Doctor strip for use in an apparatus for producing a paper web using a screen belt

Abstract

The invention relates to a scraper strip (3b) for use in an apparatus for producing a paper web using a screen belt (1), wherein the screen belt (1) can be moved on the scraper strip (3b) transversely to the longitudinal extension of the scraper strip (3b), and wherein the scraper strip (3b) has wear elements (5b) facing the screen belt (1), which are mounted on a carrier strip (4b) and arranged in the direction of the longitudinal extension of the scraper strip (3b). The carrier strip (4b) has carrier strip elements (9b) arranged in the longitudinal extension and preferably connected to each other, to which the wear elements (5b) are fixed.

Description

Technical Field

[0001] The invention relates to a scraper bar for use in an apparatus for producing a paper web using a screen belt, wherein the scraper bar has a longitudinal extension and the screen belt can be moved on the scraper bar transversely to the longitudinal extension, and wherein the scraper bar has wear elements facing the screen belt, which are mounted on a supporting strip and are arranged in the direction of the longitudinal extension of the scraper bar.

[0002] The invention further relates to a kit for use in a device for producing a paper web and to a device for manufacturing a paper web. Background Art

[0003] A known system for producing paper webs has a self-closing screen belt which is moved in a circular motion by means of transport rollers and onto which a fiber suspension is sprayed at the start of the system. In a first area of ​​the system, the screen belt moves over scraper bars and a suction box provided with the scraper bars, through which liquid escaping from the fiber suspension is scraped off and sucked out. In other areas of the system, the paper web produced on the screen belt is dried by means of a felt belt.

[0004] The scraper strips located in such devices and oriented transversely to the direction of movement of the screen belt are strips made of metal or plastic, which have a support or a wear element on their upper side facing the screen belt in the operating position, which is made of a wear-resistant material, in particular a ground ceramic plate. Such ceramic plates are made in particular of aluminum oxide, zirconium oxide, silicon nitride and silicon carbide. The screen belt moves over the scraper strips at a speed of 1 m / s to 40 m / s. The wear element is worn due to the friction between the scraper strips and the screen belt.

[0005] Therefore, the scraper strips need to be replaced regularly. All scraper strips available on the market, in particular scraper strips with ceramic wear elements (which can have a length of up to 12 m), are one-piece and are precisely adapted to the respective width of the paper machine. Therefore, the scraper strips must be produced individually. This individual design has the disadvantage that it is expensive, requires long delivery times, and production in a warehouse is not possible. Summary of the invention

[0006] The object of the present invention is therefore to provide a wiper strip which can be individually adapted to a desired length.

[0007] This technical problem is solved by a scraper strip for use in a device for producing paper webs using a screen belt, wherein the scraper strip has a longitudinal extension and the screen belt can move on the scraper strip transversely to the longitudinal extension, and wherein the scraper strip has a wear element facing the screen belt, the wear element is mounted on a supporting strip and arranged in the direction of the longitudinal extension of the scraper strip. According to the invention, the supporting strip has supporting strip elements arranged in the longitudinal extension and preferably connected to each other, and the wear element is fixed to the supporting strip element.

[0008] In addition, the technical features involved in the different embodiments of the present disclosure described below can be combined with each other as long as they do not conflict with each other.

[0009] The wiper strip according to the invention has a carrier strip element which can have a length of, for example, 0.5 m, 1 m or 2 m. According to the invention, of course, carrier strip elements with any length between the lengths given and shorter or longer carrier strip elements can also be produced. Thus, modular components of different lengths can be prefabricated, from which wiper strips of almost any length can be produced. For example, a wiper strip with a total length of, for example, 8.5 m can be produced, for example, from four carrier strip elements with a length of 2 m and one carrier strip element with a length of 0.5 m.

[0010] Viewed in the longitudinal extension of the carrier strip, in each case one, two or more than two wear elements are fastened to the carrier strip element.

[0011] The carrier strip elements, each with one or more wear elements, produced as modular components can be produced automatically. This production step is therefore no longer directly order-dependent and can be largely automated in a separate production line. These modular components can be produced in a warehouse and the customer's wiper strip can be assembled from a number of these components without delay.

[0012] In order to ensure the correct positioning of the individual supporting strip elements relative to each other, in a preferred embodiment of the present invention, the supporting strip elements have end sides, which are abutted against adjacent supporting strip elements, wherein the supporting strip elements have a form-fitting geometry on one or both end sides, which is embedded in the form-fitting geometry of the adjacent supporting strip elements.

