COMBINATION TOOL AS WELL AS DRILLS FOR SUCH A DRILLING/CHAMFERING TOOL

Abstract

The combination tool (2), in particular a drilling/chamfering tool, comprises a drill (6) extending in the longitudinal direction (4) with a clamping sleeve (8), which is designed to receive the drill (6) and fasten the drill (6) at a variable length and which has a holding seat (38) for a cutting insert (12). The drill (6) comprises a cutting region (22) provided with grooves (14), wherein the grooves (14) extend helically and are formed between two grooves (14) drill backs (18). At least one of the drill backs (18) is partially flattened to form an adjustment surface (16) for the cutting insert (12), wherein the adjustment surface (16) extends helically. As a result, a length adjustment over a large length range is made possible independently of the twist angle (γ).

Claims

1. A combination tool comprising a drill extending in a longitudinal direction along a rotational axis (R) and with a clamping sleeve, which is designed to receive the drill and fasten the drill with variable length and which has a holding seat for a cutting insert, wherein the drill has a cutting region provided with grooves and the grooves extend helically at a twist angle γ, wherein drill backs extending helically with a curved peripheral surface are formed between two grooves, wherein at least one of the drill backs is partially flattened to form an adjustment surface, wherein the adjustment surface extends helically.

2. The combination tool according to claim 1, wherein the adjustment surface extends at the same twist angle (γ) as the grooves.

3. The combination tool according to claim 1, wherein the adjustment surface tapers off into one of the grooves.

4. The combination tool according to claim 1, wherein the drill back covers a predetermined angle range (β) between the grooves, wherein the adjustment surface covers at least one quarter of the predetermined angle range (β1).

5. The combination tool (2) according to claim 1, wherein the adjustment surface encloses with the curved peripheral surface an angle (α), in the range from 80° to 160°, when viewed in cross-section.

6. The combination tool according to claim 1, wherein the adjustment surface extends in the longitudinal direction and comprises a front end, where the adjustment surface transitions via a step into the curved peripheral surface.

7. The combination tool (2) according to claim 1, wherein the adjustment surface extends in the longitudinal direction over a length that is a multiple of a nominal diameter of the drill.

8. The combination tool according to claim 1, wherein the twist angle (γ) is in the range greater than 5°.

9. The combination tool according to claim 1, wherein the drill and the clamping sleeve are forcibly guided together via a guide element so that in a longitudinal movement of the clamping sleeve in the longitudinal direction, the clamping sleeve rotates automatically about the rotational axis (R) in accordance with the twist of the grooves.

10. The combination tool according to claim 9, wherein the guide element is formed on one of the drill backs.

11. A drill for a combination tool, which drill comprises a cutting insert provided with grooves, wherein the grooves extend helically at a twist angle (γ) and drill backs extending helically with a curved peripheral surface are formed between two grooves, wherein at least one of the drill backs is partially flattened to form an adjustment surface, wherein the adjustment surface extends helically.

12. The drill according to claim 11, wherein the combination tool is a chamfering tool.

13. The combination tool according to claim 1, wherein the combination tool is a chamfering tool.

14. The combination tool according to claim 5, wherein the angle (α) is in the range of 115° to 145°.

15. The combination tool according to claim 8, wherein the twist angle is in the range from 20° to 45°.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Exemplary embodiments of the invention are explained in greater detail below on the basis of the figures. These figures partially show simplified illustrations:

[0035] FIG. 1 a side view of a drilling/chamfering tool according to the prior art,

[0036] FIG. 2 a perspective illustration of a drill according to the invention,

[0037] FIG. 3A a sectional view of a cross-section through the drill along the section line A-A according to FIG. 3B,

[0038] FIG. 3B a side view of the drill according to the invention,

[0039] FIG. 4 a perspective illustration of a clamping sleeve for receiving and fastening the drill.

DETAILED DESCRIPTION

[0040] The combination tool 2 shown in FIG. 1 is designed as a drilling/chamfering tool. It extends in the longitudinal direction 4 along a rotational axis R. The combination tool comprises a drill 6 extending in the longitudinal direction 4 and a clamping sleeve 8. The clamping sleeve 8 serves to receive and fasten, i.e., to secure the drill 6 at a defined length position. In the prior art, a variable length adjustment and fastening of the drill 6 is made possible. The clamping is carried out by means of a radial clamping screw 10, for example. On its front end, the clamping sleeve furthermore comprises a cutting insert 12 designed as a chamfering tool with a cutting edge. In the exemplary embodiment, the cutting edge is inclined obliquely to the longitudinal direction 4 or alternatively oriented perpendicularly thereto. It serves to form a chamfer/bevel or even a broadened countersunk hole at the end of a drilled hole formed using the drill 6. The cutting insert 12 comprises an abutment side (not described in more detail) extending in parallel to the longitudinal direction and thus also in parallel to the adjustment surface 16. The cutting insert 12 is arranged in a holding seat 38 (cf. FIG. 4 in this respect).

