A METHOD FOR PRODUCING GLUED REELS WITH TWO OR MORE PLIES AND RELATED MACHINERY

Technical field

The present invention refers to the technical field of the production of reels, preferably made of paper but also of other materials, such as non-woven fabric or materials obtained from plants, such as cotton.

In particular, the invention refers to a method and related device, which allows to produce reels, which tape is in the form of two or more plies glued each other in efficient and functional way.

Background art

The technique for producing paper mother reels has been known for a long time.

The equipment foresees the cellulose processing, which is mixed to water and other additives. Therefore, a tape is produced, passing along a drying section where it is subjected to warm air flows, in such a manner so as to leave said section substantially dried.

While leaving the drying section, the tape is rolled up to a mother reel, which is ready to be processed in the shape of napkin, interleaved towels, etc., depending on needs and on specific machineries which are not the object of the present invention. The reel (or more than one reel) is then mounted on aforementioned specific machineries (for example rewinders or interleaving machineries) and it is unwound along a processing path which leads to the final product.

It is often necessary to produce mother reels wherein the tape is practically formed by two or more overlapping plies and glued each other. For that purpose, the prior art foresees the coupling of two of more plies, which are unwound from their related mother reels and that overlap each other once the glue is sprayed. Therefore, a gluing section is foreseen where the glue distribution takes place and a further section wherein the two or more tape plies are overlapped each other, attaching together by means of the spread glue. Therefore, the exiting tape is a single glued tape formed by one or more plies. Finally, the tape obtained by gluing the aforementioned two or more plies is rolled up in a mother reel (defined Jumbo Roll in technical jargon), which is ready to be mounted and fed to specific machineries for paper processing and so for the production of interleaved towels, rolls, toilet paper, etc.

Over the prior art, the glue distribution for the production of mother reel of two or more plies can take place is various ways.

In a case, for example, the passage of at least one of the two tapes is foreseen in contact with a transverse rotatable roller which is wet with glue, as it is semi- immersed into a tank containing glue, for example. The roller rotates slowly, by drawing glue time by time. The ply transits along its path by brushing against the roller, thus soaking by glue along its diagonal length, corresponding to the span of the roller (i.e. its diagonal length) . In that way, along the processing path, such a ply in form of a tape is coupled to the other ply coming from the other mother reel and then attach together to form a single two-ply tape.

The main technical inconvenience with the use of a distribution roller is the impossibility to reach producing speed over 700 m/min. The whole system results in a strong productive limitation, as modern rewinders reach normally 1000-1200 m/min speed approximately. In addition, the lamination by means of a roller modifies the appearance of the final product. As a matter of fact, as the glue is spread uniformly onto plies, the two or more paper plies result finally less soft and dry to the touch and so hardly processable. Grooved rolls could be used for trying to minimize the problem, or using a regular embossing roller, but anyway the final appearance of the product would be modified in any case and showing visible strips or "small spots". In addition, it is important and also difficult, to adjust the paper tension conveniently, in order to make it brush the roller soaked by glue. This process is not so easy.

Therefore, it is not possible over the prior art to have a product with two or more glued plies with "smooth" and soft appearance and with technical features of homogeneous processing.

Another prior art foresees the use of fixed nozzles, which spray and nebulize glue during the passage of the unwinding roll. Nozzles, generally more than one, are arranged in a specific section of the machinery along it diagonal length, in such a manner so as to intercept and cover the diagonal length of the passing tape. The spraying nozzles are connected to a glue tank and they begin to spray while the paper tape is passing, thus soaking the passing ply along its whole diagonal length. The rest of the process is equal to the described one, that is the tape soaked by glue is attached to a second tape, thus creating a double-ply.

The same technique (both by means of roller and by means of spray nozzles) is obviously applied to the case of three or more plies.

A problem occurred with the use of simple fixed nozzles is that they lose glue drops in use, falling to the ground and thus creating dangerous puddles for the operators' safety. Accidents due to slipping are frequent. Moreover, glue stiffens as time passes by, ^' sticking to soles, thus making the whole environment dirty and resulting in being hardly cleanable. Another inconvenience concerns the nozzles which become easily obstructed by glue, thus spraying badly as time goes by and altering the product quality. They often get totally obstructed and their replacement or anyway a cleaning operation is necessary.

