Abstract: Disclosed is a high pressure injection molding system employing one or more plastic injection molding workstations including split molds, a single plastic extruder coupled to a heated manifold capable of delivering fluid plastic to multiple workstations, and wherein final lockup of the split mold halves results in application of compressive forces effective to maintain the split mold halves in nominal position during high pressure injection molding conditions. Operational movement is performed by use of a single remote pumping station utilizing pressure compensated pumps, accumulators and manifolds. The independent mold workstations allow independent operation while providing efficency of operation for the hydraulic system and extruder system.

Abstract: The invention is directed to a bi-directional check ring for a two-stage injection unit. More specifically, a close fitting ring is inserted behind the plunger head of the melt accumulator so that normal running clearances between the plunger and barrel bore can be used. The outer diameter of this check ring has a very close fit with the inner diameter the injection barrel, but is not rigidly connected to the plunger. Accordingly, the plunger is free to “floats” while injection and plastication/filling take place. The open volume between the ring and plunger is small, but sufficient to permit the ring to “float” very close to the barrel inner diameter, without being influenced by the alignment of the plunger and injection drive motor.

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: The present invention relates to an apparatus and method for producing molded polyester articles. More particularly, the invention concerns an apparatus and method for continuously producing molded polyester articles having low acetaldehyde content from a melt prepared by continuously reacting polyester precursors. The polyester is prepared and formed into useful shaped articles in a single, integrated, continuous melt-to-mold process without an intermediate solidification of the melt.

Abstract: A preplasticizing type injection apparatus having an injection cylinder internally provided with an injection plunger and a plasticizing cylinder provided in the inside with a plasticizing screw or plunger, the injection and plasticizing cylinders being arranged in juxtaposition and held in communication with each other by way of a resin conduit connecting an inlet path of the injection cylinder arranged at the front end thereof and defining the limit of advancement of the plunger and an outlet path of the plasticizing cylinder arranged at the front end thereof so that a front end portion of the injection cylinder is charged with resin molten in the plasticizing cylinder and the resin in the front end portion of the injection cylinder is injected into a mold by the plunger, characterized in that the resin conduit is realized in the form of a small metal pipe having an inner diameter between 5 and 10 mm and a length at least five times and preferably twenty to forty times greater than the inner diameter of the

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: 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 method and apparatus for sending a coating material (C) under high pressure into an openable mold (2, 3) which is closed and filled with a moldable material. A chamber (6) is used having one end (7) open toward the inside of the mold and an injection duct (14) emerging in the chamber (6). A piston (38) which can move in the chamber (6) from a first position in which the piston blocks the open end (7) of the chamber, is moved as far as a second position beyond the injection duct (14) in relation to the open end (7) of the chamber. The coating material (C) is injected into the chamber (6) via the injection duct (14) under a first pressure (P0); and with the mold remaining completely closed, the piston (38) is moved toward the first position by applying thereto a force (F2) corresponding, inside the chamber (6), to a second pressure (P2) which is greater than the first pressure (P0). Only thereafter is the mold (2, 3) opened.

Abstract: An injection unit (1) for injection molding machines used in the manufacture of plastic objects has a nozzle element (2), a material feed system (7), a cylinder-piston unit (3, 4) arranged between the nozzle element (2) and the material feed system (7), a valve (10) arranged between the cylinder (4) and the material feed system (7), and a device (21) for pressing the nozzle element (2) to the edge of the gate of an injection mold. The nozzle element (2), and the piston (3) guided in the cylinder (4), may be integrally formed. The nozzle element has a channel (11) in alignment with an axial bore (13) in the piston (3). The channel (11) and bore (13) are in communication with the interior of the cylinder. The cylinder (4) can be moved in the direction of the longitudinal axis of the piston while the piston (3) does not move.

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: Cold-stretchable sheet material is isostatically formed at an operating temperature beneath the softening temperature of the sheet material by means of a fluid pressure medium at a pressure of more than 20 bars so as to produce a deep-drawn formed plastics piece. Forming may take place abruptly. The sheet to be formed may be provided with a coating such as an ink imprint. The resulting thin-walled deep-drawn piece may be backed and reinforced by injecting further plastics material.

Abstract: A process for distributing wax or a similar substance in semi-solid form which uses a liquid wax supply system, a wax conditioning system including a heat exchanger which cools the wax to a semi-solid state and an accumulator for storing conditioned wax until needed, and a die press or similar work station which receives semi-solid wax from the accumulator in a continuous stream or flow. Such a system allows a lost wax die press to operate without need to manually open and reload the press with wax. An automated control system according to the invention allows die press reloading to occur automatically when needed, and operates the wax conditioning system as needed to maintain a supply of wax in the accumulator. Wax tunnelling problems are avoided by means of a piston disposed in the heat exchanger which is movably interposed between hot liquid wax entering the heat exchanger and cooler, semi-solid wax leaving the heat exchanger.

