Abstract: An apparatus for processing feed stock into a thixotropic state. The apparatus includes a barrel with first, second and nozzle sections. The first, second and nozzle sections are connected together and include surfaces that cooperatively defining a central passageway through the barrel. The first section is constructed of a first material, the second end section is constructed of a second material and the nozzle is constructed of a third material. The first material exhibits a greater resistance to thermal fatigue and thermal shock than the second material while the nozzle section includes a bushing which inhibits heat transfer to the die, precluding excessive molding pressures and cycle times. The apparatus also includes a preheater for preheating the feed stock before entry into the barrel, a thermal gradient monitoring system, a novel robust nozzle construction, and a two-stage embodiment of the apparatus.

Abstract: An injection unit for injection moulding machines comprising a plasticizing cylinder and a plasticizing screw which is arranged rotatably therein and axially displaceably by a crank drive, wherein there is provided a drive motor (1) which selectively either rotates the plasticizing screw (2) or advances same by means of a crank (5) which is pivotably connected to a thrust rod (4), and wherein there is provided a further drive motor (8) which by way of a crank (10) drives a thrust rod (9) arranged in mirror image relationship in plan view in relation to the first thrust rod (4).

Abstract: An apparatus for processing feed stock into a thixotropic state. The apparatus includes a barrel with first, second and nozzle sections. The first, second and nozzle sections are connected together and include surfaces that cooperatively defining a central passageway through the barrel. The first section is constructed of a first material, the second end section is constructed of a second material and the nozzle is constructed of a third material. The first material exhibits a greater resistance to thermal fatigue and thermal shock than the second material while the nozzle section includes a bushing which inhibits heat transfer to the die, precluding excessive molding pressures and cycle times. The apparatus also includes a preheater for preheating the feed stock before entry into the barrel, a thermal gradient monitoring system, a novel robust nozzle construction, and a two-stage embodiment of the apparatus.

Abstract: A screw for an in-line screw type thermosetting resin injection molding machine comprises a resin kneading portion in a front end portion of a full-flighted screw. In the resin kneading portion, a groove having a crest portion and a trough portion formed spirally in a circumferential direction, and a step portion. A difference between a radial dimension of the step portion and an outermost radial dimension of the crest portion is 10% to 60% of a difference between the outermost radial dimension of the crest portion and an innermost radial dimension of the trough portion. The axial length of the resin kneading portion is 0.5 to 2 times as long as the outer diameter of the full-flighted screw, or 0.5 to 2 times as long as the pitch of the full-flighted screw.

Abstract: A charging barrel and screw as well as their associated components for carrying out the processes of plasticization, injection and pressure maintaining of the polymer are all disposed in the inner cavity of a metal moving body driven to rotate pulsatorily by an electromagnetic winding. At the time when the screw and the metal moving body are simultaneously rotating pulsatorily, the screw is at the same time making axial pulsative displaments, so that the processes of plasticization, injection and pressure maintaining are all carried out in a periodic oscillating state. This type of injection moulding method and apparatus have the advantages of small volume, light weight, low manufacturing cost, low energy consumption, low noises, wide adaptability to materials and excellent quality of the moulded products.

Abstract: A pre-plasticizing type injection molding machine includes a plasticizing device for plasticizing a molding material supplied from a hopper by a first screw disposed within a first barrel, an injection device 8 for measuring a molten resin supplied from the plasticizing device 5 and for injecting the measured molten resin by a second screw disposed within a second barrel. A switching valve is provided in a resin passage between a resin outlet of the plasticizing device and a resin inlet of the injection device, and an accumulation device is provided for housing a pushing plunger having a stock chamber communicated with the resin passage at a position between the switching valve 10 and the resin outlet of the plasticizing device.

Abstract: In a method for operating a drive, in particular for an injection system of an injection molding machine, wherein a spindle (7) is provided drivable by a first electric motor (14), on which spindle a nut (15) is borne which is drivable by a second electric motor (20) and borne so as to be axially non-displaceable, a translation movement of the spindle (7) is brought about by driving the nut (15) by means of the second electric motor (20) or by driving the spindle (7) by means of the first electric motor (14). To increase the dynamics of the driving during the conveyance of an acceleration or, respectively, retardation ramp of the translation movement of the spindle (7) by means of one of the two electric motors (14, 20) the other electric motor (20, 14) is briefly driven in that rotational direction which supports the acceleration or, respectively, the retardation of the translation movement of the spindle (7).

