CN116490450A - Folding or cross-folding unit for paper webs or sheets in paper processing machines - Google Patents

Abstract

A folding or cross-folding unit of a paper web or sheet comprises first and second folding or cross-folding rollers (1 a,1 b) of the paper web or sheet, which rollers are configured to fold or cross-fold the paper web or sheet at a folding or cross-folding zone (35) arranged between the first and second folding or cross-folding rollers (1 a,1 b) according to a predetermined folding or cross-folding configuration. The folding or cross-folding unit further comprises a first and a second plurality of separating fingers (40 a,40 b) configured to separate the paper web or sheet from the outer surface (11) of the respective folding or cross-folding roller (1 a,1 b). Furthermore, a first and a second actuation group (80 a,80 b) are provided, which are configured to cause a back-and-forth oscillating movement of the first and the second plurality of separating fingers (40 a,40 b) towards/away from the folding or cross-folding zone (35), respectively, so as to separate the respective paper web or sheet from the first and the second folding or cross-folding rollers (1 a,1 b), respectively. The first and second actuation groups (80 a,80 b) are further configured to retard or advance the oscillating movement of the first and second plurality of separating fingers (40 a,40 b), respectively, relative to a predetermined reference oscillating movement, thereby retarding or advancing the moment (tr) at which the first and second plurality of separating fingers (40 a,40 b) are arranged to cause the paper web or sheet to separate from the first and second folding rollers, respectively.

Description

Folding or cross-folding unit for paper webs or sheets in paper processing machines

Description

Technical Field

The present invention relates to the technical field of paper processing, and similar products, and in particular to a machine for cross-folding paper webs or sheets.

The invention also relates to a method of folding or cross-folding a paper web or sheet according to a determined cross-folding configuration.

Description of the Prior Art

As is known, in the paper industry, many machines and processes are used to produce tissues, towels and similar products formed into stacks of sheet material having a defined height that is cross-folded. These products are produced by folding the sheets in a cross-folded manner, meaning that the final edge of the previous sheet and the starting edge of the next sheet are closed at each fold.

In this way, when the product is used, the initial edge of the next sheet is also removed when the sheets are removed from the stack, thus simplifying the use of the product in some applications.

Cross-folding machines of known type process one or more paper webs from one or more reels, which are cut into sheets of predetermined length at a cutting unit and fed alternately to a folding unit where two counter-rotating folding rollers operate. Rather, the cutting of the individual sheets of web material is performed on a cutting roll, which alternately cooperates with an associated counter blade.

Among the possible ways of folding the sheet, in particular, an "L" shaped cross fold with two panels, a "Z" shaped cross fold with three panels and a "W" shaped cross fold with 4 panels are known.

In the case of an "L" shaped cross-fold obtained by a "single-fold" machine of the type described for example in US6228014, the paper web is cut so that two interleaved sheet sequences are formed, which are fed alternately to the folding rollers. In this way, approximately half of each sheet from the first direction overlaps a portion of the sheet from the second direction and vice versa when folding is performed.

In the case of "Z" -shaped, "W" -shaped, cross-folded or even more panels obtained by a "multi-folding" machine of the known type, for example as described in US3490762, only one paper web is processed and for the folding roller the sheet sequence comes from only one direction, which sheet sequence already partially overlaps each other. As described in EP1520822, the overlap between two subsequent sheets is made immediately after cutting by a transfer roller and a delay roller which together create a small crease in the preceding sheet, the latter sheet being located partly underneath the preceding sheet.

In both single-folding and multi-folding machines, the folding rollers have circumferences that are multiple times the length of the panel. In particular, in order to fold or cross-fold the sheet, the folding rollers are provided with retaining means, such as suction holes or mechanical pincers, which are actuated in synchronism to alternately start and complete each folding between two subsequent panels.

For example, as described in EP1457444B1, a folding or cross-folding unit generally comprises a first folding or cross-folding roller which holds the paper web or sheet at a determined angular distance by a determined suction system (comprising a determined number of longitudinal rows of suction holes), and then "transfers" the sheet to a second folding or cross-folding roller which is also provided with vacuum distribution means symmetrical to those of the first suction roller and which holds another predetermined angular distance. This controlled "transport" of the paper sheet or web from one folding roller to the other allows the desired folding or cross-folding configuration of the stack of cross-folded or folded sheets to be obtained. The folding or cross-folding unit also typically provides first and second pluralities of "separating" fingers that move in phase relative to the respective folding rollers to separate the sheet from the respective outer surfaces. A separation member is also provided to separate the finished stack of cross-folded sheets from a subsequent stack to be formed. The separating fingers and separator members typically both move within corresponding grooves formed peripherally in the folding roller.

However, the folding unit described in EP1457444B1 and other similar folding rollers have some drawbacks.

In particular, the advance of the treated paper web or sheet along the machine fitted with suction rolls and similar suction rolls described in EP1457444 cannot exceed a predetermined advance speed threshold, typically about 150/200 m/min, which is imposed by the structural and functional limitations of the determined components of the machine.

The aforementioned value of the advance speed of the paper along the machine is also used, together with the path to be followed, to design the oscillating movement of the separating fingers, in particular the separating fingers, and the suction rollers, in particular to position the sealing member at a predetermined angular position. In contrast, if the aforementioned speed values for designing the suction roll are not taken into account, different kinds of defects may occur during the operation of the machine.

In particular, if the aforementioned threshold value is exceeded, the treated web or sheet also remains adhered to the surface of the suction roll, i.e. to a portion of the surface downstream of the second sealing member, after the second angular position, due to the inertia of the paper. This results in an inaccurate advance of the paper web or sheet through the different parts of the machine and further inevitably compromises the quality of the final product, in particular the formation of unwanted folds, and also may cause a jam of the paper, which makes it necessary to stop the machine to remove the jammed paper, thus losing time and productivity.

Therefore, in order to avoid the aforementioned drawbacks, it is necessary to work at low speed, so reducing the production of the machine.

Similar drawbacks also occur in prior art machines in case the paper web or sheet to be treated has a paper weight different from the predefined paper weight and folding or cross folding rollers are designed based thereon. In fact, since a sheet with a larger weight has a larger inertia than a sheet with a smaller sheet weight, if the treated sheet web or sheet has a sheet weight greater than the predefined sheet weight, the sheet web or sheet will remain adhered to the folding or cross folding roller beyond the predetermined release point, leading to the aforementioned drawbacks. Typically, due to the large inertia, paper webs or sheets with large sheet weights also cover a longer path after the end of the suction of the roll, resulting in the aforementioned functional problems and the quality loss of the final product. Thus, in addition to having low productivity, the prior art machines equipped with folding or cross-folding rollers are dead-ended, in that paper webs or sheets having different paper weights cannot be processed.

