Sieve basket for a sieving device

Abstract

Sieve basket (3) for a sieve device (1), in particular for fiber preparation, with sieve bars (5) arranged between end rings (7) and with at least one bar holder (8), wherein the at least one bar holder (8) extends over an axial area with respect to the sieve basket axis (13).

Description

[0001] The invention relates to a sieve basket for a cylindrical sieving device. The sieve basket has a plurality of profiled bars arranged at intervals from one another. The profiled bars are arranged between end rings. At least one bar holder is provided for holding the sieve bars. The sieve basket is particularly intended for use in a sieving device for cleaning / sorting fibrous suspensions.

[0002] The invention relates to a sieve basket for a sieving device and a method for manufacturing the sieve basket.

[0003] A well-known example of the use of cylindrical sieve devices that can be manufactured using this method is the sorting of fibrous suspensions, as is done in pressure sorters in the paper manufacturing industry.

[0004] The fibers contained in the suspension should pass through the sieve, while the unwanted solid components are rejected at the gap and directed out of the sieve device.

[0005] Because the openings have an elongated shape, i.e., they are slits or crevices, fibrous particles pass through more easily than cubic particles, even if both types are of a similar size. Therefore, this sorting technology allows for a very good separation of non-fibrous contaminants from fibrous suspensions.

[0006] It is also conceivable to use it for separating different fiber components, a process known as fiber fractionation. However, this requires a high degree of precision in the slot shape across the entire sieve surface.

[0007] A possible method for manufacturing such sieve baskets is shown in DE 10 2006 007 660 A1, in which the profile bars are clamped by plastically deforming the C-shaped retaining rings, which are provided with recesses for the bars. This method is used for sieve baskets where the bars are inserted at the inner edge of the retaining rings. Such an arrangement of the bars is chosen when the suspension is to pass through the slots from the inside out (centrifugal operation). To deform the retaining rings, bending forces are applied from the outside, with the butt ends on the inside being supported by backup rollers.

[0008] An alternative method for manufacturing such sieve baskets is disclosed in DE 44 35 538 A1. This method is used for sieve baskets in which the bars are inserted at the outer edge of the retaining rings. Such an arrangement of the bars is chosen when the suspension is to pass through the slots from the outside inwards (centripetal operation).

[0009] To keep the screen basket free of blockages, a rotor, often called a scraper, is frequently used. This rotor moves past the screen basket's surface at a closer distance, generating hydraulic impulses. Screen baskets for use in screening devices must therefore be manufactured with high precision and withstand high loads.

[0010] The purpose of the invention is to increase the stability of sieve baskets.

[0011] In particular, the object of the invention is to create a sieve basket with sieve bars which has increased stability with regard to the axial forces and / or torsional forces acting on the sieve basket.

[0012] Furthermore, the invention was based on the objective of providing a method for manufacturing sieve baskets with increased stability, particularly with regard to acting axial forces and / or torsional forces.

[0013] According to the invention, the object of the invention is achieved by providing at least one axially extending rod holder. Axial extension here refers to the extension of the rod holder beyond its mere thickness in the axial direction. This axial extension of the at least one rod holder allows it to better absorb axial forces, particularly by converting them into elastic deformation. This increases the stability and robustness of the sieve basket. Furthermore, torsional forces acting on the sieve rods can be better absorbed and / or compensated by the at least one axially extending rod holder.

[0014] In a preferred embodiment, all rod holders are designed with an axial extension.

[0015] In one embodiment, the at least one rod holder is designed as a ring. The ring shape contributes to the stability of the sieve basket, which has a beneficial effect on the service life of the sieve basket.

[0016] In a preferred embodiment, the at least one rod holder has a wave-like and / or serrated shape. This allows axial forces and / or torsional forces acting on the rod holder to be absorbed and compensated by elastic deformation. These elastic deformations are so small that the slot width remains virtually unchanged.

[0017] In one embodiment, several rod holders extending over an axial range are provided. In particular, all rod holders of the sieve basket extend over an axial range. This allows axial and / or torsional forces to be absorbed particularly evenly. This has a positive effect on the robustness of the sieve basket.

[0018] In one embodiment, at least two adjacent rod holders are arranged to have a maximum axial distance from each other at least at one position in the circumferential direction. This creates areas for high flow rates, which has a positive effect on the efficiency of the screen basket.

[0019] It has been found that at the position of maximum spacing of the rod holders, the distance is a maximum of 45 mm, preferably a maximum of 40 mm. This ensures sufficient stability.

[0020] In one embodiment, at least two adjacent rod holders are arranged to have a minimum axial distance from each other at least at one position in the circumferential direction, whereby the minimum distance between the adjacent rod holders is exceeded at at least one position. This minimum distance ensures a flow of fiber suspension even in this area, contributing to high efficiency and preventing malfunctions caused by clogging of the sieve basket. A distance of 1 mm to 5 mm has proven particularly suitable as a minimum distance.

