Suction roll of a laminar product

Abstract

A suction roll (1) of a laminar product comprises a fixed tubular body (10) provided with an external lateral surface (11) and of an internal lateral surface (12) delimiting a longitudinal suction chamber (16). A rotating tubular body (20) is, furthermore, provided mounted coaxially to the fixed tubular body (10) to rotate about a longitudinal rotation axis (120). The rotating tubular body (20) is provided with at least a first and a second plurality of suction channels (23,24) organized in a respective predetermined number of longitudinal rows (3,4). A device for generating an air-flow (50) is, furthermore, provided for generating an air-flow at a determined pressure in the longitudinal suction chamber (16). The fixed tubular body (10) is provided with a first and a second plurality of circumferential apertures (15a, 15b) distributed, respectively, along a first and a second longitudinal direction (13,14). Each circumferential aperture (15a, 15b) is positioned along a respective circumferential portion of the fixed tubular body (10) to put, respectively, in pneumatic connection the longitudinal suction chamber (16) with at least a row (23, 24) of the first and of the second plurality of suction channels (23, 24), at predetermined angular positions of the rotating tubular body (20).

Description

[0001] SUCTION ROLL OF A LAMINAR PRODUCT

[0002] DESCRIPTION

[0003] Field of the invention

[0004] The present invention relates to the field of paper, and similar products , converting, and in particular it relates to a suction roll , such as an advancement roll , a cutting roll , a folding or interfolding roll of a machine for interfolding a web, or sheet of paper, of the type provided with suction holes which, connected to a vacuum system, allows the sheet , or web, of paper to adhere on the surface of the same .

[0005] The invention, furthermore , relates to a paper converting machine comprising at least such a suction roll .

[0006] Description of the prior art

[0007] As known, many machines used in the industry of the paper, for example rewinding, interf olding, and folding, machines equipped with systems to cause the worked web, or sheet of paper, to adhere on the surface of the rolls , in determined working steps , in order to feed the sheets or webs of paper along a desired path .

[0008] In particular, such systems are used to carry out the fundamental operations of the cut of the paper, or its very quick trans fer from a roll to another one or still of the final fold of the paper same .

[0009] In the last years in the field of paper converting machine , suction rolls provided with pneumatic systems have had a wide di f fusion which causes the worked sheet or web of paper and its adhesion on a determined portion of the external lateral surface of the suction roll . More precisely, as for example described in EP1457444 , or in EP2514698 , the aforementioned suction systems provide a device for generating a determined vacuum degree which is pneumatically connected to the inside of the suction rolls . More precisely, a suction roll of this type comprises a rotating tubular body adapted to rotate about a longitudinal rotation axis and a fixed tubular body positioned coaxially to the rotating tubular body and internally to the same . The surface of the rotating tubular body is provided with a determined number of couples of longitudinal rows of suction holes , normally 3 , or 4 , couples of rows of holes . The fixed tubular body is , instead, provided with a longitudinal row of apertures . Between the rotating tubular body and the fixed tubular body a vacuum distribution device is provided comprising a first and a second sealing element , or gaskets , which are arranged longitudinally to the suction roll at two di f ferent angular positions and at opposite sides with respect to the aforementioned row of apertures of the fixed tubular body . In this way, the internal lateral surface of the rotating tubular body, the external lateral surface of the fixed tubular body and the longitudinal sealing elements form a suction chamber .

[0010] During the rotation of the rotating tubular body with respect to the fixed tubular body, the aforementioned rows of holes are selectively put in pneumatic connection with the aforementioned vacuum generation device dal aforementioned vacuum distribution device . More precisely, only the holes of the rotating roll arranged at a determined instant between the two sealing elements will exert a suction action on the worked sheet, or web, of paper, causing it to adhere on the corresponding portion of an external lateral surface of the suction roll.

[0011] However, these typologies of suction rolls have some drawbacks .

[0012] In particular, normally, a paper converting machine is provided with more than one suction roll, each of which directed to carry out a determined operation of the production cycle. For example, a folding or interfolding machine has, generally, a cutting roll, one or more transfer rolls, and a couple of folding or interfolding rolls. The different suction rolls of the machine are, normally, all connected by a series of ducts to the same vacuum generation device, such as a vacuum pump. This, therefore, must be dimensioned in such a way to guarantee a determined vacuum degree within all the suction rolls, in spite of the pressure drops which, unavoidably, occur along the suction line. These suction lines provide, furthermore, a series of valves for insulating or dividing the vacuum in the different parts of the machine, in particular the different suction rolls, in order to carry out the maintenance or the replacement of each suction roll without disassembling the whole line or adjusting the vacuum degree more functional to the machine. This, therefore, means further concentrated pressure drops along the vacuum suction line and long time for the adjustment in the starting configuration step of the machine.

