System and a method for stacking a fanfolded continuous web of sheet material

1 . A system ( 1 ) for stacking a fanfolded continuous web (M) of sheet material of indefinite length, the system ( 1 ) comprising:

a feeding device configured to guide a continuous web (M) in a longitudinal direction (L);

a creasing device ( 2 ) located downstream of said feeding device to form transverse creases (C) on the continuous web (M) spaced apart at a constant longitudinal pitch (K) to define a succession of adjacent partitions (P);

a folding device ( 14 ) located downstream of the creasing device ( 2 ) for progressively and alternately fanfolding the adjacent partitions (P) along the transverse creases (C) and produce a folded web;

a collection device ( 39 ) for collecting the folded web (M) into a stack of adjacent partitions (P);

wherein said collection device ( 39 ) comprises a vertically-extending column ( 40 ) for retaining the stack of adjacent partitions (P);

wherein a dynamic cutting unit ( 52 ) is mounted at the top of said vertically-extending column ( 40 ), to act on a fly on a top adjacent partition (P) of the stack while tracking stack-formation without stopping the folding device ( 14 ); and

wherein a first stack-supporting rack ( 44 ), a second stack-supporting rack ( 45 ), and a stack unloading unit ( 46 ) are mounted onto said column ( 40 ).

2 . The system as claimed in claim 1 , wherein said first stack-supporting rack ( 44 ) and said second stack-supporting rack ( 45 ) are mounted to a first lifting carriage ( 49 ) and a second lifting carriage ( 50 ) respectively, which are vertically movable along said vertically-extending column ( 40 ), said first and said second lifting carriage ( 49 , 50 ) being mounted to a first transverse end ( 44 ′, 45 ′) of said first stack-supporting rack ( 44 ) and said second stack-supporting rack ( 45 ).

3 . The system as claimed in claim 2 , wherein said unloading unit ( 46 ) is mounted to a third lifting carriage ( 51 ) which is vertically movable along said vertically-extending column ( 40 ).

4 . The system as claimed in claim 3 , wherein said dynamic cutting unit ( 52 ) is mounted to a second transverse end ( 44 ″) of said first stack-supporting rack ( 44 ) and comprises a fourth carriage ( 53 ), which is configured to move along a substantially horizontal transverse guide ( 54 ) and a circular cutting blade ( 55 ) facing a counter-blade ( 56 ) for cutting the continuous web (M).

5 . The system as claimed in claim 4 , further comprising a motorized drive ( 57 ) of a belt and pulley type, adapted to simultaneously move said cutting blade ( 55 ) about its own axis and said fourth carriage ( 53 ) along said transverse guide ( 54 ).

6 . The system as claimed in claim 2 , wherein said first lifting carriage ( 49 ) and said second lifting carriage ( 50 ) comprise respective substantially longitudinal guides ( 58 ), which are configured to selectively move said first stack-supporting rack ( 44 ) and second stack-supporting rack ( 45 ) toward the stack to support the stack temporarily when the adjacent partition (P) has been cut and to track a formation of the stack without stopping the folding device ( 14 ).

7 . The system as claimed in claim 1 , wherein said first stack-supporting rack ( 44 ) and said second stack-supporting rack ( 45 ) comprise a plurality of arms ( 47 ) which are transversely offset by a predetermined pitch.

8 . The system as claimed in claim 1 , wherein said unloading unit ( 46 ) comprises a closed-loop conveyor belt ( 48 ), which is adapted to temporarily support the stack and move the stack transversely off said vertically-extending column ( 40 ).

9 . The system as claimed in claim 1 , wherein said creasing device ( 2 ) is configured to form creases alternately on a bottom side (Si) and on a top side (S 2 ) of the continuous web (M), said vertically-extending column ( 40 ) comprising first ( 59 ) and second substantially vertical leveling plates ( 60 ) for vertically aligning the creases (Ci) of the bottom face (Si) and the creases (C 2 ) of the top face (S 2 ) respectively.

10 . A method of stacking a sheet material, said method comprising the steps of:

providing a feeding device for feeding a continuous web (M) in a longitudinal direction (L);

providing a creasing device ( 2 ) downstream of said feeding device to form transverse creases (C) on the continuous web (M) spaced apart at a constant longitudinal pitch (K) and to define adjacent partitions (P);

providing a folding device ( 14 ) located downstream of the creasing device ( 2 ) for progressively and alternately fanfolding the adjacent partitions (P) along the creases (C);

providing a collection device ( 39 ) downstream of the folding device ( 14 ) for collecting the folded web (M) and forming a stack of superimposed adjacent partitions (P);

providing a vertically-extending column ( 40 ) in the collection device ( 39 ) for retaining the stack of superimposed adjacent partitions (P);

providing in said collection device ( 39 ) a first stack-supporting rack ( 44 ) and a second stack-supporting rack ( 45 ), a stack unloading unit ( 46 ), and a dynamic cutting unit ( 52 ) for cutting at least one adjacent partition (P) of the stack;

moving said first supporting rack ( 44 ) and said second supporting rack ( 45 ) horizontally toward the stack and vertically toward the unloading unit ( 46 ), thereby tracking a formation of the stack without stopping the folding device ( 14 );

actuating the dynamic cutting unit ( 52 ) on the fly and causing the dynamic cutting unit ( 52 ) to interact with an uppermost adjacent partition (P) in the stack, thereby avoiding a need to stop the folding device ( 14 ); and

depositing the stack in the unloading unit ( 46 ).