CA2794186A1 - Supporting element, such as a foil or wire board, for use in a papermaking installation - Google Patents

Abstract

A supporting element, such as a foil or supporting board, is configured for use in a papermaking installation which has at least one wire and at least one felt that can be moved over supporting elements. The supporting element, which can be fixed to a supporting frame of the system, directly or by way of a supporting element, is formed with wear protection in that area in which the wire or the felt comes into contact with it. The supporting element is formed by a composite element which has a layer of a metallic carrier material and a layer of a hard metal alloy in which hard materials are embedded. The hard metal layer is sintered onto the metallic carrier layer.

Description

SUPPORTING ELEMENT, SUCH AS FOIL OR WIRE BOARD, FOR USE IN A PAPERMAKING INSTALLATION

CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority, under 35 U.S.C. 119, of Austrian patent application AT A1748/2011, filed November 28, 2011; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION
Field of the Invention:

[0002] The present invention relates to a supporting element, such as a foil or wire board, for use in a papermaking installation which has at least one wire and preferably at least one felt which can be moved over supporting elements, the supporting element, which can be fixed to a supporting frame of the system, directly or by means of a supporting element, being formed with wear protection in that area in which the wire or the felt comes into contact.

[0003] Papernnaking installations are constructed with a wire, which is moved along the system, paper stock being sprayed onto the wire in the direction of movement of the wire at the beginning of this system. The wire is guided over supporting elements, such as foils and wire boards, the water in the paper stock being drawn off, by which means a web or strip of paper is produced.

[0004] As a result, this strip of paper can be transferred to a likewise moving felt, being dried further. The felt is also guided over supporting elements, such as supporting bars and supporting boards.

[0005] In the further course, the strip of paper is smoothed by means of rolls and wound up on drums.

[0006] Since the supporting elements over which the wires or the felts are guided are subjected to very high wear, which is also caused by fibrous materials being carried along with the water emerging from the paper stock, they have to be constructed with wear protection in that area in which the wire or the felt comes into contact.

[0007] According to the known prior art, the supporting elements are coated with at least one layer of ceramic plates in that area in which the wire or the felt comes into contact. Ceramic plates of this type, which, for example, consist of aluminum oxide, are produced by pressing powdery starting material at high pressures in a mold to form plates, which are then sintered. These plates therefore meet the requirements for wear protection in supporting elements in papermaking installations, since they exhibit very high hardness and therefore very high wear resistance.

[0008] However, when they are used as wear protection in supporting elements for wires or felts, the ceramic plates have a number of disadvantages:

[0009] Since these plates can be produced only with small dimensions, there is the need, when coating a foil or a wire board, to arrange a multiplicity of plates beside one another. It is thereby necessary to ensure that their surfaces are located in a single plane, in which the wire or felt is moved.

[0010] Furthermore, because of the intended hardness of these ceramic plates, their processing is very complicated and expensive. In addition, because of the brittleness of these ceramic plates, there is a high risk of breakage, it being possible for the wire or the felt to be damaged in the case of breakages of plates, for which reason those supporting elements in which the ceramic plates are broken have to be replaced. In addition, foils coated with ceramic plates through which a suction action is exerted on the paper stock located on the wire exhibit different effects over their length transverse to the direction of movement of the wire or of the strip of paper on account of the gaps between the individual plates, as a result of which the quality of the strip of paper is impaired because of inhomogeneities.

SUMMARY OF THE INVENTION

[0011] It is accordingly an object of the invention to provide a supporting element, such as foil or wire board, for use in a papermaking installation which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for a supporting element for a wire system in which, although it likewise exhibits very high wear resistance, the disadvantages of the supporting elements coated with ceramic plates are avoided.

