Patent Application
20220127103
The present invention relates to the technical field of paper converting and related products, and, in particular, relates to a machine for interfolding a web, or sheet of paper, equipped with at least an innovative folding, or interfolding, unit, in particular that is able to cut a web into sheets of predetermined length before folding, or interfolding, the same.
As it is known, in the paper industry different kinds of machines and processes are used for producing tissues, towels and similar products in stacks of interfolded sheets having a determined height. These are obtained by folding the sheets in an “interfolded” way, i.e. closing, at each fold, a final border of the previous sheet and an initial border of the following sheet.
In this way, at the moment of using the same, when a sheet is extracted from the stack, also an initial border of the following sheet is extracted, thus simplifying the use of the same.
The interfolding machines of prior art work one, or more, webs of paper coming from one, or more bobbins, that are cut at a cutting unit, in sheets of predetermined length and fed staggered at a folding unit at which two counter-rotating folding rolls work. More precisely, the cut of the sheets of the webs is carried out on cutting rolls, which cooperate with respective counter-blades.
Among the possible ways to fold the sheets, in particular, the 2 panels “L”-interfolded, the 3 panels “Z”-interfolded, and the 4 panels “W”-interfolded, are known.
In the case of “L”-interfolded, which are produced with machines known as “single-fold”, for example of the kind described in U.S. Pat. No. 6,228,014, the webs of paper are cut in such a way to form two staggered sequences of sheets that are alternately fed to the folding rolls. In this way, each sheet coming from a first direction is overlapped, for about half sheet, to a portion of the sheet coming from a second direction, and vice versa, at the moment in which the fold is carried out.
In the case of “Z”, “W”, or even more interfolded panels, that are obtained by machines known as “multi-fold” machines of the kind for example described in U.S. Pat. No. 3,490,762, a single web of paper is processed and a sequence of sheets that are already partially overlapped arrive from a single direction. As described in EP1520822, the overlapping between two following sheets is carried out immediately after the cut by a transfer roll and a delay roll, which produce, together, a small fold in a previous sheet under which the following sheet at least in part positions.
Both in the single-fold machines and in the multi-fold machines, the folding rolls have a circumference whose length is a multiple of the panel length. In particular, in order to carry out the folding, or interfolding, of the sheets, the folding rolls provide retaining devices, such as for example suction holes, or mechanical pliers, that are synchronously activated for alternately starting and finishing each fold between two successive panels.
For example, as described in EP1457444B1 which comprises advancing and folding rolls having suction holes, a first series of holes keeps the sheets on a folding roll for a determined angular distance, and then “passes” the same to the other folding roll also this provided of a parallel retaining device with suction holes, which operates at another predetermined angular distance. This controlled “passage” of the sheet, or web, of paper from a folding roll to the other one, the desired folding, or interfolding configuration and therefore a stack of interfolded, or folded, sheets is obtained. The “panel length”, which determines the width of the stack of folded sheets exiting the machine, being a submultiple of the planar development of the folding rolls, is, therefore, one of the main constructive constraints of the folding machines, which prevents to change the panel length without completely replacing the folding rolls.
Therefore, both in the case of prior art multi-fold machines, and in the case of prior art single-fold machines, it is necessary to provide both folding, or interfolding, rolls and at least a cutting roll, in addition to the rolls for transferring the sheets from the cutting roll to the folding, or interfolding, rolls. Therefore, besides being complex from a constructive point of view, the prior art machines have a big size. In the prior art machines is, furthermore, necessary to have both cutting rolls and folding, or interfolding, rolls, of suction type, thus having a high energy consumption for producing the vacuum necessary for the suction.
Furthermore, both the multi-fold machines, and the single-fold machines of prior art, are not able to produce different kind of products, because, as above described, both the folding, or interfolding, rolls as well as the cutting rolls, have a predetermined circumference whose length is a multiple of the panel length, whereby they are able to produce only a specific kind of product.
In EP1630118, in the name of the same applicant, a folding machine is described having a framework comprising a folding section in which the sheets are fed to the folding rolls and, therefore, folded in such a way to obtain a determined interfolding configuration. The folding section provides a modular structure comprising a removable portion in order to be replaced with a portion equivalent, but adapted to operate with a different panel length.
Even though the solution described in EP1630118 allows to obtain a machine having a certain flexibility, however, it needs long times for carrying out the replacement of a module with an equivalent one with a consequent high loss of productivity. In fact, the replacement of the folding section is very complicated because it involves both the folding and the cutting rolls.
