Method and device

Abstract

The invention relates to a method and a corresponding device for producing or treating a fibrous web, in particular a paper or cardboard web, having the following steps: a) drying the fibrous web in a drying section, b) subsequently cooling at least one first side of the fibrous web by means of a convection cooling process, wherein the fibrous web has a temperature of 65 °C or less, in particular 50 °C or less, on at least the first side after the cooling process, c) applying steam onto at least the first side of the fibrous web, the temperature on the first side equaling at least 70 °C, preferably more than 80 °C or 90 °C, after the steam is applied, and d) treating the fibrous web in at least one calendering nip.

Description

[0001] The invention relates to a method for producing or treating a fibrous web according to claim 1 and a corresponding device according to claim 9.

[0002] During the production of fibrous webs, a variety of quality requirements are placed on the final product. For example, paper, board, or packaging webs require a sufficiently good surface smoothness to ensure good printability or stable application of coatings. For this purpose, one or more calender nips are typically used, in which the fibrous web is smoothed using pressure and heat.

[0003] On the other hand, these products also require comparatively high mechanical stability to enable safe processing and to provide the necessary strength to the finished product—e.g., packaging. This strength increases with the thickness of the fiber web.

[0004] It can be seen that these two objectives are contradictory in that improving smoothness through increased calendering is accompanied by a compression of the web and thus a reduction in strength.

[0005] The simplest way to increase the volume or thickness of the fibrous web would be to use more fiber material. Since fibers, especially pulp fibers, represent a significant cost factor, this is usually not feasible for economic reasons.

[0006] It would therefore be very advantageous to have a way to smooth the fibrous web in a way that preserves its volume.

[0007] For this purpose, European patent EP 2,682,520 B1 proposes cooling the fibrous web. For this purpose, a humidifier is arranged in conjunction with a cooling device to generate moisture evaporation from the fibrous web, resulting in a latent thermal cooling effect. The colder web is less easily deformed, so it is less compressed in the calender nip.

[0008] A disadvantage of the solution described in EP 2,682,520 B1, however, is that cooling the web makes smoothing more difficult. In extreme cases, it is conceivable that, to achieve the desired smoothness, the calender load would have to be increased to such an extent that the stability advantage gained through cooling would be completely or partially lost.

[0009] The documents DE 298 13 663 U1 and WO 2018 / 141727 A1 also show corresponding processes.

[0010] It is therefore an object of the present invention to further develop the prior art in such a way that a simple smoothing of the web is possible while largely preserving the thickness.

[0011] It is a further object of the invention to enable volume-preserving smoothing using simple and cost-effective means.

[0012] The objects are fully achieved by a method according to claim 1 and a device according to claim 9. Further advantageous embodiments of the present invention can be found in the subclaims. For clarification:

[0013] Unless explicitly stated otherwise, the terms ‘fibrous web’ and ‘web’ are used synonymously below.

[0014] The term "convection cooling" is used below. For the purposes of this application, convection cooling refers to cooling by means of an air flow. Both passive and active cooling are conceivable.

[0015] In passive cooling, the fiber web is cooled by passing it through the ambient air over a certain distance, either freely or occasionally with the support of rollers. This form of cooling is inexpensive, but the cooling effect is rather low, and passive cooling requires a comparatively large amount of space to achieve a sufficient cooling effect.

[0016] With active cooling, air is blown from suitable nozzles onto one or both sides of the web. While an active convection cooler requires a higher investment than passive cooling, the cooling capacity is significantly higher and more precisely adjustable, and the system can be designed much more compactly.

[0017] With regard to the method, the object is achieved by a method according to claim 1.

[0018] After drying the fibrous web in step a), the fibrous web is very hot. Temperatures of up to 120°C are possible; temperatures of 60°C and below are almost never measured directly after the drying section. Values between 70°C and 110°C are common, especially 80°C, 90°C, or 100°C.

[0019] When leaving the drying section, the fibrous web can have a web moisture content of between 6% and 12%, in particular between 7% and 8%.

[0020] However, due to the high web temperature, the web is relatively soft, so that direct passage through a calendering nip would result in significant compression. Therefore, in the process presented here, the fibrous web is also cooled after the drying section.

