EP2678526A2

EP2678526A2 - Self-aligning insert and degradation assembly

Info

Publication number: EP2678526A2
Application number: EP12704091.3A
Authority: EP
Inventors: Cornelis Roelof Jonker; Frank Friedrich Lachmann; Bernd Heinrich Ries
Original assignee: Element Six GmbH; Element Six Abrasives SA
Current assignee: Element Six GmbH; Element Six Abrasives SA
Priority date: 2011-02-23
Filing date: 2012-02-16
Publication date: 2014-01-01
Also published as: GB2488408B; GB2488408A8; WO2012113707A2; RU2013142994A; WO2012113707A3; GB201202650D0; CN103502572A; GB2488408A; DE112012000963T5; GB2488408B8; CA2827914A1; AU2012219742A1; GB201103096D0

Abstract

An insert (110) for a degradation assembly comprising a holder, the insert (110) comprising a tip (112), a coupler mechanism (114) for moveably coupling the insert with the holder, and an alignment mechanism operable to urge the tip (112) towards an aligned orientation within the holder; the aligned orientation being with respect to a forward direction (M) in which the insert (110) is to be driven in use.

Description

INSERT AND DEGRADATION ASSEMBLY

This disclosure relates generally to inserts for degradation tools, particularly but not exclusively for degrading hard or abrasive bodies, such as rock, asphalt, coal or concrete, for example, and to degradation assemblies comprising same.

A degradation tool such as a pick may be used for breaking, boring into or otherwise degrading structures or bodies, such as rock, asphalt, coal or concrete and may be used in applications such as mining, construction and road reconditioning. For example, in road reconditioning operations, a plurality of pick tools may be mounted on a rotatable drum and caused to break up the road as the drum is rotated. A similar approach may be used to break up rock formations such as in coal or potash mining. Some pick tools may comprise a working tip comprising synthetic diamond material, which is likely to have better abrasion resistance than working tips formed of cemented tungsten carbide material. However, synthetic and natural diamond material tends to be more brittle and less resistant to fracture than cemented carbide material and this tends to reduce its potential usefulness in pick operations. There is a need to provide a pick tool having longer working life. United States patent application publication number 2008/0035383 discloses a high impact resistant tool having a superhard material bonded to a cemented metal carbide substrate, the cemented metal carbide substrate being bonded to a front end of a cemented metal carbide segment, which has a stem formed in the base end, the stem being press fit into a bore of a steel holder. The steel holder is rotationally fixed to a drum adapted to rotate about an axis.

Viewed from a first aspect an insert for a degradation assembly is provided, the insert comprising a tip, a coupler mechanism for moveably coupling the insert with a holder so that the insert can move to some extent with respect to the holder, and an alignment mechanism capable of urging the tip to move in use relative to the holder towards an aligned orientation; the aligned orientation being with respect to a forward direction in which the insert is to be driven in use

The alignment mechanism may be capable of urging the tip towards the aligned orientation responsive to a reaction force exerted on the alignment mechanism by a body being degraded as the insert is driven against the body with a force. For example, the degradation assembly may be a pick tool assembly for pavement degradation or mining. Viewed from a second aspect, there is provided a degradation assembly comprising a holder and an insert, the insert comprising a tip, a coupler mechanism for moveably coupling the insert with the holder, and an alignment mechanism operable to urge the tip towards an aligned orientation within the holder; the aligned orientation being with respect to a forward direction in which the insert is to be driven in use.