Another kind of interfolding machine is described in WO2018/019679. More precisely, the interfolding machine provides a folding unit comprising a first and a second folding roll positioned downstream of a respective cutting unit. This provides a fixed cutting blade adapted to operate in combination with a respective counter-cutting blade for each side of the machine. The cutting unit cuts a first and a second web of paper in a respective plurality of sheets that is fed to a respective folding roll of the folding unit. This in addition to the folding rolls, provides a first and a second plurality of the removing fingers that are moved in phase with respective folding rolls for causing the sheets to be removed from the external surface of the same. Separator members are, furthermore, provided for carrying out the separation of a finished stack of interfolded sheets from the following forming stack. Both the removing fingers and the separator elements of WO2018/019679 are moved within respective grooves that are peripherally provided on the folding rolls, that means that the displacement trajectory of the same during the folding step carried out by the folding unit are positioned inside the encumbrance of the folding rolls. Notwithstanding WO2018/019679 refers to the possibility that the cutting rolls can be not present in the machine and that the cutting blades can be directly mounted on the folding rolls, however, since WO2018/019679 does not describe these alternative solutions of the removing fingers and the separator members, also in this case these components will be made as above described. Therefore, the resulting interfolding machine is not able to work because the removing fingers, and even more the separator members, at the separation zone will unavoidably interfere with the cutting blades mounted on the folding rolls, thus making impossible to carry out the folding step and the separation step.
Another solution having similar drawbacks is also described in CN102431833.
It is therefore an object of the present invention to provide a folding, or interfolding, unit, that is able to overcome the aforementioned drawbacks of the folding, or interfolding, unit of prior art.
It is, in particular, an object of the present invention to provide a folding, or interfolding, machine, equipped with a folding, or interfolding, unit, as above described and having a small encumbrance and a reduced energy consumption with respect to the prior art machines.
It is also an object of the present invention to provide a folding, or interfolding, machine, equipped with a folding, or interfolding, unit, as above described and that is able to operate at high speed without compromising the quality of the final product.
It is a further object of the present invention to provide a method for producing folded or interfolded products having the aforementioned advantages with respect to the prior art methods.
These and other objects are achieved by a folding, or interfolding, unit, for folding, or interfolding a first and a second plurality of sheets of paper of predetermined length and arranged to be folded, or interfolded, at a predetermined folding, or interfolding, zone, of a machine for converting paper, or similar product, said folding, or interfolding, unit comprising a first and a second folding, or interfolding, counter-rotating rolls between which said folding, or interfolding, zone, is defined, each of said first and second folding, or interfolding, rolls being provided with:
Other features of the present invention and related embodiments are defined by the dependent claims.
According to another aspect of the invention, a machine for converting paper, or similar product, comprising a folding, or interfolding, unit, as above described.
According to a further aspect of the invention, a method for folding, or interfolding, a first and a second plurality of sheets of paper comprises the steps of:
The invention will now be shown with the following description of its exemplary embodiments, exemplifying but not limitative, with reference to the attached drawings in which:
In
In an embodiment of the invention, each vacuum distribution device 40a, or 40b can provide a longitudinal cavity, the position of which, in figure, is diagrammatically shown with a broken line, provided within the tubular body 10a, or 10b. More in particular, the longitudinal cavity 40a, or 40b, can be permanently connected with the rows of suction holes 11a, 12a, 11b, 12b, but selectively connected to the vacuum generation device. In other words, the suction in the longitudinal cavity 40a, or 40b, of tubular body 10a, or 10b, and, therefore, in the rows of holes 11a, or 11b, or 12a, or 12b, can be activated only at determined angular positions of the holes. This result can be, for example, obtained by electro-valves, or by lateral suction sectors which provides to connect the vacuum generation device to the longitudinal cavity 40a, or 40b, of tubular body 10a, or 10b, only in predetermined angular positions. Advantageously, the aforementioned lateral suction sectors can be bell vacuum distributors arranged coaxially at an end of the tubular body 10a, or 10b. In particular, each bell vacuum distributor develops coaxially to the tubular body 10a, or 10b, and is, preferably, fixed. Therefore, during the rotation of the tubular body 10a, or 10b, zones, or sectors, are formed at which the holes 11a, or 11b, or 12a, or 12b, sucks and, therefore, keep at least a sheet 105a, or 105b, on the surface of the respective tubular body 10a, or 10b, and, instead, other zones, or sectors, at which no suction is carried out.
