EP0857818B1 - Machine to manufacture a fibrous web - Google Patents

Description

The invention relates to a machine for producing a Fibrous web, especially paper and / or cardboard web, after Preamble of claim 1.

Such a machine is known for example from DE-A-3 217 860.

At higher drainage speeds, it can at the Surface of the fibrous web to form a dense Come that another passage of water through the layer Path surface hindered. For example in the press section or the wire section can not only achieve desired effects such as low rewetting, but also to undesirable effects such as one Guide the web. Thereby lie in the wire section and at least essentially the same in the press section Conditions before.

The aim of the invention is a machine of the type mentioned Kind of creating, especially with regard to achieving the highest possible dryness and one possible gentle treatment of the fibrous web further optimized is.

The object is achieved according to the invention according to the features of claim 1 solved.

In the direction of web travel before each of the first and second a one-sided drainage zone a further drainage zone can be provided, in which the fibrous web is drained to both sides of the web simultaneously becomes. The fibrous web is double-sided Drainage causing further drainage zone preferably between two sieve belts, between two felt belts and / or dewatered between a wire and a felt belt.

It is particularly advantageous if the on the fibrous web effective pressure in at least one drainage zone through the Web tension generated at least one screen and / or felt belt is. To increase the web tension, several sieve or felt tapes may be provided.

In a preferred embodiment in practice, is a the printing-producing screen and / or felt belt over a roller with a rigid roller jacket or a shoe press unit, that can be grooved or vacuumed.

A sieve belt is preferably guided over a suction device.

In a preferred embodiment in practice the dewatering of the fibrous web in at least one dewatering zone through an applied differential pressure.

The pressure increase in the second drainage zone is expedient somewhat steeper or equal to the pressure increase in the first drainage zone.

Basically, it is also possible to pass through the web surface to consciously compress a high final pressure.

The fibrous web is preferably in at least one dewatering zone by at least one press nip of a mechanical Press led. Advantageously, at least a press nip an elongated in the web running direction, press nip formed by a shoe press.

At least one simply felted press nip is expedient provided, the fibrous web preferably between the felt and one in particular by a roller, the Sheath of a shoe press unit and / or a band formed smooth surface is guided through this press nip.

The final pressure in a web running direction before a first one Drainage zone arranged, a bilateral drainage causing further drainage zone is preferably lower or equal to the initial pressure in the first drainage zone.

According to a particularly advantageous, preferred in practice Embodiment of the machine according to the invention is the Initial printing in a first or second one-sided Drainage zone causing drainage at least essentially the same as the final pressure in the last one previous one-sided drainage to the same Drainage zone causing a side of the web.

The final pressure in the last one sided drainage too a drainage zone causing a web side is expedient at least substantially equal to the ultimate pressure in the last one-sided drainage to the other Drainage zone causing a side of the web.

The machine can be used to produce a multilayer fibrous web comprise a multi-layer headbox. It is therefore particularly a different material input possible.

The sheet-forming material can be h-free or also h-containing.

So far, especially with h-free paper, the first press nip has occurred frequently surface compaction, which led to the water in the subsequent press nips could no longer escape from the web. This disadvantage is according to an expedient embodiment of the machine according to the invention avoided in that at least one Shoe press with a press nip extended in the direction of web travel is provided, through which the fibrous web is guided, and that the maximum pressure in the nip considered in the web running direction first shoe press is less than or equal to about 15 bar. Here is the maximum pressure advantageously in a range from about 2 to about 15 bar and suitably in a range from about 2 to about 8 bar, preferably 8 bar.

In a preferred embodiment in practice it is in the press nip line force generated by the first shoe press was less than 300 kN / m and preferably less than or equal to 150 kN / m.

The length of the first shoe press considered in the direction of web travel assigned press shoe is advantageously in a range of about 200 to about 350 mm.

The counter roll assigned to the shoe press unit of the first shoe press can be, for example, a suction roll. This can also be done with Provide blind holes and / or be grooved. Instead of a suction roller can also be a simple roller with blind holes be provided. However, the counter roller can also be a Act profile roll.

