EP2085512A1 - Suction device for a machine for producing fibrous material - Google Patents

Abstract

The suction device (1) has a suction roll (3) with a carrying cylindrical tube (4) and a supporting structure (5). The suction roll has a suction roll diameter (D.3) and the cylindrical tube has a cylindrical tube diameter (D.4). The supporting structure is arranged around the carrying cylindrical tube. An annular space (13) of the suction roll is formed from a supporting structure inner area. The cylindrical tube diameter and the suction roll diameter are in the ratio of 0.75 to 0.85.

Description

The invention relates to a suction device for a fibrous web, in particular paper or board web, producing machine, in particular paper or board machine comprising a Saugwalzendurchmesser having a suction roll with a supporting and a roller tube diameter having roller tube and arranged with a supporting roller tube support structure, the both permeable to air and carries a conveyor belt with lying thereon and to be dehydrated fibrous web in a loop area, and an external suction box, which surrounds the suction roller from the outside partially and the conveyor belt and thus to be dewatered fibrous web with an external, of at least one of the Vacuum connected negative pressure source generated vacuum, wherein at least one annular space between the supporting roller tube of the suction roll and the outer, the conveyor belt-bearing portion of the support structure of the suction roll present is so that it can act on this of the negative pressure generated by the external suction box on the resting on the support structure in a wrap conveyor belt and thus on the fibrous web to be drained.

The conveyor belt can be, for example, a forming fabric, wherein the suction device is then arranged in a wire section of a machine for producing a fibrous web. It is also fundamentally possible that the conveyor belt is designed as a press felt inserted in a press section or a drying wire used in a dryer section. Both the press section and the dryer section make this in known Way form part of a machine for producing a fibrous web.

Such a suction device with a suctioned from the outside roll is for example from the US patent US 2,270,464 known. The ratio of roller tube diameter of the roller tube to Saugwalzendurchmesser the suction roller is a maximum of 0.50 [-], so that a very large annular space between the supporting roller tube of the suction roll and the outer, the conveyor belt-bearing portion of the support structure of the suction roll is present. In order for the suction roll of the suction device to obtain the necessary carrying capacity for operation, the annular space is provided with a multiplicity of spaced and each having a multiplicity of apertures having annular disks. Depending on the thickness of the discs, these discs can lead to markings in the fibrous web to be drained and thus to quality losses. In addition, the annular discs can adversely affect the formation of a uniform negative pressure across the width. The most serious disadvantage of this suction device, however, seems to be that it is not suitable for use in a modern machine for producing a fibrous web, which is currently already being operated at a web speed of up to 2,200 m / min and possibly even more, due to its required size suitable. In a modern machine is only a limited space available, which is not sufficient for such a suction device in a necessary design, for example, in view of the required high inertia.

Another suction device with a suctioned from the outside roll is for example from the European patent EP 0 889 165 B1 known. The disclosed roller, which carries in a peripheral region a conveyor belt with a fibrous web resting thereon, is at least partially enclosed by an evacuated box. The roller tube is perforated, so that the am externally enclosing box applied vacuum can act on the conveyor belt and thus on the fibrous web.

A disadvantage of the perforated and externally drawn roll is that it still has to be manufactured from expensive suction roll materials for applications in the wet part of a machine for producing a fibrous web, in particular due to corrosion reasons. Also, the drilling of the plurality of holes through the entire wall thickness of the roller tube, which must meet the necessary carrying capacity, such as the beam or shell bending, is a costly manufacturing process. For this reason, such a solution can expect no significant cost advantages over a conventional suction roll with internal suction box.

Another disadvantage of the perforated and externally evacuated roll is that its roll tube experiences the same stresses of string tension and vacuum effect as a conventional suction roll. As a result, the roller tube must also be dimensioned as in a conventional suction roller. Again, the many suction holes lead to a significantly reduced rigidity, which also increases the roller when the maximum allowable deformation determines the dimensions of the roller. In addition, the suction holes cause notch stresses in the roller tube, which also lead to a larger roller in strength-driven dimensioning.