Abstract: A screw apparatus comprises a melting extruder for melting a resin; a screw unit for kneading molten resin and reinforcing fibers to obtain a reinforcing fiber-containing molten resin and supplying it; and a mixer in which at least a part of the reinforcing fibers attach to the molten resin which is extruded from the melting extruder and flows down owing to gravity in an open space, and then the reinforcing fibers and the molten resin are fed into the screw unit.

Abstract: An extruder apparatus for use in straining refining, separating and extruding thermo-plastic and rubber like process material includes a rotor positioned in barrel with a barrier section located between two barrel sections. The portion of the rotor in the barrier section has a smooth surface and the smooth surface and the barrier section are conical. The barrier section includes receiving and sending grooves separated by barriers. All material passing through the barrier section passes between the barriers and the smooth rotor section. Longitudinal movement of the smooth rotor section changes the clearance between the barriers and the rotor to restrict flow between a maximum flow and a closed position. The clearance can be adjusted so that different materials can be extruded in the same apparatus and adiabatic flow can be achieved. Discharge ports at the downstream end of the receiving grooves port rejected material to atmosphere.

Abstract: The disc screw extruder employs a free-floating operating member that is so constructed as to attain substantially stable axial positions within the extruder chamber. The disc component cooperates with confronting surfaces to define inner and outer throat zones, extending along the lead-in and lead-out sections of the disc component, the thicknesses of the flow paths through both of the throat zones decreasing in the outward direction of the extruder.

Abstract: The extruder screw drive has a first and a second motor, a screw mechanism connected to the first motor and to the extruder screw for translating it in the extrusion cylinder, and a slide mechanism connected to the second motor and to the extruder screw for rotating it in the extrusion cylinder. The screw mechanism and the slide mechanism are coaxial and partially fit into one another to provide an axially compact arrangement. The motors can be hollow shaft electric motors axially aligned together, and pressure regulated hydraulic axial force can be added to the extruder screw during plasticating as it retracts due to increased volume of plastic at an output end of the extrusion cylinder.

Abstract: A screw head for an injection molding machine is mounted to a distal end portion of a screw, and includes a trunk portion and a screw portion, and an undercut portion formed between the trunk portion and the screw portion, wherein a relationship between a shaft diameter e of the undercut portion and a nominal diameter f of the screw portion is defined as:0.74f.ltoreq.e.ltoreq.0.85fand a relationship between the nominal diameter f of the screw portion and a radius r of curvature of the undercut portion is defined as:0.5f.ltoreq.r.

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

Abstract: A screw rotating and advancing device for an injection molding machine, in which a movable pressure plate is provided with a servomotor to drive a ball screw in association with a ball nut provided at a rear fixing plate, so that the movable pressure plate homogeneously drives a screw shaft passing through a front fixing plate to perform the operations of injection, holding pressure, and measuring back-pressure; and accomplish a close-loop control of the pressure of molding material by using a force sensor. The other side of the movable pressure plate is provided with a servomotor to rotate the screw shaft, so that the rotational speed of the screw shaft can be precisely controlled. Furthermore, the present invention includes a pre-load system including at least two pre-loaded hydraulic cylinders, at least tow pistons and a communicating tube to balance the pressure difference between the prepressurized hydraulic cylinders.

Abstract: A downsized screw driving gear supports a heavy reaction force from a screw used in preplasticization type injection molding machine. Motor rotation is directly transmitted to the screw during plasticizing by a piston member. Reaction forces from the screw are supported with a thrust bearing arranged in a hydraulic chamber, while the radial load of the piston member is supported with bushes. Hydraulic pressure is supplied to the hydraulic chamber in the injection process to advance the screw with the piston member, disconnecting a path to the injection chamber. Oil supplied from the hydraulic chamber immerses the thrust bearing and penetrates to the sliding faces of the bushes.

