US20140216824A1

US20140216824A1 - Tool holder, and chisel support and drilling bit for a drill head

Info

Publication number: US20140216824A1
Application number: US14/131,640
Authority: US
Inventors: Karl Kammerer; Wolfgang Essig
Original assignee: Betek GmbH and Co KG
Current assignee: Betek GmbH and Co KG
Priority date: 2011-07-08
Filing date: 2012-06-28
Publication date: 2014-08-07
Also published as: EP2729653A2; DE102011051684A1; WO2013007528A2; WO2013007528A3; DE202011051653U1; AU2012283286A1

Abstract

A drill head including a tool holder, chisel supports mounted thereon and drill bits. According to this invention, the chisel supports can be separated from the tool holder.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to a tool holder for a drill head with a fastening shank through which a mud channel passes and with a support structure fastened directly or indirectly to the fastening shank.
This invention also relates to a drill bit support for a drill head, with a support head on which a bearing section of a drill bit that can be fastened in rotary fashion.
This invention also relates to a drill bit for rotary attachment to a drill bit support.
2. Discussion of Related Art
Drill heads are used to dig drilling holes in the ground for construction projects. To do so, the drill heads are fastened at one end to a drill pipe. The rotation and the advancing motion of a drive unit are transferred to the drill head by the drill pipe.
For example, horizontal drilling machines are known, which are used to produce a relatively horizontal bore in the ground. This is done to drive the drill head under roads, buildings, or the like. Usually, the drill heads have a tool holder that holds drill bits, which are supported in sockets in rotary fashion. When the drill head is driven through the ground, the drill bits roll against the material to be removed and break it free. This causes it to fragment so that it can be flushed away with a mud emulsion. The mud emulsion is supplied to the drill heads via the drill pipe. The drill heads are subject to wear and thus must be regularly replaced.

