EP1314667B2 - Method for winding a paper or carton web - Google Patents

Description

The invention relates to a method for winding a paper or board web, wherein the web is heated immediately before winding to a temperature of at least 100 ° C and cooled again, wherein for heating a Breitnip used by a roller and a in a predetermined circumferential portion against the roller pressed jacket is formed.

A device for winding a paper or board web is in WO 99/23305 A disclosed there, where it is to be improved by the use of a Breitnipkaladers the surface quality of the material web, without causing the volume of the material web is substantially reduced.

Paper or board webs, hereinafter referred to as "webs", must occasionally be wound up in the course of their manufacture, if the further processing can not be done in such a context that the web can pass through. In any case, the winding of the webs at the end of the manufacturing process is required so that the webs can be formed into manageable roles.

Paper or board webs should have as uniform as possible their properties over their width. This applies, for example, the thickness, but also the moisture. A web having a non-uniform moisture profile in the transverse direction, i. is wound up in a direction transverse to the running direction, may possibly be damaged during storage on the roll. For example, cracks or wrinkles may result.

Out US-A-6 076 281 For example, a section of a paper machine for surface treatment of a material web is known, wherein the material web is wound up after passing through a calender. Should cooling of the material web be necessary, it is possible to arrange different cooling devices between the calender and the Aufwikkeleinrichtung. As an example of a cooling device while a fan is called.

Out DE 199 41 336 A a device for drying a paper or board web is known in which the material web is guided together with at least one sieve by an extended nip. The nip is formed by a flexible endless band and a counter surface. The endless belt is supported by a shoe.

The endless belt is heated and the counter surface is cooled or the other way around.

The invention is based on the object, the Improve quality of bobbins.

The object is achieved in a method of the type mentioned above in that the web is covered on cooling on both sides until its temperature has dropped below 100 ° C.

The heating evaporates moisture contained in the web. The steam spreads evenly in the web. When the vapor then condenses again, a relatively even distribution of moisture in the transverse direction of the web has been achieved.

It is used to heat a nip. The wide nip has the advantage that the web can be treated with a relatively low pressure voltage application over a longer period. Even with a temperature that is only slightly above 100 ° C, you can then heat the web over its cross-section to the evaporation temperature of the moisture.

The wide-nip device has a cooling zone in which the web is covered on its two surfaces until its temperature has dropped below 100 ° C.

By the heater, the web is heated in the nip. The broad nip provides a relatively long treatment length for the web so that the web has a relatively long dwell time in the nip. In this residence time, the web is not only supplied heat, but also pressure. However, this pressure can remain relatively small. The heat supplied lowers the viscosity of the trapped liquid in the web. By the pressure acting substantially uniformly across the width of the web, the liquid can then be made uniform. This results in a moisture balance in the web in the transverse direction, i. to a relatively uniform moisture profile in the transverse direction. When winding, therefore, there is no longer the risk that moist areas that form, for example, in the axial center of the winding roll behave differently than dry areas at the edges. The moisture is distributed rather uniformly in the axial direction. The jacket can be designed in different ways. One possibility is the use of a relatively stiff shell, which is elastic enough to adapt to the curvature of the roll, but otherwise rotates virtually in the manner of a roller. This jacket can be provided with discs on the front side. Another possibility is the use of a less rigid band, which is guided via support rollers in one circulation, wherein the deflection rollers practically define a polygon. Such a band can also be relatively thin.

Although vaporization of the moisture in the web has the advantage that the vapor is relatively quickly and evenly distributed in the transverse direction of the web. However, there is the danger that the steam, when the web leaves the nip, emerges virtually abruptly from the surface of the web. Since the web has usually been smoothed before winding up, this sudden escape of the vapor, the so-called "flash evaporation", leads to a reduction in the smoothness. The web is torn open on its surface by the rapidly exiting steam. Since the long-nip device has a cooling zone in which the web is covered on its two surfaces until its temperature has dropped below 100 ° C, the vapor is now kept in the web until the web has cooled below 100 ° C that this danger no longer exists. The steam, which has been uniformly distributed in the broad nip in the transverse direction, can condense again in the cooling zone, so that the moisture is uniformly distributed in the transverse direction of the web.

The heater acts on the web at a temperature of more than 100 ° C. This will dampen the inside Vaporized. The steam can spread relatively quickly in the transverse direction, so that the moisture compensation in the transverse direction of the web can be done even faster. It is usually completed before the train leaves the nip. The heater acts in the broad nip on the web so that the web is not only heated at its surface, but over its entire cross section to a temperature of 100 ° C or more. This ensures that the moisture that is contained in the web in deeper layers, can evaporate.

