Disc cutter

Abstract

The present disclosure relates to a disc cutter (18) comprising a cutter body, a plurality of tool holders (24), and a plurality of cutting elements (22) mounted to the tool holders. The tool holders and cutting elements are arranged in at least one group around the cutter body, each group comprising two or more cutting elements and two or more tool holders arranged in a predetermined configuration order.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a disc cutter for use in a mining or trenching machine. In particular, the invention relates to a disc cutter having cutting elements comprising super-hard material such as polycrystalline diamond. BACKGROUND

[0002] There are many types of rock formation throughout the world as large deposits, commonly referred to as slabs. A variety of different types of extraction equipment are deployed in surface quarries in order to extract slabs from the ground. The slabs are acquired using specialist equipment, typically large vehicles with very high power which drag them from their location. The rock slabs can weigh up to 40 tonnes (40,000 kg). Processing such as polishing can be carried out on site, or alternatively, the slabs can be transported off site to be cut into appropriately sized pieces for domestic and industrial use.

[0003] The same equipment used on the surface can not always be directly usable in the confined spaces of an underground mine.

[0004] It is an object of the present invention to provide a compact and versatile cutting assembly to facilitate the extraction of geometric or non-geometric shaped blocks of a particular rock formation and which can be used on the surface or underground.

[0005] Applicant’s co-pending applications WO 2019 / 180164 Al, WO 2019 / 180169 Al, WO 2019 / 180170 Al disclose a cutting assembly comprising a disc cutter movable between a horizontal cutting orientation and a vertical cutting orientation. Cylindrical cutting elements and a corresponding number of tool holders are arranged and positioned around the circumferential surface of the disc cutter. Each tool holder is at least partially laterally offset with respect to the circular body. A disadvantage of this arrangement is that still a considerable cutting force is required to cut through the rock formation.

[0006] It is an object of the present invention to provide a cutting assembly with reduced cutting force. SUMMARY

[0007] According to a first aspect of the present invention, there is provided a disc cutter comprising a cutter body, a plurality of tool holders, and a plurality of cutting elements mounted to the tool holders, wherein the tool holders and cutting elements are arranged in at least one group around the cutter body, each group comprising two or more tool holders and two or more cutting elements, the two or more cutting elements being arranged on the tool holders in a predetermined configuration order, the tool holders all facing in the same direction.

[0008] The disc cutter can comprise a plurality of groups around the circumferential surface of the cutter body.

[0009] The plurality of groups can be identical. Alternatively, the plurality of groups can be different.

[0010] The disc cutters may comprise three or more tool holders in a set.

[0011] The disc cutters can be included in a set of four tool holders.

[0012] The disc cutter can comprise a single cutting element in one or more tool holders. In this embodiment, the single cutting element is optionally mounted centrally on the tool holder.

[0013] The disc cutter may include two cutting elements in one or more tool holders. In such an embodiment, the two cutting elements may be arranged side by side adjacent to each other on the tool holder. Alternatively, the two cutting elements may be arranged spaced apart from each other on the tool holder. Optionally, the two cutting elements may be spaced apart with a groove therebetween.

[0014] The cutting element may be a polycrystalline diamond compact (PDC). Optionally, the PDC has a triple chamfer.

[0015] Preferably, the tool holder comprises a body portion and a pair of spaced apart legs.The tool holder optionally tapers inwardly from a first end adjacent the or each cutting element towards a second end.

[0016] The cutter body may include a series of slots.

[0017] According to a second aspect of the present invention, a trencher is provided that includes the disc cutter according to the first aspect. Optionally, the diameter of the cutter body is in the range of 900 mm to 1200 mm. Preferably, the thickness of the cutter body is in the range of 20 mm to 30 mm. Preferably, the effective cutting width of the disc cutter is approximately 60 mm.

[0018] According to a third aspect of the present invention, a disc-shaped tool is provided, which includes a tool body, a plurality of tool holders, a plurality of cutting elements, and at least one cutting element mounted on at least one tool holder, wherein the plurality of tool holders and the plurality of cutting elements are arranged along the peripheral surface of the tool body, and the tool holders and the cutting elements are arranged in at least one group around the tool body, each group including two or more cutting elements and two or more tool holders arranged in a predetermined configuration order, wherein the tool body includes at least one lightweight hole.

