METHOD FOR MANUFACTURING A CUTTING TOOL

Description

[0001] The invention relates to a method for manufacturing a cutting tool with at least one cutting edge, wherein the cutting tool has a tool body which is equipped with a hard coating at least in the area of ​​the cutting edge.

[0002] Cutting tools include machining tools for chip-removing manufacturing processes and tools for cutting. They typically consist of a shank and a cutting edge. At least one end of the shank serves to hold the cutting tool, for example, in a machine interface in the case of machining tools. The cutting edge is attached to the shank. It has at least one cutting edge, which the cutting tool uses to interact with the workpiece and remove material. Examples of such cutting tools include milling cutters, drills, reamers, chisels, scrapers, planes, and saws. The cutting tool can be a solid tool made entirely of a single material. Alternatively, the cutting edge can be enclosed in a insert, which is made of a different material than the shank.Cutting tools are subject to considerable mechanical and thermal stresses at their point of use due to the forces acting upon them and the temperatures generated. These include mechanical friction, oxidation and abrasion, and, especially at high machining speeds, diffusion and scaling. This leads to wear of the cutting tool in the area of ​​the cutting edge.

[0003] To improve the wear resistance of cutting tools and increase their service life, cutting tools are equipped with a hard coating in the cutting edge area. This coating is applied to the tool body. Examples of such hard coatings include diamond coatings, amorphous carbon layers (also known as diamond-like carbon, or DLC), and titanium coatings. These are applied to the tool body using methods such as chemical vapor deposition (CVD). After the hard coating is applied, the coated cutting edge has a blunt radius. This must then be sharpened to achieve the desired edge radius. This involves removing a portion of the hard coating from the cutting edge area.Sharpening a cutting edge by removing a portion of the hard material from the surface of the cutting tool can be carried out, for example, using a laser processing machine. This material removal is also known as laser ablation or laser vaporization. The material can be removed, for example, in layers across the surface. The laser beam is oriented essentially perpendicular to the surface from which a portion of the hard coating is being removed. This can be the clearance face or the rake face. Such a method is known, for example, from DE 10 2009 004 316 A1 and DE 10 2011 076 584 A1. Furthermore, it is possible to remove a portion of the hard coating using continuous or pulsed laser radiation, with the laser beam oriented essentially parallel to the surface to be created. Such a method is known, for example, from EP 2 682 219 A1.The laser beam can be directed at the cutting tool to be processed in such a way that the material removal begins in the area of ​​the cutting edge to be created, as shown in . Figure 1 This is illustrated in EP 2 682 219 A1. This is also referred to as material removal from the front. Alternatively, material removal can also begin on the side of the cutting tool facing away from the cutting edge to be produced, as shown in Figure 3 This is illustrated in EP 2 682 219 A1. This is also referred to as back-cutting. The laser radiation parameters must be adapted to the material being processed and the desired machining operation. Material removal can occur on the flank face, the rake face, or both. A method according to the preamble of claim 1 is known from JP 2016 175141 A.

[0004] Sharpening the coated cutting edge is generally carried out by ensuring that the wedge angle of the cutting wedge formed by the clearance face and rake face of the uncoated tool body matches the wedge angle of the coated and resharpened cutting wedge. However, this approach has the disadvantage that if the laser beam is aligned parallel to the surface to be created and material is removed from the back, the laser beam can be deflected in an undesirable manner by a secondary clearance face or another surface of the cutting tool that is neither the clearance face nor the rake face. Such a deflection of the laser beam can prevent the laser processing from achieving the desired sharpening of the cutting edge.

[0005] The invention is based on the objective of providing a method for manufacturing a hard-coated cutting tool in which a predetermined edge radius of the coated cutting edge can be reliably achieved even when part of the hard coating is removed by means of a laser beam to sharpen the coated cutting edge, wherein the laser beam is not oriented perpendicular to the surface of the cutting tool to be produced and the material removal can also take place from the rear.

[0006] This problem is solved by a method for manufacturing a cutting tool with the features of claim 1. The method is characterized in that the surface of the hard coating in the area of ​​the clearance face is not parallel to the underlying surface of the tool body after partial material removal, but rather that a first geometric plane, in which the surface of the tool body lying under the hard coating of the clearance face runs, and a second geometric plane, in which a surface of the hard coating bounded by the sharpened cutting edge in the area of ​​the clearance face runs after completion of the material removal, enclose an angle δ for which: 2° ≤ δ ≤ 10°.

