GB2639119A

GB2639119A - Insert

Info

Publication number: GB2639119A
Application number: GB2503329.1A
Authority: GB
Inventors: Ludwig Michael; Weinbach Eric; Heinrich Ries Bernd
Original assignee: Element Six GmbH
Current assignee: Element Six GmbH
Priority date: 2024-03-08
Filing date: 2025-03-07
Publication date: 2025-09-10
Also published as: GB202503325D0; GB202503329D0; WO2025186438A8; GB202503322D0; WO2025186436A1; WO2025186436A8; WO2025186438A1

Abstract

An insert comprising an attachment portion 18 and a wear-resistant portion 17 arranged along a longitudinal axis; wherein the attachment portion has a first connection end 24; wherein the wear-resistant portion has a second connection end 25; wherein the first connection end is configured to connect to the second connection end; wherein the first connection end comprises a cut-out portion 20 which extends along the longitudinal axis and the second connection end does not comprise a protrusion which corresponds to the cut-out portion of the first connection end; and/or wherein the second connection end comprises a cut-out portion which extends along the longitudinal axis and the first connection end does not comprise a protrusion which corresponds to the cut-out portion of the second connection end. Either connection end can have protrusions (22 fig.8), which do not correspond to a cut-out portion and extend through connecting means 19 and directly contact the opposite connection end. Also disclosed are various methods of manufacture which include brazing.

Description

INSERT

Field of the Invention

This disclosure relates generally to the field of inserts, for example inserts for drill bits. Such drill bits are typically used for drilling deep holes in rocks.

Background

Boring into the earth is an important activity in many industries, such as mining, oil and gas drilling, prospecting and tunnel construction. A wide variety of methods and various different types of bits are available for this purpose. There are three contrasting approaches that are commonly used for boring into the earth in the oil and gas drilling, mining and construction industries, namely rotary shear drilling, roller cone drilling and percussion drilling. In rotary shear drilling, a rotating drill bit head comprising a plurality of blades or inserts bores into rock by a shearing action. In roller cone drilling, the drill bit comprises several (typically three) "roller cones", each comprising a plurality of buttons or inserts. As the drill bit rotates, each of the roller cones is caused to rotate on its own axis and the blades or inserts fracture the rock by pressing onto it with a high pressure. In percussion drilling, a drill bit comprising a plurality of buttons or inserts repeatedly impacts, or hammers, a body rock at high frequency. Typically, the bit head is caused to rotate slightly between successive impacts in order to degrade the rock as much as possible. Percussion drilling is widely used in mining and construction, to drill bore holes and blast holes, for example.

Percussive drill bits are subject to extreme operational conditions, and, like any other piece of equipment, suffer from wear and tear. Once a drill bit becomes too wom to drill at an adequate rate or make a full-gauge hole, operations must be halted to replace the bit. This is a time-consuming and expensive operation.

It is an object of the invention to provide an easy to manufacture option of an insert, for example for a drill bit such as a percussive drill bit, which requires less materials and is therefore more sustainable. While principally described in the context of an insert for a drill bit, the design principle disclosed herein is applicable to any type of application where an insert with a wear-resistant element and an attachment portion as described herein may be deployed.

Summary of the invention

According to a first aspect of the invention, there is provided an insert comprising an attachment portion and a wear-resistant portion arranged along a longitudinal axis; wherein the attachment portion has an attachment end configured to connect to an insert holder and an opposing first connection end; wherein the wear-resistant portion has an impact surface and an opposing second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the first connection end comprises a cut-out portion which extends along the longitudinal axis and the second connection end does not comprise a protrusion which corresponds to the cut-out portion of the first connection end; and/or wherein the second connection end comprises a cut-out portion which extends along the longitudinal axis and the first connection end does not comprise a protrusion which corresponds to the cut-out portion of the second connection end.

As an option, the insert is a drill bit insert.

As an option, the drill bit insert is a percussive drill bit insert.

As an option, the impact surface of the wear-resistant portion is configured to protrude from an impact face of a drill bit.

As an option, the insert further comprises a connecting means between the first connection end and the second connection end.

As an option, the first connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to a cut-out portion of the second connection end, and wherein said protrusions extend through the connecting means.

As an option, the first connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to a cut-out portion of the second connection end, and wherein said protrusions extend through the connecting means and directly contact the second connection end.

As an option, the second connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to a cut-out portion of the first connection end, and wherein said protrusions extend through the connecting means.

As an option, the second connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to a cut-out portion of the first connection end, and wherein said protrusions extend through the connecting means and directly contact the second connection end.

As an option, the protrusions on the first connection end are equiangularly arranged about the longitudinal axis.

As an option, there are 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 protrusions on the first connection end.

As an option, the protrusions on the second connection end are equiangularly arranged about the longitudinal axis.

As an option, there are 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 protrusions on the second connection end.

As an option, the second connection end comprises a cut-out portion which extends along the longitudinal axis.

As an option, the connecting means at least partially fills the cut-out portion of the first connection end.

As an option, the connecting means at least partially fills the cut-out portion of the second connection end.

As an option, the connecting means is a braze layer.

As an option, the cut-out portion of the first connection end has a cylindrical portion adjacent the connecting means and connected to a conical portion or a truncated conical portion.

As an option, the cut-out portion of the second connection end has a cylindrical portion adjacent the connecting means and connected to a conical portion or a truncated conical portion.

As an option, the attachment portion is substantially cylindrical.

As an option, the wear-resistant portion comprises a substantially cylindrical body attached to a domed tip.

As an option, the wear-resistant portion comprises a substantially cylindrical body attached to a hemispherical tip.

As an option, wear-resistant portion comprises a substantially cylindrical body attached to a ballistic tip.

As an option, the attachment portion comprises a first material having a first hardness, and wherein the wear-resistant portion comprises a second material having a second hardness; wherein the hardness of the second material is greater than that of the first material.

As an option, the first material comprises a steel and the second material comprises a cemented tungsten carbide.

As an option, the first material has a Vickers hardness of between 100 and 500 HV30, and the second material has a Vickers hardness of between 900 and 1400 HV30.

