Peripheral wear member

Abstract

A peripheral wear member 20 for use with a roller of a dual roller grinding machine (fig. 18). The wear member 20 comprises a central section defining a central axis 59, a bulb portion 40 extending ar

Description

FIELD OF INVENTION The invention relates to improvements in or relating to wear members that are used to provide end-face reinforcement around both peripheral edges of each roller in a dual roller grinding machine, such as a high pressure grinding roller (HPGR). BACKGROUND OF THE INVENTION In HPGR machines, the material to be comminuted is discharged into a gap between two rollers rotating in opposite directions. The material to be comminuted is drawn into the roller gap by the rollers then compacted and crushed. Each roller comprises a central shaft having a radially enlarged central portion (which appears to be cylindrical but actually has a slightly conical shape) on which is mounted a removable tyre. The removable tyre has a large number of blind holes in its outer surface, each of which is populated by a stud protruding from the outer surface of the tyre. The stud is made from a wear resistant material, such as tungsten carbide. Although the studs protect the outer surface of the tyre, the edges of the tyre experience high wear. For this reason, removable end face reinforcements are used at each end of the tyre. The end face reinforcements protect the edges of the rollers from wear. US 7,497,396 to KHD Humboldt Wedag GmbH discloses one type of end face reinforcement. This end face reinforcement 2 is shown in Figs 1A and 1B. End face reinforcement 2 is single piece pre-fabricated body comprising a planar central section 3, a bulb 4 at one end of the planar central section 3 and a pair of wings 5 extending from opposing sides of the planar central section 3. Part of the central section 3 that protrudes beyond the wings 5 forms a foot or base 7. However, this design of end face reinforcement 2 is prone to cracking at the plane where the central section 3 meets the bulb 4, as shown by line 8. To prevent this failure mode, the end face reinforcement 2 was re-designed to create the newer end face reinforcement 12. In this design, as shown in Figs 2A to 2C, the bulb 14 is enlarged and extended towards the wings 15 so that the planar central section 13 is significantly shorter than in the end face reinforcement 2. However, this type of end face reinforcement 12 is prone to cracking where the wings 15 meet the planar central section 13 (essentially the wings 15 shear off), as shown by lines 18. It would be advantageous if the end face reinforcement could be re-designed to reduce the possibility of failure, preferably without enlarging the total volume of the end face reinforcement because highly wear resistant material is very expensive. It is among the objects of an embodiment of the present invention to overcome or mitigate one or more of the above disadvantages or other disadvantages of the prior art, or to provide a useful alternative. SUMMARY This summary is provided to introduce a selection of concepts that are further described in the detailed description below. This summary is not intended to identify indispensable features of the claimed subject matter, nor is it intended for use as an aid in limiting the scope of the claimed subject matter. In this application relative terms are used, such as front, rear, up, down, etc., only for ease of the description and understanding of the embodiments, not by way of limitation. Ordinal numbers (first, second, third, etc.) are assigned arbitrarily herein, and are used to differentiate between parts, and do not indicate a particular order, sequence or importance. According to a first aspect there is provided a peripheral wear member for use with a roller of a dual roller grinding machine, the wear member comprising a central section defining a central axis; a bulb portion extending around a rear part of the central section and defining a neck transverse to the central axis at a front part of the bulb portion, a pair of wings extending laterally from a front part of the central section beyond the bulb portion; and a pair of non-planar transition regions, each region extending from the neck of the bulb portion to one of the wings, to provide distributed stress relief along that transition region. Each non-planar transition region may comprise a transition surface which comprises a curved surface; a plurality of curved surfaces; a polygon surface, a surface comprising one or more planar portions and curved portions; or the like. The transition surface may merge with the bulb portion at one end and a respective wing at an opposite end. Where the transition surface merges with a respective wing, it preferably merges near or at an edge of that wing. Where the transition surface comprises one or more planar portions and curved portions it may comprise a planar portion extending at an acute angle to the central axis and an arcuate surface at each end thereof, wherein one arcuate surface is adjacent to, and merges with, the neck of the bulb portion, and the other arcuate surface is adjacent to, and merges with, a respective wing. The transition surface preferably extends laterally beyond the bulb region. Each non-planar transition region may comprise a transition surface in the form of a curve having a radius between 7mm and 12mm, in some embodiments approximately 9mm. The transition curved surface may comprise a continuous curve (i.e. without any straight or jagged parts). The peripheral wear member may include a planar front surface forwards of the central section. The pair of wings may extend generally orthogonally to the central axis. The bulb portion may comprise a pair of first curved portions at a rear thereof, and a pair of second curved portions adjacent the neck on opposed sides