Examples of folding or cross-folding rollers having the aforementioned disadvantages are described in WO2010/140046, WO2019/149905 and WO 2018/019679.

Disclosure of Invention

It is therefore an object of the present invention to provide a folding or cross-folding unit which is able to overcome the aforementioned drawbacks of the folding or cross-folding rollers of the prior art, in particular of the type provided with suction holes.

In particular, it is an object of the present invention to provide a folding or cross-folding unit which is able to avoid the creation of wrinkles or "creases" on the treated sheet, thus ensuring that a final product of excellent quality is obtained, even if the speed of advance of the paper web or sheet along the machine is high, in particular above 300 m/min.

It is a further object of the present invention to provide a method for folding or cross-folding a paper web or sheet in a paper machine, which method has the aforementioned advantages over prior art methods.

These and other objects are achieved by a folding or cross-folding unit of a paper web or sheet, comprising:

-a first folding or cross-folding roller or a second folding or cross-folding roller of the paper web or sheet configured to fold or cross-fold the paper web or sheet at a folding or cross-folding region (35) arranged between the first folding or cross-folding roller and the second folding or cross-folding roller according to a predetermined folding or cross-folding configuration;

-a first plurality of separating fingers and a second plurality of separating fingers configured to separate the paper web or sheet from the outer side surface of the respective folding or cross-folding roller;

-a first and a second actuation group configured to cause a back-and-forth oscillating movement of the first and second plurality of separating fingers towards/away from the folding or cross-folding zone, respectively, so as to separate the respective paper web or sheet from the first and second folding or cross-folding rollers, respectively;

it is mainly characterized in that the first and second actuation groups are further configured to retard or advance the oscillating movement of the first and second plurality of separating fingers with respect to a predetermined reference oscillating movement, so as to retard or advance the moments (tr) at which the first and second plurality of separating fingers are arranged such that the paper web or sheet is separated from the first and second folding or cross-folding rollers, respectively.

Further technical features of the present invention are defined in the dependent claims.

According to another aspect of the invention, a method for folding or cross-folding a paper web or sheet in a paper machine comprises the steps of:

-feeding at least one paper web or sheet in a predetermined advancing direction;

-folding or cross-folding the paper web or sheet at a predetermined folding or cross-folding area of the paper machine, the folding or cross-folding step being performed by a first folding or cross-folding roller and a second folding or cross-folding roller, the folding or cross-folding area being defined between the first folding or cross-folding roller and the second folding or cross-folding roller;

-separating the paper web or sheet from the outer side surface of the respective folding or interfolding roller by a first plurality of separating fingers and a second plurality of separating fingers, the separating step being obtained to cause a back and forth oscillating movement of the first plurality of separating fingers and the second plurality of separating fingers towards/away from the folding or interfolding area;

it is mainly characterized in that an adjustment step is also provided for adjusting the phase between the first and second plurality of separating fingers and the first and second folding or cross-folding rollers, respectively, said adjustment step being arranged to retard or advance the oscillating movement of the first and second plurality of separating fingers.

In particular, the adjusting step is to retard or advance the oscillating movement of the first plurality of separating fingers and the second plurality of separating fingers relative to a predetermined reference oscillating movement. More specifically, the aforementioned reference oscillating movement is arranged to cause the paper web or sheet to separate from the respective folding roller at a predetermined achievement reference instant tr.

Drawings

The invention will now be illustrated by the following description of an exemplary, but non-limiting, embodiment of the invention, with reference to the accompanying drawings, in which:

figure 1 diagrammatically shows a side elevation of a first embodiment of a folding or cross-folding unit according to the invention;

figures 2 and 3 diagrammatically show side elevation views of possible alternative embodiments of the folding or cross-folding unit of figure 1;

figure 4 diagrammatically shows a side elevation view of a first embodiment of a folding or cross-folding roller according to the invention;

figures 5 and 6 diagrammatically show cross-sectional views of a first embodiment of a folding or cross-folding roller according to the invention, at the moment of catching and at the moment of release of the paper web or sheet, respectively;

figures 7 and 8 diagrammatically show a side elevation and a cross-sectional view, respectively, of a first functional mode of the folding or cross-folding roller according to the invention;

Fig. 9 shows an enlarged view of a portion of fig. 8 to schematically illustrate some aspects of the first functional mode of the folding or cross-folding roller according to the invention;

fig. 10 and 11 diagrammatically show a side elevation and a cross-sectional view, respectively, of a second functional mode of the folding or cross-folding roller according to the invention;

fig. 12 shows an enlarged view of a portion of fig. 11 to schematically illustrate some aspects of the second functional mode of the folding or cross-folding roller according to the invention;

figure 13 diagrammatically shows a longitudinal section view of an alternative embodiment of a folding or cross-folding roller for figure 4 according to the invention;

figure 14 diagrammatically shows a side elevation view of an alternative embodiment of the folding or cross-folding roller of figure 13;

figures 15 and 16 show, in side elevation and in cross-section, respectively, a first operating mode of the folding or cross-folding roller of figures 13 and 14;

figures 17 and 18 show, in side elevation and in cross-section, respectively, a second functional mode of the folding or cross-folding roller of figures 13 and 14;

figures 19 and 21 show cross-sectional views of other possible alternative embodiments of the roller of figures 13 and 14 according to the invention;

fig. 20 shows an enlarged view of a portion of fig. 19 to highlight some technical features;

Figure 22 shows a side elevation view of another alternative embodiment of a folding or cross-folding roller for figure 4 according to the invention;

figure 23 diagrammatically shows a side elevation view of a possible embodiment of a sheet processing machine using a folding or cross-folding unit according to the invention.

Detailed Description

As schematically shown in fig. 1, a folding or cross-folding unit 150 according to the present invention comprises a first folding or cross-folding roller 1a and a second folding or cross-folding roller 1b. Specifically, the first folding or cross-folding roller 1a and the second folding or cross-folding roller 1b are configured to fold or cross-fold the paper web or sheet at a folding or cross-folding region 35 defined between the two folding or cross-folding rollers according to a predetermined folding or cross-folding configuration.

In addition to the first folding or cross-folding roller 1a and the second folding or cross-folding roller 1b, the folding or cross-folding unit 150 further comprises a first plurality of separating fingers 40a and a second plurality of separating fingers 40b, which are arranged to operate in phase with the first folding or cross-folding roller 1a and the second folding or cross-folding roller 1b, respectively, to separate the respective paper web or sheet 5 from the surfaces 11 of the respective tubular bodies 10a and 10b of the first folding or cross-folding roller 1a and the second folding or cross-folding roller 1b, thereby forming a stack 250 of folded or cross-folded sheets.

