DRILL BIT SUITABLE FOR PERCUSSION

Abstract

The present invention relates to a drill bit (10) comprising: - a body (12), with a longitudinal central axis (AX) and delimited longitudinally by an end edge (14), intended to be driven in rotation about the longitudinal axis to penetrate longitudinally from the end edge through a block in a penetration direction (T1); - a series of teeth (18) carried by the body projecting from the end edge (14) in the penetration direction to come into contact with the block, these teeth being arranged in a spaced manner along the circumference of the end edge; in which recesses (20) are formed in the body and arranged in a spaced manner along the circumference of the end edge, each recess extending from the end edge; and in which each tooth (18) is arranged at a circumferential distance from each recess (20). Figure for abstract: Figure 2a

Description

Title of the invention: DRILL BIT ADAPTED TO PERCUSSION 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 to drilling hard material by rotation-percussion. TECHNICAL BACKGROUND

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

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

[0004] In the case of drilling a block made of a hard material such as stone or concrete, it is generally recommended to mount the drill bit on a percussion drill or a perforator. Such machines make it possible to add a chiseling / percussion component 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 makes it possible to increase 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 impacts.

[0006] In order to guarantee the longevity of the drill bit 1, the manufacturers have mostly chosen to ensure a continuity of circumferential material at the first end 4, which makes it possible to prevent the appearance of local deformations, which could lead in the most critical case to tooth loosening.

[0007] This architecture, although effective in ensuring good integrity of the drill bit, nevertheless suffers from problems of accumulation of dust and fragments resulting from abrasion. This accumulation of dust and fragments makes the percussion energy transferred into the wall suboptimal, in addition to generating risks of jamming of the tool and increased wear of the body and teeth by friction.

[0008] The aim of the invention is to propose a drill bit architecture suitable for percussion work making it possible to at least partially avoid the drawbacks identified above. Statement of the invention

[0009] To this end, the invention relates to a drill bit suitable for rotary-percussion work, comprising: - a hollow cylindrical body with a central axis of longitudinal orientation, of thickness defined between an inner surface and an outer surface of the body, the body being delimited longitudinally by an end edge, this body being intended to be driven in rotation around the longitudinal axis to penetrate longitudinally from the end edge through a block following 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 arranged in a spaced manner along the circumference of the end edge; wherein at least one recess is formed through all or part of the thickness of the body extending from the end edge; and wherein each tooth is arranged circumferentially spaced from said at least one recess.

[0010] The invention also relates to a drill bit so defined, comprising a series of recesses arranged in a spaced manner along the circumference of the end rim, and in which the teeth and 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 an iso-distance from the teeth directly adjacent 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 about the longitudinal axis, and in which each said at least one recess is formed closer to the adjacent tooth in the direction opposite to the prefinished direction of rotation than it is to the other adjacent tooth in the prefinished 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 prefinished direction of rotation than it is to the other adjacent tooth in the direction opposite to the prefinished 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 obliquely at an angle α relative to the radial direction so as to extend from the inner surface towards the outer surface in the direction opposite to the predefined direction of rotation.

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

[0017] The invention also relates to a drill bit thus defined, in which said at least one notch is extended in the direction opposite 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 direction opposite to the predefined direction of rotation. Brief description of the drawings

[0021] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which: - [Fig.l] is a perspective view of an example of the production of a drill bit 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 detail view of [Fig.2a]; - [Fig.2c] is a projected view illustrating the dust evacuation dynamics during a rotary-percussion drilling operation with the bit of [Fig.2a]; - [Fig.2d] is a longitudinal view which illustrates the dynamics of evacuation of dust and fragments generated during a rotary-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 in accordance with a second embodiment; - [Fig.7b] is a detail 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 illustrating the dynamics of dust and fragment evacuation during a rotary-percussion drilling operation with the drill bit of [Fig.7a]. DETAILED DESCRIPTION OF THE INVENTION

[0022] For the description of the invention and the understanding of the claims, a drill bit reference frame will be adopted, without limitation, defined by longitudinal, radial and circumferential orientations according to the reference AX, AY, AZ indicated in the figures. The radial direction, defined by the axis AY, is at all points a direction orthogonal to the axis AX and passing through the latter, and the circumferential direction AZ is defined as rotating at iso-distance around the axis AX. Concretely, an element is said to be radially “outer” or “external” with respect to another if it is further from the axis AX than the other, and conversely an element is said to be radially “inner” or “internal” if it is less far from the axis AX than the other.

[0023] In the following description, identical, similar or analogous elements will be designated by the same reference numbers.

[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, which extends along a central axis AX of longitudinal orientation. This body 12 is defined in thickness Ep between an outer surface 12e with a circular contour, of radius noted 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 edge or ridge 4, and a connecting end 16.