[0019] The disc cutter includes a plurality of groups around the outer peripheral surface of the cutter body.

[0020] The multiple groups may be the same. Alternatively, the multiple groups may be different.

[0021] The disc cutters may comprise three or more tool holders in a set.

[0022] The disc cutters can be included in a set of four tool holders.

[0023] The disc cutter can comprise a single cutting element in one or more tool holders. In this embodiment, the single cutting element is optionally mounted centrally on the tool holder.

[0024] The disc cutter may include two cutting elements in one or more tool holders. In such an embodiment, the two cutting elements may be arranged side by side adjacent to each other on the tool holder. Alternatively, the two cutting elements may be arranged spaced apart from each other on the tool holder. Optionally, the two cutting elements may be spaced apart with a groove therebetween.

[0025] The cutting element may be a polycrystalline diamond compact (PDC). Optionally, the PDC has a triple chamfer.

[0026] Preferably, the tool holder comprises a body portion and a pair of spaced apart legs.The tool holder optionally tapers inwardly from a first end adjacent the or each cutting element towards a second end. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:

[0028] Figure 1 is a schematic plan view of an underground mine incorporating a first embodiment of a cutting assembly as part of a longwall mining system and particularly illustrating the cutting assembly in a horizontal orientation;

[0029] Figure 2 yes Figure 1 A schematic end view of a longwall mining system;

[0030] Figure 3 is a schematic plan view of an underground mine incorporating a second embodiment of a cutting assembly as part of a longwall mining system and particularly illustrating the cutting assembly in a vertical orientation;

[0031] Figure 4 yes Figure 3 A schematic end view of a longwall mining system;

[0032] Figure 5 is a perspective view of a disc cutter in a first embodiment of the present invention;

[0033] Figure 6 is formed Figure 5 a side view of a first embodiment of a tool body of a portion of a disc-shaped tool;

[0034] Figure 7 is formed Figure 5 A front view of a set of tool holders and cutting elements of a portion of a disc cutter;

[0035] Figure 8 yes Figure 5 An exploded partial view of a disc cutter;

[0036] Figure 9 yes Figure 5 A front view of a disc cutter;

[0037] Figure 10 yes Figure 5 A top view of a disc cutter;

[0038] Figure 11 yes Figure 5 A perspective view of a cutting element;

[0039] Figure 12 yes Figure 7 A side view of a tool holder with cutting elements;

[0040] Figure 13 is Figure 5 Schematic diagram of computer simulation of rock being cut by a disc cutter;

[0041] Figure 14 It includes Figure 5 A perspective view of a trencher with a disc cutter;

[0042] Figure 15 yes Figure 15 A top view of a trenching machine;

[0043] Figure 16 is formed Figure 5 a side view of a second embodiment of a tool body of a portion of a disc-shaped tool;

[0044] Figure 17 is formed Figure 5 a side view of a third embodiment of a tool body of a portion of a disc-shaped tool;

[0045] Figure 18 is formed Figure 5 a side view of a fourth embodiment of a tool body of a portion of a disc cutter; and

[0046] Figure 19 is formed Figure 5 Side view of a fifth embodiment of a tool body of a portion of a disc shaped tool.

[0047] In the drawings, like components are designated with like reference numerals. DETAILED DESCRIPTION

[0048] First reference Figures 1-2 , a cutting assembly for cutting into a natural formation 2 in layers underground is generally indicated at 10.

[0049] The cutting assembly forms part of a longwall mining system 1 commonly found in underground mines. An alternative to known shearer technology, the cutting assembly operates on a mine floor 4 within a series of adjustable roof supports 6. As the shearer advances in the mining direction, the roof supports 6 are positioned to support the mine roof 8 directly behind the shearer. Behind the roof supports 6, the mine roof 6 collapses in a relatively controlled manner. Typically, a collection arm collects the mined rock at the cutting face and transfers it to a conveyor system for subsequent removal from the mine.

[0050] like Figure 1 and Figure 2 As shown, the cutting assembly 10 includes a base unit 12, a pair of spaced apart support arms 14 extending from the base unit 12, a drive spindle 16 extending between the pair of movable support arms 14 and rotatably mounted thereto, and a plurality of disc cutters 18 fixed about the drive spindle 16.

