DE102020128265A1 - Alternative suction roll concept - Google Patents

Abstract

The invention relates to a suction device (10) for safely guiding or transferring a fibrous web, in particular a glass fiber, nonwoven or paper web, comprising a first and a second guide roller (12, 14), a suction box (16) arranged between them, and a the two guide rollers (12, 14) and the suction box (16) guided, permeable clothing (18), wherein the suction box (16) has an active surface (20) which is designed, during normal operation, to apply a negative pressure to the air over the active surface ( 20) guided clothing (18) and on the fibrous web transported thereon, the active surface (20) being arranged and dimensioned in such a way that it covers essentially the entire path that the clothing (18) travels between the two guide rollers (12, 14) put back, bridged. Further aspects of the present invention relate to a machine for producing or finishing a fibrous web with at least one such suction device and the use of such a suction device.

Description

The invention relates to a suction device for safely guiding or transferring a fibrous web, such as in particular a glass fiber, nonwoven or paper web, comprising a first and a second guide roller, a suction box arranged between them, and a permeable fabric guided over the two guide rollers and the suction box. wherein the suction box has an active surface which is designed to exert a negative pressure on the clothing guided over the active surface and on the fibrous web transported thereon during normal operation. Further aspects of the present invention relate to a machine for producing or finishing a fibrous web with at least one such suction device and the use of such a suction device.

Both guide rolls and suction boxes are regularly used, for example, in the forming section of a paper machine, so that the combination of the aforementioned features is state-of-the-art, even if the suction boxes are usually only used to dehumidify the fibrous web and not to guide it safely or have the same transfer.

If, on the other hand, the task is either to transfer the fibrous web between two different drive groups, or to hold the fibrous web securely on a clothing while another clothing is being guided away from the fibrous web, this is often the case in machines for the production or finishing of fibrous webs suction rollers are used. The transfer between different drive groups can be, for example, the transfer between the forming section and the press section of a paper machine, or the transfer from a felt of a first press assembly to the felt of a second press assembly within the press section.

Suction rolls with a very large open area are required in particular when the fibrous web comprises long fibers or is largely formed from them, for example in the case of very open papers or nonwovens or glass fiber webs. This requirement is based on the fact that the holes in the roll mantle of conventional suction rolls, which have only a relatively small open area, quickly become clogged with fibers.

Although there are such suction rolls with a large open area that are suitable for the production or finishing of fibrous webs with long fibers, they have various disadvantages. On the one hand, their structure is complex, since there are special requirements, for example, for sealing strips and spray pipes. In addition, the user of such suction rollers should always have a reserve roller in the vicinity of the machine. On the other hand, these rollers develop a noise level during operation that cannot be ignored. This is due to the fact that the vacuum in the holes in the roll shell collapses as soon as the same move out of the vacuumed zone of the suction roll.

In addition, suction rollers are sucked off by fans or water ring air pumps. A significant proportion of the suction volume flow is required in order to adapt the open area of the suction area to the negative pressure of the suction area. This makes the operation of these suction rolls energy-consuming and expensive.

Although in principle there is also the possibility in slow-running machines to use a suction box with a fixed surface instead of such a suction roll, the clothing guided over the suction box, which is usually also strongly deflected in the suctioned area, is exposed to a great deal of wear.

It is the object of the present invention to overcome or at least reduce all or at least some of the aforementioned disadvantages.

This object is solved by the features of the independent claims. However, advantageous developments are the subject matter of the dependent claims.

According to the invention, the generic suction device described at the outset is developed in such a way that the active surface is arranged and dimensioned in such a way that it essentially bridges the entire path covered by the clothing between the two guide rollers. In this context, the term “substantially” means that at least 70%, preferably at least 90%, more preferably at least 95% of the path is bridged.

In the solution according to the invention, the two guide rollers ensure that the clothing with the fibrous web transported on it can be guided and deflected with little wear. The rollers can be constructed in a very simple manner, which makes their purchase and operation cheap. Preferably, the rolls are not suctioned, so that a vacuum does not collapse in the holes in the roll shell, which enables low-noise operation. Holding the fibrous web on the per Meablen covering is carried out by the negative pressure from the suction box. As a static element, the suction box can also have a very simple structure and be easy to clean. Since the function of guiding and deflection is primarily covered by the guide rollers, the wear between the active surface of the suction box and the clothing guided over this active surface can be kept very low.