In particular, a first actuation group 80a and a second actuation group 80b may be provided that are respectively configured to cause a back and forth oscillating movement of the first plurality of separating fingers 40a and the second plurality of separating fingers 40b toward/away from the aforementioned fold or cross-fold region 35. Specifically, the first actuating group 80a and the second actuating group 80b are further configured to retard or advance the oscillating movement of the first plurality of separating fingers 40a and the second plurality of separating fingers 40b relative to a predetermined reference oscillating movement, such that the first plurality of separating fingers 40a and the second plurality of separating fingers 40b are arranged to retard or advance the moment tr at which the paper web or sheet 5 is separated from the respective folding or cross-folding rollers 1a and 1b, specifically, relative to a predetermined reference achievement moment tr.

In particular, in the first embodiment schematically shown in fig. 1, the first actuating group 80a and the second actuating group 80b may comprise a first actuating means 91a and a second actuating means 91b, respectively. More specifically, the first and second actuating devices 91a and 91b are provided with the first and second motor groups 85a and 85b, respectively. The two motor sets are operatively connected to a first motor shaft 86a and a second motor shaft 86b, respectively. More precisely, the first motor group 85a and the second motor group 85b are arranged to cause rotation of the first motor shaft 86a and the second motor shaft 86b about the respective rotation axes 185a and 185 b.

In particular, the first and second actuation groups 80a, 80b may include first and second oscillator devices 90a, 90b, respectively, configured to convert rotational motion or power output on an inlet axis to oscillating motion or power output on an outlet axis.

The mechanical type of oscillator device may be a device of a type known to a person skilled in the art, which will not be described in detail here.

Preferably, the first and second oscillator means 90a, 90b (e.g. first and second mechanical oscillators) may comprise first and second mechanical cams, respectively, preferably first and second desmodromic cams, which are not shown in the figures for simplicity.

Specifically, the first motor shaft 86a and the second motor shaft 86b may be connected to the first oscillator device 90a and the second oscillator device 90b at inlets. Advantageously, they comprise outlet shafts 83a and 83b, respectively, connected to a first transmission group 81a and a second transmission group 81b, which are arranged to transmit oscillating movements to the first plurality of separating fingers 40a and to the second plurality of separating fingers 40b. In particular, the aforementioned output shafts 83a and 83b are connected to the first transmission group 81a and the second transmission group 81b by respective mechanical cams 84a and 84b, which are advantageously desmodromic cams, not shown in the figures for the sake of clarity.

In this way, it is possible to obtain the phase between the first plurality of separating fingers 40a and the second plurality of separating fingers 40b and the other parts of the machine 100, in particular with respect to the first folding or cross-folding roller 1a and the second folding or cross-folding roller 1b, so that the first motor group 85a and the second motor group 85b rotate at a determined speed.

In particular, the solution provided by the present invention is able to guarantee a higher accuracy with respect to the prior art solutions (in particular WO 2010/140046) providing a crank and link mechanism to convert a rotary motion into an oscillating motion. In particular, the solution provided by the present invention allows to very accurately adjust the phase between the separating fingers 40a and 40b and the respective rollers 1a and 1b, in particular to advance or retard the oscillating movement of the first plurality of separating fingers 40a and of the second plurality of separating fingers 40b, respectively, with respect to a predetermined reference oscillating movement.

Advantageously, the phase of the separating fingers 40a and 40b can be adjusted, i.e. the oscillating movement is retarded or advanced with respect to the other mechanical mechanisms of the machine 100, slowing or accelerating the first motor group 85a and the second motor group 85b within the necessary time period. In other words, starting from a predetermined reference condition in which the first motor group 85a and the second motor group 85b rotate at the reference speed vm, the first motor group 85a and the second motor group 85b slow down or accelerate for a time interval Δt, then their speeds return to the reference speed vm. In particular, the rotational speed of the first and second rotational shafts 86a, 86b may be increased or decreased with respect to the set reference speed vm for a determined period of time, thereby advancing or retarding the oscillating movement of the first and second plurality of separating fingers 40a, 40b, respectively, and in particular with respect to the reference oscillating movement. Specifically, the oscillating movement of the separating fingers 40a and 40b can be accelerated or decelerated in the manner described above.

Also in the alternative embodiment schematically shown in fig. 2, the first actuating group 80a and the second actuating group 80b comprise a first motor group 85a and a second motor group 85b, respectively, which are arranged such that the first motor shaft 86a and the second motor shaft 86b rotate about respective axes of rotation 185a and 185 b. Furthermore, also in this case, a first and a second oscillator device 90a, 90b of a preferably mechanical type are provided, which are arranged to convert the rotational movement of the motor shafts 86a and 86b into an oscillating movement, and a first and a second transmission set 81a, 81b are provided, which are arranged to transmit the oscillating movement at the outlets of the first and second oscillator devices 90a, 90b to the first and second plurality of separating fingers 40a, 40b, respectively.

However, in this case, unlike what has been described above with reference to fig. 1, the first and second oscillator means 90a and 90b are advantageously associated with first and second adjustment means 94a and 94b, respectively, which are configured to adjust the phase of the first and second pluralities of separating fingers 40a and 40b with respect to the respective folding or cross-folding rollers 1a and 1 b. In particular, the first and second adjusting means 94a and 94b are arranged to advance or retard the moment tr at which the first and second plurality of separating fingers 40a and 40b are arranged to strike the paper web or sheet 5 to separate it from the respective folding or cross-folding rollers 1a and 1 b.

Advantageously, the first and second adjustment means 94a, 94b may comprise a first and a second phase shifter gearbox 95a, 95b, respectively, of a type known to a person skilled in the art. More specifically, in this case, the first and second phase shifter gearboxes 95a and 95b may be operatively connected to the first and second motor groups 85a and 85b, respectively, for example, by first drive belts 87a and 87b, and to the first and second actuation devices 91a and 91b, respectively, by second drive belts 88a and 88b, respectively. More precisely, the first and second actuation means 91a, 91b are arranged to transmit the generated rotational movement of the dal first and dal second motor groups 85a, 85b to the aforementioned first and second oscillator means 90a, 90b, respectively, which convert the rotational movement into the aforementioned oscillating movement, which is transmitted to the first and second plurality of separating fingers 40a, 40b. The first and second phaser gearboxes 95a and 95b are provided with first and second electric motors 96a and 96b, respectively. These are arranged to adjust the rotational speeds of the first and second actuators 91a, 91b, thereby adjusting the rotational speeds and rotational directions of the first and second epicycloidal gears (not shown for simplicity) housed within the first and second phaser gearboxes 95a, 95b, respectively.

