WO2025254575A1

WO2025254575A1 - A drill bit configured for reverse circulation down-the-hole drilling

Info

Publication number: WO2025254575A1
Application number: PCT/SE2024/050551
Authority: WO
Inventors: Jimmy Carlsson
Original assignee: Epiroc Rock Drills AB
Current assignee: Epiroc Rock Drills AB
Priority date: 2024-06-04
Filing date: 2024-06-04
Publication date: 2025-12-11
Anticipated expiration: 2026-12-04

Abstract

A drill bit (6), configured for reverse circulation down-the-hole drilling, the drill bit comprising a first end (8), a second end (10), and a central axis (C) extending therebetween, wherein the first end comprises a drill face (12), configured to break a mineral substrate (14). The drill bit comprises a peripheral surface (16), extending around the central axis, between the first end and the second end, a central channel (18) extending from the second end towards the first end, and an exhaust channel (20) extending from the central channel to an exhaust opening (22), formed in the drill face. The drill bit further comprises a side flushing channel (24), extending from a flushing opening (26), formed in the peripheral surface, to the exhaust channel. The side flushing channel extends from the flushing opening in a flushing direction (F), the flushing direction having at least a component acting parallel to the central axis, towards the exhaust opening, such that a flow of fluid through the side flushing channel into the exhaust channel is directed towards the exhaust opening.

Description

A DRILL BIT CONFIGURED FOR REVERSE CIRCULATION DOWN-THE-HOLE DRILLING

TECHNICAL FIELD

The present disclosure concerns a drill bit. The invention also concerns a drilling apparatus and a drill rig. The disclosed drill bit, drilling apparatus, and drill rig may for example be applied in rock drilling and/or down-the-hole drilling operations.

BACKGROUND

Where a drill bit is to be used, for example for rock drilling and/or down-the-hole drilling applications, it may be necessary to supply and remove a fluid to/from a mineral substrate to be drilled for the purpose of flushing. In such cases the drill bit may be configured for providing a flow path for the fluid. In at least some cases reverse circulation of the fluid may be preferable, wherein fluid is supplied via a peripheral surface of the drill bit and removed via a central channel. During a drilling operation, wherein the drill bit breaks a mineral substrate forming particles, the particles formed may in some cases become stuck in the drill bit causing a blockage. Blockages may prevent the flow of the drilling fluid through the drill bit, and thus lead to reduced performance. Therefore, there exists a need to provide an improved drill bit.

SUMMARY

A primary objective of the present disclosure is to achieve an in at least some aspect improved drill bit, drilling apparatus, and/or drill rig. For example, it is an objective to achieve a drill bit which may mitigate the occurrence of blockages in the drill bit.

According to a first aspect of the disclosure, at least the primary object is achieved by a drill bit according to claim 1. Hence, there is provided a drill bit, configured for reverse circulation down-the-hole drilling, the drill bit comprising a first end, a second end, and a central axis extending therebetween, wherein the first end comprises a drill face, configured to break a mineral substrate, the drill bit further comprising a peripheral surface, extending around the central axis, between the first end and the second end, a central channel extending from the second end towards the first end, an exhaust channel extending from the central channel to an exhaust opening, formed in the drill face, a side flushing channel, extending from a flushing opening, formed in the peripheral surface, to the exhaust channel, wherein the side flushing channel extends from the flushing opening in a flushing direction, the flushing direction having at least a component acting parallel to the central axis, towards the exhaust opening, such that a flow of fluid through the side flushing channel into the exhaust channel is directed towards the exhaust opening.

By providing a drill bit having a side flushing channel extending in a flushing direction such that a flow of fluid through the side flushing channel into the exhaust channel is directed towards the exhaust opening, in at least some examples a force may be applied by a fluid flow directed towards the exhaust opening. In at least some examples the force may blockages caused by particles formed during the breaking of the mineral substrate may be, in at least some cases, broken down into smaller particles and/or dislodged from the drill bit such that the occurrence of blockages in the drill bit may be mitigated against such that performance of a drilling operation may be improved. For example, during a drilling operation where solid particles, such as clay particles, enter the exhaust channel and become stuck on a surface thereof, the pressure at the side flushing opening may increase and the flow through the side flushing channel into the exhaust channel may exert a force on the blockage, breaking down the clay particles such that they become unstuck.

