Rock drill with five cutting edges

Abstract

The invention relates to a rock drill (10) comprising a shank portion (12) on which at one end an insertion portion (16) is formed for connection to a tool holder of a drilling machine tool and at the other end a drill head (18) for machining a substrate. The drill head (18) has at least one cutting edge (20) with a projection (22) at its outer end, which points away from the cutting edge (20) tangentially to the longitudinal axis (L). The rock drill (10) has a high extraction rate and a low risk of jamming.

Description

[0001] Hilti Corporation in Schaan

[0002] Principality of Liechtenstein

[0003] Rock drill with five cutting edges

[0004] Description

[0005] The invention relates to a rock drill comprising a shaft section, on one end of which an insertion section for connection to a tool holder of a drilling machine and on the other end of which a drill head for machining a subsoil is formed, wherein the drill head has at least one cutting edge extending outwards from a central longitudinal axis of the drill head.

[0006] Such rock drills are typically used to work on rocks such as reinforced concrete, for example to drill holes into the rock.

[0007] It can happen that the rock drill bit becomes stuck in the rock. This happens particularly frequently when the rock drill bit comes into contact with the reinforcement of reinforced rock.

[0008] This may result in damage to a machine tool in which the rock drill is mounted and / or to a user of the machine tool or rock drill.

[0009] The object of the present invention is therefore to offer a rock drill that allows for particularly safe processing of rock. Furthermore, it is desirable for the rock drill to enable high drilling performance.

[0010] This object is achieved by a rock drill comprising a shaft section having at one end an insertion section for connection to a tool holder of a drilling machine and at the other end a drill head for machining a subsurface, wherein the drill head has at least one cutting edge extending outwards from a central longitudinal axis of the drill head, wherein the cutting edge has a projection at its outer end pointing away from this cutting edge tangentially to the longitudinal axis. This is based on the idea that a rock drill bit becomes stuck in reinforced rock in particular if reinforcement can become jammed between the cutting edges of the drill head. It is therefore advantageous to fill the spaces between the cutting edges as widely as possible or to keep the spaces overall as small as possible.

[0011] In particular, a gap can be reduced by the projection(s). The projection(s) may have no influence on the effective contact area and thus on the specific impact power and the resulting removal rate.

[0012] A higher number of cutting edges allows the rock drill to be guided more stably during drilling. The risk of reinforcement becoming jammed between the more closely spaced cutting edges can be further reduced.

[0013] Therefore, it can generally be advantageous to provide a large number of cutting edges on the drill head. However, the number of cutting edges also increases the contact area between the drill head and the subsoil, for example, the reinforced rock. This reduces the specific impact power relative to the contact area, assuming the same impact energy per impact of the machine tool in which this rock drill is mounted, and the same impact frequency. The mining performance of the rock drill can therefore deteriorate with an increasing number of cutting edges.

[0014] Based on previous experience, it has been shown that a favorable balance is achieved, in particular between the tendency to jam, stability and mining performance, if the drill head has at least three, preferably at most seven, particularly preferably five, cutting edges extending outwards from a central longitudinal axis of the drill head.

[0015] Each of the cutting edges can have a projection at its outer end pointing away from the respective cutting edge tangentially to the longitudinal axis, so that gaps between adjacent cutting edges can be further reduced.

[0016] The rock drill thus enables drilling work with no or at most extremely low risk of jamming, thus ensuring particularly safe work. Further features and advantages of the invention will become apparent from the following detailed description of exemplary embodiments of the invention, based on the figures of the drawing, which illustrate details essential to the invention, and from the claims. The features shown therein are not necessarily to scale and are presented in such a way that the special features of the invention can be clearly seen. The various features can be implemented individually or in groups in any combination in variants of the invention.

[0017] The schematic drawing illustrates exemplary embodiments of the invention and explains them in more detail in the following description. In particular, the features described in the dependent claims are also explained in more detail with reference to the drawing.