The inventors have recognized that it is important in order to be able to effectively replace suction rolls with their disadvantages described above with the suction device according to the invention that the effective surface of the suction box extends essentially over the entire path between the two guide rolls. This is the only way to ensure that the suction or holding effect is already effective very close to the respective guide roller.

In order to make this possible and to optimally fit the suction box into the free area between the two adjacent guide rolls, it is advantageous if the suction box also has a first curved side wall adapted to the diameter of the first guide roll and/or a second side wall adapted to the diameter of the second Has adapted guide roller, curved side wall. Both side walls are preferably curved accordingly.

In addition, the suction box can have a connection on one of its two end faces between the two guide rollers, by means of which the suction box is or can be connected to a vacuum source.

The suction box can thus essentially consist of two side walls curved in accordance with the radii of the guide rollers, two end plates - namely on the guide and drive side - extending between the two guide rollers, of which at least one has a vacuum connection, a covering facing the clothing, which Defined active surface and is more or less open, and be formed a cover facing away from the fabric.

In particular, if fibrous webs of different widths are to be produced or finished in the machine in which the suction device according to the invention is used, it is advantageous if the suction box also includes at least one format slide, with which the width of the active surface can be adjusted to the width of the fibrous web or adjustable. The suction box preferably comprises at least one format slide on each of its two side edges.

Furthermore, it can be advantageous if the suction device comprises a further guide roller and a further suction box over which the clothing is guided, the further suction box having a further active surface which is designed to apply a negative pressure to the guided over the further active surface during normal operation clothing and on the fibrous web transported thereon, and wherein the further active surface is arranged and dimensioned in such a way that it essentially bridges the entire path covered by the clothing between the further guide roller and one of the two guide rollers of the first and second guide roller. In this way it is possible to provide several zones of different pressure and/or to achieve gentler deflections.

With regard to the different pressure zones, it is preferably provided that the further suction box is designed, during normal operation, to exert a different, in particular stronger, negative pressure on the clothing and on the fibrous web transported on it than the negative pressure of the suction box between the first and second guide roller . For example, the fibrous web can first be picked up from another clothing with the stronger vacuum against the clothing ("pick-up zone") and then transferred with a lower vacuum ("holding zone"). A low negative pressure can be achieved, for example, by the fact that the negative pressure inside the suction box (for the "holding zone") is already lower than the negative pressure inside the other suction box (for the "pick-up zone") and/or with the same negative pressure in the two suction boxes due to a different open area on the two surfaces.

With regard to the gentler deflection, it is advantageous if the axes of rotation of the first guide roller, the second guide roller and the further guide roller do not lie in a common plane. In particular, they can be arranged on a cylinder surface. This enables all three rolls to be supported by a common support roll.

In general, it can be advantageous if the suction device also includes a support roller, which is arranged on a side of the first and second guide roller, and possibly the further guide roller, facing away from the clothing and is in supportive contact with these guide rollers. As a result, the guide rollers themselves can be designed to be relatively small and handy, but without there being the risk of them being impermissibly deformed by the forces which the deflected clothing acts on them. Of course, the use of a common backup roll requires that all supported by this backup roll guide rolls have substantially the same diameter. However, it is in any case advantageous to design all the guide rollers identically, since the provision of a single replacement guide roller is generally sufficient.

The suction box can be constructed in a particularly simple manner if the active surface is essentially flat, so that the clothing and the fibrous web transported on it are guided in a straight line from the first guide roller to the second guide roller during normal operation. This also minimizes wear and tear caused by friction between the active surface and the covering.

However, under certain circumstances it may also be advantageous to design the active surface to be essentially curved, so that the clothing and the fibrous web transported on it are not guided in a straight line from the first guide roller to the second guide roller during normal operation. However, the curvature should not be too pronounced anywhere, or the minimum radius of curvature that the active surface has should be selected to be large enough to keep the wear during the deflection low.

