Abstract: An injection molding apparatus and method of fabricating a molded part are provided. The apparatus may include a barrel, a nozzle enclosing an end of the barrel and defining an opening in fluid communication with an inside of the barrel, and an extrusion screw positioned at least partially inside the barrel and rotatable relative to the barrel. The extrusion screw may include a screw tip. Relative axial movement between the barrel and the extrusion screw may open or close the opening of the nozzle to permit or prevent, respectively, material flow through the opening of the nozzle. The method may include clamping a mold, opening a nozzle, rotating the extrusion screw to pump a molten material into the mold until the mold is filled, closing the nozzle, and unclamping the mold to release a molded part.

Abstract: An extruder for extrusion of material, the extruder comprising a screw (110), a barrel (120), a controller, and a force sensor wherein at least a section (110b) of the screw (110) is conical and wherein at last a section (120b) of the barrel (120) is conical wherein the extruder (100) is adapted for displacing the screw (110) in an axial direction of the screw (110), such that by an axial displacement of the screw with regard to the barrel the size of a leakage gap (180) between the screw (110) and the barrel (120) is modified, wherein the extruder is adapted for actively obtaining operational characteristics and wherein the controller (160) is adapted for controlling the axial displacement of the screw (110) as a function of the operational characteristics of which at least one is an upward force of the material or an upward force on the screw.

Abstract: The present disclosure relates generally to an extruder for producing an extrudate. The present disclosure relates more particularly to an extruder including an extruder body having at least one material inlet and an exit opening. A rotatable outlet is coupled to the exit opening of the extruder body and is configured to rotate as the extrudate is expelled from the extruder body.

Abstract: A single-screw extruder (100), and a method. The extruder (100) comprises—a cylindrical rotor member (1) having diameter (D) and length (L) and comprising a feeding zone (14), —the rotor member (1) arranged in a barrel (2), —the cylindrical surface of the rotor member (1) carrying cavity/cavities and/or projection(s) (5) arranged in helically extending rows, —the helically extending row(s) of the rotor member (1) having a pitch (P) and depth (d) in the feeding zone (14) of the rotor member, and the extruder (100) further compris-ing—a drive system (4) for the rotation of the rotor member (1) in the barrel (2). The relation of the depth (d) to the diame-ter (D) of the rotor member, i.e. d:D, is not more than 1:20, and the relation of the pitch (P) of the rotor member to the di-ameter (D) of the rotor member, i.e. P:D, is not more than 1:4.

Abstract: An extruder has a barrel extending from a feed inlet end to an extruder outlet end. The barrel has an inner surface, an outer surface, and a wall thickness between the inner and outer surfaces. The extruder also has at least one heating member positioned provided on the barrel; a screw drive motor drivingly connected to a rotatably mounted screw positioned within the barrel, whereby the screw is rotatable at various revolutions per minute (RPM); and a controller is operably connected to the screw drive motor to adjust the RPM of the screw based upon a temperature of material passing through and/or being extruded from the barrel. Methods for operating an extruder filling a mold are also provided.

Abstract: The screw is intended for the extrusion or mixing of elastomers or plastic products. It comprises: a support, at least one sleeve having at least one relief projecting from an external face of the sleeve, and at least one split annular securing member, the member being clamped between the sleeve and the support in a radial direction with respect to an axis of the screw so as to secure the sleeve rigidly to the support. The member and the sleeve have frustoconical faces in mutual contact.

Abstract: A kneading apparatus includes a plasticizing cylinder in which a high pressure kneading zone and a pressure reduction zone are formed adjacently in this order from an upstream side so that a molten resin obtained by plasticizing a thermoplastic resin and a pressurized fluid are kneaded with each other in the high pressure kneading zone, and gasified pressurized fluid, which is gasified by reducing a resin internal pressure, is separated in the pressure reduction zone from the molten resin kneaded with the pressurized fluid, a screw which is arranged rotatably and movably back and forth in the plasticizing cylinder; and a downstream side seal mechanism which is provided between the high pressure kneading zone and the pressure reduction zone and which makes communication and disconnection between the high pressure kneading zone and the pressure reduction zone in accordance with a rotation state of the screw.

