Roller jacket for grinding roller of a roller mill, grinding roller, roller mill and method for repairing a grinding roller

Abstract

The invention relates to a roller jacket (1) for a grinding roller of a roller mill, comprising a main body (8) and a plurality of (wear-resistant) segment bodies (3, 3a-c) which are removably attached around the main body (8) in such a way that said segment bodies together form a circumferential working surface (9) of the roller jacket (1), wherein the segment bodies (3, 3a-c) are reversibly releasably fastened to the main body (8) mechanically via fastening elements (6). The fastening elements (6) are provided in such a way that they exert a tensile force component on the respective segment bodies (3, 3a-c) in a radial direction of the main body (8) in order to fix the segment bodies (3, 3a-c) to the main body (8).

Description

[0001] II* Wunderlich's home

[0002] the patent attorney

[0003] - 1 - L 2381

[0004] ROLLER SHATTER FOR GRINDING ROLLER OF A ROLLING MILL, GRINDING ROLLER, ROLLING MILL AND METHOD FOR REPAIRING A GRINDING ROLLER

[0005] The invention relates to a roller shell for a grinding roller of a roller mill, in particular a vertical or vertical roller mill, a grinding roller, a roller mill and a method for repairing a grinding roller of a roller mill.

[0006] Vertical roller mills, also known as vertical roller bowl mills (the terms are used synonymously in the context of this disclosure, and the term "roller mill" is used as a representative term), are used for grinding brittle materials, for example, in the cement industry and also in coal-fired power plants. Materials to be ground can include, in particular, raw meal (a raw material for cement production), cement clinker, limestone, coal, clay, gypsum, blast furnace slag (granulated blast furnace slag), ores, and others.

[0007] Roller mills essentially consist of a rotatable grinding bowl (which can also be referred to as a "grinding plate") and several grinding roller units arranged around a grinding track of the grinding bowl. Each grinding roller unit carries a grinding roller such that the grinding roller is positioned in a working position relative to the grinding track, forming a grinding gap. Within the scope of the present invention, cylindrical, convex, or conical rollers, or their roller shells, are preferably used. The grinding roller units of a roller mill can be interconnected in a common mill structure by being mounted on a common foundation or base.

[0008] Each of the grinding roller units typically has a rocker arm on which the grinding roller is rotatably mounted at one end about a pivot axis. The rocker arm is further mounted on a roller stand via a bearing block or housing, allowing it to pivot about a horizontal pivot axis, such that the grinding roller can be moved, i.e., pivoted, into the working position associated with the grinding path. In a top view, the axis of rotation of the grinding roller extends perpendicular to the pivot axis. A roller mill is disclosed, for example, in WO 2020 / 200455 A1. Designs with a vertical roller guide are also known. The material to be ground is generally fed from above or obliquely from above onto the center of the grinding bowl. The material is moved towards the edge of the bowl by the centrifugal forces. In doing so, the material is gripped by the grinding rollers, rolled over once or several times, and thereby ground.A circulating mixture of coarsely and finely ground material, the so-called "grinding bed," is created on the grinding surface of the grinding bowl. A process gas stream directed upwards enters the grinding chamber through a nozzle ring at the edge of the grinding bowl. This gas carries the lighter, ground material upwards to a classifier or separator, where coarse and fine material are separated. The fine material is discharged, and the coarse material falls back onto the grinding bowl (it is recirculated). Particularly coarse material can fall out of the grinding bowl as overflow or precipitate and can be returned to the mill via an external recirculation system, possibly using a bucket elevator.

[0009] The grinding rollers are subject to considerable wear, requiring frequent replacement. This repair also necessitates shutting down the roller mill and interrupting the grinding process.

[0010] The roller shell, which forms the actual working surface and thus acts as the grinding tool, is the main wear part of a roller mill, especially a vertical mill. It must be welded or replaced once a certain wear depth is reached. Even at the maximum permissible wear depth, the roller shell still retains approximately 80-90% of its original mass. This substantial portion of the shell is then considered waste and must be scrapped. While roller shells can theoretically be recycled, in practice this is rarely the case. Firstly, composite materials like sintered materials are complex to recycle due to the ceramic components they contain. They must also be cut into sufficiently small pieces to fit into a melting furnace. Secondly, these roller shells must be transported to a suitable foundry or steel mill, meaning that transport costs can sometimes exceed the scrap value.This results in thousands of tons of scrap metal being generated worldwide every year, which is not environmentally friendly. To increase the wear resistance of grinding rollers, it is now common practice to reinforce the roller shell, which is subject to high wear, using replaceable, wear-resistant wear segments. In one method, the wear segments are placed in a mold, which is then filled with cast iron, creating a strong connection between the base material and the specially designed underside of the segments, similar to a dovetail joint.

