Abstract: This invention relates to automating a process for manufacturing articles from plastic, particularly recyclable plastic waste. A lengthened separator head is flanged to a plasticizer to supply melting serially to several molds, by way of mold inlet shut-off mechanism. A preprogrammed control device monitors the filling of a respective mold by way of a pressure sensor in the mold. When the desired filling of the mold has occurred, the inlet shut-off mechanism is closed by the control device and another mold that is ready to be filled is filled with melting by the opening of the corresponding inlet shut-off mechanism at the another mold. In addition, the control device controls the locking and tightening of the mold as well as its opening and emptying.

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

Abstract: An extruder having a reduced nip ratio and a process employing the same.

Abstract: An injection molding unit has an injection molding machine 1 for injecting a molten resin plasticized in a screw cylinder 4 from a nozzle 9 fitted at the tip of the screw cylinder 4 by advancing a screw 3. An injection mold 31 forms a hollow 36 for forming an injection molded product 35 with a cavity mold 33 and a core mold 34. The injection molding unit further has a pressure relief valve 40 for releasing the resin out of a resin passage when a pressure greater than a predetermined value acts at any point on the resin passage, including the screw cylinder and ranging up to the terminal end of the hollow. The cavity mold 33 is of a split construction, in which a wall portion of the hollow is formed a plurality of segments.

Abstract: The present invention has a purpose to prevent leakage of resin material and disorder of cutting operation without increasing plate thickness of the cutter, thereby providing a resin material supply apparatus capable of suiting increase of resin material sheet size or higher back pressure.To this end, according to the present invention, there is provided a resin material supply apparatus and method for a resin press molding machine in which: resin material is extruded in a supply cylinder toward a die by a piston, and the molded resin material is cut by a cutter which slides along a front end surface of the die. Then, the cut resin material is supplied onto a metal mold, and new resin material is charged into the supply cylinder by pressing the cutter toward the die at a position that the cutter closes an opening of the die.

Abstract: An improved electrical insulator for high voltage transmission lines is formed from certain polymer-based concrete compositions. An apparatus provides for the molding of the polymer-based mixture to form a highly degassed product. The method and apparatus include the ability to combine the constituents of the mixture in a mixer. A vacuum is applied to the mixture to degas the mixture. A mold is filled with the degassed mixture without introducing air thereinto in the absence of a vacuum. The resulting insulator has highly reduced air entrainment.

Abstract: A method and apparatus for gas assisted injection molding which will first inject a shot of molten plastic into a suitable mold, shut off the plastic flow into the mold, and either immediately, or after a delayed time, inject a suitable pressurized gas into the mold at a desired injection pressure. The pressure of the gas in the mold is then controlled by stepping up or stepping down the pressure in the mold in a series of steps to arrive at a second predetermined and precisely controlled pressure. The predetermined pressure is held for a desired time. The setting and holding of pressure is repeated as many times as desired, and is then stepped down to a final pressure. The mold is then opened, and the article is removed.

Abstract: A method and apparatus for determining the location and stability of location of the edges of an object such as an extruded blown film polymeric material annulus. By real time detection of the edge location and mathematical and statistical manipulation of the data in both time and frequency domains, the stability and effects of extrusion parameters on the object can be determined.

Abstract: A method of controlling the extrusion of a multilayer parison so that the injection pressure for an auxiliary resin and that for an adhesive do not act on the annular fluid passages while a main resin, an auxiliary resin and an adhesive are stored in a main resin accumulator, an auxiliary resin accumulator and adhesive accumulators, respectively. The injecting pressure difference between each pair of auxiliary resins and the adhesive is maintained within a prescribed range and the injection of the resins and the adhesive from the accumulators is terminated simultaneously for all the materials.

Abstract: A plurality of cores are covered with the same jacketing material by passing the cores through respective dies of a plate, while flowing the jacketing material through sub-channels in the plate and into coating relationship with the cores. Any of the sub-channels can be shut off by diverting the jacketing material a flow diverting path without affecting the flow in the other sub-channels.