[0012] With the foregoing and other objects in view there is provided, in accordance with the invention, a supporting element in a papermaking installation equipped with at least one wire and at least one felt to be moved over supporting elements. The supporting element, which is embodied as a foil or a supporting board, can be affixed to a supporting frame of the papermaking installation, directly or by way of a carrier element, and the supporting element is a composite element formed with wear protection in a region thereof in which the supporting element comes into contact with the wire or the felt; and the composite element has a layer of a metallic carrier material and a hard metal layer sintered onto said metallic carrier layer, the hard metal layer being formed of a hard metal alloy having hard materials embedded therein.

[0013] European patent EP 446978 B1 describes forming the sliding mounting of swivel plates as a hard nickel alloy, in which hard materials are embedded.

European published patent application EP 816525 Al describes constructing a screen plate formed with passage openings for screening granular solid materials with a wear protection layer of a hard metallic alloy which is joined metallurgically to a protective layer of iron material, hard materials being embedded in the hard alloy.

[0014] By contrast, it has previously not been known to use hard metallic alloys with hard materials embedded in the latter as wear protection in supporting elements in papermaking installations. The reason for this resides in the fact that, by way of wear protection plates of a ceramic material as compared with wear protection plates of hard metallic alloys, substantially longer acting wear protection is effected because of the far greater hardness of the ceramic material as compared with hard metallic alloys.

[0015] The disadvantages of ceramic plates used hitherto as supporting elements in papermaking installations are avoided, according to the invention, in that the supporting element is formed by a composite element which comprises a layer of a metallic carrier material and a layer of a hard metallic alloy in which hard materials are embedded, the hard metal alloy being sintered onto the metallic carrier material.

[0016] The present invention is based on the finding that, by using a wear protection material which is known from unrelated prior art in supporting elements in papermaking installations, although the wear resistance as such is lower than in the case of the ceramic plates used hitherto, as a result of using a hard metallic alloy with embedded hard materials as wear protection in supporting elements in wire systems or felt systems, a number of critical advantages are achieved with regard to the manufacture, the possible uses and the specific requirements in papermaking installations.

[0017] The layer of the metallic carrier material is preferably composed of a corrosion- and acid-resistant stainless steel alloy, in particular an austenitic stainless steel having the material quality WS 1.4571 (AISI 316Ti) or WS
1.4404 (AISI 316L). According to a preferred embodiment, the layer of the hard metallic alloy is composed of a nickel-based hard alloy or it contains a nickel-based hard alloy. In particular, the layer of the hard metallic alloy is composed of a mixture of an iron-based hard alloy and a nickel-based hard alloy or of a nickel-molybdenum-based hard alloy. Likewise, the layer of the hard metallic alloy can be composed of a mixture of an iron-based hard alloy and a nickel-molybdenum hard alloy.

[0018] The hard materials are preferably formed by chromium carbides, tungsten carbides, silicon carbides and boron carbides as such or in mixtures, and the proportion of hard materials in the basic hard alloy is 50% by weight to 90% by weight.

[0019] Other features which are considered as characteristic for the invention are set forth in the appended claims.

[0020] Although the invention is illustrated and described herein as embodied in a supporting element, such as foil or wire board, for use in a papermaking installation, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