[0011] It is also known, for example, from IN 201721014278, to clamp wear-resistant segment bodies axially onto a roller core by arranging the wear-resistant segment bodies around the outer circumference of a cylindrical base body and fixing them axially between two annular retaining rings, which are fastened to the axial outer ends of the base body by means of screws. It is also known to insert the individual segments into a correspondingly shaped axial recess in the outer circumference of the base body via a dovetail-like extension formed on one underside of the segment and to hold them therein in a form-fitting manner.

[0012] This method of attaching the segments via a dovetail joint and axial fixation has the disadvantage that the segments have play in the guide relative to the base body and can move radially within this play. This movement is repeated cyclically with each rotation during operation, as the segment is pressed against the base body when it moves into the grinding zone. This movement can create a pumping effect, drawing dust into the gaps between the segments or damaging the segments and their contact surfaces. If the gaps become clogged with dust, disassembly can also become difficult or impossible.

[0013] The axial retaining rings play a crucial role in the grinding process and, like the segments, are subject to extremely high grinding pressures, especially at the large diameter of the roller shell (if it is conical). These grinding pressures can generate significant operating loads on the axial mounting screws of the retaining rings, potentially leading to screw failure. Screw failure would trigger a chain reaction of further damage. Theoretically, axially clamping the segment bodies with the axial retaining rings from both ends offers the advantage of allowing the segment bodies to be replaced in situ within the mill. However, it is questionable whether replacing the segment bodies in the mill is simpler and faster than removing the entire roller shell, as a special assembly device typically needs to be attached to the base body to remove the segment bodies.

[0014] The object of the invention is to eliminate or at least mitigate at least some of the above problems in the prior art and to improve the efficiency of wear-related repair of grinding rollers for a roller mill.

[0015] To solve this problem, the invention proposes a roller shell for a grinding roller of a roller mill with the features of claim 1, a grinding roller equipped therewith with the features of claim 13, a roller mill equipped therewith with the features of claim 14, and a method for repairing a grinding roller with the features of claim 15. Preferred embodiments of the roller shell are specified in the dependent claims.

[0016] The invention relates in particular to a roller shell for a grinding roller of a roller mill, comprising a base body and several (wear-resistant) segment bodies detachably mounted around the base body such that these together form a circumferential working surface of the roller shell, wherein the segment bodies are reversibly and detachably mechanically attached to the base body by means of fastening elements. According to the invention, the fastening elements are designed such that they exert a tensile force component on the respective segment bodies in a radial direction of the base body in order to fix the segment bodies to the base body.

[0017] The invention is based on the fundamental idea that the roller shell is designed with a segmented running or working surface with replaceable segments (segment bodies). These wear-resistant segment bodies are attached externally to a preferably one-piece base body and radially fixed, for example by screws. The base body, in turn, is a type of intermediate ring that can be attached to a roller core or shaft section of the grinding roller in a known manner, for example by clamping.

[0018] The base body is not subjected to direct grinding pressure and therefore does not experience significant wear. It can thus be manufactured from a ductile, i.e., relatively easy-to-machine, material, preferably cast steel or spheroidal graphite cast iron, and reused directly. The segment bodies have a hard, wear-resistant surface (harder than the base body material) and can be replaced when they reach their limit of wear. The wear-resistant segment bodies can be manufactured using methods already established in the art, for example, as composite elements made of a highly wear-resistant material and a wear-resistant material, particularly with a ceramic component, such as metal matrix composites.“meta! matrix composite”, MMC) made of spheroidal graphite cast iron or wear-resistant cast iron with ceramic, and a base plate made of a ductile material that is easy to machine and to which the material is attached.

