Abstract: A method and apparatus for runnerless injection molding of plastic materials utilizing a novel valve stem for controlling the opening and closing of at least two gates in a single injection nozzle The method and apparatus includes at least two separate melt streams whose flows are not obstructed by the valve stem. These melt streams may contain the same plastic material or different plastic materials and the injection nozzle may be either simultaneously or sequentially activated for filling the mold cavity.

Abstract: An injection molding apparatus is provided in which the rate of material flow during an injection cycle is controlled. According to one preferred embodiment, an injection molding apparatus is provided that includes a manifold having an inlet for receiving material from an injection molding machine, at least one injection nozzle coupled to the manifold, an actuator, and a valve pin adapted to reciprocate through the manifold and the injection nozzle, the valve pin having a first end coupled to the actuator, a second end that closes the gate in a forward position, and a control surface intermediate said first and second ends for adjusting a rate of material flow during an injection cycle.

Abstract: A method and system of operating a two stage injection molding machine wherein movement of the injection plunger in the shooting pot is coordinated with movement of the plasticizing screw and melt flow into the shooting pot such that the plunger provides minimal resistance to the melt flow into the shooting pot while avoiding the production of voids or air inside the melt. The undesired shear forces to which the melt is exposed are thus reduced, correspondingly reducing the melt degradation products which would otherwise result.

Abstract: An injection nozzle for injection molding machines with a valve system having a piston movably positioned around the top end portion of a nozzle body. A guide slot is formed at the top end portion of the nozzle body, and movably receives a pin actuating bar, integrated with a valve pin-of the valve system, and so the pin actuating bar is vertically and precisely movable under the guide of the guide slot. The valve pin is thus precisely movable in the nozzle body in a linear vertical direction without failure. The nozzle is also preferably used for producing large-scaled products or small-scaled products, thus have an improved compatibility. The nozzle is preferably used in a stack molding process. In addition, even when a manifold thermally expands due to a high temperature molten plastic material and is undesirably changed in position, the valve system is continuously operated without being stopped, thus allowing the injection molding process to be continued for a lengthy period of time.

Abstract: An improved injection molding nozzle shows a high hardness and is chemically stable so that the inner surface thereof is not corroded nor the gas or the fluid forced to penetrate into the gap between the injection molding nozzle and the valve pin seize the valve pin regardless of the temperature and the pressure of the material to be injected. Additionally, the valve pin is not pliable and does not give rise to a collapse on the part of the valve pin. The injection molding nozzle to be used for resin and molten metal is characterized in that it is made of a ceramic material and at least part of the outer periphery is covered with metal.

Abstract: Molding of relatively large articles such as automobile body parts by gas-assisted injection molding with sequential gating of injected thermoplastic resin into the mold cavity. Elongated ribs in the parts form gas channels and strengthening ribs for the parts. Structural parts are made by adhesively joining two such parts made by gas-assisted injection molding through a combination of hollow ribs and joining flanges at sides of the parts.

Abstract: An injection molding machine, and stack assembly, employing a novel mold gate insert that can decrease the cycle time of the machine, and crystallinity and other defects in the mold gate area of plastic articles. A mold gate insert is described that is formed in two pieces. A first portion of the insert can forms a gate land for valve gated machines, and can thermally shield the nozzle tip. This first portion is made of a wear resistant material having a relatively low thermal conductivity, such as H13 tool steel. A second portion of the insert forms a section of the mold cavity and is made of a relatively highly thermally conductive material, such as beryllium copper. During the cooling phase of the injection cycle, the second portion provides rapid dissipation of heat to cool the section of the mold cavity, while the first portion creates a thermal barrier to shield the nozzle tip from the cooling of the second portion.

Abstract: The hot-runner coinjection distributor block arrangement comprises several block parts (6, 7) which with the help of heating elements (8) may be brought to differing temperatures. These block parts (6, 7) are spaced from one another with an intermediate piece (9) and are supported via a support element (10) on the head plate (2). In this support element (10) spring elements, preferably a disc spring (11) is incorporated, which spaces the support element (10) from the head plate (2) and press the two block parts (6, 7) onto one another also in the cold mode. In the hot mode these disc springs (11) permit an axial expansion of the block parts (6, 7) and reduce the tension force exerted onto the support element (10). Peg-like formations of the intermediate piece (9) and of the support element (10) ensure that the bores for the guiding of the closure needle or of the feed channel (13) by the thermal expansion of the block parts (6, 7) are retained, i.e. are not laterally displaced.