[0026] The connecting end 16 is shaped to be grafted onto a drill bit holder rod of a rotating machine, while the end edge 14 is intended to be arranged opposite a block B to be drilled. As understood, the end edge 14 corresponds to the end of the body 12 from which the drill bit is inserted 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 the 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 carried by the body 12 while being distributed in the circumferential direction AZ. In practice, the teeth are shaped with a cutting face which conditions 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, longitudinally extending notches are formed in the thickness Ep of the drill bit body 12, from the end edge 14. The teeth 18 are inserted by complementary shape each in a notch 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 T1 of penetration of the drill bit 10 along the longitudinal direction. As understood, the teeth 18 are arranged to project longitudinally from the end edge 14 in the direction of penetration T1 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 drill bit-block abrasion interfaces during drilling.

[0030] The idea underlying the invention is to propose a drill bit 10 specifically adapted to be used in rotation-percussion, namely subjected both to a rotation in the circumferential direction AZ and to an oscillating back and forth movement resulting from the application of shocks along the longitudinal axis AX. It is thus aimed to provide a drill bit 10 specifically adapted to equip a hammer drill or a percussion drill, in particular to ensure drilling of hard material such as stone or concrete.

[0031] In practice, working in rotation-percussion mechanically stresses the drill bit 10 more than in the case of pure rotation of the tool. Also, since the percussion fragments the material of the wall, there follows a greater generation of fragments, splinters and dust that could impair the drill bit's penetration potential by clumping under the teeth 18.

[0032] The invention proposes to satisfy the double condition of granting the drill bit 10: - satisfactory mechanical strength to withstand repeated percussion impacts; and - drainage of the fragments outside 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 in 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 to 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 rough manufacturing 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, namely they are each formed orthogonally to the local tangent to the body 12 of circular section. Also, these notches 20 each comprise a longitudinal end open to the outside at the end edge 14. In other words, these notches 20 correspond to a removal of material in 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 direction of penetration TL.

[0037] Also, the notches 20 are identical and each lie in a respective radial plane. In other words, the notches extend parallel to the central axis AX, their bottom facet 20b being aligned longitudinally 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 body portion 12 bounded between two consecutive notches 20. In particular, in the example of FIGS. 2a to 2d, each notch 20 extends at an iso-distance from the teeth 18 directly adjacent 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 percussion on either side of the teeth 18 in the circumferential direction. As illustrated in dotted lines in [Fig.2c], it has been observed that these fragments of material, marked F, pass behind the teeth under the synergistic effect of the rotation RI and the rebound of the drill bit on block B, marked V. Concretely, 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 of [Fig.2c], the dust and fragments F detached from the block B at the level of the so-called upstream tooth 18M, namely located in front of the other so-called downstream tooth 18V, in the direction of rotation RI, will encounter the notch 20 located 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 not encounter the downstream tooth 18V during the rotation of the drill bit 10. As understood, the downstream tooth 18V will thus be able to contact the block B and abrade it directly without being interfered with by the dust and fragments F generated upstream.

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

[0042] As illustrated in [Fig.2d], the path C of the dust and fragments F takes place naturally in the direction from the inside to the outside 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 respect, it is advantageously recommended to form at least one helical groove, marked by 26, along the periphery of the outside surface 12e of the body 12.

[0043] By opening onto the external space E through the notches, the dust and fragments F are found at the interface between the external surface 12e and the delimiting wall of the groove formed in block B as the drill bit body 12 progresses in the block B in the direction of penetration T1. This helical groove 26 ensures the guidance of these dust and fragments F in the direction opposite to the direction of penetration T1, until they can freely extract themselves from the interface between the surface outer surface 12e and the delimiting 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 outer surface 12e which would lead to its progressive wear by friction.

[0044] Advantageously, this helical groove 26 extends to the connection 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 whatever the depth of penetration 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 evacuation of the fragments and dust F generated during drilling, guarantees satisfactory mechanical strength for working in rotation-percussion. Indeed, the notches 10 being formed at a distance from the teeth 18 in the circumferential direction AZ, there thus remains enough material of the body 12 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. Indeed, during drilling, the body 12 essentially absorbs the forces to which the teeth 18 are subjected, which rub and impact the block B, which results in a local concentration of stresses at the interface between the teeth 18 and the body 12.

[0046] In view of the above, the specific arrangement of the notches 20 and the teeth 18 spaced apart from each other makes it possible to increase the penetration potential of the drill bit 10, via a purge of the generated chips, fragments and dust, without however inducing a mechanical weakening which could limit the operating 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 marked by the formation of recesses, namely the notches 20, radially to the central axis AX in the thickness Ep of the body 12, namely formed orthogonally to the local tangent to the body 12 of circular section. In the example of FIGS. 2a to 2d, these recesses take the form of notches 20 which pass through the entire thickness Ep of the body and extend parallel to the central axis AX of longitudinal orientation. It should be noted, however, that a different nature or orientation of recess may be retained within the framework of the first embodiment.

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

[0049] It is recommended in this case that the notches 20 advance from the end edge 14 towards the tooth located downstream, namely adjacent in the direction opposite to the predefined direction RI of rotation, 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 on the basis of [Fig. 2c], the dust and fragments F move relative to the drill bit 10 in the direction opposite to the rotation RI. The fact that the notches 20 generally follow the path C of these dust and fragments F promotes their capture.

[0050] [Fig.4] illustrates another example in which the notches 20 have a extended both more 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 close vicinity of the end edge 14.