SUMMARY OF THE INVENTION

One object of this invention is to provide a drill bit support and a drill bit, which are designed so that they are optimized with regard to wear.
This object and others of this invention relating to the tool holder are attained if the support structure has tool sockets offset from one another in the circumference direction for accommodating drill bit supports in a replaceable fashion.
According to this invention, there is a wear system in which the tool holder has an interface for the replaceable coupling of the drill bit support. Consequently, the tool holders and the drill bit supports can be replaced independently of one another in accordance with their wear state. This achieves an optimization of the service life of the individual tool components.
According to one embodiment of this invention, it is possible for the tool sockets to be embodied or shaped in the form of insertion sockets. Thus, the drill bit supports can be easily changed and precisely positioned, even in the rough conditions of worksite operations and in installation situations with limited accessibility.
In this connection, it is particularly advantageous if the tool sockets have an insertion opening, which opens in the direction oriented away from the fastening shank or in a radially outward direction. Thus, the drill bit supports can be inserted into the insertion sockets from the front side or the rear side of the drill head. Alternatively, the insertion socket can also be embodied or shaped in the form of a guide projection onto which the drill bit support can be slid.
A tool holder according to this invention can be embodied or formed so that in the region of the tool socket, a fastening receptacle, in particular a screw receptacle, is provided, which opens in the direction toward the fastening shank and is accessible from there. Thus, the screw receptacle is oriented so that the screw head of a fastening screw is inserted into the screw receptacle and is favorably positioned with regard to wear. In particular, it is then not exposed to the abrasive wear action.
A possibility for exact positioning of the drill bit supports is provided in a simple way if the tool sockets have two guide grooves or guides situated on opposite sides from each other.
Thus, a favorable centering is achieved if the guide grooves are laterally delimited by two flanks, which extend in the longitudinal direction of the groove and are oriented at an angle relative to each other. This design is also load-optimized. The wall sections of the tool sockets that form the grooves become thicker in the direction toward the bottom of the groove and thus have a large load cross-section at the location in which the highest loads occur.
Preferably, the tool sockets each at least partially comprises two guide projections and outlet channels formed between the guide projections of adjacent tool sockets. The rock material that is removed with the supplied emulsion can be conveyed away via the outlet channels.
One object of this invention relating to the drill bit support is achieved if an insertion lug is directly or indirectly coupled to the support head of the drill bit support. With this insertion lug, the drill bit support can be inserted into a correspondingly embodied tool socket of the tool holder. It can then be replaced independently of the tool holder, each as a function of its individual wear state. This achieves a wear-optimized design. With its insertion lug, the drill bit support can be quickly and simply attached to the tool holder and detached from it again.
The insertion lug can have guide pieces on two opposing sides. With these guide pieces, it can be inserted, for example, into grooves of the tool holder, in order to thus achieve a reliable and exact positioning.
For a load-optimized design, the guide pieces can have two guide surfaces that are oriented at an angle relative to each other and are connected to each other via a connecting section. The guide pieces widen out starting from their free ends and thus have their maximum cross-section in the region in which they connect to the drill bit support and therefore have a load-optimized design.
In one embodiment of this invention, the insertion lug has a support lug at its free end and this support lug produces an additional stable attachment.
For example, it is also possible for the support lug to transition into the guide pieces in a way that results in an easy-to-produce geometry.
A drill bit support according to this invention can also be embodied so that the insertion lug is delimited by a convex inner surface and/or a convex outer surface. In the region of the convex inner surface, the drill bit support can correlate with a correspondingly concave recess of the tool holder. The matching convex/concave regions in the vicinity of the inner surface produce an interface, which, like a key in a lock, promotes the association of the correct drill bit support with a tool holder. The convex outer surface of the drill bit support reduces the number of possible weak points of the bore wall and thus contributes to a wear-optimized layout of the tool design. The convex shape also achieves a thickening of the insertion lug cross-section and thus a greater stability.
A drill bit support according to this invention can have a support head that supports a bearing section and labyrinth seal parts are positioned or situated in the transition region from the support head to the bearing section. These labyrinth seal parts can be put together with corresponding labyrinth seal parts of a drill bit in order to thus produce a labyrinth seal. This labyrinth seal counteracts the penetration of rock material and thus protects the bearing section and a bearing contained therein.
A drill bit can be simply affixed to a drill bit support so that the bearing section has a circumferential groove for accommodating a clamping element. The clamping element can then be connected to the drill head with form-locking engagement and/or frictional, nonpositive engagement.
In one embodiment according to this invention, the central longitudinal axis formed by the bearing section extends at an angle in the range between 30° and 90° in relation to the outer surface. This achieves an optimization of the bearing pressure on the bearing between the drill bit and the tool support. It is advantageous for this angular range to lie between 50° and 70°. This also produces an outer surface of the drilling tool that is functional and easy to shape.
One object of this invention is also achieved with a drill bit for coupling to a drill bit support in rotary fashion. The drill bit has an outer surface with hard material elements. The drill bit also has a bearing receptacle. In the region of the bearing receptacle, the drill bit according to this invention has labyrinth seal parts, which can be put together with labyrinth seal parts of the drill bit support to form a labyrinth seal. This labyrinth seal counteracts the penetration of rock material, thus using simple means to effectively protect the bearing receptacle from wearing action.
In order to also maintain a reliable position-fixing relative to the drill bit support, even when there are abrupt and uneven loads on the drill bit, it is possible according to this invention for the bearing receptacle to have an end surface that supports a support element of hard material. This support element can cooperate with a counterpart support element or a counterpart surface of the drill bit support.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is explained in greater detail below in view of an exemplary embodiment shown in the drawings, wherein:

FIG. 1 is a perspective side view of a drill head with a tool holder and, mounted thereon, drill bit supports with drill bits;

FIG. 2 is a partial section view taken through the drill head according to FIG. 1;

FIG. 3 is a perspective front view of a drill bit support;

FIG. 4 is a perspective front view of a drill bit support with drill bits mounted thereon;

FIG. 5 is a sectional detail view taken along line V-V in FIG. 2;

FIG. 6 is a perspective side view of another embodiment of a drill head with a tool holder and, mounted thereon, drill bit supports with drill bits;

FIG. 7 is a partial section view taken through the drill head according to FIG. 6;

FIG. 8 is a perspective front view of a drill bit support;

