EP0837181B1 - Press section - Google Patents

Abstract

The press section of a machine for making a web (10) of fibrous material (especially paper or paperboard) includes a single centrally placed, cylindrical press roll (12) of large diameter. The roll operates in conjunction with at least one press shoe (14,16) having a concave face which presses a flexible, circulating press belt (18,20) against the roll to form at least one press nip (P1,P2), which is elongated in the direction (L) of web travel. At least one felt or sieve belt (26,28) passes through the press nip.Also claimed is a press section having the inverse arrangement in which a single, large-diameter circulating press belt operates in conjunction with one or more press shoes and corresponding opposing rolls. Preferably the press roll, which is of the internally supported, controlled flexure type, has a diameter which is more than 1500 mm and is more preferably around 2000 mm. The roll has a closed or smooth cylindrical surface, and supports several press shoes (14,16) placed one after the other in the direction of web travel, each forming an elongated press nip, an each having its own circulating press belt (18,20). Each press nip has a single felt, the first felt having an open surface, and the second an open or closed surface. The felts each lie preferably between the product web and surface of the respective press shoe. One press shoe lies directly below the press roll, whilst the other is so positioned that the direction of its action towards the axis of the press roll makes an acute angle with the vertical direction of the action of the first.

Description

The invention relates to a press section of a machine for producing a Fibrous web, in particular paper and / or cardboard web, with at least one in Web running direction extended press nip through which at least one felt or Screen belt guided and the by a press roller and a flexible rotating Press belt is formed by means of a concave pressure surface Press shoe is pressed against the press roll.

The advantages of the long gap presses known per se include that the press nip is no longer essentially linear, but rather flat, so that the still wet fibrous web in the press nip over a longer distance Exposed to pressure and is thus drained more intensively. In addition, the pressure sets no longer suddenly in the press nip, this can rather be from a low one Value, for example, continuously brought to a high value, whereby the risk is countered that the fibrous web is pressed in the press nip.

In known press sections, there are usually several in the web running direction one behind the other, generally consisting of a pair of rollers Roll presses are provided so that a total of a relatively large number of Pressing and rolling results in a lot of space for the entire press section Takes up. In many cases, the decrease in the fibrous web also proves from the wire belt of the wire section and its further transfer as problematic.

In GB-A-22 18 122 and DE-A-38 98 293 press arrangements are therefore described in which a press roll with a flexible roll jacket several Forms nips with cylindrical press rolls. However, this is very constructive consuming.

In contrast, DE-U-92 06 340.3, DE-U-90 03 395.4 and the EP-A-49 69 65 press arrangements with a cylindrical press roll, which with several shoe press rolls forms extended nips. The proportions However, the rollers and their arrangement do not leave a very compact design to.

The aim of the invention is to create a press section of the type mentioned at the beginning, the extremely compact design with a minimal number of pressing points and rollers as well especially with the least possible rewetting and a volume-saving drainage one ensures the highest possible dry content of the fibrous web.

This object is achieved according to the invention in that only a single, centrally arranged, cylindrical press roll preferably larger outer diameter is provided, the at least one press shoe is opposed to an associated one to press the flexible rotating press belt against the press roll and to form a respective extended press nip.

Among other things, the invention is based on the idea the dewatering of the fibrous web at least essentially to the area of a single centrally located cylindrical press roller preferably larger outside diameter to focus, resulting in a lower overall Number of press points and rollers results in an extremely compact Structure of the press section is achieved. In particular due to the or the extended nip in the web running direction is always a drainage that is as gentle on the volume as possible ensured.

In a preferred embodiment in practice, the Outside diameter of the press roll greater than 1500 mm, being is preferably in the range of about 2000 mm.

The press roll is advantageously an internally supported Deflection roll.

Especially with regard to the highest possible dry content the fibrous web it can be advantageous if the Press roll to form several elongated press nips several Press shoes arranged one behind the other in the tape running direction opposite each other, preferably each of the press roll opposing press shoes each have a separate flexible revolving press belt is assigned.

It is particularly advantageous if at least one, preferably each extended press nip is just felted, which means a particularly gentle treatment of the fibrous web is guaranteed.

The press roll can conveniently be a closed or have a smooth roller surface. If the fibrous web in direct contact to the press roll by a respective Press nip guided, so this is already for an optimal Smoothness on the side of the press roll facing Fiber provided.