Non-limiting example arrangements to illustrate the present disclosure will be described with reference to the accompanying drawings, of which:

Fig. 1A shows a schematic side view of an example insert;

Fig. 1 B and Fig. 1 C show top views of the insert illustrated in Fig. 1A in different orientations;

Fig. 2A shows a schematic side view of an example insert;

Fig. 2B shows a schematic perspective view of the insert illustrated in Fig. 2A;

Fig. 3 shows a schematic cross section view of an example tip joined to a support body;

Fig. 4A shows a schematic side view of an example degradation assembly;

Fig. 4B shows a schematic front view of the degradation assembly illustrated in Fig. 4A, viewed from the direction of forward movement as in use;

Fig. 5A shows a schematic side view of an example insert and Fig. 5B shows a schematic top view of an example holder for the insert;

Fig. 6 shows a schematic cross section view of an example insert mounted in an example holder;

Fig. 7 shows a schematic cross section view of an example holder and sleeve;

Fig. 8 shows a schematic cross section view of an example insert mounted in an example holder; and

Fig. 9 shows a schematic cross section view of an example insert mounted in an example holder. The same reference numbers refer to the same general features in all drawings. Example inserts will now be described with reference to Fig. 1A to Fig. 2B.

An example insert 1 10 for degrading a body (not shown) comprises a tip 1 12, a coupler shank 1 14 for rotatably coupling the insert 110 to a holder (not shown), and an alignment mechanism operable to urge the tip 112 to rotate about a longitudinal axis Y defined by the coupler shank when the insert is driven against the body with a force in use. In this particular example, the alignment mechanism lies in the arrangement of the tip 112 with respect to the coupler shank 114, operable to move the tip 1 12 towards an aligned orientation with respect to the forward direction M of movement of the insert 1 10 in use.

When in use, the insert would be driven in the direction M against a body (not shown) to be degraded. As the tip 1 12 is driven against a body to be degraded with a force, the body will exert a corresponding opposing reaction force F on the tip 112, resulting in the tip moving responsive to the reaction force F. In this example arrangement, the tip 1 12 is joined to an end of a support body 1 16 and the coupler shank 114 extends from an opposite end of the support body 116. The coupler shank 1 14 is configured for rotatably coupling the insert 1 10 with a holder (not shown) and defines a longitudinal axis Y. The tip 112 may define an axis X laterally displaced from the longitudinal axis Y, with the tip 112 being positioned non-concentrically with the axis Y and capable of rotating to some extent about the longitudinal axis Y. In other words, the tip 112 is laterally offset from the axis Y and defines a longitudinal axis X that may be generally parallel with axis Y, but substantially spaced apart from it. In other example arrangements, the axis defined by the tip 1 12 may not be substantially parallel with the axis Y defined by the coupler shank 114. The tip 112 may be displaced laterally from the longitudinal axis Y by at least 2 mm or at least about 4 mm. In Fig. 1 B, the insert is schematically shown not substantially aligned with the forward direction of movement M and the angle Θ between a line X-Y and the direction of movement M is substantially non-zero degrees. In operation, when the insert engages a body (not shown) to be degraded in this orientation, the body would exert a reaction force F on the tip 1 12 opposite to the direction M, causing the tip 1 12 to rotate about the axis Y, thereby reducing the angle Θ. In the orientation of the insert 1 10 illustrated in Fig. 1 C, the angle Θ is substantially zero degrees and engagement of the insert 1 10 with the body to be degraded would not result in substantial change in the orientation. Therefore, the orientation illustrated in Fig. 1 C may be described as being relatively more stable than the orientation illustrated in Fig. 1 B. If a degradation assembly comprising the insert is mounted onto a drum or other tool carrier in less stable orientations, in which the angle Θ is not substantially zero degrees, the alignment mechanism of the insert will have the aspect of bringing the insert into closer alignment with the direction of forward movement M when in use, arising from engagement with the body to be degraded.

With reference to Fig. 1A, the tip 112 may comprise a PCD structure 1 121 joined to a cemented carbide substrate 1 122 and have a generally rounded cone shape with a rounded apex defined by the PCD structure 1 121. The support body 116 may comprise a wear retardant structure 1161 on the forward side indicated by the arrow 130, which may reduce the wear rate of the holder 1 16 in use. In some versions, the wear retardant element may comprise cemented tungsten carbide material, SiC- bonded diamond material, diamond-enhanced cemented carbide material or even PCD material.

