Hammermühle

Abstract

Hammer mill (1) with a feeding device (4) for feeding a working chamber (5) inside the hammer mill (1) with a material to be ground, which is covered at one top by a ceiling grate (12) and to which a discharge chute (10) for pieces of the material to be ground is connected for ejecting pieces of the material to be ground from the working chamber (5) through the ceiling grate (12), wherein a rotor with a plurality of movable hammers is rotatably mounted in the working chamber (5) about a horizontal axis (7), which crush the material to be ground and convey it through the working chamber (5), and wherein the ceiling grate (12) is curved towards the discharge chute (10), characterized in that the curvature describes a circular arc (16) around an edge (14) of the working chamber (5).

Description

[0001] The invention relates to a hammer mill with a feeding device for feeding a working chamber inside the hammer mill with a material to be ground, which is covered at one top by a ceiling grate and to which a discharge chute for pieces of the material to be ground is connected for ejecting pieces of the material to be ground from the working chamber through the ceiling grate, wherein a rotor with a plurality of movable hammers is rotatably mounted in the working chamber about a horizontal axis, which crush the material to be ground and convey it through the working chamber, and wherein the ceiling grate is curved towards the discharge chute.

[0002] The curvature reduces the tendency for ejected pieces of the ground material to accumulate on the grate of the hammer mill according to the invention, compared to a flat grate. Furthermore, the invention improves the passage of the crushed material through the entire surface of the grate, because otherwise the passage rate is poor on the side facing away from the discharge chute, thus promoting deposits there. The convex surface of the grate faces the discharge chute, and the concave surface faces the working area.

[0003] Such a hammer mill is disclosed in JP 2017-154083 A. Similar hammer mills are known, for example, from DE 32 34 298 A1, DE196 093 47 A1 and from DE 198 357 96 A1 and are used in particular for the processing of large-format regrind consisting of a material mix, such as entire vehicle bodies or electronic scrap: The regrind is crushed in the hammer mill, and the resulting pieces of regrind are sorted into material-pure fractions in the further processing process.

[0004] The ceiling grid above the work area is usually made of manganese steel (also: Mangalloy or Hadfield steel) with a manganese content of around 13% and has edge lengths between 0.8 and 3 m and a thickness of 5 to 30 cm.

[0005] In the operation of conventional hammer mills, pieces of the material being ground, ejected through the grate, sometimes accumulate on top of it. This is particularly true for low-density materials (plastics, foam plastics, etc.) and for those areas of the grate where the pulverized particles impact or pass through it with relatively low kinetic energy and therefore do not reach the discharge chute. Metal pieces, in particular, are heated to white-hot temperatures by the mechanical stress of the hammer mill. If such hot metal pieces come into contact with textile or plastic deposits on the grate, a high fire hazard is created.

[0006] The well-known hammer mills partially counter this risk with extinguishing devices for fires that may break out there. Task

[0007] The invention is based on the objective of reducing the risk of fire caused by deposits on the ceiling grate and thus creating the possibility of shredding materials with a high plastic or fiber content or of electronic waste. Solution

[0008] Based on known hammer mills, the invention proposes that the curvature describes a circular arc around an edge of the working space. A component can then be pivotably mounted around this same edge in the working space such that it maintains a constant, minimal distance to the ceiling grid in every position. This edge is preferably the horizontal one facing a feeding device.

[0009] In particular, in a hammer mill according to the invention, a grate flap for the discharge chute can be pivotably mounted around the edge. Such a hammer mill according to the invention also allows – by closing the flap – operation without ejecting pieces of the ground material into the discharge chute.

[0010] Preferably, in a hammer mill according to the invention, the ceiling grate is inclined towards the horizontal on an underside facing away from the discharge chute, in particular by a chord running in a vertical section through two opposite endpoints of the ceiling grate towards the discharge chute. The upper surface of the ceiling grate in such a hammer mill is inclined towards the discharge chute at every point, so that ejected pieces of the ground material that penetrate the ceiling grate always fall into the discharge chute under the force of gravity. Such an inclination of the ceiling grate is known from DE 196 093 47 A1 and from DE 198 357 96 A1, albeit without curvature. Preferably, in such a hammer mill according to the invention, the ceiling grate is inclined at least 10°, preferably 20°, and more preferably 30° to the horizontal on its underside. With such an inclined ceiling grate, the permanent accumulation of ejected pieces of the ground material on the ceiling grate is practically prevented.