[0013] In light of the above, it is necessary to oversize the device for vacuum generation in order to compensate the aforementioned pressure drops and to guarantee the ef fectiveness of the suction of the di f ferent rolls . However, this implies high costs of plant and exercise , in particular owing to the high electrical power consumption of the vacuum generation device and to the cost of the generator same .

[0014] In addition to the above , during the functioning of the suction rolls , dusts and fragments of material , in particular of paper, which are present in the environment surrounding the suction roll and produced during the working cycle , are , unavoidably, sucked by the suction line and can, over time , cause at least a partial obstruction both of the suction holes and of the ducts which connect the vacuum generation device to the di f ferent distribution devices , therefore , causing a los s of ef fectiveness of the suction system which is reflected unavoidably in a loss of quality for the final product . Therefore , the suction rolls of known type have to be necessarily periodically subj ected to maintenance interventions for cleaning the di f ferent parts which form the same . The maintenance interventions provide the disassembly of all the connections which keep together the roll same , normally flanged connections . Then, the several ducts , which can have also a length of several dozens of metres , are disassembled in order to be able to clean them, and then connected again to each other and to each suction roll once they have been cleaned .

[0015] The same action is also carried out for the ordinary maintenance interventions which are periodically programmed to replace the sealing elements . These , in fact , because of the friction generated during the rotation of the rotating tubular body about its longitudinal axis , owing to their dragging against the internal lateral surface of the rotating tubular body, are subj ected, over time , to wear .

[0016] In light of the above , therefore , also the maintenance interventions of a prior art suction roll are complex and extremely expensive in terms of workforce , and, therefore , of costs , and of time , both in the case of interventions for cleaning the several parts of the suction roll , and in the case of interventions for replacing the sealing elements .

[0017] Examples of suction rolls with the aforementioned drawbacks are described in EP3781506 , US2004 / 250706 and US 10294058 .

[0018] Summary of the invention

[0019] It is therefore an obj ect of the present invention to provide a suction roll per paper converting machine able to overcome the drawbacks of the prior art rolls .

[0020] It is in particular obj ect of the present invention to provide a suction roll for paper converting machine that is able to simpli fy and speed up the ordinary and extraordinary maintenance interventions , in particular to operate the replacement of the gaskets of which it is provided with .

[0021] These and other obj ects are achieved by a suction roll to suck a laminar product in such a way to cause the laminar product to advance along an advancing direction, said suction roll comprising : a fixed tubular body provided with an external lateral surface and of an internal lateral surface delimiting a longitudinal suction chamber; a rotating tubular body mounted coaxially to said fixed tubular body having an external lateral surface and an internal lateral surface and configured to rotate externally to said fixed tubular body about a longitudinal rotation axis , said rotating tubular body being provided with at least a first and a second plurality of suction channels organi zed according to a respective predetermined number of longitudinal rows ; a device for generating an air-flow arranged to generate an air- flow at a determined pressure in said longitudinal suction chamber ; whose main characteristic is that said fixed tubular body is provided with a first and of a second plurality of circumferential apertures distributed, respectively, along a first and a second longitudinal direction and that each circumferential aperture of said first and second pluralities of circumferential apertures is arranged along a respective circumferential portion of the fixed tubular body to put, respectively, in pneumatic connection said longitudinal suction chamber con at least a row of the first and of the second plurality of suction channels , at predetermined angular positions of said rotating tubular body .

[0022] Other features of the present invention and related embodiments are set out in the dependent claims .

[0023] In particular, the first and second pluralities of circumferential apertures can be positioned on respective circumferential portions of the fixed tubular body circumferentially staggered with respect to each other . In this way, the first and second rows of suction channels can be put in pneumatic connection con la longitudinal suction chamber at the aforementioned predetermined angular positions of the rotating tubular body .

[0024] In an embodiment of the invention, the device for generating an air- flow is provided with a main body integral to fixed tubular body . More in particular, the device for generating an air- flow comprises , furthermore , an impeller adapted to be housed within said main body and operatively connected to a motor to generate said air- flow in said longitudinal suction chamber . In an advantageous embodiment , the aforementioned device for generating an air- flow is arranged to generate an air- flow at a predetermined pressure ( Pi ) less than the atmospheric pressure .