[0019] By radially fixing the segment bodies to the base body, a number of significant advantages are achieved:

[0020] - The grinding pressure acts on the entire contact surface and does not create local stress peaks in the segment bodies or the base body;

[0021] - No gaps or play occur between the segments and the base body. Therefore, no cyclical movement can occur that could cause any damage and / or pumping effects;

[0022] - The disassembly of the segment bodies is not affected by dust ingress; - No operating loads act on the fastening elements (e.g., screws or bolts) because the grinding pressure is transferred directly from the segment bodies to the base body. Screw failure and resulting consequential damage are therefore highly unlikely;

[0023] - The entire grinding surface exposed to grinding pressure can be covered with the same wear-resistant material, so that the service life of the roller shell is not limited by premature wear of fastening components that may also be exposed to grinding pressure (as is the case, for example, with axial fastening solutions in the prior art);

[0024] - By reusing the base body and the possibility of reusing segment bodies that are not yet worn out, material usage is reduced to the actual wear areas, which conserves resources, produces less waste and keeps operating costs low;

[0025] - The production and replacement of the segment bodies can be accomplished more quickly than that of a complete integrated roller shell;

[0026] - The transport and storage of the smaller exchange components (segment bodies) is significantly cheaper and faster due to the possibility of using standard pallets and containers, especially for larger roller shells which would otherwise have to be transported on special transport vehicles;

[0027] - Replacing the segment bodies using the mechanical fasteners is easier, faster, and requires no special equipment, unlike, for example, sending a welder with the necessary equipment;

[0028] - The segmentation of the grinding or working surface and radial mounting eliminates the need for armored retaining ring segments and clamping segments in axial fixings, thereby reducing manufacturing costs;

[0029] - The segmentation of the grinding or working surface into smaller segment bodies also enables the use of technologies for the production of wear-resistant segment bodies, which are limited to smaller sizes due to process constraints and preclude application to entire integrated roller shells.

[0030] A certain disadvantage of the invention is that in-situ replacement of the segment bodies is not possible, at least when the fastening elements are preferably designed to be detachable from a radial inner side of the base body. In this case, removal and replacement of the segment bodies can only be carried out on a disassembled roller shell. On the other hand, accessibility outside the roller mill is simpler, and the segment bodies can be larger because they have to be mounted outside the roller mill anyway. This also reduces the number of segment bodies required for a given roller size and the costs of assembly.

[0031] Preferably, the base body is hollow on the inside to accommodate a section of a roller core / shaft body, and can be manufactured cost-effectively as a steel casting or spheroidal graphite casting.

[0032] The base body of the segment body can have one or more projections that are inserted or can be inserted into a suitable recess in the base body to create a positive-locking connection for absorbing shear forces. Furthermore, the projection can serve to create a thick-walled area for the production of a threaded hole or threaded stud of the fastener.

[0033] The segment bodies can be arranged on the base body with a gap of a few millimeters [mm] between adjacent segment bodies, thus avoiding the need to machine the end faces of the segment bodies. This gap can be filled with a sealant, such as silicone or epoxy resin, or another suitable material, during or after assembly. This prevents the ingress and accumulation of dust between the segment bodies.

[0034] The fastening elements are preferably designed and positioned so that they are accessible from a radial inside surface of the (hollow) base body and can be removed with a suitable tool. In this case, it may be advantageous if the fastening elements (for example, a screw head and / or a thread) are sealed / shielded against dust on the radial inside surface of the base body, for example, also by covering them with a removable sealant such as silicone or epoxy resin or another suitable material.

[0035] A particularly preferred embodiment of the mechanical, detachable fasteners, due to its ease of implementation, is one that incorporates a threaded connection. Preferably, such fasteners can comprise screws, threaded bolts, or studs, each with a shank 6b extending through a recess in the base body and connected to a mating component with a mating thread 6c. To simplify machining and assembly, the fasteners (especially in the form of screws or bolts) can be inserted through bushings that have been previously screwed into radial bores in the base body from the outside in the radial direction. These bushings, which provide the necessary bearing surface to support the tensile force component exerted by the respective fastener in the radial direction, allow the bores to be machined entirely from the radial outside of the base body.Otherwise, the countersinks for receiving the screw heads 6a or nuts as components of the fastening elements with the contact surface for supporting the radial tensile force component would have to be produced with a countersink in bores on the inside of the (hollow) base body.

[0036] On the other hand, in this variant the bushings can also be designed in such a way that, after removal of the fastening element, they can be moved radially outwards using a tool in order to push an associated segment body off the base body in the radial direction outwards (i.e., so that they can be used as a kind of ejector screw when disassembling the segments).

