Mill

Abstract

A mill, in particular a pendulum mill or roller mill, having a classifier, wherein the mill has a mill housing with an interior in which there is situated a milling space B1 in which a milling device having at least one milling tool is arranged. The classifier is arranged above the milling device in a classifying space B3. At least one drop device is provided which connects the classifying space B3 to the milling space B1. Arranged below the classifier is at least one distribution plate which has at least one drop opening on which the at least one drop device is arranged.

Claims

1. A mill, comprising: a longitudinal axis X and a classifier, wherein the mill has a mill housing with an interior in which there is situated a milling space B1 in which a milling device having at least one milling tool is arranged, wherein the classifier is arranged in the mill housing, above the milling device in a classifying space B3 and has a classifying zone, and wherein at least one drop device is provided which connects the classifying space B3 to the milling space B1, wherein at least one distribution plate is arranged below the classifier, having at least one drop opening, wherein one of the at least one drop device is arranged on each one of the at least one drop opening, wherein a diameter Dv of the distribution plate is equal to or greater than a diameter D1 of a classifier wheel of the classifier, and wherein the at least one drop device is provided away from the center of the at least one distribution plate.

2. The mill as claimed in claim 1, wherein an encircling boundary wall is arranged between the classifier and the distribution plate.

3. The mill as claimed in claim 1, wherein a plurality of drop openings are provided in the at least one distribution plate, being arranged on a circle K1.

4. The mill as claimed in claim 1, wherein the at least one drop device is arranged in the interior of the mill housing.

5. The mill as claimed in claim 1, wherein the at least one drop device is associated with the at least one milling tool, and the drop device extends in the milling space (B1) as far as the respective milling tool.

6. The mill as claimed in claim 1, wherein at least one drop device is arranged respectively between two milling tools.

7. The mill as claimed in claim 1, wherein at least one outlet of the drop device is directed at a mill bottom and/or a grinding track and/or a grinding roller of the milling tool.

8. The mill as claimed in claim 7, wherein one horizontal component of an outlet direction A of the outlet of the at least one drop device makes an angle γ with a radial direction R of a circle K2 on which the drop devices are arranged, while 70°<γ<110°.

9. The mill as claimed in claim 1, wherein one horizontal component of an outlet direction A of the outlet of the at least one drop device makes an angle γ with a radial direction R of a circle K2 on which the drop devices are arranged, while −30°<γ<+30°.

10. The mill as claimed in claim 1, wherein the at least one drop device is tapered at a lower end or has a smaller cross section than the rest of the drop device.

11. The mill as claimed in claim 1, wherein the at least one drop device has a curved section with an outlet at a lower end.

12. The mill as claimed in claim 1, wherein the drop device comprises a drop space, which is separated off inside the mill housing by fixtures, a drop pipe and/or a drop tube.

13. The mill as claimed in claim 1, wherein the milling device and the at least one drop device are able to rotate about the longitudinal axis X.

14. The mill as claimed in claim 1, wherein the distribution plate is arranged on the milling device, and wherein the milling device is a rotatable milling device.

15. The mill as claimed in claim 1, wherein the at least one distribution plate is secured on a drive shaft of the mill and/or on a crosshead secured to the drive shaft.

16. The mill as claimed in claim 1, wherein the at least one scoop is arranged in the mill housing, and each scoop is associated with a drop device.

17. The mill as claimed in claim 1, wherein at least one outlet of the drop device is directed at a scoop.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention shall now be explained and represented in the following as an example with the aid of the figures. There are shown:

(2) FIG. 1 a pendulum mill in a perspective, sectional representation,

(3) FIG. 2 the milling device of the pendulum mill with distribution plate of FIG. 1 in a perspective representation,

(4) FIG. 3 a distribution plate of the pendulum mill in a top view,

(5) FIG. 4 the distribution plate and the drop pipes of a pendulum mill in a perspective representation,

(6) FIG. 5 the distribution plate and the drop pipes of a pendulum mill according to a further embodiment in a perspective representation, and

(7) FIG. 6 a schematic representation of parts of a pendulum mill according to a further embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIG. 1 shows an embodiment of a mill 10, designed as a pendulum mill. The pendulum mill 10 has a longitudinal axis X, which also forms the axis of rotation at the same time. The pendulum mill 10 comprises a mill housing 20 with an interior 20a, which is bounded by a peripheral wall 22, a mill cover 25 and a mill bottom 21.

