초록 ▼

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 scr

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 fighting 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). This screw geometry defines a series of alternating upper and lower close-clearance high-pressure nip areas (78) defined by the flighting (58, 60) which serves to propel an extrudable mixture forwardly towards the outlet end (20) of the barrel (16). However, passageways (80) and kneading zones (82) are also defined between the screws (50, 52), which assures full mixing, shearing and cooking of the material. The extruder device (14) is capable of producing high density sinking aquatic feeds as well as expanded, low density products merely by changing the rotational speed of the screws (50, 52) together with appropriate temperature control. In another embodiment, a fluid extraction extruder (138) is provided having a specialized extruder head (140) including an outer shell (144) and an inner, elongated, slotted sleeve (152).

대표청구항 ▼

1. An extruder head comprising an elongated body having an outer shell and an inner extraction sleeve disposed within said shell and in spaced relationship to said shell, said sleeve having an inner surface defining an internal, elongated passageway adapted to receive and fully surround at least one

1. An extruder head comprising an elongated body having an outer shell and an inner extraction sleeve disposed within said shell and in spaced relationship to said shell, said sleeve having an inner surface defining an internal, elongated passageway adapted to receive and fully surround at least one extrusion screw component and an outer surface, with a plurality of openings formed in the sleeve and extending from said inner surface to said outer surface, said openings configured to permit an extracted fluid to pass therethrough for collection in said shell. 2. The extruder head of claim 1, wherein said shell includes an extracted fluid outlet. 3. The extruder head of claim 1, at least certain of said openings being slots, said slots being tapered and having a width adjacent said inner surface which is less than the width thereof adjacent said outer surface. 4. The extruder head of claim 1, said passageway being tapered along the length thereof. 5. The extruder head of claim 1, said passageway being of FIG. 8 configuration to accommodate side-by-side extrusion screws. 6. The extruder head of claim 1, said sleeve formed of a plurality of interconnected, elongated bars. 7. An extruder comprising an elongated barrel presenting a material inlet and a material outlet; and at least one elongated axially rotatable, helically flighted screw located within said barrel and operable for moving material from said inlet to said outlet, said barrel including a section having an outer shell and an inner extraction sleeve disposed within said shell, said sleeve having a sleeve inlet located downstream of and in spaced relationship to said barrel inlet, said sleeve presenting an inner surface defining an internal, elongated passageway receiving and fully surrounding a portion of said screw and an outer surface, with a plurality of openings formed in the sleeve and extending from said inner surface to said outer surface, said openings configured to permit an extracted fluid to pass therethrough for collection in said shell, said barrel and screw cooperatively configured for subjecting said material to increasing levels of temperature pressure and shear between said barrel inlet and said sleeve inlet; said at least one screw and said sleeve cooperatively configured for extraction of fluid from said material during passage through said barrel section, and collection of said fluid within said shell. 8. The extruder of claim 7, wherein said shell includes an extracted fluid outlet. 9. The extruder of claim 7, at least certain of said opening being lots, said slots being tapered and having a width adjacent said inner surface which is less than the width thereof adjacent said outer surface. 10. The extruder of claim 7, said passageway being tapered along the length thereof. 11. The extruder of claim 7, said passageway being of FIG. 8 configuration to accommodate side-by-side extrusion screws. 12. The extruder of claim 7, said sleeve formed of a plurality of interconnected, elongated bars. 13. The extruder of claim 7, said section being located adjacent said outlet.