Folding or interfolding unit for folding or interfolding sheets of paper

Abstract

A folding or interfolding unit includes first and second folding or interfolding rolls to fold or interfold the sheets of paper according to a predetermined folding or interfolding configuration. The first and second folding or interfolding rolls include, respectively, a tubular body configured to rotate in a predetermined direction of rotation about a longitudinal rotation axis, and gripping groups, each of which includes a mechanical gripping member configured to move, at a gripping point, from an opening position to a closing position, which is arranged to mechanically hold the sheets up to a releasing point. Each gripping group includes at least one suction hole associated to each mechanical gripping member. A vacuum distribution device selectively pneumatically connects at least one suction hole at a time to a device for generating a predetermined vacuum degree, to cause the sheets of paper to adhere between starting and ending positions.

Claims

1. A folding or interfolding unit of a plurality of sheets of paper, comprising: a first and a second folding or interfolding roll configured to fold or interfold, said plurality of sheets of paper according to a predetermined folding or interfolding configuration, at a folding or interfolding zone, each said first and second folding or interfolding roll including: a tubular body configured to rotate in a predetermined direction of rotation about a longitudinal rotation axis oriented along a horizontal direction; a plurality of gripping groups each of which includes: a mechanical gripping member comprising a movable part and a fixed part, said movable part being configured to move, at a gripping point having a first predetermined angular position, from an opening position to a closing position with respect to said fixed part, in said closing position said mechanical gripping member being arranged to mechanically hold said or each sheet of said plurality of sheets up to a releasing point having a second predetermined angular position; and at least one suction hole associated to each mechanical gripping member and configured to cause said or each sheet of paper to be sucked between a position of starting suction and a position of ending suction introduce the same into said mechanical gripping member; and an actuation group configured to cause a movable element at a time to move from said opening position to said closing position and vice versa; said actuation group including: an opening device that is a cam device and is configured to selectively cause a movement of a movable element at a time from said closing position to said opening position, at said releasing point; and a closing device configured to cause a movable element to move from said opening position to said closing position at said gripping point; wherein said cam device comprises a support shaft rotatably connected to a respective folding or interfolding roll, and arranged to support said movable part, each support shaft being engaged at an end portion of an actuation shaft; and wherein said cam device further comprises a feeler member arranged to engage at a second end of said actuation shaft, said feeler member being arranged to move along a fixed guide member and configured to cause said movable part to change inclination with respect to said fixed part at said gripping and releasing points to cause the same to move from said closing position to said opening position and vice versa.

2. The folding or interfolding unit according to claim 1, further comprising a first and a second plurality of detaching fingers are, furthermore, provided configured to cause said plurality of sheets of paper to be removed from an external surface of a respective folding or interfolding roll.

3. The folding or interfolding unit according to claim 1, further comprising a separation group including a first and a second plurality of separation members configured to enter from opposite sides into a completed stack of folded or interfolded sheets of paper, separating the same from a following stack of folded or interfolded sheets of paper.

4. The folding or interfolding unit according to claim 1, wherein said fixed guide member is a shaped groove and wherein said feeler member is arranged to slidingly engage in said shaped groove.

5. The folding or interfolding unit according to claim 1, wherein said closing device is an elastic return member configured to exert on said movable part an elastic return force arranged to oppose said movement from said closing position to said opening position.

6. The folding or interfolding unit according to claim 1, wherein said at least one suction hole is positioned on said fixed part of the respective mechanical gripping member.

7. The folding or interfolding unit according to claim 6, wherein each said gripping group is associated to an auxiliary suction hole positioned upstream of each said mechanical gripping member with respect to the direction of rotation of the first or second folding or interfolding roll and positioned at the external lateral surface of said first or second folding or interfolding roll.

8. The folding or interfolding unit according to claim 1, wherein said external surface of said first and second folding or interfolding roll is provided with a plurality of lateral suction holes distributed longitudinally to said respective tubular body.

9. The folding or interfolding unit according to claim 1, wherein said movable part of each mechanical gripping member is made of a flexible material.

10. The folding or interfolding unit according to claim 1, wherein said movable part is made of a harmonic steel, in such a way to elastically move from said closing position to said opening position and vice versa.