Abstract: A plasticizing unit is provided for palsticizing material which is subsequently supplied to an injection molding press. The unit includes a screw disposed in a barrel which has an inlet, an outlet, a reservoir zone portion, and a plasticizing zone portion. The plasticizing zone portion of the barrel and the screw each have a continuous helical groove of opposite hand as the other groove and the grooves transfer material therebetween to effect plasticizing of the material. The reservoir zone portion of the barrel receives a shot volume of material which has been plasticized during passage through the helical grooves of the barrel and the screw. A volume displacement member which is axially movably disposed in a bore of the screw is movable within the reservoir zone portion to selectively control the shot volume of plasticized material received in the reservoir zone portion.

Abstract: A plastics processing machine is associated with an internal mixer. Thermoplastic material is separately melted in the plastics processing machine and injected into the mixing chamber of the internal mixer, where it is mixed with fillers, caoutchouc or the like.

Abstract: An in-line screw type injection molding machine having a screw in a heating cylinder. The screw is driven and rotated by a motor to charge a feedstock resin into the cylinder, the screw simultaneously undergoing retracting movement to allow the molten resin to be stored in the cylinder, and is driven and advanced to inject the molten resin.

Abstract: In an injection unit of an in-line screw type injection molding machine, a screw is provided rotatably in both normal and reverse directions within a heating cylinder. The screw is periodically reversed in a charging stroke with the period of normal rotation being longer than that of reverse rotation, whereby a resin material is kneaded and plasticized. As a result, the resin in a melting and pooling zone (flow zone) between the inner wall of the heating cylinder and the outer peripheral wall of the screw is effectively moved back and forth and hence plasticized and molten into a uniform molten resin.

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 feed device (11) for a continuous mixer (12) for rubber and plastics materials. The feed device comprises a hopper (14) having a reciprocable plunger (16) located in the hopper to force material into the inlet passageway (15) of the continuous mixer. The plunger (16) is rotatable during its retraction and has an archimedian screw portion (17) that feeds material into the inlet (15) during the retraction movement of the plunger.

Abstract: A drive apparatus useful in screw injection molding apparatus is disclosed. The apparatus is particularly useful when both axial and rotational movements are required because the invention discloses a construction that reduces the wear attributed to sealing gaskets of relatively large diameter which are subjected to rotational stresses and relatively high linear velocities. In the injection molding embodiment described in detail, the extruder screw is rigidly attached to a drive piston that has both axial and rotational movements. Concentric to that drive piston is a drive cylinder tha has only axial movement yet is connected to the drive piston such that the piston is able to rotate freely relative to the cylinder but may move axially only when the cylinder moves. Thus, the sealing gaskets of the drive cylinder are free of rotational stresses which extends the useful life of the sealing gaskets.

Abstract: An extruder for plastic materials wherein an end portion of the extruder screw extends from the extrusion cylinder and is coupled to the adjacent end portion of the drive shaft by a U-shaped coupling element which partially surrounds the two end portions and by a claw-shaped coupling element which overlies flats on the end portions of the extruder screw and drive shaft and is secured to the U-shaped coupling element by a screw. The flat on the end portion of the extruder screw is inclined with reference to the axis of the extruder screw if the shaft is to transmit torque to and to reciprocate the extruder screw. A U-shaped clamping device is used to secure the U-shaped coupling element to the end portion of the shaft.

Abstract: In order to obtain an injection drive apparatus which is low-priced, can produce a great output torque, and has a satisfactory acceleration/deceleration characteristic, in an injection-molding machine which performs injection by driving a screw by means of servomotors, one or more ball screws (7), used to drive a screw (2) in the axial direction, are driven by means of a plurality of servomotors (M1, M2), a position detector (P1) for detecting the screw position is provided only for one servomotor (M1), and the servomotors (M1, M2) are provided individually with power amplifiers, which are controlled by means of one control circuit so that the individual servomotors (M1, M2) are controlled in synchronism with one another.

Abstract: A large-output injection/measurement mechanism of an injection molding machine, which uses measurement and injection servo motors as its drive source. A plurality of ball screws are rotatably provided between front and rear plates of the injection molding machine and are coupled to the injection servo motor. Ball nuts engaged with the plurality of the ball screws are fixed on a pressure plate. The pressure plate is coupled to the measurement servo motor through a spline shaft and a rotational drive pipe spline-coupled thereto. The spline shaft is fixed on a screw sleeve rotatably fixed to the pressure plate. A screw fixed to the pressure plate is driven by the servo motors, thereby performing injection and measurement of a molding material.

