EP4065282B1 - Wear-resistant element for a comminuting apparatus - Google Patents

Description

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

In comminution devices, such as grinding rollers, which are used in particular for material bed comminution of, for example, hard ore, high wear occurs on the surface of a wear surface, such as the grinding roller surface, during operation of the comminution device. To counteract this wear, it is made, for example, from the DE 2006 010 042 A1 known to apply additional wear protection elements to the surface of the grinding roller. At a certain level 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. Particularly with ceramic wear protection elements, replacing a worn wear protection element is problematic. Usually, in the case of a damaged wear protection element, the connection between the base body and the wear protection element, such as adhesive, is destroyed by heating and is expelled or pulled out of the recess in the base body, for example a roller body, by means of the gases produced during heating. However, with a ceramic material, the gases escape through cracks in the material. Mechanical removal of the ceramic wear protection element is also complex since, for example, soldering a metal to pull out the wear protection element is not possible. The replacement of the wear protection elements therefore often requires long downtimes of the roller mill as well as high maintenance costs.

From the WO 2017/125309 A1 a wear protection element for a shredding device is known.

From the EP 3 088 084 A1 a hard body is known as grid armor for a roller press, a method for its production and a roller for a roller press.

From the WO 2016/008967 A1 Ceramic grains and processes for their production are known.

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

This task is achieved by a wear protection element with the features of independent device claim 1. Advantageous further training results from the dependent requirements.

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 region which can be connected to the recess in the surface of the wear surface and a wear region which is at least partially made up of 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 of a metal and the jacket being made of a ceramic. In particular, the core is arranged completely within the jacket. 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.

The comminution device is, for example, a roller mill, a roller crusher, a hammer mill or a vertical roller mill, the wear surface being in particular the surface of a grinding roller which is exposed to high levels of wear during operation of the comminution device, the hammer tools and the surface of the grinding track of a hammer mill or the surface of the Rollers and the grinding plate of a vertical roller mill.

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 such that it is on the surface of the Wear surface, in particular in a recess in the surface of the wear surface, can be fastened.

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 shredding 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 beyond the fastening area at the height of the wear protection element, 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, made entirely of a metal, such as steel or hard metal, such as tungsten carbide. The jacket is preferably made entirely of 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. Preferably, the core 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 in the axial direction along an outer surface of the wear element.

Such a wear protection element can be produced much more cost-effectively, since there is no need to form the entire wear protection element from the more expensive, wear-resistant material, such as ceramic. The area of the wear protection element, which is exposed to no or only very little wear, has a less wear-resistant material, which requires lower material costs. A metal core 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 This is heated, for example, in order to loosen a connection between the fastening area and the wear surface of the shredding device. The wear protection element is then pulled out on the metal core. In the event of severe wear, it is also conceivable to attach a metallic material to the metal core, for example by 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 makes it possible to remove the wear protection element in a simple manner, regardless of the extent of the 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 removal of the attachment area along with the wear area. The core is, for example, cohesively connected to the fastening area, in particular soldered, glued or welded to it.

According to a further embodiment, the jacket is sleeve-shaped. Sleeve-shaped means in particular that the jacket is cylindrical with a central recess, with the core being arranged within the recess. The fastening area is preferably cylindrical and the wear area lies against it.

For example, the material of the jacket comprises a ceramic material, such as 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 AI2O3, zirconium oxide ZrO2, and/or silicon carbide SiC or a combination of the materials mentioned. Furthermore, particles made of industrial diamonds, in particular high-strength ceramics, are preferably embedded in a ceramic or metallic matrix in the wear area.

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 during 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%.

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

For example, the ceramic has a density of 1.5 to 5 g/cm ³ , preferably 2 to 4 g/cm ³ , in particular 2.7 to 3 g/cm ³ . For example, the ceramic has an Al2O3 (corundum) content of 10%. This leads to improved wear resistance with a small reduction in the toughness of the ceramic.

The ceramic in particular 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, using X-ray diffraction in accordance with ISO 13356. At a ratio of more than 40%, preferably more than 30%, in particular more than 20% of monoclinic to tetragonal and/or cubic zirconium oxide, negative effects occur, such as too rapid a conversion of metastable zirconium oxide into the stable monoclinic phase on, whereby an increase in volume occurs. If the transformation occurs too quickly, surface tensions arise, which, for example, cause local cracks.

The yttrium-stabilized zirconium oxide of the ceramic in particular has a grain size D50 of less than 1.5 μm, preferably less than 1 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 refers to the grain size of 50% of the ceramic grains. In 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 3µm, in particular less than 2µm, preferably less than 1.5µm. 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 an yttrium content of 2 to 4 mol% Y2O3. The advantages of such an yttrium 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 ² . The number of pores per surface also provides an indication of wear resistance. A small number of pores of a relatively large size, such as more than 200µm, ensures high wear resistance as 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 ² . In particular, the ceramic has one The number of pores with a size of more than 100µm is less than 2 per mm ² . Such a number of pores significantly increases the service life of the wear protection element.

According to a further embodiment, the material of the fastening area comprises a steel, such as a tempered structural steel. According to a further embodiment, the jacket is firmly connected to the fastening area, for example materially, 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, wherein the wear protection element is at least partially mounted 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 shredding device with such a wear protection element.

According to a further embodiment, the fastening area of the wear protection element is cohesively connected to the grinding roller, in particular welded, glued or soldered. Preferably, the fastening area is soldered, glued or welded to the recess in the wear surface.

