Milling bowl

Abstract

The invention relates to a milling bowl, in particular for vertical mills, and to the production of such a milling bowl. Milling bowls of this type have hitherto typically been produced from a cast material as a single piece. Due to the increasing size of said milling bowls, said milling bowls can generally only be transported to the destinations by means of special transport. Therefore, the invention creates a milling bowl consisting of assemblies, wherein a double-walled center part formed from two housing shells is provided between a head flange and a base flange. Said center part forms a cavity, which is filled with a curable casting compound such that a rotationally rigid milling bowl is present after the casting compound has been cured.

Claims

1. A milling bowl for use in vertical mills, having a lower ring-shaped base flange and an upper ring-shaped head flange for forming or receiving a grinding bed of the vertical mill, wherein the milling bowl is ring-shaped and constructed to be hollow in an area surrounding its axis of rotation, and a center piece, which connects rigidly the head flange and the base flange, wherein a cavity, which is formed between casing shells of the center piece and the two flanges, includes a cured casting compound that fills in the cavity, and wherein the two flanges along with the center piece and the cured casting compound form a rotationally rigid milling bowl, wherein a) the center piece provided between the head flange and the base flange is a separate piece from the head flange and the base flange, and b) the center piece is of double-walled design with the two casing shells, and c) the casing shells of the center piece feature reinforcement anchors, which are embedded into the cured casting compound.

2. The milling bowl according to claim 1, wherein the head flange has a greater outer diameter than the base flange.

3. The milling bowl according to claim 1, wherein the two casing shells are arranged to make a nearly wedge-shaped structure in a vertical section which tapers together in the direction of the base flange.

4. The milling bowl according to claim 1, wherein the two casing shells are situated at an approximate constant radial distance from one another.

5. The milling bowl according to claim 1, wherein at least the head flange is constructed to be a plurality of pieces.

6. The milling bowl according to claim 1, wherein the two casing shells are constructed to be a plurality of pieces.

7. The milling bowl according to claim 1, wherein the base flange is constructed to be one piece.

8. The milling bowl according to claim 1, wherein the milling bowl has, in its vertical section, essentially the structure of a hollow truncated cone.

9. The milling bowl according to claim 1, wherein the curable casting compound is at least a non-shrinking mass.

10. The milling bowl according to claim 1, wherein the casting compound is reinforced with fibers.

11. The milling bowl according to claim 1, wherein the reinforcement anchors are arranged at varying orientations within the cavity formed between the casing shells, and the reinforcement anchor ends are affixed to at least one, or to both, of the casing shells.

12. The milling bowl according to claim 1, wherein the flanges are produced as cast pieces or are made from iron.

13. The milling bowl according to claim 1, wherein the casing shells are produced from steel and are rigidly connected to both flanges.

14. The milling bowl according to claim 1, wherein the head flange features casting openings and aeration openings.

15. A method for producing a ring-shaped milling bowl having, in a vertical section, a hollow structure with an approximate shape of a truncated cone according to claim 1, wherein a) the head flange of the milling bowl is separately produced as a plurality of pieces, and the base flange of the milling bowl is produced separately as a plurality of pieces or as one piece, b) a center piece of the milling bowl features two separately produced casing shells between the head flange and the base flange, c) reinforcement anchors are attached to opposing surfaces of the casing shells, d) components including the head flange, the casing shells of the center piece, and the base flange are rigidly connected with one another, e) a curable casting compound is introduced into the cavity formed between the casing shells via openings in the head flange, f) the casting compound is cured at a non-shrinking volume, and g) following the curing process, a milling bowl is formed as a stiff, rotationally rigid unit.

16. The milling bowl according to claim 9, wherein the non-shrinking mass is a concrete, a resin, or a plastic.

17. The milling bowl according to claim 16, wherein the plastic is based on a high performance or polyamide.

18. The milling bowl according to claim 10, wherein the fibers are glass fibers, carbon fibers, or metal fibers.

Description

(1) The milling bowl according to the invention will be explained in greater detail with the aid of schematic drawings for two examples. Shown are:

(2) FIG. 1 a vertical section through a milling bowl according to the invention as specified in a first example regarding the reinforcement anchors in particular;

(3) FIG. 2 a comparable vertical section through a second example of a milling bowl according to the invention, having, in particular, reinforcement anchors different from than in FIG. 1;

(4) FIG. 3 an overhead view of the milling bowl according to FIG. 2, wherein the half to the left of the L-L line shows the milling bowl with a head flange attached and the corresponding openings are also shown, and the dashed lines represent rod-like stiffening anchors and their orientation. The right half of the L-L line in FIG. 3 shows an overhead view of the milling bowl according to FIG. 2 with the head flange removed; the solid lines are rod-like reinforcement anchors embedded into a casting compound; and

(5) FIG. 4 a vertical section through a milling bowl produced as one-piece from cast material according to a prior art along with the significant elements thereof.