FIG. 9 is a sectional detail view taken along line IX-IX in FIG. 7;

FIG. 10 is a full section view taken through the drill bit support according to FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a drill head with a tool holder 10 having a base part as a support structure 12. The support structure 12 has a downward-pointing fastening shank 11 integrally formed onto it. The fastening shank 11 has a conical external thread. The support structure 12 has three tool sockets 13, which protrude from the outside of the support structure 12 and are offset from one another by 120° and are embodied in the form of pockets.
FIG. 5 shows one embodiment of the tool sockets 13 in greater detail. As shown, each tool socket 13 has two guide projections 13.1 on the outside. The guide projections 13.1 each is provided with or has a respective guide groove 13.2, the guide grooves 13.2 of a tool socket 13 are situated on opposite sides from each other. The guide grooves 13.2 are delimited laterally by flanks 13.3 that are oriented at an angle with respect to each other, preferably in the range between 80° and 100°. This angular range ensures a reliable and jam-free function of the guide. The two guide projections 13.1 form convex surfaces on the outside, which lie along a pitch circle, as shown in FIG. 5.
FIG. 1 shows that in the region of the fastening shank 11, the guide projections 13.1 are connected by a transition section that is provided with or has a screw receptacle 12.1, as shown in FIG. 2. The screw receptacle 12.1 serves to accommodate a fastening screw 12.2. The screw receptacle 12.1 is let into the support structure 12 so that it feeds into the tool socket 13 and so that it is oriented toward the free end of the fastening shank 11. In this way, the head of the fastening screw 12.2 is accommodated in a protected way, on the side oriented away from the advancing direction of the drill head. The support structure 12, as shown in FIG. 2, has a mud channel 15 passing through it. The mud channel 15 feeds into a nozzle. The nozzle 15.1 transitions into a channel chamber 14, which feeds into the outlet channels 14.1. The outlet channels 14.1 are each situated between the guide projections 13.1 of adjacent tool sockets 13.
Drill bit supports 20 can be mounted in the tool sockets 13. The design of the drill bit support 20 is shown in greater detail in FIG. 3. As shown, the drill bit support 20 has an insertion lug 21 that terminates with an inner surface 24 and on the outside, with a convex outer surface 25. Rib-like guide pieces 22 are integrally formed onto the sides of the insertion lug 21. The guide pieces 22 have two guide surfaces 22.1 oriented at an angle with respect to each other so that the guide pieces 22 taper from their connecting region to the insertion lug 21 toward their free end. The inclination angle is selected in accordance with the angle between the flanks 13.3. The guide surfaces 22.1 transition into one another via a connecting section 22.2. In the region of or near the free end of the insertion lug 21, a support lug 23 is formed, which is embodied as a transition section and, like the guide pieces 22, is embodied as rib-like. The support lug 23 transitions flush into the guide pieces 22 and thus has the same cross-sectional geometry. Consequently, it has guide surfaces 23.1 inclined in relation to each other and in turn connected to each other by a connecting section.
The insertion lug 21 has a support head 26 with a bearing section 26.3 formed integrally onto it. In the transition region to the bearing section 26.3, the support head 26 has an annular shoulder 26.1 extending around it, which is adjoined by a circumferential groove 26.2. The shoulder 26.1 and the groove 26.2 constitute or form labyrinth seal parts. The cylindrical bearing section 26.1 is first adjoined by a concave transition 26.4 in order to adapt its size to a reduced-diameter connector piece at the end. A circumferential groove 26.5 is incorporated into the connector piece. The bearing section 26.3 terminates at its end with an end surface 26.7. As shown in FIG. 2, the end surface 26.7 has a recess incorporated into it, into which a support element 26.6, composed of or comprised of a hard material such as a hard metal, is soldered, glued, or press-fitted. FIG. 2 also shows that an annular clamping element 29.1 in the form of a round wire snap ring is snapped into the circumferential groove 26.2.
FIGS. 2 and 4 show that a drill bit 30 can be connected to the drill bit support 20. The drill bit 30 has an outer surface 31 with at least one circumferential groove 32, 33. Hard material elements 34, in particular hard metal elements, can be soldered into holes on the outer surface 31. The drill bit 30 has an internal bearing receptacle 37 that is embodied or shaped in the form of a hole in the drill bit 30. The bearing receptacle 37 transitions via a diameter reduction into a blind hole bore that is equipped with or has a groove 38. The blind hole bore terminates with an end surface, in which a recess for a support element 39 is provided. The support element 39 can be composed of or comprised of a hard material such as hard metal. In the end region of the bearing receptacle 37, the drill bit 30 is provided with or has a circumferential groove 35 and an adjoining circumferential shoulder 36. The groove 35 and the shoulder 36 are labyrinth seal parts. To mount the drill bit 30 on the drill bit support 20, a bearing 29 is inserted into the bearing receptacle 37 of the drill bit 30 and slid onto the bearing section 26.3 of the drill bit support 20. The bearing 29 in this embodiment is formed as a needle bearing, making it possible to achieve a small overall height.
