Abstract: An injection molding machine with an injection system and a clamping system. The injection system may include a removable injection module defining a portion of the material flow path. The injection module may include all of parts that come in contact with the material between the material source and the mold. The injection module may include a valve arrangement movable between a fill position to load the injection module with material and an inject position to eject material from the injection module into the mold. The actuators for the injection module may be supported on the machine rather than the injection module. The clamping system may include a platen linear actuator to open and close the mold, and a hydraulic clamping system to apply clamping force to the closed mold. The hydraulic clamping system may include a free-float valve manifold assembly that selectively places the hydraulic cylinders in free-float mode.

Abstract: Method and apparatus for sequentially delivering multiple shots of polymer material to a plurality of mold cavities to form multilayer articles. A first shot of greater than 50% of the total article weight of a first polymer material is simultaneously delivered to a plurality of mold cavities using, at each cavity, a chamber of predetermined volume that is prefilled with the first polymer material. A second shot of no greater than 10% of the total article weight of a second material is simultaneously delivered to all of the cavities beginning subsequent to the step of delivering the start of the first shot delivery step. The second shot of second material is delivered through a manifold channel that fluidly communicates with each cavity, and is injected to all cavities under pressure exerted by a source of the second material that is common to all of the plurality of cavities.

Abstract: A molding device including a mold having a stationary portion arranged on a stationary platen of a press, and a movable portion arranged on a movable platen of the press, at least one injection channel for injecting material into the movable portion of the mold, and a feeder device for feeding the mold with plastics material, the feeder device including a stationary installation including a first metering device for metering a first quantity of material. The feeder device includes at least one second metering device arranged on the movable platen, the second metering device being connected to the first metering device in such a manner as to be fed with plastics material by said first metering device, and being connected to the injection channel for injecting material into the movable portion of the mold in such a manner as to be capable of feeding it with plastics material.

Abstract: In a method of operating an injection molding machine of a type having an injection plunger for pushing melt from an injection space anteriorly of an injection plunger into an injection mold, a plasticizing screw of an extruder is continuously operated to continuously feed melt through a melt channel into the injection space. A passage through the melt channel is closed to allow backup of melt backwards into the extruder, and the injection plunger is moved forward to inject a shot amount from the injection space into the injection mold.

Abstract: The invention is directed to an injection unit, in particular for an injection molding machine, comprising a screw which is guided in a plastication cylinder in a rotatable and axially movable manner and via which plastic material undergoes plastication and can be injected into a tool cavity. The screw is driven via an electric drive including an electric motor and is operatively connected to a support cylinder having a pressure chamber to which dynamic and/or support pressure can be applied during plastication and injection. The electric motor is coupled to a hydrostatic machine which during plastication is driven by the pressure medium displaced from the pressure chamber and which during injection conveys pressure medium into the pressure chamber so as to build up support pressure.

Abstract: A plasticizing and injecting device for a plastics injection molding machine includes an axially fixed and rotationally driven plasticizing screw, and an injection plunger movable forwards and backwards inside the plasticizing screw by a linear drive and including, at its front end, a non-return valve. An injection cylinder is provided anteriorly of the plasticizing cylinder. The non-return valve can be moved by the injection cylinder forwards and backwards inside the injection cylinder between a rear position at the beginning of the injection process and a front position after completion of the injection process. In addition, a melt chamber is formed between the front end of the plasticizing screw and the non-return valve, and forms, during the injection process and during the holding pressure phase, an annular gap between the injection plunger and the injection cylinder for receiving plastic melt as the plasticizing screw continues to rotate during injection.

Abstract: Apparatus and method whereby coinjection molding shooting pot actuation structure is configured to be installed in a coinjection hot runner with a coinjection nozzle, the coinjection nozzle having at least two melt channels ending at the same gate. The shooting pot is preferably disposed in one of a mold cavity half and a mold core half. A shooting pot piston is configured to discharge a melt from the shooting pot. A transmission structure is configured to (i) extend through one of the mold cavity half and the mold core half, and (ii) to transmit a force to the shooting pot piston. Actuation structure is disposed on the opposite side of the mold cavity half from the coinjection hot runner, and is configured to provide the force to the transmission structure. This configuration conserves space in the mold.

