Arrangement and method for stabilising a web

Abstract

The invention relates to a method and an arrangement for stabilising a web (1) guided on a covering (9), comprising a web stabiliser (5), which has a first seal (7) and a second seal (8), wherein a removal zone (12), which can be subjected to suction via the web stabiliser (5), is formed between the first seal (7), which is formed against a first drying cylinder (2), and the second seal (8). The invention is characterised in that the second seal (8) is formed against the covering (9) in a first running distance (10) and the first running distance (10) has a length of less than 700 mm. The invention is distinguished by a reduced energy requirement and improved running properties.

Description

[0001] ARRANGEMENT AND METHOD FOR STABILIZING A TRACK

[0002] The invention relates to an arrangement for stabilizing a web, in particular for a drying section of a machine for producing the web, comprising a first drying cylinder, a second drying cylinder, a reversing roll and a web stabilizer, wherein the web stabilizer is arranged in a gusset formed by the first drying cylinder, the second drying cylinder and the reversing roll and comprises a first seal and a second seal; wherein a clothing for guiding the web can be guided around the first drying cylinder via a first train with a length of less than 500 mm to the reversing roll and around the reversing roll via a second train to the second drying cylinder;A take-off zone is formed between the first seal—formed against the first drying cylinder—and the second seal, which take-off zone can be vacuumed via the web stabilizer, wherein the web stabilizer is designed to create a negative pressure of at least 1000 Pa in the take-off zone. The invention also relates to a method for stabilizing a web guided on a fabric.

[0003] The use of web stabilizers in a dryer section of a machine for producing a web is well known and allows advantageous web removal, particularly paper or board webs, and offers the possibility of operating the machine safely at higher speeds. A disadvantage, however, is the space required by each individual web stabilizer in the gusset, i.e. in the area between the drying cylinders and the reversing roll. This is why the drying cylinders and the reversing roll must be arranged at a corresponding distance to accommodate a conventional web stabilizer. Correspondingly longer draws between the respective drying cylinders and the reversing roll mean undesirable deflection of the clothing in each draw, severe wear on the clothing and seals, and a generally higher vacuum requirement.

[0004] EP 1979534 B1 discloses a dryer group arrangement for a dryer section of a fibrous web machine with very short draws with a length of 80-400 mm, wherein a runnability component is arranged in a pocket space and comprises mechanical seals directed against the surface of the drying cylinder and against the surface of the turning cylinder. This arrangement with very short draws is advantageous with regard to the deflection of the clothing during the draw, as well as with regard to wear on the clothing and the seals.

[0005] DE 2020 1710 2453 U1 discloses an arrangement for web control on the dryer section of the fiber web machine, wherein a seal for limiting the volume subjected to negative pressure is arranged between a vacuum device and an inlet gusset.

[0006] WO 2007 085 699 A1 discloses a method in a drying section, wherein a pocket space is sealed by means of sealing elements arranged in connection with a vacuum component and placed towards the surface of the adjacent drying cylinders.

[0007] EP 0040 208 A1 relates to a device in a drying section, wherein a vacuum box is arranged so that it works against the drying fabric substantially over the entire length of the common run of the web and the drying fabric from one cylinder to the other.

[0008] DE 10200 404 5644 A1 discloses a paper machine roll, wherein the roll is arranged in connection with the paper web and the dryer fabric, and the roll causes a negative pressure by utilizing the flow at the surface structure in the sector of the roll circumference wrapped around by the web.

[0009] The aim of the invention is a web stabilizer which has a low wear of the covering or the sealing elements and an improved efficiency, ie an advantageous vacuum consumption.

