Abstract: An injection nozzle for mixing heads of reaction molding machines is disclosed which comprises a housing in which a adjustment assembly is provided for slidably moving between two adjustable stops, wherein the adjustment assembly is configured as a control sleeve which includes a pressure chamber with a movable control piston disposed therein and the pressure chamber can be impinged upon by a pressure medium, for example hydraulic fluid and wherein a first stop is provided for the control sleeve and a second stop is provided for the control plunger thereby permitting an adjustment of two operating points that are exactly reproducible, so as to prevent disturbances during operation of the molding process.

Abstract: According to the present invention, a cross over nozzle is provided of two parts which, when joined, define a housing having a passage extending therethrough, a tapered valve seat extending about the passage and a valve member having a tapered valve head disposed in the passage for engaging the valve seat. The two parts are axially separable at an interface extending through the valve seat/valve head. In order to open the valve, both valve parts are first joined and then moved together as one member in the same direction relative to the housing axially away from the valve seat. Similarly, the valve members are jointly moved into engagement with the valve seat before the cross over nozzle is separated. Accordingly, unlike the valve gate design, the valve interface between the two parts of the valve head isn't exposed to molten resin and therefore molten resin isn't trapped therebetween to cause a string upon opening.

Abstract: A shutoff nozzle and valve assembly for gas-assisted injection molding having a nozzle body, a shutoff pin, a helical spring, a spring guide and a gas-injection valve assembly. The shutoff nozzle and valve assembly is a simple design including minimal components, thereby resulting in ease of maintenance and reduced cost. The nozzle assembly is self-actuating, using direct resin pressure to open the valve thereby enabling the flow of molten resin through the nozzle and into a mold cavity. After injection of the molten resin, the helical spring automatically engages the shutoff pin thereby closing the nozzle and valve assembly to prevent backflow. The gas-injection valve assembly is similarly self-actuating such that minimal operator supervision is required to operate the nozzle assembly.

Abstract: An injection molding apparatus including a manifold having a manifold melt channel, a nozzle having a nozzle melt channel, a slidable seal having seal melt channel located between the nozzle and the manifold melt channels, and a biasing element that provides sealing contact between the slidable seal and the manifold and nozzle to maintain a sealed melt path through the manifold, seal and nozzle melt channels.

Abstract: A system for generating a simulation of fluid flow in an injection molding process carried out by an injection molding machine having an injection unit for injecting the fluid into a manifold delivering the fluid to at least two injection ports leading to one or more cavities of one or more molds. The system comprises one or more programs containing a set of instructions that generate a calculated property, state, position or image of the fluid flowing into or through each cavity, the one or more programs using one or more variable inputs that are representative of one or more selected properties, characteristics or operating parameters of the machine or the fluid. The variable inputs include at least a first value indicative of a first fluid flow rate downstream of the injection unit leading to or through a first injection port and a second value indicative of a second fluid flow rate downstream of the injection unit leading to or through a second injection port.

Abstract: In an injection molding machine having upstream and downstream channels communicating with each other for delivering fluid material to one or more mold cavities, apparatus for controlling delivery of the melt material from the channels to the one or more mold cavities, each channel having an axis, the downstream channel having an axis intersecting a gate of a cavity of a mold, the upstream channel having an axis not intersecting the gate and being associated with an upstream actuator interconnected to an upstream melt flow controller disposed at a selected location within the upstream channel, the apparatus comprising a sensor for sensing a selected condition of the melt material at a position downstream of the upstream melt flow controller; an actuator controller interconnected to the upstream actuator, the actuator controller comprising a computer interconnected to a sensor for receiving a signal representative of the selected condition sensed by the sensor, the computer including an algorithm utilizing a v

Abstract: The present invention relates to an in-mold gate opening and closing mechanism in which it is easy to adjust the gate balance, more specially, in an in-mold gate opening and closing mechanism, in which a gate pin disposed in a gate in a mold is moved in line with resin pressure in the gate, the gate is opened by the gate pin escaping from the gate when the resin pressure exceeds an appointed pressure level when filling resin, and the gate is closed by the gate pin moving the gate direction when the resin pressure is lowered from the appointed pressure level when a filling of the resin is completed, wherein the gate is opened by a gate pin escaping from the gate when the resin pressure exceeds a pressing force of a spring adjusted by a mechanism for adjusting the spring pressure when filling resin.