[0021] In contrast to the prior art, the central idea of the present invention is a combined temperature gradient and moisture gradient smoothing process. The web, which is very hot and very dry after the drying section, is to be conditioned before entering the calendering nip in such a way that the web's interior is as cold and dry as possible, while at least its first side, or both sides, are moist and warm in the surface area.

[0022] The moist and warm surface is then sufficiently soft and malleable, allowing a good smoothness to be easily achieved in the calendering nip. However, since the core of the web is comparatively cold, compressibility in this area remains low, so that the thickness is largely maintained in the calendering nip. The moisture gradient, i.e., the fact that the web is also very dry on the inside as it enters the calendering nip, also helps maintain thickness. Furthermore, it is naturally advantageous not to add too much new moisture to the already dry web, as this would then have to be laboriously removed from the web after the calendering nip.

[0023] The necessary conditioning of the web is achieved through two surprisingly simple and inexpensive process steps.

[0024] First, the web is cooled by convection cooling after the drying section, at least on one side—preferably on both sides. Air cooling reduces the web temperature, and the web remains dry, unlike cooling by water application.

[0025] It is very advantageous if no moistening of the fibrous web takes place between leaving the drying section and cooling in step b).

[0026] The web is then exposed to steam on at least one side, or preferably both sides. The steam can also be a steam-air mixture. The steam condenses on the cool surface of the fibrous web, thereby both heating and moistening the surface. However, the interior of the web remains relatively cool and dry.

[0027] To enable effective steam condensation, a relatively low surface temperature of the fibrous web is important. The lower the temperature, the better, or rather, the more steam condenses on the surface, and the stronger the moisture or temperature gradient develops. Even if the web is very hot after the drying section, it is therefore recommended that the web, or rather the surface, be cooled to at least 65°C or below after convection cooling. In advantageous embodiments, the web is cooled to a temperature below 60°C, in particular below 55°C or below 50°C, and preferably below 45°C.

[0028] Applying steam to the web increases the surface temperature again. It is advantageous if the temperature of the fibrous web, at least on the first side after exposure to steam, is at least 70°C, preferably more than 80°C or 90°C.

[0029] This also increases the moisture content on the surface. After the steam condenses on the paper web, the surface moisture content can reach 15% or more.

[0030] With this temperature and moisture gradient, the fibrous web is then fed into a calendering nip where it is treated, particularly smoothed. As described above, the thickness of the web is largely retained during the smoothing process.

[0031] If only one-sided smoothing is desired, it may be sufficient to cool the web only on the first side. However, it will often be advantageous to cool the web on both sides.

[0032] Especially when smoothing the web on both sides, it is also advantageous to apply steam to both sides of the web. Cooling the web on both sides using convection cooling is also particularly advantageous in this case.

[0033] Since the temperature of the web slowly decreases again after steam application, and since the moisture content within the web equalizes over time, the passage through the calendering nip should not take place too long after steam application. The surface temperature of the first side of the fibrous web when entering the calendering nip should preferably be at least 60°C, in particular at least 70°C, preferably between 80°C and 90°C. To this end, it is advantageous if the distance between the end of the steam application and the calendering nip is no more than 1 m, in particular 80 cm or less or 50 cm or less. An even shorter distance of e.g. 30 cm or less would be desirable, but is often difficult to achieve due to structural constraints.

[0034] In particular, to achieve a good smoothing result, it is advantageous if the calendering nip is formed from a heated roller and a counter element, wherein the heated roller has a surface temperature of 220°C or more and comes into contact with the first side of the fibrous web.

[0035] Such heated rollers ("thermorollers") are typically heated using a heating fluid, especially an oil. To achieve the desired surface temperatures, it is advisable to supply the heating fluid to the heated roller at a temperature of at least 240°C, preferably between 260°C and 310°C. To achieve temperatures significantly above 310°C, special thermal oils are required. However, these are generally difficult to handle and usually toxic. A further advantage of the present invention is that the temperature and moisture gradients in the web allow for good smoothing without requiring extremely high temperatures at the heated roller, thus eliminating the need for these toxic special oils.

