EP4332035A1

EP4332035A1 - Production line and relative method for the production of interfolded product through mechanical folding rolls

Info

Publication number: EP4332035A1
Application number: EP23186738.3A
Authority: EP
Inventors: Maurizio Giannoni
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-08-30
Filing date: 2023-07-20
Publication date: 2024-03-06

Abstract

The present invention concerns a couple of counterrotating folding rolls (10, 20) for the formation of interfold sheets, each roll being provided, along a circumference thereof, with an alternated succession of grippers (P) and wedges (C);
In accordance with the invention, at least one wedge comprises a channel forming a sliding guide within which a cutting blade (M) is slidably arranged and wherein extraction/retraction means (50) of said blade configured to control an extraction/retraction of the blade from/into said channel are comprised.

Description

Scope of the invention

The present invention refers to the technical sector of the production of sheet material of the interfolded type such as handkerchiefs, towels, etc., for example in paper material or non-woven fabric and possibly other sheet materials such as also metal material like for example aluminium.
In particular the invention refers to an innovative plant and relative method for producing said interfolded sheet material.

Brief outline of the prior art

The production of interfolded type products, for example of a paper nature, in order to make handkerchiefs/towels for hands or face and/or hygienic products in general of various formats such as napkins etc. is known.
The production lines for the manufacture of these products have been known for a long time and include an unwinding station where the mother reel is installed. Depending on the product (single-ply or multi-ply) two or more mother reels can also be provided.
It is also possible to use a single mother reel with the web itself already with two or more plies.
The starting web that is unwound from such mother reels passes through various processing stations and then ends up inside folding rolls which generally, through vacuum or gripper systems, grasp the product folding it into a V, Z shape or with other folding shapes (e.g. W shape etc.).
Some examples of interfolding machine are reported in publications EP0982255 and EP2308786 .
EP0982255 describes a machine for obtaining an interfolded product in which two paper lanes (therefore two webs) are fed towards counter-rotating folding rolls, in particular two rolls that are tangent and counter-rotating to one another.
The folding rolls are rotatably arranged with their longitudinal axis of rotation which is parallel to the ground and this machine part, comprising the folding rolls, develops vertically. The paper lanes, in essence, come from above and are fed to the folding rolls that fold the paper, forming a stack of interfolded paper that develops and grows in vertical direction.
More in detail, the two paper lanes are two continuous webs that can for example come from two mother reels and pass through cutting rolls that form the succession of individual sheets. The sheets are then fed to the next folding rolls. One paper lane feeds the succession of sheets to one of the two folding rolls while the other paper lane feeds the other succession of sheets to the other folding roll. Between the folding rolls, the couples of sheets are therefore overlapped on each other which are also overlapped in an offset manner depending on the folded product to be obtained (for example V-, W-shaped, etc.).
The folding rolls are provided with suction holes to retain the paper and the suction, always active, is offset on the two rolls in such a way that depending on the rotated position of the roll, one time it is active on a zone of the right roll and one time it is active on a zone of the other roll (the left one) in such a way as to create the transport of the finished product towards the folding zone. In essence, one time the suction of the right roll is activated, which drags the two portions of overlapped sheets and then the other suction of the other roll is activated which generates the other fold.
These types of rolls are then generally provided with detachment fingers that are movable according to an alternating up-down motion and that favour the detachment of the paper from the folding roll.
In this way, a stack of interfolded product is formed on a rest plane that progressively lowers moving away from the folding rolls in order to create the space for the formation of the vertical stack of product.
This type of machine therefore develops vertically and exploits suction to generate a vacuum.
Another similar interfolding machine is known from publication EP2308786 in which the folding rolls are equally arranged according to their longitudinal axis of rotation parallel to the ground. Also in this case, the part of the machinery relative to the folding and to the formation of the interfolded stack develops vertically.
In accordance with this solution, folding rolls are used which provide grippers alternated with wedges. The rolls are counter-rotating and with such an arrangement that a wedge of one roll faces the gripper of the other roll. Along their circumference, therefore, a wedge and a gripper are arranged alternately equally-spaced according to a certain arc of circumference and to cover the entire circumference.
In this way, the two overlapped sheets will meet, alternately, a wedge on a roll that pushes the two overlapped sheets towards the gripper of the other roll that grasps the two sheets creating the fold on one side. Subsequently, the alternated fold is obtained on the other side as, during the rotation, the other roll will grasp the two overlapped sheets with its gripper while the wedge pushes them usually inside the gripper.
The gripper and wedge therefore replace the vacuum.
The stack being formed by the two folding rolls with grippers rests on a plane that slides downwards, that is, that moves away from the folding rolls moving towards the ground to create the space of formation of the vertical stack.
The interfolding machines currently on the market, however, are quite rigid and the realization of different folds, for example the passage from a single fold to a Multi-fold, requires a complex tooling.
For example, EP2308786 describes the realization of a V-interfolded product. The realization of different formats, such as Z, is difficult to implement.
In some cases it would even be necessary to replace at least the folding rolls as well as other parts of the machine but in these types of interfolding machines this is not possible or, in any case, it is structurally complex.
Moreover, on the current machines, it is not possible to produce products of different formats without the complete replacement of at least the folding rolls and of the cutting rolls.
Therefore, the current interfolding machines are rather rigid, that is, little flexible, since they do not allow to modify the product, that is, the sizes of the product and the type of fold in a simple way.
Indeed, in the case of interfolding machines that use vacuum in the folding rolls, there is a strong limitation on account of the impossibility of being able to work products that cannot be sucked by vacuum.
Last but not least, the current machines have large overall dimensions and high consumptions.

