Machine for producing stacks of laminar products made of paper material and related method of production

Abstract

A machine (1) for producing stacks of laminar products made of paper material, in particular stacks of napkins, comprises a feeding section (10) to feed a plurality of continuous webs of paper (2a,2b) along respective predetermined feeding directions (102a,102b). The machine (1) comprises, furthermore, a first folding section (20) equipped with a plurality of folding members (21a,21b) each of which configured to fold a respective continuous web of paper (2a,2b) per obtain a respective folded web of paper (2'a,2'b) provided with at least a first folding line (6) longitudinal to the respective continuous web of paper (2a,2b). A cutting section (30) is, furthermore, provided equipped with at least a cutting blade (35) configured to work in combination with a counter-cutting blade (36) in such a way to cut at a cutting point (P1) each folded continuous web of paper (2'a,2'b) into a respective plurality of sheets of paper (4a,4b) folded along the first folding line (6). Downstream of the cutting section (30) a second folding section (40) is provided for further folding each folded sheet of paper and obtaining a respective folded laminar product (5a,5b). The first folding roll (41) puts, then, a folded laminar product of paper (5) on a forming table (50) forming a stack (100) comprising a plurality of folded laminar products.

Description

[0001] TITLE

[0002] MACHINE FOR PRODUCING STACKS OF LAMINAR PRODUCTS MADE OF

[0003] PAPER MATERIAL AND RELATED METHOD OF PRODUCTION

[0004] DESCRIPTION

[0005] Field of the invention

[0006] The present invention relates to the field of machines for producing stacks of products of wide consumption, in particular laminar products made of paper material , such as stacks of napkins , tissues , and similar products .

[0007] The invention also relates to a method for producing such laminar products .

[0008] Description of the prior art

[0009] As known, the machines for producing articles made of paper material of wide consumption such as packages of napkins , packages of tissues , and similar products , provide to feed a continuous web of paper, normally unwound from a reel of great diameter, along a movement direction . Along the aforementioned movement direction, the continuous web of paper is , normally, folded at a folding section according to a longitudinal line . The folding section provides a folding element , normally substantially triangular-shaped, on which the web of paper is caused to move forward, then, is fed between two vertical feeding rolls and, therefore , to a couple of counter-rotating folding rolls also these having a vertical axis . The folding rolls are positioned close to each other in such a way to define a passageway for the continuous web of paper and are provided with folding elements , which, when the web of paper passes through the aforementioned passageway between the folding rolls , make a fold on the web of paper along a direction orthogonal to the aforementioned longitudinal folding line . Normally, the folding elements provide on each folding roll a gripping element configured in such a way to grip the web of paper along a folding line . In some cases , the introduction of the web of paper into the folding member is carried out by blades , or wedges , also these mounted on the folding rolls , but in positions staggered with respect to the gripping elements . More precisely, in order to make a fold on the web of paper, at the aforementioned passageway defined between the two folding rolls , a gripping element of a folding roll and a folding blade of the other folding roll are alternately positioned . More in detail , the folding of the web of paper is obtained by pushing the web of paper by the folding blade of a folding roll into the gripping element of the other folding roll . Therefore , the web of paper adheres , alternately, at first to one folding roll and, then, to the other, whereby downstream of the folding rolls , the web of paper is zigzag folded . Since , normally, a folding roll has a folding blade and a gripping element , at each complete turn of a folding roll about its rotation axis , at least two folds are made on the web . Other types of folding rolls do not have a pliers but hold the sheets by sucking . Downstream of the folding rolls a cutting device and a separation unit are provided . Generally, the cutting device comprises a vertical belt saw, which divides the flow of semifinished folded product formed by napkins attached to each other, exiting the folding rolls into two distinct stacks while the separation unit is configured to separate each zigzag folded stack of panels in a predetermined number of groups each of which containing a number of panels equal to the number of napkins , or tissues , which will form a final package . The belt saws for dividing the stack of semi- finished product into two stacks of napkins are very dangerous for the worker and, furthermore , their maintenance is generally very complicated and expensive . Machines of this type are described for example in EP1599404 , EP1776304B1 .

[0010] In particular, separation units for machines for producing packages of tissues , napkins , and similar products exist which provide to move the separation fingers along a predetermined path . Normally, the aforementioned path has two straight portions , one of gone and one of return, which run parallel to the forming direction of the folded stack of panels , but along which the separation fingers are moved along opposite directions and two straight connection portions in such a way to form a closed path . Among the di f ferent proposed solutions , some of them provide curvil inear connection portions , instead, some others straight connection portions and transversal to the aforementioned gone and return portions . In the case of curvilinear connection portions , often, during the introduction of the separation fingers into the stack of panels the end portions of some panels of the stack are squashed and, therefore , a loss of quality of the product is caused . These trans fer systems are well-known complicated and inef ficient . Separation units are described, for example , in EP0294675 and

[0011] EP1641694 . A drawback of the prior art machines for producing stacks of folded products , in particular tissues and napkins , is to have a low productivity in particular because the axial length of the folding rolls is low, in fact, generally, is equal to the height of a single napkin .

[0012] Furthermore, the prior art machines are extremely rigid because they do not allow to easily and quickly change the product .

[0013] Other examples of prior art machines with analogous disadvantages are also described in W002 / 12102 , W003 / 016184 , W02022 / 070087 and EP2047710 .

[0014] Summary of the invention

[0015] It is , therefore , an obj ect of the present invention to provide a machine for producing stacks of folded products , in particular napkins and tissues made of paper, which is able to solve the problems of the prior art machines .

[0016] It is another obj ect of the present invention to provide a machine for producing stacks of folded products , in particular napkins and tissues made of paper, that have a greater productivity and ef fectiveness than the prior art machines without compromising the quality of the final product .

[0017] It is also an obj ect of the present invention to provide a machine for producing stacks of folded products , in particular napkins and tissues made of paper, that is versatile and allows to easily and quickly operate a change of the product . It is also an obj ect of the present invention to provide a method for producing stacks of folded products , in particular napkins and tissues made of paper, having analogous advantages .