In at least some examples during a drilling operation, wherein the drill bit breaks a mineral substrate, the central axis may correspond to a gravitational direction. Alternatively, in at least some examples the central axis may be inclined with respect to the gravitational direction, for example for a horizontal drilling application. In at least some examples the peripheral surface may comprise a cylindrical outer surface. Furthermore, in at least some examples the peripheral surface may comprise any number of recesses and or protrusions which may be configured for attaching the drill bit to additional components, guiding fluid, etc. In at least some examples the peripheral surface may comprise a first surface portion, and a second surface portion, wherein the first surface portion extends from the first end and the second surface portion is located closer to the second end than the first surface portion. A radial direction may be defined acting perpendicular to the central axis. In at least some examples the first surface portion may be radially outer to the second surface portion such that the first surface portion is further from the central axis along the radial direction. By having a peripheral surface wherein, a second surface portion is located closer to the second end than a first surface portion a space may be formed radially outer to the peripheral surface, relative to the central axis C, for the supply of fluid to the mineral substrate. In at least some examples the flushing direction may have a component acting parallel to the central axis and a component acting perpendicular to the central axis, such that the flushing direction is inclined with respect to the central axis.

However, in at least some embodiments there is provided a drill bit, configured for reverse circulation down-the-hole drilling, the drill bit comprising a first end, a second end, and a central axis extending therebetween, wherein the first end comprises a drill face, configured to break a mineral substrate, the drill bit further comprising a peripheral surface, extending around the central axis, between the first end and the second end, a central channel extending from the second end towards the first end, an exhaust channel extending from the central channel to an exhaust opening, formed in the drill face, a side flushing channel, extending from a flushing opening, formed in the peripheral surface, to the exhaust channel, wherein the side flushing channel extends from the flushing opening towards the exhaust opening, such that a flow of fluid through the side flushing channel into the exhaust channel is directed towards the exhaust opening.

By providing a drill bit having a side flushing channel extending in a flushing direction such that a flow of fluid through the side flushing channel into the exhaust channel is directed towards the exhaust opening, in at least some examples a force may be applied by a fluid flow directed towards the exhaust opening. In at least some examples the force may blockages caused by particles formed during the breaking of the mineral substrate may be, in at least some cases, broken down into smaller particles and/or dislodged from the drill bit such that the occurrence of blockages in the drill bit may be mitigated against such that performance of a drilling operation may be improved.

Optionally, the central channel extends along the central axis. By having the central channel extending along the central axis a direct path may be formed for the removal of fluid from the mineral substrate.

Optionally, the exhaust channel is inclined with respect to the central axis. By having the exhaust channel inclined with respect to the central axis, in at least some examples a flow from the mineral substrate and/or along the drill face, to the central channel may be improved. In at least some examples, such as where the central channel extends along the central axis the exhaust opening may be outer to a centre portion of the drill face, such that the centre portion of the drill face may be configured for breaking the mineral substrate. Furthermore, in at least some examples by having the exhaust channel inclined with respect to the central axis it may be possible to have a plurality of exhaust channels extending from the central channel to a plurality of exhaust openings formed in the drill face.

Optionally, the drill bit comprises at least one additional side flushing channel extending from an additional flushing opening, formed in the peripheral surface, to the exhaust channel, the additional side flushing channel extending from the peripheral surface in an additional flushing direction, the additional flushing direction having at least a component acting parallel to the central axis, towards the exhaust opening. By having at least one additional side flushing channel in at least some examples the additional flushing channel may be configured for supplying fluid to a different portion of the exhaust channel, or at a different angle relative to the exhaust channel, having a different cross-sectional area such that fluid may be supplied at a different pressure, such that the mitigation of the occurrence of different types of blockages, and at different locations in the exhaust channel, may be improved.

Optionally, the drill bit comprises at least one additional side flushing channel extending from an additional flushing opening, formed in the peripheral surface, to the exhaust channel, the additional side flushing channel extending from the peripheral surface towards the exhaust opening. By having at least one additional side flushing channel in at least some examples the additional flushing channel may be configured for supplying fluid to a different portion of the exhaust channel, or at a different angle relative to the exhaust channel, having a different cross-sectional area such that fluid may be supplied at a different pressure, such that the mitigation of the occurrence of different types of blockages, and at different locations in the exhaust channel, may be improved.

Optionally, the drill bit comprises a further exhaust channel extending from the central channel to a further exhaust opening, formed in the drill face, wherein the further exhaust channel is configured with a further side flushing channel. By having at least one further exhaust channel in at least some examples the rate of removal of fluid from the mineral substrate may be increased.

Optionally, the cross-sectional area of the exhaust channel is less than the cross-sectional area of the central channel. By having a cross-sectional area less than that of the central channel a flow of fluid through the exhaust channel will have a higher pressure than that through the central channel. In at least some examples the cross-sectional area is constant along the extension of the exhaust channel and/or the central channel. Alternatively, in at least some examples the cross-sectional area of the exhaust channel and/or the central channel may vary along the extension. Where the cross-sectional area of the exhaust channel and/or the central channel varies along the extension, the crosssection area of the exhaust channel and/or the central channel may be defined as the average cross-sectional area along the extension thereof. Furthermore, in at least some examples the sum of the cross-sectional areas of a plurality of exhaust channels is less than the cross-sectional area of the central channel.

