Abstract: A position detector to detect the fully open position of a valve gate pin in a gate valve controlling the flow of molten plastic material to a die cavity includes a sensing member which has a DC voltage impressed thereon and which is electrically isolated from the valve gate assembly. An extension of the valve gate pin contacts the sensing member when the valve gate pin is in its fully open position to short the impressed voltage and thereby indicate a fully open condition.

Abstract: A multi-cavity injection molding system or apparatus having a spring and sealing housing mounted between each nozzle and the manifold. Each nozzle reciprocates between a retracted open position and a forward closed position in which the tapered forward end is seated in a gate. The nozzle has a central sleeve portion with a bore which projects rearwardly into a matching bore in the housing. Disc springs received in a channel in the housing which extend around the sleeve portion of the nozzle biases the nozzle to the closed position. Thus, during each cycle injection pressure drives each nozzle to the retracted open position, and then the spring bias drives it to the forward closed position when the injection pressure is released. The spring and sealing housing avoids leakage and misalignment as the nozzle reciprocates.

Abstract: The present invention relates to a process and a device for the production of a composite part by the sequential introduction of several fillings (consisting of at least one free-flowing reaction mixture, of which at least one forms a foamed material) into the hollow space of the mold of a closed form tool. A mixing device is attached to form tool. The mixer comprises injector nozzles for the reaction components pointing into a mixing chamber and an ejector piston for the cleaning of the mixer chamber. The ejector piston may be slid forward right up to the outlet orifice of the mixing chamber.

Abstract: A meat patty molding machine having a base plate with an opening therethrough and a fill plate rotatably mounted in the base plate opening. A meat feeder forces meat up through openings in the fill plate. A mold plate defines a disk-shaped mold cavity and is mounted to move laterally between a fill position with its disk-shaped mold cavity in communication with the fill plate and a patty discharge position with the disk-shaped mold cavity away from the fill plate. A drive means rotates the fill plate relative to the mold plate, and the fill plate rotated relative to a stationary cutting blade positioned to cut meat fibers at the upstream surface of the fill plate during filling. By forming the patty while rotating the fill plate relative to the remainder of the mold, a meat patty is formed having longitudinal strands of meat disposed in a substantially circular pattern around the patty axis.

Abstract: An injection molding steel valve member in which a central cooling shaft is surrounded by a series of concentric insulation chambers. Cooling water is pumped through the cooling chamber to remove heat from the forward end of the valve member so the adjacent melt in the cavity will solidify more quickly. The insulation chambers reduce lateral heat loss to minimize the problem of solidification of melt around the outer cylindrical surface of the valve member.

Abstract: A nozzle located in an injection mold for injecting a first medium into a mold cavity containing a second medium. The injection molding has a first bore connected to a first mold surface via a second bore. An outer blowing needle having a first terminal end is located within the first and second bores. An inner blowing needle having a second terminal end is located within the outer blowing needle and has at least one opening near the second terminal end which communicates with the second bore.

Abstract: An injection molding nozzle having a self-supported valve member actuating mechanism. The elongated valve member extends rearwardly into a cylinder assembly which is mounted on the main body of the nozzle. The rear end of the valve member is connected to a pneumatically actuated piston to reciprocate it between the open and closed position. A wedge clamp removably attaches the cylinder assembly to a connector member which is bolted to the rear end of the main body of the nozzle.

Abstract: Process and apparatus for the manufacture of integral roller door structures of any desired length and width, and comprising longitudinally juxtaposed slats separated by integral hinge formations. Such a structure having slats of any desired length can be produced by a semi continuous moulding process in which a molten plastics material and a foaming agent are injected into a mould, the part of the structure so formed being allowed to solidify before removing the solidified structure partially from the mould, then closing mould about the remaining portion of the structure, thereafter moulding a further part of the structure within the mould onto the remaining portion of the previously moulded part and repeating the cycle as often as required.

