Silicon-ceramic inserts in grinding wear parts

Abstract

The invention relates to a wear part (1) for a mill, in particular a grinding roller or a grinding plate. The wear part (1) comprises a metal casting material (2) and at least one porous ceramic insert (3). The at least one porous ceramic insert (3) is embedded in the metal casting material (2) and infiltrated thereby. The at least one porous ceramic insert (3) has at least one conical or tapering recess (6). The invention also relates to a mill, to a method for producing a wear part (1) of a mill, and to the use of ceramic inserts (3) in a wear part (1) of a mill, which ceramic inserts have been cast in a metal casting material (2).

Description

[0001] Silicon ceramic inserts in grinding wear parts

[0002] The present invention relates to a wear part for a mill, a mill, a method for producing a wear part of a mill and the use of ceramic inserts cast in a metal casting material in a wear part of a mill.

[0003] Wear parts of a mill, such as a grinding roller or a grinding divider, are often exposed to severe abrasive stress and can therefore wear out quickly. The maintenance and replacement of these wear parts can represent a significant economic factor. On the one hand, the mill cannot be operated during this time, and on the other hand, the replacement itself can be associated with high costs.

[0004] Various methods for improving wear resistance are known in the prior art. For example, EP3366389B1 teaches the incorporation of hard ceramic particles in a cast iron-based alloy. CN103111347A teaches the use of ceramic pins embedded in a steel base. DE112009003706T5 describes the use of wear plates made of hard metal or ceramic that are welded to a metal base body. EP0476496B1 teaches the arrangement of rib-shaped wear inserts made of cast chromium in a metal matrix. EP2809466B1 discloses a porous filler material infiltrated with a ductile steel matrix material. DE102008032271A1 teaches the use of honeycomb-shaped hard material bodies infiltrated with a cast material.

[0005] Due to the high and cyclical forces during the grinding process, the bond between the wear inserts and the matrix material is subjected to significant stress. A poor bond between the wear inserts and the metal matrix negatively impacts the durability of the wear parts.

[0006] One object of the present invention is to improve the wear resistance and durability of milling wear parts. Another object of the present invention is to ensure simple and reliable production of the milling wear parts.

[0007] According to a first aspect of the invention, a wear part for a mill comprises at least one porous ceramic insert and a metal casting material. The at least one porous ceramic insert is embedded in the metal casting material and infiltrated by it. The at least one porous ceramic insert has at least one recess. The at least one porous ceramic insert can comprise silicon ceramic.

[0008] The wear part can be a grinding roller or a grinding plate. The grinding roller can have a radius of 90 millimeters to 1500 millimeters, preferably 250 millimeters to 1250 millimeters. The radius of the grinding roller is defined in particular as the radial distance from the rotational axis of the grinding roller to the working surface of the grinding roller. The grinding plate can have a radius of 200 millimeters to 3600 millimeters, preferably 500 millimeters to 3350 millimeters. The radius of the grinding plate is defined in particular as the radial distance from the center of the grinding plate to an outer edge of the grinding plate.

[0009] The porous ceramic insert can also be referred to as a preform. The porous ceramic insert can comprise a multitude of particles. The particles are also referred to as grains. The particles can have a size between 1 millimeter and 7 millimeters, preferably between 1.5 millimeters and 4 millimeters, preferably between 2 millimeters and 3 millimeters. Particle sizes that are too large can lead to unstable ceramic inserts. Particle sizes that are too small can cause infiltration problems. Smaller particle sizes can have a positive influence on wear resistance. The above-mentioned particle sizes represent advantageous designs, taking into account the advantages and disadvantages.

[0010] With a particle size of 2 millimeters to 3 millimeters, the ceramic insert can have a porosity of 50 to 70 percent by volume, preferably essentially 60 percent.

[0011] The at least one ceramic insert can have an upper base surface and a lower base surface. The upper base surface can be arranged on a surface of the wear part. The lower base surface can be arranged inside the wear part.

[0012] During use, the upper base surface can face the material to be ground. The upper base surface can face away from the center of gravity of the wearing part. The wearing part can be a grinding roller. The at least one ceramic insert of the grinding roller can be arranged such that the upper base surface faces away from the center of gravity of the grinding roller. The lower base surface can face the center of gravity of the grinding roller. The upper base surface can be arranged on the grinding surface of the grinding roller. The wearing part can be a grinding plate. The upper base surface of the at least one ceramic insert can be arranged on the upper side of the grinding plate. The upper side of the grinding plate can be in contact with the material to be ground when the grinding plate is used as intended. During use, the upper base surface of the at least one ceramic insert can be in contact with the material to be ground.The at least one ceramic insert can be arranged in an edge region of the wearing part.

[0013] The wear part can have a gradual transition between the at least one porous ceramic insert and the metal casting material. The gradual transition can be formed by chemisorption between the material of the ceramic insert and the metal casting material. The wear part can be formed without a separate binding phase between the at least one porous ceramic insert and the metal casting material.

[0014] The wear part can have at least one transition region between the at least one porous ceramic insert and the metal casting material. The transition region can be formed by chemisorption between the material of the ceramic insert and the metal casting material. The transition region can be formed without the separate addition of a binder. The transition region can consist of a mixture of the material of the ceramic insert and the metal casting material and, in particular, can have no additional binders or binding phases. The transition region can be formed by chemisorption between silicon carbide and nickel chilled cast iron. The transition region is, in particular, free of lamellar or flake-shaped carbon deposits. Lamellar or flake-shaped carbon deposits can negatively influence the wear behavior of the wear part.

[0015] The at least one recess can extend between two opposing surfaces of the ceramic insert. The at least one recess can extend between the lower base surface and the upper base surface of the ceramic insert, in particular in the axial direction of the ceramic insert.

[0016] The at least one recess can optionally have a tapered shape. The at least one recess can taper towards the upper base surface. The tapered recess can achieve better embedding of the ceramic insert in the metal casting material. The tapered recess can enable better infiltration of the ceramic insert with the metal casting material.