Furthermore, it is disadvantageous that the supporting material of the perforated and externally drawn roll is constantly exposed to corrosive operating conditions by the process media, such as white water, chemicals and the like. The well-known steels have no fatigue strength under such conditions, not even the special corrosion-resistant suction roll steels. Depending on the level of corrosion load, sooner or later the suction roll tube will break. In addition, due to the corrosive environment on the load bearing, loaded roller tube also the risk of Stress corrosion cracking, which limits the choice of materials (insensitive to stress corrosion cracking), limits the allowable stresses and may result in unexpectedly early failure of the roll tube due to breakage.

The invention has for its object to provide an improved suction device with an externally evacuated roller, in particular of the type mentioned, which largely largely avoided, preferably completely avoids the disadvantages mentioned. In particular, the roller tube should be cheaper to produce and have a higher load capacity or allow additional measures to increase the carrying capacity.

This object is achieved in a suction device of the aforementioned type according to the invention that the ratio of roller tube diameter to Saugwalzendurchmesser ≥ 0.75, preferably ≥0.80, in particular ≥ 0.85, is. In this case, the roller tube diameter can assume a value in the range of 500 to 2,000 mm, preferably from 800 to 1,800 mm.

The object of the invention is completely solved in this way.

The roller tube of the suction roller thus provides the advantage of a higher degree of inertia in a, compared to the prior art, not deteriorated drainage quality of the fibrous web to be dewatered across its width. In addition, the roller tube of the suction roller is no longer weakened by suction holes and can be dimensioned smaller overall with respect to the wall thickness. Furthermore, such a suction device opens up a multiplicity of further possibilities which are advantageous in operation, such as, for example, the provision of special corrosion protection measures, the realization of further measures for increasing the carrying capacity or an improvement in the properties with regard to the strip run.

In a first embodiment according to the invention, it is provided that the annular space of the suction roll is formed from at least one inner region of the support structure and that the annular space in the circumferential direction of the suction roll without interruptions or possible interruptions of the annular space in the circumferential direction of the suction roll are so far apart that the negative pressure effect on the conveyor belt and thus on the fibrous web to be drained is not disturbed or even prevented in the entire looping area. Moreover, due to the stated design of the annulus, the bearing capacity of the suction roll is further increased.

The air-permeable support structure may, in particular with regard to its operating and environmental conditions, such as the process media, be made of a corrosion-resistant material, in particular a stainless steel, preferably an austenitic stainless steel or a ferritic-austenitic duplex steel. The austenitic stainless steel may comprise four main families: the molybdenum-free Cr-Ni steels such as 1.4307, 1.4306 or 1.4301 according to DIN EN 10088/1, the molybdenum-containing Cr-Ni-Mo steels such as 1.4401, 1.4404, 1.4432, 1.4435 or 1.4436 according to DIN EN 10088/1, the high-alloyed special austenites and the manganese austenites. By contrast, the ferritic-austenitic duplex steel favorably has a carbon content of at most 1.2% by weight, preferably of not more than 0.10% by weight, in particular of not more than 0.030% by weight, a nitrogen content in the range from 0.05 to 0, 40 wt.%, In particular from 0.05 to 0.22 wt.%, A chromium content in the range of 20.0 to 30.0 wt.%, In particular from 21.0 to 24.0 wt.%, A nickel content in Range of 1.0 to 8.0 wt.%, In particular from 1.5 to 6.5 wt.%, And a molybdenum content in the range of 0.0 to 5.0 wt.%, In particular from 0.1 to 3 , 5% by weight, on.

Furthermore, the roller tube of the suction roller is preferably provided on its outer surface with a protective medium, such as a paint, a (spray) coating or a plating with corrosion-resistant sheet metal, to protect them from direct contact with the corrosive process media. Such measures also allow the use of materials with more favorable properties, in particular in terms of cost and / or strength and / or rigidity. For example, the roller tube of the suction roll may be made of a non-corrosion resistant material, particularly a structural steel such as a St-37 or St-52.

In a first preferred embodiment, the outer region of the air-permeable support structure consists of at least one perforated and preferably thin-walled hollow cylinder, the perforated hollow cylinder preferably having a wall thickness in the range of 0.5 to 8 mm, preferably 1 to 6 mm, in particular 2 to 5 mm. The perforations in the hollow cylinder can be produced inexpensively and reliably by means of drilling, punching, laser cutting or similar machining methods. In addition, the perforations can be embodied in various designs: they can have countersinks, they can have constant, converging or diverging cross-sectional shapes, and / or they can have different cross-sectional shapes, for example with regard to their diameters and their courses. Of course, further, known to those skilled execution options are conceivable. Moreover, in addition to meeting operational requirements for strength and stiffness, such ranges of thickness also provide significant weight savings, especially with otherwise unaltered design criteria.