Especially in connection with such a smooth press roll is according to a particularly advantageous embodiment provided that by a front in the web running direction extended press nip with an open surface Felt or wire belt and one in the direction of web travel rear extended press nip a closed or smooth surface having felt tape is guided, wherein the felt or sieve belts preferably on the press shoe facing side of the fibrous web through the respective Press nip are performed. This is partly due to the long-lasting pressure a particularly high dry content the fibrous web in connection with one on both sides Optimal smoothness achieved, the smoothness on the the press roller opposite side of the fibrous web because of the closed or smooth surface Felt tape is effected. It is also achieved that the fibrous web in the rear extended press nip by the relevant one Felt tape practically no noteworthy marking receives.

In practice, at least one, preferably each, is flexible revolving press belt by a non-rotatable carrier circumferential, over the or the respective press shoes guided press jacket formed. Such a press jacket can be easily closed at the end so that without further notice achieved a unit that is locked to the outside can be, whereby in particular a escape from the respective Lubricant supplied to the press shoe is excluded is.

Of particular advantage is when behind in the direction of web travel the last of the dewatering of the fibrous web serving extended nip at least one between two closed or smooth surfaces formed Smoothing gap is provided.

This smoothing gap can be particularly advantageous due to the smooth roll shell of the press roll and the smooth Roller jacket of a smoothing roller opposite the press roller be formed, which makes a particularly compact press section is obtained and in particular also a low two-sidedness the fibrous web is ensured, i.e. the differences with regard to the nature of the fibrous web be kept as small as possible on both sides.

Advantageously, the press roll takes on one Sieve belt of a wire section formed fibrous web immediately from the screen belt. An additional pickup roller is accordingly no longer required, making it not just an easier one and more compact structure results, but also the Energy consumption is reduced accordingly.

The smoothing gap can also be caused by a distance from the press roll arranged smoothing press be formed. In this case is advantageously by the at least one in the area the extended press nip formed by and the smoothing gap a closed or smooth surface having guided band, the fibrous web through the smooth tape from the extended nip to the nip is transferred.

In any case, the additional smoothing gap creates a any felt markings that may occur are practically eliminated. In addition, the two-sidedness of the fibrous web is further reduced. In addition, the direction of rotation can be reversed for the transfer into the dryer section adjoining the press section be ensured. After all, one is the fibrous web gentle closed web guiding guaranteed.

In case of using a spaced from the press roll arranged smoothing press and one by the at least one Extended press nip formed in the area of the press roll and through the smoothing gap of smooth tape the fibrous web formed on the wire of the wire section advantageously taken over by the smooth tape, which is preferred happens in the area of a guide roller over which the smooth tape in the web running direction in front of the press roll is.

A particularly compact and in view of the desired Treatment of the fibrous web optimal arrangement is obtained even if a closed or smooth surface, flexible rotating press belt both over a the press roll opposite press shoe as well as a another press shoe opposite a smoothing roll is led. In this case, too, is the flexible press belt preferably again by a non-rotatable carrier encircling press jacket guided over the press shoes formed, which among other things, the above Advantages.

The arrangement is preferably made so that the smooth Press belt or the smooth press jacket on the sieve belt Sieve section of fibrous web formed directly from the sieve belt takes over so that the otherwise required additional Pickup roller can be omitted again.

In a preferred embodiment in practice again at least one, preferably each extended Press nip just felted.

In another embodiment preferred in practice is extended by a front in the web running direction Press nip is a felt tape with an open surface and an extended one in the direction of web travel Press gap on a closed or smooth surface having felt tape, which means that at less Two-sidedness and low marking again a high one Dry content can be achieved.

Further advantageous design variants are in the subclaims specified the press section according to the invention.

Figur

eine schematische Seitenansicht einer Ausführungsform einer Pressenpartie mit einer einzigen zentral angeordneten, zylindrischen Preßwalze und zwei dieser gegenüberliegenden Preßschuhen,

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

figure

2 shows a schematic side view of an embodiment of a press section with a single, centrally arranged, cylindrical press roll and two press shoes lying opposite it,

In the figure is a purely schematic representation one press section each for the production of a fibrous web 10 such as in particular a paper and / or cardboard web serving machine. The press section includes in each case at least one elongated in the web running direction L, unilaterally felted press nip P by a press roll and a flexible circumferential press belt is formed, which means a press shoe having a concave contact surface is pressed against the press roller.

