EP4101977A1 - Wiping strip and kit for use in an installation for producing a paper sheet - Google Patents

Abstract

Scraper bar (3b) for use in a plant for producing a paper web with a screen belt (1), the screen belt (1) being movable across the scraper bar (3b) transversely to the longitudinal extent of the scraper bar (3b), and the scraper bar (3b) wear elements (5b) facing the sieve belt (1), which are mounted on a support bar (4b) and lined up in a row in the direction of the longitudinal extension of the scraper bar (3b). The support strip (4b) has support strip elements (9b) arranged in a row and preferably connected to one another in the longitudinal direction, on which the wearing elements (5b) are fastened.

Description

The present invention relates to a scraper bar for use in a system for producing a paper web with a screen belt, the scraper bar having a longitudinal extent and the screen belt being movable across the longitudinal extent over the scraper bar, and the scraper bar having wear elements facing the screen belt which are mounted on a Support bar mounted and lined up in the direction of the longitudinal extension of the wiper strip.

The present invention also relates to a kit for use in a plant for producing a paper web and a plant for producing a paper web.

Known systems for producing a paper web have a self-contained screen belt which is moved in circulation by means of conveyor rollers and onto which a pulp is sprayed at the start of the system. In a first area of the plant, the screen belt is moved over squeegee strips and over suction boxes designed with squeegee strips, through which liquid that has escaped from the pulp pulp is stripped off and sucked off. In other areas of the plant, the paper web produced on the screen belt is dried using felt belts.

The squeegee strips located in such a system, which are aligned transversely to the direction of movement of the sieve belt, are made of metal or plastic, which on their upper side facing the sieve belt in the operating position has a support or wearing elements made of a wear-resistant material, in particular made of ceramic plates ground flat , exhibit. Such ceramic plates consist in particular of Al oxide, Zr oxide, Si nitride and Si carbide. The main web is moved over the scraper bars at a speed of 1 m/sec to 40 m/sec. The wearing elements are worn out by the friction between the scraper bars and the filter belt.

It is therefore necessary to replace the wiper blades at regular intervals. All squeegee strips available on the market, especially with ceramic wearing elements, which can be up to 12 m long, are made in one piece and precisely adapted to the respective width of the paper machine. They must therefore be produced individually. This individual design has the disadvantage that it is expensive, requires long delivery times and cannot be produced in stock.

The present invention is therefore based on the object of creating a wiping strip that can be individually adapted to desired lengths.

This problem is solved with a squeegee with the features of claim 1.

Preferred embodiments of the invention are subject of the dependent claims.

The wiping strip according to the invention has support strip elements which can have a length of, for example, 0.5 m, 1 m or 2 m. According to the invention, of course, support strip elements can also be produced with any lengths between the specified lengths, as well as shorter or longer support strip elements. In this way, modular parts can be prefabricated in different lengths, from which wiper strips can be produced in almost any length. A squeegee with a total length of e.g. 8.5 m can be made, for example, from four support rail elements with a length of 2 m and one support rail element of 0.5 m.

One, two or more than two wear elements are fastened on the support strip elements, viewed in the longitudinal extension of the support strip.

The support strip elements manufactured as modular parts, each with one or more wearing elements, can be manufactured automatically. As a result, this production step is no longer directly order-related and can be largely automated in a separate production line. These modular parts can be produced to stock and a Wiper strip for a customer can be assembled from several of these parts without delay.

In order to ensure that the individual support strip elements are correctly positioned on one another, in a preferred embodiment of the invention the support strip elements have end faces on which they rest against adjacent support strip elements, with the support strip elements having a form-fitting geometry on one or both end faces which fits into the form-fitting geometry of an adjoining support strip element intervenes.

In a preferred embodiment of the invention, the form-fitting geometry has ribs or tines, which preferably run parallel to the direction of movement of the screen belt. This is advantageous because the critical height of the wearing elements of supporting rail elements that are connected to one another is thus precisely defined.

The object according to the invention is also achieved with a kit having the features of claim 11 .

Such a kit has the advantage that the wiping strip elements according to the invention can be easily and precisely assembled to form wiping strips and installed in a system mounted in a frame.