[0017] The at least one ceramic insert can extend in the axial direction between the lower base surface and the upper base surface. The at least one ceramic insert can be plate- or disc-shaped. This means that the at least one ceramic insert extends substantially in directions orthogonal to the axial direction. The extension of the ceramic insert in the axial direction can be relatively small compared to the extension of the ceramic insert in directions orthogonal to the axial direction.

[0018] The extension of the at least one ceramic insert in directions orthogonal to the axial direction can be greater than the extension of the at least one ceramic insert in the axial direction. The at least one ceramic insert can have a thickness. The thickness can be defined as the distance between the upper base surface and the lower base surface. The thickness can be defined as the extension of the ceramic insert in the axial direction. The at least one ceramic insert can have a width and a length. The width can be defined as the extension of the ceramic insert in a first direction orthogonal to the axial direction. The length can be defined as the extension of the ceramic insert along a second direction orthogonal to the axial direction. The first direction can be arranged orthogonal to the second direction.

[0019] The width of the ceramic insert can be between 50 millimeters and 200 millimeters, preferably between 80 millimeters and 160 millimeters, preferably between 110 millimeters and 130 millimeters. The length of the ceramic insert can be between 60 millimeters and 250 millimeters, preferably between 110 millimeters and 200 millimeters, preferably between 140 millimeters and 160 millimeters.

[0020] The at least one recess may have a lower diameter and an upper diameter. The lower diameter may be at least 10 percent, preferably at least 20 percent, preferably at least 30 percent larger than the upper diameter. The upper diameter may define the diameter of the recess in the upper base surface. The lower diameter may define the diameter of the recess in the lower base surface.

[0021] The at least one recess can optionally be conical. The at least one recess can be truncated cone-shaped. The at least one recess can be truncated pyramid-shaped. The conical, truncated cone-shaped, or truncated pyramid-shaped shape of the recess can improve the infiltration of the ceramic insert by the metal casting material and, in particular, thereby improve the wear behavior of the wearing part. The conical, truncated cone-shaped, or truncated pyramid-shaped shape of the recess can promote or improve infiltration of the metal casting material into the pores of the ceramic insert. A conical shape can lead to a flow advantage when pouring in the metal casting matrix. A conical shape of the recesses can also be advantageous during production of the ceramic insert. In particular, placeholder elements are introduced into the casting mold during casting of the ceramic insert.The spacer elements can be removed after the casting process and represent the recesses in the ceramic inlay. Conical spacer elements can have a positive effect on the removal of the spacer elements from the ceramic inlay.

[0022] The at least one recess may have a taper angle. The taper angle may be defined as the inclination of a side wall of the recess relative to the axial direction. The taper angle of the recess may be 5 degrees, preferably 10 degrees, preferably 15 degrees.

[0023] The at least one recess can extend from the lower base surface of the ceramic insert to the upper base surface of the ceramic insert. The at least one recess defines a lower opening in the ceramic insert in the lower base surface and an upper opening in the ceramic insert in the upper base surface. The lower opening can be larger than the upper opening. The area of ​​the lower opening can be larger than the area of ​​the upper opening. The diameter of the lower opening can be larger than the diameter of the upper opening. The lower opening can be at least 10 percent, preferably at least 20 percent, preferably at least 30 percent larger than the upper opening. The size specifications can refer to the diameter or the area of ​​the openings.

[0024] The at least one recess can have a diameter of 3 millimeters to 25

[0025] millimeters, preferably 5 millimeters to 20 millimeters, preferably 8 millimeters to 15

[0026] millimeters. The diameter of the lower opening can be 3 millimeters to 25

[0027] millimeters, preferably 5 millimeters to 20 millimeters, preferably 8 millimeters to 15

[0028] millimeters. The diameter of the upper opening can be 3 millimeters to 25 millimeters, preferably 5 millimeters to 20 millimeters, preferably 8 millimeters to 15 millimeters.

[0029] For example, the diameter of the lower opening can be 10 millimeters and the diameter of the upper opening 8 millimeters. The diameter of the lower opening can also be the same as the diameter of the upper opening.

[0030] The ceramic insert can have at least two recesses. The distance between two adjacent recesses can be between 10 millimeters and 50 millimeters, preferably between 15 millimeters and 40 millimeters, preferably between 20 millimeters and 30 or 35 millimeters. The distance between two adjacent recesses can be defined as the distance between the center axes of the two recesses.

[0031] The at least one recess can be arranged at least 5 millimeters, preferably at least 10 millimeters, preferably at least 15 millimeters from the edge of the ceramic insert.

[0032] The ceramic insert can have a thickness of 5 millimeters to 150 millimeters, preferably 5 millimeters to 80 millimeters, preferably 10 millimeters to 50 millimeters, preferably 15 millimeters to 40 millimeters. For example, the ceramic insert can have a thickness of 35 millimeters.

[0033] The wearing part has a wearing part thickness. The wearing part thickness is defined in particular as the extension of the wearing part in a direction orthogonal to the working surface of the wearing part. In the case of a grinding plate, the wearing part thickness corresponds in particular to the grinding plate thickness. Grinding rollers can be hollow or have a cavity in the center or around the axis of rotation. In the case of a grinding roller, the wearing part thickness is defined in particular as the extension of a radially outer region of the grinding roller in the radial direction of the grinding roller. In particular, the wearing part thickness of the grinding roller is the extension of the grinding roller in the radial direction from the working surface to the cavity formed around the center of the grinding roller.

[0034] The thickness of the ceramic insert can be between 15 percent and 50 percent, preferably between 20 percent and 35 percent, of the wear part thickness. The wear part thickness can be between 30 millimeters and 300 millimeters, in particular between 50 millimeters and 200 millimeters.

[0035] The thickness of the ceramic insert can be between 0.3 percent and 15 percent, preferably between 1 percent and 10 percent of the radius of the wear part, in particular the radius of the grinding roller.

