Patent ID: 8678637

Claim:
An extruder screw, comprising a screw shaft with several screw elements which can be or have been detachably slipped onto the screw shaft, the screw shaft having an external gearing and the screw elements having internal gearing which engages the external gearing, a profile of teeth of the external and the internal gearing being asymmetric and configured such that in relation to a preferred direction of rotation of the extruder screw, torque-transferring flanks of the teeth of the external and the internal gearing make a smaller angle with a perpendicular to an axis of rotation than a larger angle with the perpendicular to the axis of rotation of respective opposing flanks at the teeth of the external and internal gearing, wherein each one of the torque-transferring flank and opposing flank of each tooth of the internal and external gearing have a planar surface, each said planar surface extending to a round base that extends between neighboring teeth.