In an advantageous practical embodiment is in Web direction behind the first shoe press a second Shoe press provided, the maximum pressure in the press nip this second shoe press is about three times as large as that in the nip of the first shoe press and preferably is in a range from about 15 bar to about 30 bar. The maximum generated in the nip of the second shoe press Line force is preferably about 450 kN / m.

After the first shoe press, a roller press with a press nip lying between two rigid roll shells be provided, the maximum pressure in this press nip in a range from about 8 to about 20 bar, especially in is in a range from about 8 to about 15 bar and is preferred Is 10 bar.

The during operation in the nip of the roller press The line force generated is advantageously in a range from about 10 to about 30 kN / m, preferably is about 20 kN / m.

In the web running direction behind the first shoe press or behind the second shoe press or behind the roller press can be one additional shoe press may be provided, the one in the extended one Press gap of the further shoe press generated maximum Line force in particular in a range from about 600 to 1200 kN / m and are preferably about 800 kN / m can.

In the web running direction behind the other shoe press, one can additional press may be provided. In this case, according to a particularly advantageous practical embodiment provided that the press nips of the further shoe press and the additional press felted on different web sides are and that the maximum pressure in the nip of the additional press approximately equal to that in the press nip of the other Shoe press is. With the additional press, it can for example, a shoe press or also a act simple roller press.

The press nip of the first shoe press is preferably double felted.

According to a particularly advantageous, preferred in practice The machine comprises at least one variant Shoe press with a press nip elongated in the direction of web travel, in which the maximum line force is less than 150 kN / m, is preferably less than 100 kN / m. Such a shoe press can therefore be used as a replacement for a roller press. This makes it possible to make shoe press units smaller To produce diameter of, for example, 600 mm can be easily installed in the current presses. Such Shoe press unit is especially for quality improvement for cardboard machines, but also for the production of graphic Paper and can be used for other qualities.

Further advantageous embodiments are in the subclaims specified the machine according to the invention.

Figur 1

eine schematische Darstellung einer durch einen doppelt befilzten Walzenspalt geführten Faserstoffbahn,

Figur 2

eine schematische Darstellung eines eine Faserstoffbahn abstützenden Siebbandes, an das ein Differenzdruck angelegt ist,

Figur 3

eine schematische Darstellung des Druckverlaufs in drei in Bahnlaufrichtung hintereinander liegenden Entwässerungszonen einer Ausführungsform einer erfindungsgemäßen, zur Herstellung einer Faserstoffbahn dienenden Maschine,

Figur 4

eine schematische Darstellung des Druckverlaufs in drei in Bahnlaufrichtung hintereinander liegenden Entwässerungszonen einer weiteren Ausführungsform der erfindungsgemäßen Maschine,

Figur 5

eine schematische Darstellung zweier über eine gekrümmte Fläche geführter Sieb- und/oder Filzbänder,

Figur 6

eine schematische Darstellung eines einfach befilzten Preßspaltes einer Schuhpresse,

Figur 7

eine schematische Seitenansicht einer Ausführungsform einer zur Herstellung einer Faserstoffbahn dienenden erfindungsgemäßen Maschine,

Figur 8

eine schematische Darstellung des Druckverlaufs in mehreren in Bahnlaufrichtung hintereinander liegenden Entwässerungszonen der in Figur 7 gezeigten Ausführungsform,

Figur 9

eine schematische Seitenansicht einer Pressenanordnung einer weiteren Ausführungsform einer zur Herstellung einer Faserstoffbahn dienenden erfindungsgemäßen Maschine,

Figur 10

eine schematische Seitenansicht einer Pressenanordnung einer weiteren Ausführungsform einer zur Herstellung einer Faserstoffbahn dienenden erfindungsgemäßen Maschine und

Figur 11

eine schematische Seitenansicht einer Pressenanordnung einer weiteren Ausführungsform einer zur Herstellung einer Faserstoffbahn dienenden erfindungsgemäßen Maschine.