Therefore, it is clear that, although the use of fixed nozzles succeeds in solving the technical problem of a better distribution of the glue amount compared to the use of the roller, without modifying the final product appearance and allowing high processing speeds, nevertheless obstruction and dropping problems remain unsolved, as they cause many safety problems to the operators and the necessity of continuous checks and maintenance. Moreover, the spraying obtainable by spray nozzle creates a "fog" effect which must be limited to avoid glue dispersion into the surrounding environment at a distance from the dispersion point. Disclosure of the invention

It is therefore the aim of the present invention to provide an innovative method, and related machinery, which solves the aforementioned technical inconveniences.

In particular, the aim of the present invention is to provide a method, and related machinery, which allows to spread the glue on one or more paper plies to form the two-ply or more-ply tape, in such a manner that a homogeneous distribution occurs, thus avoiding areas with glue excess or areas without glue. At the same time, the aim of the present invention is to provide a method, and related machinery, which allows to obtain a paper tape with two or more paper plies with great qualities, that is soft and processable, even guaranteeing a good endurance between the two or more plies glued each other.

The aim of the present invention is also to provide a method, and related machinery, which minimizes the risk of malfunctioning of the means used to spread the glue and minimizes accidental loss due to drip, which may cause puddles .

These and other aims are therefore obtained through the present method for the production of a tape with two or more glued plies, according to claim 1.

Such a method comprises the following phases:

The feeding of at least a first ply (100, VI) in the form of a tape along a first processing path;

The feeding of at least a second ply (200, V2) in the form of a tape along a second processing path; - Distribution of the adhesive material (CI) on at least two plies along the processing path and subsequent overlapping of said two plies.

According to the invention, the distribution process of the adhesive material is now made through the rotation of at least one element of rotating distribution (3), to which said adhesive material is fed and which throws, by centrifugal force, a nebulization of said adhesive material .

In this way, all the aforementioned technical inconveniences are easily solved.

It has been surprisingly found that the use of a rotor which sprays the glue while rotating allows a homogeneous distribution, with drops of a correct size, such that the gluing proves to be efficient without altering the qualities of the product.

Moreover, the use of the aforementioned rotors minimizes the problem of the fogs, due to traditional nozzles and eliminating the obstruction problem that does not occur because of structure and operation of rotors.

Therefore, the production of paper or other material reels, for example in a rewinder machinery, can use such a technology in order to optimize the quality of the obtained final product.

According to the claim about the gluing section and machinery which includes said section, preferably a rewinder machinery, the same advantages occur.

Further advantages are inferable from the remaining dependent claims .

Brief description of drawings

Further features and advantages of the present method and relative machinery or section, according to the invention, will result to be clearer with the description that follows of some embodiments, made to illustrate but not to limit, with reference to the attached drawings, wherein :

Figure 1 outlines the centrifugal device 1, known in itself, used in the present invention and which is able to produce and cast a nebulization of adhesive material, generally an adhesive fluid, while figure 2 shows a possible known solution to produce a rotor 3 of such a centrifugal device for generating and casting the glue nebulization by means of its rotation;

- Figure 3 outlines a production line, to produce for example paper rolls or reels in a rewinder machinery, wherein a potential positioning example of the centrifugal devices (1, 1') is shown;

Figure 4 is a further schematization which highlights the passage of the paper tape in front of the centrifugal device 1;

Figure 5 shows the nebulized drops spread on a part of the tape;

- Figure 6 shows a solution wherein the used centrifugal device is connected to a system 50 for maintaining at a certain distance the paper tape, together with a system 60 for collecting the exceeding glue;

Figure 7 outlines a preferred positioning of the centrifugal device with respect to the passage of the tape- Figure 8 shows the system 50 for maintaining at a certain distance the paper tape of the paper in form of a holed rod 50, through which air under pressure is blown to maintain the tape separated from the centrifugal device;

Figure 9 and 10 show respectively the positioning of the centrifugal device in a production line of two and three plies.

Description of some preferred embodiments

Devices of the rotatable type have been known for a long time (i.e. centrifugal ones), suitable for nebulizing liquids/fluids thanks to centrifugal force.

Many kinds of this device exist and they are formed by rotors, rotating plates for example, which foresees a certain radial canalization.

They are connected to a feeding system of the fluid to be sprayed and, by means of suitable rotating means, are put in fast rotation, while the fluid feeds them. The fed fluid is throws by centrifugal force along said specifically shaped radial channels and it is sprayed and throw radially to a certain distance, that is for a certain distance and with a preset angular spacing. As an example, the publication US2009/0212128 is known, describing a plate which allows to spray and cast by centrifugal force a fluid to a certain distance.

Another solution example is published in EP0796622 which describes a centrifugal apparatus and related method to spread a treating fluid. Figure 2 in attachment shows the rotor used in EP0796622 specifically.

