Part

Abstract

Wear part 6 for a roller mill, the wear part comprising a wear body 7 with wear face 8 and an opposing connection face 9. A support body 10 with a main axis M, top face, bottom face 12, first side 13

Description

Field of the Invention This disclosure relates generally to the field of wear parts, in particular for roller mills such as high-pressure grinding roller mills, and roller mills comprising said wear parts. Background High-pressure grinding roller (HPGR) milling is becoming a popular route for crushing rocks and minerals. As shown in Figure 1, HPGR apparatus includes a first roller 1 and a second roller 2 with a gap between them. In use, the first and second rollers counter-rotate. A feed of material 3 is allowed to fall from a hopper through a gap between the first and second rollers 1,2. The first roller 1 is allowed to move linearly in a direction normal to the direction of the material feed. The first roller is usually biased to a particular position relative to the second roller by springs or hydraulic cylinders. As the material feed passes through the gap between the first and second rollers 1, 2, compression causes the particles of the feed material 3 to fracture, and the resultant material 4 has a reduced particle size. This longitudinal region of closest approach between the first and second rollers 1,2 is referred to as the nip 5. To prevent escape of material at the ends of the rollers, it is necessary to use some form of confinement means. Two forms of confinement means are currently in use by manufacturers of HPGR systems, namely cheek plates and flanges (also referred to as rotating side plates). Cheek plates are a class of wear part which is usually placed substantially perpendicular to the longitudinal axis of the nip at each end of the rollers. The flow of abrasive material is strongest at each end of the nip, and thus the portion of the cheek plate which faces this area is typically reinforced with a wearresistant material such as cemented tungsten carbide. The wear face of cheek plates for HPGR is typically formed of multiple cemented carbide blocks. These can vary in terms of their thickness, length, height and shape. For example, cemented carbide bodies with a rectangular or square profile may be used in the inner parts of the cheek plate, while cemented carbide bodies with curved profiles may be used at the curved edges of the cheek plate. As the interfaces between carbide blocks are points of attack for wear, it is desirable to keep the number of interfaces between the blocks as low as possible. One way of doing this is to use larger blocks of cemented carbide. The cemented carbide bodies used as wear faces in cheek plates are typically attached by brazing to a steel support. The residual stresses in a brazed joint correlate with the size of the brazed area. Thus, if a steel support is large, the resulting tensile stresses can lead to cracks and chipping in the carbide. Thus, in practice the size of cemented carbide body which can be used as a wear part is limited by the size and properties of the steel support. It is an object of the invention to provide an improved wear part which overcomes the above-mentioned issues with the steel support. Summary of the invention According to a first aspect of the invention, there is provided a wear part, the wear part comprising: a wear body with a wear face and an opposing connection face; a support body with a main axis, a top face, a bottom face, a first side face and a second side face, wherein the top face opposes the bottom face, the first side face opposes the second side face, and the first side face and the second side face are substantially perpendicular to both the top face and the bottom face; and a bonding layer between the connection face of the wear body and the top face of the support body; wherein the support body comprises an elongate cut-out portion extending substantially transverse to the main axis and between the first side face and the second side face. As an option, the support body comprises two or more elongate cut-out portions. As an option, the elongate cut-out portions are spaced approximately equidistant across the wear body. As an option, the support body is formed of a metal, preferably a steel, more preferably a stainless steel. As an option, the elongate cut-out portion extends from the top face towards the bottom face. As an option, the elongate cut-out portion extends from the bottom face towards the top face. As an option, the elongate cut-out portion extends from the top face to the bottom face. As an option, the elongate cut-out portion is a groove. As an option, the elongate cut-out portion is a slit. As an option, the support body comprises a plurality of collinear elongate cut-out portions. As an option, the support body has a depth dp measured between the top face and the bottom face, and wherein the elongate cut-out portion has a depth ds measured parallel to the depth dp and the depth ds is at least 90% of the depth dp. As an option, the elongate cut-out portion has a maximum length ls measured parallel to the top face, and wherein the maximum length ls is at least 75% and at most 98% of the length of the top face. As an option, the bonding layer is a braze layer. As an option, the wear body and / or the support body are plates. As an option, the shape of the wear body substantially corresponds to the shape of the support body. As an option, the wear part is a cheek plate segment. As an option, the wear face comprises a cemented metal carbide material, preferably a cemented tungsten carbide material. As an option, the wear face comprises a superhard material. As an option, the superhard material is diamond or polycrystalline cubic boron nitride (PCBN). As an option, the diamond is polycrystalline diamond (PCD). As an option, the wear body comprises or consists of a cemented metal carbide body. As an option, the support body further comprises a third side face and fourth side face, wherein the third side face opposes the fourth side face, and the third side face and the fourth side face are substantially perpendicular to both the top face and the bottom face. As an option, the wear part has the shape of an isosceles trapezoid