Abstract: A method is disclosed for operating a valve needle for plastic processing plants. The needle valve may be controlled by a control valve, which in turn is controlled by a working gas volume in order to prevent formation of internal waviness in injection molded articles even under very high gas pressures and to assure high flexibility in production without refitting delays. During plastic mass injection the valve needle seals tightly. During gas return the valve needle remains open until the gas bubble in the mold cavity is completely emptied.

Abstract: A hot runner system for injecting precise quantities of at least one resin advancing under pressure from a resin source wherein the system includes a shooting pot having a piston with opposed working surfaces which divide the shooting pot into at least two reservoirs. Resin under pressure is switched cyclically from one reservoir to the other whereby the piston is driven by resin under pressure to purge one reservoir while the other reservoir is loaded.

Abstract: The present invention relates to a filler injector for applying a filler to crevices in concrete surfaces. The injector has a transparent outer tube having scale markings thereon to indicate the pressure of any filler backing up from the surface and an adaptor connectable to a pressurized source of filler and screwed onto the outer tube. The injector also includes a check valve mounted in the adapter, an inner tube mounted inside a closed top of the outer tube and having a bore therein which can convey the filler from the adaptor to the surface, and a piston slidably mounted inside the outer tube and on the inner tube. The filler injector thus will not result in unwanted explosion, implosion, or skipping of a seam joint because of the pressure of the filler, and will provide a reading of the filling pressure on the concrete surface as the filler is being applied.

Abstract: In the plasticizing cylinder the plasticized plastic material is transported by a rotating feed screw into a space which is in front of the feed screw and the plastic material is subsequently injected into the injection mold of the injection molding machine by an axial discharge stroke of the feed screw. During that stroke a backflow-preventing valve is effective to seal a high-pressure space from a low-pressure space, which contains the feed screw. The plasticizing cylinder is composed of a cylinder head, which always completely encloses the high-pressure space and the backflow-preventing valve, and a cylinder shank, which encloses the low-pressure space and the feed screw. Even when the feed screw is in its rearmost initial position will the high-pressure space not be adjoined by a joint which leads to the outside of the plasticizing cylinder so that the problems previously encountered in connection with the sealing of the high-pressure space are avoided.

Abstract: A method and an apparatus of injection molding articles of thermoplastic material. The method includes initially forcing molten plastics material into an injection mold in an amount sufficient for forming the article. Subsequently, a flowable medium is forced into the injection mold with a pressure which distributes the plastics material uniformly over the surface of the mold cavity of the injection mold so as to form a hollow body. The hollow body is then cooled while the pressure of the medium is maintained. Finally, the pressure of the medium is released and the molded article is removed from the injection mold. The pressure of the medium in the mold cavity is controlled and/or varied at least temporarily until the plastics material has cooled. The apparatus for carrying out the method includes a pressure reservoir for the medium which is connectible to the injection mold through lines. The lines include control and/or regulating elements.

Abstract: This invention provides an improved injection molding apparatus which includes a check valve assembly mounted at the forward end of a feedscrew, the valve assembly being characterized by forward and rearward valve seat surfaces which co-act in a first position to allow a plasticized polymeric material to enter and flow through the valve into an injection chamber and which co-act in a second position to stop any additional material from entering the valve assembly. The second valve position is effected by a feedscrew injection stroke which generates a backpressure to close the valve, the backpressure moving a check ring of the valve assembly into a position to block entry into the valve. The valve seat surfaces are coated with a bonded metal, metal alloy, or ceramic material which effectively increases the abrasion resistance of the valve seat surfaces and thus also increases the wear service life of the check valve assembly. Other wear surfaces of the valve assembly may also be coated for abrasion resistance.

Abstract: The invention relates to a mixer device with distributive mixing action for an extruder, an injection moulding machine and the like, including a hollow stator and a rotor arranged for rotation in the stator and at least one separate mixing ring which is provided at least on its interior surface with mixing elements and which is arranged between the rotor and stator around the rotor for free rotation, characterized in that the mixing elements includes passages which are radially orientated in the mixing ring and are facing at one end the inner stator surface and on the other the outer rotor surface, and to a rotor section, to a mixing ring, to an extruder, and to an injection moulding machine provided with same.

