EP0728523B1 - Roller, method for manufacturing a roller, and material bed roller mill - Google Patents

Description

The invention relates to a roller according to the Preamble of claim 1 and a method for Production of a roller, according to the preamble of the claim 14; it also relates to a material bed roller mill for crushing brittle regrinds, according to the preamble of claim 22.

A roller of the prerequisite in the preamble of claim 1 For example, Art is related to a Gutbettwalzenmühle described in DE-A-42 10 395. In this known embodiment is a Chilled cast iron roll jacket exchangeable on a roll base attached, also on the outside or outer circumferential side of this roll shell profiling welding beads according to certain patterns in the Way can be applied that a profiled Wear protection armor with outwardly protruding hard material strips applied by build-up welding and recesses in between results in which regrind particles are pressed or pressed are and therefore an autogenous wear protection for form the surface of the jacket. Through these measures at the same time a good intake capacity of the material to be shredded Good in that between the two rollers Grinding gap created.

The invention is based on the object, a Roll according to the preamble of claim 1, a method for the production of a roller according to the generic term of claim 14 and a material bed roller mill there according to the preamble of claim 22 further develop that a particularly durable wear protection the roller surface and a reliable one Good collection and interaction of such Rolling even with relatively low consumption of hard material can be guaranteed.

This object is achieved according to the invention by the indicator of claim 1 (relating to the roller) or by the characterizing features of claim 14 (for a Process for producing such a roller) and also by the characterizing part of claim 22 (with respect to the material bed roller mill) solved.

Advantageous embodiments of this invention are the subject of subclaims.

While in the above described as well as comparable other known roller designs profiling thereby been formed on the roll shell are that on its smooth outside (Circumferential outside) hard material strips after a certain Patterns are welded on so that between fill this strip with regrind particles Wear protection armor according to the invention on the outside of the roll shell or a peripheral jacket area clearly different educated. According to the invention, the training takes place this anti-wear armor because that in the material of the peripheral jacket area (or separately formed roll shell) from the outside forth negative profiles in the form of Profile grooves or grooves are formed in which the Good particles - especially during the crushing process in a material bed roller mill - pressed tight are, and that the hard material strips only on the web-like profile projections that delimit the profile grooves are welded on. In this invention trained roller thus become the wells the profiled wear protection armor not only by the material height or material thickness of the the outside of the roll shell by hard overlay welding applied hard material strips determined, but on the one hand through the - radial - depth that from the outside of the peripheral jacket area profile grooves worked into the roller material and on the other hand, from the material height or thickness of the hard material strips. Because these hard material strips only on between the profile grooves or between the profile grooves existing or stopped, web-like Profile projections are welded on, the Roll design according to the invention compared to the known Rollers, in particular grinding rolls, thereby optimized that relatively little of the relatively expensive, highly wear-resistant hard material can be used got to. This can mainly be done by using the profile grooves pressed good particles (which these profile grooves largely or fill in almost completely) in the areas sufficient between the hard material strips solid autogenous wear protection can be created, so that the outside of the peripheral jacket area or Overall roll shell a particularly good, durable Wear protection for the roller surface and at the same time a very reliable good draw-in capacity of the rollers thus formed.

In this roller according to the invention it is also from Advantage if the profile grooves have a cross section with a Depths: width ratio of about 0.4 to 0.75 have, the profile depth - as already indicated - by the sum of the radial web height of the elaborated profile projections and the radial material height the hard material strip is formed. On this way, a particularly high stability of profiling created. It is also special advantageous if the material height of the hard material strips depending on which to load or processing material about 3 to 15 mm, preferably about 4 to 8 mm. Appropriately have the Profile grooves have a maximum cross-sectional width of about 30 to 40 mm.

Another advantageous embodiment of the invention is seen in that the hard material strips from a metal matrix with tungsten carbides embedded in it (or tungsten carbide particles) are produced, whose particle size is about 0.1 to 2 mm, preferably about 0.2 to 1.2 mm and their volume fraction about 50 to 80% of the total volume of the welded hard material strips is.

a) In das Material des Umfangsmantelbereiches bzw. des gesondert ausgebildeten Walzenmantels werden von dessen Außenseite her Negativprofilierungen etwa in Form von Profilnuten bzw. -rillen oder dgl. eingearbeitet, in denen Teilchen des zu bearbeitenden Gutes (insbesondere Mahlgutes) aufgenommen und festgepreßt werden;

b) die Hartmaterialstreifen werden nur auf die Profilnuten begrenzende Profilvorsprünge aufgeschweißt.