[0021] The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0022] Fig. 1, Fig. 1A show a wire system in a papermaking installation in a schematic illustration, a first sub-area of this wire system being shown in Fig. 1 and the following second sub-area being shown in Fig. 1A, [0023] Fig. 2, Fig. 2A show a first embodiment of a foil in cross section according to the line II-II in Fig. 2A and in longitudinal section according to the line 11A-IIA in Fig. 2A, [0024] Fig. 3, Fig. 3a show a second embodiment of a foil in cross section according to the line 111-11I in Fig. 3A and in longitudinal section according to the line IIIA-IIIA in Fig.3, [0025] Fig. 4, Fig. 4A, Fig. 4B, Fig. 4C, Fig. 4D, Fig. 4E show six embodiments of foils, each in cross section, [0026] Fig. 5, Fig. 5A, Fig. 5B show three further embodiments of foils, each in cross section, [0027] Fig. 6, Fig. 6A, Fig. 6B show three further embodiments of foils, each in cross section, [0028] Fig. 7 is a cross-section taken through a further embodiment of a foil, [0029] Fig. 8, Fig. 8A, Fig. 8B, Fig. 8C show a supporting element in the form of a wire board, in plan view and in sections according to the line VIIIA-VIIIA
in Fig. 8, each on an enlarged scale, [0030] Fig. 9 shows a detail of the wire system according to Fig. 1 und Fig.
1A, on an enlarged scale, and [0031] Fig. 10, Fig. 10A shows a further embodiment of a foil, in plan view and in side view and on an enlarged scale.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Referring now to the figures of the drawing in detail and first, particularly, to Figs. 1 and 1A thereof, there is shown a wire system in a papermaking installation with an intrinsically closed wire 1 with an upper run 11 and a lower run 12, which is guided over a plurality of guided drums or deflection drums 13 and which is moved in the direction of the arrows A. At the start of the upper run 11 of the wire 1, a device 14 is provided by means of which paper stock is sprayed onto the upper run 11 of the wire 1 over the width of the latter. The upper run 11 of the wire 1 is guided over a plurality of differently constructed suction boxes 2, which are formed with foils or wire boards and which are used to extract the water in the paper stock or to wipe off the water on the underside of the wire 1 and to support the wire 1.

[0033] In the further course of the movement of the wire 1, the latter is assigned a second intrinsically closed wire la located above it, which is guided over deflection drums 13a and which is assigned a suction box 2a likewise formed with foils. In that area in which the lower, first wire 1 is assigned the upper, second wire la, the paper stock applied to the wire 1 is located between the two wires 1 and la, and the water in the paper stock is extracted through the suction boxes 2 and 2a assigned to said wires.

[0034] At the end of the upper run 11, the strip of paper 15 located on the wire 1 is detached from the latter and, if appropriate, processed further in a felt system.

[0035] The construction of the supporting elements, in particular the foils and the wire boards, is explained below:

[0036] Fig. 2 and Fig. 2A illustrate a foil 3 which has a supporting bar 31 which, on its underside, is formed with an undercut groove 30, by means of which, in a wire system according to Fig. 1 and Fig. 1A, it can be pushed onto a supporting bar fixed to the frame such that the foil 3 extends at right angles to the direction of movement A of the wire 1.

[0037] On the side facing the wire 1, the foil 3 is formed with a metallic carrier layer 32 for a wear protection layer 33, with which the wire 2 comes into contact.
On the side facing away from the wear protection layer 33, the metallic carrier layer 32 is formed with bolts 34 which are welded or screwed to the carrier layer 32, project into recesses 35 which are provided in the supporting bar 31 and which are anchored in the recesses 35 by means of a plastic compound 36 containing glass fibers.

[0038] The carrier layer 32 is composed of a corrosion- and acid-resistant stainless steel alloy. The wear protection layer 33 is composed of a hard metallic alloy, in which hard materials are embedded. The wear protection layer 33 is joined to the metallic carrier layer 32 by being sintered on.

[0039] As can be seen from Fig. 2A, the metallic carrier layer 32 on which the wear protection layer 33 is located extends over part of the length of the foil 3, at least one further metallic carrier layer 32 having a wear protection layer 33 adjoining said foil 3 and, furthermore, the carrier layers 32 lying on one another being joined to each other by means of a welding strip 37. By means of this welding strip 37, the two carrier layers 32 are drawn so firmly against each other that the wear protection layers 33 arranged on the latter adjoin one another virtually without any joint.

[0040] The embodiment of a foil 3 shown in Fig. 3 and Fig. 3A has virtually the same construction as the foil 3 shown in Fig. 2 and Fig. 2A. These two foils 3 differ from each other only in the fact that the two carrier layers 32 abutting each other are not welded directly to each other, but that a joining plate 38 covering the abutting surfaces is provided, which is joined to the two carrier layers 32 in each case by means of a welding strip 37. By means of these two welding strips 37, the two wear protection layers 33 are also drawn against each other such that they merge into each other virtually without any joint.

