Method for producing a tool, tool, method for machining a workpiece, workpiece

Abstract

The invention relates to a method for producing a tool for machining a workpiece. A metal tool blank (11) is provided in a laser machining device (14) which structures the tool blank on a tool surface by means of interference from at least two laser beams (17, 18). The at least two laser beams have at least temporary pulse durations of at most 15 ps, and by means of the structuring on the tool surface a tool profile (20) is generated having at least one indentation. The invention also relates to a tool structured in this manner, to a method for machining a workpiece by means of the tool, and to a workpiece machined in this way.

Description

[0001]Method for producing a tool, tool, method for machining a workpiece, workpiece The invention relates to a method for producing a tool for machining a workpiece and to a tool. In addition, the invention relates to a method for machining a workpiece and to a workpiece. The invention is concerned with the task of at least partially structuring a workpiece, in particular a metallic workpiece such as a component, with a topography in the lower micrometer and / or nanometer range. A large number of biological surfaces are structured in this size range, each of which produces its own unique functional surface properties, such as altered wetting (lotus, thorny devil), color effects (scales of butterfly wings), reduced friction (shark skin), reduced adhesion / active killing of germs and pathogens (wings of cicada and dragonfly).Topographies of this magnitude are therefore also referred to as biomimetic topographies. Many of these surface properties are influenced not only by the topography of the surface itself but also by surface chemistry. For industrial surface structuring of workpieces with topographies of this magnitude, it is currently only possible to process the workpieces directly using at least two interfering laser beams. Due to this essentially thermal processing method, the surface of the workpiece undergoes not only a topographical modification but also a chemical modification during processing, which can counteract the desired function or further processing of the workpiece.In this respect, the desired functionalization of the workpiece surface cannot always be guaranteed by direct processing with the interfering laser beams, especially in the case of metallic tools, since the thermal effect of the laser radiation is particularly pronounced here due to the electromagnetic absorption properties of metals. The object of the invention is therefore to develop a method for producing a tool with which an improved surface topography of the workpiece can be produced in industrial applications, in particular with which a micro- and / or nanoscale topographical surface functionalization of the workpiece can be realized, which enables expanded design options with reduced thermal and chemical influences on the workpiece compared to direct processing using laser interference.The same applies to the tool produced by the said method, to the method for machining a workpiece carried out with the tool, and to the workpiece itself machined in this respect. The object of the invention is achieved by a method for producing a tool for machining a workpiece according to claim 1, by a tool according to claim 12, by a method for machining a workpiece using the tool according to claim 15, and a machined workpiece according to claim 22.The method according to the invention for producing a tool for machining a workpiece provides that a metallic tool blank is provided in a laser machining device and the laser machining device structures the tool blank on a tool surface by means of interference of at least two laser beams, wherein the at least two laser beams at least temporarily have pulse durations of at most 15 ps and wherein the structuring on the tool surface produces a tool profile with at least one depression. The tool according to the invention is structured according to the method according to the invention. The method according to the invention for machining a workpiece using a tool provides that the tool is structured according to the method according to the invention, in particular that the tool is a tool according to the invention.The inventive method for machining the workpiece further provides that the workpiece is plastically deformed at least in some regions by means of the tool and is thereby provided with a workpiece profile that corresponds at least in some regions to the tool profile. The inventive workpiece is machined according to the inventive method. The invention is based on the fundamental idea that, in contrast to the already known direct structuring of the workpiece by means of interfering laser radiation, the tool is now first produced by the described structuring and then, in a subsequent step, the workpiece itself can be structured.The essential core of the invention is that interaction between the laser radiation and the workpiece surface to be structured is avoided, so that the disadvantageous chemical modification of the workpiece surface known from the prior art is avoided, while its desired functionality is retained or can be guaranteed in the first place. The invention creates the structuring of the workpiece surface, in particular a metallic substrate surface, for example in the lower micrometer and / or nanometer range, through plastic deformation, which has no effect on the surface chemistry. Thus, only the topography of the metallic substrate is modified, without influencing the basic chemical interaction with substances that come