[0025] In particular, the rotating tubular body can be, furthermore, provided with at least a third plurality of suction channels organi zed according to a predetermined number of longitudinal rows . More in particular, the or each longitudinal row of the first and of the second plurality of suction channels can be positioned on the rotating tubular body in such a way to be put in pneumatic connection at said respective angular position con la first plurality of circumferential apertures , whereas the or each longitudinal row of the third plurality of suction channels is positioned on the rotating tubular body in order to be put in pneumatic connection con la second plurality of circumferential apertures at respective predetermined angular positions .

[0026] In an embodiment of the invention, the first and second pluralities of suction channels can be organized in a plurality of suction groups arranged on a plurality of rows circumferential to said rotating tubular body . In particular, each suction group of the aforementioned plurality can comprise at least a first suction channel of the first plurality and at least a second suction channel of the second plurality divided by a partition wall .

[0027] In particular, the cross-section passage of each suction channel of the aforementioned first and second pluralities of suction channels increases , at least for a portion of the its length, going from the internal surface towards the external surface of the rotating tubular body .

[0028] Analogously, la cross-section passage of each suction channel of the aforementioned third plurality of suction channels increases , at least for a portion of the its length going from the internal surface towards the external surface of the rotating tubular body .

[0029] In particular, the first and second pluralities of circumferential apertures of the first and second longitudinal rows of the fixed tubular body have respective circumferential portions arranged side by side going along a longitudinal direction .

[0030] According to another aspect of the invention, a suction roll of a laminar product configured to cause the laminar product to advance along an advancing direction comprises : a fixed tubular body provided with an external lateral surface and of an internal lateral surface delimiting a longitudinal suction chamber; a rotating tubular body mounted coaxially to said fixed tubular body having an external lateral surface and an internal lateral surface and configured to rotate externally to said fixed tubular body about a longitudinal rotation axis , said rotating tubular body being provided with at least a first and a second plurality of suction channels organized in a respective predetermined number of longitudinal rows ; a device for generating an air-flow arranged to generate an air- flow at a determined pressure in said longitudinal suction chamber ; wherein said fixed tubular body is provided with a first and a second plurality of circumferential apertures distributed, respectively, along a first and a second longitudinal direction and wherein each circumferential aperture of said first and second pluralities of circumferential apertures is arranged along a respective circumferential portion of the fixed tubular body to put , respectively, in pneumatic connection said longitudinal suction chamber with at least a row of the first and of the second plurality of suction channels , at predetermined angular positions of said rotating tubular body .

[0031] According to another aspect of the invention, a paper converting machine comprises at least a treatment unit selected among : a folding or interfolding unit adapted to fold or interfold a web or a plurality of sheets made of laminar material , in particular paper, according to a predetermined folding or interfolding configuration; a cutting unit configured to cut a continuous web made of laminar material into a plurality of sheets of predetermined length; an advancement unit arranged to cause a web or sheet of paper to advance along a predetermined advancing direction; or a combination thereof ; wherein said or each treatment unit comprises at least a suction roll as described above .

[0032] Brief description of the drawings

[0033] The invention will be now illustrated with the following description of an exemplary embodiment thereof , exempli fying but not limitative , with reference to the attached drawings wherein :

[0034] - Fig . 1 diagrammatically shows a perspective side elevation view of a first embodiment of a fixed tubular body of a suction roll according to the invention;

[0035] - Fig . 2 diagrammatically shows a perspective side elevation view of a first embodiment of a suction roll according to the invention;

[0036] - Figures 3 and 4 diagrammatically show two di f ferent longitudinal sections of the suction roll of figure 2 ;

[0037] - Figures 5 and 6 diagrammatically show two di f ferent transversal sections of the suction roll of figure 2 ;

[0038] - Fig . 7 diagrammatically shows a longitudinal section of an alternative embodiment of the suction roll of figure 2 ;

[0039] - Fig . 8 diagrammatically shows an enlargement of a portion of the figure 7 to highlight some technical characteristics ;

[0040] - Figures 9 and 10 diagrammatically show two di f ferent transversal sections of the suction roll of figure 7 ;

[0041] - Fig . 11 diagrammatically shows a perspective side elevation view of an embodiment of the fixed tubular body alternative to that of figure 1 ;

[0042] - Figures 12 and 13 diagrammatically show in a perspective side elevation view two possible alternative embodiments of the suction roll of figure 2 ;

[0043] - Fig . 14 shows an enlargement of a portion of figure 13 to highlight some technical characteristics ;