As a non-limiting example, a pick tool as disclosed may comprise a tip as described in United States patent application publication numbers 2009/005121 1 ; 2010/0065338; 2010/0065339 or 2010/0071964. With reference to Fig. 3, an example of an insert for an embodiment of a pick tool as disclosed herein comprises a tip 1 12 comprising a superhard structure 1 11 in the general form of a cap bonded to a cemented carbide substrate 113. The tip 1 12 is joined to a frusto-conical portion 1 16 of a support body 1 14. The major part of the superhard structure 1 11 has a spherically blunted conical outer shape, having a rounded apex 11 1 1 with a radius of curvature in a longitudinal plane, and a cone angle κ between an axis parallel to the longitudinal axis AL and conical portion 11 12 of the outer surface of the superhard structure 11 1. The superhard structure 1 11 comprises a nose region 11 13 and a skirt region 1 114, which depends longitudinally and laterally away from the nose region 11 13. In some versions of the example, the minimum longitudinal thickness of the skirt region 1 114 may be at least about 1.3 mm or at least about 1.5 mm. In some versions of the example, the longitudinal thickness of the superhard cap 1 1 1 at the apex 1 11 1 is at least about 4 mm or at least about 5 mm and at most about 7 mm or at most about 6 mm. In one version of the example, the longitudinal thickness of the superhard structure 11 1 at the apex 11 11 is in the range from about 5.5 mm to 6 mm. In some versions of the example, the radius of curvature of the rounded apex 1 11 1 is at least about 2 mm and at most about 3 mm. In some embodiments, the cone angle κ is at most 80 degrees or at most 70 degrees. In some versions of the example, the cone angle κ is at least 40 degrees, at least 45 degrees or at least 50 degrees.

A holder for a pick tool as disclosed may be attached to a base block (carrier body) by means of an interlocking fastener mechanism in which a shaft of the holder is locked within a bore formed within the carrier body. The shaft may be releasably connectable to the base block welded or otherwise joined to the drum. The base block and holder, more specifically the shaft of the holder, may be configured to permit releasable inter-engagement of the steel holder and base block. The shaft may be configured to inter-engage non-rotationally with a base block, and may be suitable for use with tool carriers disclosed in German patents numbers DE 101 61 713 B4 and DE 10 2004 057 302 A1 , for example. The tool carrier, such as a base block, may be welded onto a component of a drive apparatus, such as a drum, for driving the superhard pick tool. Other types and designs of tool carriers may also be used, the holder being correspondingly configured for coupling.

In operation, the pick tool may be driven forward by a drive apparatus on which it is mounted, against a structure to be degraded and with the tip at the leading end. For example, a plurality of pick tools may be mounted on a drum for asphalt degradation, as may be used to break up a road for resurfacing. The drum is connected to a vehicle and caused to rotate. As the drum is brought into proximity of the road surface, the pick tools are repeatedly impacted into the road as the drum rotates and the leading tips thus break up the asphalt. A similar approach may be used to break up coal formations in coal mining.

Example arrangements of degradation assemblies are described with reference to Fig. 4A to Fig. 9. With reference to Fig. 4A and Fig. 4B, an example degradation assembly 100 comprises an insert 1 10 moveably coupled with a holder 120, the holder being substantially non-moveably mounted onto a tool carrier (or base block) 200, which may be attached to a pick apparatus such as a drum. The insert 1 10 comprises a tip 1 12 joined to a support body 116, in which a major portion of the support body 1 16 may comprise steel and a "forward"-facing part (as indicated by the arrow 130) may comprise a wear-retardant structure 1 161 comprising a material having higher wear resistance than the steel. The support body 1 16 may be configured to present as small a projection in the forward direction as possible, as is apparent in FIG 4B, which may have the aspect of reducing the volume of steel worn away in use.

A degradation assembly 100 comprising a holder 120 and an insert 110 can be provided for degrading a body (not shown), such as a pavement or a rock formation. The holder 120 and the insert 110 may be cooperatively configured operable to moveably couple the insert 1 10 with the holder 120, and the insert 1 10 may be provided with a coupler means for this purpose. The insert 110 comprises a tip 1 12 for degrading the body and an alignment mechanism operable to urge the insert 110 to move with respect to the holder 120 when the insert is driven with a force against the body in use, responsive to the body exerting a reaction force on the alignment mechanism.