when viewed in the plane of the main axis. As an option, the roller mill is a high-pressure grinding roller mill. As an option, the wear part is for a roller mill. As an option, the wear part is for use in a method of rock crushing. As an option, the wear part is for rock crushing. According to a second aspect of the invention, there is provided a roller mill comprising: a first roller and a second roller, wherein the first roller and the second roller are configured to counter-rotate to form a longitudinal nip between the first and second rollers for crushing material; and a wear part according to any one of the preceding claims. As an option, the roller mill is a high-pressure grinding roller mill. As an option, the wear face is configured to be placed substantially perpendicular to a longitudinal axis of a nip formed between two counter-rotating rollers in the roller mill. Brief Description of the Drawings The invention will now be more particularly described, byway of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates schematically a known high-pressure grinding roller apparatus; Figure 2 is a schematic representation of a wear part in accordance with a first embodiment of the invention, with the wear face at the top; Figure 3 is an exploded view of the schematic representation of a wear part as shown in Figure 2; Figure 4 is a schematic representation of the wear part as depicted in Figures 2 and 3, with the wear face at the bottom; Figure 5 is a schematic representation of the wear part as depicted in Figures 2, 3 and 4, where the support body is shown in outline so as to show the elongate cut-out portion; Figure 6 is a schematic representation of a second embodiment of a wear part which is identical to the wear part of the first embodiment, except that it comprises two elongate cutout portions; the support body is again shown in outline so as to show the elongate cut-out portions; Figure 7 is a schematic representation of a third embodiment of a wear part which is identical to the wear part of the first and second embodiments, except that it comprises two sets of collinear elongate cut-out portions; the support body is again shown in outline so as to show the elongate cut-out portions; Figure 8 is a schematic representation of a cross-section through the support body showing the depth of the elongate cut-out portion with respect to the depth of the support body in one embodiment; Figure 9 is a schematic representation of a cross-section through the support body showing the depth of the elongate cut-out portion with respect to the depth of the support body in another embodiment; Figure 10 is a schematic representation of a cross-section through the support body showing the depth of the elongate cut-out portion with respect to the depth of the support body in still another embodiment; Figure 11 is a schematic representation of the bottom face of the support body showing the length of the elongate cut-out portion with respect to the length of the support body in one embodiment; Figure 12 is a schematic representation of the bottom face of the support body showing the lengths of a set of collinear elongate cut-out portions with respect to the length of the support body in another embodiment; Figure 13 is a schematic representation of a side view of a fourth embodiment of a wear part according to the invention; Figure 14 is a schematic representation of a front view of a fifth embodiment of a wear part according to the invention; Figure 15 is a schematic representation of a rearview of the fifth embodiment of the wear part according to the invention as depicted in Figure 14; and Figure 16 is a front view of the support body of the fifth embodiment as depicted in Figures 14 and 15. In the drawings, similar parts have been assigned similar reference numerals. Detailed Description As noted above, a problem which prevents the use of larger carbide bodies or plates in wear parts is the generation of cracks and chipping in the carbide bodies due to the high stresses which are experienced by the steel support body during brazing or other thermal bonding processes. The present invention provides a solution to this problem. The steel support body is provided with one or more elongate cut-out portions. These allow plastic deformation of the steel body, thereby reducing the above-mentioned stresses. As detailed below, this effectively allows a single steel support body to function as a plurality of smaller support bodies as the bending stress in the material is significantly reduced. The cut-out portions act like an expansion joint. This allows the use of larger steel supports, and therefore larger cemented carbide bodies or plates. A schematic representation of a first embodiment of a wear part 6 for a roller mill is shown in Figures 2-5. The wear part 6 comprises a wear body 7 with a wear face 8 and an opposing connection face 9. The wear face 8 comprises a cemented metal carbide material (also referred to as a cemented metal carbide). Cemented metal carbide material comprises particles of metal carbide such as tungsten carbide (WC) dispersed within a binder material comprising a metal such as cobalt (Co), nickel (Ni) or iron (Fe). The binder phase may be said to cement the carbide particles together as a sintered compact. Alternatively or additionally, the wear face 8 may comprise a superhard material. The superhard material may comprise or consist of diamond. For example, the superhard material may comprise or consist of a diamond-based composite material. Examples of diamondbased composite materials are polycrystalline diamond (PCD) material (also referred to herein as polycrystalline diamond (PCD)), silicon carbide-bonded diamond (SCD) material and diamond enhanced carbide (DEC) material. In the embodiment depicted in Figures 2-5, the wear body 7 consists of a cobalt-cemented tungsten carbide body. The wear part further comprises a support body 10 with a main axis M. The support body 10 has a top face 11, a bottom face 12, a first side face 13, a second side face 14, a third side face 15, and a fourth side face 16. The top face 11 opposes the bottom face 12. The first side face 13 opposes the second side face 14, and the first side face 13 and the second