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 injection moulding machine has a plasticizing cylinder, arranged in whose interior there is a worm with an axial through-hole. The interior of the plasticizing cylinder is connected to a nozzle opening via a cylinder chamber. Operating in the cylinder chamber is a needle which extends through the through-hole in the worm and has a smaller diameter than the cylinder chamber. The tip of the worm constitutes, together with a correspondingly shaped sealing seat, a reverse flow barrier during the injection process. After the end of the injection process the worm is rotated and conveys plasticized plastic material in the direction towards the nozzle opening. As a result of the rising pressure in the worm threads the worm is pushed back and the plasticized material can penetrate into the annular space between the needle and the cylinder chamber. When the worm is rotated further, a pressure is also created in the annular space which slides the needle back into its starting position.

Abstract: A mold bushing for injecting plastic material into a mold cavity. The bushing member has a one-piece body member with a central passageway for a shut-off gate pin member and a separate and distinct passageway for the molten plastic material. A tip member is positioned on the end of the body member and has a material discharge chamber. A gate or orifice opened and closed by the pin member is positioned either in the tip member or the mold. A wear bushing member is positioned in the discharge chamber or the end of the body member and acts to support the end of the pin member and prevent the flow of plastic material into the central passageway. The body member is heated by an annular cast heater member or the like. The wear bushing member can be indexed for proper positioning relative to the body member and the plastic flow passageway. The wear bushing member preferably has a body portion which partially fills the discharge chamber in the tip member.

Abstract: Valve gated injection molding apparatus having several valve pins (62) extending through each heated nozzle (12) driven by a common actuating mechanism (70). A valve bushing (100) is seated in the front end (96) of each heated nozzle (12). A central melt bore (50) in each heated nozzle (12) splits in the valve bushing (100) near the front end of the heated nozzle (12) from where the melt flows around each of the valve pins (62) to the gates (66).

Abstract: A hot runner valve gated injection molding device which directs melt from a melt channel to a melt cavity, including a guide sleeve positioned at the gate end of the nozzle body and surrounding the valve stem to guide the valve stem inside the guide sleeve and to provide a sealing device at the gate end of the nozzle body.

Abstract: A food product molding machine of the type utilizing a hydraulically driven feed ram to move food product into the cavities of a reciprocating mold plate includes a ram speed control system operated with a pump supplemented by variable flow control from an accumulator. The system also includes a feed ram pressure release feature at the end of each mold plate fill cycle to reduce component wear and improve product quality.

Abstract: At least one mold is provided having a mold cavity and a mold gate communicating with the mold cavity, an injection nozzle for feeding molten plastic material to the injection mold having a nozzle outlet in line with the mold gate, and a thin movable valve gating arrangement positioned between the mold gate and nozzle outlet having an orifice therein permitting and shutting off flow of molten plastic from the nozzle to the mold.

Abstract: A novel valve gated injection molding system and valve gate reduces the formation of gate vestiges on parts molded therewith and enhances cooling of the tip of the valve stem during the cooling portion of an injection molding cycle. Channels are provided and extend from an area adjacent the contact area of the sealing portions of the stem tip and gate to the melt channel of the injection nozzle. These channels allow material, which would otherwise form a thin film layer in the contact area of the sealing portions of the stem tip and gate, to be expressed through the channels and back to the injection nozzle. As the formation of thin films is inhibited, an increased contact area, in addition to the contact area of the tip and gate sealing portions, can be provided to improve the transfer of heat energy from the tip to the gate when the gate is cooled.

Abstract: Multi-layer injection molding apparatus having integral multi-layer melt dividing bushings seated in the melt distribution manifold for dividing a first melt passage extending to annular melt channels in heated nozzles. Matching melt channels machined in the front face of the first layer and the rear face of the second layer of each melt dividing bushing form a melt conduit which branches from an inlet to two spaced holes extending through the second layer. A pair of matching melt channels machined in the front face of the second layer and the rear face of the third layer of each melt dividing bushing form two melt conduits, each of which branch from one of the holes through the second layer to two of four spaced holes through the third layer. The four holes through the third layer align with four melt bores leading to the annular melt channel in one of the heated nozzles. A second melt passage may extend through a central bore in each melt dividing bushing to a central melt channel in the heated nozzle.