[0044] - Fig . 15 shows another alternative embodiment of the suction roll according to the invention;

[0045] - Fig . 16 diagrammatically shows a possible embodiment of a suction group which can be used by the suction roll according to the invention in an engagement configuration;

[0046] - Fig . 17 shows a cross-section of the suction group of figure 16 according to arrows XVI I-XVI I ;

[0047] - Fig . 18 diagrammatically shows the suction group of figure 16 in a disengagement configuration;

[0048] - Fig . 19 diagrammatically shows a supplementary suction group which can be used by the suction roll according to the invention;

[0049] - Figures 20 and 21 diagrammatically show two di f ferent transversal sections of the suction roll of figure 15 ;

[0050] - Figures from 22 to 24 diagrammatically show side elevation perspective views of further embodiments of the suction roll according to the invention;

[0051] - Fig . 25 diagrammatically shows a perspective side elevation view of another embodiment according to the invention of the fixed tubular body .

[0052] Detailed description of some exemplary embodiments of the invention

[0053] As diagrammatically shown in figure 1 , a suction roll 1 , according to the invention, of the type used for feeding a laminar product, for example a web, or sheet of paper, along an advancing direction, in particular in a paper converting machine , or similar products , comprises a fixed tubular body 10 provided with an external lateral surface 11 and with an internal lateral surface 12 delimiting a longitudinal suction chamber 16 . The suction roll 1 provides , furthermore, a rotating tubular body 20 mounted coaxially to the fixed tubular body 10 and configured to rotate externally to the same about a longitudinal rotation axis 120 . The rotating tubular body 20 is provided with an external lateral surface 21 and an internal lateral surface 22 . In particular, as diagrammatically shown in the figures 3 and 4 , between the rotating tubular body 20 and the fixed tubular body 10 devices can be mounted that allows the rotation of the first with respect to the second, for example bearings 85, or brasses .

[0054] The rotating tubular body 20 is provided with at least a first and a second plurality of suction channels 23 and 24 organized in a respective predetermined number of longitudinal rows 3 and 4 . In the embodiment diagrammatically shown in the figures from 1 to 3 , the rotating tubular body 20 is provided with a plurality of rows 3a and 3b of the first plurality of suction channels 23 of which in figure 2 the first two rows 3a and 3b can be seen, and with a plurality of rows 4a and 4b of the second plurality of suction channels 24 , of which in figure 2 the first two rows 4a and 4b can be seen .

[0055] A device for generating an air- flow 50 is , furthermore, provided arranged to generate an air-flow at a determined pressure, in particular a pressure less than the atmospheric pressure within the longitudinal suction chamber 16 .

[0056] The fixed tubular body 10 is , also , provided with a first and with a second plurality of circumferential apertures 15a and 15b distributed, respectively, along a first and a second longitudinal direction 13 and 14 . In particular, each circumferential or curved aperture 15a and 15b of the first and of the second plurality is positioned along a respective circumferential portion of the fixed tubular body 10 to put , respectively, in pneumatic connection the longitudinal suction chamber 16 with at least one row 3 and 4 of the first and of the second plurality of suction channels 23 , 24 at predetermined angular positions of the rotating tubular body 20 .

[0057] In particular, the first and second pluralities of circumferential apertures 15a and 15b are positioned on respective circumferential portions of the fixed tubular body 10 . More in particular, each circumferential or curved aperture 15a of the first plurality can be positioned close to a respective circumferential or curved aperture 15b of the second plurality, for example at a distance comprised between 1 mm e 150 mm, advantageously at a distance comprised between 1 . 5 mm e 100 mm, preferably at a distance comprised between 1 . 5 mm e 50 mm, for example at a distance comprised between 2 mm e 50 mm .

[0058] More in detail , the aforementioned circumferential portions can extend between the same 2 generatrixes 101 and 102 of the rotating tubular body 20 as in the embodiment diagrammatically shown in figure 1 . In other words , the first and second pluralities of circumferential apertures 15a and 15b of the fixed tubular body 10 can be distributed on a first and a second longitudinal row 13 and 14 arranged side by side , or substantially side by side , circonf erenzialmente going along a longitudinal direction .

