SINGLE-PIECE GRINDING ROLLER AND METHOD FOR PRODUCING A GRINDING ROLLER

Abstract

The present invention relates to a one-piece grinding roller (1) for vertical-axis grinders produced by casting in a metal mould in a foundry, the roller comprising, on its periphery, a perforated reinforcing structure (2) consisting of a plurality of ceramic inserts contiguously joined together, the contiguous assembly of the ceramic reinforcements being carried out along wavy lines.

Description

1 / 23 “ONE-PIECE GRINDING ROLLER AND METHOD FOR PRODUCING A GRINDING ROLLER Subject of the invention

[001] The present invention relates to a composite wear component cast from a ferrous alloy. It relates more particularly to a one-piece grinding roll reinforced by a perforated ceramic structure incorporated into the roll with a specific set of reinforcing elements that is possibly adapted to the wear stress, creating differentiated perforation. It also discloses a method for manufacturing said roll. Prior art

[002] Cast composite wear components are well known to those skilled in the art. These are mainly cast iron components that are locally reinforced in a targeted manner by alumina-zirconia type ceramics, or carbides, nitrides, borides or other intermetallic elements, on the faces most exposed to wear. These ceramics have studied geometries and are suitably situated within the metallic matrix.

[003] The particular arrangement of the reinforcement structures allows specifically the creation of hierarchical composites with differentiated reinforcement according to the arrangement or geometric shape of the ceramic reinforcements, which are generally composed of aggregates of grains infiltrated by the molten metal. In this way, it is possible to produce aggregates of granules measuring, on average, 3 to 8 mm with interstices of the order of 1 to 3 mm allowing infiltration by the liquid molten iron during casting. Petition 870250080762, dated 09 / 09 / 2025, page 11 / 49 2 / 23 Thus, it is possible to form cakes or "wafers" in the form of perforated honeycomb-type structures, for example. These "inserts" are generally arranged in a studied manner within a sand mold on the most stressed face of the wear component. These "inserts" are called "fillers." When these cakes are individually infiltrated, before being discarded, once cooled, in the casting mold, they are called bars.

[004] The present invention aims to improve the wear resistance of grinding rolls for mills in general and, in particular, for so-called vertical shaft mills. Vertical shaft mills are used, for example, to grind coal, raw mix or cement clinker. They consist of rollers supporting a rotating track that are driven by the rotational movement of the track along the vertical axis (see Figure 1). The material to be ground is introduced through a central feed path and falls onto the track, where it is crushed and ground by the rollers. This principle is illustrated in detail in Figure 2. The ground material is then discharged by centrifugation to the periphery of the track and recovered in a blower with a cyclone, allowing the material that has not yet been sufficiently ground to be recycled. Several types of roller shapes are possible, with frustoconical rollers and toric rollers being the most common.

[005] Document WO98 / 15373 discloses a cast composite wear component with a ceramic reinforcement in the form of a honeycomb and an aluminazirconia-based ceramic. Petition 870250080762, dated 09 / 09 / 2025, p. 12 / 49 3 / 23

[006] Document WO2005 / 084809 discloses a grinding roll composed of several peripheral bars made of a material with high wear resistance and mechanically sealed in a cast die of ductile material, said roll comprising zones subject to high wear stress and zones subject to low wear stress, the roll having in its peripheral front bars comprising a contiguous part in the more stressed zone and a non-contiguous part in the less stressed zone, the gap in the non-contiguous part being filled by the ductile material of the cast die, allowing the mechanical sealing of the bars.

[007] Document WO2018 / 069006 discloses a grinding roll for vertical shaft mills that is cast by casting a metal die, the roll comprising on its periphery a plurality of reinforcing inserts, of which certain portions of the peripheral surface of the same insert are situated at different distances from the periphery of the roll, depending on the wear stresses.

[008] Document WO 2021 / 1160381 discloses a grinding roll where the areas subject to wear are differentially reinforced with ceramic inserts composed of blind holes and through holes, with the blind side of the blind holes oriented towards the side most stressed by wear. Objectives of the invention

[009] The present invention aims to provide a one-piece grinding roll with a ceramic reinforcement composed of a plurality of inserts of improved geometry, whose structure and positioning are adapted to the wear stress. It aims to, Petition 870250080762, dated 09 / 09 / 2025, p. 13 / 49 4 / 23 in particular, eliminate the straight lines between adjacent ceramic inserts, which constitute propagation initiators and preferred paths for wear. Summary of the invention

[0010] The present invention discloses a one-piece grinding roll for vertical shaft mills that is cast by casting a metal die, said roll comprising on its periphery a perforated reinforcement structure consisting of a plurality of contiguously mounted ceramic inserts, the contiguity mounting of the ceramic reinforcements being produced along wavy lines.

