EP1911876B1 - Method and device for manufacturing a sheet of fibrous material - Google Patents

Abstract

The production device has a material input (1) and other components such as a former (2) and press unit (3), and upper and lower sieve rolls (4, 5). The arrangement and/or operation of the material input alone or in combination with that of another component are such as to produce the required layer orientation in the z-direction.

Description

The present invention relates to a device for producing a fibrous web, in particular paper web, with a headbox and other components, such as former, press section, dryer section, coater and / or calender, wherein
the configuration and / or the operation of the headbox alone or in combination with the configuration of at least one further component is selected so that there is a desired profile of the layer orientation in the z-direction with respect to a curl influencing the fibrous web.

Furthermore, the present invention relates to a method for producing a fibrous web, in particular paper web, in which a pulp suspension is introduced by means of a headbox in a former and then further treated by means of other components such as press section, dryer section, coater and / or calender, wherein
the design and / or the operation of the headbox alone or in combination with the design and / or operation of at least one further component is selected so that there is a desired profile of the layer orientation in the z-direction with respect to a curl influencing the fibrous web.

Such a device and such a method are for example from the publications WO 97/47803 A1 and US 2005/0144802 A1 known.

In the production of a fibrous web, in particular a wood-free copy paper, it is particularly important that the finished fibrous web has little or no tendency to curl, curl, curl and the like in terms of performance in the subsequent copying process. The curl is caused, for example by a Umklimatisierung the fibrous web. By heat during the copying process, the moisture content of the fibrous web and thus also of the fibers is reduced. The fibers shrink and create stresses in the fibrous web which cause curling when the fibrous web is asymmetrically heated. So far, it has been attempted to compensate for this tendency to curl in the production process of the fibrous web by an asymmetric heating course in the production machine by means of two-row drying groups. But this was only insufficient.

If the fibrous web, in particular the paper web in the z-direction, ie in the direction of the sheet thickness, is subdivided into different layers, then each layer has a more or less pronounced anisotropy with respect to the fiber orientation in the plane. The layers may each have main layers of fiber layers, which are characterized in that a certain number of fibers are aligned in the same direction. Fibrous main directions may point exactly in the machine main direction or across it or in directions therebetween. How many fibers point in a common direction is expressed in the degree of anisotropy. High anisotropy means that many fibers are oriented in one direction and vice versa. The anisotropy of the fiber layers also significantly determines the anisotropy of the mechanical properties, e.g. the in-plane strength anisotropy. The anisotropy or the degree of anisotropy may be different in the layers. Then one speaks of a non-constant profile of the layer orientation measured over the sheet thickness, ie in the z-direction.

A measure of the different layer orientation in the z-direction can be, for example, the ratio of the tenacial length ratios of the upper half of the sheet to the lower half of the sheet. This measure should be at the end of the paper machine in the range of 0.7 to 1.3, preferably from 0.8 to 1.2, lie. The tenacity ratio, called RLV in technical circles, is the ratio of the tear length in the machine direction (MD direction) and the tear length in the cross machine direction (CD direction). This can be determined for the entire fibrous web or, after splitting the fibrous web in layers, also for each layer.

A profile of the layer orientation manifests itself in particular in a two-sidedness, that is to say a different layer orientation on the upper side of the sheet and on the lower side of the sheet. Such a two-sidedness can arise due to the asymmetrical structure of the headbox nozzles. In the flow deflection at the diaphragm, the fibers are increasingly aligned in the machine direction. On the opposite lower lip side finds an alignment in Machine direction due to the increased microturbulence only limited. Also by the former, the press section and the dryer section in a paper machine, a two-sidedness of the layer orientation between the upper side of the sheet and the lower side of the sheet can be generated.

The invention has the object to improve a device and a method of the type mentioned. In particular, the properties of the fibrous web, in particular the curl of the fibrous web, should be improved.