of the central axis. The first curved portions may have the same shape, for example, the same radius. Alternatively, the first curved portions may have a different shape, for example, different radii. Each curved portion may not have a single radius. The first and second curved portions may be connected, or separated, by a third portion, such as a planar portion or another curved portion. The bulb portion may comprise a curved rear surface or rear surface portion with one end of each of the first curved portions connected to one another. Alternatively, or additionally, the bulb portion may comprise a generally flat rear surface or rear surface portion with one end of each of the first curved portions connected to a central planar portion. The peripheral wear member may comprise a base portion at a lower part thereof. The base portion may define a foot surface on an underside thereof. The base portion may protrude below the bulb portion, the wings, and the non-planar transition regions so that the foot surface is operatively below the remainder of the peripheral wear member. The base portion may comprise a central base section having the same or a slightly smaller width than the central section of the peripheral wear member and extending from near a front part generally towards the rear of the peripheral wear member. In some embodiments, the base portion may be a lower portion of the central section, in other embodiments, the base portion may include, but be larger than, the lower portion of the central section. The base portion may further include a bulbous rear portion which extends around a rear part of the central base section . The bulbous rear portion of the base may correspond in shape to the bulb portion of the peripheral wear member. An outer periphery of the bulbous rear portion may be the same or slighter smaller than an outer periphery of the bulb portion (i.e. the bulbous rear portion may be peripherally recessed relative to the bulb portion). The base portion may further comprise a pair of wing supports extending laterally from a front part of the central base section underneath the wings of the peripheral wear member. The wing supports may extend forwards of the central base section. The base portion may further comprise a pair of transition supports extending laterally from the central base section underneath the pair of non-planar transition regions and also extending (axially) from the bulbous rear portion to the wing supports. The transition supports 4 may each comprise a curved surface; a plurality of curved surfaces, a polygon surface, a surface comprising one or more planar portions and curved portions, or the like. In use, the foot surface may abut a support surface of the roller. The roller support surface may be recessed from an arcuate upper surface thereof. The combination of the bulb portion and the non-planar transition regions may have an axial length between 50% and 90% of the total axial length of the wear member, preferably between 60% and 80% of the total axial length of the wear member. The bulb portion may have a circumferential width between 50% and 70%, preferably between 55% and 65%, of the circumferential width of the wear member. The non-planar transition regions may have an axial length between 14% and 30% (preferably between 16% and 24%) of the total axial length of the wear member. The central section may be substantially covered by the bulb portion, the non-planar transition regions, and the wings. The wear member may have a circumferential width between 90% and 110%, preferably between 95% and 100%, of the axial length of the wear member. It is to be appreciated that the axial length of the wear member may decrease during use while the circumferential width may only decrease slightly. The peripheral wear member may comprise an end face reinforcement. It should now be appreciated that this aspect has the advantage that the non-planar transition regions distribute stress therealong to reduce the possibility of breakage, or of shearing along a plane parallel to the lateral wings or along planes perpendicular to the lateral wings. In contrast, the prior art shown in Figs. 1 and 2 have orthogonal planar surfaces that result in stress concentrations, leading to a high risk of premature failure. By ensuring that the wear members retain their structural integrity during operation, operation of a dual roller grinding machine is improved, and roller replacement frequency may be reduced. According to a second aspect there is provided a tyre comprising a plurality of wear members of the first aspect, each mounted around a periphery of the tyre to form a generally continuous reinforcement edge. According to a third aspect there is provided a grinding roller comprising the tyre of the second aspect mounted concentrically mounted on a shaft of the roller. According to a fourth aspect there is provided a high pressure grinding roller machine comprising a pair of grinding rollers according to the third aspect. According to a fifth aspect there is provided a peripheral wear member for use with a roller of a dual roller grinding machine, the wear member comprising a central section defining a central axis; a bulb portion extending around arear part of the central section and defining a neck transverse to the central axis at a front part of the bulb portion; a pair of wings extending transverse to the central axis at a front part of the central section beyond a respective side of the bulb portion, each wing having an upper surface extending convergently from a region laterally outside a respective side of the bulb portion to the neck, thereby providing distributed stress relief therealong. As used herein, “extending convergently” means that the upper surface is closer to the neck, in the direction of the central axis, as it extends orthogonally