阅读说明：本技术 用于冲击钻探的钻头、钻头组件以及用于制造这种钻头的方法 (Drill bit for percussive drilling, drill bit assembly and method for manufacturing such a drill bit ) 是由 帕斯·科特 安蒂·莱诺 于 2018-02-28 设计创作，主要内容包括：提供一种钻头(1),其包括具有圆周(2a)和端面(2b)的头部部分(2),以及从所述头部部分的与所述端面相对的一侧纵向地延伸的柄部部分(3)。中心冲洗通道(4)纵向地延伸通过所述柄部部分(3)并且在所述头部部分(2)内延伸一定的距离,并且侧向冲洗通道(5)从所述中心冲洗通道(4)延伸至所述头部部分(2)的圆周(2a)。所述侧向冲洗通道的第一部分(5a)沿冲洗流体流动方向相对于所述第二部分(5b)朝向所述端面(2b)倾斜,相对应地,第二部分(5b)沿冲洗流体流动方向朝向所述柄部部分(3)倾斜。还公开一种钻头组件以及制造这样的钻头的方法。(A drill bit (1) is provided comprising a head portion (2) having a circumference (2a) and an end face (2b), and a shank portion (3) extending longitudinally from a side of the head portion opposite the end face. A central flushing channel (4) extends longitudinally through the handle portion (3) and extends a distance within the head portion (2), and a lateral flushing channel (5) extends from the central flushing channel (4) to the circumference (2a) of the head portion (2). The first portion (5a) of the lateral flushing channel is inclined towards the end face (2b) in the flushing fluid flow direction with respect to the second portion (5b), correspondingly the second portion (5b) is inclined towards the handle portion (3) in the flushing fluid flow direction. A drill bit assembly and a method of manufacturing such a drill bit are also disclosed.)

1. A drill bit (1) for percussive drilling, comprising:

A head portion (2) having a circumference (2a) and an end face (2b) arranged for receiving a plurality of inserts;

A shank portion (3) extending longitudinally from a side of the head portion opposite the end face, the shank portion being arranged for coupling the drill bit (1) to a drill string in a manner that imparts rotation and impact;

a central flushing channel (4) extending longitudinally through the handle portion (3) and longitudinally a distance within the head portion (2), and

A lateral flushing channel (5) extending from the central flushing channel (4) to a circumference (2a) of the head portion (2), wherein the lateral flushing channel (5) comprises:

A first portion (5a) connecting the lateral flushing channel to the central flushing channel (4), and

Connecting the lateral flushing channel to a second portion (5b) of the circumference (2a) of the head portion (2),

Wherein the first portion (5a) is inclined in the flushing fluid flow direction with respect to the second portion (5b) towards the end face (2b), correspondingly the second portion (5b) is inclined in the flushing fluid flow direction with respect to the first portion (5a) towards the handle portion (3),

Wherein the drill bit (1) comprises a plurality of lateral flushing channels (5) angularly separated from each other, and

In correspondence of each lateral flushing channel (5), the drill bit further comprises at least two end face flushing channels (6), the at least two end face flushing channels (6) preferably extending between the central flushing channel (4) and the end face (2b) via the lateral flushing channels (5),

characterized in that said at least two end face flushing channels (6) corresponding to respective lateral flushing channels (5) are positioned on said end face (2b) within a sector corresponding to said respective lateral flushing channel, said sector being delimited by one or more adjacent sectors corresponding to other lateral flushing channels (5).

2. A drill bit (1) for percussive drilling, characterized by:

The first portion (5a) is oriented towards the end face (2b) between a direction transverse to the central flushing channel (4) and a direction parallel to the central flushing channel (4), and

The second portion (5b) is oriented towards the handle portion (3).

3. Drill bit (1) according to claim 2, characterized in that the first portion (5a) is oriented in a direction transverse to the central flushing channel (4).

4. drill bit (1) according to claim 2, characterized in that the first portion (5a) is oriented towards the end face (2 b).

