BE1027797B1 - Wear protection element for a shredding device - Google Patents

Abstract

The invention comprises a wear protection element (16) for partial insertion into a recess (26) in the surface of a wear surface (12, 14) of a comminution device (10), the wear protection element (16) having a fastening area (24) which is connected to the recess ( 26) is connectable in the surface of the wear surface (12, 14) and has a wear area (22) which at least partially protrudes from the surface of the wear surface (12, 14), and wherein the fastening area (24) is formed from a metal, wherein the wear area (22) has a jacket (18) and a core (20) arranged within the jacket (18), the core (20) being made of a metal and the jacket (18) being made of a ceramic (20).

Description

Wear protection element for a comminution device The invention relates to a wear protection element for partial insertion into a recess on the surface of a wear surface of a comminution device and a comminution device with such a wear protection element.

In the case of comminution devices, such as grinding rollers, which are used in particular in the comminution of material beds of, for example, hard ore, the surface of a wear surface, such as the grinding roller surface, is subject to high wear during operation of the comminution device.

In order to counteract this wear, it is known from DE 2006 010 042 A1, for example, to apply additional wear protection elements to the surface of the grinding roller.

If there is a certain degree of wear, it is necessary to replace or renew the wear protection elements of the grinding roller, for example, in order to guarantee efficient grinding.

Replacing a worn-out wear protection element is problematic, particularly with ceramic wear protection elements.

In the case of a damaged wear protection element, the connection between the base body and the wear protection element, such as adhesive, is usually destroyed by heating and is driven out or pulled out of the recess in the base body, for example a roller body, by means of the gases produced during heating.

In the case of a ceramic material, however, the gases escape through cracks in the material.

Mechanical removal of the ceramic wear protection element is also complex since, for example, it is not possible to solder a metal to pull out the wear protection element.

The replacement of the wear protection elements therefore often results in long downtimes of the roller mill and high maintenance costs.

It is therefore the object of the present invention to provide a wear protection element which has a high level of wear resistance in order to increase the maintenance intervals for replacing the wear protection elements, the wear protection element at the same time being inexpensive to replace.

This object is achieved by a wear protection element with the features of the independent device claim 1. Advantageous developments result from the dependent claims.

According to a first aspect, the invention comprises a wear protection element for partial insertion into a recess on the surface of a wear surface of a comminution device, the wear protection element having a fastening area that can be connected to the recess in the surface of the wear surface and a wear area that is at least partially from the Surface of the wear surface protrudes. The fastening area is made of a metal. The wear area has a jacket and a core arranged at least partially within the jacket, the core being made from a metal and the jacket being made from a ceramic. In particular, the core is arranged completely within the jacket.

The crushing device is, for example, a roller mill, a roller crusher, a hammer mill or a vertical roller mill, the wear surface in particular the surface of a grinding roller exposed to high wear during operation of the crushing device, the hammer tools and the surface of the grinding track of a hammer mill or the surface of the Rolls and the grinding table of a vertical roller mill is. The wear protection element is, for example, cylindrical or has a polygonal cross section. In particular, one end of the wear protection element is designed in such a way that it can be fastened to the surface of the wear surface, in particular in a recess in the surface of the wear surface. The fastening area is preferably arranged in such a way that it is exposed to no or only very little wear during operation of the comminuting device. In particular, the fastening area serves to fasten the wear protection element to the surface of the wear surface. The wear area is arranged on the fastening area and preferably extends at the level of the wear protection element beyond the fastening area, so that the wear area is exposed to the majority of the wear acting on the wear protection element. The wear area is preferably attached completely outside the surface of the wear area, with only the fastening area being arranged in the recess of the wear area. The fastening area and the core of the wear area are, for example, completely made of a metal such as steel or hard metal such as tungsten carbide. The jacket is preferably formed entirely from a ceramic.

The core is, for example, cylindrical and extends in particular from the fastening area through the entire wear area. It is also conceivable that the core has a square or polygonal cross section. The core preferably extends in the axial direction along the central axis of the wear protection element through the wear area. It is also conceivable that the core extends along an outer surface of the wear element in the axial direction.

Such a wear protection element can be produced much more economically, since it is possible to dispense with the formation of the entire wear protection element from the more expensive, more wear-resistant material, such as ceramic. The area of the wear protection element that is exposed to no or only very little wear has a less wear-resistant material, which results in lower material costs. A core made of metal in the wear area offers the advantage that the worn wear protection element can be removed from the recess in the surface of the grinding roller. To remove the wear protection element, it is heated, for example, in order to release a connection between the fastening area and the wear surface of the comminution device. The wear protection element is then pulled out on the metal core. In the event of heavy wear, it is also conceivable to fasten a metallic material to the metal core by, for example, soldering, and to pull the wear protection element out of the recess in the wear surface.