[0018] These and other obj ects are achieved by a machine for producing stacks of laminar products made of paper material , in particular stacks of napkins , tissues , or similar products , said machine comprising : a feeding section configured to feed a plurality of continuous webs of paper along respective predetermined feeding directions ; a first folding section equipped with a plurality of folding members each of which configured to fold a respective continuous web of paper of said plurality in such a way to obtain a respective folded web of paper provided with at least a first folding line longitudinal to said respective continuous web of paper ; a cutting section equipped with at least a cutting blade configured to work in combination with a countercutting blade in such a way to cut each folded continuous web of paper of said plurality in a respective plurality of sheets of paper folded along said first folding line , said or each counter-cutting blade being positioned at a support roll arranged to rotate about a longitudinal rotation axis and provided with an external lateral surface , said support roll being arranged to receive said plurality of folded sheets longitudinally staggered along said external lateral surface , said support roll being, furthermore , provided with a first holding group configured to hold said folded sheets on a predetermined portion of said external lateral surface ; a second folding section positioned downstream of said cutting section, said second folding section comprising at least a first folding roll configured to further fold each folded sheet of paper of said plurality along a second folding line orthogonal a said first folding line obtaining a folded laminar product , said first folding roll being configured to rotate about a longitudinal rotation axis and being provided with a second holding group configured to hold said folded sheet on a predetermined portion of the respective external lateral surface ; whose main characteristic is that said first folding roll is , furthermore , configured to put a folded laminar product at a time on a forming table forming a stack of folded laminar products comprising a plurality of folded laminar products adapted to grow in height along a predetermined forming direction and that said forming table is arranged to progressively move away from said second folding section in such a way to follow the growth of said stack and to position a completed stack on a discharge device arranged to move said completed stack along a predetermined discharge direction, once that a predetermined number of folded sheets is reached .

[0019] In particular, the second folding section can comprise , furthermore, a second folding roll provided with a respective external lateral surface and configured to rotate about a longitudinal rotation axis . More in particular, the second folding roll can be provided with a third holding group configured to hold the folded sheet on a predetermined portion of the external lateral surface , in such a way to make with the first folding roll the second folding line on each folded sheet .

[0020] Preferably, a detaching group can be , furthermore , provided comprising at least a first plurality of detaching elements , or "detaching finger" , associated to said first folding roll . More in particular , the aforementioned plurality of detaching finger can be arranged to cause said folded sheets provided with said first and second folding lines to be detached from the external lateral surface of the first folding roll .

[0021] Furthermore , a separation group can be provided comprising at least a plurality of separation elements configured to move from a position external to said stack being formed to a position internal to said stack being formed, once that the aforementioned predetermined number of folded sheets is reached, in such a way to cause a completed stack of sheets to be separated from a following stack of folded sheets being formed . In particular, the movement of the separation elements from the external position to the internal position can occur by at least one rotation, or by a combination of movements comprising at least one translation and at least one rotation, or by at least two translations along respective directions of translation .

[0022] Preferably, at least a second forming table can be , furthermore , provided configured to move from / towards the second folding section, and wherein, while one between said first and said second forming table is arranged to support said following stack of folded sheets , the other forming table is arranged to trans fer the completed stack on the aforementioned discharge device and vice versa .

[0023] In an embodiment of the invention, a third forming table can be , furthermore , provided configured to move from / towards the second folding section . In particular, in this case , due of said prima, second and third forming table can be adapted to be positioned, respectively, at a first folded laminar product and a last folded laminar product of said completed stack and to position together said completed stack of folded laminar products on a discharge device pressing the same between them, while the other forming table among said first , second and third forming table is arranged to support said stack being formed .

[0024] In particular, the aforementioned plurality of detaching elements is configured to oscillate between a rest position, where they are not in interference with the folded laminar product , and a removal position, where they are in interference with the folded laminar product causing the same to be detached from the external lateral surface of the first folding roll . More in particular, the detaching elements can be adapted to move from the rest position to the removal position by a rotation in a first rotational direction and from the removal position to the rest position by a rotation in a second rotational direction opposite to the first one .

[0025] In particular, each detaching element of the aforementioned plurality, at the rest position, can be adapted to house within a respective groove of a plurality of grooves which are made peripherally to said first folding roll . More in particular , at the removal position, the plurality of detaching elements is adapted to come out of the aforementioned plurality of grooves to move in the aforementioned removal position, where they are in interference with the folded laminar products to cause these to be detached from the external lateral surface o f the first roll .

[0026] In particular, in a first embodiment of the invention, the aforementioned support roll provided with the or each counter-cutting blade is configured to hold the folded sheets on the external lateral surface up to a point of tangency or minimum distance with the first folding roll at which the plurality of folded sheets moves from the support roll to the first folding roll .

[0027] In particular, the first holding group can comprise a first plurality of holding members arranged to hold each folded sheet at a respective head portion and a second plurality of holding members arranged to hold each folded sheet at a respective tail portion . More in particular, said first and second pluralities of holding members can be organized according to respective rows longitudinal to said support roll .

[0028] In particular, the support roll can be coincident with the first folding roll . In this case , the first folding roll is provided with the or each counter-cutting blade .

[0029] Advantageously, the second holding group can comprise holding members of pneumatic type , in particular adapted to be put in pneumatic communication with a device for generating vacuum only at predetermined portions of its external lateral surface , or of mechanical type , or even of mixed pneumatic-mechanical type , advantageously, of the "sucking pliers" type as for example described in WO2022 / 234481 in the name of the same Applicant .

[0030] In an embodiment foreseen, the second holding group can comprise : a first plurality of holding members arranged to hold each folded sheet of said plurality at a respective head portion; a second plurality of holding members arranged to hold each folded sheet of said plurality at a respective tail portion; a third plurality of holding members arranged to hold each folded sheet of said plurality at a respective middle portion .