Abstract: A method for the production of elastomer and duromer molded items in an injection molding process using an injection molding machine with a respectively separately heatable filling unit, injection unit and cross-linking tool. The filling unit is heated to a temperature which is non-critical with regard to the cross-linking reaction of the plastic to be treated. The injection unit is heated to a temperature which is slightly below the cross-linking temperature of the molding material used.

Abstract: A discharge apparatus for a two-stage injection molding machine, includes a check shaft seat having a runner, and disposed between a feeding portion and an injection portion of the two-stage injection molding machine, for allowing a plastic material in the feeding portion to enter the injection portion via the runner; at least one check shaft disposed in the check shaft seat, and for opening and closing the runner via movement of the check shaft; at least one cover provided at a side of the check shaft seat, and having at least one discharge hole for discharging residues of the plastic material between the check shaft seat and the check shaft; and at least one adjustable unit for adjusting a discharge speed of the residues of the plastic material. The discharge hole and the adjustable unit can prevent locking of the check shaft and pollution from degraded residues of plastic material.

Abstract: An injection molding shooting pot shot size control apparatus is configured to be installed in a coinjection hot runner with a coinjection nozzle, the coinjection nozzle having at least two melt channels ending at the same gate includes a valve inlet and a valve outlet. An adjustable melt control mechanism, preferably in the form of a hydraulically actuated wedge, is configured to (i) be disposed in a cavity plate adjacent to a hot runner assembly, and allow the shot size position to be set while the mold is open, and (ii) permit the charged shooting pot cylinder to decompress the melt when the wedge is pulled away from the shooting pot piston.

Abstract: Platen-mounted, post-mold cooling apparatus and method includes structure and/or steps for handling molded parts in an injection molding machine having a fixed platen, a moving platen, a core half, and a cavity half. A take off device coupled to the fixed platen is configured to remove molded parts from either the core half or the cavity half. A cooling device coupled to the moving platen is configured to cool the molded parts carried by the take off device. Preferably, the take off device extracts the just molded parts from the mold's core half and then moves linearly outboard of the mold halves. The subsequent movement of the moving platen to close the mold in the next molding cycle causes the cooling device's pins to engage the molded parts in the take off device part carriers. When the moving platen opens again, the molded parts are extracted from the part carriers by external gripping devices. When the moving platen is fully open, the cooling device is rotated to eject the cooled parts from the machine.

Abstract: Thermoplastic polymers, rubbery polymeric components and reinforcing fillers are mixed and heated to a range of 380° F. to 440° F. The resulting mixture is then fed into a BANBURY mixer, with the resulting mixture fed into a diverter feeding two molds. The velocity of the piston of each mold being filled is controlled to thereby control the density of the molded product along its length (BANBURY is a registered trademark of Farrel Corporation). As each mold is filled, it is deposited in a cool water bath (50° F.–60° F.) while the next mold is being filled. The molds are sequentially transferred to an air cooling rack to complete the process. A texture, generally comprising indentations perpendicular to the longitudinal axis on the molded object, provides a frictional surface between the railway crosstie and the ballast beneath the crosstie.

Abstract: An injection unit for an injection molding machine includes a plasticizing unit in the form of an extruder, a plunger-type injection device, which can be connected to the injection molding machine by an injection nozzle. The plunger-type injection device defines an injection space. The extruder has a forward portion which is connected to the injection space by a melt through channel in which a shutoff valve is disposed. The extruder is operated continuously and includes one or more plasticizing screws, wherein the extruder is configured in such a way that the backup length can expand backwards into the extruder, when the shutoff valve is closed.

