DRILLING TOOL

Abstract

Proposed is a drilling tool for drilling workpieces, having a tool tip and a basic body and a core, wherein the basic body has at least one main groove as at least one helical depression, for the purpose of realizing a conveying helix in each case. For the purpose of prolonging the service life, the core, in a first portion that starts at the tool tip and/or extends to the tool tip, has a constant cross-sectional area perpendicular to the axis of rotation and, in an adjoining second portion, counter to the direction of advance, has a cross-sectional area that increases, at least in portions.

Claims

1. A drilling tool for drilling workpieces, which is rotatable about an axis of rotation in a direction of rotation during chip-removing machining, comprising: a tool tip that narrows in the direction of advance along the axis of rotation, and a basic body, wherein the basic body has at least one main groove as at least one helical depression with respect to the rotational volume occupied by the rotating drilling tool, for the purpose of realizing a conveying helix, wherein the volume occupied by the drilling tool during standstill, minus the at least one main groove, which is permanently pervaded both during standstill and during rotation defines a core, wherein the core, in a first portion that starts at the tool tip and/or extends to the tool tip, has a constant cross-sectional area perpendicular to the axis of rotation and, in an adjoining second portion, counter to the direction of advance, has a cross-sectional area that increases, at least in portions.

2. The drilling tool as claimed in claim 1, wherein the main groove and/or the tool tip has/have at least one cutting edge.

3. The drilling tool as claimed in claim 1, wherein, in the second portion, the cross-sectional area of the core increases monotonically along the axis of rotation, contrary to the direction of advance.

4. The drilling tool as claimed in claim 3, wherein the second portion has at least two successive sub-portions, which have an inclination in relation to the axis of rotation that decreases progressively along the axis of rotation, contrary to the direction of advance.

5. The drilling tool as claimed in claim 3, wherein, in the second portion, the increase in the cross-sectional area of the core lessens progressively contrary to the direction of advance.

6. The drilling tool as claimed in claim 3, wherein the second portion, contrary to the direction of advance, progressively approximates to the cross-sectional area of the rotational volume that is occupied by the rotating drilling tool.

7. The drilling tool as claimed in claim 1, wherein the at least one helical depression decreases progressively perpendicularly to the axis of rotation, contrary to the direction of advance.

8. The drilling tool as claimed in claim 1, wherein the at least one main groove in each case realizes a secondary cutting edge, which encloses a spiral angle, as an angle with respect to a perpendicular to the axis of rotation, which decreases in the course of the secondary cutting edge, contrary to the direction of advance, and which is preferably in the range of between 43 and 38.

9. The drilling tool as claimed in claim 1, wherein the tool tip tapers conically.

10. The drilling tool as claimed in claim 1, wherein the at least one helical depression comprises two helical depressions.

11. The drilling tool as claimed in claim 1, wherein the at least one conveying helix comprises two conveying helices.

12. The drilling tool as claimed in claim 4, wherein the second portion has at least two successive sub-portions, which have an inclination in relation to the axis of rotation that decreases monotonically.

13. The drilling tool as claimed in claim 5, wherein, in the second portion, the increase in the cross-sectional area of the core lessens monotonically.

14. The drilling tool as claimed in claim 6, wherein the second portion, contrary to the direction of advance, monotonically approximates to the cross-sectional area of the rotational volume that is occupied by the rotating drilling tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] An exemplary embodiment of the present invention is represented in the drawings and is explained in greater detail in the following, with further details and advantages being specified. In detail, there are shown:

[0021] FIG. 1 shows a representation of a drill according to the present invention, in a side view;

[0022] FIG. 2 shows a top view of the tool tip of the drill from FIG. 1, along the axis of rotation; and

[0023] FIG. 3 shows a schematic representation of the side view of a drill according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] FIG. 1 shows a drill 1 having a tool tip 2 and a basic body 3. The drill 1 is rotated about an axis of rotation A for the purpose of drilling a workpiece. In a rotation about the axis of rotation A, the basic body 3 occupies a cylindrical volume.

[0025] The tool tip 2 is shown in a top view in FIG. 2. Going through the axis of rotation A is a chisel edge 4, which in turn merges into two main cutting edges 5, 6 of the tool tip 2. These main cutting edges 5, 6 extend outward, and then merge into the main groove 7, 8, or into the secondary cutting edges 9, 10. In the intermediate region of the main groove there are thus formed two helical depressions 11, 12, which serve as conveying helices and provide for transport of the machined-off drilling dust, or the machined-off chips, contrary to the direction of advance V. The conveying helices 11, 12 each end in the region of the point B. Up to this point, or up to this height, the depth of each also decreases. Additionally indicated, by way of example, is a spiral angle , this angle decreasing, contrary to the direction of advance V, in the course from the tool tip 2 in the direction of the shank 13.

[0026] Also shown in FIG. 1, indicated by a broken line, is the core 14, its contour lines being represented in side view. In the case of the present exemplary embodiment, it is a core 14 that is substantially rotationally symmetrical about the axis of rotation A. Accordingly, in a sectional representation through the axis of rotation A, not only do its contour lines diverge in the direction contrary to the direction of advance V, but the cross-sectional area (measured perpendicularly to the axis of rotation) also increases correspondingly. As the cross-sectional area of the core 14 increases in the course contrary to the direction of advance V, the depth of the conveying helix 11, 12 also decreases with respect to the axis of rotation A. In the upper region close to the tool tip 2, however, in the first portion I, the cross-sectional area of the core 14 is constant (FIG. 3). In the subsequent second portion II, the cross-sectional area of the core 14 increases continuously in individual portions II.1, II.2, II.3. The cross-sectional area of the core 14 thus approximates to the cross-sectional area of the cylindrical rotational volume of the basic body 3. Thus, if it is necessary for the drilling tool 1 to be ground, the core 14 is retained in respect of its shape and cross-sectional area, and in effect does not differ from that of the original tool.

[0027] As additionally represented in FIGS. 1 and 2, behind the secondary cutting edges 9, 10 in the direction of rotation R there is a respective flank 15, 16, which is curved outwardly and is substantially parallel to the peripheral surface of the cylindrical rotational volume.

LIST OF REFERENCES

[0028] 1 drilling tool [0029] 2 tool tip [0030] 3 basic body [0031] 4 chisel cutting edge [0032] 5 main cutting edge [0033] 6 main cutting edge [0034] 7 main groove [0035] 8 main groove [0036] 9 secondary cutting edge [0037] 10 secondary cutting edge [0038] 11 conveying helix [0039] 12 conveying helix [0040] 13 shank [0041] 14 core [0042] 15 flank [0043] 16 flank [0044] I first portion [0045] II second portion [0046] II.1 sub-portion [0047] II.2 sub-portion [0048] II.3 sub-portion [0049] A axis of rotation [0050] B end of the conveying helices [0051] R direction of rotation [0052] V direction of advance [0053] spiral angle