In the illustrated embodiment is only a single, centrally arranged, cylindrical Press roll 12 preferably of larger outer diameter intended.

This single, centrally arranged, cylindrical press roll 12 lie two each having a concave contact surface Press shoes 14, 16 opposite to each one assigned to press flexible rotating press belt to the press roller 12 and a respective extended press nip P1 or P2 to build. Each of the two rotating flexible press belts is in each case by a rotating around a non-rotatable carrier, press jacket guided over the respective press shoe P1, P2 18 or 20 formed. So in the present case each of the two press shoes 14 and 16 a separate flexible Press jacket 18 and 20 assigned.

The outside diameter of the press roll 12 is expedient greater than 1500 mm, preferably in the range of Can be 2000 mm. The press roll 12 is one by supporting elements 22, 24 internally supported deflection compensation roller with a closed or smooth roller surface.

Through the extended nip in the web running direction L P1 is an open surface felt or Screen belt 26 and through the rear in the web running direction L extended press nip P2 a closed or smooth surface having felt tape 28 out. there the felt or sieve belt 26 coming from below is over a guide roller 30 already in front of the press nip P1 to the press roller 12 introduced with which it forms a wedge gap, in the fiber web previously taken over by the press roll 12 10 arrives. This already before the press nip P1 fibrous web 10 lying directly on the press roll 12 is practically only within the actual press nip P1 pressurized by the press jacket 18. So it is ensured that the fibrous web 10 and the felt or Sieve belt 26 does not run over a bulge that runs through give the press jacket 18 before entering the press nip P1 can. After an abrupt redirection of the fibrous web 10 is avoided, is also in this area gentle, i.e. especially distortion-free management of the Fiber web 10 guaranteed.

After the press nip P1, the felt or wire belt 26 is immediately separated from the fibrous web 10 by passing over the press jacket 18 is led down, whereupon it back again reaches guide roller 30.

The felt belt 28 is from below on the press jacket 20 in the Press nip P2 and then again via a guide roller 31 led down, whereupon it again over the press jacket 20 enters the press nip P2.

The comprehensive the press shoe 14 and the flexible press jacket 18 Long nip press unit is directly below the press roll 12 arranged, the direction of action of the bottom press shoe 14 acting upwards in a through the axis the press roll 12 extending vertical plane.

The comprehensive the press shoe 16 and the flexible roll shell 20 Long nip press unit is practically instant arranged to the right of the other long gap press unit, the press shoe 16 in relation to the press shoe 14 in the circumferential direction the press roll 12 is offset so that the respective through the axis of the press roll 12 extending directions of action of the two press shoes 14, 16 form an acute angle, something in the present embodiment is less than 45 °.

As can be seen, the outside diameter is the Press roll 12 larger than the same outer diameter the press sleeves 18, 20.

In the web running direction L behind the last one of the drainage the extended press nip P2 serving the fibrous web 10 is one formed between two closed or smooth surfaces Smoothing gap G provided. This is due to the smooth Roll jacket of the press roll 12 and the smooth roll jacket a smoothing roller 32 opposite the press roller 12 educated. Here, the roller shell of the smoothing roller 32 supported by at least one inner support member 34 and can be pressed against the press roll 12. The outside diameter of the Smoothing roller 32 is smaller than that of the press sleeves 18, 20 and thus in particular also smaller than that of the press roller 12.

The smooth press roll 12 takes over on a belt 36th a fibrous web 10 formed in the shown directly from the screen belt 36.

From the smoothing roller 32, the fibrous web 10 is one felt or sieve belt 40 guided around a guide roller 38 and a drying cylinder 42 of a dryer section.

In the illustrated embodiment, the Smoothing roller 32 arranged to the right of the press roller 12, wherein the effective direction of the at least one support element 34 is at least substantially horizontal.

The press roll 12 preferably has a rubber cover, while the one in turn arranged to the right of the press roll 12 Smoothing roller 32 has a hard cover.

The felt or wire belt 26 is both before and after extended press nip P1 in each case via a guide roller 30 guided. In contrast to the exemplary embodiment after the press nip P1 also an immediate one Separation of the felt or wire belt 26 from the press jacket 18.

The sieve belt 36 can by means of an adjustable guide roller to the press roller 12 can be brought up to and removed from this.