[0037] The respective bushing can have a recess with an internal drive profile (e.g., an internal hexagon) against which the tool for turning the bushing after removing the fastener can be applied. The contact surface for the fastener can be formed at the bottom of this recess.

[0038] The bushings can preferably be anchored in the recess by means of a positive fit and / or a force fit, for example by screwing them in and / or gluing them in and / or crimping or clamping them.

[0039] A circumferential contact surface between the base body and the segment bodies can be either cylindrical or cylindrical with flat or flattened contact areas, so that the contact surface forms a polygonal cross-section, optionally with rounded edges at the transitions. This simplifies the machining of the segment bodies and ensures full-surface contact between the base body and the segment bodies, preventing dust ingress. The mechanical connection (e.g., screwing) of the wear-resistant segment bodies to the base body can optionally be combined with bonding to strengthen the bond.

[0040] The invention further relates in particular to a grinding roller for a roller mill, comprising a roller core / shaft body and a roller shell according to the invention, which is detachably attached to the roller core / shaft body.

[0041] The invention further relates in particular to a roller mill, especially a vertical roller mill, with a rotatable grinding bowl and several grinding roller units arranged around a grinding track of the grinding bowl, each of which carries a grinding roller such that the grinding roller is assigned to the grinding track in a working position, forming a grinding gap. By designing the grinding roller according to the invention, the advantages of the roller shell according to the invention, as previously explained, can be realized.

[0042] Finally, the invention also relates to a method for repairing a grinding roller with a roller shell according to the invention after wear, comprising the following steps:

[0043] Removing the roller shell from a roller core / shaft body of the grinding roller,

[0044] Loosening the fastening elements of at least some of the worn segment bodies and removing these segment bodies from the base body of the roller shell, preferably by movement in a radial direction or in an axial direction of the base body,

[0045] Replacing the removed segment bodies with new segment bodies and attaching the new segment bodies to the base body of the roller shell via the fastening elements, and

[0046] Attaching the roller shell to the roller core / shaft body.

[0047] This method also enables the realization of the advantages and beneficial effects described in connection with the roller shell. The invention is described below by way of example using schematically illustrated embodiments with reference to the accompanying drawings. These show:

[0048] Fig. 1 shows a side view of a conical or conical roller shell for a grinding roller of a roller mill in cross-section along a longitudinal direction;

[0049] Fig. 2 a perspective partial sectional view of the roller shell of Fig. 1; and Fig. 3 variants of segment body arrangements in embodiments of the roller shell.

[0050] The figures show, by way of example, a roller shell 1 for a grinding roller of a roller mill which is conical or conical on the radial outside and overall ring-shaped or rotationally symmetrical, but which is also included in the scope of the invention are round cylindrical or convex roller shells (i.e. those in which a radial working surface 9 of the roller shell is not flat in the axial direction of an axis of rotation, but curved outwards).

[0051] The roller shell 1 comprises a base body 8, which has an approximately triangular cross-section containing the axis of rotation and is also annular or rotationally symmetrical, and has a cavity 12 on its radial inner side, and several wear-resistant segment bodies 3,3a-c detachably attached around the base body 8 in such a way that these together form the circumferential working surface 9 of the roller shell 1 on the radial outer circumference of the roller shell 1, wherein the segment bodies 3,3a-c are reversibly and detachably mechanically attached to the base body 8 by means of fastening elements 6.

[0052] According to the invention, the fastening elements 6 are designed and provided such that they exert a tensile force component on the respective segment bodies 3, 3a-c in a radial direction of the base body 8, thereby fixing the segment bodies 3, 3a-c to the base body 8. After loosening the fastening elements 6, the segment bodies 3, 3a-c can be removed from the base body in a radial direction or, if they are additionally received in a dovetail guide as is known in the prior art, in an axial direction of the base body. To form a functional grinding roller, the roller shell 1 is detachably attached to a roller core / shaft body 11, which is only schematically shown in the drawing, by placing the roller shell 1 with its radially inner cavity onto a section of the roller core / shaft body 11 and clamping it in place (the illustration of the grinding roller in Fig.Figure 1 is schematic and does not correspond to the actual situation, as only one side in cross-section is shown in detail.

