EP1626920B1 - Guiding device for a continuous sheet - Google Patents

Abstract

The invention relates to a guiding device for a continuous paper sheet comprising at least one guiding element which is disposed downstream with respect to an application group and used in the form of an air circulating channel in order to ensure a contactless guiding in a machine producing and/or processing a continuous material sheet, in particular a paper or paperboard sheet. Said guiding element consists of a guiding surface made at least partially of an air-permeable porous material which is exposed to a compressed air pressure in such a way that air can circulate therethrough, thereby forming an air cushion between said guiding surface and a moving material sheet.

Description

The invention relates to a web guiding device with at least one arranged according to a coating unit serving as Airturn guide for non-contact web guide in one of the production and / or treatment of a material web, in particular paper or board web, serving machine. It further relates to a machine for producing and / or treating a material web, in particular paper or board web, with at least one such web guide device.

So far, the web is guided over a conventional Airturn. Thus, while a contactless guide is possible with the guide member, but in the air cushion there is usually a non-uniform pressure. In the case of holes or partial breaks, the web can nevertheless still touch the guide element. In addition, no reliable, flat and wrinkle-free web guide is guaranteed. So it can come to so-called omega wrinkles in particular. A corresponding track guide is again relatively expensive. It requires large amounts of air and large dimensions.

A web guide, which is considered to be the closest prior art, is disclosed in US 5,957,360.

The invention has for its object to provide an improved web guide device of the type mentioned, in which the aforementioned disadvantages are eliminated. In particular, a stable wrinkle-free and reliable, non-contact web guide should be achieved. In particular, it should be possible to use in paper machines, coating machines, calenders, slitter machines, etc.

The object is achieved in that the guide element has a guide surface, which consists at least partially of air-permeable porous material which can be acted upon with compressed air to form an air cushion over the air flowing through this porous material between the guide surface and the moving material web.

The high pressure loss on the porous material produces a very uniform air cushion, so that the material web is reliably guided at a relatively small distance from the surface. This brings in particular a wrinkle-free run with it. The relatively high internal pressure prevents any web contact with the surface.

In particular, the web guide device can therefore comprise at least one guide element which is supplied with compressed air and has an open surface, but with a high pressure loss, through which air is forced from the inside. Thus, a stable uniform air cushion is generated both in time and space, which leads the web without contact with the guide element.

Preferably, the guide element comprises at least one pressure chamber, via which the porous material can be acted upon with compressed air. In this case, the porous material may be at least partially applied to a carrier containing the pressure chamber, provided with air passage openings. However, for example, in particular, such embodiments are conceivable in which the porous material forms at least a part of the pressure chamber wall.

The pressure in the pressure chamber may in particular be greater than 0.5 bar, wherein it is preferably greater than 1 bar.

The specific volume flow in the porous material is suitably in a range of about 10 to about 5000 Nm ³ / h · m ² .

The hole or pore distance or the distance of the outlet openings of the air-permeable porous material is preferably less than 1 mm.

The porous material is in particular such that no individual jets, but instead a very uniform air cushion is generated, whereby a very good web guide is ensured, which remains contact-free in any case, especially in holes, cracks or straps. In a preferred practical embodiment of the web guiding device according to the invention, the mean size of the outlet openings, pores and / or holes of the porous material is less than 0.2 mm and preferably less than 0.1 mm.

Preferably, the porous material is chosen so that there is a high pressure loss from the inside to the environment, whereby a very uniform air cushion is generated. In an expedient practical embodiment of the web guiding device according to the invention is the Pressure loss in particular from the side facing away from the moving material web side to the web of material facing side of the porous material greater than 0.2 bar and preferably greater than 0.8 bar.

The thickness of the air cushion formed between the guide surface and the moving material web and thus the web distance to the surface is expediently less than 5 mm and preferably less than 3 mm.

The guide element can be designed in particular as a roller. It can be designed as a standing or non-rotating roller or as a rotating, preferably driven roller.

In particular, in the case that the guide element is designed as a standing or non-rotating roller, the air cushion is advantageously produced only on a part of the roll circumference.

For example, the roller may have a diameter in a range of about 50 mm to about 1500 mm.