into contact with it, e.g. wetting by water or oils.The present invention makes a previously unattainable, purely topographical surface functionalization accessible for industrial application, which is particularly suitable for further processing of the surfaces via electroplating, PVD, etc. Investigations by the applicant have shown that the essentially plastic processing of the workpiece carried out within the scope of the invention does not result in any significant chemical modification of the workpiece, as was previously mandatory with the known prior art methods. For example, studies by the applicant have shown that the wetting properties of a workpiece processed according to the invention differ significantly from the wetting properties of a workpiece processed by direct laser interference structuring, which is attributable to the avoidance of chemical surface modification in the case of the invention.A further basic idea of ​​the invention is that by using interfering laser beams to produce the tool, a large tool surface can be processed in a short time by structuring it, thus improving the process efficiency of the method according to the invention. In particular, the tool can be provided with a full-surface surface structuring in the micrometer and / or nanometer scale range in a short processing time, which leads to significantly higher process efficiency and thus lower tool costs compared to other existing high-precision machining methods, such as focused laser or ion radiation. This advantage is particularly evident when compared to structuring the tool with just a single laser beam, which must be laboriously directed across the entire tool surface to be structured, making the process laborious and slow.Further advantages over direct structuring of the workpieces include, in particular, a greater variety of possible topographic geometries of the workpieces, for example, through partial molding with low contact pressure and multiple embossing with variable structuring of the tool, as well as the shorter process time for structures with a high depth or aspect ratio. The latter type of structure, in particular, can sometimes lead to very long process times with a purely ablative laser process, whereas embossing can achieve this in a single stroke. Since the workpiece is machined by the structured tool and no longer directly by laser radiation as with conventional processes, a significant improvement in occupational safety in industrial applications is also achieved.The inventive use of laser pulses with a maximum pulse duration of 15 ps largely avoids thermal effects during the interaction between the laser radiation and the tool surface, which in particular prevents the formation of melting and thermally induced material damage, especially stress cracks. It is known that with shorter pulse durations, thermal effects are increasingly neglected and the tool is increasingly mechanically processed. This effect is therefore also referred to as cold ablation. From this perspective, it can be provided that the maximum pulse duration of the laser beams is 10 ps, ​​so that even fewer thermal effects occur. In addition, the accuracy of the structure is improved.For the same reason, it is most preferably provided that the temporal pulse duration of the laser radiation is at most 1 ps, whereby an even better surface quality of the tool structuring can be achieved. A temporal pulse duration between 100 fs and 15 ps, in particular between 100 fs and 1 ps, is preferably provided. Furthermore, the power of the laser radiation can be between 1 W and 500 W and / or the energy of the pulses of the laser radiation can be between 10 µJ and 100 mJ. When generating the structuring according to the invention, between 10 and 1000 individual pulses can be superimposed in a spatial area in order to obtain high structural aspect ratios through a correspondingly high material removal. Furthermore, it can be provided that exactly two interfering laser beams are used to structure the tool.A further development of the invention provides for the use of three interfering laser beams, whereby, for example, a structuring of the tool with depressions in a hexagonal pattern can be created. In this case, the structuring has three axes along the surface, along which the depressions are each arranged in a lateral period, wherein, within the meaning of the invention, the lateral periods for the three axes are identical in the hexagonal pattern. In addition, four interfering laser beams can be used to create a square pattern of depressions when structuring the tool. Finally, it can be provided that a maximum of nine interfering laser beams are used.The tool can be a punching or forming tool, and the machining of the workpiece can accordingly be a punching or forming process, in particular a stamping process. Preferably, the at least one depression is produced with a dimension, in particular with a depth compared to an unstructured region of the tool surface, of between 10 nm and 50 µm, in particular between 100 nm and 15 µm. In further embodiments of the invention, it can be provided that the dimension of the depression corresponds to its length in the x and / or y direction, wherein, within the meaning of the invention, in the case of multiple depressions, the y direction corresponds to the offset direction of the depressions, while the x direction is arranged perpendicular thereto. The x and y directions are each perpendicular to the normal of the tool surface and thus each extend along the tool surface.For the purposes of the invention, a dimension can also be a combination of the x- and y-directions, which in