Abstract: A multi-cavity coinjection mold having a relatively large plurality of cavities for simultaneously molding a relatively large plurality of multi-layered articles including a) a plurality of cavity groups each defining a relatively small plurality of said cavities, a single balanced hot runner for supplying said relatively small plurality of cavities with contiguous different plastics materials, and a valve for sequentially supplying desired contiguous quantities of the plastics materials from plastics material sources, common to all of said groups, to the balanced hot runner; and b) a hot runner manifold system connected to the plastic material sources to supply the plastic materials to all of the valves; and related methods.

Abstract: A hot sprue bushing is provided for transporting plasticized material from an injection nozzle to a mold cavity while controlling the temperature of the plasticized material. This hot sprue bushing comprises an elongate body having a head, a stem and a distal end portion, and a through passage extending therethrough from end to end through the head, stem and distal end portion of the body for transporting plasticized material through the hot sprue bushing from the heat to the distal end portion thereof. The distal end portion of the body bears a first engaging device, and the head of the body is of greater cross-section than the stem so that the head provides a first abutment surface extending outwardly of the stem. An electrically powered heater is wrapped around the stem of the head in heating conducting relationship therewith.

Abstract: A multilayer injection molding machine manufactures a molded product formed of a plurality of layers of resins or colors by press fitting resins from a core layer injection unit and a skin layer injection unit to a cavity part formed by pressing and clamping a moving metal mold to a fixed metal mold fixed to a support member. The multilayer injection molding machine is formed by integrating a connecting device body interposed between the fixed metal mold and the support member so as to support the fixed metal mold to the support member and an injection unit connecting device provided on the connecting device body and having a plurality of resin passages allowing the cavity part to communicate with each injection unit.

Abstract: Sprue gated injection molding apparatus for molding preforms or other products having two layers of a barrier material such as EVOH or nylon alternating between three layers of another thermal plastic material such as PET. The PET is injected by one injection cylinder into first and third melt passages which branch in a front melt distribution manifold to extend to a number of heated nozzles. The first melt passage extends through a central melt channel in each heated nozzle and the third melt passage extends through an outer annular melt channel surrounding the central melt passage to an aligned gate leading to a cavity. The barrier material is injected by another injection cylinder into a second melt passage which branches in a rear melt distribution manifold to extend to an inner annular melt channel extending between the central melt passage and the outer annular melt channel in each heated nozzle.

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 valve gating apparatus and method for injection molding includes at least one shutter disposed between the gate and the cavity melt channel into a mold cavity. The shutter is moved laterally, between a closed position wherein flow of melt from the nozzle into the cavity is inhibited, and an open position wherein flow of melt into the cavity is unimpeded by the shutter. Intermediate these two positions, the shutter can be employed to reduce the cross sectional area of the gate to throttle the gate. Embodiments are disclosed wherein one shutter or pairs of shutters are employed to gate the gate. Further, when pairs of shutters are employed, the shutters can abut each other in the close position or can overlie each other. This novel design prevents generation of waste material and eliminates the need to have devices for removing cold plugs.

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: Multi-layer injection molding apparatus having integral melt transfer and dividing bushings extending from a rear melt distribution manifold through openings in a front melt distribution manifold to aligned heated nozzles. Each bushing has two or three integral layers which are drilled and machined to have melt holes through them connected to melt conduits between them which divides one melt flowing from the rear melt distribution manifold to several bores extending to an annular melt channel in the aligned heated nozzle. In some embodiments, the bushing can also divide a second melt flowing from the front melt distribution manifold to another annular channel in the aligned heated nozzle.

