TREPAN SUITABLE FOR PERCUSSION

Abstract

The present invention relates to a drill bit (10) comprising: - a body (12), with a central longitudinal axis (AX) and longitudinally delimited by an end rim (14), intended to be rotated about the longitudinal axis to penetrate longitudinally from the end rim through a block in a penetration direction (T1); - a series of teeth (18) carried by the body and projecting from the end rim (14) in the penetration direction to contact the block, these teeth being spaced apart along the circumference of the end rim; wherein recesses (20) are formed in the body and spaced apart along the circumference of the end rim, each recess extending from the end rim; and wherein each tooth (18) is arranged circumferentially from each recess (20). Figure 2a

Description

Title of the invention: PERCUSSION-ADAPTED TREPAN TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of material removal tools, and more particularly to a drill bit specifically adapted for drilling hard material by rotation-percussion. TECHNICAL BACKGROUND

[0002] A hole saw, also known as a core drill, is a type of masonry tool used to make a large diameter circular hole compared to a drill bit.

[0003] Such a tool, denoted 1 in [Fig. 1], conventionally comprises an annular body 2 and teeth 3 mounted at a first end 4 of this body. The body 2 is mounted on a machine by means of a tool holder, at a second opposite end 5, which drives it in rotation about its axis of revolution. During the rotation, the teeth 3 are pressed against a block of material, such as a partition, so as to abrade it. The drill bit 1 progresses in the wall, forming an increasingly deep circular groove until it passes through it. Once the drilling operation is complete and the tool is removed, the wall has a cylindrical opening, the negative of which, called the "core," is housed in the body 2 of the drill bit 1. This core can then be removed.

[0004] When drilling a block made of a hard material such as stone or concrete, it is generally recommended to mount the drill bit on a hammer drill or rotary hammer. Such machines allow a chiseling / percussion component to be added to the rotation, namely a back-and-forth movement of the drill bit 1 relative to the wall in the form of vibrations. Coupled with the effect of rotation, the percussion generates multiple energetic impacts against the wall, which pulverizes the material and thus increases the penetration potential of the tool compared to pure rotation.

[0005] In the case of such use in rotation-percussion, the drill bit 1 is subjected to more severe stresses than in the case of pure rotation, in particular in pressure and fatigue due to repeated shocks.

[0006] In order to guarantee the longevity of the drill bit 1, manufacturers have mostly opted to ensure circumferential material continuity at the first end 4, which prevents the appearance of local deformations, which in the most critical case can lead to tooth loosening.

[0007] This design, while effective in ensuring good drill bit integrity, suffers from problems with the accumulation of dust and fragments resulting from abrasion. This accumulation of dust and fragments makes the impact energy transferred to the wall suboptimal, in addition to generating risks of tool jamming and increased wear of the body and teeth due to friction.

[0008] The invention aims to provide a suitable drill bit architecture for percussion work, allowing at least some of the disadvantages identified above to be avoided. Description of the invention

[0009] To this end, the invention relates to a drill bit adapted for rotary-percussion work, comprising: - a hollow cylindrical body with a central axis of longitudinal orientation, of a thickness defined between an inner surface and an outer surface of the body, the body being delimited longitudinally by an end rim, this body being intended to be driven in rotation around the longitudinal axis to penetrate longitudinally from the end rim through a block in the direction of penetration; - a series of teeth carried by the body projecting longitudinally from the end edge in the direction of penetration to come into contact with the block, these teeth being spaced apart along the circumference of the end edge; in which at least one recess is formed through all or part of the thickness of the body extending from the end edge; and in which each tooth is arranged circumferentially away from said at least one recess.

[0010] The invention also relates to a drill bit as defined, comprising a series of recesses arranged at intervals along the circumference of the end rim, and in which the teeth and the recesses are arranged alternately along the circumference of the body.

[0011] The invention also relates to a drill bit thus defined, in which said at least one recess is formed at iso-distance from the directly adjacent teeth in the circumferential direction.