The invention is explained below using exemplary embodiments with reference to the drawing; in this show:

Figure 1

1 shows a schematic representation of a fibrous web passed through a double felted nip,

Figure 2

1 shows a schematic representation of a screen belt supporting a fibrous web, to which a differential pressure is applied,

Figure 3

2 shows a schematic representation of the pressure curve in three dewatering zones lying one behind the other in the web running direction of an embodiment of a machine according to the invention used for producing a fibrous web,

Figure 4

2 shows a schematic representation of the pressure curve in three dewatering zones, one behind the other in the web running direction, of a further embodiment of the machine according to the invention,

Figure 5

2 shows a schematic representation of two sieve and / or felt belts guided over a curved surface,

Figure 6

1 shows a schematic representation of a simply felted press nip of a shoe press,

Figure 7

2 shows a schematic side view of an embodiment of a machine according to the invention used for producing a fibrous web,

Figure 8

2 shows a schematic representation of the pressure curve in a plurality of drainage zones of the embodiment shown in FIG. 7, one behind the other in the web running direction,

Figure 9

2 shows a schematic side view of a press arrangement of a further embodiment of a machine according to the invention used for producing a fibrous web,

Figure 10

is a schematic side view of a press arrangement of a further embodiment of a machine according to the invention for producing a fibrous web and

Figure 11

is a schematic side view of a press arrangement of a further embodiment of a machine according to the invention for producing a fibrous web.

Figure 1 shows a schematic representation by a Roll gap guided fiber web 10. The roll gap is double felted, the fibrous web 10 through on both sides the two felts 13 is dewatered. At higher drainage speeds it can be on the surface of the web come to the formation of a dense layer 12, the further water penetration through the surface of the track is hindered.

FIG. 2 schematically shows a fibrous web 10 supporting Screen belt 14 shown, on one side of the Stock suspension 16 applied and on the other side a differential pressure -Δp is applied. As with FIG. 2 can be seen, it can also be used for training in this case come a dense layer 12. The surface compaction is among others of the respective fabric, the respective basis weight and the respective dry matter content.

In order to avoid the disadvantages associated with such a surface compaction, in a first embodiment of a machine according to the invention for producing a fibrous web, which can in particular be a paper and / or cardboard web, at least two drainage zones I, II which follow one another in the web running direction L (cf. e.g. 3, 4 and 8) are provided, in which the fibrous web 10 is dewatered on one side in each case with the pressure p increasing in the web running direction L from an initial to an end pressure p ₁ , p ₃ or p ₂ , p ₄ (see, for example, FIG. 3) , wherein the dewatering of the fibrous web 10 takes place in the first I of the two dewatering zones I, II, viewed in the direction of web travel L, to one side of the web and in the second dewatering zone II to the other side of the web, and the initial pressure p ₃ in the second dewatering zone II is lower than the final pressure p ₂ in the first drainage zone I. In the embodiment shown in FIG. 8 For example, two further such drainage zones I ', II' are provided.

Figure 3 shows a schematic representation of the pressure curve in three drainage zones one behind the other in the web running direction L. an embodiment of an inventive for the production of a fibrous web 10 serving machine. Here is in the web running direction L before the first and the second one causing one-sided drainage Drainage zone I or II a further drainage zone Z provided in which the fibrous web 10 simultaneously to both Railway sides is drained.

As can be seen from FIG. 3, the initial pressure p ₃ in the second drainage zone II is significantly lower than the final pressure p ₂ in the first drainage zone I.

In the present case, the drainage takes place in the first Drainage zone I up while in the second Drainage zone II downwards.

The same applies to the embodiment shown in FIG. 4 to, but only in the further zone Z. upward drainage with increasing pressure takes place.

In both the first and the second drainage zones I and II, respectively, which cause one-sided drainage, the initial pressure p ₁ or p _{3 is} lower than the final pressure p ₂ or p ₄ .