towards the central axis. The upper surface may have any convenient shape, for example, an angled planar surface (not parallel or orthogonal to the central axis), a curved surface, or the like. Each wing may comprise a continuously increasing thickness towards a central axis. Each wing upper surface curve may start extending convergently at or near an end surface of the wing. Each wing upper surface may have an axial length between 10% and 40% of the total axial length of the wear member. BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figs. 1A and 1B are perspective and plan views, respectively, of a prior art peripheral wear member; Figs. 2A to 2C are underside and front perspective views and a plan view, respectively, of another prior art peripheral wear member; Figs. 3A to 3C are front, rear, and underside perspective views of a peripheral wear member according to one embodiment of the invention; Fig. 4 is an underside plan view of the peripheral wear member of Fig. 3; Fig. 5 is a sectional view from the rear along line 5-5 of Fig. 4; Fig. 6 is an elevation view of the peripheral wear member of Fig. 3; Fig. 7A is a sectional underside plan view along line 7A-7A of Fig. 6; Fig. 7B is an enlarged view of part of the sectional underside plan view of Fig 7A; Fig. 8 is a top plan view of the peripheral wear member of Fig. 3; Fig. 9 is an rear view of the peripheral wear member of Fig. 3; Figs. 10A to 10C are front, rear, and underside perspective views of a peripheral wear member according to another embodiment of the invention; Fig. 11 is a rear view of the peripheral wear member of Fig. 10; Fig. 12 is a underside perspective view of a peripheral wear member according to another embodiment of the invention; Fig. 13 is a detailed perspective view of a profiled peripheral end of a roller; Figs. 14 to 16 are detailed perspectives views showing three different stages in which a peripheral wear member of Fig. 3 is inserted into one of the recesses in the profiled end; Fig. 17 is a detailed perspective view of a profiled peripheral end of a roller populated with adjacent peripheral wear members to form a nearly continuous wear surface on a top and side of the roller; Fig. 18 is a schematic perspective view of a tyre including a profiled ring at each end, populated with a plurality of circumferentially adjacent peripheral wear members, such as those of Fig. 3; and Figs. 19A and 19B are two graphs illustrating the two prior art end face reinforcement designs and the peripheral wear member of Fig. 3, illustrating x and y positions in Fig. 18A and stress distribution, in Fig. 18B, for the three designs. DETAILED DESCRIPTION OF EMBODIMENTS Reference is now made to the drawings, and particularly to Figs. 3 to 9, which are various views of a first embodiment of a peripheral wear member 20, in the form of an end face reinforcement, for use with a roller of a dual roller grinding machine. The wear member 20 has been designed to have approximately the same volume as the end face reinforcement 10 shown in Figs. 2A to 2C, thereby ensuring that the cost of the wear members is not increased by this new design. Peripheral wear member 20 extends in three directions. Wear member 20 has a height (Rh) in a radial direction (indicated by arrows 22 in Figs. 3), a length (Al) in an axial direction (shown by arrows 24 in Figs. 3), and a width (Cw) in a circumferential direction (shown by arrows 26 in Figs. 3). Radial, axial, and circumferential relate to directions of a roller on which this wear member 20 may be mounted. The peripheral wear member 20 comprises a central section 32 (best seen in Figs. 5 and 7). The peripheral wear member further comprises a base 34 defining a foot surface 36 (best seen in Fig. 30) on a lower portion thereof. In this embodiment, the base 34 is a lower portion of the central section 32. In other embodiments, the base 34 may be larger or smaller than the central section 32. The peripheral wear member 20 further comprises a bulb portion 40 extending around a rear part of the central section 32 above the base 34; and a pair of wings 42 extending laterally (in a circumferential direction, as shown by arrows 26) from a forward part of the central section 32 above the base 34. In this embodiment, the base 34 is less than 15% of the total radial height of the peripheral wear member 20. The bulb portion 40 narrows (in the circumferential direction) to a neck 43 at its furthest forward part and in front of its widest part 44 (the bulb portion width) (best seen in Fig. 8). The peripheral wear member 20 further comprises a pair of non-planar transition regions 46, each region 46 extending from the bulb portion 40 (in this embodiment, from the neck 43) to one of the wings 42, to provide distributed stress relief along that transition region 46, as will be described in more detail below. It is to be appreciated that in other embodiments the transition regions 46 may have a different shape to that shown in the drawings. The bulb portion 40, the central section 32, the wings 42, and the non-planar transition regions 46 define an upper surface 50 opposite the foot surface 36. In this embodiment the upper surface 50 is generally planar (and generally parallel to the foot surface 36), but may have a different configuration for example the upper surface may be angled relative to (and sloping towards) the foot surface 36 from its rear portion to its front portion. In this embodiment, the distance between the foot surface 36 and the upper surface 50 (in other words the radial height Rh of the wear member 20) is approximately 40mm; although in other embodiments a different height may be selected. In alternative embodiments the distance between the foot surface 36 and the upper surface 50 at the rear of the wear member 20 may be larger than the distance between the foot