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

Abstract: Valve gated injection molding apparatus for coinjecting and/or sequentially injecting two different fluids through a gate into a cavity. An elongated valve pin member is received in an elongated valve sleeve member in alignment with the gate and both are reciprocated rotatably as well as axially by separate actuating mechanisms to control the flow of the fluids through the gate. Each actuating mechanism has a piston driven rack member to provide rotary motion which is then converted to axial movement of the corresponding valve member between the retracted open and forward closed positions. In one embodiment, helical threads on the valve members engage fixed teeth extending inwardly from the surrounding nozzle to convert the rotary motion of each valve member to corresponding axial movement. Linear position transducers on the rack members provide for accurate control of the valve members.

Abstract: A die assembly (10) for controlling extrudate profile dimension. The die assembly includes a die block (12) having a feed passage (16) for movably supporting a diverter member (13) within the die block, and first and second die block passages (18, 20). The diverter member (13) includes a diverter passage (32) and first and second feed openings (34, 36) interconnected by the diverter passage. One of the first or second feed openings (34, 36) has a larger diameter than the other of the first or second feed openings. The diverter member (13) is movable with respect to the die block (12) for directing extrudate flow via the diverter passage (32) through the second die block passage (20), to thereby vary the profile dimension of the extrudate exiting the die block. The die block (12) additionally includes a disposal passage (22).

Abstract: A liquid dispensing apparatus comprises a syringe containing liquid to be dispensed and an air supply for supplying compressed air to the syringe. The syringe is connected to the compressed air supply via a discharging solenoid valve by means of a pipe line which is provided with an accumulator so as to prevent disturbance of stand-up of the pressure in the syringe to thereby effect a highly accurate quantitative discharge of liquid from the syringe independent of whether a quantity of liquid remaining in the syringe is much or less. The apparatus further comprises an air suction connected to the discharge solenoid valve by means of an additional pipe line provided with an accumulator to prevent liquid from dropping out of the syringe after the end of discharge of liquid.

Abstract: Extrusion of a tubular parison for blow molding is controlled according to a program of set point data defining parison wall thicknesses and extrusion rates. Progress of purge of plasticized material from an accumulator through a variable annular gap is measured. Parison profile set point signals defining wall section thickness at points correlated with progress of purge of the accumulator are produced in response to the measured progress. Purge velocity set point signals defining purge velocities correlated to selected profile points are produced in response to progress of purge of the accumulator. Variation of the annular gap is controlled in response to the parison profile set point signals and velocity of purge of the accumulator is controlled in response to the purge velocity set point signals.

Abstract: A control device for timed control of a filling pressure during filling of a press die with a pasty or slip-like mass has a pressure sensor detecting a pressure in the press die, a threshold stage to which a corresponding pressure signal is fed from the pressure sensor, a timing element on which the threshold stage acts to maintain a filling pressure at an intended value during determinable holding time, a second threshold stage to which the pressure signal can be fed, and a logical gate to which outputs of the two threshold stages are connected and which generate a trigger signal for timing element when a particular value simultaneously exceeds a first threshold value of the first threshold stage and falls below a second threshold value of the second threshold stage.

Abstract: An apparatus for controlling a molding of a solid product in a mold cavity from molten material which solidifies in the mold cavity, in which first and second conduits are coupled to the mold cavity at spaced positions for carrying the molten material, includes first and second elements, and a controller for controlling the driving the first and second elements repeatedly during solidification of the molten material in the mold cavity so that the molten material is repeatedly moved through the mold cavity. The first element is disposed in the first conduit and the second element is disposed in the second conduit.

Abstract: A seal on a drive shaft of an extrusion machine having a housing, is provided by a sealing chamber through which the shaft, for example the drive shaft of the shear spindle, extends in entering the housing, and a sealing screw thread on a portion of the shaft in the sealing chamber, the sealing screw thread having a screw direction for propelling material toward the interior of the housing. Sealing material in the form of granular plastic material is fed to the sealing chamber at a controlled rate by a device having a storage container for the granular plastic material, the bottom of the container having a funnel feeding the granular plastic material into an elongate cavity which communicates with the sealing chamber and in which the piston rod of a piston-cylinder unit is reciprocable to propel the granular plastic material into the sealing chamber. The pressure inside the sealing chamber is sensed and the operation of the piston-cylinder unit is controlled to maintain the pressure approximately constant.

