Abstract: Procedure for the fabrication of a blank for a structural product, such as a blank for a structural board, from material (1) comprising longer (L) and shorter (S) particles and possibly also particles (F) smaller than these. The particles are mixed with a binding agent and possible additives and then passed into at least one blank former, from where the particles are brought onto a base (10). Longer particles (L) are brought onto the base (10) to form a first surface layer, onto which is brought at least one layer of smaller particles (F, S), and onto this layer is again brought a layer of longer particles (L) to form a second surface layer, the smallest particles (F) being so brought onto the base that they mainly end up in at least one middle layer in the cross-section of the blank while the amount of the smallest particles (F) diminishes towards the surface layers as seen in the cross-section of the blank.

Abstract: An apparatus for length screening of elongated particles such as wood chips, having a roll set (2) formed by at least two essentially horizontal rolls, mounted parallel to each other and adapted to rotate with a gap (5) adjusted between each pair of rolls, and on which roll set the material to be screened is fed essentially orthogonally to the longitudinal axis of the rolls at the intake end of the roll set, whereafter a portion of the material to be screened falls down through the gaps (5) and a remaining portion is removed from the exit end of the apparatus.