As already mentioned at the beginning, it is important for the safe guiding or transfer of a fibrous web with long fibers that the vacuumed area includes as large an open area as possible. It is therefore proposed that the effective area has an open area of between 20% and 100%, preferably between 50% and 100%, more preferably between 70% and 100%. In fact, in extreme cases, the open area can even be 100%, which means that the side of the suction box facing the clothing—apart from the format slides, if applicable—is essentially completely open. In most cases, however, it should be preferable to support the clothing in this area by means of a support structure, for example by means of a plurality of struts aligned parallel to one another and spaced apart, which preferably extend orthogonally to the direction of movement of the clothing in normal operation. Care should be taken to ensure that the material of the support structure is chosen so that the coefficient of sliding friction between the support structure and the covering is as low as possible. For this purpose, the support structure can have a ceramic surface, for example.

A further aspect of the present invention relates to a machine for producing or finishing a fibrous web, such as in particular a glass fiber, nonwoven or paper web, comprising at least one suction device according to the invention as described above.

Another aspect of the present invention relates to the use of such a suction device for transferring, preferably in a closed train, a fibrous web, in particular one with long fibers, between two sections in a machine for producing or finishing the fibrous web or between two functional units of these sections. When transferring the fibrous web, the suction device according to the invention can make particularly good use of its advantages.

In particular when the suction device comprises a further guide roller and a further suction box, as described above, it can be used as a replacement for a pick-up roller. To this end, it is advantageous if the active surface between the first guide roller and the second guide roller provides a holding zone, while the other active surface provides a pick-up zone, with the negative pressure that is exerted on the clothing and in the holding zone the fibrous web being transported on it is different from the vacuum that is exerted on the clothing and the fibrous web transported on it in the pick-up zone. For the sake of simplicity, both suction boxes can be connected to the same vacuum source, but have coverings with different open areas.

• 1 a eine erste Ausführungsform einer erfindungsgemäßen Saugvorrichtung;
• 1b eine Abwandlung der ersten Ausführungsform gemäß 1a;
• 2 eine zweite Ausführungsform einer erfindungsgemäßen Saugvorrichtung;
• 3 eine Überführvorrichtung mit einer Saugwalze aus dem Stand der Technik;
• 4 eine Kombination aus erster und zweiter Ausführungsform der erfindungsgemäßen Saugvorrichtung, welche als Ersatz für die Überführvorrichtung gemäß 3 eingesetzt werden kann;
• 5 eine dritte Ausführungsform der erfindungsgemäßen Saugvorrichtung.

The invention is illustrated in more detail below using different exemplary embodiments, these being illustrated in schematic figures. Show it:

• 1 a a first embodiment of a suction device according to the invention;
• 1b according to a modification of the first embodiment 1a ;
• 2 a second embodiment of a suction device according to the invention;
• 3 a transfer device with a suction roll from the prior art;
• 4 a combination of the first and second embodiment of the suction device according to the invention, which as a replacement for the transfer device 3 can be used;
• 5 a third embodiment of the suction device according to the invention.

In 1a is shown schematically a relatively simply constructed, first embodiment of a suction device 10 according to the invention. The suction device 10 comprises a first guide roller 12, a second guide roller 14 and a suction box 16 arranged between the two guide rollers 12, 14. The suction device 10 also includes a permeable covering 18, which covers a peripheral section of the first guide roller 12, an active surface 20 of the suction box 16, indicated here by dashed lines, and a Peripheral portion of the second guide roller 14 is guided or is.

The fabric 18 is an endless circulating fabric, with in 1a only a portion thereof is shown. At least in the area in which the clothing 18 is or is guided over the effective surface 20 of the suction box 16, a fibrous web (not shown here) can be transported on the clothing 18 on the side of the clothing 18 facing away from the effective surface 20 during normal operation. If the suction box 16 is connected during normal operation to a vacuum source, also not shown, for example via a connection on one of its end faces, the vacuum acts on the fabric 18 via the active surface and, since the fabric 18 is designed to be permeable, also through the fabric 18 through to the fibrous web. The latter is thus held securely on the covering 18 and guided with it over the area of the active surface 20 .