[0010] This is achieved according to the invention in that the second seal is designed to seal against the clothing in the first pull. According to the inventive arrangement for stabilizing the web, the web, in particular paper or board web, can be guided in a meandering manner from the first drying cylinder to the reversing roll and further to the second drying cylinder on the clothing. The web is arranged between the respective drying cylinder and the clothing, or the clothing is arranged between the web and the reversing roll, wherein the web can be guided from the first drying cylinder to the reversing roll via the first pull and from the reversing roll to the second drying cylinder via the second pull on the clothing. In the gusset, ieThe web stabilizer is arranged in the area between the drying cylinders and the reversing roll and comprises the first seal formed against the first drying cylinder and the second seal, wherein the removal zone is formed between the first seal and the second seal. According to the invention, the clothing for guiding the web from the first drying cylinder to the reversing roll can be guided via the first short draw, which first short draw is designed with a length of less than 500 mm, which is advantageous because deflection of the clothing and subsequent wear is minimized. In a preferred embodiment, the first draw is designed with a length greater than 80 mm and preferably less than 400 mm. The length of the draw is defined as the length between contact points of a common tangent to the drying cylinder and to the reversing roll.Typically, the diameter of the drying cylinder is between 1500 mm and 2200 mm, preferably 1830 mm; and the diameter of the reversing roll is between 1200 and 1800 mm, preferably 1400 mm. According to the invention, the second seal against the clothing is formed in the first draw, with the take-off zone being capable of being suctioned via the web stabilizer. This has the advantageous effect that the take-off zone is very short and, in particular, only over a portion of the first draw, which is short according to the invention; corresponding to the design of the take-off zone between the first seal formed against the drying cylinder and the second seal formed against the clothing in the first draw.The negative pressure of at least 1000 Pa, preferably at least 2000 Pa, and particularly preferably at least 3000 Pa, created in the take-off zone thus acts only over a portion of the length of the first draw, resulting in a significantly reduced vacuum requirement and reduced energy consumption to provide the vacuum. This allows for energy-optimized take-off of the web from the first drying cylinder onto the clothing, as well as stabilization of the web on the clothing over a portion of the first draw, allowing the machine to operate safely at higher speeds.

[0011] In an advantageous embodiment of the arrangement, a first holding zone is formed between the second seal and the reversing roller, wherein the first holding zone can be vacuumed via the reversing roller or the web stabilizer. The first holding zone allows the web guided on the clothing to be vacuumed in the area between the second seal up to the contact of the clothing with the reversing roller. In the first holding zone, it is sufficient to create a lower negative pressure than in the removal zone, whereby the vacuum requirement or the energy requirement for providing the vacuum in the first holding zone is significantly reduced. Particularly preferably, the vacuuming of the holding zone takes place via the reversing roller and not via the web stabilizer.This allows the formation of both a take-off zone which is vacuumed via the web stabilizer and a holding zone in relation to the first short draw - with a length of less than 500 mm - whereby the web stabilizer still finds space in the gusset formed between the drying cylinders and the reversing roll.

[0012] Advantageously, the arrangement comprises a second holding zone formed between a third seal—enclosed by the web stabilizer and directed toward the second drying cylinder—and the reversing roll, which second holding zone can be vacuumed via the reversing roll or the web stabilizer. The second holding zone allows the web guided on the clothing to be vacuumed in the area between the reversing roll and the third seal, wherein the formation of a lower vacuum in the second holding zone is sufficient compared to the take-off zone, thus resulting in a lower vacuum requirement or energy consumption. Particularly preferably, the vacuum supply to the second holding zone takes place via the reversing roll and not via the web stabilizer.The web stabilizer thus allows the formation and suction of the take-off zone, and further the formation of the second holding zone with respect to the second draw, whereby the web stabilizer continues to be arranged in the gusset between the drying cylinders and the reversing roll.

[0013] In a particularly advantageous arrangement, the first holding zone and the second holding zone form a common zone that is vacuumed via the reversing roller, and the common zone comprises the area between the web stabilizer and the reversing roller. The common zone ensures that the same conditions with regard to suction and vacuum level are set in both the first and second holding zones. In particular, it is possible to form the first and second holding zones via the second and third seals of the web stabilizer, thus resulting in very little equipment expenditure and only wear on two seals, i.e., the second and third seals.

[0014] In a further advantageous arrangement, the second seal is designed as a mechanical seal, and preferably as a labyrinth seal comprising at least one sealing chamber, wherein the at least one sealing chamber is designed against the covering. By designing the second seal as a labyrinth seal, a contact-free seal against the covering is possible, wherein the sealing effect is based on the extension of the flow path and the increase in flow resistance by the labyrinth seal. In this case, the at least one sealing chamber is directed towards the covering. Preferably, the sealing chamber is designed as a groove, wherein the groove is designed in particular in an axial direction of the second seal. The sealing effect can be increased by forming a plurality of sealing chambers. The second seal designed as a labyrinth seal is particularly advantageous with regard to wear of the covering.Furthermore, it is particularly advantageous to design the mechanical seal, in particular the labyrinth seal, in a wedge shape. This allows for a very slim construction and is therefore optimally suited for the arrangement according to the invention. The mechanical seal, in particular the labyrinth seal, advantageously comprises at least one sealing chamber designed as a groove.

[0015] In an equally advantageous arrangement, the position of the second seal relative to the covering can be adjusted closer to or further from the covering. This allows for an improved sealing effect.

