Method and device for patching a fibre web

The invention relates to a method for patching a fibre web according to the preamble of claim 1.

The invention also relates to a device for patching a fibre web according to the preamble of claim 13.

It is known in the state of the art that the web manufactured on fibre web machines, such as paper and board machines, may have holes, which shall be patched before it causes problems in further processing or at least before customer rolls formed of the web are delivered to a customer. As known in the state of the art, the patching of a hole is usually performed manually with patching tape either such that the web is slowed to crawling speed or such that the web is stopped before patching. For this reason, holes are usually patched off-line, for example, in a rereeler, which is also one of the main uses of a rereeler, in a calender or a slitter- winder. Since the hole patching is performed either at crawling speed or when the device has been stopped, the hole patching process clearly lowers the production throughput / capacity of the device in question, in particular if there are a large number of holes, the device in question will easily become a bottleneck in the entire manufacturing line, thus limiting production.

With respect to the state of the art, reference may be made to JP publication 4354760 disclosing a method and a device for repairing a web. The publication describes an automatic hole patching device for a rereeler, wherein the positions of holes are detected automatically and patches are automatically affixed onto the holes. When a hole has been detected, the unwinding speed of the web is slowed down and the passage of the hole is further sensed and the hole is patched at crawling speed.

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With respect to the state of the art, reference may also be made to EP patent 0922139 describing an automatic defect/hole detection arrangement, which also enables patching directly for a paper or a coating machine. In the arrangement, patching is performed with spray glue, roll application, for example, using rapid- curing adhesive. A drawback in this kind of arrangement is contamination and the clogging of glue nozzles when glue dries in the nozzle.

An object of the invention is to eliminate or at least minimize the problems and drawbacks of the prior art arrangements described above.

An object of the invention is to provide a patching method and device allowing the patching of holes to be also performed automatically at a speed higher than crawling speed.

With a view to achieving the objectives described above as well as those coming out later, the method according to the invention is mainly characterized by what is stated in the characterizing part of claim 1.

The device according to the invention is in turn mainly characterized by what is stated in the characterizing part of claim 13.

In accordance with the invention, in the method and device for patching a web, at least one piece of tape is adhered to a web by means of an applicator roll. In ac- cordance with an advantageous embodiment of the invention, a backing roll is arranged on the other side of the web with respect to the applicator roll to form a patching nip between the patching tape applicator roll and its backing roll, which patching nip can be opened and closed according to the need for patching such that at least one roll is moved out of a position in contact with the web. The patch- ing tape is adhered to the patching tape applicator roll advantageously by means

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of an applicator device. The patching tape can also be adhered manually to the applicator roll.

In accordance with an advantageous embodiment of the invention, when applying the tape, the patching roll is brought into contact with the web by closing the patching nip, so that the piece/pieces of tape placed on the surface of the patching roll come into contact with the web and, upon coming out of the nip, the piece/pieces of tape adhere to the web and separate from the surface of the applicator roll.

The applicator roll used in connection with the invention is movable out of contact with the web/backing roll / into contact with the web/backing roll, so that the roll can be stopped when it is not in contact with the web, for applying tape / for cleaning the roll.

In accordance with an advantageous embodiment of the invention, at least one roll in the patching nip is a patching tape applicator roll, but the invention also encompasses embodiments in which the patching of the top and bottom sides of the web is arranged to take place in the same station, i.e. in the same patching nip, in which case both rolls of the patching nip are advantageously provided with a tape applicator device. The tape can also be adhered manually to either or both of the rolls.

In accordance with the invention, the application of the hole patching tape is per- formed based on information about the CD position and size of a hole supplied by a defect detector located upstream of the patching station in the running direction of the web, and based on the speed of the web.

The invention is suitable for use in connection with web finishing processes, ad- vantageously in connection with the reeling of a web, for example, in connection

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with a reel-up of a fibre web machine, so that at least one piece of tape is used for patching the web that is being passed onto a web roll, i.e. a machine roll.