Abstract: To avoid generation of air bubbles and silver which otherwise may be caused due to forced retraction of a dwelling plunger after a dwelling cycle is completed. A dwelling cycle is performed at the same time of metering by using an injection machine 1 and a dwelling machine 2. The injection machine 1 comprises an injection screw 11 mounted in a heating cylinder 12. The dwelling machine 2 comprises a dwelling plunger 21 slidably mounted therein and faced to a resin passage 14. An advancing motion of the dwelling plunger 14 is limited to the side surface of the resin passage while a backward movement of the dwelling plunger is limited to a position at which a desired volume of a resin trap 26 is formed for the resin to be packed in the passage between the head of the plunger and the resin passage 14. The dwelling plunger 21 is allowed to be in a free state during an injection cycle or the metering.

Abstract: A valve-gated injection moulding device in which an actuating device of the valve pin comprises a sliding member having its walls in sliding engagement with an axial guide track. The sliding member comprises a radial opening defined by an upper and a lower contact surface. A free end of an actuating lever having two curved actuating surfaces extends radially into the opening of the sliding member. Thanks to this construction, a compact and accurate actuating device is provided which reduces radial forces on the valve pin, such that it can be operated without friction or wear. Residual radial forces are taken up by the sliding member. The stroke of the actuating device can be adjusted after mounting in a cavity plate of an injection moulding device.

Abstract: A method is disclosed for making a multi-layer up molded article.

Abstract: A gas injector including a tube extending into the hollow enclosure of a housing. The hollow enclosure of the housing is connected with gas pressure. The outside end of the tube being extendable into the cavity of a plastic material injection mold. That end of the tube defines a valve seat. A valve is seatable on the seat. A rod on the valve extends through the tube into the hollow enclosure of the housing. A spring in a cup shape support normally urges the rod to move the valve onto the valve seat. A solenoid plunger acting on the rod and activated by an electromagnet moves the rod against the spring to raise the valve off the valve seat.

Abstract: A multi-cavity coinjection mold having a relatively large plurality of cavities for simultaneously molding a relatively large plurality of multi-layered articles including a) a plurality of cavity groups each defining a relatively small plurality of said cavities, a single balanced hot runner for supplying said relatively small plurality of cavities with contiguous different plastics materials, and a valve for sequentially supplying desired contiguous quantities of the plastics materials from plastics material sources, common to all of said groups, to the balanced hot runner; and b) a hot runner manifold system connected to the plastic material sources to supply the plastic materials to all of the valves; and related methods.

Abstract: A valve gated injection molding system to facilitate improved melt flow to the gate of the nozzle. The system includes an annular flow insert through which the valve pin passes. The annular flow insert includes an annular groove on its outer surface. The edge of the annular groove is spaced from the wall of the melt channel so that some of the melt can flow longitudinally between the edge of the groove and the wall, while the remainder of the melt flows in the groove. The flow direction initiated by the annular flow insert eliminates flow separation and dead spots about the valve pin. The system also includes an actuator assembly including a sled attached to the valve pin.

Abstract: Valve gated injection molding apparatus having three position valve member actuating mechanism for multilayer molding. A first melt passage extends to the gate through an annular channel in a heated nozzle, while a second melt passage extends around an elongated valve member in a central melt channel. A rack member engaging the rear end of the valve member is driven by a pinion member connected to a front piston in a front cylinder. A rear piston in a shorter rear cylinder aligned with the front cylinder has a stem extending forwardly into the front cylinder. First, air pressure applied behind the rear piston retracts the valve member from a first closed position to a second partially open position wherein melt flows only through the annular channel. Then, air pressure applied behind the front piston retracts the valve member to a third fully open position wherein melt flows simultaneously through both melt channels to provide the three layers.

Abstract: A method and apparatus for the manufacture of optical polymer contact lenses in a closed mold, where a mold cavity is created between a front curve insert and a back curve insert, the side walls of the mold cavity being formed by the inner wall of a movable annular gate collar, the collar being positioned in a retracted position during polymer dosing and then moved prior to polymer cure into an extended position to complete the mold cavity and to separate the polymer curing inside the mold cavity from any waste polymer outside of the mold cavity.

Abstract: A multi-cavity coinjection mold and method for simultaneously producing a plurality of multi-layered articles comprising: a mold structure defining a plurality of mold cavities; a first supply source for supplying metered amounts of a first molding material; a second supply source for supplying metered amounts of a second molding material; a hot runner system in communication with the first and second supply sources for conveying the metered amounts of the first and the second materials separately to a region proximate each of the cavities; a valve mechanism per cavity for receiving the metered amounts of the first and second materials from the hot runner system and for sequentially supplying desired quantity of the first and second materials contiguously to each cavity.