[0007] This takes into account that the surface of the tool body lying beneath the coating on the clearance face ends at the uncoated cutting edge, while the geometric plane in which this surface of the tool body extends infinitely. The surface of the hard coating in the clearance face area after partial material removal ends at the sharpened cutting edge, while the second geometric plane extends infinitely. The first and second geometric planes intersect along a geometric line. This geometric line can coincide with the uncoated cutting edge of the tool body, coincide with the sharpened cutting edge of the cutting tool, extend outside the tool body and within the hard coating on the rake face, or extend outside the cutting tool.

[0008] The surface of the hard coating in the clearance area is preferably inclined after material removal such that the coating thickness on the clearance area increases with increasing distance from the cutting edge. If a hard coating with a uniform thickness is deposited on the cutting edge, the clearance area, and the rake face, subsequent resharpening of the cutting edge requires material removal only directly at the cutting edge. The amount of hard coating material to be removed decreases with increasing distance from the cutting edge. This creates a cutting edge with a predetermined radius while simultaneously leaving more hard coating material on the cutting tool. Since less material needs to be removed, the material removal process is completed in a shorter time.

[0009] The cutting tool can be elongated and extend along a geometric longitudinal axis. Examples include milling cutters or drills. The at least one cutting edge can be a primary or secondary cutting edge. It can be located on an end face of the elongated cutting tool or extend along the shank in the area of ​​a chip groove.

[0010] The hard coating is removed by means of laser processing. For this purpose, a laser beam from a laser processing machine is aligned at a specific angle relative to the surface of the hard coating at the clearance face in order to partially remove the hard coating. The angle at which the laser beam is aligned with its geometric beam axis relative to the surface of the coated cutting tool depends on the angle δ formed by the first geometric plane and the second geometric plane after the material removal is complete. According to a first embodiment of the invention, the laser beam is aligned such that the geometric beam axis runs parallel or tangentially to the surface to be created at the clearance face.Since the laser beam is typically focused on the surface of the cutting tool, a second alternative of the invention takes the laser beam's opening angle into account when aligning the laser beam. If the hard coating has a uniform layer thickness in the area of ​​the clearance surface after deposition, the laser beam can be aligned with its geometric beam axis at the beginning of material removal at an angle δ relative to the surface to be produced. When the opening angle of the focused laser beam is considered, this angle corresponds to the sum of half the opening angle and the angle δ. The hard coating can be removed, in particular, from the rear. This means that the removal begins in a section of the clearance surface facing away from the sharp cutting edge to be produced. This avoids unwanted deflection of the laser beam.Furthermore, it is ensured that all areas where the laser beam strikes the cutting tool are removed during material ablation. The resulting surface on the clearance face is therefore smooth and exhibits good surface quality. A sharpened cutting edge with a predefined edge radius is produced to the desired quality.

[0011] According to an advantageous embodiment of the invention, a hard coating with a layer thickness between 2 µm and 40 µm is deposited on the tool body.

[0012] According to a further advantageous embodiment of the invention, the hard coating is removed such that the angle δ is: 3° ≤ δ ≤ 6°. The angle δ typically depends on the layer thickness of the hard coating at the clearance face, the material of the hard coating, and the wedge angle of the cutting wedge.

[0013] According to a further advantageous embodiment of the invention, when the hard coating is partially removed, the thickness of the hard coating on the clearance surface is reduced in such a way that the thickness of the hard coating on the clearance surface increases with increasing distance from the sharpened cutting edge, starting from the sharpened cutting edge.

[0014] According to a further advantageous embodiment of the invention, the first geometric plane and the second geometric plane intersect at the uncoated cutting edge. In this case, the tool body is free of the hard coating in the area of ​​the uncoated cutting edge. This prevents mechanical or thermal stresses between the tool body and the hard coating.

[0015] According to the second alternative of the invention, during laser processing, the laser beam is aligned with its beam axis such that it forms an angle α + δ with the first geometric plane, where 1° ≤ α ≤ 10°. This takes into account that the laser beam can be focused on the surface of the workpiece and therefore has an opening angle. Here, the angle α corresponds to half the opening angle of the laser beam.

