Agitator Mill

Abstract

An agitator mill including a milling chamber and a milling rotor, which forms a circumferential boundary wall of the milling chamber during operation. The milling elements are made to execute a milling movement in the milling chamber by the milling rotor. There is also a slit tube for removing the milled material while separating out the milling elements.

Claims

1. A agitator mill comprising a milling chamber and a milling rotor, which forms a circumferential boundary wall of the milling chamber during operation, and milling elements, which are made to execute a milling movement in the milling chamber by the milling rotor, and a slit tube for removing the milled material while separating out the milling elements, wherein the slit tube is an axial slit tube, the adjacent slit formers of which form a slit between their two long edges, to which slit a disruptive geometry is assigned, which causes a milling element rolling or sliding in the circumferential direction along the outer circumferential face of the slit tube to lift off from the outer circumferential face defined by the slit formers as it crosses the slit.

2. The agitator mill, according to claim 1, comprising a milling chamber and a milling rotor, which forms a circumferential boundary wall of the milling chamber during operation, and milling elements, which are made to execute a milling movement in the milling chamber by the milling rotor, and a slit tube for removing the milled material while separating out the milling elements, wherein the slit tube is an axial slit tube, the adjacent slit formers of which form a stepped slit between their two long edges, in the sense that the long edge, bounding the slit, of one slit former lies on a smaller radius than the long edge, bounding the same slit, of the other slit former.

3. The agitator mill according to claim 1, wherein the slit formers are strips, the cross-section of which, in relation to the rotational axis of the slit tube, in each case defines a flat structure, which is fixed to the slit tube such that there is no mirror symmetry relative to the rotational axis of the slit tube and/or relative to any plane of the slit tube, wherein the plane runs through the rotational axis of the slit tube.

4. The agitator mill according to claim 1, wherein the slit formers are strips, the cross-section of which, in relation to the rotational axis of the slit tube, becomes narrower and narrower in the radially inward direction as seen in the circumferential direction.

5. The agitator mill according to claim 1, wherein the slit formers are strips, the cross-section of which, in relation to the rotational axis of the slit tube, is in each case a wedge and preferably a double wedge with at least two wedge sections, the base of which, opposite the inner wedge tip, defines the outer circumferential face.

6. A slit tube for an agitator mill comprising a milling chamber and a milling rotor, which forms a circumferential boundary wall of the milling chamber during operation, and milling elements, which are made to execute a milling movement in the milling chamber by the milling rotor, and a slit tube for removing the milled material while separating out the milling elements, wherein the slit tube is an axial slit tube, the adjacent slit formers of which form a slit between their two long edges, to which slit a disruptive geometry is assigned, which causes a milling element rolling or sliding in the circumferential direction along the outer circumferential face of the slit tube to lift off from the outer circumferential face defined by the slit formers as it crosses the slit, wherein the slit tube is an axial slit tube, the adjacent slit formers of which form a slit between their two long edges, to which slit a disruptive geometry is assigned, which causes a milling element rolling or sliding in the circumferential direction along the outer circumferential face of the slit tube to lift off from the outer circumferential face defined by the slit formers as it crosses the slit.

7. The slit tube foraan agitator mill according to claim 6, wherein the slit tube is an axial slit tube, the adjacent slit formers of which form a stepped slit between their two long edges, in the sense that the long edge, bounding the slit, of one slit former lies on a smaller radius than the long edge, bounding the same slit, of the other slit former.

8. A use of a slit tube comprising a milling chamber and a milling rotor, which forms a circumferential boundary wall of the milling chamber during operation, and milling elements, which are made to execute a milling movement in the milling chamber by the milling rotor, and a slit tube for removing the milled material while separating out the milling elements, wherein the slit tube is an axial slit tube, the adjacent slit formers of which form a slit between their two long edges, to which slit a disruptive geometry is assigned, which causes a milling element rolling or sliding in the circumferential direction along the outer circumferential face of the slit tube to lift off from the outer circumferential face defined by the slit formers as it crosses the slit, wherein the slit tube is an axial slit tube, the adjacent slit formers of which form a slit between their two long edges, to which slit a disruptive geometry is assigned, which causes a milling element rolling or sliding in the circumferential direction along the outer circumferential face of the slit tube to lift off from the outer circumferential face defined by the slit formers as it crosses the slit in a mill and preferably an agitator mill for removing the milled material while separating out milling elements.

