Abstract: A process for removing the screw from the screw cylinder of a screw-type injection molding machine and a screw-type injection molding machine of a corresponding configuration, having a base frame for receiving an injection unit which comprises a screw cylinder (1), a screw which is rotatable and axially displaceable in the screw cylinder and a drive device (2) for the screw, which is arranged axially behind the screw cylinder. The screw cylinder (1) is releasably connected to the drive device (2) and is pivotable, independently of the drive device (2), about a pivot axis (6) which extends vertically at a spacing in front of its rear end. The screw cylinder (1) and/or the drive device (2) are arranged to be movable separately from each other on the injection molding machine in the axial direction of the injection unit in order for the rear end of the screw to be pulled out of the drive device (2) after the connection has been released.

Abstract: A plasticizing screw for an injection molding machine or the like having one or more lands in a crest portion of a screw flight to prevent the screw flight from coming into contact with a cylinder wall surface when the plasticizing screw is rotated during a molding operation. The land has a smaller diameter than that of a crest portion of the screw flight and is provided at the screw flight crest portion either between leading and trailing surfaces of the screw flight or extending from the leading edge of the screw flight. The land can also be provided as a plurality of circumferentially spaced-apart lands on the side of a front surface of the screw flight, or provided at a central portion between the leading and trailing surfaces of the screw flight.

Abstract: In a molding machine, the front end of a rotary screw is provided with at least one slot communicated with a metering section so as to make uniform the temperature of plasticized resin in a space in front of the rotary screw.

Abstract: The mass which is made flowable (rendered plastic) must be degassed on its way to the outlet. In order to make the degassing section free of pressure a diaphragm, through which the mass flows, is provided further upstream. The extruding helix is provided with at least one helical flute, the free flow passage of which is blocked, and the diaphragm is provided with an adjustable throughput area. The diaphragm can simply consist of two perforated disks, which are rotatable with respect to each other around their axes. Each perforated disk has a fixed throughput area. The holes of both perforated disks overlap more or less, or not at all. The throughput rate of the mass through the extruding device can therefore, according to the state or the kind of mass, be regulated independently of the rotation speed of the extruding helix. Different masses can be extruded with one and the same helix, in a way hitherto not possible. One can also use an extruding helix which is shorter than was hitherto possible.

Abstract: A portable apparatus adapted for use in filling chuck holes in paved surfaces with a sulphur-based material that has been heated to a plasticized condition. The apparatus includes an electrically heated furnace in which an auger is mounted for the purpose of moving a sulphur-based material through the furnace at a controlled rate (e.g., about 2 feet per minute), such that the material will be elevated to a temperature of above 305 degrees Farenheit (the melting point of sulphur) to produce a tenacious filler material. The furnace is heated by tubular resistance heaters that are bent in a spiral fashion around a mandrel, so that they may be placed in intimate contact with the exterior of a tube which constitutes the core of the furnace. The furnace is fed by a hopper that is mounted above the entry point for the auger, so that dry material may be fed--by gravity--into the furnace whenever a gate-valve mechanism is opened.

Abstract: An extruder, including a rotor and a barrel having a mixing or working section therein, in which all of the material being worked is in barrel grooves and is moved only in a circumferential direction by a smooth cylindrical rotor. The barrel groove consists of wide tapering in depth area, which starts deep and progressively decreases in depth to the downstream end where the depth is restrictive to oversize and viscous material. Well worked material passing the barrier is separated from and directed downstream, thus providing fast forward flow of the fluent phase material, minimizing the rework of already worked material and exposing the less worked material to extruder action. The tapering depth area coacting with the smooth rotor generates progressively high pressure, and an increasing shear rate along its length and thereby provides the ideal conditions for dispersing powdered chemicals into the polymer.

Abstract: The heating and cooling arrangement (3, 4) for an extrusion cylinder comprises a copper strip (4) bent aside at right angles at its ends (6, 7) and twisted by 45.degree., the middle portion (8) of which rests upon the extrusion cylinder (1) as well as a band-shaped flexible heating element (3) disposed over the middle portion (8). The cooling elements (4) are disposed on a cylinder section (b 5) at regular intervals over the whole periphery thereof. Two copper wires led through the end regions (9, 10) of the middle portions (8) of the cooling elements (4) fasten the same to the surface of the extrusion cylinder (1). The heating element has two outer metal sheets (15, 16), an insulating layer (17) lying therebetween, as well as heating wires (18). This heating and cooling arrangement can be disposed on as many sections of the extrusion cylinder (1) as desired and makes possible an individual cooling or heating of each section of the cylinder, which fact is important for very rapid extrusion processes.