Abstract: An injection unit for injection molding machines includes an extruder as plasticizing unit and a plunger-type injection molding device that can be coupled to the injection molding machine by an injection nozzle. The plunger-type injection molding machine has an injection plunger, wherein the area in front of the injection plunger forms an injection space which is connected to a forward end of the extruder by a melt channel, with a shutoff valve disposed in the melt channel. The extruder can be continuously operated and has one or more plasticizing screws for plastification, wherein the extruder is so configured that a backup length is able to increase backwards into the extruder, when the shutoff valve is closed.

Abstract: A mold valve assembly includes a mold valve chamber having an output port and an injection chamber in communication with the mold valve chamber. A first actuator drives an injection piston within the injection chamber to drive mixture material from an inlet port into the mold valve chamber. A second actuator drives a mold valve piston along the mold valve axis within the mold valve chamber to drive mixture material through an outlet and into a mold cavity of a mold assembly. The mold valve piston closely fits within the mold valve chamber to scrape along an end segment of the injection piston to clean any mixture material remnants therefrom such that remnants within the mold valve chamber are minimized and the necessity of flushing between injection cycles is substantially eliminated.

Abstract: Disclosed is an injection unit having a rotatable device for preventing reverse flow. To connect first flow channels formed in a spacer and second flow channels formed in a screw head when the metering is performed, and prevent reverse flow of resin by cutting off the first flow channels and the second flow channels when the resin is injected, the injection unit has a torsion spring as spring means between a shaft of the screw head and a screw, thereby rapidly preventing movement of the melted resin by restoring force of the spring when the metering of the resin is finished.

Abstract: A plunger machine for molding reinforced polymer compositions is provided. The plunger machine has particular application in molding polymer that is reinforced with particles having an aspect ratio that is greater than 1:1. The plunger machine includes a barrel housing with a smooth walled barrel with longitudinal fins projecting inwardly towards the center of the bore that defines a main melt chamber. A plunger housing, having a plunger bore, defines an initial melt chamber and is in communication with the main melt chamber. A plunger resides in the plunger bore and is reciprocatable therein. The barrel bore is continuously inwardly tapered and cooperates with the longitudinal fins to provide a shortened melt period and a smooth transition and alignment of reinforcing members within the polymer mixture during the melt process.

Abstract: A plunger machine for molding reinforced polymer compositions is provided. The plunger machine has particular application in molding polymer that is reinforced with particles having an aspect ratio that is greater than 1:1. The plunger machine includes a barrel housing with a smooth walled barrel with longitudinal fins projecting inwardly towards the center of the bore that defines a main melt chamber. A plunger housing, having a plunger bore, defines an initial melt chamber and is in communication with the main melt chamber. A plunger resides in the plunger bore and is reciprocatable therein. The barrel bore is continuously inwardly tapered and cooperates with the longitudinal fins to provide a shortened melt period and a smooth transition and alignment of reinforcing members within the polymer mixture during the melt process.

Abstract: A rubber extruder includes a barrel, a screw rod extending into the barrel, a threaded member threadedly engaging the screw rod and rotatable relative to the screw rod, a limiting member for limiting rotation of the screw rod upon rotation of the threaded member so as to permit axial movement of the screw rod, and a driving unit for rotating the threaded member.

Abstract: An injection unit for an injection molding machine includes an injection device in the form of a plunger/screw, which is driven axially and rotationally in a housing, and a device intended for mixing and metering plastic melt and including an inlet for introduction of an additive. A spacer element is disposed between a backflow prevention assembly of the screw and the plunger, with the spacer element having a length, which corresponds at least to the stroke of the injection device. The spacer element has a first flow channel for establishing in each position a fluidic connection with a second flow channel which initially extends radially in an outward direction and then parallel to the movement and guide area of the plunger to an area between a nozzle and the plunger. The second flow channel extends through the mixing and metering device arranged adjacent to a movement and guide area of the plunger.

Abstract: In a compounder-type injection molding machine having an extruder for continuously producing a melt and at least one injection device is fluidly connected to the extruder to receive melt, a reservoir is provided which is in fluid communication with the extruder as well as with the injection device for temporary storage of melt. In order to maintain a pressure at a desired level at the outlet of the extruder, a pressure sensor is provided for ascertaining a melt pressure state downstream of an outlet of the extruder. The pressure sensor outputs a signal, commensurate with the melt pressure state, to a control unit for activating a drive in the reservoir or a drive in the injection device in response to the signal according a predetermined algorithm.