In the embodiment shown in Figure 3 results in two drainage zones I and II at least essentially same pressure increase. In contrast, in FIG shown embodiment of the pressure increase in the second Drainage zone II is steeper than in the first drainage zone I.

In particular, FIG. 3 also shows that the final pressure in zone Z causing double-sided drainage is substantially equal to the initial pressure p ₁ in the first zone I causing single-sided drainage. The final pressure of a previous bilateral drainage can also be slightly lower than the initial pressure of the subsequent bilateral drainage.

The double-sided dewatering of the fibrous web can e.g. between two sieve belts, two felt belts and / or between a sieve and a felt belt.

In the exemplary embodiment according to FIG. 5, it is placed on the fibrous web 10 acting pressure through the web train two over creates a curved surface of guided bands 18, 20 at which are each a sieve and / or felt belt can. In the present case, the band 18 is immediately over guided a roller 22 with a rigid roller shell. in principle however, it is also possible to e.g. over a To guide shoe press unit. The roller 22 and the Shoe press unit can be grooved or vacuumed.

A sieve can run over one or more suction cups.

Dewatering can also be done by applying a differential pressure take place, as indicated for example in Figure 2 is.

The fibrous web can be in at least one dewatering zone 10 by at least one press nip of a mechanical press be led. For example, in Figure 6 is a schematic Representation of a simple felted slit one Shoe press shown. Here, the fibrous web is 10 between the felt 24 and an all-round smooth surface passed through the press nip, which in the present case a smooth counter-roller 28 assigned to the shoe press unit 26 is formed.

Figure 7 shows a schematic side view of another Embodiment of one for producing a fibrous web serving machine according to the invention with several in Direction of web running drainage zones Z, I, II, I 'and II', the pressure curve of which is shown schematically in FIG 8 is shown.

Then in the web running direction L are behind the two drainage zones I and II two more, also one each unilateral drainage serving drainage zones I 'and II 'provided in which the drainage turn to different Railway sides out. Drainage also takes place in Zone I 'in an opposite to that of Zone II Direction.

The initial pressure in the one-sided drainage down effecting drainage zone I 'is at least essentially equal to the final pressure of the last preceding one, one-sided drainage to the same web side dewatering zone I. In addition there is the initial pressure which causes a one-sided drainage upwards Drainage zone II 'at least substantially the same size like the final print in the previous one, one-sided Causing drainage to the same side of the web Drainage zone II. Finally, the final pressure is in the last one causing one-sided drainage upwards Drainage zone II 'at least substantially the same Final pressure in the last one-sided drainage down effecting drainage zone I '.

The embodiment shown in Figure 7 includes for generation a multi-layer fibrous web a multi-layer headbox 30th

In the sheet formation zone 32 are in the loop of the upper one Sieve belt 34 water removal means 36 is provided. Opposite these a first suction device 38 is provided, which in the Loop of the lower sieve belt 40 is arranged. In the area this sucker 38 becomes a relatively low differential pressure Δp generated, for example in the range of about 0.1 to can be about 0.5 bar. In the area of the suction cup 38 results in the present case the drainage zone Z (cf. also Figure 8).

Then the two sieve belts 40, 34 are around a suction roll 42 led, in the area of which one-sided drainage downward effecting drainage zone I. becomes. The differential pressure generated in this case is relative high. For example, it can be around 0.6 bar.

In contrast, there is an adjoining area second sucker 44 again a relatively low differential pressure, the between in the present embodiment about 0.1 and about 0.5 bar. This overhead sucker 44 causes unilateral drainage upwards, which, like can be seen in Figure 8, is less than the subsequent also upward one-sided drainage in the area of a further suction roller 46, around which in turn both sieve belts 34, 40 are guided. In the area of the second Sucker 44 and the other suction roller 46 is thus the Correspondingly, a drainage zone with a stepped pressure curve II formed (see also Figure 8). After the suction roll 46, the two sieve belts 34, 40 are separated from one another.