Provided that, fluids that are sprayed with such a kind of centrifugal device are always perfuming liquids, lotions or softeners, in such a manner that the finished product has better softness and/or perfuming features.

The aforementioned apparatuses are purchased by factories for paper production, in order to use them for spraying liquid perfuming solutions or conditioners exclusively.

The same publication EP0796622 specifies the use of the aforementioned apparatuses for casting treating liquid, such as conditioners.

Nowadays, it has been surprisingly tested and found that the use of the aforementioned rotating apparatuses is able to throw efficaciously also a fluid like glue, which has technical features, like viscosity, specific weight and its own gluing features which make it very different compared to treating liquids which are sprayed with the aforementioned centrifugal apparatuses.

Therefore, the implementation of the aforementioned centrifugal apparatuses as glue distributing system along the passage of paper not only allows to optimize the glue distribution but also, as explained further, allows to solve all the technical inconveniences of prior art, without causing obstructions due to glue in the rotating device, although it is specifically made for balsamic or perfuming lotions.

The technical expedient to replace the known apparatuses of glue distribution, such as roller or nozzles, with the aforementioned rotating device, allows to obtain an optimal glue distribution, thus optimizing the quality of the product with respect to results obtained by rollers, thus reducing the problems of dripping and mists. Therefore, it has been found that it is possible to adjust precisely the glue amount to spray and the nebulization with the use of the aforementioned apparatuses and, at the same time, the leakage by dripping are minimized, as well as the problems of nozzles obstructions .

Figure 1, as an example, describes a part of such an apparatus of the rotating type 1, wherein rotors 3 and flexible ducts 2 through which the fluid is fed, (glue in this case) are highlighted. Always figure 1 shows the openings 4 which lead to rotors and through which the nebulization is cast.

It has been found that a particularly functional model for that purposes is the system "WEKO RF COMPACT 3" - "ARTICLE 650445", produced by EKO.

As outlined in figure 1, such a model foresees a sequence of rotors 3, forming a line one next to the other and which lead to an opening through which the glue is throw and such an opening is re-closable through a shutter (S) (see for example figure 6) . In this way, at the end of use, the shutter (S) can be closed again automatically to avoid spurts and dropping of glue throughout the environment .

Therefore, this own expedient of the aforementioned model helps to reduce glue leakage throughout the environment .

The device 1, as shown in figure 4 or in figure 6, is placed to a certain distance from the paper tape passing horizontally according to the arrow direction of figure 6 downwards .

According to the invention, it has been surprisingly found that the distance between the paper tape and the rotor which casts the glue can be comprised preferably between 20mm and 25mm (even more preferably, ranges between 20mm and 23mm or between 20mm and 22mm are optimal) with an unwinding direction, and therefore of paper passage, from top downwards (see the arrow direction of figure 4 or figure 6) . As a matter of fact, in case of specific use of the aforementioned EKO device, the producer, as per figure 7, recommends a distance of 18mm with an unwinding of paper from bottom upstream with the help of a carter placed behind the paper. It has been found that such an arrangement creates many problems with fogs, dropping and motions, for this reason the above- mentioned ranges between 20mm and 25mm with the passage of paper from top downwards solve said problems, above all if the carter behind the paper itself is removed.

As a matter of fact, figure 4, highlights that the centrifugal device is not coupled to a carter to the opposite side of the tape.

The above-mentioned WEKO model is used, according to the invention, with a 2800 RPM speed, that is the rotating speed of rotors spraying the glue is fixed and not adjustable. Such a value is however optimal for obtaining correct spraying effects, eventually by increasing the flow rate and maintaining constant the rotation when the forward motion speed of the tape increases.

Moreover, the use of such a centrifugal system eliminates the risks of obstructions completely, as there are no fixed nozzles. At most, obstructions of filters can occur but they can be replaced also in use, thus allowing to wash the dirty one for its reuse.

Therefore, the preferred rotation speed of rotors is approximately 2800 RPM.

Such a speed is independent from the forward motion speed of the tape but, as already said, the flow rate can be varied, that is the glue feeding to said centrifugal device.

As alternative, it would be also possible to vary the speed. Therefore, a new version of centrifugal system is available, always produced by eko, allowing to vary the speed rotation of rotors.

This is possible thanks to a control panel which allows to modify Hertz, thus varying the rotation speed of rotors consequently.

The new system foresees the Hz variation in a range of 40 ÷ 60 Hz.

Low speed entails bigger and heavier drops.