Abstract: A center entry valve gated injection molding system having a heated nozzle secured in front of a heated manifold with at least a pair of valve member biasing mechanisms extending radially outward from a reciprocating elongated valve member. The melt passage splits into two branches which extend through a manifold outwardly around a rear portion of the valve member. The two branches of the melt passage and the two biasing mechanisms are alternatively evenly angularly spaced around the valve member which considerably reduces the space required. The valve member has an enlarged forward end which opens forwardly into the cavity and is closed in a retracted position in which it seats in the matching mouth of a gate in a nose portion of the nozzle. Each biasing mechanism includes a compression spring which engages a lever member to continuously urge the valve member rearwardly. When injection pressure is applied it overcome the force of the springs and moves the valve member forwardly to the open position.

Abstract: A multi-cavity valve gated injection molding system having an elongated manifold through which a melt passage to a number of heated nozzles. A separate valve member bushing is seated in an opening through the manifold in alignment with each nozzle. The bushing is in bearing contact between the back plate and the rear face of each nozzle. The bushing has a melt duct with two smoothly curved arms which connect between the melt passage in the manifold and the melt passage around the valve member. The bushing provides a seal around the reciprocating valve member and has an outer flange which forms a combination insulative air space and containment chamber for melt which does escape.

Abstract: A valve which serves to admit hardenable metallic, plastic or other material into the die of a molding machine has a housing with a centrally located passage for a reciprocable needle-like valving element, an inlet for hardenable material at one side and adjacent one end of the passage, an outlet which is coaxial with the other end of the passage, an eccentric chamber disposed at the one side of the passage and communicating with the inlet, and an elongated gap which establishes communication between the chamber and the passage. The valving element is movable between an extended position in which it seals the gap from the outlet and a retracted position in which the gap admits hardenable material into the passage so that the admitted material can flow toward and through the outlet. The housing surrounds the valving element in the region of the gap along an arc of more than 180.degree..

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: A valve gated injection molding system having a double acting pneumatic rack and pinion valve pin actuating mechanism. The melt passage branches in a manifold from a central inlet and flows along the valve pin in a central bore in the nozzle to the gate. A pneumatically driven piston pivots a toothed pinion member mounted in a slot in the manifold. The pinion member engages a toothed rack member which reciprocates along a straight line in the slot in the manifold and engages an enlarged head of the valve pin in a slot in the rack member. Lateral forces from the pinion member are absorbed by sliding contact of surfaces of the rack member against matching surfaces of the slot and/or a valve pin bushing, and are not transmitted to the valve pin. This avoids uneven wear and buildup of melt deposits around the valve pin which can otherwise result in leakage and malfunction.

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: A valve gated injection molding apparatus in which the actuating force from a pivotal lever member is transmitted to an elongated valve member through a split ring. The two opposing segments of the split ring are mounted around the neck portion of the valve member when it is in the retracted position. The segments are received in a central opening in the manifold which keeps them in longitudinal engagement with the valve member as they reciprocate. The split ring has a notch which engages the inner end of the lever member. The split ring has a collar portion which extends into the nozzle bore in the forward position and determines the length of travel of the valve member between the open and closed positions.

Abstract: Injection molding nozzle having electric plate heaters mounted thereon. Insulative air spaces are provided according to a predetermined size, shape and pattern between the outer surfaces of the nozzle and the abutting inner surface of each heater. This provides heat transfer from the heaters to the nozzle according to a desired profile along the melt flow passage through the nozzle, depending upon the system configuration and the application.

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: 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: A mold comprises a molding chamber, a sprue aperture communicating with the chamber for introducing molding compound into the chamber, and a mold gate for regulating molding compound flow through the sprue aperture. In accordance with this invention, the mold gate comprises flexible flap means positioned to restrict flow of molding compound through the sprue aperture. The flap means is positioned to be flexed toward the molding chamber by pressurized molding compound, to permit increased flow of the molding compound through the sprue aperture into the molding chamber. The flap means is capable of returning to their original shape when the pressurized molding compound is substantially released of its pressure, particularly in the circumstance where a suction step in the molding compound pressure cycle provides a negative pressure. The flap means in its original shape at least substantially obstructs the sprue aperture.