(6) In order to achieve greater flexibility for the company producing this milling bowl with respect to dimensions, delivery time, transportation costs, and, ultimately, aggregate production costs, which include assembly at the intended site of operations.

(7) The milling bowl 1 shown in vertical section in FIG. 1 is produced to be ring-shaped and is made of a plurality of components.

(8) The lower component of the milling bowl 1 features a ring-shaped base flange 5, which, in consideration of its outer diameter, is preferably produced as one piece from a cast material or steel material. A ring-shaped head flange 4, which has a greater outer diameter 11 than the base flange 5, is provided on the upper side of the milling bowl 1.

(9) The head flange 4, which is manufactured from a cast material, preferably has a plurality of ring segments and may consist of, for example, three or four ring segments.

(10) Provided in the head flange 4 is a circular bowl opening 24, which is in the center of and symmetrical with respect to an axis of rotation 21. Circular casting openings 17 and aeration openings 18 are furthermore present in the head flange.

(11) The head flange 4 and the ring segments thereof are preferably produced from cast material or, for example, from metal slabs.

(12) The milling bowl 1 furthermore features a ring-shaped center piece 7, which is formed by an inner casing shell 8 and an outer casing shell 9.

(13) While the inner casing shell 8 nearly extends vertically upward from a lower fastening area 33, where it fastens together with the base flange 5, the outer casing shell 9 is fastened in the outer area of the ring-shaped base flange 5 like a cone with an opening angle upwards base flange.

(14) Advantageously, both casing shells 8, 9 can be produced as a plurality of pieces, in particular, each as two segments, which are preferably welded together to create an inner casing ring and, in the outer area, a cone-shaped outer casing ring. Both casing shells 8, 9 are preferably produced from a ferrous material.

(15) When the milling bowl 1 is assembled, these casing shells 8, 9 form between them a nearly wedge-shaped cavity 12, which tapers towards the bottom. At the top, the upper end of the outer casing shell 9 is furnished with a flat iron ring 19 as a horizontal projecting flange, which is on the one hand, for example, welded onto the upper end of the outer casing shell 9, and is on the other hand, for example, rigidly connected to the lower face of the outer area of the head flange 4 by means of a screwed attachment 25.

(16) Following the construction of the casing shells 8, 9, or rather the segments thereof, reinforcement anchors 14, which in the example are rod-shaped and furnished with a V-shaped end, are, in particular, rigidly welded onto the inner walls of the casing shells 8, 9. A screwed attachment is also possible. In the example shown, these reinforcement anchors protrude from their attachment zones into the cavity 12 in a nearly perpendicular direction. In the example shown according to FIG. 1, these reinforcement anchors 14 are shorter in length, and they do not extend as far as the opposite interior surface of the corresponding casing shell. It is also possible for these reinforcement anchors to be attached to the lower side of the head flange 4.

(17) At their upper end sectors, the casing shells 8, 9 are on the one hand firmly attached to the head flange 4 by means of attachments 32 and 25. The same is true of the lower sectors, where fastenings 33 are provided for the inner casing shell 8, and where fastenings by means of, for example, a fastening anchor 27 and a threaded bolt 28, are also provided for rigidly attaching the outer casing shell 9 to the base flange 5. These means for fixing the casing shells 8, 9 to the flanges 4 and 5 can also be provided as form fits and press fits.

(18) In the example, a reinforcing iron 26 is welded, for example on the outer surface of the outer casing shell 9 in order to further reinforce the iron ring and, in particular of the upper, horizontally projecting flat iron ring 19, which extends from the upper end of the casing shell 9 and into the middle thereof. Said reinforcing iron is, for example, welded, thus achieving greater overall stiffness between the center piece 7 and the head flange 4.

(19) Subsequent to the previously described construction and assembly of the individual components of the milling bowl 1 according to FIG. 1, an additional important step takes place for the final completion of the desired milling bowl 1.

(20) At this point, a casting compound 16 is introduced via the casting openings 17 so as to fill the cavity 12 formed between the casing shells 8 and 9 completely and tightly, in particular without air pockets.

(21) Chosen for this purpose is a mass, which does not shrink upon curing and which, advantageously, exhibits a slight swelling properties during the curing phase.

(22) Aeration openings 18 in the head flange are slightly offset at a distance from and basically radially outward from the casting openings 17. These aeration openings 18 enable the gases present in the cavity 12 during the phase when the casting compound 16 is being introduced to easily escape, thus also achieving a tight seal at the interfaces between the casting compound and the metallic or cast surfaces.

(23) A preferential casting compound is one which, for example, a concrete mixture which interacts with the reinforcement anchors attached in the cavity 12 to produce a ring-shaped core made in the mentioned example, of reinforced concrete having high compressive and tensile strength along with a relatively low coefficient of thermal expansion.