[0016] According to a further advantageous embodiment of the invention, the material removal of the hard coating begins at the clearance surface of the hard coating in a section of the clearance surface furthest from the cutting edge and ends at the rake face. In this case, material removal takes place from the rear.

[0017] According to a further advantageous embodiment of the invention, the cutting edge provided with the hard coating is sharpened by additional partial removal of the hard coating in the rake face area, such that after partial removal of the hard coating, the angle ε between a third geometric plane, in which the surface of the tool body lying beneath the hard coating of the rake face runs, and a fourth geometric plane, in which the surface of the hard coating bounded by the sharpened cutting edge in the rake face area runs after partial material removal, is: 0° ≤ ε ≤ 70°. The angle δ can be the same as or different from the angle ε. In this case, to resharpen the cutting edge after deposition of the hard coating, not only is the layer thickness of the hard coating reduced on the flank face, but also on the rake face.The material removal can be carried out in such a way that the newly formed surface after material removal is parallel to the underlying surface of the tool body, i.e., ε=0°, or forms an angle other than 0° with this surface. If the latter is the case, then, just as on the clearance face, the layer thickness on the rake face is preferably reduced such that the layer thickness of the hard coating increases with increasing distance from the cutting edge.

[0018] According to a further advantageous embodiment of the invention, the hard coating on the rake face is removed in such a way that the angle ε is: 2° ≤ ε ≤ 10°, particularly preferably 3° ≤ ε ≤ 6°.

[0019] According to a further advantageous embodiment of the invention, when the hard coating is partially removed, the thickness of the hard coating on the rake face is reduced in such a way that the thickness of the hard coating on the rake face increases with increasing distance from the sharpened cutting edge.

[0020] According to a further advantageous embodiment of the invention, a diamond layer is deposited on the tool body as a hard coating. This can be a crystalline or polycrystalline diamond layer. The latter has a heterogeneous distribution of the size of the crystalline domains. Instead of diamond, a hard coating made of DLC, a nitride-based material such as titanium nitride, another titanium-containing material, or another material suitable for a hard coating can also be applied to the tool body. The abbreviation DLC stands for Diamond-like Carbon. This type of hard coating is also referred to as amorphous diamond.

[0021] According to a further advantageous embodiment of the invention, the hard coating on the clearance surface is completely removed section by section such that the tool body is exposed in the relevant section. This applies in particular to the cutting edge of the tool body and optionally an adjacent area. The tool body is thus freed from the hard coating at or near the cutting edge. This allows mechanical or thermal stresses between the tool body and the hard coating to be avoided or at least reduced.

[0022] According to a further advantageous embodiment of the invention, the hard coating on the rake face is completely removed section by section such that the tool body is exposed in the relevant section. Preferably, the tool body is exposed in the area of ​​the cutting edge. This reduces or eliminates mechanical and / or thermal stresses between the tool body and the tool body.

[0023] According to a further advantageous embodiment of the invention, laser processing is carried out with a pulsed laser beam, wherein the pulse duration is between 50 ns and 150 fs. Processing with such ultrashort laser pulses has the advantage that very high energy densities can be generated locally on the surface of the workpiece, and thus material can be removed without the heat spreading undesirably within the workpiece.

[0024] According to a further advantageous embodiment of the invention, the pulse duration is between 190fs and 10ps.

[0025] According to a further advantageous embodiment of the invention, the pulse frequency is between 100kHz and 1,000kHz.

[0026] According to a further advantageous embodiment of the invention, the average laser power is between 4 and 40 W. With a pulse duration between 190 fs and 10 ps, ​​a pulse frequency between 100 kHz and 1,000 kHz, and an average laser power between 4 and 40 W, a processing speed of between 10 mm / min and 40 mm / min can be achieved with respect to CNC-controlled machine axes of a laser processing device.

[0027] According to a further advantageous embodiment of the invention, the pulse duration is between 6 ns and 45 ns and the pulse frequency is between 15 kHz and 200 kHz. In this case, the average laser power is preferably between 9 and 18 W. For example, a processing speed of between 45 mm / min and 100 mm / min can be achieved with respect to CNC-controlled machine axes of a laser processing device.