Abstract: A plunger machine for molding reinforced polymer compositions is provided. The plunger machine has particular application in molding polymer that is reinforced with particles having an aspect ratio that is greater than 1:1. The plunger machine includes a barrel housing with a smooth walled barrel with longitudinal fins projecting inwardly towards the center of the bore that defines a main melt chamber. A plunger housing, having a plunger bore, defines an initial melt chamber and is in communication with the main melt chamber. A plunger resides in the plunger bore and is reciprocatable therein. The barrel bore is continuously inwardly tapered and cooperates with the longitudinal fins to provide a shortened melt period and a smooth transition and alignment of reinforcing members within the polymer mixture during the melt process.

Abstract: An injection molding machine includes a plasticating unit for plasticating a thermoplastic resin, and an injecting unit connected to the plasticating unit through a connecting passage to inject the plasticated resin into a mold. In the connecting passage, provided is a buffering unit for reserving the resin in an amount at least equal to the quantity of the resin injected per one shot. The plasticated resin is temporarily reserved in the buffering unit, and then, the reserved resin is fed to the injecting unit when the measuring is carried out, whereby the plasticating unit can be driven continuously simultaneously with the operation of the injecting unit and the mold. The molding cycle can shortened with the plastication efficiency being enhanced.

Abstract: A wax liquid temperature control device of a wax injector is disclosed. In this device, a coal oil heat exchanger controls the temperature of the coal oil in a predetermined range. Then, the coal oil is transferred to a wax liquid temperature control cylinder to control the temperature of the wax liquid so that the wax liquid is retained in a proper temperature for being injected to a mold. Therefore, the wax liquid temperature control device of a wax injector may cool the wax liquid in the mold rapidly.

Abstract: Manufacturing variable and/or singular property products, such as a tubing, in a tip-and-die assembly, where intermittent acting material injectors are used. Two or more injectors take turns making material shots to maintain a continuous material stream. A singular flow controller regulates the flow for all material streams coming from the injectors.

Abstract: Moulding apparatus is disclosed which comprises transfer element (12) which has a holding cavity (14) therein for receiving a charge of mouldable material. Mouldable material in particulate or molten form is fed into a heated passage (30) by a feed spiral (40) in a tube (36). A plunger (42) displaces molten mouldable material along the passage (30) and into the holding cavity (14). The transfer element (12) is then displaced to a position in which the holding cavity (14) is aligned with an opening (18) in a backing plate (16). The opening (18) is in communication with a mould cavity (20) having the shape of the article to be produced. A second plunger (46) displaces the charge of molten mouldable material from the holding cavity (14) through the opening (18) and into the mould cavity.

Abstract: An injection-molding machine is disclosed. The machine has an injection unit and nozzle and the injection unit includes a tubular cylinder and a screw that is capable of back and forth movements along the tubular cylinder. Means are provided to stop the movement of the screw at its end/stop position at a distance from the nozzle so as to form a gap between the screw head and nozzle. The gap has a volume of more than &pgr;/4 ·D3 and up to the volume of a shot wherein D is the dimension of a single screw stroke. The use of the machine yields molded articles that are virtually streak free.

Abstract: An injection assembly for an injection molding machine, with a continuously operating plasticizing unit, includes a piston-type injection unit and an arrangement for intermediate storage and discharge of melt. Several melt reservoirs with melt inlet openings are provided between the plasticizing unit and the piston-type injection unit. Melt lines that connect the melt reservoirs with each other and with the plasticizing unit extend to the melt inlet openings. The melt reservoirs include actuatable work pistons for discharging the melt, wherein the work pistons can open and close the melt inlet openings in the melt reservoirs to divert the melt flow. The disclosed injection unit increases the total volume of bufferable melt and allows individual and separate adjustment of the reservoir volumes and the discharge velocity of the individual melt reservoirs. In addition, switching valves can be eliminated since the melt flow is switched by the work pistons.