Abstract: An injection molding apparatus and method for multi-layer molding of preforms and closures has a central melt channel, an annular melt channel radially spaced from the central melt channel, and an annular ring channel surrounding the central melt channel. The central melt channel has a first portion for flow of a first material, a second portion for flow of the first material and a second material, and a flow extension connecting the first portion and the second portion. The flow extension has a flow opening in communication with the annular ring channel for flow of the second material. The apparatus and method also include a cavity for receiving flow of the first material and the second material from the central melt channel, and for receiving flow of the first material from the annular melt channel. In addition, the apparatus and method include a melt passage having a first melt portion in communication with the central melt channel, and a second melt portion in communication with the annular melt channel.

Abstract: An injection molding apparatus and method for multi-layer molding of preforms and closures has a central melt channel, an annular melt channel radially spaced from the central melt channel, and an annular ring channel surrounding the central melt channel. The central melt channel has a first portion for flow of a first material, a second portion for flow of the first material and a second material, and a flow extension connecting the first portion and the second portion. The flow extension has a flow opening in communication with the annular ring channel for flow of the second material. The apparatus and method also include a cavity for receiving flow of the first material and the second material from the central melt channel, and for receiving flow of a third material from the annular melt channel.

Abstract: An injection molding apparatus comprises a first sprue bar element having a first sprue channel for receiving a melt stream of moldable material under pressure. A second sprue bar element has a second sprue channel for selectively receiving the melt stream from the first sprue channel. A manifold has a manifold channel for receiving the melt stream from the second sprue channel and delivering the melt stream to a nozzle channel of a nozzle. A mold cavity receives the melt stream from the nozzle. The nozzle channel communicates with the mold cavity through a mold gate. A first gate assembly is coupled to an outlet of the first sprue bar element for selectively restricting the flow of the melt stream from the first sprue channel. The first gate assembly is movable to restrict the flow when the flow of the melt stream between the first sprue channel and the second sprue channel is interrupted.

Abstract: A three piece, sliding ring valve for use in a plasticating screw and barrel arrangement has an extended life. The sliding ring has apertures for passing molten resin therethrough. The sliding ring also has annular contact surfaces for spreading the force driving the screw, thereby decreasing the pressure between the sliding ring and the valve retainer. The result is less valve wear and longer life.

Abstract: A valve-gate mechanism for use with gas-assisted plastic injection molding systems. A moveable pin mechanism is positioned in a bushing or machine nozzle to regulate the injection of plastic material into a mold cavity. The pin mechanism has an outer pin member and an inner pin member. Movement of the inner pin member relative to the outer pin member allows gas to be injected into the plastic in the mold cavity. A spring member, such as a Belleville washer, biases the inner pin member to a closed position relative to the outer pin member. Gas pressure from the gas source overcomes the force of the spring member allowing gas to enter into the mold cavity.

Abstract: The invention relates to a plasticizing unit in injection-moulding machines, in particular for processing thermoplastics, with a plasticizing cylinder in which a rotatable and axially displaceable screw is arranged, at the head of which a non-return valve is provided, which has an axially displaceable barrier sleeve which encloses with radial play a tapered region which belongs to a basic body fixed in the screw head and is present between blades and a stop ring. The basic body has at least three blades, in that supporting elements provided on the surfaces of the blades facing the barrier sleeve, wherein at least the supporting surfaces of the supporting elements are made of a hard-wearing material.

Abstract: The invention provides an injection molding method comprising supplying a gas into a molten resin in a plasticizing cylinder and injecting the molten resin having the gas dissolved therein, wherein when the resin is being plasticized, a gas space with a predetermined gas pressure is formed within the plasticizing cylinder in a gas supply section and the pressure at the front end of the screw is adjusted to be at least equal to the gas pressure in the gas space and within a range where the gas space can be maintained within the plasticizing cylinder in the gas supply section. According to the invention, the necessary amount of gas can be dissolved in the molten resin with good reproducibility in a quantitative manner.