[0018] They show:

[0019] Fig. 1 a rock drill in a side view,

[0020] Fig. 2 the rock drill in a perspective view,

[0021] Fig. 3 the rock drill in another perspective view,

[0022] Fig. 4 a plan view of a drill head of the rock drill,

[0023] Fig. 5 is a perspective view of a front section of the rock drill and in particular of the drill head,

[0024] Fig. 6 to 9 several side views of a partial section of a shaft section and of a drill head of a rock drill adjacent thereto and

[0025] Fig. 10 is a side view corresponding to the view in Fig. 6 of a rock drill.

[0026] In the following description of the figures, the same reference numerals are used for identical or functionally corresponding elements to facilitate understanding of the invention.

[0027] Fig. 1 shows a side view of a rock drill 10. The rock drill 10 comprises a shaft section 12. A conveying helix 14 is formed on the shaft section 12.

[0028] At one end of the shaft section 12, an insertion section 16 is provided for connection to a tool holder of a drilling machine (not shown in Fig. 1), and at the other end, a drill head 18 is provided for machining a substrate (not shown in Fig. 1), for example, reinforced rock. The insertion section 16 is designed, for example, in the manner of a plug-in end generally known as an "SDS Max." It is also conceivable that the plug-in end is designed in the manner of a so-called "SDS Plus" or a similar standardized plug-in end.

[0029] The conveyor helix 14 is designed as a double-flighted helix. Alternatively, it would also be conceivable to design the conveyor helix as a three-, four-, or five-flighted helix. A double-flighted helix can convey mined rock away from the drill head 18 with a high transport capacity. It can be designed to be comparatively robust and yet can be manufactured at an acceptable cost. Its turning bars are sufficiently far apart so that even larger grain sizes of the mined rock can be conveyed along the conveyor helix without jamming. A double-flighted helix 14 has therefore proven particularly advantageous.

[0030] The drill head 18 has five cutting edges 20. For reasons of clarity, only one of the five cutting edges 20 is marked with a reference symbol.

[0031] The cutting edges 20 extend outward from a central longitudinal axis L of the drill head 18. It is understood that the rock drill 10 can also be operated in a percussive manner, particularly along the longitudinal axis L, to mine rock. Overall, the rock drill 10 can thus be operated in a rotary percussive manner to mine rock.

[0032] The rock drill 10 can be designed for drill holes with a diameter of at least 10 mm and / or at most 32 mm, so that despite the special geometry described in more detail below, a sufficient material thickness can be ensured everywhere.

[0033] With such dimensions, the weight and thus the associated inertia can still remain within a range suitable for rotary impact rock mining.

[0034] Preferably, the drill head 18 comprises a more fracture-resistant material than the shaft portion 12. While the shaft portion 12 may comprise steel, for example, the drill head may comprise a hard metal, such as a tungsten-based hard metal. Fig. 2 and Fig. 3 show further perspective views of the rock drill 10, so that, in particular, the conveying helix 14, the insertion portion 16, and the drill head 18 can be seen from additional viewing directions.

[0035] Fig. 4 shows a top view of the drill head 18. The five cutting edges 20 can be seen.

[0036] At its outer ends, each of the cutting edges 20 has a projection 22 pointing away from the respective cutting edge 20 tangentially to the longitudinal axis L. For reasons of clarity, only one of the projections 22 is marked with a reference symbol.

[0037] As can be seen, for example, from Fig. 4, the projections 22 pointing away from the respective cutting edge 20 tangentially to the longitudinal axis L each have at least one main direction H which has at least one predominant directional component pointing in a tangential direction.

[0038] The projections 22 point along a circumferential direction U. The circumferential direction U corresponds to the working direction of rotation of the rock drill 10, in which it rotates to excavate the subsoil. Thus, the projections 22 each extend slightly ahead of their associated cutting edges 20 during rock excavation.

[0039] Alternatively or additionally, it is also conceivable that at least one of the projections 22 points against the circumferential direction U, thus slightly trailing its associated cutting edge 20.

[0040] In particular, in alternative rock drills, at least one of the cutting edges 20 can be equipped with leading and trailing projections 22.

[0041] The projections 22 reduce the gaps 24, of which in Fig. 4 only one is marked with a reference symbol as an example, between adjacent cutting edges 20.