As an option, the wear resistant portion and the attachment portion have corresponding diameters and are provided in a volumetric ratio of about 1:1, 2:1, 3:1, 4:1, or 5:1.

As an option, the wear resistant portion and the attachment portion have corresponding diameters and are provided in a volumetric ratio of from about 1:1 to about 5:1.

As an option, the insert further comprises a layer of super-hard material integrally bonded to the impact surface of the wear-resistant portion.

As an option, the super-hard material is polycrystalline diamond.

As an option, the attachment end is configured to attach to the drill bit body by any one of the following techniques: gluing, brazing, press-fitting, shrink fitting, threaded connection and/or mechanical connection.

As an option, the attachment portion further comprises a first side wall connecting the attachment end to the first connection end.

As an option, the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end.

As an option, the cut-out portion of the first connection end and/or the cut-out portion of the second connection end has the form of a blind hole.

As an option, the cut-out portion of the first connection end and/or the cut-out portion of the second connection end has the form of a through hole.

As an option, the cut-out portion of the first connection end has the form of a through hole. As an option, the cut-out portion of the second connection end has the form of a through hole.

As an option, the cut-out portion of the first connection end has the form of a blind hole.

As an option, the cut-out portion of the second connection end has the form of a blind hole.

In a second aspect of the invention, there is provided a drill bit comprising: a drill bit body with an impact face and a plurality of inserts according to any one of the preceding claims, each insert seated in a correspondingly shaped insert holder in the impact face.

As an option, the insert holder in the impact face is a recess.

As an option, each insert is attached to the drill bit body by any one of the following techniques: gluing, brazing, press-fitting, shrink fitting, threaded connection, and mechanical connection.

In a third aspect of the invention, there is provided a method of manufacturing an insert, for example, an insert as described herein, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion comprising a plurality of protrusions, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the first connection end comprises a cut-out portion which extends along the longitudinal axis and wherein the second connection end does not comprise a protrusion which corresponds to the cut-out portion of the first connection end; and/or wherein the second connection end comprises a cut-out portion which extends along the longitudinal axis and wherein the first connection end does not comprise a protrusion which corresponds to the cut-out portion of the second connection end; wherein the second connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to the cut-out portion of the first connection end; placing a braze material in the cut-out portion of the attachment portion and/or in the cut-out portion of the wear-resistant portion; positioning the plurality of protrusions of the second connection end on the first connection end such that the first side wall of the attachment portion is in longitudinal alignment with the second side wall of the wear resistant portion; attaching the protrusions to the attachment portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming a wear-resistant element.

In a fourth aspect of the invention, there is provided a method of manufacturing an insert, for example, an insert as described herein, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the first connection end comprises a cut-out portion which extends along the longitudinal axis; wherein the first connection end comprises a plurality of protrusions; placing a braze material in the cut-out portion of the attachment portion; positioning the second connection end on the plurality of protrusions of the first connection end such that the first side wall of the attachment portion is in longitudinal alignment with the second side wall of the wear resistant portion; attaching the protrusions to the wear-resistant portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming an insert.

In a fifth aspect of the invention, there is provided a method of manufacturing an insert, for example, an insert as described herein, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the second connection end comprises a cut-out portion which extends along the longitudinal axis; wherein the second connection end comprises a plurality of protrusions; placing a braze material in the cut-out portion of the wear-resistant portion; positioning the first connection end on the plurality of protrusions of the second connection end such that the second side wall of the wear-resistant portion is in longitudinal alignment with the first side wall of the attachment portion; attaching the protrusions to the attachment portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming an insert.

As an option, the method of the third, fourth, or fifth aspects does not comprise a step of grinding the attachment portion after the brazing step.

Brief Description of the Drawings

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side elevation view of a first exemplary insert; Figure 2 is a cross-sectional view of a first embodiment of the insert of Figure 1; Figure 3 is a cross-sectional view of another embodiment of the insert of Figure 1; Figure 4 is a top plan view of an attachment portion of the insert of Figure 1; Figure 5 is a cross-sectional view of another embodiment of the insert of Figure 1; Figure 6 is a cross-sectional view of another embodiment of the insert of Figure 1; Figure 7 is a cross-sectional view of another embodiment of the insert of Figure 1; Figure 8 is a side elevation view of a wear-resistant portion of an insert; Figure 9 is a bottom plan view of a wear-resistant portion of the insert of Figure 6; Figure 10 is a bottom plan view of an alternative embodiment of an insert; Figure 11 is a side elevation view of a second exemplary insert; Figure 12 is a side elevation view of the second exemplary insert after brazing; Figure 13 is a cross-sectional view of the insert of Figure 12; Figure 14 is a cross-sectional view of another embodiment of the insert of Figure 12; Figure 15 is a cross-sectional view of another embodiment of the insert of Figure 12; Figure 16 is a side elevation view of a third exemplary insert; Figure 17 is a drawing of a side perspective view of an embodiment of a percussive drill bit head mounted onto an anvil portion of a percussive bit as in use; Figure 18 is a perspective exploded view of Figure 17; Figure 19 is a flow diagram showing a first method of manufacturing an insert according to the invention; Figure 20 is a flow diagram showing a second method of manufacturing an insert according to the invention; and Figure 21 is a flow diagram showing a third method of manufacturing an insert according to the invention.

In the drawings, similar parts have been assigned similar reference numerals. Detailed Description Referring to Figure 1, an insert 7 is provided. The insert 7 is elongate and has a central longitudinal axis L. The insert 7 comprises a wear-resistant portion 17 and an attachment portion 18 joined by connecting means 19.

The attachment portion 18 comprises a first material and the wear-resistant portion 17 comprises a second material. Preferably, the attachment portion 18 consists of a first (bulk) material and the wear-resistant portion 17 consists of a second (bulk) material. Wear resistance of the first and second materials is substantially different to each other. Hardness is used as an indirect measure (or proxy) for wear resistance. The first material may have a Vickers hardness of 100 to 500 HV30. The second material may have a Vickers hardness of 900 to 1400 HV30.