In the area of the suction roller 46, a relatively high one again Differential pressure generated, as in the suction roller 42 for example can be about 0.6 bar.

As can also be seen in FIG. 7, this includes two shoe presses adjoining the wire section 48, 50, through which the two also shown in Figure 8 Drainage zones I 'and II' are formed.

In certain applications, the web surface can pass through a high final pressure can be deliberately compressed.

In Figures 9 to 11 is a schematic side view in each case a press arrangement of a further embodiment an inventive for the production of a fibrous web Machine shown.

Each of these press assemblies includes multiple shoe presses. The maximum pressure in the press nip is in the web running direction L considers the first shoe press 52 smaller or about 15 bar.

In the present case, the maximum pressure is in a range from about 2 to about 15 bar, it being expedient are in a range from about 2 to about 8 bar and preferably Can be 8 bar.

In addition, in the present exemplary embodiments, the operation in the nip of the first shoe press 52 generated line force less than 300 kN / m and preferably less than or equal to 150 kN / m. The one viewed in the web running direction L. Length of the press shoe assigned to this shoe press 52 54 is in a range of about 200, for example up to about 350 mm.

In the embodiment shown in Figure 9, the Shoe press 52, a shoe press unit 56 and a suction roll 58. The press nip A formed by this shoe press 52 is double felted.

According to this figure 9 is in the web running direction L behind the first Shoe press 52 a second shoe press 60 is provided, a roller press between the two shoe presses 52 and 60 62 is formed, the one roller 64 and the central Suction roll 58 includes to form the nip B therebetween. The roller 64 simultaneously forms the counter roller to one of the second shoe press 60 associated shoe press unit 66 to form the third press nip C.

The suction roller 58 can additionally be provided with blind bores and / or be grooved, as in the exemplary embodiment according to Figure 10 is shown. In this embodiment 10, the suction roller 58 is also another Shoe press unit 56 'assigned to this suction roller 58 a further press nip extended in the direction of web travel form.

In addition, in the exemplary embodiment according to FIG. 10, the second is Shoe press 60 designed so that in this through Press formed press nip C gives a maximum pressure that is about three times the size of that in the first shoe press. This maximum pressure in the press nip C can, for example, in range from about 15 bar to about 30 bar. there the maximum line pressure can be, for example, about 450 kN / m be.

In particular in the embodiment according to FIG. 9, the roller press 62 following the first shoe press 52 designed in this way be that there is a smaller one in the press nip B in question Pressure results, the maximum pressure in this press nip B, for example, in a range from about 8 to about 15 bar can be. The line force is, for example, in a range from about 10 to about 30 kN / m, with preference is about 20 kN / m.

Basically, behind a first shoe press, behind a second shoe press or behind one, for example after a first shoe press, another roller press Shoe press can be provided, which in the extended Press nip of this further shoe press generated maximum line force e.g. are in a range from about 600 to 1200 kN / m can and is preferably about 800 kN / m. For example the shoe press 60 having the press nip C. correspondingly in the embodiment shown in FIG. 9 be trained.

In practice, it can be advantageous if, in the case of FIG illustrated embodiment, the maximum pressure in the press nip A is in a range from 2 to 15 bar and for example Is 8 bar, the maximum pressure in the press nip B is in a range from 8 to 20 bar and for example Is 10 bar and the maximum pressure in the Press nip C is in a range from 30 to 100 bar.

The embodiment shown in Figure 11 differs differs from that of FIG. 9 essentially in that in Web running direction L behind the second shoe press 60 an additional Press 70, in the present case again Shoe press is provided. Here, the press nips C, D the second shoe press 60 and the additional press 70 felted on different web sides. The maximum pressure in the press nip D of the additional press 70 is preferred approximately equal to that in the nip C of the second shoe press 60th

In all of the exemplary embodiments illustrated in FIGS. 9 to 10 is the press nip A of the first shoe press 52 double felted.