Abstract: An injection apparatus of an injection-molding machine is described, including a servomotor for screw rotation including a pulse coder, the motor being driven in accordance with the difference between a command output from a control section of the injection-molding machine and an output from the pulse coder, thereby rotating a screw. During injection and pressure hold processes in which the motor is rendered nonoperative, the screw rotates as molten resin flows backward, if a check valve attached to the screw does not function normally, and this situation is detected as an abnormality of the check valve by a control section.

Abstract: A positive-type, non-return valve (10) primarily for use with an injection molding machine utilizes a frame (12) which surrounds a coaxial primary chamber (34). The primary chamber (34) is accessed by several passages. Inlets (30) allow material to be fed to a reduced diameter passage (34) adjacent to said primary chamber (32). Outlet passage (42) connects this reduced diameter passage (34) to outlet ports (40). A piston (60) is dimensioned to fit within said primary chamber (32) and reduced diameter passage (34). In a forward position, the piston (60) allows positive flow of material therethrough. In a rearward position, the piston (60) positively blocks flow of material from the inlet (30) to the outlet passage (42). The piston (60) is forced to its rearward position during the injection step.

Abstract: A check valve is provided that is especially useful in gas-assisted injection molding wherein pressurized gas is injected into molten plastic material. A tapered or cone-shaped valve member which seats into a correspondingly tapered or cone-shaped valve chamber provides the mechanism by which the valve seals against reverse flow. Any plastic material entering the gas passageway would contact the base end of the tapered or cone-shaped valve member and not any sealing surfaces. By minimizing contact with the sealing surfaces, the useful lifetime of the check valve is significantly increased.

Abstract: A non-return valve for an injection molding machine is provided which includes a conventional tip member threaded into the end of a plasticating screw and carrying therewith an annular valve seat member. An annular check ring receives the tip member. Tang protuberances axially extend from the check ring to rotably engage the retainer end of the tip member. This causes the check ring to couple with the tip member during screw rotation to minimize valve wear while permitting the check ring to axially move relative to the tip member for effecting valve closure by pressure differentials in the normal manner. A ramp surface is provided on the tang protuberances which engages a drive surface on the retainer end of the tip/stud member upon reverse rotation of the screw through a predetermined rotational angle or for a set time to positively close the valve prior to injection.

Abstract: The valve needle of a gas sealing valve for plastic processing plants may be controlled by a control valve, which in turn is controlled by a working gas volume in order to prevent formation of internal waviness in injection molded articles even under very high gas pressures and to assure high flexibility in production without refitting delays. During plastic mass injection the valve needle seals tightly. During gas return the valve needle remains open until the gas bubble in the mold cavity is completely emptied.

Abstract: A die casting vacuum valve has a cover die block and ejector die block. A cushion member is positioned in the cover die block and a reciprocating member is positioned in the ejector die block such that upon reciprocation of the reciprocating member, it contacts the cushion member and cover die block to seal the reciprocating member with the cover die block and the surrounding surface. A controller mechanism controls the reciprocation of the reciprocating member such that the reciprocating member contacts the cushion when the molten material enters the mold cavity and slot to prevent further flow of the molten material in the slot past the reciprocating member.

Abstract: A nozzle for injecting viscous fluid such as a thermoplastic into a mold cavity of a mold body includes a tip section and a nozzle body secured thereto. The tip section serves as a sprue of the mold body. The mold body includes a core portion, a cover portion and a clamp plate for securing the core portion to the cover portion. The nozzle body having an inlet end, a discharge end, which communicates with the tip section, and a flow passage for viscous fluid extending from the inlet to the discharge end. A valve element is mounted for reciprocation in the nozzle body flow passage to control the flow of viscous fluid through the nozzle body discharge end. At least the tip section of the nozzle body is located in the mold body cover and the nozzle body is substantially positioned between the mold body cover and the clamp plate. The valve element can be a shut-off needle which is disposed for reciprocating movement in the nozzle body flow passage.

Abstract: A stringiness-preventing pad having a resin passage hole defined by partition leaves is interposed between a sprue bush and an injection cylinder nozzle so that the partition leaves are spread by the pressure of molten resin material being injected into a mold and elastically closed upon completion of injection. The resin material solidified in the sprue is prevented from stringing by virtue of the partition leaves when removing a molded object from the mold.