The shredding device is, for example, a grinding roller for shredding the material bed or a vertical roller mill.

Description of the drawings

Fig. 1

zeigt eine schematische Darstellung einer Zerkleinerungseinrichtung in einer Frontansicht gemäß einem Ausführungsbeispiel.

Fig. 2

zeigt eine schematische Darstellung einer Mahlwalze der Zerkleinerungseinrichtung gemäß Fig. 1.

Fig. 3

zeigt schematische Darstellungen eines Ausführungsbeispiels des Verschleißschutzelements in einer Seitenansicht und einer Draufsicht.

Fig. 4

zeigt schematische Darstellungen eines Ausführungsbeispiels des Verschleißschutzelements in einer Schnittansicht.

The invention is explained in more detail below using several exemplary embodiments with reference to the accompanying figures.

Fig. 1

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

Fig. 2

shows a schematic representation of a grinding roller of the shredding device Fig. 1 .

Fig. 3

shows schematic representations of an exemplary embodiment of the wear protection element in a side view and a top view.

Fig. 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.

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

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

Furthermore, the grinding roller has wear protection corner elements 17 attached to its end, which, for example, have a rectangular cross section and are arranged next to one another in a row in such a way that they form a ring over the circumference of the grinding roller. Other cross-sectional shapes of the wear protection corner elements 17 are also conceivable, which differ from those in Fig. 2 Cross-sectional shape shown may vary. An arrangement of the wear protection corner elements 17 at a distance from one another is also possible. In Fig. 2 For example, only the left end of the grinding roller with the wear surface 12 is shown, the right end, not shown, advantageously being identical in structure.

Fig. 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, approximately 10 to 30% of the diameter of the wear protection element 16.

Fig. 4 shows a sectional view of the wear protection element 16 Fig. 3 . The wear protection element 16 has a fastening area 24 and a wear area 22, wherein the fastening area 24 is arranged in the recess 26 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 at least partially or completely arranged 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 a third of the entire wear protection element 16, with the wear area 22 approximately comprising the further 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 made 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, which includes, for example, diamond, ceramic or titanium. The matrix material includes, for example, tungsten carbide. The particles are in particular bonded to the matrix material, for example by sintering.

During operation of the shredding device 10, the wear protection elements 16 are exposed to a high level of wear, with the wear area 22 of the wear protection elements 16 protruding from the surface of the wear surfaces 12, 14 of the grinding rollers in particular wearing out. The wear-resistant material of the wear area 22 significantly reduces the wear of the wear protection elements 16. Furthermore, a design of the fastening area, which is exposed to no or only very little wear, is made from the more expensive, wear-resistant material is dispensed with. The metal core makes it possible to remove the wear protection element from the recess 26 in the roller surface, even if the wear area 22 is already heavily worn, by pulling out the wear protection element 16 on the metal core 20 using an appropriate tool.

The fastening area 24 is preferably made entirely of 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 formed in one piece with it.

Reference symbol list

10

Shredding device/roller mill

12

Wear surface / grinding roller

14

Wear surface / grinding roller

16

Wear protection element

17

Wear protection corner element

18

Coat

20

core

22

Wear area

24

Fastening area

26

recess

Claims (9)

1. Wear-resistant element (16) for partially inserting into a recess (26) in the surface of a wearing area (12, 14) of a comminuting device (10),

   wherein the wear-resistant element (16) has a fastening region (24), which can be connected to the recess (26) in the surface of the wearing area (12, 14), and has a wearing region (22), which protrudes at least partly from the surface of the wearing area (12, 14), and

   wherein the fastening region (24) is made from a metal,

   characterised in that

   the wearing region (22) has a shell (18) and a core (20) arranged inside the shell (18), wherein the core (20) is made from a metal and the shell (18) is made from a ceramic (20), and wherein the material of the shell comprises a ceramic, which includes yttrium-stabilised, tetragonal polycrystalline zirconium oxide (TPZ), wherein the TPZ makes up at least 60%, preferably at least 80%, in particular 95% to 100% by volume of the ceramic.
2. Wear-resistant element (16) according to claim 1, wherein the core (20) extends through the entire wearing region.
3. Wear-resistant element (16) according to any one of the preceding claims, wherein the core (20) is fixed securely to the fastening region (24) or is formed integrally therewith.
4. Wear-resistant element (16) according to any one of the preceding claims, wherein the shell (18) is configured to be sleeve-like.
5. Wear-resistant element (16) according to any one of the preceding claims, wherein the material of the fastening region (24) comprises a steel.
6. Wear-resistant element (16) according to any one of the preceding claims, wherein the shell of the wearing region (22) is fixed securely to the fastening region.
7. Wear-resistant element (16) according to any one of the preceding claims, wherein the fastening region (24) comprises less than 50%, preferably less than 20%, most preferably less than 15% of the wear-resistant element (16).
8. Comminuting device (10) having a wearing area (12, 14) and a wear-resistant element (16) according to any one of claims 1 to 7, wherein the wear-resistant element (16) is attached at least partly in a recess (26) in the surface of the wearing area (12, 14).
9. Comminuting device (10) according to claim 8, wherein the fastening region (24) of the wear-resistant element (16) is materially connected to the wearing area/grinding roller (12, 14), in particular welded, adhered or soldered.

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