Summary of the invention

It is therefore an object of the present invention to provide an interfolding system, a production line, and relative method, which solves the above technical drawbacks.
In particular, it is an object of the present invention to provide a couple of innovative interfolding rolls, a production line comprising such a couple of rolls and relative method that allows to produce interfolded material with no need to use the vacuum and with the possibility of being able to produce different types of folds with the same machine in a simple way without requiring structural interventions.
In particular, it is also an object of the present invention to provide a couple of interfolding rolls, a production line and relative method that also allows a format change in a simple and economical way with respect to what is currently possible with the current machines.
It is also an object of the present invention to provide a couple of interfolding rolls, a production line and relative method that allows to reduce the sizes of the same production line while also greatly reducing the energy consumption.
It is therefore an object of the present invention to provide a machine that is flexible and versatile.
Still more particularly, the objects of the present invention are to provide a production line for interfolded material and relative production method which enables to:

Reduce energy consumptions compared to a standard line for the production of the interfolded product even by up to 70%;
Reduce the overall dimensions compared to the known lines even by up to 70%;
Flexibility in the production of different products that make it possible to realize products with two, three, four, five and n folds simply by varying the processing parameters from the control panel;
Flexibility also in the production in width of the format; in the current state of the art, in fact, there are dedicated lines for producing products of fixed width. In order to produce products with a width different from the initial one of the project, it is necessary to replace a large part of the components of a head.
Simplicity in maintenance activities.

These and other objects are therefore obtained with a couple of counter-rotating folding rolls (i.e. which in use one rotates in one direction and the other rotates in the opposite direction, i.e. for example one clockwise and the other anticlockwise) for the formation of interfolded sheets in accordance with claim 1.
In such a couple of folding rolls (10, 20), each roll is provided, along a circumference thereof, with an alternating succession of grippers (P) and wedges (C).
For example, according to a specific angular spacing that is repeated, there is provided a gripper which at said angular spacing is followed by a wedge which is then followed by a further gripper and which is followed by a further wedge, etc.
Any number of couples in succession of gripper - wedge, from a couple to two or more couples depending on the product it is wished to be obtained and the diameters of the rolls in use can be provided in succession.
Generally, preferably, the number of grippers and wedges is fixed by the possibility of folding the paper and therefore the minimum angle between one gripper and the next wedge is generally 45° (one can for example place four grippers and four wedges).
The diameter of the roll is determined by the "cut-off" (i.e. distance calculated on the circumference between one wedge and the other or one gripper and the other) and by the number of grippers and wedges.
In accordance with the invention, at least one wedge of each of said rolls comprises a channel forming a sliding guide within which a cutting blade (M) is slidably arranged.
Preferably all the wedges of at least one of said two rolls is shaped as indicated above, i.e. with the sliding guide and relative cutting blade (M).
For an optimal operation, even more preferably, all the wedges of both the two rolls are shaped as indicated above, i.e. with the sliding guide and relative cutting blade (M).
As also clarified below, the invention finds application where there is a pre-cutting line of the product, i.e. a line of consistent material interrupted by stretches without material.
Where in the product being formed there is the cutting line (or pre-cutting in other words) formed by consistent material and stretches without material, the blade of the wedge will make the neat cut of said cutting line (or pre-cutting in other words) with the neat separation of two successive sheets while, in other cases and always as better described below, in the absence of a cutting or pre-cutting line in other words, the blade (M) will be limited to a perforation without making a neat separation.
The configuration in which, therefore, all the wedges of both rolls are provided with said removable/retractable cutting blade in a synchronized manner with the rotation of the roll on which it is mounted is a preferred solution.
Also comprised are means (50) for extracting/retracting said blade which are configured to control an extraction/retraction of the blade from/into said channel.
In this way, the aforementioned technical problems are solved.
In particular, this technology can advantageously be used in production lines similar to those for the production of napkins, however, allowing to obtain an interfolded product with all the aforementioned advantages.
The napkin lines, if integrated with this couple of interfolding rolls, allow versatile production of an interfolded item.
In particular, the napkin line can be further integrated with upstream perforators and any dedicated separation systems.
The napkin lines are compact, consume little and develop mainly longitudinally, including the stacking part, with the aforementioned rolls that can be placed, as it is already in use in the production of napkins, on an interchangeable support buckle.
In this way flexibility and low consumptions are easily obtained.
Advantageously said extraction/retraction means can be synchronized with the rotation angle of the roll in such a way as to command the achievement of an extraction and/or retraction position of the blade as a function of the rotation angle occupied by the roll.
Advantageously said extraction/retraction means may comprise at least one cam.
Advantageously, all the wedges of both rolls comprise said cutting blade and the relative blade retraction extraction means.
In this way, each time the roll reaches a certain angular position the system controls the extraction and the subsequent retraction of the blade.
The extraction and the retraction therefore take place within a certain angular range once the specific angular position of the roll in question has been reached.
Advantageously said cutting blade can be made of elastic material, for example harmonic steel or technopolymer and/or the like.
This solution is advantageous in that the wedge is hinged in its seat so that it is rotatable (or floating in other words) around its fulcrum.
Its rotation is idle and it is floating within the limits of the two side walls of the seat where it is located.
The blade placed in its inside, if it has good qualities of flexibility, is able to control with its elastic flexion, and therefore with its return to the non-flexed position, the correct positioning of the wedge instant by instant.
In particular, from the fully extracted position to the return towards the retracted position, the flexibility of the blade allows a control of a precise position of the floating wedge.
It has been found that for these purposes, harmonic steel or technopolymer can be considered preferred construction materials.
Also described herein is the use of a couple of rolls according to one or more of the above-mentioned features for producing interfolded sheet material.
Also described herein is a machine for the production of interfolded product comprising:

At least one first feeding path for feeding at least one first web of material;
At least one second feeding path for feeding at least one second web of material;
A first perforating station (a) arranged along said first feeding path so as to be able to generate transverse pre-cutting lines (also called in an equivalent manner pre-cutting lines) on the web being fed;
A second perforating station (b) arranged along the second feeding path so as to be able to generate transverse pre-cutting lines (also called in an equivalent manner pre-cutting lines) on the web being fed;
In accordance with the invention, at least one couple of folding rolls having one or more of the aforementioned characteristics and arranged so as to be able to interfold the two entering webs is comprised.