9. The agitator mill according to claim 2, wherein the slit formers are strips, the cross-section of which, in relation to the rotational axis of the slit tube, in each case defines a flat structure, which is fixed to the slit tube such that there is no mirror symmetry relative to the rotational axis of the slit tube and/or relative to any plane of the slit tube, wherein the plane runs through the rotational axis of the slit tube.

10. The agitator mill according to claim 2, wherein the slit formers are strips, the cross-section of which, in relation to the rotational axis of the slit tube, becomes narrower and narrower in the radially inward direction as seen in the circumferential direction.

11. The agitator mill according to claim 2, wherein the slit formers are strips, the cross-section of which, in relation to the rotational axis of the slit tube, is in each case a wedge and preferably a double wedge with at least two wedge sections, the base of which, opposite the inner wedge tip, defines the outer circumferential face.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 schematically shows an agitator mill known from the prior art, on which the slit tubes according to the invention are used.

[0057] FIG. 2 shows a non-inventive radial slit tube in an isometric view.

[0058] FIG. 3 shows the radial slit tube from FIG. 2 in a side view.

[0059] FIG. 4 shows the radial slit tube from FIG. 2 in cross-section.

[0060] FIG. 5 shows the movement of a milling element in the region of the radial slit tube from FIG. 2.

[0061] FIG. 6 shows a non-inventive axial slit tube in an isometric view.

[0062] FIG. 7 shows the axial slit tube from FIG. 6 in a side view.

[0063] FIG. 8 shows the axial slit tube from FIG. 6 in cross-section.

[0064] FIG. 9 shows the movement of a milling element in the region of the non-inventive axial slit tube from FIG. 6.

[0065] FIG. 10 shows an axial stepped slit tube according to the invention in an isometric view.

[0066] FIG. 11 shows the axial stepped slit tube according to the invention from FIG. 10 above in a side view.

[0067] FIG. 12 shows the axial stepped slit tube according to the invention from FIG. 10 above in cross-section.

[0068] FIG. 13 shows the movement of a milling element in the region of the slit tube according to the invention from FIG. 10.

[0069] FIG. 14 shows a variant of the invention in the form of an axial helical slit tube.

[0070] FIG. 15 shows a variant of the invention in which the disruptive geometry is designed differently, specifically as a strip protruding radially over the surroundings, like a spoiler.

DETAILED DESCRIPTION

[0071] The operating principle of the invention is explained by way of example with reference to FIGS. 10-13. Modifications are illustrated in FIGS. 14 and 15. The elements or regions appearing multiple times are provided with reference signs only by way of example, for reasons of clarity.

[0072] In the assembled state, the slit tube 6 is arranged in the outlet region of a agitator mill not shown in FIGS. 10-13; see also FIG. 1. It is used to allow the milled material to exit the milling chamber and at the same time to prevent the milling elements 5 from exiting the milling chamber. To this end, the slit tube 6 has a plurality of slits 8 on its outer circumferential face, which is composed of the outer circumferential faces 11 of the slit formers 7. The milled material flows through the slits 8 into the interior of the slit tube 6 and out from there via an open-end face of the slit tube 6. The slits 8 are so narrow that the milling elements 5 do not pass through them or substantially do not pass through them or do not easily pass through them.

[0073] The slit tube 6 is formed from the two end pieces 17, the slit formers 7 and the circular supports 16. The supports 16 are used to hold the slit formers 7 in position and in particular to increase their rigidity. They are formed from rings, ideally metal rings.

[0074] To achieve a sufficiently strong connection between the supports 16 and the slit formers 7, they are ideally welded to one another. The slit formers 7 are arranged at regular intervals around the supports 16, and a slit 8 in the form of a stepped slit is provided between the long edges 9 of two adjacent slit formers 7 in this clearly preferred exemplary embodiment.