Abstract: A device for dosing a plastic, perishable mass into moulds has a pressing chamber for receiving a dose of the mass from a feed vessel and a piston operable in the chamber to push and compress the dose into a mould. The device includes a valve for shutting off feed of the mass from the feed vessel and is particularly constructed to avoid spaces into which the mass can collect and spoil, while preventing reentry of the mass from the pressing chamber into the feed vessel.

Abstract: In the injection molding of a hollow shaped article by the injection of not only molten synthetic resin but also compressed gas into a die, a method is provided by this invention which effects the supply of the compressed gas with a multistage compressor and the injected compressed gas is recovered in a recovery container connected to the suction side of the multistage compressor. For the injection molding of a hollow shaped article by the injection of not only molten synthetic resin but also compressed gas into a die, an apparatus is provided by this invention which has a gas nozzle for injecting the compressed gas into the die connected through a first switching valve to the discharge side of the multistage compressor and, at the same time, has the gas nozzle connected through a second switching valve to a recovery container connected to the suction side of the multistage compressor.

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

Abstract: Apparatus and method for injecting a shot of flowable material into a mold involve moving a plunger-type injector in a continuous non-decelerating manner past an outlet which leads to the mold. The injector is decelerated, but only after it passes the outlet to the mold.

Abstract: A single-state apparatus for injection molding structural foam articles has a resin plasticating barrel in which a cylindrical plunger reciprocates and rotates. The plunger has a screw section for plasticating resin and advancing the plasticate into a metering section with grooves in which plasticate flows. The grooves are contiguous to a fluid foaming agent inlet in the side of the barrel so that they alternately open and close the inlet to introduce fluid foaming agent periodically into the plasticate. Downstream, the plunger has channels for mixing and advancing plasticate to the forward end of the plunger where it accumulates and is periodically rammed by the plunger into the mold.

Abstract: A system and method of controlling hold pressure applied to molding cavities of a stacked multi-parting injection molding system having desynchronized injection periods while cyclic injection molding a plastic material. A combination of the center molding block and an injection system together provide an adjustable feed system. The feed system is adjusted to enable plastic material to be fed from the injection system through a left branch to the left molding cavity. The injection system is pressurized to inject the plastic material through the left branch to fill the left molding cavity. The injected plastic material is confined within the left branch and the left molding cavity; and the confined plastic material is hold pressurized by a movable packing element. A like sequence of steps is followed to hold pressurize the right molding cavity.

Abstract: An injection moulding apparatus (10) includes similar co-injection modules (12) each provided with common supplies (238-242) and supplied with different polymer materials at intermediate pressure by common plasticisers (14-18). Each module has a co-injection nozzle assembly (70) in wich each nozzle (148-154) is supplied with polymer at injection pressure by an injector (208) which receives polymer through a non-return valve (220). The injector is mounted alongside the nozzle on a polymer transfer plate (138-146), and has the position of its piston (212) controlled by a hydraulic actuator (214) under the control of a dedicated micro-processor (164) in accordance with a stored injection control program. Each polymer is injected by an injector (208) directly into the associated nozzle (148-154) and is controlled solely by injector operation, and without the use of any control valve between the injector and the nozzle.

Abstract: The improved check valve assembly includes a cylindrical barrel, a rotating and reciprocating plasticizing feed screw in said barrel, a screw tip or head portion downstream of the feed screw and connected thereto with the feed screw feeding heated thermoplastic material to the screw tip which in turn feeds the material externally of the screw tip, a check valve assembly between the feed screw and the screw tip including a sliding ring inside the barrel, a first sealing surface of the ring sealable against the feed screw operative to block communication between the feed screw and screw tip, and means operative to seal the ring against the feed screw upon rotation of the feed screw.

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

Abstract: A backflow-preventing valve for use in a screw head of a screw injection-molding machine which has an annular shape and comprises a ceramic member is disclosed and a metallic member. At least a surface portion of a backflow-preventing valve which is brought into contact with a material to be injected and a screw groove or a valve seat is constituted by a ceramic material.

Abstract: It has been found that when layered preforms are being injection molded utilizing at least two materials, it is possible to maintain the same horizontal and vertical pitch of adjacent cavities as is possible when each mold cavity is being filled with a single material. Most particularly, it has been found that when the percentage of the material to be injected into a mold cavity is relatively high, it is possible to utilize a single metering pot for four adjacent mold cavities. On the other hand, if one of the materials to be injected into a mold cavity constitutes a relatively low percentage of the volume of a mold cavity, it has been found that a small metering pot must be provided for each of the cavities of the four cavity mold.

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

Abstract: An injection apparatus of a plunger type for injecting reinforced materials such as BMC is of a single barrel type or a double barrel type having a rotatable plunger disposed in the barrel. A check valve device for preventing a back flow of the materials in a metering process is provided such that it is closed when the plunger is actuated to move axially for injection.