The cooling zone may be arranged subsequent to the broad nip. This is a relatively simple embodiment, in which the broad nip with a heater on the one hand and the cooling device on the other hand can be connected in series.

In an alternative embodiment it can be provided that the cooling zone is formed in the nip. In this embodiment, there is no risk that steam may escape during the transition from the heating zone in the cooling zone. Rather, the cooling zone joins seamlessly with the heating zone.

Here, it is preferable that the roller has a thin surface layer of a thermally conductive material disposed on a heat-insulating layer, the heater acting on the roller from the outside. The thin surface layer of the thermally conductive material has only a limited heat absorption capacity. It is now possible to adjust this heat absorption capacity so that the heat transfer from the surface layer to the web is completed before the web has completely passed through the nip. As a constraint, it should only be noted here that the heat absorbed in the surface layer must be able to heat the web to a temperature of 100 ° C or more. This can be realized by the heater acting from outside on the roller. This heater can work, for example, inductively. Once a heat balance between the web and the surface layer has taken place, there is no further heating of the web more. Rather, the web begins to heat balance to colder boundary areas of the broad nip, for example, the jacket produce. Since the broad nip has a corresponding treatment length, it is thus possible to heat the web in a first subsection, which is, for example, the first half of the broad nip, and to cool it in a second subsection, which can for example make up the second half of the broad nip. At the end of the broad nip then the web is cooled to a temperature below 100 ° C, so that the previously evaporated liquid can condense again.

Preferably, a cooling device is arranged in the cooling zone. The cooling device accelerates the cooling of the web, so that it can be expected with increased security so that actually no more steam at the exit of the cooling zone the train can escape.

Preferably, the wide-nip device is arranged so close to the winding section, that the running time of the web from the wide-nip device for running on a winding is a maximum of 3.5 ms. In this short time, moisture exchange with the atmosphere is not or not possible to any appreciable extent, so that the uniformly transversely wetted web is actually wound up as well.

Preferably, a longitudinal cutting device is arranged between the wide-nip device and the winding section. The longitudinal cutting device divides the web into partial webs, which can then be wound up into separate winding rolls. Paper webs are currently produced with relatively large widths up to 10 m, which are no longer manageable for a later user. It therefore cuts in a conventional manner, the webs in narrower partial webs in the order of 0.8 to 3.8 m and then wound up these partial webs. By balancing the moisture in the web can then be relatively easy to ensure that all webs have the same quality in terms of moisture.

Fig. 1

eine erste Ausführungsform einer Rollenwikkelvorrichtung und

Fig. 2

eine zweite Ausführungsform.

The invention will be described in more detail below with reference to preferred embodiments in conjunction with the drawings. Herein show:

Fig. 1

a first embodiment of a Rollenwikkelvorrichtung and

Fig. 2

a second embodiment.

A device 1 for winding a paper or board web 2 to a winding roll 3 has a Wikkelabschnitt 4, in which the winding roll 3 is formed, and a feed section 5, the web 2 passes through before it enters the winding section 4.

The winding section 4 is formed in the present case as Doppeltragwalzenwickler, in which the winding roller 3 is located in a winding bed 6, which is formed by two support rollers 7, 8. The two support rollers 7, 8 each have a drive 9, 10. When the support rollers 7, 8 are rotated, they rotate the winding roller 3 with.

Before the winding section 4, a longitudinal cutting device 11 may be arranged with an upper blade 12 and a lower blade 13, which divides the web 2 in partial webs 2a, which are then wound to partial web rolls, which are axially adjacent to each other in the winding bed 6.

In the feed section 5, a wide-nip device 14 is arranged, which has a roller 15 with a heater 16 and a co-operating with the roller 15 jacket 17 which is pressed by means of a support shoe 18 against the circumference of the roller 15. The support shoe 18 has a pressure surface 19, the curvature of the curvature of the roller 15 is adapted. The jacket 17 is yielding, so that it can invest under the action of the support shoe 18 over a predetermined peripheral region of the circumference of the roller 15 and thereby forms a long nip 23. In the pressure surface 19 may not be provided in detail lubrication devices. For example, the pressure surface 19 may have a hydrostatic lubrication.