Abstract: A rotor and stator mixing system has mixing-chamber recesses in the outer periphery of the rotor and inner periphery of the stator which are generally similar, arrayed in peripheral and axial rows and are mutually axially offset. The guide radius R of the semicircular ends of each elongated recess is also the trough radius thereof and the trough depth is less than this guide radius. The length L of the mixing chambers is three to four times the guide radius, the web width between the recesses of each circumferential row is less than half the guide radius and the shear gap width W is so selected that the shear velocity which is realized is sufficient for effective mixing by a shear action.

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: A process and an apparatus for continuously producing a rubber mixture. In the process, the constituents of the mixture are fed into a twin-screw extruder and are masticated and homogenized therein, with approximately 5% of the mixture being discharged and the remainder being recycled for further homogenization and for mixing with fresh batches of the constituents being fed into the extruder. The recycled mixture is circulated to and returned from a cooled, annular chamber dispersed exteriorly of the chamber of the twin-screw extruder, with the annular chamber having outflow and inflow passages communicating with the interior of the extruder.

Abstract: The apparatus is for the mixing and refining of rubber-like materials, either hot or cold feed, and some thermoplastic materials. It comprises an elongated cylindrical barrel member and an elongated rotor member, disposed coaxially in the interior of said barrel member. The rotor member is provided with a concentric bore, at its downstream end in which a stationary screw-like member is coaxially disposed. Means are provided for relative rotational movement of the rotor member, to the barrel member and to the stationary screw-like member in the treating and axial advancement of the process material. With such a construction, the barrel, rotor and screw-like members have a feed end, a forcing zone, a mixing and refining zone, a stationary screw-like member and discharge end, interposed between the ends of the apparatus. The rotor member of the forcing zone is provided with extrusion grooves or groove, capable of warming, pressurizing and transporting the process material to the mixing and refining zone.

Abstract: This invention relates to a process of producing sheets from thermoplastic resins and a screw used therefor. The resin extruder includes a cylinder and the screw. The resin is passed through a feeding section, a compressing section, a metering section, a mixing section, a shearing section and a stress relaxing section, which are successively positioned from a resin feeding side to a resin extruding side, and a molten film-shaped resin is extruded, and this film-shaped resin is passed in a co-current direction with cooling water and is cooled.

Abstract: A screw type, polymeric material extruder with an elongated body having a cylindrical bore with a hollow screw in the bore, the screw having external and internal threads. A cylindrical body is within the internal threads, and the screw with the wall of the bore and with the cylindrical body forms, respectively, an external material flow chamber and an internal material flow chamber. The cylindrical body can have channels for heating fluid and for additives or dyes. The screw can have openings for feeding one material to a single extrusion head with one mouth by way of both chambers, or the chambers can be supplied with the same or different materials which are fed by way of the chambers to an extrusion head with two mouths for applying the latter materials separately.

Abstract: Continuous strands of color concentrate are metered into the feed zone of a screw-melter polymer extruder where they are cut into pellets by the shearing action of the flights of a rotating screw against the extruder housing. These pellets are mixed within the extruder with a thermoplastic polymer to be colored and this mixture is then melted and extruded into a useful article, for example, a fiber for textile or carpeting end-use.Additionally, color concentrates can be first formed into continuous strands and stored conveniently on a spool for subsequent metering into the polymer extruder.

Abstract: For bonding particularly radioactive wastes into a binder, a transporting and mixing device is used which transports the mixture to a storage tank prior to the hardening. The wastes are transported into the mixing zone by gravity and aided by the conveyor helix which also imparts additional wall cleaning action through the dry conveyor zone. A single or multi-component binder is concurrently transported in a direction lateral to the mixing tool to the mixing zone. The mixture is conducted in a straight-line extension of the transport and mixing direction to an outlet to which the storage tank is connected.