Abstract: The invention is embodied as a raw material resin feeding apparatus for a molding machine, such as an injection molding machine or an extruder. In this system, upon carrying out a variable resin-change operation by making use of material to be changed, raw material resin is intermittently fed to a feed section by intermittently opening and closing a resin passageway. The improvements reside in that the apparatus includes a raw resin material feed selection mechanism provided midway along a resin passageway for selectively either feeding a predetermined amount intermittently or continuously to a feed section. A resin-change resin feed start detector mechanism is provided for detecting completion of discharge of the amount of raw material corresponding to the predetermined amount, and a resin-change completion detector mechanism is provided. With this apparatus, raw material can be selectively fed to effect quick resin-change or for normal operation.

Abstract: An apparatus for forming multiple layer preforms wherein the various layers may be varied as to number, material, thickness and position in the preform by controlling the injection of the specific materials as to timing, quantity and rate of delivery. Most specifically, a featured aspect is the ability to simultaneously deliver to an injection nozzle and through such injection nozzle into a preform mold cavity two or more molten plastic materials simultaneously. This is possible by way of a multiple gate nozzle and a plurality of separately operable metering pots all controlled by way of a timing device. The timing device may also control the rate of the dispensing an individual material from each of the metering pots.

Abstract: A die assembly for configuring extrudate flow is provided. The die assembly includes a die head having a feed member passage, first and second die head passages, and first and second die surfaces respectively associated with the first and second die head passages. The die head passages are located intermediate the corresponding die surfaces and the feed member passage. A feed member is supported in the feed member passage of the die head and has a feed passage and a feed opening for supplying extrudate to the die head. The feed member is supported for relative movement within the die head whereby the feed opening may be moved to communicate with either the first die head passage or the second die head passage. The central axis feed of the feed opening is moveable with respect to the central axis of the first or second die head passage to correspondingly configure extrudate exiting the respective die head passage when the feed opening is in communication with this die head passage.

Abstract: In an extrusion device of the type which has a screw rotating in a housing and which has a feed section in which a feed roller, cooperating with the screw, is provided, a stripper blade is used to remove the fed material from the feed roller. The present invention provides a method and an apparatus for maintaining the net force acting on the stripper blade to direct it towards the feed roller constant. To achieve this, the force of the fed material which acts in a direction tending to move the feed roller and the extrusion screw apart is measured. An opposing force is applied to the stripper blade in dependence upon the magnitude of the measured force. By so doing, the net force directing the stripper blade towards the feed roller is maintained constant.

Abstract: A position detector to detect the fully open position of a valve gate pin in a gate valve controlling the flow of molten plastic material to a die cavity includes a sensing member which has a DC voltage impressed thereon and which is electrically isolated from the valve gate assembly. An extension of the valve gate pin contacts the sensing member when the valve gate pin is in its fully open position to short the impressed voltage and thereby indicate a fully open condition.

Abstract: A method and apparatus for injecting molten material such as molten metal into a die cavity under pressure from a shot cylinder wherein a valve arrangement is provided which prevents undesirable pressure spikes in the die cavity during injection of molten material, and which effects rapid pressure buildup in the die cavity during solidification and curing of the molten material. The valve arrangement is operative to effect a regenerative or counterforce mode in the shot cylinder which limits the force applied during injection of molten material into the die cavity so as to substantially reduce pressure spikes, the regenerative mode being terminated in response to a predetermined pressure within the die cavity indicating that the die cavity is full.