An example degradation assembly may comprise an insert and a holder as illustrated in Fig. 5A and Fig. 5B. In this example arrangement, the coupler means may comprise a shank 1 14 and the holder 120 may be provided with a bore 122 for receiving the shank 114. The shank 114 and the holder 122 may be cooperatively configured so that the insert 1 10 can be rotatably mounted onto the holder 120. The holder 120 and the insert 1 10 may have respective opposing bearing surfaces 1202 and 1162 (when the insert 1 10 is mounted in the holder 120). In the particular example illustrated in FIG 5A and FIG 5B, the degradation assembly may comprise a limitation mechanism operable to limit the moveable coupling means within a range of positions. The holder 120 may be provided with a projection 1 101 extending from the bearing surface 1 162, and the holder 120 may be provided with a slot 1201 configured to receive the projection 1 101 and permit it to move in a constrained path, which in this particular example is generally arctuate. When the insert 110 is mounted onto the holder 120 with the shank 1 14 inserted into the bore 122, the projection 1101 will be inserted in the slot 1201. When the insert 110 is caused to rotate within the bore 122 of the holder 120, the slot 1201 permits the projection 1101 to move between rotational limits, resulting in constrained rotation of the insert 110 relative to the holder 120. Some arrangements may have the aspect that the insert 1 10 can rotate sufficiently to locate a desired stable configuration, but not so much that it faces the wrong direction. In an example arrangement of a degradation assembly, the holder and the coupler means may be cooperatively configured operable to retard movement of the insert relative to the holder in use, responsive to the body exerting a reaction force on the insert. With reference to the example arrangements illustrated in Fig. 6 to Fig. 9, the coupler means may comprise a shaft 1 14 having a generally tapered portion and the holder 120 may have a cooperatively tapered bore 122 for receiving the shaft 114, configured so that the shaft 1 14 will exert a lateral force onto a side surface of the bore 122 responsive to the shaft 114 being forced into the bore 122. The arrangement may permit the shaft 114, and consequently the entire insert 110, to rotate within the holder 120 with increasing resistance as the shaft 114 is urged into the bore 120 with increasing force. In other words, as the shaft 114 is forced into the bore 122 and against the tapered side wall of the bore 122, friction will result in increased resistance to rotation of the shaft 114 within the bore 122. In use, the arrangement may permit the insert 110 to rotate sufficiently to locate a stable configuration and substantially to preserve this configuration by forcing the insert 1 10 into the bore 122 as the insert 1 10 engages the body to be degraded, thereby tightening the coupler means 114.

In some examples, a sleeve 140 may be arranged between the coupler means 114 and the bore 122. For example, the bore 122 may be generally cylindrical and not substantially tapered, and the sleeve 140 may have a tapered inner surface 1401 for accommodating a tapered shaft 1 14 of the insert 110.

The following clauses are offered as further descriptions of the disclosed pick tools. 1. An insert for a degradation assembly comprising a holder, the insert comprising a tip, a coupler mechanism for moveably coupling the insert with the holder, and an alignment mechanism operable to urge the tip towards an aligned orientation within the holder; the aligned orientation being with respect to a forward direction in which the insert is to be driven in use.

2. The insert of clause 1 , the alignment mechanism being operable to urge the tip towards the aligned orientation responsive to a reaction force exerted on the alignment mechanism by a body being degraded as the insert is driven against the body with a force.

3. The insert of clause 1 or 2, in which the coupler mechanism comprises a shank for insertion into a bore within the holder. 4. The insert of any of the preceding clauses, in which the alignment mechanism comprises the tip.

5. The insert of any of the preceding clauses, in which the coupler mechanism comprises a shank, which defines a longitudinal axis; the insert being configured with the tip laterally displaced from the longitudinal axis.