According to the invention, the active surface 20 is arranged and dimensioned in such a way that it essentially bridges the entire path covered by the clothing 18 between the two guide rollers 12 and 14 . For this purpose, the suction box 16 can preferably have a first curved side wall adapted to the diameter of the first guide roller 12 and a second curved side wall adapted to the diameter of the second guide roller 14 . Furthermore, the suction box 16 can comprise a cover opposite the active surface 20 and a front plate on the driver and drive side, wherein at least one of the two front plates preferably has a connection for the vacuum source, not shown.

Depending on the application, the effective surface 20 of the suction box can have a relatively large open surface. The active surface can in particular comprise a plurality of struts which are aligned parallel to one another and are spaced apart from one another and which preferably extend orthogonally to the direction of movement of the clothing in normal operation. In extreme cases, the open area can also be 100%, i.e. the suction box 16 can be essentially completely open towards the clothing 18 .

In addition, the suction box 16 can preferably also include format slides, which are not shown here, which are positioned in the cross-machine direction, ie orthogonally to the image planes 1a , Be adjustable to match the width of the active surface 20 to the width of the fibrous web.

1 b 12 shows a modification of the first embodiment according to the present invention 1a . In the following, therefore, only the differences from the embodiment according to FIG 1a received. In the modification according to 1b the suction box 16 is designed in such a way that it can exert negative pressures of different strengths on the clothing and the fibrous web transported on it in two different zones. For example, one of these zones can serve as a so-called pick-up zone, whereas the other zone can function as a so-called stop zone. In order to form the different negative pressures in the two zones, the suction box can have a dividing wall on the inside, so that there are virtually two suction box sections 16.1 and 16.2 in which different negative pressures can prevail. Alternatively or additionally, the active surface 20 can have two sections 20.1, 20.2, the open surfaces of which vary from one another.

2 shows a second embodiment of a suction device 10' according to the invention. This is an extension of the suction device 10 according to the first embodiment. Thus, the same reference numerals are used for the same components and component sections as in FIG 1a used and reference is made to the description above.

The second embodiment according to 2 differs essentially only in this from the first embodiment according to FIG 1a that, viewed in the direction of movement of the clothing 18 , a further guide roller 22 is provided in front of the first guide roller 12 and a further suction box 26 is provided between the further guide roller 22 and the first guide roller 12 . In normal operation, the clothing 18 and the fibrous web transported on it are first transported over a peripheral section of the additional guide roller 22 and then over an additional effective surface 30 of the additional suction box 26 before they reach a peripheral section of the first guide roller 12.

All three guide rollers 12, 14 and 22 are preferably designed to be essentially identical to one another. As a result, a separate replacement roller does not have to be kept available for each guide roller. The guide rollers 12, 14 and 22 also have a relatively simple structure and are not vacuumed. Their axes of rotation, indicated by crosses in the figures, preferably all lie on a common cylindrical surface.

In principle, the further suction box 26 can be constructed in exactly the same way as was described above for the suction box 16 . In the present exemplary embodiment, however, it differs from the suction box 16 in that it is narrower, since the distance between the further guide roller 22 and the first guide roller 12 is smaller than the distance between the first guide roller 12 and the second guide roller 14. The further active surface 30 of the further suction box 26 is therefore shorter than the active surface 20 of the suction box 16. In addition, the further active surface 30 can have a different open area than the active surface 20, so that the clothing 18 and the fibrous web transported on it different vacuums are applied in the two areas of the suction boxes 16 and 26, even if both suction boxes 16 and 26 are connected to the same vacuum source.

the 4 now shows schematically how a combination of the first embodiment 10 according to 1a and according to the second embodiment 10' 2 can be used to transfer a transfer device known from the prior art with a suction roller, as is shown in 3 is shown to replace.

In the transfer device 32* known from the prior art, a fibrous web (not shown) is pulled from a first covering 34 (from top left in 3 coming) to a second covering 36 (moving to the right in 3 groundbreaking) transferred. In the transfer area, the first clothing 34 is guided over a first deflection roller 38 that is not subjected to suction. Likewise, the second clothing 36 is guided over a second deflection roller 40 in the transfer area. Unlike the first deflection roller 38, however, the second deflection roller 40 can be evacuated in sections in order to be able to reliably transfer the fibrous web to the second span 36.

