EP0999305A2 - Apparatus for treating a web material - Google Patents

Abstract

A web (14) of paper or cardboard is dried by passing over a support surface (22) to move with a porous support blanket (16) around a deflection roller (18) between the drying cylinders. Before the roller (18), it passes over a cohesive underpressure zone (24), with the suction box wall (26) and at least one other wall fitted with suction openings (34). The assembly has at least one additional suction opening slit (34). At the support, the web (14) is in contact with the smooth support surface (22), in its travel with the support blanket (16). At the leading end of the underpressure zone (24), a seal (28) acts with the support blanket (16) where the web (14) leaves the support surface (22). At least one additional suction opening (34) is at the leading end of the underpressure zone (24), as a slit opening across the direction (L) of web (14) travel and over part of the machine width. The additional suction opening slit (34) runs from a web leader or a starter edge strip zone of the web (14), across its direction (L) of travel. An additional suction opening can be at both side edges of the web (14), which can be outside the web width and matched to another paper edge. The additional slit suction opening can be aligned along the direction (L) of web travel. A slit suction opening (34), at the leading end of the underpressure zone (24) and across the direction (L) of web movement, is adjacent to a slit suction opening along the line (L) of web travel and opens into it. The first slit suction opening (32) projects beyond the web width, on both sides. The deflection roller (18) is perforated and/or ridged. The suction box (20) shrouds the zone of the deflection roller (18) which is not covered by the web (14) and the blanket (16). The support surface (22) is on a rotating drying cylinder (10) and the blanket (16) is a drying blanket or fourdrinier.

Description

The invention relates to a device for treating a material web such as in particular a paper or cardboard web in which the material web over at least one particularly smooth support surface and then together with a porous support belt to a deflection roller or the like is guided, the one running from the support surface Material web can be sucked onto the porous support belt by means of a vacuum zone is that on the side facing away from the material web of the porous Support band adjacent and between this and an opposite Wall of a suction box defined and on her in the direction of web travel front end by at least one cooperating with the support band Sealing element is sealed and with its rear End extends at least substantially to the deflecting roller, and wherein the suction box wall with a slot-like first suction opening in particular is provided in the area adjacent to the deflecting roller rear end of the vacuum zone and through the Air can be extracted from the vacuum zone.

In a device known from DE-A1-195 27 289, this is the Porous support band opposite suction box wall only in the area of the rear end viewed in the direction of web travel with a suction opening Mistake.

As soon as the web of material moves away from, for example, a drying cylinder detached formed support surface, it is due to the negative pressure the back of the porous, for example formed by a dryer fabric Support band held on this support band. The previous suction box principle brings with it a number of disadvantages. So yourself when the sealing element lies directly on the porous support band, which is practically never the case, cannot be prevented from being straight air also penetrates into the vacuum zone in the area of this sealing element. This is due to the porosity of the support band, the one certain air passage through the support band. Behind the sealing element then experiences a corresponding pressure loss. In addition comes that the still wet web of material tends to, in particular smooth, for example formed by a drying cylinder support surface to stick. It is therefore only at a certain distance a sufficient negative pressure from the sealing element to the material web to suck against the porous support band.

Problems also arise with the two-step process Introduction of a respective material web. This is how it happens during insertion the tip or the initial edge strip of a respective material web without ropes due to sticking to the smooth support surface as well given the lack of vacuum behind the not yet or at best slightly covered support tape so that the tip is not of the smooth, formed for example by a drying cylinder Support surface releases and consequently up to a usually provided Scraper continues to run, eventually being returned to by air pressure Support band must be brought back. The tip will eventually be from the porous support band, so air can still pass through pass the support band into the vacuum zone. A corresponding one Air passage is particularly possible at the side of the tip. This results in a substantial reduction in the vacuum, so that finally only in the area of the near the rear end of the vacuum zone vacuum slot provided there is sufficient vacuum to suck the web of material onto the support belt and hold it there.