side face 14 are perpendicular to both the top face 11 and the bottom face 12. The third side face 15 opposes the fourth side face 16, and the third side face 15 and the fourth side face 16 are perpendicular to both the top face 11 and the bottom face 12. In other words, in this embodiment the wear part has the form of a rectangular cuboid. However, the exact shape of the wear part can vary and is adapted to the function it is designed to perform, as will be detailed below. The wear part 6 further comprises a bonding layer 17 between the connection face 9 of the wear body 7 and the top face 11 of the support body 10. The bonding layer 17 in this embodiment is a braze layer. However, the invention would be applicable to any high temperature bonding process. The support body 10 further comprises an elongate cut-out portion 18 extending substantially transverse to the main axis M and between the first side face 13 and the second side face 14. In this embodiment, the support body is formed of a stainless steel. The purpose of the elongate cut-out portion is to reduce stress in the support body during a high temperature bonding process, such as brazing, which is deployed to connect the support body and the wear body. The cut-out portion may be formed by any suitable machining method, for example by laser processing. The wear part may comprise more than one elongate cut-out portion 18. For example, wear part 106 depicted schematically in Figure 6 has two elongate cut-out portions 18. The elongate cut-out portions of this embodiment are spaced approximately equidistant across the wear body (along the main axis M). The separation provided by the elongate cut-out portions 18 reduces the tensile stresses induced in the cemented metal carbide material, which reduces the risk of cracking. This makes it possible to use larger cemented metal carbide material bodies. The elongate cut-out portion 18 may extend from the top face 11 of the support body 10 to the bottom face 12 of the support body 10. Such an embodiment is depicted in the schematic cross-section shown in Figure 8. This elongate cut-out portion 18 may be termed a slit. However, as depicted in Figures 9 and 10, the elongate cut-out portion 18 does not have to extend all the way from the top face 11 to the bottom face 12. As depicted in Figure 9, the elongate cut-out portion 18 may extend from the bottom face 12 towards the top face 11, while as depicted in Figure 10, the elongate cut-out portion 18 may extend from the top face 11 towards the bottom face 12. In the embodiments shown in Figures 9 and 10, the elongate cutout portion 18 may be termed a groove. Advantageously, the elongate cut-out portion 18 extends most of the depth of the support body 10. For example, and as depicted in Figure 10, the elongate cut-out portion 18 preferably has a depth ds measured parallel to a depth dp (measured between the top face 11 and the bottom face 12) and the depth dp is at least 90% of the depth dp. As depicted schematically in Figure 11, the elongate cut-out portion may have a maximum length Ls measured parallel to the top face 11 and between the first side face 13 and the second side face 14, where the maximum length Ls is at least 75% and at most 98% of the length of the top face 11. As depicted in Figure 12, the support body 10 may comprise a plurality of collinear cut-out portions 18 extending from the first side face 13 to the second side face 14. As depicted in Figure 13, the wear body 7 may have a greater depth than the support body 10. It is particularly advantageous to have a thicker wear body in positions of high wear. The wear body 7 and / or the support body 10 may be plates. As shown in Figures 2-13, the shape of the wear body 7 substantially corresponds to the shape of the support body 10. However, this is not essential, and the wear body 7 and the support body 10 may be different shapes. In one example, the wear body 7 partly overhangs the support body 10. As noted above, the overall shape of the wear part can be varied depending on the desired application. For example, as depicted in the embodiment shown in Figures 14-16, the wear part 406 may have the shape of an isosceles trapezoid when viewed in the plane of the main axis. Such a wear part broadly conforms to the concave edges required for cheek plates for high-pressure grinding roller mills. The wear part may further comprise attachment portions. These can be used to attach the wear part to a roller mill using suitable corresponding attachment means, for example a series of corresponding holes. In an embodiment, the attachment portions are in the form of pins and can be attached to the wear part by any suitable method, for example, by welding. The wear part as described herein may be a cheek plate segment. The roller mill may be a high-pressure grinding roller mill. The roller mill may comprise a first roller and a second roller, wherein the first roller and the second roller are configured to counter-rotate to form a longitudinal nip between the first and second rollers for crushing material, and a wear part as described herein. The invention as set out in the appended claims has been shown and described with reference to embodiments. However, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A wear part, the wear part comprising:a wear body with a wear face and an opposing connection face;a support body with a main axis, a top face, a bottom face, a first side face and a5 second side face, wherein the top face opposes the bottom face, the first side face opposes the second side face, and the first side face and the second side face are substantially perpendicular to both the top face and the bottom face; anda bonding layer between the connection face of the wear body and the top face of the support body;10 wherein the support body comprises an elongate cut-out portion extendingsubstantially transverse to the main axis and between the first side face and the second side face;22 12 25wherein the elongate cut-out portion extends from the top face towards the bottom face; or15 wherein the elongate cut-out portion extends from the bottom face towards the topface; orwherein the elongate cut-out portion extends from the top face to the bottom face.