As shown in FIG. 2, a radial shaft sealing ring or a similar circumferential seal 28 is also inserted in the region between the bearing receptacle 37 and the bearing section 26.3. In the inserted state, the circumferential shoulder 36 of the drill bit 30 protrudes into the circumferential groove 26.2 of the drill bit support 20. In a similar way, the circumferential shoulder 26.1 of the drill bit support 20 protrudes into the circumferential groove 35 of the drill bit 30, so that a labyrinth seal is formed. Consequently, the circumferential shoulders 36 and 26.1 and the grooves 26.1 and 35 constitute formed-on seal profiles or labyrinth profiles. Adjacent to the labyrinth seal, the seal 28 seals the bearing receptacle 37 so that the labyrinth seal and the seal 28, effectively protect the bearing 29 from the penetration of rock material and mud emulsion. This prevents premature failure of the bearing 29. In order to affix the drill bit 30 to the drill bit support 20, the clamping element 29.1 simultaneously engages in the grooves 26.5 and 38 of both the drill bit support 20 and the drill bit 30. This produces a form-locked engagement between these components. In addition, the drill bit 30 is supported with its support element 39 on the support element 26.6 of the drill bit support 20. During assembly of the drill bit 30, the clamping element 29.1 slides between the bearing receptacle 37 and the region of the bore that accommodates the groove 38. As a result, the clamping element 29.1 is compressed radially inward into the groove 26.2 and its diameter is reduced. The clamping element 29.1 can then snap into the groove 38 so that a form-locked connection is achieved.
The tool combination composed of the drill bit support 20 and drill bit 30 can be inserted into a tool socket 13 of the tool holder 10. For this purpose, the insertion lug 21 is slid into the tool socket 13, which is embodied or shaped in the form of an insertion socket. In the process of this, the guide surfaces 22.1 of the guide pieces 22 slide along the flanks 13.3 of the guide grooves 13.2. The insertion movement of the drill bit support 20 is limited by the support surfaces 23.2 that come to rest against corresponding counterpart surfaces of the tool sockets 13. Then the fastening screw 12.2 can be inserted through the screw receptacle 12.1 and screwed into a threaded hole 21.1 of the insertion lug 21. FIG. 5 shows the joined pair of the insertion lug 21 and the tool socket 13. As this drawing shows, the guide surfaces 22.1 rest against the flanks 13.3. The convex outer surface 25 of the insertion lug 21 transitions flush into the convex outer sections of the guide projections 13.1, thus avoiding an abrupt cross-sectional change in favor of a tool design that is optimized in terms of wear.
As shown in FIG. 5, the guide projections 13.1 are spaced farther apart from the outer surface 25 than from the inner surface 24, which is illustrated in FIG. 5 with the dimensions a and b, where a is smaller than b. Correspondingly, there is a certain wear volume available in the region of or near the outer surface of the insertion lug 21, which can wear down during use of the tool without significantly influencing the fastening region between the insertion lug 21 and the tool socket 13. The cross-section of the insertion lug 21 is thus asymmetrical to its central transverse plane Q extending in the longitudinal direction of the insertion lug. Consequently, the tool sockets 13 are also asymmetrical.
After all three drill bit supports 20 are fastened to the tool holder 10, the drill head is ready for use. During engagement of the tool, the tool holder 10 and with it, the drill bit support 20, rotates around the rotation axis R. As this occurs, the drill bits 30 come into engagement with the material to be removed. Because of the rotating motion, the drill bits 30 roll in the drilling hole and the hard material elements 34 cut into the material to be removed. An emulsion is supplied via the mud channel 15, which is sprayed out in the region of the nozzle 15.1. The emulsion flushes out the removed and crushed material, where the emulsion then flows out via the outlet channels 14.1. The drill bits 30 are designed differently from one another in the region of or near their outer surface 31 so that the rotating rows of hard material elements 34 of one drill bit 30 can travel in a respective groove 32, 33 of the adjacent drill bit 30.
During engagement of the tool, the above-described tool combination experiences wear. Consequently, the drill bit 30, the drill bit support 20, and the tool holder 10 undergo continuous wear. Depending on the wear state, according to this invention, the tool holder 10, the drill bit support 20, and the drill bits 30 can each be individually replaced. For tool replacement, the drill head is detached from the drilling lance. To accomplish this, the screw connection between the fastening shank 11 and the drilling lance is disconnected. The drill bit support 20 can then be detached by simply unscrewing the fastening screw 12.2 from the tool holder 10. The drill bit 30 can be pressed out from the drill bit support 20. In the course of this, the clamping element 29.1, due to the geometry of the grooves 26.5 and 35, is deflected radially inward and thus disengages from the groove 35 of the drill bit 30. The drill bit 30 can then be slid off of the drill bit support 20.
FIGS. 6 through 10 show another embodiment of an apparatus according to this invention. In it, parts that are the same have the same reference numerals so that in order to avoid repetitions, reference can be made to the descriptions above.
