Patent ID: 8172450

Claim:
An extruder having at least two axially parallel support shafts with slip-on elements configured as conveying and/or working elements slipped thereon antirotationally by a shaft-to-hub connection, said elements meshing with adjacent shafts, whereby at least some of the slip-on elements have a profile portion defined by a cross-sectional profile comprising a plurality of opposite pairs of first, second and third circular arcs (A-B, E-F and A-E) respectively corresponding to the maximum slip-on element diameter (DA), the slip-on element core diameter (Dk) and at most the center distance (Ax) of the slip-on elements defined between respective rotation axes of said support shafts, characterized in that the slip-on element is configured so as to have an annular reinforcement segment at each opposite end which projects from said profile portion, wherein said reinforcement segments define the shaft-to-hub connection, said reinforcement segments being provided, in the thin-walled areas of the second circular arcs (E-F) corresponding to the slip-on element core diameter (Dk), with contact surfaces which provide flat or partly flat contact against the support shaft so as to avoid torque transmission in the shaft-to-hub connection, and being provided with two groups of at least two splines or teeth each of which are provided for torque transmission in the shaft-to-hub connection, the distance from group to group being greater than that from tooth to tooth wherein said two groups are provided in the thick-walled areas of the slip-on element corresponding to the first circular arcs (A-B) in the profile portion.