In one embodiment of the present invention (not shown in the figures for clarity), in any of the above embodiments, the first and second oscillator devices 90a and 90b may be connected to the respective first ends 81'a and 81' b of the aforementioned first and second drive sets 81a and 81b, which are operatively connected to the first and second pluralities of separating fingers 40a and 40b, respectively, at second ends 81 "a and 81" b opposite the first ends. Thus, the first and second oscillator devices 90a, 90b are laterally positioned relative to the first and second pluralities of separating fingers 40a, 40b, respectively.

According to one possible mode of operation of the invention, the first electric motor 96a and the second electric motor 96b may also normally be stationary, so that the phase of the separating fingers 40a and 40b with respect to the rest of the machine 100, in particular with respect to the folding rollers 1a, 1b, is unchanged. In the event that it is desired to change the phase of the first and second pluralities of separator fingers 40a, 40b, the first and second electric motors 96a, 96b are used to actuate the first and second epicyclic gears, respectively, to temporarily accelerate or decelerate the second drive belts 88a, 88 b. In this way, a delay or advance can be introduced in the oscillating movement of the first plurality of separating fingers 40a and the second plurality of separating fingers 40b, thus delaying or advancing the moment at which the paper web or sheet is separated from the respective folding or cross-folding roller 1a, 1b, i.e. the moment tr at which the first plurality of separating fingers 40a and the second plurality of separating fingers 40b are arranged such that the paper web or sheet 5 is separated from the respective folding or cross-folding roller 1a and 1b, in particular with respect to the reference separation moment tr.

In particular, the first folding or cross-folding roller 1a and the second folding or cross-folding roller 1b of the folding or cross-folding unit 150 described above with reference to fig. 1 and 2 may be provided with means for holding the processed paper web or sheet 5 of a mechanical type (for example provided with mechanical pincers of a known type) or of a pneumatic type. In the latter case the holding member may provide a bell-shaped vacuum dispensing device of a known type or comprise a sealing section part of the type described in e.g. EP1457444B 1.

As schematically shown in fig. 3, the folding or cross-folding unit 150 may provide a first folding or cross-folding roller 1a and a second folding or cross-folding roller 1b as described below in addition to the first actuating group 80a and the second actuating group 80b of the aforementioned separating fingers 40a and 40 b.

Specifically, each folding or cross-folding roller 1a or 1b of a paper web or sheet 5 fed in an advancing direction 15 in a paper machine or similar product comprises a tubular body 10 configured to rotate about a longitudinal rotation axis 101 in a predetermined rotation direction 110 (e.g., clockwise). More precisely, the tubular body 10 of the roller 1a or 1b is provided with an outer surface 11 and an inner surface 12, which communicate with each other through a plurality of suction holes 3.

In particular, the suction apertures 3 of the folding or cross-folding rollers 1a or 1b may be organized according to a predetermined number of suction groups (for example 2, or 3, or 4 suction groups 30) positioned at predetermined angular positions (for example respectively at 180 °, 120 ° or 90 °) of the folding or cross-folding rollers 1a or 1 b. In general, the angular position of the suction group 30 depends on the number of sheets 5 which can be placed adjacent to each other on the outer side surface 11 of the folding or cross-folding roller 1. The arc of a circle arranged between the suction group 30 and the next suction group is equal to the length of the processed sheet 5, and therefore, depending on the diameter of the folding or cross-folding roller 1a or 1b, there may be two, three, four or even more suction groups 30. For example, if there are five suction groups 30 on the folding or cross-folding roller 1a or 1b, the angular distance between the suction groups 30 will be 72 °. In the following example, the folding or cross-folding roller 1 provides 3 suction groups 30, each comprising two longitudinal rows of suction holes 3 close to each other. The folding or cross-folding roller 1 also provides a suction chamber 20 defined inside the aforesaid tubular body 10 and pneumatically connected to means for generating a predetermined vacuum, for example a vacuum pump, which means are not shown in the figures for the sake of simplicity, but are of a type known to the person skilled in the art. A vacuum distribution device 50 is also provided, which is configured to pneumatically communicate the suction chamber 20 selectively with at least one row of suction holes 3 of the plurality of suction holes 3 at a predetermined angular position of the tubular body 10. In this way, as is known, the treated paper sheet or web is sucked and adheres only at the determined portion of the outer side surface 11 of the folding or cross-folding roller 1, which is arranged between the catch point P1 and the release point P2 with determined angular positions, in particular with respect to a predetermined reference frame (Xo, yo, zo). According to the present invention, a displacement device 70 is provided, which is configured to move the aforementioned vacuum distribution device 50 such that the angular position of at least the release point P2 is changed, in particular with respect to a predetermined angular position P2, the latter being occupied with respect to the aforementioned predetermined reference frame (Xo, yo, zo).

The displacement device 70 may advantageously be operated by the main control unit 300, for example comprising a PLC or an industrial PC or similar device (see e.g. fig. 23). The main control unit 300 may interact with an operator through a panel interface, for example of HMI (human machine interface) type, through which the operator may give commands and/or adjust the machine 100. For example, the electronic control unit 300 may detect the need to adjust the capture point P1 and/or the release point P2 and communicate the necessary settings to the operator through the HMI. The operator may then perform adjustments via the HMI in accordance with the communication of the master control unit 300.

In this way, it is possible to advance or retard the moment ta at which the paper web or sheet adheres to the aforementioned outer surface 11 of the folding or cross-folding roller 1a or 1b and/or the moment tr at which the paper web or sheet 5 leaves the aforementioned outer surface 11 of the folding or cross-folding roller 1a or 1 b.

In particular, the aforesaid displacement device 70 may be configured to move the aforesaid vacuum distribution device 50 according to at least one predetermined operating parameter of the machine 100 in which the folding or cross-folding roller 1a or 1b is mounted. For example, the aforementioned predetermined operating parameter may be the advance speed of the paper web or sheet along the machine 100.

In this case, in particular, if the advancing speed v of the paper web or sheet is greater than a predetermined reference value v, or if the operating speed of the machine 150 increases, the displacement device 70 is arranged to move the vacuum dispensing device 50 so as to advance the moment tr at which the paper web or sheet is separated from the folding or cross-folding roller 1a or 1 b. Specifically, in this case, the displacement device 70 may be configured such that the aforementioned vacuum distribution device 50 rotates in a direction opposite to the aforementioned rotation direction 110 of the folding roller or about the rotation axis 101 (fig. 7 to 9).