In this way, as advantageously described above, where in the product being formed there is the pre-cutting line, formed by consistent material and stretches without material, the blade of the wedge will also make during the folding, at the same time, the neat cutting of said pre-cutting line with the neat separation of two successive sheets whereas, in the absence of a pre-cutting line, the blade (M), for how it is shaped, will be limited to a perforation without making a neat separation.
The blade therefore integrated in the wedge is cooperating with the pre-cutting line and is configured to neatly separate the pre-cutting line whereas, in the absence of a pre-cutting line, it is limited with its conformation to generating a perforation that in any case does not cause a separation between them of two successive web stretches.
Advantageously, between the perforating stations and said folding rolls there can be provided a pulling station (40) configured to overlap the two web lanes with each other and feed them to the folding rolls.
Advantageously, a removable support buckle (10) can be provided, within which said folding rolls are rotatably mounted, such that said support buckle (10) can be replaced with a different support buckle including a further couple of folding rolls.
Advantageously, the folding rolls can be arranged with their longitudinal axis of rotation (Z) which is orthogonal to the ground.
Advantageously, said extraction / retraction means of the cutting blade are synchronized to actuate the extraction of each blade relative to a wedge when said wedge is in the position in which it penetrates the gripper of the other opposing roll in the grasping step.
It is also an object of the present invention to provide a method for making interfolded sheet products, the method comprising the following steps:

Arrangement of a couple of folding rolls (20, 30) counter-rotating to one another and provided with an alternating succession of gripper (P) and wedge (C) in such a way that during their rotation a wedge of one roll faces, in the zone of tangency between them of the rolls, a gripper of the other roll and with the movable gripper between an opening position and a closing position;
Feeding at least one first continuous web of material towards said couple of folding rolls;
Feeding at least one second continuous web of material towards said couple of folding rolls;
Generation of transverse pre-cutting lines on both webs;
Overlap of said two entering webs to each other within said folding rolls;
Folding of the webs overlapped on each other for the formation of the interfold through the wedge that in the zone of tangency faces the gripper of the other roll thereby pushing the web inside the gripper that by closing grasps the web;
In accordance with said method, during the folding operation, in which the wedge pushes the overlapped webs inside the gripper, a neat cutting operation of the webs is provided through the extraction of a blade that protrudes from a channel present in the wedge thus intercepting and cutting along a previously made pre-cutting line.

Advantageously, in the two overlapped webs the transverse pre-cutting lines are staggered from each other and not overlapped.
Advantageously, each pre-cutting line defines at least one fold line of the continuous web.
Therefore, when the blade penetrates the fold line, it causes a neat cut of the web when said blade intercepts the pre-cut.
Otherwise, if the blade intercepts a fold line without pre-cut, the blade is not able to neatly cut the web.
Advantageously, first one roll and then the other alternatively cause the neat cut of the pre-cutting line through the extraction of the cutting blade in said step of making the fold.
As mentioned above, advantageously, the cutting blade (M) cuts neatly a web exclusively when it intercepts a pre-cutting line present in said web whereas it does not cut neatly the web that does not have, in the interception line with the blade (M), said pre-cutting line.
Advantageously, therefore, in the case of staggered pre-cutting lines between two overlapped webs, the cutting blade (M) cuts neatly the web it intercepts the pre-cutting line thereof and simply by punching the underlying web if the pre-cutting line is not present in the underlying web.
Generally, in fact, the pre-cutting lines are staggered between the two overlapped webs.
A further object of the present invention is the combined use of at least one cutting blade (M), slidably arranged in a seat of a wedge relative to an interfolding roll, and cooperating with transverse pre-cutting lines obtained according to a certain pitch (L) along two mutually overlapped webs of material.
In accordance with this use, the cutting blade (M) and the pre-cutting lines are configured in such a way that, in the folding step with the wedge pushing the webs inside a gripper of an opposing interfolding roll, the step of extraction of the cutting blade (M) takes place.
Advantageously the cutting blade penetrates along the fold line such that, if the fold line develops along the pre-cutting line then the cutting blade intercepts the pre-cut and generates a neat cut of the web.
In the case, instead, of a fold line being intercepted along which there is no pre-cutting line, then the cutting blade (M) is not able to make the neat cut of the web.
As mentioned above, the pre-cutting lines are staggered on the two overlapped webs, which is why the blade intercepting the cutting line cuts the web neatly while, simply, it punches the web in which the pre-cutting line is not present.
As mentioned, a cutting blade is preferably present for each wedge of the two interfolding rolls.
It is also an object of the present invention to provide an arrangement for a folding roll (10, 20) for the formation of interfolded sheets, the said arrangement comprising at least one gripper (P) and at least one wedge (C) to be applied, in use, to the folding roll according to a certain angular spacing and wherein said at least one wedge comprises a channel forming a sliding guide within which a cutting blade (M) is slidably arranged and wherein extraction/retraction means (50) of said cutting blade (M) configured to control an extraction/retraction of said cutting blade (M) from/into said channel are comprised .

Brief description of the drawings

Further characteristics and advantages of the present production line for single or multi-fold interfolded material and relative method, according to the invention, will become more evident with the following description of some embodiments thereof, made by way of non-limiting example, with reference to the attached drawings, in which:

Figure 1 and Figure 2 schematically show from above a production line in accordance with the invention;
Figure 3 and Figure 4 each show two web lanes (for example in paper) that are overlapped for the formation of the interfolded product and highlight the transverse cutting lines (also called in an equivalent manner pre-cutting lines); these cutting lines (or pre-cutting in other words) run precisely throughout the height of the web and are spaced apart by a distance (L) adjustable by the control panel;
Figure 5 shows the two counter-rotating folding rolls (20, 30) forming the stack of interfolded product;
Figure 6 shows a section highlighting the web cutting system incorporated in the wedge of the folding roll;
Figures 7A to 7H show the processing step of the folding rolls for the formation of the stack of interfolded product;
Figure 8 is an enlarged detail D relative to Figure 7D highlighting the extracted blade that makes the neat cut of the web;
Figure 9 is an example of a V-folded product;
Figure 10 shows in two different (front and side) views the buckle on which the folding rolls object of the invention are mounted and with the removable buckle;
Figure 11A takes up the example of Figure 3 showing the two web lanes (for example in paper) when they are overlapped on each other as they are entering the folding rolls. In this regard, the continuous web that is visible, as overlapped on the other, was represented with the pre-cutting lines made up of two cutting stretches interspersed with three stretches of intact material. The underlying web has been represented, in order to distinguish it, with pre-cutting lines always dashed but in the form of a sort of continuous punctuation that constitutes the pre-cutting line; as it can be noted all the pre-cutting lines are equally-spaced from each other at L/2 thereby, in this example, taking up Figure 3;
Figure 11B schematizes a non-limiting example of the cutting blade used in the wedge which, for example, may have one, two or more tips depending on the type of pre-cut made upstream; in this example case, three tips are highlighted assuming that the pre-cut leaves three stretches of consistent material and therefore with the three tips arranged in order to intercept and break the three consistent stretches; it is not excluded that the blade may for example have a single tip for example in the case in which the pre-cut leaves only one stretch of consistent material to be definitively broken during the folding step; the blade is placed in front of the two overlapped webs of Figure 11A and such tips (in the case of non-limiting example of Figure 11B with three tips) pierce, as described below, the two overlapped webs in order to break the pre-cutting lines.

