Roller mill, aspirating assembly, and method for retrofitting a roller mill

Abstract

A roller mill (10) for grinding material, an aspirating assembly (23; 23) and a method of retrofitting an existing roller mill. The roller mill (10) contains a grinding space (11, 11) for grinding material, a separating wall (17) separates the grinding space from an aspiration space (21, 21). At least one aspiration opening (13), is formed in the separating wall (17) through which aspiration air can flow due to a pressure difference between the aspiration space and the grinding space. The roller mill (10) has a closing element (14) for opening and closing the aspiration opening (13). The closing element (14) is in or moves into an opening position (O), which opens the aspiration opening (13), when the pressure difference exceeds a threshold value, and is in or moves into a closing position (S), which closes the aspiration opening (13), when the pressure difference falls bellow the threshold value.

Claims

1. A roller mill for grinding grinding material, said roller mill comprising: at least one grinding space in which the grinding material can be ground, at least one partition wall which separates the grinding space from an aspiration space, at least one aspiration opening which is formed in the at least one partition wall and through which aspiration air can be drawn from the aspiration space into the grinding space on account of a pressure difference prevailing between the aspiration space and the grinding space, wherein the roller mill has at least one closure element for automatically opening and automatically closing the aspiration opening, and the closure element is either designed and arranged in such a manner or is controllable in such a manner, that: the closure element is automatically located in an open position or automatically moves into an open position in which the closure element opens the aspiration opening when the pressure difference exceeds a threshold value, the closure element is automatically located in a closed position or automatically moves into a closed position in which the closure element closes the aspiration opening when the pressure difference undershoots the threshold value, and wherein the roller mill comprises at least one inspection opening, through which the grinding space is accessible, and also at least one grinding space door, with which the inspection opening can be opened or closed, the inspection opening, the grinding space door and the closure element are arranged and designed and matched to one another in such a manner that the pressure difference lies above the threshold value, when the grinding space door is closed, and lies below the threshold value, when the grinding space door is open.

2. The roller mill according to claim 1, wherein the roller mill is a cereal roller mill for grinding cereal.

3. The roller mill according to claim 1, wherein the closure element is designed as a passive closure element, which is designed and arranged in such a manner that: on account of the threshold value being exceeded, the closure element is automatically located in the open position or automatically moves from the closed position into the open position, and, on account of the threshold value being undershot, the closure element is automatically located in the closed position or automatically moves from the open position into the closed position.

4. The roller mill according to claim 3, wherein the closure element is designed and arranged in such a manner that, if the threshold value is undershot, the closure element is automatically located in the closed position or automatically moves from the open position into the closed position on account of its dead weight.

5. The roller mill according to claim 1, wherein the closure element is designed as a pivotable closure flap.

6. The roller mill according to claim 1, wherein a plurality of aspiration openings are provided in the at least one partition wall, through which openings aspiration air can be drawn from the aspiration space into the grinding space on account of a pressure difference prevailing between the aspiration space and the grinding space.

7. The roller mill according to claim 6, wherein a respective separate closure element is provided for each of the aspiration openings and is designed for automatically opening and automatically closing only said associated aspiration opening.

8. The roller mill according to claim 1, wherein the roller mill comprises at least one securing element, which is designed and arranged in such a manner that the at least one securing element prevents the closure element from falling into the grinding space.

9. The roller mill according to claim 1, wherein the roller mill contains a component which is configured to reduce pressure, for at least temporarily generating a reduced pressure in the grinding space, or is connected or can be connected to such reduced pressure means.

10. The roller mill according to claim 9, wherein the component which is configured to reduce pressure is a pneumatic conveying system, which is arranged in the region of a discharge of the roller mill and with an aid of which the ground grinding material can be conveyed away from the discharge.

11. The roller mill according to claim 1, wherein the roller mill comprises at least one frame and an aspirating assembly, which is detachably connected to the frame and contains at least the at least one partition wall, the at least one aspiration opening formed in the at least one partition wall, and the at least one closure element.

12. The roller mill according to claim 1, wherein the closure element is controllable either pneumatically or electrically.