(9) The interior 20a of the mill housing 20 is divided into three spaces B1, B2 and B3, designated as the milling space B1, the transport space B2 and the classifying space B3.

(10) In the classifying space B3 is arranged the classifier 100, having a classifier wheel 110 with diameter D1. The classifier wheel 110 is driven by means of a classifier shaft 114. The classifier 100 furthermore comprises a guide vane assembly 111 surrounding the classifier wheel 110, having an outer diameter D2. Between the classifier wheel 110 and the guide vane assembly 111 is situated the classifying zone 102 of the classifier 100.

(11) Beneath the classifier 100 is located a milling device 80 with a crosshead 88 and three milling tools 81 in the form of grinding pendulums 82, two of which being represented. Each grinding pendulum 82 has a pendulum shaft 84 with a grinding roller 86. The grinding rollers 86 are located in the milling space B3.

(12) The grinding pendulums are swivel-mounted on the crosshead 88. When used as intended, the grinding pendulums 82 are pressed against the grinding track 23 of the grinding ring 27 of the mill housing 20. The grinding stock is ground between the grinding spaces 86 and the grinding track 23.

(13) Beneath the mill housing 20 is arranged a drive mechanism (not shown), which drives a drive shaft 30. The drive shaft 30 extends from the drive mechanism to the mill housing 20. The crosshead 88 of the milling device 80 is arranged at the upper end 34 of the drive shaft 30.

(14) The milling space B1 extends from the mill bottom 21 upward to an upper edge 26 of the grinding track 23. The classifying space B3 extends from a mill cover 25 to a lower edge 116 of the classifier wheel 110. Between the spaces B1 and B3 is situated the transport space B2, in which the distribution plate 40, the crosshead 88 and the pendulum shaft 84 are arranged. The grinding pendulums 82 extend from the crosshead 88 to the milling space B1.

(15) In the transport space B2, a distribution plate 40 with a diameter Dv which is larger than the outer diameter D2 of the classifier 100 is arranged above the crosshead on the drive shaft 30. The distribution plate 40 when used as intended is driven in rotation by the drive shaft 30. In this way, the distribution plate 40 likewise turns about the axis of rotation X. The distribution plate 40 comprises a round disc, in which drop openings 42 are arranged. At the center of the distribution plate 40 there is arranged a distributing cone 43. Only one drop opening 42 is represented of the plurality of drop openings 42, where a downwardly extending drop device 60 in the form of a drop pipe is secured.

(16) In operation, the grinding stock and air stream rises upward in the transport space B2, as indicated by the arrows P1. At the same time, the coarse material is rejected by the classifier 00 in the classifying zone 102 and drops down onto the distribution plate 40, as indicated by the arrows P2. Between the classifier 100 and the distribution plate 40 is situated an encircling boundary wall 130, which prevents contact between the streams P1 and P2 in the upper region of the transport space B2. The boundary wall 130, which is fixed in location, is designed as a cylinder whose height is less than or equal to the spacing between the classifier 100 and the distribution plate 40. The diameter of the upper edge of the cylinder is greater than the diameter D2 of the classifier 100. The diameter of the lower cylinder edge is less than or equal to the diameter Dv of the distribution plates 40.

(17) On the mill housing 20 is arranged a grinding stock feed 90, comprising a chute 92, which extends from a region outside the mill housing 20 to the interior of the mill housing 20. A grinding stock outlet 94 is arranged in the transport space B2 above the milling space B1. The material to be ground is introduced through the grinding stock feed 90 into the mill housing.

(18) Above the classifier 100 there is arranged a suction device 112. The suction device 112 stands in communication with the interior of the classifier wheel 110 and generates a flow, which serves to lift up the material ground between the grinding rollers 86 and the grinding track 23. The material flows from the milling space B1 outside the boundary wall 130 through the transport space B2 and into the classifying space B3. In the classifying space B3, the material at first finds itself outside the guide vane assembly 11 of the classifier 100. Thanks to the flow generated by the suction device 112, the material moves through the guide vane assembly 111 into the classifying zone 102. The classifier wheel 110 separates the material into coarse material and fine material. The fine material gets into the interior of the classifier wheel 110 and is transported by the suction device 112 out from the mill housing 20. The coarse material is rejected by the classifier wheel 110 and drops onto the distribution plate 40—as already described.