Abstract: A plasticating unit having a channeled rotor rotating in an annular housing for processing plastic or polymeric material. The processed material is fed by a screw to a chamber which expands to receive a predetermined charge of material for injection into a mold.

Abstract: A screw-rotating/injection mechanism of an injection molding machine has a screw shaft (1) having a rear portion thereof connected to a drive shaft (1') which is rotatably fixed to a pressure plate (4). A nut (6) which is spline-coupled to a spline shaft (5) constituting a rear portion of the drive shaft (1') is driven by a screw rotating motor (M1) through a first transmission unit (9, 10, 13, 15) to rotate the screw shaft (1). A ball screw (8, 8') threadedly engaged with a ball nut (7, 7'), fixed to the pressure plate (4), is driven by an injection servo motor (M2) through a second transmission unit (11, 11', 14, 16) to move the screw shaft (1) forward, thereby performing injection.

Abstract: A jet-molding unit device adapted to use in attaching soles directly to uppers. The device comprises a mixing head with a worm gear therein, the worm gear having an axis and being in a gear mounting, and a magazine adapted to retain a plurality of worm gears. The device further includes an automatic gripping device for gripping the worm gear in the gear mounting at a point removed from the mixing head, removing the worm gear from the gear mounting and depositing the worm gear in the magazine, and removing a second worm gear from the magazine and inserting it into the worm gear mounting.

Abstract: An apparatus is disclosed for optimizing a method of producing a foam or expanded thermoplastic material, the material usually being mixed with a propellant. The apparatus comprises a filter unit which is disposed between and connects, a fusing and homogenizing extrusion device and a dynamic cooling device. The material is fed into the apparatus at one end of the extrusion device and passes sequentially through the extrusion device, the filter unit and the cooling device. Separate drive means are provided for the fusing and homogenizing extrusion device and the cooling device respectively. Both the extrusion device and the cooling device are disposed on a common longitudinal axis. The connections of the two devices to the filter unit is effected by means of flange mountings. The filter units also includes interchangeable filters which are traversed by the material. In the filter unit, the material flows through a conduit which flares conically outwardly from the filter to the inlet of the cooling device.

Abstract: The disclosure relates to a ram extruder including an extruder barrel having an extrusion die at one end and a hydraulic ram at the other end having a piston which is advanced along the barrel by the ram to displace material in the barrel through the extrusion die. To facilitate loading of the barrel a loading port is provided in the side of the barrel adjacent said other end of the barrel through which the barrel may be charged after retraction of the piston following an extrusion operation and a port closure device is provided to close the port after extrusion and evacuate air from the barrel prior to advancing the piston past the port to minimize the air contained in the barrel prior to the extrusion operation.

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: A mixing apparatus for mixing material in a mixing chamber (19) is provided. A rotor (21) is mounted on a shaft (15) which is both rotated and moved axially simultaneously. Motors (13) through gears (14,16) rotate shaft (15) and rotor (21)' and hydraulic cylinders (9) move the rotor (21) axially. Motors (13), the gears (14,16), the rotor shaft (15), and the rotor (21) are all supported by carriages (11) which slide on horizontal rods (7). The rotor (21) has internal radial mixing slots (39). A rotor cleaning apparatus is provided which includes two separable collar parts (41, 41') having a plurality of cleaning prongs (43) in the form of a comb. The collar parts (41, 41') are supported by comb carriages (45, 45') which move the collar parts (41, 41') radially from a non-use position into cleaning position. When the rotor cleaning apparatus is in cleaning position, the cleaning prongs (43) are in alignment with the radial slots (39).

Abstract: An injection assembly for an injection molding machine in which an auger is disposed in a bore formed in the molding machine and defines therewith an annular passage for receiving the material to be injected. A valve assembly is operatively connected to the auger and includes internal passages communicating with the annular passage and adapted to communicate with the mold. A sealing ring extends around the valve with the outer diameter of the sealing ring being in a sealing relation to the bore downstream of the annular passage. The inner diameter of the ring is slightly greater than the outer diameter of the valve to permit rotation of the valve relative to the sealing ring. As a result, upon rotation of the auger and the valve, the material is advanced along the annular passage and the internal passages while the sealing ring remains stationary and provides the sealing function.