Abstract: An object is to increase the mechanical efficiency of an injection molding machine, decrease the inertia, and decrease the axial length. The injection molding machine comprises a cylinder member; an injection member disposed within the cylinder member such that the injection member can advance and retract; an injection motor (82); and a transmission shaft which is connected to the injection member such that the transmission shaft can rotate relative to the injection member. The transmission shaft has a rotation transmission portion, to which rotation of the injection motor (82) is transmitted, as well as a motion conversion portion for converting rotational motion to linear motion. The injection motor (82) and the transmission shaft are disposed on the same axis, and the transmission shaft is advanced and retracted inside the rotor (92) of the injection motor (82).

Abstract: A two-stage, electrically-powered injection unit for an injection molding machine includes an extruder for plasticating material, and a separate melt accumulator to receive the plasticated material. The accumulator includes an injection plunger that is slidably positioned to inject the plasticated material from the accumulator into a mold. The plunger is rotated and translated by an electrically-driven linear actuator, such as a roller screw mechanism. The plunger extends outwardly of the accumulator barrel at the commencement of an injection stroke and is peripherally supported by a bushing at the outer end of the accumulator barrel. The outwardly-extending portion of the plunger can also be supported by a movable intermediate support member to minimize lateral deflection of the plunger and enable a longer injection stroke to be employed.

Abstract: An injection device includes a cylinder, a plunger and a driving device. The cylinder has a port for supplying molding material into the cylinder, and the molding material supplies into the cylinder is compressed by the plunger. The plunger has a groove extending circumferentially around an outer wall of a large-diameter portion of the plunger, and the clearance between the outer wall of the large-diameter portion of the plunger and the inner wall of the cylinder is determined by a specified equation.

Abstract: An electric injection assembly for injection presses for plastic materials, comprising a plasticating screw (5) that performs a translational feed movement during injection of the plastic material into a mould cavity and a rotary movement around its own axis and a rotary translational movement of rotation around its own axis and retraction during the plasticating stage of the plastic material, the plasticating screw being connected to a drive screw (30) comprising two sections (30A, 30B) with threads having the helix in opposite directions, each of the sections (30A, 30B) engaging in respective screw nuts (31A, 31B) driven in rotation by respective electric motors (32A, 32B) through respective reduction units (33A, 33B).

Abstract: When a process measurement metering operation is performed during a molding cycle, a plunger is forcibly caused to retract to a position behind measurement metering completed position, while at the same time a periodic forced purge operation is implemented in which the plunger is immediately restored to the vicinity of the position at which the forced retraction operation commenced. By this operation, leaked resin is removed to the rear, i.e., beyond the plunger metering stroke range, and any increase in resistance to movement of the plunger due to disposition of leaked resin is avoided. The forced purge operation is preferably performed either immediately prior to the normal metering operation, or after a specified time has elapsed following completion of a metering operation.

Abstract: An apparatus and method provides that before, during, and/or after the plastic objects have been injection molded, a portion of the first plastic component, the second material, and/or a mixture of the two components is conveyed to at least one storage element with a variable volume. This element adjoins the flow path of the material melt. After completion of the injection molding process of the plastic objects and/or before the material is injected for the next plastic object to be produced, the plastic or the material stored in a storage element with a variable volume is conveyed to the flow path of the melt of the plastic or material. This frees the melt flow path of a mixture of the two plastic components and/or obtains a desired material mixture for producing the next plastic object.

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: A two-stage, electrically-powered injection unit for an injection molding machine is disclosed. The injection unit includes an extruder for plasticating material, and a separate melt accumulator to receive the plasticated material. The accumulator includes an injection plunger that is slidably positioned to inject the plasticated material from the accumulator into a mold. The plunger is rotated and translated by an electrically-driven linear actuator, such as a roller screw mechanism. The plunger extends outwardly of the accumulator barrel at the commencement of an injection stroke and is peripherally supported by a bushing at the outer end of the accumulator barrel. The outwardly-extending portion of the plunger can also be supported by a movable intermediate support member to minimize lateral deflection of the plunger and enable a longer injection stroke to be employed.