2. The wear part of claim 1, wherein the support body comprises two or more elongate cut-out portions.

203. The wear part of claim 2, wherein the elongate cut-out portions are spaced approximately equidistant across the wear body.

4. The wear part of any one of the preceding claims, wherein the support body is25 formed of a metal, preferably a steel, more preferably a stainless steel.

5. The wear part of any one of the preceding claims, wherein the elongate cut-outportion is a groove.30 6. The wear part of any one of the preceding claims, wherein the elongate cut-outportion is a slit.

7. The wear part of any one of the preceding claims, wherein the support bodycomprises a plurality of collinear elongate cut-out portions.

8. The wear part of any one of the preceding claims, wherein the support body has a depth dp measured between the top face and the bottom face, and wherein the elongate cut-out portion has a depth ds measured parallel to the depth dp and the depth ds is at least 90% of the depth dp.

9. The wear part of any one of the preceding claims, wherein the elongate cut-out portion has a maximum length ls measured parallel to the top face, and wherein the maximum length ls is at least 75% and at most 98% of the length of the top face.

10. The wear part of any one of the preceding claims, wherein the bonding layer is a braze layer.

11. The wear part of any one of the preceding claims, wherein the wear body and / or the support body are plates.

12. The wear part of any one of the preceding claims, wherein the shape of the wear body substantially corresponds to the shape of the support body.

13. The wear part of any one of the preceding claims, wherein the wear part is a cheek plate segment.

14. The wear part of any one of the preceding claims, wherein the wear face comprises a cemented metal carbide material, preferably a cemented tungsten carbide material.

15. The wear part of any one of the preceding claims, wherein the wear face comprises a superhard material.

16. The wear part of any one of the preceding claims, wherein the wear body comprises or consists of a cemented metal carbide body.

17. The wear part of any one of the preceding claims, wherein the support body further comprises a third side face and a fourth side face, wherein the third side face opposes the fourth side face, and the third side face and the fourth side face are substantially perpendicular to both the top face and the bottom face.

18. The wear part of any one of the preceding claims, wherein the wear part has the shape of isosceles trapezoid when viewed in the plane of the main axis.

19. A roller mill comprising:5 a first roller and a second roller, wherein the first roller and the second roller areconfigured to counter-rotate to form a longitudinal nip between the first and second rollers for crushing material;and a wear part according to any one of the preceding claims.22 12 25

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