Abstract: An apparatus for continuously shaping and extruding concrete or other moldable material as a decorative curbing. The apparatus is operable by one person at high extrusion velocity, negotiates short radius serpentine curbing paths, and is maneuverable in tight spaces because of side-to-side and vertical adjustment features, and a short "wheel base". Moldable material is placed in a hopper and flows into an auger which compresses, mixes and extrudes the material through a shaped, non-flanged mold into the desired curb bed. A fueled engine or electric motor drives a hydraulic pump to pressurize hydraulic fluid. The pressurized fluid drives a hydraulic motor which turns the auger. The speed is controlled by simply setting a fluid flow valve.

Abstract: An apparatus for extruding plastic materials, particularly plastic explosives or propellants, has a casing, at least one pressing member moving therein, e.g. a rotating extruder screw and a shaping retainer plate terminating the casing at the outlet side, which is fixed to the casing and can be raised therefrom if an excessive overpressure occurs. So as to ensure rapid raising and a rapid release of the overpressure when a safety hazard occurs, the retainer plate is fixed to the casing by a mechanical or a gas pressure spring, whose spring tension is adjustable. It is also possible to provide a hydraulic pressure directed in opposition to the spring and by which the retainer plate can be raised in random manner from the casing.

Abstract: A paste-dispensing apparatus for bonding machines, etc., which constantly dispenses a fixed amount of paste, glue, etc. regardless of the amount remaining in a syringe and detects the amount of paste remaining in the syringe, including an air supply which supplies air under positive pressure to the syringe, a dispensing valve installed between the syringe and the air supply and connected to the syringe via a first pipe and to the air supply via a second pipe so that the syringe and the air supply communicate with each other when the paste is discharged, a first pressure sensor which measures the pressure inside the first pipe, a second pressure sensor which measures the pressure inside the second pipe, and a controller. Pressure values measured by the first and second pressure sensors are supplied to the controller so that the controller outputs a signal which actuates the dispensing valve so that the first and second pipes communiate when the paste is discharged.

Abstract: A mold fill coupling combined with a pinch fill valve and an overflow valve permits filling of a mold at one station and disconnecting the fill valve without rotating the mold.

Abstract: A mold fill coupling combined with a pinch fill valve and an overflow valve permits filling of a mold at one station and disconnecting the fill valve without rotating the 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: A control apparatus for an injection molding machine injects a melted resin within a housing into a cavity of a mold through a nozzle section of a nozzle at a housing and by movement of a screw. A nozzle opening changing mechanism variably changes a throttled path area of the nozzle while a mold temperature sensing mechanism sensing the temperature of the mold. A control mechanism controls the nozzle opening changing mechanism in accordance with the sensed temperature of the mold temperature sensing mechanism.

Abstract: Apparatus for manufacturing a multicolored aerated confection product utilizing individually adjustable multi-orifice extrusion systems.

Abstract: Shaping device and method for shaping extrudable material including at least one extrusion nozzle for feeding extrudable material and being supported in a carrier common to all nozzles, motors for moving either the carrier or a movable support surface for receiving extruded material directly from the nozzles and a programmable computer for controlling the motors.

Abstract: A method of manufacturing a multi-layer resin material by employing a plurality of kinds of thermoplastic resin. Resins for inner and outer layers are supplied into a feed block of a feed block type T-die coextrusion apparatus where they are laid up another, and are then sent to the T-die side. In this case, a resin which is practically similar to the resin for the outer layer is supplied as an auxiliary resin to both lateral edges of the multi-layer resins within the feed block. Thus, the sheet extruded from the T-die slit has lateral edges which are made of a single resin.

Abstract: An apparatus for forming an egg roll. A sheet of dough is placed on a conveyor belt, with a corner of the dough pointed in the direction of movement of the belt. An egg roll filling is placed on the dough with the filling extending transversely to the direction of movement of the conveyor belt. The leading corner of the dough is reversely folded over and around the upper surface of the filling by a deflector. The dough is creased along its length of movement on both sides immediately outwardly of the ends of the egg roll by O-ring belts guided about pulleys. The opposite corners of the dough, which extend transversely to the direction of movement of the conveyor belt, are folded about the creases inwardly over the filling and the opposite corners of the dough are pressed downwardly toward each other by belts which gradually bend from a horizontal support surface to an inwardly inclined belt surface. The corners of the dough are pressed to their final positions by disks.

