Method for the movement of superimposed bands of flexible material

Method for the continuous or intermittent movement by friction of a set (1) of two bands of superimposed flexible material (2, 3) using at least two pulling rollers (4, 5) placed tangentially opposite at both sides of said set of bands and that turn in the direction of movement of the bands, so that these are pulled together in unison, involuntary offsets from the correct mutual position of the bands could occur, characterized in that between both adjacent bands of the set of bands there are antifriction devices (6) that allow mutual movement between both bands when these are pressurised between the opposite rollers and are pulled by them, without appreciable slipping between the bands and the rollers, and because on at least one operative cycle the method includes an adjustment stage, wherein one of the bands is pulled to a greater distance (or even in the opposite direction) than the other band by the respective rollers in order to correct the aforementioned involuntary offsets of the mutual position between both bands.