[0012] The invention also relates to a drill bit thus defined, intended to be driven in a predefined direction of rotation around the longitudinal axis, and in which each said at least one recess is formed closer to the adjacent tooth in the opposite direction to the predefined direction of rotation than it is to the other adjacent tooth in the predefined direction of rotation.

[0013] The invention also relates to a drill bit thus defined, intended to be driven in a predefined direction of rotation around the longitudinal axis, and in which said at least one recess is formed closer to the adjacent tooth in the predefined direction of rotation than it is to the other adjacent tooth in the opposite direction to the predefined direction of rotation.

[0014] The invention also relates to a drill bit thus defined, in which said at least one recess is formed radially to the central axis in the wall thickness of the body.

[0015] The invention also relates to a drill bit thus defined, intended to be driven in a predefined direction of rotation around the longitudinal axis, and in which said at least one recess is formed at an angle α with respect to the radial direction so as to extend from the inner surface to the outer surface in the opposite direction to the predefined direction of rotation.

[0016] The invention also relates to a drill bit as defined, in which said at least one recess is a notch which goes through the thickness of the body.

[0017] The invention also relates to a drill bit as defined above, in which said at least one notch is extended in the opposite direction to the direction of penetration by a groove formed from the outer surface of the body

[0018] The invention also relates to a drill bit thus defined, in which at least one groove which extends a notch communicates with a helical groove formed in the outer face of the body.

[0019] The invention also relates to a drill bit thus defined, in which said at least one recess extends parallel to the central axis from the end edge.

[0020] The invention also relates to a drill bit thus defined, in which said at least one recess extends from the end edge along a longitudinal component in the opposite direction of penetration and a circumferential component in the opposite direction to the predefined direction of rotation. Brief description of the drawings

[0021] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which: - [Fig.l] is a perspective view of an example of the realization of a trepan according to the state of the art; - [Fig.2a] is a perspective view of a drill bit according to the invention comprising dust evacuation recesses in accordance with a first embodiment; - [Fig.2b] is a detailed view of [Fig.2a]; - [Fig.2c] is a projected view that illustrates the dynamics of dust evacuation during a rotary-percussion drilling operation with the drill bit from [Fig.2a]; - [Fig.2d] is a longitudinal view that illustrates the evacuation dynamics of dust and fragments generated during a rotation-percussion drilling operation with the drill bit of [Fig.2a]; - [Fig.3] is a perspective view of a drill bit according to a variant of the first embodiment; - [Fig.4] is a perspective view of a drill bit according to another variant of the first embodiment; - [Fig.5] is a perspective view of a drill bit according to another variant of the first embodiment; - [Fig.6] is a perspective view of a drill bit according to another variant of the first embodiment; - [Fig.7a] is a perspective view of a drill bit according to the invention comprising dust evacuation recesses according to a second embodiment; - [Fig.7b] is a detailed view of [Fig.7a]; - [Fig.7c] is a side view of the drill bit as shown in [Fig.7a]; - [Fig.7d] is a longitudinal view that illustrates the dynamics of dust and fragment evacuation during a rotation-percussion drilling operation with the drill bit of [Fig.7a]. DETAILED DESCRIPTION OF THE INVENTION

[0022] For the purpose of describing the invention and understanding the claims, a drill bit frame of reference defined by longitudinal, radial, and circumferential orientations according to the coordinate system AX, AY, AZ shown in the figures will be adopted, without limitation. The radial direction, defined by the axis AY, is at every point a direction orthogonal to the axis AX and passing through it, and the circumferential direction AZ is defined as rotating at an iso-distance around the axis AX. Specifically, an element is said to be radially "external" or "outer" with respect to another if it is farther from the axis AX than the other, and conversely, an element is said to be radially "inner" or "inner" if it is closer to the axis AX than the other.

[0023] In the description that follows, identical, similar or analogous elements will be designated by the same reference numerals.