Abstract: An injection apparatus for plastics materials containing glass reinforcing fibers includes a fixed sheath 5, a movable sheath 7 slidably disposed within the fixed sheath, a mixing screw 9 rotatable within the movable sheath, a pressurized supply hopper or funnel 8 for feeding material to the mixing and conveying screw, and a piston/cylinder unit 14-16 for advancing the movable sheath and screw to inject a charge of plastics material within a chamber 26 to a mold M. The supply funnel is coupled to the movable sheath and includes a compression plate 35 controlled by a jack 38 mounted on a sliding plate 39, whereby the compression plate may be retracted into abutment with the sliding plate and laterally withdrawn to enable the reloading of the supply funnel.

Abstract: Method for the forming of thermoplastic and/or elastomeric resins, in which method use is made of a melt torpedo in the melting zone of a processing machine having a screw. The torpedo has grooves and ridges with a helix angle of preferably between 55.degree. and 75.degree.. The final melt temperature, that is the temperature at the beginning of the outlet of the processing machine is chosen lower than that applied in the same processing machine without a torpedo.

Abstract: A plasticizing screw which has a feed zone, a plasticizing zone, and a metering zone. In the feed zone the screw has a single flight which forms a feed channel and which feeds solid material to the plasticizing zone. At the beginning of the plasticizing zone, a secondary or barrier flight is introduced to divide the feed channel into a solids channel and a melt channel. The solids channel is cut deeper than the feed channel at the beginning of the plasticizing zone so as to be able to accommodate all of the solids contained in the feed channel even though its width is substantially less than the width of the feed channel. The depth of the solids channel gradually decreases as it approaches the end of the plasticizing zone.The depth of melt channel is shallow at the beginning of the plasticizing zone and gradually deepens as it approaches the end of the plasticizing zone so as to accommodate all of the plasticized material.

Abstract: Hydraulic controls for the injection unit of an injection molding machine of the type which has tandem supporting bridges riding on two guide rods and hydraulic cylinder assemblies surrounding the rods, the cylinder assemblies in the rear supporting bridge which control the movements of the plastification screw being convertible from single-acting cylinders to double-acting cylinders with a differential piston, for the selective connection to a first hydraulic control system which has presettable proportional-response control valves for the adjustment of the pressure and flow rate of the hydraulic fluid, or to a second hydraulic control system which provides a continuous electronic control input to a servo-valve, adjusted by an electronic feedback loop with pressure transducers. The conversion involves the exchange of a piston and a cylinder cover in the two cylinder assemblies of the rear supporting bridge.

Abstract: A plasticizing screw of an injection-molding machine, axially movable in an extruder barrel, is driven by a tubular input shaft via a splined quill partly retractable into the shaft with which the quill is coupled through an internally and externally splined bushing. Another such bushing is removably seated, for possible replacement by a similar bushing of different inner diameter, in an internally splined cup-shaped head of the quill and engages the splined rear end of the screw. The quill head rests via a thrust bearing against the front end of a nonrotatable tubular piston coaxially surrounding the quill and entering by its rear end an annular cylinder which is hydraulically connected with a pressure accumulator including a gas cushion. The accumulator creates a back pressure by which molding material, plasticized by the screw during the preceding phase in which the screw was repressed into a rear position, is introduced via a check valve into a shooting pot alongside the extruder barrel.

Abstract: A plasticating apparatus operates continuously to plasticate material which is delivered intermittently to a molding device, the plasticating apparatus including a first screw conveyor which rotates in a barrel, a backfeed passage within the first screw conveyor and a second screw conveyor in the backfeed passage arranged to recirculate material in a circuit extending back through the backfeed passage. The first screw conveyor reciprocates axially so that during periods of non-delivery of plasticated material, the capacity of the circuit is increased to accommodate the accumulation of added plasticated material generated by the continuous rotation of the first screw conveyor.

Abstract: Methods and apparatus for marbleizing molded parts produced by screw extruder machines. Liquid colorant is advantageously injected at a comparatively high pressure into a melt containing portion of the machine between the screw and its housing, where the melt is either completely molten or more than fifty percent molten.

Abstract: An improved injection unit for a plastic materials injection molding machine, having a plastification cylinder and a cooperating rotatable and axially movable plastification screw, both supported and guided on tie rods by means of a carrier bridge, the plastification cylinder being axially adjustable and clampable in relation to the carrier bridge by means of a threaded adjustment nut cooperating with a threaded end portion of the plastification cylinder and a central threaded clamping sleeve cooperating with a stationary thrust plate, the latter being permanently secured to the carrier bridge.

