Screw Extruder (2)

A screw extruder for working plastic compositions, said extruder comprising: a cylinder having radially directed bore holes extending there through, said bore holes being disposed in at least two planes perpendicular to the cylinder axis and said bore holes of adjacent planes being aligned parallel to the axis of said cylinder; a rotating spiral screw disposed in said cylinder, said screw having at least two adjacent circumferential grooves forming gaps in the spiral, said gaps corresponding in position to said adjacent bore hole planes; pins corresponding to said bore holes, said pins being radially disposed about said cylinder and having an inner end extendible through said bore holes and into said spiral screw gaps; a beam fastened to an outer end of at least two pins, said at least two pins being aligned in a row parallel to said cylinder axis; stud means for jointly connecting said pins to said beam, said stud means being guidingly engaged in corresponding slots in said beam so as to allow angling of said beam with respect to a normally parallel adjustment of the beam and the cylinder axis; and two drive means disposed at opposing ends of said beam for displacing said beam, whereby said opposing beam ends are independently displaceable by said drive means, thereby controlling the depth to which said at least two pins extend into said screw gaps relative to one another