As the rotating speed is increased, drops result in being smaller and lighter.

Therefore, the following settings would be possible:

- 40 Hz -> 2' 400 rpm;

- 50 Hz -> 3' 000 rpm;

- 60 Hz -> 3 '600 rpm

The new system allows to adjust these parameters by the control panel.

It is recommended to work preferably with 50 Hz, thus obtaining similar speeds to the model with fixed speed described above.

In theory, it would be useful to work with Hz comprised between 20 ÷ 80 Hz, in such a manner so as to vary the speed, in order to "pulverize" the glue depending on needs and depending on the paper speed.

Obviously, the flow rate of glue is adjusted by a pump which feds the glue toward the aforementioned apparatus 1. Therefore, if the production speed increases, so the forward motion speed of the tape increases and it is possible to operate by increasing the flow rate and/or varying the rotating speed of rotors, in such a manner so as to maintain the sprayed glue amount fixed per square centimeter.

However, if the available technology does not allow to vary the rotation speed of rotors, it is necessary to operate on the flow rate of the pump only.

Generally, the pump which feeds the centrifugal device is regulated on values ideal for balm. Therefore, the inverter which monitors the pump engine can be programmed in such a manner so as to allow to vary the pump speed depending on specific need, in the case of use of glue.

Moreover, in order to optimize the glue spraying, measuring valves with 1mm diameters, instead of measuring valves equipped with 0,54mm diameters, have been used, those valves can be customized upon request to the producer. In those types of well-known devices, the aforementioned Weko model in particular, a flexible tube 2 is foreseen, bringing the fluid to the rotor. The rotor, as already said, is rotatable around an axis. The flexible tube 2 is connected to a feeding duct, which is equipped with an adjusting valve, that is said adjusting valve (not represented in figure 1 for the sake of simplicity) . It has to be underlined that the 0,54mm diameter is a standard converting size. The need to increase the flow rate has led to such a selection of increased diameters, speeds of the current rewinder machineries permitting. Moreover, by using increased (heavier) bulks (types of paper) , adjusting valves of bigger sizes will be necessary.

Therefore, if the standard value 0,54 for conditioners was not used with the glue, the glue feeding would not be enough, while the optimal use of 1mm glue would be excessive in the case of conditioners.

Carrying on with the structural description of the invention, figure 3 outlines a production line (rewinder machinery) , wherein two paper tapes are glued each other, in such a manner so as to obtain a single two-ply tape which will form the two-ply mother roll. The arrangement of figure 3, as explained further, is for the production of three or more plies and it is to be highlighted that the other gluing sections have been omitted for the sake of simplicity.

Therefore, as shown in figure 3, a first mother roll 10 is highlighted, formed by a wound paper tape and from which such a tape 10 unwinds, which forms a first-ply of the tape. As outlined in the figure, such a ply of tape 100 is made pass in front of the centrifugal device 1, where the glue is sprayed along the horizontal length of the tape.

Figure 4 shows in details, as already said, the passage of paper in front of the apparatus 1.

A second ply of the paper tape is unwound equally from a second reel 20, following his processing path itself .

If a two-ply tape is produced, the glue is spread only on a side of a ply, attaching together the two plies subsequently. Instead, in the case of more plies, the glue is spread on a side of the first ply and on the opposite side of the subsequent ply (as in figure 3) .

For clarity purposes, figure 9 shows a machinery for the production of a glued two-ply tape, wherein only a centrifugal device is arranged, spraying on the side of a ply only, in such a manner that the glue layer (CI) is comprised between the two plies to glue them. Instead, in the case of three plies, as in figure 10, the glue is spread onto the side of the first ply (VI) which glues to the second one ( V2 ) and to the opposite side of the second ply (V2) which glues to the third one (V3) . The same sequence is repeated in the case of four or more plies, by spreading additional glue on the opposite side of the third ply which glue to the fourth one, etc. Then plies along the path are attached by gluing by overlapping one another as per prior art and then they are wound onto a single mother reel (see schematization in figures 9 and 10) .

According to such a technique, it is obvious that any number of plies (even three or more) can be spread with glue and then they are overlapped one another.

The used glue is preferably a traditional glue used in the specific technical field of "coverting paper". It is a polyvinyl alcohol based glue that must be used with certain dilutions, compatible with the centrifugal device. The dilution from 1:2 (two liters of water each liter of glue) to 1:10 (ten liters of water each liter of glue) range has proved to be optimal, depending on the glue supplier. The optimal dilution proves to be 1:5.