Optionally, the cross-sectional area of the side flushing channel is less than the cross- sectional area of the exhaust channel. By having a cross-sectional area less than that of the exhaust channel a flow of fluid through the side flushing channel will have a higher pressure than that through the exhaust channel. In at least some examples the cross- sectional area is constant along the extension of the side flushing channel. Alternatively, in at least some examples the cross-sectional area of the side flushing channel may vary along the extension. Where the cross-sectional area of the side flushing channel varies along the extension, the cross-section area of the side flushing channel may be defined as the average cross-sectional area along the extension thereof. Furthermore, in at least some examples the sum of the cross-sectional areas of a plurality of side flushing channels in fluid communication with each exhaust channel is less than the cross- sectional area of the exhaust channel.

According to a second aspect of the disclosure, at least the primary object is achieved by a drilling apparatus according to claim 8, the drilling apparatus further comprising a fluid actuation system, configured to supply fluid along the peripheral surface of the drill bit towards the drill face, and to remove fluid via the central channel away from the drill face.

By providing a drilling apparatus comprising the drill bit and a fluid actuation system, a drilling apparatus wherein the occurrence of blockages in the drill bit may be mitigated against may be achieved. In at least some examples the fluid actuation system comprises a compressor. In at least some examples the fluid actuation system comprises a single fluid actuation device configured to both supply fluid to the mineral substrate, and to remove fluid from the mineral substrate. Alternatively, in at least some examples the fluid actuation system may comprise a plurality of fluid actuation devices, such as a fluid supply device configured to supply fluid to the mineral substrate and a fluid removal device configured to remove fluid from the mineral substrate.

Optionally, the drilling apparatus further comprises a peripheral sleeve, configured to surround the central axis such that at least a portion of the peripheral sleeve surrounds a portion of the peripheral surface of the drill bit, and a peripheral channel is formed therebetween. By providing a peripheral sleeve in at least some examples a fluid supply path may be formed. Furthermore, in at least some examples a sealing may be achieved between a peripheral wall of the mineral substrate and the peripheral sleeve, such that the return of fluid via a path formed inner to the drill bit may be improved.

Optionally, the side flushing channel is configured for fluid communication between the peripheral channel and the exhaust channel.

Optionally, the cross-sectional area of the side flushing channel is less than the cross- sectional area of the peripheral channel. By having a cross-sectional area less than that of the peripheral channel a flow of fluid through the side flushing channel will have a higher pressure than that through the peripheral channel. In at least some examples the cross- sectional area is constant along the extension of the peripheral channel. Alternatively, in at least some examples the cross-sectional area of the peripheral channel may vary along the extension. Where the cross-sectional area of the peripheral channel varies along the extension, the cross-section area of the peripheral channel may be defined as the average cross-sectional area along the extension thereof. Furthermore, in at least some examples the sum of the cross-sectional areas of a plurality of side flushing channels in fluid communication with the peripheral channel is less than the cross-sectional area of the peripheral channel.

According to a third aspect of the disclosure, at least the primary object is achieved by a drill rig according to claim 12. By providing a drill rig comprising the drilling apparatus, a drill rig wherein the occurrence of blockages in the drill bit may be mitigated against may be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS (OPTIONAL)

With reference to the appended drawings, below follows a more detailed description of embodiments of the disclosure cited as examples.

Fig. 1 is a schematic diagram of a drill rig according to an embodiment of the disclosure,

Fig. 2 is a schematic diagram of a drill bit according to an embodiment of the disclosure,

Fig. 3 is a schematic diagram of a drill bit according to an embodiment of the disclosure,

Fig. 4 is a perspective view of a drill bit according to an embodiment of the disclosure,

Fig. 5 is a schematic diagram of a drilling apparatus according to an embodiment of the disclosure,

Fig. 6 is a schematic diagram of a drilling apparatus according to an embodiment of the disclosure,

Fig. 7 is a schematic diagram of a drilling apparatus according to an embodiment of the disclosure,

The drawings show diagrammatic, exemplifying embodiments of the present disclosure and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the disclosure is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the disclosure. Like reference characters refer to like elements throughout the description, unless expressed otherwise. DETAILED DESCRIPTION