Abstract: A valve gate injection nozzle includes a valve stem for guiding molten resin to a molding area. The valve stem includes an input area for receiving the molten resin, a central area following the input area for processing the molten resin and an output area following the central area for connection of the nozzle with the molding area. The central area includes a first zone for splitting the molten resin into a plurality of streams, a second zone for mixing and homogenizing the molten resin, and a third zone for combing the plurality of streams and forming recombined molten resin for subsequent direction in a homogenized state to the output area. The nozzle further includes a nozzle body portion for enclosing the valve stem, wherein the nozzle body portion preferably includes means for heating the resin. An injection molding system incorporating this nozzle as well as a method for homogenizing molten resin are also disclosed.

Abstract: A mold bushing for injecting plastic material into a mold cavity. The bushing member has a one-piece body member with a central passageway for a shut-off gate pin member and a separate and distinct passageway for the molten plastic material. A tip member is positioned on the end of the body member and has a material discharge chamber. A gate or orifice opened and closed by the pin member is positioned either in the tip member or the mold. A wear bushing member is positioned in the discharge chamber or the end of the body member and acts to support the end of the pin member and prevent the flow of plastic material into the central passageway. The body member is heated by an annular cast heater member or the like. The wear bushing member can be indexed for proper positioning relative to the body member and the plastic flow passageway. The wear bushing member preferably has a body portion which partially fills the discharge chamber in the tip member.

Abstract: A valve pin actuator is disclosed that includes a cylinder mounted to the clamping plate, a piston slidably mounted in the cylinder, and a valve pin assembly carried by the piston. A hydraulic or pneumatic circuit is provided for controlling the movement of the piston, and in turn translation of the valve pin between the seated and unseated positions. The valve pin assembly includes a first part removably secured to the piston so as to translate therewith, and a second part for receiving the valve pin and secured to said manifold. The actuator assembly enables removal of the clamping plate without removal of the valve pin assembly, and also adjusting of the valve pin without removal of the clamping plate. The assembly further provides a clearance between the piston and valve pin assembly, to accommodate expansion and movement of the manifold that would otherwise cause a side load to be exerted on the valve pin.

Abstract: Injection molding apparatus including a first mold cavity having an inlet, a second mold cavity having an inlet, a source of a first material to be injected, a source of a second material to be injected, and a co-injection manifold including a nozzle housing including a first outlet adapted to communicate with the first mold cavity inlet, a second outlet adapted to communicate with the second mold cavity inlet, first and second spaced apart inlets respectively adapted to communicate with the first and second sources of material to be injected, a first passageway communicating between the first inlet and the first and second outlets, and a second passageway communicating between the second inlet and the first and second outlets.

Abstract: An injection molding nozzle is provided that includes a heater disposed about an insert seated in the nozzle body. The heater provides extra heat about the insert where heat loss to the mold can cause a reduction in melt temperature. The heater remains on from one injection cycle to the next injection cycle. In one embodiment, a thermocouple is used to measure the temperature about the insert so that the intensity of the heater can be adjusted accordingly. The heater can also be used with nozzles used in multiple nozzle applications to balance the flow of the nozzles.

Abstract: A resin injector is used to fill recesses created in plaster moulds containing teeth in the interior of muffles with resin, with a simple economic mechanical device which is attached to the muffle and is operated by a conventional press. An assembly of two cylindrical part (4,8) is adjusted to a wide inlet mouth cut in the muffle. The resin which is received in this assembly is projected towards the muffle through at least one hole, which can be opened or closed at will by means of a manually operated part.

Abstract: A valve pin actuator for a valve-gated injection molding system. The actuator has an annular piston mounted in and movable back and forth along an annular bore along a pin axis. The piston extends radially outwardly of any melt passages fluidly communicating with an injection molding nozzle. A tie bar extends substantially diametrically across the piston for securing an upper end of a valve pin extending into the injection molding nozzle to cause the valve pin to move axially with the piston thereby moving the valve pin between open and shut positions.