[0041] The foils 3 shown in Fig. 4, Fig. 4A, Fig. 4B, Fig. 4C, Fig. 4D and Fig. 4E
have all the supporting bars 31, on which carrier layers 32 which are provided with wear layers 33 are fixed, the wear protection layers 33 being composed of hard metallic alloys in which hard materials are embedded, and the wear protection layers 33 being joined metallurgically to the carrier layers 32 by being sintered on.

[0042] The foils 3 according to Fig. 4 to Fig. 4E differ from the foils 3 according to Fig. 2, Fig. 2A and Fig. 3, Fig. 3A only by way of different formations of the supporting bars 31, by means of which they are fixed to supporting bars fixed to the frame, and by way of different types of fixing the carrier layers 32 to the supporting bars 31.

[0043] In the foil according to Fig. 4, the fixing bolts 34a are formed on their circumferential surfaces with annular recesses, into which the plastic material 36 located in the recesses 35 penetrates, which reinforces the fixing of the bolts 34a.

[0044] In the foil 3 according to Fig. 4A, the supporting bar 31 is formed with a rib 30a, which has lateral undercuts and with which it can be pushed into a groove of complementary cross section aligned transversely with respect to the wire in a supporting frame and can be clamped in this groove.

[0045] In the foil 3 according to Fig. 4B, the supporting strip 31 is formed with a triangular cross section.

[0046] In the foil 3 according to Fig. 4C, the carrier layer 32 is formed with an undercut groove 32a on the side facing away from the wear layer 33, the supporting bar 31 is formed with a rib 31 approximately complementary in cross section to the groove 32a, and an adhesive material 39 is introduced into the interspace.

[0047] In the foil 3 according to Fig. 4D, the carrier layer 32 is provided on the side facing away from the wear protection layer 33 with two undercut grooves 32a, which are assigned two ribs 31a of complementary cross section projecting from the supporting bar 31.

[0048] In the foil 3 according to Fig. 4E, the carrier layer 32 is provided on the side facing away from the wear protection layer 33 with a projecting rib 32b which has lateral undercuts, and the supporting bar 31 is formed with an undercut groove 31b.

[0049] In the foils according to Fig. 4C, Fig. 4D and Fig. 4E, in each case adhesive materials 39 are introduced between the undercut ribs 31a, 32b and the undercut grooves 31b, 32a.

[0050] In the foil 3 according to Fig. 5, bolts 34b provided with a thread are welded onto the carrier layer 32 and pass through drilled holes 40 located in the supporting bar 31, and nuts 40a are screwed onto the bolts 34b.

[0051] In the foil 3 according to Fig. 5A, the carrier layer 32 is formed with threaded holes 41 and the supporting bar 31 is formed with drilled holes 42, through which machine screws 43 pass and are screwed into the threaded holes 41, by which means the carrier layer 32 is fixed to the supporting bar 31.

[0052] The foil 3 according to Fig. 5B is formed with a width enlarged substantially as compared with the foil 3 according to Fig. 5, it being formed over its width with a plurality of bolts 34b welded to the carrier layer 32, which pass through drilled holes 40 provided in the supporting bar 31 and are screwed by means of nuts 40a.

[0053] In the foil according to Fig. 6, the metallic carrier layer 32 is fixed to the supporting bar 31 by means of lateral welding strips 44.

[0054] In the foil 3 according to Fig. 6A, the supporting bar 31 is formed with drilled holes 40, within which there are annular welding strips 44a, by means of which the carrier layer 32 is fixed to the supporting bar 31.

[0055] The foil 3 according to Fig. 6B differs from the foil 3 according to Fig. 6A
in that it has a substantially greater width and in that the supporting bar 31 is formed over its width with two drilled holes 40, in which there are annular welding strips 44a. In addition, the supporting bar 31 is formed with a trapezoidal cross section wherein it can be pushed into a groove formed with a complementary cross section in a supporting bar of the supporting frame and locked in this groove.