[0041] The drill 6 is a grooved drill 6, i.e., a drill provided with grooves 14. Specifically, two grooves are provided, which are designed to extend helically at a twist angle γ (cf. FIG. 3B in this respect). An adjustment surface 16 can also be seen. Said adjustment surface in the drill shown in FIG. 1 extends according to the prior art in parallel to the longitudinal direction 4. It is incorporated into one of the drill backs 18, which are formed between the grooves 14.

[0042] FIG. 2 shows a drill 6 according to the invention. It also extends in the longitudinal direction 4 and comprises a rear shaft region 20, which is adjoined by a cutting region 22 provided with the grooves 14. On its front end, the drill has a drill tip 24. Thereon are formed the main blades for the drilling process. Starting from the front-side main blades, the grooves 14 extend over the length of the cutting region.

[0043] In the drill according to the invention, an adjustment surface 16 is also designed as a flattened partial surface of the drill back 18. In the drill 6 according to the invention, the adjustment surface 16 extends helically, namely in particular at the same twist angle γ at which the grooves 14 are also oriented. The twist angle γ is determined here by the inclination/orientation of the groove or a lateral delimiting line of the adjustment surface to the longitudinal direction 4 as viewed in a side view (cf. FIG. 3B in this respect).

[0044] The adjustment surface 16 is designed to be flat. This is in particular understood to mean that it is spanned at each point of its surface by two linear vectors, wherein one vector extends in parallel to the longitudinal direction 4 and the other extends perpendicularly to the longitudinal direction 4. In general, the adjustment surface is designed in the manner of a helical flat side. It has no curvature, especially no convexly curved surface regions, in contrast to the normal drill back 18.

[0045] The adjustment surface 16 starts in particular at the rear end of the drill back 18 and extends in the longitudinal direction 4 preferably via a large subregion of the cutting region 20. For example, the adjustment surface 16 extends over 30% to 70% of the length of the cutting region 20; in the exemplary embodiment, the adjustment surface 16 extends approximately over 50% of the length of the cutting region 22.

[0046] The adjustment surface 16 has a preferably constant width or at least an approximately constant width over its entire length. This means that both its lateral delimiting boundary lines extend in parallel to one another.

[0047] The adjustment surface 16 is formed in particular by grinding one of the two drill backs 18. The position and orientation of the adjustment surface 16 arises in particular from FIG. 3A. As can be seen therefrom, the adjustment surface 16 on the one side tapers off into the leading groove 14. On its opposite edge, it transitions into a curved peripheral side 26 of the drill back 18. With it, especially with a tangent 28, it encloses an obtuse angle α, which is approximately 135° in the exemplary embodiment.

[0048] It can also be seen that the adjustment surface 16 covers an angle range β1, which is approximately half of a total angle range β which is covered by the drill back 18.

[0049] In a preferred embodiment, the drill 2 also has a guide groove 29, which is indicated in FIG. 3A by way of example. This guide groove 29 serves a forced guidance for the clamping sleeve 8. The guide groove 29 is introduced into the drill back 18 opposite the drill back 18 into which the adjustment surface 16 is introduced. The guide groove 29 is introduced from outside into the peripheral side 26 and extends helically at the same twist angle γ as the grooves 14. A guide pin not shown here engages in this guide groove 29 and is formed on the inside of the clamping sleeve 8. The guide groove 29 and the guide pin define a forced guidance of the clamping sleeve 8 on the drill 6 so that in a longitudinal movement of the clamping sleeve 8 along the drill 6, the clamping sleeve 8 automatically rotates.

[0050] As can also be seen in FIG. 3A, the drill 6 generally also has cooling channels 30, one cooling channel respectively extending in each drill back 18. The cooling channels 30 therefore also extend helically.

[0051] Furthermore, it can be seen by means of the sectional view in FIG. 3A that the peripheral side of both drill backs 18 is somewhat radially recessed in comparison to a circle with a drill nominal diameter D.

[0052] Both drill backs 18 only have one support chamfer 32 each on the side that is oriented toward the leading groove 14, said support chamfers often provided with a side blade. The nominal diameter D is defined by the main blades on the end of the drill 6.

[0053] The support chamfer 32 is removed in the region of the adjustment surface 16 by the same and not present there.

[0054] FIG. 4 also shows a preferred clamping sleeve 8. It corresponds to a known clamping sleeve as described in DE 10 2017 210 986 A1. It comprises a rear slotted clamping shaft 34 as well as a front machining head 36, in which the holding seat 38 for receiving the cutting insert 12 is formed. The holding seat 38 is designed to highly accurately receive the cutting insert 12. The arrangement and orientation of the cutting insert 12 and of the cutting edge 13, even with regard to the adjustment surface 16, is analogous to what was described with respect to FIG. 1.

[0055] Overall, the clamping sleeve 8 comprises a cylindrical receptacle into which the drill can be inserted with variable length. The clamping sleeve 8 shown in FIG. 4 is received by a tool holder and clamped therein. At the same time, the drill 6 is also clamped via the slotted clamping sleeve.