[0011] Preferably, in a hammer mill according to the invention, the ceiling grate has a honeycomb structure at least in sections. The honeycomb structure improves the elasticity and stability of the ceiling grate and results in a high density of the ground material.

[0012] Preferably, a hammer mill according to the invention has a receiving device for a flat grate between the rotor and the top grate. Depending on the application of the hammer mill according to the invention, the curved top grate can then be replaced by the flat grate.

[0013] Preferably, a hammer mill according to the invention has a bottom grate or a closed bottom plate (each preferably composed of several sections) that closes off the working space below the rotor. Depending on their size, pieces of the material being ground can also escape from the working space through the bottom grate below the rotor in a hammer mill according to the invention with a bottom grate.

[0014] Preferably, a hammer mill according to the invention has an exhaust air extraction device at the top of the discharge chute. Dusts and gases generated during the operation of such a hammer mill according to the invention can then be selectively discharged from the working area and treated separately.

[0015] According to the invention, a top section for such a hammer mill is further proposed, which supports the ceiling grate and is detachably connected to a lower section of the hammer mill only by means of screw, plug, and / or clamp connections (optionally with hydraulic assistance). A hammer mill with such a top section according to the invention simplifies both access to the working area and the replacement of damaged or worn components such as the rotor or ceiling grate, as well as the optional use of different top sections – for example, with or without a grate flap, ceiling grate, or extraction device.

[0016] In the operation of a hammer mill according to the invention, the pieces of the ground material are preferably subsequently mechanically separated in a sorting device according to material characteristics, for example with regard to density, shape and magnetizability, into fractions with the same material characteristics. Example of implementation

[0017] The invention is explained below using an exemplary embodiment. Figures show... Fig. 1 a hammer mill according to the invention, Fig. 2a-c each an upper part of the hammer mill with different positions of a grate flap and Fig, 3: a curved ceiling grid with honeycomb structure.

[0018] The in Fig. Figure 1 shows a hammer mill 1 according to the invention comprising a lower part 2 and an upper part 3, as well as a feeding device 4. A line L, which forms the underside of a flat grate that can be used as an alternative to the ceiling grate 12, marks a dividing line between the lower part 2 and the upper part 3.

[0019] The lower section 2 contains a working chamber 5, which is closed off at the bottom by a floor grate 6. Above the floor grate 6, a plurality of movable hammers (not shown) are arranged on a rotor mounted to rotate about a horizontally extending axis 7. A chute 8 leads from the feeding device 4 into the working chamber 5. The working chamber 5 in the lower section 2 is open at the top and is separated from a vertically extending discharge chute 10 by a partition 9.

[0020] The upper part 3 covers the working chamber 5 and the discharge chute 10 and has a grate flap 11 for the working chamber 5, a ceiling grate 12 made of manganese steel, and a chimney 13 of an exhaust air extraction device (not shown, but known). The grate flap 11 is pivotably arranged above the working chamber 5 opposite the partition wall 9 at an edge 14 of the working chamber 5. In the Fig. In the closed, essentially horizontal position shown in 2a, the grate flap 11 closes off the working space 5.

[0021] The ceiling grate 12 connects to the partition 9 in the upper part 3. An underside 15 of the ceiling grate 12, facing the working chamber 5, follows a circular arc 16 described by the front edge 17 of the grate flap 11 around the edge 14 of the working chamber 5. A casing segment M of the grate flap 11 closes the inner side of the curved ceiling grate 12 facing the working chamber 5, thus allowing continued dust extraction. The grate flap 11, the casing segment M, and the rear wall R, together with sector-shaped end walls (not shown), form a cylindrical segment-shaped closed housing. In the Fig. In the open position of the grate flap 11 shown in 2c, pivoted upwards by approximately 50°, the ceiling grate 12 separates the (now enlarged upwards) working chamber 5 from the discharge chute 10. Accordingly, the ceiling grate 12 is inclined at its underside 15 by approximately 40° to the horizontal.