Abstract: An improved positive control non-return valve assembly which is mounted on the front end of a helical plasticating screw of an injection molding machine. The valve assembly comprises a thread retainer with means for attachment to the plasticating screw. The valve assembly also comprises a distribution chamber that has an annular shaped flow gap and a cylindrical passageway that leads to a plurality of discharge ports. The non-return valve assembly forms a seal, builds pressure, and displaces molten plastic fluid from the distribution chamber through a discharge chamber passageway, and into a mold.

Abstract: A sliding ring non-return valve primarily for use with an injection molding machine utilizes a frame having cut therein one or more longitudinal grooves. Material flows around the outer edge of a flange surface, into an inlet area, and through the longitudinal grooves in the frame's outer surface before entering an accumulation volume. A ring, dimensioned to fit slidably around the frame, blocks material flow into the grooves while in an upstream position and allows material to pass through the grooves while in a downstream position. In an alternative embodiment, the non-return valve utilizes a frame that surrounds a central passage accessed by inlets. The outlet passage is located downstream of said inlet and connects the central passage with an accumulation volume. A ring is dimensioned to slidably fit around the frame. A flange surface limits the ring's upstream travel, while grooves in the flange surface throttle, or limit, material flow into the inlet area.

Abstract: The invention relates to a non-return valve, which is situated at the end of a plasticizing and injection screw to control the flow of plastic melt from the region of the screw channels of the plasticizing and injection screw to the region of the space in front of the screw of a preplasticizing cylinder, where the plasticizing and injection screw is situated, the non-return valve having a basic body, which is rigidly connected to the plasticizing and injection screw, and an outside part, which can move translationally and preferably also rotationally relative to the basic body, so as to allow the flow of plastic melt in a first position and block the flow of plastic melt in a second position.

Abstract: An extruder assembly for an injecting moulding machine in which the screw point pin has a small diameter that can float and is self-centering. The pin has two support points or flats. The screw point and pin are used as a check valve in front of the piston screw of an injection molding machine for plastic materials. As a result of the small diameter of the pin the total output of plastified material is not diminished and there are no head losses. The screw point can be adapted to any models of injection molding machine, and its technical advantages give it high performance both in the field of what are known as “technical” molded parts and in the field of high-speed packaging.

Abstract: A sliding ring non-return valve primarily for use with an injection molding machine utilizes a frame having cut therein one or more longitudinal grooves. Material flows around the outer edge of a flange surface, into an inlet area, and through the longitudinal grooves in the frame's outer surface before entering an accumulation volume. A ring, dimensioned to fit slidably around the frame, blocks material flow into the grooves while in an upstream position and allows material to pass through the grooves while in a downstream position. In an alternative embodiment, the non-return valve utilizes a frame that surrounds a central passage accessed by inlets. The outlet passage is located downstream of said inlet and connects the central passage with an accumulation volume. A ring is dimensioned to slidably fit around the frame. A flange surface limits the ring's upstream travel, while grooves in the flange surface throttle, or limit, material flow into the inlet area.

Abstract: An injection molding method, an injection mold and a valve gate device, in which a movable pin moves easily, without excess force being exerted thereto, to properly open and close a gate. Closing a gate 10B by a cylindrical movable pin 27 allows excess resin to easily return back to a resin conveying path side through an outer edge portion at the end of the movable pin 27, so that even a large-diameter gate 10B can be reliably closed by the movable pin 27 which can be easily moved due to reduced resin resistance on the movable pin 27.

Abstract: A backflow blocking arrangement is for an injection unit of an injection molding machine having a plasticising screw with a front end for carrying the backflow blocking arrangement. The arrangement has a screw tip, a blocking bush and a blocking sleeve each with a base body material. The screw tip has friction surfaces and the blocking bush and the blocking sleeve each have sealing and friction surfaces. At least one of the friction and sealing surfaces is formed by a protective layer made of a fusion metallurgical compound of the base body material plus an additive. The additive is any one or more of a metal, a carbide, a carbonitride, a boride, a carboboride, a silicide, a sulfide or an oxide. The screw tip includes a mixed layer between its base body material and its outer layer, that includes the additive. The mixed layer is thinner than the outer layer and both the outer layer and the mixed layer include base body material in specific proportions with the additive.