Abstract: In a method of and apparatus for controlling a plasticizing process of a resin of an in-line screw-type injection molding machine, a position of the screw is continuously detected in accordance with the movement thereof and a control function is determined by a back pressure of the screw which is compensated for by taking into consideration such as resin heating energy and shearing energy, which determine a temperature distribution of a resin to be injected. The operating condition, particularly the number of revolutions and the back pressure of the screw, is controlled on the basis of the screw position so as to make uniform the temperature distribution of the resin.

Abstract: A method of and apparatus for melting a thermoplastic material in order to obtain an at least nearly homogeneous molten mass, according to which a granular or similar material is melted while it is being transported e.g. by a screw conveyor through a space between a housing of circular cross section and a body rotating in the housing. The transfer of heat to the granular or similar material takes place over at least an axial section of the space between the above mentioned housing and the rotatable body. This space is divided into alternating inlet and discharge channels by first ridges fixedly connected to the rotating body over the above mentioned distance and extending along the inside surface of the housing so as to at least nearly block the passage of molten material, and by second ridges respectively arranged between the first ridges and extending at least substantially parallel to the first ridges while being fixedly connected to the rotating body.

Abstract: Methods and apparatus for marbleizing molded parts produced by screw extruder machines. Liquid colorant is advantageously injected at a comparatively high pressure into a melt containing portion of the machine between the screw and its housing, where the melt is either completely molten or more than fifty percent molten.

Abstract: A mixing apparatus for continuously preparing pulverous to granular thermoplastic synthetic material. The mixing apparatus includes a tubular, rotatably mounted horizontal container, on the inner surface of which mixing instruments or tools are attached. An inlet and outlet for the material to be mixed are respectively located near the ends of the container. A shaft is rotatably arranged about the axis of the container and extends at least over the entire length of the container. Mixing instruments are likewise attached to the shaft. The mixing instruments, in the region between the inlet and outlet, comprise a plurality of sections of single or multi-threaded worms which extend in the radial direction from the shaft to the inner surface of the container. These sections are adjacent to and spaced from one another, and are alternately mounted to the shaft and to the inner surface of the container.

Abstract: A plasticizing and melting apparatus for granular synthetic plastic material has a heatable cylinder one end of which has an inlet opening for reception of granular material from an adjustable feeding unit which includes a shaker. The cylinder surrounds a rotary feed screw having a material advancing section in the region of the inlet opening, a first material densifying section immediately downstream of the advancing section, a collar which defines with the cylinder a narrow annular shearing gap immediately downstream of the first densifying section, a pressure relaxing section immediately downstream of the collar, and a second densifying section immediately downstream of the pressure relaxing section. The cylinder has one or more gas evacuating apertures which connect the interior of the cylinder with the atmosphere in the region surrounding the pressure relaxing section.

Abstract: A process for admixing additives to plastics and simultaneously removing volatile constituents in a horizontal devolatilizing extruder. Taken in sequence in the direction of flow, the additives are first introduced into the devolatilizing extruder from above, and the plastic melt, solution or dispersion is then introduced from below, while the bulk of the volatile constituents are withdrawn from the devolatilizing extruder at an orifice located vertically above the point at which the plastic is fed in. The process permits the removal of volatile constituents with simultaneous admixture of additives during aftertreatment of plastics, in a single step and at very high throughputs.

Abstract: The charge forming barrel has a screw slidably and rotatably received therein, and the screw is specially suited for successively forming a mottle charge, a valve stud being mounted on the forward end of the screw, and this stud cooperating with a ring shaped non-return valve to close off rearward flow of the plasticized ingredients comprising the charge. The valve closes in a sliding or shearing action which avoids the propensity for such pellets to prevent the full closure of the non-return valve during the period of the cycle where a charge is injected into the mold cavities, and prior to forming of the next succeeding charge.

Abstract: The instant invention relates to a continuous process for the hydrolytic degradation of plastics wherein a hydrolyzable material is introduced with water into a screw machine, and is subjected therein to a temperature of 100 to 300.degree. C, and a pressure of 5 to 100 bars for 2 to 100 minutes. The invention also relates to an apparatus useful in conducting the process.