[0042] At the same time, free space remains in the spaces 24 so that crushed material can reach the conveyor helix 14 from there. The cutting edges 20 extend rotationally symmetrically, preferably at an angle alpha of between 70° and 80°, in particular 72°, from a center point M of the drill head 18, i.e., transversely to the longitudinal axis L (see Fig. 1). The rotationally symmetrical arrangement results in a particularly uniform distribution of the contact of the drill head 18 with the subsurface across the cross-section of the drill head 18. The rock drill 10 can thus be guided very stably into the subsurface to be processed.

[0043] The cutting edges 20 have cutting edges 26. The cutting edges 26 are curved, with the exception of one cutting edge 26, i.e., in Fig. 4, up to the cutting edge 26 at approximately 1 o'clock, ie, which runs obliquely upwards to the right.

[0044] It is also conceivable to design an alternative rock drill 10 with such cutting edges 26, but without projections 22. Such an alternative rock drill 10 may have one or more of the features described above and / or below and / or included in the drawing, in particular with the exception of the features relating to the projections 22.

[0045] Fig. 5 shows a further perspective view of the rock drill 10. In particular, the end of the rock drill 10 with its drill head 18 can be seen.

[0046] Two of the five cutting edges 20, particularly with their free ends, are set back relative to the adjacent cutting edges 20, i.e., parallel to the longitudinal axis L in the direction of the conveyor helix 14. They form secondary cutting edges 28. Thus, the drill head 18 impacts the substrate to be machined primarily with the three remaining cutting edges 20, hereinafter referred to as main cutting edges 30.

[0047] The secondary cutting edges 28 are more curved perpendicular to the longitudinal axis L than the main cutting edges 30, so that the removal of drilling dust is further improved.

[0048] In this respect, the rock drill 10 with its five cutting edges 20 results in a particularly high specific impact power and thus a particularly high mining performance.

[0049] In addition to their stabilizing function described above, the secondary cutting edges 28 can be used particularly when the rock drill 10 encounters reinforcement, such as steel reinforcement, and possibly penetrates it to some extent. In this case, the secondary cutting edges 28 can accelerate the removal of the reinforcement.

[0050] Fig. 5 further shows that the free ends of the projections 22 are offset rearward relative to their cutting-edge ends, i.e., toward the conveyor helix 14, so that the projections 22 also do not impact the subsurface during normal rock mining, thereby further minimizing the effective contact area in favor of a high specific impact power. Together with the side surfaces of the cutting edges 20, the projections 22 also form sliding surfaces along which crushed material can be guided toward the conveyor helix 14, so that the rearward offset of the free ends of the projections 22 also improves the removal of the crushed material.

[0051] Furthermore, it can be seen from Fig. 5 and in conjunction with Fig. 1 to Fig. 3 that the conveyor spiral 14 is designed with two flights in order to achieve a high conveying capacity.

[0052] Cutting edges 20 that do not directly adjoin a spiral wall 33 (of which only one spiral wall 33 is marked with a reference symbol in Fig. 5 for illustrative purposes) of one of the spiral flights 32 of the conveyor spiral 14 are supported by support bodies 34 projecting from the conveyor spiral 14. The support bodies 34 are configured to project from the conveyor spiral 14 independently of the spiral walls 33. Thus, such a support body 34 is configured for the five cutting edges 20 and the two-flight conveyor spiral 14.

[0053] The support bodies 34 thus make it possible to connect a drill head 18 with a number of cutting edges 20 to a conveyor helix 14 having a number of helix walls 33 that differs from the number of cutting edges 20. In particular, a drill head 18 with an odd number of cutting edges 20 can be provided with a conveyor helix 14 with an even number of threads. Thus, particularly advantageous configurations for the drill head 18 can be combined with particularly advantageous configurations of the conveyor helix 14.

[0054] All cutting edges 20 open into the conveyor spiral 14 along walls 36, of which, for reasons of clarity, only one wall 36 is provided with a reference symbol in Fig. 5. The walls 36 run parallel to the longitudinal direction L, resulting in inlet regions 38 opening into the conveyor spiral 14 parallel to the longitudinal direction L, of which only one is provided with a reference symbol. The inlet regions 38, and in particular the walls 36 running parallel to the longitudinal direction L, serve to further improve the removal of comminuted material.