Abstract: A screw shaft structure for a twin screw extruder includes a tapered section (20) provided between a ground section (6) and a screw piece inserting section (8), and a tapered ring (21) fitted onto the tapered section (20). The tapered ring (21) serves as a flange section. An object is to reduce the weight of raw material to be used for manufacturing a screw shaft by combining a tapered section and a tapered ring as a structure of a flange section.

Abstract: An extruder for feeding material and for removing gas from the fed material. The extruder includes a vent block positioned between a first and second auger. The vent block including a vent cavity having a feed end and an exit end, an inner feed ring that partially extends into said vent cavity at the feed end of the vent cavity, and a screw element rotatably positioned in the vent cavity. A front portion of the outer ring is longitudinally aligned with or overlapping the front end of the inner feed ring. The outer ring forms at least one gap or opening at or adjacent the feed end of the vent cavity to enable a vacuum to be pulled on the vent cavity as material is moved though the vent cavity from the feed end to the exit end by the screw element.

Abstract: A plastication screw (1) comprises a shank (2) extending along a rectilinear axis (3), a feeding region (4) to supply a product to be plasticated, a plastication region (5) placed immediately downstream of the feeding region (4), relative to a main feeding direction (S) of the product along the axis (3) of the shank (2), at least one primary thread (7) extending in a helical development around the shank (2) at least in the plastication region (5), following a predetermined winding direction (V), and at least one secondary thread (10) extending in a helical development around the shank (2) in the same way as said predetermined winding direction (V), in at least part of the plastication region (5). The primary thread (7) and the secondary thread (10) each have a varying pitch (p1, p2). The pitch variation (p2) of the secondary thread (10) is greater than the pitch variation (p1) of the primary thread (7).

Abstract: Extruders for processing material have a selectively variable extruder volume. The extruders include an extruder barrel containing a bore sized to process 5 to 50 grams of material, wherein the bore has an upstream inlet portion for feeding the material to be processed and a downstream outlet portion connectable to an extruder exit for material processed through the extruder, and at least two recycle channels which differ from one another in at least one of volume, area of cross-section and length. A diverter valve of a flow control system is positioned at the outlet of the extruder for controllably directing material flow from the bore to either the extruder exit or at least one of at least two recycle channels.

Abstract: The invention relates to an apparatus for extruding thermoplastic material, comprising an extruder screw (2) which is mounted in a housing (1), comprises a plasticizing section (P) on the inlet side, a degasification section (E) upstream of an outlet section (A), a flow arrester (S) between the plasticizing section (P) and the degasification section (E) with a screw section with a counter-rotating delivery flight (3), and at least one flow channel (5) bridging the flow arrester (S) and containing a melt filter (4). In order to reduce the driving power of the extruder screw (2) it is proposed that a sleeve (7), which encompasses the screw (6) and is mounted in the housing (1) in a rotationally fixed manner, is associated with the screw section that forms the flow arrester (S), and the screw (6) in the screw section of the flow arrester (S) has a smaller screw diameter in relation to the plasticizing section (P) and preferably also to the degasification section (E).

Abstract: Extruders for processing material have a selectively variable extruder volume. The extruders include an extruder barrel containing a bore sized to process 5 to 50 grams of material, wherein the bore has an upstream inlet portion for feeding the material to be processed and a downstream outlet portion connectable to an extruder exit for material processed through the extruder, and at least two recycle channels which differ from one another in at least one of volume, area of cross-section and length.

