Patent ID: 8246240

Claim:
A single screw extruder operable to process a human food or animal feed material, said extruder comprising: an elongated barrel having an inlet and a spaced, restricted orifice die outlet; and a single, elongated, axially rotatable, flighted screw assembly ( 52 ) presenting a longitudinal axis and situated within said barrel and operable to move material from said inlet through said barrel and out said die outlet, said screw assembly ( 52 ) including at least one elongated screw section ( 76 ) having a central body ( 82 ) defining a root diameter, and helical flighting ( 86 ) extending outwardly from said central body and presenting an outer periphery with spacings between adjacent portions ( 86 a , 86 b ) of said flighting ( 86 ), said spacings each defined by a surface ( 88 ) extending from a first outer periphery ( 90 a ) of one of said flighting portions ( 86 a ) to a second outer periphery ( 90 b ) of the adjacent flighting portion ( 86 b ), said spacing-defining surface ( 88 ) including first and second surface segments ( 88 a , 88 b ) respectively extending inwardly from said first and second peripheries ( 90 a , 90 b ) and toward said central body ( 82 ), and a third surface segment ( 88 c ) interconnecting said first and second surface segments ( 88 a , 88 b ), said second surface segments ( 88 b ) and the proximal second flighting peripheries ( 90 b ) defining respective angles of from about 75-90° relative to said longitudinal axis, the joinder of said first and second surface segments ( 88 a , 88 b ) with said third surface segment ( 88 c ) being substantially smooth and arcuate without any substantial angular discontinuities, the section of said barrel in surrounding relationship to said at least one screw section having inwardly extending rib elements, said extruder configured to at least partially cook said human food or animal feed material during passage thereof through said barrel.