Fig. 1 illustrates schematically a drill rig 2 comprising a drilling apparatus 4. The drilling apparatus 4 is configured to perform a drilling operation in which the drilling apparatus 4 breaks a mineral substrate 14. In the shown example the drilling apparatus 4 comprises a drill bit 6. The drill bit 6 is configured to break the mineral substrate 14, during a drilling operation. During the drilling operation the drill bit 6 breaks the mineral substrate 14 such that a hole 15 is formed. The drilling apparatus 4 may for example be configured for rock drilling and/or down-the-hole drilling operations. The hole 15 may comprise a circular cross-section. In the shown example the drill rig 2 comprises a mobile drill rig comprising a carrier portion having tracks for the movement thereof. In alternative examples the drill rig 2 may comprise wheels, or may be towable, to enable mobility thereof. Furthermore, in at least some examples the drill rig 2 may comprise a fixed structure. The drill rig 2 may comprise at least one power source (not shown) for powering the drilling apparatus 4, and any further equipment of the drill rig 2 such as tracks etc. The power source may comprise an engine, such as a diesel engine, or alternatively an electric motor, or any known power source. The drill rig 2 may be a manned drill rig 2 and may comprise a cabin wherein the drilling apparatus 4 and/or the movement of the drill rig 2 may be controlled, or alternatively the drill rig 2 may be a remote controlled, autonomous, or semi- autonomous drill rig. The drilling apparatus 4 comprises a drill bit (described with reference to Fig. 2-4).

Fig. 2 illustrates schematically a drill bit 6 according to an embodiment of the disclosure. The drill bit 6 is configured for the supply and the removal of fluid to/from the mineral substrate 14. The supply and the removal of fluid to/from the mineral substrate 14 may be for the purpose of flushing, such that particles formed during the breaking of the mineral substrate 14 may be removed from the hole 15 (illustrated in Fig. 1). The drill bit 6 is configured for reverse circulation, wherein fluid is supplied to the mineral substrate 14 via a fluid supply path F_s, wherein the fluid supply path F_s is formed outer to the drill bit 6, and fluid is removed from the mineral substrate 14 via a fluid removal path FR, wherein the fluid removal path FR is formed inner to the drill bit 6. In at least some examples the fluid may comprise air. Alternatively, in at least some examples the fluid may comprise another gas, such as an inert gas, or a liquid, such as drilling mud.

In the shown example the drill bit 6 comprises a first end 8, a second end 10, and a central axis C extending therebetween. In the shown example the first end 8 comprises a drill face 12, configured to break the mineral substrate 14. In the shown example the drill face 12 comprises a plurality of buttons 32 configured to break the mineral substrate 14.

The drill bit 6 may be actuated along the central axis C, and/or about the central axis C during a drilling operation, wherein the drill bit 6 breaks the mineral substrate 14. In at least some examples the actuation of the drill bit 6 may be achieved by pneumatic or hydraulic means. In at least some examples the actuation of the drill bit 6 may be achieved by the same fluid supplied and removed to/from the mineral substrate 14. In at least some examples a piston (described later with reference to Fig. 5-7) may be located at the second end 10 of the drill bit 6, wherein the piston may be actuated along the central axis C such that the piston impacts the drill bit 6 and the drill bit 6 breaks the mineral substrate 14. In at least some examples during a drilling operation, the central axis C may correspond to a gravitational direction G. Alternatively, in at least some examples the central axis C may be inclined with respect to the gravitational direction G, for example for a horizontal drilling application.

In the shown example the drill bit 6 further comprises a peripheral surface 16, extending around the central axis C, between the first end 8 and the second end 10. In at least some examples the peripheral surface 16 may comprise a cylindrical outer surface. Furthermore, in at least some examples the peripheral surface 16 may comprise any number of recesses and or protrusions which may be configured for attaching the drill bit 6 to additional components, guiding fluid, etc. In at least some examples the peripheral surface 16 may comprise a first surface portion 34, and a second surface portion 36, wherein the first surface portion 34 extends from the first end 6 and the second surface portion 36 is located closer to the second end 10 than the first surface portion 34. A radial direction R may be defined acting perpendicular to the central axis C. In at least some examples the first surface portion 34 may be radially outer to the second surface portion 36 such that the first surface portion 34 is further from the central axis C along the radial direction R.

In the shown example a central channel 18 extends from the second end 10 towards the first end 8. In the shown example the central channel 18 extends along the central axis C. Furthermore, in the shown example the central channel 18 is coaxial with the central axis C. In at least some examples the central channel 18 may be offset from the central axis C. Furthermore, in the shown example an exhaust channel 20 extends from the central channel 18 to an exhaust opening 22, formed in the drill face 12. In the shown example the exhaust channel 20 is inclined with respect to the central axis C. In at least some examples the exhaust channel may be inclined by 5-75° with respect to the central axis C. Alternatively, in at least some examples the exhaust channel 20 may be parallel with the central axis C. In the shown example the cross-sectional area of the exhaust channel 20 is less than the cross-sectional area of the central channel 18. In at least some examples the cross-sectional area of the central channel 18 and/or the exhaust channel 20 is constant. Alternatively, in at least some examples the cross-sectional area of the central channel 18 and/or the exhaust channel 20 may vary along the extension thereof. Where the cross-sectional area of the central channel 18 and/or the exhaust channel 20 varies along the extension, the cross-section area may be defined as the average cross- sectional area of the central channel 18 and/or the exhaust channel 20. In the shown example the exhaust channel 20 is a straight channel. In at least some examples at least a portion of the exhaust channel 20 may be curved.