[0036] The effective surface temperatures that can be achieved with a heating fluid, especially with fluid temperatures up to 310°C, also depend on the amount of heat energy dissipated with the fibrous web. Generally, more heat is dissipated at higher line loads in the calendering nip and higher production speeds. To ensure sufficiently high surface temperatures on the heated roll even in such applications, it is advantageous for the heated roll to have a large diameter. The roll diameter can be over 1 m, and in particular 1.50 m or 1.60 m.

[0037] In most cases, surface temperatures above 200°C, especially above 220°C, can be achieved using the heating fluid. However, it may be difficult to achieve temperatures above 240°C.

[0038] Therefore, the heated roller can be additionally heated by a heating bar that is directed against the thermal roller from the outside and heats the roller by means of induction or a tempered air stream.

[0039] This allows the roller surface to be heated stably and reliably to temperatures above 220°C, preferably in the range between 230°C and 250°C.

[0040] The calendering nip can advantageously be operated with a maximum line load of 150 N / mm, especially less than 100 N / mm, preferably with a line load between 10 N / mm and 40 N / mm. Here, too, it has been shown that the temperature and moisture gradients in the web can achieve good smoothing even at low line loads. Reducing the line load also reduces web compression and thus thickness loss.

[0041] The fibrous web can, in principle, be any paper or cardboard web. In particular, it can be a cardboard web made up of two or more layers and having a basis weight between 100 g / m 2 and 600 g / m 2 , in particular between 150 g / m 2 and 450 g / m 2 . Such heavy and thick fibrous webs are particularly well suited for treatment according to one aspect of the present invention. In these webs, the coolness and dryness content are particularly well maintained due to the high thickness and large mass inside the web when the surface is heated and moistened by condensation of the steam. The moisture and temperature gradients are therefore particularly pronounced in these thick and heavy types.

[0042] The process can be carried out over a wide speed range. For example, the fibrous web can be moved at a speed between 600 m / min and 1600 m / min, in particular between 800 m / min and 1400 m / min. Passive convection cooling can be particularly advantageous at slower speeds of 800 m / min or less, as the distance required for cooling will not be too great due to the lower speed. However, at speeds of 800 m / min and higher, in particular, the provision of an active convection cooler is advantageous in order to avoid overly large installations. For this reason, it can also be advantageous to use the free space of an existing passive convection cooling system to install an active convection cooler, which can open up the possibility of higher operating speeds.

[0043] Paper or board machines typically have a press section upstream of the dryer section. In the press section, the fiber web is dewatered by mechanical pressing. The web is usually guided between two felts through one or more press nips.

[0044] For applications within the scope of the present invention, it has proven advantageous if at least the last press nip before the dryer section is designed as a wet press. The fibrous web runs through the press nip either supported only by a felt ("laying press") or completely without felt ("offset press"). Thus, in the press nip, at least one side of the fibrous web (or both sides, as in the offset press) has direct contact with the smooth press roll. It is particularly advantageous if at least the first side of the fibrous web has direct contact with the smooth press roll, to which steam is later applied. It has been shown that the provision of such a wet press can achieve smoothing that preserves volume, since the fibrous web emerges from the dryer section smoother and less smoothing is required in the calender.

[0045] Often, the wet press only achieves minimal dewatering of the web. The dry content, for example, increases by less than 2 percentage points, and especially by 1 percentage point or less.

[0046] To ensure a sufficiently dry fiber web after the press section, the fiber web can be dewatered before the wet press by at least one, preferably two, double-felted shoe presses. The wet press itself can be designed as a roller press or as a single-felted shoe press.

[0047] Alternatively or additionally, it can be provided that the calender has means for thickness calibration at the calendering nip in order to adjust the thickness of the fibrous web across the web width.

[0048] The calibration means can, for example, be thermal calibration. This involves applying a temperature profile across the width of a calender roll, the thermoroll or the counterroll, from the outside. Higher-temperature areas expand more, slightly increasing the radius of the roll at that point and thus increasing the pressure in the calendering nip. Thus, the temperature profile can be used to set a pressure profile in the calendering nip, which in turn influences the thickness profile of the fibrous web. However, thermal calibration has been shown to be less effective, particularly at comparatively high surface temperatures in the calender, for example, 220°C or more.