this respect corresponds to a generally lateral direction. Preferably, at least two depressions with essentially identical dimensions, in particular with essentially identical depths, are produced. For the purposes of the invention, two dimensions have essentially identical dimensions if their deviations do not exceed the machining tolerance customary in comparable processes. At least two adjacent depressions can be arranged at a distance of 10 nm to 50 µm, in particular 100 nm to 15 µm. By means of the tool structured in this way, structural geometries in the order of magnitude between 10 nm and 50 µm, in particular between 100 nm and 15 µm, can be realized on the workpiece at an industrially relevant process speed while simultaneously ensuring reproducibility.Preferably, at least one group of depressions is created in a periodic pattern on the tool surface, since this structure can be created particularly easily using the interfering laser beams. In the context of the present invention, the period refers to the distance between two identical structural features of different depressions of the periodic pattern, for example the distance between the beginning of a first depression of the periodic pattern and the beginning of the adjacent depression of the same periodic pattern. Alternatively or additionally, the period within the meaning of the invention can refer to the distance between a center point of the first depression of the periodic pattern and the center point of the adjacent depression of the same periodic pattern.Since the depressions of the periodic pattern are laterally offset, the term lateral period is also used in the context of the invention, which, as already mentioned, refers to the distance between recurring structural features of adjacent depressions of the periodic pattern. In an advantageous development of the invention, it can be provided that the group of depressions in the periodic pattern on the tool surface is produced with a period between 10 nm and 50 µm, in particular between 100 nm and 15 µm, in at least one direction along the tool surface. A periodic structuring with a lateral period of this magnitude enables the formation of the advantageous surface functionalities mentioned above, with which the workpiece is ultimately also to be provided.The group of depressions in the periodic pattern can also have different periods in different directions, for example when three, four or more interfering laser beams are used to structure the tool. In an advantageous further development, the group of depressions in the periodic pattern has identical periods in two different directions. Furthermore, it can be provided that the group of depressions in the periodic pattern has identical periods in three different directions, which corresponds, for example, to a hexagonal arrangement of the depressions. The group of depressions is designed, for example, as a sinusoidal line structure in which depressions and elevations are each arranged one behind the other in the same lateral period.Preferably, at least one group of depressions is created on the tool surface with a linear profile and / or with a rectangular, preferably square basic shape and / or with a circular basic shape. The basic shape of the depressions can be polygonal, in particular hexagonal. As a special case, the depressions can be designed as lines, which can be arranged in particular offset perpendicular to the direction of extension and / or with a defined period. It is preferably provided that at least two first depressions, in particular a first group of depressions, are created with a first lateral period between 10 nm and 50 µm, in particular between 100 nm and 15 µm, and at least two second depressions, in particular a second group of depressions, are created with a second lateral period, wherein in particular the second lateral period is smaller than the first lateral period.The first lateral period can be between 100 nm and 999 µm. However, the second lateral period can also be larger than or identical to the first lateral period. The second group of depressions can be designed mathematically similar to the first group of depressions, so that the second group of depressions results from the first group of depressions by means of at least one mathematical similarity transformation, for example, translation, rotation, stretching, and / or scaling. Preferably, the second group of depressions corresponds to a 90° rotation of the first group of depressions about an axis perpendicular to the tool surface.Alternatively or additionally, it can be provided that at least two first depressions, in particular a first group of depressions, are produced with a first dimension between 10 nm and 50 µm, in particular between 100 nm and 15 µm, and at least two second depressions, in particular a second group of depressions, are produced with a second dimension, wherein the second dimension is in particular smaller than the first dimension. As already stated, the dimension of the depression within the meaning of the invention can correspond to its depth. In addition, it can be provided that, in addition to the second depressions, at least two third depressions, in particular a third group of depressions, are produced with a third lateral period and / or a third dimension, wherein the third lateral period and / or the third dimension are in particular smaller than the second lateral period and / or the second dimension.In further developments, up to ten groups of depressions can be created, each with a lateral period and / or dimension, wherein in particular the lateral period and / or the dimension of a group are