[0024] With reference to Figures 2a to 7d, a drill bit 10 according to the invention comprises an annular drill bit body 12, namely cylindrical and hollow, extending along a central axis AX with longitudinal orientation. This body 12 is defined in thickness Ep between an outer surface 12e with a circular contour, of radius Re, and an inner surface 12i also with a circular contour, of radius Ri. The inner surface 12i delimits a cylindrical internal enclosure of body 12, noted I, separated from an external space E to the drill body.

[0025] The body 12 is bounded longitudinally by an end border or edge4, and a connecting end 16.

[0026] The connecting end 16 is shaped to be attached to a drill bit holder rod of a rotating machine, while the end rim 14 is designed to be positioned opposite a block B to be drilled. As can be understood, the end rim 14 corresponds to the end of the body 12 from which the drill bit is driven into the block B during drilling. In practice, the machine on which the drill bit 10 is mounted is oriented so that the central axis AX extends orthogonally to the surface S of the block B to be drilled.

[0027] To ensure the drilling of block B under the effect of the rotation imposed by the rotating machine, the drill bit 10 further comprises teeth 18, advantageously formed from tungsten carbide. These teeth 18 are supported by the body 12 and are distributed along the circumferential direction AZ. In practice, the teeth are shaped with a cutting face that determines the direction of rotation of the drill bit 10. In the context of the invention, this predefined direction of rotation is denoted RL

[0028] In more detail, longitudinal notches are formed in the thickness Ep of the drill body 12, from the end edge 14. The teeth 18 are inserted by complementary shape each in a notch and then crimped by brazing to the body 12 to ensure their retention.

[0029] The teeth 18 and the corresponding notches are shaped so that the head of the teeth, including their cutting face, protrudes from the end edge 14 in a direction Tl of penetration of the drill bit 10 along the longitudinal direction. As understood, the teeth 18 are arranged in a longitudinal projection from the end edge 14 in the direction of penetration Tl to come into contact with the surface S of the block B to be drilled. With this arrangement, it is intended that the teeth 18 constitute the only abrasion interfaces between the drill bit and the block during drilling.

[0030] The idea behind the invention is to provide a drill bit 10 specifically adapted for use in rotary-percussion drilling, namely subjected both to rotation in the circumferential direction AZ and to an oscillatory reciprocating motion resulting from the application of impacts along the longitudinal axis AX. The aim is thus to provide a drill bit 10 specifically adapted for use with a hammer drill or impact drill, particularly for drilling hard materials such as stone or concrete.

[0031] In practice, working in rotation-percussion mode puts more mechanical stress on the drill bit 10 than in the case of pure rotation of the tool. Also, since the percussion fragments the wall material, this results in a greater generation of fragments, splinters and dust that could impair the penetration potential of the drill bit by accumulating under the teeth 18.

[0032] The invention aims to satisfy the dual condition of providing the drill bit 10 with: - satisfactory mechanical strength to withstand repeated impacts from percussion; and - a drainage of the fragments out of the working area, i.e. at the interface between the end edge 14 and the surface S of the block B to be drilled.

[0033] In this respect, the major feature of the invention lies in the formation of material recesses in the body 12 of the drill bit 10, these recesses each being arranged at a distance from the teeth 18 along the circumferential direction.

[0034] With reference to figures 2a to 2c, the body 12 of the drill bit 10 according to a first embodiment is provided with recesses in the form of notches 20. The notches 20 correspond to recesses passing through the entire thickness Ep of the body 12, namely from the outer surface 12e until opening into the internal space I defined by the inner surface 12i of the body 12. These notches 20 can be formed by machining in a raw material of the body, or formed directly by molding the body.

[0035] In this first embodiment, the notches 20 are formed in the radial direction AY, that is, each is formed orthogonally to the local tangent to the circular cross-section body 12. Furthermore, each of these notches 20 has a longitudinal end open to the outside at the end edge 14. In other words, these notches 20 correspond to a material withdrawal through the entire thickness Ep from the end edge 14.