[0053] The grinding roller is mounted on a roller unit (not shown) for use in a roller mill and rotatably mounted. In a roller mill, particularly a vertical roller mill, several roller units, for example an even number such as 2, 4, or 6, are arranged around a grinding track of a rotatable grinding bowl (also not shown) that can be actively driven to rotate. The grinding roller units each support a single grinding roller such that the respective grinding roller can be selectively assigned to the grinding track in a working position, forming a grinding gap. A roller mill in which the grinding rollers with the roller shells according to the invention can be used is disclosed, for example, in WO 2020 / 200455 A1 and is included for the explanation of the details of a basic structure of such a vertical roller mill that are not shown here.

[0054] Each of the grinding roller units has a bearing lever, in particular a rocker arm, on which the grinding roller is rotatably mounted about an axis of rotation aligned with an axis of symmetry of the grinding roller. The grinding roller can be actively driven or freely rotatable, so that it is passively carried along in interaction with the material being ground on the rotating grinding bowl.

[0055] The rocker arm is mounted on a rigid roller stand via a bearing block / bearing housing, and in particular pivotable about a pivot axis, such that the grinding roller, which is mounted at one end of a lever arm of the rocker arm, can be moved into the working positions associated with the grinding track, and in particular, can be repositioned. The roller stands of the roller mill are rigidly mounted to a base (not shown) of a machine base, so that the grinding forces occurring during operation can be introduced into and supported by the machine base.

[0056] The grinding roller has a cylindrical, conical, or convex roller shell, with the conical roller shell, which is also shown as an example in this disclosure, being preferred. This has the consequence that, in the case of a conical roller shell as shown here, and preferably in conjunction with the pivotable mounting of the grinding roller at one end of the rocker arm, a change in the roller position (height distance to the grinding track) is always accompanied by a change in the angle of the roller position, and the roller position is linked to a specific working position or a specific pivot position of the rocker arm via a parallel gap.

[0057] The base body 8 of the roller shell is made of a ductile material that is easy to machine and is designed as a reusable part. The base body 8 can, for example, be manufactured from cast steel or ductile iron followed by machining. As shown in Fig. 2, the internal cavity can also have recesses and grooves to provide clearance for the fastening elements described later between the base body and the roller core / shaft body 11.

[0058] The segment bodies 3, as the actual wear parts, each comprise a base body 4b and a wear-resistant surface 4a, preferably made of a different material than that of the base body 4b. In the embodiment shown, the base body 4b preferably has a base plate made of a ductile material, for example steel, to which a wear-resistant material, in particular with a ceramic component (for example, made of metal matrix composites, spheroidal graphite cast iron, or wear-resistant cast iron with ceramic), is attached to form a composite element (for example, by force-fit and / or form-fit fastening).

[0059] In this embodiment, the base body 4b has a projection 5 that is inserted or can be inserted into a suitable recess in the base body 8 to ensure precise positioning and a positive connection for receiving and transmitting transverse forces. In addition to transmitting transverse forces to the base body, the projections 5 also provide thickened areas for creating, for example, threaded bores into which fasteners 6 with screw threads (screws, bolts) can be screwed to fix the segment bodies 3 to the base body 8. By screwing these radially to the base body, the tensile force component is exerted on the respective segment bodies 3 in the radial direction of the base body 8. The tensile force component does not necessarily have to be exactly radial in the strict sense.The segments do not run perpendicular to a central axis of the base body, but can – as also shown in the exemplary embodiment – ​​run at an angle to the central axis. The essential point is only that the segment bodies 3 are fixed to the base body without radial play and that the working surface 9 of the roller shell has no fastening components that are subjected to the grinding pressure during operation.

[0060] In the embodiment shown in Figures 1 and 2, the segment bodies 3, 3a-c are arranged circumferentially in three axially adjacent rows and together form the wear-resistant working surface. The adjacent segment bodies 3, 3a-c can be arranged on the base body 8 with a certain gap 13 between neighboring segment bodies 3, 3a-c, the gap 13 preferably being filled with a sealant (e.g., silicone, epoxy resin). In this case, the outer edges of the segment bodies 3, 3a-c, or of their hard, wear-resistant surfaces 4a, do not need to be precisely machined, which reduces manufacturing costs.