[0013] In a preferred embodiment of the invention, the form-fitting geometry has ribs or pointed teeth, which preferably extend parallel to the direction of motion of the screen belt. This is advantageous because the critical height of the wear elements of the mutually adjacent carrier strip elements is thus precisely determined.

[0014] The object of the invention is furthermore achieved by a kit for use in a plant for producing a paper web using a screen belt, the kit comprising:

[0015] Two or more parallel and side-by-side scraper strips according to the foregoing;

[0016] A frame with two or more transverse supports arranged transversely below the wiper strip

[0017] and two longitudinal supports connected to the transverse support, which are arranged parallel to the wiper strip and between which the wiper strip is accommodated.

[0018] Such a kit has the advantage that the wiper strip elements according to the invention can be assembled in a simple and precise manner to form a wiper strip and installed in a device in a frame-mounted manner.

[0019] In the invention, preferably, in the end region of the scraper strips, a sealing element is arranged between the scraper strips. The sealing element serves to seal the edge region of the sleeve relative to the screen belt so that a vacuum can be established.

[0020] In a further preferred embodiment of the invention, the sealing element has two clamping elements which are arranged one behind the other in the direction of the longitudinal extension and bear against each other on inclined surfaces which are oriented at an angle not equal to 90° relative to the longitudinal extension. By pushing the clamping elements together, they are displaced relative to each other in the horizontal direction, thereby increasing the effective width of the sealing element and fixing the sealing element between the wiper strips.

[0021] The object of the invention is also achieved with a device for producing a paper web, which device has a doctor bar according to the invention and, if applicable, a kit according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features and advantages of the present invention are derived from the following description of preferred embodiments of the present invention with reference to the accompanying drawings, which do not limit the scope of protection.

[0023] Figure 1 A section of a plant for producing a paper web with a screen belt which moves over a doctor bar and a suction box located therebelow is shown in longitudinal section;

[0024] Figure 2 An alternative embodiment of a section of a device for producing a paper web with a screen belt which moves over a doctor bar and a suction box located therebelow is shown in longitudinal section;

[0025] Figure 3A first embodiment of a wiper strip according to the invention is shown, which wiper strip is for example Figure 2 Used in the implementation method;

[0026] Figure 4 The diagram is shown on an enlarged scale. Figure 3 The load-bearing strip element of the embodiment;

[0027] Figure 5 A second embodiment of a wiper strip according to the invention is shown, which is used, for example, in Figure 1 in the implementation mode;

[0028] Figure 6 shows a kit according to the invention in an assembled state;

[0029] Figure 7 Shown on an enlarged scale Figure 6 the end of the kit; and

[0030] Figure 8 The exploded view shows Figure 7 The end of the kit. DETAILED DESCRIPTION

[0031] Figure 1 A section of a screen belt 1 in a plant for producing a paper web is shown, on which a layer of a fiber suspension 2 is present and which moves in the direction of the arrow over a set of scraper strips 3a. The fiber suspension 2 is sprayed onto the screen belt 1 at the beginning of the screen belt 1. The scraper strips 3a have a carrier strip 4a, on the upper side of which, facing the screen belt 1, a wear element 5a made of a wear-resistant material is fixed.

[0032] The present invention Figure 1 The embodiment shown is preferably used in a part of the device in which the fiber suspension has been dehydrated to a certain extent. Therefore, there is a suction box 6 below the scraper bar 3a, and there is a negative pressure of about -2 mbar to -700 mbar in its inner space 7. By the negative pressure existing in the inner space 7 of the suction box 6, a suction force is applied to the fiber suspension 2, and the liquid F contained in the fiber suspension 2 is sucked out by this suction force. The liquid F escaping from the fiber suspension 2 passes through the screen belt 1 and reaches the bottom of the screen belt 1. When the screen belt 1 moves on the scraper bar 3a, the liquid is scraped off from the bottom of the screen belt 1 by the scraper bar and enters the suction box 6, and the liquid is discharged through the suction box.

[0033] In this embodiment of the invention, the scraper strip 3 a is mounted on a frame 16 which is detachably fixed to the upper side of the suction box 6 .

[0034] Figure 2An embodiment of the invention with a scraper strip 3 b is shown, which is preferably used in parts of the apparatus in which the fiber suspension 2 still contains a very high proportion of liquid F, which even in the absence of negative pressure passes through the underside of the screen belt 1 and can be scraped off by the scraper strip 3 b. Figure 1 In the embodiment of FIG. 5 , the suction box 6 is provided with a box 8 which is only used to discharge the scraped liquid F.

[0035] exist Figure 2 In the embodiment of the invention shown, the scraper strip 3 b also has a carrier strip 4 b , on the upper side of which facing the screen belt 1 a wearing element 5 b made of a wear-resistant material is fixed.