[0011] Preferred embodiments of the invention have at least one, or any suitable combination, of the following characteristics: - the reinforcement structure 2 comprises at least a first zone 21, which is the least perforated and most exposed to wear, and at least a second zone 22, which is the most perforated and least exposed to wear; - the first and second zones 21 and 22 of the plurality of ceramic inserts are formed by multiple overlapping rings, these inserts being mounted in a staggered and contiguous manner along wavy lines; - the perforation of the first zone 21, which is the most exposed to wear, is formed by through holes 3 of frustoconical shape with a diameter that progressively decreases towards the periphery of the roller or by a combination of through holes 4 of any shape with blind holes whose blind side is located on the peripheral side of the roller; Petition 870250080762, dated 09 / 09 / 2025, p. 14 / 49 5 / 23 - the perforation of the second zone 22, which is the least exposed to wear, is formed by through holes 4 of any shape, preferably cylindrical, and positioned perpendicularly or at an angle to the surface on the periphery of the roller; - the plurality of inserts is assembled in such a way as to form a frustoconical roll or a toric roll; - the amplitude (a) of the wavy lines represents between 2 and 20%, preferably between 5 and 15%, in relation to the length L of the ceramic insert; - the amplitude (A) of the wavy lines represents between 2 and 20%, preferably between 3 and 15%, in relation to the width l of the ceramic insert; - The ceramic composition of the reinforcing structure is selected from oxides, carbides, nitrides, and borides; - Ceramic inserts consist of an aggregate of ceramic-metallic composite grains in which the micrometric ceramic particles are cemented into a metallic binder, with the composite grains having an average D50 dimension of 2 to 8 mm, preferably 3 to 6 mm, determined by sieving with a square mesh or by a Retsch Camsizer in accordance with Standard 13322-2:2006; - The metal-ceramic composite grains consist of medium-sized titanium carbide (D50) between 3 and 20 μm, preferably between 5 and 15 μm, cemented into a metallic binder. The particle size distribution is measurable by laser diffraction using the MIE theory according to the instructions provided in ISO 13320:2020, using, for example, a Malvern Mastersizer 2000. Petition 870250080762, dated 09 / 09 / 2025, page 15 / 49 6 / 23 defining a refractive index of 3 and an absorption index of 1. The obscuration should be in a range between 10 and 15% and the weighted residual less than 1%; - The ceramic composition of the reinforcement structure in the first zone 21 is different from the ceramic composition in the second zone 22.

[0012] The present invention also discloses a method for producing a grinding roller according to the invention, comprising the following steps: - Supply of a mold for the production of a one-piece grinding roll by casting from a ferrous alloy; - Positioning of a reinforcement structure composed of a plurality of ceramic inserts mounted contiguously in wavy lines, the inserts being in the form of perforated aggregates of millimeter-sized granules, the aggregate being permeable and therefore infiltrable; - infiltration of the insert by the liquid ferrous alloy; - Cooling and demolding of the grinding roll.

[0013] The method according to the invention preferably has at least one, or any suitable combination, of the following characteristics: - Ferrous alloys comprise steel or cast iron; - the reinforcement structure comprises at least one first zone 21, which is the least perforated and most exposed to wear, and at least one second zone 22, which is the most perforated and least exposed to wear; - The infiltrated aggregates of millimeter-sized ceramic granules used for grinding roller inserts are selected from the following compositions: Petition 870250080762, dated 09 / 09 / 2025, p. 16 / 49 7 / 23 - alumina-zirconia in proportions of 90 / 10 to 10 / 90, with the zirconia possibly being stabilized with yttria; - carbon powder and titanium, optionally including iron powder as a moderator and precursors of a self-propagating thermal synthesis (SHS) reaction initiated by melting the ferrous alloy; - Ceramic-metal composites of titanium carbide cemented to a metal binder. Brief description of the figures

[0014] In the annotated figures below, the inserts are shown schematically. In reality, these ceramic inserts are three-dimensional infiltrated structures formed by permeable aggregates, such as, for example, agglomerates of millimeter-sized grains (with an average size of 2 to 8 mm, preferably 3 to 6 mm) aggregated by an adhesive with millimeter-sized interstices that are infiltrable by the molten metal.