The invention can be advantageously applied in the treatment of the web before it is wound up by means of a machine reel, on which the fibre web manufactured on a paper machine/board machine is reeled as a full-width web into machine rolls for further processing. The web is wound about a reeling drum, for example, a reel spool, either by means of surface winding in a reeling nip defined by a reeling cylinder and a growing web roll or by centre drive when the reeling drum is also provided with a drive. In accordance with an advantageous embodiment of the invention, tape is attached by means of a tape applicator device to a separate tape applicator roll, which is placed before the reeling cylinder of the reel-up and from which tape piece/pieces is/are adhered to a web roll that is being completed, i.e. to the web passed to a machine roll. The patching tape is applied in the cross direc- tion to the correct location either by moving the taping device in the cross direction to the correct area of the applicator roll, so that the applicator and backing rolls of the hole patching tape can be ordinary guide rolls or other similar rolls used in the manufacture of paper or narrower rolls (slightly broader than the patching tape) movable in the cross direction, so that the rolls' and the patching tape are moved to the area of the hole to be patched. When patching heavy fibre web grades, it is also possible to adhere the tape by means of web tension by arranging adequate web coverage over the applicator roll.

The tape piece/pieces is/are placed on the surface of the tape applicator roll lengthwise, crosswise or spirally and it/they can be placed in one or more areas of the web in the cross direction thereof depending on the shape, size and number of holes. The length of the tape piece and, thus, the cut-off point of the applicator device are adjusted according to information about the hole size.

In connection with the tape there can also be an openable protective surface layer that is removed to the side, for example, by suction or a blow jet in connection

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with patching. When patching is performed at low speed, a protective surface layer is not necessarily needed but, in that case, the application of tape shall be timed to the closing of the patching nip, which requires high accuracy and/or a slow web speed.

The side facing outwards in the patching tape used in connection with the invention must not be sticky in order that the tape shall not stick to other rolls or the like during the running of the web, or to the next layer when it is in a roll, the surface/coating of the applicator roll shall be such that the non-adhering side of the tape adheres to it, for example, the coating of the roll can be two-sided tape or the roll can be provided with suction or an equivalent adhesion means. Alternatively, one tape layer can be added to the tape, so that the lowermost protective tape adheres to the applicator roll, and the roll must be cleaned.

The adhesion to the web of the patching tape used in connection with the invention shall be greater than the adhesion between it and the tape arranged onto the surface of the patching roll. This can be accomplished by selection of an adhesive agent.

The adhesion of the patching tape used in connection with the invention shall in any case be sufficient in order that the tape shall not separate from the surface of the patching roll before it adheres to the web. The adhesion force of the tape (separation adhesion 180° Tesa test method jopma 002) to the web is advantageously greater than 0 N/cm ² but smaller than 2 N/cm ² , preferably 0.5 - 1.5 N/cm ² .

In accordance with an advantageous additional feature of the invention, the tape is pulpable, thus enabling the machine roll to be used as broke. One of this kind is, for example, the splicing tape known in itself and used in unwind stands. For ex- ample, packing tape is suitable as a possible tape to be placed on the surface of the patching roll.

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The invention provides a considerable number of advantages. When applying the method in accordance with the invention, the hole patching can also be performed automatically at a speed higher than crawling speed. The automatic hole patching accomplished by means of the invention speeds up the hole patching process, thus improving the production of the line. In addition, the proportion of manual work is reduced because the tape roll of the applicator device need be changed considerably less often than in case it had been necessary to patch holes manually. Moreover, the need for a rereeler is substantially reduced, thus allowing cost sav- ings to be achieved. In some concepts it may be possible to dispense with the rereeler altogether.

The invention can be applied in connection with modernizations of both new fibre web machines and old fibre web machines.

In the following, the invention will be described in greater detail with reference to the figures in the appended drawing, but the invention is by no means meant to be narrowly limited to the details of the figures.

Figure 1 is a schematic view of a hole patching arrangement applied in connection with a windup stand according to one embodiment of the invention.

Figure 2 is a schematic view of one tape structure used in connection with the invention on the surface of an applicator roll.

Figure 3 shows different alternatives for placing a piece of patching tape on the surface of an applicator roll.

In the figures and in the description concerning them, the same reference signs are used of parts corresponding to one another, unless otherwise stated.