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: An anti-backflow valve for mounting on the forward end of a plasticating screw rotatably and translatably carried in a tubular barrel of an injection molding machine. The valve includes a rod-like body member that extends forwardly of the plasticating screw for rotation relative to the screw and for axial translation relative to the screw for a limited distance. A retaining sleeve is threadedly secured to the forward end of the screw to define a forward stop to limit axial outward movement of the body member relative to the screw. The outer surface of the retaining sleeve includes a valve seat that is engagable with a sealing surface on a screw tip that is carried at the forward end of the body member. The screw tip includes flow passageways extending substantially axially therethrough to provide communication between the space ahead of the screw and an area behind the screw tip and between the screw body and the screw-receiving tubular barrel.

Abstract: An injection adapter for introducing a flowable compound into a drilled hole in masonry has a plastic tubular part having an inner thread in the upper end thereof for engaging a threaded end of a bolt of a fixing element anchored in the drilled hole which threaded end projects from the drilled hole. The injection adapter has a lower tapering end having a front annular end face for engaging an adjacent annular end face of a sleeve of the fixing element.

Abstract: A heated plastic flow control valve assembly which is intended for use in controlling the flow of molten plastic to a mold in a molding press includes a spring biased slide valve that cooperates with a valve body to shut of plastic flow unless the slide valve is displaced against the spring. This displacement is caused by engagement of a plastic injection machine nozzle with the slide valve. Two separately controllable heaters are useable to provide two heat zones in the valve assembly.

Abstract: The invention relates to a mixer device with distributive mixing action for an extruder, an injection moulding machine and the like, including a hollow stator and a rotor arranged for rotation in the stator and at least one separate mixing ring which is provided at least on its interior surface with mixing elements and which is arranged between the rotor and stator around the rotor for free rotation, characterized in that the mixing elements include passages which are radially orientated in the mixing ring and are facing at one end the inner stator surface and on the other the outer rotor surface, and to a rotor section, to a mixing ring, to an extruder, and to an injection moulding machine provided with same.

Abstract: An injection molding machine has a high volume cylinder with a piston slidably disposed in the cylinder. The piston is formed with channels and check valves for selective communication from the back of the cylinder to the front of the cylinder. A vertically disposed screw plasticizer provides molten thermoplastic material to the back of the cylinder, which material flows to the front of the cylinder with rearward movement of the piston. When the front of the cylinder is filled with thermoplastic material, the piston is moved forewardly to inject the thermoplastic material into a mold. A reciprocating screw plasticizer first assists in filling the front of the cylinder, and then in completing the injection molding under a high pressure. Novel composite thermoplastic products may be produced.

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: Apparatus operative to reduce molten plastic drool when the injection unit is separated from the runner system. The apparatus includes access means for closing the runner system when the injection unit is disengaged therefrom and for opening the runner system for engagement with the injection unit, wherein the injection unit is operative to move the access means away from the runner system for engagement of the injection unit with the runner system.

Abstract: A device for the injection of a plastic material in a mold having an injection head with an injection face designed to be placed in contact with the mold feeder channel. The injection head has an injection chamber supplied with plastic material by a feeder conduit. The plastic material is injected from the injection chamber to the mold feeder channel by means of a clack-valve system. The device also has a support for the injection head and an injection rod.

Abstract: An extruder screw of a plastic injection molding machine has a tip seal device at its forward end. The tip seal device has a body portion and a tapering tip portion, a circumferential sealing skirt is provided between the tip portion and the body portion. During extrusion, the pressure of molding material behind the skirt compresses it radially to allow for passage of the material through an extruder nozzle. When the screw is moved forwardly after extrusion, pressure of material forwardly of the skirt increases and expands the skirt radially into contact with the extruder barrel to form a seal.

Abstract: An injection molding method and nozzle for use therein wherein first and second variable pressures are applied to a piston of a valve mechanism of the nozzle so that a differential fluid pressure on the piston causes a tip portion of the valve mechanism to alternately open and close. In this way, the tip portion communicates the flow of resin from a nozzle body of the nozzle to an injection aperture of a mold. Differential pressure on the piston prevents a fluid which distributes the molten resin over the interior surfaces of the mold from entering the flow path of the molten resin in the nozzle body. The fluid preferably is a gas, such as nitrogen. Preferably, the piston is mounted for reciprocating movement within the nozzle body and the first pressure is provided by the resin during resin injection and the second pressure is partially applied by the nitrogen gas.