Abstract: In a fluidized-bed granulating apparatus for continuously producing granular particles from a powdered raw material, while a granulated product is continuously exhausted in a substantially constant amount from the bottom or bottom side wall of a fluidizing chamber and is introduced into a classifying section where the granulated product is classified by classifying means thereby selecting and delivering the granules granulated to particle size greater than the desired size and returning ungranulated material to the fluidizing chamber, the pressure drop of the fluidized bed is detected to adjust the charging rate of the powdered raw material into the fluidized bed and the moisture content of the material to be granulated in the bed is detected to adjust the feed rate of a binding liquid, thereby producing a granulated product of a desired particle size.

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

Abstract: An injection molding machine of the present invention has a flow rate control device (11) located between an injection screw (2) mounted inside a housing (1) so that it may be rotated freely and reciprocated freely and an injection nozzle (12) mounted in the leading end of the housing (1) so as to inject the molten resin into a cavity (14) of a mold (13). The control device serves to control the rate of flow of the molten resin from the injection screw (2) to the injection nozzle (12). The flow rate control device (11) cooperates with an injection speed control device and a dwell pressure control device installed separately to control the flow rate and speed of the molten resin thereby making it possible to control the injection speed rapidly, and with a high accuracy and with an excellent response.

Abstract: A method of and apparatus for controlled coextrusion of plastic bag making film and a reclosable fastener male profile comprising extruding the film through an orifice with which is aligned a profile orifice and one or more alignment rib orifices as well as one or more stablizing ridge orifice cooperating with the profile and/or rib orifices. The resulting extruded product provides a bag making material comprising a plastic film carrying the zipper profile and with one or more alignment ribs in spaced parallel relation to the profile, with a reinforcing ridge or ridges effecting stabilizing beam effect in respect to the alignment rib or ribs and/or the profile during the processing of the extruded product into its final bag making material form. The extrudate for the film and the extrudate for the alignment rib or ribs may be derived from separate sources so that different plastics of different density or characteristics may be supplied to the alignment rib or ribs.

Abstract: This invention relates to a method and apparatus for improving not only the quality of the production of molded foamable thermoplastic resin particles converted into fusion-bonded materials but also the output by protecting the resin from atmospheric pressure by pressurizing the particles and heating the particles to soften the same.

Abstract: A method of molding pre-foamed synthetic resin particles is described, which comprises increasing the pressure in a mold cavity with a pressurized gas, charging the mold cavity with pre-foamed synthetic resin particles as they are compressed with a gas pressurized to a pressure higher than the pressure in the mold cavity and heating the charged pre-foamed synthetic resin particles with steam so that they are fused together or expanded and fused together to form a foamed molded article, wherein a pressure detector is provided in a conduit for conveying the pre-foamed synthetic resin particles into the mold cavity as they are carried by the pressurized gas or at an inlet portion of a charging port leading to the mold cavity, and the supply of pre-foamed synthetic resin particles into the mold cavity is stopped when the pressure detected by the detector exceeds the pressure in the mold cavity by a predetermined amount.

Abstract: The present invention provides a novel edge-laminating apparatus, in which an edge-laminating stream exiting from an edge-laminating flow channel, is driven by flow pressure into an edge of another stream. Also provided is a novel process for forming an edge-laminated stream, and for forming an extruded product.

Abstract: An apparatus for reducing wastage during the start-up phase of extrusion device used to produce extruded profiles such as tread strips for vehicle tires from a plurality of mixtures. Each of a plurality of extruders extrudes one component of the profile and is provided with its own drive motor. The outlets from the extruders communicate with a template member having flow channels formed therein which communicate with the outlet ends of the extruders and which lead into a common extrusion port. Pressure sensors are positioned adjacent to the outlet of each extruder. These pressure sensors and the drive motors for each extruder are operatively connected to a control device which has stored therein predetermined desired pressure levels for each extruder. The drive motors for the several extruders are actuated and the pressure of each is monitored and compared with the predetermined desired pressure for each extruder.