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: There is provided an apparatus for the manufacture of plastic parts from thermoplastic, thermoset and/or elastomer material by injection molding or reaction injection molding. The apparatus includes a multi-station locking unit of horizontal or vertical configuration adapted to hold a number of molds, and an associated injection unit for the simultaneous injection of the molds. The apparatus further has a movable center mold clamping plate sectioned lengthwise relative to the locking direction, the two parts of the plate being kept together by a high-speed clamping device and having arranged between the parts a melt conduction system having one or a number of separate melt conduction rails. Each melt conduction rail is rigidly clamped at its face between the sectioned mold clamping plate lengthwise relative to the direction of flow of the melt.

Abstract: The invention relates to a single nozzle injection molding system in which the nozzle is reciprocated longitudinally to valve gate the flow of melt to the cavity. The nozzle has a pointed tip which seats in the gate in the forward closed position and is retracted to the open position. The nozzle is secured against rotation, and an inner collar is secured to it. This inner collar threadably engages a surrounding outer collar which is free to rotate, but secured longitudinally. A pneumatic piston is connected to the outer collar to rotate it through a predetermined angle. Thus, when the outer collar is rotated in one direction, the inner collar and nozzle are driven to the forward closed position, and when the outer collar is rotated in the opposite direction the inner collar and nozzle are retracted to the open position.

Abstract: A method and an apparatus for forming a coating layer on a molded product formed in a split-type mold assembly, which assembly includes first and second dies supported for movement relative to each other and a shut-off pin for forming a perforation in the molded product. The shut-off pin is first caused to project into a mold cavity, defined between the first and second dies when the both are closed together, through the first dies during the formation of the molded product. The shut-off pin is then allowed to retract from the mold cavity and inwardly of the first dies, leaving in the molded product the perforation extending completely through the thickness of the molded product.

Abstract: A self-regulating gate valve assembly, adapted for use in a plastic product injection molding apparatus having a mold cavity and a core therein for molding a hollow product of predetermined design, is characterized by a construction substantially eliminating core deflection during plastic molding compound flow in the injection molding apparatus and thus uneven wall thicknesses and weld lines in the hollow molded plastic product. The gate valve assembly includes a valve pin of unique construction for creating a sheath-like flow configuration of the plastic molding compound as it is injected into the mold cavity to produce balanced forces on the mold core to prevent deflection and for closing the gate in a self-regulating manner when the mold cavity is filled.

Abstract: The device for pressure-aided molding of shaped bodies formed from high-molecular masses, preferably of small dimension, comprises at least one preparation chamber having at least one plasticizing or transport and mixing screw conveyor and at least one charging port for filling the preparation chamber with preferably thermally plasticizable and possibly molecularly cross-linkable molding mass. The preparation chamber flow communicates with a pressure-tight transition with at least one storage chamber for plasticized polymer. The storage chamber opens into at least one mold cavity filling conduit for charging a mold with molding mass. The device also comprises a drive mechanism for translatory-relative motion of the preparation chamber and the mold cavity filling conduit. The preparation chamber has at least one prolongation.

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: There is provided an apparatus for the manufacture of plastic parts from thermoplastic, thermoset and/or elastomer material by injection molding or reaction injection molding. The apparatus includes a multi-station locking unit of horizontal or vertical configuration adapted to hold a number of molds, and an associated injection unit of the simultaneous injection of the molds. The apparatus further has a movable center mold clamping plate sectioned lengthwise relative to the locking direction, the two parts of the plate being kept together by a high-speed clamping device and having arranged between the parts a melt conduction system having one or a number of separate melt conduction rails. Each melt conduction rail is rigidly clamped at its face between the sectioned mold clamping plate lengthwise relative to the direction of flow of the melt.