[0036] The ratio between the distance between two adjacent recesses and the diameter of the recesses, in particular the diameter of the upper opening of the recesses, can be 0.5 to 10, preferably 1 to 8, preferably 2 to 5. The distance between two adjacent recesses can be defined as the shortest distance between the edges of the two recesses, in particular between the edges of the upper openings of the recesses.

[0037] The ceramic insert may have a plurality of recesses. The plurality of recesses may each extend from the lower base surface of the ceramic insert to the upper base surface of the ceramic insert. The recesses in the upper base surface may amount to between 5 percent and 30 percent, preferably between 8 percent and 20 percent, preferably between 10 percent and 15 percent of the total upper base surface.

[0038] The geometric specifications described above, such as diameter or ratio of the openings to the total base area, can have a positive effect on the wear behavior, in particular the wear resistance of the wearing part. The geometric specifications described above can also have a positive effect on the bond between the ceramic insert and the metal casting material. A large recess, in particular a recess with a large diameter, can have a positive effect on the bond between the ceramic insert and the metal casting material. However, a recess that is too large can have a negative effect on the wear behavior, in particular the wear resistance of the wearing part. A small recess, in particular a small diameter of the recess, can have a positive effect on the wear behavior, in particular the wear resistance of the wearing part.A recess that is too small, especially a recess diameter that is too small, can have a negative effect on the bond between the ceramic insert and the metal casting material.

[0039] The recesses can be arranged in a plurality of rows. The individual rows can be offset from one another, in particular offset with respect to a first direction. Adjacent rows can each be offset from one another, in particular offset with respect to a first direction. The recesses can be arranged in a regular pattern in the ceramic insert. The offset between two adjacent rows, in particular in a first direction, can be half the distance, in particular in a first direction, between the center axes of two adjacent recesses within a row. The center axis of a recess can run between the center point of the upper opening in the ceramic insert and the center point of the lower opening of the ceramic insert, in particular in the axial direction.The offset between two rows can be defined as the distance, in particular along the first direction, between the center axis of a recess in the first row to the center axis of a recess in the second row.

[0040] The distance, in particular in a first direction, between two adjacent recesses within a row can be referred to as the first distance and can be substantially equal to twice the offset between two adjacent rows. A second row of recesses can be arranged offset by a first distance, in particular in a first direction, from a first row of recesses. A third row of recesses can be arranged offset by the first distance, in particular in a first direction, from the second row of recesses. The first row of recesses can be aligned with the second row of recesses, in particular with respect to the first direction. The distances between two adjacent recesses within a row, in particular along a first direction, can be identical within the row.The distances between two adjacent recesses within a row, in particular along a first direction, may be identical within the entire ceramic insert.

[0041] Adjacent rows of recesses can be arranged at a second distance from each other, in particular along a second direction. The second direction can be orthogonal to the first direction. The second distance can correspond to the offset between two adjacent rows. The second distance can be defined as the distance between the center axes of recesses of two adjacent rows, in particular along the second direction.

[0042] For example, the distance, in particular the distance along a first direction, between two adjacent recesses, in particular between the center axes of two adjacent recesses, can be 25 millimeters to 35 millimeters, preferably 30 millimeters. The offset between a first row of recesses and a second row of recesses, in particular in the first direction, can be 10 millimeters to 20 millimeters, preferably 15 millimeters. The diameter of the recesses, in particular of the lower opening, can be 9 millimeters to 11 millimeters, preferably 10 millimeters. The diameter of the recesses, in particular of the upper opening, can be 7 millimeters to 9 millimeters, preferably 8 millimeters. The distance between two adjacent rows, in particular along the second direction, can be 10 millimeters to 20 millimeters, preferably 15 millimeters. The ceramic insert can have 9 rows of recesses.Each row can have between 3 and 4 recesses. The number of recesses within a row can vary from row to row. For example, a first row can have 4 recesses. A second row can have 3 recesses. A third row can have 4 recesses again, and so on. The diameter of the lower openings in the ceramic inserts can be 10 millimeters. The diameter of the upper openings in the ceramic inserts can be 8 millimeters.

[0043] The ceramic insert can be flat, in particular plate-shaped.

[0044] The ceramic insert can be curved. The at least one recess can extend in the radial direction of the ceramic insert. The axial direction of the ceramic insert or of the recess can be arranged parallel to the radial direction of the ceramic insert. The lower base surface of the ceramic insert can represent a radially inner surface of the ceramic insert. The upper base surface of the ceramic insert can represent a radially outer surface of the ceramic insert.

[0045] The ceramic insert, particularly the upper base surface, can have a radius of 90 millimeters to 1500 millimeters, preferably 250 millimeters to 1250 millimeters. The ceramic insert can represent an arc segment of the wear part.

[0046] The wear part can be arcuate. The ceramic insert can be arranged on a radially outer side of the wear part. The upper base surface of the ceramic insert can be arranged on a radially outer side of the wear part. The upper base surface of the ceramic insert can be arranged in a surface of the wear part. The upper base surface of the ceramic insert can be arranged inside the wear part. The lower base surface of the ceramic insert can be arranged on a radially inner side of the wear part.

[0047] The wear part can have a working surface that, during the intended use of the wear part, faces a grinding material. The working surface can be a grinding surface of a grinding roller or a grinding plate. The working surface can be designed to act on the grinding material, particularly in cooperation with another wear part. The ceramic insert, in particular the upper base surface of the ceramic insert, can form part of the working surface. The ceramic insert can be positioned such that the upper opening is arranged in the working surface.

[0048] The ceramic insert or several ceramic inserts can form at least 50 percent, preferably at least 75 percent, preferably at least 90 percent of the working surface.