5. Drill bit (1) according to any of the preceding claims, characterized in that it further comprises a deflecting element (6a) arranged at the end face (2b) end of the end face flushing channel (6) for deflecting the flushing fluid flow before being introduced at the end face (2 b).

6. Drill bit (1) according to any one of the preceding claims, characterized in that the at least two end face flushing channels (6) corresponding to respective lateral flushing channels (5) are spaced apart from each other, preferably at least radially, on the end face (2b) in a direction transverse to the central flushing channel (4).

7. Drill bit (1) according to any one of the preceding claims, characterized in that it comprises, for each lateral flushing channel (5), on the circumference (2a) of the head portion (2) a flushing channel (7) extending longitudinally through the head portion (2), wherein the respective lateral flushing channel (5) extends between the central flushing channel (4) and the flushing channel (7).

8. Drill bit according to any of the preceding claims, characterized in that the drill bit (1) comprises a separate part (9) of the head part (2) attached to the drill bit, wherein the separate part (9) comprises at least a part of the lateral flushing channel (5), preferably at least a part of the second part (5b) of the lateral flushing channel (5).

9. Drill bit (1) according to any of the preceding claims, characterized in that the drill bit is a pilot bit (1), further comprising pilot bit coupling means (8) arranged on the circumference (2a) of the head portion (2) for coupling the drill bit with a ring bit in a manner that transmits impacts and rotation.

10. A drill bit assembly, characterized in that it comprises a drill bit (1) according to claim 9, the drill bit assembly further comprising a ring bit equipped with ring bit coupling means operatively corresponding to the pilot bit coupling means (8),

Wherein, in coupled condition, the inner circumference of the ring bit and the flushing groove (7) form a return route for flushing fluid from the lateral flushing channel (5) and preferably the face flushing channel (6).

11. A method for manufacturing a drill bit (1) according to any one of claims 1-9, characterized in that at least a part of the head portion (2) is manufactured by adding material in order to form at least a part of a lateral flushing channel (5).

Technical Field

The present invention relates to drill bits for percussive drilling, and more particularly to drill bits in which flushing fluid is directed via lateral flushing fluid channels. The disclosure further relates to a drill bit assembly having such a drill bit and a method for manufacturing such a drill bit assembly.

Background

Flushing fluid is typically used to flush cuttings from the borehole ahead of the drill bit. This enables the drill bit to effectively act on the formation to be drilled rather than on the excess cuttings present in the borehole.

it has been recognized that the use of flushing fluids can cause problems when drilling in sensitive formation conditions. In soft formations, the flushing fluid may remove excess formation around the drill bit, which is known as over drilling. This is particularly problematic when drilling a pile into the formation, because a bore that is too large cannot support the pile in the desired manner, so that the pile is less able to support the structure on top of it. Another problem associated with the use of flushing in sensitive formation conditions is that the flushing fluid may travel long distances along certain formations, such as viscous formations. Thus, in densely built areas, the flushing fluid may accidentally travel to existing piles or foundations and weaken their structure. Therefore, minimizing the effects of flushing fluids while drilling is a common concern.

Disclosure of Invention

It is an object of the present disclosure to provide a drill bit and a drill bit assembly with which the problems associated with drilling in sensitive formation conditions may be overcome or effectively alleviated. It is another object of the present disclosure to provide a method of manufacturing such a drill bit.

the object of the invention is achieved by a drill bit, a drill bit assembly and a method for manufacturing a drill bit, which are characterized by what is stated in the independent claims. Preferred embodiments of the present disclosure are disclosed in the dependent claims.

The invention is based on the following idea: providing a lateral flushing channel extending from a central flushing channel of the bit head portion to the circumference of the bit head portion such that flushing fluid exiting the channel may be directed to increase the pressure differential between the surrounding environment of the circumference of the head portion and the end face while enabling the lateral flushing channel to be formed so as to minimize the deflection required for flushing fluid to flow from the central flushing channel to the lateral flushing channel.