The perforated hollow cylinder may consist of a bent and assembled, in particular a welded sheet, preferably a perforated plate. This practical option is characterized in particular by comparatively low production costs with short production times.

Furthermore, the outer region of the air-permeable support structure may be arranged of several along the roll length adjacent Hollow cylinder segments exist. On the one hand this simplifies the assembly of the suction roll, on the other hand the costs are markedly reduced by smaller, in particular easier to manufacture components.

In a second preferred embodiment, the outer region of the air-permeable support structure consists of at least one honeycomb structure composed of upright bands, which has a multiplicity of honeycombs. Such a honeycomb structure, as is customary today in forming rolls, provides the advantage of low weight coupled with good stiffness values and ideal conditions for uniform negative pressure on the conveyor belt and the fibrous web resting thereon. Furthermore, such a honeycomb structure has a low marking effect on the conveyor belt and thus on the fibrous web to be dewatered. Such a honeycomb structure is for example from the German patent application DE 32 10 320 A1 The content of which is hereby made the subject of the present description.

Taking into account aspects of strength engineering, the honeycomb structure may preferably have a longitudinal extension aligned in or approximately in the circumferential direction of the suction roll. Also, the honeycomb of the honeycomb structure can be offset in the circumferential direction of the suction roll to each other, so that the best possible area support of the conveyor belt takes place.

In view of the operational requirements in terms of carrying capacity, it is advantageous if the honeycomb structure has a height in the range of 3.0 to 25.0 mm, preferably from 4.0 to 20.0 mm, in particular from 5.0 to 15.0 mm, has. Moreover, such height ranges provide significant weight savings, especially with otherwise unaltered design criteria.

In a further preferred embodiment, the inner region of the air-permeable support structure is in the longitudinal direction of the suction roll spaced supports, such as Hochkantringen or honeycomb, or spacers, such as pins, formed, all of which are part of the air-permeable support structure. Such a trained inner region of the air-permeable support structure ensures sufficiently that the negative pressure effect on the conveyor belt and thus on the fibrous web to be dewatered is not disturbed or even prevented in the entire wrapping area.

The supports or spacers may be suitably connected at their inner ends to the supporting roll tube. The connection can be made, for example, by shrinking the air-permeable support structure on the supporting roller tube.

In view of the operational requirements in terms of carrying capacity, it is favorable if the inner region of the air-permeable support structure a height in the range of 5.0 to 50.0 mm, preferably from 10.0 to 40.0 mm, in particular of 15.0 up to 30.0 mm. Moreover, such height ranges provide significant weight savings, especially with otherwise unaltered design criteria.

Also, in another preferred embodiment, the suction roll may further include at least one additional means for supporting the supporting roll tube over its length to thereby increase its carrying capacity and minimize any deformations. The additional device preferably comprises a supporting and static yoke, which extends through the entire supporting roller tube and is statically supported at its two ends in the racks of the machine. The supporting roller tube can in turn be supported by a plurality of hydrostatic elements on the supporting and static yoke, wherein the hydrostatic elements are preferably adjustable, in particular controllable / regulated. Such an additional device is for example from the German patent application DE 25 55 677 A1 known, the content of which is hereby made the subject of the present description.

In an alternative and preferred embodiment, the additional means may comprise a second rotating roller tube which extends through the first supporting roller tube and is connected to the first supporting roller tube only in the roller center.

The second rotating roller tube can here be rotatably mounted at its two ends, preferably via pins, in the racks of the machine. Such an additional device is for example from the German patent application DE 101 12 202 A1 The content of which is hereby made the subject of the present description.

Furthermore, in a further preferred embodiment, at least one further suction box may be provided on the suction device, which adjoins the first suction box and pressurizes the fibrous web to be dewatered with negative pressure via the conveyor belt. By this at least one further suction box a stable and rigid support body is created, which provides sufficient stability for supporting a sealing strip in the gusset area even with very wide machines for producing a fibrous web. Furthermore, the suction zone is extended by the at least one further suction box in such a way that a continuous and uninterrupted Gesamttsaugzone arises, whereby the suction effect is significantly improved overall. This is in contrast to the arrangement of one of the suction roll at a distance from this arranged insulated suction box, whereby no such effective suction can be achieved. The provision of at least one further suction box is, for example, from the already mentioned European patent specification EP 0 889 165 B1 The content of which is hereby made the subject of the present description.