[0015] For simplicity's sake, the figures show only the outline of these inserts placed in the reinforced parts of the grinding roller.

[0016] Figure 1 shows an example of a vertical shaft mill equipped with frustoconical grinding rolls pressing and rotating on a rotary table fed with ore to be ground.

[0017] Figure 2 shows the grinding principle using a frustoconical grinding roller.

[0018] Figure 3 shows a grinding roller produced with bars that are reinforced with ceramic according to the state of the art WO2005 / 084809. In this case, a plurality of honeycomb-shaped ceramic inserts is Petition 870250080762, dated 09 / 09 / 2025, page 17 / 49 8 / 23 infiltrated individually to form bars before being discarded, once cooled, into a mold, ensuring a distance is maintained between each individual reinforcing element (non-contiguous assembly) to allow molten metal to penetrate between the individual elements and ensure the sealing of the assembly on the cast roll.

[0019] Figure 4a shows a bar consisting of a metal die incorporating a honeycomb-shaped ceramic insert. Figure 4b shows a detail of the bar assembly before casting on the grinding roll.

[0020] Figure 5 shows an image of a frustoconical grinding roller that is very worn on its underside. It is a grinding roller according to the state of the art and produced according to the techniques shown in Figures 3, 4a and 4b. A ceramic structure in the form of a honeycomb is seen protruding through a heavily eroded metal matrix. The spaces left between the individual bars (straight grooves) are also heavily corroded.

[0021] Figure 6 shows an image of a toric grinding roll that has a significant level of wear. It was produced according to the state of the art WO2005 / 084809 by discarding infiltrated and cooled bars in a mold, maintaining a distance between the bars so as to ensure the sealing of the bars on the roll.

[0022] Figure 7a shows a single-piece toric-shaped grinding roll according to the invention. Figure 7b shows only the assembly of the corresponding perforated inserts, in which the inserts are mounted in a single ring in a contiguous manner and along a line. Petition 870250080762, dated 09 / 09 / 2025, p. 18 / 49 9 / 23 wavy.

[0023] Figure 8a shows a one-piece toric-shaped grinding roll according to the invention. Figure 8b shows only the assembly of the corresponding perforated inserts, in which the inserts are mounted in two overlapping rings in a staggered and contiguous manner along a wavy line.

[0024] Figure 9a shows a single-piece grinding roll of frustoconical shape according to the invention. Figure 9b shows only the assembly of the corresponding perforated inserts, in which the inserts are mounted in a single ring in a contiguous manner along a wavy line.

[0025] Figure 10 shows a single-piece frustoconical grinding roll according to the invention, which is similar to that in Figure 9a, a plurality of perforated ceramic inserts being arranged contiguously along a wavy line. However, two types of openings (cells) are shown with a differentiated perforation ratio adapted to the wear stress for a specific use. The perforated inserts show two zones 21 and 22. Zone 21, which is the most exposed to wear, has a limited degree of perforation with conical holes arranged in the part that is subject to the most wear stress, and a taper whose diameter changes from the inside of the roll to the outside surface of the roll decreasing. Zone 22, which is subject to the least wear stress, has a higher perforation ratio and is composed of cylindrical holes perpendicular to the grinding surface. The holes may also form an angle with the normal to the surface. Petition 870250080762, dated 09 / 09 / 2025, p. 19 / 49 10 / 23 peripheral.

[0026] Figure 11a shows a one-piece toric grinding roll according to the invention, a plurality of perforated ceramic inserts being arranged contiguously along a wavy line. Two types of openings with a differentiated perforation ratio adapted depending on a specific wear stress are also shown. In this case, the perforated inserts also show two zones 21 and 22. Figure 11b shows only the plurality of inserts assembled before casting the grinding roll. Note here that the sets of inserts are not only contiguous, but the elements have complementary shapes, allowing them to be perfectly assembled with their neighbors. An assembly according to a wavy shape was selected in order to avoid straight lines which constitute a preferred initiator and a preferred path for wear.Once this wear has begun, it continues to propagate very easily along a straight line, and wavy lines to a more or less pronounced extent help to slow down or even block this phenomenon. Furthermore, tests showed that a simple curved, low-amplitude, wave-free contiguous assembly line, while more prone to wear path propagation than a straight contiguous line, provided only an intermediate result between the straight line and the wavy contiguous line.