FIG. 6 shows a drill head with a tool holder 10, having the base part as a support structure 12. The support structure 12 has a downward-pointing fastening shank 11 integrally formed onto it. The fastening shank 11 has a conical external thread. The support structure 12 is equipped with or has three tool sockets 13, which protrude from the outside of the support structure 12 offset from one another by 120°.
FIG. 9 clearly shows the tool socket 13. As the drawing shows, the support structure 12 has one guide projection 13.1 for each tool socket 13. Each guide projection 13.1 has longitudinal guides in the form of prism guides on opposite sides. The two prism guides are each formed by two guide surfaces 22.1 oriented at an angle relative to each other. An angle in the range between 45° and 75° between the guide surfaces 22.1 can be advantageous. This makes it possible to ensure a simple assembly in the rough conditions of worksite operations. In addition, this embodiment of the guide projections 13.1 does not have a tendency to jam. The guide surfaces 22.1 extend in the longitudinal direction of the guides, as shown in FIG. 8 and FIG. 10. The drill bit supports 20 can be fastened to the tool sockets 13.
As shown in FIGS. 8 and 10, the tool supports 20 have a tool head 26, which is integrally joined to an insertion lug 21. On a radial inside, the insertion lug 21 forms a recessed fastening receptacle. In this case, the fastening receptacle is open toward the radial inside and in the downward direction, as shown in FIG. 3. The fastening receptacle is delimited by flanks 13.3 that are oriented relative to each other in prism fashion. The flanks 13.3 are oriented relative to each other at the same angle as the guide surfaces 22.1 so that the flanks 13.3 and the guide surfaces 22.1 form sliding guides.
As shown in FIG. 9, the flanks 13.3 are part of guide pieces 22, that delimit the fastening receptacle toward the front and the back in the advancing direction V. The guide pieces 22 each forms a respective shoulder 22.2, which supports one of the flanks 13.3 and which engages in a form-locked way behind the guide projection 13.1. As a result, the drill bit support 20 is not offset in the radial direction. Now, the drill bit support 20 can only be slid in the guidance direction. The two guide pieces 22 are connected to each other by a wall section 21.2. In the attachment region to the tool holder 12, the guide pieces 22 terminate at inner surfaces 24 that are flush with each other and are situated or positioned in one plane. The outside of the tool support 20 is defined by an outer surface 25 which is divided into a plurality of partial surfaces. In the advancing direction, the outer surface 25 has a first surface section 25.1 which transitions at an angle into a deflecting surface 25.2. The deflecting surface 25.2 is tilted in the opposite direction from the advancing direction V, as shown in FIGS. 8 and 9. The deflecting surface 25.2 transitions via a clearing edge 25.6 into a side surface 25.3. The clearing edge 25.6 extends essentially in the direction of the central longitudinal axis of the drill bit support 20. In the opposite direction from the advancing direction V, the side surface 25.3 transitions at the back into an open surface 25.4. Between the side surface 25.3 and the open surface 25.4 there is also an edge region. The open surface 25.4 finally ends at a surface section 25.5, which like the surface section 25.1, transitions into the inner surface 24.
As shown in FIG. 8 and in FIG. 10, a fastening receptacle 21.3 in the form of a bore that passes through the two guide pieces 22 is located in the region of or near the insertion lug 21. In order to mount the drill bit support 20 on the tool holder 10, the flanks 13.3 of the drill bit support 20 in the region of or near its open underside are placed onto the guide surfaces 22.1. Then, the insertion lug 21 of the drill bit support 20 is slid onto the guide projection 13.1 of the tool socket 13 in the guide direction. The sliding-on movement is limited by a stop 21.4 (see FIG. 10). The stop 21.4 here is likewise embodied or shaped in the form of an internal prism in order to produce a form-locked engagement. This cooperates with corresponding prism surfaces of the guide projection 13.1. In the installed state, the fastening receptacle 21.3 is flush with a corresponding bore receptacle in the guide projection 13.1. Then a corresponding fastening element such as a hollow dowel pin can be slid through the flush fastening receptacles 21.3 of the insertion lug 21 and of the guide projection 13.1. This prevents an offset of the tool support 20 relative to the tool holder 10 in the guidance direction.
As shown in FIG. 9, the guide piece 22 toward the front in the advancing direction V has a larger wear volume than the rear guide piece 22. FIG. 9 also shows that the structural height of the front guide piece 22 in the radial direction is greater than the structural height of the rear guide piece 22 (distance dimension d₂>d₁). Consequently, the clearing edge 25.6 lies on a different, namely larger, pitch circle or center of the circle on the rotation axis R than the edge region between the open surface 25.4 and the side surface 25.3. The side surface 25.3 thus has a wear-optimized geometry that decreases radially inward in the opposite direction from the advancing direction V, as shown in FIG. 9.
The insertion lug 21 supports a tool head 26, which has a bearing section 26.3 integrally formed onto it.
The embodiment of the tool head 26 and drill bit 30 is selected to be similar or essentially identical to that of the embodiment according to FIGS. 1 through 5, so that reference can be made to the explanations above.