[0059] As it will be described in detail in the following, in the alternative embodiment of figure 11 the aforementioned circumferential portions at which the circumferential apertures 15a and 15b are positioned, instead, are provided circumferentially staggered with respect to each other . In particular, as shown in figure 11 , the circumferential portions at which the circumferential apertures 15a and 15b are positioned can be partly overlapped to each other . In particular, as diagrammatically shown in figure 11 , the first and second pluralities of circumferential apertures 15a and 15b of the first and of the second longitudinal row 13 and 14 of the fixed tubular body 10 have respective circumferential portions 17a and 17b arranged side by side going along a longitudinal direction . More precisely, going along a determined number of generatrixes of the cylindrical body of the fixed tubular body 10 , both the circumferential portions 17a and the circumferential portions 17b is met . Instead, going along other generatrixes , only the circumferential apertures 15a, or only the circumferential apertures 15b, is met .

[0060] As , for example , diagrammatically shown in figure 22 , the device for generating an air-flow 50 can comprise a main body 51 where an impeller 52 can be mounted, diagrammatically shown in figure . The impeller 52 can be operatively connected to a motor 56 to cause a rotation about a rotation axis .

[0061] The device for generating the air- flow 50 can be put in pneumatic connection with the aforementioned longitudinal suction chamber 16 by at least a duct 60 , or can be mounted integral to the fixed tubular body 10 ( see figure 23 ) . In both the cases , the device for generating an air- flow 50 is arranged to generate in the longitudinal suction chamber 16 a determined air-flow 55 at a predetermined pressure ( Pi ) , preferably a pressure less than the atmospheric pressure .

[0062] In particular, the device for generating an air- flow 50 is configured to move the air- flow through the longitudinal suction chamber 16 between an inlet 16a and an outlet 16b of which the fixed tubular body 10 is provided of . More in particular, the aforementioned device for generating an air-flow 50 can be selected among a fan, preferably a centrifugal fan, and a compressor, preferably a centri fugal compressor .

[0063] As diagrammatically shown for example in the embodiment of figure 12 , the rotating tubular body 20 can be , furthermore , provided with at least a third plurality of suction channels 25 organized in a respective predetermined number of longitudinal rows 5 . In particular, the aforementioned suction channels 25 of the third plurality can be used for folding the sheet, or web, of laminar material , for example paper, or cardboard, but also non-woven fabric, and similar materials . For example , as diagrammatically shown in figure 20 for an embodiment of the invention, but that can be generally also applied to the other alternative embodiment here described, the suction channels 23 and 24 of the first and of the second plurality can be used to suck, respectively, the head or a head portion 6 , and the tail or a tail portion 7 , of a sheet 5 of laminar material at a time, in particular for moving the same downstream of a cutting section, not shown in figure for simplicity .

[0064] In an embodiment foreseen, the or each longitudinal row of suction channels 23 and 24 of the first and of the second plurality of suction channels can be positioned on the rotating tubular body 20 , in such a way to be put in pneumatic connection at the aforementioned respective predetermined angular positions with the first plurality of circumferential apertures 15a . Instead, the or each longitudinal row of suction channels 25 of the third plurality of suction channels can be positioned on the rotating tubular body 20 in order to be put in pneumatic connection with the second plurality of circumferential apertures 15b at the respective predetermined angular positions . For example, whereas , as anticipated above , the first and second pluralities of suction channels 23 and 24 can be adapted to suck the head and the tail of a sheet of laminar material on the surface 21 of the rotating tubular body 20 , in particular paper, the third plurality of suction channels 25 can be adapted to suck the aforementioned sheet at the centre portion 8 of the sheet 5, in particular to allow the suction roll 1 to make a fold or an interfold, at a folding or interfolding section, cooperating with a second suction roll 1 counterrotating with respect to the same .

[0065] In an embodiment foreseen by the invention and diagrammatically shown in the figures from 12 to 21 , the first and second pluralities of suction channels 23 and 24 can be organi zed in a plurality of suction groups 30 . These can be arranged on a plurality of rows 36 circumferential to the rotating tubular body 20 . Each suction group 30 comprises , in particular, a first suction channel 23 of the first plurality and a second suction channel 24 of the second plurality divided by a partition wall 27 .

[0066] In another embodiment a fourth plurality of suction channels 26 is , furthermore , provided organized according at least a row longitudinal to the rotating tubular body 20 . In an embodiment according to the invention, each suction group 30 can be an insert member arranged to be engaged to the rotating tubular body 20 at a respective seat . Also the suction channels 26 can be involved in the suction step of the centre portion 8 of the sheet 5 .

[0067] In the case that also the aforementioned fourth plurality of suction channels 26 is present , a second plurality of suction groups 30 ' can be provided . In particular, as for example diagrammatically shown in figure 19, each suction group 30 ' of the second plurality can comprise at least a suction channel 25 of the third plurality and at least a suction channel 26 of the fourth plurality divided by a partition wall 27 ’ .