11. The folding or interfolding unit according to claim 1, wherein said fixed guide member is a shaped groove and wherein said feeler member is arranged to slidingly engage in said shaped groove.

12. A folding or interfolding unit of a plurality of sheets of paper, comprising: a first and a second folding or interfolding roll configured to fold or interfold, said plurality of sheets of paper according to a predetermined folding or interfolding configuration, at a folding or interfolding zone, each said first and second folding or interfolding roll including: a tubular body configured to rotate in a predetermined direction of rotation about a longitudinal rotation axis oriented along a horizontal direction; a plurality of gripping groups each of which includes: a mechanical gripping member comprising a movable part and a fixed part, said movable part being configured to move, at a gripping point having a first predetermined angular position, from an opening position to a closing position with respect to said fixed part, in said closing position said mechanical gripping member being arranged to mechanically hold said or each sheet of said plurality of sheets up to a releasing point having a second predetermined angular position; and at least one suction hole associated to each mechanical gripping member and configured to cause said or each sheet of paper to be sucked between a position of starting suction and a position of ending suction introduce the same into said mechanical gripping member; and an actuation group configured to cause a movable element at a time to move from said opening position to said closing position and vice versa; said actuation group including: an opening device that is a cam device and is configured to selectively cause a movement of a movable element at a time from said closing position to said opening position, at said releasing point; and a closing device configured to cause a movable element to move from said opening position to said closing position at said gripping point; wherein each folding or interfolding unit further comprises: a vacuum distribution device is, furthermore, provided configured to selectively pneumatically connect at least one suction hole of said first and second folding or interfolding rolls at a time to a device for generating a predetermined vacuum degree in such a way to cause said or each sheet of paper to be sucked between said position of starting suction and said position of ending suction; and a fixed tubular body positioned coaxially to said tubular body, said fixed tubular body being provided with an external lateral surface and an internal lateral surface pneumatically connected to each other by at least an aperture and a longitudinal cavity pneumatically connected to said device for generating a predetermined vacuum degree; and wherein said vacuum distribution device comprises: a suction chamber pneumatically connected to said longitudinal cavity and delimited by an internal lateral surface of said tubular body and laterally by a first and a second sealing member arranged to extend longitudinally to said tubular body, said suction chamber being configured to selectively pneumatically connect said longitudinal cavity to a suction hole at a time between said first and second predetermined angular positions.

13. Folding or interfolding unit of a plurality of sheets of paper, comprising: a first and a second folding or interfolding roll configured to fold or interfold, said plurality of sheets of paper according to a predetermined folding or interfolding configuration, at a folding or interfolding zone, each said first and second folding or interfolding roll including: a tubular body configured to rotate in a predetermined direction of rotation about a longitudinal rotation axis oriented along a horizontal direction; a plurality of gripping groups each of which includes: a mechanical gripping member comprising a movable part and a fixed part, said movable part being configured to move, at a gripping point having a first predetermined angular position, from an opening position to a closing position with respect to said fixed part, in said closing position said mechanical gripping member being arranged to mechanically hold said or each sheet of said plurality of sheets up to a releasing point having a second predetermined angular position; and at least one suction hole associated to each mechanical gripping member and configured to cause said or each sheet of paper to be sucked between a position of starting suction and a position of ending suction introduce the same into said mechanical gripping member; and an actuation group configured to cause a movable element at a time to move from said opening position to said closing position and vice versa; wherein said actuation group comprises a desmodromic cam comprising a shaped guide in which a feeler member is arranged to slidingly engage, said shaped guide comprising at least one opening stretch configured to cause said movable part to change inclination with respect to said fixed part of said gripping member to bring the same in said opening position, and at least one closing stretch arranged to cause said movable part to change inclination with respect to said fixed part of said gripping member to bring the same in said closing position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be shown with the following description of its exemplary embodiments, exemplifying but not limitative, with reference to the attached drawings in which:

(2) FIG. 1 diagrammatically shows a side elevation partly sectioned view of a first embodiment of a folding or interfolding unit according to the invention;

(3) FIG. 2 diagrammatically shows a transverse section view of one possible embodiment of a folding or interfolding roll, of which the folding or interfolding unit of FIG. 1 can be equipped with;