[0051] exist Figure 3 and Figure 4 In the second embodiment shown, a single support arm 14 extends from the base unit 12. A drive spindle 16 is centrally supported by the single support arm 14, and a plurality of disc cutters 18 are mounted on the drive spindle 16, distributed on either side of the single support arm 14.

[0052] In an alternative embodiment not shown, only a single disc cutter 18 is used.

[0053] Preferably, the or each disc cutter 18 is mounted centered about the drive spindle 16 (i.e., centrally). However, this is not required, and the or each disc cutter 18 may alternatively be mounted offset from being centered about the drive spindle 16. Alternatively, a combination of these two arrangements may be used instead. For example, when a plurality of disc cutters 18 are used in series (i.e., in parallel adjacent to one another along the drive spindle 16), alternating disc cutters 18 may be mounted centrally about the drive spindle 16. The centers of the remaining disc cutters 18 may be radially offset from the position in which the disc cutters 18 are mounted about the drive spindle 16. Other combinations are contemplated.

[0054] Base unit 12 serves as a transport system for disc cutters 18. Base unit 12 is movable to move disc cutters 18 into and out of a working position proximate to the rock formation 2 to be cut. The speed at which base unit 12 is moved proximate to the rock formation 2 is one of several variables that determine the feed rate of cutting assembly 10 into the rock formation 2. Base unit 12 (along with roof support 6) can also be moved laterally along the longwall of the rock formation 2 to be mined, from left to right, and vice versa.

[0055] Each support arm 14 is configured to be movable to a first cutting orientation and a second cutting orientation. Figure 1 and Figure 2 As best seen, the drive spindle 16 is horizontal. Therefore, the cut made by the disc cutter 18 in the rock formation 2 is correspondingly vertical. In the second cutting orientation, as shown in FIG. Figure 3 and Figure 4 As best seen, the drive spindle 16 is vertical. Therefore, the cut made by the disc cutter 18 in the rock formation 2 is correspondingly horizontal. For either the first or second embodiment described above, both the first and second cutting orientations are possible.

[0056] Optionally, one or more support arms 14 may also be movable so that the drive spindle 16 can operate in any cutting orientation between the aforementioned vertical and horizontal orientations, but this is not required. Alternatively, one or more support arms 14 may be configured so that they are movable between a first cutting orientation and a second cutting orientation, but are only fully operable (i.e., one or more disc cutters rotate to cut or crush rock) in the first and second cutting orientations.

[0057] Depending on the desired cutting depth, each support arm 14 is movable between a first working position and a second working position, optionally in each of a first cutting orientation and a second cutting orientation. Figure 2 For example, in the first working position, the drive spindle 16 is lowered to be close to the mine floor 4, and in the second working position, the drive spindle 16 is raised to be close to the mine top 8.

[0058] Alternatively, each support arm 14 may have a first arm portion connected to a second arm portion by a pivot joint (or alternatively, a universal joint), each first arm portion and second arm portion being movable independently relative to each other. This arrangement increases the degrees of freedom with which the cutting assembly 10 can operate and advantageously improves its maneuverability.

[0059] The drive spindle 16 is driven by a motor to rotate at a specific speed. The motor power of each disc cutter 18 is typically between 20 and 50 kW, depending on the type of disc cutter 18 selected and the required cutting force.

[0060] Now go to Figure 5In an embodiment of the present invention, the disc cutter 18 includes a generally circular body 20 and a plurality of cutting elements 22 arranged peripherally around the circular body 20. Rotation of the drive spindle 16 causes corresponding rotation of the disc cutter 18. The disc cutter 18 need not be generally circular; for example, an octagonal cutter can approximate a generally circular disc cutter depending on its size. Thus, the disc cutter 18 can be hexagonal, octagonal, decagonal, etc., or indeed have any number of circumferentially extending sides. Further information regarding the body 20 is provided further below.

[0061] In a preferred embodiment, a plurality of disc cutters 18 are arranged on the drive spindle 16. Typically, six or more disc cutters 18 may be provided. Depending on the embodiment, the disc cutters 18 are preferably regularly spaced along the length of the drive spindle 16 between the pair of spaced apart support arms 14 or on either side of the support arms 14.

