Taps and processes

Abstract

A screw tap (10) with a shank and a cutting area arranged along a longitudinal axis (A) of the screw tap, wherein the cutting area (10) has a plurality of cutting teeth (16) on its circumferential side (14) which are provided for the machining of thread turns in a drilled hole, wherein the cutting area has at least one chip surface (18) running transversely to its circumferential side (14) and extending at least over associated chip flanks (20) of the cutting teeth (16), characterized in that the at least one chip surface (18) has at least one respective strip-shaped surface structuring (124, 224, 324) produced by means of a laser process, which extends at least over a partial area of ​​the chip flanks (20) of the cutting teeth (16).

Description

[0001] The present invention relates to a tap with a shank and a cutting area arranged along a longitudinal axis of the tap. The cutting area has a plurality of cutting teeth on its circumferential side, which are provided for the machining of threads in a drilled hole. The cutting area has at least one chip surface running transversely to its circumferential side, which extends at least over associated chip flanks of the cutting teeth. The cutting teeth are arranged along a helical line according to the shape of the thread to be created. STATE OF THE ART

[0002] A tap typically has two or more chip faces, also known as cutting surfaces, with the cutting teeth arranged along the respective chip faces. The cutting teeth are increasingly flattened toward the end of the cutting area opposite the shank. The tap can be designed as a single-cut tap or as part of a multi-part tap set, e.g., as a leading cutter, intermediate cutter, or finishing cutter of a three-part tap set. The chip flank of a cutting tooth is the flank of the cutting tooth that is at the front in the machining direction of the tap.

[0003] In a tap, the chip surfaces, and especially the flanks of the cutting teeth, are subject to particularly high levels of wear. Deposits can also form in the chip surface area.

[0004] US 2013 / 0302102 A1 describes a drilling tool and a method for its manufacture, in which the cylindrical outer walls are provided with a plurality of recesses which can absorb lubricant and thus increase the thickness of a lubricating film between the tool and a workpiece.

[0005] EP 3 115 137 A1 proposes providing a metal core of a cutting tool with a texture of linearly arranged, circular depressions on the circumference, which is intended to improve the adhesion of a surface coating.

[0006] Furthermore, DE 195 11 829 B4 is known from the prior art.

[0007] It is the object of the present invention to provide a tap which has low wear, ensures good removal of material chips and in which undesirable formation of deposits is reduced. DISCLOSURE OF THE INVENTION

[0008] The problem is solved by a tap having the features of claim 1. Advantageous embodiments of the method are the subject of subclaims.

[0009] It is proposed that at least one rake face has at least one respective strip-shaped surface structuring 10 produced by means of a laser process, which extends at least over a partial region of the rake flanks. With the said laser process, one or more laser beams can be guided in a focused manner in adjacent paths over the rake faces. The surface structuring can be limited to the rake faces of those cutting teeth that are involved in the cutting process. For example, the surface structuring can extend only over the rake faces of the first five cutting teeth. In the region of those cutting teeth that essentially only ensure the guidance of the tap in threads that have already been cut, the surface structuring can be omitted.

[0010] The surface texture improves the evacuation of material chips generated during machining. This prevents the material chips from becoming trapped in the chip surfaces, ultimately reducing wear on the tap.

[0011] The strip-shaped surface structuring is particularly designed as a microstructure, whereby the distance between adjacent stripes, lines, or tracks can be between 1 µm and 500 µm. The track or beam width of a laser device used to produce the strip-shaped surface structuring can, for example, be between 1 µm and 500 µm. The track width can, in particular, be between 10 µm and 100 µm.

[0012] According to an advantageous embodiment of the invention, the strip-shaped surface structuring has alternating adjacent elevations and valleys, wherein the valleys are created by material removal and / or the elevations are created by material deposition, and / or wherein the elevations and valleys are created by material redistribution. In other words, the rake faces in the region of the strip-shaped surface structuring have a three-dimensional structure. The elevations do not necessarily have to protrude beyond the original plane of the rake face that existed before the laser process was carried out, but can also run flush with it. The material can be deposited, for example, using foreign material, in particular according to the principle of build-up welding. In principle, however, material that was removed from the valleys can at least partially be deposited on the elevations during material redistribution.

[0013] Advantageously, the strip-shaped surface structuring comprises alternating adjacent regions of different microstructures, wherein the regions of different microstructures also differ in terms of their hardness. For example, regions that have been hardened or remelted by the laser can alternate with essentially unchanged or less significantly altered regions. The altered and unchanged or less significantly altered regions do not necessarily have to be of equal width, but can also have different widths. For example, the machined, i.e., hardened or remelted regions can be significantly wider than the unchanged or less significantly altered regions.