[0021] In some applications where the risk of clogging is lower due to the nature of the suspension, it has proven advantageous for the adjacent rod holders to touch or even be firmly connected to each other. This increases the stability of the sieve basket.

[0022] For particularly efficient absorption of axial and / or torsional forces, it has proven advantageous for the minimum and maximum spacing positions of the adjacent rod holders to repeat periodically. The minimum and maximum distances specified in the circumferential direction do not need to be identical. The only important factor is that the predetermined limits are adhered to.

[0023] The axial extent of the individual rod holders can also vary. Furthermore, the rod holders can have different wave shapes and / or tooth profiles.

[0024] Providing rod holders with an identical shape can have a beneficial effect on the manufacturing process and thus reduce manufacturing costs.

[0025] In a preferred embodiment, the rod holders are arranged in opposite directions with a wave-shaped and / or serrated form.

[0026] The method for manufacturing a sieve basket according to one of the preceding claims has proven to be advantageous, in which the following process steps are provided: - Transformation of flat bar holders into bar holders with axial extension - After forming, recesses for receiving sieve bars are formed in the respective bar holders, - Equipping the rod holders required for the sieve basket with sieve rods - Connecting the sieve bars to the bar holders - Assembly of the end rings. The end rings can be mounted by screwing them together or by a permanent connection, such as welding.

[0027] By forming recesses for receiving sieve bars, these recesses can be aligned so that the insertion of the sieve bars is still guaranteed.

[0028] The invention will now be explained in more detail using an exemplary embodiment. The accompanying drawing shows: Fig. 1: a schematic view of a cylindrical sieve basket; Fig. 2: Enlarged view of a section of the sieve basket; Fig. 3: Schematic representation of a sieve device; Fig. 4: Manufacturing process axial extension of the rod holder 8; Fig. 5: Manufacturing process of the recesses for receiving sieve rods.

[0029] In Fig. Figure 3 schematically depicts a screening device 1, also referred to as a pressure sorter, with a cylindrical screen basket 3. The screen basket 3 has a vertical screening axis 13. Within the screening device 1, the screen basket 3 separates an inlet chamber 15 from a material chamber 17. Here, the inlet chamber 15 is located radially inside the screen basket 3, and the material chamber 17 is located radially outside. The screen basket 3 has adjacent screen bars 5 to form a screening surface 9. If the inlet chamber were located radially outside the screen basket 3, the material chamber would be located radially inside the screen basket.

[0030] The medium to be treated, i.e. the fiber suspension 19, is fed into the inlet chamber 15 via a suspension inlet 16.

[0031] In the sieve device 1 used here, the fiber suspension 19 receives an angular momentum that sets the fiber suspension 19 into circumferential motion. In addition, a transport flow is generated as a result of the pressure gradient between the suspension inlet 16 shown above and a reject outlet 20 located below in the inlet chamber 16.

[0032] During this transport flow, a large part of the fibrous suspension 19 is directed as intended through the sieve surface 9 of the sieve basket 3 into the material chamber 17 and from there discharged via the material outlet 18.

[0033] The portion of the fiber suspension 19 rejected by the sieve basket 3 is conveyed as reject via the reject outlet 20 from the inlet chamber 15.

[0034] To prevent the sieve openings from becoming clogged, a rotor 11, also known as a sieve sweeper, is used. The rotor 11 moves relative to the sieve surface 9. The rotor 11 may be equipped with attached rotor blades. The rotor 11 has the shape of a cylindrical drum, with its axis of rotation coinciding with the sieve axis 13.

[0035] The cylindrical sieve basket 3 consists according to Fig. 4 and Fig. 5. The sieve basket consists of a plurality of sieve bars running parallel to the cylinder axis 13. The sieve bars are held by several axially spaced bar holders 8. The sieve basket is provided with end rings 7 on both sides at the end.

[0036] The sieve openings of the sieve basket 3 are sorting slots 6. The sorting slots 6 are formed by adjacent sieve bars 5. Fig. 1 - 2. The sorting slots 6 are approached either clockwise or counterclockwise, depending on the flow direction of the suspension.

[0037] At the in Fig. In the example shown, the fibrous suspension 19 flows essentially centrifugally along the radials, i.e. from the inside out through the sorting slots 6 of the sieve basket 3. Accordingly, the profile bars 5 are supported on the inside of the bar holders 8.

[0038] In a centripetal flow through the sieve basket, the profile bars are arranged and held on the radial outside of the retaining elements, not shown.

[0039] For consistent sorting quality, the slot width between the profile bars 5 is the same and constant in the axial direction.