[0049] Therefore, especially at high surface temperatures in the calender, it can be advantageous to perform calibration using a so-called bend-adjusting roll. These rolls, marketed by the applicant under the name 'NipCo' roll, contain a series of punches inside the roll that can deform the roll shell in a targeted manner, thus setting a pressure profile.

[0050] The bending adjustment roller is usually not designed as a thermal roller.

[0051] A preferred calendering nip can then be constructed from a thermo roll and a bending adjustment roll as a counter roll.

[0052] With regard to the device, the object is achieved by a device according to claim 9.

[0053] In advantageous embodiments, it can be provided that the means for convection cooling are realized as passive cooling through a free section of the fibrous web, wherein the free section is at least 5 m, preferably at least 7 m, in particular 10 m or more long.

[0054] Alternatively or additionally, the means for convection cooling may comprise or consist of active cooling by at least one convection cooler, wherein the convection cooler is configured to blow air onto at least the first side, in particular onto both sides, of the fibrous web. Preferably, a certain free distance is provided before and / or after the convection cooler. However, this can then usually be designed according to the criteria of favorable web guidance and need not make a significant contribution to convection cooling.

[0055] Even if only one side of the web is to be smoothed, it can be advantageous to design the convection cooler so that air is blown onto both sides of the web. This leads to more efficient cooling of the web. Furthermore, more stable web travel can be achieved if air is blown onto both sides of the web simultaneously or at a very short distance.

[0056] Furthermore, such a convection cooler is very compact. Very effective cooling of the web can be achieved with a MD extension of between 1 and 2 meters, e.g., 1.5 meters. However, in challenging applications, e.g., with high web speeds and / or high web weights, the convection cooler can also have a MD extension of over 4 meters, especially up to 6 meters. In such applications, passive cooling is hardly feasible, as this would require an extremely long free path.

[0057] In principle, it is also possible to achieve the cooling effect using contact cooling instead of convection cooling. In this case, for example, one or more cooling cylinders can be provided instead of a convection cooler. The fibrous web can then be guided over these cooling cylinders so that one or both sides are in contact with the cooled cylinder surfaces. These cylinder surfaces can be cooled to temperatures below 40°C, especially below 30°C or 25°C. With this type of cooling, however, there is no material exchange and no penetration of the air boundary layer on the fibrous web. Therefore, the efficiency of this type of cooling is comparatively low. In addition, cooling cylinders require a comparatively large installation space and are relatively expensive. Therefore, convection cooling is preferred, especially for newly built plants.

[0058] However, it can be advantageous—for example, when converting a system that already includes a cooling cylinder—to combine convection cooling with contact cooling. Especially with passive cooling, additional contact cooling can be provided on one or both sides of the track before and / or after a free section.

[0059] In preferred embodiments, a convection cooler can have means for conditioning the air. Conditioning can be achieved by tempering, preferably by cooling, the air. Alternatively or additionally, conditioning can also be achieved by humidifying and / or dehumidifying the air. The effectiveness of the convection cooler can be significantly influenced by appropriate conditioning of the air blown onto the web.

[0060] Tests conducted by the applicant demonstrated that, when cooling with ambient air at temperatures between 30°C and 45°C, surface temperatures between 50°C and 65°C could be achieved. When the ambient air was cooled to temperatures below 30°C in the same test setups—in particular, to 25°C and below—surface temperatures of 50°C and below, in particular 45°C and below, could be achieved after the cooling device. Temperatures of 40°C are also possible.

[0061] Typically, a measuring device, such as a scanner, can be installed downstream of the calender. This makes it possible, for example, to measure properties of the fiber web, such as thickness or gloss. Using these measured values, it is then possible to control or regulate the quantity and / or temperature and / or moisture content of the air applied to the active convection cooler.

[0062] After the calender, especially after the scanner, the web can then be wound up. Alternatively, further process steps can also be planned after the calender. For example, one or more coating units can be provided.

