ring has at least one melt channel and at least one orifice for transporting molten plastic material from the at least one melt channel in the nozzle assembly to the at least one injection gate in the mold cavity plate. In a preferred embodiment, the seal ring is formed from a material having a thermal coefficient of expansion lower than the thermal coefficient of expansion of the material forming the nozzle.

Abstract: An apparatus for gas assisted injection molding is shown including a source of injection gas and a source of molten plastic or synthetic resin material. The apparatus includes an injection nozzle with a minimum of moving parts. The injection nozzle includes a nozzle body portion having an axially extending bore therethrough for establishing a flow path. A valve chamber is provided in the axially extending bore, and a spherical valve is mounted in the valve chamber for rotation between a first position in which a first flow path is established, and a second position in which a second flow path is established. A sealing member sealingly mounts the spherical valve in the valve chamber, and means to activate the spherical valve are included.

Abstract: A seating and sealing insert for mounting a heated injection molding nozzle in a well in a mold. The hollow insert has a cylindrical central portion extending between a rear seating portion and a forward sealing portion. The rear seating portion is outwardly flanged to seat in the well in the mold and forms an inner seat to receive a cylindrical support flange of the nozzle to accurately support the nozzle in the well in the mold. The forward sealing portion has a V - shaped forward face and inner and outer surfaces which are forced outwardly by melt pressure to seal against the nozzle and the mold. Thus, the seating and sealing insert provides an insulative air space between the heated nozzle and the surrounding mold and the forward sealing portion prevents the escape of pressurized melt into the insulative air space.

Abstract: A hot passage nozzle system including a manifold block, nozzle plate and one or more sprue bushings. At one end the sprue bushings are screwed into mating receptacles in the manifold block and centered at the exit openings of the material passageways in the block. The other ends of the sprue bushings are centered in the nozzle plate. The sprue bushings have annular grooves adjacent the connection with the manifold block creating points of flexure in order to accommodate dimensional changes due to temperature changes during use, and also to accommodate manufacturing tolerances.

Abstract: A nozzle for injecting a moldable material has a nozzle body which defines a nozzle channel leading to the nozzle outlet. The nozzle outlet is controlled by an axially slidable nozzle pin extending coaxially through the nozzle channel. A guide sleeve slidably supports the nozzle pin until it reaches the region adjacent the nozzle outlet. As a result, the length along which the nozzle pin is exposed to the moldable material is significantly reduced, thereby substantially eliminating the bending stresses applied to the nozzle pin by the pressure asymmetries in the incoming moldable material. The nozzle pin may also be retracted fully within the guide sleeve to provide an unobstructed path for the moldable material to flow through and consolidate as it approaches the nozzle outlet. With this arrangement, the incoming moldable material may be conveyed towards the nozzle channel asymmetrically with respect to the axis of the nozzle pin without any deleterious effect.

Abstract: A method and apparatus for making a plastic injection molded part with a smooth surface or skin and a hollow core wherein thermoplastic material is injected as a molten stream into the mold cavity through a sprue bushing fixed in the mold. Simultaneously, an unmeasured quantity of inert gas is introduced through an adapter into the molten stream at the sprue bushing substantially coaxially with the melt stream and at a pressure sufficient to penetrate the thermoplastic material to form a gas cavity in the molten material in the mold. For retrofitting an existing mold, an adapter can be added to the exisiting sprue bushing. During plastic injection and cooling in the mold the gas is maintained at a high pressure, preset, constant and adequate to maintain the plastic against the mold surface until it is self-supporting. The gas is exhausted from the mold, back through the sprue bushing and adapter, before the mold is opened.

Abstract: The invention provides a pressure molding apparatus for molten resin capable of efficiently maintaining the temperature of molten resin in the gate pipe, which is provided with molten-resin feeding gate pipes beneath the gate aperture of a molding unit composed of upper and lower molds in order that molten resin can be delivered to the interior of the molding unit before being pressed and molded, where the heater unit for maintaining the temperature of molten resin is disposed in the external periphery of the gate pipes in the state of being divided into two units in the vertical direction. Opposite portions of the gate pipe vertically being divided into two units are connected to each other so that length can optionally be adjusted to the extended or contracted direction, wherein the heater unit is discretely provided in the periphery of the gate pipes which are separately disposed.

Abstract: Hot runner nozzle assembly including a mold assembly with a mold cavity therein, an inlet port in the mold assembly communicating with the mold cavity, an injection nozzle for delivering molten resin to the inlet port and an insulating sleeve positioned around the nozzle between the mold assembly and nozzle insulating the nozzle from the mold assembly.