The wear resistance of the wear-resistant portion 17 is higher than the wear resistance of the attachment portion 18. Preferably, the material of the wear-resistant portion 17 is a cemented metal carbide, for example a cemented tungsten carbide, and the material of the attachment portion 18 is a steel. The wear-resistant portion 17 is preferably a tungsten carbide grade of material with an 8 to 20 wt.% cobalt content. The medium grain size in the structure may be 2 to 5 pm. The attachment portion 18 may be formed of a standard tool or construction steel.

The attachment portion 18 of insert 7 is substantially cylindrical, and typically circular in axial cross-section. The wear-resistant portion 17 has a substantially cylindrical body 17a attached to a dome-shaped tip 17b. Thus, each of the substantially cylindrical body 17a of the wear-resistant portion 17 and the attachment portion 18 is also circular in axial cross-section. While in this embodiment the tip 17b of the wear-resistant portion is dome-shaped, it could alternatively have a hemispherical, chisel, ballistic, or conical shape. As a further alternative embodiment, the tip 17b may be substantially planar. In this embodiment, the entire wear-resistant portion 17 is substantially cylindrical. Typically, each insert 7 has a diameter of 12 mm to 20 mm, with a length of 10 mm to 40 mm. Other diameters may be used, for example, 6 mm to 30 mm. However, a shorter insert 7, for example having a length of from 5 mm to 12 mm, may alternatively be used. In a further embodiment, a mixture of longer and shorter inserts 7 may be used.

The wear-resistant portion 17 and the attachment portion 18 may be joined by connecting means 19 using any one or more of the following techniques: brazing (e.g. silver braze, copper braze, brass braze and the like), gluing (e.g. epoxy, 2 component glue and the like), friction welding, welding, laser welding or threaded connection.

In one embodiment, the volumetric ratio of the wear resistant portion 17 to the attachment portion 18 is approximately 1:1. In another embodiment, the volumetric ratio of the wear resistant portion 17 to the attachment portion 18 is approximately 2:1. In another embodiment, the volumetric ratio of the wear-resistant portion 17 to the attachment portion 18 is approximately 3:1. In a further embodiment, the volumetric ratio of the wear-resistant portion 17 to the attachment portion 18 is approximately 4:1. The volumetric ratio is influenced by the strength of the joining technique used. For example, with a strong braze as the connecting means 19, the attachment portion 18 may be made longer than it could be otherwise because it is able to withstand the applied forces during use when the connecting means 19 of the insert 7 is no longer directly supported within an insert holder. A volumetric ratio of 5:1 is also envisaged. In all of these embodiments, the diameter of the wear-resistant portion 17 corresponds to that of the attachment portion 18 at their respective connection ends.

The attachment portion 18 has an attachment end 9 configured to connect to a drill bit body and an opposing first connection end 24. The attachment end 9 and the first connection end 24 are connected by a first side wall 10a. The wear resistant portion 17 has an impact surface 8 arranged to contact the material to be impacted. A second connection end 25 is located at the opposite end of the wear resistant portion 17 to the impact surface 8. The impact surface 8 and the second connection end 25 are connected by a second side wall 10b. The wear-resistant portion 17 includes the impact surface 8 and the attachment portion 18 includes the attachment end 9.

As shown in the schematic cross-sectional view of Figure 2, in one embodiment, the attachment portion 18 comprises a cut-out portion 20. The cut-out portion 20 extends along the longitudinal axis L from the first connection end 24 towards the attachment end 9. In this embodiment, the cut-out portion 20 is in the form of a blind hole in the attachment portion 18, wherein the blind hole faces the second connection end 25 of the wear-resistant portion 17. However, in the embodiment depicted in Figure 3, the cut-out portion 20 is in the form of a through hole which extends through the attachment portion 18. Specifically, the through hole extends from the first connection end 24 to the attachment end 9. It has been found that when a through hole is used as the cut-out portion 20 in the attachment portion 18, a better flow of braze material is enabled which results in a stronger braze connection than when a blind hole is used as the cut-out portion 20 in the attachment portion 18. Furthermore, use of a through hole prevents build-up of gas pressure in the cut-out portion during brazing.

A top plan view of the attachment portion 18 of this embodiment is shown in Figure 4. As can be seen, the cut-out portion 20 has a circular cross-section and is coaxial with the cylindrical body of the attachment portion 18. While a circular cross-section is shown in Figure 3, the shape of the cross-section of the cut-out portion 20 is not particularly limited, though simpler shapes are simpler to machine. In this embodiment, the cut-out portion 20 has a cylindrical profile. The cut-out portion 20 may have a stepped or tapered profile. Where the cut-out portion 20 is a blind hole, the cut-out portion 20 may have an initial portion adjacent to the connecting means 19 with a cylindrical profile and a further conical portion which tapers to a point. Alternatively, the further conical portion may have the form of a truncated cone, terminating in a flat planar surface.

The cut-out portion 20, or the bore of the cut-out portion 20, may have a longest linear axial dimension of from 5% of the longest linear axial dimension of the attachment portion to 70% of the longest linear axial dimension of the attachment portion, for example from 10% of the longest linear axial dimension of the attachment portion to 60% of the longest linear axial dimension of the attachment portion, for example from 15% of the longest linear axial dimension of the attachment portion to 50% of the longest linear axial dimension of the attachment portion, for example from 20% of the longest linear axial dimension of the attachment portion to 40% of the longest linear axial dimension of the attachment portion, for example from 30% of the longest linear axial dimension of the attachment portion to 40% of the longest linear axial dimension of the attachment portion. The cut-out portion 20 may have a longest linear axial dimension of at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 35% of the longest linear axial dimension of the attachment portion. The cut-out portion 20 may have a longest linear axial dimension of at most 70%, or at most 65%, or at most 60%, or at most 55%, or at most 50%, or at most 45%, or at most 40% of the longest linear axial dimension of the attachment portion. For example, where both the attachment portion 18 and the cut-out portion 20 are cylindrical and the attachment portion 18 has a diameter of 20 mm and the cut-out portion has a diameter of 7 mm, then the longest linear axial dimension (i.e. the diameter) of the cut-out portion 20 would be 35% of the longest linear axial dimension (i.e. the diameter) of the attachment portion 18.