[0063] It will often be provided that the calendering nip is formed from a heated roll and a counter element, wherein the heated roll can be heated to a surface temperature of 220°C or more and is arranged so that it comes into contact with the first side of the fibrous web. AMENDED SHEET

[0064] The counter element can advantageously be formed by a deflection compensation roller. This allows, for example, profiling of the calendering nip.

[0065] The diameter of the heated roller and / or the deflection compensation roller can each be between 400 mm and 1600 mm.

[0066] The diameters of the two rollers can be the same. However, the diameter of the deflection compensation roller can also deviate from the diameter of the heated roller by a maximum of 50%, preferably a maximum of 40%. In this case, the deflection compensation roller usually has a smaller diameter than the heated roller.

[0067] The calendering nip can be designed as a hard nip or a soft nip. One or both rolls of the calendering nip can, in particular, have a hardness of 60° ShoreD to 98° ShoreD, preferably between 88 and 92° ShoreD.

[0068] For example, one or both rolls of the calender can be composite rolls.

[0069] The calendering nip can consist of a roller nip. Alternatively, the calendering nip can also be an extended nip, such as in a shoe calender or a belt calender.

[0070] A second steam blow box can also be provided for applying steam to the second side of the fibrous web. When using an active convection cooler, this is advantageously located between the convection cooler and the calendering nip.

[0071] As already described in the context of the method, it is advantageous if the distance between the end of the steam application in the steam box and / or the second steam box and the calendering nip is no more than 1 m, in particular 80 cm or less or 50 cm or less. An even shorter distance of, for example, 30 cm or less would be desirable, but is often difficult to achieve due to structural constraints.

[0072] The invention is explained below with reference to figures. The invention is not limited to the embodiments shown in the figures. The figures show in detail: Figure 1shows a device according to one aspect of the present invention Figure 2 shows a device according to a further aspect of the present invention Figure 3 shows a convection cooler for use in a device according to a further aspect of the invention

[0073] Figure 1 shows an apparatus according to one aspect of the invention, which is suitable for carrying out a method according to the invention. A drying section 10 is provided in which a fibrous web 1, for example a paper or board web 1, is dried. The web 1 leaves the drying section 10 with a low residual moisture content of typically below 12%, e.g., 7% or 8%, and a high temperature, for example, between 75°C and 90°C.

[0074] For further processing of lane 1, Figure 1a calender 2 is provided. The calender 2 is shown here as an example as a roll calender 2, which has a heating roll 4 and a counter roll 5, which together form the calendering nip 3. The heating roll 4 can have a surface temperature of 220° C or more and is in contact with the first side 1a of the fibrous web 1. The counter roll 5 can be designed as a bending compensation roll. However, any other type of calender can also be provided, for example shoe or belt calenders, which have an extended calendering nip 3. Usually, a measuring device such as a scanner can be provided after the calender 2. After the calender 2, in particular after the scanner, the web 1 can then be wound up. Alternatively, it can also be provided that further process steps follow after the calender 2. For example, one or more coating units can also be provided.

[0075] In order to achieve the desired volume-preserving smoothing, means 6 for convection cooling of the web 1 are provided after the dryer section. In the design according to Figure 1 For this purpose, the web 1 is guided via guide rollers 8 to a convection cooler 6, in which it can be actively cooled. For this purpose, air is blown at least onto the first side 1a of the web 1, in particular onto both sides of the web 1. Even if only one side of the web 1 is to be smoothed, it can be advantageous to design the convection cooler 6 so that air is blown onto both sides of the web 1. On the one hand, this leads to more efficient cooling of the web 1. On the other hand, a more stable web run can be achieved if the web 1 is blown with air from both sides simultaneously or at a very short distance.

[0076] This air can be taken directly from the environment—for example, from a cooler area of the production facility such as the machine basement—or it can be conditioned before being applied to the fibrous web 1. Cooling the air, e.g., by means of a suitable heat exchanger, is particularly advantageous, as this can significantly improve the cooling effect of the convection cooler 6, so that a significantly lower web temperature can be achieved downstream of the convection cooler 6.