[0061] Fig. 3 shows further variants of the segmentation of the working surface 9 of the roller shell by the segment bodies 3, 3a-c, wherein, according to Fig. 3a, two circumferential rows of segments 3a, 3b are provided and the segments 3b are fastened on the right side by two fastening elements (screws) each. According to Fig. 3b, a single circumferential row of longer segments 3a is provided, which are also fastened by two fastening elements (screws) each. According to Fig. 3c, two circumferential rows of segments 3a, 3b are provided, which, instead of a third row (as in the variant of Fig. 1 / 2), are supplemented by a circumferential armor plate 8a, which is formed from the same material as the base body 8. This variant can be advantageous if a specific axial section of the working surface is subject to lower grinding pressure and wear.

[0062] In the exemplary embodiments, the fastening elements 6 are provided such that they can be detached from the radial inside of the base body 8, i.e. from the inner cavity 12.

[0063] The mechanical fasteners 6 preferably have a threaded connection, which may include, for example, screws, threaded bolts, or studs, each extending through a recess in the base body 8, and a corresponding mating thread. In the illustrated embodiments, the fasteners 6 are designed as screws that are inserted from the inside of the base body 8 into recesses in the base body and screwed into threaded bores in the segment body 3, 3a-c or in the respective projections 5 of the base plate 4b. An enlarged head of the screws is recessed in a recess of the base body 8.

[0064] To simplify machining and assembly, the fasteners 6 (here, screws) are inserted from the radial inside through bushings 7 that have been previously screwed into larger recesses or bores in the base body 8. These bushings 7 allow the bores to be machined entirely from the radial outside. Otherwise, countersinks for the screw heads and a bearing surface to support the tensile force component exerted by the respective fastener 6 would have to be machined on the radial inside of the inner cavity using a countersink. Depending on accessibility, the bushings 7 can be installed in some, preferably all, of the recesses. They can be anchored in the recess preferably by positive locking and / or friction locking, for example, by screwing and / or bonding.

[0065] The bushings 7 are further designed such that they have the contact surface 7a for supporting the tensile force component exerted by the respective fastening element 6 in the radial direction.

[0066] The bushings 7 can also be used as extraction screws during the disassembly of the segments. For this purpose, the bushings 7 are designed such that, after removal of the fastening element 6, they can be moved radially outwards using a tool in order to extract an associated segment body 3,3a-c from the base body 8 in the radial direction outwards (which of course requires that the segment bodies are not inserted into undercut or dovetail-like recesses of the base body from which they would have to be pulled out in an axial direction).

[0067] The bushings 7 in the illustrated embodiments have, for example, a recess 7b with an internal drive profile (e.g., an internal hexagon) against which the tool for turning the bushing 7 can be applied. The contact surface 7a for the fastening element 6 is, for example, formed at the bottom of the recess 7b. The drive profile can also have a different shape.

[0068] The fastening elements 6 and the receiving recesses for them on the radial inside of the base body 8 can be sealed / shielded against dust by individually covering or filling them with an easily removable material such as resin, plastic or rubber, or by detachably inserting a cover element on the inside, for example into the recesses or grooves shown.

[0069] In a variant not shown, it is conceivable to guide the fastening elements from the radial outer surface of the roller shell through the segment bodies and screw them into the base body. For this purpose, recesses can be formed in the segment bodies to lower the heads of the fastening elements relative to the working surface, preferably to the extent of a wear limit. The recesses can then be filled with a removable material, as described for the inner surface and the gap, to seal / shield the fastening elements against dust.

[0070] The contact surface between the base body and the segment bodies is preferably not curved, but rather polygonal, as can be seen in Fig. 2. The contact surface between the base body 8 and the segment bodies 3, 3a-c on the outer circumference of the base body therefore has flat contact areas 8a, so that the contact surface forms a polygonal cross-section. This simplifies the machining of the segment bodies and their base bodies and ensures full-surface contact between the base body 8 and the respective segment bodies 3 in a simple manner, preventing the ingress of dust. The screwing of the wear-resistant segment bodies to the base body 3 can optionally be combined with adhesive bonding to reinforce / secure them.

Claims

II* Wunderlich's home the patent attorney L 2381 Claims 1. Roller shell (1) for a grinding roller of a roller mill, comprising: a basic body (8), and several (wear-resistant) segment bodies (3,3a-c) detachably attached around the base body (8) such that these together form a circumferential working surface (9) of the roller shell (1), wherein the segment bodies (3,3a-c) are reversibly and detachably mechanically attached to the base body (8) via fastening elements (6), characterized by the fact that the fastening elements (6) are provided such that they exert a tensile force component on the respective segment bodies (3,3a-c) in a radial direction of the base body (8) in order to fix the segment bodies (3,3a-c) to the base body (8).