When the cut-out portion 20 is in the form of a blind hole, the maximum length of the cut-out portion 20, measured along the longitudinal axis, may be from 5% of the total length of the attachment portion, measured along the longitudinal axis, to 95% of the total length of the attachment portion, measured along the longitudinal axis, for example from 10% of the total length of the attachment portion, measured along the longitudinal axis, to 90% of the total length of the attachment portion, for example from 15% of the total length of the attachment portion, measured along the longitudinal axis, to 85% of the total length of the attachment portion, for example from 20% of the total length of the attachment portion, measured along the longitudinal axis, to 80% of the total length of the attachment portion, measured along the longitudinal axis, for example from 25% of the total length of the attachment portion, measured along the longitudinal axis, to 75% of the total length of the attachment portion, measured along the longitudinal axis, for example from 30% of the total length of the attachment portion, measured along the longitudinal axis, to 70% of the total length of the attachment portion, measured along the longitudinal axis, for example from 35% of the total length of the attachment portion, measured along the longitudinal axis, to 65% of the total length of the attachment portion, measured along the longitudinal axis, for example from 40% of the total length of the attachment portion, measured along the longitudinal axis, to 60% of the total length of the attachment portion, measured along the longitudinal axis, for example from 45% of the total length of the attachment portion, measured along the longitudinal axis, to 55% of the total length of the attachment portion, measured along the longitudinal axis. The maximum length of the cut-out portion 20, measured along the longitudinal axis, may be at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 35%, or at least 40%, or at least 45% of the total length of the attachment portion, measured along the longitudinal axis. The maximum length of the cut-out portion 20, measured along the longitudinal axis, may be at most 95%, or at most 90%, or at most 85%, or at most 80%, or at most 75%, or at most 70%, or at most 65%, or at most 60%, or at most 55%, or at most 50% of the total length of the attachment portion, measured along the longitudinal axis. For example, where both the total length of the attachment portion 18 is 25 mm and the maximum length of the cut-out portion 20 as measured along the longitudinal axis is 15 mm, then the maximum length of the cut-out portion 20 would be 60% of the total length of the attachment portion 18.

As depicted in Figure 5, as an alternative to the embodiment of Figure 2, instead of having a cut-out portion 20 in the attachment portion 18, a cut-out portion 21 can be provided in the wear-resistant portion 17.

In this embodiment, the cut-out portion 21 is in the form of a blind hole in the wear-resistant portion 17, wherein the blind hole faces the first connection end 24 of the attachment portion 18. While in principle cut-out portion 21 could also be provided in the form of a through hole, in practice this is not favoured as a through hole in the wear-resistant portion 17 would greatly reduce the lifetime of the wear-resistant portion 17. The cut-out portion 21 extends along the longitudinal axis L. In this embodiment, the cut-out portion 21 has a circular cross-section and is coaxial with the cylindrical body of the wear-resistant portion 17. However, the shape of the cross-section of the cut-out portion 21 is not particularly limited, though simpler shapes are simpler to machine. In this embodiment, the cut-out portion 21 has a cylindrical profile. The cut-out portion 21 may have a stepped or tapered profile. The cut-out portion 21 may have an initial portion adjacent to the connecting means 19 with a cylindrical profile and which adjoins a further conical portion which tapers to a point. Alternatively, the further conical portion may have the form of a truncated cone, terminating in a flat planar surface.

The cut-out portion 21, or the bore of the cut-out portion 21, may have a longest linear axial dimension of from 5% of the longest linear axial dimension of the wear-resistant portion to 70% of the longest linear axial dimension of the wear-resistant portion, for example from 10% of the longest linear axial dimension of the wear-resistant portion to 60% of the longest linear axial dimension of the wear-resistant portion, for example from 15% of the longest linear axial dimension of the wear-resistant portion to 50% of the longest linear axial dimension of the wear-resistant portion, for example from 20% of the longest linear axial dimension of the wear-resistant portion to 40% of the longest linear axial dimension of the wear-resistant portion, for example from 30% of the longest linear axial dimension of the wear-resistant portion to 40% of the longest linear axial dimension of the wear-resistant portion. The cut-out portion 21 may have a longest linear axial dimension of at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 35% of the longest linear axial dimension of the wear-resistant portion. The cut-out portion 21 may have a longest linear axial dimension of at most 70%, or at most 65%, or at most 60%, or at most 55%, or at most 50%, or at most 45%, or at most 40% of the longest linear axial dimension of the wear-resistant portion. For example, where both the wear-resistant portion 18 and the cut-out portion 21 are cylindrical and the wear-resistant portion 17 has a diameter of 20 mm and the cut-out portion 21 has a diameter of 7 mm, then the longest linear axial dimension (i.e. the diameter) of the cut-out portion 21 would be 35% of the longest linear axial dimension (i.e. the diameter) of the wear-resistant portion 17.

The maximum length of the cut-out portion 21, measured along the longitudinal axis, may be from 5% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 95% of the total length of the wear-resistant portion, measured along the longitudinal axis, for example from 10% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 90% of the total length of the wear-resistant portion, for example from 15% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 85% of the total length of the wear-resistant portion, for example from 20% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 80% of the total length of the wear-resistant portion, measured along the longitudinal axis, for example from 25% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 75% of the total length of the wear-resistant portion, measured along the longitudinal axis, for example from 30% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 70% of the total length of the wear-resistant portion, measured along the longitudinal axis, for example from 35% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 65% of the total length of the wear-resistant portion, measured along the longitudinal axis, for example from 40% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 60% of the total length of the wear-resistant portion, measured along the longitudinal axis, for example from 45% of the total length of the wear-resistant portion, measured along the longitudinal axis, to 55% of the total length of the wear-resistant portion, measured along the longitudinal axis. The maximum length of the cut-out portion 21, measured along the longitudinal axis, may be at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 35%, or at least 40%, or at least 45% of the total length of the wear-resistant portion, measured along the longitudinal axis. The maximum length of the cut-out portion 20, measured along the longitudinal axis, may be at most 95%, or at most 90%, or at most 85%, or at most 80%, or at most 75%, or at most 70%, or at most 65%, or at most 60%, or at most 55%, or at most 50% of the total length of the wear-resistant portion, measured along the longitudinal axis. For example, where both the total length of the wear-resistant portion 17 is 25 mm and the maximum length of the cut-out portion 21 as measured along the longitudinal axis is 15 mm, then the maximum length of the cut-out portion 21 would be 60% of the total length of the wear-resistant portion 17. Typically, where there is a cut-out portion 21, its total length is at most 50% of the total length of the wear-resistant portion, because removal of too much of the wear-resistant portion by formation of a cut-out 21 could weaken the wear-resistant portion to the point where it can no longer properly perform its function.