[0036] The screen belt 1 , which can extend over a length of up to 50 m and typically has a width of 2 to 12 m, moves over the scraper strips 3a, 3b at a speed of, for example, 1 to 40 m / s via transport rollers located in the device.

[0037] When the screen belt 1 moves on the scraper strips 3a, 3b (at this time, the screen belt 1 slides on the surface of the wear elements 5a, 5b of the scraper strips 3a, 3b), a high friction resistance occurs, which must be overcome by the transport rollers located in the screen belt device for moving the screen belt 1. In addition, this leads to high wear of the screen belt 1 and the wear elements 5a, 5b, as a result of which the screen belt 1 has a short service life and the scraper strips 3a, 3b have a limited service life.

[0038] The support strips 4 a , 4 b are usually, but not necessarily, made of glass-fiber-reinforced plastic, acid-resistant refined steel or a plastic such as polyethylene. Figure 1 The suction box 6 of the embodiment and Figure 2 The box 8 of the embodiment of FIG. 1 is also usually made of acid-resistant refined steel.

[0039] The wear elements 5a, 5b located on the support strips 4a, 4b are preferably made of a ceramic material, for example aluminum oxide (hardness HV0.5 18000 N / mm 2 )、Zirconium oxide (Hardness HV0.5 12700N / mm 2 ), silicon nitride (hardness HV0.5 18800N / mm 2 ), Silicon carbide (Hardness HV0.5 28150N / mm 2). The ceramic plate has 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 further has a height of, for example, 2 mm to 10 mm. In order to keep the friction resistance occurring when the screen belt 1 moves on the scraper strips 3a, 3b as low as possible, the surface of the scraper strips 3a, 3b, in particular the ceramic plates 5a, 5b, is ground flat according to the prior art, wherein it has a surface roughness value Ra of 0.15 μm to 0.7 μm.

[0040] Figure 3 A first embodiment of a wiper strip 3b according to the invention is shown, which is assembled from support strip elements 9b, wherein in the embodiment shown, the wiper strip 3b has four support strip elements 9b. The two middle support strip elements 9b have a length of, for example, 2 m, and the two outer support strip elements 9b have a length of, for example, 1 m.

[0041] Figure 4 More details are shown in Figure 3 In the longitudinal extension of the scraper strip 3b, a plurality of wear elements 5b are fixed and glued, for example by form-fit elements (not shown), to the upper side of the support strip element 9b facing the screen belt 1. It is also not shown in the figures, but it is also possible that two wear elements, if necessary more than two wear elements, are also present transversely to the longitudinal extension.

[0042] The support strip elements 9b each have two end sides 11b, 12b. The middle support strip element 9a has two end sides 11b, which are as shown in FIG. Figure 4 As can be seen in the figure, the carrier strip element 9b has a positive-fitting geometry 13, which corresponds to the positive-fitting geometry 13 of the end side 11b of the adjacent carrier strip element 9b. In the embodiment shown, the positive-fitting geometry is formed by ribs or teeth oriented horizontally, that is, oriented parallel to the wear element 5b, so that the carrier strip elements 9b connected to each other engage in a tooth-like manner with their positive-fitting geometry 13. This ensures that the upper sides of the wear elements 5b of the adjacent carrier strip elements 9b are precisely aligned in their height. It is of course also possible to design the positive-fitting geometry 13 in such a way that a precisely aligned orientation of the carrier strip element 9b and the wear element 5b fastened thereto is also provided in the horizontal direction, but this is not very important.

[0043] Before the support strip elements are installed in the device, the support strip elements 9b are preferably glued to each other on their end sides 11b. Alternatively, the support strip elements 9b can also be glued to each other during installation. Of course, gluing is not absolutely necessary.

[0044] As especially in Figure 4 As can be seen in FIG. 1 , a support strip element 9 b arranged at the end of a support strip 3 b can also have a smooth end side 12 b , since this end side 12 b does not have to form a positive fit with an adjacent support strip element 9 b .

[0045] On its underside, i.e. the side opposite the wear element 5b, the carrier strip element 9b has a depression 14 extending in the direction of its longitudinal extension, which in the embodiment shown has a T-shaped geometry. A corresponding T-shaped strip 10 is fastened to the box 8, onto which the carrier strip element 9b is pushed and slid.

[0046] Figure 5 A second embodiment of a carrier strip element 9a is shown, which is similar to Figure 2 and Figure 3 and preferably, but not necessarily, in combination with the kit 15 according to the invention. Figure 1 In the embodiment of the present invention, the kit is described below, for example Figures 6 to 8 Give a description.