Conversely, if the machine 100 is expected to operate at a paper advance speed lower than the aforementioned reference value v, or simply if the operating speed of the machine 100 is reduced, the displacement device 70 is arranged to move the aforementioned vacuum dispensing device 50 so as to delay the release of the paper web or sheet with respect to the reference condition. More precisely, in this case, the displacement device 70 will be arranged to rotate the aforesaid vacuum distribution device 50 in the same direction as the aforesaid rotation direction 110 of the folding roller or about the rotation axis 101 (fig. 10 to 12).

In a preferred arrangement of the invention, the vacuum dispensing device 50 can be rotated in accordance with at least one operating parameter, such as the speed of advance of the paper. In this case, the main control unit 300 may operate the displacement device 70 to cause rotational displacement of the vacuum dispensing device 50. The main control unit 300 may operate the shifting means 70 according to a predetermined function or an algorithm based on real-time calculation, such as a self-learning algorithm or an artificial intelligence algorithm in general.

In an alternative embodiment of the invention, the capture position P1 and/or the separation position P2 may be controlled such that the angular position of the vacuum dispensing device 50 alternates between at least two predetermined angular positions. For example, the release position of point P2' of FIG. 12 may correspond to a slow advance speed of the paper (e.g., between 50m/min and 100 m/min), while the release position P2 "of FIG. 12 may correspond to a high advance speed (e.g., greater than 250 m/min). In this case, a speed threshold value may be set, beyond which the displacement device 70 is operable to move the vacuum dispensing device 50 from position P2' to position P2 ", so as to advance or retard the separation of the paper web or sheet 5. The actuation command of the displacement device 70 may be given directly by the main control unit 300 or by the operator via an HMI interface.

Another operating parameter of the machine 100 may be the sheet thickness s or the sheet weight of the processed web or sheet, according to which the displacement device 70 may be arranged to move the vacuum distribution device 50. Specifically, if the sheet thickness is greater than a predetermined reference thickness s, the displacement device 70 is arranged to move the vacuum distribution device 50 such that the instant tr at which the sheet web or sheet is released from the roll 1 is advanced with respect to the release reference instant tr.

In particular, in this case, the displacement means 70 may be arranged to rotate the vacuum dispensing device 50 in a direction opposite to the direction of rotation 110 of the tubular body 10 about the longitudinal axis 101. Conversely, in case the sheet thickness is smaller than a predetermined reference thickness s, the displacement device 70 is arranged to move the vacuum dispensing device 50 such that the moment of release of the sheet web or sheet from the roll 1 is delayed. In particular, in this case, the displacement means 70 may be arranged to rotate the vacuum dispensing device 50 in a rotation direction that coincides with the rotation direction of the tubular body 10 about the longitudinal axis 101.

In this case, the machine 100 can be adjusted according to the product, i.e. according to the characteristics of the sheets that have to be processed. The displacement device 70 can be operated in different ways depending on the type of paper or product to be treated, so that great advantages are obtained in terms of the setting of the machine 100 during product replacement. Each product or sheet type may correspond to a particular movement of the displacement device 70, or to a particular reference value of the sheet velocity v, so that the position of the catch point P1 and/or the release point P2 is optimized for each particular product or sheet type.

In a preferred embodiment of the invention, the aforesaid displacement device 70 may be configured to move (in particular rotate) the vacuum dispensing device 50, in particular to retard or advance the moment tr at which the paper web or sheet is released from the surface 11 during the working conditions of the machine 100 (which means during the rotation of the tubular body 10 about the aforesaid longitudinal rotation axis 101). In this way, in particular, the vacuum dispensing device 50 can be moved so as to gradually follow an increase or decrease in the advancing speed of the paper web or sheet.

Specifically, in the first embodiment, the aforementioned vacuum distribution device 50 may comprise a fixed tubular body 25 coaxially mounted within the aforementioned tubular body 10. More specifically, the aforementioned fixed tubular body 25 is in pneumatic communication with means for generating a predetermined vacuum and is provided with at least one hole 26. More precisely, the vacuum dispensing device 50 may further comprise a first sealing member 27a and a second sealing member 27b, which are integral with the fixed tubular body 20 on opposite sides with respect to the or each aperture 26 and are positioned longitudinally with respect to the tubular body 10. In particular, the displacement device 70 may be configured to cause rotation of the fixed tubular body 25 about the aforementioned longitudinal rotation axis 101.

More specifically, as schematically illustrated in fig. 13, the aforementioned displacement means 70 may be arranged to engage the fixed tubular body 25 at least at an actuation portion 75, which is advantageously a portion axially protruding from one end of the tubular body 10.

In particular, if the aim is to advance the release moment tr with respect to the reference condition tr (dashed line in fig. 9), for example because the machine 100 is operating at a sheet advance speed higher than the reference speed, in particular for the purpose of having a higher productivity, or for the purpose of handling a type of sheet having a sheet weight s lighter than the reference sheet weight s, the displacement device 70 may be arranged to rotate the fixed tubular body 25 in a direction opposite to the predetermined rotation direction 110 of the tubular body 10. In this way, in practice, as schematically illustrated in fig. 9, the paper sheet or web moves from the release point P2 of the surface 11 of the tubular body 10 to upstream of the reference release point P2.

Conversely, if the aim is to operate the machine at a speed slower than the reference speed v, or to process a type of sheet having a sheet weight greater than the reference sheet weight s, the displacement device 70 may be arranged to rotate the fixed tubular body 25 about the longitudinal rotation axis 101 in a rotation direction coinciding with the predetermined rotation direction 110 of the tubular body 10, to delay the release instant tr of the sheet web or sheet 5 with respect to the reference realisation time tr (see fig. 7 to 9). In this way, in practice, as schematically illustrated in fig. 9, the paper sheet or web moves downstream from the release point P2 of the surface 11 of the tubular body 10 to a reference release point P2.

In an alternative embodiment of the invention, the catch point P1 and/or the release point P2 vary with the speed of the machine 100, conveniently advancing or retarding at least one of the two moments between ta and tr at which the sheet is held and released, respectively, at the outer surface 11 of the folding or cross-folding roller 1a or 1 b. In this case, in order to advance or retard the two moments ta or tr, advantageously, no reference is made to a predetermined speed v, but the electronic control unit 300 may be configured to calculate the position of the capture point P1 and/or of the release point P2 as a function of the speed of the machine 100, and to operate the displacement device 70 directly, or indirectly by an operator giving commands through the HMI device.

As schematically shown in fig. 13-18, and in particular in fig. 14, the displacement device 70 may comprise an actuation device 73. In particular, the actuation means 73 may be an actuator, for example a pneumatic actuator, or a mechanical actuator, or an electromechanical actuator.