(4) FIG. 3 shows an enlargement of a portion of the folding or interfolding roll of FIG. 2 to highlight some technical characteristics;

(5) FIG. 4 diagrammatically shows a possible alternative embodiment of the folding or interfolding unit of FIG. 1 foreseen by the invention;

(6) FIG. 5 shows an enlargement of the folding or interfolding zone of the folding or interfolding unit of FIG. 4 to highlight some technical characteristics;

(7) FIG. 6A diagrammatically shows another possible alternative embodiment foreseen by the invention for the folding or interfolding unit of FIG. 1;

(8) FIG. 6B shows an enlargement of the folding or interfolding zone of the folding or interfolding unit of FIG. 6A to highlight some technical characteristics;

(9) FIG. 7A diagrammatically shows still another possible alternative embodiment foreseen by the invention for the folding or interfolding unit of FIG. 1;

(10) FIG. 7B shows an enlargement of the folding or interfolding zone of the folding or interfolding unit of FIG. 7A to highlight some technical characteristics;

(11) FIG. 8 diagrammatically shows a transverse section view of another possible embodiment of a folding or interfolding roll, of which the folding or interfolding unit according to the invention can be equipped with;

(12) FIG. 9 shows an enlargement of a portion of the folding or interfolding roll of FIG. 8 to highlight some features;

(13) FIGS. 10A to 10D diagrammatically show a possible operative sequence carried out by an embodiment foreseen by the invention of an actuation group of a folding, or suction roll;

(14) FIG. 11 diagrammatically shows a transverse section view of an alternative embodiment of the actuation group of a of a folding, or suction roll of the FIGS. 10A-10D;

(15) FIG. 12 diagrammatically shows a further embodiment of the invention for the folding or interfolding unit according to the invention.

DETAILED DESCRIPTION OF SOME EXEMPLARY EMBODIMENTS OF THE INVENTION

(16) As diagrammatically shown in FIG. 1, a first embodiment of a folding or interfolding unit 100, according to the invention, for folding or interfolding a plurality of sheets of paper 5 comprises a first and a second folding or interfolding roll 1a and 1b configured to fold or interfold the aforementioned plurality of sheets of paper 5 according to a predetermined folding or interfolding configuration, at a folding or interfolding zone 35. In particular, each of the first and the second folding or interfolding roll 1a and 1b comprises a tubular body 10 provided with an external lateral surface 11 and configured to rotate in a predetermined direction of rotation 110 about a longitudinal rotation axis 101, in particular oriented along a horizontal direction, or substantially horizontal. In particular, the first and second folding rolls 1a and 1b are counter-rotating. The first and the second folding or interfolding rolls, 1a, or 1b are, furthermore, provided, respectively, with a plurality of mechanical gripping groups 30, each of which comprising a mechanical gripping member 15, in the following also called pliers member. More precisely, each pliers member 15 is configured to move, at a gripping point P1 having a first predetermined angular position, from an opening position to a closing position, in which is arranged to mechanically hold the or each sheet 5 up to a releasing point P2 having a second predetermined angular position in which is arranged to release the sheet 5.

(17) Still as diagrammatically shown in FIG. 1 the folding or interfolding unit 100 can provide, furthermore, a first and a second plurality of detaching fingers 40a and 40b configured to cause the aforementioned plurality of sheets of paper 5 to be detached from the external surface 11 of a respective folding or interfolding roll 1a and 1b. In particular, the first and the second pluralities of detaching fingers 40a and 40b are advantageously moved in phase with the folding or interfolding rolls 1a and 1b, in such a way that it can, alternatively laterally and/or vertically move towards the or each worked sheet 5, and move the same away from the respective roll 1a, or 1b, thus causing the same to be detached from the surface of the roll to which it adheres.

(18) In particular, still as diagrammatically shown in FIG. 1, the folding or interfolding machine equipped with the folding or interfolding unit 100, according to the invention, furthermore, provides a separation group comprising a first and a second plurality of separation members 45a and 45b, configured to enter from opposite sides into a completed stack of folded or interfolded sheets 150a, and to separate the same from a following stack of folded or interfolded sheets, not shown in the figure for simplicity. More in particular, a displacement unit, not shown in the figure for simplicity, is provided configured to displace the separation members 45a and 45bbetween a first and a second position along a predetermined back and forth displacement trajectory with respect to the respective folding or interfolding rolls 1a and 1b.