[0028] According to a further advantageous embodiment of the invention, the beam diameter of the laser beam at the focus is between 7 µm and 25 µm. The focus is preferably located at or near the surface of the workpiece to be processed.

[0029] According to a further advantageous embodiment of the invention, the tool body consists of carbide.

[0030] According to a further advantageous embodiment of the invention, the layer thickness of the hard coating in the area of ​​the clearance surface and the rake surface of the cutting edge, in which no material removal takes place, is between 2 and 40µm.

[0031] Further advantages and advantageous embodiments of the invention can be found in the following description, the drawing and the claims. drawing

[0032] The drawing shows exemplary embodiments of the invention. It shows: Figure 1: Cutting tool without hard coating in perspective view; Figure 2: Detail of the cutting tool according to Figure 1 , Figure 3 Cutting tool according to Figure 1 in perspective view immediately after the application of a hard coating and before sharpening the cutting edge, Figure 4 section of the cutting tool according to Figure 3 Figure 5: Section through the cutting tool according to Figure 3in the area of ​​a cutting edge on the front face, Figure 6 section according to Figure 5 , wherein the hard coating on the clearance face of the cutting edge is partially removed, Figure 7 Illustration according to Figure 6 with the angle δ, Figure 8 representation according to Figure 7 with an angle α, Figure 9 Section through the cutting tool according to Figure 3 and 5 , wherein the hard coating on the clearance face and on the rake face of the cutting edge is partially removed, Figure 10 Section through the cutting tool according to Figure 3 and 5 , wherein the hard coating is applied to the free surface and in one of Figure 9 The cutting edge is partially removed in a different manner, as shown in Figure 11, cutting tool according to... Figure 3 , wherein the hard coating is applied to the clearance surface and the rake face of the cutting edge according to Figure 9 removed, Figure 12 Detail from the cutting tool according to Figure 11Figure 13 shows the orientations of a laser beam during material removal at the cutting tool according to Figures 6 to 12 , wherein the material removal takes place in the area of ​​a cutting edge on the face of the cutting tool, Figure 14 further cutting edge of the cutting tool according to Figure 3 Figure 15 shows an alignment of the laser beam during material removal using the cutting tool according to Figures 6 to 12 on a free surface of a cutting edge in the area of ​​the chip groove, Figure 16 shows an alignment of the laser beam during material removal at the cutting tool according to Figures 6 to 12 on a rake face of a cutting edge in the area of ​​the chip groove, start of material removal, Figure 17 progressive material removal according to Figure 16 on the chip surface in the area of ​​the cutting edge of the chip groove. Description of the exemplary implementations

[0033] In the Figures 1 to 10The image shows the head of a cutting tool at various stages of its manufacture. The cutting tool is a square-shank end mill. Figures 1 and 2 Figure 1 shows the head of the tool body 1 of the cutting tool without a hard coating. The tool body has a cutting edge 3 on its end face with an associated clearance surface 5 and an associated rake face 6.

[0034] The Figures 3, 4 and 5 The cutting tool is shown after the application of a hard coating 2 to the tool body 1. The hard coating extends over the entire surface. Figure 1The surface of the tool body 1 is shown. The application of the hard coating has formed a blunt radius 4 above the uncoated cutting edge 3 of the tool body 1. Adjacent to the blunt radius 4 are the surface 7 of the hard coating 2 on the clearance face 5 and the surface 11 of the hard coating on the rake face 6. The hard coating 2 exhibits in the Figure 5 The section shown has a uniform layer thickness.

[0035] Figure 5 This shows that the edge radius of the blunt rounding 4 is larger than the edge radius of the cutting edge 3 of the uncoated tool body 1. To reduce the edge radius of the coated cutting edge, the cutting edge is sharpened after coating by partially removing the hard coating 2.