Moreover, according to a further embodiment of the first suction box as a central, the suction roll from the outside partially enclosing suction box may be formed extending from the inlet gusset to the outlet gusset, wherein seen in the web running direction in front of the suction roll, a second suction box is arranged, extending to the first suction box extends and which is sealed against the conveyor belt, and wherein seen in the web running direction after the suction roll, a third suction box is arranged, which extends to the first suction box and which is sealed against the conveyor belt. In this way, a particularly strong negative pressure can be transferred to the conveyor belt or to the fibrous web to be drained. Furthermore, a better adaptation of the negative pressure to the specific operating conditions can be achieved since the respective suction boxes can be operated either with the same negative pressure or with different negative pressures. Thus, for example, by applying the second suction box upstream in the web running direction, initially a lower negative pressure is applied, while in the area in which the fibrous web and the conveyor belt are in contact with the roll shell, a greater negative pressure is generated and in the subsequent third suction box again a lower vacuum is applied to avoid adverse effects on the fibrous web at extremely high web speeds. Such a use of further suction boxes before and after the central suction box is associated with relatively little additional effort, since practically to achieve the necessary rigidity of the external suction box anyway rigid cross-sections in the inlet and outlet gusset are necessary.

Also, negative pressure in the suction boxes can be adjusted separately, in particular controllable / regulated, so as to allow optimum adaptation to different operating conditions.

To seal the at least one suction box against the conveyor belt can be provided transversely to the running direction running sealing strips.

Here, in particular in the region of a gusset, which is enclosed by one of the suction boxes, a sealing strip is provided. In this way, an effective sealing of the suction boxes is ensured to prevent leakage.

It is understood that the features of the invention mentioned above and those yet to be explained can not be used in the particular combination given, but also in other combinations and in isolation, without departing from the scope of the invention.

The suction device according to the invention is outstandingly suitable for use in a machine for producing a fibrous web, in particular paper or board web, since in this case the advantages of the suction device according to the invention fully come into play.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings.

Figur 1

eine erste Ausführungsform einer erfindungsgemäßen Saugeinrichtung in geschnittener und stark vereinfachter Darstellung;

Figur 1A

eine Schnittansicht der Figur 1 gemäß der Schnittlinie A-A;

Figur 2

eine zweite Ausführungsform einer erfindungsgemäßen Saugeinrichtung in geschnittener und stark vereinfachter Darstellung;

Figur 2A

eine Schnittansicht der Figur 2 gemäß der Schnittlinie B-B;

Figur 3

eine dritte Ausführungsform einer erfindungsgemäßen Saugeinrichtung in geschnittener und stark vereinfachter Darstellung;

Figur 3A

eine Schnittansicht der Figur 3 gemäß der Schnittlinie C-C; und

Figur 4

zeigt einen beispielhaften Ausschnitt einer Wabenstruktur der erfindungsgemäßen Saugeinrichtung der Figur 3.

Show it

FIG. 1

a first embodiment of a suction device according to the invention in a sectional and highly simplified representation;

Figure 1A

a sectional view of FIG. 1 according to the section line AA;

FIG. 2

a second embodiment of a suction device according to the invention in a sectional and highly simplified representation;

FIG. 2A

a sectional view of FIG. 2 according to the section line BB;

FIG. 3

a third embodiment of a suction device according to the invention in a sectional and highly simplified representation;

FIG. 3A

a sectional view of FIG. 3 according to the section line CC; and

FIG. 4

shows an exemplary section of a honeycomb structure of the suction device according to the invention the FIG. 3 ,

The FIGS. 1 to 3 show three exemplary embodiments of a suction device 1 for a fibrous web 2 producing machine in a cut and greatly simplified representation. The at least one-layer fibrous web 2 may in particular be a paper or board web, in the case of the machine, which is not completely illustrated, in particular a paper or board machine.