Abstract: A resin injection port has a tapered outer cylindrical surface, an inner resin passage which is also tapered, and one or more grooves in the outward end thereof to provide a keyway for locking the plastic in the end after cure. The port also has a flange, with a recess matable with a head of a retaining bolt through rotation such that the port is twisted into position for injection. This simultaneously compresses an O-ring which provides a tight seal between the port and the mold. The flange has cut-away portions which align with the bolt head prior to twisting into position. Additionally, the mold has at least one pin which engages a corresponding inner cam surface on the port. The inner cam surface travels over the pins as the flange is twisted to force the port to break the plastic, release and move away from the mold with a 1/4 turn. Utilizing such an injection port provides a means for quickly releasing an injection port from a mold without requiring slide hammers or other such devices.

Abstract: A nozzle for injecting molten plastic includes a housing having an inlet and an outlet. Wires embedded in the housing serve to heat the housing. The housing defines a chamber, and a strainer is disposed in the chamber between first and second guides which are respectively located adjacent to the inlet and the outlet. The strainer and the guides divide the chamber into an outer compartment which surrounds the strainer and an inner compartment within the strainer. A rod extends through the inner compartment and carries first and second pistons which are slidably supported by the first and second guides, respectively, so that the rod can be moved between two terminal positions. Each of the pistons is provided with an axial blind bore and several radial bores which radiate from the associated blind bore.

Abstract: An elongated probe which extends into the melt passage in an injection molding system. The probe has an integral electrical heating element which extends longitudinally from a terminal near the rear end. The probe also has a longitudinal bore which extends beside the heating element to receive a thermocouple wire to monitor the temperature near the forward end of the probe. The heating element extends off center in the body of the probe which provides the body of the probe with the combination of a minimum outer diameter and sufficient thickness between and around the heating element and the thermocouple bore. A forward portion of the probe has a number of outwardly projecting locating fins. The thermocouple wire bends to extend radially outwardly through a groove at the rear end and is retained in place by a retaining screw received in a threaded bore. A ground wire extends in through a hole in a rim portion around the threaded bore and is also clamped in position by the retaining screw.

Abstract: A method and apparatus for providing gas assistance in a resin injection molding process of the type in which hot resin is injected into a mold, gas is injected into the mold to displace a portion of the resin in the mold, the resin cools, the gas is vented, and the mold is opened to remove the molded part. The apparatus includes a high pressure gas storage system, a plurality of pressure control assemblies set at varying pressures and interposed between the high pressure gas storage system and the injection nozzle, and a control system which is operative to selectively communicate each of the pressure control assemblies with the injection nozzle so as to allow the delivery of gas at varying pressures to the mold to facilitate the creation of an individualized gas pressure profile to suit the particular molding requirement.

Abstract: Multi-cavity injection molding apparatus to coinject pressurized melt from two or more melt sources. An inner melt passage extends through the central bore of a melt distribution plate and an adjacent heated nozzle. The nozzle has a tapered nose portion which extends into an adjacent heated cavity forming insert having a gate leading to one of the cavities. An outer melt passage is separated by curved conduits on opposite faces of the melt distribution plate into four channels which are radially spaced around the central bore of the nozzle. The four channels lead to a melt funnel duct which extends in the adjacent cavity forming insert around the nose portion of the nozzle. Thus the melt from the outer melt passage is evenly distributed around the melt from the inner melt passage when they join just before entering the gate.

Abstract: A plastic injection mold apparatus which includes a multiple tip torpedo heater in a fluid plastic flow passageway. The torpedo heater includes an elongated body having an exposed outer cylindrical surface with tips at opposite ends thereof over which the fluid plastic material may be directed at an elevated temperature. The body is formed with an internal bore at the location of each tip for receiving a respective heating element. The torpedo heater is supported within the fluid plastic flow passageway by means of an outer cylindrical collar portion and three circumferentially spaced radial supporting elements which are formed of a softer metallic material than the body of the torpedo heater, and hence, are susceptible to repeated thermally induced expansion and contraction without undesired cracking or failure which can result in leakage of the flow stream and heater failure.

Abstract: A mix head bushing including a body portion having first and second ends. The body portion includes a flange extending radially outwardly from the first end thereof and an essentially conical passage extending therethrough to define a first opening at the first end of the body portion and a second smaller opening at the second end of the body portion. The body portion further includes a second flange having an inner edge extending radially inwardly partially over the second opening. A resilient coating is adhered to the body portion in the passage and extends inwardly beyond the inner edge of the second flange.