Abstract: Extrusion machine and process, the machine having a barrel having a feed section for receiving solid extrusion material, and containing a screw for moving the solid extrusion material through a solids conveying section to a compression section of the barrel to generate heat and pressure to melt the extrusion material and force the melt through a downstream extrusion die. The solids conveying section of the barrel has a cross-section comprising a plurality of flat or slightly curved surfaces which extend substantially tangentially relative to the extrusion screw circumference, providing axial recesses which restrain the rotation of the solid extrusion material with the screw as it is moved axially into the compression section. The present machine and process causes plastic extrusion composition to be packed as a non-rotating mass to fill the solids-conveying and compression sections and increase the dead head pressure and extrusion output of the machine.

Abstract: This invention is directed to a worm shaft assembly used to move corrosive and/or abrasive material such is part of an extrusion device or a press. More particularly, it relates to the construction of flights, feed quills and intermediate rings or collars for mechanical presses and extrusion devices.

Abstract: Extrusion process and apparatus, the apparatus including an extrusion barrel having axial grooves which extend through the feed section and solids conveying section and disappear at the exit end of the compression section. The apparatus also includes a helical thread extrusion screw having a maximum channel depth in the feed section, which depth disappears at the exit end thereof. The process and apparatus causes plastic extrusion composition to be packed as a non-rotating mass to fill the solids-conveying and compression sections and increase the dead head pressure and extrusion output of the apparatus.

Abstract: The invention relates to a process for mixing a polymer composition using an internal mixer having rotors 18, 20 rotatably mounted in a chamber 12, a ram 28 by which pressure can be applied to material in the chamber 12, and temperature control for the mixer. Materials are introduced into the chamber 12 and, after introduction of all the materials, at least three mixing variables e.g. temperature, time and energy, indicating mixing quality are monitored and control variables e.g. rotor speed and/or ram pressure adjusted dependent on the monitored mixing variables to achieve previously defined targets or if all are not simultaneously achievable, the most significant target. Control is initiated when the ram has reached a predetermined position and when at least one preselected condition e.g. time, temperature or energy, has been achieved.

Abstract: This invention relates to a method and molding screw for injection molding. The molding screw has a fixed inner screw mounted within a rotatable and reciprocally movable outer screw. The outer screw is continuously rotated throughout the injection cycle to (1) counter the back flow of melt material around the screw, (2) subject the melt material surrounding the inner screw to a vigorous mixing action, (3) add additional thrust to inject the melt material into the mold, and (4) return the outer screw to its initial starting position. A rod-type electrical heater is internally positioned in the fixed screw to maintain the temperature throughout the melt material surrounding the inner screw at a substantially constant value which is substantially equal to the barrel temperature.

Abstract: An extruder screw designed to operate in a continuous diameter barrel-type housing having a variable flight width, helix angle and radical clearance along the length of the extruder screw to reduce extruder screw induced power consumption and stock temperature generation in the manufacture of linear low density polyethylene plastics.

Abstract: The present invention relates to a novel extruder screw and method for extruding low melt viscosity polymers which form an anisotropic melt phase. In a preferred embodiment, the method and apparatus according to the present invention employ a high rate of rotational speed of the extruder screw in combination with a relatively low compression ratio and a high volume rate of flow through a compression section in order to effectively extrude the low melt viscosity liquid crystalline polymers. The particular design of the screw is dictated by the unique rheology of the polymers which are difficult to effectively move along the helix of the screw due, in part, to the extremely low viscosity. Each dimension and each relative size of the various sections of the screw must be carefully controlled in order to effectively extrude the unique material.

Abstract: A kneader which comprises a main body, which forms a support structure, part of the main body constituting a support for a bowl or receptacle; a rotatable helix mounted on the main body so as to extend into the bowl or receptacle, the helix being connected to appropriate drive means which effect rotation of the helix about its axis in either a clockwise or counter-clockwise direction, the arrangement being such that when the helix is rotated in one direction material within the bowl is kneaded and when rotated in the opposite direction of rotation the kneaded material is lifted upwardly out of the bowl by the helix; the kneader being further provided with means for guiding the kneaded material over the edge of the bowl or receptacle so as to effect removal of the kneaded material from the kneader.