[0031] According to another aspect of the invention, a method for producing stacks of laminar products made of paper material , in particular stacks of napkins , paper tissues , or similar products , comprises the steps of : feeding a plurality of continuous webs of paper along respective predetermined feeding directions ; making a first fold on said plurality of continuous webs of paper in such a way to obtain a plurality of folded continuous webs of paper provided with at least a first longitudinal folding line ; cutting said plurality of folded continuous webs of paper into a respective plurality of sheets of paper folded along said first folding line, said cutting step being carried out by at least a cutting blade arranged to work in combination with at least a counter-cutting blade positioned at a support roll arranged to rotate about a longitudinal rotation axis and provided with an external lateral surface , said support roll being arranged to receive said plurality of folded sheets longitudinally staggered along said external lateral surface , said support roll being, furthermore , provided with a holding group configured to hold said folded sheets on a predetermined portion of said external lateral surface ; making a second fold by a first and a second folding roll configured to fold each folded sheet of paper of said plurality along a second folding line orthogonal to said first folding line obtaining a plurality of folded laminar products , said first folding roll being adapted to hold said folded sheet on a predetermined portion of a respective external lateral surface ; wherein the first and the second folding roll are configured to put a folded laminar product at a time on a forming table in such a way to form a stack comprising a plurality of folded laminar products adapted to grow in height along a predetermined forming direction, and wherein said forming table is arranged to progressively move away from said second folding section in such a way to follow the growth of said stack of folded laminar products and to put a completed stack, once that a predetermined number of folded sheets is reached, on a discharge device arranged to move said completed stack along a predetermined discharge direction .

[0032] According to a further aspect of the invention, a machine for producing stacks of laminar products made of paper material , in particular stacks of napkins , comprises : a feeding section configured to feed a plurality of continuous webs of paper along respective predetermined feeding directions ; a first folding section equipped with a plurality of folding members each of which configured to fold a respective continuous web of paper of said plurality in such a way to obtain a respective folded web of paper provided with at least a first folding line longitudinal to said respective continuous web of paper ; a second folding section comprising a first and a second folding roll , said first folding roll being provided with an external lateral surface and being arranged to receive said folded webs of paper longitudinally staggered along said external lateral surface , wherein said first folding roll comprises at least a cutting blade configured to work in combination with a counter-cutting blade in such a way to cut at a cutting point ( Pl ) each folded continuous web of paper of said plurality into a respective plurality of sheets of paper folded along said first folding line , and wherein said first and second folding rolls are configured to further fold each folded sheet of paper of said plurality along a second folding line orthogonal to said first folding line obtaining a respective folded laminar product , said first folding roll being provided with a first holding group configured to hold said folded sheet on a predetermined portion of said external lateral surface ; wherein said first and second folding rolls are, furthermore, configured to put a folded laminar product of paper provided with said first and second folding lines , at a time, on a forming table forming a stack comprising a plurality of folded laminar products adapted to grow in height along a predetermined forming direction, and that said forming table is arranged to progressively move away from said second folding section in such a way to follow the growth of said stack and to position a completed stack once that a predetermined height is reached, on a discharge device arranged to move said completed stack along a predetermined discharge direction .

[0033] Brief description of the drawings

[0034] The invention will now be shown with the following description of its exemplary embodiments , exempli fying but not limitative , with reference to the attached drawings in which :

[0035] - Fig . 1 diagrammatically shows a side view of a first embodiment of a machine , according to the invention, for producing stacks of laminar products of paper, in particular stacks of napkins ;

[0036] - Fig . 2 diagrammatically shows a front view of the machine for producing stacks of laminar products of paper of figure 1 ;

[0037] - Fig . 3 diagrammatically shows a detail of a continuous web folded by the first folding section of the machine for producing stacks of laminar products of paper of figure 2 ;

[0038] - Fig . 4 diagrammatically shows an enlargement of a part of the machine of figure 1 to highlight some technical characteristics ;

[0039] - Fig . 5 diagrammatically shows a plan view of a folded laminar product produced by the machine of figure 1 ;

[0040] - Figures from 6 to 8 diagrammatically show a side view of some possible working steps of an alternative embodiment of the machine of figure 1 for producing stacks of laminar products of paper, in particular stacks of napkins ;

[0041] - Fig . 9 diagrammatically shows an enlargement of a part of the machine of figures 6- 8 to highlight some technical characteristics ;

[0042] - Fig . 10 diagrammatically shows a side view of another alternative embodiment of the machine of figure 1 for producing stacks of laminar products of paper, in particular stacks of napkins , according to the invention;

[0043] - Figures from 11 to 13 diagrammatically show a sideview of some possible working steps of another alternative embodiment of the machine of figure 1 for producing stacks of laminar products of paper, in particular stacks of napkins ;

[0044] - Fig . 14 diagrammatically shows an enlargement of a part of the machine of figures 11- 13 to highlight some technical characteristics ;

[0045] - Figures 15 and 16 show a detail of a support roll and of a first folding roll of still another alternative embodiment according to the invention for the machine for producing stacks of napkins ;

[0046] - Fig . 17 diagrammatically shows a side view of another alternative embodiment of the machine of figure 1 for producing stacks of laminar products of paper, in particular stacks of napkins , according to the invention;

[0047] - Fig . 18 diagrammatically shows an enlargement of a part of the machine of figure 17 to highlight some technical characteristics ;

[0048] - Figures 19 and 20 show a detail of a first and a second folding roll that can be used in the machine of figure 17 for producing stacks of laminar products of paper .

[0049] Detailed description of some exemplary embodiments of the invention

[0050] As diagrammatically shown in figure 1 , a machine 1 , according to the invention, for producing stacks of laminar products made of paper material , in particular stacks of napkins , comprises a feeding section 10 configured to feed a plurality of continuous webs of paper, for example first and a second continuous web of paper 2a and 2b, along respective predetermined feeding directions 102a and 102b . The machine 1 provides a first folding section 20 equipped with a plurality of folding members , for example a first and a second folding member 21a and 21b . The folding members 21a and 21b can be configured to fold a respective continuous web of paper 2a and 2b in such a way to obtain a respective folded web of paper 2 ' a and 2 ' b provided with at least a first folding line 6 longitudinal to the respective continuous web of paper 2a and 2b . In particular, each folding member 21a, 21b can be a folding triangle in such a way to make the aforementioned folding line 6 and, therefore, a "V"- folded product, or can be a folding member of dif ferent type, for example a folding trapezium to make on the continuous web of paper at least 2 longitudinal folding lines and to obtain, this way, a "C"-folded web .

[0051] A cutting section 30 equipped with at least a cutting blade 35 is , furthermore , provided configured to work in combination with a counter-cutting blade 36 in such a way to cut at a cutting point Pl , each folded continuous web of paper 2 ' a and 2 ' b into a respective plurality of sheets of paper 4a and 4b folded along the first folding line 6. As diagrammatically shown in figure 1 , the or each cutting blade 35 can be mounted on a fixed support .