6. The insert of any of the preceding clauses, in which the coupler mechanism is configured for rotatably coupling the insert with the holder. 7. The insert of any of the preceding clauses, in which the coupler mechanism comprises a shank defining a longitudinal axis, the alignment mechanism comprises the tip being laterally displaced from the longitudinal axis; the tip and the shank configured operable to permit variation in the angular position (azimuthal position) of the tip about a longitudinal axis defined by the shank, when the shank is inserted into a bore formed in the holder.

8. An insert comprising a tip, a coupler shank, a support body having a proximate end and a distal end, the tip joined to the proximate end of the support body and the coupler shank joined to or extending from the support body at the distal end; the coupler shank configured for rotatably coupling the insert to a holder and defining a longitudinal axis; the tip displaced laterally from the longitudinal axis.

9. The insert of any of the preceding clauses comprising a limitation mechanism operable to limit the extent of movement of the insert relative to the holder, as permitted by the coupler mechanism.

10. The insert of any of the preceding clauses, in which the coupler mechanism comprises a shank defining a longitudinal axis, the alignment mechanism comprises the tip being laterally displaced from the longitudinal axis; the tip and the shank configured operable to permit variation in the angular position (the azimuthal position) of the tip about a longitudinal axis defined by the shank, when the shank is inserted into a bore formed in the holder; the insert comprising a limitation mechanism operable to limit the extent of rotation of the tip about the longitudinal axis.

1 1. The insert of any of the preceding clauses, in which the tip comprises a superhard material, for example synthetic or natural diamond material, such as PCD, SiC-bonded diamond material or diamond-enhanced carbide material.

12. The insert of any of the preceding clauses, in which the tip comprises a PCD structure joined to a cemented carbide substrate and has a working end having generally rounded conical shape. 13. The insert of any of the preceding clauses, in which the support body comprises steel material.

14. The insert of any of the preceding clauses, in which the support body comprises a wear retardant structure.

15. The insert of any of the preceding clauses, in which the coupler mechanism is configured operable to retard or resist movement of the insert relative to the holder. The insert of any of the preceding clauses, in which the coupler mechanism is configured operable to retard or resist movement of the insert relative to the holder in use, responsive to the body exerting a reaction force on the coupler mechanism. The insert of any of the preceding clauses, in which the degradation assembly is for pavement degradation (road refurbishment) or mining. A degradation assembly comprising a holder and the insert of any of the preceding clauses. The degradation assembly of clause 18, for pavement degradation or mining. The degradation assembly of clause 18 or 19, comprising a limitation mechanism operable to limit the extent of movement of the insert relative to the holder, as permitted by the coupler mechanism. The degradation assembly of any of clauses 18 to 20, in which the holder and the coupler means are cooperatively configured operable to retard or resist movement of the insert relative to the holder. The degradation assembly of any of clauses 17 to 21 , in which the holder is provided with a bore for accommodating the coupler mechanism of the insert; the coupler mechanism and bore being configured to permit the insert to rotate about a longitudinal axis defined by the coupler mechanism when the insert is coupled to the holder. The degradation assembly of any of clauses 17 to 22, in which the insert and holder are cooperatively configured operable to limit the extent of movement, such as rotation, of the insert relative to the holder as permitted by the coupler mechanism. The degradation assembly of any of clauses 17 to 23, in which the insert and holder are cooperatively configured operable to limit the extent of rotation of the tip about a longitudinal axis defined by the coupler mechanism; the tip being limited to positions rearward of the longitudinal axis when the tip is driven forward as in use. 25. The degradation assembly of clause 24, in which rotation of the tip is limited to within about 30 degrees of arc.

26. The degradation assembly of any of clauses 17 to 25, comprising a limitation mechanism for limiting the extent of movement, such as rotation, of the tip about the longitudinal axis.

27. The degradation assembly of any of clauses 17 to 26, configured operable to resist or retard movement of the insert permitted by the coupler mechanism, responsive to a force or component of a force applied longitudinally to the insert.