[0056] The foil 3 according to Fig. 7 differs from all the foils illustrated and explained above in the fact that the carrier layer 32 for the wear protection layer 33 is used only for direct fixing to a supporting frame of the wire system. For this purpose, the carrier layer 32 is formed with an undercut groove 32a, by means of which it can be pushed onto a supporting bar of complementary cross section fixed to the frame and belonging to a supporting frame and can be fixed to the latter.

[0057] The supporting element 3a according to Fig. 8 and Fig. 8A, which is formed as a wire board, is formed by a metallic carrier layer 32 which, on its side facing the wire or felt, is provided with a wear protection layer 33, which is composed of a hard metallic alloy with embedded hard materials, the carrier layer 32 and the wear protection layer 33 being formed with a large number of drilled holes 45. Welded to the carrier layer 32a on the side facing away from the wear protection layer 33 are bolts 34b provided with a screw thread, which pass through drilled holes 51 located in a support 50 fixed to the frame. Here, the fixing of this wire board 3a to the support 50 fixed to the frame is carried out by means of nuts 40a screwed onto the bolts 34b. The direction of movement of the wire is indicated by the arrow A.

[0058] In the supporting element 3a according to Fig. 8B, which is likewise formed as a wire board having a multiplicity of drilled holes 45, the carrier layer 32 is joined to a support 50 fixed to the frame by means of welding strips 44.

[0059] In the supporting element 3a according to Fig. 8C, which is likewise formed as a wire board having a multiplicity of drilled holes 45, the metallic carrier layer 32 is formed with threaded holes 41 for fixing to a support 50, fixed to the frame, by means of threaded screws.

[0060] On account of the formation of the supporting element as a metallic carrier board 32, on which a wear protection layer 33 of a hard metallic alloy with embedded hard materials is located, said carrier board 32 is sufficiently elastic that it can be curved in the direction of movement of the wire, as is illustrated in Fig. 8B
and Fig. 80.

[0061] By using Fig. 9, firstly two suction boxes 21 and 22 which are assigned to the upper run 11 of the first wire 1 and over which the upper run 11 of the wire 1 is guided and supported, and, secondly, the suction box 2a assigned to the second wire la are explained in more detail. The suction box 21 is formed with a plurality of foils 3 aligned transversely with respect to the direction of movement of the wire 1, over which plurality of foils 3 the wire 1 is guided and is supported thereby.
Likewise, the suction box 2a assigned to the second wire la is formed on its underside with a plurality of foils 3, over which the second wire la is guided and is supported thereby. The last foils 3 of the upper suction box 2a in the direction of movement A of the two wires 1 and 1a are arranged and formed in such a way that the two wires 1 and la are guided on a slightly curved movement path. As a result of a movement path curved in this way, an improvement in the suction action and in the quality of the strip of paper is achieved. In order to divert into a horizontal movement path again in the course of this movement path, the second suction box 22 is formed on its side facing the wire 1 with a wire board 3a which, according to Fig. 8B and Fig. 80, has a curved surface.

[0062] A wire board having a curved surface with a wear protection layer of a hard metallic alloy in which hard materials are embedded, and which is sintered onto a supporting layer of a stainless steel metal, can be manufactured substantially more easily than is true of wear protection layers which are manufactured from a ceramic material.

[0063] The supporting element 3b illustrated in Fig. 10 and Fig. 10A
comprises a supporting frame 6 which, on the side facing the wire or felt, is formed with a plurality of foils 61 which are aligned transversely with respect to the direction of movement A of the wire or felt and which each comprise a carrier layer 32 of a stainless steel alloy and a wear protection layer 33 of a hard metallic alloy with embedded hard materials sintered onto said carrier layer.