[0052] In particular, the or each counter-cutting blade 36 is positioned at a support roll 31 arranged to rotate about a longitudinal rotation axis 131 . More in particular, the support roll 31 is provided with an external lateral surface 33 and is arranged to receive the aforementioned plurality of sheets 4a, 4b folded along the first folding line 6 longitudinally staggered along the external lateral surface 33 ( see figure 2 ) . The support roll 31 is , furthermore, provided with a first holding group configured to hold the folded sheets 4a, 4b on a predetermined portion of the external lateral surface 33 . The first holding group can comprise holding members of pneumatic type , in particular suction holes or rows of holes which are put in pneumatic communication with a device for generating a predetermined vacuum degree only at predetermined angular positions . In a possible embodiment of the invention, the first holding group provides a first plurality of suction holes 38a, in particular organized according to one or more respective longitudinal rows , adapted to suck the folded sheet 4a, or 4b at the head portion, and to hold the same on the external lateral surface 33 , positioned downstream of the or each counter-cutting blade 36 , and a second plurality of suction holes 38b, in particular organi zed according to one or more respective longitudinal rows , adapted to suck the folded sheet 4a, or 4b at the tail portion, and to hold the same on the external lateral surface 33 , positioned upstream of the or each countercutting blade 36 ( see figure 9 ) . In some cases , the first holding group can provide a third plurality of suction holes , not shown for simplicity, in particular organi zed according to one or more respective longitudinal rows , adapted to suck the folded sheet 4a, or 4b, at a middle portion, and to hold the same on the external lateral surface 33 of the support roll 31 .

[0053] The machine 1 provides , furthermore, a second folding section 40 positioned downstream of the cutting section 30 . In particular, the second folding section 40 comprises at least one folding roll 41 arranged to rotate about a respective longitudinal rotation axis 141 and configured to carry out at least a second folding line 7 on each folded sheet of paper 4a, 4b, in particular a second folding line 7 orthogonal to the first folding line 6. In the case diagrammatically shown as an example in the figures from 1 to 9, the second folding section 40 comprises a first and a second counter-rotating folding roll 41 and 42 . These are configured to rotate about respective longitudinal rotational axes 141 and 142 and to further fold each folded sheet of paper 4a, and 4b, of the aforementioned plurality along a second folding line 7 orthogonal to the first folding line 6 .

[0054] In this way, from each folded sheet 4a, 4b a respective folded laminar product 5 is obtained, in particular the so called "M-folded product" , as shown in figure 5. As explained above, by changing the first folding section 20 it is possible to obtain folded laminar products 5 of di fferent type , where, for example, the panels can be in a number greater or less than 4 and / or the surface area of each panel forming the laminar product 5 , can change . According to what is foreseen by the present invention, the first folding roll 41 is configured to put a folded laminar product of paper 5 provided with the first and second folding lines 6 and 7 at a time, on a forming table 50 forming a stack 100 of folded laminar products 5.

[0055] In the case that is diagrammatically shown in the figures from 1 to 9 , the first and second folding rolls 41 and 42 are configured to put the folded laminar product of paper 5 provided with the first and second folding lines 6 and 7 at a time , on the forming table 50 forming the stack 100 of folded laminar products 5 . In particular, the stack 100 grows in height along a predetermined forming direction 105 and the forming table 50 moves along the direction 150 progressively moving away from the second folding section 40 in such a way to follow the growth of the stack 100 . More in particular, at opposite sides of the stack, lateral guides 125a and 125b, which are shown only in the enlargement of figure 9 for clarity reasons , are , advantageously, provided, in order to laterally hold the stack of laminar products 100 same during its displacement by the forming table 50 .

[0056] Once that a predetermined height of the stack is reached, which means a predetermined number of folded laminar products 5 on the forming table 50 , the stack 100 is considered to be completed . The forming table 50 , then, advantageously, moves the corresponding completed stack 100 ' on a discharge device 80 , for example a conveyor belt , arranged to move the completed stack 100 ' along a predetermined discharge direction 180 . In particular, in this way, the completed stack 100 ' can be subj ected to following operations , in particular the banding .

[0057] The discharge device 80 can be adj ustable in height . In particular, the discharge device 80 can be positioned more or less distant from the second folding section 40 .

[0058] In further embodiments , in order to optimi ze and speed up the machine time cycle , the discharge device 80 can be mobile during the formation cycle of the stack 100 , for example can carry out a movement towards the forming table 50 to shorten the stroke of the table same when this discharges a completed stack 100 ' , and then returns with the completed stack 100 ' at a lower height along direction 150 . More in particular, the first folding roll 41 is , advantageously, provided with a second holding group to hold each folded sheet 4a, 4b on its external lateral surface 43 from the point of tangency, or minimum distance , P' 1 with respect to the support roll 31 up to at least a first predetermined releasing point P' 2 .

[0059] The second holding group can be of pneumatic type, which means comprising a predetermined number of rows of suction holes which are put in pneumatic communication with a device for generating vacuum only at a predetermined portion of the surface 43 , or of mechanical type , in particular of the "pliers" type , i . e . comprising a thin plate adapted to move from an opening position to a closing position where is adapted to hold the sheet or even of mixed type, advantageously of the " sucking pliers" type as for example described in WO2022 / 234481 in the name of the same Applicant .