As depicted in Figure 6, in a further embodiment both the attachment portion 18 comprises a cut-out portion 20 as described above and the wear-resistant portion 17 comprises a cut-out portion 21 as described above.

While in this embodiment the cut-out portions 20, 21 are mirror images of each other, this is not necessary. Preferably the bores of the cut-out portions 20, 21 correspond with each other, but the length and cross-sectional shape of the cut-out portions 20, 21 can be adapted and altered as required. For example, and as shown in Figure 7, the cut-out portion 21 is likely to be a lower proportion of the wear-resistant portion 17 than the cut-out portion 20 is of the attachment portion 18, because removal of too much of the wear-resistant portion by formation of a cut-out 21 could weaken the wear-resistant portion to the point where it can no longer properly perform its function. The cut-out portions 20, 21 may have differing depths and/or diameters, so long as at least a portion of the cut-out portions 20, 21 overlap. An example of to this is shown in Figure 7, where cut-out portion 20 has a larger diameter and a greater depth than cut-out portion 21.

The use of cut-out portion 20 and/or cut-out portion 21 advantageously allows the provision of a robust, fit-for-purpose insert which is more sustainable as less material is required. Furthermore, and as detailed below, the provision of a cut-out portion provides an improved method of manufacturing the insert.

As depicted in Figure 8, the second connection end 25, i.e. the connection end of the wear-resistant portion 17, may comprise a plurality of protrusions 22 which do not correspond to a cut-out portion 20 of the first connection end 24, and wherein said protrusions 22 extend into the connecting means 19. In this embodiment, the protrusions 22 extend through the connecting means 19 and directly contact the first connection end 24. As an example, these protrusions 22 can be spaced evenly around the periphery of the second connection end 25. Such an arrangement is depicted in Figure 9, which shows six protrusions 22 evenly spaced around the periphery of the second connection end 25. Specifically, the protrusions 22 are equiangularly arranged on the second connection end 25 about the central longitudinal axis L. In this embodiment, the angular spacing 4) between adjacent protrusions 22 is 60 degrees since there are 6 protrusions 22. In another embodiment, (not shown), the angular spacing 41 between the adjacent protrusions 22 is 120 degrees since there are 3 protrusions 22. Any number of protrusions 22 may be arranged on the second connection end 25, as long as none of them correspond to a cut-out portion 20 in the attachment portion 18. For example, the number of protrusions 22 may be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. The protrusions 22 help to create a small gap G1 (as shown in Figure 11) between the wear-resistant portion 17 and the attachment portion 18. For example, the gap G1 may be from 0.1 mm to 1 mm, for example from 0.1 mm to 0.5 mm, for example from 0.2 mm to 0.4 mm. Where the wear-resistant portion 17 and the attachment portion 18 are joined by brazing, the protrusions 22 further increase the surface area of the wear-resistant portion 17 against which the braze bonds, yet further enhancing the shear strength of the join.

When the plurality of protrusions 22 is provided, the first and second connection ends 24, 25 face each other but, aside from any protrusions 22, they do not abut one another.

In the embodiment shown in Figure 9, the wear-resistant portion 17 does not comprise a cut-out portion 21. However, the plurality of protrusions 22 can be combined with a cut-out portion 21 in the wear-resistant portion 17, as depicted in Figure 10.

While in the embodiments disclosed herein the protrusions 22 are on the wear-resistant portion 17, they could also (i.e. in addition to the wear-resistant portion 17) or alternatively be on the attachment portion 18. Protrusions 22 on the attachment portion 18 can be arranged in the same way as those on the wear-resistant portion 17. If protrusions 22 are present on both the wear-resistant portion 17 and the attachment portion 18, they would typically be arranged so that none of the protrusions on the wear-resistant portion 17 are in contact with any of the protrusions on the attachment portion 18.

In the embodiment depicted in Figure 11, there is a plurality of protrusions 22 on the wear-resistant portion 17 (only one is labelled on the Figure for simplicity, but four are visible). Figure 11 depicts the wear-resistant element 7 in an assembled position prior to joining of the wear-resistant portion 17 and the attachment portion 18 by a bonding layer which forms the connecting means 19, in this case a braze layer. A schematic depiction of the embodiment of Figure 11 after brazing is shown in Figure 12, where the connecting means 19 is formed of a braze layer. A cross-sectional view of the brazed wear-resistant element is shown in Figure 13. Here, the protrusions 22 can be seen penetrating the connecting means 19. Additionally, it can be seen that some of the braze used to form the connecting means 19 has partially filled the cut-out portion 20. Thus, in the brazed wear-resistant element, there is a void formed from the remains of cut-out portion 20, which is effectively capped by a braze plug. A similar void formation may also be observed in the above embodiment in which the wear-resistant portion 18 also comprises a cut-out portion 21.

Advantageously, the combination of the above-mentioned plurality of protrusions 22 and cutout portion 20 and/or cut-out portion 21 facilitates a simpler manufacturing process for the insert. Where there is a planar interface between the wear-resistant portion 17 and the attachment portion 18, it is necessary to provide some means for pre-positioning of the wear-resistant portion 17 and the attachment portion 18 prior to brazing. This can, for example, take the form of a circumferential peripheral ridge provided on the attachment portion 18 into which the wear-resistant portion 17 can be seated. However, the disadvantage of the provision of such a circumferential peripheral ridge is that it must be removed post-brazing, for example by grinding, and this adds a laborious step to the manufacturing process. The provision of the plurality of protrusions 22 allows the pre-positioning to be performed using a simple technique such as resistance welding to create a weak bond between the plurality of protrusions 22 and the attachment portion 18 and/or the wear resistant portion 17 (depending on where the plurality of protrusions 22 are positioned). Placing the braze inside the cut-out portion 20 and/or the cut-out portion 21 allows this welding process, which requires direct contact between the plurality of protrusions 22 and the attachment portion 18 and/or the wear to resistant portion 17, to occur, and the braze is then ready for the subsequent brazing step.