This object is achieved in a device of the type mentioned, characterized
in that a former having a forming roller arranged on the upper side of the fibrous web is combined with a headbox which causes a correspondingly asymmetrical layer orientation, and in that the headbox for effecting the asymmetrical layer orientation comprises an asymmetrical nozzle and / or an asymmetrical disk arrangement and / or a two-or has multilayer structure with different film speeds.

Most of the dewatering takes place in the area of the forming roller, as a result of which this element has a great influence on the fiber orientation. Since only on the side of the forming roll vacuum is applied, the one-sided vacuum leads to a different level of orientation on the top and bottom of the fibrous web. This is exacerbated when the forming sucker is placed after the forming roll with its vacuum on the same side as the forming roll. Since the vacuum level also affects other paper properties such as formation and dry content, the vacuum can not be used solely for setting a desired profile of the layer orientation. A desired profile of the layer orientation can therefore be achieved only by the inventive combination of the former with a headbox with a corresponding asymmetric layer orientation.

The different layer speeds also result in a different layer orientation, since the fiber orientation also increases with increasing flow velocity.

In a method of the type mentioned, the object is achieved by
in that a former is combined with a forming roll arranged on the upper side of the fibrous web, with a headbox causing a correspondingly asymmetric layer orientation, and that the headbox is provided with an asymmetrical nozzle and / or asymmetrical lamellae for effecting the asymmetrical layer orientation and / or two or is formed multi-layered, wherein the layer velocities of the pulp suspension are chosen according to different.

The inventors have recognized that the headbox, the former, the press section, the dryer section and other components of the production machine have different effects on the structure of the fibrous web with regard to curl tendency. While the headbox and the former can mainly negatively affect the fiber layer of the fibrous web, the press section, for example, has an effect on the composition of the fibrous web in the z-direction. For example, a different ratio between fibers and fillers on the top and the bottom of the As a result of these structural differences, fibrous webs have a negative effect on curl tendency.

The inventors have found that this can not be corrected by the known measures, such as the adaptation of the heating curve in the dryer section. Rather, the headbox offers the possibility of correcting the layer orientation by shaping its flow space a correction, so that in later use of the fibrous web minimal or no curl occurs more.

It has also been found that when the transfer from one component of the production machine to the other, the trains or expansions of the fibrous web negatively influence the structure of the fibrous web with regard to curl behavior.

According to the invention, it is therefore proposed to selectively use the known influence of the headbox and at least one further constituent on the profile of the layer orientation by combining a headbox with a specific influence on this profile with at least one further constituent whose influence on said profile is influenced by the influence Counteracts or supports headbox, depending on whether according to a preferred embodiment of the invention, a symmetrical to the median plane of the fibrous web layer orientation is desired or in certain cases an asymmetric layer orientation. For example, an asymmetric layer orientation may be preferred or chosen for certain types of paper to compensate for an influence of another component of the paper machine on the profile of the layer orientation.

In this case, the selection is preferably made such that a desired, preferably no curl tendency in the fibrous web results before the coater and / or that a desired, preferably no curl tendency results in the finished fibrous web.

In a method according to the invention, the headbox on the one hand and / or the former, on the other hand, or only the headbox, depending on the machine configuration, are configured and combined with one another in the manner described above. The solution can be used particularly advantageously in the production of copy paper, in particular of wood-free pulp fibers.

The former types of formers described so far are from the group of twin-wire formers, and more particularly from the sub-group of roll-blade formers in which the first dewatering element is a rotating dewatering element, such as a forming roll, ie an open roll. This drainage element can be operated with or without a vacuum.

However, the invention also relates to formers in which the forming roll is formed by a stationary dewatering element, such as, for example, an evacuated or non-evacuated and preferably curved shoe. In the further dewatering process, at least one evacuated forming roll can follow this type of former.

The invention can also find application in a so-called hybrid former. This type of shaper is characterized in that the twin-wire zone follows only after a Einsiebzone. In this, absorbent elements are used for drainage. An asymmetric layer orientation is the result. In the twin-wire area, in turn, at least one forming roll or suction roll and stationary dewatering elements can follow.