Abstract: A back-flow prevention apparatus is composed of a screw and a platelike closing member. The screw includes at least a metering portion having a groove formed thereon for advancing a resin. The closing member is brought into an open position state by resin pressure which is developed behind the closing member in association with metering, thereby establishing communication between the groove and a space located ahead of the screw. The closing member is brought into a closed position by a restoring force of an elastic material, thereby shutting off communication between the groove and the space located ahead of the screw. Upon completion of a metering step, the restoring force brings the closed position into the closing state to thereby shut off communication between the groove and the space located ahead of the screw. Accordingly, sealing can be completed before the start of an injection step.

Abstract: An injection press apparatus for molding/joining separate parts. The apparatus having a work table with first and second work stations for injecting material into a mold. A movable extruder/injection assembly is provided which has an extruder portion for extruding material, and an injection portion for injecting material. The extruder portion and injection portion are in fluid communication such that material is provided from the extruder portion to the injection portion prior to injection of material from the injection portion to the mold. The injection portion of extruder/injection assembly has a nozzle assembly for receiving and injecting material from the injection portion to a self-actuating mold clamp assembly at the first or second work stations. The first and second work stations support the mold clamp assembly which receives the molding material. The extruder/injection assembly is movable between the first and second work stations by a shuttle assembly.

Abstract: The invention concerns an injection molding device which has an injection unit (1) comprising an injection cylinder (20) and an injection piston (10) travelling inside it. The injection cylinder can be filled via a filling channel (12) arranged in the injection piston and can be emptied via an outlet opening (24) in the injection cylinder. An opening (14) in the filling channel (12) is spatially and/or thermally seperated from the outlet opening (24). Thus there exists the possibility of the complete vulcanization of the material in the outlet opening.

Abstract: A reciprocating screw for an injection molding machine includes a heating extruder barrel in which the reciprocating screw is mounted rotatably. The barrel has an extruder head and a tail portion. A hopper is coupled with the tail portion of the barrel for feeding plastic granules into the barrel via the hopper. The screw is capable of rotating in the barrel so as to move the plastic granules from the tail portion to the extruder head, thereby melting gradually the plastic granules in the barrel to form a molten plastic material in the extruder head, and extruding the molten plastic material from the extruder head. A check valve is disposed in the extruder head to prevent return flow of the molten plastic material in the extruder head.

Abstract: A back-flow prevention apparatus includes a screw which includes a metering portion and a screw head; a seal ring which is removably disposed on a rear portion of the screw head and which has a first resin passageway formed therein; a back-flow prevention ring which is disposed on a front portion of the screw head in such a manner as to be rotatable with respect to the seal ring and which has a second resin passageway formed therein; and a drive unit for selectively rotating the screw in a regular or reverse direction. A first positioning mechanism is disposed between the screw head and the seal ring and adapted to position the seal ring at a predetermined position with respect to the screw head.

Abstract: The invention relates to a valve nozzle used for a molding machine of synthetic resin and is characterized in that a gate opening and closing mechanism consisting of a spool having a head portion at which a circular cross-sectioned part and a notched part are formed, a shaft portion and an arrow feather shaped projection, and a coil spring which presses the abovementioned spool in the direction opposite to the gate, is disposed in the interior space of a nozzle head attached to the tip end of a nozzle holder via a screw mechanism, when resin pressure is less than a certain fixed level, the abovementioned spool is pressed by the abovementioned coil spring in the direction opposite to the gate and the entire periphery of the circular cross-sectioned portion of the head portion of the spool is brought into contact with the interior wall of the gate of the nozzle head to cause the resin flow path to be closed, and when the resin pressure becomes higher than a certain fixed level, the head portion of the abovement

Abstract: A shut-off valve is mounted between an injection nozzle and a mold. The valve has a piston within the valve body, A material passage is formed through the piston having an exit aperture and a terminal end. When material is injected through the material passage, the piston is forced to a downstream position which allows the material to flow into the mold. A pneumatic pressure applied to the piston forces the piston to a closed position after injection.

Abstract: An injection plug device for injecting concrete repairing agent into a concrete structure and a connector to be connected to such an injection plug device are provided. The injection plug device has a small diameter, a simple structure, and low manufacturing cost to be appropriate to be used as a disposable device.