In an expedient practical embodiment, the guide element is wrapped only by the material web. In principle, however, such embodiments are also conceivable in which the guide element is surrounded not only by the material web but also by at least one moving belt, in particular a wire belt. In the latter case, the moving belt, in particular wire belt, be guided between the guide element and the material web or on the side facing away from the guide element side of the material web, ie lie outside.

The material web or the moving belt can wrap around the guide element, for example, in accordance with a wrap angle whose range is from about 5 to about 260 °.

Of particular advantage is also when the guide element is designed as a bow segment. It may have a constant radius of curvature in the machine direction or a radius of curvature changing in the machine direction. In the latter case, the guide element may have a continuously varying radius of curvature in the machine direction or a radius of curvature varying in the machine direction in discrete steps.

In order to produce a spreader effect, the guide element or its guide surface can in particular also have a curved course in the transverse direction. In this case, the radius of curvature of the guide element or of the guide surface can change over the width extending in the transverse direction.

If the guide element is designed as a curved segment, then it expediently has a segment height in a range from approximately 30 to approximately 500 mm.

The radius of curvature of the guide surface is suitably in a range of about 5 to about 3000 mm.

In a preferred practical embodiment of the web guiding device according to the invention, the guide element is composed in the transverse direction and / or in the machine direction of several individual segments.

In this case, at least a part of the segments can be assigned a common compressed air supply. However, the segments can also be supplied at least partially via separate compressed air supplies.

In a preferred practical embodiment of the web guiding device according to the invention, a zone-wise separate compressed air supply is provided via individual separate segments and / or segment groups in the machine running direction and / or in the transverse direction. In the machine direction or transverse direction, therefore, a special zonal pressure graduation can take place.

According to the invention, the guide surface of the guide element is formed by two layers, namely an inner layer facing away from the material web and an outer layer of air-permeable porous material having preferably different properties.

In this case, for example, the pressure loss at the side facing away from the material web inner layer may be smaller than at the outer layer. Alternatively or additionally, the porosity of the inner layer facing away from the web of material may be higher or the hole spacing greater than in the outer layer. Alternatively or additionally, the hole diameter at the side facing away from the material web inner layer may be greater than at the outer layer. It is particularly advantageous if the layers at least partially made of different materials.

A further preferred embodiment of the web guiding device according to the invention is characterized in that the material from the mate rialbahn facing away from the inner layer only in a portion of air-permeable porous material or is provided with air passage openings and otherwise is impermeable to air, so that only in a partial region of the guide element, an air cushion is generated.

The facing away from the web inner layer may at least partially, in particular made of metal, fiberglass and / or CFK.

The inner layer facing away from the material web preferably provides the mechanical load carrying capacity of the guide element or of the guide surface.

The material web facing the outermost surface of the guide element may consist in particular of finely porous material. In particular, it can therefore have a finer degree of porosity than the inner layer.

It is also advantageous, in particular, if the outermost surface of the guide element facing the material web is sintered.

However, this the material web facing outermost surface of the guide element may for example also consist of ceramic material.

It is also particularly advantageous if the outermost surface of the guide element facing the material web is easy to clean, ie, for example, consists of an easy-to-clean material.

Advantageously, the guide surface of the guide element is provided with air outlet openings preferably produced directly during the production of the outermost surface. The relevant air outlet openings Therefore, they do not have to be introduced into the outermost surface by subsequent processing.

As already mentioned, the web guiding device according to the invention can be used in particular in a machine for producing and / or treating a material web, in particular a paper or board web.

Preferably, after, in particular immediately after, e.g. the surface treatment serving order aggregate is provided as a replacement for an Airturn at least one corresponding web guide device. Due to the small path distance and the uniform air cushion a wrinkle-free guidance is ensured here. Further advantages result from the lower air volume and the smaller construction volume.

The guide element can, for example, only be looped around by the material web or be looped around except for the material web, for example by at least one screen belt.

In an advantageous practical embodiment, at least one corresponding web guide device is provided as a replacement for a respective spreader roll.

If the guide element in question is provided as a rotatably mounted roller, this also results in good emergency running properties, since friction between the material web or a moving belt, eg wire belt and the rotating roller, can not occur even if the pressure supply fails.