The respective suction device 1 comprises a suction roll diameter D.3 having a suction roll 3 with a supporting and a roller tube diameter D.4 having roller tube 4 and arranged around the supporting roller tube 4 support structure 5, which is both permeable to air and a conveyor belt 6 with lying on it and to be drained fibrous web 2 in a wrap 7 carries. By definition, the wrap area 7 is the area, that is to say the length between the feed point 8 of the conveyor belt 6 on the support structure 5 and the drain point 9 of the conveyor belt 6 from the support structure 5. The fibrous web 2 has a web running direction L.2 (arrow).

The ratio of roller tube diameter D.4 to suction roller diameter D.3 is ≥ 0.75, preferably ≥ 0.80, in particular ≥ 0.85. In this case, the roller tube diameter can assume a value in the range of 500 to 2,000 mm, preferably from 800 to 1,800 mm.

Furthermore, the respective suction device 1 comprises an external suction box 10, which partially encloses the suction roll 3 from the outside and the conveyor belt 6 and thus the fibrous web 2 to be dewatered with an external vacuum source 11 connected to the suction box 10 generated negative pressure p _U applied. The preferably controllable / controllable negative pressure source 11 is merely indicated by means of an arrow, since it is well known to the person skilled in the art both constructively and functionally.

Between the supporting roller tube 4 of the suction roller 3 and the outer, the conveyor belt 6 bearing portion 12 of the support structure 5 of the suction roll 3 is at least one annulus 13 is present, so that on this generated with the external suction box 10 vacuum p _U at the on the support structure 5 in the wrap 7 resting conveyor belt 6 and thus can act on the fibrous web 2 to be drained.

The annular space 13 of the individual suction roll 3 is also formed from at least one inner region 14 of the support structure 5. Also, the annular space in the circumferential direction of the suction roll 3 without interruptions or possible interruptions of the annular space 13 in the circumferential direction of the suction roll 3 are so far apart that the negative pressure effect on the conveyor belt 6 and thus on the fibrous web 2 to be dewatered in the entire Umschlingungsbereich 7 not disturbed or even prevented.

The air-permeable support structure 5 of the respective suction roll 3 consists of a corrosion-resistant material 15, in particular a stainless steel, preferably an austenitic stainless steel or a ferritic-austenitic duplex steel. The austenitic stainless steel may comprise four main families: the molybdenum-free Cr-Ni steels such as 1.4307, 1.4306 or 1.4301 according to DIN EN 10088/1, the molybdenum-containing Cr-Ni-Mo steels such as 1.4401, 1.4404, 1.4432, 1.4435 or 1.4436 according to DIN EN 10088/1, the high-alloyed special austenites and the manganese austenites. By contrast, the ferritic-austenitic duplex steel favorably has a carbon content of at most 1.2% by weight, preferably of not more than 0.10% by weight, in particular of not more than 0.030% by weight, a nitrogen content in the range from 0.05 to 0, 40% by weight, in particular from 0.05 to 0.22% by weight, a Chromium content in the range from 20.0 to 30.0% by weight, in particular from 21.0 to 24.0% by weight, a nickel content in the range from 1.0 to 8.0% by weight, in particular from 1.5 to 6.5 wt.%, And a molybdenum content in the range of 0.0 to 5.0 wt.%, In particular from 0.1 to 3.5 wt.%, On.

Furthermore, the roller tube 4 of the individual suction roller 3 is provided on its outer surface 16 with a protective medium 17 in order to protect it from direct contact with the corrosive process media. The protective medium 16 may include, for example, a paint, a (spray) coating or a plating with corrosion-resistant sheet metal. Due to the provision of the protective medium 17, the roller tube 4 of the individual suction roller 3 consists of a non-corrosion-resistant material 18, in particular a structural steel, such as a St-37 or St-52.

In the embodiment of the FIG. 1 the perforated hollow cylinder 19 consists for example of a bent and assembled, in particular a welded sheet 20, preferably a perforated plate, and has a wall thickness d.19 in the range of 0th , 5 to 8 mm, preferably from 1 to 6 mm, in particular from 2 to 5 mm. Also, the perforation of the thin-walled hollow cylinder 19 may have an irregular or regular pattern, for example, when forming pattern lines or areas.

Depending on the width of the suction roll 3, the outer region of the air-permeable support structure 5 can also consist of a plurality of hollow cylinder segments arranged adjacently along the roll length L.3 (arrow).