2. Roller shell (1) according to claim 1 , characterized by the fact that The base body (8) comprises a ductile material and is hollow on the inside to accommodate a section of a roller core / shaft body (11), wherein the base body (8) is preferably made of cast steel or ductile iron.

3. Roller shell (1) according to claim 1 or 2, characterized by the fact that the segment bodies (3,3a-c) have a base body (4b) and a wear-resistant surface (4a), preferably made of a different material than that of the base body (4b), wherein the base body (4b) preferably has a base plate made of a ductile material to which a wear-resistant material, in particular with a ceramic component, is attached.

4. Roller shell (1) according to claim 3, characterized by the fact that the base body (4b) has a projection (5) which is inserted or can be inserted into a suitable recess in the base body (8) to create a positive connection for absorbing shear forces.

5. Roller shell (1 ) according to any one of claims 1 to 4, characterized by the fact that the segment bodies (3,3a-c) are arranged with a gap (13) between adjacent segment bodies (3,3a-c) on the base body (8), wherein the gap (13) is preferably filled with a sealant (silicone, epoxy resin).

6. Roller shell (1 ) according to any one of claims 1 to 5, characterized by the fact that The fastening elements (6) are provided such that they are detachable from a radial inner side of the base body (8) and are preferably sealed / shielded against dust on the radial inner side of the base body (8).

7. Roller shell (1) according to any one of claims 1 to 6, characterized by the fact that the fastening elements (6) have a threaded connection, and preferably have screws, threaded bolts or studs, each passing through a recess in the base body (8).

8. Roller shell (1 ) according to any one of claims 1 to 7, characterized by the fact that A bushing (7) is installed in at least some, preferably in all recesses, preferably in a radial direction of the base body (8) from a radial outside, and / or is preferably positively and / or force-fit anchored (screwed in and / or glued in) in the recess.

9. Roller shell (1) according to claim 8, characterized by the fact that the bushing (7) is designed such that it has a contact surface (7a) for supporting the tensile force component exerted by the respective fastening element (6) in the radial direction.

10. Roller shell (1) according to claim 8 or 9, characterized by the fact that The bushing (7) is designed such that, after removal of the fastening element (6), it can be moved radially outwards by means of a tool in order to press an associated segment body (3, 3a-c) off the base body (8) in the radial direction outwards.

11. Roller shell (1) according to claim 10, characterized by the fact that the bushing (7) has a recess (7b) with an internal drive profile on which the tool for turning the bushing (7) can be applied, and preferably a contact surface (7a) for the fastening element (6) is formed in the recess (7b).

12. Roller shell (1 ) according to one of claims 1 to 11 , characterized by the fact that a contact surface between the base body (8) and the segment bodies (3,3a-c) has flat contact areas (8a) such that the contact surface forms a polygon in cross-section.

13. Grinding roller for a roller mill, with a roller core / shaft body (11) , and a roller shell (1 ) according to one of claims 1 to 12, which is detachably attached to the roller core / shaft body (11 ).

14. Roller mill, in particular vertical roller mill, with: a rotating grinding bowl, and several grinding roller units arranged around a grinding track of the grinding bowl, each carrying a grinding roller such that the grinding roller is assigned to the grinding track in a working position forming a grinding gap, characterized in that at least some, preferably all, grinding rollers are designed according to claim 13.

15. Method for repairing a grinding roller with a roller shell (1) according to any one of claims 1 to 12 after wear, comprising the steps: Removing the roller shell (1) from a roller core / shaft body (11) of the grinding roller, Loosening the fastening elements (6) of at least some of the worn segment bodies (3,3a-c) and removing these segment bodies (3,3a-c) from the base body (8) of the roller shell (1), preferably by a movement in a radial direction or in an axial direction of the base body (8), Replacing the removed segment bodies (3,3a-c) with new segment bodies (3,3a-c) and attaching the new segment bodies (3,3a-c) to the base body (8) of the roller shell (1) via the fastening elements (6), and Attaching the roller shell (1) to the roller core / shaft body (11).

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