According to a first embodiment, the core extends through the entire wear area. This enables the wear protection element to be removed in a simple manner regardless of the degree of wear.

According to a further embodiment, the core is firmly connected to the fastening area or is formed in one piece with it. For example, the fastening area with the core is produced by casting or machining, such as turning or milling. This ensures that the fastening area is removed together with the wear area. The core is, for example, materially connected to the fastening area, in particular soldered, glued or welded to it.

According to a further embodiment, the jacket is sleeve-shaped. By sleeve-shaped is to be understood in particular that the jacket is designed in the shape of a cylinder with a central recess, the core being arranged within the recess. The fastening area is preferably cylindrical and the wear area rests against it.

For example, the material of the jacket comprises a ceramic material, such as, for example, tungsten carbide WC, titanium carbide TiC, titanium carbonitride TiCN, vanadium carbide VC, chromium carbide CrC, tantalum carbide TaC, boron carbide BC, niobium carbide NbC, molybdenum carbide Mo2C, aluminum oxide / Al2O3, zirconium oxide and Al2O3, zirconium oxide or a combination of the materials mentioned. Furthermore, particles of industrial diamonds, in particular high-strength ceramics, are preferably embedded in a ceramic or metallic matrix in the wear area. According to a further embodiment, the material of the jacket comprises a ceramic which has yttrium-stabilized, tetragonal polycrystalline zirconium oxide (TPZ), the TPZ having a volume fraction of at least 60%, preferably at least 80%, in particular 95% to 100% of the ceramic . This has the advantage of increased corrosion resistance of the material, especially when wet grinding.

In particular, the ceramic has a porosity of less than 5%, preferably less than 4%, in particular less than 3%. The ceramic preferably has a porosity of at least 1%.

5 A porosity of less than 5%, preferably less than 4%, in particular less than 3%, leads to improved wear behavior. The aforementioned information on porosity is preferably the total porosity, which corresponds to an average value of the pore sizes of the material. The pores are preferably distributed essentially uniformly over the ceramic material.

For example, the ceramic has a density of 1.5 to 5 g / cm 3, preferably 2 to 4 g / cm®, in particular 2.7 to 3 g / cm®. For example, the ceramic has an Al 2 O 3 (corundum) content of 10%. This leads to improved wear resistance and, at the same time, a slight reduction in the toughness of the ceramic.

In particular, the ceramic has a ratio of monoclinic to tetragonal zirconium oxide of less than 40%, in particular less than 30%, preferably less than 20%. The ratio of monoclinic to tetragonal zirconium oxide is preferably at least 2%. For example, the zirconium oxide contained in the ceramic has less than 40%, in particular less than 30%, preferably less than 20% monoclinic zirconium oxide, the remaining zirconium oxide being tetragonal zirconium oxide. The ratio of monoclinic to tetragonal zirconium oxide is determined, for example, by means of X-ray diffraction in accordance with ISO 13356. At a ratio of more than 40%, preferably more than 30%, in particular more than 20% monoclinic to tetragonal and / or cubic zirconium oxide, negative effects occur, such as, for example, too rapid a conversion of metastable zirconium oxide into the stable monoclinic phase, whereby a Volume increase takes place. If the transformation is too rapid, surface tensions arise which, for example, cause local cracks. The yttrium-stabilized zirconium oxide of the ceramic has, in particular, a grain size D50 of less than 1.5 μm, preferably less than 14 μm, in particular less than 0.8 μm. The D50 grain size of the ceramic is preferably at least 0.2 µm.

The D50 value means the grain size of 50% of the grains of the ceramic. With the exemplary D50 grain size value, 50% of the grains of the yttrium-stabilized zirconium oxide have a grain size diameter of less than 1.5 μm, preferably less than 1 μm, in particular less than 0.8 μm.

The D90 value of the grain size is preferably less than 3 μm, in particular less than 2 μm, preferably less than 1.5 μm. Wear protection elements of a shredding device are exposed to local stresses. Therefore, a wide grain size distribution should be avoided in order to prevent the formation of cracks or breakouts. In particular, the ceramic has a yttrium content of 2 to 4 mol% Y203. Advantages of such a yitrium content are better sintering behavior at an even lower sintering temperature, as well as a finer crystalline structure, which in turn leads to higher fatigue resistance and improved fracture toughness. Furthermore, the ceramic has, for example, Ce-TZP with a content of 10 to 12 mol% of CeO2. In particular, the ceramic has a content of 8 to 10 mol% of Mg-PSZ. It is also conceivable that the ceramic has a content of 5 to 10 mol% of MgO as a stabilizer.