Abstract: A screw head device 1 for an injection molding machine includes a ring valve 3 set on a stem portion 2 of a screw head for movement in back and forth direction and for defining a rear side resin passage Rr between its own inner peripheral surface and the stem portion 2, a front side resin passage Rf extending axially and communicated with the rear side resin passage Rr, and a surge preventing mechanism, in which the front end of a screw main body Sm acts as a valve seat for mating with the rear end face of the ring valve 3. At a rear side of the head portion 4, a spacer guide 6 is provided. The outer peripheral surface 6s of the spacer guide 6 is located radially inside of the outer peripheral portion 4s of the head portions end racially outside of the bottom portion Rfd of the front side resin passage Rf.

Abstract: An apparatus and method for injection molding of thermoplastics has elements and steps comprising mating mold components having multiple mold cavities with flow passages and a plurality of conduits connected to the mold cavities so that thermoplastic can flow into the cavities. A plurality of flow control members are mounted relative to the mold and to corresponding conduits to be moved to regulate the flow of plastic through corresponding conduits into corresponding cavities to allow for controlling the rate of thermoplastic flow among the cavities. The flow control member can each have a first member movable into its corresponding conduit, and a second adjusting member movable to engage and move the first member. A biasing member can be provided to bias the first member relative to its corresponding conduit. The control members can be inserted to varying degrees within their corresponding conduits to control thermoplastic flow rate among the mold cavities.

Abstract: An injection molding apparatus comprising an injection unit having a plurality of injection nozzles of which respective distal end portions move back and forth between a first position and a second position, a mold clamp unit comprising a first mold clamp unit having a first frame body and an upper mold, a second mold clamp unit having a second frame body and a lower mold. A plurality of nozzle reception portions to which the distal end portions of the injection nozzles fit respectively are formed in one of the first and second frame bodies, and a resin introduction passage for introducing the molten resin from central portions of the plurality of nozzle reception portions to a plurality of cavities formed between the upper mold and lower mold as they are clamped is formed. The plurality of injection nozzles are mounted to the injection unit so as to permit the respective distal end portions to move loosely in any direction in response to an external force applied thereto.

Abstract: A method of injection molding of workpieces, formed of at least two different layers, and which includes forming at least one layer from lacquer, with the apparatus for effecting the method including at least two injection molding devices for forming melts of lacquer and non-lacquer materials and an injection unit communicating with the two devices for injecting the two melts into a mold cavity of a mold.

Abstract: A penetration hole of plasticized resin is pierced in a screw head, so that the resin may be accumulated in uniform temperature distribution without sacrificing the function of the injection screw. More specifically, a penetration hole 15 of plasticized resin is pierced inside a screw head 13 at the front end of a screw 12 from the front middle to the rear periphery so as to communicate between the screw peripheral parts and the screw head front space. A ring valve 17 for opening and closing a rear opening 15a of the penetration hole 15, and closing the gap around the screw head is fitted to the rear periphery of the screw head 13 so as to be free to move back and forth.

Abstract: An improved hot tip (40) for forming a thermoplastic body having a mold cavity (42) and a gate portion (44) has an elongated body member (46) and a channel (48) passing axially through the body member (46). The channel (48) has an inlet end (51) and outlet end (52) for passing a molten material, such as an amorphous resin, therethrough. The body member (46) has a necked-down portion (54) surrounding the outlet end (52) of the channel (48). The necked down portion (54) is configured to permit the outlet end (52) of the channel (48) to proximately contact the gate portion (44) of the mold cavity (42) resulting in a formed body having vestigeless gate.

Abstract: A non-return valve (10) primarily for use with an injection molding machine utilizes a frame (12) which surrounds a first bore (34) and a second bore (32). The second bore (32) is accessed by inlets (30). Outlet passages (40) are located downstream of said inlet (30) and connect second bore (32) with an accumulation area (6). A piston (60) is dimensioned to slidably fit within the first bore (34) and extend into the second bore (32). In a downstream position, the piston (60) allows positive flow of material from the inlet (30) to the outlet (40). In an upstream position, the piston (60) positively blocks flow of material from the inlet (30) to the outlet (40). The piston (60) can be forced to its upstream position at the beginning of the injection step or can be preclosed by eliminating rearward movement prior to injection.