The bought glue has to be diluted, according to the aforementioned dilutions. To maintain its features, a continue agitation of the solution is necessary, as water and glue tend to separate themselves. Therefore, a preparation tank has been foreseen and it is placed close to the Weko machinery with an agitating system with a lower number of rotations than the preparation tub, to avoid the separation between glue and water. This second tank is linked to a feeding system, a pump for example, which feeds the diluted glue continuously, in such a manner so as to maintain the processing conditions stable.

Nevertheless, the use of different glues, already diluted with various dilution degrees, is not excluded.

In order to optimize the machinery, further expedients have been added.

One of these expedient concerns a blowing system 50 to distance the paper from the section which sprays the glue by means of the described centrifugal device (see figure 6) .

This is necessary as, even if glue is not supplied, the risk of contact of paper parts to the parts of the spraying device may occur, leading the paper to stick to it, as a result of residual glue. Even if the aforementioned Weko model is specifically used, foreseeing a closing shuttle which isolates rotors, the risk is still present, as other parts of the Weko machinery itself may be dirtied by glue. In particular, potential motions or loosening of paper tension may bring the product in contact with the glued parts. As a matter of fact, glue dirties the machinery body and if the paper touches the glue, it tears off while restarting: then it is necessary to clean the whole machinery with a waste of time, as glue and paper creates a mixture difficult to remove. Moreover, it is necessary to arrange the passage of paper again.

For that purpose, as shown in figure 6 and figure 8, a rod 50 has been added (simply made by a holed tube) , wherein pressurized air flows. Holes are directed properly and work as nozzles. The rod is arranged in such a manner that the air flow intercepts the paper tape diagonally. As the WEKO system begins to work, the air cast by nozzles maintains the paper distanced from the machinery itself. The air pressure range may be between 0,05 bar to 1 bar, with a found optimal value of 0,15 bar.

Generally, the air flow is continuous and is sent also during the normal operation of the machinery, that is while gluing. In this way, the air helps to conduct better the sprayed glue on the passing paper, thus allowing to obtain a double advantage. Moreover, air flows allow a more efficient gluing, because they prevent the dust from depositing onto the paper tape and the glue can have a better adherence on the paper itself.

According to the invention, a containing tank 60 has been integrated below said section which sprays glue by centrifugal force (outlined in figure 6) . As a matter of fact, hat centrifugal system are used for conditioners and a potential conditioner excess is absorbed by paper. Instead, a potential glue excess causes the paper to rip. The glue system used in the paper factory operates in an environment different from those one for such converting centrifugal devices. For example, there is more dust in the paper factory. If it is dispersed in the environment, the glue together with dust forms clumps which stick to the various parts of the machine, thus spoiling its operation. For this reason, the tank 60 collecting the exceeding glue has been integrated, placed below the centrifugal device. The position can be optimized by placing the tank slightly backward with respect to the rotor itself, in order to collect as much glue as possible, thus facilitating the further cleaning and the maintenance. Therefore, if glue is collected, it will be held in the tub, even forming clumps together with dust, without the risk of dirtying other parts of the machinery or even the paper under production.

Moreover, according to the invention, if a conditioner is used and it is sprayed onto rollers as paper has some defects (holes, rips or lacerations), no problems occur: the conditioner is reabsorbed by paper during the passage. Instead, in the case of glue, it is necessary to stop the supply, as the paper passing on the roller may cause the paper itself to rip, due to holes, as glue begins to stiffen. For that purpose, a controlling system has been integrated, in order to detect paper breakages or lacerations, such a technology is very well known in itself in the technical field of paper processing .

Ultrasound and optical sensors have been placed in suitable points upstream the gluing section (also different sensors may be used, such as for example inductive optimal sensors, in the case of dark paper colorations) . The aforementioned sensors are placed upstream the centrifugal device, along the unwinding path of the paper. Sensors are connected to the centrifugal device and, as they detect a hole or a laceration on paper, they send a signal for closing the shutter of the rotor, thus preventing the glue from being sprayed. The defective paper is removed by the operator, which lets an extra piece to the strips of "healthy" paper and starts again, making the shutter open from the panel. As alternative, sensors can block the glue supply and/or block the operation of the whole production line.

Finally, figure 5 shows the result obtained as the glue is sprayed onto a paper passing approximately 1200 meters per minute (extremely high speed) . The figure shows a uniform distribution of nebulized drops which lay on the part of the passing tape.

The preferred embodiment of the invention is destined for the paper production, preferably paper reels, but the interleaved towels production is not excluded.