In the shown example a side flushing channel 24, extends from a flushing opening 26, formed in the peripheral surface 16, to the exhaust channel 20. In the shown example the cross-sectional area of the side flushing channel 24 is less than the cross-sectional area of the exhaust channel 20. In at least some examples the cross-sectional area of the side flushing channel 24 may vary along the extension thereof. Where the cross-sectional area of the side flushing channel 24 varies along the extension, the cross-section area may be defined as the average cross-sectional area of the side flushing channel 24. In the shown example the side flushing channel 24 is a straight channel. In at least some examples at least a portion of the side flushing channel 24 may be curved.

Furthermore, in the shown example the drill bit 6 may be configured such that the fluid supply path F_s comprises a flushing supply portion F_Sf, wherein the flushing supply portion F_Sf comprises a portion of the fluid supply path F_s configured to supply fluid to the flushing opening 26. In at least some examples the flushing supply portion F_Sf has a cross- sectional area greater than the cross-sectional area of the side flushing channel 24. In at least some examples the cross-sectional area of the the flushing supply portion F_Sf may be at least partially achieved by forming the flushing opening 26 on, for example the second surface portion 36 of the drill bit 6, wherein the first surface portion 34 is radially outer to the second surface portion 36, such that the hole 15 is formed having a diameter at least equal to that of the diameter of the first surface portion 34, and the flushing supply portion F_Sf may be defined in a volume between the second surface portion 36 and the peripheral wall 17 of the hole 15. In at least some examples at least a portion of the flushing supply portion F_Sf may be defined between the second surface portion 36 and a peripheral sleeve (described later with reference to Fig. 5-7). By having the cross- sectional area of the side flushing channel 24 less than both the cross-sectional area of the exhaust channel 20 and the flushing supply path F_Sf, a flow through the side flushing channel 24 may utilise the venturi effect.

In at least some examples the drill bit 6 may be configured such that the fluid supply path F_s comprises an exhaust supply portion F_se, wherein the exhaust supply portion F_se comprises a portion of the fluid supply path F_s configured to supply fluid from the flushing opening 26 to the side exhaust opening 22. In at least some examples the cross-sectional area of the side flushing channel 24 may be less than that of exhaust supply portion F_se, such that the flow of fluid through the side flushing channel 24 may be less than the flow of fluid through the exhaust supply portion F_se when the exhaust channel 20 is unblocked, and when the exhaust channel 20 is blocked the flow of fluid via the exhaust supply path Fse will be restricted and a pressure of fluid at the flushing opening 26 increased, such that the flow through the side flushing channel 24 will be increased.

In the shown example the side flushing channel 24 extends towards the exhaust opening 22. Furthermore, in the shown example the side flushing channel 24 extends from the flushing opening 26 in a flushing direction F. The flushing direction F has at least a component acting parallel to the central axis C, towards the exhaust opening 22, such that a flow of fluid through the side flushing channel 24 into the exhaust channel 20 is directed towards the exhaust opening 22. In at least some examples the flushing direction F is parallel to the central axis C. In at least some examples the flushing direction F has at least a component acting in the radial direction, such that the flushing direction F is inclined with respect to the central axis. In at least some examples the flushing direction F is inclined with respect to the exhaust channel 20.

Fig. 3 illustrates schematically a drill bit 6 according to an embodiment of the disclosure. In the shown example the drill bit 6 differs from that described with reference to Fig. 2 as the drill bit 6 comprises at least one additional side flushing channel 24’ extending from an additional flushing opening 26’, formed in the peripheral surface 16, to the exhaust channel 20. In at least some examples the drill bit 6 may comprise any number of additional side flushing channels. In the shown example the additional flushing opening 26’ is formed in the peripheral surface 16 at a location further from the first end 8 of the drill bit than the flushing opening 26, in a direction parallel to the central axis C. In at least some examples the additional flushing opening 26’ may be formed in the peripheral surface 16 at a location closer to the first end 8 of the drill bit 6 than the flushing opening 26, or at the same distance to the first end 8 of the drill bit, further from the first end 8 of the drill bit than the flushing opening 26, in. In at least some examples the additional flushing opening 26 may be formed in the peripheral surface 16 at a location spaced along a circumference thereof, the circumference extending about the central axis C, relative to the flushing opening 26.