surface 36 and the upper surface 50 at the front of the wear member. The wings 42 and the base 34 define a front surface 52, which, in this embodiment, is also generally planar, but may have a different configuration in other embodiments. The front surface 52 is transverse (in this embodiment, generally perpendicular) to the upper surface 50. In an alternative embodiment where the upper surface 50 is angled relative to (and sloping towards) the foot surface, the front surface 52 is not generally perpendicular to the upper surface 32 but rather transverse (or generally perpendicular) to the foot surface 36. The peripheral wear member 20 defines an arcuate surface 54 extending between the upper surface 50 and the front surface 52. The arcuate surface 54 helps to prevent chipping of, or other damage to, the wear member 20 when in use. The bulb portion 40 comprises a central section 56 (which is generally planar) and a pair of side surfaces 58 extending axially from the central section 56 to the neck 43. In this embodiment, the bulb portion 40 is symmetrical about a centreplane 59 (best seen in Fig. 3A), but in other embodiments, the bulb portion 40 may be asymmetrical. The bulb portion 40 extends radially from the upper surface 50 to a lower part of the central section 32 where the base 34 starts. In this embodiment, the central section 56 is generally planar, but in other embodiments, it may be curved (optionally symmetrical about the centreplane 59). Each side surface 58 comprises a convex portion 62, a planar portion 64, and a concave portion 66 which meets the neck 43. Although in other embodiments, the planar portion 64 may not be used, i.e. the convex portion 62 may blend into the concave portion 66. The concave portions 66 comprise a first radius (also referred to as R1), which in this embodiment is approximately 10mm (but a different size of radius may be used in other embodiments). In this embodiment, the distance between the front surface 52 and the central portion 56 (of the bulb portion 40) (in other words, the axial length Al) is approximately 43mm; although in other embodiments a different distance may be selected. The non-planar transition regions 46 are located on either side of the central section 32. As best seen in Figs. 7B and 8, each non-planar transition region 46 extends from the neck 43 (shown by broken line labelled NL in Fig. 7B) to a portion of the respective lateral wing 42 (shown by the intersection of broken lines labelled US and LW in Fig. 7B). In this embodiment, the non-planar transition regions 46 comprise a transition surface 68. In this embodiment, the transition surface 68 is arcuate and has a radius (also referred to as R2). The centre of the radius (R2) is at the intersection of lines US and NL in Fig. 7B. In Fig. 7A, broken lines CS1 and CS2 indicate the area at which the central section 32 merges with other portions of the wear member 20. Broken lines CS1 and CS2 are substantially parallel to the centreplane 59. Broken lines NL and LW indicate the area at which each non-planar transition region 46 merges with the bulb portion 40 (the concave portion 66 of the bulb portion 40 at the neck 43 (line NL)) and the lateral wings 42 (LW), respectively. Broken lines NL, and LW are substantially perpendicular to centreplane 59. The central section 32 is defined: circumferentially by the portion between CSC1 and CSC2 (see Fig. 7A), axially by the portion between lines CSA1 and CSA2 (see Fig. 6), and radially by the portion between lines CSR1 and CSR2 (see Fig. 5). It will be appreciated that this definition is primarily to aid clarity and understanding, the boundaries of the central section 32 could be moved to some extent. The left-side (looking at Fig. 7A) non-planar transition region 46 comprises the portion outside (to the left of) line CSC1 and between lines NL and LW. Similarly, the right-side (looking at Fig. 7A) non-planar transition region 46 comprises the portion outside (to the right of) line CSC2 and between lines NL and LW. In this embodiment, the two non-planar transition regions 46 are identical (mirror images of each other) but in other embodiments, each non-planar transition region 46 may be different from the other non-planar transition region 46. In this embodiment, the concave portions 66 has a radius (R1) larger than the transition surface 68 radius (R2). In particular, in this embodiment, the concave portions 66 have a radius (R1) of approximately 10mm (plus or minus 10%); whereas the transition surface 68 has a radius (R2) of approximately 9mm (plus or minus 10%). As best seen in Fig. 7B, the concave portions 66 and transition surfaces 68 meet and blend at the neck 43 (see region labelled by broken line NL). As best seen in Figs. 3C and 9, the foot surface 36 is lower than most of a lower surface 72 (best seen in Fig. 5) of each of the lateral wings 42, although lower surface 72 includes an arcuate portion that merges with the foot surface 36. The difference in height between the most lateral part of the lower surface 72 and the foot surface 36 is approximately 5mm. Each of the lateral wings 42 has an end surface 74 transverse to the front surface 52. In this embodiment, the end surfaces 74 are sloping inwards (i.e. towards the centreplane 59) as they extend from the upper surface 50 to the base 34. This inward slope is relatively small, for example, at an angle of less than 5 degrees. In this embodiment, the distance between the end surfaces 74 is approximately 39mm at the upper surface 50 and approximately 37mm at the base 34; although in other embodiments a different distance may be selected, or the end surfaces may be parallel. The base 34 defines a chamfer portion on all sides of the foot surface 36 such that the base 34 extends outwards from the foot surface 36 to a lower part of the front surface 52, to a lower