It is preferred in the invention if sealing elements are arranged between the wiper strips in the region of the ends of the wiper strips. The sealing elements are used to seal the edge area of the kit to the filter belt so that a vacuum can be built up.

In a further preferred embodiment of the invention, the sealing elements have two tensioning elements, which are arranged one behind the other in the direction of the longitudinal extent and abut one another at inclined surfaces which are oriented at an angle other than 90° to the longitudinal extent. By pushing the clamping elements together, they move against each other in the horizontal direction, which increases the effective width of the Sealing elements are enlarged and the sealing elements are fixed between the wiper strips.

The object of the invention is further achieved with a plant for producing a paper web, which has the wiper strips according to the invention and optionally the kit according to the invention.

Fig. 1

einen Abschnitt einer Anlage zur Herstellung einer Papierbahn mit einem Siebband, das über Abstreifleisten und einem darunter befindlichen Saugkasten hinweg bewegt wird, in einem Längsschnitt,

Fig. 2

eine alternative Ausführungsform eines Abschnitt einer Anlage zur Herstellung einer Papierbahn mit einem Siebband, das über Abstreifleisten und einem darunter befindlichen Kasten hinweg bewegt wird, in einem Längsschnitt,

Fig. 3

eine erste Ausführungsform einer erfindungsgemäßen Abstreifleiste, wie sie bei der Ausführungsform von Fig. 2 zum Einsatz kommt,

Fig. 4

ein Tragleistenelement der Ausführungsform gemäß Fig. 3 in vergrößertem Maßstab,

Fig. 5

eine zweite Ausführungsform einer erfindungsgemäßen Abstreifleiste, wie sie bei der Ausführungsform von Fig. 1 zum Einsatz kommt,

Fig. 6

einen erfindungsgemäßen Bausatz im zusammengebauten Zustand,

Fig. 7

ein Ende des Bausatzes von Fig. 6 in vergrößertem Maßstab, und

Fig. 8

das Ende des Bausatzes von Fig. 7 in einer Explosionsdarstellung.

Further features and advantages of the invention result from the following description of preferred exemplary embodiments of the invention, which do not limit the scope of protection, with reference to the attached drawings. It shows:

1

a section of a plant for the production of a paper web with a wire that is moved over scraper strips and a suction box underneath, in a longitudinal section,

2

an alternative embodiment of a section of a plant for the production of a paper web with a screen belt, which is moved over scraper strips and a box located below, in a longitudinal section,

3

a first embodiment of a squeegee according to the invention, as in the embodiment of 2 is used,

4

a support strip element according to the embodiment 3 on an enlarged scale,

figure 5

a second embodiment of a squeegee according to the invention, as in the embodiment of 1 is used,

6

a kit according to the invention in the assembled state,

7

one end of the kit from 6 on an enlarged scale, and

8

the end of the kit from 7 in an exploded view.

In 1 shows a section of a wire 1 in a plant for the production of a paper web, on which there is a layer of pulp 2 and which moves in the direction of the arrow over a group of scraper bars 3a becomes. The pulp 2 is sprayed onto the screen belt 1 at the beginning of this. The squeegee strips 3a have a support strip 4a, on the upper side of which, facing the screen belt 1, wearing elements 5a made of a wear-resistant material are fastened.

one as in 1 The illustrated embodiment of the invention is preferably used in a part of the plant in which the pulp has already been dewatered to a certain extent. Below the wiper strips 3a is therefore a suction box 6, in the interior 7 of which there is a negative pressure of about -2 mbar to -700 mbar. Due to the negative pressure prevailing in the interior 7 of the suction box 6, a suction force is exerted on the pulp 2, by means of which the liquid F contained in this is drawn off. The liquid F emerging from the pulp 2 penetrates the screen belt 1 and reaches the underside of the screen belt 1, from which it is scraped off by the squeegee bars 3a during the movement of the screen belt 1 and enters the suction box 6, through which it is discharged .

In this embodiment of the invention, the squeegee strips 3a are mounted on a frame 16 which is detachably fastened to the upper side of the suction box 6 .

In 2 an embodiment of the invention with scraper strips 3b is shown, which is preferably used in a part of the system in which the pulp 2 still contains a very high proportion of liquid F, which penetrates the sieve belt 1 on its underside even without negative pressure and from the scraper strips 3b can be stripped off. Instead of a suction box 6 as in the embodiment of FIG 1 a box 8 is therefore provided which only serves to drain off the liquid F which has been stripped off.