In particular, the ceramic has a number of pores with a size of more than 200 μm of less than 0.1 per mm? on. The number of pores per surface also provides an indication of the wear resistance. A small number of pores of a relatively large size, such as more than 200 μm, ensures high wear resistance, since local breakouts from the ceramic material are avoided. The ceramic preferably has a number of pores with a size of more than 150 μm of less than 0.4 per mm? on. In particular, the ceramic has a number of pores with a size of more than 100 μm of less than 2 per mm? having. Such a number of pores increases the service life of the wear protection element considerably. According to a further embodiment, the material of the fastening area comprises a steel, such as, for example, a hardened and tempered structural steel. According to another

Embodiment, the jacket is firmly connected to the fastening area, for example cohesively, such as gluing or soldering, or positively. According to a further embodiment, the fastening area comprises less than 50%, preferably less than 20%, most preferably less than 15% of the wear protection element. For example, the fastening area comprises at least 10% of the wear protection element. The invention further comprises a comminution device having a wear surface and a wear protection element as described above, the wear protection element being at least partially attached in a recess in the surface of the wear surface, in particular a grinding roller. The advantages described with reference to the wear protection element also apply to the comminution device with such a wear protection element. According to a further embodiment, the fastening area of the wear protection element is materially connected to the grinding roller, in particular welded, glued or soldered. The fastening area is preferably soldered, glued or welded to the recess in the wear surface. The comminution device is, for example, a grinding roller for comminuting the bed of material or a vertical roller mill.

Description of the drawings The invention is explained in more detail below on the basis of several exemplary embodiments with reference to the accompanying figures.

1 shows a schematic representation of a comminution device in a front view according to an exemplary embodiment.

FIG. 2 shows a schematic representation of a grinding roller of the comminution device according to FIG. 1. FIG. 3 shows schematic representations of an exemplary embodiment of the wear protection element in a side view and a top view.

4 shows schematic representations of an exemplary embodiment of the wear protection element in a sectional view.

In Fig. 1, a comminution device 10, in particular a roller mill, is shown schematically. The comminution device 10 comprises two grinding rollers, shown schematically as circles, with wear surfaces 12, 14, which have the same diameter and are arranged next to one another. A grinding gap is formed between the wear surfaces 12, 14 of the grinding rollers, the size of which can be adjusted, for example.

When the comminution device 10 is in operation, the grinding rollers rotate in the opposite direction to one another in the direction of rotation shown by the arrows, with ground material running through the grinding gap in the direction of fall and being ground.

2 shows an end region of a grinding roller which has a wear surface 12 to which wear protection elements 16 are attached. The wear protection elements 16 are mounted in the outer periphery of the surface of the grinding roller. By way of example, the wear protection elements 16 of FIG. 2, which are spaced apart from one another and arranged next to one another, have a circular cross section. It is also conceivable that the wear protection elements 16 vary in size, number, cross-sectional shape and arrangement to one another over the surface of the grinding roller in order to compensate for local differences in wear during operation of the comminution device 10, for example.

Furthermore, the grinding roller has wear corner elements 17 attached to its end, which for example have a rectangular cross section and are arranged in a row next to one another in such a way that they form a ring over the circumference of the grinding roller. There are also other cross-sectional shapes of the

Wear protection corner elements 17 are conceivable which differ from the cross-sectional shape shown in FIG. 2. An arrangement of the wear protection corner elements 17 at a distance from one another is also possible. In FIG. 2, only the left end of the grinding roller with the wear surface 12 is shown by way of example, the right end (not shown) advantageously being identical in structure. 3 shows a wear protection element 16 in a side view and a top view. The wear protection element 16 has a jacket 18 and a core 20 which is at least partially radially surrounded by the jacket. The core 20 extends axially along the central axis of the essentially cylindrical wear protection element 16 to the upper end face of the wear protection element

16. The core 20 is, for example, cylindrical and is preferably firmly connected to the jacket 18. It is also conceivable that a plurality of cores 20, for example two, four or six cores 20, extend through the wear protection element 16, preferably parallel to one another. The diameter of the core 20 is, for example, about 10 to 30% of the diameter of the wear protection element 16. FIG. 4 shows a sectional view of the wear protection element 16 of FIG the recess 26 is arranged on the surface of the wear surface 12 of the grinding roller and is connected to the wear surface 12 of the grinding roller. For example, the wear protection element 16 is cohesively connected to the fastening area 24 with the recess 26 in the surface of the wear surface 12 of the grinding roller, in particular welded, soldered or glued or positively connected, in particular screwed or wedged. The wear area 22 of the wear protection element 16 is arranged at least partially or completely outside the recess 26 in the wear surface 12, so that it protrudes from the surface of the wear surface 12 in the radial direction of the grinding roller (not shown). In the exemplary embodiment shown, the fastening area 24 comprises approximately one third of the entire wear protection element 16, with the wear area 22 encompassing approximately the other two thirds. The fastening area 24 is preferably formed from a metal such as steel.