[0014] The strip-shaped surface structuring can, for example, be formed as a pattern of parallel, in particular straight, lines.

[0015] The striped surface structuring can run parallel to the tap's longitudinal axis or transversely, particularly perpendicularly, to it. Diagonal surface structuring is also possible.

[0016] The edges that define the chip flanks of the cutting teeth are approached. Alternatively, the strip-shaped surface structure can also be spaced from the edges that define the chip flanks.

[0017] The strip-shaped surface structuring provided on a respective chip face can be formed as a continuous surface. Alternatively, it is also possible for the strip-shaped surface structuring provided on a respective chip face to be divided into several spaced-apart sub-areas. In particular, in this case, the sub-areas can only cover the chip flanks of the cutting teeth.

[0018] The laser process mentioned can in particular be a laser marking process.

[0019] The invention further relates to a method for producing a strip-shaped surface structuring on a tap, wherein the tap has a shank and a cutting area which are arranged along a longitudinal axis of the tap, wherein the cutting area has a plurality of cutting teeth on its circumferential side which are provided for the machining of thread turns in a drilled hole, wherein the cutting area has at least one chip surface running transversely to its circumferential side which extends at least over associated chip flanks of the cutting teeth, wherein a laser beam is guided in a plurality of strip-shaped paths over at least one of the chip surfaces in order to generate local changes in the material properties which form the strip-shaped surface structuring by energy input.

[0020] Advantageous embodiments of the invention which were mentioned in connection with the tap according to the invention also form advantageous embodiments of the method according to the invention. DRAWINGS

[0021] The invention is described below using exemplary embodiments with reference to the drawings. In the drawings: Fig. 1a a side view of a tap provided with a strip-shaped surface structuring according to a first embodiment; Fig. 1b and Fig. 1c enlarged views of the tap from Fig. 1a; Fig. 2a a side view of a tap provided with a strip-shaped surface structuring according to a second embodiment; Fig. 2b an enlarged view of the tap of Fig. 2a; Fig. 3a shows a side view of a tap provided with a strip-shaped surface structuring according to a third embodiment; and Fig. 3b an enlarged view of the tap of Fig. 3a.

[0022] In the following, similar components or elements are given the same reference symbols.

[0023] Fig. 1a to 1c, 2a, 2b, 3a and 3b each show a tap 10 with a shank (not shown) and a cutting area 12 which adjoins it in the direction of the longitudinal axis A of the tap 10 and is shown at least in section. On the circumferential side 14 of the cutting area 12, a plurality of cutting teeth 16 are provided which are arranged along a helical line and are designed for the essentially machining formation of threads in a drilled hole of a workpiece.

[0024] In the present exemplary embodiments, the tap 10 has a total of four chip flutes 26 running in the longitudinal direction of the tap 10, each of which is bordered by a rake face 18 running transversely to the circumferential side 14 and a flank face 22 facing the rake face 18. In the present figures, a maximum of two of the chip flutes 26 are visible; the other two chip flutes are located on the opposite, non-visible side of the tap 10. Accordingly, in the plan view, a maximum of only one rake face 18 and one flank face 22 can be seen. The other rake face 18 or flank face 22 runs essentially parallel to the viewing direction.

[0025] The cutting teeth 16 are designed such that respective chip flanks 20 of the cutting teeth 16 form partial surfaces of the respectively associated chip surface 18.

[0026] For the tap 10 according to Fig. 1a to 1c, a respective strip-shaped surface structuring 124 is formed on the chip flanks 20 as a pattern of parallel, straight lines or paths, wherein this pattern runs substantially parallel to the longitudinal axis A of the tap 10. As particularly shown in Fig. 1c, the surface structures 124 cover only partial areas of the chip flanks 20, so that the surface structures 124 are spaced from edges 28 of the cutting teeth 16.

[0027] For the tap 10 of Fig. 2a and Fig. 2b, a strip-shaped surface structuring 224 is provided on each of the chip faces 18, which extends completely over the associated chip flanks 20 as well as over an adjacent partial area of ​​the chip face 18, so that the surface structuring 224 provided on a respective chip face 18 is continuous. In contrast to the embodiment of Fig. 1a to 1c, the surface structuring 224 runs essentially transversely to the longitudinal axis A.