The insert 7 is typically inverted during the brazing process, such that the attachment portion 18 is above the wear-resistant portion 17. Thus, the combination of the plurality of protrusions 22 and the cut-out portion 20 and/or the cut-out portion 21 facilitates manufacturing of the composite insert, thereby providing time savings.

As shown in Figure 14, instead of a cut-out portion 20 in the form of a blind hole as depicted in Figure 13, the cut-out portion 20 may be in the form of a through hole. As noted above, the provision of the cut-out portion 20 in the form of a through hole helps to provide a stronger braze connection between the attachment portion 18 and the wear-resistant portion 17.

As shown in Figure 15, instead of a cut-out portion 20 in the form of a blind hole as depicted in Figure 13, the cut-out portion 20 may be in the form of a through hole, and the wear-resistant portion 17 may further comprise a cut-out portion 21 in the form of a blind hole.

The drill insert as described herein enables the provision of a more sustainable drill bit than what has been previously available.

Furthermore, each composite insert has a better fit in the steel body of the drill bit because the portion of the insert in contact with the drill bit will have a much more closely matched hardness to the steel than an insert with higher wear resistance (and therefore hardness). As a result of this, the copper shim which is typically used to attach inserts to a drill bit body can be omitted, simplifying the manufacturing process.

Lastly, combination material inserts also provide for the higher utilisation of tungsten carbide.

The above-described insert is described in the context of a drill bit. However, the same insert design principle can be applied to any type of insert. For example, the insert could be used in a disc cutter mounted in a tunnel boring machine or in a tricone or roller cone bit of the type used for drilling in the oil and gas industry.

In a further embodiment, as shown in Figure 16, the insert comprises a layer 310 of superhard material integrally bonded to the impact surface 8 of the wear-resistant portion 17. This layer 310 of super-hard material can be combined with any of the previously described embodiments. For example, layer 310 could be combined with any of the inserts or insert components depicted in Figures 1-15. In a preferred embodiment, the super-hard material is polycrystalline diamond (PCD) and the wear-resistant portion 17 is cemented tungsten carbide. In use, the attachment portion 18 and preferably part of the wear-resistant portion 17 is embedded into insert holders, in this case recesses within a drill bit head, the insert holders (not shown) adapted to receive and hold securely the inserts 7.

The term "super-hard" used in relation to a material is understood to mean that the material has a hardness of at least 30 GPa. Diamond and cubic boron nitride (cBN) are examples of super-hard material.

As used herein, PCD comprises a plurality of diamond grains, a substantial number of which are directly inter-bonded with each other and in which the content of the diamond is at least about 80 volume per cent of the material. Interstices between the diamond grains may be substantially empty or they may be at least partly filled with a bulk filler material or they may be substantially empty. The bulk filler material may comprise sinter promotion material.

An embodiment of a percussion drill bit assembly is described with reference to Figures 17 and 18, which comprise a drill bit head, 100, comprising a cemented carbide drill bit head body, 110, to which has been affixed a plurality of inserts 7 as described herein and a steel anvil portion 200 of a drill bit. Each insert 7 is as detailed above and is embedded into the drill bit head body 110 with the wear-resistant portion protruding from a working surface of the drill bit head body 110 which comprises a plurality of insert holders, in this case recesses, adapted to accommodate and securely hold the plurality of inserts 7. The working surface has at least one hard area 135 free of inserts 7. The drill bit head body 110 comprises at least one through-hole 160 to conduct a fluid which may be introduced to flush out debris. The drill bit head 100 is mounted or mountable onto an anvil portion 200 of a drill bit assembly (not shown).

A flow diagram summarising a first method of manufacturing an insert, for example, the above-mentioned insert, is shown in Figure 19. The first method has the steps S1-34.

Si. Providing an attachment portion (i.e. of an insert) comprising a first connection end, wherein the first connection end comprises a cut-out portion, and a wear-resistant portion comprises a second connection end which comprises a plurality of protrusions which do not correspond to the cut-out portion of the first connection end.

The attachment portion has an attachment end configured to connect to an insert holder and which opposes the first connection end. The attachment portion further comprises a first side wall connecting the attachment end to the first connection end. The wear-resistant portion has an impact surface and an opposing second connection end. The wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end. The first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert. The cut-out portion of the first connection end extends along the longitudinal axis. As detailed above, the cut-out portion may to be a blind hole or a through hole. The second connection end does not comprise a protrusion which corresponds to the cut-out portion of the first connection end.

S2. Placing a braze material in the cut-out portion of the attachment portion. The braze material may be in any suitable form, for example, the form of a rod.

S3. Positioning the plurality of protrusions of the second connection end on the first connection end.

This step is done such that the first side wall of the attachment portion is in longitudinal alignment with the second side wall of the wear resistant portion.

S4. Attaching the protrusions to the attachment portion, for example, by resistance welding, to form a pre-connection assembly.

S5. Heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming an insert.

In an alternative embodiment of the first method, the second connection end rather than the first connection end comprises a cut-out portion, the first connection end rather than the second connection end comprises a plurality of protrusions which do not correspond to the cut-out portion of the second connection end, and the braze material is placed in the cut-out portion of the second connection end.

A second example method of manufacturing an insert is shown in Figure 20. Instead of the plurality of protrusions being provided on the wear-resistant portion, they can instead be provided on the attachment portion.

S1. Providing an attachment portion comprising a first connection end and a wear-resistant portion comprising a second connection end, wherein the first connection end comprises a cut-out portion and a plurality of protrusions.

S2. Placing a braze material in the cut-out portion of the attachment portion (as above).

S3. Positioning the second connection end of the wear resistant portion on the plurality of protrusions on the first connection end of the attachment portion.

S4. Attaching the protrusions to the wear-resistant portion, for example, by resistance welding, to form a pre-connection assembly.

S5. Heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming a wear-resistant element.