[0060] More precisely, according to a possible embodiment of the invention, the second holding group can comprise a first plurality of holding members 46, diagrammatically shown in figure 9, arranged to catch and hold on the external lateral surface 43 a head portion 4 ' of each folded sheet 4a, 4b from the catching point P' 1 of minimum distance , or of tangency, with the support roll 31 , up to a first releasing point P' 2 at which the first folding roll 41 is tangent to or positioned at a minimum distance with respect to the second folding roll 42 . Also this can be provided with a third holding group 49 , for example of pneumatic type ( figure 9 ) . When the head 4 ' of the folded sheet 4a, or 4b arrives at the aforementioned first releasing point P' 2 , the third holding group 49 of the second folding roll 42 catches , in particular because provided with a suction system which is more powerful than the one of the first folding roll 41 , or because the first plurality of holding members 46 of the first folding roll is deactivated shortly before , or at point P' 2 , the head 4 ' of the folded sheet 4a, or 4b, up to a predetermined respective releasing point P"2 . The first folding roll 41 is , furthermore , provided with a second plurality of holding members 47 arranged to hold the tail 4" of each sheet 4a, or 4b, between the aforementioned catching point P' 1 and the aforementioned first releasing point P' 2 , and of a third plurality of holding members 48 . These are arranged to hold each folded sheet 4a, or 4b, at the middle portion 4"' of the same between the aforementioned catching point P' 1 and a second releasing point P' 3 . More precisely, as diagrammatically shown in figure 9 , the third plurality of holding members 48 of the second holding group can be adapted to hold the middle 4 of the folded sheet 4a, or 4b up to a releasing point P' 3 positioned downstream of the aforementioned releasing point P' 2 .

[0061] The machine 1 is , furthermore, provided with a detaching group 60 comprising at least a first plurality of detaching elements 61 , or "detaching fingers", associated to the first folding roll 41 . In particular, the detaching fingers 61 are adapted to cause the folded laminar products 5a and 5b provided with the first and second folding lines 6 and 7 to be detached from the external lateral surface 43 of the first folding roll 41 . In a possible embodiment not shown in the figure for clarity reasons , the detaching group 60 can comprise , furthermore , a second plurality of detaching elements 61 adapted to work at the second folding roll 42 to remove the folded sheets or laminar products which adhere on the external lateral surface .

[0062] In particular, the aforementioned plurality of detaching elements 61 can be configured in such a way to oscillate between a rest position, where they are not in interference with the folded laminar product 5 , and a removal position, where they are in interference with the folded laminar product 5 to cause the folded laminar product to be removed from the external lateral surface 43 of the first folding roll 41 . More in particular, each detaching element 61 , at the rest position, is housed within a respective groove , in particular a circumferential groove, not shown in the figure for clarity reasons , of a plurality of grooves provided peripherally to the first folding roll 41 . At the moment of remove the folded laminar product 5 from the surface of the first folding roll 41 , the aforementioned plurality of detaching elements 61 is moved from the rest position to the aforementioned removal position, for example by a rotation, where come out of the respective grooves and are arranged in interference with the folded laminar product 5.

[0063] A separation group 70 is , furthermore , provided comprising at least a plurality of separation elements 71 configured to move from a position external to the stack being formed 100 to a position internal to the same stack being formed 100 , once that the aforementioned predetermined number of folded sheets 4a, or 4b, is reached which means a predetermined height, or length depending on the direction of growth of the stack 100 ' , to cause the completed stack of folded laminar products 100 ' to be separated from a following stack of folded laminar products being formed 100 . In particular, the movements of the separation elements 71 from the external position to the internal position can occur by at least one rotation, or by a combination of movements comprising at least one translation and at least one rotation, or by at least two translations along respective translation direction, in this case the translations are preferably orthogonal to each other .

[0064] As diagrammatically shown in particular in the figures from 6 to 8 , at least a second forming table 50 ' can be , advantageously, provided configured to move from / towards the second folding section 40 . In particular, while one between the first and the second forming table , in the figures from 6 to 8 the first forming table 50 , is arranged to support the stack of folded laminar products being formed 100 , the other one , in the figures from 6 to 8 the second forming table 50 ' , is arranged to trans fer the completed stack on the discharge device 80 and vice versa . In this way, the machine 1 can work at a high speed thus increasing the productivity .

[0065] In the embodiments described above with reference to the figures from 1 to 9, the discharge direction 180 is orthogonal to the forming direction 105 of the completed stacks 100 ' . However, the possibility is foreseen that the machine 1 can have a di fferent layout , where , in particular, the discharge direction 180 is parallel to the forming direction 105 of the completed stacks 100 ' , or coincident with the same , as in the case diagrammatically shown in figure 10 .

[0066] In this case, advantageously, a third forming table 50" can be provided configured to move from / towards the second folding section 40 . In particular, two among the first, the second and the third forming table 50 , 50 ' and 50", in the example of figure 10 the second and third forming tables 50 ' and 50", are arranged to be positioned at opposite sides of the completed stack 100 ' , and in particular, respectively, at a first folded laminar product 5a and at a last folded laminar product 5n of the completed stack 100 ' . More in detail , the aforementioned two forming tables 50 ' and 50" are adapted to move together the completed stack of folded laminar products 100 ' on the discharge device 80 , which, this time , causes the completed stack 100 ' to move away along a discharge direction 180 , which is coincident with the forming direction 105 , pressing the same between them . At the same time , the other forming table, in the case of figure 10 the first forming table 50 , is arranged to laterally support the stack being formed 100 .

[0067] According to a further embodiment foreseen by the invention and diagrammatically shown in the figures from 11 to 13 , the first holding group of the support roll 31 can be configured to hold the head portion 4 ' of each folded sheet 4a, or 4b, from the cutting point Pl up to a second releasing point P3 positioned downstream of the point of tangency, or minimum distance , with the first folding roll 41 . In particular, in this case the second holding group of the first folding roll 41 can be arranged to catch the folded sheet 4a, or 4b, at the middle portion 4"' of this . In this working configuration, the rotation of the support roll 31 , which holds the folded sheet 4a, or 4b, at the head portion 4 ' , and of the first folding roll 41 , which holds the folded sheet 4a, or 4b, at the middle portion, about respective rotational axes 131 and 141 , carries out the orthogonal fold 7 on the folded sheet 4a, or 4b, between the support roll 31 and the first folding roll 41 . Then, the first holding group of the support roll 31 releases the head portion and the tail portion of the sheet 4a, or 4b, provided with the second folding line 7 , which, therefore, is positioned by the first folding roll 41 which is still holding the folded sheet 4a, or 4b, at the middle 4"' with the help of the second folding roll 42 , on the forming table 50 . Therefore, in this case , the second folding roll 42 cannot be provided with the third holding group and can be simply a roll for pressing the folded sheet on the first folding roll 41 to obtain a respective folded laminar product 5 . Still in this embodiment but in a di fferent configuration, the second folding roll 42 can be omitted because , as described, does not concur to form the second folding line 7 in combination with the first folding roll 41 .