(19) According to the present invention each gripping group 30 comprises, furthermore, at least one suction hole 16. In particular, the or each suction hole 16 is arranged to cause the, or each, sheet of paper 5 to be sucked in order to introduce the same into the pliers member 15. More in particular, the or each suction hole 16 can be pneumatically connected to a device for generating a predetermined vacuum degree, not shown in the figure for simplicity reasons, through a vacuum distribution device. This latter is configured to selectively pneumatically connect a suction hole 16 of the first or second folding or interfolding roll, 1a, or 1b, to the aforementioned device for generating a predetermined vacuum degree and to cause the, or each, sheet to be sucked between a position of starting suction P1 and a position of ending suction

(20) P2. In particular, the or each suction hole 16 can be pneumatically connected to the aforementioned device for generating a predetermined vacuum degree between a point of starting suction P1 preferably positioned upstream of the gripping point and a point of ending suction P2 positioned upstream or downstream, of the releasing point. Generally, the suction hole 16 is, advantageously, positioned within the external lateral surface 11 of the respective folding or interfolding roll, 1a, or 1b.

(21) The particular technical solution provided by the present invention allows, with respect to the prior art solutions, to work the sheets 5 in order to fold or interfold them, at a high velocity, also higher than 300 m/min, in particular because the mechanical gripping members 15 associated to the aforementioned suction holes 16 are able to take and release the or each worked sheet 5 at extremely accurate angular positions besides exerting a higher gripping strength on the, or each, sheet 5. Furthermore, the present solution allows to avoid the use of wedges, or other mechanical introduction members, to introduce the sheets of paper into the gripping members 15.

(22) As for example diagrammatically shown in FIG. 2, in a preferred embodiment of the invention, each folding or interfolding roll, 1a and 1b comprises, furthermore, a fixed tubular body 20 positioned coaxially to the tubular body 10. The fixed tubular body 20, preferably cylindrical, is, in particular, provided with an external lateral surface 21 and an internal lateral surface 22 pneumatically connected one another by at least an aperture 25, in particular a longitudinal aperture, and a longitudinal cavity 24 pneumatically connected to the aforementioned device for generating a predetermined vacuum degree.

(23) More precisely, the vacuum distribution device comprises a suction chamber 26 pneumatically connected to the longitudinal cavity 24 and delimited by an internal lateral surface 12 of tubular body 10 and, laterally, by a first and a second sealing member 23a and 23b arranged to extend longitudinally tubular body 10, in to the particular along respective radial directions. More in particular, the suction chamber 26 is configured to selectively pneumatically connect the aforementioned longitudinal cavity 24 to at least one suction hole 16 at a time between the aforementioned predetermined angular positions P1 and P2, in such a way to cause the, or each, sheet to be sucked by the roll 1a, or 1b and, therefore, to assist the pliers member 15 to grip the same.

(24) In particular, the machine equipped with the folding unit 100 as described above is arranged to operate as multi-fold machine, in particular to produce Z, or W, interfolded products or even more panels. As known, in this type of paper converting machines a single web of paper is worked and a succession of sheets, which are already partly overlapped to each other, arrives to the folding or interfolding unit from one only direction.

(25) According to an embodiment of the invention, the external surface 11 of each folding or interfolding roll 1a, or 1b, can be, furthermore, provided with a plurality of lateral suction holes 3 distributed longitudinally to the aforementioned tubular body 10. In particular, the aforementioned lateral suction holes 3, preferably oriented along respective radial directions, are selectively operated by a secondary vacuum distribution device. More in particular, the secondary vacuum distribution device is configured to selectively connect at least one row of the aforementioned rows of lateral suction holes 3 to the aforementioned device for generating a predetermined vacuum degree, or with a supplementary device for generating a predetermined vacuum degree, at a predetermined second portion of the surface 11 of the folding or interfolding roll, 1a, or 1b, comprised preferably between a point positioned upstream of, or coincident with, the point of starting suction P1 and a point positioned downstream of, or coincident with, the point of ending suction P2.