Abstract: Optimum sprue design requires suitably large cross-sectional area of the open aperture during mold filling and packing yet fast heat removal from the molten sprue during solidification. This is accomplished by a "hollow" sprue configuration, wherein an enlarged female sprue bushing cavity of large draft angles is axially aligned with a "spreader die" type of male member having a generally conical-tipped or parabolic-tipped torpedo shape, creating a cross-sectional open aperture consisting of an annular ring along at least partway up from the base to the tip. Both male and female may be fitted with internal mass-transport cooling. Since the cooling time of the sprue is directly proportional to the wall thickness of the molten plastic sprue being formed, and cooling time is further inversely proportional to the plastic/mold surface area, the resulting "hollow sprue" provides superior cooling without impaired fill and pack function.

Abstract: A method and apparatus for making a plastic injection molded part with a smooth surface or skin and a hollow core wherein thermoplastic material is injected as a molten stream into the mold cavity through a sprue bushing fixed in the mold. Simultaneously, an unmeasured quantity of inert gas is introduced through an adapter into the molten stream at the sprue bushing substantially coaxially with the melt stream and ata pressure sufficient to penetrate the thermoplastic material to form a gas cavity in the molten material in the mold. For retrofitting an existing mold, an adapter can be added to the existing sprue bushing. During plastic injection and cooling in the mold the gas is maintained at a high pressure, preset, constant and adequate to maintain the plastic against the mold surface until it is self-supporting. The gas is exhausted from the mold, back through the sprue bushing and adapter, before the mold is opened.

Abstract: Apparatus for thermal gated injection molding having a cavity forming insert separate from the heated nozzle. The cavity forming insert has a combination of heating and cooling extending around a central melt bore leading to a gate. The cavity forming insert has an integral electric heating element with an inner portion having a number of adjacent coils near the gate. Power to the heating element is switched on and off during the thermal gated cycle, and the combination of heating and cooling in the cavity forming insert improves the thermal response and shortens the cycle time.

Abstract: An integral heated torpedo for use in injection molding has an internal melt distribution chamber which distributes heated melt through multiple melt flow paths onto the exterior surface of the torpedo. The torpedo is formed from a single piece of metal and has an elongate body portion which extends axially from an enlarged end portion and which terminates in tip. The center of the torpedo body portion contains an axial cavity extending between the torpedo tip and the enlarged end portion. The bore is adapted to receive a heating element which includes a coil of resistance wire and a thermocouple which are surrounded by heat insulative material. A plurality of melt flow passages extend axially through the enlarged end portion and are disposed generally around the torpedo bore to provide a series of melt flow paths through the enlarged end portion onto the heated exterior surface of the torpedo body.

Abstract: To extend the useful life of the elastic seal (6) which is arranged between a base plate (1) and a cover plate (2) of molds for the production of flat moldings of curable casting resins and through the passages (8) of which the mold cavity is charged with the casting resin melt and vented and to accelerate venting and filling, the passages (8) are in the form of fixed capillary tubes (9) which project partly into the seal (6) and which are each adjoined by a channel (10) opening into the mold cavity (3) and closure needles (13) insertable into the channels are provided.

Abstract: An insulated injection molding nozzle having several alternating layers of stainless steel and ceramic insulating material surrounding an integral spiral electrical heating element. The coils of the heating element are wound around a central cylindrical portion of the body of the nozzle extending between larger diameter rear and forward collar portions. The alternating layers are plasma sprayed over the coil from a thin inner stainless steel layer to a thick outer stainless steel layer. The heating element and an outer shoulder portion are vacuum brazed in two stages to provide a completely integral structure.

Abstract: An injection molding thermal gated nozzle having a nose portion which extends forwardly to the cavity. The nozzle has a melt channel which extends through the nose portion to form the gate. An integral electric heating element has a forward portion with a generally rectangular cross section and a number of adjacent coils which form an inwardly tapered inner surface. Part of the inner surface of the forward portion of the heating element forms an inwardly tapered portion of the melt channel adjacent the gate. This direct contact of the heating element with the melt reduces considerably the cycle time of the thermal gate. The forward portion of the heating element is shaped by compressing it between tapered dies. It is then mounted between forward and rearward portions of the nozzle, and the assembly is integrally brazed together in a vacuum furnace.