[0049] The ceramic insert can consist essentially of silicon ceramic. The ceramic insert can comprise a silicon-carbon compound, in particular silicon carbide. The ceramic insert can comprise a silicon-carbon compound, in particular silicon carbide. The ceramic insert can comprise a silicon-nitrogen compound, in particular silicon nitride. The ceramic insert can comprise a silicon-nitrogen compound, in particular silicon nitride.

[0050] The ceramic insert may comprise at least 70 mass percent, preferably 80 mass percent, preferably 90 mass percent, of silicon carbide or silicon nitride. In a preferred embodiment, the ceramic insert comprises at least 90 mass percent silicon carbide.

[0051] The metal casting material may comprise, in particular consist of, nickel chill casting. The metal casting material may comprise high-alloy, wear-resistant cast iron. The metal casting material may comprise nickel chill casting. The metal casting material may consist essentially of high-alloy, wear-resistant cast iron. The metal casting material may consist essentially of nickel chill casting.

[0052] The metal casting material can consist of white-set cast iron. The nickel-hard cast iron can be Ni-Hard, especially Ni-Hard IV. The metal casting material can contain 8 to 10 mass percent chromium. The metal casting material can contain 4 to 6.5 mass percent nickel. The metal casting material can contain 1.5 to 2.5 mass percent silicon. The metal casting material can essentially contain 9 mass percent chromium, 5 mass percent nickel, and 2 mass percent silicon.

[0053] The wear part can have multiple ceramic inserts. The wear part can have between 10 and 80 ceramic inserts, preferably between 20 and 70 ceramic inserts, preferably between 30 and 60 ceramic inserts. The ceramic inserts can be identical.

[0054] Joints may be arranged between the individual ceramic inserts. These joints may be filled with cast metal material.

[0055] The at least one ceramic insert can have a combination of conical and cylindrical recesses.

[0056] According to one embodiment of the invention, the at least one ceramic insert consists essentially of silicon carbide. The metal casting material consists essentially of nickel chill cast iron, in particular Ni-Hard. The at least one ceramic insert has a plurality of recesses, in particular 30 to 35 recesses. The recesses have a conical shape, in particular a truncated cone shape. The recesses define upper openings in the upper base area with a diameter of 8 millimeters. The recesses define lower openings in the lower base area with a diameter of 10 millimeters. The ceramic insert can have a thickness of 5 millimeters to 80 millimeters, in particular 30 millimeters to 40 millimeters. The plural and singular of the ceramic inserts are used largely synonymously in the above and following description.The use of the term "ceramic insert" therefore does not imply that the features described in this context are limited to a single ceramic insert. When features are described with reference to a single ceramic insert, the skilled person understands that the remaining ceramic inserts may be of the same design.

[0057] According to a second aspect of the invention, a mill comprises a wear part according to the first aspect of the invention. The mill may have a grinding plate. The grinding plate may be a wear part according to the first aspect of the invention. The mill may have one or more grinding rollers. The one or more grinding rollers may be wear parts according to the first aspect of the invention.

[0058] According to a third aspect of the invention, a method for producing a wear part of a mill comprises providing a casting mold for the wear part, arranging at least one porous ceramic insert in the casting mold, and pouring a metal casting material into the casting mold. The metal casting material flows through one or more recesses in the ceramic insert, in particular into pores of the ceramic insert. The at least one porous ceramic insert can comprise silicon ceramic.

[0059] The one or more recesses may have a tapered or conical shape. The one or more recesses may have a truncated cone or truncated pyramid shape. Such a shape of the recesses can simplify the pouring of the metal casting material into the ceramic insert, in particular, it can promote the infiltration of the metal casting material into the pores of the ceramic insert.

[0060] The at least one ceramic insert can be designed as described in the first aspect of the invention. The at least one ceramic insert can consist essentially of a silicon-nitrogen compound, in particular silicon nitride. The at least one ceramic insert can consist essentially of a silicon-carbon compound, in particular silicon carbide.

[0061] The metal casting material may comprise, in particular consist of, nickel chill casting.

[0062] The one or more recesses may extend from a lower base surface of the ceramic insert to an upper base surface of the ceramic insert.

[0063] The one or more recesses may be cylindrical or prism-shaped. The one or more recesses may be truncated cone-shaped. The one or more recesses may be truncated pyramid-shaped.

[0064] Each of the recesses can define a lower opening and an upper opening in the ceramic insert. The lower openings of the recesses can be arranged in the lower base surface. The upper openings of the recesses can be arranged in the upper base surface of the ceramic insert. The lower openings can be larger than the upper openings. The metal casting material can be poured into the at least one ceramic insert through the lower openings.

[0065] Providing the casting mold may comprise producing a hybrid casting mold. The hybrid casting mold may comprise a first component and a second component. The first component may comprise, in particular, water glass-bonded sand. The second component may comprise, in particular, furan resin-bonded sand.

[0066] The second component can be arranged in an outer region of the casting mold. The first component can be arranged in an inner region of the casting mold. During the casting of the metal casting material, the first component can come into contact with the metal casting material. The first component can determine the shape of the wear part.

[0067] The at least one ceramic insert can be positioned in the casting mold, in particular on the first component, by means of a grid. The at least one ceramic insert can be fastened to the casting mold, in particular to the first component, by means of a fastening means. The fastening means can be arranged in one of the recesses. Two fastening means can be provided for each ceramic insert. The at least one ceramic insert can be fastened to the casting mold, in particular to the first component, by means of a screw and / or clamp. A dowel can be arranged in the casting mold, in particular to the first component. The at least one ceramic insert can be fastened to the dowel in the casting mold, in particular to the first component, by means of a fastening means, in particular a screw and / or a clamp.A spacer, particularly in the form of a washer or flat washer, can be placed between the edge of the casting mold and the ceramic insert. The spacer is arranged, in particular, between a side wall of the casting mold and the ceramic insert. This ensures, in particular, that the metal casting material also penetrates into the space between the side wall of the casting mold and the ceramic insert, which can lead to better embedding of the ceramic insert in the metal casting material. A washer can be arranged between the nut of the screw and the ceramic insert. A washer can be arranged between the ceramic insert and the casting mold.