Description of some preferred embodiments

In the present description, the term two panels denotes a single folded sheet with a single V-fold.
The fold line around which the sheet is folded forms in fact the two panels to the right and to the left of the fold line (see for example Figure 9).
A three-panel product will therefore imply in the area of the sheet the presence of two fold lines arranged parallel to each other at a certain distance from each other, whereas a four-panel product will imply three fold lines etc.
Figure 9, for the sake of clarity only, shows on a sheet the single fold line in the case of a simple V-shaped product.
The figure therefore shows frontally the opened sheet with the fold line forming the two panels and the same figure shows the folded sheet around the fold line with a view in which the sheet is arranged tilted to highlight its fold and the V shape.
As is well known, in the case of two fold lines one will have a Z-shaped product, in the case of three fold lines one will have a W-shaped product, etc.
The shape of the interfold is something that has been known for some time and is not the specific object of the present invention.
Furthermore, in the present description in an equivalent manner cutting or pre-cutting line means a transversal line obtained in the material (see for example Figure a3 or 4) in which consistent and intact material is followed by absence of material. The line thus obtained is therefore defined as a cutting line since in the production process, as clarified, it is the line along which subsequently in the folding phase the neat cut will take place with separation and, in an equivalent manner, it is also defined in this text in a simpler and clearer way as a pre-cutting line since, at the time it is made, there is no neat separation between the two stretches joined by said line, at least as long as a neat cut also of the consistent material will take place in the folding step. The terms cutting or pre-cutting line are therefore used interchangeably in the present description.
The production line (or machinery in other words) and the relative production method therefore allow to obtain single-fold (i.e. with a single fold line) or multi-fold (therefore with two or more fold lines) products in a flexible way.
In accordance with the invention, the machine for the production of an interfold in accordance with the invention is now described with reference to Figures 1 and 2.
In particular, in accordance with the invention, the folding rolls that are used can be, as to the arrangement, similar to those used in the field of napkin production.
In a preferred embodiment of the invention, therefore, they are arranged in a removable buckle 10 with axis of rotation that in use is arranged orthogonally to the ground (see Figure 1).
Figure 10 schematizes this arrangement of the rolls inside the buckle and that will be taken up later.
In this way, in accordance with the preferred configuration of the invention, the processing path of the webs for the formation of the interfold develops in accordance with a direction parallel to the ground, unlike the classic interfolding machine in which at least a part of the path (in particular the arrangement and the entry into the folding rolls) takes place in a vertical direction to the ground with a substantial development of the machine thus vertically.
However, a vertical arrangement like in the classic interfolding machines is not excluded.
Returning therefore to Figure 1 and Figure 2, these therefore show a schematization in accordance with the invention in which the production line is shown in a top view, in order to highlight such a preferred (but not essential) development of the machinery in a horizontal direction and therefore with the folding rolls rotating around an axis Z orthogonal to the ground, like in the classic napkin machines, making sure that the lane of the web is always substantially parallel to the ground from the entry to the exit but with the web arranged vertically with respect to the ground.
Figure 1 therefore shows the axis Z coming out of the plane and orthogonal to the ground (see also schematization of Figure 10).
The axis of rotation of the folding rolls (20, 30) is therefore an axis Z orthogonal to the ground and the rolls (20, 30) are arranged in the support buckle 10 (see also Figure 10).
Figure 1 or Figure 10 shows the axis Z of rotation of the two rolls (20, 30).
As shown in Figures 1 and 2, at least two independent web lanes (in any material, for example paper) are fed to said folding rolls, exactly as happens in the interfolding machines, for example with idle folding.
The two web lanes (e.g. in paper or in other materials) are shown in Figures 1 and 2 as "web lane 1" and "web lane 2".
Each web lane (for example in paper) therefore represents a continuous "web".
Each web, as clarified below, is processed by the folding rolls to obtain the single-fold (a classic V as per Figure 9) or multiple-fold (two or more folds) interfolded sheet.
Each web, and consequently each sheet, may in turn consist of a single ply or of several overlapped plies.
These two lanes of material web are therefore obtained by unwinding for example a single web from a mother reel exactly arranged as such in the napkin production line and by providing a cutting blade immediately downstream of the mother reel in such a way as to cut the web into two symmetrical halves along its longitudinal axis and obtain the two web lanes as schematized in Figure 1.
The cutting blade may be in the form, for example, of a rotating knife with counter-knife.
Thus a single web lane (as said with mono-ply or two or with more plies) can be cut into two independent web lanes through a knife in the form of for example a rotating blade.
The same technology allows a web to be cut for the formation of any number of paper lanes greater than two.
Alternatively, the two or more web lanes can come from two or more single reels (obviously as already mentioned mono-ply or two or more plies, for example in paper).
Obviously also in this case any number of paper lanes is obtainable by providing an equivalent number of mother reels.
A hybrid solution with the blade cutting the web and multiple mother reels is feasible to obtain any number of web lanes.
As can be note from Figure 1 and Figure 2, the web constituting each lane (the two-lane example is therefore not limiting) is arranged in such a way as to be with its two faces orthogonal to the ground (it is therefore cut with respect to the ground) in a configuration in which the two counter-rotating rolls are placed with their axis of rotation Z orthogonal to the ground.
Such an arrangement is typical, for example, in napkin production technology.
The structure of the machinery is symmetrical along its longitudinal axis of development shown in dotted line in Figure 1, whereby the part of first web lane is mirrored to the part of second web lane.
Returning therefore to Figure 1 and 2, there are therefore a first and a second couple of primary perforating rolls (110, 110'). As clarified below, they generate a pre-cutting line on the web as per Figure 3 or 4.
These first and second couples of rolls are rotatably arranged in a support buckle (a, b).
The first couple of primary perforating rolls (110, 110') intercepts the first web lane while the second couple of perforating rolls (110, 110') intercepts the second web lane.
The primary perforating rolls (of course both the first lane and second lane) make a transverse cutting line (or pre-cutting in other words, see Figure 3 or 4) through the formation of a succession of holes interspersed with intact material along the width of the web.
Figure 1 shows in fact with the numbering 110 the blade (generally a serrated blade to leave integral consistent material interspersed with absence of material) that engraves the web along its width forming the tear line.
Each couple of perforating rolls, more particularly, comprises a blade 110 and a counter-blade 110' such that the web that is trapped between blade and counter-blade is engraved according to a line that corresponds to the length of the blade and counter-blade and therefore, generally, with a pre-cutting line that runs throughout the transverse height of the web (see in this regard Figure 3 or 4).
At each rotation, the counter-blade 110' meets the blade 110 to make the cut with the succession of holes as per Figure 3 or 4.
This pre-cutting line therefore does not cause a separation of the web which remains essentially "continuous" even if "engraved" transversely.
By synchronizing the rotation speed of said primary perforating rolls with respect to the web feeding speed (therefore a synchronization that is also a function of the rotation speed of the folding rolls) they intercept the paper at a predetermined pitch that varies as a function of their rotation speed.
That is, more specifically, having set a web feeding speed, it is clear that the more said perforating rolls rotate quickly and the smaller the pitch (distance L) between one tear line and the next. The more the rolls turn at reduced speeds, the greater the distance between one tear line and the next.
By appropriately adjusting the rotation speed of said perforating rolls it is therefore possible to adjust the distance between the pre-cutting lines (compare for example Figure 3 and Figure 4).
The distance L between one pre-cutting line and the other identifies the width of the sheet, that is, of the finished product that is interfolded with another sheet again with width L. Clearly the sheet with width L is then folded to form the two or more panels in order to obtain the interfolded product.
The distance between two pre-cutting lines and defining the width L is generally called "cut-off".
For example, taking into account Figure 1 and Figure 3, the two couples of primary perforating rolls engrave the web with each complete turn of the roll obtaining a certain distance L between one perforating line and the next which varies as a function of the rotation speed of said perforating rolls. The faster these rotate, the smaller the distance "L" will be. The lower the rotation speed of these perforating rolls and the greater the distance "L" will be (compare for example Figure 3 with Figure 4).
Figure 3 shows the distance "L" between the perforating lines that cause the "length" of a sheet.
The rotation synchronization of the two couples of rolls (110, 110') can be different from one another, such that the perforating lines obtained on the two web lanes are not overlapped when the two lanes are overlapped on each other but, instead, are staggered by a certain distance (for example L/2).
Figure 3 shows in fact the perforating lines obtained in the two web lanes and both at a certain longitudinal distance L between them.
It should also be noted that, in accordance with Figure 3, the perforating lines obtained in the two web lanes are staggered by a certain distance between each other, i.e. they do not overlap perfectly.
In particular, the perforating line of the first web lane is located at a longitudinal distance (L/2) from the perforating line of the second web lane with a distance that can be adjusted by appropriately synchronizing the rotations of the two couples.
In this sense, as shown in Figure 11A, the two webs when overlapped do not have overlapped perforating lines (i.e. the pre-cuts) but rather spaced apart by L/2.
The same would apply for the case of Figure 4 in which the two overlapped webs do not have superimposing pre-cutting lines.
Adjustment can take place very easily from the special control panel of the machine.
The staggering, as per Figure 4, must be the size of the panel of the final product that it is wished to be made (for example Figure 4 shows L/3, hence the product being made will have three panels and therefore two fold lines, or Z-shaped product).
The measurement of L must always be a multiple of the distance between gripper and wedge of the interfolding roll, as will be clearer from the following.
All these parameters, as mentioned, can be easily controlled by the electronic control panel.
The operator can select the rotation speeds of the perforating rolls together with the feeding speed of the two webs in order to be able to adjust, according to the chosen values, the distance L and the possible staggering between the perforations in the two lanes.
As better described below, the pre-cutting line (or cutting line in other words) serves to keep the two webs intact to drag them as far as the folding rolls where they are folded as described below and where, in accordance with the invention, cutting occurs simultaneously along said cutting line.
In the folding step, in accordance with the invention and as described below, the neat cut takes place for the formation of the single folded sheet and therefore of the interfold.
Returning to Figures 1 and 2, pulling rolls 40 are then comprised (generally a mutually counter-rotating couple) whose function is to overlap and pull the two web lanes (as said preferably in paper material), in such a way as to feed the web obtained by superimposing the two web lanes towards the folding rolls (20, 30).