The Figure 1A shows a sectional view of FIG. 1 according to the section line AA.

The respective suction device 1 comprises a suction roll diameter D.3 having a suction roll 3 with a supporting and a roller tube diameter D.4 having roller tube 4 and arranged around the supporting roller tube 4 support structure 5, which is both permeable to air and a conveyor belt 6 with lying on it and to be drained fibrous web 2 in a wrap 7 carries. By definition, the wrap area 7 is the area, that is to say the length between the feed point 8 of the conveyor belt 6 on the support structure 5 and the discharge point 9 of the conveyor belt 6 from the support structure 5.

The additional device 21 comprises in the present embodiment, a supporting and static yoke 22 which extends through the entire supporting roller tube 4 and, only indicated, is statically supported at its two ends 23 in the two-sided frames 24 of the machine. The supporting roller tube 4 is in turn supported by a plurality of hydrostatic elements 25 on the supporting and static yoke 22, wherein the hydrostatic elements 25 are preferably adjustable, in particular controllable / regulated.

Such an additional device is for example from the German patent application DE 25 55 677 A1 The content of which is hereby made the subject of the present description.

The FIG. 2A shows a sectional view of FIG. 2 according to the section line BB.

In the embodiment of the FIG. 3 the outer region 14 of the air-permeable support structure 5 consists of at least one honeycomb structure 26 composed of upright bands 27, which has a multiplicity of honeycombs 28. The honeycomb structure 26 has a longitudinal extent aligned in or approximately in the circumferential direction of the suction roll 3, and the honeycombs 28 of the honeycomb structure 26 are offset from one another in the circumferential direction of the suction roll 3 (cf. FIG. 4 ).

The honeycomb structure 26 has a height H.26 in the range from 3.0 to 25.0 mm, preferably from 4.0 to 20.0 mm, in particular from 5.0 to 15.0 mm.

In another, in the FIG. 3 merely indicated embodiment, the additional device 21 may alternatively comprise a second rotating roller tube 29 which extends through the first supporting roller tube 4 and is connected to the first supporting roller tube 4 only in the roller center M.3 (arrow). The second rotating roller tube 29 is in this case rotatably mounted at its two ends 23, preferably via pins, again in the racks 24 of the machine.

Such an additional device 21 is for example from the German patent application DE 101 12 202 A1 The content of which is hereby made the subject of the present description.

The FIG. 3A shows a sectional view of FIG. 3 according to the section line CC.

The inner region 14 of each in the FIGS. 1 to 3 shown air-permeable support structure 5 of the suction device 1 is made in the longitudinal direction of the suction roll 3 spaced supports 30, such as Hochkantringen (see. Figures 1 and 1a ) or honeycomb 28 (cf. FIGS. 3 and 3a ), or spacers 31, such as pins (see. Figures 2 and 2a ), all of which are part of the air-permeable support structure 5. The supports 30 or the spacers 31 are connected at their inner ends 32 in a suitable manner with the supporting roller tube 4. The connection can be made for example by shrinking the air-permeable support structure 5 on the supporting roller tube 4, wherein the supporting roller tube 4 has a roller tube diameter D. 4. The inner region 14 of the respective air-permeable support structure 5 has a height H.14 in the range from 5.0 to 50.0 mm, preferably from 10.0 to 40.0 mm, in particular from 15.0 to 30.0 mm, on. The support structure 5 is permeable to air and carries in an indicated manner the conveyor belt 6 with lying thereon and to be dewatered fibrous web 2 in a wrapping area, not shown.

Furthermore, in the two embodiments of the Figures 2 and 3 two further suction boxes 33, 34 are provided, which adjoin the first suction box 10 and which act on the fibrous web 2 to be dewatered via the conveyor belt 6 with negative pressure pU.

In this case, the first suction box 10 is formed as a central, the suction roll 3 from the outside partially enclosing suction box 10 which extends from the inlet gusset 35 to the outlet gusset 36. Furthermore, in the web running direction L.2 (arrow) seen in front of the suction roll 3, the second suction box 33 is arranged, which extends to the first suction box 10 and which is sealed against the conveyor belt 6. And in the direction of web travel L.2 (arrow) seen after the suction roller 3, the third suction box 34 is arranged, which extends to the first suction box 10 and which is sealed against the conveyor belt 6. The respective negative pressure p _U in the suction boxes 10, 33, 34 is separately adjustable, in particular controllable / controllable. Moreover, to seal the two suction boxes 33, 34 against the conveyor belt 6 transversely to the web running direction L.2 (arrow) extending, the skilled person well-known sealing strips 37 are provided.