always smaller than the lateral period and / or the dimensions of the previous groups. Preferably, the area of ​​the second depressions, in particular the second group of depressions, at least partially overlaps the area of ​​the first depressions, in particular the first group of depressions. The same applies to any third depressions that may be created, in particular the third group of depressions. Such an overlap makes it possible to combine structures with different lateral periods and / or dimensions with one another, in particular to modulate them mathematically, and to provide the tool with complex surface structures that are not possible with simple structuring.This expands the possibilities for surface functionalization of the tool, and thus also those of the workpiece. Preferably, the creation of the first depressions, in particular the first group of depressions, and the creation of the second depressions, in particular the second group of depressions, take place in a single work step or in separate work steps. The creation of the first depressions and the second depressions in a single work step increases the process speed. In contrast, the design of the creation of the first depressions and the second depressions in separate work steps includes, in particular, structuring the tool surface with different interference patterns. For example, it can be provided that the tool is moved between two work steps.Preferably, it can be provided that the tool rotates between two work steps, in particular by 90°, for example about an extension axis of the tool, so that depressions can be formed particularly easily, for example as cross-structure patterns and / or so-called Penrose structure patterns. The depressions of the second group can be arranged perpendicular to the depressions of the first group, so that the lateral period of the second group of depressions is arranged perpendicular to the lateral period of the first group of depressions. In addition, the lateral period of the second group of depressions can be aligned parallel to the lateral period of the first group of depressions or can enclose an angle between 0° and 180°.The second group of depressions is preferably created by a polarization of the laser beams selected depending on the material of the tool to be structured, whereby, in particular, laser-induced periodic surface structuring can be formed, in particular in a joint work step with the formation of the first group of depressions. The lateral period of the second group of depressions corresponds, for example, at most to the wavelength used for the laser beams. The polarization of the laser beams can be aligned linearly, wherein the polarization vector is arranged substantially perpendicular to the direction of extension of the laser-induced periodic surface structuring and / or parallel to the lateral period assigned to the laser-induced periodic surface structuring.In addition, the direction of the polarization vector of the laser beams can be aligned at an angle between 0° and 180° relative to the lateral period of the first group of depressions, so that the arrangement of the second group of depressions, in particular relative to the first group of depressions, can be adjusted by aligning the polarization vector of the laser beams. For example, it can be provided that the first depressions, in particular the first group of depressions, are generated by interference of the at least two laser beams, wherein the second depressions, in particular the second group of depressions, are generated by interference of at least two laser beams and / or by a single laser beam.This means that the first depressions are always created using interfering laser beams, whereas this does not necessarily have to be the case for the creation of the second depressions. Creating the second depressions using a single laser beam can be useful if the number of second depressions is small compared to the number of first depressions and / or if the area of ​​the second depressions is small compared to the area of ​​the first depressions. If the second depressions are also created using interfering laser beams, it can be provided that the number of interfering laser beams differs from or is identical to the number used to create the first depressions.Preferably, the tool blank is coated before structuring and / or the tool is coated after structuring, for example with a hard material layer, in particular with a carbon layer. Most preferably, an amorphous carbon layer is used as the coating. After structuring the tool, further surface functionalization can take place, for example by means of thermal processes and / or by chemical vapor deposition (CVD) and / or by physical vapor deposition (PVD), for example to smooth the surface of the tool by removing unwanted substructures or roughness. In a further embodiment, it can be provided that the tool surface is polished before structuring. The tool preferably has at least one component made of a hard metal that has a plurality of hard material particles and a binder matrix.Cemented carbides are metal matrix composite materials, also known as cemented carbide composite materials. The hard material particles present in the cemented carbide contain at least one member from the group consisting of diamond, nitride, carbide, or oxide. They exhibit comparatively high hardness but comparatively low toughness. For improved processability, the hard material particles are embedded in a binder matrix containing at least one member from the group consisting of cobalt, nickel, molybdenum, or a combination, which increases the ductility of the resulting