An advantage of the present invention is that the ability of the corresponding flushing fluid flow to transport drill cuttings is increased by providing a smooth direction transition facilitating the flushing fluid flow via the lateral flushing channel, i.e. a smooth overall profile resulting in less flow resistance and thus less pressure loss. This advantage is particularly pronounced when drilling deep boreholes that require relatively high flushing fluid flow rates and/or velocities to carry the cuttings to the surface. As the increased flow rate through the lateral flushing fluid passage increases, the pressure differential between the circumference of the head portion and the surface also increases, thereby drawing cuttings from the circumference of the end face along with the flushing fluid flow from the lateral flushing fluid passage. The effect of such a pressure difference is very similar to the vacuum effect, sucking the chips in front of the end face of the head portion. Thus, as a synergistic effect, the flow of flushing fluid through the bit face may be reduced, thereby reducing the risks associated with drilling in sensitive formation conditions. Moreover, providing lateral flushing channels according to the present disclosure enables the flushing fluid flow to be directed towards the shank portion (i.e. the surface), even in combination with a drill bit having a relatively large diameter relative to the height of the drill bit.

drawings

The present disclosure will be described in more detail hereinafter by means of preferred embodiments with reference to the accompanying drawings, in which:

Fig. 1 to 4 show several embodiments of a drill bit according to the invention, which are shown in cross-section, an

Fig. 5 and 6 show two views of the embodiment in fig. 4.

It should be noted that for the sake of clarity, the drawings are simplified illustrations of various embodiments of the disclosure. Accordingly, the drawings should not be construed as limiting the scope of the disclosure.

Detailed Description

fig. 1 shows a cross-sectional view of a drill bit 1, the drill bit 1 comprising a head portion 2 having a circumference 2a and an end face 2 b. Further, the shank portion 3 extends longitudinally from the head portion 2 in a direction opposite to the end face 2 b. The central flushing channel 4 extends longitudinally through the handle portion 3 and longitudinally a distance within the head portion 2. The lateral flushing channel 5 extends from the central flushing channel 4 up to the circumference 2a of the head portion 2. The first part 5a of the lateral flushing channel extends in a direction transverse to the central flushing channel 4, while the second part 5b of the lateral flushing channel 5 is inclined towards the handle portion 3 in the flow direction of the flushing fluid with respect to the first part 5a of the lateral flushing channel 5. A smooth transition is provided between the first and second portions 5a, 5 b. The drill bit 1 is further equipped with a face flushing channel 6, which extends partly between the central flushing channel 4 and the face 2b via the lateral flushing channels 5. On the circumference 2a of the head portion, flushing grooves 7 are arranged which extend longitudinally through the circumference. Furthermore, the lateral flushing channel (i.e. the second portion 5b thereof) is arranged to extend up to the lateral flushing groove 7. Pilot bit coupling means 8 are also provided on the circumference 2a of the head portion 2 for coupling the drill bit 1 with a corresponding ring bit in a manner to transmit impacts and rotations.

fig. 2 shows a drill bit 1, which drill bit 1 is similar to the drill bit 1 of fig. 1, except that there is no face flushing fluid channel and an alternative structure of lateral flushing channels 5 is provided. In particular, a first portion 5a of the lateral flushing channel 5 is inclined towards the end face 2b in the flow direction of the flushing fluid, whereas a second portion 5b is inclined towards the shank portion 3.

Likewise, in fig. 3, the first portion 5a of the lateral flushing channel 5 is inclined towards the end face 2b in the flow direction of the flushing fluid, while the second portion 5b is inclined towards the shank portion 3. However, unlike the drill bit 1 of fig. 2, a face flushing channel 6 is provided which extends directly between the face 2b and the central flushing channel 4. On the end face 2b, the end face flushing channel 6 is equipped with a deflecting element 6a, which deflects the flushing fluid flow originating from the end face flushing channel 6 towards the periphery of the end face 2 b.