Likewise, the invention is applicable to four-wire former which exclusively dewater to one side and thus - depending on the choice of the drainage course - produce a more or less asymmetric layer orientation applicable.

Fig. 1a

eine erste Formerausgestaltung;

Fig. 2b

eine zweite Formerausgestaltung;

Fig. 3c

eine dritte Formerausgestaltung;

Fig. 4a bis 16a

verschiedene Varianten eines Stoffauflaufs;

Fig. 1b bis 16b

die jeweils zugehörige Verteilung der Layerorientation auf der Papierober- und -unterseite;

Fig. 17a bis 17d

weitere verschiedene Varianten eines Stoffauflaufs mit einem jeweils direkt angeflanschten Verteilrohr; und

Fig. 18

eine vorteilhafte Maschinenkonfiguration für die Herstellung von curlarmen und holzfreien Kopierpapieren.

Embodiments of the invention are illustrated in the drawings and will be described below. They show, in each case in a schematic representation,

Fig. 1a

a first former design;

Fig. 2b

a second former design;

Fig. 3c

a third shaper design;

Fig. 4a to 16a

different variants of a headbox;

Fig. 1b to 16b

the respective associated distribution of the layer orientation on the paper top and bottom side;

Fig. 17a to 17d

other variants of a headbox with a directly flanged manifold; and

Fig. 18

an advantageous machine configuration for the production of curlar and wood-free copying papers.

The in Fig. 1a Former shown is part of a paper machine with a headbox 1, said former 2, a subsequent press section 3, of which only the beginning is shown, and other components such as dryer section, optionally coater and calender. The former 2 comprises a forming roller 5 arranged in a bottom wire loop 4 and a forming suction device 6 arranged in a top wire loop 6. The bottom wire loop 4 and top wire loop 6 are each guided via deflection rollers 8. In addition, in the lower sieve loop 4, a suction device 9 and a suction sieve roller 10 are arranged. About a pickup roller 11, which already belongs to the press section 3, the fibrous web is removed from the lower wire 4 of the former and fed to the press section 3. As you can see, in this variant, the forming roller 5 is thus arranged on the underside of the fibrous web.

In Fig. 1b is shown that such a Shaper design results in a symmetric layer orientation. The jet velocity is greater than the sieve speed.

At the in Fig. 2a illustrated variant, the forming roller 5 is arranged in the upper wire loop 6. For this, the lower wire loop 4 has the forming suction 7. Both sieve loops 4 and 6 are again guided in each case over deflection rollers 8, and here too a suction device 9 and a sieve suction roller 10 are provided, the suction device 9 being located in the upper sieve loop 6 and the sieve suction roller 10 again in the lower sieve loop 4. The web removal to the press section is also carried out here by a pickup roller 11 which is arranged in a felt loop 12. In the variant of Fig. 2 Thus, the forming roller 5 is on the upper side of the fibrous web.

In Fig. 2b is shown that results from such a former design an asymmetric layer orientation. The jet velocity is greater than the sieve speed.

Also in the variant of Fig. 3a is the forming roller 5 on the top of the fibrous web. The difference to the variant of Fig. 2 consists merely in that the Formiersauger 7 is on the top of the fibrous web, so in the upper wire loop 6, while the suction device 9 is arranged in the lower wire loop 4. Incidentally, this variant agrees with the variant of Fig. 2 match.

In Fig. 3b is shown that results from such a former design an asymmetric layer orientation. The jet velocity is greater than the sieve speed.

As mentioned at the beginning, can in the Fig. 1a . 2a and 3a Forming roller 5 shown also by a stationary dewatering element, such as an evacuated or not vacuumed and preferably curved shoe, be formed. In the further dewatering process, at least one evacuated forming roller can then follow.