[0068] The spacer can be formed as part of the ceramic insert. The ceramic insert can have spacers, in particular in the form of spacer cams or spacer studs. The spacers, in particular the spacer cams or spacer studs, are arranged in particular on the upper base surface of the ceramic insert or extend from the upper base surface of the ceramic insert. The ceramic insert can have three, four, or more spacers, in particular spacer cams or spacer studs. The spacers are arranged in particular between a side wall of the basic shape and the upper base surface of the ceramic insert, thereby creating a distance between the side wall of the basic shape and the upper base surface of the ceramic insert.

[0069] The method may further comprise preheating the mold prior to pouring the metal casting material into the mold.

[0070] The method may comprise providing a second casting mold, in particular a plurality of second casting molds. The method may comprise casting the at least one ceramic insert in the second casting mold, in particular the plurality of second casting molds. Casting the at least one ceramic insert may precede arranging the at least one ceramic insert in the casting mold.

[0071] The method may further comprise forming at least one green compact, in particular made of silicon nitride or silicon carbide. The method may further comprise sintering the green compact to form at least one ceramic insert.

[0072] The bond between the ceramic insert and the metal casting material can be achieved by chemisorption between the material of the ceramic insert and the metal casting material. The bond between the ceramic insert and the metal casting material can be achieved without the addition of an additional binding phase or binder. A transition region can be formed between the ceramic insert and the metal casting material. The transition region can be formed by chemisorption between the material of the ceramic insert and the metal casting material. The transition region can be formed without the separate addition of a binder. The transition region can consist of a mixture of the material of the ceramic insert and the metal casting material and, in particular, can have no additional binders or binder phases. The transition region can be formed by chemisorption between silicon carbide and nickel chilled casting.The transition area can represent a gradual transition between the material of the ceramic insert and the metal casting material.

[0073] Pouring the metal casting material into the casting mold, in particular into one or more recesses of the ceramic insert, may involve melting or dissolving edge regions of the ceramic insert, thereby forming, in particular, a gradual transition between the ceramic insert and the metal casting material. The gradual transition may be formed by chemisorption between the material of the ceramic insert and the metal casting material.

[0074] A fourth aspect of the invention comprises the use of ceramic inserts cast into a metal casting material in a wear part of a mill. The ceramic inserts have cylindrical, prism-shaped, truncated cone-shaped, or truncated pyramid-shaped recesses. In a preferred embodiment, the ceramic inserts have conical or tapered recesses. The wear part can be a grinding roller or a grinding plate. The ceramic inserts can be designed as described in the first aspect of the invention. The metal casting material can be designed as described in the first aspect of the invention.

[0075] The following statements relate to the first aspect, the second aspect, the third aspect and the fourth aspect of the invention.

[0076] The ceramic insert(s) may be porous. The ceramic insert(s) may contain pores.

[0077] The ceramic insert(s) may have a pore content of more than 20 volume percent, preferably more than 35 volume percent, preferably more than 50 volume percent. The ceramic insert(s) may have a solids content of 25 volume percent to 80 volume percent, preferably 40 volume percent to 70 volume percent, preferably 55 volume percent to 65 volume percent.

[0078] The ceramic insert or the ceramic inserts can essentially have a pore content of 20 volume percent to 80 volume percent, preferably 25 volume percent to 75 volume percent, preferably 30 volume percent to 70 volume percent, preferably 35 volume percent to 45 volume percent.

[0079] The base material, in particular the solid, of the ceramic insert(s) may have a density of 2 grams per cubic centimeter (g / cm 3 ) to 4 grams per cubic centimeter, preferably 2.5 grams per cubic centimeter to 3.5 grams per cubic centimeter, preferably 3.1 grams per cubic centimeter to 3.3 grams per cubic centimeter. The pores of the ceramic insert(s) are not included in the above-mentioned densities.

[0080] The ceramic insert(s) may consist essentially of silicon ceramic. The ceramic insert(s) may comprise a silicon-carbon compound, in particular silicon carbide. The ceramic insert(s) may comprise a silicon-carbon compound, in particular silicon carbide. The ceramic insert(s) may comprise a silicon-nitrogen compound, in particular silicon nitride. The ceramic insert(s) may comprise a silicon-nitrogen compound, in particular silicon nitride.

[0081] The ceramic insert(s) may comprise at least 70 mass percent, preferably 80 mass percent, preferably 90 mass percent, of silicon carbide or silicon nitride. The ceramic insert(s) may comprise at least 70 mass percent, preferably 80 mass percent, preferably 90 mass percent, of silicon carbide or silicon nitride. The ceramic insert(s) may comprise at least 90 mass percent of silicon carbide.

[0082] The metal casting material may comprise high-alloy, wear-resistant cast iron. The metal casting material may comprise nickel-chilled cast iron. The metal casting material may consist essentially of high-alloy, wear-resistant cast iron. The metal casting material may consist essentially of nickel-chilled cast iron.

[0083] The metal casting material can consist of white-setting cast iron. The nickel chill casting can be Ni-Hard, in particular Ni-Hard IV. The metal casting material can contain 8 mass percent to 10 mass percent chromium. The metal casting material can contain 4 mass percent to 6 mass percent nickel. The metal casting material can contain 1 mass percent to 2.5 mass percent silicon. Preferably, the metal casting material has a silicon content of less than 1.5 mass percent, in particular less than 1.45 mass percent, preferably between 1 and 1.45 mass percent. Such a silicon content can reduce or prevent the formation of carbon precipitates, in particular lamellar or lamellar carbon precipitates.

[0084] The metal casting material can essentially contain 9 mass percent chromium, 5 mass percent nickel and between 1 and 1.45 mass percent silicon.