[0075] In the assembled state, the end face of the slit tube 6 opposite the end face of the slit tube 6 through which the milled material flows away is ideally closed or at least covered, so that neither milled material nor milling elements can flow through it.

[0076] The slit formers 7 are formed by strips, the extent of which in the direction parallel to the longitudinal axis of the slit tube 6 is at least 10 times greater than their extent in the circumferential direction of the slit tube 6. Ideally, the strips are produced from wires or from drawn or extruded metal material.

[0077] The cross-sectional profile of the slit formers 7 is in this case a wedge 10, preferably in the form of a double wedge, which consists of the two wedge sections 18 and 19. The wedge section 19 is formed by a triangle, while the wedge section 18 is formed by a trapezium. The sides of the wedge sections merge into one another, wherein the double wedge 10 has a kink at the transition of the two wedge sections 18 and 19. This kink therefore means that the angle between the base 11 of the wedge 10 and the sides of the wedge section 18 is greater than the angle between the base 11 and the sides of the wedge section 19.

[0078] To prevent milling elements becoming wedged in the slits and blocking them, the slits 8 are in the form of stepped slits. It is explained how these are formed and what the result of this is with reference to FIGS. 12 and 13.

[0079] In the assembled state, the slit formers 7 are arranged around the longitudinal axis of the slit tube 6 such that the perpendicular on the base 11 and running through the wedge tip 12 does not run through the longitudinal axis of the slit tube 6. It is ideal if the two edges forming the same slit lie on different radii, the delta of which is preferably smaller than four and ideally two milling element diameters, however.

[0080] In other words: It can be preferred for the individual slit formers to be fixed, usually welded, like a row of dominoes tilting in the circumferential direction and to form the stepped slit tube in this way; see FIG. 12.

[0081] This means that the long edge 9 of a first slit former 7 is arranged on a larger radius around the longitudinal axis of the slit tube 6 than the long edge 9, facing this long edge 9, of the next slit former 7. As a result, the slit 8 between each pair of slit formers 7 is in the form of a stepped slit.

[0082] This type of positioning is easy to manage in manufacturing terms. The whole thing is also very advantageous from a wear standpoint, since the cross-sections of the slit formers are thick and therefore wear-resistant everywhere, much more wear-resistant than cross-sections from which a type of spoiler or deflection lips protrude as naturally finer extensions.

[0083] Therefore, milled material in this region flows under a milling element 5 rolling or sliding along a first slit former 7 as it crosses the long edge 9. Since the milled material between the milling element 5 and the slit former 7 flows more slowly than the milled material on the opposite side of the milling element 5, a negative pressure is produced according to Bernoulli in the region between the milling element 5 and the next slit former 7. This means that the milling element 5 is pushed away from the slit tube 6. Blockage of the slits 8 with milling elements is thus counteracted.

[0084] As already mentioned, the term axial slit tube has a narrower and a broader meaning according to the invention. In the narrower sense, it includes only slit tubes with slits having a longitudinal axis which runs (in any case substantially or even completely except for tolerance deviations) parallel to the central longitudinal axis L of the slit tube.

[0085] In a broader sense, however, it currently also covers slit tubes with slits running helically, which can therefore be referred to as axial helical slit tubes. This is illustrated in FIG. 14. Like the slits, the slit formers run helically, but are tilted into themselves, as described previously.

[0086] It should then be noted that the axial slit tube according to the invention can alternatively also have adjacent slit formers 7 which form a slit 8 between their two long edges 9 but form a different type of disruptive geometry. In the present case, the disruptive geometry is formed by a protrusion or spoiler. These are impacted by milling elements in the process of rolling or sliding in the circumferential direction along the outer circumferential face 11 of the alit tube 6 in order then to bounce off in a diagonal radially outward direction and in this manner to be prevented from blocking the slits. This solution functions according to the invention but is subject to much higher wear in some applications owing to the higher impact effect of the milling clements.