[0016] The invention also relates to a method for stabilizing a web guided on a fabric, in particular a paper or cardboard web, in an arrangement according to the invention. The web is guided:

[0017] - over the first drying cylinder between the clothing and the first drying cylinder,

[0018] - together with the clothing via a first pulley with a length of less than 500 mm and preferably less than 400 mm, to the reversing roller,

[0019] - around the reversing roller with the arrangement of the clothing between the web and the reversing roller,

[0020] - together with the clothing via a second train to the second drying cylinder and

[0021] - via the second drying cylinder between the clothing and the second drying cylinder.

[0022] According to the invention, the web is vacuumed in the take-off zone via the web stabilizer between the first seal - formed against the first drying cylinder - and the second seal, wherein the second seal is formed against the clothing in the first pull. The short take-off zone and in particular the vacuuming only over part of the length of the first pull results in a significantly reduced vacuum requirement and reduced energy requirement to provide the vacuum. In addition to the energy-optimised take-off of the web from the first drying cylinder and the stabilisation of the web on the clothing over at least part of the first pull, the machine can be operated effectively at higher speeds. Furthermore, the short length of the first pull results in a correspondingly small deflection of the clothing in the first pull and in particular in the take-off zone, which is advantageous with regard to the possible wear of the clothing at the second seal.The web is vacuumed in the take-off zone with a negative pressure of at least 1000 Pa, preferably at least 2000 Pa and particularly preferably at least 3000 Pa, which ensures a reliable transfer of the web from the first drying cylinder to the clothing.

[0023] In an advantageous embodiment of the method according to the invention, the web is vacuumed via the reversing roller in the first holding zone formed between the second seal and the reversing roller. By further vacuuming the web after the take-off zone, the web is stabilized on the clothing and, in particular, detachment of the web from the clothing or the formation of wrinkles or bubbles in the web on the clothing between the second seal and the reversing roller is avoided. The vacuuming of the first holding zone via the reversing roller is what enables the compact design of the web stabilizer, which is thus designed only to vacuum the take-off zone. Typically, the negative pressure in the first holding zone is lower than the negative pressure in the take-off zone, in particular less than 75% of the negative pressure in the take-off zone and particularly preferably less than 50% of the negative pressure in the take-off zone.Due to the short length of the first pull according to the invention and consequently the even shorter length of the first removal zone, and the lower negative pressure in the first holding zone compared to the removal zone, a correspondingly low vacuum requirement or reduced energy requirement for providing the vacuum is provided.

[0024] In an equally advantageous embodiment of the method according to the invention, the web is vacuumed via the reversing roller in the second holding zone formed between the third seal formed against the second drying cylinder and the reversing roller. This has a similarly advantageous effect, i.e. the stabilization of the web on the clothing in the second pull. Typically, the negative pressure in the second holding zone is analogous to the negative pressure in the first holding zone, wherein the negative pressure in the second holding zone is lower than the negative pressure in the take-off zone, in particular less than 75% of the negative pressure in the take-off zone and particularly preferably less than 50% of the negative pressure in the take-off zone. Thus, as a result of the lower negative pressure in the second take-off zone, the vacuum requirement is lower and the energy requirement is reduced.It is particularly advantageous for the web to be vacuumed in the first pull and in the second pull via the common zone, with the common zone being vacuumed via the reversing roll and the common zone comprising the communicating first and second holding zones. In other words, the first holding zone and the second holding zone are vacuumed via the reversing roll, with the negative pressure introduced via the reversing roll acting in both the first holding zone and the second holding zone and the holding zones being designed to communicate with each other, i.e. to be connected to each other. This allows a very compact design and is very energy-efficient in operation. Vacuuming of the reversing roll via a side surface of the reversing roll that is designed essentially normal to a rotational axis of the reversing roll is particularly advantageous. For example, vacuuming can take place via the pin designed to mount the drying cylinder.Alternatively, the ring area surrounding the pin can also be vacuumed.

[0025] The invention will now be described by way of example with reference to the drawings.

[0026] Fig. 1 shows an arrangement for stabilizing a web according to the prior art.

[0027] Fig. 2 shows a first embodiment of an arrangement according to the invention for stabilizing a web.

[0028] Fig. 3 shows a detail of the first embodiment of the arrangement according to the invention for stabilizing a web.

[0029] Fig. 4 shows a second embodiment of an arrangement according to the invention for stabilizing a web. Fig. 1 shows an arrangement for stabilizing a web according to the prior art, comprising a first drying cylinder 2, a second drying cylinder (not shown), a reversing roll 4, and a web stabilizer 5. The web stabilizer 5 is arranged in a gusset 6 formed by the first drying cylinder 2, the second drying cylinder, and the reversing roll 4, wherein a first seal 7 and a second seal 8 are included. This arrangement is disclosed in particular in EP1979534B1, wherein the web 1 guided on the clothing 9 is guided around the first drying cylinder 2 via a first draw 10 to the reversing roll 4, and the first draw 10 is designed with a length of less than 400 mm. Web stabilizers for such short draws differ fundamentally from other conventional web stabilizers, which require longer draws.According to EP1979534B1, in particular the second seal 8 is to be guided against the reversing roller 4, wherein a take-off zone 12 which is sucked via the web stabilizer 5 is designed with a vacuum corresponding to the take-off.