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 relates to laminated preforms, the method of forming such preforms and products which may be beneficially formed utilizing such preforms. Most particularly, this relates to a preform which has formed as part of the injection molding thereof two layers of barrier material which are disposed within two layers of thermoplastic resin and having received therebetween a solid core of thermoplastic resin. The specific method of forming the preform permits the barrier material layers to be of a greatly reduced thickness as compared to such layer thicknesses permissible in the past, with the result that the barrier material layers in the blow molded articles are of a thickness recognized to be acceptable for the barrier function. The barrier material layers may be selectively terminated along the length of the preform so as to permit portions of the resultant blow molded article to be removed and reused. This abstract is not to be construed as limiting the claims of the application.

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 hydraulic actuating mechanism for a valve gated injection molding system wherein the enlarged head of the valve pin is removably connected to the piston and a floating seal is provided against the leakage of hydraulic fluid. The actuating mechanism has a piston which is reciprocated in a cylinder between open and closed positions. The valve pin extends through a bore in the piston and has an enlarged head which is retained in a cup in the piston by a circular cap which fits over it. The cap is held in position between a removable resilient retaining ring which snaps into a groove and a compressible O-ring. Thus, both a seal against leakage and an easily releasable connection between the valve pin and the piston are provided by the combination of the resilient retaining ring and the O-ring.

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: The process and apparatus includes a die assembly having a die cavity defined therein and an inlet port in the die assembly communicating with the die cavity. An injection nozzle is provided for delivering molten synthetic resin to the die cavity through the inlet port having an opening aligned with the inlet port and a thermally insulating sleeve positioned around the injection nozzle having an elastically yieldable component and a rigid component.

Abstract: Disclosed herein is a hot nozzle for use with a mold for runnerless injection molding of plastic material. The hot nozzle includes a body formed of a conductive metal having a predetermined electrical resistance. The body has a nozzle portion and a base portion, and has a pair of diametrically disposed longitudinal slits extending substantially over the length thereof except at least a portion of the forward end of the nozzle portion in such a manner as to divide the nozzle portion substantially into two sections. The base portion has on opposite ends separated by the slits a pair of power receiving mechanisms for connection to an external source of power. With this arrangement, the nozzle portion itself, particularly at the front end thereof, is heated by voltage applied across the opposite ends of the base portion.

Abstract: In an apparatus for producing molded articles from a pourable compound, such as an oxide-ceramic compound, for example a porcelain compound, an injection chamber is formed between an isostatic compression molding tool and an injection chamber. A suction opening is connected to the injection chamber. The pourable compound is supplied through an inlet opening. A fluidizing air inlet line is positioned in the compound inlet opening and it is movable relative to the inlet opening so that it can be placed in an open or closed position for admitting or blocking flow of the compound into the injection chamber.

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: Apparatus for forming a concave lens of resin material and adapted to be used, for example, in spectacles, video projection devices, etc., whereby raw material is fed into substantially the center thinner portion of the mold first and then radially outwardly until the material reaches the periphery, thereby to eliminate weld lines in the produced lenses.

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 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 a pointed heat-generating device for molds of injection molding machines. It comprises a metal casing, a pointed projectile heat-generating means fixed with the metal casing, and a gate formed at the pointed heat-generating means and communicated to a cavity of the molds, characterized in that a heat-generating wire is penetrated wholly into a passage which is bored in a non-processed cylindrical material and an alloy portion is formed in an inert gas between an end of the heat-generating wire and the non-processed cylindrical material, thereby the alloy portion being formed as a pointed part of the heat-generating means by machining.

Abstract: This invention relates to cap means for preventing resin from remaining in a mold of a runnerless injection molding apparatus. The cap means is of a frusto-conical profile and incorporated in a space formed adjacent to a front end of a heating cylinder. Further, the cap means is provided with an opening from which a pointed tip member of the heating cylinder can project. The invention aims at removing resin scorching, its thermal decomposition, inconveniences of color or material exchange or the like.