[0027] Figures 12 and 13 show other possibilities for assembling inserts according to the present invention. The inserts can be dedicated to zones 21 and 22 and form several overlapping rings with dimensions Petition 870250080762, dated 09 / 09 / 2025, p. 20 / 49 11 / 23 possibly different. When inserts are dedicated to zones 21 and 22 with high and low wear stress, respectively, the staggered arrangement is preferred in order to avoid as much as possible the propagation of wear along a continuous line. This figure also shows in detail significant differences in drilling between zones 21 and 22 with frustoconical holes 3 and cylindrical holes 4 as an example (detail not shown).

[0028] Figures 14a and 14b, respectively, show a large toric grinding roll once cast and a set of its corresponding inserts. Two distinct zones 21 and 22 adapted to different stresses are again distinguished there. The inserts are arranged according to two overlapping and staggered rings. The grinding roll can be slightly inclined on the rotary table, thus necessitating such a configuration.

[0029] Figures 15a and 15b, respectively, show a set of inserts for a toric grinding roll and the grinding roll once cast. In this case, it is a very large roll (18 tons and 3 m in diameter). Two distinct zones 21 and 22 adapted to different stresses are again distinguished there. The inserts are arranged according to three overlapping and staggered rings. The high-stress zones are arranged on either side of a zone with lower stress. This symmetrical arrangement makes it possible to use slightly inclined grinding rolls on the rotary table alternately on both sides. Once one side has worn down, the roll can be rotated.

[0030] Figure 16 shows a reinforcing insert with its length L and its width lea amplitude of Petition 870250080762, dated 09 / 09 / 2025, p. 21 / 49 12 / 23 waves A in their width, and how to measure them.

[0031] Figure 17 shows a staggered set of different inserts, in which it can be seen that the wave amplitude is not necessarily the same in the same assembly line. The amplitude is measured in terms of absolute value between a minimum and a maximum of the wave, A or A'“ in relation to the width l or a in relation to the length L or L'“ of the mounted inserts. The amplitudes A and a are evaluated respectively as a percentage in relation to the width l and the length L.

[0032] Figure 18 shows a method for measuring the wear profile of a toric grinding roll using rods for comparison with the surface of a new grinding roll.

[0033] Figure 19 shows a wear profile of a frustoconical grinding roll with a thicker arrow showing the position of maximum wear, which is a determining factor for roll replacement. List of reference symbols 1: One-piece grinding roller 2: Ceramic inserts 21: first zone of the ceramic inserts that is placed on the side most exposed to wear. 22: the second zone of the ceramic inserts, which is the least exposed to wear. 3: Example of frustoconical openings in ceramic inserts positioned on the most stressed face of the grinding roll. 4: Example of cylindrical openings in ceramic inserts positioned on the less stressed face of the grinding roller. Petition 870250080762, dated 09 / 09 / 2025, page 22 / 49 13 / 23 Detailed description of the invention

[0034] Cast wear components are common in the mining and cement industries for grinding rocks and ores. Among them are the tables of vertical compression mills and their grinding rolls in general, and the frustoconical and toric grinding rolls in particular that illustrate the present invention.

[0035] To increase the wear resistance of grinding rolls, ferrous alloys such as cast iron or steel are combined with the hardness of a ceramic material (such as carbides, nitrides, oxides of various types, etc.), which exhibit good wear resistance.

[0036] Combining these two types of material is not easy, however, because they have very different coefficients of expansion that can generate microcracks during the cooling of the components and cancel out, through potential defects, this synergy effect in a composite wear component.

[0037] Another difficulty lies in the problem of complete infiltration of the ceramic insert by the liquid molten iron, which tends to cool down upon contact with it, thus neutralizing satisfactory infiltration.

[0038] Numerous configurations of ceramic inserts have been tested by manufacturers. The most popular ceramic insert is a “honeycomb” shape that is relatively easy to infiltrate, such as those cited in the prior art WO98 / 15373.