Claims

1. A tool holder (10) for a drill head with a fastening shank (11) having at least one mud channel (15) passing through or associated with the at least one mud channel (15) and having a support structure (12) fastened directly or indirectly to the fastening shank (11), the tool holder (10) comprising the support structure (12) having tool sockets (13) offset from one another in a circumference direction.

2. The tool holder (10) according to claim 1, wherein the tool sockets (13) are formed as insertion sockets.

3. The tool holder (10) according to claim 2, wherein the tool sockets (13) have an insertion opening which opens in a direction oriented away from the fastening shank (11) or in a radially outward direction and/or the tool socket (13) has a protruding guide region (13.1) with guide surfaces.

4. The tool holder (10) according to claim 3, wherein near the tool socket (13) a fastening receptacle (12.1) being a screw receptacle positioned which opens in a direction toward the fastening shank (11) and being accessible from the opening.

5. The tool holder (10) according to claim 4, wherein the tool sockets (13) have guide grooves (13.2) on opposite sides from each other.

6. The tool holder (10) according to claim 5, wherein the guide grooves (13.2) are each delimited by two flanks (13.3) which extend in a longitudinal direction of the groove.

7. The tool holder (10) according to claim 6, wherein the tool sockets (13) each at least partially comprises two guide projections (13.1), and outlet channels (14.1) are formed between the guide projections (13.1) of the adjacent tool sockets (13).