[0036] Each notch 20 is thus delimited by two lateral facets 20a, which are oriented opposite each other in the circumferential direction AZ, and a bottom facet 20b which connects the two lateral facets 20a. The bottom facet 20b corresponds to the extremum point of the notch in the direction opposite to the penetration direction TL

[0037] Also, the notches 20 are identical and each lies in a respective radial plane. In other words, the notches extend parallel to the central axis AX, their bottom facet 20b being longitudinally aligned with their open longitudinal end at the end edge 14.

[0038] Preferably, the teeth 18 and the notches 20 are arranged alternately along the circumferential direction AZ as illustrated in this example. With this arrangement, each tooth 18 is located at a portion of the body 12 bounded between two consecutive notches 20. In particular, in the example of Figures 2a to 2d, each notch 20 extends at an equal distance from the directly adjacent teeth 18 in the circumferential direction.

[0039] In principle, during a drilling operation of block B by the drill bit 10, the material fragments under the effect of the percussion on either side of the teeth 18 in the circumferential direction. As illustrated by the dotted lines in [Fig. 2c], it has been observed that these fragments of material, identified by F, pass behind the teeth under the synergistic effect of the rotation RI and the rebound of the drill bit on block B, denoted V. In practice, the teeth 18 "jump" the fragments which move relative to the drill bit 10 in the direction opposite to the rotation RI.

[0040] Considering the pair of adjacent teeth 18M and 18V in [Fig. 2c], the dust and fragments F detached from block B at the upstream tooth 18M, located in front of the downstream tooth 18V, in the direction of rotation RI, will encounter the notch 20 situated between these two teeth. This notch 20 will then form an escape route for these dust and fragments F upstream of the downstream tooth 18V. The dust and fragments F will spontaneously pass through the notch 20, as illustrated along the path C, and thus avoid encountering the downstream tooth 18V during the rotation of the drill bit 10. As can be understood, the downstream tooth 18V will thus be able to contact block B and abrade it directly without being affected by the dust and fragments F generated upstream.

[0041] Overall, the notches 20 formed in the block 12 allow for the drainage of dust and fragments F to prevent their accumulation in the groove progressively formed in the block B during drilling. This feature ensures maximum abrasion potential of the teeth 18 by preventing material detached from the block B from remaining flush with the surface S and thus hindering tooth-surface contact. It should also be noted that the invention prevents premature wear of the body 12 and the teeth 18 from friction between the end edge 14 and the contour of the teeth 18 and the dust and fragments F.

[0042] As illustrated in [Fig.2d], the path C of the dust and fragments F naturally takes place in the inside-outside direction of the body 12, namely is directed towards the outside space E, passing through the notches 20. This path dynamic C results in particular from the centrifugal force generated by the rotation of the drill bit 10. In this regard, it is advantageously recommended to form at least one helical groove, identified by 26, along the perimeter of the outside surface 12e of the body 12.

[0043] Upon exiting the external space E through the notches, the dust and fragments F are found at the interface between the external surface 12e and the boundary wall of the groove formed in block B as the drill body 12 progresses in block B along the penetration direction Tl. This helical groove 26 guides these dust and fragments F in the opposite direction to the penetration direction Tl, until they can freely exit the interface between the surface exterior 12th and the boundary wall of the groove formed in block B. As understood, such an arrangement aims to avoid an accumulation of dust and fragments F against the exterior surface 12th which would lead to its progressive wear by friction.

[0044] Advantageously, this helical groove 26 extends to the connecting end 16, where the diameter in longitudinal section of the body is notably smaller than at the level of the end edge 14, so as to be able to ensure the rejection of dust and fragments F regardless of the penetration depth of the drill bit 12.

[0045] It should be noted that the arrangement of the teeth 18 and the notches 10 according to the invention, in addition to ensuring the evacuation of fragments and dust F generated during drilling, guarantees satisfactory mechanical strength for rotary-percussion operation. Indeed, since the notches 10 are formed at a distance from the teeth 18 along the circumferential direction AZ, sufficient material of the body 12 remains in the vicinity of the teeth 18 to adequately absorb the mechanical stresses, which would not be the case if the notches extended to the root of the teeth. In fact, during drilling, the body 12 essentially absorbs the forces to which the teeth 18 are subjected as they rub against and impact the block B, resulting in a local concentration of stresses at the interface between the teeth 18 and the body 12.