In the case of a multilayer structure of the guide surface, the pressure loss of the layers may increase from the inside to the outside. The porosity can decrease from the inside out. The hole spacing can decrease from the inside out. The hole diameter can also decrease from the inside to the outside.

As order aggregate are u. a. For example, also different coating units conceivable.

In order to be able to guide the material web safely and without wrinkles, it is advantageous to arrange at least one web guiding device immediately before, preferably also immediately after, a contactless drying path.

The contactless drying sections are generally designed as infrared and / or Konvektionstrockener. Non-contact drying is required in particular for coated or very moist material webs.

The guide elements of the web guide cleaning form with the material web only a relatively thin air cushion, which minimizes the risk of wrinkling. In addition, the guide elements require relatively little compressed air.

The guide elements of the web guiding device can also be assigned contactless drying devices to intensify the drying of the material web. These drying devices are located opposite the guide elements.

Figur 1

eine schematische Querschnittsdarstellung eines der berührungslosen Bahnführung dienenden Leitelements mit einer zumindest teilweise aus porösem Material bestehenden Leitfläche,

Figur 2

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform des Leitelements, das beispielsweise in Form eines Bogen-Segments ausgeführt ist,

Figur 3

eine schematische Längsschnittsdarstellung einer weiteren Ausführungsform des Leitelements, das in Querrichtung in zumindest zwei Zonen oder Segmente unterteilt ist, wobei im vorliegenden Fall die verschiedenen Segmente mit gleichem Druck beaufschlagt sind,

Figur 4

eine mit der Ausführung gemäß Figur 3 vergleichbare Ausführungsform des Leitelements, wobei im vorliegenden Fall die verschiedenen Segmente jedoch mit unterschiedlichem Druck beaufschlagt sind,

Figur 5

eine schematische Darstellung eines in Querrichtung durchgebogenen, beispielsweise zum Breitstrecken einsetzbaren Leitelements,

Figur 6

eine schematische Darstellung einer bevorzugten Ausführungsform, bei der ein Leitelement nach einem Auftragsaggregat als Ersatz für einen Airturn vorgesehen ist und

Figur 7

eine schematische Darstellung einer kontaktlosen Trokkenstrecke mit Leitelement.

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

FIG. 1

2 a schematic cross-sectional view of a non-contact web guide serving guide element with an at least partially made of porous material guide surface,

FIG. 2

a schematic cross-sectional view of another embodiment of the guide element, which is designed for example in the form of a sheet segment,

FIG. 3

3 is a schematic longitudinal sectional view of a further embodiment of the guide element, which is subdivided transversely into at least two zones or segments, wherein in the present case the different segments are subjected to the same pressure,

FIG. 4

a comparable with the embodiment of Figure 3 embodiment of the guide element, but in the present case, the different segments are subjected to different pressure,

FIG. 5

a schematic representation of a transversely bent, for example, usable for spreading guide element,

FIG. 6

a schematic representation of a preferred embodiment in which a guide element is provided after a coating unit as a substitute for an Airturn and

FIG. 7

a schematic representation of a contactless dry track with guide element.

Figure 1 shows a schematic representation of a first embodiment of the non-contact web guide serving guide element 10 of a web guide device, which is particularly used in one of the production and / or treatment of a material web, in particular paper or board web, serving machine. In this case, such a guide element 10, such. described in more detail below, in particular after a coating unit 34 may be provided as a replacement for an Airturn (see, in particular Figure 6).

The running in the present case, for example in the form of a roller guide element 10 has a guide surface 12, which consists of air-permeable porous material 14 which is acted upon from the inside with compressed air to a through the porous material 14 through flowing air 16 and the moving web Air cushion 18 to form.

The guide element 10 comprises at least one pressure chamber 20, via which the porous material 14 can be acted upon with compressed air.

