METHOD AND APPARATUS FOR PRODUCING A PRIMARY ROLL OF MATERIAL, OR FOR DETERMINING AN AMOUNT OF MATERIAL AVAILABLE ON A PRIMARY ROLL

摘要

The method is provided for producing a first primary roll (8) having a predetermined lateral surface defined by a diameter Df, or for determining an amount of material available on a primary roll. The primary roll is made of material wound around a spindle (6). The material is used to produce smaller secondary rolls (12) of material. The method for producing the primary roll of material comprises steps of (a) calculating portion Sf of the lateral surface, which is covered by the spindle; (b) calculating a portion Si of the lateral surface, which represents material needed to produce the smaller secondary rolls of material; (c) calculating a compression factor K1 which is derived from a compression rate K of a previous second primary roll used to produce previous secondary rolls with respect to the previous secondary rolls; (d) calculating Df where: Df = <IMG>; (e) winding up material around the spindle to produce the first primary roll until a diameter of the first primary roll reaches said diameter Df; whereby loss of material is reduced by taking into account compression factor K1 which varies with respect to time. Apparatus to perform the method for producing the first primary roll (8) and for determining the amount of material available on a primary roll for producing smaller secondary rolls (12) is also provided.