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

Abstract: An improved check valve assembly which is mounted on the front end of a feedscrew of an injection molding machine has 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 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. A compression coil spring is telescopically mounted on the retainer shank and is located within the annular-shaped flow gap and biases the check ring toward the material block position to provide a positive valve shut-off irrespective of the viscosity of the heated material.

Abstract: An apparatus and method for controlling thermoplastic mixing in a plastic extrusion machines used for injection molding, blow molding or other reciprocating molding process. The plastic extruder having a rotating helical screw within a cylindrical shell with an automatic shut-off and mixing valve secured to the helical screw at the downstream end of the screw. The automatic shut-off and mixing valve includes a unitary valve body with a poppet. A plurality of mixing groove pairs are arranged extending substantially longitudinally on the surface of the valve body. Select angular bores extend from the groove pairs to the poppet. The poppet is axially movable within and rotatable relative the valve body. The poppet has an axial stem extending into a longitudinal axial bore within the valve body. An elastic means is positioned on the rearward end of the poppet maintaining the valve in a normally closed position against a seating surface of the valve body when there is no rotation of the helical screw.

Abstract: A magnetic plastic rotor disk manufacturing apparatus, includes an injection device for injecting a magnetic plastic material containing a synthetic resin matrix and a magnetic powder; a mold for molding the magnetic plastic material injected thereinto from the injection device, and a device for generating a magnetic field and magnetizing the magnetic powder in a direction along a diameter of the magnetic plastic rotor disks. The mold includes a three-plate type mold constructed of two retainer plates and a single runner stripper plate. One of the retainer plates is formed with a plurality of pin gates corresponding to the cavities so as to supply the magnetic plastic material through the pin gates into the cavities.

Abstract: An injection molding ring valve assembly, having a concentrically disposed axially translatable center valve body member which when in a first axial position allows mass flow through the valve assembly and a separate front valve seat member in the shape of a torus in cooperation with a check ring, thereby providing smooth and unrestricted annular flow through the valve assembly during the priming process of the injection sequence. The check ring, formed from a cylindrical outer ring disposed about the center valve body member, sealingly engages an outer valve seat portion of the torus or front valve seat member. The torus further includes a center hub portion and at least one radially projecting web portion connecting the hub portion and the annular outer portion, resulting in one or more substantially axial semi-annular openings for the smooth and unrestricted passage of molding material.

Abstract: A flow regulating assembly for restricting plastic material from flowing directly from a central chamber of an injection piston to an accumulator cavity of a plastic injection machine and instead directing the plastic material towards the wall of the accumulator cavity thereby providing a scouring effect and reducing build-up of the plastic material on the wall of the accumulator cavity. The flow regulating assembly includes a valve member having a central opening located proximate to and in corresponding alignment with the central chamber of the injection piston and four branch passageways extended from the central opening of the valve member to external openings in a circumferential groove in an outer edge of the valve member, the outer edge of the valve member which is concentric with and proximate to the wall of the accumulator cavity. Four channels are located on a conical-shaped head portion of the valve member proximate to the circumferential groove.

Abstract: A needle shut-off nozzle for plastic injection moulding compounds with an internal chamber for a spring acting on a shut-off nozzle has a basic body. The end of the shut-off needle (11) facing the spring (7) is designed as a cylinder (12) which is closed on the end facing the tip of the needle. The cylinder (12) engages an opposing cylinder (13), designed as a hollow cylinder, in sliding fashion, producing a sealing effect.

Abstract: A pressure transducer for an injection molding machine includes a housing coupled to a nozzle of an injection molding machine. A hollow stress tube, attached to the housing, through which molten material of the injection molding machine flows, bellows in response to pressure from the material. An outer ring having an opening is coupled to the stress tube such that the outer ring expands, causing displacement of the outer ring about the opening, when the stress tube bellows. A displacement sensor is included for determining the displacement of the outer ring about the opening. This displacement is directly proportional to the pressure of the material. In this manner, the pressure transducer determines the pressure of the molten material.