A lift off has always been counteracted so far by the fact that Suction box and / or the vacuum zone is divided accordingly. A corresponding subdivision can then be made, for example, via the Peak width a higher negative pressure can be generated. The box structure in question is correspondingly complex and complex, especially since the corresponding Additives are required. Only when the material web in fully extended and the porous support band at least essentially covered over its entire width, prevails in the whole Vacuum zone is a sufficient vacuum to adhere to the material web suck the support band and hold it. However, it can Even in this operating phase, there is still external air in the vacuum zone arrive, in the area of the interacting with the support band Sealing element through the porous support band and on the two lateral web edges, i.e. both on the leader side as also on the drive side.

During operation, it now comes along on the straight path the particularly smooth support surface and the deflection roller for edge lifting the material web. These can be found on both the leader as well occur on the drive side, on which usually no special tip width or edge strip area is provided. The edge lifting are irregular and of short duration, so that a kind of web flutter occurs. The main reason for this is the reduced vacuum after the sealing element and a loss of negative pressure on the two side Edges of the material web. Decisive for those in the area the straight course of the material web between the particular smooth support surface and the deflection roller occurring web edge lifting both on the leader and on the drive side are special also between the web of material and, for example, through a drying cylinder formed support surface occurring air turbulence entail.

The aim of the invention is to provide a device of the type mentioned create in which the aforementioned problems are eliminated and practical without additional energy expenditure and without the previous requirement a subdivision of the suction box or the vacuum zone all relevant points in the vacuum zone are sufficient Negative pressure is ensured.

This object is achieved according to the invention in that a coherent Vacuum zone is provided and that the suction box wall with at least one other opening into this vacuum zone Suction opening is provided.

Due to this design, the air passage through the suction box wall spread over different places, so that at least one more Area of relatively high negative pressure is created, with that in the area the first suction opening can fuse. By an appropriate Positioning of the at least one further suction opening can thus in particular also directly behind the sealing element and on provided the necessary negative pressure on the side web edges become. A subdivision of the suction box or the vacuum zone is not necessary for this. The total energy consumption is also practical not increased. Although the porous support band when inserting the tip or the edge strip of a respective material web is only partially covered is now ensured due to the training according to the invention, that the web tip measured over its entire in the web running direction Length sticks to the porous support band. By appropriate positioning the at least one further suction opening can i.a. ensured be that in the area of the sealing element in the vacuum zone penetrating external air is sucked off again as quickly as possible, so that already at the front end of this vacuum zone in the direction of web travel required negative pressure prevails to the material web from the particular smooth, for example formed by a cylinder support surface to replace. The web tip thus runs together with the support band from the particularly smooth support surface, so that the previous pressurized air could be omitted in the area of a scraper. Through the can increase the negative pressure at the relevant points also the aforementioned, due to air turbulence between the material web and that formed, for example, by a drying cylinder Support surface to be compensated. After also by a corresponding positioning of at least one further suction opening each Negative pressure losses in the negative pressure zone counteracted can, the previously occurring web edge lifts be practically eliminated. Such web edge withdrawals are therefore despite generated with the airflow emerging laterally from the machine Negative pressure in the area between the material web and the one in particular smooth support surface forming cylinder and the existing Practical tendency of the web to be lifted off the support belt locked out. By appropriate positioning of the at least a further suction opening can thus be ensured that came through the porous support band into the negative pressure zone External air from the suction box as quickly as possible Vacuum zone is suctioned off, so that as a result of the relevant Set the negative pressure already corresponding to the negative pressure zone is increased.

In a device known from DE-U-296 01 543, the device at the beginning mentioned type is the negative pressure zone in a smaller, on the drain area restricted sub-zone and an adjoining one in the web running direction further, down to the area of a perforated deflection roller extending and sub-divided over this sub-zone.

In a preferred practical embodiment of the invention The device is at least one respective further suction opening slit-like executed.

The material web can in particular together with the support band the support surface can be guided, preferably the material web Support surface touched. This is at the front end of the vacuum zone provided, cooperating with the support band sealing element preferably arranged in the area in which the material web carrying Support tape runs off the support surface.