The FIG. 4 shows an exemplary section of a honeycomb structure 26 of the suction device 1 of FIG. 3 , The honeycomb structure 26 is composed of a plurality of upstanding bands 27, of straight bands 38, 39, which extend in the circumferential direction and between which there is a certain distance, and arranged between the straight bands zigzag bands 40. At the points of contact 41, the zigzag tapes 40 are welded to the straight bands 38, 39. The bands 38, 39, 40 thus form a multiplicity of trapezoidal honeycombs 28.

In the present embodiment are by a certain arrangement of recesses 42 in the bands 38, 39 now each adjacent honeycomb each other in line connection. Namely, the straight bands 39 each have 40 recesses 42 between the contact points 41 with the zigzag bands. These may be, for example, circular holes. The zig-zag tapes 40 also have recesses 43, according to a specific pattern, so that honeycomb groups of a certain shape are formed. For example, six honeycombs, for example, the honeycomb 44 to 49 are combined into a honeycomb group. Between adjacent honeycomb groups, for example 44 to 49 and 50 to 55, there is no line connection. As can be readily seen, the honeycomb groups 44 to 49 and 50 to 55 extend diagonally.

One in the FIG. 4 illustrated honeycomb structure 26 is for example from the German patent application DE 32 10 320 A1 The content of which is hereby made the subject of the present description.

The respectively in the FIGS. 1 to 3 shown suction device 1 is particularly suitable for use in a machine for producing a fibrous web, in particular a paper or board web.

In summary, it can be stated that the invention provides an improved suction device with an externally evacuated roller of the type mentioned at the outset, which largely avoids, preferably completely eliminates, the disadvantages mentioned. In particular, the roller tube can be made cheaper and it has a higher load capacity or it allows additional measures to increase the carrying capacity.

Bezuaszeichenliste

1

suction

2

Fibrous web

3

suction roll

4

roll tube

5

support structure

6

conveyor belt

7

wrap region

8th

accumulating point

9

the end point

10

suction box

11

Low pressure source (arrow)

12

Outer area

13

annulus

14

Inner area

15

material

16

surface

17

protective medium

18

material

19

hollow cylinder

20

sheet

21

Facility

22

yoke

23

The End

24

frame

25

Hydrostatic element

26

honeycomb structure

27

tape

28

honeycomb

29

Second roller tube

30

support

31

spacer

32

Inner end

33

Second suction box

34

Third suction box

35

inlet pocket

36

outlet pocket

37

sealing strip

38

Straight band

39

Straight band

40

Zigzag tape

41

contact point

42

recess

43

recess

44 to 49

Honeycomb (honeycomb group)

50 to 55

Honeycomb (honeycomb group)

A-A

intersection

B-B

intersection

C-C

intersection

D.3

Saugwalzendurchmesser

D.4

Rolling tube diameter

d.19

wall thickness

H.14

Height (inner area)

H.26

Height (honeycomb structure)

L.2

Web direction (arrow)

L.3

Length (arrow)

L.4

Length (arrow)

M.3

Roller center (arrow)

p _u

vacuum

Claims (15)