Also at the in 2 illustrated embodiment of the invention, the squeegee 3b on a support bar 4b, on the upper side facing the screen belt 1 wearing elements 5b made of a wear-resistant material are attached.

The screen belt 1, which can extend over a length of up to about 50 m and usually has a width of 2 m to 12 m, is conveyed by means of conveyor rollers located in the system at a speed of, for example, 1 m/sec to 40 m/sec moved over the squeegee 3a, 3b away.

During the movement of the screen belt 1 over the squeegee strips 3a, 3b, during which the screen belt 1 slides over the surface of the wearing elements 5a, 5b of the squeegee bars 3a, 3b, high frictional resistance occurs, which is caused by the conveyor rollers in the screen belt system for moving the screen belt 1 must be overcome. In addition, this causes high wear of the screen belt 1 and the wearing elements 5a, 5b, as a result of which the screen belt 1 has a short service life and the wiper strips 3a, 3b have a limited service life.

The support rails 4a, 4b are usually, but not necessarily, made of a glass fiber reinforced plastic, acid-resistant stainless steel or a plastic such as polyethylene. The suction box 6 of the embodiment of FIG 1 and box 8 of the embodiment of FIG 2 is usually also made of acid-resistant stainless steel.

The wear elements 5a, 5b located on the support rails 4a, 4b are preferably plates made of a ceramic material, e.g. Al oxide (hardness HV 0.5 18000 N/mm ² ), Zr oxide (hardness HV 0.5 12700 N/mm ² ), Si nitride (hardness HV 0.5 18800 N/mm ² ), Si carbide (hardness HV 0.5 28150 N/mm ² ). The ceramic plates have a length of, for example, 12 mm to 230 mm in the longitudinal extension of the scraper strips 3a, 3b and a width of, for example, 12 mm to 100 mm transversely to the scraper strips 3a, 3b and also a height of, for example, 2 mm to 10 mm. In order to keep the frictional resistance that occurs when a screen belt 1 moves over the squeegee strips 3a, 3b as low as possible, the surfaces of the squeegee strips 3a, 3b, in particular the ceramic plates 5a, 5b, are ground flat according to the prior art, with surface roughness values Ra from 0.15 µm to 0.7 µm.

In 3 a first embodiment of a wiper strip 3b according to the invention is shown, which is composed of support strip elements 9b, the wiper strip 3b having four support strip elements 9b in the embodiment shown. The two middle support strip elements 9b have a length of 2 m, for example, and the two outer support strip elements 9b have a length of 1 m, for example.

In 4 is that in 3 the leftmost support strip element 9b shown in more detail with the subsequent support strip element 9b. On the upper side of the support bar element 9b, which faces the sieve belt 1, several wearing elements 5b are fastened and glued in the longitudinal extension of the squeegee bar 3b, for example by means of positive-locking elements (not shown). Also not shown in the drawings, but it is also possible that two wear elements are present transversely to the longitudinal extent, if necessary more than two wear elements.

The support strip elements 9b each have two end faces 11b, 12b. The central support strip elements 9a have two end faces 11b, which, as in 4 can be seen to have a form-fitting geometry 13 which corresponds to the form-fitting geometry 13 of the end face 11b of an adjoining support strip element 9b. In the illustrated embodiment, the form-fitting geometry consists of ribs or prongs aligned horizontally, ie parallel to the wear elements 5b, so that support rail elements 9b joined together engage one another with their form-fitting geometries 13 in a tooth-like manner. This ensures that the height of the upper side of the wearing elements 5b of supporting strip elements 9b adjoining one another is exactly aligned. Of course, it would also be possible to design the form-fitting geometry 13 in such a way that the support strip elements 9b are also aligned horizontally with the wear elements 5b fastened thereon, but this is less critical.

The support strip elements 9b are preferably glued together at their end faces 11b before they are installed in a system will. Alternatively, the supporting strip elements 9b can also be glued together during installation. Of course, gluing is not absolutely necessary.

As in particular in 4 As can be seen, a support strip element 9b arranged at the end of a support strip 3b can also have a smooth end face 12b, because it does not have to form a positive fit with any adjacent support strip elements 9b.