[0039] Ceramic reinforcements are generally introduced in the form of bars, therefore in the form of an insert in which the interstices have already been infiltrated by Petition 870250080762, dated 09 / 09 / 2025, page 23 / 49 14 / 23 liquid cast iron, and cooled before being reintroduced into a mold to cast the wear part as a single block as desired. This technology is illustrated in figures 3 to 5 of this document and is the subject of publication WO2005 / 084809.

[0040] There is a great deal of skill involved in the production of a ceramic insert, as it must have a permeable structure to be infiltrated by molten iron, the level of permeability being a determining factor, and this has led to a series of technologies for the manufacture of powder agglomerates (aggregates) in the form of aggregate grains of a few millimeters which are then assembled into a cake / wafer structure in a mold and compacted by vibration. After leaving the mold, these inserts always exhibit irregular interstices on the order of 1 to 5 mm.

[0041] There are many possible compositions for the production of a ceramic insert that can be used in a reinforced grinding roller according to the invention. In a non-exhaustive list, the following can be mentioned, for example: - 10 / 90 to 90 / 10 alumina-zirconia, with or without yttria stabilization, in the form of millimeter-sized granules assembled into aggregates by means of an inorganic adhesive in a structure permeable to molten metal and therefore infiltrable by conventional casting; - particles resulting from ground or sintered metal-ceramic composites derived from mixtures of carbide, nitride, boride, or intermetallic powders, cemented in a metallic binder before being agglomerated into a permeable structure, and Petition 870250080762, dated 09 / 09 / 2025, page 24 / 49 15 / 23 therefore, infiltrable by a cast ferrous alloy; - Ceramics formed by self-propagating exothermic synthesis (SHS), such as, for example, titanium carbide from carbon and titanium powders, possibly mixed with a powder to moderate the reaction, such as, for example, iron powder, which may be in the form of millimeter-sized grains agglomerated with millimeter-sized interstices. The reaction between carbon and titanium is initiated by melting the ferrous alloy.

[0042] Holding the pellet in the mold during casting also requires a certain level of skill acquired by manufacturers over the years.

[0043] The configuration and positioning of ceramic inserts within a one-piece composite grinding roll has been the subject of much research which has always concluded that the results relating to wear rate obtained during testing are relatively unpredictable because they depend on the specific application, i.e. the type of machine used and the type of rocks to be ground.

[0044] The situation becomes even more complex due to the fact that, during the wear phenomenon, the geometry of the grinding roll changes and zones that are only slightly stressed at the beginning can become much more so as the wear advances. Therefore, it is often necessary to make a compromise on the insert structure, allowing for both short-term and long-term wear to be reconciled, these two notions possibly varying considerably from one specific case to another. Petition 870250080762, dated 09 / 09 / 2025, page 25 / 49 16 / 23

[0045] The inventors of the grinding roll according to the invention have now produced a reinforcing structure comprising a plurality of ceramic inserts that address this compromise. This reinforcing structure is adapted to the final shape of the roll and is, for example, of frustoconical or toric shape and comprises on its periphery a set of ceramic inserts that can be of different shapes, such as, for example, a side-by-side, therefore contiguous, set of inserts with approximately the same dimension as the grinding roll or an overlapping of two or more rings of ceramic inserts along wavy lines. The assembly in one or more rings largely depends on the final size of the roll, insofar as there is still a limit to the feasibility of an insert for reasons of handling by an operator (mass, volume, friability).Thus, a roller weighing one ton may require only one ring with a limited number of inserts to be mounted, whereas a roller weighing >15 tons will require at least 2 or 3 rings with several overlapping inserts. (See Figure 15b, for example).

[0046] Depending on the stresses for specific uses, it is possible to imagine a differentiated perforation depending on the position of the insert on the roll. For example, it is possible to imagine a different perforation ratio depending on whether the more stressed side, zone 21, or the less stressed side, zone 22, due to wear, is in question. An example of an assembly of an insert ring of this type for a toric grinding roll is shown in Figure 11a, and an example of two overlapping rings is shown in Figure 14a. Three overlapping insert rings are shown in Figure 15b. Petition 870250080762, dated 09 / 09 / 2025, page 26 / 49 17 / 23

[0047] To prevent wear from spreading along a predetermined line, overlapping inserts are preferably mounted in a staggered pattern.