Preferably, the actuation means 73 may be a motor, in particular an electric motor 73, provided with a motor shaft (not shown in the figures) arranged to rotate about a rotation axis 173. The motor shaft of the motor 73 may be arranged to engage with the worm 71 sliding in the sliding direction 171. More precisely, the worm 71 is pivotally connected at an engagement portion 76 to an actuation portion 75 integral with said fixed tubular body 25.

Accordingly, to cause rotation of the stationary tubular body 25 in a first direction, in particular in a direction opposite to the direction of rotation 110 of the tubular body 10, the motor 73 is operated such that the motor shaft rotates about the rotation axis 173 on the first rotation axis 172 (see fig. 15). In this way, as described above, the release point P2 (also the capture point P1 in the case of fig. 13) is positioned at an angular position upstream of the angular position of the reference capture point P2. Therefore, the release time tr is advanced with respect to the reference time tr (see also fig. 9).

In contrast, to cause the fixed tubular body 25 to rotate in the second rotational direction, in particular in a direction coinciding with the rotational direction 110 of the tubular body 10, the motor 73 is operated such that the motor shaft rotates about the rotational axis 173 in the second rotational direction 172' (see fig. 17). In this way, as described above, the release point P2 (also the capture point P1 in the case of fig. 15) is positioned at an angular position downstream of the angular position of the reference capture point P2. Thus, the release time tr is delayed relative to the reference time tr (see also fig. 12).

In an alternative embodiment of the present invention, instead of the motor 73, a linear electric actuator, i.e. an electric motor whose axis is slidable without rotation, may be used. In this way, the axis of the electric motor can be directly connected at the engagement portion 76 to the actuation portion 75 integral with the fixed tubular body 25.

In particular, in the above-described embodiments and in particular shown in fig. 4 to 18, the suction chamber 20 is pneumatically connected to the suction aperture 3 by a vacuum distribution device 50 equipped with a first sealing member 27a and a second sealing member 27b, which are oriented radially and positioned at opposite sides for the or each aperture 26. More specifically, there is no other element capable of closing the suction hole 3 between the first sealing member 27a and the second sealing member 27 b. Thus, the suction chamber is delimited by the first sealing member 27a and the second sealing member 27 b.

In an alternative embodiment, schematically illustrated in fig. 19 and 20, the aforesaid vacuum dispensing device 50 comprises a fixed tubular body 25 coaxially mounted inside the tubular body 10 and in pneumatic communication with means for generating a predetermined vacuum. In more detail, the fixed tubular body 25 is provided with at least one hole 26 having a predetermined angular amplitude, in particular corresponding to the length of the sheet or panel 5 to be treated, or to the portion of the path covered by the web or sheet 5 on the roller.

In this case, the vacuum dispensing device 50 comprises a plurality of sealing members 27, which are integral with the tubular body 10 and are positioned longitudinally. More specifically, each sealing member 27 is associated with at least one row of suction holes 3 arranged to pneumatically connect the outer surface 11 to means for generating a predetermined vacuum through the holes 26. Furthermore, between the sealing member 27 associated with two different suction groups 30 and the subsequent sealing member 27, an annular sealing member 28 may be provided. In this case, the displacement means 70 are advantageously configured to cause rotation of the fixed tubular body 25 about the longitudinal rotation axis 101. More precisely, as shown in detail in fig. 20, for example, in order to advance the release instant tr of the paper sheet or web 5 with respect to the reference condition tr, the fixed tubular body 25 can be rotated in a direction opposite to the rotation direction 110 of the tubular body 10. In this way, the release point P2 will be positioned upstream of the angular position of the reference release point P2 in the direction of rotation 110, since the suction holes 3 will be advanced away from the web or sheet 5 with respect to the reference situation (schematically shown in the figure with a dashed line).

In another alternative embodiment, schematically shown in fig. 21, a first sealing member 27a and a second sealing member 27b are provided extending longitudinally to the tubular body 10 between the inner surface 12 and the stationary tubular body 25, similar to the embodiments described above with reference to fig. 8, 11, 16 and 18. In this case, however, at least one sealing member (for example, the sealing member 27 b) is mounted on a support 21 which is movable with respect to the fixed tubular body 25, for example, inside a guide 22 formed along the outer periphery at the fixed tubular body 25. Thus, in this case, the displacement device 70 may be configured to move the movable support 21, in particular to rotate about the longitudinal axis 101.

In this way, only the release position P2 may be changed, while the capture position P1 may be a fixed position and coincide with the reference angular position P1.

Alternatively, a first displacement device 70a and a second displacement device 70b may be provided, one of which is configured to move the movable support 21 and the other is configured to move the tubular body 25. Thus, in this way, the capture point P1 and the release point P2 (fig. 22) can be changed independently of each other.

In an alternative embodiment of the invention, not shown, the first sealing member 27a and the second sealing member 27b may be mounted on two supports that are able to move independently with respect to each other to adjust the catch point P1 and/or the release point P2 so as to keep the fixed tubular body 25 fixed. In a further alternative embodiment of the invention, the displacement means 70 may comprise a linear actuator, in particular of the mechanical, or electrical, or electromechanical, or pneumatic type, arranged to rotate the vacuum dispensing device 50 against the movable abutment member. In this way, by varying the position of the movable abutment member, the angular position of the vacuum dispensing device 50 can be adjusted.

In another embodiment, schematically shown in fig. 23, upstream of the folding or cross-folding unit 150 according to the invention, a first cutting roller 1c and a second cutting roller 1d may be provided, configured to cut the respective paper web in a predetermined first and second plurality of sheets of predetermined length, respectively. According to the invention, the first 1c and the second 1d cutting roll may also be provided with respective displacement means 70c and 70d, which are configured to move the respective vacuum dispensing device 50 according to one of the embodiments described above with reference to fig. 4 to 18 of the folding or cross-folding roll, such that the release point P2 of the respective processed paper web or sheet, and in some cases also the catch point P1 of the respective processed paper web or sheet, is retarded or advanced according to different purposes.

The phase of both the first plurality of separating fingers 40a and the second plurality of separating fingers 40b and the phase of the position of the catch point P1 and/or the release point P2 relative to the reference value may be adjusted and may be calculated relative to the starting conditions and/or relative to the operating conditions of the machine 100. In the case where the aforementioned reference values are those of the starting conditions of the machine or zero points, the reference points may preferably be calculated from the weight of the paper or from the dimensions of the sheet 5. In addition to changing the sheet weight or changing the sheet of the sheet 5, a function of the instant moment used to calculate the catch point P1 and/or the release point P2 and/or the release moment tr of the separating fingers 40a and 40b may also be changed.