Abstract: In a plastic processing machine (injection moulding machine) the amount of working medium to be supplied to the hydraulic drives and to the injection cylinder and the clamping cylinder is regulated to control the adjustment rates via a quantity control of an adjustment pump. The setting of the pressures necessary at the drives is effected in contrast via a directional valve which controls the fluid paths to one of the drives and which is adapted to be connected to the tank via a regulatable throttle point governing the pressure. This simplifies the apparatus expenditure for the pressure control of such a machine.

Abstract: An automatic dough cutter that is preferably for use in a mall type cookie store and includes pneumatically operated moving parts. The dough cutter is contained within a single housing that includes a vessel wherein the dough is deposited and is acted upon by a piston traveling therein to extrude that dough through a nozzle, the invention including an oscillating knife that is operated to swing a blade at set intervals through that extruded dough column cutting end sections therefrom. All of which components including covers, a chute, the knife blade, piston, vessel, dough conveying pipe and nozzle that contact the dough are removable for cleaning so as to limit a possibility of bacteria growth and contamination.

Abstract: An improved, low cost, energy efficient extrusion device and method for processing of cellulose, hemicellulose, and like fiber-bearing materials is described which includes a pretreatment extrusion zone and a reaction extrusion zone separated by a pressure sensitive variable die. The method hereof includes the steps of extruding cellulosic material through the pretreatment zone at an elevated pressure and temperature, passing the material into the reaction zone where it is mixed with an acid and is processed at a lower pressure and temperature than in the pretreatment zone, and extruding the material through a final extrusion die. The surging and blowing usually experienced with extrusion of fibrous material is drastically reduced by the unique construction of the extruder die members. The cellulosic material may be hydrolyzed to simple sugars in accordance with the method and apparatus hereof with a minimum of acid degradation of the extrusion equipment.

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: A hydraulic control system for the operation of three linear and one rotary hydraulic drive assemblies of the injection unit of an injection molding machine, comprising a variable delivery pump supplying drive fluid at a constant pressure gradient to several supply lines controlled by two control units which are arranged in parallel and feature proportional P/Q valves and pressure transducers, a smaller pressure maintenance pump which is controllable by a third proportional P/Q valve and switchable into one of the supply lines, and a hydraulic accumulator for the temporary supply of a large quantity of drive fluid. The proportional P/Q valves convert automatically from their flow rate programs, controlled by displacement-to-voltage converters on the injection unit, to pressure programs controlled by the pressure transducers.

Abstract: The invention relates to injection molding and is provided with a heating cylinder, an injection nozzle disposed at the forward end of the heating cylinder, a resin feed means, such as screw, which feeds molten resin to a portion in the vicinity of the forward end of the heating cylinder. Also provided is a piston means, such as a plunger, which has a stop valve mechanism that closes when it is moved in an injection direction and is opened when it is moved in a counterinjection direction and injects molten resin, fed to a portion in the vicinity of the forward end of the heating cylinder, into a cavity through the injection nozzle, whereby, through driving of the resin feed means and the piston means, charging of molten resin into the forward end of the heating cylinder and injection of the molten resin into a cavity are carried out partially concurrently.

Abstract: A method of reducing wastage during the start-up phase of an extrusion device used to produce extruded profiles such as tread strips for vehicle tires from a plurality of mixtures is disclosed. The extrusion device comprises a plurality of extruders each extruding a component of the profile and each extruder has its own drive means. The outlets from the extruders communicate with a template member having flow channels formed therein which lead into a common extrusion port. The drive means are actuated simultaneously and the pressure of each of the components is monitored in the outlet region of each extruder. These pressures are compared with a pre-determined desired pressure by a control device, which device switches-off the appropriate drive means as each desired pressure is attained. When all desired pressures have been attained, all of the drive means are re-actuated simultaneously by the control device.