The invention relates to a rock drill bit, particularly for use in combination with an impact drilling device or hammer drilling device, having the features of the preamble of claim 1, and to a method for producing such a rock drill bit, having the features of the preamble of claim 8.

The rock drill bit in question is suitable for drilling in concrete or steel-reinforced concrete, but also in other masonry, rock or the like. The known rock drill bit (DE 20 2006 003 539 Ul), from which the invention proceeds, is equipped, in the conventional manner, with a drill-bit shank, which has an insertion portion comprising an insertion profile; a helical portion, comprising two removal flutes and two helical webs, that axially adjoins the insertion portion; and a head portion that axially adjoins the helical portion and that comprises a receiver for an insert element. The head portion has a removal-flute runout and a helical- web runout, the conveying function of the helix being largely discontinued in the head portion. The transport of drilling swarf from the head portion into the removal flute results substantially from the drilling swarf turbulence that occurs in the head portion . Overall, various approaches for improving the transport of drilling swarf have become known. One approach consists, for example, in providing supplementary webs, supplementary flutes or the like within the removal flute, in order to provide additional conveying edges and/or additional conveyance volume in the removal flute. These measures, however, have no effect on the transport of drilling swarf from the head portion into the removal flute. The invention is based on the problem of configuring and developing the known rock drill bit in such a way that the transport of drilling swarf is improved, particularly in the region of the head portion.

The above problem is solved, in the case of a rock drill bit according to the preamble of claim 1, by the features of the characterizing portion of claim 1. Substantive is the fundamental consideration that a reduction of geometric discontinuities between the head portion and the helical portion promotes the transport of the drilling swarf from the head portion into the helical portion, in particular into the removal flute.

In particular, in an alternative, it is proposed that in the removal flute a profile formation continues spirally relative to the drill bit axis, which profile formation, when of appropriate design, results in improvement of the transport of drilling swarf within the removal flute.

What is substantive is that the profile formation also continues in the removal-flute runout of the head portion, this corresponding to a reduction of discontinuities between the head portion and the helical portion in the above sense.

Furthermore substantive is that the profile formation continues in the removal-flute runout, rectilinearly and parallelwise in relation to the drill-bit axis. This effects an additional turbulence of drilling swarf in the region of the head portion, whereby the entry of drilling swarf into the removal flute is further promoted.

As an alternative or in addition to the removal flute and the removal-flute runout being provided with a profile formation, as above, it can be provided, according to the proposal, that on the back of the helical web, a profile formation continues spirally relative to the drill-bit axis and continues further in the helical-web runout, where it continues rectilinearly and parallelwise in relation to the drill-bit axis. With appropriate design of this profile formation, the interaction between the side surfaces of the rock drill bit and the material to be drilled can be adjusted within a wide range.

The term "profile formation" encompasses all conceivable formations in the cross profile of the removal flute or of the helical web. These formations, continued in the above manner, in each case constitute, along the removal flute or along the helical web, webs, flutes, edges, steps or the like that run spirally in the removal flute and on the back of the helical web and run rectilinearly in the removal-flute runout and in the helical-web runout.

Preferred configurations for profile formations constitute subject-matter of claims 2 to 5.

According to a further teaching, which likewise is of importance in its own right, the method for producing a rock drill bit is claimed, as set forth in claim 8.

In the case of the method according to the proposal, it is provided, firstly, that the drill-bit shank is formed, by means of extrusion, from a cylindrical blank. In this case, the cylindrical blank is pressed axially through a die.

In particular, it is proposed that the head portion, including the profile formation, is formed in a single extrusion cycle with the use of a single die. Alternatively or additionally it is proposed that the helical portion, including the profile formation, is formed in a single extrusion process with the use of a single die.

Owing to the head portion and/or the helical portion being produced in a single forming step, in this case through a single extrusion cycle, the material costs and the fabrication resource requirement can be reduced substantially, as compared with the known production methods .

In the case of the proposed method, it is to be taken into account that, in principle, before or after the extrusion operation the drill-bit shank can also undergo a material-removing machining operation or the like, to enable a slot, chamfers or the like to be realized. Differing, additional work operations can also be provided for shaping of the insertion end.

The invention is explained m greater detail m the following, with reference to an exemplary embodiment. In the drawing:

Fig. 1 shows a schematic, perspective view of a rock drill bit according to the proposal, and

Fig. 2 shows the rock drill bit according to Fig. 1, in a perspective detail view relating to the head portion.

The rock drill bit according to the proposal is provided with a drill-bit shank 1, which, in the usual manner, has an insertion portion 2 comprising an insertion profile 3. Likewise in the usual manner, the insertion portion 2 is adjoined by a helical portion 4 comprising two removal flutes 5 and two helical webs 6. In principle, the number of removal flutes 5 and helical webs 6 can vary. For simplicity of description, only a single removal flute 5 or a single helical web 6 is referred to in each case in the following. The respective embodiments are then correspondingly applicable to all other removal flutes 5 and helical webs 6. Axially adjoining the helical portion 4 is a head portion 7 having a receiver 8 for an insert element 9, which is represented by a broken line and has a cutting edge 9a. Here, and preferably, the receiver 8 is a slot in the drill-bit shank 1. In principle, however, it is also possible for a mount-on element, having a cutting edge 9a, to be provided here, which mount-on element does not require a slot, requiring instead a receiving surface or a particular receiving profile.