The invention also relates to the production of a roller, in particular a grinding roller for comminuting brittle regrind (for example mineral goods, ores or the like) in a material bed roller mill known per se, in which two such rollers are driven in counter-rotating rotation and pressed against one another at high pressure, accordingly the preamble of claim 14. According to the invention, such a roller is produced by the following method steps for forming the wear protection armor:

a) In the material of the peripheral jacket area or the separately formed roll jacket, negative profiles are incorporated from the outside thereof, for example in the form of profile grooves or grooves or the like, in which particles of the material to be processed (in particular ground material) are taken up and pressed;

b) the hard material strips are only welded onto the profile projections delimiting the profile grooves.

A good bed roller mill for shredding brittle Regrind, according to the preamble of the claim 22, is characterized in that the wear protection armor each of the two grinding rollers installed there at least in the previously described invention Way is executed.

Fig.1

eine Querschnittsansicht zweier etwa in einer Gutbettwalzenmühle zusammengeordneter Walzen bzw. Mahlwalzen gemäß der Erfindung;

Fig.2

eine im vergrößerten Maßstab sowie teilweise im Längsschnitt dargestellte Perspektivansicht eines Walzenausschnittes im Umfangsmantelbereich;

Fig.3

eine Teil-Längsschnittansicht durch den Umfangsmantelbereich der Walze zur Erläuterung einer anderen Ausführungsform von Profilnuten;

Fig.4

eine vereinfachte Aufsicht auf eine weitere Ausführungsform der Walze;

Fig.5

eine teilweise (in Axialrichtung) geschnittene Teilansicht zweier in einer Gutbettwalzenmühle zusammenwirkenden Mahlwalzen.

In the following, the invention (both with regard to the structural design and also with regard to the manufacturing process of the roller and also with regard to the material bed roller mill equipped with two such rollers) will be explained in more detail with reference to the drawing. In this largely schematic drawing:

Fig. 1

a cross-sectional view of two roughly arranged in a Gutbettwalzenmühle rollers or grinding rollers according to the invention;

Fig. 2

a perspective view of a roller cutout in the peripheral jacket area, shown on an enlarged scale and partly in longitudinal section;

Fig. 3

a partial longitudinal sectional view through the circumferential surface area of the roller to explain another embodiment of profile grooves;

Fig. 4

a simplified supervision of a further embodiment of the roller;

Fig. 5

a partial (in the axial direction) sectional view of two grinding rollers interacting in a material bed roller mill.

In the following explanation of the drawing it is assumed that rollers designed according to the invention in particular preferably as grinding rollers for comminution brittle regrind in a material bed roller mill can be used, although these rollers also in almost similarly in a roller press or the like. can be installed where there are often similar conditions or stresses can exist if a such a roller press for pressing any mineral goods, e.g. Coal, fertilizer or Like., Is used.

First, the general structure of a known well-bed roller mill explained. In a such roller mill are two opposing - accordingly arrows 1 - - can be driven in rotation, as Grinding rollers 2 arranged rollers arranged with high Pressure (as indicated by arrows 3) at least partially pressed elastically against each other. Both grinding rollers 2 2 have the same design Construction according to the present invention. Between a grinding gap 4 is formed in the two grinding rollers 2, that of the regrind to be crushed (dashed Arrows 5) during the known and therefore not detailed bed crushing happens. It should also be assumed here that the left grinding roller 2 is mounted as a fixed roller, while the right roller an elastic or resilient against the Fixed roller can be pressed and is relatively displaceable Loose roller represents (as known per se).

Below is the basic structure of such Grinding roller with regard to those of particular interest here Wear protection armor explained in more detail.

In the case of Fig. 2 only partially illustrated milling drum 2 it is assumed that this contains a roller body 6, whose annular outer peripheral area is a kind Has roll shell or a peripheral shell region 7, which is particularly illustrated in this Fig.2 is. The roller body 6 together with its peripheral jacket area 7 can according to the invention from a pressure-resistant and well weldable roller base material, for which any suitable material can be used such as. or preferably an 18 Ni-Cr-Mo-14.6 alloy or a similar iron base alloy.

On the outside or outside circumference of this circumferential jacket area 7 is a profiled wear protection armor 8 formed, the protruding outwards Hard material strips 9 9 and existing in between Has depressions 10 in which regrind particles recorded and pressed into a layer, so to speak are, as indicated at 11. This pressed down Regrind layers 11 (in the depressions 10) thus form - in addition to the hard material strips 9 also an essential part of the wear protection armor 8th.