In a preferred practical embodiment of the invention The device is at least one respective additional suction opening in the area the front end of the negative pressure zone, thereby achieving is that the desired vacuum is already immediate is behind the sealing element. Such a suction opening can in particular be designed slit-like and transverse to the direction of web travel extend. It is also advantageous if this slit-like suction opening only extends over part of the machine width. It extends such a slit-like further suction opening expediently at least over an initial peak or initial Edge strips of the material web corresponding area transverse to Web direction.

Alternatively or additionally, it is also possible to have at least one more Suction opening in the area of a respective lateral edge of the material web to be arranged, this further suction opening preferably at one changing paper edge is customizable. It is preferably in the range both web edges each have at least one such additional suction opening intended.

In a preferred practical embodiment, at least one such others in the area of a respective lateral edge of the material web provided suction opening outside the web width.

At least one is expediently in the region of a respective one side edge of the material web arranged suction opening again slit-like design, such a suction slit preferably in Web direction extends.

In an expedient practical embodiment of the invention Device is at least in the area of both web edges such a further slit-like suction opening is provided, which is outside the web width extends in the web running direction.

An expedient practical embodiment of the invention The device is characterized in that one in the area of the front End of the negative pressure zone, arranged transversely to the web running direction extending slot-like suction opening with one end to one in the area a web edge arranged, extending in the web running direction slot-like suction opening adjoins and preferably opens into this.

The first suction opening of the suction box wall can also be designed as a slot be, this first suction opening preferably transverse to Web direction extends. In an expedient embodiment this slit-like first suction opening extends on both sides beyond the web width.

In a preferred practical embodiment of the invention The deflection roller is perforated and / or grooved. This with the support belt in contact with the deflecting roller can then in its peripheral area not covered by the support band and the material web be sucked from the outside by the suction box.

The support surface can in particular by a moving surface and here preferably be formed by a rotating cylinder.

In a preferred practical embodiment, the support surface through a drying cylinder and the support belt through a dryer fabric educated.

Basically, it is possible to use one instead of a respective suction slot To provide a series of several successive smaller suction openings.

Figur 1

eine schematische Teildarstellung eines zwischen zwei Trockenzylindern gelegenen Bereichs einer Papiermaschine,

Figur 2

eine schematische Seitenansicht eines Teils des Saugkastens in Richtung des Pfeiles F der Figur 1,

Figur 3

eine schematische Schnittdarstellung der Anordnung gemäß Figur 2, geschnitten entlang der Linie A-A, und

Figur 4

eine der der Figur 2 vergleichbare Ansicht einer weiteren Ausführungsform mit einem zusätzliche Randschlitze aufweisenden Saugkasten.

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

Figure 1

2 shows a schematic partial representation of an area of a paper machine located between two drying cylinders,

Figure 2

2 shows a schematic side view of part of the suction box in the direction of arrow F in FIG. 1,

Figure 3

3 shows a schematic sectional illustration of the arrangement according to FIG. 2, cut along the line AA, and

Figure 4

one of the view comparable to Figure 2 of a further embodiment with an additional edge slots having suction box.

Figure 1 shows a schematic partial representation of the heated between two Drying cylinders 10, 12 located area of a device for treatment a material web 14, which in the present case is is a paper or cardboard web.

As can be seen from FIG. 1, the material web 14 is together with a porous formed in the present case by a sieve belt 16 Support belt over both the drying cylinder 10 and the drying cylinder 12 and in between via a perforated and / or grooved Deflection roller 18 out. The two drying cylinders 10 and 12 each from the material web 14 and the deflection roller 18 from the Screen belt 16 touches.

The deflection roller 18 is not in its material web 14 and the sieve belt 16 covered peripheral area via an outer suction box 20 sucked, the inside of the loop of the deflection roller 18th guided sieve belt 16 is arranged.