part of the wing end surfaces 74, to a lower part of the bulb portion 40, and to a lower part of the non-planar transition regions 46. In this embodiment, the peripheral wear member 20 comprises a prefabricated unitary piece so that there is no join or connection between the central section 32, the bulb portion 40, the wings 42, and the non-planar transition regions 46. Being a unitary piece means that the different portions are identified for clarity and ease of description only. An alternative description of the peripheral wear member 20 (a different way of describing the same shape) is that the bulb portion 40 extends to the neck 43, but instead of a pair of non-planar transition regions 46 extending from the neck 43 to the wings 42, each wing includes an upper surface (equivalent to transition surface 68) extending convergently from a region laterally outside a respective side of the bulb portion 40 (shown by broken line BW in Fig 7B) to the neck 43 (shown by broken line NL in Fig 7B). In this embodiment, the upper surface 68 starts at a region on the wings 42 near (but spaced from) the end surface 74 (the start is shown by the intersection of broken lines US and LW in Fig 7B). In other embodiments, the upper surface 68 may start at (rather than just near) the end surface 74. As best seen in Figs. 10-11, a second embodiment of a peripheral wear member 220 is shown having a different base portion 234 and foot surface 236 to that of the peripheral wear member 20 while the other features remain similar. The base portion 234 comprises a central base section 235 having a similar or slightly smaller width than the central section 32 and which extends, in a similar way to the central section 32, from the front portion generally towards the rear of the wear member 220. As shown in Fig. 10C the central base portion 235 is indicated by the broken lines. The base portion 234 further includes a bulbous rear portion 278 which extends around a rear part of the central base section 235. The bulbous rear portion 278 corresponds to the bulb portion 40 of the peripheral wear member 20. The bulbous rear portion 278 has an outer periphery which is smaller than the outer periphery of the bulb portion 40. In this embodiment, the bulbous portion 278 includes a central portion 280 which is generally planar, and a pair of first curved portions 282 (on each side of the central portion 280) having an arcuate shape. In this embodiment, each first curved portion 282 has the same shape as the other, but in other embodiments, one side portion may have a different shape to the other side portion. The bulbous portion 278 further defines planar portions 284 which extend from the first curved portions 282 towards a pair of second curved portions 286. The base portion 234 further comprise a pair of wing supports 288 which extend laterally from opposed sides of a front portion of the central base section 235 generally towards the end surface 74 of the lateral wings 42. In this embodiment, the wing supports 288 each comprise a generally planar portion 290 (see Fig. 10B) extending from the front surface 252 rearwards and an arcuate portion 292 extending from the generally planar portion 290 rearwards. The front portion 252 is similar to front portion 52 but the lower portion (defined by the generally planar portions 290) of front portion 252 is radially higher than the corresponding portion of the front portion 52. The base portion 234 further includes a pair of transition surfaces 294 which extend from the bulbous rear portion 278 towards the wing supports 288. In this embodiment, the transition surfaces 294 extend from the second curved portions 286 towards the arcuate portion 292 of the wing supports 288. The transition surfaces 288 may each comprise a curved surface; a polygon surface, a surface comprising one or more planar portions and curved portions. In an alternative embodiment the transition surfaces include an arcuate portion adjacent the arcuate portion of the wing support and a generally planar portion adjacent the second curved portions of the bulbous rear portion 278. The base portion 234 11 defines a chamfer portion on all sides of the foot surface 236 extending to the surrounding periphery of the base portion 234. The advantages of the peripheral wear member 220 compared with peripheral wear member 20 are that the top wear part (upper surface 50 and part of front surface 54) adjacent the wing portions 42 is supported in height to minimize the stress in the peripheral wear member 220 (caused by crushing forces) to prevent chipping and breaking of the peripheral wear member 220. Furthermore, stress in the protruding tongues 122 of the tyre caused by crushing forces is reduced by restricting axial movement of the peripheral wear member 220 due to the bulbous rear portion 278 of the base portion 234 being held in position by the tyre over the toral radial heigh of the bulbous rear portion 278. By reducing the stress in the protruding tongues 122 deformation thereof is prevented which prevents dislocation of the peripheral wear member 220 from the tyre.. Both mentioned advantages are especially beneficial when the crushing surface (outer surface 100 and protruding carbide studs) of the tyre are worn. The difference in height between a most lateral part of a lower surface 272 and the foot surface 236 is approximately 13,5mm. In this embodiment, the base portion 234 is less than 30% of the total radial height of the peripheral wear member 220. As best seen in Figs. 12, a third embodiment of a peripheral wear member 320 is shown having a different base portion 334 and foot surface 336 to that of the peripheral wear member 20 and 220 while the other features remain similar. The base portion 334 comprises a central base section 335 having a similar or slightly smaller width than the central