[0068] In particular, the longitudinal rows of the first and of the second suction group 30 and 30 ' can be , preferably, positioned alternating to each other on the rotating tubular body 20 .

[0069] As diagrammatically shown in figure 23 at least a pressure sensor 80 can be, furthermore, provided arranged to detect the pressure within the longitudinal suction chamber 16 . In particular, the or each pressure sensor 80 can be arranged to send a corresponding pressure signal P ( ti ) to a control unit 300 arranged to operate the aforementioned device for generating an air-flow 50 . More in particular, the control unit 300 can be arranged to adj ust the device for generating an air-flow 50 in function of the received pressure signal P ( ti ) , in particular acting on a motor 56 of which this is provided with . In this way, the air-flow 55 can be increased or decreased to increase or decrease , the pressure P ( ti ) in the longitudinal suction chamber 16 and to bring the same to be equal to a predetermined value P* , or anyway to differ from that less than a predetermined deviation value AP* .

[0070] As , for example shown in the figures 3 , 4 , 8 , and from 17 to 19 , the cross-section passage of each suction channel of the first and of the second plurality of suction channels 23 and 24 increases , at least for a portion of the length, advantageously, going from the internal surface 22 to the external surface 21 of the rotating tubular body 20 . Advantageously, each suction channel 23 and 24 of the first and of the second plurality, and in case each channel 25 and 26 of the third and of the fourth plurality, i f present, is associated to a respective shield member 40 . This can be, in particular, provided with a plurality of holes 41 of size such that the worked product of laminar material , in particular a web or sheet of paper, is impeded from entering in the suction channels 23 , 24 , and analogously in the suction channels 25 and 26 , i f present , and allow, at the same time , to be sucked in order to adhere to the predetermined angular portions of the external surface 21 of the rotating tubular body 20 at the circumferential apertures 15a and 15b, in such a way to allow the same to be trans ferred downstream of the suction roll 1 along the aforementioned advancing direction .

[0071] In particular, as diagrammatically shown in the figures from 16 to 19, each suction group 30 can comprise a hollow body 31 provided with the first and the second suction channel 23 and 24 ( figures from 16 to 18 ) , or with the third and the fourth suction channel 25 and 26 ( figure 19 ) .

[0072] In particular, each suction group 30 can be associated to a respective shield member 40 , advantageously provided with a plurality of holes 41 . The shield member 40 can be configured to move from an engagement configuration ( figures 16 and 17 ) to a disengagement configuration ( figures 18 and 19 ) , in particular with respect to the hollow body 31 , for example by a coupling which can be disassembled by screws , or bolts , or similar engagement elements , not shown in the figure for simplicity . In this way, in case of need, or during programmed interventions of ordinary maintenance, it is possible to remove the shield member 40 in such a way to be able to reach the hollow body 31 and, therefore , to carry out the cleaning interventions for cleaning from dusts and fragments of the worked product the suction channels 23 , 24 , 25 and 26 where unavoidably they penetrate during the functioning of the machine provided with the or each suction roll 1 , according to the invention . In particular, each hollow body 31 is housed, in use , in a respective seat 28 of which the rotating tubular body 20 is provided with .

[0073] More precisely, the shield member 40 is provided with the aforementioned plurality of holes 41 . These are adapted to put in pneumatic connection each suction channel 23 , 24 , 25, and 26 , advantageously having an inlet opening 23a, 24a, 25a and 26a of si ze less than the outlet opening 23b, 24b, 25b and 26b with the external surface 21 of the rotating tubular body 20 .

[0074] As diagrammatically shown in the embodiment of figure 18 , the shield member 40 can be provided with a longitudinal lowered portion 45. In this way, in working conditions , it is possible to avoid to obstruct the action of any cutting blade of a cutting section, not shown in figure for simplicity, positioned downstream of the suction roll 1 to divide the continuous web made of laminar material into a plurality of sheets of predetermined length .

[0075] As diagrammatically shown in the figures from 1 to 25 , each suction channel 23 , 24 , 25 and 26 is configured in such a way to extend longitudinally to the rotating tubular body 20 .

[0076] Analogously, each circumferential aperture 15a and 15b can be configured in such a way to extend longitudinally to the fixed tubular body 10 .