In the shown example the additional side flushing channel 24’ extends from the peripheral surface 16 towards the exhaust opening 22. Furthermore, in the shown example the additional side flushing channel 24’ extends from the peripheral surface 16 in an additional flushing direction F’, the additional flushing direction F’ having at least a component acting parallel to the central axis C, towards the exhaust opening 22. In a least some examples the inclination of the additional flushing direction F’ with respect to the exhaust channel 20 may differ from the inclination of the additional flushing direction F’ with respect to the exhaust channel 2.

In the shown example the cross-sectional area of the additional side flushing channel 24’ is less than the cross-sectional area of the side flushing channel 24. In at least some examples the cross-sectional area of the additional side flushing channel 24’ may be more than the cross-sectional area of the side flushing channel 24, or the same as.

In the shown example the sum of the cross-sectional area of the side flushing channels 24, 24’ is less than the cross-sectional area of the exhaust channel 20.

Furthermore, in at least some examples the drill bit 6 may be configured such that the flushing supply portion F_Sf is configured to supply fluid to the flushing opening 26 and the additional side flushing channel 24’, and wherein the flushing supply portion F_Sf has a cross-sectional area greater than the sum of the cross-sectional area of the side flushing channels 24, 24’. Alternatively, in at least some examples the fluid supply path F_s may comprise separate flushing supply portions F_Sf configured to supply each of the side flushing channels 24, 24’, each configured as described with reference to Fig. 2. exhaust supply portion F_se

In at least some examples the drill bit 6 may be configured such that the exhaust supply portion F_se is configured to supply fluid from the flushing opening 26 and the additional flushing opening 26’. In at least some examples the sum of the cross-sectional areas of the side flushing channels 24, 24’ may be less than that of the exhaust supply portion F_se, such that the flow of fluid through the side flushing channels 24, 24’ will be less than that through the exhaust supply portion F_se when the exhaust channel 20 is unblocked, and the flow through the side flushing channel 24 will be increased when the exhaust channel 20 is blocked. Alternatively, in at least some examples the fluid supply path F_s may comprise separate side flushing channels 24, 24’ configured to supply fluid from each of the side flushing channels 24, 24’ to the mineral substrate 14, each configured as described with reference to Fig. 2.

Furthermore, in the shown example the drill bit 6 differs from that described with reference to Fig. 2 as the drill bit 6 comprises a further exhaust channel 20” extending from the central channel 18 to a further exhaust opening 22”, formed in the drill face 12. In at least some examples the drill bit 6 may comprise any number of further exhaust channels 20”. In the shown example the further exhaust channel 20” is inclined with respect to the central axis C. Furthermore, in the shown example the inclination of the further exhaust channel 20” with respect to the central axis C is equal to the inclination of the exhaust channel 20 with respect to the central axis C. In at least some examples the inclination of the further exhaust channel 20” with respect to the central axis C may differ from the inclination of the exhaust channel 20 with respect to the central axis C.

In the shown example the sum of the cross-sectional areas of the exhaust channels 20, 20” is less than the cross-sectional area of the central channel 18.

In the shown example the further exhaust channel 20” is configured with a further side flushing channel 24”. The further side flushing channel 24” may be configured similar to the flushing channel 24 as described with reference to Fig. 2. In at least some examples the further exhaust channel 20” may further be configured with an additional side flushing channel as described above. Fig. 4 illustrates a perspective view of a drill bit 6 according to an embodiment of the disclosure. The drill bit 6 comprises an exhaust opening 22’ and two further exhaust openings 22” formed in the drill face 12 thereof. In the shown example the three exhaust openings 22, 22” are formed such that they are equally spaced about the central axis C. Furthermore, in the shown example the three exhaust openings 22, 22” are equally spaced from the central axis C in the radial direction R. In at least some examples any number of exhaust openings may be formed in the drill face 12, wherein the exhaust openings may be equally spaced about the central axis or spaced differently thereabout. Furthermore, the exhaust openings may be spaced differently from the central axis C in the radial direction R.

In the shown example the drill bit 6 comprises a plurality of flushing supply recesses 38, wherein the flushing supply recesses 38 are configured to guide fluid at least partially along the flushing supply portion F_Sf of the fluid supply path Fs. In the shown example flushing supply recesses 38 are formed such that they extend from a location further away from the first end 8 of the drill bit 6 than the flushing openings 26 and extend in a direction towards the second end 10 of the drill bit 6, parallel to the central axis C. Furthermore, in the shown example the drill bit 6 comprises a plurality of exhaust supply recesses 39, wherein the exhaust supply recesses 39 are configured to at least partially guide fluid along the exhaust supply portion F_se of the fluid supply path Fs. In the shown example the drill bit 6 comprises a plurality of exhaust supply recesses 39 formed on the drill face 12 extending from each of exhaust openings 22 radially outwards, relative to the central axis C, and extending along the peripheral surface 16, in a direction parallel to the central axis C to a location spaced from the flushing opening 26, such that the flushing opening 26 is further away from the first end 8 of the drill bit 6. In at least some examples any number of flushing supply recesses 38 and or exhaust supply recesses 39 may be formed such that the fluid supply path F_s may be guided to each flushing opening 26 and/or each exhaust opening 22.