[0047] Unless otherwise stated below, Figure 3 and 4 The contents described in the embodiment of the support strip 3b also apply in principle to Figures 5 to 8 of the load-bearing strip 3a, and vice versa.

[0048] The kit 15 has a frame 16, which is composed of a transverse support 17 and a longitudinal support 18 and in which a plurality of wiper strips 3a are mounted. The longitudinal support 18 has an essentially L-shaped geometry, wherein recesses in the form of slots 21 are arranged in the essentially horizontally oriented legs 19 of the longitudinal support 18. In the embodiment shown, the ends of the flat transverse support 17 are accommodated in these slots 21, so that these ends are fixed in the longitudinal direction of the longitudinal support 18. In addition, the transverse support 17 is fixed to the longitudinal support 18 by screw fasteners 22, which are screwed into the end side of the transverse support 17 through the longitudinal support 18.

[0049] The wiper strip 3a can be installed in the stable frame 16 produced in this way. The distance between the transverse supports 17 depends on the length of the support strip elements 9a and is selected so that each support strip element 9a is supported on at least two transverse supports 17. On the other hand, the distance between the transverse supports 17 is determined by the expected load caused by the negative pressure in the suction box 6.

[0050] The transverse support 17 has a recess 20 at its upper edge, in the center of which a pin 23 stands. The support strip element 9a has a hole 24 on its underside. In the installed state, the wiper strip 3a is located in the recess 20 of the transverse support 17, and the pin 23 of the transverse support 17 projects into the hole 24 of the support strip element 9a. The support strip element 9a is fixed to the transverse support 17 by filling the hole 24 with adhesive.

[0051] Between the recesses 20, a wider, flat web 30 is located on the transverse support 17, which serves as a support for a sealing element 25. The sealing element 25 is arranged on two sides between the end-side ends of the wiper strip 3a. In the embodiment shown, the sealing element 25 is composed of two clamping elements 26, 27, which are in contact with each other on an inclined surface 28, which is oriented at an angle α not equal to 90°, preferably between 45° and 60°, relative to the longitudinal extension of the wiper strip 3a.

[0052] The clamping elements 26, 27 are pulled toward each other by means of a clamping screw 29 which is guided through a through hole in the clamping element 26 and screwed into the other clamping element 27. Of course, it is also 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 overall width of the sealing element 25 is increased and the sealing element 25 is fixed between the wiper strip 3a or the end-side carrier strip elements 9a thereof.

[0053] Arranged on two side faces 31 of the clamping elements 26 , 27 are springs 32 which engage in grooves 33 on two side faces 34 of the support strip element 9 a , so that the clamping elements 26 , 27 are fixed in their correct position.

[0054] It should be understood that the above description is only some embodiments of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present disclosure is not limited to the technical solutions formed by a specific combination of the above technical features, but also should cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept.