[0077] In the embodiment diagrammatically shown in figure 24 , a cover member 70 is provided adapted to be positioned at the inlet 16a of the longitudinal suction chamber 16 . In particular, the cover member 70 can be provided with a passageway opening 71 through which the air-flow 55 enters the longitudinal chamber 16 sucked by the device for generating an air- flow 50 , and wherein an adj ustment group 77 is , furthermore , provided to increase , or decrease , the cross-section passage of the passageway opening 71 . For example , as diagrammatically shown in figure 24 , the adj ustment group 77 can comprise a series of movable elements 75 arranged to engage in respective guide 76 to be moved in a guided way and to increase or decrease depending on the need, the cross-section of the passageway opening 71 .

[0078] In the further alternative embodiment diagrammatically shown in figure 25, between a circumferential aperture 15a, or 15b, and the following circumferential aperture 15a, or 15b, the fixed tubular body 10 can be , advantageously, provided with an annular portion 18 adapted to pneumatically separate the same .

[0079] The suction roll 1 as described above can be installed in a treatment unit of a paper converting machine .

[0080] In particular, at least a first and a second suction roll 1 counter-rotating with respect to each other can be installed at a folding or interfolding unit configured to fold or interfold a web or a plurality of sheets according to a predetermined folding or interfolding configuration .

[0081] The suction roll 1 , as described above , can be also installed at a cutting unit configured to cut a continuous web made of laminar material into a plurality of sheets for causing them to advance downstream of the aforementioned cutting unit .

[0082] In an embodiment foreseen the suction roll 1 , as described above, can be installed at an advancement unit arranged to cause a web or sheet of paper to advance along a predetermined advancing direction .

[0083] The foregoing description of a speci fic embodiment wil l so ful ly reveal the invention according to the conceptual point o f view, so that others , by applying current knowledge , wil l be able to modi fy and / or adapt for various applications such an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. The means and the materials to realise 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 employed herein is for the purpose of description and not of limitation.

Claims

CLAIMS1. A suction roll (1) for sucking a laminar product in such a way to cause said laminar product to advance along an advancing direction, said suction roll (1) comprising : a fixed tubular body (10) provided with an external lateral surface (11) and with an internal lateral surface (12) delimiting a longitudinal suction chamber (16) ; a rotating tubular body (20) mounted coaxially to said fixed tubular body (10) having an external lateral surface (21) and an internal lateral surface (22) and configured to rotate externally to said fixed tubular body (10) about a longitudinal rotation axis (120) , said rotating tubular body (20) being provided with at least a first and a second plurality of suction channels (23, 24) organized in a respective predetermined number of longitudinal rows (3, 4) ; a device for generating an air-flow (50) arranged to generate an air-flow at a determined pressure in said longitudinal suction chamber (16) ; said suction roll (1) being characterized in that said fixed tubular body (10) is provided with a first and a second plurality of circumferential apertures (15a, 15b) distributed, respectively, along a first and a second longitudinal direction (13, 14) , and in that each circumferential aperture (15a, 15b) of said first and second pluralities of circumferential apertures (15a, 15b) is arranged along a respective circumferential portion of said fixed tubular body (10)to put, respectively, in pneumatic connection said longitudinal suction chamber (16) con at least a row (23, 24) of said first and second pluralities of suction channels (23, 24) , at predetermined angular positions of said rotating tubular body (20) .

2. Suction roll (1) according to claim 1, wherein said first and second pluralities of circumferential apertures (15a, 15b) are positioned on respective circumferential portions of said fixed tubular body (10) circumferentially staggered with respect to each other .

3. Suction roll (1) according to claim 1, wherein said device for generating an air-flow (50) is provided with a main body (51) integral to said fixed tubular body (10) is provided with an impeller (52) housed in said main body (51) and operatively connected to a motor (56) to rotate about a rotation axis in order to generate in said longitudinal suction chamber (16) said determined air-flow.

4. Suction roll (1) according to any previous claim, wherein said rotating tubular body (20) is, furthermore, provided with at least a third plurality of suction channels (25) organized in a respective predetermined number of longitudinal rows (5) , wherein said or each longitudinal row of said first and second pluralities of suction channels are positioned on said rotating tubular body (20) in such a way to be put in pneumatic connection at said respective angular position con said first plurality of circumferential apertures (15a) , whereas said or each longitudinal rowof said third plurality of suction channels is positioned on the rotating tubular body in order to be put in pneumatic connection with the second plurality of circumferential apertures (15b) at respective predetermined angular positions.