[0068] In a further alternative embodiment of the figures from 11 to 13 , it is possible to foresee that the second holding group of the first folding roll 41 holds both the middle portion 4"' of the folded sheet 4a, or 4b, and the tail portion . Both the middle portion 4"' and the tail portion, when have held, move from the support roll 31 to the first folding roll 41 in the point of tangency, or minimum distance , between the two rolls .

[0069] With reference to all the embodiments described, in the case that the first folding roll 41 is provided with holding members of mechanical type , in particular of "catching pliers", or of mixed pneumatic-mechanical type of the " sucking pliers" type , the or each cutting blade 35 can be , advantageously, mounted on a movable support , for example on a cutting roll 32 , arranged to rotate about a respective longitudinal rotation axis 132 . More in detail , in this case the support roll 31 can be provided with introducing elements or wedges 37 arranged to assist the catch of the cut sheets 4a and 4b by the holding elements of mechanical type, as for example diagrammatically shown in the figures 16 and 17 , or mixed pneumatic-mechanical , of the first folding roll 41 . In this way, by synchroni zing the rotations of the support roll 31 and the cutting roll 32 , it is avoided that an interference can occur between the or each cutting blade 35 and the wedges 37 of which, in this case, the support roll 31 is provided .

[0070] In the embodiment described with reference to the figures from 1 to 10 , the first folding roll 41 , on the external lateral surface 43 , can be provided with recesses , or "slots" , in such a way that, by synchronizing the rotations of the support roll 31 and the first folding roll 41 , the counter-blades 36 do not interfere with the external lateral surface 43 of the first folding roll 41 .

[0071] In the further embodiment according to the invention and diagrammatically shown in the figures 17 and 18 , the first folding roll 41 can be provided with the or each counter-cutting blade 36. In this case , therefore, the first folding roll 41 coincides with the support roll 31 . More precisely, in this case , the or each cutting blade 35 is adapted to work in combination with the or each countercutting blade 36 mounted on the first cutting roll 41 to divide each folded continuous web of paper 2 ' , for example a first and a second continuous web of paper 2 ' a and 2 ' b .

[0072] In figure 17 it is shown, as an example, a possible path defined by a plurality of guide elements 22 , for example guide rolls , to move the folded webs of paper 2 ' a and 2 ' b from the first folding section 20 on the first folding roll 41 longitudinally staggered with respect to each other analogously to what described above with reference to the figures from 1 to 10 . In this case , therefore, each folded continuous web 2 ' is , at first, cut into a respective plurality of folded sheets 4 , each of which is fed at a second folding section placed between the first and the second folding roll 41 and 42 , where is subj ected to a following folding step to carry out the aforementioned second folding line 7 and to obtain, this way, the folded laminar products 5 . Also in this case , the first and the second folding roll 41 and 42 are adapted to put each laminar product 5 on at least a forming table 50 , which, then, puts the completed stack 100 ' on the discharge device 80 . Also in this embodiment , the first folding roll 41 is , advantageously, provided with the first , the second and the third plurality of holding members 46 , 47 and 48 .

[0073] What described above with reference to the figures from 1 to 16 can be also applied to the embodiment of figures 17 and 18 . In particular, the first holding group can comprise a first plurality of holding members 46 arranged to hold on the external lateral surface 43 of the first folding roll 41 a head portion 4 ' of each folded sheet 4a or 4b between a catching point P' 1 and a first releasing point P' 2 , in particular tangent , or however positioned at a minimum distance , with respect to the second folding roll 42 . This can be provided with a third holding group 49 configured to hold the head portion 4 ' between a point Pl" tangent to the first folding roll 41 and a predetermined releasing point P2" . Furthermore, a second plurality of holding members 47 can be provided arranged to hold a tail portion 4" of each folded sheet 4a, or 4b, between the catching point P' 1 and the first releasing point P' 2 . Finally, a third plurality of holding members 48 can be also provided arranged to hold each folded sheet , at a middle portion 4"' between the catching point P' 1 and a second releasing point P' 3 positioned downstream of the second releasing point P' 2 .

[0074] Also in this embodiment , a detaching group can be , furthermore, advantageously, provided comprising at least a first plurality of detaching elements 60 associated to the first folding roll 41 and arranged to cause the folded laminar products having the first and second folding lines 6 and 7 to be detached from the external lateral surface of the first folding roll 41 .

[0075] In particular, a separation group 70 can be, furthermore, provided comprising at least a plurality of separation elements configured to move from an external position to an internal position with respect to stack being formed 100 once that the aforementioned predetermined number of folded sheets 4a, 4b to cause a completed stack of folded laminar products 100 ' to be separated from a following stack of folded laminar products being formed 100 .

[0076] As diagrammatically shown in figure 16 , also in this case , furthermore, at least a second forming table 50 ' can be provided configured to move from / towards the second folding section 40 . More precisely, while one between the first and the second forming table 50 , 50 ' is arranged to support the stack of folded laminar products being formed 100 , the other forming table 50 , 50 ' moves the completed stack 100 ' on the discharge device 80 and vice versa .

[0077] In particular, in an embodiment not shown in the figures for simplicity but that is , anyway, analogously to what is described above with reference to the embodiment of figure 10 , also in this case , a third forming table 50" can be provided configured to move from / towards the second folding section 40 , and wherein two among the first , the second and the third forming table 50 , 50 ' , 50" are arranged to be positioned, respectively, at a first folded laminar product 5a and of a last folded laminar product 5n of the completed stack of folded laminar products 100 ' to position together this last on the discharge device 80 pressing the same between them, while the other forming table 50 , 50 , 50" among said first , second and third forming table is arranged to support the stack being formed

[0078] 100 .

[0079] Advantageously, the holding members 48 of the third plurality can be selected among: holding elements of pneumatic type, holding elements of mechanical type, or holding elements of mixed type pneumatic-mechanical. In particular, the second folding roll 42 can comprise one or more introducing elements, or wedges, 37' to assist the catch of each folded sheet 4a, or 4b, by the third plurality of holding members when these are holding elements of mechanical type (see figures 19 and 20) . In the embodiments described above with reference to the figures from 1 to 20, the folded sheets 4a, 4b, advantageously, arrive at the folding group 40 not superimposed with each other.