section 32 and which extends, in a similar way to the central section 32, from the front portion generally towards the rear of the wear member 320. As shown in Fig. 12 the central base portion 335 is indicated by the broken lines and comprises a curved rear surface 337. The base portion 334 further comprise a pair of wing supports 388 which extend laterally from opposed sides of a front portion of the central base section 335 generally towards the end surface 74 of the lateral wings 42. In this embodiment, the wing supports 388 each comprise a generally planar portion 390 (see Fig. 12) extending from the front surface 352 rearwards and an arcuate portion 392 extending from the generally planar portion 390 rearwards. The front portion 352 is similar to front portion 252. The base portion 334 further includes a pair of transition surfaces 394 which extend from the central section 335 towards the wing supports 388. In this embodiment, the transition surfaces 394 extend from central section 335 towards the arcuate portion 392 of the wing supports 388. The transition surfaces 388 may each comprise a curved surface; a polygon surface, a surface comprising one or more planar portions and curved portions. The 12 base portion 334 defines a chamfer portion on all sides of the foot surface 336 extending to the surrounding periphery of the base portion 334. The difference in height between a most lateral part of a lower surface 372 and the foot surface 336 is approximately 13,5mm. In this embodiment, the base portion 334 is less than 30% of the total radial height of the peripheral wear member 320. The advantages of the peripheral wear member 320 compared with peripheral wear member 20 is that the top wear part (upper surface 50 and part of front surface) adjacent the wing portions 42 is supported in height to minimize the stress in the peripheral wear member 320 (caused by crushing forces) to prevent chipping and breaking of the peripheral wear member 320. In these embodiments, the peripheral wear member 20 comprises tungsten carbide, although in other embodiments different high wear material may be used, such as silicon carbide, a cobalt based alloy (such as Stellite), cobalt-chromium alloys, a high density ceramic, or another high wear alloy. Peripheral wear members 20 are used to provide a wear resistant peripheral surface for grinding rollers, as will now be described with reference to Figs. 12 to 16. As is known, a grinding roller for an HPGR is generally cylindrical and includes an arcuate outer surface populated with tungsten carbide studs protruding therefrom, and terminating at each axial end. Typically, the outer surface is provided as a removable steel tyre (approximately 100mm thick) that is mounted around a shaft. A grinding roller according to one embodiment (part of which is shown in each of Figs. 13 to 17) includes a removable tyre. In this embodiment, the tyre comprises steel, but other materials may be used in other embodiments. The tyre includes an arcuate outer surface 100 (which is populated with tungsten carbide studs protruding therefrom, but these are not shown for clarity) and defines a profiled ring 102 at each axial end (only one of which is shown in Figs. 13 to 17, but the other end is identical other than being a mirror image thereof). The profiled ring 102 defines an upper surface 104 raised by a small amount (a few mm) relative to most of the tyre outer surface 100. The tyre also defines a support surface 106 having a smaller radius than the arcuate outer surface 100 and protruding axially from the profiled ring 102. The support surface 106 comprises a series of circumferentially spaced foot supports 108 and wing spacings 110, with each foot support 108 being adjacent two wing arrangements 110 (and vice versa). The foot supports 108 are recessed relative to the wing arrangements 110 by a very small distance (e.g. 1mm). The foot supports 108 are also recessed relative to the upper surface 104 by an amount equal to the radial height (Rh) of the wear member 20. The difference in height between the foot surface 36 and an uppermost part of the lateral wing lower surfaces 72 in this embodiment is approximately 4.9mm. The profiled ring 102 has a generally tongue and groove appearance, and defines a plurality of circumferentially spaced recesses 120 (the grooves) alternating with protruding tongues 122. The combination of a recess 120 and half (on a circumferential basis) of each adjacent tongue 122 provide a wear member locating feature 126. The wear member locating feature 126 is illustrated in Fig. 13 between broken lines 128 and 130. Each wear member locating feature 126 is complementary to the bulb portion 40, the wings 42, and the non-planar transition regions 46. This allows each peripheral wear member 20 to be inserted into a wear member locating feature 126 (stages of which process are shown in Figs. 14 to 16 for one wear member 20). Half of each adjacent tongue 122 encloses the neck 43 of a wear member therebetween to prevent the wear member 20 from moving axially out of the profiled ring 102. Once all of the peripheral wear members 20 have been inserted, the profiled ring 102 is fully populated (as shown in Fig. 17), thereby providing high wear resistance in both the radial and axial directions at each end of the grinding roller. Each recess 120 partially surrounds the neck 43 of a wear member 20 and thereby retains the wear member 20 in position. The spacing of the wear member locating features 126 is selected to be slightly larger (but only by approximately 1mm) than the distance between lateral wing end surfaces 74 of a wear member 20. This ensures that the wear members 20 form an almost continuous ring around the periphery of a grinding roller tyre. It is to be appreciated that in another embodiment the wear member 220 could be used. In such