28. The degradation assembly of clause 27, in which the coupler mechanism comprises a shaft at least a portion or which is tapered, and the holder is provided with a bore having a surface at least a portion of which is cooperatively tapered, operable to cause the shaft to exert a lateral force on a surface of the bore responsive to a force or component of a force being applied longitudinally to the insert.

29. The degradation assembly of any of clauses 17 to 28, in which the insert comprises a shaft at least a portion of which is provided with a taper having a taper angle of at least about 2 degrees and at most about 45 degrees, and the holder is provided with a bore having a surface that is correspondingly tapered.

30. The degradation assembly of any of clauses 17 to 29, in which the coupler mechanism comprises a shank and the degradation assembly comprises a sleeve disposed around at least a portion of a shank.

31. A degradation apparatus comprising the degradation assembly of any of clauses 17 to 30 substantially non-moveably coupled to a carrier device, such as a drum. A non-limiting example of a degradation assembly is described in more detail below. Example An example pick tool assembly for asphalt pavement degradation, comprising an insert and a holder for the insert may be provided as follows.

The insert may comprise a tip, a coupler shank for rotatably coupling the insert with the holder, and a support body. The tip may comprise a PCD structure bonded to a cemented tungsten carbide substrate, which may be joined by means of a braze material to the support body at one end of the support body. The substrate may have a generally cylindrical side surface with a lateral (cylindrical) diameter of about 6 mm. The PCD structure may have the general form of a cap bonded to the substrate, the major part of the PCD structure having a spherically blunted conical outer shape with a rounded apex having a radius of curvature of 2.25 mm (in a longitudinal plane), and a cone angle of 42 degrees between an axis parallel to the longitudinal axis and conical portion of the outer surface of the PCD structure. The PCD structure may comprise a nose region and a skirt region, which may depend longitudinally and laterally away from the nose region. The minimum longitudinal thickness of the skirt region may be at least 1.45 mm. The longitudinal thickness of the PCD structure at the apex is about 4.5 mm.

The coupler shank may extend from the support body at the end opposite that at which the tip is joined. The coupler shank may be generally cylindrical in shape and define a longitudinal axis passing through the support body, and the tip may be positioned on the support body so that it is displaced laterally from the longitudinal axis (i.e. the tip is offset from the longitudinal axis), so that the apex of the tip is about 4 mm from the longitudinal axis. The longitudinal axis may pass through the tip, but is substantially spaced apart from the apex if the tip.

The support body may comprise steel and be provided with a wear protective structure comprising cemented carbide disposed on the forward side of the support body, which is the side that will face the pavement in use. The support body may be provided with generally concave lateral sides so that the forward-facing area is reduced. The holder may be provided with a bore configured to accommodate the coupler shank of the insert, such that the shank may rotate within the bore, and consequently, so that the insert may rotate relative to the holder. The holder may be provided with a shank for non-rotatable fastening to a base block welded to a pavement degradation drum.

Various example embodiments of pick tools and methods for assembling and connecting them have been described above. Those skilled in the art will understand that changes and modifications may be made to those examples without departing from the spirit and scope of the claimed invention.

Certain terms as used herein are briefly explained below.

As used herein, "superhard" means a Vickers hardness of at least 25 GPa, and a superhard tool, insert or component means a tool, insert or component comprising a superhard material.

Synthetic and natural diamond, polycrystalline diamond (PCD), cubic boron nitride (cBN) and polycrystalline cBN (PCBN) material are examples of superhard materials. Synthetic diamond, which is also called man-made diamond, is diamond material that has been manufactured. Polycrystalline diamond (PCD) material comprises a mass (an aggregation of a plurality) of diamond grains, a substantial portion of which are directly inter-bonded with each other and in which the content of diamond is at least about 80 volume percent of the material. Interstices between the diamond grains may be at least partly filled with a binder material comprising a catalyst material for synthetic diamond, or they may be substantially empty. Catalyst material for synthetic diamond is capable of promoting the growth of synthetic diamond grains and or the direct inter-growth of synthetic or natural diamond grains at a temperature and pressure at which synthetic or natural diamond is thermodynamically more stable than graphite. Examples of catalyst materials for diamond are Fe, Ni, Co and Mn, and certain alloys including these. Bodies comprising PCD material may comprise at least a region from which catalyst material has been removed from the interstices, leaving interstitial voids between the diamond grains. As used herein, PCBN material comprises grains of cubic boron nitride (cBN) dispersed within a matrix comprising metal and or ceramic material.