[0055] Preferably, the drill head 18 can be butt-joined to the shaft portion 12 using a metallurgical joining zone 40 to ensure the necessary strength of the connection. The metallurgical joining zone 40 can be produced, for example, by welding or soldering.

[0056] Fig. 6 to 9 show several side views from different angles of a partial section of a shaft section 12 and of a drill head 18 of a rock drill 10 adjacent thereto.

[0057] Particularly in Fig. 6, it can be seen that the cutting edge 20, provided with a reference symbol, sits on the support body 34. The support body 34, in turn, is designed to protrude from the conveyor spiral 14. It sits between two spiral walls 33 of one of the spiral passages 32.

[0058] Such support of cutting edges 20 by support bodies 34 can be provided both for cutting edges 20 with a tangential projection and for cutting edges 20 without a tangential projection. Therefore, cutting edges 20 without a tangential projection are shown as examples in Figs. 6 to 9.

[0059] Fig. 10 shows, in a view corresponding to Fig. 6, a partial section of a rock drill 10 in which cutting edges 20 have a tangential projection 22, wherein again only one cutting edge 20 and the associated projection 22 are marked with reference numerals.

[0060] List of reference symbols

[0061] 10 Rock drill 12 Shaft section 14 Conveyor helix 16 Insert section 18 Drill head

[0062] 20 Cutting edge 22 Projection

[0063] 24 space

[0064] 26 Cutting edge

[0065] 28 Minor cutting edge 30 Main cutting edge 32 Spiral thread 33 Spiral wall 34 Support body

[0066] 36 Wall 38 Introduction area 40 Metallurgical joining zone H Main direction L Longitudinal axis

[0067] M Center U Circumferential direction alpha angle

Claims

Patent claims 1. Rock drill (10), comprising a shaft section (12) on which an insertion section (16) for connection to a tool holder of a drilling machine is formed at one end and a drill head (18) for machining a subsoil is formed at the other end, wherein the drill head (18) has at least one cutting edge (20) extending outwards from a central longitudinal axis (L) of the drill head (18), characterized in that the cutting edge (20) has a projection (22) at its outer end pointing away from this cutting edge (20) tangentially to the longitudinal axis (L).

2. Rock drill according to the preceding claim, characterized in that the drill head (18) has at least three, preferably at most seven, particularly preferably five, cutting edges (20) extending outwards from a central longitudinal axis (L) of the drill head (18).

3. Rock drill according to one of the preceding claims, characterized in that each of the cutting edges (20) has at its outer end a projection (22) pointing away from the respective cutting edge (20) tangentially to the longitudinal axis (L).

4. Rock drill according to one of the preceding claims, characterized in that the projection (22) or the projections (22) point or point along a circumferential direction (U) which corresponds to a working direction of rotation of the rock drill (10).

5. Rock drill according to one of the preceding claims, characterized in that the cutting edges (20) extend rotationally symmetrically, in particular at an angle of 3607n, with n being the number of cutting edges (20), from a center point (M) of the drill head (18).

6. Rock drill according to one of the preceding claims, characterized in that at least one of the cutting edges (20), in particular two of the cutting edges (20), is set back relative to at least one of the cutting edges (20) adjacent to it, ie parallel to the longitudinal axis (L) in the direction of the shaft section (12).

7. Rock drill according to one of the preceding claims, characterized in that the free end of the at least one projection (22) is set back relative to the cutting-side end of this projection (22).

8. Rock drill according to one of the preceding claims, characterized in that a double-start conveyor helix (14) is formed on the shaft section (12).

9. Rock drill according to one of the preceding claims, characterized in that at least one of the cutting edges (20) is supported by a support body (34) projecting from the conveyor helix (14).

10. Rock drill according to one of the preceding claims, characterized in that a metallurgical joining zone (40) is located between the drill head (18) and the shaft section (12). 11 . Rock drill according to one of the preceding claims, characterized in that the drill head (18) has a diameter of at most 32 mm.

12. Rock drill according to one of the preceding claims, characterized in that the drill head (18) has a diameter of at least 10 mm.

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