5. Suction roll (1) according to any previous claim, wherein said plurality of said first and second suction channels (23, 24) are organized in a plurality of suction groups (30) arranged on a plurality of rows (36) longitudinal to said rotating tubular body (20) , each suction group (30) of said plurality comprising a first suction channel (23) of said first plurality and a second suction channel (24) of said second plurality divided by a partition wall (27) .

6. Suction roll (1) according to any previous claim, wherein at least a pressure sensor (80) is provided arranged to detect the pressure in said longitudinal suction chamber (16) and to send a corresponding pressure signal (P(ti) ) to a control unit (300) arranged to control said device for generating an air-flow (50) in function of said pressure signal (P(ti) ) .

7. Suction roll (1) according to any previous claim, wherein the cross-section passage of each suction channel of said first and second pluralities of suction channels (23,24) increases going from said internal surface (22) to said external surface (21) of said rotating tubular body (20) .

8. Suction roll (1) according to claim 1, wherein said first and second pluralities of circumferentialapertures (15a, 15b) of said first and second longitudinal rows (13,14) of said fixed tubular body (10) have respective circumferential portions (17a, 17b) arranged side by side going along a longitudinal direction .

9. Suction roll (1) according to any previous claims, wherein said device for generating an air-flow (50) is a centrifugal compressor or a centrifugal fan provided with a main body (51) , said main body (51) being integral to said fixed tubular body (10) and configured to house an impeller (52) arranged to rotate about a rotation axis substantially coaxial to said fixed tubular body (10) operated by a motor (56) .

10. Suction roll (1) according to any claim from 5 to 9, wherein each suction group (30) of said plurality is associated to a respective shield member (40) provided with a plurality of holes (41) of size such that said worked laminar product is impeded from entering into said suction channels (23,24) and to allow, at the same time, that said worked laminar product is sucked to adhere to said predetermined angular portions of said external lateral surface (21) of said rotating tubular body (20) .

11. Suction roll (1) according to any previous claim, wherein a cover member (70) is, furthermore, provided arranged to be positioned at said inlet (16a) of said longitudinal suction chamber (16) , said cover member (70) being provided with a passageway opening (71) through which said air-flow is arranged to enter said longitudinal suction chamber (16) sucked by said devicefor generating an air-flow (50) , and wherein an adjustment group (77) is, furthermore, provided adapted to increase or decrease the cross-section passage of said passageway opening (71) .

12. Suction roll (1) according to claims 3 and 6, wherein said control unit (300) is arranged to act on said motor (56) of said device for generating an air-flow (50) to adjust said air-flow (55) to increase or decrease, said pressure P(ti) in said longitudinal suction chamber (16) , in such a way to bring said pressure to be equal to a predetermined value P*, or to differ from that less than a predetermined deviation value AP* .

13. Suction roll (1) according to one or more of the previous claims, wherein said suction channels (23, 24) of said first and second pluralities are used to suck, respectively, a head portion and a portion of tail, of a sheet of laminar material (5) .

14. Suction roll (1) according to claim 5, wherein each suction group (30) comprises a hollow body (31) provided with said first and with said second suction channel (23, 24) , each hollow body (31) being housed, in use, in a respective seat (28) of which said rotating tubular body (20) is provided with.

15. Suction roll (1) according to claims 10 and 14, wherein said shield member (40) is configured to move from an engagement configuration to a disengagement configuration with respect to said hollow body (31) .

16. Suction roll (1) according to one or more of the previous claims, wherein each circumferential or curvedaperture ( 15a) of said first plurality is positioned at a distance comprised between 1 mm and 150 mm from a respective circumferential or curved aperture ( 15b) of said second plurality .17 . Paper converting machine comprising a folding or interfolding unit arranged to fold or interfold a laminar product , in particular a web or a plurality of sheets , according to a predetermined folding or interfolding configuration said machine being characterized in that said folding or interfolding unit comprises at least a suction roll according to any claim from 1 to 16 .18 . Paper converting machine according to claims 4 and 17 , wherein said suction channels ( 25 ) of said third plurality are engaged to suck a centre portion ( 8 ) of a sheet of laminar material ( 5 ) .

19. Paper converting machine comprising at least a treatment unit selected among : a folding or interfolding unit arranged to fold or interfold a laminar product, in particular a web or a plurality of sheets , according to a predetermined folding or interfolding configuration; a cutting unit configured to cut a continuous web made of laminar material into a plurality of sheets ; an advancement unit arranged to cause a laminar product , in particular a web or sheet of paper, to advance along a predetermined advancing direction; or a combination thereof ; said machine being characterized in that said at least a treatment unit comprises at least a suction roll according to any claim from 1 to 16.

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