Other examples of superhard materials include certain composite materials comprising diamond or cBN grains held together by a matrix comprising ceramic material, such as silicon carbide (SiC), or cemented carbide material, such as Co- bonded WC material (for example, as described in United States patents numbers 5,453, 105 or 6,919,040). For example, certain SiC-bonded diamond materials may comprise at least about 30 volume percent diamond grains dispersed in a SiC matrix (which may contain a minor amount of Si in a form other than SiC). Examples of SiC-bonded diamond materials are described in United States patents numbers 7,008,672; 6,709,747; 6, 179,886; 6,447,852; and International Application publication number WO2009/013713).

Claims

1. An insert for a degradation assembly, comprising a tip, a coupler mechanism for moveably coupling the insert with a holder so that the insert can move to some extent with respect to the holder, and an alignment mechanism capable of urging the tip to move in use relative to the holder towards an aligned orientation; the aligned orientation being with respect to a forward direction in which the insert is to be driven in use.

2. An insert as claimed in claim 1 , the alignment mechanism being capable of urging the tip towards the aligned orientation responsive to a reaction force exerted on the alignment mechanism by a body being degraded as the insert is driven against the body with a force.

3. An insert as claimed in claim 1 or claim 2, in which the alignment mechanism comprises the tip.

4. An insert as claimed in any one of the preceding claims, in which the coupler mechanism comprises a shank, which defines a longitudinal axis; the insert being configured with the tip laterally displaced from the longitudinal axis.

5. An insert as claimed in any one of the preceding claims, in which the coupler mechanism is configured for rotatably coupling the insert with the holder.

6. An insert as claimed in any one of the preceding claims, in which the coupler mechanism comprises a shank defining a longitudinal axis, the alignment mechanism comprises the tip being laterally displaced from the longitudinal axis; the tip and the shank configured operable to permit variation in the angular position (the azimuthal position) of the tip about a longitudinal axis defined by the shank, when the shank is inserted into a bore formed in the holder; the insert comprising a limitation mechanism operable to limit the extent of rotation of the tip about the longitudinal axis.

7. An insert as claimed in any one of the preceding claims, in which the tip comprises a superhard material.

8. An insert as claimed in any one of the preceding claims, in which the degradation assembly is for pavement degradation or mining.

9. A degradation assembly comprising a holder and an insert as claimed in any one of the preceding clauses.

10. A degradation assembly as claimed in claim 9, comprising a limitation mechanism operable to limit the extent of movement of the insert relative to the holder permitted by the coupler mechanism.

1 1. A degradation assembly as claimed in claim 9 or claim 10, in which the holder and the coupler means are cooperatively configured operable to retard or resist movement of the insert relative to the holder, permitted by the coupler mechanism.

12. A degradation assembly as claimed in any one of claims 9 to 1 1 , in which the insert and holder are cooperatively configured operable to limit the extent of rotation of the tip about the longitudinal axis; the tip being limited to positions rearward of the longitudinal axis when the tip is driven forward as in use.

13. A degradation assembly as claimed in any one of claims 9 to 12, in which the coupler mechanism comprises a shaft at least a portion or which is tapered, and the holder is provided with a bore having a surface at least a portion of which is cooperatively tapered, operable to cause the shaft to exert a lateral force on a surface of the bore responsive to a force or component of a force being applied longitudinally to the insert.

14. A degradation assembly as claimed in any one of claims 9 to 13, in which the coupler mechanism comprises a shank and the degradation assembly comprises a sleeve disposed around at least a portion of a shank.