In the Fig. 4a illustrated first variant of a headbox 1 has an asymmetrical nozzle 13 with a diaphragm 14 on the top and a protruding bottom lip 15 on the bottom. In addition, the headbox of this first variant has symmetrically arranged lamellae 16.

In this first variant of the headbox 1, it may moreover be provided that the diaphragm 14 has a main surface which is in contact with the inner surface of the upper nozzle wall or the lower nozzle wall and which is in contact with at least one pulp suspension guided through the asymmetrical nozzle 13. Such a "parallel-aperture" is in the German patent application DE 10 2004 047 879 A1 disclosed; Their disclosure content is hereby made the subject of the present description. The lower lip board ULV of the lower lip 15 may in this embodiment have a value in the range of 0.1 to 1.0 mm, preferably from 0.2 to 0.5 mm.

In Fig. 4b is shown that results from such a design of the headbox asymmetric layer orientation, namely a high anisotropy in the upper half 17 and a lower anisotropy in the lower half 18 of the fibrous web. That is, the fibers in the upper half 17 have a fiber layer main direction, while in the lower half, no such direction is preferred.

In the second headbox variant of Fig. 5a the nozzle design agrees with that of Fig. 4a match. In contrast to the first variant, however, the slats 16 are arranged asymmetrically here.

In this second variant of the headbox 1, it is also possible for the diaphragm 14 to have a main surface which is in contact with the inner surface of the upper nozzle wall or the lower nozzle wall and touched by the at least one fibrous suspension guided through the asymmetrical nozzle 13. Such a "parallel-aperture" is in the German patent application DE 10 2004 047 879 A1 disclosed; Their disclosure content is hereby made the subject of the present description. The lower lip board ULV of the lower lip 15 may in this embodiment have a value in the range of 0.1 to 1.0 mm, preferably from 0.2 to 0.5 mm.

As in Fig. 5b represented by the combination of an asymmetrical nozzle 13 with reversed asymmetric blades 16 results in a symmetrical layer orientation.

In the variants of Fig. 6a and 7a both the nozzles 13 and the lamellae are symmetrical. Accordingly, as shown in the Fig. 6b and 7b shown, a symmetric layer orientation.

The same applies to the variant of Fig. 8a that differ from the variant according to Fig. 6a only by an additional flexible separating element 19 in the middle of the Headbox different. Fig. 8b again shows the symmetric layer orientation.

Also the variant of Fig. 9a has a flexible separating element 19. However, the nozzle design here is asymmetrical, so that as in Fig. 9b shown, gives an asymmetric layer orientation.

In Fig. 10a Another variant is shown, depending on the variant Fig. 9a only differs in that here the lamellae are reversely arranged asymmetrically. As a result, the asymmetrical nozzle design is compensated, so that according to Fig. 10b gives a symmetric layer orientation.

The subsequent machine configuration may necessitate the asymmetry in Fig. 9a even to reinforce. This can be achieved by using longer lamellae 16 in the lower half of the nozzle 13 than in the upper half of the nozzle 13.

Fig. 11a agrees largely with Fig. 8a match. The flexible separating element 19 is merely replaced by a rigid separating element 20. According to Fig. 11b Consequently, a symmetrical layer orientation also results here.

Rigid separators are generally used to separate the die space into at least two die subspaces in which different pressures can be maintained for the purpose of generating different jet velocities, respectively.

Fig. 12a differs from the variant according to Fig. 11a by an asymmetrical lamellar arrangement, so that according to Fig. 12b also gives an asymmetric layer orientation.

In Fig. 13a In turn, a variant with a rigid separating element 20 is shown, in which an asymmetrical nozzle 13 is combined with inversely asymmetrical lamellae 16, so that a symmetrical layer orientation results.

The preferably long and short lamellae 16 in the two nozzle subspaces of the nozzle 13 move in certain length ranges relative to the corresponding aperture 14, in particular in the case of the continuously convergent nozzles. The long fins 16, either flexible or stiff, bend in the range of +/- 30 mm to the aperture tip. The short fins 16 are shorter in all cases. They are preferably in the range of less than -30 to -150 mm, in particular in the range of less than -50 to -100 mm.