DETAILED DESCRIPTION OF FOLDING ROLLERS:

Continuing with the structural description of the invention, the web arrives at the folding rolls.
These folding rolls have the following characteristics:

They are preferably, but not necessarily, placed with the axis of rotation Z orthogonal to the ground (see for example Figure 10);
They are with gripper and wedge, such that around the circumference of each of them a gripper alternates to a wedge according to a certain angular spacing and such that, during their counter-rotation, the wedge present in one roll pushes the web into the grip of the gripper of the other roll in an alternating manner;
These two folding rolls are preferably arranged in a support buckle 10 which is preferably of an interchangeable type, in such a way as to easily allow the format change simply by replacing the buckle that fits the specific rolls (see for example Figure 10).
As immediately clarified below, each wedge of both rolls integrates a cutting blade (M) of the perforation, i.e. of the pre-cut, made upstream;
There is a blade extraction/retraction system, therefore a system that controls the movement of said blade, which is synchronized with the angular position occupied by the roll in question.

Figure 5 shows a detail of the two folding rolls.
The Figure therefore shows the two folding rolls (20, 30) and highlights how each folding roll includes on its periphery a gripper (P) that alternates with a wedge (C) according to a certain angular spacing that varies from project to project depending on the grippers that are inserted (for example, Figure 5 shows an arc of circumference of 60°).
Figure 5 therefore shows on the roll 20 the succession of gripper (P) alternated with wedge (C) and the same succession is present on the roll 30.
In the non-limiting example of Figure 5 there are three wedges and three grippers per roll and therefore the angular spacing between one gripper and the next wedge is 60°.
However, the arrangement between the two rolls is offset so that during their counter-rotation the wedge of one roll meets the gripper of the other roll at the point of contact (tangency point of the two rolls) or vice versa.
In this way the gripper grasps the web as the wedge tends to push the web inside the gripper which, by closing, grasps the web and while continuing its rotation causes the formation of the fold.
Thanks to a well-known cam system, the gripper, during the rotation of the roll, opens and closes in such a way as to open while approaching and going past the point of tangency to receive the paper from the wedge and subsequently to close grasping the web and making the fold thanks to the continuation of its rotation until the release of the web with the opening of the gripper.
With reference to Figure 5, it is highlighted that the alternation gripper-wedge causes the formation of the stack since one time one gripper is on the roll 30 that rotates and forms the fold to the right and thereafter, however, the other gripper comes into play on the other roll 20 that drags the grasped web to the left.
The grasping and release technique through gripper and wedge for the formation of the stack schematized in Figure 5 is absolutely known art and not specific object of the present invention. For this reason it is not further detailed here.
Having said all this, in accordance with the invention there is now provided a cutting system that cuts the web neatly along the cutting line (or pre-cutting line in other words) that was made previously upstream, that is, made before entry into the folding rolls and made in the stations (a, b) of Figure 1.
More specifically, as schematized in Figure 6, a portion of the two counter-rotating folding rolls is highlighted in the tangency zone in which the gripper (P) of a roll is opened to allow the penetration of the tip of the wedge (C).
The gripper (P) has an active grasping part (P1) in the form of an elongated leg (P1) integral with a rotating part (P2). The rotation of the rotating part (P2), for example through a cam system commanded by the position occupied by the roll itself during its rotation, moves (generally rotates) the leg (P1) between an opening position (that of Figure 6 in which the wedge can penetrate) and a closing position close to the wall of the seat where the gripper is arranged.
The wedge (C), in accordance with the invention, forms a longitudinal channel which, de facto, constitutes a sliding guide for a cutting blade (M).
The cutting blade is therefore guided along the channel of wedge between an extended position, in which it at least partly protrudes from the wedge, and a retracted position in which it is placed within the wedge.
The cutting blade is therefore synchronised with the grasping motion of the gripper in such a way as to be extracted at a precise moment when the wedge pushes the web into the gripper during the grasping step, in such a way as to make a neat cut at the same time as the web is being grasped.
Still Figure 6 shows a possible blade retraction extraction system 50 which may for example be in the form of a cam that moves the blade in its alternating motion of extraction from the wedge and/or retraction within the channel of the wedge.
For example, the cam can synchronize as a function of the angular position of the roll during its rotation.
In principle, the extraction of the blade can be commanded in a range of rotation angles of the roll from 0° to 14° considering 0° the position in which gripper and wedge are aligned as per Figure 7A at their point of tangency.
Starting from said tangency position, the subsequent steps of rotation in two degrees by two degrees highlight an extraction and retraction of the blade until the separation of the wedge from the gripper like in the final step of Figure 7H at 14°.
In particular, precisely at the angle of 6°, as per detail of Figure 7D and detail of Figure 8, the blade is fully extracted, preferably about 3 mm, which is inserted into a space between the gripper and the wall of the seat of the gripper against which the gripper then comes close.
Basically, the folding zone is perfectly located at the point of contact of the tangents of the rolls.
The gripper, near this point, is already open so as to accommodate the paper pushed by the wedge.
Inside the wedge there is the channel where the cutting blade transits. In the condition highlighted by Figure 6, the blade that is in the rest step (fully retracted) and its connection to the actuating bar can be seen.
The actuating bar is constrained to move radially through a cam.
The path of the cam is such that, after a 6° rotation of the roll (step 7D), the blade protrudes from the wedge, for example by about 3 mm. At that instant the paper is in the best condition to be processed, since the wedge is closed by the contact of the movable/fixed heads of the gripper.
This contact, at that instant, makes the paper integral with the reference system of the blade and then at the exit the blade finds a paper basically blocked.