[0046] In light of the foregoing, the specific arrangement of the notches 20 and the widely spaced teeth 18 increases the penetration potential of the drill bit 10 by purging the generated splinters, fragments, and dust, without inducing mechanical weakening that could limit its service life. The drill bit 10 according to the invention therefore provides increased compatibility and efficiency for rotary-percussion drilling of a block B of hard material, such as concrete.

[0047] The first embodiment of the drill bit 10 is characterized by the formation of recesses, namely notches 20, radially to the central axis AX in the thickness Ep of the body 12, i.e., formed orthogonally to the local tangent to the circular cross-section of the body 12. In the example shown in Figures 2a to 2d, these recesses take the form of notches 20 that traverse the entire thickness Ep of the body and extend parallel to the longitudinally oriented central axis AX. It should be noted, however, that a different type or orientation of recess may be used in the first embodiment.

[0048] By way of example, the notches 20 can be oriented linearly at an angle to the central axis AX, as in the example in [Fig. 3]. In such a case, the notches 20 extend along both a longitudinal and a circumferential component. As a result, their bottom facet 20b is not longitudinally aligned with their open longitudinal end at the end edge 14.

[0049] In this case, it is recommended that the notches 20 extend from the end edge 14 towards the downstream tooth, i.e., the adjacent tooth in the opposite direction to the predefined rotation RI, as in the example of [Fig. 3]. This particular orientation is judiciously defined with regard to the path C of the dust and fragments F. Indeed, as described based on [Fig. 2c], the dust and fragments F move relative to the drill bit 10 in the opposite direction to the rotation RI. The fact that the notches 20 generally follow the path C of this dust and these fragments F facilitates their capture.

[0050] Figure 4 illustrates another example in which the notches 20 have a extended both greater in the circumferential direction, namely extending over a larger sector of the body 12, and less in the longitudinal direction than in the example of figures 2a and 2b. This particular morphology of notches 20 increases the window for capturing dust and fragments F in the immediate vicinity of the end edge 14.

[0051] With reference to [Fig. 5], the recesses take the form of notches 20, each extended at its bottom facet 20b by a slot 22. In this example, the notches 20 extend strictly from the end edge 14 along the longitudinal direction, while the slots 22 extend diagonally. This embodiment is a hybrid version of the variant in [Fig. 4] and the variant in [Fig. 3], combining their respective advantages.

[0052] Finally, [Fig. 6] illustrates another example of a variant that corresponds to the variant of [Fig. 5], with the difference that the notches 20 are extended in the opposite direction to the penetration direction T1 by grooves 24, not slots 22. These grooves 24 are partially cut into the thickness Ep of the body 12 from the outer surface 12e, i.e., without opening into the inner chamber I. With this arrangement, the dust and fragments F that pass through the notches 20 towards the outer space E of the drill body 12 are directly guided by the grooves 24 along the outer surface 12e to be expelled from the working area. In particular, it is preferred to have all or part of the grooves 24 communicate with the helical groove 26 formed on the outer surface 12e to further facilitate the flow of this dust and fragments F.

[0053] Unlike the first embodiment, a second embodiment, with reference to Figures 7a to 7d, proposes forming the notches 20 at an angle to the radial direction AY. As illustrated, the notches 20 extend at an angle α from the outer surface 12e to the inner surface 12i with respect to the radial direction AY. This angle is oriented in the opposite direction to the predefined direction of rotation RI.

[0054] Each notch 20 is delimited by two lateral facets 20a, which are oriented obliquely in the circumferential direction, forming a bevel with the body 12. These two lateral facets 20a are connected by a bottom facet 20b of the notch. The bottom facet 20b corresponds to the extremum point of the notch in the direction opposite to the direction of penetration T1.