(26) In particular, as diagrammatically shown in FIG. 4, each secondary vacuum distribution device can provide a longitudinal channel 81 made within the tubular body 10 pneumatically connected and associated respectively to the series of lateral suction holes 3, a shaped cavity, or lateral suction sector 80, associated to the tubular body 10 of each folding or interfolding roll 1a, or 1b, whose position is diagrammatically indicated in FIG. 4 with a broken line. More in particular, the lateral suction section 80 can be permanently connected to the secondary device for vacuum generating to selectively connect the rows of lateral suction holes 3. More precisely, by the lateral suction sector 80 associated to the tubular body 10, the rows of lateral holes 3 can be pneumatically connected with the aforementioned device for vacuum generating, only at determined angular positions of the holes. The lateral suction sector 80 is normally fixed, i.e. it does not rotate together with the tubular body 10, but can be movable, i.e. rotating about an axis coaxial to that of the tubular body 10, to carry out adjustments in such a way to modify the point of starting suction and the point of ending suction of the lateral suction holes 3. More in particular, the aforementioned lateral suction sectors 80 can be bell vacuum distributors coaxially arranged at an end of the tubular body 10 of each folding or interfolding roll 1a, or 1b. In particular, each bell distributor device can be arranged coaxially to the tubular body 10, and is preferably fixed. Therefore, during the rotation of the tubular body 10, some zones, or sectors, are formed where the lateral suction holes 3 suck and hold, therefore, on the external surface 11 of the respective tubular body 10, at least one sheet 5, in particular at the head 5a, or at the tail 5b, of the same, some others, instead, where the sheet is not sucked (see FIG. 5). In this case, each pliers member 15 will be arranged to hold a sheet 5, in FIG. 5 the sheet 5 which is adhering to the surface 11 of the right roll 1b, in particular at the centre line, and at the same time the tail 5b and the head 5a of two following sheets 5 and 5 which are adhering to the surface 11 of the other roll, in FIG. 5 the left roll 1a, held up that instant by a respective lateral suction hole 3 of the same couple of longitudinal rows of lateral suction holes 3. In the FIGS. 6A and 6b a folding or interfolding unit 100 is diagrammatically shown comprising a first and a second folding or interfolding roll 1a and 1b according to the invention, in the case of a multi-fold machine and, therefore, not provided with the aforementioned lateral suction holes 3. In this case, the machine will be therefore able to produce Z, or W, interfolded products or having even more panels.

(27) In the embodiment diagrammatically shown in the FIGS. 7A and 7B, the folding or interfolding unit 100 comprises, instead, both the mechanical gripping groups 30 according to the invention, and the lateral suction holes 3. In this case, the folding or interfolding machine, equipped with tale folding or interfolding unit 100 will be able to work both as a single-fold machine, in particular for producing V interfolded products, and as multi-fold machine.

(28) In particular, as known, the single-fold machines work two webs of paper, which are cut in such a way to obtain two staggered sequences of sheets that are, then, alternately fed to the folding or interfolding rolls 1a and 1b. In this way, each sheet coming from a first direction is overlapped, for half a sheet, to a portion of the sheet coming from a second direction, and vice versa, at the moment when the fold is carried out.

(29) In an embodiment foreseen, a machine for folding or interfolding sheets of paper 5 can be equipped with a folding unit 100 comprising both the mechanical gripping groups 30 according to the invention, and the suction holes 3, and can be provided with a selection device, not shown in FIG. 9B for simplicity, configured to pneumatically disconnect, in particular by electric valves, the suction holes 3 and the aforementioned device for vacuum generating. In this case, therefore, the machine for folding or interfolding sheets of paper 5 is highly flexible because it is able to work both as single-fold machine by connecting the suction holes 3 to the aforementioned device for vacuum generating, and as multi-fold machine, in the case diagrammatically shown in FIG. 7B, by pneumatically disconnecting the suction holes 3 and the aforementioned device for vacuum generating by means of the aforementioned selection device, or simply deactivating the device for vacuum generating.

(30) As diagrammatically shown in the figures from 1 to 5, and in detail in the FIGS. 3 and 5, each suction hole 16 of a gripping group 30 is positioned on the fixed part 15b of the respective gripping member 15 and is, advantageously oriented towards the movable part 15a of this. In particular, each suction hole 16 is not positioned on the external lateral surface 11 of the respective folding or interfolding roll 1a, or 1b, but at an internal position with respect to the same. Preferably, each suction hole 16 is positioned at the fixed part 15b of a respective pliers member 15 and, advantageously, faces towards the movable part 15a of this.