[0030] Fig. 2 shows a first embodiment of an arrangement according to the invention for stabilizing a web. It shows a first drying cylinder 2, a second drying cylinder 3, a reversing roll 4 and a web stabilizer 5. The web stabilizer 5 is arranged in the gusset 6 formed by the first drying cylinder 2, the second drying cylinder 3 and the reversing roll 4 and comprises a first seal 7 and a second seal 8. A clothing 9 for guiding the web 1 is guided around the first drying cylinder 2 and via a first train 10 with a length of less than 500 mm and preferably less than 400 mm to the reversing roll 4, around the reversing roll 4 and further via a second train 11 to the second drying cylinder 3. A take-off zone 12 is formed between the first seal 7 - formed against the first drying cylinder 2 - and the second seal 8.The take-off zone 12 is vacuumed via the web stabilizer 5, wherein according to the invention the second seal 8 is designed to seal against the clothing 9 in the first draw 10. Advantageously, a first holding zone 13 is formed between the second seal 8 and the reversing roll 4, wherein the first holding zone 13 is vacuumed via the reversing roll 4. Equally advantageously, a second holding zone 14 is formed between a third seal 15 - encompassed by the web stabilizer 5 and designed against the second drying cylinder 3 - and the reversing roll 4, wherein the second holding zone 14 is vacuumed via the reversing roll 4. Particularly advantageously, the first holding zone 13 and the second holding zone 14 are encompassed by a common zone 16 which is vacuumed via the reversing roll 4, wherein the common zone 16 encompasses the area between the web stabilizer 5 and the reversing roll 4.

[0031] Fig. 3 shows a detail of the first embodiment of the arrangement according to the invention, wherein the statements regarding Fig. 2 apply accordingly. In particular, the first drying cylinder 2, the reversing roll 4 and the web stabilizer 5 are shown. Furthermore, the second seal 8 of the web stabilizer 5 is shown. The take-off zone 12 is formed between the first seal (not shown) and the second seal 8 and is vacuumed via the web stabilizer 5. According to the invention, the second seal 8 is designed to seal against the clothing 9 in the first draw 10. Advantageously, the first holding zone 13 is formed between the second seal 8 and the reversing roll 4, wherein the first holding zone 13 is vacuumed via the reversing roll 4. Particularly advantageously, the second seal 8 is designed as a labyrinth seal and comprises at least one sealing chamber, wherein the at least one sealing chamber is formed against the clothing 9. In Fig.3, for example, shows a wedge-shaped labyrinth seal which comprises several sealing chambers designed as a groove.

[0032] Fig. 4 shows a second embodiment of an arrangement according to the invention for stabilizing a web. The statements made with regard to Fig. 2 and Fig. 3 also apply to the arrangement according to Fig. 4, wherein in Fig. 4 the position of the second seal 8 with respect to the covering 9 can be adjusted closer to or further from the covering 9. The second seal 8 can be connected to the web stabilizer 5, for example, via a double-hose holder, wherein the second seal 8 can be moved relative to the covering 9 by selecting the pressures in the individual hoses of the double-hose holder.

[0033] The present invention offers numerous advantages. The inventors have recognized that by designing a very short take-off zone, which extends over only part of the first, inventively short, draw, significantly reduced vacuum and energy requirements. This ensures energy-optimized take-off of the web from the first drying cylinder onto the clothing, as well as stabilizing the web on the clothing, allowing reliable machine operation at higher speeds.