[0055] Reference numerals list

[0056] 1 Screen belt

[0057] 2 Fiber suspension

[0058] 3a, 3b Scraping strips

[0059] 4a, 4b Load-bearing strips

[0060] 5a, 5b Wear elements

[0061] 6 Suction box

[0062] 7. Internal Space

[0063] 8 boxes

[0064] 9a, 9b Load-bearing strip elements

[0065] 10 T-shaped strips

[0066] 11a, 11b side

[0067] 12a, 12b End side

[0068] 13 Form-fitting geometry

[0069] 14 T-shaped concave part

[0070] 15 Kits

[0071] 16 Frame

[0072] 17 Transverse bearing

[0073] 18 Longitudinal bearing member

[0074] 19 Side Leg

[0075] 20 concavity

[0076] 21 Gap

[0077] 22 Threaded fasteners

[0078] 23 Pegs

[0079] 24 holes

[0080] 25 Sealing element

[0081] 26 Clamping element

[0082] 27 Clamping element

[0083] 28 Inclined Surface

[0084] 29 Clamping threaded fasteners

[0085] 30 splice

[0086] 31 Side of the clamping element

[0087] 32 Spring

[0088] 33 slots

[0089] 34 Side of the load-bearing strip element

[0090] F Liquid

Claims

1. A doctor bar for use in an apparatus for producing a paper web using a screen belt (1), wherein: The scraper strips (3a, 3b) have a longitudinal extension, and the screen belt (1) can move on the scraper strips (3a, 3b) transversely to the longitudinal extension, and wherein the scraper strips (3a, 3b) have wear elements (5a, 5b) facing the screen belt (1), and the wear elements are mounted on the supporting strips (4a, 4b) and arranged in the direction of the longitudinal extension of the scraper strips (3a, 3b), wherein the supporting strips (4a, 4b) have supporting strip elements (9a, 9b) arranged in the longitudinal extension, and wherein the supporting strips (4a, 4b) have supporting strip elements (9a, 9b) arranged in the longitudinal extension. The wear element (5a, 5b) is fixed to the carrier strip element, wherein the carrier strip element (9a, 9b) has an end side (11a, 11b) on which the carrier strip element rests on an adjacent carrier strip element (9a, 9b), characterized in that the carrier strip element (9a, 9b) has a form-fitting geometric structure (13) on one or both end sides (11a, 11b), and the form-fitting geometric structure is embedded in the form-fitting geometric structure (13) of the adjacent carrier strip element (9a, 9b).

2. The wiper strip according to claim 1, characterized in that The carrier strip elements (9a, 9b) are connected to each other.

3. The wiper strip according to claim 1, characterized in that The wear elements (5a, 5b) are ceramic plates.

4. The wiper strip according to claim 1, characterized in that The length of the wear elements (5a, 5b) measured in the direction of the longitudinal extension corresponds to the length of the carrier strip elements (9a, 9b).

5. The wiper strip according to claim 1, characterized in that Two or more than two wear elements (5a, 5b) are arranged on the carrier strip element (9a, 9b) in the direction of longitudinal extension.

6. The wiper strip according to claim 1, characterized in that The support strip elements (9a, 9b) are glued to one another at their end sides (11a, 11b).

7. The wiper strip according to claim 1, characterized in that The positive-fitting geometry (13) has pointed teeth.

8. The wiper strip according to claim 7, characterized in that The pointed teeth extend parallel to the direction of movement of the screen belt (1).

9. The wiper strip according to claim 1, characterized in that The support strip element (9b) has a depression (14) on its side opposite the wearing element (5b).

10. The wiper strip according to claim 9, characterized in that The recessed portion (14) extends along the longitudinal direction.

11. The wiper strip according to claim 9, characterized in that The recessed portion (14) has a T-shaped or trapezoidal cross section.

12. A kit for use in an apparatus for producing a paper web using a screen belt (1), characterized in that The kit has: - two or more wiper strips (3a) according to any one of claims 1 to 11 arranged parallel to one another, - a frame (16) with two or more transverse supports (17) arranged transversely below the wiper strip (3a), and Two longitudinal supports (18) connected to the transverse support (17), which are arranged parallel to the wiper strip (3a) and between which the wiper strip (3a) is accommodated.

13. The kit according to claim 12, characterized in that A recess is arranged on the longitudinal support (18), in which the end of the transverse support (17) is received.

14. The kit according to claim 12, characterized in that A recess (20) is arranged on the transverse support (17) together with a peg (23) arranged in the recess (20) and cooperating with a hole (24).

15. The kit according to claim 14, characterized in that The peg (23) is glued into the hole (24).

16. The kit according to claim 12, wherein: In the region of the ends of the wiper strips (3a), a sealing element (25) is arranged between the wiper strips (3a).

17. The kit according to claim 16, characterized in that The sealing element (25) has two clamping elements (26, 27) which are arranged one behind the other in the direction of the longitudinal extension and bear against each other on an inclined surface (28) which is oriented at an angle (α) not equal to 90° relative to the longitudinal extension.

18. The kit according to claim 17, characterized in that The clamping elements (26, 27) are clamped to one another by means of a clamping screw (29).

19. A kit according to claim 17 or 18, characterized in that At least one of the clamping elements (26, 27) has a spring (32) or a groove extending in the direction of the longitudinal extension, which engages in a groove (33) or a spring of the abutting support strip element (9a).

20. An apparatus for producing a paper web using a screen belt (1) and doctor bars (3a, 3b), wherein: The screen belt (1) is capable of transverse movement on the scraper strips (3a, 3b), and wherein the scraper strips (3a, 3b) have wear elements (5a, 5b) facing the screen belt (1), the wear elements are mounted on the supporting strips (4a, 4b) and are arranged along the longitudinal extension direction of the scraper strips (3a, 3b), characterized in that a scraper strip (3a, 3b) according to any one of claims 1 to 11 is implemented.

21. An apparatus for producing a paper web using a screen belt (1) and a doctor bar (3a), wherein: The screen belt (1) is capable of moving laterally on the scraper strip (3a), and wherein the scraper strip (3a) has a wear element (5a) facing the screen belt (1), the wear element is mounted on the supporting strip (4a) and arranged along the longitudinal extension direction of the scraper strip (3a), characterized in that the device has a kit according to any one of claims 12 to 19.

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