(19) FIG. 2 shows basically the arrangement of the milling device 80 in combination with the distribution plate 40 with the distributing cone 42 arranged on its top 45 and the drop devices 60 from FIG. 1. Other parts of the pendulum mill are left out for drafting reasons.

(20) The distribution plate 40 has three drop openings 42, which are arranged on a circle K1. The midpoint of the circle K1 lies in the axis of rotation X. The drop openings 42 are arranged on the circle K1 at regular angular intervals about the axis X. D designates the turning direction of the distribution plate 40. Drop devices 60 designed as drop pipes are fastened to the drop openings 42.

(21) In the representation shown here, the pendulum mill 10 comprises three drop pipes 60. A respective grinding pendulum 82 is arranged along an orbit U (circle K2) of the drop pipes 60 between every two drop pipes 60. Likewise, a respective drop pipe 60 is arranged along the orbit U between every two grinding pendulums 82. The drop pipes 60 are joined together by struts 68. The struts 68 prevent vibrations of the drop pipes 60 during operation. Beneath the drop pipes 60 are drawn scoops 24, which are connected by a support structure 28 to the drive shaft 30 and are driven in rotation by the latter. Grinding stock which has settled on the mill bottom 21 is moved by the scoops 24 in the direction of the grinding track 23, in order to be ground up between the grinding rollers 86 and the grinding track 23.

(22) Each scoop 24 is thus associated with a drop pipe 60. In the present case, the outlets 62 of the drop pipes 60 are oriented such that the material from the drop pipe 60 after exiting from the outlet 62 lands directly on the scoop 24 and in this way is taken at once to the grinding roller 86.

(23) FIG. 3 shows an enlarged top view of the distribution plate 40. One can see that the drop openings 42 are arranged on the circle K1. At the center of the distribution plate 40 is found the distributing cone 43.

(24) FIG. 4 shows an embodiment in which each drop pipe 60 tapers at a lower end 64 and then passes into a curved section 61.

(25) A further embodiment is shown in FIG. 5. The drop pipes 60 do not taper, but each have a curved section 61 at their lower end 64.

(26) FIG. 6 shows a schematic bottom view of the milling device 80 with different arrangements of the drop pipes 60. Each drop pipe 60 has a vertical axis H. The drop openings 42 of the drop pipes 60 are arranged on a circle K1 about the axis of rotation X. The circle K1 has radial directions R. Of the radial directions R, the ones which run through the vertical axes H of the drop pipes 60 are shown. The drop pipes 60 each have an outlet direction A. In FIG. 6, all outlet directions A are horizontal. The outlet directions A are each arranged at an angle γ to the radial direction R of the respective drop pipe. For two of the drop pipes 60 shown, the angle γ is between −30° and +30°, for the other two drop pipes 60 the angle γ is between 70° and 110°.

LIST OF REFERENCE SYMBOLS

(27) 10 Mill, pendulum mill 20 Mill housing 20a Interior 21 Mill bottom 22 Peripheral wall 23 Grinding track 24 Scoop 25 Mill cover 26 Upper edge 27 Grinding ring 28 Support structure 30 Drive shaft 34 Upper end 40 Distribution plate 42 Drop opening 43 Distributing cone 45 Top 60 Drop device, drop pipe 61 Curved section 62 Outlet 64 Lower end 68 Strut 80 Milling device 81 Milling tool 82 Grinding pendulum 84 Pendulum shaft 86 Grinding roller 88 Crosshead 90 Grinding stock feed 92 Chute 94 Grinding stock outlet 100 Classifier 102 Classifying zone 110 Classifier wheel 111 Guide vane assembly 112 Suction device 114 Classifier shaft 116 Lower edge 130 Boundary wall B1 Milling space B2 Transport space B3 Classifying space A Outlet direction D Turning direction of distribution plate D1 Diameter of classifier wheel D2 Outer diameter of guide vane assembly, outer diameter of classifier Dv Diameter of distribution plate H Vertical axis K1 Circle K2 Circle P1 Flow arrow P2 Flow arrow R Radial direction U Orbit X Axis of rotation, longitudinal axis γ Angle