Fig. 14a shows a variant with a rigid separator 20, asymmetric nozzle 13 and symmetrical blades 16. This results in an asymmetric layer orientation.

Fig. 15a again shows the variant of Fig. 11a , wherein it is additionally shown here according to arrows 21 and 22 that the flow velocities v1 and v2 in the upper half of the headbox and in the lower half of the headbox can be chosen differently. In the Fig. 15b1, b2 and b3 It shows how the layer orientations are adjusted depending on the speed conditions. Fig. 15b1 shows the case that velocities v1 and v2 are the same Fig. 15b2 shows the case that the speed v1 in the upper half of the headbox is greater than the speed v2 in the lower half and Fig. 15b3 the opposite case. Accordingly, according to Fig. 15b1 a symmetric layer orientation, according to Fig. 15b2 an asymmetric layer orientation with high anisotropy in the upper half of the fibrous web and according to Fig. 15b3 an asymmetric layer orientation with high anisotropy in the lower half of the fibrous web.

Fig. 16a shows a further variant of a headbox with two rigid separating elements. Accordingly, three different speeds v1, v2 and v3 can be set. If all velocities v1 to v3 are set the same, a uniform layer orientation results over the thickness of the fibrous web, as in Fig. 16a shown. By appropriate different choice of speeds v1 to v3, the layer orientation can be selected in the desired manner, in particular also different on the top 17, the bottom 18 and in the center 24 of the fibrous web.

Fig. 17a to 17d Finally show further different variants of a headbox with a directly flanged manifold. The supply of the respective system thus takes place from a manifold.

In the in the Fig. 17a Due to the position of the separating lamella, different flow velocities in the individual layers can be set and thus the layer orientation can be influenced.

The flow rates in the individual layers can be adjusted in different ways. On the one hand, the friction conditions of the flow in the individual layers of the nozzle can be influenced. For example, as in Fig. 17a indicated by the double arrow 26, by means of a pivoting of the rigid blade 27 out of the neutral position and / or by a change in the flow resistance in the respective upstream of the nozzle turbulence generators T1, T2. This is particularly advantageous when both layers are supplied by a distributor tube.

It is also conceivable to supply each layer separately with pulp suspension, for example via separate distributor tubes. The flow rate is tax-related or adjustable.

It is also possible to influence the layer orientation via the setting of different beam contractions in the two layers, for example by setting different aperture boards and / or different aperture angles.

Also conceivable are length-adjustable lamellae and / or variable-shape lamellae for the targeted change of the fluid friction conditions for changing the flow velocities in the respective layers and thus for adjusting the layer orientation. Long lamellae increase the friction and thereby support the anisotropy of the fiber layer, as well as a possible thickening of a lamella and the resulting constriction of a flow channel.

In the in the Fig. 17b Headbox shown with rigid separation blade 27 can be set by the position of the lip support 28, 29 different flow velocities in the individual layers and thus the layer orientation can be influenced. The positioning of the lip supports 28, 29 can be done, for example, by a respective pivoting (double arrows 30, 31) when changing the lip openings.

By varying the flow rate, the existing driving pressure gradient is more or less displaced into the nozzle. This results in different jet speeds. For example, increasing the gap opening by 5% (5% throughput reduction) increases the pressure loss by 10.25% in one shift. At a pressure drop of 500 mbar, this means a pressure reduction of 50 mbar. This achieves, depending on the jet speed, for example at 1200 m / min, a relevant change in the differential speed, for example about - 15 m / min.