As shown, the guide element 10 may comprise, for example, a carrier 24 containing the pressure chamber 20 and provided with at least one and preferably a plurality of air passage openings 22, on which the porous material 14 is applied. In the present case, this here, for example, roller-shaped carrier 24 is completely surrounded by porous material 14 in the circumferential direction. However, the wall of the pressure chamber 20 is provided only over part of its circumference with air passage openings 22, so that the air cushion 18 is generated only over part of the circumference of the guide element 10. Appropriately, the air cushion 18 generates at least in the area in which the material web wraps around the guide element 10.

Due to the roller-shaped design, the guide element 10 has a radius of curvature, in particular also in the wrap area in the machine direction L.

FIG. 2 shows, in a schematic cross-sectional representation, a further embodiment of the guide element 10, which is embodied here, for example, in the form of a sheet segment. Via a pressure chamber 20, the relevant segment is again supplied with compressed air, so that air 16 flows from the inside to the outside through the porous material 14. Also in the present case, the porous material 14 is again applied externally on a carrier 24 containing the pressure chamber 20. The wall of the carrier 24 and the pressure chamber 20 is again provided with air passage openings 22 through which the porous material 14 is pressurized from the inside with compressed air.

As can be seen with reference to FIG. 2, the guide element 10 or its guide surface 12 is curved again in the machine direction L in the present case as well. As in the case of the embodiment according to FIG. 1, the radius of curvature over the looping region is also constant, for example.

FIG. 3 shows, in a schematic longitudinal section, a further embodiment of the guide element 10. In this case, the guide element 10 or its pressure chamber is subdivided transversely into at least two zones or segments 20 ', 20 "over which the porous material 14 may be separated in the transverse direction In the phase shown in FIG. 3, the zones 20 ', 20 "are at least temporarily in contact with compressed air applied to the same pressure. By contrast, FIG. 4 shows the same guide element 10 in a phase in which the zones or segments 20 ', 20 "are being subjected to different pressure.

Thus, the pressure can vary across the width, i.e., across the width requirements. be varied in the desired manner in the transverse direction.

Moreover, the guide element 10 may at least substantially in particular again have such a structure, as has been described in connection with the other embodiments. Corresponding parts are assigned the same reference numerals.

Figure 5 shows a schematic representation of a transversely bent, for example, for spreading usable guide element 10. The guide again has a at least one pressure chamber 20 having carrier 24 on which the porous material 14 is mounted and the pressure chamber 20, the porous material 14 from the inside Her compressed air is applied.

With a corresponding rotation of the guide element 10, for example, the effective deflection radius can be changed.

Moreover, this embodiment may at least substantially again have the same structure as the previously described embodiments. Corresponding parts are assigned the same reference numerals.

While in the embodiments described above, the porous material 14 is mounted in each case on a provided with air passage openings 22 carrier 24, in principle, at least a part a support wall or at least part of the wall of the pressure chamber 20 may be formed by the porous material 14.

In the illustration according to FIG. 6, a guide element 10 ₁ after the drying section 32 and in front of a coating unit 34, a guide element 10 ₂ as a replacement for an air tunnel between the application unit 34 and, for example, an impingement dryer 36 and a guide element 10 ₃ after the impingement Dryers 36 arranged. The guide elements 10 can in particular be designed again as described above, for example, with reference to FIGS. 1 to 5.

For example, it is also possible to provide at least one guide element 10 in a coating machine, in front of a reel-up and / or after a dispenser.

In the embodiment according to FIG. 7, the material web 28 runs through a contactless drying section 38 in which the material web 28 is blown on both sides with hot air.

In order to be able to guide the material web 28 directly before and after this drying section safely and without risk of wrinkling, there is a guide element 10 at the beginning and at the end of the drying section 38. To intensify the drying, the material web 28 is additionally provided opposite the guide elements 10 arranged drying devices 37 blown with hot air.