[0036] The removal of the hard coating is in the Figures 6 to 10 as shown. First, as in Figure 6 and 7As shown, a portion of the hard coating on the flank face is removed, while the rake face initially remains unchanged. For this purpose, a laser beam with its geometric beam axis 15 is aligned such that the beam axis forms an angle δ with a first geometric plane 16. In this first geometric plane 16, the surface 9 of the tool body 1 runs beneath the hard coating on the flank face 5. This surface 9 of the tool body 1 is bounded by the cutting edge 3 of the uncoated tool body 1. It is adjacent to the coating 2. The first geometric plane is not bounded. It extends beyond the surface 9 of the tool body 1. The original contour 7 of the surface of the hard coating 2 on the flank face is shown as a dashed line. Due to the partial material removal, a new surface 8 of the hard coating on the flank face has been created.This surface 8 lies in a second geometric plane 18. The first geometric plane 16 and the second geometric plane 18 are not parallel to each other. They intersect in a geometric line 20, which, due to the viewing direction, Figure 7 Only one point is recognizable. The geometric line 20 runs outside the cutting tool. The first geometric plane 16 and the second geometric plane 18 enclose the angle δ. In the present embodiment, the angle δ is 10°. The angle δ is in Figure 7 As shown. The partial removal of material from the free surface creates a new sharpened cutting edge 10. Figure 7 shows that the laser beam with its beam axis 15 is essentially parallel or tangential to the second geometric plane 18, in which the surface 8 of the hard coating created by material removal on the free surface runs. Figure 7further shows that the material removal begins in a section of the clearance surface facing away from the cutting edge and continues along the second geometric plane 18 to the rake face.

[0037] Figure 8 shows an alternative to the alignment of the beam axis 15 of the laser beam according to Figure 7 The laser beam is inclined with its beam axis 15a relative to the orientation 15 by an angle α, where the angle α corresponds to half the opening angle of the laser beam. α typically has a value between 1° and 10°.

[0038] The Figures 9, 10 , 11 and 12 The cutting tool is shown after an additional portion of the hard coating 2 has been removed from the rake face. The original surface profile 11 of the hard coating on the rake face is shown in Figure 9The dashed lines represent the surface area. The partial material removal has created a new surface 12 of the hard coating on the rake face. This surface 12 is parallel to the underlying surface 13 of the tool body 1. Surface 13 lies in a third geometric plane 17. Surface 12 lies in a fourth geometric plane 19. The angle ε between the two surfaces 12 and 13 is 0°. Similarly, the angle ε between the third geometric plane 17 and the fourth geometric plane 19 is also 0°. The third geometric plane 17 and the fourth geometric plane do not intersect. The partial material removal on the rake face has created a new sharpened cutting edge 14.

[0039] Figure 10 shows an alternative to Figure 9Material is removed from the rake face such that the angle ε is not 0°. The new surface 12a of the hard coating on the rake face, created by the material removal, is not parallel to the underlying surface 13 of the tool body 1. The fourth geometric plane 19a, in which the new surface 12a runs, intersects the third geometric plane 17 along a straight line and forms an angle ε = 3° with the third geometric plane 17. The partial material removal on the rake face results in a new, sharpened cutting edge 14a.

[0040] Figure 13This shows how the laser beam, with its beam axis, is aligned during material removal at the clearance face and the rake face when the corresponding cutting edge is located in the area of ​​the end face of the cutting tool. The first alignment of the beam axis 30 is given during material removal at the clearance face. It essentially corresponds to the alignment of the beam axis 15 of the laser beam in Figure 7 or the alignment of the beam axis 15a of the laser beam in Figure 8The laser beam strikes the surface of the hard coating 2 of the tool body 1 at point 32. Material removal begins in a section of the clearance face facing away from the cutting edge and ends at the rake face along the sharpened cutting edge. The advantage of this laser beam orientation is that the areas struck by the laser beam are completely removed. The hard coating remaining on the cutting tool contains no impact points. Therefore, the surface produced by material removal on the clearance face is very smooth. The same applies to material removal on the rake face: Here, the beam axis 31 of the laser beam also has an orientation that is parallel or tangential to the surface to be produced, or forms an angle α between 1° and 10° with this surface. In this way, a very smooth surface of the hard coating can also be produced on the rake face.The material removal begins in a section of the rake face facing away from the cutting edge and ends at the clearance face along the sharpened cutting edge.