[0034] Reference symbol

[0035] 1 lane

[0036] 2 first drying cylinder

[0037] 3 second drying cylinder

[0038] 4 reversing roller

[0039] 5 Orbit stabilizer

[0040] 6 gussets

[0041] 7 first seal

[0042] 8 second seal

[0043] 9 Covering

[0044] 10 First move

[0045] 11 Second move

[0046] 12 Acceptance zone

[0047] 13 First stopping zone

[0048] 14 Second stopping zone

[0049] 15 Third Seal

[0050] 16 Common Zone

Claims

Patent claims 1 . Arrangement for stabilizing a web (1), in particular for a drying section of a machine for producing the web, comprising a first drying cylinder (2), a second drying cylinder (3), a reversing roll (4) and a web stabilizer (5), wherein the web stabilizer (5) is arranged in a gusset (6) formed by the first drying cylinder (2), the second drying cylinder (3) and the reversing roll (4) and comprises a first seal (7) and a second seal (8); wherein a clothing (9) for guiding the web (1) can be guided around the first drying cylinder (2) via a first train (10) with a length of less than 500 mm to the reversing roll (4) and around the reversing roll (4) via a second train (11) to the second drying cylinder (3);wherein a take-off zone (12) is formed between the first seal (7) formed against the first drying cylinder (2) and the second seal (8), which take-off zone (12) can be suctioned via the web stabilizer (5), wherein the web stabilizer (5) is designed to form a negative pressure of at least 1000 Pa in the take-off zone (12), characterized in that the second seal (8) is designed to seal against the clothing (9) in the first pull (10); 2. Arrangement according to claim 1, wherein a first holding zone (13) is formed between the second seal (8) and the reversing roller (4), wherein the first holding zone (13) can be suctioned via the reversing roller (4) or the web stabilizer (5).

3. Arrangement according to one of claims 1 to 2, wherein a second holding zone (14) is formed between a third seal (15) - encompassed by the web stabilizer (5) and formed against the second drying cylinder (3) - and the reversing roller (4), and which second holding zone (14) can be suctioned via the reversing roller (4) or the web stabilizer (5).

4. Arrangement according to claim 3, wherein the first holding zone (13) and the second holding zone (14) form a common zone (16) which is suctioned via the reversing roller (4) and the common zone (16) comprises the area between the web stabilizer (5) and the reversing roller (4).

5. Arrangement according to one of claims 1 to 4, wherein the second seal (8) is designed as a mechanical seal, and preferably as a labyrinth seal comprising at least one sealing chamber, wherein the at least one sealing chamber is designed against the covering (9).

6. Arrangement according to claim 5, wherein the mechanical seal, in particular labyrinth seal, is wedge-shaped and preferably comprises at least one sealing chamber designed as a groove.

7. Arrangement according to one of claims 1 to 6, wherein the position of the second seal (8) with respect to the covering (9) is adjustable closer to or further from the covering (9).

8. Arrangement according to one of claims 1 to 7, wherein the first train (10) is designed with a length greater than 80 mm and preferably less than 400 mm.

9. Arrangement according to one of claims 1 to 8, wherein the web stabilizer (5) is designed to form a negative pressure of at least 2000 Pa and preferably at least 3000 Pa in the removal zone (12).

10. A method for stabilizing a web (1) guided on a covering (9), in particular a paper or cardboard web, in an arrangement according to one of claims 1 to 9; wherein the web (1) is guided: - over the first drying cylinder (2) between the clothing (9) and the first drying cylinder (2), - together with the clothing (9) via a first pulley (10) with a length of less than 500 mm and particularly preferably less than 400 mm, to the reversing roller (4), - around the reversing roller (4) with the arrangement of the clothing (9) between the web (1) and the reversing roller (4), - together with the clothing (9) via a second train (11) to the second drying cylinder (3) and - via the second drying cylinder (3) between the clothing (9) and the second drying cylinder (3); wherein the web (1) is suctioned in the take-off zone (12) between the first seal (7) formed against the first drying cylinder (2) and the second seal (8) via the web stabilizer (5), wherein the web (1) is suctioned in the take-off zone (12) with a negative pressure of at least 1000 Pa, characterized in that the web (1) is suctioned via the take-off zone (12) until the second seal (8) formed in the first pull (10) against the covering (9) is sucked.

11. The method according to claim 10, wherein the web (1) is vacuumed in the removal zone (12) with a negative pressure of at least 2000 Pa and preferably at least 3000 Pa.

12. Method according to one of claims 10 to 11, wherein the web (1) is suctioned via the reversing roller (4) in the first holding zone (13) formed between the second seal (8) and the reversing roller (4).

13. Method according to one of claims 10 to 12, wherein the web (1) is suctioned via the reversing roller (4) in the second holding zone (14) formed between the third seal (15) formed against the second drying cylinder (3) and the reversing roller (4).

14. The method according to claim 13, wherein the web (1) is suctioned in the first train (10) and in the second train (11) via the common zone (16), the common zone (16) is suctioned via the reversing roller (4) and wherein the common zone (16) comprises the first and second holding zones (13, 14) communicating with one another.

15. Method according to one of claims 12 to 14, wherein the reversing roller (4) is suctioned via a side surface of the reversing roller (4) which is formed substantially normal to a rotational axis of the reversing roller (4).

Images