Abstract: A sprue gated injected molding system having nozzles with a removable hollow gate insert received in a seat in the forward end of each nozzle to form the gate. Each gage insert has a forward portion with a tapered outer surface which abuts against a matching tapered surface of an opening through to mold to the cavity. The forward portion of the gate insert is resilient which ensures extremely good contact between them under bearing pressure due to thermal expansion of the nozzle. Thus optimum uniform heat transfer is provided between the gate insert and the cooled mold. The gate insert has a circumferential removal flange to facilitate it being pryed out of the seat if replacement is required. In an alternate embodiment an elongated torpedo is seated centrally in the melt bore of each nozzle. The torpedo has an outer retaining ring and a number of radially extending tapered fins which form melt flow channels between them.

Abstract: A nozzle assembly for mounting on a cold runner block has a cooled housing with a bore and a nozzle member with a shaft portion mounted in the bore for rotation about a bore axis. A cap portion of the nozzle member is connected to the shaft portion and has a surface for positioning close to the mold surface of a mold member. A mold cavity in the mold member has a mold orifice in the mold surface for alignment with a nozzle opening in the surface of the cap portion. The nozzle opening is positioned radially outward from the bore axis and is rotatable into alignment with the mold orifice upon rotation of the nozzle member. A nozzle passage extends from the nozzle opening to the bore for communicating a fluid molding material to the mold cavity. A spring device may be disposed between the housing and the nozzle member to urge the surface of the nozzle member towards the mold surface. A ball member with a flat sealing surface may be mounted in a spherical recess in the surface of the cap portion.

Abstract: An injection molding system having at least one insulation gate seal extending outwardly to bridge an insulative air space between a heated nozzle and the adjacent cooled cavity plate. Each seal has a central bore therethrough to convey pressurized melt from the nozzle to the aligned gate. The outer end of each seal has a circular groove extending between a central portion and a surrounding flange portion. The flange portion is substantially larger in diameter than the gate and extends outwardly past the face of the central portion into sealing contact around the gate against the surrounding surface of the cavity plate. The combination of the clearance provided between the face of the central portion and the surrounding surface of the cavity plate and the distance between the gate and the surrounding flange portion limits the temperature of the cavity plate immediately around the gate, while still providing the necessary seal.

Abstract: To provide a thermodynamic pinpoint gate nozzle which will permit a so-called cosmetic gate without stringing, and during which the plastic material to be processed is not subjected to high viscous or shear stress by the heating elements placed inside the nozzle channel, it is provided that the pinpoint gate nozzle on the side facing the mold cavity exhibits a low-mass inside nozzle (7) and that inside nozzle (7) can be heated by an ohmic resistance wire either inductively or by inside nozzle (7) formed as a Peltier element.

Abstract: A method, system and device utilized therein for the injection molding of plastic articles of enhanced surface quality using pressurized fluid. The fluid is prevented from contaminating the molten resin in the nozzle from which it was injected to thereby eliminate splay. The method involves the initial step of injecting molten resin at a nominal injection pressure from the nozzle of an injection molding machine through a resin injection aperture at an upstream position in a mold. The resin travels along a resin flow path in the mold to a mold cavity defining the shape of the molded article at a downstream position. The device at least partially defines the resin flow path in the mold. A charge of fluid pressurized at a predetermined level is communicated to the resin flow path through an orifice in the device which opens to the resin flow path.

Abstract: A valve gated injection molding system having a heated nozzle which is secured to a heated manifold received in a well in a cooled cavity plate. An insulative air space extends around between the heated nozzle and the cooled cavity plate. An locating flange extends outwardly across the insulative air space from either the nozzle or the manifold into contact with the surrounding cavity plate. The locating flange has number of holes extending transversely therethrough according to a predetermined configuration to reduce heat loss from the heated nozzle and manifold to the surrounding cooled cavity plate.

Abstract: A valve gated injection molding system having a novel valve member for large volume applications. The elongated valve member has a ribbed insulative portion between the main steel portion and a conductive portion adajcent the tip end. The conductive portion provides more rapid cooling when the tip end is seated in the gate in the closed position. The adjacent insulative portion provides a thermal barrier to reduce heat flow along the valve member to the conductive portion. This combination avoids sticking of the tip end when the mold opens and thus allows cycle time to be reduced. The conductive portion has an integral beryllium copper plug which is supported by radially extending ribs of the insulative portion to withstand continual repeated impact loading every time the gate is closed.