The felt or wire web 40 can be in the area of the smoothing roller 32 guided over two guide rollers and in between Area to take over the fibrous web 10 to the Smoothing roller 32 can be applied. From the two guide rollers can, for example, the lower one be driven.

In the illustrated The embodiment is on the outer circumference of the press roll 12 a scraper 60 arranged obliquely at the top left, the through this removed water, for example, in a collecting container 62 arrives, which is emptied accordingly.

In the area above the smoothing gap G there is also a steam blower box 64 or the like for a corresponding application the fibrous web taken over from the smoothing roller 32 10 be provided, which also with a vorzgusweise integrated, the pressure roller 12 acting scraper can be. In addition is to recognize a spray pipe 66 assigned to the press roll 12, the before the takeover of the fibrous web 10 from Screen belt 36 a water spray over the width of the roller applies to the outer surface of the press roll 12.

In the area of the screen belt brought up to the press roller 12 36 can support the takeover of the fibrous web 10 through the press roll 12, a blow pipe 68 or the like be provided.

In addition, a scraper 70 is also assigned to the smoothing roller 32, the is arranged below the smoothing roller 32.

The press shoes 14, 16 are in the usual way in particular lubricated hydrodynamically and / or hydrostatically. After this the press sleeves 18, 20 preferably closed at the end ensures that there is no lubricant penetrates to the outside.

In the embodiment, the smoothing roller has 32 an outer diameter smaller than that of Press cover 18 and thus again smaller than that of Press roll 12 is.

The smoothing gap G can also by a distance arranged from the press roll 12 smoothing press are formed, whereby by the between the press roll 12 and the Press shoe 14 and the flexible press jacket 18 comprehensive Long nip press unit formed extended press nip P2 and the smoothing gap G a closed or smooth surface having band is guided through and Fibrous web 10 from the extended press nip P2 to the Smoothing gap G is transferred. In front of the extended press nip P2 and the smoothing gap G is then the smooth band around guided a guide roller. The smooth tape takes over the formed on the wire 36 of the wire section Fiber web 10 in the area of the front, at a distance from Press nip P1 arranged guide roller.

It can in a respective press nip setting pressure curve at least be adjustable transversely to the web running direction L.

With the described embodiment of a press section the number of pressing points is reduced to a minimum. Overall, less space is required. In addition, the Number of rollers can be kept relatively small. Also is for easy acceptance and Transfer of the fibrous web provided. The respective rewetting is reduced to a minimum. In particular due to the additional smoothing gap is always one if possible low two-sidedness guaranteed. After, if necessary an additional take-off roller can be dispensed with can, there is an even more compact structure, with the Elimination of such an additional take-off roller also the Energy consumption is reduced. Overall, one is extreme volume-saving drainage ensured. by virtue of the additional smoothing gap becomes practically every remaining one Felt mark removed and the two-sidedness further decreased. Through a respective smoothing roller, too for the corresponding reversal of the direction of rotation to be taken care of manage the transfer to the dryer section. Of special Another advantage is the resulting closed Web guide. Due to the preferably closed at the front Flexible press sleeves ensure that the press shoes supplied lubricant and especially the press jacket acting coolant, for example can be about oil and water, not externally penetrates.

Claims (23)