Abstract: A support for the discharge end of the barrel of a rotary extrusion machine includes a body having a two-armed cradle for receiving the barrel and a cover extending across the tops of the cardle arms defining an interior barrel-receiving opening. Three leaf springs extend around the interior circumference of the opening with an adjustable barrel-engaging set screw located in the center of each leaf spring. The leaf springs compensate for radial thermal expansion and contraction of the barrel held in the support.

Abstract: The outer periphery of a screw and the inside of a barrel of a screw type extruding or kneading machine are made of ceramics, to improve the abrasion and heat resistances thereof, so that the screw and the barrel will operate for a longer life time even if a hard material or a material containing a hard material is worked.

Abstract: Extruder screw having a feed section, compression section and metering section. The compression section includes two transition portions with a barrier flighted portion disposed therebetween. The screw reduces the power consumption and stock temperature of thermoplastic material.

Abstract: A plasticizing unit for an injection molding machine includes a plasticizing cylinder; a plurality of separately energizable resistance heaters arranged on the plasticizing cylinder; clamping sleeves surrounding the resistance heaters and oriented generally coaxially with the plasticizing cylinder; and clamping elements tightening the clamping sleeves for pressing the resistance heaters against the outer face of the plasticizing cylinder. There is provided a protective casing surrounding the plasticizing cylinder and being attached thereto. Each resistance heater comprises a flat-tube heater body including consecutive first and second length portions. The first length portion contains heating wires and has a helical course about the outer face of the plasticizing cylinder. The second length portion forms an end of the flat-tube heater body and is free from heating wires and contains the lead wires.

Abstract: The present invention relates to a novel extruder screw and method for extruding low melt viscosity polymers which form an anisotropic melt phase. In a preferred embodiment, the method and apparatus according to the present invention employ a high rate of rotational speed of the extruder screw in combination with a relatively low compression ratio and a high volume rate of flow through a compression section in order to effectively extrude the low melt viscosity liquid crystalline polymers. The particular design of the screw is dictated by the unique rheology of the polymers which are difficult to effectively move along the helix of the screw due, in part, to the extremely low viscosity. Each dimension and each relative size of the various sections of the screw must be carefully controlled in order to effectively extrude the unique 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 for use in an extruder barrel for plasticizing plastic material from a solid phase to a viscous form wherein the feed screw has a cylindrical core with a helical flight extending for the full length of the screw. A selected portion or portions of the screw's core has a polygonal cross section whose apexes are parallel to the axis of rotation of such screws to thereby more precisely control the plasticizing action of the plastic material, its viscosity and temperature while providing a thoroughly mixed and homogeneous melt.

Abstract: Disclosed is a screw extruder comprising a feed bush having a screw extruder coaxially mounted therein, and which, around its circumference, is provided with several longitudinally extending grooves distributed evenly in the circumferential direction. Adapters are disposed in the grooves which can be adjusted radially in the grooves relative to the extruder screw with the aid of adjustment mechanisms. Each adapter is connected to several bolts connected over the length of the adapter. The bolts pass through holes in the feed bush and are surrounded by helical springs, each of which is supported on the one side against a collar of the bolt and on the other side against a face of the hole. The bolts are of one-piece or two-piece design and may include at the outer bolt ends, rollers which are pressed against cam rings or a cam segment, which surround the extruder barrel in annular or semi-annular shape.

Abstract: An extruder (2) comprising an extruder barrel comprising a plurality of barrel modules (4), each provided with an inner lining material (16), and at least one plate (6) is described. Such an arrangement facilitates assembly and dismantling of the barrel for replacement of inner parts. In a preferred embodiment, a plate (6) having an opening (26) passing therethrough and comprising projections (30) extending into said opening, is interposed between each two adjacent barrel modules (4), the openings of the plates (6) and internal surfaces of the barrel modules forming a substantially continuous passageway which provides an extrusion chamber (3).

Abstract: A device is described which eliminates the pre-drying of particulate plastic prior to processing by an extrusion or injection molding machine. A tubular guide member directs particulate plastic under gravity into the feed inlet of the machine. During delivery, the temperature of the particulate plastic is raised with heated air flows to between about 150.degree.-200.degree. F. Suction is applied to the feed inlet of the machine to remove volatiles (primarily water) released when the temperature of the particulate plastic is increased by contact with the heated barrel and screw-drive of a machine. Temperature and suction controls permit selection of operating temperature and suction levels that ensure removal of volatiles prior to any extensive plasticization and transfer along the barrel which would otherwise preclude proper removal of volatiles.