an embodiment the support surface comprising the spaced foot supports and wing supports would differ to accommodate the base portion 234 and foot surface 236 of the wear member 220. In such an embodiment, the foot supports may be recessed relative to the wing arrangements by a larger distance. A grinding roller tyre 150 is schematically illustrated in Fig. 18 in perspective view from one end 152a thereof. The second end 152b is identical to the first end 152a, so will not be described. The tyre 150 has a profiled ring 102 at each end 152a,b, populated with wear members 20 as shown in detail in Fig. 14 (not shown in Fig. 18 for clarity). The tyre 150 includes an internal machined surface 154 defining a frusto-conical bore extending the axial length (direction 24) of the tyre 150. The angle of slope of the frusto-conical bore is very small (typically less than four degrees). The machined surface 154 mounts on an HPGR shaft as an interference fit. An HPGR (not shown) includes two such tyres 150 radially spaced from each other. Reference is now made to Figs. 19A and 19B, which are two graphs relating to the two prior art end face reinforcement designs 2, 12 and the peripheral wear member 20 of Fig. 3. Fig. 19A illustrates relative axial and circumferential positions of some external surfaces to the right of the centreplane 59 and above the wing 42, and Fig. 19B illustrates stress distribution as a function of axial position for each of the three designs (but only the portions of those designs illustrated in Fig. 19A). In Fig. 19A line 180 corresponds to the wear member 20, line 184 corresponds to the prior art end face reinforcement 12, and line 188 corresponds to the prior art end face reinforcement 2. It is clear from Fig. 19B that the stress concentration for end face reinforcement 2 (shown by line 190) peaks at the central section 3 but is also high at a location close to the wing, whereas the stress concentration for end face reinforcement 12 (line 186) is reduced at the corresponding region (the central section 13), but is still relatively high (unchanged) at a location close to the wing. This explains the breaking failure mode for end face reinforcement 2 and also for end face reinforcement 12. It is also clear that the stress concentration for wear member 20 (line 182) is more linear than for end reinforcement 12, without any significant stress peaks. Wear member 20 is therefore less likely to exhibit the breaking failure modes experienced by the prior art end face reinforcements 2, 12. This demonstrates that a relatively small change in design can achieve significant performance improvements, and therefore result in significant cost savings. In the foregoing description of certain embodiments, specific terminology has been used for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes other technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "upper" and "lower", "above" and "below" and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms, nor to imply a required orientation of the wear member. The word “or" is used to indicate that one or more of the words listed may be present, unless the context requires the disjunctive use. In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of’. A corresponding meaning is to be attributed to the corresponding words “comprise", "comprised" and "comprises" where they appear. The preceding description is provided in relation to several embodiments which may share common characteristics and features. It is to be understood that one or more features of any one embodiment may be combined with one or more features of the other 15 embodiments. In addition, any single feature or combination of features in any of the embodiments may constitute additional embodiments. In addition, the foregoing describes only some embodiments of the inventions, and alterations, modifications, additions and / or changes can be made thereto without departing from the scope of the disclosed embodiments, the embodiments being illustrative and not restrictive. List of reference numerals: End face reinforcement 2 Planar central section 3 Bulb 4 Pair of wings 5 Foot or base 7 Shear off line 8 Newer end face reinforcement 12 Planar central section 13 Bulb 14 Wings 15 Shear off lines 18 Peripheral wear member 20, 220 Radial height (Rh) 22 Axial length (Al) 24 Circumferential width (Cw) 26 Central section (of peripheral wear member) 32 Base (of central section) 34, 234, 334 Foot surface (of base) 36, 236, 336 Bulb portion 40 Wings 42 Neck 43 Bulb portion width 44 Non-planar transition regions 46 Upper surface 50 Front surface 52, 252 Arcuate surface 54 Central portion (of bulb portion) 56 Side surfaces (of bulb portion) 58 Centreplane 59 Convex portion (of bulb portion) 62 Planar portion (of bulb portion) 64 Concave portion (of bulb portion) 66 Transition (upper) surface (radius R2) (of non-planar transition region) 68 Lower surface (of lateral wing) 72, 272, 372? End surface (of lateral wing) 74 Arcuate outer surface (of grinding roller) 100 Profiled ring 102 Upper surface (of profiled ring) 104 Support surface (of roller) 106 Foot supports (of support surface) 108 Wing supports (of support surface) 110 Recesses (of profiled ring) 120 Tongues (of profiled ring) 122 Wear member locating feature (of profiled ring) 126. Grinding roller tyre 150 End (of tyre) 152a,b Internal machined surface (of tyre) 154 Central base section 235, 335 Bulbous rear portion 278 Central portion (of bulbous portion) 280 First curved portion (of bulbous portion) 282 Planar portions (of bulbous portion) 284 Second curved portion (of bulbous portion) 286 Wing support (of base portion) 288. 388 Planar portion (of wing support) 290, 390 Arcuate portion (of wing support) 292, 392 Transition surfaces (of base portion) 294, 394 Curved rear surface (of central base section) 337