The wear area 22 of the wear protection element 16 has the jacket 18 and the core 20, the jacket 18 preferably made of a ceramic material such as tungsten carbide, titanium carbide, titanium carbonitride, vanadium carbide, chromium carbide, tantalum carbide, boron carbide, niobium carbide, molybdenum carbide, aluminum oxide, zirconium oxide, and / or silicon carbide or a combination of the materials mentioned. In particular, the ceramic of the jacket comprises yttrium-stabilized, tetragonal polycrystalline zirconium oxide (TPZ), the TPZ having a volume fraction of at least 60%, preferably at least 80%, in particular 95% to 100% of the ceramic. Furthermore, particles of industrial diamonds or high-strength ceramics can also be embedded in a ceramic or metallic matrix in the jacket 18. For example, the jacket 18 has a matrix material in which a plurality of particles are arranged. The particles are in particular a highly wear-resistant material that includes, for example, diamond, ceramic or titanium. The matrix material includes, for example, tungsten carbide. The particles are in particular materially bonded to the matrix material, for example by sintering.

During operation of the comminution device 10, the wear protection elements 16 are exposed to a high level of wear, in particular the wear area 22 of the wear protection elements 16 protruding from the surface of the wear surfaces 12, 14 of the grinding rollers wears. The wear-resistant material of the wear area 22 considerably reduces the wear of the wear protection elements 16. Furthermore, the fastening area, which is exposed to no or only very little wear, is not made from the more expensive, more wear-resistant material. The core made of metal enables the wear protection element to be removed from the recess 26 in the roll surface even if the wear area 22 is already heavily worn, by pulling the wear protection element 16 out of the metal core 20 with a suitable tool.

The fastening area 24 is preferably formed entirely from a metal and is firmly connected to the core 20.

For example, the fastening area 24 is glued, soldered or welded to the core 20 or is formed in one piece therewith.

LIST OF REFERENCE NUMERALS 10 comminution device / roller mill 12 wear surface / grinding roller

14 Wear surface / grinding roller 16 Wear protection element 17 Wear protection corner element 18 Shell 20 Core

22 Sanding area 24 Fastening area 26 Recess

Claims (10)

Claims 1. Wear protection element (16) for partial insertion into a recess (26) in the surface of a wear surface (12, 14) of a comminution device (10), the wear protection element (16) having a fastening area (24) which is connected to the recess (26) is connectable in the surface of the wear surface (12, 14) and has a wear area (22) which at least partially protrudes from the surface of the wear surface (12, 14), and wherein the fastening area (24) is formed from a metal, characterized that the wear area (22) has a jacket (18) and a core (20) arranged inside the jacket (18), the core (20) being made from a metal and the jacket (18) made from a ceramic (20) . 2. Wear protection element (16) according to claim 1, wherein the core (20) extends through the entire wear area. 3. Wear protection element (16) according to one of the preceding claims, wherein the core (20) is fixedly connected to the fastening area (24) or is formed in one piece therewith. 4. Wear protection element (16) according to one of the preceding claims, wherein the jacket (18) is sleeve-shaped. 5. Wear protection element (16) according to one of the preceding claims, wherein the material of the jacket comprises a ceramic which has yttrium-stabilized, tetragonal polycrystalline zirconium oxide (TPZ), the TPZ having a volume fraction of at least 60%, preferably at least 80%, in particular 95% to 100% of the ceramic. 6. Wear protection element (16) according to one of the preceding claims, wherein the material of the fastening region (24) comprises a steel. 7. Wear protection element (16) according to one of the preceding claims, wherein the jacket of the wear area (22) is firmly connected to the fastening area. 8. Wear protection element (16) according to one of the preceding claims, wherein the fastening area (24) comprises less than 50%, preferably less than 20%, most preferably less than 15% of the wear protection element (16). 9. Crushing device (10) having a wear surface (12, 14) and a wear protection element (16) according to one of claims 1 to 9, wherein the wear protection element (16) is at least partially in a recess (26) in the surface of the wear surface (12, 14) is attached. 10. Crushing device (10) according to claim 9, wherein the fastening area (24) of the wear protection element (16) is integrally connected to the grinding roller (12, 14), in particular welded, glued or soldered.