FI110256B - Method of cutting edge strips of a continuous web - Google Patents

Description

110256

Method for Cutting the Edge of a Continuous Strip Förfarande för att skära kantband av en kontinuerlig bana 5

The present invention relates to paper machines or the like. More particularly, the invention relates to a method for cutting a continuous web, such as a paper web or the like, to allow the web to be wound.

10 In order to protect the coatings of the paper machine calender rolls, the paper machine runs an over-wide web relative to the nip width of the calender rolls so that the calender's thermal rollers and the polymer rolls are never in contact.

After the calender, the non-calendered edge strip 15 left outside the nip before the web is rolled is cut off from the web, because the thicker edge than the rest of the web makes it impossible to roll.

Blade cutters have traditionally been used for edge band cutting, the main problems of which are blade wear and web breakage sensitivity, especially when starting and finishing the cut 20 easily cause web breaks. To reduce these problems, high pressure water jet cutting equipment has been developed. Such * · '· water jet cutting devices are functional but have problems with nozzle wear,

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high cost and short lifetime of high pressure pumps and dirt on the web cutting board;

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The object of the present invention is to eliminate or at least reduce the known web. edge strip cutting problems and thereby provide an improved web edge • ·, · · ·. nanofiber cutting method.

This objective is achieved by the method mentioned at the beginning, which is characterized by special features. are disclosed in the appended claims.

• 110256

Thus, the invention is based on the new and inventive basic idea that the edge band is cut periodically using an optional water jet, or laser or blade, so that the web is wound around the winding core periodically only at a length corresponding to the number of revolutions.

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Preferably, the web is periodically cut with a water jet, laser or blade at a distance corresponding to at least a percentage of the difference between the thickness of the web and the web.

Among the advantages of the invention, it can be mentioned that intermittent water jet cutting does not cause an interruption when starting or stopping 10, so that the cutting can be easily accomplished in cycles such as cutting 10% of the time or length of the web and 90% of the time or length. Further advantages can be noted as follows. For example, when cutting 20% of the time or edge band, the lifetime of high pressure pumps and nozzles is about five times higher, water and energy consumption drops to one fifth and the table can easily be followed by 15 automatic cleaning.

The invention will now be described with reference to a preferred embodiment thereof, wherein the edge strip is cut by a water jet.

20 For many paper grades, polishing results in temperatures up to 200-250 ° C.

M t '· · · * Thus, the polishing of the web is traditionally performed in a nip between a soft roll and a metal chuck roll by heating the metal roll, for example, with hot oil or induction. tiolämmityksellä. The typical running temperature of the chuck roll is about 150 ° C, even above 200 ° C, and the web temperature after the nip, respectively, is about 50 ° C. The ends of the soft roll casing become warm, •• .25, especially when using thin web materials, because the rolls are almost in contact with each other. In this case, the roll surface is easily damaged because ....: most elastomers used as soft roll surface have a maximum temperature of only 80-90 ° C. Typical soft calendars have soft hardness coatings for soft rolls ranging from 20P & J to 93 Shore D and modulus of elasticity from 500 MPa to 4000 [mu] m. The softest coatings are used in processes where light calendering is sufficient and paper swarms are minimized (eg folding boxboard). Co- 3 110256! with the latest coatings, the paper can be considerably compacted. smoothness and gloss are achieved. Hard coatings also have better speed and line pressure resistance than soft ones. If the soft roll surface material is damaged, the damaged roll will also damage the edge of the web, especially when running on calender nip-width flaps or narrower web.

Typically, to protect coatings of a papermaking calender rolls, the papermaking machine runs an over-wide web relative to the nip width of the calender rolls to ensure that the calender thermo rolls and polymer rolls are never contacted and the polymer roll temperature is not elevated due to the thermo roll.

After calendering, to allow for winding, or after other treatment of the web, such as coating, where the web edge is exposed to mechanical stress, an edge strip, typically about 10-150 mm wide, is removed from the web. The detached edge strip 15 is either sucked under vacuum through the edge strip nozzle to the pulper, or the edge strip removal apparatus can be designed such that the cut edge strip is deflected out of the process by gravity.

According to the invention, the edge strip is cut periodically from the web, preferably by using a periodically cutting water jet for cutting the edge strip with which the reel core, '··· * so. of the reel, the web to be wound around is cut off periodically * · ”only for a length corresponding to the number of turns that it is possible to wind the web.

Thus, the ribbon-cut layers and the ribbon-strip are alternately formed on the machine reel; *; uncut layers.

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In a particularly preferred embodiment of the invention, the continuous web web is cut in a section. at war, the length of which, over the total length of the web to be rolled, represents at least a percentage of the difference between the thickness of the ribbon and the web, which can be calculated from the formula:; li [%]> [(dm-dr) / dr] x 100 where • · '. 30 li =% of the web cut in intervals dm = thickness of the ribbon. '' * Dr = thickness of the calendered web 4 110256

When driving according to the invention at full width, i. wider than the nipple, the track, the water jet trimmer can be in its home position, allowing cleaning of the clipboard also in the car | matrixed by suitable means, preferably utilizing the water jet of the water jet cutter itself.

The invention has been described above only by means of a preferred embodiment thereof. This, of course, was not intended to limit the invention and, as will be apparent to those skilled in the art, many alternative solutions and variations are possible within the scope of the new and inventive idea as defined in the appended claims. Thus, for example, laser cutting or blade cutting is also suitable instead of a water jet.

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Claims (4)

110256 A method for cutting a continuous web, such as a paper web or the like, to allow the web to be wound, characterized in that the edge web Lei-5 is intermittently coated with an optional water jet, or laser or blade such that the web is wound of the same length that the web strip can be wound. Method according to Claim 1, characterized in that the edge strip is cut at intervals of at least a percentage of the difference between the thickness of the edge strip and the web. Method according to claim 1 and / or 2, characterized in that the amount of the portion to be cut periodically from the web is calculated by the formula: li [%]> [(dm-dr) / dr] x 100, where li =% part dm = thickness of the ribbon dr = thickness of the calendered web 20 ···, A method according to claim 1, characterized in that, when running at full width, • 1 ·, ·,; i. wider than the nipple, the track, the water jet cutter is kept in its home position, and • · 5 that the cleaning of the clipboard is automated by utilizing a water jet • 1 1. “·, Water jet from the cutter. * »· • 1 • 'II ··· •» • · · »' • · 1 I · • · 110256 i j