Although the above processing angles may therefore vary, the best time for the cut through the protrusion of the blade is when the tip of the wedge is blocked between the mobile leg of the gripper and the fixed abutment, i.e. the position in which the web is blocked.
In accordance with what is described, this occurs at an angle of approximately 6° starting from an angle of 0° considered at the point of tangency, since for angles from 0° to 5° the gripper does not completely block the wedge. In the phase at 6° degrees the wedge is perfectly blocked after which in the other further degrees up to 14° the gripper is opened again.
This blocking of the paper is guaranteed by the phasing of the cam that commands the opening of the gripper.
The adjustment of the cam that adjusts the extraction of the blade would also allow, if desired, to modify the aforementioned optimal 6° angle.
The blade therefore performs a neat cut only when it intercepts the previously made pre-cut, as better clarified immediately below.
The schematization of Figure 11A takes up, as mentioned, the example of Figure 3 with the two continuous and pre-cut webs overlapped on each other and entering the folding rolls.
The arc of circumference between a pin and the next wedge, in a folding roll, represents the panel that it is wished to be obtained (in this case of size L/2) while the distance L is the overall width of the sheet product. Thus the example of Figure 3, and relative Figure 11A, show the realization of a V-shaped product while the example of Figure 4 shows the realization of a Z-shaped product.
Now, that said, the blade of one roll and alternatively then the one of the other roll act by cutting neatly the pre-cutting line they intercept thus separating the sheet from the continuous web at the same time as the interfolding operation.
The two webs are overlapped in an offset manner, which means, as said, that the cutting lines are not overlapped. This therefore implies that the blade must cut neatly, in order to achieve separation, only the sheet that is in front of it and that envisages the pre-cutting line and not the underlying sheet in which the cutting line is not present. The underlying, in fact, is cut by the other roll when the web is folded by the other roll in the opposite direction.
Actually, the pre-cutting lines always coincide indeed with a fold of the continuous web that is made according to the normal folding operation with a well-known wedge-gripper.
In essence, in all cases, each pre-cutting line is positioned in such a way that it is always grasped by a gripper and therefore represents a fold line.
Precisely because the pre-cutting lines are not overlapped on each other but offset, it is necessary that the neat cut occurs only for the pre-cutting line and thus not for the underlying sheet in which the pre-cutting line is staggered.
For this purpose, the blade can be made with tips, as for example schematized in a non-limiting way in Figure 11B (by way of example three tips). This implies that, for example, having a suitable pre-cutting line in the sheet, the tips penetrate the sheet they have right in front of them thereby cutting, during the folding step that folds at the cutting line, the consistent material of the pre-cutting line hence making the neat cut of the web and simply creating imperceptible perforating holes on the underlying continuous web that, in that folding zone, does not envisage any pre-cutting line (it is reminded that the fold lines are offset, see for example Figure 3 or 4). When the other roll then grasps and folds the two overlapped webs on the other side, then the fold will be folded at the other pre-cutting line relative to the sheet that was previously underlying and the other blade will intercept the other pre-cutting line of the sheet that was previously underlying, thereby making the neat cut and simply punching the other overlapped sheet that belongs to the continuous web. For example, this applies in the case of Figure 3.
If the pre-cutting line is for example such as to leave only a minimum stretch of consistent material which is sufficient anyway to make the web "continuous", then the blade (M) could for example advantageously be made with a single tip sufficient to break said consistent material and making a simple and single hole on the underlying sheet.
In any case, the person skilled in the art will be able to evaluate the best shape of the blade according to the pre-cutting line made.
In the example of Figure 4 what happens is similar.
In particular, the first fold generates the cut along the first pre-cutting line present on a web and simply by punching the underlying one (with piercing being also adjustable based on a maximum extraction of the blade). Then it follows the fold in the opposite direction in which the blade of the other roll, in this case of Figure 4, does not meet any cutting line since at 2/3 L no cutting line is present for both overlapped sheets (see Figure 4). In this case, therefore, a piercing of one or both of the webs simply occurs during folding without creating a neat cut, though, and then, in the third fold, the other pre-cutting line is neatly cut.
In this way, the sheets of the overlapped webs are folded and simultaneously separated forming the interfold.
In particular, according to the described method, a neat cut of each sheet is made during the interfolding operation with the neat cut along the previously made pre-cutting line.
Each pre-cutting line of a continuous web is a fold line.
The extraction/retraction means are such as to extract/retract the blade from the relative wedge each time each wedge reaches the point of tangency entering the relative gripper.
In the preferred configuration of the invention, therefore, all the wedges of all the rolls are provided with such a blade (M) whose extraction always takes place when the relative wedge penetrates the gripper at the point of tangency.
In the event that the blade, in its extraction motion, intercepts a pre-cutting line then it causes a neat cut while otherwise it causes a simple piercing while maintaining the web continuous, that is, not making any separation.
The shape of the blade is therefore related to the geometry of the pre-cut.
In all cases, therefore, the pre-cutting line can provide one, two, three or more consistent points of intact material such that relative one, two, three or more blade tips are sufficient to break the pre-cutting line generating a neat separation and simply punching the underlying web.
In this way, thanks to this solution with integrated cut, it is possible to be able to drag the two webs until the step of completion of the fold while making, once folded, a separation of the sheets.
The wedge, in all the rolls, is floating hinged but cannot be extracted. The blade being arranged in the channel of the wedge, in its extraction and retraction motion, controls the positioning thereof and therefore, during the retraction step, brings the wedge back into the rest position in abutment against the wall of its seat, as per Figure 6.
For this purpose, preferably but not necessarily, the blade is made of harmonic steel.