Abstract: A device is described which eliminates the pre-drying of particulate plastic prior to processing by an extrusion or injection molding machine. A tubular guide member directs particulate plastic under gravity into the feed inlet of the machine. During delivery, the temperature of the particulate plastic is raised with heated air flows to between about 150.degree.-200.degree. F. Suction is applied to the feed inlet of the machine to remove volatiles (primarily water) released when the temperature of the particulate plastic is increased by contact with the heated barrel and screwdriver of a machine. Temperature and suction controls permit selection of operating temperature and suction levels that ensure removal of volatiles prior to any extensive plasticization and transfer along the barrel which would otherwise preclude proper removal of volatiles.

Abstract: An injection molding apparatus including a power transmission device is provided for axially moving a screw by a rotational force of a motor received through a first clutch. During non-injection/non-metering, the motor is driven to cause an energy accumulation device to accumulate energy through a second clutch. During injection, a driving force of the motor and the energy accumulated in the energy accumulation device achieve high-pressure, high-speed injection with good response characteristics.

Abstract: Blending reclaimed rubber buffing dust with tread rubber for tire retreading includes feeding buffing dust from a container through a discharge pipe into a hopper which receives the tread rubber horizontally in a ribbon form. An auger from the discharge pipe which is vertically orientated meters the buffing dust onto the tread ribbon in a predetermined measured quantity and in a direct feed, so as to affect a suitably blended rubber product for tire retreading.

Abstract: An apparatus and method are disclosed which greatly facilitate molding of plastic material in the form of structural foam. The invention contemplates the provision of a valve-like mixing nozzle assembly which is selectively operable to control the flow of plastic material into an injection mold. Significantly, the nozzle assembly includes a mixing turbine rotatably mounted in the flow path of the plastic material. Notably, the turbine is driven by the plastic material itself as the material is driven into the mold assembly, and thus desirably provides intense mixing of the material during injection. This mixing action can be advantageously employed for effecting dispersion and/or expansion of the blowing agent carried by the plastic material for greatly enhanced control and flexibility in molding structural foam articles.

Abstract: A check valve at the end of a plastifying worm for an extrusion or injection molding machine comprises a valve ring whose inner diameter is greater than that of a tip at the end of the head of the worm and which surrounds the neck connecting this tip with the valve seat of the worm. Spacers, preferably balls, are disposed between the ring and the tip and the surfaces of the ring and the tip flanking the balls are oriented to allow radial removal of the balls when the valve projects from the cylinder.

Abstract: Processing shaft for machines for extruding or the like, comprising a core shaft having at its front end an axial stop member for slip-on processing members arranged non-rotationally on the core shaft, further comprising a spacer sleeve supporting the processing members rearwardly, and arranged non-rotationally at the rear end area of the core shaft a slip-on coupling sleeve on whose external thread a clamp nut is screwed, and also comprising a clamping force transmitting member tightenable rearwardly against a stop member of the core shaft by the clamp nut.

Abstract: This invention relates to an improved method and apparatus for use in extruders of the screw type having an elongated passageway defined by a rigid barrel, the surface of which is susceptible to wear from abrasive, corrosive, adhesive or other severe wearing conditions. The improvement comprises a relinable barrel assembly having a housing, a removable sleeve liner and means for securing said liner in said housing. The housing has an elongated tapered bore therethrough, tapering from the feed end to the discharge end of the barrel (i.e. the largest cross-sectional diameter of the bore is at the feed end of the barrel). The sleeve liner has an elongated tapered exterior surface, shaped to mate tightly within the tapered bore of the housing, and an interior surface of wear resistant material, wherein the interior surface defines the passageway within which the screw of the extruder rotates.

Abstract: A method for extruding and/or refining soap, which comprises supplying soap to one end of a helix disposed in a casing and rotating the helix to move the soap lengthwise along the casing and out of the casing. The helix rotates at a speed between 20 and 50 rpm. The length of the helix is 5 to 15 times its diameter. The winding angle of the helix is between 15.degree. and 25.degree.. The helix has a diameter of about 150 mm and a helix depth between 30 and 35 mm.