The one running off the smooth support surface 22 of the drying cylinder 10 and guided together with the screen belt 16 in a straight line to the deflection roller 18 Material web 14 is attached to the by means of a vacuum zone 24 Sieve belt 16 sucked in, facing away from the material web 14 Side of the screen belt 16 is adjacent and between this and an opposite Wall 26 of the suction box 20 is defined. At her in Web running direction L is the negative pressure zone 24 through a sealed with the screen belt 16 cooperating sealing element 28. This vacuum zone extends with its rear end in the web running direction L 24 to the deflection roller 18, in the present case the suction box wall 26 is another, cooperating with the deflection roller 18 Sealing element 30 is provided.

The suction box 20 is also with a suction line shown in Figure 1 50 provided.

As can be seen in particular from FIGS. 2 and 3, has the suction box wall 26 has a slit-like first suction opening 32 in the region of the rear end adjacent to the deflection roller 18 Vacuum zone 24 transverse to the web running direction L on both sides over the Web width 48 extends (see also Figure 4) and through Air can be extracted from the vacuum zone 24.

In the present case, neither the suction box 20 nor the vacuum zone 24 divided in the usual way. It is therefore special also not a separate one of the web top or an initial one Edge strips of the sub-area assigned to the material web are provided. Instead is the suction box wall 26 with another in the vacuum zone 24 opening 34 provided.

This further suction opening 34 is again slit-like, for example executed. It extends in the area of the front end of the vacuum zone transverse to the direction of web travel L. It is thus close to itself sealing element 28 likewise extending transversely to the web running direction L. arranged, which is provided in the drain region 36 in the present case, in which the sieve belt 16 runs from the drying cylinder 10. In the illustrated In the exemplary embodiment, the sealing element 28 is arranged in an area in which the sieve belt 16 and the material web 14 are still on the rest smooth outer support surface 22 of the drying cylinder 10.

As can be seen in particular from FIG. 2, the slot-like further suction opening 34 parallel to the sealing element 28 only over part of the machine width, at least over the an initial tip or edge strip of the web of material 14 corresponding area. In the present case it extends the slit-like suction opening 34 on both sides slightly above this area 38 out.

As can be seen in particular from FIG. 3, the further Suction opening 34 in the region of the front end of the vacuum zone 24 in addition to the area of the suction opening 32, raised another area Vacuum created that with that of the first suction opening 32nd merges. This is already at the front end of the vacuum zone 24 provided for the necessary negative pressure, so that in particular the Web tip or an initial edge strip of the material web 14 over its entire length in the web running direction L on the screen belt 16 attached.

In the further embodiment according to FIG. 4, both are in the region Web edges 40, 42 each have at least one further slit-like suction opening 44, 46 provided. These each extend in the web running direction L. Additional slit-like suction openings 44, 46 are present Case arranged just outside the web width 48.

In the present case it opens in the area of the front end of the vacuum zone 24 arranged slot-like suction opening 34 with its Web edge 40 adjacent end in the relevant, in the web running direction L extending slot-like additional suction opening 44. As with reference 4 can be seen, the slot-like extends Suction opening 44 in the direction of the strip-like sealing element 28 somewhat beyond the slot-like suction opening 34 parallel to the sealing element 28. On the other hand, it ends at a distance from the first in the area of suction opening 32 arranged at the rear end of the vacuum zone 24.

Otherwise, this embodiment has at least in accordance with FIG essentially the same structure as that of Figures 1 to 3. Also in In the present case, the slit-like first suction opening 32 extends on both sides beyond web width 48.

In the present embodiments, the sieve belt 16 extends on both sides both over the material web 14 and over the suction box wall 26 (see in particular Figures 2 and 4).