Abstract: The invention is directed to a two-stage, all-electric injection unit. More specifically, an injection unit in which the feed screw is preferably used only for plastication and the injection of the plasticized material is accomplished by a separate accumulator having an electrically driven linear actuator, such as a ball screw mechanism. The plunger of the accumulator is configured with a helical flight and is rotatable by way of a one-way clutch interposed between the plunger and the ball screw.

Abstract: In a process for the simultaneous manufacturing of a plurality of injection-molded micro parts from thermoplastic or cross-linking polymers in an injection molding tool, an injection device is provided which has injection cylinders, injection pistons and temperable antechambers. The plastic melt coming from a conveyor worm, by way of temperable sprues, first arrives in the antechambers and, in a second step, is supplied by the injection pistons by way of the injection nozzles to the mold cavities. The mold cavities are filled independently of one another. The co-solidifying runners are eliminated, and it is possible to manufacture particularly small parts with a low injection volume at particularly reasonable cost.

Abstract: A method for injection molding a material consisting of a suspension of particles. The suspension of particles moves through convergent passages in an obturator and an injection channel so that the particles remain in suspension. The press has a head in which a portion of the feed channel and a portion of the injection channel, when the channel is open, is formed by a passage in an externally controlled obturator, the controlled obturator for the feed channel and the one for the injection channel being one and the same or adjacent, and disposed close to the injection orifice.

Abstract: The invention is directed to a two-stage, all-electric injection unit. More specifically, an injection unit in which the feed screw is preferably used only for plastication and the injection of the plasticized material is accomplished by a separate accumulator having an electrically driven linear actuator, such as a ball screw mechanism. The accumulator is configured so that the ratio of the piston stroke to the piston diameter is preferably in the range of ten to fifteen. In the preferred embodiment there are separate motors for rotation of the screw and operation of the accumulator. An alternate embodiment is disclosed wherein the system is driven with a single motor and one-way clutches.

Abstract: One or several molten materials are extruded at low pressure from one or several continuous plasticizers through central stationary nozzles via individually circumferential flow passages of common distribution spools directly into individual extendable transfer reservoirs. From there, the molten materials are transferred in a continuous cascading manner into secondary transfer reservoirs to be subsequently transferred and condensed within mold cavities into finished molded articles. The central stationary nozzles and stationary primary displacement plugs are grooved with lateral longitudinal melt-flow channels to allow the conveyance of molten materials across intersecting molten material passage ways during the extending movement of the manifold assembly. The molten materials are conveyed through secondary displacement plugs into secondary transfer reservoirs by external cylinders, retracting the manifold assembly on adjustable-length spacer rods in unison against the stationary primary displacement plugs.

Abstract: An injection molding apparatus for processing thermoplastic materials has at least one plasticizer unit, at least one injection molding cylinder with associated emptying piston, and at least one injection molding mold. The injection molding cylinder is provided with a sleeve which is arranged reciprocally between a position in which communication with the injection molding mold is interrupted and a position in which communication with the injection molding mold exists. In the position in which the communication with the injection molding mold is interrupted, a passage is provided between the sleeve and the housing which is connected between the feed conduit from the plasticizer unit and a storage space defined on the inside by the sleeve. The outside diameter of the ejection piston is slightly smaller than the inside diameter of the sleeve so that remaining between the two is an annular gap through which the plastic material passes into the storage space from one end of the sleeve.

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: Molten resin, plasticized in the plasticization chamber, is fed to the injection chamber through a connection passage where it is measured. Before it is injected by the plunger, the connection passage is blocked and the molten resin is preliminarily compressed. This invention provides a method using a preplasticization type injection molding machine that controls the volume of the filled molten resin with little variation utilizing blocking and preliminary compression. By means of blocking or preliminary compression, the position movement by which the plunger moves from the position at which the measurement is completed is calculated, and the position at which the next measurement will be complete is corrected. Furthermore, the molten resin fill operation is done on the basis of the position of the plunger detected at the time of the preliminary compression.