[0077] Following convection cooling, the web 1 is exposed to steam on at least the first side 1a. For this purpose, a steam blow box 7 is provided in the device shown. The steam is intended to condense on the web 1 and both humidify and heat the region near the surface. To allow the steam to condense as effectively as possible, it is advantageous if the web temperature after the convection cooling means or before entering the steam blow box is 50°C or less. With the active convection coolers 6, the temperature can be reduced even further, e.g., to 45°C or 40°C.

[0078] If both sides of the fibrous web 1 are to be treated, in particular smoothed, a second steam blow box can also be provided, which is arranged in such a way that it applies steam to the second side of the fibrous web.

[0079] After leaving the steam box 7, the web 1 exhibits, at least on the first side 1a, the temperature and moisture gradients desired to achieve volume-preserving smoothing. Since the fibrous web 1 tends to equalize such gradients over time, it is advantageous to guide the web 1 into the calendering nip 3 as quickly as possible after the steam box 7. Therefore, the steam box 7 is preferably arranged very shortly before the calendering nip 3, so that the distance between the steam box 7 and the calendering nip 7 is a maximum of 1000 mm, in particular a maximum of 500 mm.

[0080] The Figure 2 shown version differs from the one in Figure 1 merely by the design of the means for convection cooling. Instead of active cooling by a convection cooler 6, Figure 2the convection cooling is realized as passive cooling through a free section of the fibrous web 1. In order to improve the cooling of the web 1, it is advantageous if the free section is at least 5m, preferably at least 7m long. In order to achieve the longest possible free section, in the embodiment according to Figure 2 the web 1 between the dryer section 10 and the steam blow box 7 is redirected several times - e.g. twice, three times, four times or more - by guide rollers 8, so that even with a limited structural length of the device, a sufficient free distance can be provided for the cooling of the web 1.

[0081] Figure 3 shows schematically a section of a convection cooler 6 for the active cooling of the fibrous web 1, as it is used, for example, in an embodiment according to Figure 1can be used. Two rows of nozzles 61 are provided, each blowing an air stream 62 onto the fibrous web 1. The nozzles 61 in the upper row apply an air stream 62 to the first side 1a of the web 1, while the nozzles 61 in the lower row apply an air stream 62 to the second side. The nozzles 61 extend across the entire width of the web 1 (CD - Cross Direction) and are arranged one behind the other in the running direction (MD - Machine Direction). Figure 3 shows, by way of example, two or three nozzles 61 per row. In practical applications, however, there may be significantly more, e.g., 10, 12, 15, or more nozzles per row, in order to achieve the desired cooling of web 1. A distance in the MD direction can advantageously be provided between the nozzles 61 of each row. The distance, which may correspond in particular to the MD extension of a nozzle 61, allows for trouble-free discharge of the air stream 62 after it hits web 1.

[0082] Nevertheless, such a convection cooler 6 is very compact. Even with a MD extension of between 1 and 2 meters, e.g., 1.5 meters, excellent cooling of the track can be achieved. However, larger MD extensions of up to 4, 5, or 6 meters are also possible.

[0083] An active convection cooler 6 with two rows of nozzles, as shown here, has the advantage that the web 1 is cooled from both sides, which enables faster cooling. Furthermore, the web path of the web 1 is stabilized. By applying an air stream 62 to the first side 1a, the web deflects downward. The air streams 62 from the lower nozzles 61 counteract this and guide the web 1 back upward. Due to the alternating pushing and lifting, the web 1 runs in a slight undulating motion, but essentially stably and straight through the convection cooler 6.

[0084] The air for the air streams 62 can simply be ambient air, which in the vicinity of a paper machine typically has a temperature of 30°C or more and can also be quite humid. Alternatively, the air can also be conditioned, for example, cooled to 25°C or 20°C and, if necessary, dehumidified. List of reference symbols

[0085] 1Fibrous web 1aFirst side 2Calender 3Calendering nip 4Heating roll 5 10Counter roll 6Convection cooler 7Steam box 8Guide roll Dryer section 61 62Nozzle Air flow