Fig. 4 shows a cross-sectional view of an embodiment similar to the embodiment shown in fig. 3, except without the deflecting element and with a portion of the head portion 2 being provided as a separate part 9 attached to the rest of the drill bit 1. In particular, a part of the second portion 5b of the lateral flushing channel 5 and a transition area between the first portion 5a and the second portion 5b are arranged on the separate portion 9.

Fig. 5 shows the drill bit of fig. 4 as a side view. In particular, it shows a tongue and groove arrangement between the separate portion 9 and the head portion 2.

Fig. 6 shows a perspective view of the drill bit of fig. 4. In particular, it shows how the separate portions 9 are positioned within the respective flushing grooves 7 and extend radially therefrom. Also, the second portion 5b is partially formed in the separate portion 9.

according to a first aspect of the present disclosure, a drill bit 1 for percussive drilling is provided.

the drill bit 1 comprises a head portion 2 having a circumference 2a and an end face 2b arranged for receiving a plurality of inserts for cutting rock. Furthermore, when in use, the end face is arranged for drilling a formation, i.e. crushing formation material into cuttings. The drill bit 1 further comprises a shank portion 3 extending longitudinally from a side of the head portion 2 opposite the end face 2 b. The shank portion 3 is arranged for coupling the drill bit 1 to a drill string in a manner that transmits rotation and impact. Preferably, but not necessarily, the handle section may be coupled to, for example, a hammer or a drill rod.

The central flushing channel 4 extends longitudinally through the handle portion 3 and a distance within the head portion 2. In the context of the present disclosure, the longitudinal axis of the drill bit 1 is considered to extend in the direction of extension of the shank portion 3. Furthermore, the lateral flushing channels 5 extend from the central flushing channel 4 to the circumference 2a of the head portion 2. It should be noted that the lateral flushing channel 5 itself need not be vertically lateral, i.e. need not be a straight channel extending vertically in a lateral direction, but may be curved and/or inclined in one or more directions.

The central flushing channel 4 is arranged to direct flushing fluid from the surface along the drill string to the drill bit and further away from the drill bit via at least the lateral flushing channels 5. The purpose of the flushing fluid is to flush the cuttings away from the bottom of the borehole and to transport the cuttings within the borehole, preferably within the casing, to the surface. That is, the cuttings are carried away from the front of the end face 2b by the flushing fluid. Flushing the cuttings may be further enhanced by providing an end face flushing channel 6, as discussed in detail later.

The lateral flushing channel 5 comprises a first portion 5a connecting said lateral flushing channel to the central flushing channel 4 and a second portion 5b connecting said lateral flushing channel to the circumference 2a of the head portion 2. In particular, the first portion 5a is inclined towards the end face 2b with respect to the second portion 5b in the flushing fluid flow direction. Correspondingly, the second portion 5b is inclined in the flushing fluid flow direction with respect to the first portion 5a towards the handle portion 3. Suitably, the second portion 5b of the lateral flushing channel 5 directs the flushing fluid flow towards the surface, i.e. is inclined towards the shank portion in the flushing fluid flow direction. This ensures that the flushing fluid flow originating from the lateral flushing channel 5 flows towards the surface with minimal flow disturbances and flow turbulence. For example, the loss of kinetic energy of the flow is particularly small upon collision with the inner periphery of the ring bit.

It should be noted that the first portion 5a and the second portion 5b do not necessarily need to be inclined in an absolute manner towards the end face 2b and the shank portion 3, respectively, but that above refers to a mutually corresponding inclination of the first and second portions 5a, 5b of the lateral flushing channel 5. Furthermore, in the context of the present disclosure, the term "inclined" is used to describe the general orientation of the first and second portions 5a, 5b of the lateral flushing channel 5. Correspondingly, the present disclosure encompasses such an arrangement: in this arrangement, the lateral flushing channel is for example curved. Moreover, the present disclosure encompasses such arrangements: in this arrangement, both the first and second portions 5a, 5b are oriented towards the handle portion in the flushing fluid flow direction, while the first portion 5a is inclined towards the end face 2b relative to the second portion 5b and the second portion 5b is inclined towards the handle portion 3 relative to the first portion 5 a.