Abstract: An injection molding multi-gate nozzle with a central portion having a central melt bore and a spiral electrical heating element integrally brazed in a channel in its outer surface. The nozzle has a number of elongated conductive probes spaced in a sleeve portion which extends around the central portion adjacent its forward end. Each probe extends in the sleeve portion a predetermined distance rearwardly along the central portion and projects from the sleeve portion a predetermined distance forwardly of the forward end of the central portion. Each conductive probe has a copper inner portion which picks up heat from the adjacent coils of the heating element and carries it forwardly to the projecting forward portion adjacent one of the gates. In addition to providing additional heat, this configuration with the forwardly projecting probes provides the mold with more structural strength and improved cooling.

Abstract: A nozzle touch sprue bushing device for a unit-type injection metal mold which includes a molding body such as a metal mold including an inner mold element which is removably mounted on an outer frame mounted on an injecting molding machine, wherein a sprue bush has a nozzle touch provided at a rear end thereof for fitting with an end of a nozzle of an injecting machine, and has a front end formed in such a fitting configuration as to allow fitting engagement thereof with a material admitting portion of a metal mold.

Abstract: A valve gated injection molding system for making hollow plastic products. A fixed pin extends through an elongated hollow valve member which is reciprocated between a retracted open position and a forward closed position in which the forward end of the valve member is seated in the gate. The fixed pin has a hollow portion for the flow of pressurized gas to a porous portion at the forward end which is centrally located in the gate. In the open position, gas from the fixed pin flows into the hollow center of a stream of melt which flows into the cavity around the forward end of the fixed pin to form a melt bubble in the cavity.

Abstract: An injection molding heater assembly for use in multi-gate injection molding includes an elongate heating member extending within a mold bore in heating communication with the mold bore mold gates. The heating member has an elongate body portion extending between an inlet portion and an outlet portion. A melt injection passage extends through the inlet portion to convey melt along the body portion to an enlarged portion having a nozzle face. Extending down from the nozzle face are a series of members which include gate tips at their lower ends. Radial channels present in the gate tips serve as extensions to the mold bore mold gates. The gate tips are peripherally spaced apart around the nozzle face and define a recess between the gate tips, the nozzle face and the mold bore for initially injected melt to accumulate in and solidify to form a melt plug. The melt plug serves to insulate the subsequently injected melt from the mold bore and maintain the injected melt in a third condition.

Abstract: An injection nozzle for an injection molding machine having a heating device for heating its injection nozzle body (3) protruding from the front end of the heating cylinder (1) thereof. The heating device is composed of a plurality of heating members (7, 10) longitudinally arranged side by side. The temperatures of the different nozzle body sections heated by the respective heating members are individually detected (9, 11), the heating members (7, 10) being individually controlled in accordance with the temperatures thus detected. The construction enables the different nozzle body sections to be individually set to a desired, optimum temperature. The nozzle front end section 3b, for example, which is in contact with a metallic mold and whose temperature is consequently apt to be lowered can be kept high, and the nozzle middle-rear section 3a, which is near the heating cylinder and whose temperature is consequently apt to be raised, can be kept low.

Abstract: This invention relates to a gate insert which screws into the forward end of an injection molding nozzle and a method of making it. The gate insert has an intermediate portion which extends between a threaded cylindrical rear portion which screws into the nozzle and a cylindrical nose portion which is secured in an opening in the cavity plate and forms the gate. A gradually tapered melt bore extends axially through the gate insert, and an electrical heating element is integrally embedded in the gate insert with a helical portion extending around the melt bore to maintain the temperature of the melt as it flows through the bore. The gate insert is made by forming a body portion with a neck portion having a tapered outer surface extending between the rear portion and the nose portion. A recess is machined in the tapered surface and a helical portion of the heating element is wound in the channel. A nut portion having a matching tapered inner surface is mounted on the neck portion.

Abstract: This invention relates to an injection molding nozzle having an improved heating element configuration in the tapered nose portion and a method of making it. A longitudinal portion of the heating element which is integrally brazed centrally into the nose portion is bent back upon itself at least once to provide a multiple thickness part. The type and length of the multiple thickness part which is selected to provide additional heat depends upon the application which the nozzle is to be used for. The multiple thickness part of the heating element is swaged to provide a more circular cross-section before being brazed into a larger diameter part of the heating element bore through the nose portion of the nozzle.