[0040] Based on Fig. 4 and Fig. 5. The production of the rod holders 8 will be carried out according to Fig. 1 and Fig. 2 described in more detail. The rod holders 8 are manufactured as ring segments or as one-piece rings 81. The rings 81 or ring segments are formed into a corrugated shape, e.g. by a rolling device or by die forming. The rings 81 are formed with open-edged recesses, for example by laser cutting, as in Fig. Figure 5 shows the rings designed to accommodate sieve bars 5. The subsequent position of the respective bar holder 8 can already be taken into account. The bar holders 8 are arranged in a predetermined configuration relative to each other with respect to the shaft contour. The sieve bars 5 can be inserted into the rings from an axial and / or radial direction. The sieve bars 5 are firmly connected to the bar holders 8. For example, a permanent connection between the sieve bars 5 and the bar holders 8 can be achieved by clamping / pressing. End rings 7 are provided at the ends of the sieve basket.

[0041] In the Fig. 1 and Fig. In the embodiment shown in Figure 2, the rod holders 8 are designed with a corrugated shape. Due to the axial extension of the rod holders 8, forces in the axial direction can be absorbed more effectively. The corrugated shape also allows the rod holders 8 to better absorb torsional forces. These absorbed forces can be compensated by elastic deformation.

[0042] In the illustrated embodiment, the rod holders 8 are arranged in opposite directions. This results in alternating positions with minimum distances 83 and maximum distances 85 of the rod holders 8 in the circumferential direction. Reference symbol list 1 sieve device, pressure sorter 3 sieve basket 5 sieve rods 6 sorting slots 7 End ring 8 rod holders 9 sieve area 11 Rotor, scraper 13 Siebachse 15 Inlet area 16 Suspension inlet 17 Goods room 18 Good material discharge 19 Fiber suspension 20 Reject outlet 81 rings 83 Minimum distances 85 Maximum distances 87 Circumferential direction 89 Axial height of the sieve basket surface QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2006 007 660 A1

[0007] DE 44 35 538 A1

[0008]

Claims

[1] Screen basket (3) for a screen device (1), in particular for fiber preparation, with screen bars (5) arranged between end rings (7) and with at least one bar holder (8), characterized by , that the at least one rod holder (8) extends over an axial area with respect to the sieve basket axis (13). [2] Sieve basket (3) according to claim 1 characterized by , that the at least one rod holder (8) is designed as a ring and surrounds the axial axis of the sieve basket (13). [3] Sieve basket according to claim 1 or 2, characterized by , that the at least one rod holder (8) has a serrated and / or a wavy shape in the circumferential direction. [4] Sieve basket according to any one of the preceding claims, characterized by , that several rod holders (8) extending over an axial area are provided. [5] Sieve basket (3) according to claim 4, characterized by, that at least two adjacent rod holders have a maximum axial distance (85) from each other at least at one position in the circumferential direction (87), wherein the maximum distance (85) of the adjacent rod holders (8) is less than the maximum distance (85) of the adjacent rod holders (8) at at least one position. [6] Sieve basket according to claim 5, characterized by , that at the position of the maximum distance (85) of the rod holders (8) the distance is a maximum of 45mm, preferably a maximum of 40mm. [7] Sieve basket according to any one of the preceding claims 4 to 6, characterized by , that at least two adjacent rod holders (8) have a minimum axial distance (83) from each other at least at one position in the circumferential direction (87), wherein the minimum distance (83) of the adjacent rod holders is exceeded at at least one position. [8] Sieve basket according to claim 7, characterized by, that at the position of the minimum distance (83) of the rod holder the distance is minimal from 1mm to 5mm. [9] Sieve basket according to any one of the preceding claims 1 to 7, characterized in that adjacent rod holders touch each other at points or are connected to each other. [10] Sieve basket according to any one of the preceding claims 4 to 9, characterized by , that the positions of minimum distance (83) and maximum distance (85) of the adjacent rod holders (8) repeat periodically. [11] Sieve basket according to any one of the preceding claims 3 to 10, characterized by , that the rod holders (8) are arranged with their wavy or jagged shape offset from each other, in particular in opposite directions. [12] Method for producing a sieve basket according to any of the preceding claims comprising the process steps: - Step 1: Transformation of flat bar holders into bar holders with axial extension - Step 2: After the forming process, recesses are formed in the respective rod holders to accommodate sieve rods, - Step 3. Equipping the rod holders required for the sieve basket with sieve rods - Step 4: Connecting the sieve rods to the rod holders - Step 5: Mounting the end rings, whereby steps 1 and 2 can also be performed in reverse order. [13] Method according to claim 12, characterized by that the rod holders are positioned relative to each other before being fitted with sieve rods. [14] Sieving device (1) for fiber preparation with a sieve basket (3) according to one of claims 1 to 11.

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