On their underside, i.e. the side opposite the wear elements 5b, the support strip elements 9b have a depression 14 running in the direction of their longitudinal extension, which in the illustrated embodiment has a T-shaped geometry. Corresponding T-shaped bars 10 are attached to the box 8, onto which the support bar elements 9b are pushed.

In figure 5 a second embodiment of support strip elements 9a is shown, which corresponds to the embodiment of FIG 2 and 3 is similar and preferably, but not necessarily, in the embodiment of FIG 1 is used in conjunction with a kit 15 according to the invention, as described below with reference to FIG Figures 6 to 8 is described.

The embodiment of the support bar 3b of Figures 3 and 4 Said applies in principle to the support bar 3a of Figures 5 to 8 , unless otherwise described below, and vice versa.

The kit 15 has a frame 16 which is composed of crossbeams 17 and longitudinal beams 18 and in which a plurality of scraper strips 3a are mounted. The longitudinal beams 18 have a substantially L-shaped geometry, with recesses in the form of slots 21 being provided in a substantially horizontally aligned leg 19 of the longitudinal beam 18 . The ends of the transverse supports 17 which are flat in the illustrated embodiment are accommodated in these slots 21 so that they are fixed in the longitudinal direction of the longitudinal supports 18 . In addition, the cross member 17 by means of screws 22 to the Fixed longitudinal members 18, which are screwed through the longitudinal members 18 in the end faces of the cross member 17.

The wiper strips 3a can be used in the stable frame 16 produced in this way. The distance between the crossbeams 17 depends on the one hand on the length of the support rail elements 9a and is chosen such that each support rail element 9a rests on at least two crossbeams 17 . On the other hand, the distance between the crossbeams 17 is determined by the load to be expected from the negative pressure in the suction box 6 .

The crossbeams 17 have at their upper edge recesses 20, in the center of which are pins 23. The support strip elements 9a have bores 24 on their underside. In the installed state, the wiper strips 3a sit in the recess 20 of the crossbeam 17 and the pins 23 of the crossbeam 17 protrude into the bore 24 of the support strip elements 9a. The support strip elements 9a are fastened to the crossbeam 17 by filling the bores 24 with adhesive.

Between the recesses 20 are located on the crossbeams 17 wider, flat webs 30 which serve as supports for the sealing elements 25 . These sealing elements 25 are arranged on both sides between the front ends of the wiper strips 3a. In the illustrated embodiment, the sealing elements 25 each consist of two clamping elements 26, 27 which abut one another on inclined surfaces 28 which are aligned at an angle α unequal to 90°, preferably between 45° and 60°, to the longitudinal extent of the wiper strips 3a.

The clamping elements 26, 27 are pulled towards one another by a clamping screw 29 which is passed through a through hole in one clamping element 26 and is screwed into the other clamping element 27. Of course, it would also be possible to provide through holes in both clamping elements 26, 27 and to tighten the clamping screw 29 with a nut. By tightening the clamping screw 29, the clamping elements 26 slide against each other along the inclined surfaces 28, whereby the effective The overall width of the sealing element 25 is increased and the sealing element 25 is fixed between the wiper strips 3a or their end support strip elements 9a.

Springs 32 are arranged on both sides 31 of the clamping elements 26, 27 and engage in grooves 33 on both sides 34 of the supporting strip elements 9a, so that the clamping elements 26, 27 are secured in their correct position.

Reference list:

1

main web

2

pulp

3a, 3b

squeegee bars

4a, 4b

support rails

5a, 5b

wear elements

6

suction box

7

inner space

8th

Crate

9a, 9b

support rail elements

10

T-shaped bars

11a, 11b

end faces

12a, 12b

end faces

13

Form fit geometry

14

T-shaped indentations

15

kit

16

frame

17

cross member

18

side members

19

leg

20

recesses

21

slots

22

screws

23

cones

24

drilling

25

sealing elements

26

clamping elements

27

clamping elements

28

bevels

29

clamping screws

30

webs

31

sides of the clamping elements

32

feathers

33

grooves

34

sides of the support rail elements

f

liquid

Claims (15)