Overall, this wear protection armor 8 is now produced that in the material or in the roller base material of the peripheral jacket area 7 of the On the outside, negative profiles, for example in shape of profile grooves or grooves 12 are incorporated, whereby web-like profile projections 13 remain formed between two adjacent profile grooves 12 are or limit these profile grooves. Only on these profile projections 13 are the hard material strips 9 in layers by build-up welding appropriate hard material welded.

Since such a grinding roller 2 is not only exposed to relatively large wear stresses during operation in a material bed roller mill, but also generally particularly high pressure stresses, care must be taken to ensure that, despite relatively narrow widths b, the profile projections 13 and also the hard material strips 9 welded onto them have sufficient stability this profiling of the wear protection armor 8 is guaranteed. Accordingly, it is expedient if the groove-shaped depressions 10 (which include the profile grooves 12) have a clear cross section with a depth: width ratio (T: B) of approximately 0.4 to 0.75, the depth (T) is formed by the sum of the radial web height h _{1 of} the elaborated profile projections 13 and the radial material height h _{2 of} the hard material strips 9. The material height h _{2 of} the hard material strips 9 is expediently chosen depending on the nature (in particular hardness and abrasiveness) of the ground material to be processed or comminuted and is approximately 3 to 15 mm, preferably approximately 4 to 8 mm, as is shown in FIG. 2 is indicated by different thickness representations in the different illustrated hard material strips 9. The profile grooves 12 and thus the depressions 10 can in turn have a maximum cross-sectional width B of approximately 30 to 40 mm, depending on the material to be ground.

As is also indicated in Fig. 2, it can sometimes be expedient at at least one axial end 2a the grinding roller 2 a slightly wider in the axial direction provided edge strips 14 to provide, however - exactly as in the rest of the longitudinal section of the roller - basically also from a profile projection 13 welded hard material strip 9 there. This Edge strips 14 can, depending on the use and width of the whole roller an axial width of about 20 to 50 mm have.

In addition to the appropriate cross-sectional width B the profile grooves is also their cross-sectional shape of some importance as being special reliable holding of those in the wells 10 or profile grooves 12 pressed ground particles or ground material layer 11 is ensured. In this sense, at least the profile grooves 12 (if necessary also the entire wells 10) one have approximately rectangular to trapezoidal cross-section. 2 is a rectangular one Cross section illustrated (with the light Width B and the total depth T). A trapezoidal Cross section of the profile grooves 12 is in Figure 3 in a Partial longitudinal sectional view illustrates, accordingly the trapezoidal cross section is radial tapered outwards (towards the outside), i.e. the narrower trapezoidal sides of the groove cross section about on the outside of the circumference of the jacket so that a kind of undercut groove shape for the Profile grooves 12 results in a particularly good Press firmly and permanently hold the ground particle layer 11 is guaranteed.

The profile of the wear protection armor profiles mentioned 8 can now be used for various purposes the roller 2 can be adjusted. In the presentation in Fig. 2 it is assumed that the profile grooves 12 and the web-shaped profile projections 13 so in the peripheral jacket area 7 are incorporated that they run in the circumferential direction of the roller 2. In Fig.4 is on the other hand illustrates a way in which the Profile grooves 12 and the web-shaped profile projections 13 extend in the axial direction of the roller 2. Without it should be illustrated in more detail easily imagine that if necessary the profile grooves 12 and profile projections 13 also approximately helical or diagonally running on the outside of the peripheral jacket area 7 can be formed.

It is particularly advantageous in this invention Roller 2 further if the hard material strips 9th made of a metal matrix with tungsten carbides embedded in it or tungsten carbide particles - by hard surfacing - are manufactured in which the Particle size about 0.1 to 2 mm, preferably about 0.2 up to 1.2 mm and the volume fraction of these tungsten carbides about 50 to 80% of the total volume of the welded Hard material strips 9 is. These tungsten carbides can be in the form of tungsten carbides or tungsten pellets. In a more appropriate way The metal matrix can be used for the embedded tungsten carbides made of an alloy containing Ni, Cr, B, Si, an iron-based alloy with the elements C, Mn, Si, Cr and Mo or from an unalloyed filler metal consist.

Also for the purely constructive structure of the invention Roller 2 are several options based on of the two illustrated in cross section in Fig.1 Grinding rollers 2 are explained.