(31) In the alternative embodiments diagrammatically shown in the figures from 7A to 8B, each gripping group 30 according to the invention, further to the aforementioned suction hole 16, can comprise at least one secondary suction hole 17 positioned at the opposite side of the suction hole 16 with respect to the gripping member 15. In particular, each secondary suction hole 17 can be positioned at the external surface of the folding or interfolding roll 1a, or 1b, in particular downstream of the respective mechanical gripping member 15 with respect to the direction of rotation 110. More in particular, the secondary suction hole 17 can be pneumatically connected to the suction hole 16 associated to the same pliers member 15 by a connection duct 18. In this way it is possible to pneumatically connect, or disconnect, both the suction hole 16 and the secondary suction hole 17 by the same vacuum distribution device.

(32) Advantageously, in a further embodiment foreseen and diagrammatically shown in the FIGS. 8 and 9 each gripping group 30 can comprise a further auxiliary suction hole 19 positioned at the same side of the respective suction hole 16, but positioned at the external lateral surface 11 of the first and of the second folding or interfolding roll 1a, and 1b. In particular, as shown, in detail in FIG. 9, in this case, the suction duct 14 of each gripping group 30 divides into two branches, one of which ends with the suction hole 16 arranged in an internal position of the roll 1a, or 1b with respect to the lateral surface 11 of the same, instead the other ends with the further auxiliary suction hole 19 positioned, as anticipated above, on the surface 11 of the same roll 1a, or 1b. In particular, the further auxiliary suction hole 19 helps to stabilize the sheet 5 on the respective folding or interfolding roll 1a, and 1b assuring that it is correctly stretched on the external lateral surface 11 and introduced into the mechanical gripping member 15 for a sufficient portion.

(33) As diagrammatically shown in the enlargements of the FIGS. 3, 5, 7 and 9, the gripping member 15 can comprise a movable part 15a arranged to move from/towards a fixed part 15b to move from a closing position to an opening position and vice versa.

(34) The folding or interfolding unit 100, according to the invention, can comprise, furthermore, an actuation group configured to cause a pliers member 15 at a time of the aforementioned plurality of pliers members 15 to move from the opening position to the closing position and vice versa at determined angular positions of the tubular body 10 during its rotation about the longitudinal rotation axis 101.

(35) In a possible embodiment foreseen, the aforementioned actuation group can comprise an opening device configured to selectively cause a pliers member 15 at a time to move from an opening position to a closing position at a predetermined angular position of the tubular body 10, in such a way to allow the same to hold the or each worked sheet 5. In particular, each mechanical gripping member 15 can comprise a movable part 15a arranged to move towards, or from, a respective fixed part 15b. More in particular, a closing device can be, furthermore, provided configured to cause the pliers member 15 to move from the opening position to the closing position. More precisely, the closing device and the opening device can be configured to move the movable part 15a of a mechanical gripping member 15 at a time from a closing position to an opening position with respect to the respective fixed part 15b, in such a way to allow the, or each, sheet 5 to be positioned at an engagement position arranged upstream of the movable part 15a of the mechanical pliers member 15. In this way, the or each sheet 5 can be arranged at an engagement position internal to the external lateral surface 11 of the tubular body 10 of the first or second folding or interfolding roll 1a, or 1b, in particular for the contemporary suction action carried out by the, or each, respective suction hole 16. Then, the closing device and the opening device are arranged to bring the pliers member 15 back from the opening position to the closing position.

(36) As diagrammatically shown in the figures from 10A to 10D, the opening device can be a cam device 60. In particular, each pliers member 15 is operatively connected to a support shaft 63 rotatably connected to the tubular body 10, preferably by bearings, not shown for simplicity. In this way, each shaft 63 is rotationally integral with the tubular body 10, but, at the same time, is able to rotate with respect to a respective rotation axis 163, to operate the opening and closing movements of the movable part 15a of the respective pliers member 15.