A quite particular form is imparted to the head portion 7 by the fact that, in the case of the exemplary embodiment represented, a slot-type receiver 8 is realized for the insert element 9. Here, and preferably, the head portion 7 is substantially of a box-type configuration as far as its outer dimensions are concerned. This corresponds to the substantially box-type configuration of the slot-type receiver 8. Other configurations of the head portion 7 are conceivable .

A removal-flute runout 10 of the head portion 7 adjoins the removal flute 5 of the helical portion 4, and a helical-web runout 11 of the head portion 7 adjoins the helical web 6 of the helical portion 4. "Adjoins" in this case means that the respective regions are adjoined directly.

In the case of the exemplary embodiment that is represented, and to that extent preferred, the helical- web runout 11 extends substantially rectilinearly and substantially parallelwise in relation to the drill-bit axis la. This is shown in the representation according to Fig. 2, and it is to be noted in this case that the slot-type receiver 8 constitutes a through opening in the helical-web runout 11.

It can best be seen from the representation in Fig. 1 that here, and preferably, in the removal flute 5 a profile formation 12 continues spirally relative to the drill-bit axis la. This profile formation, as to be explained below, is a substantially undulate profile formation 12.

What is substantive is that the profile formation 12 also continues in the removal-flute runout 10, where it continues rectilinearly and parallelwise in relation to the drill-bit axis la. This can best be seen from the representation in Fig. 2.

Here, and preferably, the entire profile formation 12 of the removal flute 5 continues in the removal-flute runout 10. In principle, however, it can be provided that only a portion of the profile formation 12, for example only the middle portion or a lateral portion, is continued thus.

Preferably, it is provided that, on the back 6a of the helical web 6, a profile formation 13 continues spirally, and also continues in the helical-web runout 11, where, again, it continues rectilinearly and parallelwise in relation to the drill-bit axis la. The realization and continuation of the profile formation 13 of the helical web 6 can be provided as an alternative or in addition to the realization and continuation of the profile formation 12 of the removal flute 5.

Numerous advantageous variants are conceivable for the configuration of the profile formations 12, 13 in the removal flute 5 and on the back 6a of the helical web 6, respectively, which variants can be applied, largely independently of one another, on the removal flute 5, on the one hand, and on the helical web 6, on the other hand .

In order principally to improve the conveyance of drilling swarf by means of the profile formation 12, 13, it is preferably provided that the profile formation 12, 13 constitutes at least one supplementary web, supplementary flute, supplementary edge or the like, which then in each case extend spirally in the removal flute 5 or on the back 6a of the helical web 6, or rectilinearly in the removal-flute runout 10 or in the helical-web runout 11.

Depending on design-related parameters, the at least one supplementary web and/or the at least one supplementary flute can be configured with a rectangular, curved, in particular round, or tapered cross-section. Other configurations are conceivable. In the case of the exemplary embodiment that is represented, and to that extent preferred, the profile formation 12 of the removal flute 5 constitutes a plurality of supplementary webs 12a and supplementary flutes 12b that are next to one another, in this case directly next to one another, and that have a curved cross-section. In principle, it is also conceivable for the profile formation 12, 13 to constitute supplementary edges or the like that are next to one another. Likewise, a combination of supplementary webs, supplementary flutes and supplementary edges can be advantageous .

Here, the profile formation 12 is of an undulate configuration overall. In principle, such an undulate configuration can also be used for the profile formation 13 on the back 6a of the helical web 6. A serrated or sawtooth configuration is also conceivable in both cases . Here, and preferably, the profile formation 13 on the back 6a of the helical web 6 is composed of two entirely differing sub-profiles. Here, the profile formation 13 constitutes two flat webs 13a, which enclose a flute 13b.

The profile formations 12, 13 of the removal-flute runout 10 and of the helical-web runout 11 preferably continue over the respective, entire axial length thereof. Here, and preferably, this length also corresponds to the axial length of the head portion 7. Quite generally, the respective profile formation 12, 13 advantageously continues as far as the axial end of the head portion 7. In principle, however, it can also be provided that the respective profile formation extends over only a portion of the axial length of the head portion 7.

Particularly advantageous in the case of the solution according to the proposal is the fact that particularly simple production is possible. This is because, in a particularly preferred configuration, it is provided that the helical portion 4 and the head portion 7, including the respective profile formation 12, 13, is or are formed in an extrusion process. In principle, it can also be provided that only one of the two abovementioned helical portions is formed in an extrusion process. The above method for production of a rock drill bit also constitutes subject-matter of a further teaching, which is of importance in its own right.

According to this further teaching, the drill-bit shank is formed, by means of extrusion, from a cylindrical blank. In this case, as indicated above, a cylindrical blank is pressed axially into a die by means of a punch . What is substantive is that the head portion 7, including the profile formation 12, 13, is formed in a single extrusion cycle. Alternatively or additionally it can be provided that the helical portion 4, including the profile formation 12, 13, is formed in a single extrusion cycle.

Advantageous in the case of the proposed method is the fact that the, in this case, box-type structure of the head portion 7 can be realized simultaneously with the profile formation 12, 13, in a single extrusion cycle. With regard to the helical portion 4, it is advantageous that the removal flute 5 and the helical web 6 can be formed together with the profile formation 12, 13 in a single extrusion cycle.

Reference has already been made above to the fact that further processing steps can be provided for realization of the slot-type receiver 8 and/or of the insertion end 6.