So the left in Fig.1 grinding roller 2 - as already indicated with reference to FIG. 2 - have a roller body 6, the one with its only hinted at - approximately cylindrical - Circumferential jacket area 7 in the form of a Solid roller made of forged steel or, if necessary, cast iron is.

In the case of the right grinding roller 2 in FIG. 1, it is assumed that the roller body 6 in a manner known per se a roller body 6a and one separately on this Roller base body 6a interchangeably attached roller shell consists of the peripheral jacket area described above 7 7 forms. This one on its outside roller jacket provided with wear protection armor 8 can in turn be designed differently his. This roller shell can now be made according to the Representation in the left half (the right roller) in 1 in the manner of an interchangeable bandage 7a fastened in a known manner on the roller base body 6a be on the outside using the Fig. 2 explained wear protection armor 8 8 his. As shown in the right half (the right roller) in Fig. 1 is the drum-shaped roller jacket sort of divided into several jacket segments 7b, which are exchangeable on the roller base body 6a are attached and then in turn on the outside the profile grooves explained in more detail with reference to FIG. 2 12 and profile projections 13 are formed.

expedient as a roller or grinding roller 2 according to the invention can already be produced largely from the previous description. After that the or each grinding roller 2 when training Wear protection armor 8 in several process steps manufactured by in the material of the peripheral jacket area 7 from the outside mentioned profile grooves 12 are incorporated, in which Particles of the to be processed or comminuted Good are picked up and pressed, and by the Hard material strips 9 9 only on the profile grooves 12 delimiting or between these profile grooves 12 remaining profile projections 13 are welded. A depth: width ratio should be appropriate (T: B) from about 0.4 to 0.75 for the clear cross section the wells 10 are adhered to as it is explained in more detail above with reference to FIG.

The in their material composition and other execution also explained in more detail above Hard material strips 9 can be used in the appropriate one Thickness or material height due to build-up welding the profile projections 13 applied in different ways become.

One possibility for the type of surfacing and thus for the formation of wear protection armor 8 is that first the profile grooves 12th incorporated into the peripheral jacket area 7 of the roller body 6 and then on the outside of the next to the Profile grooves 12 stopped or between two adjacent profile grooves 12 remaining, web-like profile projections 13 the hard metal alloy welded to form the hard material strips 9 becomes. The profile grooves 12 and the web-like profile projections 13, for example, either when casting the roller body 6 or after manufacture of the full roller body 6 by appropriate Milling or turning into the material of the Circumferential jacket area 7 are produced.

In any case, it can with the just described Prefabrication of the profile grooves 12 and profile projections 13 be expedient, build-up welding of the hard metal alloy (to form the hard material strips 9) using molds, which the profile projections 13 during the implementation of the surfacing are assigned so that the Hard material strips 9 with particularly great shape accuracy or dimensional accuracy on the outside of the profile projections 13 can be applied.

Another approach to training wear protection armor 8 on the outside of the peripheral jacket area 7 results from the fact that first the carbide alloy according to a the profile grooves 12 to be incorporated Pattern on the outside of the peripheral jacket area 7 welded in the form of strips 9 9 and then the Profile grooves 12 in the area between the welded Strip 9 worked out, preferably milled or be turned out. This can also be extremely good dimensional accuracy and precise shaping both the hard material strip 9 as well as the one carrying it Profile projections 13 and thus also the profile grooves 12 be guaranteed.

Although many different welding processes are used can be to the hard material strips 9 on their To attach profile projections 13, the PTA (plasma Transferred Arc), the MAG (metal active gas), MIG (metal inert gas) and autogenous welding and welding with cored wires are particularly suitable Welding process preferred.

In each of the manufacturing options explained with reference to the drawing the profiled wear protection armor 8 8 can be an optimal width of the profile grooves 12 achieved with relatively narrow profile projections 13 be, the width of the profile grooves 12 many times depends on the grain size of the material to be crushed Feed good. This leads to a relatively small one Width of the profile projections 13 to a proportion low consumption of relatively expensive hard material for the hard material strips 9, without this - with attention an optimal ratio of Depth: Width (T: B) of the profile recesses 10 like explained above - a risk of breakage of the profile projections 13 (with the hard material strips applied to it 9) occur during high operational loads becomes.