[0041] Figure 14 shows the material removal at another cutting edge 23 of the cutting tool according to Figure 3The hard coating 2 on the tool body 1 is removed from the clearance face 25 to the rake face 26, creating a new surface 28 of the hard coating on the clearance face. This new surface 28 lies in a second geometric plane 38. The surface of the tool body 1, located beneath the hard coating 2 on the clearance face 25, lies in a first geometric plane 36. The first geometric plane 36 and the second geometric plane 38 intersect at an angle δ at the cutting edge 23 of the tool body 1. In this case, the angle δ is 50°. Through the material removal and the resulting new surface 28, the hard coating on the cutting edge 23 of the tool body 1 is removed, leaving the cutting edge 23 free of any hard coating.

[0042] The Figures 15, 16 and 17show the partial material removal on a clearance surface and a rake surface along a chip groove 40 of the cutting tool according to Figures 1 to 12 Along the chip groove 40 extends another cutting edge 43 with an associated clearance face 45 and an associated rake face 46. This cutting edge 43 is also sharpened by partial material removal after the application of a hard coating. The chip groove 40 is an elongated recess between two cutting edges that extend helically along the outside of the cutting tool shank. Of these two cutting edges, the Figures 15 to 17 Only the cutting edge 43 is visible. The other cutting edge is located on the side of the cutting tool facing away from the viewer. The chip groove 40 serves to collect the chips produced during the cutting action of the cutting tool on a workpiece not shown in the drawing.

[0043] Figure 15This shows how the laser beam is aligned with its geometric beam axis 47 to remove material from the free surface 45. The geometric beam axis 47 forms an angle β with a tangent 48 to the surface of the free surface 45 to be created. This angle typically corresponds to half the opening angle of the laser beam. The angle β can be related to the angle α according to Figure 8 This is not strictly necessary, however. Since the clearance surface 45 of the cutting edge 43 is located on an outwardly directed section of the cutting tool, the laser beam can be aligned with its geometric beam axis 47 in a plane that is essentially perpendicular to a geometric longitudinal axis of the cutting tool.

[0044] The Figure 16 and 17 show how the laser beam is aligned with its geometric beam axis 49 to remove material from the rake surface 46. Figure 16shows the orientation of the geometric beam axis at the beginning of material removal at the face of the cutting tool. Figure 17 Figure 1 shows the orientation of the geometric beam axis 49 when material removal has already progressed along the chip groove 40 in the axial direction. In both cases, the geometric beam axis 49 is inclined at an angle γ relative to a tangent 50, 51 to the surface being machined. Since the rake face 46 is located on the inwardly curved surface of the chip groove, the laser beam with its geometric beam axis 49 must be oriented differently than shown in Figure 2. Figure 15 It must be aligned so that it hits the surface of the cutting tool at the intended position and in a tangential direction. Reference figures

[0045] 1 Tool body 2 Hard coating 3 Cutting edge of the tool body 4 Blunt radius 5 Clearance face 6 Chip surface 7 Original surface profile of the hard coating on the clearance face 8 Surface profile of the hard coating on the clearance face after partial material removal 9 Surface of the tool body on the clearance face 10 Re-sharpened coated cutting edge 11 Original surface profile of the hard coating on the chip surface 12 Surface profile of the hard coating on the chip surface after partial material removal 12a Surface profile of the hard coating on the chip surface after partial material removal in an alternative 13 Surface of the tool body on the chip surface 14 Re-sharpened coated cutting edge 14a Re-sharpened coated cutting edge in an alternative 15 Geometric beam axis of a laser beam 15 Geometric beam axis of the laser beam 16 First geometric plane 17 Third geometric plane 18 Secondgeometric plane 19 fourth geometric plane 19 fourth geometric plane in an alternative 20 geometric line where the first and second geometric planes intersect 23 cutting edge of the tool body 25 clearance surface 26 rake surface 28 contour of the hard coating surface on the clearance surface after partial material removal 30 first alignment of the laser beam axis 31 second alignment of the laser beam axis 32 point of impact of the laser beam on the hard coating surface 36 first geometric plane 38 second geometric plane 40 chip groove 43 cutting edge 45 clearance surface 46 rake surface 47 geometric beam axis of the laser beam 48 tangent to the surface of the clearance surface to be machined 49 geometric beam axis of the laser beam 50 tangent to the surface of the clearance surface to be machined 51 tangent to the surface of the clearance surface to be machined