(37) In particular, an engagement portion, advantageously an end portion 61a of an actuation shaft 61 fitting on each support shaft 63. At another engagement portion, advantageously the other end portion 61b, the same actuation shaft 61 is arranged to support a feeler member 62, in particular of mechanical type, that is able to rotate about a respective rotation axis 162. In particular, the feeler member 62 is arranged to slide along the guide member 70, or sliding race, during the rotation of the folding or interfolding roll 1a, or 1b about its longitudinal rotation axis 101.

(38) More in particular, the guide member 70 is a cam configured in such a way to guide the feeler member 62, and, therefore, the respective actuation shaft 61, along a predetermined trajectory. More precisely, the guide member 70 is fixed with respect to the respective folding or interfolding roll 1a, or 1b, and is arranged to cause the movable part 15a of the pliers member 15 to change inclination with respect to the fixed part 15b at predetermined angular positions to cause the aforementioned movement from the closing position to the opening position. Advantageously, the feeler member 62 can be maintained in contact with the guide member 70 by a push member 65 or can be slidingly engaged into a shaped groove, also this not shown in the figure for simplicity. For example, the feeler member 62 can be provided with a rolling member, for example a roller, or a wheel, arranged to slide along the aforementioned guide member 70.

(39) In the embodiment diagrammatically shown in the figures from 10A to 10D, the push member 65 is an elastic return member. In particular, the elastic return member 65 is configured to apply on a respective pliers member 15, in particular on the movable part 15a of the same, an elastic return force arranged to oppose the movement from the closing position to the opening position caused by the cam opening device 60. More precisely, the elastic strength of the return member 65 is configured to maintain the movable part 15a in the closing position (stretch from P1 to P2 of FIGS. 10A-10D), but is, however, less than the opening strength due to the push exerted by the guide member 70 on the feeler member 62 between the positions P3 and P0 of the guide member 70. In particular, between the point P3 and the point P0 the opening strength exceeds the elastic strength of the return member 65 and causes the actuation shaft 61, and therefore the support shaft 63, to rotate causing the pliers member 15 to rotate to be opened. More precisely, at the stretch comprised between P0 and P1 the cam opening device 60 is arranged to cause the pliers member 15 to move from a minimum opening position to a maximum opening position at point P1, where at a step of the guide member 70, the push strength on the feeler member 62 is suddenly reduced and the same is overcome by the elastic strength of the return member 65, which brings the pliers member 15 in the closing position at the gripping point P1 (diagrammatically shown in FIG. 10D) in which it remains until the feeler member 62 arrives at point P2, at which the pliers member 15 is in position P2 (diagrammatically shown in FIG. 10C).

(40) In the stretch between P2 and P3, instead, the cam opening device 60 is arranged to bring the movable part 15a of the pliers member 15 from the closing position to the opening position, in which is far-removed from the fixed part 15b (as can be deduced comparing FIGS. 10C and 10D). More precisely, the cam device 60, during the sliding along the stretch comprised between P0 and P1 of the guide member 70 by the feeler member 62, progressively causes the movable part 15b of the gripping member 15 to move from an intermediate opening position to a maximum opening position. Then, when the feeler member 62 runs the stretch comprised between P1 and P2 the return member 65 causes the movable part 15b of the gripping member 15 to move in the closing position. Then, when the feeler member 62 arrives at the position P3, the guide member 70 causes the movable part 15b of the gripping member 15 to move from the closing position to a starting opening position and, at the end, when the feeler member 62 arrives at the position P4, the cam device 60 causes the movable part 15b of the gripping member 15 to move in an intermediate opening position that is maintained until the feeler member 62 arrives again at the position P0. In this way at point P2 of the feeler member 62 and therefore at point P2 of the pliers member 15, the sheet 5 as well as the tail 5b and the head 5a of two following sheets 5 and 5 are released.

(41) According to an embodiment of the invention, the actuation group can comprise a desmodromic cam configured to cause the pliers member 15, in particular its movable part 15a, to move from the opening position to the closing position and vice versa, that means from the closing position to the opening position with respect to the respective fixed part 15b. In particular, in this case the guide member 70 comprises a stretch where is arranged to cause the movable part 15a to move from the closing position to the opening position and a stretch where is arranged to cause the movable part 15a to move from the closing position to the opening position.

