Folding roller and interfolding machine employing said roller
An interfolding machine ( 1 ) is described, including folding rollers ( 3 ). Such a roller has a cylindrical sleeve ( 3 C) having a rotation axis ( 3 A), an outer surface ( 3 X) and an inner surface ( 3 Y) defining an inner axial cavity ( 23 ) of the cylindrical sleeve ( 3 C). The cylindrical sleeve includes, furthermore, a plurality of suction holes ( 41, 43 ) which extend from the outer surface ( 3 X) to the inner surface ( 3 Y) of the cylindrical sleeve ( 3 C). The suction holes are arranged depending on longitudinal alignments ( 42, 44 ), parallel to the rotation axis ( 3 A) of the cylindrical sleeve ( 3 C) and angularly staggered in relation to one another. Inside a suction chamber ( 23 A) in the cylindrical sleeve ( 3 C), shutters are stationarily arranged having closing surfaces ( 37 A) cooperating with the inner surface ( 3 Y) of the cylindrical sleeve ( 3 C) to selectively close the suction holes.
1. A folding roller ( 3 ) comprising:
a cylindrical sleeve ( 3 C) having a rotation axis ( 3 A), an outer surface ( 3 X) and an inner surface ( 3 Y) delimiting an axial cavity ( 23 ) of the cylindrical sleeve ( 3 C);
an inner body ( 25 ) axially extending in the axial cavity ( 23 ) of the cylindrical sleeve ( 3 C), the cylindrical sleeve ( 3 C) arranged so as to rotate around the inner body ( 25 );
a suction chamber ( 23 A) inside the cylindrical sleeve ( 3 C);
a plurality of suction holes ( 41 , 43 ) extending from the outer surface ( 3 X) up to the inner surface ( 3 Y) of the cylindrical sleeve ( 3 C); wherein the suction holes are arranged according to longitudinal alignments ( 42 , 44 ) that are substantially parallel to the rotation axis ( 3 A) of the cylindrical sleeve ( 3 C) and angularly spaced apart with respect to one another;
wherein inside the suction chamber ( 23 A) a plurality of stationary shutters ( 37 ) are arranged, spaced from one another along the rotation axis ( 3 A) of the cylindrical sleeve ( 3 C), each shutter ( 37 ) having a closing surface ( 37 A) co-acting with the inner surface ( 3 Y) of the cylindrical sleeve ( 3 C) to close selected suction holes ( 41 ) of the plurality of suction holes ( 41 , 43 ), and wherein the plurality of suction holes ( 41 , 43 ) are subdivided into at least a first longitudinal alignment ( 42 ) and a second longitudinal alignment ( 44 ), which are angularly spaced apart with respect to one another; and wherein the suction holes ( 41 , 43 ) are configured and arrangement so that, during rotation of the cylindrical sleeve ( 3 C), the selected suction holes ( 41 ) of the first longitudinal alignment ( 42 ) are closed by the shutters ( 37 ) while remaining suction holes ( 43 ) of the second longitudinal alignment ( 44 ) are not closed by the shutters ( 37 ).
2. The folding roller ( 3 ) according to claim 1 , wherein the plurality of suction holes ( 41 , 43 ) are arranged according to annular arrangements around the rotation axis ( 3 A) of the cylindrical sleeve ( 3 C).
3. The folding roller ( 3 ) according to claim 1 , wherein said plurality of shutters ( 37 ) have an adjustable angular development comprised between 55° and 65°.
4. The folding roller ( 3 ) according to claim 1 , wherein the suction chamber ( 23 A) is delimited by two radial walls ( 27 , 29 ) integral with the inner body ( 25 ) and angularly spaced with respect to each other, and wherein the shutters ( 37 ) each extend tangentially from one ( 29 ) of said two radial walls inside the suction chamber ( 23 A) towards another ( 27 ) of said two radial walls.
5. The folding roller ( 3 ) according to claim 1 , wherein the suction chamber ( 23 A) has an angular development comprised between 150° and 230°.
6. The folding roller ( 3 ) according to claim 1 , comprising a plurality of annular grooves ( 3 S) provided on the outer surface ( 3 X) of the cylindrical sleeve ( 3 C), wherein the annular grooves ( 3 S) are interposed between annular alignments of the plurality of suction holes ( 41 , 43 ).
7. An interfolding machine ( 1 ) comprising a pair of folding rollers ( 3 ) according to claim 1 , arranged with respective rotation axes ( 3 A) substantially parallel to each other and adjacent to each other such as to form a folding nip ( 5 ).
8. The interfolding machine ( 1 ) according to claim 7 , wherein the pair of folding rollers ( 3 ) are arranged such that each shutter ( 37 ) of one folding roller ( 3 L) of the pair of folding rollers ( 3 ) is arranged in front of a space between a pair of consecutive shutters ( 37 ) of another ( 3 R) of said pair of folding rollers ( 3 ).