Abstract: Improved single screw extruders systems (40) are provided including a single screw extruder (42, 92) as well as an upstream preconditioner (44). The extruders (42, 92) include a single, internal, elongated, helically flighted, axially rotatable screw assembly (52) having one or more improved screw sections (74, 74a, 76). The screw sections (74, 74a, 76) include specially configured flighting (86) wherein adjacent flighting portions (86a, 86b) have smoothly arcuate surfaces (88) extending between the respective flighting portion peripheries (90a, 90b). This flighting design provides smooth, substantially surge-free operation while increasing SME and cook values. The preferred preconditioner (44) has independently controlled mixing shafts (106, 108) allowing the shafts (106, 108) to be rotated at different rotational speeds and/or directions.

Abstract: A novel barrier screw scientifically designed with new structural features that eliminate the shortcomings of the previous barrier screws and further improve their performance. The important new structural features include a structure of originating the barrier flight without creating any dead-spot while maintaining a constant solid channel width, a structure of terminating the barrier flight without creating any dead-spot while assuring good melt quality, a melt channel structure of avoiding excessively deep channel depth while assuring sufficient melt conveying capacity, and a solid channel structure of avoiding excessively large channel area with shallow channel depth while assuring good melt quality.

Abstract: A kneading screw is disclosed which comprises a screw body, the screw body comprising a feed section and a kneading section, the feed section comprising screw segments for feeding a to-be-kneaded material to a downstream side and the kneading section comprising kneading segments for kneading the material. The screw body is provided within the kneading section with a multi-stage portion which gradually changes axially in rotating outside diameter. It is preferable that the multi-stage portion be constituted by kneading segments of plural kneading discs different in rotating outside diameter. With such a construction, it is possible to avoid stress concentration on an axial part of the kneading screw and thereby prevent breaking of a spline shaft and abnormal wear of kneading flights.

Abstract: A clay kneader has a drum having a pressure raising section on a supply opening side, an extrusion section having an inner diameter smaller than that of the pressure raising section on side of an extrusion opening for extruding clay as a columnar article, and a flow controlling section located between the pressure raising section and the extrusion section and being equipped with a supply opening for clay, a screw having a rotary shaft having a diameter which gradually decreases toward the extrusion opening in the flow controlling section and being ended around a boundary between the flow controlling section and the extrusion section, and a helical rotating blade provided along the rotary shaft for kneading the clay a rotary shaft.

Abstract: Provided is a method of mixing a modified bitumen composition and feeding one or more polymeric materials to an extruder, together with asphalt fed at more than one location along a length of the extruder. Improved mixing and elimination of asphalt melting in the production of rolled goods and other products is improved.

Abstract: A barrel alignment structure for a pair of barrel sections each defining an end surface configured to abut each other is disclosed. The barrel alignment structure comprises of a plurality of alignment pins distributed on the end surface of the first barrel section. The barrel alignment structure further comprises of a corresponding number of slots defined on the end surface of the second barrel section, each slot configured to receive one alignment pin, wherein the slot has a width substantially equal to that of the alignment pin and a length larger than the width of the alignment pin permitting relative thermal expansion between the pair of barrel sections. An extruder barrel section is also disclosed. The extruder barrel section defining an end surface configured to abut the end surface of another extruder barrel section. The extruder barrel section comprises of a plurality of alignment pins distributed on its end surface.

Abstract: Provided is a kneading degree adjusting apparatus, which can have a wide adjusting range for a kneading degree even if a gate member and a cylindrical segment are not made so close as to invite a fear of metallic contacts. The kneading degree adjusting apparatus is disposed in a kneading treatment equipment, which includes a cylindrical segment formed at a predetermined portion and a kneading screw for kneading a material while feeding the same to the downstream side, thereby to adjust the kneading degree of the material. The kneading degree adjusting apparatus comprises a gate member having an opposed face confronting the outer circumference of the cylindrical segment and moved toward and away from the outer circumference of the cylindrical segment thereby to change the area of the material passage to be formed between the opposed face and the outer circumference of the cylindrical segment. The outer circumference and the opposed face are corrugated to form the passage into a bent shape.