Claims

1. An end-face reinforcement member for use with a roller of a dual roller grinding machine to protect edges of the roller from wear, the end-face reinforcement member comprising:a central section defining a central axis;a bulb portion extending around a rear part of the central section and which narrows toa neck transverse to the central axis at a front part of the bulb portion, the neck being axially spaced from a front of the end-face reinforcement member and extends in a radial direction;a pair of wings extending laterally from a front part of the central section beyond the bulb portion;first and second wear surfaces which are transversely orientated relative to one another; anda pair of non-planar transition regions, each region extending from the neck of the bulb portion to one of the wings, to provide distributed stress relief along that transition region.

2. An end-face reinforcement member according to claim 1, wherein the first and second wear surfaces are defined by an upper surface and a front surface of the end-face reinforcement member respectively.

3. An end-face reinforcement member according to claim 1 or 2, wherein each non-planar transition region comprises a transition surface which comprises a curved surface, a plurality of curved surfaces, a polygon surface, a surface comprising one or more planar portion and curved portion wherein the transition surface merges with the bulb portion at one end and merges a respective wing.

4. An end-face reinforcement member according to claim 1 or 2, wherein each non-planar transition surface comprises a transition surface in the form of a curve having a radius between 7mm and 12mm.

5. An end-face reinforcement member according to claim 1 or 2, wherein the transition surface comprises one or more planar portion and curved portion the transition surface comprise a planar portion extending at an acute angle to the central axis and an arcuate surface at each thereof, wherein one arcuate surface is adjacent to, and merges with, the neck of the bulb portion, and the other arcuate surface is adjacent to, and merges with, a respective wing.26 02 256. An end-face reinforcement member according to claim 4, wherein the bulb portion comprises a pair of first curved portions at a rear thereof, and a pair of second curved portions adjacent the neck on opposed sides of the central axis.

7. An end-face reinforcement member according to claim 6, wherein a radius of 5 the second curved portion is larger than the radius of the transition surface.

8. An end-face reinforcement member according to any preceding claim, which comprises a base portion at a lower part thereof, and protruding below the bulb portion, the wings, and the non-planar transition regions so that a foot surface of the base portion is operatively below the remainder of the peripheral wear member.10 9. An end-face reinforcement member according to claim 8, wherein the baseportion comprises a central base section having the same or a slightly smaller width than the central section of the peripheral wear member and extending from near a front part generally towards the rear of the peripheral wear member.

10. An end-face reinforcement member according to claim 9, wherein the base 15 portion includes a bulbous rear portion which extends around a rear part of the central base section.

11. An end-face reinforcement member according to claims 9 or 10, wherein the base portion includes a pair of wing supports extending laterally from a front part of the central base section underneath the wings of the peripheral wear member.20 12. An end-face reinforcement member according to claims 11, wherein the baseportion comprises a pair of transition supports extending laterally from the central base section underneath the pair of non-planar transition regions and also extending (axially) from the bulbous rear portion to the wing supports.

13. An end-face reinforcement member according to any preceding claim, wherein25 the combination of the bulb portion and the non-planar transition regions has an axial lengthbetween 50% and 90% of the axial length of the wear member.

14. An end-face reinforcement member according to any preceding claim, wherein the bulb portion has a circumferential width between 50% and 70% of the total circumferential width of the wear member.30 15. An end-face reinforcement member according to any preceding claim, whereinthe non-planar transition region has an axial length between 14% and 30% of the axial length of the wear member.

16. A tyre for mounting around a shaft to provide a grinding roller, comprising axially spaced ends, each end comprising a plurality of end-face reinforcement members according to any preceding claim and mounted around a periphery of the tyre to form a generally continuous reinforcement edge for resisting axial and radial wear thereof.5 17. A grinding roller comprising a tyre according to claim 16 concentrically mountedon a shaft.

18. A high pressure grinding roller machine comprising a pair of grinding rollers according to claim 17.26 02 25

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