(42) As diagrammatically shown in FIG. 11, the guide member 70 can be a shaped groove in which each feeler member 62 of each arm 61 is arranged to slide in order to be guided along a predetermined trajectory, during the rotation of the respective folding or interfolding roll 1a, or 1b. In particular, each feeler member 62 can comprise a first and a second rolling member, each of which configured to slide on a respective sliding race of guide member 70, which forms the shaped groove (in FIG. 11 only one rolling member and the respective sliding race are shown for clarity reasons). In this way, the feeler member 62 can operate the opening of the pliers member 15 by interaction of the first rolling member with one of the two races of the guide member 70. Vice versa, the closing of the pliers member 15 is obtained by interaction of the second rolling member of the feeler member 62 with the second race of the guide member 70. The use of desmodromic cam allows to avoid the use of the push member 65. More precisely, the shaped groove 70 has a geometry such that when the pliers member 15 reaches a predetermined angular position P0, the movable part 15a begins to progressively move away, in particular by rotating, from the fixed part 15b. In particular, when the first rolling member of the feeler member 62 moves along an opening stretch 71 of the first race of the shaped groove 70 causes the arm 61 and, therefore, the support shaft 63 to rotate in order to cause the pliers member 15 to open. The shaped groove 70 provides, then, a closing stretch 72 of the second race a geometry such that when the second rolling member of the feeler member 62 arrives at another angular position causes the movable part 15a to close towards the fixed part 15b, in such a way to hold the or each worked sheet. Then, when during the rotation of the roll 1a, or 1b, about the respective longitudinal axis 101, the first rolling member of the feeler member 62 reaches at a following predetermined angular position of a following second opening stretch 73 of the first race of the shaped groove 70 is forced to cause again the pliers member 15 to open, in such a way to allow the same to release the sheet, and then to go back to the position far removed from the fixed part 15b once that a further angular position of a third opening stretch 74 of the shaped groove 70 is reached. Therefore, in this case, the opening device and the closing device are formed by respective shaped stretches of the guide member 70, in particular of the shaped groove. More precisely, analogously to what is described above with reference to the figures from 10A to 10D, at the opening stretch 71, the guide member 70 is configured in such a way to move the movable part 15b of the gripping member 15 from an intermediate opening position to a maximum opening position and, then, at the closing stretch 72 to cause the sudden movement in the closing position and, therefore, at the stretch 73, the movement from the closing position to a starting opening position and, at the end, at the stretch 74 in an intermediate opening position, which is maintained until it passes again the opening stretch 71.

(43) In an embodiment foreseen, the movable part 15a of each pliers member 15 can be made of a flexible material, advantageously in harmonic steel, in such a way to elastically move from the closing position to the opening position and vice versa.

(44) In the further embodiment of the invention that is diagrammatically shown in FIG. 12, each folding or interfolding roll, 1a and 1b comprises, furthermore, a respective cutting device 90 provided with at least one cutting blade 95. In this case, each first and second folding or interfolding roll, 1a and 1b is respectively, provided, in particular between a couple of lateral suction holes 3, as diagrammatically described above with reference to the embodiments of FIGS. 4 and 8, of a first and a second plurality of counter-blades 8 distributed along the respective tubular body 10. More precisely, the counter-blades 8 of each roll 1a and 1b are arranged to cooperate with the respective cutting blade 95 to divide a first and a second web of paper 105a and 105b, or similar products, in a first and a second plurality of sheets 5. For clarity reasons, in FIG. 13 are not shown the pliers members 15 and the respective suction holes 16 which can be, anyway, of the type described above with reference to the figures from 1 to 12. In particular, in this case, the counter-blade 8 of a roll, for example of roll 1a, at the folding or interfolding zone, 35 can act as introduction member and, therefore, assist the introduction of the, or each, worked sheet 5 within the pliers member 15 of the other roll, for example of the roll 1b.

(45) Also in the embodiment of FIG. 12 are present, but not shown for simplicity, both the first and the second plurality of detaching fingers 40a and 40b as well as the first and the second plurality of separation members 45a and 45b having the same functionality described above.

(46) The foregoing description exemplary embodiments of the invention will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiment without further research and without parting from the invention, and, accordingly, it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realize the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation.