Patent Application
20180354741
The present invention relates to the production of articles made of paper into stacks of sheets, for example sheets that are simply folded or interfolded, and it relates, in particular, to a web or sheet conveying unit for paper converting machines.
Furthermore, the invention relates to a structure of folding and stacking machine of such sheets that uses such conveying unit.
As well known, in the paper industry, different types of machines and processes exist for producing paper tissues, towels and similar articles into stacks of sheets of a determined height.
The stacks can be produced by folding the sheets in an “interfolded” way, i.e. at each fold a wing of the previous sheet and a wing of the next adjacent downstream sheet are overlapped to each other. In the interfolded way, when a sheet is extracted from the stack, at the moment of the use, also a wing of the next adjacent downstream sheet is extracted, with subsequent ease for certain types of users.
Among the different possible way to fold the sheets, the L-type, with 2 panels (single-fold), or the Z, or W types, respectively with 3 and 4 panels (multi-fold) are known.
The folding machines use one or more webs of paper coming from one or more rolls cut into sheets and fed shifted from each other on counter-rotating folding rollers. More precisely, the cut of the webs into sheets is carried out on cutting rollers, which alternately interact with respective counter-blades.
In case of L-type interfolding, obtained by “single-fold” machines, as for example described in U.S. Pat. No. 6,228,014, the two webs coming from two different directions, are cut in such a way to form two shifted successions of sheets that are alternately fed to the folding rollers. In this way, once the fold is carried out, about half sheet of each sheet coming from a first direction is overlapped with a portion of the sheet coming from a second direction, and vice-versa.
In case of Z-type or W-type interfolding, or in case of even more panels, produced by “multi-fold” machines, as for example described in U.S. Pat. No. 3,490,762, a single web is generally fed, and a stream of already partially overlapped sheets reaches, from a single direction, the folding rollers. The overlapping of two successive sheets happens immediately after the cut, as described in EP1520822, by means of a transfer roller and a retard roller, which together produce a bend in an upstream sheet, under which, the downstream sheet partially overlaps.
Both in the single-fold and in the multi-fold machines, in order to continuously fold the sheets, the folding rollers of prior art have a circumference that is a multiple of the length of a folded panel. Furthermore, the folding rollers of prior art provide devices for holding the sheet, or web, of paper, such as suction holes, or mechanical clamps, that are synchronously and alternately operated for starting and completing each fold of two successive panels on each other.
For example, EP1457444B1 discloses conveying and folding rollers having suction holes, with a first series of suction holes holding the sheets on a folding roller for a determined angular distance, and then “delivering” it to the other folding roller, also having a parallel holding device with suction holes, which works for another predetermined angular distance. Through this controlled “delivery” of the sheets, or web, of paper, from a folding roller to another, a desired folding, or interfolding, configuration is carried out, obtaining a stack of folded, or interfolded, sheets.
The “panel length”, which determines the width of the stack of folded sheets exiting the machine, is a submultiple of the circumferential development of the folding rollers, and, therefore, it is one of the main structural constraints of the folding machines, that prevents from changing the length of the panels without completely changing the folding rollers.
In EP1630118, in the name of the same Applicant, an interfolding machine is described having a framework, which comprises a folding section where the sheets are fed to the folding rollers shifted from each other, and then folded in such a way to obtain a predetermined interfolding configuration. The folding section provides a structure of modular type comprising a portion that can be removed in order to be exchanged with an equivalent portion, but capable of working with a different panel length.
Notwithstanding the solution described in EP1630118, which is capable of giving to the machine a certain versatility, a long time is required for changing a module with another equivalent module with a loss of productivity. Furthermore, it is necessary to have wide areas available where it is possible to position the different modules that are not installed in the machines. The different modules have, in fact, a considerable encumbrance.
It is also known that, in many industrial fields, machines are provided with conveying rollers for conveying the webs, or sheets, of paper, or similar thin materials, where the conveying rollers have peripheral holes for applying the suction, which determines an adhesion of the webs, or the sheets, to the roller surface for a predetermined conveying angle. The modification of the pitch between the holes, for example in order to transfer sheets of different length, needs, however, that the roller is exchanged with another roller having suction holes with a different pitch, and, therefore, different diameter, with considerable production problems, for the long stops that are needed. In order to reduce the duration of the stops, for example, EP1826165 describes a system for replacing groups of rollers for changing the cut-off parameter, i.e. the length of each sheet.
It is therefore an object of the present invention to provide an improved structure of sheet folding and stacking machine, which is highly versatile and, in particular, able to produce stacks of folded sheets with panels having different length.
It is also an object of the present invention to provide a similar structure of sheet folding and stacking machine that is able to change very quickly the length of the panels.