[0048] Perforated ceramic structures generally have openings of any shape. The openings provided in the insert structure generally have a diameter between 1 and 10 cm, preferably between 1 and 8 cm, and particularly between 2 and 4 cm. When perforation is differentiated within the same grinding roll, the peripheral zone most exposed to wear 21, the holes preferably have a frustoconical shape 3 or are combined with blind holes. The most exposed zone may also include a skillful combination of blind holes and through holes. When blind holes are used, the blind side is placed on the side that is most stressed by wear. When frustoconical openings 3 are used, the opening will progressively narrow towards the outer surface most exposed to wear. In the less exposed and more perforated zone 22, the holes have any shape, but the cylindrical shape will be preferred. (See Figure 12).

[0049] Furthermore, the inventors observed that straight lines or even slightly curved lines constituted significant initiators for the wear of a grinding roller. Wear propagates much more rapidly in a straight line because it encounters no obstacle once it has started.

[0050] To mitigate this phenomenon, the inventors eliminated the spaces between the inserts, and the technological change in their manufacture now allows for better infiltration. The insert sets according to Petition 870250080762, dated 09 / 09 / 2025, page 27 / 49 18 / 23 The invention is therefore contiguous and formed along a wavy line, preventing the onset and propagation of wear in a straight line. All wave shapes are obviously conceivable, but for logistical reasons preference is given to components that have the same shape, having a concave-convex side allowing for perfectly contiguous complementary assembly.

[0051] The amplitude of the wave and how it is measured is shown in figures 16 and 17. In these figures, the amplitude of the waves is exaggerated for demonstration purposes. Examples

[0052] The tests were carried out on different rolls according to the invention in a vertical rotary mill of two different types suitable for the rolls to be tested. To neutralize the variable due to the influence of the ceramic composition on wear, the same ceramic was used for all tests. These are millimeter-sized grains of a titanium carbide-type metal-ceramic composite cemented in a manganese steel-type metallic binder. These grains, with an average size of about 5 mm, were compacted to form perforated inserts about 50 mm thick, which were used for all tests.

[0053] For the purposes of the test, the configurations of inserts distributed in several rings were carried out, considering that, in a roller weighing one ton, for example, several rings would not necessarily be necessary. The inventors, however, wanted to test the behavior of the rollers according to the invention when the inserts were configured in several overlapping rings with Petition 870250080762, dated 09 / 09 / 2025, page 28 / 49 19 / 23 a staggered positioning.

[0054] Each of the 2 frustoconical rollers was tested in parallel with a reference roller for 500 hours and the wear was extrapolated to 1000 hours. For each of the 3 toric roller tests, two rollers were arranged alternately with two reference rollers and were rotated for 1000 hours. The tests were performed continuously.

[0055] The test conditions are summarized in Table 1 below. Table 1 Ground Material Lignite-type coal Calcareous silica ore Mill Type Polysius RM25 / 12 (type 1) Loesche LM15.2 (type 2) Roller Type Toric Frustoconical Number of Rollers in the Mill 4 2 Roller Mass (T) External Size 1.4 130x33 cm 1 120 / 104x33 cm Flow Rate (T / h) 27-30 25 Test Duration 1000 hours 500 hours Roller Positioning 2 reference rollers and 2 rollers according to the invention alternating in the same mill 1 reference roller and one roller according to the invention in the same mill

[0056] Roller wear can be determined early on from profile measurements along the generators, using a gauge pressed against surfaces not subject to wear. The distance between the roller surface and the gauge is noted at several points along the gauge, representing a number of points on the roller contour. (See Figure 18). These measurements are then compared with the distances noted on a new roller. An average wear profile is determined. Petition 870250080762, dated 09 / 09 / 2025, page 29 / 49 20 / 23 providing information on wear geometry that can be exploited by the manufacturer.