In case the reference value relates to the state of the machine, i.e. to the moment when the machine is in an operating state and therefore operating at an instantaneous operating speed or at a predetermined speed, the release moment tr of the catch point P1 and release point P2 and/or of the separating fingers 40a and 40b is calculated by the main control unit 300 by means of a determined algorithm. The calculation may be of the threshold speed type, i.e. the capture point P1 and/or the release point P2 may be changed when a predetermined operating speed is exceeded upwards or downwards. In an alternative embodiment of the invention, the capture point P1 and/or the release point P2 may be changed starting from a start value or zero value, so that they are calculated from the set speed or the instantaneous speed. The function of the instantaneous speed and position of the association points P1 and P2 may be of any type, for example linear, non-linear or other. Further, these functions may be selected based on sheet weight, or sheet size, or product size, that adapts machine 100 to the sheet type. Similar to the above, the delay or advance of the moments ta and tr of the separation of the fingers 40a, 40b may be varied, automatically adapting the machine 100 to the operating conditions and/or to the variations of the product type.

Although not shown in fig. 1, 2, and 3 for clarity, it should be noted that a separation member of a type known to those skilled in the art may be provided and configured to perform separation of the finished stack of folded or cross-folded sheets 250 from the subsequently formed stack 250.

The foregoing description of exemplary embodiments of the invention will so fully reveal the invention according to the conceptual point of view that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiments without further research and without deviation from the present invention, and it is therefore understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and materials used to achieve the different functions described herein may have different properties without thereby departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims (26)

1. A folding or cross-folding unit of a paper web or sheet, the folding or cross-folding unit comprising:

-a first folding or cross-folding roller and a second folding or cross-folding roller (1 a,1 b) of the paper web or sheet, which are configured to fold or cross-fold the paper web or sheet at a folding or cross-folding area (35) arranged between the first folding or cross-folding roller and the second folding or cross-folding roller (1 a,1 b) according to a predetermined folding or cross-folding configuration;

-a first and a second plurality of separating fingers (40 a,40 b) configured to separate the paper web or sheet from the outer side surface (11) of the respective folding or cross-folding roller (1 a,1 b);

-a first and a second actuation group (80 a,80 b) configured to cause an oscillating movement back and forth of the first and the second plurality of separating fingers (40 a,40 b) towards/away from the folding or cross-folding zone (35), respectively, so as to separate the respective paper web or sheet from the first and the second folding or cross-folding rollers (1 a,1 b), respectively, the folding or cross-folding unit being characterized in that the first and the second actuation groups (80 a,80 b) are further configured to delay or advance the oscillating movement of the first and the second plurality of separating fingers (40 a,40 b), respectively, with respect to a predetermined reference oscillating movement, so as to delay or advance the oscillating movement of the first and the second plurality of separating fingers (40 a,40 b), respectively, so that the first and the second plurality of separating fingers (40 a,40 b) are arranged to cause the separation of the paper web or sheet from the first and the second folding roller (1 a,1 b), respectively.

2. The paper web or sheet folding or cross-folding unit according to claim 1, wherein the first folding or cross-folding roller and the second folding or cross-folding roller (1 a,1 b) each comprise:

-a tubular body (10) configured to rotate in a predetermined rotation direction (110) about a longitudinal rotation axis (101), the tubular body (10) being provided with an outer side surface (11) and an inner side surface (12) which are in pneumatic communication with each other through a plurality of suction holes (3) organized according to a plurality of longitudinal rows (30);

-a suction chamber (20) defined within the folding or cross-folding roller (1) and pneumatically connected to vacuum generating means configured to generate a predetermined vacuum;

-a vacuum distribution device (50) configured to pneumatically connect the suction chamber (20) selectively with at least one row of suction holes of the plurality of suction holes (3) at a determined angular position of the tubular body (10) so that the treated paper sheet or web is sucked (100) and adheres to the outer side surface (11) of the folding or cross-folding roller (1) arranged at a corresponding portion between a catch point and a release point (P1, P2) having a determined angular position.

3. The folding or cross-folding unit of paper web or sheet according to claim 2, wherein a displacement device (70) is also provided, which is configured to move the vacuum dispensing device (50) such that the angular position of the catch point (P1) and/or the release point (P2) of the paper web or sheet is changed and thus the moment at which the paper web or sheet adheres to the outer side surface (11) or leaves the outer side surface of the first folding or cross-folding roller or the second folding or cross-folding roller (1 a,1 b) is advanced or retarded.

4. A paper web or sheet folding or cross-folding unit according to claim 3, wherein the displacement device (70) is configured to move the vacuum dispensing device (50) during the rotation of the tubular body (10) about the longitudinal rotation axis (101).

5. A paper web or sheet folding or cross-folding unit according to claim 2, wherein the vacuum dispensing device (50) comprises a stationary tubular body (25) coaxially mounted within the tubular body (10), the stationary tubular body (25) being pneumatically connected with the means for generating a predetermined vacuum and provided with at least one aperture (26), and wherein the displacement device (70) is configured to cause rotation of the stationary tubular body (25) about the longitudinal rotation axis (101).

6. A paper web or sheet folding or cross-folding unit according to claim 2, wherein the displacement means (70) comprise actuation means (73) selected from the group comprising:

-a linear actuator;

-a mechanical actuator;

-an electric actuator;

-an electromechanical actuator;

-a pneumatic actuator;

or a combination thereof.

7. A paper web or sheet folding or cross-folding unit according to claim 2, wherein the vacuum dispensing device (50) comprises a first and a second sealing member (27 a,27 b) integral with the stationary tubular body (25) at opposite sides with respect to the aperture (26), the first and second sealing members (27 a,27 b) being positioned longitudinally with respect to the tubular body (10).

8. A paper web or sheet folding or cross-folding unit according to claim 2, wherein the vacuum dispensing device (50) comprises a plurality of sealing members (27, 28) integral with the tubular body (10) and longitudinally positioned with respect thereto, each sealing member (27, 28) of the plurality being associated with at least one row of suction holes (3) arranged to pneumatically connect the outer surface (11) with the means for generating a predetermined vacuum.

9. Folding or cross-folding unit according to any one of the preceding claims, wherein the first and second actuation groups (80 a,80 b) respectively comprise:

-a first and a second motor group (85 a,85 b) configured to cause rotation of the first and second motor shafts (86 a,86 b) about respective rotation axes (185 a,185 b);

-first and second oscillator means (90 a,90 b) configured to convert a rotational movement of the first and second motor shafts (86 a,86 b) on an inlet axis into an oscillating movement on an outlet axis to transmit the oscillating movement to the first and second plurality of separating fingers (40 a,40 b).