9. The interfolding machine ( 1 ) according to claim 8 , wherein the shutters ( 37 ) of the pair of folding rollers ( 3 ) extend annularly from the folding nip ( 5 ) downstream thereof with respect to a rotation direction (f 3 ) of the pair of folding rollers ( 3 ).
10. The interfolding machine ( 1 ) according to claim 7 , comprising a respective cutting roller ( 7 ) for each folding roller ( 3 ) of the pair of folding rollers, each cutting roller ( 7 ) having a plurality of blades ( 9 ) co-acting with at least a respective counter-blade ( 11 ) to cut a continuous web material (N 1 , N 2 ) in sheets (F 1 -Fn) for folding and interfolding.
11. The interfolding machine ( 1 ) according to claim 10 , wherein each cutting roller ( 7 ) forms, together with a respective folding roller ( 3 ), a transfer nip ( 15 ), wherein sheets (F 1 -Fn) cut by the cutting roller ( 7 ) are transferred from the respective cutting roller ( 7 ) to the corresponding folding roller ( 3 ) in the transfer nip ( 15 ).
12. The interfolding machine ( 1 ) according to claim 11 , wherein the suction chamber ( 23 A) of each folding roller ( 3 ) extends from the transfer nip ( 15 ) towards the folding nip ( 5 ) and downstream of said folding nip ( 5 ).
13. The interfolding machine ( 1 ) according to claim 7 , wherein a removing member ( 17 ) is associated with each folding roller ( 3 ), the removing member configured and arranged to remove sheets (F 1 -Fn) from a respective folding roller ( 3 ).
14. The interfolding machine according to claim 13 , wherein the suction chamber ( 23 A) of each folding roller ( 3 ) extends downstream of the folding nip ( 5 ) up to an area where the removing member ( 17 ) operates.
15. A folding roller ( 3 ) comprising:
a cylindrical sleeve ( 3 C) having a rotation axis ( 3 A), an outer surface ( 3 X) and an inner surface ( 3 Y) delimiting an axial cavity ( 23 ) of the cylindrical sleeve ( 3 C);
an inner body ( 25 ) axially extending in the axial cavity ( 23 ) of the cylindrical sleeve ( 3 C), the cylindrical sleeve ( 3 C) arranged so as to rotate around the inner body ( 25 );
a suction chamber ( 23 A) inside the cylindrical sleeve ( 3 C);
a plurality of suction holes ( 41 , 43 ) extending from the outer surface ( 3 X) up to the inner surface ( 3 Y) of the cylindrical sleeve ( 3 C); wherein the suction holes are arranged according to longitudinal alignments ( 42 , 44 ) that are substantially parallel to the rotation axis ( 3 A) of the cylindrical sleeve ( 3 C) and angularly spaced apart with respect to one another;
wherein inside the suction chamber ( 23 A) a plurality of stationary shutters ( 37 ) are arranged, spaced from one another along the rotation axis ( 3 A) of the cylindrical sleeve ( 3 C), each shutter ( 37 ) having a closing surface ( 37 A) co-acting with the inner surface ( 3 Y) of the cylindrical sleeve ( 3 C) to close selected suction holes ( 41 ) of the plurality of suction holes ( 41 , 43 ), wherein the plurality of suction holes ( 41 , 43 ) are subdivided into a plurality of first longitudinal alignments ( 42 ) and into a plurality of second longitudinal alignments ( 44 ), alternating with, and angularly spaced apart from one another, and wherein the plurality of suction holes ( 41 , 43 ) are configured and arranged so that, during rotation of the cylindrical sleeve ( 3 C), the selected suction holes ( 41 ) of the first longitudinal alignments ( 42 ) are closed by the shutters ( 37 ) while the remaining suction holes ( 43 ) of the second longitudinal alignments ( 44 ) are not closed by the shutters ( 37 ).
16. The folding roller ( 3 ) according to claim 15 , wherein the selected suction holes ( 41 ) of each first longitudinal alignment ( 42 ) are circumferentially aligned with the shutters ( 37 ) and are closed by said shutters, while the remaining suction holes ( 43 ) of each second longitudinal alignment ( 44 ) are displaced with respect to the shutters ( 37 ), so that they are not closed by the shutters ( 37 ).
17. The folding roller according to claim 15 , wherein the inner surface ( 3 Y) of the cylindrical sleeve has, in correspondence of the remaining suction holes ( 43 ) of each second longitudinal alignment ( 44 ), grooves which prevent the shutters ( 37 ) from closing the suction holes ( 43 ) of each second longitudinal alignment ( 44 ).
18. The folding roller ( 3 ) according to claim 15 , wherein each longitudinal alignment ( 42 , 44 ) of suction holes ( 43 , 41 ) comprises two adjacent lines of suction holes.