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

[0052] Finally, [Fig. 6] illustrates another example of a variant which corresponds to the variant of [Fig. 5] with the difference that the notches 20 are extended in the direction opposite to the direction of penetration T1 by grooves denoted 24, not slots 22. These grooves 24 are partially hollowed out in the thickness Ep of the body 12 from the outer surface 12e, namely without opening into the internal enclosure I. With this arrangement, the dust and fragments F which pass through the notches 20 towards the outer space E of the drill bit 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 promote the flow of these dust and fragments F.

[0053] Unlike the first embodiment, it is recommended according to a second embodiment, with reference to FIGS. 7a to 7d, to form the notches 20 at an angle relative 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 relative to the radial direction AY. This angle is oriented in the direction opposite 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 notch bottom facet 20b. The bottom facet 20b corresponds to the extremum point of the notch in the direction opposite to the penetration direction 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 tooth 18 considered move naturally both towards the tooth 18 located downstream, namely in the direction opposite to the rotation RI, and towards the external space E. This particular morphology of notch 20, which extends towards the external space E in the direction opposite 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 in dotted lines in [Fig.7d]. In comparison with the first embodiment which imposes a 90° bent trajectory through the notches 20, understood 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 propagation orientation in the context of this second embodiment. This has the consequence of exacerbating the capture of the fragments and dust F by the notches 20 to result in more efficient evacuation.

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

[0059] In practice, the fragments and dust F are extracted from the block in a chaotic manner in response to the impacts of the teeth 18 by percussion. Considering the upstream tooth 18M of the pair of teeth 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 which encounters the notch 20 under the effect of centrifugal force. This particular arrangement thus has the advantage of maximizing the inflow of fragments and dust F encountering the notches 20, which leads to maximum release 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 direction opposite to the direction of rotation RI maximizes tooth-block contact and therefore induces better penetration of the tool into block B.

[0060] The value of the angle a and the tooth-notch spacing are in practice defined as a function of the external radius Re of the body 12. With reference to [Fig.7c], it may be retained for a drill bit whose body 12 has an external diameter of 68 mm to: - distribute the notches between 5 and 6 mm, and more precisely at 5.75 mm, from the teeth in the direction opposite to the direction RI; and - form these notches in the thickness Ep of the body at an angle a relative 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 on the basis of the appended figures as comprising an alternation of 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 even 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 of the figures, the teeth 18 are distributed at regular pitches 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 strictly equidistant from two teeth. Similarly, it is not required to respect a distribution of the notches 20 closer to the teeth in the direction opposite 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 according to the specific case either at iso-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 direction opposite to the predefined direction of rotation RL.

[0065] As stated previously, a distribution of the notches 20 closer to the tooth which is directly adjacent to them in the direction opposite to the predefined direction of rotation RI is to be favored 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 which is directly adjacent to them in the predefined direction of rotation RI can be retained. By this particular arrangement, it is intended to grant the drill bit 10 increased durability. Indeed, by limiting the measured spacing between a tooth considered and the notch located downstream, it is understood that this leads to limiting the end edge surface 14 likely to rub against the fragments F before their expulsion through the notch 20. Concretely, such a reduction in the working edge arc section 14 in the circumferential downstream extension of each tooth reduces the occurrence and the induced wear of 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 may also be used. A hybrid arrangement is understood to mean an arrangement in which all or part of the notch positions set out above are found.

[0069] Finally, the invention is not limited to the orientation and nature of the recesses described on the basis of the different embodiment variants illustrated. By way of example, the different notches 20 of the first and second embodiments may be substituted by grooves or grooves.

[0070] In practice, great flexibility in positioning the teeth 18 and the recesses according to the invention is permitted, 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 to working in rotation-percussion by ensuring effective purging of dust and fragments while maintaining sufficient stiffness to withstand the different load cases, in particular the repeated energetic shocks of percussion.

Claims

Claims

1. Drill bit (10) suitable 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 edge (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 edge (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 edge (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 edge (14);wherein 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 wherein each tooth (18) is arranged circumferentially spaced from said at least one recess; the drill bit (10) being characterized in that said at least one recess (20) is formed obliquely at an angle α relative to the radial direction (AY) so as to extend from the inner surface (12i) towards the outer surface (12e) in the direction opposite to the predefined direction of rotation (RI) around the longitudinal axis (AX); wherein said at least one recess is formed closer to the adjacent tooth in the direction opposite to the pre-finished direction (RI) of rotation than it is to the other adjacent tooth in the pre-finished direction (RI) of rotation.;

2. A drill bit (10) according to claim 1, comprising a series of recesses arranged in a spaced manner along the circumference of the end rim (14), and wherein the teeth (18) and 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 passes through the thickness (Ep) of the body (12). Drill bit (10) according to claim 3, wherein said at least one notch (20) is extended in the direction opposite to the direction of penetration (Tl) by a groove (24) formed from the outer surface (12e) of the body (12). A drill bit (10) according to claim 4, wherein at least one groove which extends a notch communicates with a helical groove (26) formed in the outer face of the body (12). A drill bit (10) according to any preceding claim, 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 direction opposite to the predefined direction (RI) of rotation.

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