Abstract: A method and associated apparatus for the injection molding of plastic articles of enhanced surface quality using fluid pressure. The method involves the initial step of injecting molten plastic at a nominal injection pressure from an injection molding machine through a flow path to a mold cavity defining the shape of the molded article. A charge of fluid pressurized at a predetermined level no greater than the nominal plastic injection pressure is communicated to the plastic flow path through an orifice of sufficiently small dimension to resist entry of the molten plastic against the pressure of the fluid charge. The pressurized charge of fluid responds to a reduction of the pressure in the plastic flow path below the predetermined level upon substantial completion of plastic injection and enters the flow path and passes into the mold cavity. The fluid is contained within the mold cavity under pressure until the article has set up, and is thereafter vented to atmosphere.

Abstract: A mixing plate apparatus for use in a conventional reaction injection molding mixing head. The injection molding mixing head has a metering valve system to produce a chemically reactive of at least two fluid reactant streams which are metered into a mixing chamber within the mixing head through an orifice over which is disposed a mixing plate composed of a multi-portal grate. The plate is composed of a plurality of apertures symmetrically disposed thereon. The plate introduces turbulence into the fluid stream as each stream is introduced into the mixing chamber to ensure more efficient mixing with the other fluid stream(s). The reacting mixture is then ejected form the mixing chamber into a desired mold cavity.

Abstract: This invention relates to an injection molding system having an axially aligned forward and rearward heated nozzle mounted in tandem. The rearward nozzle is seated in a fixed position, while the forward nozzle reciprocates between a retracted open position and a forward closed position to provide valve gating. The forward nozzle has a rearwardly extending sleeve portion which projects into the rearward nozzle to connect the melt bores of the nozzles as the forward nozzle reciprocates. The forward nozzle has a heated nose portion with a tip which seats in the gate in the closed position. A pneumatically actuated piston bears against the rear end of the forward nozzle to drive it to the closed position. Injection melt pressure around the nose portion drives the forward nozzle back to the open position.

Abstract: A nozzle head of thermoplastic material injection nozzle is closed in the customary manner with a closure head which has a jet orifice. A jet needle closes the jet orifice in a closed position. The needle is held axially displaceable in a needle bearing. An actuation lever is set into a slit-like recess in the needle bearing and it is supported with a bearing ball carried at the rear wall of the needle bearing. A stroke transmission bolt set inbetween jet needle and actuation lever in overhung position serves for transmitting the closing force from the actuation lever to the jet needle. Upon opening, the injection pressure pushes the jet needle rearward if the actuation lever is rotated into the open position. In this arrangement a locking spring becomes superfluous and, consequently, no force counter to the spring force must be effected by the injection force.

Abstract: The present invention relates to a system for injection molding large parts. The system includes a large diameter hot runner valve gated nozzle assembly which can be removed for servicing. The assembly includes a heated nozzle body having a substantially C-shaped flow channel for conveying molten plastic to a nozzle having an injection gate and a valve arrangement for opening and closing the injection gate. The assembly further includes a nozzle extension attached to the nozzle body so as to accommodate thermal expansion of the nozzle extension. A manifold for supplying molten plastic material to the nozzle assembly is mounted and retained within a slot in the nozzle extension so as to permit sliding action of the manifold.

Abstract: In a vent type injection molding machine of the type comprising a heating cylinder, injection nozzle means having a vent port and connected to the front end of the heating cylinder and a reciprocatable screw for metering a predetermined quantity of resin to be injected, the injection nozzle means comprises a first injection nozzle connected to the heating cylinder, a second injection nozzle coaxial with the first injection nozzle, a spring for urging the second injection nozzle against a stationary metal mold and a housing surrounding the first and second injection nozzles. The vent port is provided through the housing at a point communicating with a space in the housing between the first and second injection nozzles.

Abstract: This invention relates to a hot tip gated multicavity injection molding system wherein an elongated heated probe extends centrally in a straight portion of the melt passage leading to each gate in a position wherein a tip end of the probe is centrally aligned adjacent the gate. One part of the straight portion of the melt passage is formed by a locating sleeve which is seated in the cavity plate and has spaced pins which extend inwardly to contact the outer surface of the probe to accurately locate the probe with the tip end in central alignment with the gate. Each probe has a central heating element with a double thickness portion extending to provide additional heat where the pins contact the probe. One of the pins is hollow to receive a thermocouple to measure the temperature of the melt flowing past the pins.

Abstract: A nozzle utilized to grout or fill cold joints and cracks formed in or occuring at structural corners. The nozzle includes a tip which is defined by converging planar surfaces about an axial opening. The nozzle tip defining surfaces include a relatively large area which is separated from the nozzle axial opening for wall contact to permit the nozzle to be secured by an adhesive or bonding agent to the corner walls before injection of the grouting material or sealant.