Suction device (1) for a fibrous web (2), in particular paper or board web, producing machine, in particular paper or board machine, comprising a suction roll diameter (D.3) having suction roll (3) with a ¹ em carrying and a roll tube diameter ( D.4) having a roller tube (4) and with a supporting roller (4) arranged support structure (5) which is both permeable to air and a conveyor belt (6) lying thereon and to be dehydrated fibrous web (2) in a looping ( 7), and an external suction box (10), which surrounds the suction roll (3) from the outside partially and the transport belt (6) and thus the fibrous web (2) to be dewatered with an external, of at least one of the suction box (10 Subpressure (PU) supplied to the connected vacuum source (11), wherein at least one annular space (13) between the supporting roller tube (4) of the suction roll (3) and the outer, the transpo 6) of the support structure (5) of the suction roll (3) is present, so that above this the external suction box (10) generated negative pressure (PU) at the on the support structure (5) in a wrap ( 7) lying conveyor belt (6) and thus on the fibrous web (2) to be drained,
characterized,
that the ratio of roller tube diameter (D.4) to Saugwalzendurchmesser (D.3) ≥ 0.75, preferably ≥0,80, in particular ≥ 0.85, is. Suction device (1) according to claim 1,
characterized,
that the annular space (13) of the suction roll (3) consists of at least an inner portion (14) of the supporting structure (5) is formed and that the annular space (13) or in the circumferential direction of the suction roll (3) without interruptions (possible interruptions in the annular space 13) in the circumferential direction of the suction roll (3) are so far apart that the negative pressure effect on the conveyor belt (6) and thus on the fibrous web to be dewatered (2) in the entire Umschlingungsbereich (7) is not disturbed or even prevented. Suction device (1) according to claim 1 or 2,
characterized,
that the roller tube (4) of the suction roll (3) is provided on its outer surface (16) with a protective medium (17), such as a paint, a (spray) coating or a plate with corrosion-resistant sheet, in front of them to protect direct contact with the corrosive process media. Suction device (1) according to one of the preceding claims,
characterized,
in that the outer region (12) of the air-permeable support structure (5) consists of at least one perforated and preferably thin-walled hollow cylinder (19), the perforated hollow cylinder (19) preferably having a wall thickness (d.19) in the range of 0.5 to 8 mm, preferably from 1 to 6 mm, in particular from 2 to 5 mm. Suction device (1) according to one of claims 1 to 3,
characterized,
in that the outer region (12) of the air-permeable support structure (5) consists of at least one honeycomb structure (26) composed of upright bands (27), which has a plurality of honeycombs (28). Suction device (1) according to claim 5,
characterized,
in that the honeycomb structure (26) has a height (H.26) in the range from 3.0 to 25.0 mm, preferably from 4.0 to 20.0 mm, in particular from 5.0 to 15.0 mm. Suction device (1) according to one of the preceding claims,
characterized,
in that the inner region (14) of the air permeable support structure (5) is formed by supports (30) spaced longitudinally of the suction roll (3), such as vertical rings or honeycombs, or spacers (31), such as pins, all of which are part of permeable supporting structure (5). Suction device (1) according to claim 7,
characterized,
in that the inner region (14) of the air-permeable support structure (5) has a height (H.14) in the range from 5.0 to 50.0 mm, preferably from 10.0 to 40.0 mm, in particular from 15.0 to 30 , 0 mm. Suction device (1) according to one of the preceding claims,
characterized,
that the suction roll (3) or at least one additional means (21) for supporting the supporting roll tube (4) over its length (L.4) thereby increasing its carrying capacity and minimizing any deformations. Suction device (1) according to claim 9,
characterized,
in that the additional device (21) comprises a supporting and static yoke (22) which extends through the entire supporting roller tube (4) and is statically supported at its two ends (23) in the racks (24) of the machine. Suction device (1) according to claim 10,
characterized,
that the supporting roll tube (4) is connected via a plurality of hydrostatic elements (25) to the supporting and static yoke (22) supported, wherein the hydrostatic elements (25) are preferably adjustable, in particular controllable / regulatable. Suction device (1) according to claim 9,
characterized,
in that the additional device (21) comprises a second rotating roller tube (4) which extends through the first supporting roller tube (4) and is connected to the first supporting roller tube (4) only in the roller center (M.4). Suction device (1) according to one of the preceding claims,
characterized,
in that at least one further suction box (33, 34) is provided, which adjoins the first suction box (10) and pressurizes the fibrous web (2) to be dewatered with negative pressure (p _U ) via the conveyor belt (6). Suction device (1) according to claim 13,
characterized,
in that the first suction box (10) is designed as a central suction box (10) which partially encloses the suction roll (3) and extends from the inlet gusset (35) to the outlet gusset (36), as seen in the web running direction (L.2) a second suction box (3) is arranged in front of the suction roll (3), which extends up to the first suction box (10) and which is sealed against the conveyor belt (6), and that in the web running direction (L.2) after the suction roll ( 3) a third suction box (34) is arranged, which extends to the first suction box (10) and which is sealed against the conveyor belt (6). Machine for producing a fibrous web (2), in particular paper or board web,
characterized,
in that it comprises at least one suction device (1) according to one of the preceding claims.

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