Abstract: High-capacity extrusion die assemblies (20, 90, 130, 140, 180, 252) each having a tubular section (44, 146, 162, 268) and an elongated, axially rotatable, helically flighted screw section (56, 56a, 152, 168, 276, 278) which cooperatively define frustoconical, outwardly diverging material flow paths (75, 160, 291) at constant or differing divergence angles of from about 1-11°. The use of diverging tubular sections (44, 146, 162, 268) and screw sections (56, 56a, 152, 168, 276, 278) permits the use of larger die plates (76, 118, 292) with an increased number of die openings (80, 124, 296). This allows significant increases in extrusion production rates. The die assemblies (20, 90, 130, 140, 180, 252) can be used in the production of a wide number of human foods or animal feeds, and particularly aquatic feeds of the floating or sinking variety.

Abstract: A method for producing a masticated rubber, which comprises the steps of masticating rubber at a shear rate of from 500 to 4,500 (l/s); and obtaining masticated rubber having a weight-average molecular weight of from 100,000 to 1,300,000.

Abstract: Provided is a method of mixing a modified bitumen composition and feeding one or more polymeric materials to an extruder, together with asphalt fed at more than one location along a length of the extruder. Improved mixing and elimination of asphalt melting in the production of rolled goods and other products is improved.

Abstract: A mixer for mixing liquid additive with polymer dope constituted by cellulose ester as polymer and solvent is provided. There is a mixing conduit for flow of the polymer dope. A supply conduit ejects liquid additive into the polymer dope in the mixing conduit. A rotor hub is positioned downstream from the supply conduit, contained in the mixing conduit rotatably about an axis directed in a flow direction of the polymer dope, and has a diameter decreasing end on an upstream side. A driving device with electromagnets rotates the rotor hub by electromagnetic induction through a chamber inside the mixing conduit. Furthermore, a support is disposed within the mixing conduit to extend transversely to the flow direction, for supporting the rotor hub rotatably. Flow openings are formed in the support, for passing the polymer dope in the flow direction about the rotor hub.

Abstract: A method of injection molding or extruding a polymer composition having a predetermined bulk density associated with particles, granules or pellets of the polymer composition and a predetermined melt density when the polymer composition is fully melted and compressed. The method of the invention employs a screw having a volume compression ratio that is greater than or equal to the ratio of the predetermined melt density to the predetermined bulk density of the polymer composition and up to 1.25 × the ratio of the predetermined melt density to the predetermined bulk density of the polymer composition.

Abstract: A method for dehumidifying and drying resin pellets that can efficiently dry both non-crystallized resin pellets and crystallized resin pellets, the apparatus being adapted to downsizing. A control means 67 adapts to operate in a first drying mode of controlling the heating operation of the first heating member 25 for heating longitudinally divided regions of the first cylinder 5 section to produce differentiated respective heating effects and that of the second heating member 31 for uniformly heating the second cylinder 7 section so as to crystallize the supplied non-crystallized resin pellets NCRP and subsequently drying them and in a second drying mode of controlling the heating operation of the first heating member 25 and that of the second heating member 31 for uniformly heating the first and second cylinder 5,7 sections so as to drying the supplied crystallized resin pellets CRP.

Abstract: Apparatus and a method for mixing a liquid within a disposable aspirating probe tip so that most of the liquid is forced to move past a transition zone between two different inside diameters to cause rotational mixing. The apparatus and method can be used to provide agglutination of blood, which in turn can be used for blood typing. The probe tip can include a single integral piece, or two separate portions. The transition zone can include a sharp demarcation between inside diameters, or a smooth one.

Abstract: A plasticating screw for an extruder or an extrusion press has a thread change, whereby the volume of the transporting cross-section does not change and thus a pressure increase in the region of the thread is avoided. To this end, in the region wherein a first and a second screw thread of the plasticating screw overlap, the thread width outside the overlapping region is equal to d and the thread width inside the overlapping region is equal to ½ d.