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: 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: A plasticizing unit for an injection molding machine includes a carrier block; a plasticizing cylinder securable to the carrier block; an injection nozzle having a nozzle body connected to the front end of the plasticizing cylinder; a discharge outlet at the front end of the nozzle body; a valve needle cooperating withe the discharge outlet and having a closed position shutting off the discharge outlet and an open position allowing discharge of material from the plasticizing cylinder through the discharge outlet; force-transmitting linkage means being connected to the valve needle; and a power unit for displacing said force-transmitting linkage means and the valve needle into the open or power unit for displacing the valve needle into the open or closed position.

Abstract: A plastic material molding apparatus, wherein when the pressure at a material inlet of a cylinder of a material holding mechanism increases as a piston in the cylinder compresses a resilient member provided in the material holding mechanism, the speed of a motor for driving a material fluidizing mechanism is reduced. A servo motor for intermittently driving a plastic material metering and delivering mechanism is controlled according to the revolution speed and a predetermined total number of revolutions of the servo motor and to the number of pulses from a pulse generator provided in the servo motor. A relief valve is interposed between a material delivery port and a delivery nozzle of the metering and delivering mechanism, the relief valve being adapted to open when the material pressure at the delivery port is higher than the relief pressure, the relief pressure being set higher than the vapor pressure according to the temperature of the material at the delivery port.

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 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: Injection molding apparatus (10) for processing and transferring molding material from a feed mechanism (30) to a nozzle (75) for discharging into a mold including a bolster (12), an injection head (11) extending through the bolster, an injection barrel (37) in the injection head for containing a predetermined sized shot of the molding material, a plunger (46) movable in the injection barrel for discharging the shot of molding material into the mold, a bore (47) extending longitudinally of the plunger for loading molding material into the barrel, feed mechanism (30) supplying molding material to the bore of the plunger irrespective of the position of the plunger, and a valve (60) closing the bore upon movement of the plunger in one direction for discharging the shot of molding material and opening the bore upon movement of the plunger in the other direction for discharging the barrel with a predetermined shot of molding material.

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: An apparatus (10) for molding metallic articles such as wheel weights (11). Opposed mold sections (108, 109) are carried on support plates (41, 42) that are movable within a stanchion (40) by virtue of an actuating means (45). A feed mechanism (115) delivers mounting clips (18) to one of the mold sections (109), and an escapement means (135) assures that only one clip (18) is delivered at a time. The actuating mechanism (45) sequentially closes the mold sections (108, 109) to form a cavity (100) therebetween, moves the closed mold sections (108, 109) into engagement with an injection tube (79) which mates with a sprue hole (111). The injection tube (79) also presents a positioning lug (180) accurately to rotate the clip (18) to its desired disposition.

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: An injection molding valve nozzle comprises a nozzle head with a gate dividing a flow passage into two sections, a spool slidably attached to the gate and including axial grooves in its outer surface and a spring for urging the spool rearward. The valve nozzle is so arranged that the gate is closed by the spool because the grooves do not reach the gate upon lower pressure of resins below a certain level, but that the spool may slide forward to extend the grooves over the gate, communicating a front passage with a rear passage upon higher resin pressure above a certain level and that when the pressure differential between the front and rear passages decreases or the resin pressure descends below a certain level, the spool slides rearward by the spring for closing the gate.Thus, the gate is closed by the spool until the resin pressure rises up to a certain level.

Abstract: An apparatus for purging an injection molding machine utilizing a three stage or three position nozzle assembly.

Abstract: An improved check valve assembly which is mounted on the front end of a feedscrew of an injection molding machine having a check ring which is slidably mounted on the shank of a retainer within the heated barrel of the molding machine. An annular-shaped flow gap is formed between the inner periphery of the check ring and retainer shank for feeding cylindrical-shaped sleeves of heated material into a discharge chamber at the forward end of the barrel. The check ring is movable between a forward material feed position where it is engaged with a front valve seat and a rearward material blocking position where it is engaged with a rear valve seat.

Abstract: A cut-off process for an injection molding machine for forming two-layer, directly laminated footwear soles and includes a pressure transmission pin which is guided in a passageway constructed as a through-hole between the mold cavity and the outer surface of the mold. The pressure transmission pin is preloaded by a spring in the direction of the mold cavity so that it can be depressed or actuated under injection pressure. When the injection pressure is relieved and the molded piece shrinks, the pressure transmission pin will be moved back by the spring to its initial position, thereby releasing a switch for a new switching operation for the next, second, injecting operation.