Basically, it is possible to have at least one shoe press a maximum line force that is less than 150 kN / m is preferably less than 100 kN / m, as a replacement for roller presses use. This allows shoe press units to be smaller Diameter of 600 mm, for example, which can then be easily installed in the current presses are. An appropriate shoe press can be used to improve quality especially in advance machines, but also used for graphic papers and other qualities.

LIST OF REFERENCE NUMBERS

10

Fibrous web

12

dense layer

13

felt

14

screen belt

16

suspension

18

tape

20

tape

22

roller

24

felt

26

shoe press

28

backing roll

30

Multi-layer headbox

32

Forming zone

34

screen belt

36

water laxatives

38

Mammal

40

screen belt

42

suction roll

44

Mammal

46

suction roll

48

shoe press

50

shoe press

52

shoe press

54

press shoe

56

shoe press

56 '

shoe press

58

suction roll

60

second shoe press

62

roll press

64

roller

66

shoe press

70

Press

A

nip

B

nip

C

nip

I

first drainage zone

I '

first drainage zone

II

second drainage zone

II '

second drainage zone

Z

further drainage zone

Claims (32)

1. Machine for producing a fibrous web (10), especially paper and/or board web, in which the preformed fibrous web (10) is dewatered, the machine comprising at least two dewatering zones (I, II) following each other in a web running direction (L), in which the fibrous web (10) is in each case dewatered on one side with a pressure which rises in the web running direction (L) from a starting pressure to a final pressure (p₁, p₃ and p₂, p₄), the dewatering of the fibrous web (10) in the first (I) of the two dewatering zones (I, II), as viewed in the web running direction (L), taking place towards one web side and, in the second dewatering zone (II), taking place towards the other web side, characterized in that the starting pressure p₃ in the second dewatering zone (II) is lower than the final pressure (p₂) in the first dewatering zone (I).
2. Machine according to Claim 1, characterized in that upstream of the first and the second dewatering zone (I and II) in the web running direction (L) there is provided a further dewatering zone (Z), in which the fibrous web (10) is dewatered simultaneously towards both web sides.
3. Machine according to Claim 2, characterized in that in the further dewatering zone (Z), effecting two-sided dewatering, the fibrous web (10) is dewatered between two wires, between two felts and/or between a wire and a felt.
4. Machine according to one of the preceding claims, characterized in that the pressure acting on the fibrous web (10) in at least one dewatering zone is produced by the web tension of at least one wire and/or felt (18, 20).
5. Machine according to Claim 4, characterized in that a wire or felt (18) producing the pressure is led over a roll (22) with a rigid roll cover or a shoe press unit.
6. Machine according to Claim 5, characterized in that the roll (22) or shoe press unit is grooved or evacuated.
7. Machine according to one of the preceding claims, characterized in that a wire is led over a suction means.
8. Machine according to one of the preceding claims, characterized in that the fibrous web (10) is dewatered in at least one dewatering zone by means of an applied differential pressure.
9. Machine according to Claim 8, characterized in that the differential pressure lies in a range from about 0.2 to about 0.9 bar.
10. Machine according to Claim 8 or 9, characterized in that the maximum differential pressure lies in a range from about 0.7 to about 0.95 bar.
11. Machine according to one of the preceding claims, characterized in that the pressure rise in the second dewatering zone (II) is steeper than or equal to the pressure rise in the first dewatering zone (I).
12. Machine according to one of the preceding claims, characterized in that the fibrous web (10) in at least one dewatering zone is led through at least one press nip belonging to a mechanical press.
13. Machine according to Claim 12, characterized in that at least one press nip is a press nip that is extended in the web running direction and formed by a shoe press.
14. Machine according to Claim 12 or 13, characterized in that at least one press nip is single-felted.
15. Machine according to Claim 14, characterized in that the fibrous web is led through the relevant press nip between the felt (24) and a smooth surface formed in particular by a roll (28), the cover of a shoe press unit and/or a belt.
16. Machine according to one of Claims 2 to 15, characterized in that the final pressure in the further dewatering zone (Z) arranged upstream of the first dewatering zone (I) in the web running direction (L) and effecting two-sided dewatering is lower than or equal to the starting pressure (p₁) in the first dewatering zone (I).