Abstract: Apparatus according to this invention for plasticating a resin polymer, especially polypropylene, includes a barrel having an inlet, outlet, and inner surface. A screw, located within and closely spaced from the inner surface of the barrel, has a longitudinal axis extending from the inlet toward the outlet, and includes length sections arranged in a series along the axis. The screw includes a core and a main flight located on and projecting radially from the core, extending in a helix along the axis, and having a push side and a trailing side. The screw sections include a feed section, a transition section following the feed section, a metering section following the transition section, and a barrier melting section following the metering section.

Abstract: A process for injection-foaming a thermoplastic resin by using an injection molding machine with a two-stage-compression screw, injecting a physical foaming agent into the cylinder of the machine at a pressure lower than the storage pressure of the physical foaming agent, mixing it with a melted resin and expanding the volume of the cavity of the mold at the time of injection, and an injection molding machine and resin composition suitable therefore.

Abstract: An extrusion molding apparatus comprises a shaping die for producing a ceramic molded product, and a screw extruder having built therein an extruding screw (40) for mixing while leading a ceramic material forward. The extruding screw (40) includes a pressing screw portion (410) having a first lead (411) and a dispersing screw portion (420) having a second lead (421) adjacent to a forward end (412) of the pressing screw portion (410). The second lead (421) is formed in such a manner that the rear ends of all the second lead surfaces (426) at the rear end (422) of the dispersing screw portion (420) and the forward end of the first lead surface (416) at the forward end (412) of the pressing screw portion (410) are displaced from each other.

Abstract: The extruding apparatus has the molding die to form the ceramic molding, the screw extruder containing the extrusion screw to knead and guide the ceramic material toward the molding die. The extrusion screw is comprised of the pressure screw part and the diffusion screw part. The diffusion screw part provided at the front end of the extrusion screw has a diameter greater than the screw diameter of the pressure screw part.

Abstract: A rotatable screw for moving material in a plasticating process along an axis through a conduit from an inlet to an outlet. The screw having a feed section, barrier melting section, reorientation section and metering section disposed sequentially downstream. The screw includes an axial core, and a helical main flight that extends radially from the core and is formed with recesses located at the first periphery and extending through the thickness of the main flight and radially toward the core. A helical secondary flight extends radially from the core between successive helical passes of the main flight, and is formed with recesses extending through the secondary flight and toward the core. Materials conveyed along the metering section can cross through the main flight at the recesses and recirculate, in addition to passing over the periphery of the secondary flight, for still further enhanced and homogenous mixing, before reaching the outlet.

Abstract: A screw rotates in a containment barrel, and comprises a shaft having an upstream end and a downstream end At least one flight is secured to the surface of the shaft and extends helically in successive turns around the circumference of the shaft. An upstream barrier member extends radially from the surface of the shaft and generally transversely between successive turns of the flight. The upstream barrier is disposed proximal the upstream end of the shaft. A downstream barrier member extends radially from the surface of the shaft and generally transversely between successive turns of the flight. The downstream barrier is disposed proximal the downstream end of the shaft.

Abstract: A screw element includes an outer radius Ra and a core radius Ri for multiscrew extruders with co-rotating and intermeshing screw shafts. The screw element has in axial cross section through its longitudinal axis a profile which has at each of the two axial end faces (i.e. a front end face and a rear end face) only one screw flight corresponding to a conventional single-start screw element for intermeshing screw shafts. In this case, the width (flight land angle ?) of the screw flight and conversely, in a corresponding way, the width (flight land angle ?) of the screw flight are formed in a special way and a shearing flight with a constant shearing flight radius Rs, which is greater than Ri, and less than Ra, is provided.

Abstract: The present invention concerns a screw for moving plastic through a barrel in a direction of flow from a drive to a tip. The screw has a shaft having opposing first and second ends, a drive located on the first end of the shaft, a tip located on the second end of the shaft, and a flight helically extending around the shaft. The shaft also has a section of decreasing diameter in the flow direction and a section of increasing in diameter in the flow direction.

Abstract: A screw nose for a rubber extruder screw has an upstream portion of increasing diameter providing working engagement of the rubber flowing from the screw with the extruder barrel and a downstream portion of decreasing diameter providing working engagement of the rubber with a converging tapered wall of a flow channel block for reducing the shrinkage and pressure drop at the discharge end of the screw and thereby prevent porosity and blisters in an extruded rubber component.

