The invention relates to a method for producing a drill bit, in particular a masonry drill bit, according to the preamble of claim 1 and to a drill bit produced according to this method according to the preamble of claim 10.

The drill bit in question can be designed for all possible fields of application. The main focus here is on the design of the drill bit as a masonry drill bit, which is to be understood in a non-restrictive manner.

Modern drill bits are provided with a drill bit shank which has an insertion section, a helical section axially adjoining the insertion section and a head section axially adjoining the helical section. The head section is provided with a groove-like connecting recess for the insert element or attachment having at least one cutting edge. The insert element or attachment is regularly a carbide element which has a cutting edge design tailored to the respective application. A known drill bit (WO 08/095716 A2) shows different variants of insert elements which are each in engagement with the drill bit shank in a positive- locking manner via the connecting recess. With the increasing complexity and thus extent of the insert elements or attachments, a challenge when designing drill bits is to provide, with the limited volume of the head section, sufficient support of the insert element or attachment.

The known drill bit (DE 199 15 305 C2), on which the invention is based, shows a head section which has a radial cross-sectional thickening relative to the helical section. With the additional material volume, obtained by the cross-sectional thickening, in the edge region of the head section, sufficient support of the insert element or attachment is ensured in most cases. A disadvantage with the known drill bit is the fact that the production of the cross-sectional thickening in the head section is always associated with an additional production step, for example with separate upsetting of the head section. This leads to increased expenditure of time and increased costs.

The problem addressed by the invention is to specify a method for producing a drill bit having a radial cross- sectional thickening in the head section, said method being optimized from the point of view of time and costs . The above problem is solved in a method according to the preamble of claim 1 by the features of the characterizing part of claim 1.

The basic idea that the incorporation of the groove- like connecting recess into the head section can be used in order to produce the desired radial cross- sectional thickening in the head section is essential.

In particular, it is proposed that the connecting recess be incorporated into the shank by forming, in particular by extrusion, to be precise in such a way that at least a portion of the cross-sectional thickening is produced at the same time by the resulting material displacement.

It has been recognized that the incorporation of the connecting recess by forming, in particular by extrusion, causes, at any rate, an outwardly acting, that is to say radially acting, material displacement. According to the proposal, this material displacement is used in order to produce the cross-sectional thickening . Owing to the fact that the incorporation, which is necessary anyway, of the connecting recess into the drill bit shank is used for allowing at least a portion of the cross-sectional thickening to be produced, significant time and cost advantages can be achieved with the method according to the proposal.

In the preferred configuration according to claim 2, a ram having a substantially web-like negative shape is pressed axially into the head section for incorporating the connecting recess. Owing to the fact that the production of the cross-sectional thickening is permitted at the same time, the loading of the ram is comparatively low, which ensures a long service life of the ram.

In the especially preferred configuration according to claim 3, when incorporating the connecting recess, the drill bit shank is inserted into a die having lateral forming jaws. Any desired forms of cross-sectional thickening can thus be set within a desired range.

With the further preferred configuration according to claim 8, it is proposed that the head section be upset at the same time as the connecting recess is incorporated. This can be appropriate if the incorporation of the connecting recess is insufficient for producing the desired cross-sectional thickening. According to a further teaching, to which independent significance is likewise attached, a drill bit which has been produced by the above method is claimed. Reference may be made to all the explanations which are suitable for describing such a drill bit.

The invention is explained in more detail below with reference to a drawing which shows merely one exemplary embodiment and in which: fig. 1 shows a drill bit according to the proposal in a schematic, perspective view, fig. 2 shows the drill bit according to fig. 1 in view

II, fig. 3 shows the drill bit according to fig. 1 in view

III, and fig. 4 shows the method step for incorporating the connecting recess while at the same time producing the cross-sectional thickening, in an entirely schematic illustration.

The method according to the proposal serves to produce a drill bit which can be designed for all conceivable applications. The exemplary embodiment shown, and in this respect the preferred exemplary embodiment, concerns a masonry drill bit, which is to be understood in a non-restrictive manner.