Such an arrangement ensures that the direction of the flushing fluid from the surface and directed back to the surface can be gradually redirected. That is, in order to let the flushing fluid enter the lateral flushing channel 5, it is not necessary to deflect the flushing fluid to the desired direction out of the lateral flushing channel 5 (i.e. the direction of the second portion 5b), but instead it is sufficient to deflect the flushing fluid less (to the direction of the first portion 5 a). This in turn makes the flow path smoother and, therefore, less resistant to the flow of flushing fluid than conventional arrangements which provide lateral flushing channels as straight rearwardly inclined conduits drilled from the circumference 2a to the central flushing channel. As a result of the smaller flow resistance achieved, a greater flushing fluid flow is obtained at a given feed pressure, which translates into a higher flushing capacity for the drill cuttings.

Furthermore, it has been found that providing a flow of flushing fluid from the circumference 2a of the head portion towards the handle portion 3 (i.e. away from the end face 2b) will create a pressure difference between the surroundings of the circumference 2a and the surroundings of the end face 2b, so that cuttings drifting about the circumference 2a will be sucked to the surface together with the flow of flushing fluid from the lateral flushing channel 5. This enables the drill cuttings to be flushed from the bottom of the borehole to the surface while directing little or no flushing fluid to the end face 2 b. The risk associated with sensitive formation conditions (i.e., over drilling and/or damage to existing formation structures due to the flushing fluid traveling within the formation) is minimized, particularly when the flushing fluid returning to the surface flows within the casing. The drill bit 1 according to the invention enables a further reduction of the risks associated with sensitive formation conditions, since a larger flushing fluid flow and/or a larger proportion of the flushing fluid flow may be introduced at a given feed pressure via the lateral flushing channels 5.

Moreover, to further enhance these benefits, the lateral flushing channel 5 may comprise one or more intermediate portions between the first portion 5a and the second portion 5 b. In addition, the first portion 5a, the second portion 5b and any possible intermediate portions may be provided with a smooth transition therebetween.

According to one embodiment of the first aspect of the present disclosure, the first portion 5a is oriented towards the end face 2b between a direction transverse to the central flushing channel 4 and a direction parallel to the central flushing channel 4. That is, the first portion 5a is oriented in any of these directions or any direction therebetween. Since the first portion 5a of the lateral flushing channel does not extend towards the handle portion 3, the flushing fluid does not need to be deflected back towards the direction from which it came in order to enter the lateral flushing channel 5. This further reduces the flow resistance of the flushing fluid flowing to the lateral flushing channel 5. Furthermore, the second portion 5b is oriented towards the handle portion 3, which helps to generate a pressure difference between the end face 2b and the circumference 2a and increases the cuttings to be sucked from around the end face 2 b.

according to another embodiment of the first aspect of the present disclosure, the drill bit 1 comprises a face flushing channel 6 extending between the central flushing channel 4 and the face 2 b. Preferably, the end face flush channel 6 extends between the central flush channel 4 and the end face 2b via the lateral flush channels 5, but the end face flush channel 6 may alternatively be arranged to extend directly between the central flush channel and the end face 2 b. Furthermore, the drill bit 1 may comprise a deflection element 6a arranged at the end of the end face 2b of the end face flushing channel 6 for deflecting the flushing fluid flow before it is introduced at the end face 2 b. Such a deflecting element 6a redirects the flushing fluid flowing from the end face flushing channel 6 beyond the periphery of the end face 2b, i.e. towards the circumference 2a of the head portion 2. This arrangement causes the flushing fluid flow from the end face flushing channel 6 to blow cuttings towards the surroundings of the circumference 2a, from where the flushing fluid flow from the lateral flushing channels 5 will carry the cuttings to the surface. Moreover, since the deflecting element 6a directs the associated flushing fluid towards the circumference 2a, a smaller flow rate of flushing fluid through the end face flushing channel 6 is required and, thus, the risks associated with sensitive formation conditions are further minimized.