1. Press section for a machine for producing a fibrous web (10), in particular a paper and/or board web, having a plurality of press nips (P1, P2) which are extended in the web running direction (L), through which at least one felt or mesh belt (26, 28) is guided and which are formed by a press roll (12) and a flexible circulating press belt (18, 20), which can be pressed against the press roll (12) by means of a press shoe (14, 16) having a concave pressing surface, characterized in that only a single centrally arranged, cylindrical press roll (12) with an external diameter of more than 1500 mm is provided, opposite which there are a plurality of press shoes (14, 16) arranged one after another in the web running direction, in order to press an associated flexible circulating press belt (18, 20) against the press roll (12) and to form a respective extended press nip (P1, P2), and in that two of the press shoes (14, 16) opposite the press roll (12) are offset with respect to each other in the circumferential direction of the press roll (12) such that their respective operative directions, running through the axis of the press roll (12), form an acute angle.
2. Press section according to Claim 1, characterized in that the external diameter of the press roll (12) lies in the region of about 2000 mm.
3. Press section according to Claim 1 or 2, characterized in that the press roll (12) is an internally supported controlled deflection roll.
4. Press section according to one of the preceding claims, characterized in that the press shoes (14, 16) opposite the press roll (12) are each assigned a separate flexible circulating press belt (18, 20).
5. Press section according to one of the preceding claims, characterized in that at least one, preferably each, extended press nip (P1, P2) is only single-felted.
6. Press section according to one of the preceding claims, characterized in that the press roll (12) has a closed or smooth roll surface.
7. Press section according to one of the preceding claims, characterized in that a felt or mesh belt (26) having an open surface is led through an extended press nip (P1) which is upstream in the web running direction (L), and a felt belt (28) having a closed or smooth surface is led through an extended press nip (P2) that is downstream in the web running direction (L), the felt or mesh belts (26, 28) preferably being led through the respective press nip (P1, P2) on the side of the fibrous web (10) facing the press shoe (14, 16).
8. Press section according to one of the preceding claims, characterized in that one press shoe (14) is arranged directly underneath the press roll, and in that the direction of action of this press shoe (14) lies in a vertical plane running through the axis of the press roll (12).
9. Press section according to one of the preceding claims, characterized in that at least one, preferably each, flexible circulating press belt is formed by a press cover (18, 20) which circulates around a rotationally fixed carrier (44) and is led over the respective press shoe or shoes (14, 16).
10. Press section according to one of the preceding claims, characterized in that opposite the press roll (12) there are two press shoes (14, 16) which are arranged one after another in the web running direction and over which in each case a circulating flexible press cover (18, 20) is led, and in that the external diameter of the press roll (12) is greater than the preferably mutually equal external diameters of the press covers (18, 20).
11. Press section according to one of the preceding claims, characterized in that downstream in the web running direction (L) of the last press nip (P2), serving to dewater the fibrous web (10), at least one smoothing nip (G) formed between two closed or smooth surfaces is provided.
12. Press section according to Claim 11, characterized in that the smoothing nip (G) is formed by the smooth roll cover of the press roll (12) and the smooth roll cover of a smoothing roll (32) opposite the press roll (12).
13. Press section according to Claim 12, characterized in that the roll cover of the smoothing roll (32) is supported by at least one preferably internal supporting element (34) and can-be pressed against the press roll (12).
14. Press section according to Claim 12 or 13, characterized in that the press roll (12) has a greater external diameter than the smoothing roll (32).
15. Press section according to one of the preceding claims, characterized in that the press roll (12) picks up the fibrous web (10) formed on a mesh belt (36) of a wire section directly from the mesh belt (36).
16. Press section according to one of the preceding Claims 11 to 15, characterized in that the smoothing nip (G) is formed by a smoothing press arranged at a distance from the press roll (12), in that a belt having a closed or smooth surface is led through the at least one extended press nip (P2) formed in the region of the press roll (12) and through the smoothing nip (G), and in that the fibrous web (10) is transferred by the smooth belt from the extended press nip (P2) to the smoothing nip (G).
17. Press section according to Claim 16, characterized in that the smooth belt picks up the fibrous web (10) formed on a mesh belt (36) of a wire section, preferably in the region of a guide roll, over which the said smooth belt is led upstream of the press roll (12) in the web running direction (L).
18. Press section according to one of the preceding claims, characterized in that a flexible circulating press belt having a closed or smooth surface is led both over a press shoe (14) opposite the press roll (12) and over a further press shoe opposite a smoothing roll.
19. Press section according to Claim 18, characterized in that the flexible press belt is formed by a press cover circulating about a rotationally fixed carrier and led over the press shoes (14).
20. Press section according to Claim 19, characterized in that the unit comprising the press cover and the press shoes (14) is generally arranged obliquely above the press roll (12), and in that the direction of action of the press shoe (14) opposite the press roll (12) and acting obliquely downwards lies in a plane that runs through the axis of the press roll (12) and forms an acute angle with a vertical plane running through the axis of the press roll (12).
21. Press section according to one of Claims 18 to 20, characterized in that the direction of action of the further press shoe is at least substantially perpendicular to that of the press shoe (14) which is opposite the press roll (12).
22. Press section according to one of Claims 18 to 21, characterized in that the length of the press shoe (14) opposite the press roll (12), as measured in the web running direction, is greater than that of the further press shoe.
23. Press section according to one of Claims 18 to 22, characterized in that the smooth press belt or the smooth press cover picks up the fibrous web (10) formed on a mesh belt (26) of a wire section directly from the mesh belt (36).

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