The heater 16 is shown only schematically. It can act both on the surface of the roller 15 and the roller 15 itself a heat transfer medium, for example, a hot liquid or a hot gas, perform. The heater 16 causes the roller 15 is heated, that is, has an elevated temperature. This temperature is preferably above 100 ° C. The hot roller 15 then forms a heating device which acts on the web 2 in the extended nip 23.

The jacket 17 is supported by schematically illustrated rollers 20, one roller of which may have a drive 21. The roller 15 may also have a drive 22. The jacket 17 therefore runs around in the manner of a roll jacket.

Since the shell 17 rests on a relatively large peripheral portion on the circumference of the roller 15, the web 2 takes a certain time to pass through the formed between the roller 15 and the shell 17 23 wide nip. This time, the treatment time is so great that the web 2 is heated not only on its surface to the temperature of the roller 15, but the heat introduced into the web propagates also in the interior of the web and causes the Web 2 is heated to a total of at least 100 ° C, ie also in their interior.

Heating the web to a temperature of 100 ° C or more will cause moisture in the web to evaporate. The vapor thus formed can not escape through the surface of the web 2 because both surfaces are included in the nip 23. The top is covered by the roller 15. The underside is covered by the jacket 17. The steam is therefore distributed in the transverse direction of the web (in Fig. 1 perpendicular to the plane of the drawing) evenly. A significant compressive stress in the extended nip 23 is not required for this purpose.

Behind the exit of the broad nip 23, a cooling zone 24 is arranged, in which the web 2 is covered on both sides by vapor-impermeable belts 25, 26. The belts 25, 26 are hereby guided over deflecting rollers 27, which are shown only schematically. A cooling device 28 acts on the upper belt 25. The vapor-impermeable belts 25, 26 prevent steam from escaping from the surfaces of the web 2. The cooling device 28 leads to a lowering of the temperature of the web 2 below the value of 100 ° C. The vapor which has been uniformly distributed in the web 2 in the transverse direction can then condense, resulting in a very even moisture distribution in the transverse direction of the web 2.

The web 2 is wound up almost immediately after cooling, i. There is basically no time available in which a balance of moisture to the ambient atmosphere could take place. The time between leaving the broad-nip device 14 and running on the winding roll 3 is a maximum of 3.5 ms.

Fig. 2 shows a modified embodiment in which the same characters are provided with the same reference numerals.

This is in the present embodiment designed as a support roller winder, in the partial web rolls 3a, 3b, which have their own drive 29a, 29b, alternately rest on both sides of a support roller 30, which also has a drive 31. Since back-up roller winders are known per se, a more detailed explanation is dispensed with.

In the feed section 5, in turn, a wide-nip device 14 is arranged, in which the roller 15 has a somewhat different structure. The roller 15 has on a carrier body 32 on a thermal insulating layer 33 made of plastic. The outside of the insulating layer 33 is covered by a relatively thin layer 34 of a thermally conductive material, such as steel. The steel has the advantage that on the one hand it provides a relatively smooth surface, but on the other hand provides only a relatively low heat capacity.

On the layer 34, the heater 16 acts from the outside. The heater 16 is in this case arranged just before the nip.

The heat capacity of the layer 34 is now matched to the heat absorption capacity and the speed of the web 2 that a heat transfer from the layer 34 to the web 2 is completed in about half of the wide nip 23. This notional boundary 35 is shown by a dashed line.

The support shoe 18 has, at least on the winding section 4 facing side of the boundary 35 on a schematically illustrated cooling device 28, with the web 2 heat can be withdrawn through the jacket 17 therethrough. In the first half of the wide nip 23 Therefore, the web 2 is heated in such a way that it has a total of, ie, in the interior, a temperature of 100 ° C or more. In the second half of the nip 23, the web 2 is then cooled so that it has a temperature below 100 ° C at the exit of the broad nip.

The effect is the same as in the embodiment after Fig. 1 , By heating the web 2, the liquid in the interior of the web can evaporate. The steam spreads evenly. If the steam then in the cooling zone, which in the embodiment according to Fig. 2 is arranged in the right half of the wide nip 23, condensed, then results in a uniform distribution of moisture in the transverse direction of the web.

Claims (1)

1. Device for winding up a web of paper or card, where immediately before the winding up the web (2) is heated to a temperature of at least 100°C and then cooled, where the heating is achieved by a broad-nip (23) formed by a roll (15) and a jacket (17) which is pressed to a pre-determined peripheral extent against the roll (15) characterized in that the web (2) is covered on both sides when cooling until its temperature has dropped below 100°C.

Images