In order to reliably transfer the fibrous web from the first skin 34 to the second skin 36, the transfer device 32* includes a suction roller 42. The structure of the latter is relatively complicated. In order to also be able to transfer fibrous webs with long fibers, it requires a roller shell with a relatively large open area. Since these cannot be reached with bores, or only with difficulty, suction rolls with casings in honeycomb geometry are used in practice, in particular triangular honeycombs or hexagonal honeycombs, which are welded or soldered together. Otherwise there is a risk that the suction openings will become clogged. Furthermore, the suction roller 42 usually comprises at least two different suction zones, namely at least one pick-up zone, which is opposite the first deflection roller 38, and a holding zone, which is used to hold the fibrous web between the first deflecting roller 38 and the second deflecting roller 40.

4 shows schematically how the complicated structure of the deflection roller 42 3 by the inventive suction device 10 'according to the second embodiment 2 can be replaced. In addition, shows 4 , as well as the vacuumed second deflection roller 40 from 3 by the suction device 1 according to the invention according to the first embodiment 1a can be replaced. With regard to these two embodiments, reference is made to the above description 3 and 4 referenced, with the covering being 18 in 1a here the second covering 36 corresponds. The suction devices 10 and 10′ according to the invention make it possible to provide a transfer device 32 for safe transfer, preferably in a closed train, of the fibrous web from the first skin 34 to the second skin 36, which is free of suction rollers and the problems associated therewith. The advantages of the present invention are particularly effective when the fibrous web to be transferred has long fibers or is largely formed from them. At this point it should be noted that in the transfer device known from the prior art according to 3 Strictly speaking, the fibrous web is usually not really transferred in one closed train, but with a small gap of about 2 mm. According to the transfer device 32 according to the invention 4 it is possible to actually transfer the fibrous web in a closed train, but it is alternatively also possible to transfer the fibrous web - as in the prior art - with a small gap.

If the effective surface 30 of the additional suction box 26 has a different open surface than the effective surface 20 of the suction box 16 of the suction device 10', it is possible, even if both suction boxes 16 and 26 are connected to the same vacuum source, to have a different vacuum to apply the fibrous web transported on the clothing 18 in the area of the other suction box, compared to the negative pressure in the area of the suction box 16. Thus, compared to the first deflection roller 38, a pick-up zone with greater negative pressure and between the first clothing 34 and the second Upholstery 36 are set up a holding zone with lower vacuum. The area in which the clothing 18 and the fibrous web transported on it are guided around a peripheral section of the first guide roller 12 of the suction device 10' without a negative pressure acting on it can be kept relatively small, since according to the invention the respective active surfaces 20, 30 are such arranged and are dimensioned to bridge substantially the entire path covered by the fabric 18 between the respective guide rollers 22, 12 and 14.

5 shows a third embodiment of a suction device 10" according to the invention. This is an extension of the suction device 10' according to the second embodiment. The same reference numbers are therefore used for the same components and component sections as in FIG 2 used and reference is made to the description above.

According to the third embodiment 3 differs essentially only in this from the second embodiment according to FIG 2 that a support roller 44 is additionally provided, which is arranged on a side of the first guide roller 12, the second guide roller 14 and the further guide roller 22 facing away from the clothing 18 and is in supporting contact with these guide rollers 12, 14 and 18. In this way, said guide rollers 12, 14, 18 can be made relatively small and inexpensive, without the risk that they will sag unacceptably as a result of the forces that act on them from the deflected clothing 18.