13. The roller mill according to claim 1, wherein the at least one inspection opening is located beneath a pair of grinding rollers of the grinding mill.

Description

(1) Hereinbelow, the invention will be explained in detail on the basis of an exemplary embodiment and a plurality of drawings, in which:

(2) FIG. 1: shows a roller mill according to the invention in a lateral sectional view;

(3) FIG. 2: shows the roller mill in an enlarged lateral sectional view;

(4) FIG. 3: shows an aspirating assembly of the roller mill with a closure flap in an open position in a further enlarged detailed view;

(5) FIG. 4: shows the aspirating assembly of the roller mill with the closure flap in a closed position in a further enlarged detailed view;

(6) FIG. 5: shows the aspirating assembly without a securing bracket in a perspective view, and

(7) FIG. 6: shows the aspirating assembly with a securing bracket in a perspective view.

(8) FIG. 1 shows a cereal roller mill 10 for grinding cereal. The roller mill 10 contains a distributing element 31 with an inlet depot 32 arranged thereabove. With the aid of the distributing element 31, cereal flowing in through the inlet depot 32 is divided into two feed spaces 33, 33 of respective feed-in regions 12, 12. The cereal is metered into grinding spaces 11, 11 by means of respective metering devices 34, 34 of the feed-in regions 12, 12. In said grinding spaces, said cereal is ground with the aid of respective pairs of grinding rollers 35, 35. Aspirating assemblies 23, 23 are arranged in the vicinity of the metering devices 34, 34 and in the upper region of the grinding spaces 11, 11, i.e. in particular above the grinding rollers 16, 16, and separate the respective grinding space 11, 11 from a respective aspiration space 21, 21. Inspection openings 19, 19 are located beneath the grinding rollers 35, 35 and, in the state shown here, are closed by respective grinding space doors 20, 20. Finally, the cereal is conveyed away through respective discharges 16, 16 by means of a pneumatic conveying system (not shown here).

(9) FIG. 2 once again shows, in an enlarged illustration, the feed-in region 12 with the feed space 33 and the metering device 34 and also the aspirating assembly 23, which is arranged in the upper region of the grinding space 11 and separates said grinding space 11 from the aspiration space 21.

(10) The aspirating assembly 23 is shown once again in detail in FIG. 3. It contains a rigid mount 36, manufactured for example from aluminum, with a first horizontal portion 37, a vertical portion 38 and a second horizontal portion 39. At a first end, the first horizontal portion 37 bears with the aid of a first seal 40 against a first boundary wall 24 of the roller mill 10. The opposing end of the first horizontal portion 37 is adjoined by the upper end of the vertical portion 38. The lower end of the vertical portion 38 merges into the second horizontal portion 39, the opposing end of which bears by means of a second seal 41 against a second boundary wall 25 of the roller mill 10. Together with the first seal 40 and the second seal 41, the mount 36 therefore forms a partition wall 17, which separates the grinding space 11 from the aspiration space 21.

(11) A first protrusion 42 with a groove-like recess 43 extends from the vertical portion 38 of the mount 36 laterally and in the direction of the first horizontal portion 37. A closure element designed as a closure flap 14 is hooked into said recess 43 (see in this respect also FIG. 5). In this way, the closure flap 14 is suspended in a pivotable manner, to be precise about a pivot axis which runs parallel to the axes of rotation of the grinding rollers 35 (i.e. perpendicular to the plane of the drawing). A plurality of aspiration openings 13, of which only one can be seen here, are present in the vertical portion 38 of the mount 36.

(12) A second protrusion 44 extends downward from the first horizontal portion 37, and a third protrusion 45 extends downward from the second horizontal portion 39. Furthermore, a notch 47 is provided in the transition region 46 between the first horizontal portion 37 and the vertical portion 38. A securing element designed as a securing bracket 18 is fixedly clamped on the mount 36 by means of the second protrusion 44, the third protrusion 45 and the notch 47, and prevents the closure flap 14 from falling into the grinding space 11.