Alternatively to the aforementioned technical solution, as diagrammatically shown in
Furthermore, according to the invention, as diagrammatically shown in
As shown, for example in
According to the present invention, the folding, or interfolding, unit, 100, furthermore, comprises, a first and a second cutting device 60a, 60b, respectively, associated to the first and to the second folding, or interfolding, roll 1a, 1b. More precisely, the first and the second cutting device 60a and 60b can provide, respectively, at least a first and a second cutting blade 65a, or 65b, for example mounted on a respective, preferably fixed, support body 61a, or 61b.
More in detail, the first and the second folding, or interfolding, rolls 1a, or 1b, provide, respectively, a first and a second plurality of counter-blades 5a and 5b, distributed on the respective tubular body 10a and 10b. The counter-blades 5a and 5b are configured to operate, respectively, in combination with the first and the second cutting blades 65a and 65b, in order to divide a first and a second web of paper 101a and 101b, that are fed along a first and a second feeding direction 111a and 111b, in the aforementioned first and second plurality of sheets 105a and 105b, of predetermined length. In a particular configuration, as shown, for example, in
In the embodiments according to the invention that are diagrammatically shown in
Advantageously, the first and the second plurality of counter-blades 5a and 5b, are positioned, respectively, on the first, and on the second, tubular body 10a and 10b, at predetermined angular positions such to be positioned at a constant angular distance. For example, on each roll 1a, or 1b 3, can be provided counter-blades 5a and 5b, which are positioned at angular positions such that the central angle between two successive angular positions is equal to 120°. The possibility is also provided that the number of counter-blades 5a and 5b on each roll 1a and 1b can be, however, greater than 3, for example equal to 6. In this case, the central angle between two successive angular positions is equal to 60°.
In the embodiment diagrammatically shown in the
In the preferred alternative embodiment shown in the
Preferably, each counter-blade 5a, or 5b, of the first, or the second, plurality of counter-blades is positioned between two suction holes of the same couple of suction holes close to each other (see at this regard the enlargements depicted in the
In
The machine 200 can advantageously, furthermore, provide a removing unit comprising a first plurality of removing members 85a, and a second plurality of removing members 85b, or removing fingers, configured to act, respectively, at the first and the second folding roll 1a and 1b to remove the sheets from the respective folding, or interfolding, roll 1a, or 1b. More precisely, the first and the second plurality of removing members 85a and 85b and the folding rolls 1a and 1b are, advantageously, displaced in phase from each other in such a way to, alternately, advance laterally towards sheet 105a, or 105b, and to move away the same from the respective roll 1a, or 1b, thus, causing the sheet same to be removed from the surface of the roll to which it adheres, without, anyway, interfering with the aforementioned counter-blades 6a, or 6b.
In some particularly advantageous embodiments of the invention, the phase between the removing members 85a and 85b and the folding, or interfolding, rolls 1a and 1b can be mechanically carried out. More in particular, each removing member 85a and 85b can be moved from an internal position to a respective groove, that is not shown in the figures for simplicity, provided in the folding rolls 1a and 1b, to a position external to the folding rolls 1a and 1b same, in such a way to cause the sheets 105a, 105b to be “detached” from the respective folding rolls 1a and 1b. With the expression “mechanical phase” it is to be intended that the removing members 85a and 85b and the folding rolls 1a and 1b are mechanically connected to each other, in particular by gears and/or cams, in particular desmodromic cams, and/or pulleys actuated by the same motor, or by different motors in phase from one another, that means such that are able to give the same law of motion to the kinematic mechanism.
According to a particular embodiment of the invention, the removing members 85a and 85b can have a geometry such that they do not interfere with the plurality of counter-blades 5a and 5b of rolls 1a and 1b. For example, as diagrammatically shown in
In particular, still as diagrammatically shown in
As diagrammatically shown in the two snapshots depicted in the
The displacement unit 90 can be electronically in phase with the folding, or interfolding, rolls 1a and 1b and with the removing members 85a and 85b. In this case, kinematic connection mechanisms between the different components are not provided. The actuation of the displacement unit 90 is, advantageously, operated by an electronic control unit configured to detect, during the cycle of the machine, the instant in which the separator members 80a and 80b have to be inserted in the stack of folding, or interfolding, sheets.
In a further alternative embodiment of the invention also the displacement unit 90 can be mechanically in phase with the other parts of the folding machine. In this case, the change of the length of the stack can be, advantageously, carried out by stopping the machine and modifying the part of the machine adjusting the phase between the displacement unit 90 and the other parts of the folding machine.
Advantageously, in a further alternative embodiment of the invention that is not shown for simplicity, the folding, or interfolding, machine providing of the folding, or interfolding, unit, as above described with reference to
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102019000001579 | Feb 2019 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2020/050731 | 1/30/2020 | WO | 00 |