[0085] The metal casting material, in particular nickel chill casting, can have a carbon content of less than 3.5 mass percent, preferably less than 2.5 mass percent. The metal casting material preferably has a carbon content between 1.5 mass percent and 2.5 mass percent, preferably between 2 mass percent and 2.45 mass percent. Such a carbon content can reduce or prevent the formation of carbon precipitates, in particular carbon-shaped carbon precipitates. Alternatively, the metal casting material, in particular nickel chill casting, can have a carbon content between 3 mass percent and 5 mass percent, preferably between 3.5 mass percent and 4 mass percent.This leads to a uniform distribution of carbon deposits in the wear part, resulting in improved wear behavior compared to only local carbon deposits in the transition area between the ceramic insert and the metal casting material.

[0086] The particles of the ceramic insert can be coated with a glaze. The glaze can comprise, in particular consist of, aluminum oxide (Al2O3). The glaze can comprise water glass, in particular soda water glass. The glaze can reduce or prevent the formation of carbon precipitates, in particular lamellar carbon precipitates. Alternatively, the particles of the ceramic insert can be formed without a glaze. This creates, in particular, a transition region between the ceramic insert and the metal casting material that is free of an additional binding phase or an additional binder.

[0087] The wear part or the first casting mold can be actively heated after the casting process, particularly to extend the cooling phase. This extended cooling phase can reduce or prevent the formation of carbon precipitates, particularly lamellar or lamellar carbon precipitates. In particular, the existing carbon can be consumed during carbide formation through a longer cooling phase.

[0088] The wear part can be subjected to heat treatment. The ceramic insert can be subjected to heat treatment before and / or after encapsulation with the metal casting material.

[0089] The at least one recess can extend between two opposite surfaces of the ceramic insert, in particular the upper base surface and the lower base surface. The recesses can extend between two opposite surfaces of the ceramic insert, in particular the upper base surface and the lower base surface. The at least one recess can extend over the entire thickness of the ceramic insert. The recesses can extend over the entire thickness of the ceramic insert.

[0090] In the context of the present application, the terms “embed” and / or “surround” may in particular mean direct contact between the two materials, in particular the ceramic insert and the metal casting material.

[0091] In the context of the present application, the terms "embed" and / or "surround" can, in particular, refer to indirect contact between the two materials, in particular the ceramic insert and the metal casting material. For example, an intermediate layer can be present at least in some areas between the metal casting material and the ceramic insert.

[0092] The wear part according to the first aspect of the invention can be manufactured using method steps of the method according to the third aspect of the invention. The mill according to the second aspect of the invention can comprise one or more wear parts according to the first aspect of the invention. The method according to the third aspect of the invention can be used to produce a wear part according to the first aspect of the invention. The components described in the method, in particular the ceramic inserts and / or the metal casting material, can be designed as described in the context of the first aspect of the invention.

[0093] The use according to the fourth aspect of the invention may comprise the method or method steps according to the third aspect of the invention. The use according to the fourth aspect of the invention may be carried out with a wear part according to the first aspect of the invention.

[0094] As used in the description of the various described embodiments and the appended claims, the singular forms are to be understood as including the plural forms, and vice versa, unless the context clearly indicates otherwise. For example, one skilled in the art will understand that features described with respect to one ceramic insert may also be present in the remaining ceramic inserts.

[0095] The terms "first," "second," "third," and "fourth" are merely designations for a specific element or component and do not necessarily indicate a particular order or arrangement of the components or elements mentioned. For example, the presence of a fourth element / component does not necessarily imply the presence of a first, second, or third element / component, and vice versa.

[0096] Advantageous embodiments of the invention are explained in more detail below with reference to the attached figures.

[0097] Fig. 1 shows a perspective view of a wear part according to the invention in the form of a grinding roller.

[0098] Fig. 2 shows a sectional view and a plan view of a ceramic insert according to the invention shown in Fig. 1 of a wear part according to the invention.

[0099] Fig. 3 shows a section of the sectional view of a ceramic insert according to the invention shown in Fig. 2.

[0100] Fig. 4 shows a perspective view of an embodiment of the ceramic insert shown in Fig. 2 according to the invention.

[0101] Fig. 5 shows a schematic plan view of a ceramic insert according to the invention fastened in a casting mold according to the invention.

[0102] Fig. 6 shows a section of a sectional view of an exemplary alternative ceramic insert.

[0103] Fig. 7 shows a micrograph of a wear part according to the invention.

[0104] Fig. 8 shows a micrograph of a wear part according to the invention.

[0105] Fig. 1 shows a perspective view of a wear part 1 according to the invention in the form of a grinding roller. The grinding roller 1 comprises a cast metal material 2 and a plurality of ceramic inserts 3. The ceramic inserts 3 are surrounded by the cast metal material 2 or embedded therein. The grinding roller 1 has a working surface 4. The working surface 4 is also referred to as a grinding surface. In the intended use of the grinding roller 1, the working surface 4 faces the material to be ground. The working surface 4 is arranged in the radially outer region of the grinding roller 1. The ceramic inserts 3 or the upper base surfaces 5 of the ceramic inserts 3 are arranged in the working surface 4. The upper base surfaces 5 of the ceramic inserts 3 form the working surface 4. The ceramic inserts 3 have a plurality of recesses 6. The recesses 6 define upper openings 7 in the upper base surfaces 5 of the ceramic inserts 3.Joints 2 are arranged between the ceramic inserts 3. The joints 20 are filled with metal casting material 2.

[0106] Fig. 2 shows a sectional view and a plan view of a ceramic insert 3 according to the invention, shown in Fig. 1, of a wear part 1 according to the invention. The ceramic insert 3 is arcuate. The ceramic insert 3 has an upper base surface 5 and a lower base surface 8. The upper base surface 5 and the lower base surface 8 are arranged on opposite sides. The ceramic insert 3 extends along an axial direction 100 and a radial direction 100, respectively, between the upper base surface

[0107] 5 and the lower base surface 8. The ceramic insert 3 has a thickness 50. The thickness 50 is defined as the distance between the upper base surface 5 and the lower base surface 8 along the axial direction 100.

