METHOD FOR PRODUCING A MACHINING TOOL AND MACHINING TOOL

Abstract

In order to achieve a long service life for a machining tool, in particular for a solid carbide drill, it is provided with a special wear protection coating. In a first method step, in order to form this coating, a first layer made of a first material is applied in the region of a cutting edge and in the adjoining surface regions, and specifically, a flank face and a rake face. In a second step, the applied first material of the first layer is selectively removed at least partially, and preferably completely, only in the region of the cutting edge. Finally, in a third method step, a second layer made of a second wear-resistant material is applied both to the cutting edge and to the face regions. In this way, a coating having a high overall thickness in the face regions is made possible, without the risk of cracking.

Claims

1. A method for producing a machining tool which comprises a main body having a cutting edge, and further comprising a face region including a flank face and/or rake face adjoining the cutting edge, wherein a wear protection coating is applied to the cutting edge and to the face region, wherein for forming the coating, in a first step, a first layer made of a wear-resistant material is initially applied to the cutting edge and to the face region; subsequently, in a second step, the applied material of the first layer is selectively removed at least partially from the cutting edge; and finally, in a third step, a second layer made of a wear-resistant material is applied to the cutting edge and to the face region.

2. The method according to claim 1, wherein the first and second layers in the face region each have a layer thickness (d1, d2) in the range of 2 m to 10 m.

3. The method according to claim 1, wherein a combined thickness (D) of the first and second layers in the face region is greater than 8 m.

4. The method according to claim 1, wherein the first and second layers in the face region have the same layer thickness (d1, d2).

5. The method according to claim 1, wherein in the second step, the first layer in the region of the cutting edge is completely removed.

6. The method according to claim 1, wherein in the second step, the material of the first layer in the region of the cutting edge is mechanically removed.

7. The method according to claim 1, wherein the wear-resistant material of the first layer is the same as the wear-resistant material of the second layer.

8. The method according to claim 1, wherein differing materials are selected for the first layer and for the second layer.

9. The method according to claim 1, wherein the first and second layers are independently formed as nitride layers such as TiN, TiAlN, SiN, TiCrN, TiCN, TiAlSiN, as metallic oxide layers such as Al2O3, or as boride layers.

10. The method according to claim 1, wherein the main body is made of carbide.

11. The method according to claim 1, wherein the first and second layers are applied by way of a PVD method.

12. The method according to claim 1, wherein the coating is applied to a main body or tip of a rotary tool.

13. A machining tool comprising a main body having a cutting edge and a face region comprising a flank face and/or rake face abutting the cutting edge, wherein a wear protection coating is applied to the cutting edge and to the face region, the coating comprising a first layer that is applied to the main body and an outer second layer that is applied to the first layer, wherein the thickness (d1) of the first layer is at least reduced in the region of the cutting edge compared to the thickness (d2) of the first layer in the face region.

14. The machining tool according to claim 13, wherein overall thickness of the coating is lower in the region of the cutting edge than in the face region.

15. The machining tool according to claim 13, wherein overall thickness of the coating in the face region is greater than 8 m and is up to 16 m.

16. The machining tool according to claim 13, wherein the coating is applied to a main bod or tip of a rotary tool.

17. The machining tool according to claim 16, wherein machining tool is formed of solid carbide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] One non-limiting embodiment of the invention is explained in greater detail based on the figures. In simplified illustrations:

[0042] FIG. 1 shows a side view of a solid carbide drill;

[0043] FIG. 2A shows a schematic sectional illustration in the region of a cutting edge comprising an applied first coating layer;

[0044] FIG. 2B shows the illustration according to FIG. 2A after the first layer was removed in the region of the cutting edge; and

[0045] FIG. 2C shows the illustrations according to FIGS. 2A, 2B after the third method step was completed, with the second coating layer applied.

[0046] Parts having the identical functions are marked with the same reference numbers in the figures.

DETAILED DESCRIPTION

[0047] FIG. 1 shows a rotary tool which, in particular, is designed as a drill 2. The drill 2 extends in the longitudinal direction 4 along a center axis or an axis of rotation 5, around which the drill 2 rotates during operation. The drill 2 comprises a shank part 6 in the rear sub-region and a blade 8 in the front region. This extends up to a drill bit formed on the end face, which is usually formed by special point geometry and comprises main blades, which form the cutting edges 10. The blade 8 has an overall fluted design and in the exemplary embodiment it comprises spiral flutes 14. A secondary blade is usually formed along these flutes 14. In the exemplary embodiment, the drill 2 is designed with inside cooling channels, which exit at the end face at outlet holes 16.

[0048] In order to increase stability and wear resistance, a wear protection coating 18 is applied to the drill 2, in particular in the region of the cutting edges 10, and preferably in the entire blade 8. The special manufacturing method for applying this coating 11 will be described in more detail based on FIGS. 2A through 2C.

[0049] The coating 18 is generally applied to a main body 20. This body is in particular formed by the main body of the drill 2 and is specifically made of carbide. The drill 2 is in particular a solid carbide drill.

[0050] In a first method step, initially a first layer 18A of the coating 18 is applied to the main body 20, both in the region of the cutting edge 10 and in the adjoining face region, and specifically, to a flank face 22 and to a rake face 24. A first wear-resistant material is applied by way of the PVD method. The rake face 24 is in particular a flute face, and specifically, at least a sub-region of the flute 14.

[0051] The PVD application method creates a thickened region at the cutting edge 10, which favors the development of cracks 26.

[0052] In the second method step as shown in FIG. 2B, the first layer 18A is subsequently completely removed again in the region of the cutting edge 10 only, so that the cutting edge 10 itself is exposed again.

[0053] Finally, in the following third method step as shown in FIG. 2C, a second layer 18B is applied. Here, too, a second wear-resistant material is reapplied by way of the PVD method. The two materials are preferably the same wear-resistant material.

[0054] The first layer 18A has a layer thickness d1, and the second layer 18B has a layer thickness d2. In the exemplary embodiment, d1 is slightly lower than d2. Preferably, the layer thicknesses d1, d2, of the two layers 18A, 18B, generally range between 4 and 8 m. In total, the coating 18 has an overall thickness D of >8 m, and preferably >10 m, up to 16 m. The overall thickness D is measured for this purpose in the region of the flank face 22 or of the rake face 24 at a distance from the cutting edge 10, and specifically, in a region in which both layers 18A, 18B are formed.

[0055] The measure described herein in particular also prevents cracking in the critical region of the cutting edge 10, while achieving a comparatively high layer thickness in the face regions 22, 24, so that a long service life is achievable.

[0056] The concept described herein is not limited to the exemplary embodiment. The specially designed coating can be used not only for rotating tools, but for all machining tools in which a sharp, coated cutting edge is needed. In addition to drills/milling cutters, the coating concept is used in particular for superfinishing tools such as reamers, boring bars or hollowing tools.