In an alternative embodiment of the second method, the second connection end rather than the first connection end comprises a cut-out portion, the second connection end rather than the first connection end comprises a plurality of protrusions, and the braze material is placed in the cut-out portion of the second connection end.

In a third exemplary method, as outlined in Figure 21, a plurality of protrusions can be provided on both the attachment portion and the wear-resistant portion.

In an alternative embodiment of the third method, the second connection end rather than the first connection end comprises a cut-out portion.

In any of the above methods, both the first and second connection ends may comprise cutout portions. In such an embodiment, the braze material may either be placed in the cut-out portion of only one of the first and second connection ends, or it may be placed in both cut-out portions. As detailed above, the cut-out portion(s) may be a blind hole or a through hole.

In all of the above methods, it is advantageously not required to perform a grinding step to remove any locating means from the attachment portion after the brazing step. This simplifies the manufacturing method.

The invention as set out in the appended claims has been shown and described with reference to embodiments. However, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as defined by the appended claims.

For example, other types of material could be used, such as hardened steel, and the insert may have a shape other than cylindrical as described in the examples.

Certain embodiments of the present invention include: 1. An insert comprising an attachment portion and a wear-resistant portion arranged along a longitudinal axis; wherein the attachment portion has an attachment end configured to connect to an insert holder and an opposing first connection end; wherein the wear-resistant portion has an impact surface and an opposing second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein: the first connection end comprises a cut-out portion which extends along the longitudinal axis; and wherein the second connection end does not comprise a protrusion which corresponds to the cut-out portion of the first connection end; and/or the second connection end comprises a cut-out portion which extends along the longitudinal axis; and wherein the first connection end does not comprise a protrusion which corresponds to the cut-out portion of the second connection end.

2. The insert of embodiment 1, wherein the insert is a drill bit insert, preferably a percussive drill bit insert.

3. The insert of embodiment 1 or embodiment 2, further comprising a connecting means between the first connection end and the second connection end.

4. The insert of embodiment 3, wherein the first connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to a cut-out portion of the second connection end, and wherein said protrusions extend through the connecting means.

5. The insert of embodiment 3 or embodiment 4, wherein the second connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to a cut-out portion of the first connection end, and wherein said protrusions extend through the connecting means.

6. The insert of embodiment 4 or embodiment 5, wherein the protrusions on the first connection end are equiangularly arranged about the longitudinal axis.

7. The insert of embodiment 5 or embodiment 6, wherein the protrusions on the second connection end are equiangularly arranged about the longitudinal axis.

8. The insert of any one of embodiments 3 to 7, wherein the connecting means at least partially fills the cut-out portion of the first and/or second connection end.

9. The insert of any one of embodiments 3 to 8, wherein the connecting means is a braze layer.

10. The insert of any one of the preceding embodiments, wherein the cut-out portion of the first and/or second connection end has a cylindrical portion adjacent the connecting means and connected to a conical portion or a truncated conical portion.

11. The insert of any one of the preceding embodiments, wherein the attachment portion is substantially cylindrical, and the wear-resistant portion comprises a substantially cylindrical body attached to a dome-shaped tip.

12. The insert of any one of the preceding embodiments, wherein the attachment portion comprises a first material having a first hardness, and wherein the wear-resistant portion comprises a second material having a second hardness; wherein the hardness of the second material is greater than that of the first material.

13. The insert of embodiment 12, wherein the first material comprises a steel and the second material comprises a cemented tungsten carbide.

14. The insert of embodiment 12 or embodiment 13, wherein the first material has a Vickers hardness of between 100 and 500 HV30, and the second material has a Vickers hardness of between 900 and 1400 HV30.

15. The insert of any one of the preceding embodiments, wherein the wear resistant portion and the attachment portion have corresponding diameters at their respective ends and are provided in a volumetric ratio of from 1:1 to 5:1.

16. The insert of any one of the preceding embodiments, further comprising a layer of super-hard material integrally bonded to the impact surface of the wear-resistant portion.

17. The insert of embodiment 16, wherein the super-hard material is polycrystalline diamond.

18. A drill bit comprising: a drill bit body with an impact face and a plurality of wear-resistant inserts according to any one of the preceding claims, each insert seated in a correspondingly shaped insert holder in the impact face.

19. A drill bit as claimed in embodiment 18, wherein each insert is attached to the drill bit body by any one of the following techniques: gluing, brazing, press-fitting, shrink fitting, threaded connection, and mechanical connection.

20. A method of manufacturing an insert, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion comprising a plurality of protrusions, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the first connection end comprises a cut-out portion which extends along the longitudinal axis and wherein the second connection end does not comprise a protrusion which corresponds to the cut-out portion of the first connection end; and/or wherein the second connection end comprises a cut-out portion which extends along the longitudinal axis and wherein the first connection end does not comprise a protrusion which corresponds to the cut-out portion of the second connection end; wherein the second connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to the cut-out portion of the first connection end; placing a braze material in the cut-out portion of the attachment portion and/or in the cut-out portion of the wear-resistant portion; positioning the plurality of protrusions of the second connection end on the first connection end such that the first side wall of the attachment portion is in longitudinal alignment with the second side wall of the wear resistant portion; attaching the protrusions to the attachment portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming a wear-resistant element.

21. A method of manufacturing an insert, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the first connection end comprises a cut-out portion which extends along the longitudinal axis; wherein the first connection end comprises a plurality of protrusions; placing a braze material in the cut-out portion of the attachment portion; positioning the second connection end on the plurality of protrusions of the first connection end such that the first side to wall of the attachment portion is in longitudinal alignment with the second side wall of the wear resistant portion; attaching the protrusions to the wear-resistant portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming an insert.

22. A method of manufacturing an insert, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the second connection end comprises a cut-out portion which extends along the longitudinal axis; wherein the second connection end comprises a plurality of protrusions; placing a braze material in the cut-out portion of the wear-resistant portion; positioning the first connection end on the plurality of protrusions of the second connection end such that the second side wall of the wear-resistant portion is in longitudinal alignment with the first side wall of the attachment portion; attaching the protrusions to the connection portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming an insert.