Looking again at the schematic in Fig. 1 Cross-sectional view of illustrated bed-type roller mill, then each of the two can be built into it Grinding rollers 2 with wear protection armor according to at least one of the previously described embodiments be executed. Basically there is here also the possibility of using both rollers with the same type attached and equally sized profile grooves 12 and profile projections 13 with welded thereon Form hard material strips 9, namely in such a way that the profile grooves 12 of both grinding rollers 2 and the profile projections 13 with their hard material strips 9 face each other exactly. This would be the case, for example, if both grinding rollers 2 the material bed roller mill is exactly the same as in FIG. 2 illustrated are executed.

However, an embodiment of the Gutbettwalzenmühle, in which the two grinding rollers 2-apart on the respective dimensions of the profile grooves and profile projections - basically constructed in the same way and are made, as it is based in particular 2 and 3 has been explained, the but-how 5 illustrates - the profile grooves 12 and the web-like profile projections 13 (with their on it welded hard material strips 9) on the peripheral jacket area the one grinding roller opposite the profile grooves and profile projections 13 / hard material strips 9 on the peripheral jacket area of the other, opposite Grinding roller 2 'is offset from one another in this way are that - except for relatively narrow end sections - each with pressed-in good particles (cf. good layers 11) filled profile grooves 12 and with hard material strips 9 provided profile projections 13 preferably are approximately symmetrical to each other. this means so that the profile grooves 12 and profile projections of the two opposing grinding rollers 2, 2 'are mutually offset. In doing so, same axial roller width of both rollers the axial Edge strips 14 and 14 'appropriately one have different axial widths to each other and only directly opposite each other in the outermost edge area, as can be seen from Fig. 5.

Claims (24)

1. Roll, particularly a grinding roll for the comminution of brittle materials for grinding in a material bed roll mill, in which two grinding rolls (2) which can be driven so that they rotate in opposite directions are pressed against one another with a high pressure, comprising a roll body (6) with a circumferential casing region (7), the outer face of which has a profiled cladding (8) for protection against wear with outwardly projecting hard material strips (9) and depressions (10) lying between them with particles of material pressed into them, characterised by the following construction of the cladding (8) for protection against wear:

   a) negative profilings, for instance in the form of profile grooves (12), are produced from the outer face in the material of the circumferential casing region (7), and the particles of material are pressed firmly into these profilings;

   b) the hard material strips (9) are only welded onto the land-like profile projections (13) which delimit the profile grooves (12).
2. Roll as claimed in Claim 1, characterised in that the profile depressions (10) have a cross-section with a depth : width ratio (T : B) of approximately 0.4 to 0.75, wherein the depth (T) is formed by the sum of the radial land height (h1) of the exposed profile projections (13) and the material height (h2) of the hard material strips (9).
3. Roll as claimed in Claim 2, characterised in that the material height (h2) of the hard material strips (9), depending upon the material to be processed, amounts to approximately 3 to 15 mm, preferably approximately 4 to 8 mm.
4. Roll as claimed in Claim 2, characterised in that the profile grooves (12) have a maximum cross-sectional width (B) of approximately 30 to 40 mm.
5. Roll as claimed in Claim 2, characterised in that the profile grooves (12) have an approximately rectangular to approximately trapezoidal cross-section, the trapezoidal cross-section tapering radially outwards.
6. Roll as claimed in Claim 1, characterised in that the profile grooves (12) and the land-like profile projections (13) extend in the axial direction of the roll (2).
7. Roll as claimed in Claim 1, characterised in that the profile grooves (12) and the profile projections (13) run approximately helically or in the circumferential direction of the roll (2).
8. Roll as claimed in Claim 1, characterised in that the hard material strips (9) are produced from a metal matrix with tungsten carbides embedded therein, the particle size of which is approximately 0.1 to 2 mm, preferably approximately 0.2 to 1.2 mm, and the proportion by volume of these tungsten carbides being approximately 50 to 80% of the total volume of the hard material strips which are welded on.
9. Roll as claimed in Claim 8, characterised in that the metal matrix for the embedded tungsten carbides consists of an alloy containing Ni, Cr, B, Si, an iron-based alloy with the elements C, Mn, Si, Cr and Mo or from an unalloyed welding additive.
10. Roll as claimed in Claim 1, characterised in that the roll body (6) together with the circumferential casing region (7) is produced from a compression-proof and readily weldable basic roll material, preferably from a 18 Ni-Cr-Mo-14.6 alloy.
11. Roll as claimed in Claim 1, characterised in that the roll body (6) together with its circumferential casing region (7) is produced in the form of a solid roll from forged steel or cast iron.
12. Roll as claimed in Claim 1, characterised in that the roll body (6 ) is made up of a basic roll body (6a) and a tyre (7a) which forms the circumferential casing region and is replaceably fixed on this basic roll body, the outer face of the tyre being provided with the profile grooves (12) and profile projections (13) with the hard material strips (9).
13. Roll as claimed in Claim 1, characterised in that the roll body (6) is made up of a basic roll body (6a) and a plurality of casing segments (7b) which form a closed circumferential casing region and are replaceably fixed on the basic roll body, the profile grooves (12) and profile projections (13) with the hard material strips (9) being constructed on the outer face of the casing segments.
14. Method of producing a roll, particularly a grinding roll for the comminution of brittle materials for grinding in a material bed roll mill, in which two grinding rolls which can be driven so that they rotate in opposite directions are pressed against one another with a high pressure, wherein a profiled cladding for protection against wear, with outwardly projecting hard material strips and depressions lying between them with particles of material pressed into them, is constructed on the outer face of the circumferential casing region of a roll body, characterised by the following method steps for construction of the cladding (8) for protection against wear:

    a) negative profilings, for instance in the form of profile grooves (12), are machined from the outer face thereof into the material of the circumferential casing region (7), and particles of the material to be processed are received and pressed firmly in these profilings;

    b) the hard material strips (9) are only welded onto the land-like profile projections (13) which delimit the profile grooves (12).
15. Method as claimed in Claim 14, characterised in that the profile grooves (12) are produced with a cross-section with a depth : width ratio of approximately 0.4 to 0.75, the total profile depth (T) being formed by the sum of the land height (h1) of the profile projections (13) and the material height (h2) of the hard material strips (9).
16. Method as claimed in Claim 15, characterised in that the hard material strips (9) are produced from a highly wear-resistant hard metal alloy and are applied to the profile projections (13) by build-up welding with material height (h2), depending upon the nature of the material to be processed, of approximately 3 to 15 mm, preferably approximately 4 to 8 mm.
17. Method as claimed in Claim 16, characterised in that for the hard material strips (9) a hard metal alloy is used which contains a metal matrix with tungsten carbides embedded therein in a particle size of approximately 0.1 to 2 mm, preferably approximately 0.2 to 1.2 mm, and in a proportion by volume of approximately 50 to 80% of the total volume of the hard material strips.
18. Method as claimed in Claim 17, characterised in that first of all the profile grooves (12) are machined into the circumferential casing region (7) of the roll body (6) and then the hard metal alloy is welded on the outer face of the land-like projections (13) remaining between each pair of neighbouring profile grooves.
19. Method as claimed in Claim 18, characterised in that the profile grooves (12) and the land-like profile projections (13) are produced during casting of the roll body (6) or by milling into the material of the circumferential casing region (7).
20. Method as claimed in Claim 18, characterised in that the build-up welding of the hard metal alloy is carried out using moulding chills which are coordinated with the profile projections (13) during the build-up welding.
21. Method as claimed in Claim 17, characterised in that first of all the hard metal alloy is welded in the form of hard material strips (9) on the outer face of the circumferential casing region (7) according to a predetermined design corresponding to the profile grooves (12 ) to be machined in, and then the profile grooves (12) are machined out, preferably by milling or recessing, in the region between the welded-on strips.
22. Material bed roll mill for the comminution of brittle materials for grinding, with two grinding rolls (2, 2') which can be driven so that they rotate in opposite directions and are pressed against one another with a high pressure and which each contain a roll body with a circumferential casing region, the outer face of which has a profiled cladding (8) for protection against wear with outwardly projecting hard material strips (9) and depressions (12) lying between them containing particles of pressed-in material, characterised in that the cladding (8) for protection against wear of each grinding roll (2, 2') is constructed in accordance with at least one of Claims 1 to 21.
23. Material bed roll mill as claimed in Claim 22, characterised in that the profile grooves (12) and the land-like profile projections (13) are applied to the circumferential casing region of one grinding roll (2) opposite those on the circumferential casing region of the other grinding roll (2') offset with respect to one another in such a way that - up to short end portions - in each case profile grooves (12) filled with pressed-in particles of material (11) and profile projections (13) provided with hard material strips (9) preferably lie symmetrically opposite one another.
24. Material bed roll mill as claimed in Claim 22, characterised in that the two grinding rolls (2) are constructed with similarly applied profile grooves (12) and profile projections (1 3) with hard material strips (9) welded thereon, so that profile grooves (12) and profile projections (13) with their hard material strips (9) of both rolls lie exactly opposite one another in each case.

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