Conveyor screw element

Claim 1

A screw conveyor comprising a tube and a screw mounted for rotation within the tube, wherein said conveyor screw comprises a shaft; a plurality of screw sections mounted on the shaft in end to end relationship, each screw section being molded as a unitary structure in a plasticS materials and comprising a generally cylindrical hub portion which receives said shaft and a spiral flight portion extending around the hub portion to run neatly within the tube; and formed on the external periphery of the shaft and the internal periphery of said hub portions of the screw sections, spline and groove means coupling the screw sections to the shaft, said spline and groove means including at least eight splines with cooperating grooves extending longitudinally of the shaft and the hub portions of the screw sections and spaced at equal intervals circumferentially thereof so that each screw section can be coupled to the shaft in any of at least eight rotational positions relative to one shaft, the rotational positions of the screw sections adapted to be varied relative to one another to vary the characteristics of the screw, and said flight portion of each section being spiraled to a regular helix and the length of the section being less than the pitch of said helix so that the flight portion extends through less than one complete turn of the helix whereby molding of the screw section is facilitated.