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: A needle seal nozzle assembly for a plastics injection machine, injection mold or hot-runner system, includes a housing defining a passageway for feeding a melt from an inlet to an outlet, with housing being formed by a first housing portion having one end facing the inlet, and by a second housing portion facing the other end of the first housing portion and having an interior forming part of the passageway. The first housing portion includes a substantially cylindrical tubular body which defines a fluid channel that forms another part of the passageway and is fluidly connected to the interior of the second housing portion. Received in fluidtight manner between the first and second housing portions is a slide for displacement between a first position in which a fluid flow through the outlet is cut and a second position in which the flow of melt is open through the outlet.

Abstract: A molding apparatus produces high-density thin type optical disk substrates having good replicability and birefringence sufficient for practical use. In filling the resin into the cavity, the stress on the resin is reduced by controlling the relation of the cavity width and the injection compression force to reduce birefringence. Further, the mirror surface of the mold is maintained at a certain temperature to facilitate the resin flow and a good replicability and reduction of birefringence is achieved by terminating the resin filling and starting the compression process at the time at which the pressure of the resin filling is at a minimum.

Abstract: An apparatus for thermoset molding includes a first mold portion having a first rim and a second mold portion, having a second rim which substantially conforms to the first rim. The first and second mold portions form a mold cavity therebetween. An actuator mechanism is coupled to the first and second mold portions and is adapted to selectively press the first and second mold portions together. An inner seal positioned between the first and second rims and generally conforming to the first and second rims is provided to substantially seal the first and second rims when pressed together. A bridging member spans the inner seal and selectively weakens the inner seal thereby allowing air passage therepast. An injection valve is provided having a plunger which is moveable to allow resin injection or resin blow-through. Further, a mount is provided for removably attaching a clamp to a mold portion.

Abstract: An injection molding machine for thermoplastic resin consisting of an accumulator in which a plunger is slidably provided and an injection mold, the sprue of which connects with the nozzle of said accumulator, wherein said plunger consists of a cylinder and a screw rotatably arranged in said cylinder, the tip of said screw protrudes from the front end of said cylinder and the maximum diameter of said tip is larger than the diameter of said screw, and the ratio of the effective volume of said plunger to the effective volume of said accumulator is in the range between 1:4 to 1:10 is provided in the present invention. By using said injection molding machine a large size product can be molded at a low injection pressure.

Abstract: A melt ducting arrangement for an injection molding system having a heated nozzle, a valve pin axially slideable in the heated nozzle and a guide bushing for the valve pin which extends into a manifold and of the heated nozzle. The melt ducting arrangement includes a groove in the heated nozzle extending at least part way around the guide bushing. A melt passage extends between the groove and a melt passage in a manifold. The guide bushing has a hole extending generally axially therethrough. The hole has a narrower diameter portion facing away from the heated nozzle and a wider diameter portion facing into the heated nozzle. The narrower diameter portion slideably receives and guides a valve pin. The wider diameter portion provides space to receive melt between the valve pin and the bushing. Radially spaced openings extend through the bushing and register with the groove and to provide a melt conduit between the bushing and the wider diameter portion of the hole.

Abstract: An apparatus for preparing flowable reaction mixtures from at least two flowable reactants in which the components are injected into a mixing chamber by means of injection nozzles, the force of the reactant acting upon the nozzle needle is at least substantially compensated to avoid impairing the mixing ratio during a change-over of the nozzle needle. The rear end of the nozzle needle is provided with a chamber communicating with the component supply line.

Abstract: An injection nozzle has an annular gate directing a flow of plastic melt into an annular opening in a mold cavity. A valve sleeve is shifted over the gate to control outflow of plastic melt.

Abstract: A valve gate injection nozzle includes a valve stem for guiding molten resin to a molding area. The valve stem includes an input area for receiving the molten resin, a central area following the input area for processing the molten resin and an output area following the central area for connection of the nozzle with the molding area. The central area includes a first zone for splitting the molten resin into a plurality of streams, a second zone for mixing and homogenizing the molten resin, and a third zone for combing the plurality of streams and forming recombined molten resin for subsequent direction in a homogenized state to the output area. The nozzle further includes a nozzle body portion for enclosing the valve stem, wherein the nozzle body portion preferably includes means for heating the resin. An injection molding system incorporating this nozzle as well as a method for homogenizing molten resin are also disclosed.