Reference list

10th

Drying cylinder

12th

Drying cylinder

14

Material web

16

porous support belt, mesh belt

18th

Deflection roller

20th

Suction box

22

smooth support surface

24th

Vacuum zone

26

Suction box wall

28

Sealing element

30th

Sealing element

32

first suction opening

34

further suction opening

36

Drain area

38

Top area

40

Web edge

42

Web edge

44

further suction opening

46

further suction opening

48

Web width

50

Suction line

F

arrow

L

Web direction

Claims (19)

Device for treating a material web (14), such as in particular a paper or cardboard web, in which the material web (14) has at least one, in particular smooth, support surface (22) and then together with a porous support belt (16) to form a deflection roller (18) or the like The material web (14) running from the support surface (22) can be sucked into the porous support band (16) by means of a vacuum zone (24), which adjoins the side of the porous support band (16) facing away from the material web (14) and defined between this and an opposite wall (26) of a suction box (20) and at its front end in the web running direction (L) is sealed by at least one sealing element (28) interacting with the support band (16) and at least at the rear end in extends essentially to the deflecting roller (18), and the suction box wall (26) is provided with a slot-like first suction opening (32) which arranged in the region of the rear end of the vacuum zone (24) adjacent to the deflection roller (18) and through which air can be extracted from the vacuum zone (24),
characterized by
that a coherent vacuum zone (24) is provided and that the suction box wall (26) is provided with at least one further suction opening (34, 44, 46) opening into this vacuum zone. Device according to claim 1,
characterized by
that at least one further suction opening (34, 44, 46) is designed like a slot. Device according to claim 1 or 2,
characterized by
that the material web (14) is guided together with the support band (16) over the support surface (22), the material web (14) preferably touching the support surface (22). Device according to claim 3,
characterized by
that the sealing element (28) provided at the front end of the vacuum zone (24) and cooperating with the support band (16) is arranged in the area in which the support band (16) carrying the material web (14) runs from the support surface (22). Device according to one of the preceding claims,
characterized by
that at least one further suction opening (34) is arranged in the region of the front end of the vacuum zone (24). Device according to claim 5,
characterized by
that at least one further slit-like suction opening (34) is provided in the region of the front end of the vacuum zone (24) and extends transversely to the web running direction (L). Apparatus according to claim 6,
characterized by
that the slot-like further suction opening (34) extends only over part of the machine width. Apparatus according to claim 6 or 7,
characterized by
that the slot-like further suction opening (34) extends at least over an area (38) corresponding to an initial tip or an initial edge strip of the material web (14) transversely to the web running direction (L). Device according to one of the preceding claims,
characterized by
that at least one further suction opening (44, 46) is arranged in the region of a respective lateral edge (40, 42) of the material web (14). Device according to claim 9,
characterized by
that at least one further suction opening (44, 46) is provided in the area of both web edges (40, 42). Device according to claim 9 or 10,
characterized by
that at least one further suction opening (44, 46) provided in the area of a respective lateral edge (40, 42) of the material web (14) is arranged outside the web width, this further suction opening (44, 46) preferably being adaptable to a changing paper edge . Device according to one of claims 9 to 11,
characterized by
that at least one further slit-like suction opening (44, 46) is provided in the area of a respective lateral edge (40, 42) of the material web (14) and extends in the web running direction (L). Device according to claim 12,
characterized by
that at least one further slit-like suction opening (44, 46) is provided in the area of both web edges (40, 42), which extends outside the web width in the web running direction (L). Device according to one of the preceding claims,
characterized by
that a slit-like suction opening (34) arranged in the region of the front end of the vacuum zone (24) and extending transversely to the web running direction (L) has one end arranged in the region of a web edge (40, 42) and extending in the web running direction (L) slot-like suction opening (44) adjoins and preferably opens into this. Device according to one of the preceding claims,
characterized by
that the first suction opening (32) of the suction box wall (26) is designed like a slot and extends transversely to the web running direction (L). Device according to one of the preceding claims,
characterized by
that the particularly slit-like first suction opening (32) extends on both sides beyond the web width (48). Device according to one of the preceding claims,
characterized by
that the deflection roller (18) is perforated and / or grooved and that this deflection roller (18) in contact with the support belt (16) in its peripheral region not covered by the support belt (16) and the material web (14) through the suction box (20 ) is sucked from the outside. Device according to one of the preceding claims,
characterized by
that the support surface (22) is formed by a moving surface and preferably by a rotating cylinder (10). Device according to claim 18,
characterized by
that the support surface (22) is formed by a drying cylinder (10) and the support band by a drying screen (16).

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