[0062] The spacing of the disc cutters 18 is selected according to the required cutting depth and the mechanical properties of the rock formation 2 being cut, such as the ultimate tensile strength (UTS), so as to optimize the specific cutting energy, which will determine the required power consumption. The goal is to achieve a condition in which the cut material is crushed under its own weight. For example, for a cutting depth of 0.4 m in kimberlite, the ideal spacing between adjacent disc cutters is about 0.3 m. However, this can be increased or decreased depending on the force required for crushing. Preferably, the spacing is adjustable in situ and can be an automatic or manual process. The spacing can be adjusted remotely, for example from an operations office on the ground. A wedge-shaped tool can be used to apply this crushing force to assist in rock crushing.

[0063] The disc cutters 18 are spaced apart by a gap measuring preferably between 0.01 m and 2 m, more preferably between 0.01 m and 0.5 m. Still more preferably, the disc cutters 18 are spaced apart by a gap measuring between 10 cm and 40 cm.

[0064] The circular body 20 of the disc cutter 18 is typically made of steel and has a diameter of approximately 1000 mm and a thickness of approximately 10 to 30 mm (measured axially, also considered to be the lateral extent for the purposes of the subsequent description). In practice, such a diameter enables a cutting depth of up to 400 mm. The axial diameter of the circular body 20 is between 60 mm and 100 mm and is sized and shaped to receive the drive spindle 16.

[0065] The diameter (or effective diameter in the case of non-circular disc cutters) and thickness of the disc cutter 18 is appropriately selected according to the intended application of the cutting assembly. For example, a cable laying application would call for a disc cutter 18 having a small diameter. A robotic arm angle grinder would require a smaller diameter. However, a tunneling application would require a disc cutter 18 having a significantly larger diameter and would be adjusted accordingly.

[0066] According to the present invention, the disc cutter 18 further comprises a plurality of tool holders 24, each tool holder receiving at least one cutting element 22. In this embodiment, there is a repeating set of four tool holders 24 and seven cutting elements 22. There are a total of forty-two PDC cutting elements 22. Each set is repeated in the same manner around the circular body 20. In each set, there are four different spatial configurations of tool holders 24 and cutting elements 22, as explained in greater detail below. The cutting forces required by the disc cutter 18 are significantly reduced when arranged sequentially one after the other in the direction of rotation of the disc cutter 18.

[0067] In each set, the tool holders remain facing the same forward direction toward the direction of rotation. The arrangement of cutting elements is from one tool holder to the next tool holder within the set. The predetermined order of cutting elements is advantageous and different from the prior art

[0068] Different sets around the circular body 20 can be used.

[0069] Not all sets must contain tool holders with any cutting elements. They can simply be “blank” without cutting elements.

[0070] Each tool holder 24 includes a body portion 26 and a pair of spaced apart legs 28 extending from the body portion 26. The body portion 26 is generally cuboidal. The body portion 26 carries the cutting element or cutting elements 22. Each of the pair of legs 28 is plate-like. The legs 28 are spaced apart by a gap 30, which enables the tool holder 24 to be coupled on either side of the circular body 20. As shown, a plurality of slots 32 are periodically positioned along a circumferential surface 34 of the generally circular body 20. Each slot 32 is occupied by the gap 30 when the tool holder 24 is installed on the circular body 20. The slots 32 reduce shear forces on the bolts during use. The tool holders 24 are regularly spaced around the circular body 20 due to the circumferential surface 34 of the circular body 20 extending between adjacent slots 32. In this embodiment, twenty-four slots are provided for the twenty-four tool holders 24. Figure 6

[0071] The tool holder 24 tapers inwardly from a first end 36 proximate the cutting element or cutting elements 22 toward a second end 38 proximate the free ends of the legs 28.

[0072] Figure 7 ​A first embodiment of a tool holder 24 is shown in a of a, configured to seat a single (axially) centrally mounted cutting element 22.

[0073] Figure 7 A second embodiment of a tool holder is shown in b of a, configured to seat two adjacent cutting elements 22.

[0074] Figure 7 A third embodiment of a tool holder 24 is shown in c of a, configured to seat two spaced apart cutting elements 22.

[0075] Figure 7 A fourth embodiment of a tool holder 24 is shown in d of a, configured to seat two spaced apart cutting elements 22, with a central recess 40 between the two cutting elements 22. The elongated channels 36 extend in the intended direction of rotation of the disc cutter 18, see Figure 10 .

[0076] Preferably, the tool holders are arranged in the following order: a, d, c, b, as shown in Figure 8 . However, if all four tool holder configurations are used, any ordering within the sequence can be envisaged. See, for example, Table 1 below.