Abstract: Valve gated injection molding apparatus with a spring mounted on a central pin adjacent the head of a valve member in a spring chamber in each of the pistons. The spring is compressed between the base of the pin and the cap of the piston to preload it. When the valve member and piston are driven forwardly to the closed position, the head of the valve member retracts somewhat into the spring chamber against the force applied forwardly against the head of the valve member by the spring. This cushions the impact of the front end of the valve member in the gate and provides for tight seating of the front end of the valve member in the gate without requiring all of the components to be made to precise tolerances with exact allowance for thermal expansion. The spring is a number of selected disc springs stacked in sets facing in opposite directions, from which the force applied to the head of the valve member is predetermined.

Abstract: A mold for hollow injection molding has an inlet for admitting a fluid into the molten resin when injected to form an interior hollow in the molded product. The inlet is opened and closed by retraction and advancement of a movable pin having at least a portion to fill the inlet and close it. When the inlet is closed, while the resin is being injected, the pin has a portion which projects out of the inlet into the space where the resin is injected. When the inlet is opened, the retraction of the pin leaves a short passageway in the injected resin leading from the fluid inlet for flow thereinto of the hollow-forming fluid. Preferably, the pin is stepped with an inlet-closing large rear portion and a smaller projecting forward portion which is located in and has an annular clearance with the inlet when it is open. The pin may be detachably connected to a movable plunger, operated by fluid or spring pressure, to enable replacement by pins of different lengths, sizes, etc.

Abstract: An improved nozzle for gas-assisted injection molding and a method of gas-assisted injection molding using the improved nozzle are provided. This improved nozzle employs a very simple design to vent the gas from the mold cavity once the plastic article has cooled sufficiently to be self supporting. In one especially preferred embodiment of this invention, the improved nozzle contains a separate plastic shut-off valve, a separate gas inlet passage with a check valve, and a separate gas venting passage containing a movable pin. Venting of the pressurized gas occurs by movement of the movable pin so that the pressurized gas can burst through the thin layer of plastic material covering the gas venting passage. The improved nozzle design and method allow for almost continuous operation with minimal operator attention to the nozzle.

Abstract: A positive-type, non-return valve (10) primarily for use with an injection molding machine utilizes a frame (12) which surrounds a first bore (34) and a second bore (32). The second bore (32) is accessed by inlets (30). Outlet passages (40) are located downstream of said inlet (30) and connect second bore (32) with an accumulation area (6). A piston (60) is dimensioned to slidably fit within the first bore (34) and extend into the second bore (32). In a downstream position, the piston (60) allows positive flow of material from the inlet (30) to the outlet (40). In an upstream position, the piston (60) positively blocks flow of material from the inlet (30) to the outlet (40). The piston (60) can be forced to its upstream position at the beginning of the injection step or can be preclosed by maintaining back pressure on the screw (2) prior to injection.

Abstract: A screw head is composed of a cone portion, a tapered portion formed behind the cone portion and a narrow portion formed behind the tapered portion. A counter-flow stopper ring is provided around the narrow portion so that an annular resin passage is formed between the counter-flow stopper ring and the narrow portion. The tapered portion of the screw head has a plurality of circumferentially spaced grooves. The sectional area of each groove decreases from the inner circumference toward the outer circumference of the tapered portion. The grooves are so formed that the resin flowing through the grooves creates a force which pushes the counter-flow stopper ring backward, the ring being moved forward by forward flow of resin caused during backward movement of the screw. Thus, the grooves help maintain a gap between the counter-flow stopper ring and the screw head.

Abstract: An injection mold for use with a molding press has four mold levels in axially stacked relation, permitting a substantial doubling of output for a given size of press as compared with a back-to-back two level stacked mold. The mold feeder flow path extends axially from the injector head to a flow distribution block located at the center of the stacked mold block series. The centrally located distribution block is connected, in use isolation, sealed relation with the injector head, being axially displaceable therefrom in continuing sealed relation upon the opening of the mold. A drool prevention valve system, located at two of the mold interfaces, to preclude drooling of fluid plastic stock upon opening of the molds includes pressure fluid actuators for operating the valves, wherein the pressure fluid may comprise the fluid plastic stock.