8. A drill bit support (20) for a drill head with a support head (26), on which a drill bit (30) can be fastened to a bearing section (26.3) in a rotary fashion, comprising an insertion lug (21) directly or indirectly coupled to the support head (26).

9. The drill bit support (20) according to claim 8, wherein the insertion lug (21) has guide pieces (22) on two opposite sides.

10. The drill bit support (20) according to claim 9, wherein the guide pieces (22) have two guide surfaces (22.1), and flanks (13.3) oriented at an angle relative to each other and connected to each other by a connecting section (22.2).

11. The drill bit support (20) according to claim 10, wherein the insertion lug (21) has a support lug (23) at a free end.

12. The drill bit support (20) according to claim 11, wherein the support lug (23) transitions into the guide pieces (22).

13. The drill bit support (20) according to claim 12, wherein the insertion lug (21) is delimited by a flat inner surface (24) and/or by a convex outer surface (25).

14. The drill bit support (20) according to claim 13, wherein the support head (26) supports a bearing section (26.3) and labyrinth seal parts are positioned in a transition region from the support head (26) to the bearing section (26.3).

15. The drill bit support (20) according to claim 14, wherein the bearing section (26.3) has a circumferential groove (26.5) for accommodating a clamping element (29.1).

16. The drill bit support (20) according to claim 15, wherein a central longitudinal axis (ML) formed by the bearing section (26.3) is oriented at an angle (a) in a range between 70° and 90° relative to the outer surface (25).

17. The drill bit support (20) according to claim 16, wherein the guide pieces (22) on the insertion lug (21) are asymmetrical relative to the central longitudinal plane (L) extending in the longitudinal direction of the insertion lug.

18. A drill bit (30) for a rotatable coupling to a drill bit support (20), having an outer surface (31) with hard material elements (34) and a bearing receptacle (37), the drill bit (30) comprising: near the bearing receptacle (37), a circumferential groove (38) accommodating a clamping element (29.1) adjustable between two clamping positions.

19. The drill bit (30) according to claim 18, wherein the labyrinth seal parts are positioned near the bearing receptacle (37).

20. The drill bit (30) according to claim 19, wherein the bearing receptacle (37) has an end surface that supports a support element (39) of a hard material.

21. The drill bit (30) according to claim 18 for mounting on a tool support (20) according to claim 8.

22. The tool holder (10) according to claim 1, wherein near the tool socket (13) a fastening receptacle (12.1) being a screw receptacle positioned which opens in a direction toward the fastening shank (11) and being accessible from the opening.

23. The tool holder (10) according to claim 1, wherein the tool sockets (13) have guide grooves (13.2) on opposite sides from each other.

24. The tool holder (10) according to claim 1, wherein the tool sockets (13) each at least partially comprises two guide projections (13.1), and outlet channels (14.1) are formed between the guide projections (13.1) of the adjacent tool sockets (13).

25. The drill bit support (20) according to claim 8, wherein the insertion lug (21) has a support lug (23) at a free end.

26. The drill bit support (20) according to claim 8, wherein the insertion lug (21) is delimited by a flat inner surface (24) and/or by a convex outer surface (25).

27. The drill bit support (20) according to claim 8, wherein the support head (26) supports a bearing section (26.3) and labyrinth seal parts are positioned in a transition region from the support head (26) to the bearing section (26.3).

28. The drill bit support (20) according to claim 8, wherein the bearing section (26.3) has a circumferential groove (26.5) for accommodating a clamping element (29.1).

29. The drill bit support (20) according to claim 13, wherein a central longitudinal axis (ML) formed by the bearing section (26.3) is oriented at an angle (a) in a range between 70° and 90° relative to the outer surface (25).

30. The drill bit support (20) according to claim 8, wherein the guide pieces (22) on the insertion lug (21) are asymmetrical relative to the central longitudinal plane (L) extending in the longitudinal direction of the insertion lug.

31. The drill bit (30) according to claim 18, wherein the bearing receptacle (37) has an end surface that supports a support element (39) of a hard material.