[0064] In all the exemplary embodiments explained above, the carrier layer 32 is preferably composed of a corrosion- and acid-resistant stainless steel alloy, preferably having a material quality WS 1.4571 (AISI 316 Ti) or WS 1.4404 (AISI
316L), and the wear protection layer 33 is composed of a hard metallic alloy in which hard materials are embedded, the wear protection layer 33 being joined metallurgically to the carrier layer 32 by being sintered on.

[0065] The hard metallic alloy 33 can be composed of a nickel-based hard alloy or can contain a nickel-based hard alloy. Furthermore, the hard metallic alloy can be composed of a mixture comprising an iron-based hard alloy and a nickel-based hard alloy, of a nickel-molybdenum-based hard alloy, and of a mixture of an iron-based hard alloy and a nickel-molybdenum hard alloy.

[0066] The wear protection layer can have a thickness of 1.5 mm to 10 mm.
The wear protection layer is joined to the metallic carrier layer by means of sintering under vacuum or under a protective atmosphere.

[0067] The hard materials located in the hard metal alloy can be formed by chromium carbides, tungsten carbides, silicon carbides and boron carbides, on their own or in any desired mixtures. The hard materials in the hard metal alloy can make up 50% by weight to 90% by weight.

[0068] The hard metal alloy can contain characteristic hard materials with hardnesses of 600 HV0.3 to 900 HV0.3 or special hard materials with hardnesses of 1200 HV0.3 to 1900 HVO 3.

[0069] Since wear protection layers according to the invention have relatively high thicknesses, the supporting elements exhibit long service lives.
Furthermore, as a result of sintering the wear protection layer onto the metallic carrier material, optimal joining of the wear protection layer to the metallic carrier layer is effected.

[0070] The sintering of the wear protection layer 33 onto the carrier layer 32 is carried out at a temperature from 870 C to 1300 C. In this regard, it is pointed out that the melting point of a corrosion- and acid-resistant stainless steel alloy with a material quality of 1.4571 (AISI 316 Ti) or 1.4404 (AISI 316L) lies at around 1400 C.

Claims (11)

1. In a papermaking installation equipped with at least one wire and at least one felt to be moved over supporting elements, a supporting element to be fixed to a supporting frame of the papermaking installation, directly or by way of a carrier element, the supporting element comprising:
a composite element formed with wear protection in a region thereof in which the supporting element comes into contact with the wire or the felt;
said composite element including a layer of a metallic carrier material and a hard metal layer sintered onto said metallic carrier layer, said hard metal layer being formed of a hard metal alloy having hard materials embedded therein.

2. The supporting element according to claim 1, configured to form a foil or a supporting board.

3. The supporting element according to claim 1, wherein said carrier layer is composed of a corrosion-resistant and acid-resistant stainless steel alloy.

4. The supporting element according to claim 1, wherein said stainless steel alloy is an austenitic steel having a material quality AISI 316 Ti (WS 1. 4571) or AISI
316L (WS 1.4404).

5. The supporting element according to claim 1, wherein said hard metal layer consists of a nickel-based hard alloy.

6. The supporting element according to claim 1, wherein said hard metal layer contains a nickel-based hard alloy.

7. The supporting element according to claim 1, wherein said hard metal layer is a hard metallic alloy composed of a mixture of an iron-based hard alloy and a nickel-based hard alloy.

8. The supporting element according to claim 1, wherein said hard metal layer is a hard metallic alloy composed of a nickel-molybdenum-based hard alloy.

9. The supporting element according to claim 1, wherein said hard metal layer is a hard metallic alloy composed of a mixture of an iron-based hard alloy and a nickel-molybdenum hard alloy.

10. The supporting element according to claim 1, wherein said hard materials are selected from the group consisting of chromium carbides, tungsten carbides, silicon carbides, boron carbides, and mixtures thereof.

11. The supporting element according to claim 1, wherein said hard materials in said basic hard alloy make up between 50% by weight and 90% by weight.