[0057] The measurement of the wear selected for the comparison of the performance properties of the rolls is, however, the maximum wear depth on the roll, which is fundamental for its replacement. It is this maximum wear that will be used in the table below for the performance measurements. The grinding rolls produced with bars according to W02005 / 084809 and shown in figures 3, 4 and 5 are used as a comparative reference of frustoconical and toric rolls. These reference rolls are always combined with rolls according to the invention in the same mill during the test. In the latter, the wear is measured above the bars and not between the bars in the heavily worn ductile die. Tests on a type 1 mill with toric rollers Example 1 000o 'OOOO >0000 lõooo (oooo I 'OOOO oooo loooo 'oooo .oooo1IOOOOO oooo J0»00o 00 OOOO I < °oo OOOOO |ir* Z0000 / < POoAftftft0\oooo (< Iooo° / oo8E>, loooo I \ooooo —loooo / oooo oooo looooo oooo oooo IOOOOO ò õ oõ y> jooooo)2?,oo )oo°° Γ Λ oooo / oooo I \°00%A(^o4lÍ <0000 V^^^A^ooo^Dr* IOOOOO 'oooo .oooo 1 oo ooo 'oooo | oooo 1 loooo λΤοοοΥώοο^ «ΊοοηΉ / 0000 / 00 l0oo0 V^tKj A toric roller (as shown in figure 7a) perforated by 23 mm cells of the same shape in all inserts that are mounted in a single ring with junctions that describe a wave amplitude of 14% relative to width 1. Example 2 Petition 870250080762, dated 09 / 09 / 2025, page 30 / 49 21 / 23 A toric roller (as shown in Figure 11a) is differentially perforated by 13 and 23 mm cells in the inserts, which are mounted in a single ring with junctions that describe a wave amplitude of 12% relative to the width 1. Example 3 A toric roller (as shown in figure 14a) is differentially perforated by 13 and 23 mm cells in the inserts, which are mounted in two staggered rings with junctions that describe a wave with an amplitude (A) of 13% relative to the width 1 and an amplitude (a) of 12% relative to the length (L). Tests in a type 2 mill with frustoconical rollers Petition 870250080762, dated 09 / 09 / 2025, page 31 / 49 22 / 23 Example 4 Example 5 fl 'Pl / IL· J' - r ' A« · V ° ♦(· . ' · / ° % \ o OL—r __*--t 0 ° \ ° of 5 o M Oy^l7®cõ / Sooo( ooooooo ©©©©©©©( °°oXJ J of °°noooo \oooooee \ο®®©©©Θ \©®°Ooooc / ^ò3rxJ í ( %°°UnO \00° <?nOOO ) OOOOOO© ) ©©©®©Θο )®θΟο©ΟΟ ( °ΟΟο°°0 / / \\oO°B2??o ) °3?Soo / oooce©© / e©e©©©o / o°°°°oOo )θ°θοϊ°ο / ( / cO°Ar> no( OOOOOOOl ©®©θ©οβ( 1°O°OθO / °Oθη 0 Toronic roller (as shown in figure 12) perforated in a differentiated manner by 13 and 23 mm cells in the inserts which are mounted in two stepped rings with junctions that describe a wave amplitude (A) of 9% in relation to the width 1 and an amplitude of 5% in relation to the length (L) . Petition 870250080762, dated 09 / 09 / 2025, p. 32 / 49 23 / 23 Table 2 - Results Examples Number of rings Cells (mm) A / l 5- 0 a / L 9- 0 Wear mm / 1000h Improvement coefficient Reference 1 23 11 1.00 1 1 23 14 9.9 1.11 2 1 23 and 13 12 8.8 1.25 3 2* 23 and 13 13 12 9.2 1.19 Reference 23 37 1.00 4 1 23 and 13 4 29.1 1.27 5 2* 23 and 13 9 5 33.6 1.10 (*) the inserts are mounted in a staggered manner Interpretation of results

[0058] With regard to the reference toric and frustoconical grinding rolls produced with bars according to WO2005 / 084809, all grinding rolls according to the invention exhibit an improvement in wear performance. This improvement is between 10 and 27%, which is significant.

[0059] Rollers with differentiated perforation depending on wear stress with zones 21 and 22 (Examples 2 and 4 with 13 and 23 mm cells) exhibit better performance properties when the reinforcement insert consists of a single mounting ring with a minimum of joining lines.

[0060] Rollers composed of multiple overlapping staggered rings and differentiated perforation exhibit reduced performance due to the multiplication of the number of inserts and, therefore, of the joining lines that will be necessary for large grinding rollers.

[0061] Non-differentiated drilling, without specific zones 21 and 22, also allows for an 11% improvement in performance on the toric grinding roll. Petition 870250080762, dated 09 / 09 / 2025, pp. 33 / 49

Claims

1 / 4 CLAIMS 1. One-piece grinding roll, for vertical shaft mills, cast by casting a metal die, characterized in that said roll comprises on its periphery a perforated reinforcement structure (2) composed of a plurality of contiguously mounted ceramic inserts, the contiguous set of ceramic reinforcements being produced along wavy lines.