[0108] The recesses 6 extend along the axial direction 100 from the upper base surface 5 to the lower base surface 8. The recesses 6 have central axes 9. The central axes 9 are aligned parallel to the axial direction 100 and in the radial direction 100, respectively. The recesses 6 define upper openings 7 in the upper base surface 5. The recesses 6 define lower openings 10 in the lower base surface 8. The upper openings 7 have an upper diameter 51. The lower openings 7 have a lower diameter 52. In the exemplary embodiment shown in Fig. 2, the upper diameters 51 are smaller than the lower diameters 52. The recesses 6 are conical or tapered.

[0109] The ceramic insert 3 extends essentially in a first direction 200 and a second direction 300. The second direction 300 corresponds to the circumferential direction of the grinding roller 1 shown in Fig. 1. The first direction 200 and the second direction 300 are orthogonal to one another and each orthogonal to the axial direction 100. The extension of the ceramic insert 3 along the first direction 200 defines the width 53 of the ceramic insert 3. The extension of the ceramic insert 3 along the second direction 300 defines the length 54 of the ceramic insert 3.

[0110] The thickness 51 of the ceramic insert is 35 millimeters. The width 53 of the ceramic insert 3 is 120 millimeters. The length 54 of the ceramic insert is 150 millimeters. These values ​​are for illustrative purposes only. Other values ​​are also possible.

[0111] The recesses 6 are arranged in several rows 11 in the ceramic insert 3. The rows 11 extend in the first direction 200. Five rows 11 are shown in Fig. 2. Each row 11 has three or four recesses 6. The distances between adjacent recesses 6, in particular the central axes 9 of the recesses 6, within a row 11 along the first direction 200 are referred to as first distances 55 and amount to 30 millimeters. The distances between adjacent rows 11, in particular the central axes 9 of the recesses 6 of adjacent rows 11 along the second direction 300, are referred to as second distances 56 and amount to 15 millimeters. Adjacent rows 11 are offset by an offset 57 in the first direction 200; the offset 57 amounts to 15 millimeters. The values ​​are to be understood merely as examples. Other values ​​are also possible.

[0112] The minimum edge distance 58 between the recesses 6, in particular the central axes 9, and the edge of the ceramic insert 3 along the first direction 200 is 15 millimeters. The minimum edge distance 59 between the recesses 6, in particular the central axes 9, and the edge of the ceramic insert 3 along the second direction 300 is 15 millimeters.

[0113] Fig. 3 shows a section of the sectional view of a ceramic insert 3 according to the invention shown in Fig. 2. For reasons of clarity, the ceramic insert 3 shown in Fig. 3 is flat. However, the ceramic insert 3 can also be curved, as shown in Fig. 2. In Fig. 3, only one recess 6 is shown. The upper diameter 51 of the upper opening 7 in the ceramic insert 3 is smaller than the lower diameter 52 of the lower opening 10 in the ceramic insert 3. The upper diameter 51 is 8 millimeters. The lower diameter is 10 millimeters. These values ​​are to be understood as examples only. Other values ​​are also possible.

[0114] The recess 6 is conical, in particular frustoconical. The conical shape of the recess 6 can lead to better infiltration 13 of the ceramic insert 3 by the metal casting material 2 and to improved wear behavior. The conical recesses 6 can be arranged in the ceramic insert 3 as shown in Fig. 2. The recesses 6 of the wear part 1 shown in Fig. 1 can be designed according to the recess 6 shown in Fig. 3.

[0115] Fig. 4 shows a perspective view of an embodiment according to the invention of the ceramic insert 3 shown in Fig. 2. The ceramic insert 3 is arc-shaped. The ceramic insert 3 has nine rows 11 of recesses 6. The recesses 6 can be formed according to Fig. 3 or Fig. 6. Adjacent rows 11 are offset by the offset 57 along the first direction 200. The distances 55 between adjacent recesses 6 within a row 11, the edge distances 58, 59 and the distances 56 between adjacent rows 11 can be formed as shown in Fig. 2. The thickness 50, the width 53 and the length 54 of the ceramic insert 3 can be formed as shown in Fig. 2. Other values ​​are also possible.

[0116] Fig. 5 shows a schematic plan view of a ceramic insert 3 fastened in a casting mold 14. The casting mold 14 can be a hybrid casting mold 14 with a first component 15 made of water glass-bonded sand and a second component 16 made of furan resin-bonded sand. The ceramic insert 3 is fastened to the casting mold 14, in particular to the first component 15. For this purpose, dowels 17 are introduced into the first component 15. Fastening means 18 in the form of screws protrude through recesses 6 in the ceramic insert 3 and are fastened with the dowels 17. Spacers 19, in particular in the form of washers 19, can be arranged between the dowels 17 and the ceramic insert 3. Washers 19 can be arranged between the nuts of the fastening means 18 and the ceramic insert 3. By way of example, only two recesses 6 are shown in Fig. 5. The ceramic insert 3 has further recesses 6, through which, however, no fastening means 18 protrude.As a rule, two fastening means 18 are sufficient. For example, the left recess 6 in Fig. 5 is shown as a cylindrical recess 6 according to Fig. 6, and the right recess 6 in Fig. 5 is shown as a conical recess 6 according to Fig. 3. In practice, the recesses 6 within a ceramic insert 3 are generally identically shaped. However, a combination of cylindrical recesses 6 and conical recesses 6 can also be provided.

[0117] Fig. 6 shows a section of a sectional view of an exemplary alternative ceramic insert 3. In Fig. 6, only one recess 6 is shown. The upper diameter 51 of the upper opening 7 in the ceramic insert 3 corresponds to the lower diameter 52 of the lower opening 10 in the ceramic insert 3. The metal casting material 2 is poured through the lower opening 10 into the recess 6 of the ceramic insert 3. The angled arrows indicate the pouring direction 12. The metal casting material 2 penetrates into the pores of the ceramic insert 3. This infiltration 13 is indicated by the small arrows. The ceramic insert 3 shown in Fig. 6 is flat. However, the ceramic insert 3 can also be curved.