[0080] The foregoing description exemplary embodiments of the invention will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and / or adapt for various applications such embodiment without further research and without parting from the invention, and, accordingly, it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realize the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation.

Claims

CLAIMS1. A machine (1) for producing stacks of laminar products made of paper material, in particular stacks of napkins, said machine (1) comprising: a feeding section (10) configured to feed a plurality of continuous webs of paper (2a, 2b) along respective predetermined feeding directions (102a, 102b) ; a first folding section (20) equipped with a plurality of folding members (21a, 21b) each of which configured to fold a respective continuous web of paper (2a, 2b) of said plurality in such a way to obtain a respective folded web of paper (2'a,2'b) provided with at least a first folding line (6) longitudinal to said respective continuous web of paper (2a, 2b) ; a cutting section (30) equipped with at least a cutting blade (35) configured to work in combination with a counter-cutting blade (36) in such a way to cut at a cutting point (Pl) each folded continuous web of paper (2'a,2'b) of said plurality in a respective plurality of sheets of paper (4a, 4b) folded along said first folding line (6) , said or each counter-cutting blade (36) being positioned at a support roll (31) arranged to rotate about a longitudinal rotation axis (131) , said support roll (31) being provided with an external lateral surface (33) and being arranged to receive said plurality of folded sheets (4a, 4b) longitudinally staggered along said external lateral surface (33) , said support roll (31) being,furthermore, provided with a first holding group (38a, 38b) configured to hold said folded sheets (4a, 4b) on a predetermined portion of said external lateral surface (33) ; a second folding section (40) positioned downstream of said cutting section (30) , said second folding section (40) comprising at least a first folding roll (41) provided with an external lateral surface (43) configured to further fold each folded sheet of paper (4a, 4b) of said plurality along a second folding line (7) orthogonal a said first folding line (6) obtaining a respective folded laminar product (5) , said first folding roll (41) being configured to rotate about a longitudinal rotation axis (141) and being provided with a second holding group (46,47,48) configured to hold said folded sheet (4a, 4b) on a predetermined portion of said external lateral surface (43) ; said machine (1) being characterized in that said first folding roll (41) is, furthermore, configured to put a folded laminar product of paper (5) provided with said first and folding lines (6,7) at a time on a forming table (50) forming a stack (100) comprising a plurality of folded laminar products adapted to grow in height along a predetermined forming direction (105) , and that said forming table (50) is arranged to progressively move away from said second folding section (40) in such a way to follow the growth of said stack (100) and to position a completed stack (100') once that a predetermined number of folded sheets is reached, on a discharge device (80) arranged to move said completed stack (100') along a predetermined discharge direction (180) .

2. Machine for producing stacks of laminar products, according to claim 1, wherein said second folding section (40) comprises, furthermore, a second folding roll (42) provided with a respective external lateral surface (44) and configured to rotate about a longitudinal rotation axis (142) , said second folding roll (42) being provided with a third holding group configured to hold said folded sheet on a predetermined portion of said external lateral surface (44) in such a way to make together with said first folding roll (41) said second folding line (7) on each said folded sheet (4a, 4b) .

3. Machine for producing stacks of laminar products, according to claim 1, or 2, wherein a detaching group (60) is furthermore, provided comprising at least a first plurality of detaching elements (61) associated to said first folding roll (41) and arranged to cause said folded laminar products (55a, 55b) provided with said first and second folding lines (6,7) to be detached from the external lateral surface (43) of said first folding roll (41) .

4. Machine for producing stacks of laminar products, according to any previous claim, wherein a separation group (70) is, furthermore, provided comprising at least a plurality of separation elements (71) configured to move from a position external to said stack being formed (100) to a position internal to said stack being formed (100) same, once that said predetermined number of folded sheets (4a, 4b) is reached, to cause the separation of a completed stackof folded laminar products (100' ) from a following stack of folded laminar products being formed (100) .

5. Machine for producing stacks of laminar products, according to any previous claim, wherein at least a second forming table (50' ) is, furthermore, provided configured to move from / towards said second folding section (40) , and wherein while one between said first and said second forming table (50,50' ) is arranged to support said stack (100) of folded laminar products being formed, the other forming table (50,50' ) is arranged to transfer said completed stack (100' ) on said discharge device (80) and vice versa.

6. Machine for producing stacks of laminar products, according to claim 5, wherein a third forming table (50") is, furthermore, provided configured to move from / towards said second folding section (40) , and wherein two of said first, second and third forming table (50, 50', 50") are arranged to be positioned, respectively, at a first folded laminar product (5a) and at a last folded laminar product (5n) of said completed stack of folded laminar products (100' ) and to position together said completed stack of folded laminar products (100' ) on said discharge device (80) pressing between them said completed stack, while the other forming table among said first, second and third forming table (50, 50', 50") is arranged to support said stack being formed (100) .

7. Machine for producing stacks of laminar products, according to claim 3, wherein said plurality of detaching elements (61) is configured to oscillatebetween said position external to said stack being formed (100) and said position internal to said stack being formed (100) , each detaching element (61) of said plurality, at said position external to said stack being formed (100) being arranged to be housed within a respective groove of a plurality of groove made peripherally to said first folding roll, and at said position internal to said stack being formed said plurality of detaching elements is arranged to come out of said plurality of grooves to be positioned in a position of interference with said folded laminar products to cause these to be detached from said external lateral surface (43) of said first roll (41) .

8. Machine for producing stacks of laminar products, according to any previous claim, wherein said roll provided with said or each counter-cutting blade (36) is a support roll (31) arranged to hold said folded sheets on said external lateral surface (33) up to a point of transfer to said first folding roll (41) at which said plurality of folded sheets move from said support roll (31) provided with said or each countercutting blade to said first folding roll (41) .

