Helical screw conveyor unit, worm shaft, worm extruder, and method for providing a worm shaft

A worm extruder for dewatering a suspension comprising an extruder chamber in which a worm shaft having a helicoidally winding helix element is mounted so as to be rotatable about its longitudinal axis, wherein the worm shaft is comprises:

• a shank which extends along a longitudinal axis and which has a helicoidally or spirally winding helix,
• a helical screw conveyor unit configured as an exchangeable element for the helicoidally or spirally winding helix,
• the helical screw conveyor unit comprising a main body extending along the longitudinal axis, the main body having two axial end regions and a lateral surface that connects the end regions to one another, at least one helicoidally winding helix element being arranged on a top side of the lateral surface and extending radially outward away from the top side, wherein
• the top side of the lateral surface is concavely curved in shell-like form about the longitudinal axis, and the main body has a radial opening, the radial opening being configured such that a fastening region of the shank can be led through the opening in a direction perpendicular to the longitudinal axis and can be arranged in a cavity formed by the main body,
• the helix element has at most one half of one helix turn,
• the lateral surface of the main body has an inner surface configured for being seated on the fastening region, and
• the helical screw conveyor unit has at least one first fastener configured for detachably fastening the main body to the fastening region,
• the worm shaft further comprising at least one second fastener configured for detachably fastening the first fastener, and
• wherein the shank has a cylindrical shaft body and the fastening region, the fastening region being assigned to a support region, configured for supporting the main body of the helical screw conveyor unit of the shank, and having a cross-sectional diameter smaller than that of the cylindrical shaft body, and
• wherein the shank of the worm shaft having at least two helical screw conveyor units, and the helical screw conveyor units each having a configuration of the helical screw conveyor unit.