Abstract: A gear pump assisted screw conveyor extrusion system utilizing a cartridge heating device disposed axially within the screw and having the drives for the gear pump and the screw correlated in speed to create relatively little pressure in the thermoplastic material being extruded such that relatively little mechanical working thereof occurs. The thermoplastic material is melted in the screw conveyor primarily by heat transfer from the cartridge heater and the gear pump is utilized for conveying the melted material under pressure to a subsequent work station. A relatively deep material-conveying spiral channel is provided in the screw for maximized extrusion output per revolution of the screw and minimized mechanical energy generation by the screw. A motionless mixer may be employed intermediate the screw and the work station to homogenize the melted material for reducing temperature gradients therein.

Abstract: The funnel member of a single-screw extruder comprises a housing and a feed screw which passes at least partially axially therethrough and is sealed from the drive shaft by a return feed screwthread covered by a bushing which is fixed with respect to the housing. The feed screw is enveloped by a grooved sleeve having take-in grooves which are parallel to the axis and become shallower in the feeding direction. For charging the material, the funnel member is provided with an eccentric filling aperture tangential to the feed screw. To reduce torque and pressure fluctuations caused in the charged thermoplastic masses by the threads of the screw running past the single aperture, the grooved sleeve (9) is provided with take-in grooves (10, 11) over its entire circumference only in the zone upstream of the filling aperture (4) and, in the region of the filling aperture (4), is provided with take-in grooves (10) only in the part substantially radially opposite to the filling aperture (FIG. 3).

Abstract: The hopper of a screw communicates with a feed chamber situated upstream from the extruder cylinder. The substantially rectangular feed chamber is large enough so that the behavior of a mass of plastic material in its initial state, i.e., in the form of powder or pellets, is affected neither by the side-walls nor by the upper wall nor by the removable bottom of the chamber. Thus, in the case of pellets, the distance between any of those walls and the apex of the screw thread is appreciably greater than the average diameter of the pellets.

Abstract: A backflow preventer at the end of an injection molding worm has a pressure ring which abuts directly upon the worm and serves a shank of the valvehead which also bottoms in a bore upon the worm so that force transmission to the worm is over its entire cross section. The shank is surrounded by a blocking ring which can shift in its axial stroke between a position in which it abuts the head and a position in which it abuts the pressure ring, the axial stroke being adjustable by shims forming the floor against which the shank abuts within the bore of the worm.

Abstract: A plasticating extruder screw conveyor includes multiple primary flights and corresponding multiple secondary flights defining multiple channels on the screw conveyor arranged about the longitudinal axis of the screw conveyor such that radial components of forces between the screw conveyor and unplasticated material located in the channels are substantially balanced so as to reduce to a minimum any resultant radial force upon the screw conveyor and any concomitant lateral deflection of the screw conveyor, thereby reducing or eliminating excessive vibration, wear or galling of the screw conveyor.

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: Screw feeder or Archimedian screw for pasty materials, such as soap, wherein the winding angle of the screw ranges between 15.degree. and 25.degree., and the screw height, diameter and thrust length depend on the section of bar extrusion and/or free passage area of the refining holes.

Abstract: An extrusion apparatus having a barrel and a rotatable threaded screw coaxially positioned therein is disclosed. The apparatus includes an upstream inlet section having an opening therein for receiving material to be processed by the apparatus, a compression section downstream of the inlet section, and a mixing or plasticizing section downstream of the compression section. The interior surface of the barrel is provided with an undercut therein which intercommunicates the feed opening with the compression section and has a portion thereof which extends downstream in the compression section about the interior surface of the barrel with a continuously decreasing cross-sectional area. The undercut may be formed in a cylindrical insert carried within the barrel and, in an alternate embodiment, a second undercut cylindrical insert positioned about the first insert and rotatable relative thereto may be employed to vary the cross-sectional area of the undercut.

Abstract: Plastics recycling apparatus in which an elongated tubular body has a core member therein and in which the core member has leading and trailing conical heads for directing the flow of molten material through the elongated tubular body. Inner and outer annular chambers are provided for the flow of material through a wall between the chambers while the material is being heated by energized coils about one of the chambers. The material flows to the discharge under pressure and passes through discharge orifices to form plastic ribbons which are cooled and then cut into pellets for reuse.