Wiper bar for use in a plant for producing a paper web with a screen belt (1), the wiper bar (3a, 3b) having a longitudinal extent and the screen belt (1) being movable transversely to the longitudinal extent over the wiper bar (3a, 3b), and wherein the wiping strip (3a, 3b) has wearing elements (5a, 5b) facing the sieve belt (1), preferably ceramic plates, which are mounted on a support strip (4a, 4b) and lined up in the direction of the longitudinal extent of the wiping strip (3a, 3b), characterized characterized in that the support strip (4a, 4b) has support strip elements (9a, 9b) which are lined up in a row in the direction of the longitudinal extent and are preferably connected to one another and on which the wearing elements (5a, 5b) are fastened. Wiper strip according to Claim 1, characterized in that the length of a wear element (5a, 5b), measured in the direction of the longitudinal extent, corresponds to the length of a support strip element (9a, 9b). Scraper strip according to Claim 1 or 2, characterized in that two or more than two wearing elements (5) are lined up in a row on a support strip element (9a, 9b) in the direction of the longitudinal extension. Wiper strip according to one of Claims 1 to 3, characterized in that the support strip elements (9a, 9b) have end faces (11a, 11b) on which they bear against adjacent support strip elements (9a, 9b) and are preferably glued together. Wiper strip according to Claim 4, characterized in that the support strip elements (9a, 9b) have a form-fitting geometry (13) on one or both end faces (11a, 11b) which engages in the form-fitting geometry (13) of an adjoining support strip element (9a, 9b). Squeegee according to Claim 4 or 5, characterized in that the form-fitting geometry (13) has teeth which preferably run parallel to the direction of movement of the sieve belt (1). Wiper strip according to one of Claims 1 to 6, characterized in that the support strip elements (9b) have, on their side opposite the wear elements (5b), a depression (14) which preferably runs in the direction of the longitudinal extension and which preferably has a T-shaped or trapezoidal shape has cross section. Kit for use in a plant for producing a paper web with a screen belt (1), characterized by - two or more than two wiper strips (3a) arranged parallel next to one another according to one of claims 1 to 7, - a frame (16) with two or more than two crossbeams (17) arranged transversely under the squeegee strips (3a), and - Two longitudinal members (18) connected to the cross members (17), which are arranged parallel to the squeegee strips (3a) and between which the squeegee strips (3a) are accommodated. Kit according to Claim 8, characterized in that recesses (21), in which the ends of the cross members (17) are received, are arranged on the longitudinal members (18). Kit according to Claim 8 or 9, characterized in that recesses (20) with pins (23) arranged therein are arranged on the crossbeams (17) and interact with bores (24), and that the pins (23) are preferably in the bores (24) are glued in. Kit according to one of Claims 8 to 10, characterized in that sealing elements (25) are arranged between the wiping strips (3a) in the region of the ends of the wiping strips (3a). Kit according to Claim 11, characterized in that the sealing elements (25) have two clamping elements (26, 27) which are arranged one behind the other in the direction of the longitudinal extension and abut one another on inclined surfaces (28) which are at an angle (α) not equal to 90° are aligned to the longitudinal extent and that preferably the clamping elements (26, 27) are braced against one another by means of a clamping screw (29). Kit according to one of Claims 8 to 12, characterized in that at least one of the clamping elements (26, 27) has a tongue (32) or groove running in the direction of the longitudinal extension, which groove (33) or tongue of an adjacent support strip element (9a) intervenes. Plant for producing a paper web with a screen belt (1) and scraper bars (3a, 3b), the screen belt (1) being movable transversely over the scraper bars (3a, 3b), and the scraper bars (3a, 3b) being attached to the screen belt (1st ) have facing wear elements (5a, 5b) which are mounted on a support strip (4a, 4b) and lined up in the direction of the longitudinal extension of the scraper strip (3a, 3b), characterized in that the scraper strips (3a, 3b) according to one of the claims 1 to 7 are executed. Plant for producing a paper web with a screen belt (1) and scraper bars (3a), the screen belt (1) being movable transversely over the scraper bars (3a), and the scraper bars (3a) having wear elements (5a) facing the screen belt (1) which are mounted on a supporting strip (4a) and lined up in a row in the direction of the longitudinal extension of the wiping strip (3a), characterized in that the system has a kit according to one of Claims 8 to 13.

Images