Fig. 5 illustrates schematically a drilling apparatus 4 according to an embodiment of the disclosure. Furthermore, Fig. 6 illustrates schematically a drilling apparatus 4 according to an embodiment of the disclosure. Furthermore, Fig. 7 illustrates schematically a drilling apparatus 4 according to an embodiment of the disclosure. Fig. 5 represents a front view, Fig. 6 represents a sectional view, and Fig. 7 represents a close-up sectional view of the drill bit portion of an embodiment of the disclosure. The drilling apparatus 6 may comprise the drill bit as described with reference to Fig. 2-4.

In the shown example the drilling apparatus 4 further comprises a fluid actuation system 26, configured to supply fluid along the peripheral surface 16 of the drill bit 6 towards the drill face 12, and to remove fluid via the central channel 18 away from the drill face 12. In at least some examples the fluid actuation system 26 may comprise a compressor. In at least some examples the fluid actuation system 26 comprises a single fluid actuation device (not shown) configured to both supply fluid to the drill face 12, and to remove fluid from the mineral substrate 14. Alternatively, in at least some examples the fluid actuation system 26 may comprise a plurality of fluid actuation devices, such as a fluid supply device configured to supply fluid to the mineral substrate 14 and a fluid removal device configured to remove fluid from the mineral substrate 14.

In the shown example the drilling apparatus 4 comprises a piston 40 configured to be actuated along the central axis C of the drill bit 6 such that the piston 40 impacts the drill bit 6 and the drill bit 6 breaks the mineral substrate 14. During the drilling operation the drill bit 6 may be actuated along the central axis C such that a hole 15 is formed having an extension coaxial with the central axis C of the drill bit 6. Furthermore, in at least some examples the hole 15 may comprise a peripheral wall 17 extending around the central axis C, and along the central axis C. In at least some examples at a least a portion of the fluid supply path F_s may be defined between the peripheral surface 16 and the peripheral wall 17 of the hole 15.

The drilling apparatus 4 further comprises a casing 42 extending coaxially with said drill bit 6 and configured to surround said piston 40 and at least a portion of the drill bit 6. In at least some examples the casing 42 may at least partially define the fluid supply path F_s. In the shown example at least a portion of the fluid supply path F_s is formed radially inner to the casing 42, relative to the central axis C. In the shown example the drilling apparatus 6 further comprises a chuck 44 configured to guide the movement of the drill bit 6. In at least some examples the chuck 44 may be fixed for movement relative to the casing 42, for example the chuck 44 may be attached to the casing 42. In at least some examples the chuck 44 may at least partially define the fluid supply path F_s. In the shown example at least a portion of the fluid supply path F_s is formed radially outer to the chuck 44 and radially inner to the casing 42, relative to the central axis C. In the shown example the drilling apparatus 4 further comprises a peripheral sleeve 28, configured to surround the central axis C such that at least a portion of the peripheral sleeve 28 surrounds a portion of the peripheral surface 16 of the drill bit 6, and a peripheral channel 30 is formed therebetween. Furthermore, in at least some examples at least a portion of the peripheral channel 30 may be formed between the chuck 44 and the peripheral sleeve 28. In at least some examples the peripheral sleeve 28 may be arranged coaxially with the central axis C The peripheral sleeve 28 may be fixed relative to the chuck 44 and/or the casing 42, for example the peripheral sleeve 28 may be attached to the chuck 44 and/or the casing 42. In the shown example the peripheral channel 30 at least partially defines the fluid supply path F_s. In the shown example at least a portion of the fluid supply path F_s is formed radially outer to the chuck 44 and radially inner to the peripheral sleeve 28, relative to the central axis C. Furthermore, in the shown example the peripheral channel 30 at least partially defines the flushing supply portion F_Sf of the fluid supply path F_s. The peripheral sleeve 28 may comprise any number of protrusions or recesses, for example for fixing the peripheral sleeve to the chuck 42, or for further defining the fluid supply path F_s. In at least some examples the peripheral sleeve 28 may be configured to seal against a peripheral surface of the drilled hole 15, for example to ensure a fluid from the sleeve flows to the mineral substrate 14 and through the exhaust opening 22, and not towards the second end 10 of the drill bit 6 via the peripheral wall 17 of the hole 15. In at least some examples the peripheral channel 30 may be formed such that it surrounds the central axis C of the drill bit 6. Alternatively, in at least some examples the peripheral channel 30 may be formed such that it partially extends about the central axis C of the drill bit 6, such that in at least some examples a plurality of peripheral channels 30 may be formed, for example where the drill bit 6 comprises a plurality of exhaust channels each of the peripheral channels may be formed for one of the exhaust channels, and wherein the plurality of peripheral channels 30 may be configured to surround the central axis C of the drill bit 6.