The drill bit shown in figs 1 and 2 is provided in a conventional manner with a drill bit shank 1. The drill bit shank 1 has an insertion section 2 having an insertion profile 3. Axially adjoining the insertion section 2 is a helical section 4 having two disposal flutes 5 and two helical webs 6. In principle, the number of disposal flutes 5 and helical webs 6 can vary.

Axially adjoining the helical section 4 is a head section 7 having a groove-like connecting recess 8 for the positive-locking engagement with an insert element 9. The insert element 9 is shown in figs 1 and 2 by broken lines. It can be seen from the illustration that the insert element 9 here is a plate-shaped insert element 9. In other variants (not shown), the insert element 9 is an object which is star-shaped in cross section and which has at least three arms. In a further variant, the insert element 9 is of substantially trapezoidal configuration in cross section, the insert element 9 preferably extending over the entire cross-sectional width of the head section 7. An attachment can also be provided instead of the insert element 9, said attachment being in engagement with the groove-like connecting recess 8 in the fitted state.

The configuration of the connecting recess 8 results from the configuration of the insert element or attachment 9. Accordingly, the connecting recess 8, as mentioned above, can be configured in cross section substantially in a star shape, trapezoidal shape or the like. Walls 10, 11 having a wall thickness which depends on the configuration of the connecting recess 8 remain at the respective edges of the groove-shaped connecting recess 8. In order to achieve the increase in the wall thickness, provision is made for the head section 7 to have a radial cross-sectional thickening 12.

The expression "radial cross-sectional thickening" in this case means that the cross section of the head section 7 increases at least partly outward, that is to say in the radial direction, over a region of the head section 7, in particular from the axially lower end of the head section 7 toward the drill point.

Here, the cross-sectional thickening 12 need not extend over the entire outer contour of the head section 7. In other words, the cross-sectional thickening 12 need not be the same or need not be present at all in every radial direction, as will be explained. The cross- sectional thickening 12 can be seen especially clearly in fig. 2 as a result of the transition region 12a, shown there, from a non-thickened region (on the right in fig. 2) into a thickened region (on the left in fig. 2) .

It may be pointed out that the specifications "radial" and "axial" are always related here to the drill bit axis 13. Accordingly, the "cross section" here is always a section at right angles to the drill bit axis 13.

A method step for the purposes of producing the drill bit in which the connecting recess 8 and the cross- sectional thickening 12 are incorporated into the head section 7 is now essential. According to the proposal, the connecting recess 8 is incorporated into the drill bit shank 1 by forming, here preferably by extrusion, in such a way that at least a portion of the cross- sectional thickening 12, preferably the complete cross- sectional thickening 12, is produced at the same time by the resulting material displacement. It can be seen from the illustration according to fig. 2 that, when the connecting recess 8 is being incorporated by extrusion, a material displacement takes place anyway in the radial direction, and according to the proposal it is this very material displacement that is used for producing the cross-sectional thickening 12. The essential method step of the method according to the proposal is shown schematically in fig. 4. To incorporate the connecting recess 8, a ram 14 is pressed here axially into the head section 7, the ram 14 here preferably having a substantially web-like negative shape 15 relative to the connecting recess 8. The pressing direction of the ram 14 is designed by reference numeral 14a in fig. 4. It can be seen from the illustration in fig. 4 that, when incorporating the connecting recess 8, the drill bit shank 1 is preferably inserted into a die 16 having lateral forming jaws 17 with respect to the drill bit axis 13. The form of the cross-sectional thickening 12 is in this case determined by the shapes of the lateral forming jaws 17. In particular, provision can be made for the outer contour of the cross-sectional thickening 12 to be provided with a quite particular profile which can be determined by the shapes of the lateral forming jaws 17. In this case, the drill bit shown in fig. 1 involves, for example, a type of wave profile.

For the configuration of the connecting recess 8, numerous variants are conceivable which substantially depend on the configuration of the insert element or attachment 9. Here, the connecting recess 8 is of substantially elongated configuration in cross section.

The elongated connecting recess 8 runs here transversely to the drill bit axis 13 and preferably through the drill bit axis 13. This can best be seen from the illustration in fig. 3.