LIST OF REFERENCE NUMBERS

10

vane

12

baffle

14

porous material

16

air flowing through

18

bubble

20

pressure chamber

22

Air passage opening

24

carrier

26

Press, press section

28

web

30

drying cylinders

32

drying section

34

application unit

36

Impingement dryer

37

drying device

38

contactless drying line

Claims (54)

1. Web guide device having at least one guide element (10) arranged after an applicator unit (34) and serving as an air turn for non-contact web guidance in a machine used for the production and/or treatment of a material web (28), in particular a paper or board web, where the guide element (10) has a guide surface (12) which, at least to some extent, consists of air-permeable porous material (14) to which compressed air can be applied, in order to form an air pad (18) between the guide surface (12) and the moving material web (28) via the air (16) flowing through this porous material (14) , characterized in that the guide surface (12) of the guide element (10) is formed by two layers, specifically an inner layer, facing away from the material web, and an outer layer, consisting of air-permeable porous material with different properties.
2. Web guide device according to Claim 1, characterized in that the guide element (10) comprises at least one pressure chamber (20), via which the porous material (14) can have compressed air applied to it.
3. Web guide device according to Claim 2, characterized in that the porous material (14) can be applied, at least to some extent, to a carrier (24) containing the pressure chamber (20) and provided with air passage openings (22).
4. Web guide device according to Claim 2 or 3, characterized in that the porous material (14) forms at least part of the pressure chamber wall.
5. Web guide device according to one of the preceding claims, characterized in that the pressure in the pressure chamber (20) is higher than 0.5 bar and preferably higher than 1 bar.
6. Web guide device according to one of the preceding claims, characterized in that the specific volume flow in the porous material lies in a range from about 10 to about 5000 Nm³/h·m².
7. Web guide device according to one of the preceding claims, characterized in that the hole or pore spacing or the spacing of the outlet openings of the air-permeable porous material (14) is less than 1 mm.
8. Web guide device according to one of the preceding claims, characterized in that the average size of the outlet openings, pores and/or holes in the porous material (14) is less than 0.2 mm and preferably less than 0.1 mm.
9. Web guide device according to one of the preceding claims, characterized in that the pressure loss from the side facing away from the moving material web (28) to the side of the porous material (14) facing the material web (28) is greater than 0.2 bar and preferably greater than 0.8 bar.
10. Web guide device according to one of the preceding claims, characterized in that the thickness of the air pad (18) formed between the guide surface (12) and the moving material web (28) is less than 5 mm and preferably less than 3 mm.
11. Web guide device according to one of the preceding claims, characterized in that the guide element (10) is designed as a roll.
12. Web guide device according to Claim 11, characterized in that the guide element (10) is designed as a stationary or nonrotating roll.
13. Web guide device according to Claim 12, characterized in that the air pad (18) is produced on only part of the circumference of the roll.
14. Web guide device according to Claim 11, characterized in that the guide element (10) is designed as a rotating, preferably driven, roll.
15. Web guide device according to one of the preceding claims, characterized in that the roll has a diameter in a range from about 50 mm to about 1500 mm.
16. Web guide device according to one of the preceding claims, characterized in that the guide element (10) is wrapped around only by the material web (28).
17. Web guide device according to one of Claims 1 to 15, characterized in that the guide element (10) is also wrapped around by at least one moving belt, in particular a fabric belt, in addition to the material web (28).
18. Web guide device according to Claim 17, characterized in that the moving belt, in particular fabric belt, is guided between the guide element (10) and the material web (28).
19. Web guide device according to Claim 17, characterized in that the moving belt, in particular fabric belt, is guided on the side of the material web (28) facing away from the guide element (10).
20. Web guide device according to one of the preceding claims, characterized in that the material web (28) and/or the moving belt wraps around the guide element in accordance with a wrap angle whose range is from about 5 to about 260°.
21. Web guide device according to one of the preceding claims, characterized in that the guide element (10) is designed as a segment of a curve.
22. Web guide device according to Claim 21, characterized in that the guide element (10) has a radius of curvature which is constant in the machine running direction (L).
23. Web guide device according to Claim 21, characterized in that the guide element (10) has a radius of curvature which changes in the machine running direction (L).
24. Web guide device according to Claim 22, characterized in that the guide element (10) has a radius of curvature which changes continuously in the machine running direction (L).
25. Web guide device according to Claim 22, characterized in that the guide element (10) has a radius of curvature which changes in discrete steps in the machine running direction (L).
26. Web guide device according to one of the preceding claims, characterized in that the guide element (10) or its guide surface (12) has a course which is curved in the transverse direction.