INTERCHANGEABLE HEAD:

According to a further aspect of the invention, the head where the two counter-rotating folding rolls are arranged is of the interchangeable type, such that it is possible to remove the head with the rolls integrally placed therein and replace the whole with a head having rolls with different diameter.
For example, sets of buckles can also be arranged with different rolls that can be exchanged, even with an automated exchange and coupling/uncoupling system.
For example, Figure 10 schematizes the buckle 10 with the two folding rolls 20 and 30.
The buckle is placed on a support structure 60 that emerges from the ground and connects to it interchangeably, therefore removably.
In this way the buckle 10 can easily be uncoupled from the support base 60 to replace the entire buckle with a further buckle already provided with other folding rolls of different format.
In this way, by modifying the folding rolls, it is possible to select rolls having different distance between gripper and wedge according to the needs thereby modifying the panel of the product to be made and/or modifying the diameter of the rolls which, depending on the number and arrangement of the grippers and wedges, can allow the formation of panels of different sizes.
The head turns out to be interchangeable through quick connection systems that allow easily to uncouple one head and replace it with another having different folding rolls, for example a grooved profile attachment.

EXIT ZONE:

As shown in Figures 1 and 2, a product exit zone is then provided in the form of a continuous stack of product.
The product slides on an exit table 60', as highlighted in Figure 1.
The exiting product is in the form of a product snake with the web of the snake placed vertically with respect to the rest plane and already separated, i.e. in which each sheet of the interfold is separated from the next one.
At this point, therefore, the product is ready to be separated into individual stacks to be packaged.