[0022] The ceiling grid 12 has a substantially constant thickness 18 and a honeycomb structure with honeycomb-shaped openings 19, as can be seen in particular from Fig. 3 results. On its side 20 facing the discharge chute 10, the ceiling grid 12 has a support area 21 for bracing against the partition wall 9, in which no openings 19 are formed.

[0023] The hammer mill 1 according to the invention is used, for example, for crushing automobile bodies or electrical scrap as grinding material: The grinding material is fed from the feeding device 4 via the chute 8 into the working chamber 5 and is crushed there by the hammers and simultaneously pulled further along.

[0024] The pieces of material being ground are swept along by the hammers and flung upwards. With the grate flap 11 closed, the pieces bounce off it and fall back into the working chamber 5. There they are further ground until they fall through the bottom grate 6 into a collection trough (not shown) beneath the hammer mill 1.

[0025] With the grate flap 11 open, the pieces rebound at least partially from the grate flap 11 in such a way that they penetrate through the openings 19 in the ceiling grate 12 and fall downwards out of the hammer mill 1 in the discharge chute 10 into a collection trough (not shown).

[0026] Dust and gases generated during the grinding process are extracted by the exhaust air extraction device via the chimney 13 from the discharge chute 10; the pieces of the ground material collected in the collection troughs are separated in a sorting device (not shown) according to density, color and magnetic permeability into ferrous, non-ferrous and non-metallic fractions, which can then be used further. The characters are 1 Hammer Mill 2 lower part 3 Top 4. Feeding device 5 workroom 6 floor grate 7-axis 8 slides 9 Partition wall 10 Discharge chute 11 Rust flap 12 Ceiling grate 13 Fireplace 14 edge 15 Underside 16 circular arcs 17 Leading edge 18 Thickness 19 Breakthrough Page 20 21 Support area L line M mantle segment R Back wall

Claims

[1] Hammer mill (1) with a feeding device (4) for feeding a working chamber (5) inside the hammer mill (1) with a material to be ground, which is covered at one top by a ceiling grate (12) and to which a discharge chute (10) for pieces of the material to be ground are connected for ejecting from the working chamber (5) through the ceiling grate (12), wherein a rotor with a plurality of movable hammers is rotatably mounted in the working chamber (5) about a horizontal axis (7), which crush the material to be ground and convey it through the working chamber (5), and wherein the ceiling grate (12) is curved towards the discharge chute (10), characterized by , that the curvature describes a circular arc (16) around an edge (14) of the workspace (5). [2] Hammer mill (1) according to the aforementioned claim, characterized by a grate flap (11) that can be pivoted around the edge (14) for the discharge chute (10). [3] Hammer mill (1) according to any of the aforementioned claims, characterized by, that the ceiling grate (12) is inclined at one underside (15) towards the horizontal to the discharge chute (10). [4] Hammer mill (1) according to the aforementioned claim, characterized by , that the ceiling grid (12) is inclined at least 10° to the horizontal on the underside (15). [5] Hammer mill (1) according to any of the aforementioned claims, characterized by , that the ceiling grid (12) has a honeycomb structure at least in sections. [6] Hammer mill according to one of the aforementioned claims, characterized by a receiving device for a flat grate between the rotor and the ceiling grate. [7] Hammer mill (1) according to any of the aforementioned claims, characterized by a floor grate (6) that closes off the working space (5) under the rotor. [8] Hammer mill (1) according to any of the aforementioned claims, characterized by an exhaust air extraction device (13) at the top of the discharge chute (10). [9] Upper part (3) for a hammer mill (1) according to one of the preceding claims, characterized by , that the upper part (3) includes the ceiling grid (12) and, if applicable, a receiving device for a flat grid and is only detachably connected to the lower part (2) by means of screw, plug and / or clamp connections.

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