27. Web guide device according to Claim 26, characterized in that the radius of curvature of the guide element (10) or the guide surface (12) changes over the width extending in the transverse direction.
28. Web guide device according to one of the preceding claims, characterized in that the guide element (10) designed as a segment of a curve has a segment height in a range from about 30 to about 500 mm.
29. Web guide device according to one of the preceding claims, characterized in that the radius of curvature of the guide surface (12) lies in a range from about 5 to about 3000 mm.
30. Web guide device according to one of the preceding claims, characterized in that the guide element (10) is assembled from a plurality of individual segments (20', 20") in the transverse direction and/or in the machine running direction (L).
31. Web guide device according to Claim 30, characterized in that at least some of the segments (20', 20" ) are assigned a common compressed air supply.
32. Web guide device according to Claim 30 or 31, characterized in that the segments (20', 20") are at least to some extent assigned separate compressed air supplies.
33. Web guide device according to one of the preceding claims, characterized in that an application of compressed air which is separated zone by zone via individual separate segments (20', 20") and/or segment groups in the machine running direction (L) and/or in the transverse direction is provided.
34. The web guide device according to one of the preceding claims, characterized in that the pressure loss in the inner layer, facing away from the material web (28), is lower than on the outer layer.
35. Web guide device according to one of the preceding claims, characterized in that the porosity of the inner layer, facing away from the material web (28), can be higher or its hole spacing can be greater than in the outer layer.
36. Web guide device according to one of the preceding claims, characterized in that the hole diameter of the inner layer, facing away from the material web (28), is greater than in the outer layer.
37. Web guide device according to one of the preceding claims, characterized in that the layers consist, at least to some extent, of different material.
38. Web guide device according to one of the preceding claims, characterized in that the inner layer, facing away from the material web (28), consists of an air-permeable porous material (14) or is provided with air passage openings (22) only in a subregion and is otherwise air-impermeable, so that an air pad (18) is produced only in a subregion of the guide element (10).
39. Web guide device according to one of the preceding claims, characterized in that the inner layer, facing away from the material web (28), consists, at least to some extent, of metal, GRP and/or CRP.
40. Web guide device according to one of the preceding claims, characterized in that the inner layer, facing away from the material web (28), supplies the mechanical loadbearing capacity of the guide element (10) or of the guide surface (12).
41. Web guide device according to one of the preceding claims, characterized in that the outermost surface of the guide element (10), facing the material web (28), consists of finely porous material.
42. Web guide device according to one of the preceding claims, characterized in that the outermost surface of the guide element (10), facing the material web (28), is sintered.
43. Web guide device according to one of the preceding claims, characterized in that the outermost surface of the guide element (10), facing the material web (28), consists of ceramic material.
44. Web guide device according to one of the preceding claims, characterized in that the outermost surface of the guide element (10), facing the material web (28), consists of a material which can be cleaned easily.
45. Web guide device according to one of the preceding claims, characterized in that the guide surface (12) of the guide element (10) is provided with air outlet openings (22) preferably produced directly during the production of the outermost surface.
46. Machine for the production and/or treatment of a material web (28), in particular a paper or board web, having at least one web guide device according to one of the preceding claims.
47. Machine according to Claim 46, characterized in that at least one appropriate web guide device is preferably provided immediately after an applicator unit (34), as a replacement for an air turn.
48. Machine according to Claim 47, characterized in that the guide element (10) is wrapped around only by the material web (28).
49. Machine according to Claim 47, characterized in that the guide element (10) is wrapped around by at least one fabric belt (33, 40) in addition to the material web (28).
50. Machine according to one of the preceding claims, characterized in that at least one appropriate web guide device is provided as a replacement for a respective spreader roll.
51. Machine according to one of Claims 46 to 50, characterized in that at least one web guide device is arranged immediately before a non-contact drying section.
52. Machine according to Claim 51, characterized in that at least one web guide device is arranged immediately after a non-contact drying section.
53. Machine according to Claim 51 or 52, characterized in that the non-contact drying section is designed as an infrared and/or convection dryer.
54. Machine according to one of Claims 46 to 53, characterized in that the material web (28) is assigned a non-contact drying apparatus (37), at least in the wrap region of a web guide device.

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