9. Machine for producing stacks of laminar products, according to any claim from 2 to 8, wherein said second holding group comprises: a first plurality of holding members (46) arranged to catch and hold on said external lateral surface (43) a head portion (4' ) of each folded sheet (4a, 4b) between a catching point (P'l) and a first releasing point (P'2) tangent to said second folding roll (42) ,said second folding roll (42) being provided with a third holding group configured to hold said head portion (4' ) between a point (Pl") tangent to said first folding roll (41) to a predetermined releasing point ( P2" ) ; a second plurality of holding members (47) arranged to hold a tail portion (4") of each folded sheet (4a, 4b) between said catching point (P'l) and said first releasing point (P'2) ; a third plurality of holding members (48) arranged to hold each folded sheet (4a, 4b) , at a middle portion (4"') between said catching point (P'l) and a second releasing point (P'3) positioned downstream of said second releasing point (P'2) .

10. Machine for producing stacks of laminar products, according to claim 9, wherein said first holding group of said support roll (31) is configured to hold said head portion (4' ) of each said folded sheet (4a, 4b) from said cutting point (Pl) up to a second releasing point (P3) positioned downstream of a point tangent to said first folding roll (41) and wherein said second holding group is arranged to catch each said folded sheet (4a, 4b) at a middle portion (4'") and to hold said middle portion (4'") between a catching point (Pl' ) tangent to said support roll (31) and a releasing point ( P3 ' ) positioned downstream of the point of tangency between said first and said second folding roll (41,42) .

11. Machine for producing stacks of laminar products, according to any previous claim wherein said dischargedevice (80) is configured to be positioned more distant or closer to said second folding section (40) .

12. Machine for producing stacks of laminar products, according to any previous claim wherein said discharge device (80) is configured to be moved towards / from said forming table (50) during a production cycle of said stack (100) .

13. Machine for producing stacks of laminar products, according to claim 4, wherein said separation elements (71) are arranged to move from said external position to said internal position to said stack (100) by a combination of movements comprising at least one translation and at least one rotation.

14. Machine for producing stacks of laminar products, according to claim 4, wherein said separation elements (71) are arranged to move from said position external to said position internal to said stack (100) by a combination of movements comprising at least two translations along respective directions of translation .

15. Machine for producing stacks of laminar products, according to any claim from 1 to 7, wherein said first folding roll (41) is provided with said or each counter-cutting blade (36) .

16. Machine for producing stacks of laminar products, according to any previous claim, wherein a plurality of guide elements (22) is, furthermore, provided arranged to move said folded webs of paper (2' a, 2'b) from said first folding section (20) on said first folding roll (41) longitudinally staggered one with respect to the other.

17. Method for producing stacks of laminar products made of paper material, in particular stacks of napkins, tissues, or similar products, comprising the steps of: feeding a plurality of continuous webs of paper (2a, 2b) along respective predetermined feeding directions (102a, 102b) ; making a first fold on said plurality of continuous webs of paper (2a, 2b) in such a way to obtain a plurality of folded webs of paper (2'a,2'b) provided with at least a first longitudinal folding line (6) ; cutting said plurality of folded continuous webs of paper (2'a,2'b) into a respective plurality of sheets of paper (4a, 4b) folded along said first folding line(6) , said cutting step being carried out by at least a cutting blade (35) arranged to work in combination with at least a counter-cutting blade (36) positioned at a support roll (31) arranged to rotate about a longitudinal rotation axis and provided with an external lateral surface (33) , said support roll being arranged to receive said plurality of folded sheets longitudinally staggered along said external lateral surface (33) , said support roll (31) being, furthermore, provided with a first holding group configured to hold said folded sheets (4a, 4b) on a predetermined portion of said external lateral surface (33) ; making a second fold by at least a first folding roll (41) configured to fold each folded sheet of paper (4a, 4b) of said plurality along a second folding line(7) orthogonal to said first folding line (6) obtaining a respective folded laminar product (5) , said firstfolding roll (41) being provided with a second holding group configured to hold said folded sheet on a predetermined portion of a respective external lateral surface (43) ; said method being characterized in that said first folding roll (41) is configured to put one folded laminar product (5) at a time upon a forming table (50) in such a way to form a stack (100) comprising a plurality of folded laminar products (5) adapted to grow up in height along a predetermined forming direction (105) , and that said forming table (50) is arranged to progressively move away from said first folding roll (41) in such a way to follow the growth of said stack (100) and to position a completed stack (100' ) once that a predetermined number of folded sheets (4a, 4b) is reached on a discharge device (80) arranged to move said completed stack (100' ) along a predetermined discharge direction (180) .

18. A machine (1) for producing stacks of laminar products made of paper material, in particular stacks of napkins, said machine (1) comprising: a feeding section (10) configured to feed a plurality of continuous webs of paper (2a, 2b) along respective predetermined feeding directions (102a, 102b) ; a first folding section (20) equipped with a plurality of folding members (21a, 21b) each of which configured to fold a respective continuous web of paper (2a, 2b) of said plurality in such a way to obtain a respective folded web of paper (2'a,2'b) provided withat least a first folding line (6) longitudinal to said respective continuous web of paper (2a, 2b) ; a second folding section (40) comprising a first and a second folding roll (41,42) , said first folding roll (41) being provided with an external lateral surface (43) and being arranged to receive said folded webs of paper (2'a,2'b) longitudinally staggered along said external lateral surface (43) , wherein said first folding roll (41) comprises at least a cutting blade (35) configured to work in combination with a countercutting blade (36) in such a way to cut at a cutting point (Pl) each folded continuous web of paper (2'a,2'b) of said plurality into a respective plurality of sheets of paper (4a, 4b) folded along said first folding line (6) , and wherein said first and second folding rolls (41,42) are configured to further fold each folded sheet of paper (5a, 5b) of said plurality along a second folding line (7) orthogonal to said first folding line (6) obtaining a respective folded laminar product (5) , said first folding roll (41) being provided with a first holding group configured to hold said folded sheet on a predetermined portion of said external lateral surface (43) ; said machine (1) being characterized in that said first and said second folding rolls (41,42) are, furthermore, configured to put a folded laminar product of paper provided with said first and second folding lines (6,7) at a time on a forming table (50) forming a stack (100) comprising a plurality of folded laminar products adapted to grow in height along a predetermined forming direction (105) , and that said forming table (50) isarranged to progressively move away from said second folding section (40) in such a way to follow the growth of said stack (100) and to position a completed stack (100' ) once that a predetermined number of folded sheets (4a, 4b) is reached on a discharge device (80) arranged to move said completed stack (100' ) along a predetermined discharge direction (180) .

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