[0077]

[0078]

[0079] Table 1

[0080] It is also possible to use a set comprising one or more tool holders of two, three or more configurations and one or more cutting elements. If more than one cutting element is used on a particular tool holder 24, the dimensions of the individual cutting elements 22 and the spacing between the cutting elements needs to be adjusted accordingly.

[0081] Preferably, the individual tool holders 24 are made of steel, but can alternatively comprise any one or more metals or carbides or ceramic based materials with a hardness above 70 HV (Vickers hardness). The individual tool holders 24 can be permanently connected to the cutter body 20, for example using brazing or welding, or as in the embodiment shown in Figures 5-15 , be removably mounted to the cutter body 20 using a holding mechanism, such as the two pairs of nuts and bolts 42 in the holes 44 on the body 20 and the holes 46 on the legs 28. Brazing, welding and / or mechanical connections can be used in a mix. Alternatively, one or more tool holders 24 can be integrally formed with the body 20 of the disc cutter 18, for example by forging, powder metallurgy, etc.

[0082] In one embodiment, each cutting element 22 is rigidly or fixedly supported by one of the tool holders 24. The tool holders 24 are preferably equiangularly spaced about the circumferential surface of the cutter body 20. Brazing may be used to secure each cutting element 22 in place in or on the tool holder 24. Alternatively, the tool holder or each tool holder 24 may be configured to rotatably receive the cutting element 22. In such an embodiment, the cutting element or elements 22 and the tool holder 24 may be configured such that the cutting element or elements 22 can freely rotate within the tool holder 24, for example, by a clearance fit, or alternatively, can rotate within the tool holder 24 only when the cutting element 22 is in contact with the rock formation being mined / excavated, for example, by a transition fit.

[0083] Each of cutting elements 22 comprises a hard, wear-resistant material having a hardness of 130 HV or greater. Cutting elements 22 preferably comprise a superhard material selected from the group consisting of cubic boron nitride, diamond, diamond-like material, or combinations thereof, but may also be a hard material such as tungsten carbide. Cutting elements 22 may include a cemented carbide substrate bonded with a superhard material.

[0084] In one embodiment, the cutting element 22 is a polycrystalline diamond compact (PDC), more commonly found in the oil and gas drilling field. Such PDCs are often cylindrical and typically include a diamond layer sintered onto a steel or carbide substrate.

[0085] The diameter of the PDC is between 6 mm and 30 mm, preferably between 8 mm and 25 mm. For example, the diameter of the PDC can be 6 mm, 11 mm, 12 mm, 13 mm, or 16 mm, or 19 mm. A combination of diameters can be used in a disc cutter.

[0086] Each PDC can be chamfered, double chamfered, or multi-chamfered; Figure 11 The PDC is depicted as triple chamfered (indicated at 47 ) to reduce the risk of premature failure of the cutting element 22 .

[0087] Each PDC may include a polished cutter surface, or be at least partially polished.

[0088] Alternatively, the cutting elements 22 can be 3-D shaped cutters instead of conventional PDCs. The impact head of the cutting elements 22 can be conical, pyramidal, ballistic, chisel, or hemispherical. The impact head can be flat-tipped or non-tipped. The impact head can be axisymmetric or asymmetric. Any shape of cutting element 22 can be used in conjunction with any aspect of the present invention. Examples of such shaped cutters can be found in WO 2014 / 049162 and WO 2013 / 092346.

[0089] Optionally, the face angle of the (PDC type) cutting elements is between 15 and 30 degrees. Optionally, the face angle is about 20 degrees. Optionally, the face angle can be positive or negative. Figure 12 How the cutting elements 22 project from the tool holder 24 is shown.

[0090] In rock excavation applications, the disc cutter 18 contacts the rock formation 2 and rotates the drive spindle 16, and thus its one or more disc cutters 18, causing a cut layer of the rock formation 2. The cutting assembly 10 cuts into the rock formation 2 in layers, for example, producing a neat orthogonal cut of about 16 mm depending on the size of the cutting elements 22 selected. The cut rock breaks under its own weight or secondary wedge forces (for example using a wedge tool). As Figure 13 shown, the cutting elements 22 in each group produce overlapping cuts in the rock, generally indicated at 48. This allows the cutting forces to be evenly distributed across the cutting slot.

