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DE-102024133229-A1 - Cutting sieve with evenly distributed cutting surfaces

DE102024133229A1DE 102024133229 A1DE102024133229 A1DE 102024133229A1DE-102024133229-A1

Abstract

The invention relates to a cutting screen (1) for use in wet shredders (2) with an inner edge region (4) and an outer edge region (6), wherein the cutting screen (1) has a working area (8) between the inner and outer edge regions (4, 6) consisting of empty sections (10) and material sections (12), wherein the working area (8) is designed to be swept by at least one cutting edge (11) during operation, characterized by a circumferential ratio (UV) that is the ratio of accumulated lengths of material sections A M (12) along a circumferential line to a circumference (U) belonging to the circumferential line, and wherein at least one continuous, curvature-free circumferential function F exists for the cutting screen (1) that maps circumferences U to a reference circumferential ratio RUV, wherein the circumferential ratio (UV) is determined for each circumference U of a working area (8) of the cutting screen (1) that is concentric with and within the circle lying in the work area (8) does not deviate from the reference circumference ratio RUV = F(U) by more than 0.05, preferably 0.03, preferably 0.01 of the reference circumference ratio (RUV) at the respective circumference.

Inventors

  • PETER HARTOGH
  • Hugo Vogelsang

Assignees

  • VOGELSANG GMBH & CO. KG

Dates

Publication Date
20260513
Application Date
20241113

Claims (20)

  1. Cutting screen (1) for use in wet shredders (2) with an inner edge region (4) and an outer edge region (6), wherein the cutting screen (1) has a working area (8) between the inner and the outer edge regions (4, 6) consisting of empty sections (10) and material sections (12), wherein the working area (8) is designed to be swept by at least one cutting edge (11) during operation, characterized in that a circumferential ratio (UV) is the ratio of accumulated lengths of material sections A M (12) along a circumferential line to a circumference (U) belonging to the circumferential line. U V = ∑ U A M U and wherein for the cutting screen (1) there exists at least one continuous, curvature-free circumferential function F which maps perimeters U to a reference circumferential ratio RUV: F : U → R U V wherein the circumferential ratio (UV) for each circumference U of a circle concentric to the working area (8) of the cutting screen (1) and lying within the working area (8) does not deviate from the reference circumferential ratio RUV = F(U) by more than 0.05, preferably 0.03, preferably 0.01 of the reference circumferential ratio (RUV) at the respective circumference.
  2. Cutting sieve (1) according Claim 1 , wherein a radial ratio (RV) is the ratio of all accumulated lengths of material sections ( AM ) (12) along a radial cutting line L to the length of the cutting line L, wherein the cutting line L forms an angle φ ∈ [0°, 360°] with a radial horizontal cutting line, wherein the cutting line extends over the working area (8) without protruding into the inner edge area (4) and/or the outer edge area (6), R V = ∑ L A M L where for the cutting sieve (1) there exists at least one continuous, curvature-free angular function G that maps circular angles φ to a reference radial ratio RRV: G : φ → R R V and wherein the radial ratio (RV) for each radial section line with a circular angle φ ∈ [0°, 360°] does not deviate from the reference radial ratio RRV = G(φ) by more than 0.15, preferably 0.1.
  3. Cutting screen (1) according to one of the preceding claims, wherein the function (F) is convex, linear or constant.
  4. Cutting screen (1) according to one of the preceding claims, wherein the working area (8) comprises an area of at least 30%, preferably 40%, 50%, 60%, 70%, 80% of a front surface of the cutting screen (1) and of at most 95%, preferably 90%, 85%, 80%, 70% of the front surface of the cutting screen (1).
  5. Cutting sieve (1) according to one of the preceding claims or the preamble of Claim 1 , the inner edge region having a central recess (16) for receiving a rotating element, wherein the material sections (12) are formed by a first plurality of first material webs (36) extending spirally from the inside to the outside; and a second plurality of second material webs (38) extending in a curved, preferably spiral, direction opposite to the first material webs (36) from the inside to the outside, wherein the first material webs (36), the second material webs (38), the inner edge region (4, 6) and the outer edge region (6) enclose material-free empty sections.
  6. Cutting sieve (1) according Claim 5 , wherein the first material webs extend in an involute shape, preferably in a circular involute shape.
  7. Cutting sieve (1) according Claim 5 or 6 , wherein the second material webs (38) cross the first material webs (36).
  8. Cutting sieve (1) according to one of the Claims 5 until 7 , wherein the second material webs (38) do not taper radially outwards or inwards.
  9. Cutting sieve (1) according to one of the Claims 5 until 7 , wherein the second material webs (38) taper radially outwards.
  10. Cutting sieve (1) according to one of the Claims 5 until 7 , wherein the first material webs (36) taper radially inwards.
  11. Cutting sieve (1) according to one of the Claims 5 until 10 , wherein the second material webs (38) run continuously from the inner edge region (4) to the outer edge region (6).
  12. Cutting sieve (1) according to one of the Claims 5 until 11 , wherein the cutting sieve (1) is designed is, when interacting with the cutting edge (11) cutting angle in a range of 10° to 30°, preferably in a range of 15° to 25°, preferably of 20°.
  13. Cutting sieve (1) according Claim 12 , wherein each cutting angle is in a range of 10° to 30°, preferably from 15° to 25°, preferably at 20°.
  14. Cutting sieve (1) according to one of the preceding claims, wherein the ball passage diameters of the empty sections (10) are in a range from a lower limit of 5 mm, preferably 10 mm, 15 mm, 20 mm, 25 mm to an upper limit of 25 mm, preferably 30 mm, 35 mm, 40 mm.
  15. Cutting sieve (1) according to one of the preceding claims, characterized in that the cutting sieve (1) has a higher hardness on the surface of the first and second material webs (36, 38) than in the interior of the first and second material webs (36, 38).
  16. Cutting screen (1) according to one of the preceding claims, wherein the outer edge region (6) has bores (32) for positioning and/or fixing the cutting screen (1) in a wet shredder (2).
  17. System (3) for comminuting solids in mixed fluids, comprising a cutting screen (1) according to one of the preceding claims and at least one cutting knife (14).
  18. System (3) according to Claim 17 , wherein the working area (8) of the cutting screen (1) is swept over by the at least one cutting knife (14) when the at least one cutting knife (14) rotates and is at least partially in contact with the at least one cutting knife (14).
  19. System (3) according to one of the Claims 17 and 18 , wherein the axis of rotation of the at least one cutting blade (14) is coaxial to a central axis of the working area (8).
  20. System (3) according to one of the Claims 17 until 19 , wherein the axis of rotation of the at least one cutting knife (14) is coaxial to a central axis of the cutting screen (1).