2. One-piece grinding roll, as claimed in claim 1, characterized in that said reinforcing structure (2) comprises at least a first zone (21), which is the least perforated and most exposed to wear, and at least a second zone (22), which is the most perforated and least exposed to wear.

3. Roller, as claimed in either of claims 1 or 2, characterized in that the first and second zones (21, 22) of the plurality of ceramic inserts are formed by several overlapping rings, said inserts being mounted in a staggered and contiguous manner along wavy lines.

4. Roller, according to any one of claims 1 to 3, characterized in that the perforation of the first zone (21), which is the most exposed to wear, is formed by through holes (3) of frustoconical shape with a diameter that progressively decreases towards the periphery of the roller or by a combination of through holes (4) of any shape with blind holes whose blind side is located on the peripheral side of the roller.

5. Roller, according to any of claims 1 to 4, characterized in that the perforation of the second Petition 870250080762, dated 09 / 09 / 2025, p. 34 / 49 2 / 4 zone (22), which is the least exposed to wear, is formed by through holes (4) of any shape, preferably cylindrical shape, positioned perpendicularly or inclined in relation to the peripheral surface of the roller.

6. A roller, according to any one of claims 1 to 5, characterized in that the plurality of inserts is assembled so as to form a frustoconical roller or a toric roller.

7. Roller, according to any one of claims 1 to 6, characterized in that the amplitude (a) of the wavy lines represents between 2 and 20%, preferably between 5 and 15%, in relation to the length L of the ceramic insert.

8. Roller, according to any one of claims 1 to 7, characterized in that the amplitude (A) of the wavy lines represents between 2 and 20%, preferably between 3 and 15%, in relation to the width l of the ceramic insert.

9. Roller, according to any one of claims 1 to 8, characterized in that the ceramic composition of the reinforcing structure is selected from oxides, carbides, nitrides and borides.

10. Roller, according to any one of claims 1 to 9, characterized in that the ceramic inserts comprise an aggregate of ceramic-metallic composite grains in which micrometric ceramic particles are cemented into a metallic binder, the composite grains having an average D50 size of 2 to 8 mm, preferably 3 to 6 mm, determined by sieving.

11. Roller, according to claim 11, characterized in Petition 870250080762, dated 09 / 09 / 2025, p. 35 / 49 3 / 4 by the fact that said grains comprise medium-sized titanium carbide D50 between 3 and 20 μm, preferably between 5 and 15 μm, cemented onto a metal binder.

12. Roller, according to any one of claims 1 to 11, characterized in that the ceramic composition of the reinforcing structure of the first zone (21) is different from the ceramic composition of the second zone (22).

13. Method for producing a grinding roll, according to any one of claims 1 to 12, characterized in that it comprises the following steps: - providing a mold for the production of a one-piece grinding roll by casting a ferrous alloy; - positioning a reinforcing structure composed of a plurality of ceramic inserts mounted contiguously along wavy lines, the inserts being in the form of perforated aggregates of millimeter-sized granules, the perforated aggregates being permeable and therefore infiltrable by a cast ferrous alloy; - infiltration of the insert by the liquid ferrous alloy; - cooling and demolding of the grinding roll.

14. Method according to claim 13, characterized in that the ferrous alloy comprises steel or cast iron.

15. Method, according to any one of claims 13 and 14, characterized in that the reinforcing structure comprises at least a first zone (21) which is the least perforated and most exposed to wear and at least a second zone (22) which is the most perforated and least exposed to wear. Petition 870250080762, dated 09 / 09 / 2025, p. 36 / 49 4 / 4 16. Method, according to any one of claims 13 to 15, characterized in that the infiltrated aggregates of millimeter-sized ceramic granules used for the grinding roll inserts are selected from the following compositions: - alumina-zirconia in proportions of 90 / 10 to 10 / 90, the zirconia possibly being stabilized with yttria; - carbon powder and titanium, optionally comprising iron powder as a moderator and precursors of a self-propagating thermal synthesis (SHS) reaction initiated by melting the ferrous alloy; - ceramic-metallic composites of titanium carbide cemented in a metal binder. Petition 870250080762, dated 09 / 09 / 2025, pp. 37 / 49

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