[0091] The overlap cut in the main embodiment is 60 mm, and this is based on a combination of four tool holders and cutting elements within each group. If a larger overlap cut is required, a greater combination of tool holders and cutting elements will be used, for example six, eight, ten, twelve, etc. If a smaller overlap cut is required, a lesser combination of tool holders and cutting elements will be required, for example two or three.

[0092] Referring to Figure 14 and Figure 15 trenching is an important potential application for cutting assemblies, in particular disc cutters 18. Typically, a single disc cutter 18 is mounted around a drive spindle 16 and rotates in the direction indicated by the arrow when in use. The disc cutter 18 and spindle are mounted and housed within a housing 50. When the disc cutter 18 is rotated and contacts the ground, the one or more disc cutters 18 will cut a layer of rock.

[0093] Smaller versions can be used to create micro-trenches in roads and sidewalks, for example, to lay small-diameter fiber optic cables. In this case, the cutting assembly 10 will cut into asphalt and concrete rather than rock. In such an embodiment, the cutter body 20 has a diameter of approximately 300 mm and a lateral thickness of up to 20 mm, with the cutting elements sized accordingly. The goal is to achieve a cutting depth of approximately 50 mm to 100 mm.

[0094] For some trenching operations, the diameter of the cutter body is approximately 1100 mm and the lateral thickness of the disc cutter (including the cutting elements 22) is approximately 60 mm.

[0095] While several applications for cutting assemblies have been mentioned above, tunnel excavation is a particularly attractive application. Typically, a tunnel boring machine (TBM) is used to construct a new tunnel underground. TBMs form cylindrical tunnels in a well-known manner. If the tunnel is intended for vehicular or pedestrian traffic and can only have a circular transverse cross-section, a new horizontal floor must be included in the lower portion of the tunnel. In practice, the diameter of the tunnel is too large. To create the actual usable space required in the upper portion of the tunnel, excess rock material must be excavated, which increases tunneling costs, not only because larger TBMs require more consumable cutting heads than smaller ones, but also because tunneling operations take longer. Furthermore, constructing the new floor requires additional material. Thanks to the cutting assemblies described herein, tunnels with a smaller transverse cross-section can be created, thereby achieving the desired shape for the upper tunnel. The cutting assembly then follows the smaller TBM to shape the lower half of the tunnel, creating a floor perpendicular to the walls and removing significantly less material than with a larger TBM.

[0096] The circular body 20 was previously represented as a solid disc having only a central (or offset) axial hole for receiving the drive spindle 16 . Figures 16-19 An alternative form of circular body 20 is depicted which may be used in conjunction with the features described herein. Figure 16 and Figure 17 In the , four panels have been removed from the body to leave four holes, and similarly, in Figure 18 and Figure 19 In this example, five panels have been removed. While any form of machining can be used, these panels are typically removed using a laser. The pattern of holes maintains structural strength while reducing the overall weight of the disc. Different geometric designs can be used to achieve an optimized strength-to-weight ratio for different applications.

[0097] refer to Figure 16A second embodiment of a tool body is designated 100. The body includes four radial spokes 102 and four lightening holes 104, one between each pair of adjacent spokes 102. The spokes 102 are regularly spaced and symmetric about the central axial bore 106 that receives the drive spindle 16. The spokes 102 taper circumferentially outward from the center of the body 100 toward the peripheral surface 34 of the body 100. Thus, each hole 104 is generally trapezoidal in shape, having a pair of arcuate inner and outer surfaces 108 and a pair of flat surfaces 110 that adjoin the arcuate surfaces 108. The arcuate surfaces 108 extend circumferentially, while the flat surfaces 110 extend radially.

[0098] In Figure 17 a third embodiment of a tool body is designated 200. The body includes four radial spokes 202 and four lightening holes 204, one between each pair of adjacent spokes 202. The spokes 202 are regularly spaced about the central axial bore 106. However, the spokes 202 are offset from the center, and the body 200 is asymmetric about its axis of rotation (i.e., the bore 106). The width of the spokes 202 remains substantially constant from the center of the body 100 toward the peripheral surface 34 of the body 200. Each hole 204 is quadrilateral, having two generally radially extending adjoining surfaces 208 and a pair of generally circumferentially extending opposing adjoining surfaces 210.