In the drill bit shown, the fact that the head section 7 is of substantially rectangular configuration in cross section is also of interest, the longitudinal sides of the rectangular shape running substantially along the connecting recess 8. Here, the connecting recess 8, in cross section, preferably runs diagonally through the rectangular shape of the head section 7. This is appropriate if it is considered that the drill bit has a preferred direction of rotation (counterclockwise in fig. 3), which requires a correspondingly asymmetrical support of the insert element 9.

It has already been pointed out that, with the method according to the proposal, largely any desired shape of the head section 7 can be set. In the exemplary embodiment shown, and in this respect in the preferred exemplary, the cross-sectional thickening 12 at any rate extends axially over the substantial portion of the head section 7. However, it is also conceivable for the cross-sectional thickening 12 to extend only over a small portion of the head section 7 in which material is precisely reguired for support. The degree of the cross-sectional thickening 12 over the axial extent thereof is preferably substantially constant. In principle, however, the degree of the cross-sectional thickening over the axial extent thereof can also increase or decrease, thereby resulting, at least in sections, in a substantially conical configuration of the head section 7.

In principle, provision may also be made for the cross- sectional thickening 12 to extend over the entire cross-sectional outer contour of the head section 7. Here, however, provision is preferably made for the cross-sectional thickening 12 to extend solely over a region of the cross-sectional outer contour. Furthermore, the cross-sectional thickening 12 preferably extends solely over the region of the cross- sectional outer contour which runs substantially along the connecting recess 8. This, too, can be set by a corresponding configuration of the forming jaws 17. The fact that a disposal flute 5, here all the disposal flutes 5, continues, or continue, in a corresponding disposal-flute runout 5a in the head section 7 can be seen when figs 1 to 3 are viewed together. Furthermore, a helical web 6, here all the helical webs 6, preferably continues, or continue, in a corresponding helical-web runout 6a.

Here, the cross-sectional thickening 12 preferably extends solely over the disposal-flute runout 5a and not over the helical-web runout 6a. This ensures that the cross-sectional thickening 12 is not accompanied by an increase in the maximum diameter of the head section 7 beyond the maximum diameter of the helical section 4. Fig. 3 accordingly shows that the diameter of the head section 7 in the region of the helical-web runouts 6a (maximum diameter of the head section 7) corresponds to the diameter of the helical section 4 in the region of the helical webs 6 (maximum diameter of the helical section 4) and does not project beyond that. This is of interest independently of the above, practical implementation, since an undesirable braking effect of the head section 7 on account of a radial projection relative to the helical section 4 is avoided.

Given a suitable configuration of the ram 14, it is also conceivable for the head section 7 to be upset at the same time as the connecting recess 8 is incorporated. This is in particular advantageous if the material displacement associated with the incorporation of the connecting recess 8 should be insufficient for producing the entire cross-sectional thickening 12 in the head section 7.

The above explanations of the method according to the proposal are based on the assumption that the head section 7 is of substantially rectangular configuration in cross section both before the connecting recess 8 is incorporated and after the connecting recess 8 is incorporated. This can be brought about, for example, by a preceding forming step by extrusion or the like. However, it is also conceivable for the rectangular shape not to be incorporated until after the connecting recess 8 is incorporated into the head section 7. Numerous variants are conceivable here.

In very general terms, at least one method step for processing the head section 7 and the drill bit shank 1 otherwise proceeds or can proceed and/or follows or can follow the incorporation of the connecting recess 8. Apart from that, the shaping of the drill bit shank 1, in particular of the helical section 4 with disposal flutes 5 and helical webs 6, can be realized with different methods. In addition to grinding and milling, a forming method, in particular extrusion, can also be used here.

In an especially preferred configuration, the shaping of the helical section 4 and the shaping of the head section 7 are effected in a single progressive die.

According to a further teaching, to which independent significance is likewise attached, the drill bit produced by the method according to the proposal is claimed as such. Reference may be made to the above explanations, provided they are suitable for describing the drill bit according to the proposal.