Claims

1. Method for producing a cutting tool comprising a tool body with a hard coating, wherein the hard coating (2) is applied to the tool body (1) at least in an area of a cutting edge (3), a flank face (5) and a rake face (6) comprising the following steps: depositing a hard coating (2) on the surface of the tool body (1) of the cutting tool in the area of the cutting edge (3), a flank face (5) adjacent to the cutting edge (3) and a rake face (6) adjacent to the cutting edge (3), sharpening the cutting edge that is provided with the hard coating (2) and forming a dull rounded edge (4) by partially removing the hard coating (2) in the area of the flank face (5) of the cutting edge by laser machining, characterized in that the removal of the hard coating (2) is carried out in such a way that for an angle δ between a first geometric plane (16), in which the surface (9) of the tool body (1) lying beneath the hard coating (2) of the flank face (5) extends, and a second geometric plane (18), in which a surface (8) of the hard coating (2) defined by the sharpened cutting edge (10, 14, 14a) in the area of the flank face (5) extends after removal, the following applies: 2° ≤ δ ≤ 10°, preferably 3° ≤ δ ≤ 6°, and that during laser machining, a laser beam is aligned with its geometric beam axis (15, 15a, 30) in such a way that the geometric beam axis encloses an angle δ or an angle α + δ with the first geometric plane (16), where 1° ≤ α ≤ 10°.

2. Method according to claim 1, characterized in that a hard coating (2) is deposited on the tool body (1) with a layer thickness between 2 µm and 40 µm.

3. Method according to one of the preceding claims, characterized in that the partial removal of the hard coating (2) reduces the thickness of the hard coating (2) at the flank face (5) so that the thickness of the hard coating (2) increases from the sharpened cutting edge (10, 14, 14a). 14a) with an increasing distance from the sharpened cutting edge (10, 14, 14a).

4. Method according to one of the preceding claims, characterized in that the material removal of the hard coating (2) starts at the flank face (5) of the hard coating (2) in a section of the flank face (5) that is distal from the cutting edge (3) of the tool body (1) and terminates at the rake face (6) .

5. Method according to one of the preceding claims, characterized in that the cutting edge (10, 14, 14a) provided with the hard coating (2) is sharpened by additionally partially removing the hard coating (2) in the portion of the rake face(6) by laser machining, so an angle ε is enclosed between a third geometric plane (17), in which the surface (9) of the tool body (1) extends that is arranged under the hard coating (2) of the rake face(6) and a fourth plane (19) in which a surface (12) of the hard coating (2) defined by the sharpened cutting edge (14) extends in the area of the rake face (6) after the partial removal of the hard coating (2), wherein 0° ≤ ε ≤ 70°.

6. Method according to claim 5, characterized in that the hard coating (2) is removed in such a way that the following applies to the angle ε: 2° ≤ ε ≤ 10°, particularly preferably 3° ≤ ε ≤ 6° .

7. Method according to claim 5 or 6, characterized in that, partial removal of the hard coating (2) reduces the thickness of the hard coating (2) at the rake face (6) so that the thickness of the hard coating (2) at the rake face (6) increases from the sharpened cutting edge (14) with an increasing distance from the sharpened cutting edge (14)..

8. Method according to one of the preceding claims, characterized in that a diamond layer is deposited on the tool body (1) as a hard coating (2) .

9. Method according to one of the preceding claims, characterized in that the hard coating (2) is removed from the flank face (5) completely in sections so that the tool body (1) is exposed in sections.

10. Method according to one of the preceding claims, characterized in that the hard coating (2) is removed from the rake face (6) completely at least in sections so that the tool body (1) is exposed in the sections.

11. Method according to one of the preceding claims, characterized in that the laser machining is performed by a pulsed laser beam, wherein the pulse duration is between 50 ns and 150 fs.

12. Method according to claim 11, characterized in that the pulse duration is between 190 fs and 10 ps.

13. Method according to claim 11 or 12, characterized in that the pulse frequency is between 100 kHz and 1,000 kHz.

14. Method according to one of the preceding claims, characterized in that the average laser power is between 4 and 40W.

15. Method according to claim 12, characterized in that the pulse duration is between 6 ns and 45 ns and the pulse frequency is between 15kHz and 200kHz.

16. Method according to claim 15, characterized in that the average laser power is between 9 and 18 W.

17. Method according to one of the preceding claims, characterized in that the beam diameter of the laser beam at the focus is between 7 µm and 25 µm