According to another embodiment of the first aspect of the present disclosure, for each lateral flushing channel 5, the drill bit 1 comprises at least two end face flushing channels 6, which preferably extend between the central flushing channel 4 and the end face 2b via said lateral flushing channel 5. As a result, the flow of flush fluid to the end face 2b is more evenly distributed thereon, and the velocity of the flush fluid introduced to the end face 2b can be reduced while maintaining a similar flow rate. Reducing the flow velocity further helps to minimize the risks associated with sensitive formation conditions, as high flow velocities lead to over drilling in soft formations.

Advantageously, the at least two end face flushing channels 6 corresponding to the respective lateral flushing channels 5 are spaced apart from each other on the end face 2b in a direction transverse to the central flushing channel 4. Preferably, but not necessarily, the at least two end face flushing channels 6 are at least radially spaced from each other.

According to another embodiment of the first aspect of the invention, the drill bit 1 may comprise a plurality of lateral flushing channels 5 most suitably angularly separated from each other, as discussed in connection with any of the previous embodiments. Such an arrangement ensures that the pressure difference between the end face 2b and the circumference 2a, and the fluid flow from the lateral flushing channels 5, is distributed more evenly over the circumference of the head portion 2 of the drill bit 1.

In a further embodiment of the first aspect of the invention, at least two end face flush channels 6 corresponding to respective lateral flush channels 5 are positioned on the end face 2b within the sector (sector) corresponding to said respective lateral flush channel 5. Such sectors are defined by one or more adjacent sectors corresponding to other lateral flushing channels. Moreover, such sectors need not be separate portions on the end face 2b, but may be formed as portions of a common end face 2 b. In other words, the at least two end face flushing channels 6 corresponding to the respective lateral flushing channel 5 need not be positioned on the projection of the associated lateral flushing channel 5 on the end face 2b, i.e. directly below the lateral flushing channel 5, but may be at a distance therefrom.

According to a further embodiment of the first aspect, the drill bit 1 comprises, for each lateral flushing channel 5, a flushing groove 7 on the circumference 2a of the head portion 2. The flushing channel 7 extends longitudinally through the head portion 2, i.e. from the periphery of the end face 2b towards the shank portion 3, so that drill cuttings can be flushed from in front of the end face 2b to the surface through the drill bit 1. Furthermore, respective lateral flushing channels 5 extend between the central flushing channel 4 and the flushing channel 7. This ensures that the pressure difference created by the flushing fluid flow from the lateral flushing channel 5 sucks in the cuttings along the flushing groove 7 from in front of the end face 2b, which are carried further to the surface by the flow.

According to another embodiment of the first aspect, the drill bit is a pilot drill bit 1. Thus, the drill further comprises a pilot bit coupling means 8 arranged on the circumference 2a of the head portion 2. The pilot bit coupling means 8 is arranged for coupling the drill bit with the ring bit in a manner that transmits impacts and rotation.

According to yet another embodiment of the first aspect, the drill bit 1 comprises a separate part 9 of the head part 2 attached to the drill bit. Such a separate portion 9 comprises at least a part of the lateral flushing channel 5, preferably at least a part of the second portion 5b of the lateral flushing channel 5. This arrangement enables the remainder of the drill bit to be produced using conventional machining tools while still achieving the lateral flushing channel 5 according to the present disclosure. Suitably, the separate part 9 as well as the remaining part of the drill bit 1 are provided with mutually corresponding tongue and groove arrangements for securing the separate part 9 to the drill bit by simply inserting the separate part 9 into the corresponding groove on the drill bit 1. After insertion, the separated portions may be further secured by further securing means (e.g., by welding). Preferably, the separate portion 9 is arranged to the flushing channel 7 of the drill bit 1 so as to extend radially therefrom. This provides the additional advantage that the return path formed by the flushing groove 7 and, where appropriate, the inner circumference of the ring bit is divided into smaller flow areas by the separation section 9. Furthermore, this prevents oversized cuttings from entering the washtrough 7 and possibly blocking subsequent flow paths to the surface. Of course, more than one separate portion 9 may be provided, i.e. at least one or each lateral flushing channel 5 may be at least partially formed by a separate portion 9 attached to the drill bit 1.

