Patent ID: 6926654

Claim:
A method for continuously folding a web continuously fed in a machine direction in two along a folding guide line extending in parallel to said machine direction in a cross direction orthogonal to said machine direction, said method comprising the stages of: continuously feeding said web in said machine direction along guide means defining said folding guide line so that said web may be folded by a plurality of guide rolls arranged intermittently in said machine direction, said guide rolls being rotatable in said machine direction in contact with transversely opposite side edge portions of said web and having rotary shafts crossing the side edge portions of said web at an angle of 90° or less opening in a direction in which said web is fed, so that a fold angle of said web in said cross direction may be gradually reduced; downstream of said guide rolls and immediately before a stage of completely folding said web, providing a detector means adapted to detect positions of said side edge portions in said cross direction, swing guide rolls located upstream of said detector means so as to be held in contact with respective said side edge portions and thereby to change the crossing angle of said web with respect to said machine direction and actuators interposed between these detector means and said swing guide rolls; and energizing said actuators on the basis of differences between data supplied from said detector means representing actual positions of said side edge portions and data representing expected positions of said side edge portions so that said swing guide rolls may swing and thereby move said side edge portions toward said expected positions.