[0055] As a result, the notches 20 each advance towards the tooth 18 located downstream from the inner surface 12i towards the outer surface 12e.

[0056] As stated previously, the dust and fragments F generated by a considered tooth 18 move naturally both towards the downstream tooth 18, i.e. in the opposite direction to the rotation RI, and towards the external space E. This particular notch morphology 20, which extends towards the external space E in the opposite direction to the rotation RI, thus follows the natural path of the dust and fragments F. This results in a most favorable evacuation of the dust and fragments F.

[0057] Indeed, from the point of view of the dust and fragments F, their path C towards the external space E through the notches follows a curved trajectory as illustrated by the dashed line in [Fig. 7d]. Compared to the first embodiment, which imposes a 90° angled trajectory through the notches 20, given that they are formed orthogonally to the local tangent to the body 12, the dust and fragments F do not have to significantly change their direction of propagation in this second embodiment. This has the effect of enhancing the capture of the fragments and dust F by the notches 20, resulting in more efficient evacuation.

[0058] In the example shown in Figures 7a to 7d, and unlike the example shown in Figures 2a to 2d of the first embodiment, the notches 20 are not arranged equidistant from the teeth of a pair of adjacent teeth. More specifically, for each pair of two adjacent teeth, each notch 20 is positioned closer to the downstream tooth 18V than to the upstream tooth 18M, considering the predefined direction of rotation RI. In other words, each notch 20 is positioned closer to the adjacent tooth in the opposite direction to the direction of rotation RI.

[0059] In practice, the fragments and dust F are extracted from the block chaotically in response to the impacts of the teeth 18 by percussion. Considering the upstream tooth 18M of the tooth pair 18M, 18V, it is understood that the greater the distance separating the notch 20 from this tooth 18M, the more time the fragments and dust F generated by this tooth 18M have to centralize into a jet that strikes the notch 20 under the effect of centrifugal force. This particular arrangement thus has the advantage of maximizing the influx of fragments and dust F encountering the notches 20, which leads to maximum clearance of the working space before the passage of the downstream tooth 18V. Overall, the positioning of the notches 20, each closer to the adjacent tooth in the opposite direction to the direction of rotation RI maximizes tooth-block contact and therefore induces better penetration of the tool into the block B.

[0060] The value of angle α and the tooth-notch spacing are practically defined as a function of the outer radius Re of the body 12. With reference to [Fig. 7c], it can be assumed that for a drill bit whose body 12 has an outer diameter of 68 mm, the following can be used: - the notches should be distributed between 5 and 6 mm, and more precisely at 5.75 mm, with the teeth in the opposite direction to RI; and - form these notches in the thickness Ep of the body at an angle a with respect to the radial direction AY of a value between 0° and 30° and preferably of the order of 25°.

[0061] The drill bit 10 has been described based on the accompanying figures as comprising alternating teeth 18 and notches 20 along the circumference of the body 12. It should be noted that the invention is not limited to this feature. For example, several notches 20 may be formed between two adjacent teeth 18, or an angular sector of the body defined between two adjacent teeth may be devoid of notches without departing from the scope of the invention.

[0062] In the example shown in the figures, the teeth 18 are distributed at regular intervals in the circumferential direction AZ. It should be noted, however, that the invention is not limited to a particular regularity in the arrangement of these teeth 18.

[0063] Also, the first embodiment is not limited exclusively to providing notches 20 each formed precisely equidistant from two teeth. Similarly, it is not required to maintain a distribution of the notches 20 closer to the teeth in the opposite direction to the predefined direction of rotation RI in the case of the second embodiment.

[0064] In the context of the invention, each notch 20 can be distributed, depending on the specific case, either at the same distance from the directly adjacent teeth, or closer to the adjacent tooth in the predefined direction of rotation RI, or even closer to the adjacent tooth in the opposite direction to the predefined direction of rotation RL

[0065] As stated previously, a distribution of the notches 20 closer to the tooth directly adjacent to them in the opposite direction to the predefined direction of rotation RI is to be preferred when it comes to maximizing the penetration potential of the tool in the block B.