Abstract: An injection molding process for forming high strength, long fiber-reinforced thermoplastic resin, and for holding damage to the pellet-shaped thermoplastic resin to a minimum even when being plasticized, and maintaining the fiber length of pellet-shaped fiber bundles while unwinding the fibers and melting the resin. After the long fiber-reinforced thermoplastic resin has been heated and melted, pressure is applied to unwind the long fiber-reinforced thermoplastic resin while melted, and injection molding then performed.

Abstract: An injection molding machine having an injection plunger (21) capable of moving back and forth within an injection chamber (22) includes a scraper ring (23) attached to one end of an injection cylinder (2) having a hole penetrated by the injection plunger. A protuberance (23a), which forms the smallest diameter portion of the hole penetrating the scraper ring and extends to the surface of the injection plunger, is formed on the inside wall of that scraper ring. The perimeters (23e, 23h) of this protuberance scrape off any molding material which adheres to the injection plunger. The scraper ring has windows (23f, 23g) for the purpose of dropping scraped-off material outside thereof. Preferably, the injection plunger has a shank (21b) and a head (21a) which forms the tip of the injection plunger and which has a diameter larger than the shank and slightly smaller than the injection chamber; the protuberance of the scraper ring has a diameter which is slightly larger than the shank and smaller than the head.

Abstract: The invention pertains to an apparatus and method of using the same. This apparatus includes a mold defining a mold cavity and an inlet through which molten material can pass. Also included is at least one feeder for preparing a molten material. This feeder has an outlet through which molten material can pass. There is also at least one accumulator spaced from the feeder and the mold. This accumulator has an inlet through which molten material can enter, and an outlet through which molten material pass. The accumulator also is designed such that it can introduce a molten material through its outlet into the mold cavity and exert a shear stress, compressive force or stress tensor on the molten material contained within the accumulator and/or within the mold cavity. The apparatus also includes a flow control mechanism is designed to prevent the flow of molten material from the accumulator back into the feeder.

Abstract: Equipment, in particular pressure gelling equipment, is provided to fill one or more casting molds with castable, liquid materials of which the components are fed by pumps through closable conduits to at least one plunger-cylinder system from where the components are moved to a mixing chamber and from there to the particular casting mold. In order to process especially abrasive casting materials of high viscosity and short pot life, the invention provides that at least one plunger-cylinder system be operated at a pressure substantially higher than are the pumps and that the mixing-chamber volume be comparatively slight.

Abstract: Molten resin flows from the opening of a path and washes a closed space of an injection chamber to prevent molten resin from being retained therein. Resin leaking from between a peripheral wall of a cylinder and a head of an injection plunger is quickly exhausted. When a screw retreats, molten resin is delivered from the opening to the injection chamber through the path. Resin from the opening causes a flow that washes and agitates resin remaining in the closed space opposite a nozzle hole, since a front face of the plunger is conical in shape with a protruding or higher center. There is a slight step between the plunger head and a shank of the plunger. The step scrapes resin which adheres on the cylinder peripheral wall to quickly exhaust such resin through a narrow clearance between the peripheral wall and the shank. The plunger head is coated with a ceramic.

Abstract: A standard injection molding machine is combined with an auxiliary plasticizing unit having a hot runner manifold that can be alternately connected with or disconnected from the main injection unit of the molding machine to perform sandwich molding. The injection unit retracts from the mold to connect with a hot runner and receive skin material from a non-reciprocating screw extruder directly into the barrel of the injection unit. The injection unit then disconnects from the hot runner and moves back into position for injection into the mold. Simultaneously with this movement, the injection unit plasticizes sufficient core material to complete the stacked arrangement of skin and core material necessary for sandwich molding. In an alternate embodiment, the sandwich molding apparatus includes an accumulator with a suitable valve and connections to the other components to supply a final shot of skin material into the mold, as well as provide the pack and hold functions of the injection cycle.