Abstract: The invention relates to an extruder for the preparation of rubber mixtures for elastomeric products and comprises a cylinder, an endless screw rotatably mounted in the cylinder for uptake transport and homogenization of the rubber mixture, and an extrusion tool; wherein the endless screw is configured with zones of multiple treads in dependence of varying helix angle and depth of thread so that the rubber mixture transported through the zones undergoes a temperature increase through heat dissipation to such an extent that the temperature of the extrudate approaches the vulcanization temperature thereof.

Abstract: An extrusion molding apparatus capable of improving the extrusion rate of the ceramic material without a major reconstruction of a drive system is disclosed. The extrusion molding apparatus comprises screw extruders (2, 3) including housings (29, 39) having screws (4, 5) built therein, wherein the ceramic material introduced into the housings (29, 39), respectively, is extruded by way of the forward end extrusion ports by rotating the screws (4, 5). The screws (4, 5) built in the screw extruders (2, 3), respectively, include pressure portions (41, 51) with the feed rate per revolution progressively decreased toward the forward end extrusion port, and extended portions (43, 53) with the feed rate per revolution progressively increased toward the forward end extrusion port.

Abstract: A rotatable screw for moving material in a plasticating process along an axis through a conduit from an inlet to an outlet. The screw having a feed section, barrier melting section, reorientation section and metering section disposed sequentially downstream. The screw includes an axial core, and a helical main flight that extends radially from the core and is formed with recesses located at the first periphery and extending through the thickness of the main flight and radially toward the core. A helical secondary flight extends radially from the core between successive helical passes of the main flight, and is formed with recesses extending through the secondary flight and toward the core. Materials conveyed along the metering section can cross through the main flight at the recesses and recirculate, in addition to passing over the periphery of the secondary flight, for still further enhanced and homogenous mixing, before reaching the outlet.

Abstract: A new plasticity apparatus including a rotating and reciprocating screw having a hellcal flight that is wrapped around a core, disposed within and cooperting with the inner wall of a heated barrel that substantially increases the melt quality of a polymeric material. This is accomplished by incorporating an increase in the hefix angle of the primary flight at the taper terminus of the transition section, in cooperation with a stepped change in the root that terminates either upstream or downstream of the end of one complete revolution of the flight.

Abstract: The invention relates to a screw element with an outer radius Ra and a core radius Ri for multiscrew extruders with co-rotating and intermeshing screw shafts, in particular for twin-screw extruders, which has in axial cross section through its longitudinal axis (10) a profile which has at each of the two axial end faces (front end face 8, rear end face 8′) only a screw flight (1, 1′) corresponding to a conventional single-start screw element for intermeshing screw shafts. In this case, the width (flight land angle &phgr;) of the screw flight (1) and conversely, in a corresponding way, the width (flight land angle &phgr;) of the screw flight (1′) are formed in a special way and a shearing flight (7) with a constant shearing flight radius Rs, which is greater than Ri and less than Ra, is provided.

Abstract: An apparatus for manufacturing moldings by which clear colors and patterns can be brought out without a remarkable lowering of strength. Immediately before delivery to a metal mold, outer resin material positioned on the main cylinder inner wall side is put in the molten state, and inner resin material positioned on the main screw side is controlled to be from the softening temperature to the melting temperature both inclusive to be extrusion-molded as they are. The inner wall of the main cylinder is expanded where the outer resin material is received to help the outer resin material be thrown in smoothly.

Abstract: An extruder for polymer melts, with an extrusion space arranged in an extruder barrel and through which at least one extruder screw shank extends so that it can be rotated by a motor. The screw shank has at least one section in the form of a cylinder casing, the extrusion space having at least one barrel section which surrounds the cylinder casing in an essentially equidistant manner to form an encircling gap as a restricted flow zone (blister), in particular to set the pressure of the melt. The clearance of the encircling gap at the restricted flow zone can be changed in a specifically selective manner by externally adjustable force, with elastic deformation of the inside surface of the extrusion space and/or of the surface of the screw shank, by a hydraulic pressure chamber provided in the region of the restricted flow zone in the wall of the barrel section and/or in the least one screw shank.