[0066] Conversely, a distribution of the notches 20 closer to the tooth directly adjacent to them in the predefined direction of rotation RI may be used. This particular arrangement aims to provide the drill bit 10 with increased durability. Indeed, by limiting the measured distance between a given tooth and the notch located downstream, it is understood that this leads to limiting the end edge surface 14 that is likely to rub against the fragments F before their expulsion through notch 20. Specifically, such a reduction in the working edge arc section 14 in the circumferential downstream extension of each tooth reduces the occurrence and induced wear of a contact between the end edge 14 and a fragment F.

[0067] The distribution of the notches at iso-distance from the adjacent teeth corresponds to a compromise between durability and penetration potential of the tool.

[0068] Note that a random or hybrid arrangement of the notches 20 can also be used. A hybrid arrangement is understood to be one in which all or part of the notch positions described above are found.

[0069] Finally, the invention is not limited to the orientation and nature of the recesses described on the basis of the various embodiments illustrated. By way of example, the various notches 20 of the first and second embodiments can be replaced by grooves or channels.

[0070] In practice, considerable flexibility is allowed in the positioning of the teeth 18 and the recesses according to the invention, provided that there is at least one recess positioned between a pair of adjacent teeth 18 and at a distance from each of these teeth 18 in the circumferential direction AZ. With this arrangement, the drill bit 10 according to the invention is particularly well suited for rotary-percussion operation, ensuring efficient removal of dust and fragments while maintaining sufficient rigidity to withstand various load cases, in particular the repeated energetic shocks of percussion.

Claims

Demands

1. A drill bit (10) adapted for rotary-percussion work, comprising: - a hollow cylindrical body (12) with a central axis of longitudinal orientation (AX), of thickness (Ep) defined between an inner surface (12i) and an outer surface (12e) of the body, the body (12) being delimited longitudinally by an end rim (14), this body (12) being intended to be driven in rotation around the longitudinal axis (AX) in a predefined direction of rotation (RI) to penetrate longitudinally from the end rim (14) through a block (B) in the direction of penetration (Tl); - a series of teeth (18) carried by the body (12) projecting longitudinally from the end rim (14) in the direction of penetration (Tl) to come into contact with the block (B), these teeth (18) being arranged in a spaced manner along the circumference of the end rim (14);in which at least one recess (20) is formed through all or part of the thickness (Ep) of the body (12) extending from the end edge (14); and in which each tooth (18) is arranged circumferentially away from said at least one recess; the drill bit (10) being characterized in that said at least one recess (20) is formed at an angle α with respect to the radial direction (AY) so as to extend from the inner surface (12i) to the outer surface (12e) in the opposite direction to the predefined direction of rotation (RI) about the longitudinal axis (AX), in which said at least one recess is formed closer to the adjacent tooth in the predefined direction (RI) of rotation than it is to the other adjacent tooth in the opposite direction to the predefined direction (RI) of rotation.

2. A drill bit (10) according to claim 1, comprising a series of recesses arranged at intervals along the circumference of the end rim (14), and in which the teeth (18) and the recesses (20) are arranged alternately along the circumference of the body (12).

3.

4.

5.

6.

7. Drill bit (10) according to any one of the preceding claims, wherein said at least one recess is a notch (20) which goes through the thickness (Ep) of body (12). Drill bit (10) according to claim 3, wherein said at least one notch (20) is extended in the opposite direction to the direction of penetration (Tl) by a groove (24) formed from the outer surface (12e) of body (12). drill bit (10) according to claim 4, in which at least one groove extending a notch communicates with a helical groove (26) formed in the outer face of the body (12). Drill bit (10) according to any one of the preceding claims, wherein said at least one recess extends parallel to the central axis (AX) from the end edge (14). Drill bit (10) according to any one of claims 1 to 6, wherein said at least one recess extends from the end edge (14) along a longitudinal component in the opposite direction of penetration (Tl) and a circumferential component in the opposite direction to the predefined direction of rotation (RI).