Abstract: An apparatus and method for molding polycarbonate lenses is disclosed in which the lenses are formed in a single injection molding operation. Polycarbonate is injected into a cavity between two movable dies which are forced apart by the injected polycarbonate. These dies are then urged together forcing a portion of the injected polycarbonate back through the same port through which the polycarbonate was injected. The finished lens does not have the knit line normally associated with injection molded lenses.

Abstract: A backflow preventer on the end of a plastifying screw for an injection molding apparatus has a housing provided with radial bores which are axially and angularly offset. A pin accessible from the exterior of the housing passes through a radial hole but traversing in a valve member with clearance to permit the stroke of the valve member to be adjusted by selective insertion of the pin in the bores.

Abstract: A backflow preventer at the end of an injection molding worm has a pressure ring which abuts directly upon the worm and serves a shank of the valvehead which also bottoms in a bore upon the worm so that force transmission to the worm is over its entire cross section. The shank is surrounded by a blocking ring which can shift in its axial stroke between a position in which it abuts the head and a position in which it abuts the pressure ring, the axial stroke being adjustable by shims forming the floor against which the shank abuts within the bore of the worm.

Abstract: Hot runner injection molding apparatus for coinjecting two thermoplastic materials sequentially through separate channels to form at least a two-layer sandwich material is provided. There is a valve means for instantaneously switching the flow of thermoplastic material from one channel to the other channel, the valve means preferably comprising a shuttle ball member.

Abstract: A shut-off nozzle for injecting molten resin into a mould cavity comprises a cylinder to be connected to a moulding machine, a nozzle head attached to the front end of the cylinder to be connected to a mould, a flow path for molten resin through the cylinder and the nozzle head, a torpedo disposed in the flow path, and a shut-off pin protruding from the front end of the torpedo. The torpedo is of a streamline shape and is divided into a front portion having a hole and a rear portion having a cavity. A spring is disposed in the cavity applying forward force onto the shut-off pin. The cross sectional area of the shut-off pin to accept pressure of molten resin and the force of the spring are adjusted so that the shut-off pin is in the front position until the pressure of molten resin becomes a predetermined value.

Abstract: The method and apparatus for the injection of an injection material into a mold includes an upright extruder mechanism having an upright feed screw driven from its lower end. Material introduced at the top of the extruder is fed by the screw outwardly of the extruder through an outlet projected laterally outwardly from the extruder at a position adjacent the lower end of the screw. The extruder outlet constitutes a piston receivable with a cylindrical material chamber of an injection nozzle unit. Material is fed in one direction in incremental amounts from the extruder and into the material chamber when the extruder is moved in one direction relative to the injection nozzle unit, and is then forced from the material chamber by the extruder outlet and into the nozzle unit for injection into a mold when the extruder is moved in an opposite direction relative to the nozzle unit.

Abstract: A hot sprue valve assembly is provided for controlling flow of molten material into the mold cavity of an injection molding machine. The valve assembly is particularly designed for use with an injection molding machine for molding centrally apertured record discs, such as video information discs. The valve assembly includes a hot sprue bushing defining a heated flow path for passage of molten material toward a stationary dispersion head positioned centrally within the mold cavity. The dispersion head directs the molten material to flow in a generally radially outward direction with substantially uniform radial distribution into the mold cavity.

Abstract: A hot sprue valve assembly is provided for controlling flow of molten material into the mold cavity of an injection molding machine. The valve assembly is particularly designed for use with an injection molding machine for molding centrally apertured record discs, such as video information discs. The valve assembly comprises a stationary valve body supporting a movable valve member for sliding motion toward and away from the mold cavity. The valve member includes a hot sprue bushing defining a heated flow path for passage of molten material toward the mold cavity, and a dispersion head carried by the bushing for directing the molten material to flow in a generally radially outward direction through gate passages with substantially uniform radial distribution into the mold cavity. In one position, the valve member is advanced into the mold cavity to align the gate passages with the mold cavity and thereby permit flow of the molten material into the mold cavity.

Abstract: A stationary platen of an injection-molding machine, carrying a mold portion with a sprue leading to one or more cavities, is connected by a set of metallic tie bars with a fixed part of the machine frame containing the mold drive and is limitedly slidable on the machine bed to an extent corresponding to the stretch of the tie bars under a mold-clamping force exerted by that drive upon another platen moving along the tie bars. An injection unit behind the stationary platen has a precompression chamber which communicates with a channel leading to an injection nozzle, this nozzle being received in a cutout of that platen and confronting the sprue through the head of a hollow gating plunger slidable in the nozzle orifice.