EXAMPLE OF OPERATION:

In use, the at least two web lanes are fed from upstream to downstream along the processing direction of the product, as per Figures 1 and 2, therefore starting from the stations (a, b) towards the interfolding zone and then exiting on the exit web 60' of the finished product.
Each lane passes through the stations (a, b) that create on each web the succession of pre-cutting lines spaced one pitch apart ("cut-off") from each other that determines the width L of the finished product and therefore of each sheet of the interfold.
The two overlapped webs enter the folding station and the transverse pre-cutting lines in the two overlapped sheets are offset with each other.
Each pre-cutting line corresponds to one fold line of the product.
The interfolding rolls, as per prior art, provide for interfolding with the wedge gripper mechanical system but, in accordance with the invention, each fold corresponds to a protrusion of the cutting blade at the fold.
The cutting blade (M) is configured with a shape such as to cut the sheet it intercepts neatly if and only if, on this sheet, there is provided the pre-cutting line made in the previous station (a, b) and, otherwise, the blade is limited to making holes on the intact sheet in the absence of a cutting line.
The blade is therefore shaped as a function of the type of pre-cut in such a way as to cut neatly only the pre-cut present.
The blade and the pre-cutting lines, therefore, are related to each other with a blade that cuts the sheet neatly only if the blade penetrates at the pre-cutting line, thus breaking the few points (for example only one, two or three) of intact material relative to the cutting line.
With this technique, during the folding it is possible to cut the sheet which is thus separated and interfolded and at the exit a snake of product is obtained which is already interfolded and with each sheet separated from the others.
The product can thus be packaged in packages with a predetermined number of interfolded product.
The production line in accordance with the invention, by integrating a cutting system into the folding system, allows to compact the whole with lines of small size and therefore of small overall dimensions and consumptions.
The solution lends itself well to an integration in napkin lines with the rolls placed with axis of rotation Z orthogonal to the ground although this technology can be integrated into traditional interfolding machines.

Claims

A couple of folding rolls (10, 20) for the formation of interfolded sheets, each roll being provided, along a circumference thereof, with at least one gripper (P) followed by at least one wedge (C) according to a certain angular spacing;
- Characterized in that at least one wedge comprises a channel forming a sliding guide within which a cutting blade (M) is slidably arranged and wherein extraction/retraction means (50) of said cutting blade (M) configured to control an extraction/retraction of said cutting blade (M) from/into said channel are comprised.
The couple of folding rolls (10, 20) according to claim 1, wherein said extraction/retraction means are synchronized with the rotation angle of the roll in such a way as to command the achievement of an extraction and/or retraction position of the blade as a function of the rotation angle of the roll.
The couple of folding rolls (10, 20) according to claim 1 or 2, wherein said extraction/retraction means comprise at least one cam.
The couple of folding rolls (10, 20) according to one or more of the preceding claims, wherein each folding roll comprises around its circumference an alternating sequence gripper - wedge and wherein each gripper is spaced from the next wedge by a predetermined constant angular spacing.
The couple of folding rolls according to one or more of the preceding claims, wherein all the wedges of both rolls comprise said cutting blade and the relative blade retraction extraction means.
The couple of folding rolls (10, 20) according to one or more of the preceding claims, wherein said cutting blade is made of elastic material, for example harmonic steel or technopolymer and/or the like.
A machine for the production of interfolded product comprising:
- At least one first feeding path for feeding at least one first web of material;

- At least one second feeding path for feeding at least one second web of material;

- A first perforating station (a) arranged along said first feeding path so as to be able to generate transverse pre-cutting lines on the web being fed;

- A second perforating station (b) arranged along the second feeding path so as to be able to generate transverse pre-cutting lines on the web being fed;

- Characterized in that at least one couple of folding rolls is comprised according to one or more of the preceding claims 1 to 6 arranged so as to be able to interfold the two entering webs.
The machine according to claim 7, wherein between the perforating stations and said folding rolls there is provided a pulling station (40) configured to overlap the two web lanes on each other and feed them to the folding rolls.
The machine according to claim 7 or 8, wherein there is provided a removable support buckle (10) within which said folding rolls are rotatably mounted, such that said support buckle (10) can be replaced with a different support buckle including a further couple of folding rolls.
The machine according to one or more of the preceding claims from 7 to 9, wherein the folding rolls are arranged with their longitudinal axis of rotation (Z) which is orthogonal to the ground.
The machine according to one or more of the preceding claims from 7 to 10, wherein the extraction / retraction means of the cutting blade are synchronized to actuate the extraction of each blade relative to a wedge when said wedge is in the position in which it penetrates the relative gripper in the grasping step.
The machine according to one or more of the preceding claims from 7 to 11, wherein the cutting blade (M) has a geometry that is a function of the geometry of the blade present in the pre-cutting station (a, b) such that, in use, the cutting blade (M) cuts neatly exclusively the pre-cutting line generated in the web and is prevented from cutting neatly the intercepted web without pre-cutting.
A method for making interfolded sheet products, the method providing for the following steps:
- Arrangement of a couple of mutually counter-rotating folding rolls (20, 30) and each provided with an alternated succession gripper (P) - wedge (C) in such a way that during their rotation a wedge of one roll faces, in a zone of tangency between them of the rolls, a gripper of the other roll and with the gripper which is movable between an opening position and a closing position;

- Feeding at least one first continuous web of material towards said couple of folding rolls;

- Feeding at least one second continuous web of material towards said couple of folding rolls;

- Generation of transverse pre-cutting lines on both continuous webs;

- Overlap of said two entering webs to each other within said folding rolls;

- Folding of the webs overlapped on each other for the formation of the interfold through the wedge that in said zone of tangency faces the gripper of the other roll thereby pushing the web inside the gripper that by closing grasps the web;

- Characterized in that during the folding operation, in which the wedge pushes the overlapped webs inside the gripper, a neat cut of at least one of the two overlapped continuous webs takes place, through the extraction of a cutting blade (M) that protrudes from a channel present in the wedge, when said cutting blade (M) intercepts a previously made pre-cutting line.
The method according to claim 13, wherein in the two overlapped webs the transverse pre-cutting lines are staggered from each other and not overlapped, each pre-cutting line defining at least one fold line of the continuous web and wherein alternatively first one roll and then the other cause the neat cut of the pre-cutting line through the extraction of the cutting blade (M) in said step of making the fold.
The method according to claim 13 or 14, wherein the cutting blade (M) cuts neatly a web exclusively when it intercepts a pre-cutting line present in said web whereas it does not cut neatly the web that does not have, in the interception line with the blade (M), said pre-cutting line, preferably, in the case of staggered pre-cutting lines between two overlapped webs, the cutting blade (M) cutting neatly the web it intercepts the pre-cutting line thereof and simply punching the underlying web.