The Indian Fig. 17c Headbox presented basically makes a combination of the headboxes of the two Fig. 17a and 17b A change in the pressure loss in the turbulence generator T1, T2 can by actively changing the Flow cross-section, for example by introduction or replacement of inserts, by slide and / or by valves, of one or more lines in one layer or two layers. Preferably, the control is performed on one side of a line, since the flow differences in the percentage range at the nozzle start are not relevant, have a strong impact in the area of sheet formation in the percent range. The control of the jet velocity is carried out by a dynamic pressure control by pressure transmitter in each layer.

And in the in the Fig. 17d headbox is a further development of in the Fig. 17c illustrated headbox. The illustrated headbox also has a known to the expert white water dosing system 32, as for example in the German patent DE 40 19 593 C2 is described.

In particular for writing and printing papers and especially for copying papers made of wood-free pulp fibers, press concepts with, in particular, an extended press nip (shoe press) can be advantageously used. In these types of press, despite the exercise of a pressing operation, the specific volume, the so-called bulk, can be obtained. A possible press concept with only one long press nip with a press nip length> 300 mm, preferably> 400 mm, is, for example, in the German Offenlegungsschriften DE 10 2004 050 593 A1 or DE 10 2004 039 785 A1 described.

Furthermore, two successive press nips can be beneficial. In this case, both press gaps can be formed from shoe presses. Particularly in the case of wood-free papers, a press concept with two press nips, wherein the first press nip is a nip press nip and the second press nip is a shoe press nip, represents a volume-saving combination. The nip press nip, for example, by an overhead and deflection-controlled roll and by an opposing Saugpresswalze formed. Since the fibrous web has a dry content of less than 25% at the inlet to the press section, only small compression pressures are necessary to dewater relatively large amounts of water. These can be easily removed through the suction press roll.

Likewise, the use of a so-called compact press is possible, wherein in the first and / or third press nip a shoe press can be provided. Such a press concept is for example in the German Offenlegungsschrift DE 198 00 807 A1 described.

An exemplary and advantageous machine configuration 100 for the production of curlar and wood free copy papers having a high specific volume is disclosed in U.S.P. FIG. 18 shown. The machine configuration 100 is shown in a total of four partial views, which are marked with the following arrows A, B and C with regard to their sequence.

The pulp suspension 101 is fed via a two-layer headbox 102 to a former 103 in the form of a twin-wire former, wherein pulp suspension 101 from the same substance source 104 is fed into each layer of the headbox 102. The headbox 102 further includes a rigid separator blade 105 which projects from the nozzle 106 and thus divides it into two halves. Each half is fitted with flexible laminations 107, 108 between each row of tubes of the associated turbulence generator 109, 110. These flexible laminations 107, 108 terminate within the nozzle 106 and are symmetrically populated in this example, and moreover two diaphragms 111, 112 are provided.

The former 103 comprises a forming roll 113 and a forming suction 114 which are not disposed on the same side.

The Indian Fig. 18 Shaper shown in a suitable manner with in the Fig. 4a to 16a and 17a to 17d combined headbox variants become. Furthermore, the shaper shown also as a in the Fig. 1a . 2a and 3a be performed executed form variant.

After the former 103, the fibrous web 115 is transferred to a press section 116. The press section 116 consists of a first nip press 117 with an upper and deflection-controlled roller 118 and a lower suction press roller 119. The second and last press nip 120 is formed by a respective shoe roller 121, 122.

The fibrous web 115 is now with a transfer belt 123 to a so-called impingement drying device 124, as for example from the already mentioned German Offenlegungsschrift DE 10 2004 039 785 A1 is known, transferred. The advantage here is the closed web guide up to a dry content of over 60% or 63%. This allows a high production speed for this fibrous web 115 of ≥ 1,500 m / min, in particular ≥ 1,650 m / min.

This is followed by a known single-row (pre-) dryer section 125 with several dryer groups 126. Essential for high production speeds is a supported web guide equipped with stabilizers 127 between the drying cylinders 128.

Subsequent to the pre-drying section 125, at least one coating device 129 follows for preferably two-sided and indirect application of a liquid or pasty medium 130, 131, in particular glue. The application of glue 130, 131 reduces, for example, the dusting of the copy paper in the copier.

