Sieving device and method for sorting out foreign particles and a system for the production of composite wood boards with such a sieving device

A device for sieving foreign bodies out of a material stream, comprising:

• a roller sieve comprising a plurality of rollers disposed in parallel to one another;
• and
• discs disposed on the plurality of rollers such that they are perpendicular to the axial extension of the rollers,
• wherein the discs of adjacent rollers are engaged so as form slot areas between the discs and the adjacent rollers through which a first portion of the material stream can flow,
• wherein the discs disposed on each roller comprise
• impulse discs having a peripheral contour comprised of at least one corner, the peripheral contour of the impulse discs configured to disaggregate a material stream disposed on the roller sieve, and
• conveyor discs having a peripheral contour comprised of a series of indentations, the conveyor discs configured to promote friction to convey a second portion of the material stream in a transport direction, and
• wherein the conveyor discs disposed on each roller have varying diameters.