It is a particular object of the present invention to provide a folding and stacking machine that is constructively easier and less encumbering than similar machines of prior art, for producing stacks of interfolded sheets with a panel length that can be changed.
These and other objects are achieved by a folding and stacking machine, according to the present invention, comprising:
In this way, each belt slides air-tightly on a peripheral groove closing the respective suction portion, producing a pneumatic vacuum under the belt. The vacuum is transmitted to the web, or sheet, that is in contact with the belt, and therefore there is a perfect adhesion of the sheet, or web thereon. The belts are positioned on respective supports in such a way that, at a central line, the sheet, or web, is withdrawn from one, or the other belt, like the folding rollers of prior art. In practice, the belts are initially positioned in such a way that the holes of the two respective belts are shifted at a distance from each other corresponding to a panel length, in the conveying direction of the sheets. This way, by changing the length of the belts, it is possible to change the distance between the holes of a same belt, changing the width of the panel of the folding/interfolding machine.
Preferably, each support is a fixed support. In this way, a considerable structural simplification is obtained with respect to a folding section of prior art, since less moving parts and components are provided.
Alternatively, each support can be arranged to be movable, in particular, in the case each support is substantially cylindrical-shaped, it can be arranged to rotate ad a predetermined speed about a rotation axis.
Preferably, each suction belt provides a predetermined number of rows of through holes.
In particular, each suction belt can provide a plurality of rows of through holes. In this way, it is possible to make more folds at each complete turn of a belt. It is therefore possible to design belts with a length that allows to avoid that the positioning of the different parts of the machine, by the respective motorization, can be obstructed.
In particular, each row can comprise, in turn, a plurality of through holes. This technical solution allows, in particular, to carry out a more effective suction of the web, or sheet, by the belt.
More precisely, in the case of suction belts used in a folding section, the distance between two successive rows of through holes, i.e. the pitch of the rows of through holes, is substantially equal to the double of the length of a panel.
In a possible embodiment, the first and the second support have a substantially circular cross section and the length of the, or each, peripheral suction groove is arranged to define a suction portion extending for a predetermined angular width α, in particular set between 30° and 120°.
In particular, each suction portion of the lateral surface is pneumatically connected to a respective suction chamber. More precisely, each suction chamber is, advantageously, housed in a respective support and is pneumatically connected to a vacuum pump.
Preferably, each suction belt is a toothed belt comprising a plurality of teeth alternated to a plurality of recesses. More precisely, the plurality of teeth is arranged to engage with a corresponding plurality of recesses made on the lateral surface of the respective support. Analogously, each recess of said plurality is arranged to engage with a corresponding protrusion of said plurality of protrusions made on the lateral surface of the respective support. This technical solution allows to constrain the belt to the support, in such a way to accurately guide the belt same, during its movement along the above described trajectory, and to improve the air-tight engagement.
In particular, at least one portion of the surface of said, or each, support can be the external surface of a bearing. In this way, it is possible, in use, to reduce the friction at contact points of the suction belt with the external surface of the support, thanks to the presence of the bearing.
Advantageously, at the lateral surface of the support at least one bearing is provided arranged, in use, to reduce the friction and to avoid, therefore, the a sliding engagement of the suction belt on the support surface. In particular, the friction reduction between the support and the belt allows to considerably reduce the friction of the components in play and, therefore, their half-life, besides reducing the energy consumption.
Preferably, the, or each, peripheral suction groove can be provided at a respective protrusion of said lateral surface of said support.
Alternatively, the, or each, peripheral suction groove can be made at a respective recess of said lateral surface of said support.
Advantageously, each support can provide:
In particular, a plurality of suction belts can be provided, having a different pitch, for example stored in a storage housing available for the machines, namely with a different distance between two successive rows of suction holes, provided on said suction belts. The different suction belts are arranged to be selectively installed at the folding, or interfolding, section, i.e. mounted on the support, for processing panels of different length corresponding to half of the pitch between the holes, and, therefore, to obtain folded sheets with panels of different length.
In other words, in order to change the panel length, it is sufficient to stop the production of the machines, to replace the current suction belts with similar suction belts having the pitch between the holes equal to the double of a new panel length, i.e. the stack width. Furthermore, in general, it is necessary to automatically, or manually, adjust the supplemental folding and separation members, as for example the folding fingers, the containing guides of the stack, and the separation combs, in addition to adjust the cutting group, or cut-off, where it is necessary.
In particular, the machine can comprise, furthermore, a feeding section capable of feeding at least one web of paper, at a predetermined conveying speed, to said folding section.
Advantageously, the folding, or interfolding, machine, comprises, furthermore:
Advantageously, the cutting section comprises at least one cutting roller, on which at least one blade operates arranged to divide the web of paper into a plurality of sheets having a predetermined length.