After a non-contact deflection 132 and drying 133 of the coated fibrous web 115 is followed by a post-dryer section 134, which includes both single-row dryer groups 135 and two-row dryer groups 136. With the aid of the double-row dryer group 136, a symmetrical drying of the double-sided glue application can be achieved. A slightly different glue application The two sides of the fibrous web 115 would lead to different Trocknungsverläufen and thus in turn to Curlneigung.

This is followed by a two-nip calender 137 and a preferably winding tension controlled / regulated and surface-sparing reeling in a winding machine 138. The two-nip calender 137 may also be generally designed as a calender.

The in the Fig. 1a . 2a and 3a Former variants shown can now in a suitable manner with in the Fig. 4a to 16a . 17a to 17d and 18 Depending on which layer orientation is desired, combined headbox variants are combined. Combinations of multilayer headboxes with the formers of the Fig. 1a . 2a and 3a because desired layer orientations can be set in a particularly advantageous manner by the different flow velocities. In particular, the asymmetry of the layer orientation by the shape variants of the Fig. 2a and 3a be compensated by correspondingly reversed asymmetric headboxes, while the symmetric shaper of Fig. 1a can be combined with a symmetrical headbox to achieve a symmetric layer orientation. However, if an asymmetric layer orientation is to be set, then other combinations can be selected accordingly. In this case, a desired layer orientation can be set by selecting the embodiments of headbox and former according to the invention.

LIST OF REFERENCE NUMBERS

1

headbox

2

molder

3

press section

4

Lower wire loop

5

forming roll

6

Upper wire loop

7

suction box

8th

idler pulley

9

suction

10

Suction roll

11

Pickup roll

12

dryer

13

jet

14

cover

15

bottom lip

16

lamella

17

Top of the fibrous web

18

Bottom of the fibrous web

19

Flexible separator

20

Rigid separating element

21

arrow

22

arrow

23

arrow

24

Middle layer

26

double arrow

27

Rigid separating blade

28

lip carrier

29

lip carrier

30

double arrow

31

double arrow

32

Siebwasserdosierungssystem

100

machine configuration

101

Fibrous suspension

102

headbox

103

molder

104

material source

105

Rigid separating blade

106

jet

107

Flexible lamella

108

Flexible lamella

109

turbulence generator

110

turbulence generator

111

cover

112

cover

113

forming roll

114

suction box

115

Fibrous web

116

press section

117

First nip press

118

Deflection-controlled roller

119

suction press

120

Second press nip

121

shoe roll

122

shoe roll

123

transfer tape

124

Impingement drying device

125

pre-dryer

126

drying group

127

stabilizer

128

drying cylinders

129

coater

130

medium

131

medium

132

Non-contact deflection

133

desiccation

134

Afterdryers

135

Single tier dryer group

136

Double row drying group

137

Two-nip calender

138

winder

A

follow arrow

B

follow arrow

C

follow arrow

T1

turbulence generator

T2

turbulence generator

v1 to v3

flow rates

ULV

Lower lip Board

z

Thickness direction of the fibrous web

Claims (16)

1. Device for manufacturing a fibrous web (115), in particular a paper web, having a flowbox (1; 102) and further constituent parts, such as a former (2; 103), press section (3; 116), drying section (125, 134), coating apparatus (129) and/or calender (137), the configuration of the flowbox (1; 102) on its own or in combination with the configuration of at least one further constituent part being chosen such that the result is a desired profile of the layer orientation in the z direction with regard to influencing curl of the fibrous web (115),
   characterized in that
   a former (2; 103) having a forming roll (5; 113) arranged on the top side (17) of the fibrous web (115) is combined with a flowbox (1; 102) which brings about a correspondingly asymmetric layer orientation, and
   in that in order to effect the asymmetric layer orientation, the flowbox (1; 102) has an asymmetric nozzle (13; 106) and/or an asymmetric slat arrangement (16; 107, 108) and/or a two-layer or multilayer structure with different layer speeds (v1 to v3).
2. Device according to Claim 1,
   characterized in that
   the choice is made such that the result is a layer orientation that is symmetrical with respect to the mid-plane in the z direction of the fibrous web (115).
3. Device according to Claim 1 or 2,
   characterized in that
   the choice is made such that the result is a desired tendency, preferably no tendency, to curling in the fibrous web (115) before the coating apparatus (129).
4. Device according to Claim 1, 2 or 3,
   