Claims

Claims 1. An insert comprising an attachment portion and a wear-resistant portion arranged along a longitudinal axis; wherein the attachment portion has an attachment end configured to connect to an insert holder and an opposing first connection end; wherein the wear-resistant portion has an impact surface and an opposing second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; and further comprising a connecting means between the first connection end and the second connection end; wherein: the first connection end comprises a cut-out portion which extends along the longitudinal axis; and wherein the second connection end does not comprise a protrusion which corresponds to the cut-out portion of the first connection end; and/or the second connection end comprises a cut-out portion which extends along the longitudinal axis; and wherein the first connection end does not comprise a protrusion which corresponds to the cut-out portion of the second connection end; and wherein: the first connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to a cut-out portion of the second connection end, and wherein said protrusions extend through the connecting means and directly contact the second connection end; and/or the second connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to a cut-out portion of the first connection end, and wherein said protrusions extend through the connecting means and directly contact the second connection end.
The insert of claim 1, wherein the insert is a drill bit insert.
The insert of claim 2, wherein the drill bit insert is a percussive drill bit insert.
4. The insert of any one of claims 1 to 3, wherein the protrusions on the first connection end are equiangularly arranged about the longitudinal axis.
5. The insert of any one of claims 1 to 4, wherein the protrusions on the second connection end are equiangularly arranged about the longitudinal axis.
6. The insert of any one of the preceding claims, wherein the connecting means at least partially fills the cut-out portion of the first connection end.
7. The insert of any one of the preceding claims, wherein the connecting means at least partially fills the cut-out portion of the second connection end.
8. The insert of any one of the preceding claims, wherein the connecting means is a braze layer.
9. The insert of any one of the preceding claims, wherein the cut-out portion of the first and/or second connection end has a cylindrical portion adjacent the connecting means and connected to a conical portion or a truncated conical portion.
10. The insert of any one of the preceding claims, wherein the attachment portion is substantially cylindrical, and the wear-resistant portion comprises a substantially cylindrical body attached to a dome-shaped tip.
11. The insert of any one of the preceding claims, wherein the attachment portion comprises a first material having a first hardness, and wherein the wear-resistant portion comprises a second material having a second hardness; wherein the hardness of the second material is greater than that of the first material.
12. The insert of claim 11, wherein the first material comprises a steel and the second material comprises a cemented tungsten carbide.
13. The insert of claim 11 or claim 12, wherein the first material has a Vickers hardness of between 100 and 500 HV30, and the second material has a Vickers hardness of between 900 and 1400 HV30.
14. The insert of any one of the preceding claims, wherein the wear resistant portion and the attachment portion have corresponding diameters at their respective ends and are provided in a volumetric ratio of from about 1:1 to about 5:1.
15. The insert of any one of the preceding claims, further comprising a layer of super-hard material integrally bonded to the impact surface of the wear-resistant portion.
16. The insert of claim 15, wherein the super-hard material is polycrystalline diamond.
17. The insert of any one of the preceding claims, wherein the cut-out portion of the first connection end has the form of a blind hole.
18. The insert of any one of claims 1 to 16, wherein the cut-out portion of the first connection end has the form of a through hole.
1 9. The insert of any one of the preceding claims, wherein the cut-out portion of the second connection end has the form of a blind hole.
20. The insert of any one of claims 1 to 18, wherein the cut-out portion of the second connection end has the form of a through hole.to
21. A drill bit comprising: a drill bit body with an impact face and a plurality of wear-resistant inserts according to any one of the preceding claims, each insert seated in a correspondingly shaped insert holder in the impact face.
22. A drill bit as claimed in claim 21, wherein each insert is attached to the drill bit body by any one of the following techniques: gluing, brazing, press-fitting, shrink fitting, threaded connection, and mechanical connection.
23. A method of manufacturing an insert, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion comprising a plurality of protrusions, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the first connection end comprises a cut-out portion which extends along the longitudinal axis and wherein the second connection end does not comprise a protrusion which corresponds to the cut-out portion of the first connection end; and/or wherein the second connection end comprises a cut-out portion which extends along the longitudinal axis and wherein the first connection end does not comprise a protrusion which corresponds to the cut-out portion of the second connection end; wherein the second connection end comprises a plurality of protrusions, wherein said protrusions do not correspond to the cut-out portion of the first connection end; placing a braze material in the cut-out portion of the attachment portion and/or in the cut-out portion of the wear-resistant portion; positioning the plurality of protrusions of the second connection end on the first connection end such that the first side wall of the attachment portion is in longitudinal alignment with the second side wall of the wear resistant portion; attaching the protrusions to the attachment portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming a wear-resistant element.
24. A method of manufacturing an insert, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the first connection end comprises a cut-out portion which extends along the longitudinal axis; wherein the first connection end comprises a plurality of protrusions; placing a braze material in the cut-out portion of the attachment portion; positioning the second connection end on the plurality of protrusions of the first connection end such that the first side wall of the attachment portion is in longitudinal alignment with the second side wall of the wear resistant portion; attaching the protrusions to the wear-resistant portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming an insert.
25. A method of manufacturing an insert, comprising: providing an attachment portion, wherein the attachment portion has an attachment end and an opposing first connection end, wherein the attachment portion further comprises a first side wall connecting the attachment end to the first connection end; and providing a wear-resistant portion, wherein the wear-resistant portion has an impact surface and an opposing second connection end, wherein the wear resistant portion further comprises a second side wall connecting the impact surface to the second connection end; wherein the first connection end is configured to connect to the second connection end such that the attachment end of the attachment portion and the impact surface of the wear-resistant portion are at opposing longitudinal extremities of the insert; wherein the second connection end comprises a cut-out portion which extends along the longitudinal axis; wherein the second connection end comprises a plurality of protrusions; placing a braze material in the cut-out portion of the attachment portion; positioning the first connection end on the plurality of protrusions of the second connection end such that the first side wall of the wear-resistant portion is in longitudinal alignment with the second side wall of the attachment portion; attaching the protrusions to the connection portion to form a pre-connection assembly; and heating the pre-connection assembly so as to form a braze layer between the wear-resistant portion and the attachment portion, wherein the plurality of protrusions extends through the braze layer, thereby forming an insert.