17. Machine according to one of the preceding claims, characterized in that the starting pressure in a first or second dewatering zone (I' or II') respectively effecting one-sided dewatering is at least substantially equal to the final pressure in the last preceding dewatering zone (I or II) effecting one-sided dewatering towards the same web side.
18. Machine according to one of the preceding claims, characterized in that the final pressure in the last dewatering zone (II') effecting one-sided dewatering towards one web side is at least substantially equal to the final pressure in the last dewatering zone (I') effecting one-sided dewatering towards the other web side.
19. Machine according to one of the preceding claims, characterized in that it comprises a multi-layer flow box (30) for producing a multi-ply fibrous web (10).
20. Machine according to one of the preceding claims, characterized in that at least one shoe press with a press nip extended in the web running direction (L) is provided, through which the fibrous web (10) is led, and in that the maximum pressure in the press nip of the first shoe press (52), as viewed in the web running direction (L), is less than or equal to about 15 bar.
21. Machine according to Claim 20, characterized in that the maximum pressure lies in a range from about 2 to about 15 bar, expediently in a range from about 2 to about 8 bar, and is preferably 8 bar.
22. Machine according to Claim 20 or 21, characterized in that the line force produced in the press nip (A) of the first shoe press (52) during operation is less than 300 kN/m and preferably less than or equal to 150 kN/m.
23. Machine according to one of Claims 20 to 22, characterized in that the length of the press shoe (54) associated with the first shoe press (52), as viewed in the web running direction (L), lies in a range from about 200 to about 350 mm.
24. Machine according to one of Claims 20 to 22, characterized in that, in the web running direction (L), a second shoe press (60) is provided downstream of the first shoe press (52), and in that the maximum pressure in the press nip (C) of this second shoe press (60) is about three times as high as that in the press nip (A) of the first shoe press (52) and also preferably lies in a range from about 15 bar to about 30 bar.
25. Machine according to Claim 24, characterized in that the maximum line force produced in the press nip (C) of the second shoe press (60) is about 450 kN/m.
26. Machine according to one of Claims 20 to 25, characterized in that, in the web running direction (L), a roll press (60) having a press nip (B) between two rigid roll covers is provided downstream of the first shoe press (52), and in that the maximum pressure in this press nip (B) lies in a range from about 8 to about 20 bar, in particular in a range from about 8 to about 15 bar, and is preferably 10 bar.
27. Machine according to Claim 26, characterized in that the line force produced in the press nip (B) of the roll press (62) during operation lies in a range from about 10 to about 30 kN/m, and is preferably about 20 kN/m.
28. Machine according to one of Claims 20 to 27, characterized in that the second shoe press (60) provided downstream of the first shoe press (52) or downstream of the roll press (62) in the web running direction (L), or a further shoe press provided downstream of the second shoe press, is constructed in such a way that the maximum line force produced in the extended press nip (B) of the second or further shoe press lies in a range from about 600 to 1200 kN/m, and is preferably about 800 kN/m.
29. Machine according to Claim 28, characterized in that an additional press (70) is provided downstream of the second (60) or further shoe press in the web running direction (L), in that the press nip (C, D) of the second (60) or further shoe press and of the additional press (70) are felted on different web sides, and in that the maximum pressure in the press nip (D) of the additional press (70) is approximately equal to that in the press nip (C) of the second (60) or further shoe press.
30. Machine according to one of Claims 20 to 29, characterized in that the press nip (A) of the first shoe press (52) is double-felted.
31. Machine according to one of the preceding claims, characterized in that it comprises at least one shoe press having a press nip that is extended in the web running direction and in which the maximum line force is less than 150 kN/m, preferably less than 100 kN/m.
32. Machine according to Claim 31, characterized in that the shoe press comprises a shoe press unit whose diameter is about 600 mm.

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