Abstract: A hot manifold system for use in the injection molding of plastics is disclosed wherein runner channel heating is accomplished by heat pipes disposed within the manifold adjacent to the runner channels contained therein. The manifold system is an elongated structure having a heat receiving portion and a runner containing portion such that heat input may be applied to the heat receiving portion at an accessible location relative to the mold and conveyed to the remainder of the manifold for uniform heating thereof by the heat pipes.

Abstract: A process of producing a moulding by introducing thermoplastics material into a mould space through gate means having a passageway, which process includes the formation of a sprue in the passageway. A retractable member cuts off the sprue before the material solidifies and closes the passageway at its junction with the mould space, the sprue being subsequently ejected from the passageway of the gate means before the next moulding cycle. A holder provides the gate means and the retractable member which is preferably inclined to the passageway. The gate means may also provide air ejecting means for removing the sprue and may conveniently be bolted onto an otherwise conventional injection moulding machine. The retractable member may incorporate a feed pipe for injecting a fluid into the plastics material.

Abstract: In the production of molded articles from a pourable compound, such as an oxide ceramic compound, for example, a porcelain compound, an injection chamber is formed between an isostatic compression molding tool and a superposed injection head, negative pressure conditions are established within the injection chamber. The pourable compound is fluidized and is drawn into the injection chamber by the negative pressure. Subsequently, the compound is isostatically compressed while the negative pressure conditions are maintained during at least the initial phase of the compressing operation. A closing member is positioned at the opening into the injection chamber through which the pourable compound flows. The closing member is displaceable between an open position admitting flow and a closed position blocking flow into the injection chamber. In the closed position, the surface of the closing member facing into the injection chamber forms a continuation of the adjacent surface of the injection chamber.

Abstract: This invention relates to an improved valve pin bushing for use in a multi-cavity valve gated injection molding system and a method of manufacture. Each valve pin bushing has a main body portion which is positioned between the end of a manifold plate arm and the heated nozzle, and a collar portion which projects from the main body portion with clearance beyond the end of the manifold plate arm. The melt passage 34 extending through the manifold plate joins a melt duct extending diagonally through the main body portion and the valve pin is snugly received in a bore in the bushing. The bore has an enlarged portion which receives the melt from the diagonal duct which then flows through the heated nozzle around the valve pin. The valve pin bushing has a peripheral flange which laterally locates it in the cavity plate to offset frictional forces from thermal expansion of the manifold plate.

Abstract: This invention relates to an improved integral manifold for a sprue gated multi-cavity injection molding system and a method of manufacturing the same. The manifold has an inner body portion which fits into a hollow retaining ring portion to define a circular peripheral space between them. The inner body portion is formed of a corrosion and abrasion resistant material such as stainless steel and has a number of straight melt ducts extending through it from a common inlet to spaced outlets each leading to a central bore in separate heated nozzles. The peripheral space contains an electric heating element surrounded by a highly conductive material such as copper. The manifold is manufactured by assembling the retaining ring portion on the inner body portion with the heating element in the space between them. A filler tube is located on the retaining ring portion in alignment with a filler duct therethrough and all the joints are sealed by brazing the assembly in a vacuum furnace.

Abstract: An injection nozzle for use in an injection molding apparatus including a generally annular base portion which supports a generally cylindrical hollow side wall portion. The hollow side wall portion terminates at its upper end portion in an inwardly beveled heat transfer control portion. The beveled heat transfer control portion terminates in an angled mating portion which is of complementary angle to the angled mating surface of an injection nozzle accepting recess in the injection mold portion of the apparatus. The injection nozzle structure provides for controlled heat transfer control from the sprue portion of an injection molded parison to prevent crystallization in the sprue portion of the parison.