(24) It is also possible to use other casting compounds based on resins or plastics and based in this case in particular on a high-performance polymer or polyamide.

(25) The milling bowl 1 according to FIG. 1 has a stepped, ring-shaped base opening 23 in the base flange 5.

(26) Thus, the lower surface 29 of the base flange 5 rests upon a bearing arrangement, which enables the rotation of the completed milling bowl 1, which is one component of a vertical mill. Otherwise, the gearbox flange used for the milling bowl's rotary drive is provided in the area of the base opening 23.

(27) The concept according to the invention for producing the schematically illustrated milling bowl not only goes beyond achieving a significant cost reduction in comparison with a cast milling bowl produced as one piece.

(28) Indeed, it has been shown that the overall weight of a milling bowl produced in this manner, which measures, for example, approximately 100 tons, can be designed to be even greater in comparison with a one-piece cast milling bowl of approximately the same dimensions, which can weigh approximately 901 tons.

(29) This can also be achieved by virtue of the fact that the volume of the cavity 12 between the casing shells 8, 9 is approximately four times as large as the volume of the center piece 43 of a cast milling bowl.

(30) For example, assuming a casting compound made of reinforced concrete, the weight of the casting compound in relation to the overall weight of the milling bowl can be as much as approximately 60%, whereas the cast and metal pieces in the other components make up only approximately 40% of the overall weight of the milling bowl.

(31) In addition, it should be noted with respect to the following FIGS. 2 and 3, that in this application, the same reference signs refer to the same components and objects.

(32) The milling bowl 2, shown in FIG. 2 as a further example has, in its vertical section, essentially the same structure as was previously described in regards to FIG. 1.

(33) As compared to the milling bowl 1 according to FIG. 1, the key difference exists in the arrangement of the reinforcement anchors 15 within the cavity 12 formed between the inner casing shell 8 and the outer, conical casing shell 9.

(34) In the example according to FIG. 2, the reinforcement anchors 15 in the cavity between the inner casing shell 8 and the conically tapering outer casing shell 9, into which the casting is poured, are arranged so that the ends 13 of the reinforcement anchors are in each case welded onto both interior surfaces of the casing shells 8, 9.

(35) In this context, in addition to the reinforcement anchors being radially arranged and oriented, the reinforcement anchors 15 can also be welded at varying heights onto the corresponding casing shell 8, 9.

(36) In consideration of FIG. 3 makes it evident that the reinforcement anchors 15, for example extending from the surface of the inner casing shell 8, are pointing randomly outward at virtually every angle of orientation. In other words, the reinforcement anchors 15 provided will, in their immediate area, overlap, intersect, and traverse not only in a horizontal plane, but rather (using the vertical direction as a basis) also in three dimensions.

(37) The reinforcement anchors can also be knotted together.

(38) The arrangement of the reinforcement anchors 15 can also have an angular component contrary to the direction of rotation of the milling bowl 2, as a result of which the transmission of forces and torques acting on the casting compound, and hence on the components rigidly connected thereto, will be improved.

(39) The area at left of the L-L line in the schematic depiction according to FIG. 3 shows, as it were, an overhead view of the milling bowl 2 according to FIG. 2 with the head flange 4 placed on top.

(40) The channel 6 formed in the upper surface of the head flange 4 features casting openings 17, which are situated radially inward in the example, as well as circular aeration openings 18, which are situated radially outward in the example.

(41) Facilitated by the conical orientation of the outer casing shell 9, the gas present in the cavity 12 during the casting compound is being poured into the interior cavity 12 through the casting openings 17 can easily escape via the aeration openings 18.

(42) In order to enhance the compression of the poured casting compound, it can, for example, be compressed by means of vibrators at the casting openings 17.

(43) Advantageously, the openings 17, 18 are sealed by means of the casting compound or another material.

(44) To create the grinding bed itself, the appropriate segments, which are typically made of hardened ferrous materials, are inserted into the channel 6 and secured.

(45) The right half of the L-L line in the overhead view depicted in FIG. 3 shows, as it were, the right section of the milling bowl 2 according to FIG. 2 with the head flange 4 removed. The outer semicircle 19 represents in this context the flat iron ring, which according to FIG. 2, supports the head flange 4 from below by means of a screwed attachment 25.

(46) The drawings shown are schematic illustrations, so that simplifications are present in the depictions.

(47) For example, the outer edge of the flat iron ring 19 has a slightly smaller diameter than the outer edge 11 of the head flange 4.

(48) The section on the right seen in FIG. 3 shows the reinforcement anchors 15 represented as solid lines. These are rods embedded into the casting compound 16 and it is evident in this case that the reinforcement anchors 15 cross over and overlap one another.

(49) Therefore, the multi-piece concept according to the invention for producing a milling bowl creates a high degree of flexibility with respect to the material and the dimensional design of a milling bowl, while also being able to significantly reduce the cost of the qualitative requirements for a milling bowl.