(13) In the state shown in FIGS. 1 to 3, the grinding space door 20 closes the inspection opening 19, and the pneumatic conveying system adjoining the discharge 16 generates a reduced pressure in the grinding space 11. Since this reduced pressure arises only in the grinding space 11 but not in the aspiration space 21 as well, a pressure difference is formed between the aspiration space 21 and the grinding space 11. This pressure difference has the effect that the closure flap 14 is pivoted against its dead weight and thus opens the aspiration opening 13. As a result of this, aspiration air is drawn from the aspiration space 21 into the grinding space 11. This inflowing aspiration air compensates for the air stream withdrawn at the discharge 16 by means of the pneumatic conveying system. The open position O of the closure flap 14 is therefore present in FIG. 3.

(14) If the grinding space door 20 is then opened, air flows through the grinding space door 20 into the grinding space 11 on account of the reduced pressure which prevails in the grinding space 11. Since the pressure which prevails in the aspiration space 21 does not change in the process, the pressure difference between the aspiration space 21 and the grinding space 11 drops below a threshold value, and therefore the closure flap 14 moves from the open position O shown in FIG. 3 into the closed position S shown in FIG. 4 on account of its dead weight. In this closed position S, the closure flap 14 closes the aspiration opening 13. Therefore, aspiration air can no longer be drawn from the aspiration space 21 into the grinding space 11. Above all, however, no grinding dust can escape out of the grinding space 11 into the environment from the aspiration opening 13. The closure of the closure flap 14, which results in this advantageous effect, is therefore effected as it were automatically when the grinding space door 20 is opened; further operating steps are therefore not required.

(15) In order that the closure flap 14 can securely close the aspiration opening 13 in the closed position S, the position of the recess 43, the shape of the closure flap 14, and that part of the vertical portion 38 of the mount 36 which surrounds the aspiration opening 13 are matched to one another in such a manner that the closure flap 14 is tilted by a small angle of =2.87 with respect to a vertical V in the closed position S, in which it bears against the horizontal portion 38.

(16) If the grinding space door 20 is then closed again, the pneumatic conveying system once again draws air from the discharge 16. Since, however, further air can then no longer flow into the grinding space 11 through the inspection opening 19, the closure flap 14 moves back into the open position O shown in FIG. 3 on account of the pressure difference which then prevails again between the aspiration space 21 and the grinding space 11. This is therefore also effected solely by operating the grinding space door 20.

(17) FIG. 5 shows the aspirating assembly 23 according to the invention separately in a perspective view, but here initially without the securing bracket 18 (this is shown only in FIG. 6). As can be seen in FIG. 5, the aspirating assembly 23 is designed as an elongate strip which extends along a longitudinal direction L. In the inserted state of the aspirating assembly 23, this longitudinal direction L runs in a horizontal direction and parallel to the axes of rotation of the grinding rollers 11.

(18) The vertical portion 38 and the second horizontal portion 39 of the mount 36 and also the two seals 40, 41 are designed with a profiled shape; in other words, they each have a constant cross section along the longitudinal direction L. With the exception of the aspiration openings 13, the first horizontal portion 37 is also designed with a profiled shape.

(19) The first protrusions 42 extending from the vertical portion 38 and the second protrusions 44 extending from the first horizontal portion 38 are not designed with a profiled shape, however, but instead are only present at individual discrete locations. Each of the closure flaps 14 is arranged between two respectively adjacent first protrusions 42. At the upper end, each of the closure flaps 14 has two lateral extensions, which are hooked into the recesses 43 of these two adjacent first protrusions 42. The closure flaps 14 can therefore be pivoted about the recesses 43.

(20) FIG. 6 shows the aspirating assembly 23 together with the securing bracket 18, which is fixedly clamped on the mount 36. In the lower region, said securing bracket has a multiplicity of struts 48, between which there are formed slots 49. These slots 49 are dimensioned in such a manner that aspiration air flowing in through the aspiration openings 13 can pass through said slots 49, but unintentionally detached closure flaps 14 cannot fall through said slots into the grinding space 11.