   characterized in that
   the choice is made such that the result is a desired tendency, preferably no tendency, to curling in the finished fibrous web (115).
5. Device according to one of the preceding claims,
   characterized in that
   at least one further constituent part of the device is also taken into account in the choice with regard to its influence on the profile of the layer orientation.
6. Device according to one of the preceding claims,
   characterized in that
   the former (2; 103) has a forming suction box (7; 114) arranged on the top side (17) or the underside (18) of the fibrous web (115).
7. Device according to one of the preceding claims,
   characterized in that
   the flowbox (1; 102) is constructed with one, two or more layers.
8. Device according to Claim 7,
   characterized in that
   in the case of a two-layer or multilayer flowbox (1; 102), asymmetry of the nozzle (13; 106) and/or slats (16; 107, 108) of the flowbox is compensated for by different layer speeds (v1 to v3) of the fibrous suspension (101).
9. Method for manufacturing a fibrous web (115), in particular a paper web, in which a fibrous suspension (101) is introduced into a former (2; 103) by means of a flowbox (1; 102) and is then treated further by means of further constituent parts such as a press section (3; 116), drying section (125, 134), coating apparatus (129) and/or calender (137), the configuration and/or operation of the flowbox (1; 102) on its own or in combination with the configuration and/or operation of at least one further constituent part being chosen such that the result is a desired profile of the layer orientation in the z direction with regard to influencing curl of the fibrous web (115),
   characterized in that
   a former (2; 103) having a forming roll (5; 113) arranged on the top side (17) of the fibrous web (115) is combined with a flowbox (1; 102) which brings about a correspondingly asymmetric layer orientation, and
   in that in order to effect the asymmetric layer orientation, the flowbox (1; 102) is provided with an asymmetric nozzle (13; 106) and/or asymmetric slats (16; 107, 108) and/or is of two-layer or multilayer configuration, the layer speeds (v1 to v3) of the fibrous suspension (101) being chosen to be correspondingly different.
10. Method according to Claim 9,
    characterized in that
    the choice is made such that the result is a layer orientation that is symmetrical with respect to the mid-plane in the z direction of the fibrous web (115).
11. Method according to Claim 9 or 10,
    characterized in that
    the choice is made such that the result is a desired tendency, preferably no tendency, to curling in the fibrous web (115) before the coating apparatus (129).
12. Method according to Claim 9, 10 or 11,
    characterized in that
    the choice is made such that the result is a desired tendency, preferably no tendency, to curling in the finished fibrous web (115).
13. Method according to one of Claims 9 to 12,
    characterized in that
    at least one further constituent part of the device is also taken into account in the choice with regard to its influence on the profile of the layer orientation.
14. Method according to one of Claims 9 to 13,
    characterized in that
    the former (2; 103) is provided with a forming suction box (7; 114) arranged on the top side (17) or the underside (18) of the fibrous web (115).
15. Method according to one of Claims 9 to 14,
    characterized in that
    the flowbox (1; 102) is constructed with one, two or more layers.
16. Method according to Claim 15,
    characterized in that
    in the case of a multilayer flowbox (1; 102), the layer speed (v1 to v3) of the fibrous suspension (101) is selected such that asymmetry of the nozzle (13; 106) and/or slats (16; 107, 108) of the flowbox (1, 102) is compensated for.

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