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

Abstract: Apparatus for producing an injection moulding of plastics material comprises means for introducing a supply of plastics material, passage means for communicating the supply means to a mould space, and means for introducing a pressurized gas into the plastics material filling the mould space whereby the gas creates a gas containing cavity in the plastics material and for thereafter relieving the gas pressure within the gas containing cavity before the mould is opened.

Abstract: The present invention increases the shot capacity and the screw recovery time of an injection molding machine without increasing hydraulic pump capacity or motor horsepower. In accordance with one aspect of the invention, an existing injection molding machine is retrofitted with two cylinder and piston arrangements which are bolted onto the machine between its plasticizer barrel and its melt manifold. One of the cylinder and piston arrangements is employed to perform a mold-filling operation, whereas the other cylinder and piston arrangement is employed to perform packing and suck back operations.

Abstract: Apparatus for coinjecting a plurality of thermoplastic materials to mold an article having a layered wall structure using thermoplastic material having different optimum processing temperatures including the maintenance of the optimum temperatures in flow paths individual to each material from its source to a mold cavity.

Abstract: An injection molding machine for molding with a high polymer material such as rubber and resin which is improved in the working efficiency and productivity thereof. The injection molding machine comprises a plurality of independent metallic molds, a metallic mold securing device having two receiving portions for receiving and clamping the metallic molds therein, a metallic mold loading and unloading device for loading and unloading the metallic molds to and from the receiving portions, and a drive device for moving the metallic mold securing device. Accordingly, injection and vulcanization can be carried out alternately for two metallic molds so that, also during vulcanization for the first metallic mold, injection to the cavity of the second metallic mold can be carried out. The metallic mold securing device can otherwise have more than two such receiving portions when necessary.

Abstract: Disclosed is an injection press for use in a transfer molding system for fiber reinforced thermo-setting resins, comprising an injection piston, an injection cylinder in which the injection piston moves, a feed bore which traverses the injection cylinder, a sprue orifice which leads into the mold, a telescoping sleeve which serves to seal off the feed bore when the piston travels toward the sprue orifice, wherein the injection piston seals the transfer bore at the end of the stroke near the sprue orifice, and wherein said feed bore is open when the piston is in a position a stroke length away from the sprue orifice.

Abstract: The output of a plastic or polymeric material processor is fed through a three-way valve to an expandable chamber in a barrel having a ram therein. When the chamber has a predetermined charge the valve is shifted to direct the output of the plasticator to an accumulator. Operation of the ram injects the material into a mold cavity and thereafter the valve shifts to direct the combined output of the plasticator and the accumulator to recharge the chamber.

Abstract: Method and apparatus for injection molding plastic articles having solid exterior surfaces and porous interior cores wherein a molten mixture of a chemically reactive foaming agent and a thermoplastic resin is injected into a mold so as to fill the mold cavity with unfoamed resin and form an outer solid skin on the molded article. Immediately prior to injection, an activator additive is introduced into the mixture, the additive reacting chemically with the foaming agent after a time delay of no more than a few seconds to provide for cellular expansion within the core of the molded article. The result is a molded body with a solid unfoamed skin which accurately relicates the surface of the mold and a cellular inner core.

Abstract: A wax cylinder for a wax spraying machine is disclosed. The wax cylinder includes a housing, an ejection cylinder having a chamber mounted in the housing. An elongated piston is slidably mounted in the chamber and includes a pressure face for pressurizing and urging wax in the chamber out through an ejection opening. The chamber is maintained in constant fluid communication with a feed line for feeding wax into the chamber throughout the stroke of the piston. A check valve is utilized to prevent back flow of wax through the feed line. Air is prevented from flowing into the chamber during the return stroke of the piston.

Abstract: The proposed machine incorporates a rotatable support on which injection cylinders which cooperate with actuating hydraulic cylinders are mounted. Each injection cylinder accommodates a ram and a nozzle which are capable of mutual axial motion. The actuating hydraulic cylinder is coupled directly to the ram which engages the nozzle at the moment they come into contact. The injection cylinder is fitted with internal annular grooves, one of which communicates with a plasticator.The nozzle is provided with channels for placing in communication a cavity, defined between the ram and the nozzle, and the nozzle outlet orifice via one of the annular grooves.

Abstract: Voluminous products of plastics are made by providing between a filling cylinder of the injection part and the mould a transfer chamber with a piston, the axis of which does not coincide with the axis of the filling cylinder.

Abstract: Hydraulic cement or the like is poured into a closed mould under a reduced pressure condition to a level slightly higher than a predetermined level. Coarse aggregate and steel rods are prepacked in the mould. After pouring, the pressure in the mould is increased to atmospheric pressure or a higher pressure to force the hydraulic cement above the predetermined level back into the space below the level thus compacting the poured in hydraulic cement. A cushion device is provided for the pouring device. An overflow tank is connected to the mould to observe the level of the poured cement. The pressure in the overflow tank is also decreased during pouring and increased after pouring.