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In the arrangement shown in Fig. 1 there is a web roll 11, i.e. a machine roll 11, that is being completed about a reeling drum 10. A reeling cylinder is designated by the reference numeral 13 and, for the purpose of making a turnup onto a fresh spool to produce the next web roll, a new reeling drum 12 has been transferred to a stand-by position in connection with the reeling cylinder 13. The arrows Sl and S2 indicate the direction of rotation of the machine roll 11 being completed and the direction of rotation of the reeling cylinder 13, and the running direction of a web W is indicated by the arrow SW. The web W is passed to the reeling cylinder 13 over a guide roll 14. A web patching device 20 is placed on the run of the web W before the guide roll 14. A hole detection device 30 located before the patching device 20 is arranged in connection with the web W. In this embodiment of the invention, the patching device 20 comprises a tape applicator device 21, a patching tape applicator roll 22 and a backing roll 23. The patching tape applicator roll 22 and the backing roll 23 define a patching nip between themselves when the applicator roll 22 has been moved against the backing roll 23, the web W running through the patching nip between them. The applicator roll 22 is movable from a stand-by position (the position shown in the figure) to a patching position, i.e. against the backing roll 23, as shown by the arrow S22. When the detection device 30 has detected a hole/holes in the web W, it transmits information about the size and position of the hole/holes to the tape applicator device 21. The tape applicator device 21 comprises a tape roll, from which a desired amount of patching tape is transferred to the desired location on the applicator roll 22. When the hole/holes arrive at the patching device 20, the applicator roll 22 is moved to the patching position, i.e. the patching nip is closed, and when the web W runs through the patching nip, the pieces of patching tape are transferred from the applicator roll 22 to the web W, to the area of the hole/holes. After that, the applicator roll 22 is moved back to the stand-by position close to the tape applicator device to await the next patching operation.

The patching tape is applied in the cross direction to the correct area either by moving the tape applicator device 21 in the cross direction to the correct location

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on the applicator roll 22, or the applicator and backing rolls 22, 23 of the hole patching tape can be ordinary guide rolls or other similar rolls used in the manufacture of paper or rolls that are narrower (slightly broader than the patching tape) and movable in the cross direction, in which case the rolls 22, 23 and the patching tape are moved to the area of the hole to be patched.

The embodiment shown in Fig. 1 illustrates a hole patching operation that takes place on one side of the web W. In the figure, the hole patching tape is transferred to the web from below, but the invention also encompasses embodiments in which the patching tape is transferred to the web from above, in which case the backing roll 23 is naturally located under the web, and the applicator roll and the tape applicator device are located above. The hole patching in accordance with the invention can also be arranged to take place on both sides of the web W, so that both rolls 22, 23 function as applicator rolls and a separate tape applicator device 21 is arranged in connection with both rolls. Hole detection can take place from above or below the web regardless of the embodiment.

As shown in Fig. 2, a piece of patching tape 31 is adhered to a surface 22A of the applicator roll 22 by means of the tape applicator device 21. The surface 22A of the applicator roll 22 has an adhesion that allows the patching tape 31 to be de- tachably adhered to it on its surface 3 IB, which does not comprise any adhesive agent, the adhesion being lower than the adhesion of the patching tape 31 to the web on its adhesive surface 3 IA. On the surface of the applicator roll there can be, for example, two-sided tape, which is adhered on one side thereof to the sur- face 22A of the applicator roll 22 and which, on the other side thereof, causes the patching tape 31 to adhere. The surface 22A of the applicator roll 22 can also be arranged by other means to be such that the patching tape 31 can be detachably adhered to it, for example, the applicator roll 22 can be provided with suction. The surface 31A facing towards the web W in the patching tape 31 is adhesive and the surface 3 IB facing away from the web W is not adhesive. On the surface 31A facing towards the web W in the patching tape 31 it is possible to arrange, when

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needed, a protective tape 32 that prevents the patching tape 31 from adhering before the patching operation. The protective tape 32 is removed from the surface 31A of the patching tape 31 before patching, for example, using suction or a blow jet, to the side to a position 32'.

Fig. 3 shows different alternatives for placing a piece of patching tape 31 on the surface 22A of the applicator roll 22. The pieces of patching tape 31 are provided with a protective tape 32, under which on the surface of the patching roll 22 there are patching tape pieces 31 placed at locations according to the size and shape of the holes that have been detected. The piece/pieces of tape 31 is/are placed on the surface of the tape applicator roll 22 lengthwise, crosswise or spirally, and it/they can be located in one or more areas of the web in the cross direction thereof depending on the shape, size and number of the holes.

The invention has been illustrated above in Fig. 1 in connection with a reel in which a reeling nip is formed between a reeling cylinder and a roll that is being wound. The method according to the invention can also be applied in reels in which, for example, a support fabric, for example, a belt, runs over a reeling cylinder through a reeling nip between the reeling cylinder and the roll that is being wound. The invention can also be applied in reels in which a reeling nip is formed between a support fabric, for example, a belt, and a roll that is being wound. It is also possible to apply the invention at another appropriate location in the treatment of the web before it is slit and wound into customer rolls.

Above, the invention has been described only with reference to some of its advantageous embodiments, but the invention is not by any means meant to be narrowly limited to the details of them.