[0099] In Figure 18 a third embodiment of a tool body is designated 300. The body includes five radial spokes 302 and five lightening holes 304, one between each pair of adjacent spokes 302. The spokes 302 are regularly spaced about the central axial bore 106. However, the spokes 302 are offset from the center, and the body 300 is asymmetric about its axis of rotation (i.e., the bore 106). The width of the spokes 202 remains substantially constant from the center of the body 100 toward the peripheral surface 34 of the body 300. Each hole 304 is triangular with rounded corners. Two surfaces 308 extend generally radially, and a third surface 310 extends generally circumferentially.

[0100] Referring to Figure 19 a fourth embodiment of a tool body is designated 400. The body includes five radial spokes 402 and five lightening holes 404, one between each pair of adjacent spokes 402. The spokes 402 are regularly spaced and symmetric about the central axial bore 106 that receives the drive spindle 16. The spokes 402 taper circumferentially outward from the center of the body 400 toward the peripheral surface 34 of the body 400. Thus, each hole 404 is generally trapezoidal in shape, having a pair of arcuate inner and outer surfaces 408 and a pair of flat surfaces 410 that adjoin the arcuate surfaces 408. The arcuate surfaces 408 extend circumferentially, while the flat surfaces 410 extend radially.

[0101] While the application has been particularly shown and described with reference to particular embodiments, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the scope of the application as defined by the appended claims.

[0102] For example, any tool body variant can be used in combination with any feature disclosed herein.

[0103] The following briefly explains certain standard terminology and concepts as used herein.

[0104] As used herein, polycrystalline diamond (PCD) material comprises a plurality of diamond grains, wherein a majority of the diamond grains are directly bonded to one another, and wherein the diamond content is at least about 80% (by volume) of the material. The interstices between the diamond grains can be substantially empty, or they can be at least partially filled with a volume filler material, or they can be substantially empty. The volume filler material can comprise a sintering promoting material.

Claims

1. A disc cutter comprising a cutter body, a plurality of tool holders, and a plurality of cutting elements mounted on the tool holders, the tool holders comprising a body portion and a pair of spaced-apart legs, the cutter body comprising a series of slots positioned along a circumferential surface of the cutter body, the tool holders being mounted within the series of slots, wherein: The tool holders and the cutting elements are arranged in at least one group around the tool body, each group comprising two or more cutting elements and two or more tool holders arranged in a predetermined configuration sequence, each individual tool holder occupying a position within the predetermined configuration sequence, wherein, in each group, the number and / or the relative lateral spacing of the cutting elements on each tool holder varies depending on the position of the tool holder within the predetermined configuration sequence.

2. The disc cutter of claim 1, comprising a plurality of groups around the circumferential surface of the cutter body.

3. The disc cutter according to claim 2, wherein: The groups are identical.

4. The disc cutter according to claim 2, wherein: The groups are not identical.

5. A disc cutter according to any preceding claim, comprising three or more tool holders in a set.

6. A disc cutter according to any preceding claim, comprising four tool holders in a set.

7. A disc cutter according to any preceding claim, comprising a single cutting element in one or more of the tool holders.

8. The disc cutter according to claim 7, wherein The single cutting element is centrally mounted on the tool holder.

9. A disc cutter according to any preceding claim, comprising two cutting elements in one or more of the tool holders.

10. The disc cutter according to claim 9, wherein The two cutting elements are arranged side by side adjacent to each other on the tool holder.

11. The disc cutter according to claim 9, wherein The two cutting elements are arranged on the tool holder at a distance from each other.

12. The disc cutter according to claim 11, wherein The two cutting elements are spaced apart with a groove therebetween.

13. A disc cutter according to any preceding claim, wherein The cutting element is a polycrystalline diamond compact (PDC).

14. The disc cutter according to claim 13, wherein The PDC has a triple chamfer.

15. The disc cutter of claim 1, wherein The tool holder tapers inwardly from a first end proximate the or each cutting element towards a second end.

16. A trenching machine comprising a disc cutter as claimed in any preceding claim.

17. The trenching machine of claim 16, wherein: The diameter of the tool body is in the range of 900 to 1200 mm.

18. A trenching machine as claimed in claim 16 or 17, wherein: The thickness of the tool body is in the range of 20 to 30 mm.

19. A trenching machine as claimed in claim 16, 17 or 18, wherein: The effective cutting width of the disc cutter is approximately 60 mm.

Images