Reference List

10, 10', 10"

suction device

12

first guide roller

14

second guide roller

16

suction box

16.1, 16.2

suction box sections

18

covering

20

effective area

20.1, 20.2

active surface sections

22

another guide roller

26

another suction box

30

further effective area

32, 32*

transfer device

34

first covering

36

second covering

38

first deflection roller

40

second deflection roller

42

suction roll

44

backup roll

Claims (15)

Suction device (10, 10', 10") for reliably guiding or transferring a fibrous web, such as in particular a glass fiber, nonwoven or paper web, comprising a first and a second guide roller (12, 14), a suction box (16) arranged between them, and a permeable fabric (18) guided over the two guide rollers (12, 14) and the suction box (16), the suction box (16) having an active surface (20) which is designed, during normal operation, to apply a negative pressure to the active surface (20) guided clothing (18) and on the fibrous web transported on it, characterized in that the active surface (20) is arranged and dimensioned in such a way that it covers essentially the entire path that the clothing (18) travels between the two guide rollers (12, 14) put back, bridged. suction device (10, 10', 10") claim 1 , characterized in that the first and/or second guide roller (12, 14) are not evacuated. suction device (10, 10', 10") claim 1 or 2 , characterized in that the suction box (16) further has a first curved side wall adapted to the diameter of the first guide roller (12) and/or a second curved side wall adapted to the diameter of the second guide roller (14). Suction device (10, 10', 10") according to one of the preceding claims, characterized in that the suction box (16) also has a connection on one of its two end faces between the two guide rollers (12, 14), by means of which the suction box (16 ) is connected or connectable to a vacuum source. Suction device (10, 10', 10") according to one of the preceding claims, characterized in that the suction box also comprises at least one format slide with which the width of the active surface (20) can be set or adjusted to the width of the fibrous web. Suction device (10', 10") according to one of the preceding claims, characterized in that the suction device (10', 10") comprises a further guide roller (22) and a further suction box (26) over which the clothing (18) is guided the further suction box (26) has a further active surface (30) which is designed to exert a negative pressure on the clothing (18) guided over the further active surface (30) and on the fibrous web transported thereon during normal operation, and wherein the further active surface (30) arranged in such a way and is dimensioned such that it essentially bridges the entire path covered by the clothing (18) between the further guide roller (22) and one of the two guide rollers of the first and second guide roller (12, 14). suction device (10', 10") claim 6 , characterized in that the further suction box (26) is designed, in normal operation, to exert a different, in particular stronger, negative pressure on the clothing (18) and on the fibrous web transported on it than the negative pressure of the suction box (16) between the first and second guide rollers (12, 14). suction device (10', 10") claim 6 or 7 , characterized in that the axes of rotation of the first guide roller (12), the second guide roller (14) and the further guide roller (22) do not lie in a common plane, but are preferably arranged on a cylinder surface. Suction device (10") according to one of the preceding claims, characterized in that the suction device (10") further comprises a support roller (44) which is on a side of the first and second guide roller (12, 14) remote from the clothing (18), and possibly the further guide roller (22) and is in supporting contact with these guide rollers (12, 14, 22). Suction device (10, 10', 10") according to any one of the preceding claims, characterized in that the active surface (20) is essentially planar, so that the clothing (18) and the fibrous web transported on it, in normal operation, extend in a straight line from the first Guide roller (12) are guided to the second guide roller (14). Suction device according to one of Claims 1 until 9 , characterized in that the active surface is essentially curved, so that the clothing and the fibrous web transported thereon are not guided in a straight line from the first guide roller to the second guide roller during normal operation. Suction device (10, 10', 10") according to one of the preceding claims, characterized in that the active surface (20) has an open surface of between 20% and 100%, preferably between 50% and 100%, more preferably between 70% and 100 % having. Machine for producing or finishing a fibrous web, such as in particular a glass fiber, nonwoven or paper web, comprising at least one suction device (10, 10', 10") according to one of the preceding claims. Use of a suction device (10, 10', 10") according to one of Claims 1 until 12 for transferring, preferably in a closed train, a fibrous web, in particular one with long fibers, between two sections in a machine for the production or finishing of the fibrous web or between two functional units of these sections. use after Claim 14 with reference to the suction device (10, 10', 10") at least according to claim 7 , characterized in that the active surface (20) between the first guide roller (12) and the second guide roller (14) provides a holding zone, while the further active surface (30) provides a pick-up zone, the open surface of the The holding zone is different from the open area of the pick-up zone in order to exert a greater negative pressure in the holding zone on the clothing (18) and the fibrous web transported thereon than in the pick-up zone.

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