Alternatively to the cutting section, the machine can provide a perforating section arranged to perforate said, or each, web of paper without dividing it into sheets. More in detail, the perforating section is capable of making the perforation lines on the processed web of paper at a predetermined distance from each other. In this case, downstream of the perforation section, a tearing section is provided that is arranged to divide said web of paper, provided with said perforations, into a plurality of sheets.
In particular, in the transfer section, at least one transfer roller can be provided having holding members arranged to hold the cut sheets in the cutting section and to transfer them directly to the folding, or interfolding, section.
Advantageously, the transfer section comprises, furthermore, at least a first and a second transfer belt. More in detail, each transfer belt is arranged to receive the sheets from the transfer roller and to transfer them to a respective suction belt of the folding, or interfolding, section.
Advantageously, it is possible to provide a separation section, at which separation members can be provided that is arranged to enter into the stack, once completed, and to separate the same from a successive forming stack.
According to another aspect of the invention, a conveying unit of a web, or sheet, of paper is provided that is arranged to transfer along a transfer direction of a paper converting machine, the web, or the sheet, of paper, and comprises:
Further characteristics and the advantages of the invention will be made clearer with the following description of some exemplary embodiments thereof, exemplifying but not limitative, with reference to the attached drawings, in which:
Figs. from 14 to 16 diagrammatically show some embodiments of the machine for holding the paper using the transfer unit according to the invention in the folding, or interfolding, section.
With reference to
Device 100, according to the invention, comprises, furthermore, a suction belt 45 arranged to move along a closed trajectory 46 comprising suction portion 44. More in detail, suction belt 45 provides at least one through hole 47, arranged to be positioned at a respective suction groove 43 for causing a suction on web 5, or sheet 11, and for transferring it from a first point P1 to a second point P2 of a paper converting machine 1 (
Suction belt 45 is, generally, equipped with a predetermined number of rows of through holes 47. For example, in the embodiment of
In general, however, suction belt 45 can provide at least a first and a second suction hole 47 and 47′ positioned at a predetermined distance from each other, and arranged to selectively cause a suction effect on web 5, or the sheet of paper 11 (
In the alternative embodiment of
In
As shown in detail, for example in
More precisely, the plurality of teeth 55 of belt 45 is arranged to engage with a corresponding plurality of recesses 53 made on lateral surface 42 of support 41. Analogously, each recess 56 of belt 45 is arranged to engage with a corresponding protrusion 52 of lateral surface 42 of support 41.
As shown in
In the example of
As diagrammatically shown in
As shown in detail in
In the alternative embodiment of
The first and the second suction group define on the surface 42, respective different, but partially overlapped to each other, suction portions 44′ and 44 (
In the case shown, for simplicity, in
In
With reference to
More in detail, as well known, the folding, or interfolding, section 40, is arranged for folding, or interfolding, a web of paper 5, or a plurality of sheets of paper 11, into a plurality of panels 12, according to a predetermined folding, or interfolding, configuration.
According to the invention, the folding, or interfolding, section, 40, in this case, comprises a first and a second support 41a and 41b facing each other at a central zone 140. With reference to what it is shown in
More precisely, the first and the second closed trajectory comprise, respectively, the above described suction portions 44a and 44b of the first and the second support 41a and 41b. More precisely, each suction belt 45a and 45b provides at least one through hole 47a and 47b which are arranged to be positioned at a respective suction groove 43a and 43b for causing a suction on the processed web 5, or on sheets 11.
The driving device 60 is arranged to move the belts 45a and 45b with respect to support 41a and 41b, respectively, in such a way that the through holes 47 of one, or the other, belt 45 are positioned at the central zone 140 shifted from each other. In this way, it is possible to cause a suction effect on the web, or the sheet, alternately, on the first, and on the second support 41a and 41b, for obtaining the desired folded or interfolded configuration.
As shown in the schematic representation of
Between the feeding section 10a and 10b and the folding, or interfolding, section, 40, a perforating section 20′a and 20′b (
More in detail, in the case of the cutting section 20a and 20b, the web of paper 5a and 5b is directly divided into a plurality of sheets 11.
Instead, in the case of the perforating section 20′a and 20′b, the web of paper 5a and 5b is perforated along the perforation lines. The perforated web 5′a and 5′b is, then, divided into sheets 11, in the transfer section 30a and 30b, which is positioned downstream of the perforating section 20′a and 20′b, in a known way and, therefore, not described in detail.
In the examples of
The foregoing description of specific exemplary embodiments 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 in various applications the specific exemplary embodiments without further research and without parting from the invention, and, then it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. 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 that is employed herein is for the purpose of description and not of limitation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102015000087107 | Dec 2015 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2016/057772 | 12/19/2016 | WO | 00 |