[0028] Finally, the tap 10 according to Fig. 3a and Fig. 3b a strip-shaped surface structuring 324 is provided, which is similar to the embodiment according to Fig. 2a and Fig. 2b extends as a continuous area over a portion of a respective chip surface 18 including the chip flanks 20. In contrast to Fig. 2a and Fig. 2b, however, the strip-shaped surface structuring 324 runs parallel to the peripheral side 14, ie essentially parallel to the longitudinal axis A.

[0029] All surface structures 124, 224, and 324 were created using a "TruMark Station 1000" laser marking system from Trumpf Laser- und Systemtechnik GmbH, Germany. In all three examples, the track width was 50 µm and the laser power was 100%. In the first example ( Fig. 1a to 1c) the marking speed of the laser was 400 mm / s and the pulse frequency was 20,000 Hz, while in the second and third embodiments ( Fig. 2a, Fig. 2b, Fig. 3a, Fig. 3b) the speed of the laser was 50 mm / s and the pulse frequency was 50,000 Hz. List of reference symbols 10 taps 12 Cutting area 14 Peripheral side 16 cutting teeth 18 chip surface 20 chip flank 22 open space 124, 224, 324 Surface structuring 26 flute 28 edge A Longitudinal axis

Claims

[1] Tap (10) with a shank and a cutting area which are arranged along a longitudinal axis (A) of the tap, wherein the cutting area (10) has several cutting teeth (16) on its circumferential side (14) which are provided for the machining of threads in a borehole, wherein the cutting area has at least one rake surface (18) extending transversely to its circumferential side (14) which extends at least over associated chip flanks (20) of the cutting teeth (16), characterized by , that at least one rake surface (18) has at least one strip-shaped surface structuring (124, 224, 324) produced by a laser process, which extends at least over a partial area of ​​the chip flanks (20) of the incisal teeth (16). [2] Tap (10) according to claim 1, characterized by, that the striped surface structuring (124, 224, 324) has alternating adjacent elevations and valleys, wherein the valleys are produced by material removal and / or the elevations by material deposition, and / or wherein the elevations and valleys are produced by a redistribution of material. [3] Tap (10) according to claim 1 or 2, characterized by , that the striped surface structuring (124, 224, 324) comprises alternately adjacent areas of different structural structure. [4] Tap (10) according to claim 3, characterized by that the areas with different structural structures also differ in terms of their hardness. [5] Tap (10) according to any one of the preceding claims, characterized by , that the striped surface structuring (124, 224, 324) is formed as a pattern of parallel lines. [6] Tap (10) according to claim 5, characterized bythat the lines run straight. [7] Tap (10) according to any one of the preceding claims, characterized by , that the strip-shaped surface structuring (124, 224, 324) runs parallel to the longitudinal axis (A) of the tap (10). [8] Tap (10) according to any one of claims 1 to 6, characterized by , that the strip-shaped surface structuring (124, 224, 324) runs transversely to the longitudinal axis (A) of the tap (10). [9] Tap (10) according to claim 8, characterized by , that the strip-shaped surface structuring (124, 224, 324) runs perpendicular to the longitudinal axis (A) of the tap (10). [10] Tap (10) according to any one of the preceding claims, characterized by , that the strip-shaped surface structuring (224, 324) extends directly to edges (28) which define the chip flanks (20). [11] Tap (10) according to any one of claims 1 to 6, characterized by, that the strip-shaped surface structuring (124) of edges (28) which limit the chip flanks (20) is spaced apart. [12] Tap (10) according to any one of the preceding claims, characterized by , that the strip-shaped surface structuring (224, 324) provided on a respective chip surface (18) is formed as a continuous surface. [13] Tap (10) according to any one of claims 1 to 11, characterized by , that the strip-shaped surface structuring (124) provided on a respective chip surface (18) is divided into several spaced-apart sub-areas. [14] Tap (10) according to claim 13, characterized by , that the sub-areas only cover the chip flanks (20) of the incisors (16). [15] Tap (10) according to any one of the preceding claims, characterized by that the laser process is a laser marking process. [16] Method for producing a strip-shaped surface structuring (124, 224, 324) on a tap (10), wherein the tap has a shank and a cutting area (12) which are arranged along a longitudinal axis (A) of the tap (10), wherein the cutting area has several cutting teeth (16) on its circumferential side (14) which are provided for machining threads in a borehole, wherein the cutting area has at least one rake surface (18) extending transversely to its circumferential side (14) which extends at least over associated chip flanks (20) of the cutting teeth (16), wherein a laser beam is guided in several strip-shaped paths over at least one of the rake surfaces (18) in order to generate local changes in the material properties which form the strip-shaped surface structuring (124, 224, 324) by means of heat input.

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