[0118] 7 and 8 show micrographs of wearing parts 1. Fig. 7 shows that the ceramic insert 3 is arranged in an upper edge region 21 of the wearing part 1, in particular in the region of the working surface 4 of the wearing part 1. The upper base surface 5 of the ceramic insert 3 forms part of the working surface 4. The recesses 6 are cylindrical in the exemplary embodiment shown. The diameter of the upper opening 7 corresponds to the diameter of the lower opening 10. The cast metal material 2 is poured into the recesses 6. The infiltration 13 of the cast metal material 2 into the pores of the ceramic insert 3 can be seen in Figs. 7 and 8. The micrograph shown in Fig. 7 shows a wearing part 1 which comprises a ceramic insert 3 according to the embodiment shown in Fig. 6. According to the invention, however, the recesses 6 have a shape that tapers conically towards the upper base surface 5.

Claims

Claims 1. Wear part (1) for a mill, in particular a grinding roller or a grinding plate, comprising at least one porous ceramic insert (3) and a metal casting material (2), wherein the at least one porous ceramic insert (3) is embedded in the metal casting material (2) and infiltrated by it, wherein the at least one porous ceramic insert (3) has at least one recess (6), wherein the at least one porous ceramic insert (3) comprises silicon ceramic, wherein the at least one recess (6) has a tapered or conical shape.

2. Wear part according to claim 1, wherein a transition region is formed between the at least one porous ceramic insert (3) and the metal casting material (2), wherein the transition region consists of the material of the at least one porous ceramic insert (3) and the metal casting material (2) and in particular has no additional binding agents or binding phases.

3. Wear part according to claim 1 or 2, wherein the ceramic insert (3) has at least two recesses (6), wherein the distance between the at least two recesses (6), in particular between the central axes (9) of the two recesses (6), is between 10 millimeters and 50 millimeters, preferably between 15 millimeters and 40 millimeters, preferably between 20 millimeters and 35 millimeters.

4. Wear part according to one of the preceding claims, wherein the wear part (1) has a wear part thickness, wherein the ceramic insert (6) has a thickness of 15 percent to 50 percent of the wear part thickness, preferably 20 percent to 35 percent of the wear part thickness.

5. Wear part according to one of the preceding claims, wherein there is a gradual transition between the material of the at least one porous ceramic insert (3) and the metal casting material (2).

6. Wear part according to one of the preceding claims, wherein the ceramic insert (3) has a plurality of recesses (6) extending from a lower base surface (8) of the ceramic insert (3) to an upper base surface (5) of the ceramic insert (3), wherein the recesses (6) in the upper base area (5) make up between 5 percent and 30 percent, preferably between 8 percent and 20 percent, preferably between 10 percent and 15 percent, of the entire upper base area (5).

7. Wear part according to one of the preceding claims, wherein the ceramic insert (3) is arc-shaped, wherein the at least one recess (6) extends in the radial direction of the ceramic insert (3).

8. Mill comprising a wear part (1) according to one of the preceding claims.

9. A method for producing a wear part (1) of a mill, in particular for producing a grinding roller or a grinding plate, comprising: - Providing a casting mold (14) for the wear part (1), - arranging at least one porous ceramic insert (3) in the casting mold (14), and - Pouring a metal casting material (2) into the casting mold (14), wherein the metal casting material (2) flows through one or more recesses (6) in the ceramic insert (3) into pores of the ceramic insert (3), wherein the ceramic insert (3) comprises silicon ceramic.

10. The method according to claim 9, wherein each of the recesses (6) defines a lower opening (10) and an upper opening (7) in the at least one ceramic insert (3), the lower opening (10) being larger than the upper opening (7), the metal casting material (2) being poured into the at least one ceramic insert (3) through the lower opening (10).

11. The method according to claim 9 or 10, wherein providing the casting mold (14) for the wear part (1) comprises producing a hybrid casting mold (14), wherein the hybrid casting mold (14) has a first component (15) made of water glass-bonded sand and a second component (16) made of furan resin-bonded sand.

12. Method according to one of claims 9 to 11, wherein a spacer (19) is mounted between the ceramic insert (3) and the hybrid casting mold (14), in particular a side wall of the casting mold (14).

13. Use of ceramic inserts (3) cast into a metal casting material (2) in a wear part (1) of a mill, in particular in a grinding roller or a grinding plate, wherein the ceramic inserts (3) have conical, in particular truncated cone-shaped or truncated pyramid-shaped, recesses (6), wherein the ceramic inserts (3) comprise silicon ceramic.

14. Wear part according to one of claims 1 to 7, mill according to claim 8, method according to one of claims 9 to 12, or use according to claim 13, wherein the at least one ceramic insert (3) or the ceramic inserts (3) comprise silicon carbide, in particular consist thereof.

15. Wear part according to one of claims 1 to 7, mill according to claim 8, method according to one of claims 9 to 12, or use according to claim 13, wherein the at least one ceramic insert (3) or the ceramic inserts (3) have a solids content of 25 volume percent to 80 volume percent, preferably 30 volume percent to 75 volume percent, preferably 55 volume percent to 65 volume percent.

16. Wear part according to one of claims 1 to 7 or mill according to claim 8, wherein the at least one recess (6) extends between two opposite surfaces (5, 8) of the ceramic insert (3).

17. Use according to claim 13, wherein the recesses (6) extend over the entire thickness of the ceramic insert (3).

18. Wear part according to one of claims 1 to 7, mill according to claim 8, method according to one of claims 9 to 12, or use according to claim 13, wherein the metal casting material (2) comprises nickel chill casting, in particular consists of nickel chill casting.

Images