Description

The present invention relates to a cutting screen for use in wet shredders. The invention further relates to a wet shredder for shredding solids, wherein the wet shredder comprises a cutting screen. Liquid or sludge-like media, sometimes containing solids, especially fibrous and/or fiber-containing solids, are processed in various industries, including food processing, pulp and paper production, and the operation of biogas or wastewater treatment plants. During the transport and/or processing of such media containing solids, a wide variety of plant components are used: pipelines, pumps, restrictors, etc. To prevent damage or blockage of these components, the media containing solids should not contain large solids or long fibers. Otherwise, downstream pumps can become blocked and/or pipes can be damaged, resulting in costly maintenance and/or plant downtime. Wet shredders, also called macerators, and heavy solids separators are therefore frequently used at the beginning of the material flow through the plant. Heavy solids separators remove heavy solids (e.g., stones). Light solids, such as wood chips, bones, hair, fibers, or food scraps, are shredded in the wet shredder. Various principles of wet shredders are known, e.g., twin-shaft shredders. The present application proposes a cutting screen for a wet shredder in which the shredding is carried out by a circular cutting screen arranged within the wet shredder, which is swept by at least one cutting blade rotating relative to the screen. The cutting screen has openings of specific sizes. Solids are shredded between the cutting screen and the at least one cutting blade by shear forces until they are small enough to pass through the openings of the circular cutting screen. The applicant markets generic shredding devices under the brand name RotaCut. In the WO 2012/032175 A1 The construction of such a comminution device is described. An adjustment mechanism moves a second cutting element (cutting knife), which is movable relative to a first cutting element (cutting screen), in such a way that, in the event of wear on the cutting edges of the first cutting elements, the second cutting element remains in permanent contact with the first. This is ensured in particular by the use of a hydraulic cylinder. Preferably, the first cutting element is a cutting screen with a plurality of openings, the boundary edges of which form cutting edges. The design of a cutting screen geometry presents several challenges. Depending on the intended application, the sphere size must be appropriately selected to ensure that the shredded solids and fibers are sufficiently small for further processing. Simultaneously, the sphere size must not be too small to guarantee a specific throughput. Materials resistant to chemicals processed during operation may be required. To maximize replacement intervals, the geometry should exhibit minimal wear during operation. The applicant offers cutting screens with various geometries, allowing the selection of the most suitable option for each specific application. To further increase efficiency, maximize maintenance intervals, and achieve a sustainable, durable product design, there is a need to further optimize the material and geometric properties of cutting screens for wet shredders. In particular, it has not yet been sufficiently considered that the shearing action of the cutting screen against the cutting edge of a cutting knife, and the varying contact conditions of the cutting edge with the cutting screen, lead to locally uneven wear of the cutting knife along its edge. The cutting edge of the cutting knife wears unevenly. Consequently, the shearing action exerted by the cutting knife in combination with the cutting screen on solids also varies locally in the worn state. As a result, the shearing performance decreases and the throughput is reduced. The object of the invention is therefore to provide a cutting screen with improved wear properties, which leads to improved, more uniform wear of the cutting edges of cutting knives during operation. Furthermore, it is an object of the invention to provide a system for comminuting solids in mixed fluids, which, when using the cutting screen, allows for the extension of maintenance intervals for changing the cutting screens and/or cutting knives. The problem is solved by a cutting screen with the features of independent claim 1. Such a cutting screen has an inner edge region and an outer edge region, wherein the cutting screen has a working area between the inner and the outer edge region consisting of empty sections and material sections, wherein the working area is provided to be used in operation by a cutting The edge is to be swept over. A circumferential line of a circle within a working area intersects material sections AM and empty sections AL . A circumferential ratio UV is the ratio of accumulated lengths of material sections AM along a circumferential line to a circumference U belonging to t