Claims

1. Method for producing or treating a fibrous web (1), in particular a paper or board web (1), the fibrous web moving at a speed of between 600 m / min and 1600 m / min, comprising the following steps a. Drying the fibrous web (1) in a drying section (10) b. Subsequent cooling of at least a first side (1a) of the fibrous web (1) by means of convection cooling, the fibrous web (1) having a temperature of 65°C and less, in particular 50°C and less, on at least the first side (1a) after cooling. c. Application of steam to at least the first side (1a) of the fibrous web (1), wherein in particular the temperature at the first side after the steam application is at least 70°C, preferably more than 80°C or 90°C. d. Treatment of the fibrous web (1) in exactly one calendering nip (3), wherein the exactly one calendering nip (3) is formed from a heated roll (4) and a counter element (5) and wherein the distance between the end of the steam application and the calendering nip (3) is not more than 1 m2. The method according to claim 1, wherein the fibrous web (1) is smoothed by means of a wet press before the dryer section (10).

3. Method according to one of the preceding claims, wherein the surface temperature of the first side (1a) of the fibrous web (1) is at least 60°C, preferably between 80°C and 90°C, when it enters the calendering nip (3).

4. The method according to any one of the preceding claims, wherein the heated roller (4) has a surface temperature of 220°C or more and comes into contact with the first side (1a) of the fibrous web (1).

5. Method according to one of the preceding claims, wherein the heated roller (4) is heated by means of a heating fluid, wherein the heating fluid is supplied to the heated roller (4) at a temperature of at least 240°C, preferably between 260°C and 310°C.

6. Method according to one of the preceding claims, wherein the at least one calendering nip (3) is operated with a line load of at most 150 N / mm, preferably with a line load of between 10 N / mm and 40 N / mm.

7. Method according to one of the preceding claims, wherein no moistening of the fibrous web (1) takes place between leaving the dryer section (10) and the cooling in step b).

8. Method according to one of the preceding claims, wherein the fibrous web is a cardboard web which is composed of 2 or more layers and has a basis weight of between 100 g / m2 and 600 g / m2, in particular between 150 g / m2 and 450 g / m2.

9. Apparatus for producing or treating a fibrous web (1), in particular a paper or board web (1), the apparatus comprising a drying section (10) for drying the fibrous web (1) and a calender (2) for treating, in particular smoothing, the fibrous web (1), the apparatus being suitable for treating the fibrous web at a speed of between 600 m / min and 1600 m / min, the apparatus having a steam blow box (7) upstream of the calender (2) in the web running direction for applying steam to a first side (1a) of the fibrous web (1), and means for convection cooling being provided between the dryer section (10) and the steam blow box (7), which means are suitable for this purpose, cooling at least the first side (1a) of the fibrous web (1) by means of convection to a temperature of 65°C and less, in particular to 50°C and less, the distance between the steam blow box (7) and the calendering nip (3) being at most 1000 mm, characterized in that the calender comprises exactly one calendering nip (3).

10. Device according to claim 9, characterized in that the means for convection cooling are implemented as passive cooling by a free section of the fibrous web (1), the free section being at least 5 m long, preferably at least 7 m long.

11. Apparatus according to one of claims 9 or 10, characterized in that the means for convection cooling comprise or consist of active cooling by at least one convection cooler (6), wherein the convection cooler (6) is arranged to blow air (62) onto at least the first side (1a), in particular onto both sides of the fibrous web (1).

12. Device according to claim 11, characterized in that the convection cooler (6) has means for conditioning the air, in particular for tempering and / or humidifying or dehumidifying the air.

13. Apparatus according to any one of claims 9 to 12, characterized in that the calendering nip (3) is formed from a heated roller (4) and a counter element (5), wherein the heated roller (4) can be heated to a surface temperature of 220°C or more and comes into contact with the first side (1a) of the fibrous web (1).

14. Device according to one of claims 9 to 13, characterized in that the calender (2) has means for calibrating the thickness, the means for calibrating the thickness being implemented in particular by means of thermal calibration and / or via a bending adjustment roller.

15. Device according to one of claims 9 to 14, characterized in that a second steam blow box is provided for applying steam to a second side of the fibrous web (1), and the distance between the second steam blow box and the calendering nip (3) is at most 1000 mm

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