10. A second folding or interdigitating unit, and wherein the first and second motor groups (85 a,85 b) are further configured to vary the rotational speed of the first and second rotational shafts (86 a,86 b) relative to a reference rotational speed (vm) over a determined time interval (Δt), such that the oscillating movement of the first and second plurality of separating fingers (40 a,40 b), respectively, is advanced or retarded.

11. The folding or cross-folding unit according to any one of claims 1 to 10, wherein the first and second actuation groups (80 a,80 b) respectively comprise:

-a first and a second motor group (85 a,85 b) configured to cause rotation of the first and second motor shafts (86 a,86 b) about respective rotation axes (185 a,185 b);

-first and second oscillator means (90 a,90 b) configured to convert the rotational movement of the first and second motor shafts (86 a,86 b) into an oscillating movement of the first and second plurality of separating fingers (40 a,40 b);

and wherein first and second adjusting means (94 a,94 b) are also provided, associated with the first and second oscillator means (90 a,90 b), respectively, and configured to advance or retard the moment (tr) at which the first and second plurality of separating fingers (40 a,40 b) are arranged to strike the paper web or sheet (5) to separate the paper web or sheet (5) from the first and second folding or cross-folding rollers (1 a,1 b), respectively.

12. Folding or cross-folding unit according to claim 11, wherein the first and second adjustment means (94 a,94 b) comprise a first and a second phase shifter gearbox (95 a,95 b), respectively.

13. The folding or cross-folding unit of claim 12, wherein the first and second phase shifter gearboxes (95 a,95 b) are provided with first and second epicycloidal gears, respectively, the first and second phase shifter gearboxes (95 a,95 b) being operatively connected to first and second motors (96 a,96 b), respectively, configured to operate the first and second epicycloidal gears, respectively, such that the oscillating movement of the first and second plurality of separating fingers (40 a,40 b) is accelerated or decelerated.

14. The paper web or sheet folding or cross-folding unit according to claim 4, wherein the displacement device (70) and/or the first and second actuation groups (80 a,80 b) are configured to be operated by an operator through an interface panel or HMI "man-machine interface".

15. The paper web or sheet folding or cross-folding unit according to claim 14, wherein the displacement means (70) and/or the first and second actuation groups (80 a,80 b) are operated by an electronic control unit (300) according to at least one of the following parameters:

-the instantaneous operating speeds of the first folding or cross-folding roller and of the second folding or cross-folding roller (1 a,1 b);

-the length of the paper sheet;

-sheet weight.

16. A paper web or sheet folding or cross-folding unit according to any of the preceding claims, wherein the plurality of longitudinal rows of suction holes (3) are organized according to a plurality of suction groups (30), each suction group of the plurality comprising at least 2 longitudinal rows of holes (3) close to each other.

17. A paper web or sheet folding or cross-folding unit according to any of the preceding claims, wherein the plurality of longitudinal rows of suction holes (3) are organized according to a plurality of suction groups (30), each suction group of the plurality comprising at least 3 longitudinal rows of holes (3) close to each other.

18. A paper web or sheet folding or cross-folding unit according to claim 16 or 17, wherein the distance between two subsequent suction groups (30) of the plurality of suction groups is equal to the length of the treated sheet (5).

19. The paper web or sheet folding or cross-folding unit of claim 11 wherein the first and second phase shifter gearboxes (95 a,95 b) are operatively connected to the first and second motor groups (85 a,85 b) by first and second drive belts (87 a,87 b), respectively.

20. The paper web or sheet folding or cross-folding unit according to claim 19, wherein the first and second phase shifter gearboxes (95 a,95 b) are further operatively connected to first and second actuation means (91 a,91 b) by a second drive belt (88 a,88 b), the first and second actuation means (91 a,91 b) being arranged to transmit the rotational movement caused by the first and second motor groups (85 a,85 b) to the first and second oscillator means (90 a,90 b), respectively.

21. A paper web or sheet folding or cross-folding unit according to claim 20, wherein the first and second phase shifter gearboxes (95 a,95 b) are provided with first and second electric motors (96 a,96 b), respectively, arranged to adjust the rotational speed of the first and second actuation means (91 a,91 b).

22. Folding or cross-folding unit according to claim 9, wherein the first oscillator means (90 a) and the second oscillator means (90 b) are provided with a first desmodromic cam and a second desmodromic cam, respectively.

23. The folding or cross-folding unit of claim 9, wherein the first and second oscillator devices (90 a,90 b) are connected at respective first ends (81 'a,81' b) of the first and second drive sets (81 a,81 b), the first and second drive sets (81 a,81 b) being operatively connected to the first and second pluralities of separating fingers (40 a,40 b) at respective second ends (81 "a,81" b) opposite the first ends (81 'a,81' b), respectively.

24. A method of folding or cross-folding a paper web or sheet in a paper processing machine, the method comprising the steps of:

-feeding at least one paper web or sheet (5) in an advancing direction (15);

-folding or cross-folding the paper web or sheet (5) at a predetermined folding or cross-folding area of the paper machine, the folding or cross-folding step being performed by a first folding or cross-folding roller and a second folding or cross-folding roller (1 a,1 b) at a folding or cross-folding area (35) defined therebetween;

-separating the paper web or sheet from the outer side surface (11) of the respective folding or cross-folding roller (1 a,1 b) by a first and a second plurality of separating fingers (40 a,40 b), the separating step being performed to cause a back-and-forth oscillating movement of the first and second plurality of separating fingers (40 a,40 b) towards/away from the folding or cross-folding area (35);

the method is characterized in that an adjustment step is also provided for adjusting the phase between the first and second pluralities of separating fingers (40 a,40 b) and the first and second folding or cross-folding rollers (1 a,1 b), respectively, the adjustment step being arranged to retard or advance the oscillating movement of the first and second pluralities of separating fingers (40 a,40 b), in particular with respect to a predetermined reference oscillating movement, so as to retard or advance at least the moments (tr) at which the first and second pluralities of separating fingers (40 a,40 b) are arranged to separate the paper web or sheet from the first and second folding or cross-folding rollers (1 a,1 b), respectively.

25. The method for folding or cross-folding a paper web or sheet according to claim 24, wherein the oscillating movement of the first and second plurality of separating fingers (40 a,40 b) is regulated by an electronic control unit (300) according to at least one of the following parameters:

-the instantaneous operating speed of the folding or cross-folding roller (1);

-the operating speed of the folding or cross-folding roller (1);

-the length of the sheet;

-sheet weight.

26. Method for folding or cross-folding a paper web or sheet according to claim 25, wherein the electronic control unit (300) automatically adjusts the oscillating movement of the first and second plurality of separating fingers (40 a,40 b) or adjusts the oscillating movement of the first and second plurality of separating fingers (40 a,40 b) based on commands received by an interface panel or HMI (human-machine interface).