Abstract: The present invention concerns a screw for moving plastic through a barrel in a direction of flow from a drive to a tip. The screw has a shaft having opposing first and second ends, a drive located on the first end of the shaft, a tip located on the second end of the shaft, and a flight helically extending around the shaft. The shaft also has a section of decreasing diameter in the flow direction and a section of increasing in diameter in the flow direction.

Abstract: A plasticating screw having a feed section, barrier melting section, reorientation section and metering section disposed sequentially downstream wherein solid material is moved from a trail side of a main flight to a push side of the main flight in the reorientation section. The reorientation of solids is accomplished by discontinuing a barrier flight at a terminal end of said barrier melting section. The main flight decreases its pitch and continues into the reorientation section, which has a longitudinal length at least 360° about the screw axis. A melt channel and solids channel in said barrier melting section merge into a substantially uniform reorientation channel in the reorientation section so that solid plastic material conveyed along the reorientation section moves toward the push side of the main flight.

Abstract: An extrusion apparatus is provided having an extrusion worm with a threaded exterior passage and rotatably driven by a drive shaft operatively couplable with a drive motor for driving rotation of the drive shaft. A feed in device feeds to the extrusion apparatus material that is to be extruded. The extrusion device includes a socket having a threaded interior passage, the socket receiving therein the extrusion worm in at least partial axial overlap such that material to be extruded passes between and in contact with the threaded exterior passage of the extrusion worm and with the threaded interior passage of the socket. The rate of rotation of the socket and the rate of rotation of the extrusion worm are independently adjustable relative to one another.

Abstract: The invention provides a molding apparatus adapted to use a screw having an overall length permitting the use of an existing molding machine cylinder as it is, and is capable of realizing a gas impregnation step. The screw 3 for use in the gas impregnation step comprises a resin melting portion C disposed at an upstream position for rendering the resin molten, a molten resin nonfilled-up portion E integral with the downstream side of the resin melting portion C for making the resin lower than an inert gas at a gas supply opening 5 in pressure, and a gas impregnation portion D integral with the downstream side of the molten resin nonfilled-up portion E for supplying the inert gas and impregnating the molten resin with the inert gas.

Abstract: An improved twin screw extruder device (14) is provided which is capable of producing a wide variety of high quality extrudates having greatly varying final properties, without the need for extensive machine modifications. The extruder (14) includes a barrel (16) together with a co-rotating twin screw assembly (22). The assembly (22) is made up of a pair of screws (50, 52) having central, tapered shafts (54, 56) equipped with outwardly extending helical flighting (58, 60); the screws (50, 52) are non-parallel and are positioned so that the flighting (58, 60) thereof is intercalated along the length of the screws (50, 52). The flighting is of specialized configuration and tapers along the length of the screws (50, 52) preferably at an angle of taper different than that of the shafts (54, 56); moreover, the width of the outer flighting surfaces (70, 72) increases along the length of the shafts (54, 56).

Abstract: An improved twin screw extruder device (14) is provided which is capable of producing a wide variety of high quality extrudates having greatly varying final properties, without the need for extensive machine modifications. The extruder (14) includes a barrel (16) together with a co-rotating twin screw assembly (22). The assembly (22) is made up of a pair of screws (50, 52) having central, tapered shafts (54, 56) equipped with outwardly extending helical flighting (58, 60); the screws (50, 52) are non-parallel and are positioned so that the flighting (58, 60) thereof is intercalated along the length of the screws (50,52). The flighting is of specialized configuration and tapers along the length of the screws (50, 52) preferably at an angle of taper different than that of the shafts (54, 56); moreover, the width of the outer flighting surfaces (70, 72) increases along the length of the shafts (54, 56).