it should be noted that any of the embodiments of the first aspect may be combined to obtain a drill bit having desired characteristics without departing from the scope of the present disclosure.

According to a second aspect of the present disclosure, a drill bit assembly is provided. Such a drill bit assembly comprises a ring bit, in addition to the drill bit 1 according to any of the embodiments discussed in connection with the first aspect. The ring bit is equipped with ring bit coupling means operatively corresponding to the pilot bit coupling means 8. In the coupled condition, the inner circumference of the ring bit and the flushing grooves 7 of the pilot bit 1 form a return path for flushing fluid from the lateral flushing channel 5 and preferably the face flushing channel 6.

According to a third aspect of the present disclosure, a method for manufacturing a drill bit 1 as discussed in connection with any of the embodiments according to the first aspect is provided. In the method, at least a part of the head portion is produced by adding material so as to form at least a part of the lateral flushing channel 5.

according to an embodiment of the third aspect, at least a part of the head portion is produced by additive manufacturing (additive manufacturing). Examples of such suitable additive manufacturing production methods include powder bed systems as well as powder feed systems. Preferably, but not necessarily, at least the shank portion 3, and suitably the portion of the head portion 2 immediately adjacent the shank portion 3, are prefabricated using conventional production methods, such as machining. Thereafter, at least a part of the head portion (including at least a part of the lateral flushing channel 5), suitably the rest of the drill bit 1, is produced by additive manufacturing. Alternatively, the entire drill bit 1 may be produced using additive manufacturing.

According to another embodiment of the third aspect, the drill bit is produced such that at least one lateral flushing channel is formed by providing a first opening extending between the central flushing channel 4 and the circumference 2a of the head portion 2, such that a part of the first opening corresponds to a first part 5a of the lateral flushing channel 5. Furthermore, a second opening is provided extending between the first opening and the circumference 2a of the head portion 2, such that the second opening corresponds to the second portion 5b of the lateral flushing channel 5. Thereafter, the parts of the first opening which do not correspond to the first portions 5a of the lateral flushing channels 5 are filled, for example by welding.

according to another embodiment of the third aspect, at least a part of the head portion 2 is produced separately from the rest of the drill bit as a separate part 9 and subsequently attached to the rest of the drill bit. Preferably, the portion 9 of the head portion 2 (which comprises at least a part of the lateral flushing channel 5, more preferably at least a part of the second portion 5b of the lateral flushing channel 5) is made as a separate part from the rest of the drill bit 1. For example, the rest of the drill bit 1 and such a separate portion 9 may be arranged to have a mating form such that the separate portion 9 may be received by the drill bit 1 simply by inserting the separate portion into the drill bit 1. After insertion, such separate parts are preferably fixed to the drill bit 1 using conventional means (such as various fastening elements) or by welding. Preferably, but not necessarily, such a separate portion 9 is arranged on the drill bit so as to extend radially from the respective flushing groove 7, effectively dividing the flow area of the flushing groove into two smaller areas. This prevents oversized cuttings from entering the flushing channel and possibly blocking the return path of the flushing fluid to the surface.

Of course, if the drill bit 1 to be produced comprises more than one lateral flushing channel 5, a plurality of such portions may be produced separately and subsequently attached to the rest of the drill bit 1.

It should be noted that the drill bit 1 according to any of the embodiments discussed in connection with the first aspect of the invention may alternatively be produced using conventional manufacturing processes, such as moulding.