In the shown example the side flushing channel 24 is configured for fluid communication between the peripheral channel 30 and the exhaust channel 20. In the shown example the peripheral sleeve 28 is configured such that it is arranged radially outer to said flushing opening 26, such that said peripheral sleeve 28 surrounds the flushing opening 26. In the shown example the cross-sectional area of the side flushing channel 24 is less than the cross-sectional area of the peripheral channel 30. In at least some examples, where the peripheral channel 30 is configured to supply more than one side flushing channel 24, the sum of the cross-sectional area of the side flushing channels 24 may be less than the cross-sectional area of the peripheral channel 30. In at least some examples the drilling apparatus 4 may comprise a drill string, comprising one or more drill rods (not shown). In at least some examples additional drill rods may be added to the drill string to increase the depth of a drilling operation. The drill bit 6 may be located at the end of the drill string. The drill bit 6 may be connected to the drill string via the second end 10 thereof. Fluid may be supplied to and/or removed from the drill bit 6 via the drill string. In at least some examples a feed force may be applied to the drill bit 6 via the drill string. Furthermore, in at least some examples a rotation of the drill bit 6 may be achieved by a rotation of the drill string.

Claims

1 . A drill bit (6), configured for reverse circulation down-the-hole drilling, the drill bit (6) comprising a first end (8), a second end (10), and a central axis (C) extending therebetween, wherein the first end (8) comprises a drill face (12), configured to break a mineral substrate (14), the drill bit (6) further comprising: a peripheral surface (16), extending around the central axis (C), between the first end (8) and the second end (10), a central channel (18) extending from the second end towards (10) the first end (8), an exhaust channel (20) extending from the central channel (18) to an exhaust opening (22), formed in the drill face (12), a side flushing channel (24), extending from a flushing opening (26), formed in the peripheral surface (16), to the exhaust channel (20), wherein the side flushing channel (24) extends from the flushing opening (26) in a flushing direction (F), the flushing direction (F) having at least a component acting parallel to the central axis (C), towards the exhaust opening (22), such that a flow of fluid through the side flushing channel (24) into the exhaust channel (20) is directed towards the exhaust opening (22).

2. The drill bit (6) according to claim 1 , wherein the central channel (18) extends along the central axis.

3. The drill bit according (6) to any of the preceding claims, wherein the exhaust channel (20) is inclined with respect to the central axis (C).

4. The drill bit (6) according to any of the preceding claims, comprising at least one additional side flushing channel (24’) extending from an additional flushing opening (26’), formed in the peripheral surface (16), to the exhaust channel (20), the additional side flushing channel (24’) extending from the peripheral surface (16) in an additional flushing direction (F’), the additional flushing direction (F’) having at least a component acting parallel to the central axis (C), towards the exhaust opening (22).

5. The drill bit (6) according to any of the preceding claims, comprising a further exhaust channel (20”) extending from the central channel (18) to a further exhaust opening (22”), formed in the drill face, wherein the further exhaust channel (20”) is configured with a further side flushing channel (24”).

6. The drill bit (6) according to any of the preceding claims, wherein the cross- sectional area of the exhaust channel (20) is less than the cross-sectional area of the central channel (18).

7. The drill bit (6) according to any of the preceding claims, wherein the cross- sectional area of the side flushing channel (24) is less than the cross-sectional area of the exhaust channel (20).

8. A drilling apparatus (4) comprising the drill bit (6) of any of the preceding claims, further comprising a fluid actuation system (26), configured to supply fluid along the peripheral surface (16) of the drill bit (6) towards the drill face (12), and to remove fluid via the central channel (18) away from the drill face (12).

9. The drilling apparatus (4) according to claim 8, further comprising a peripheral sleeve (28), configured to surround the central axis (C) such that at least a portion of the peripheral sleeve (28) surrounds a portion of the peripheral surface (16) of the drill bit (6), and a peripheral channel (30) is formed therebetween.

10. The drilling apparatus (4) according to claim 9, wherein the side flushing channel (24) is configured for fluid communication between the peripheral channel (30) and the exhaust channel (20).

11 . The drilling apparatus (4) according to any of claims 9-10, wherein the cross- sectional area of the side flushing channel (24) is less than the cross-sectional area of the peripheral channel (30).

12. A drill rig (2) comprising the drilling apparatus (4) according to any of claims 8-11 .