cemented carbide. Cemented carbides are harder than pure metals, alloys, and hardened steels and therefore exhibit greater wear resistance, which also applies to tools with a cemented carbide component.According to the invention, the metallic tool blank can comprise or consist of a component made of a hard metal composite, which, for example, comprises a ceramic-metal composite. The tool blank preferably comprises a component made of tungsten carbide-cobalt hard metal (WC-Co), which can optionally contain components made of vanadium carbide (VC), chromium carbide (Cr3C2) and / or tantalum niobium carbide. The tool can have a coating made of a hard metal material and / or diamond and / or amorphous carbon. Alternatively or additionally, the tool preferably comprises at least one component made of a thermally treated tool steel. By selecting the thermal treatment, the properties of the tool steel can be adapted to the use of the tool. For example, the tool comprises a component made of tempered tool steel.The tool can have a hard material layer, preferably a carbon layer, most preferably a tetrahedral, hydrogen-free carbon layer, at least in some areas on the tool surface. In particular, the tool surface has an amorphous carbon layer, which is also referred to as DLC (diamond-like carbon). Alternatively or additionally, the carbon layer can have a graphite layer and / or a diamond layer. By forming a carbon layer on the tool surface, the surface of the tool can be further functionalized; in particular, the friction and wear properties of the tool can be optimized for tribological applications. The method according to the invention for machining the workpiece can provide that the plastic deformation of the workpiece takes place by the tool being pressed oris pressed, in particular with a user-defined offset and / or with a user-defined press-in pressure. The resulting workpiece profile is thus created by pressing, spinning, or embossing. The tool according to the invention can be integrated into an industrial press. Due to the simple process design via the adjustment of the press-in pressure, the structural depth and / or the structural geometry of the workpiece profile can be varied very easily and efficiently, which is of particular interest for tribological applications. In addition, by adjusting the press-in pressure, variable aspect ratios can be achieved when structuring the workpiece with negligible changes in process times.The workpiece profile is, in particular, at least partially mathematically similar, for example, at least partially complementary to the tool profile, which, within the meaning of the invention, means that the workpiece profile corresponds at least to a partial negative impression of the tool profile. In particular, the workpiece profile is an at least partial, in particular complete, impression of the tool profile. Since the machining of the workpiece is carried out based on the geometry of the structuring of the tool, essentially identical structures can be created on different workpiece materials. Preferably, the workpiece to be machined is fed to the tool, in particular by means of a belt guide.An advantageous development of the invention can provide that the workpiece, at least in the area associated with the tool, is plastically deformed in a single machining step, whereby the workpiece profile is provided with a structure that is at least partially complementary to the tool profile. Complete machining of the workpiece can be achieved by successively moving the tool laterally relative to the workpiece surface after a machining step and then machining the workpiece again in a single machining step.Preferably, the workpiece is plastically deformed by means of the tool in at least two machining steps, wherein in a first machining step the tool plastically deforms the workpiece along a machining axis with a first machining depth and wherein in a second machining step the tool plastically deforms the workpiece along the machining axis with a second machining depth and wherein in particular the first machining depth differs from the second machining depth. The second machining depth is in particular smaller than the first machining depth. Several machining steps with corresponding machining depths can be provided, wherein the machining depth of one machining step is in particular smaller than the machining depth of the previous machining step. The machining axis is preferably aligned perpendicular to the workpiece surface.By repeatedly machining the workpiece with different machining depths, which correspond, for example, to press-in depths, complex workpiece topographies can be produced that cannot be manufactured with a single machining step. In another embodiment of the invention, the second machining depth can be identical to the first machining depth. It can be provided that the same tool is used in two machining steps, wherein the tool is moved in translation and / or rotation between the two machining steps. Preferably, the tool is moved by 90° between the two rotation steps, in particular about an extension axis of the tool. In a further embodiment of the invention, the tool is moved in translation, in particular between the machining steps, successively over the entire area of ​​the workpiece to be structured.For this purpose, for example, a suitable tool guide can be designed. Preferably, the first machining step is carried out with a first tool and the second machining step with a second tool, wherein the first tool and / or the second tool were manufactured using the method according to the invention. Preferably, both tools were manufactured using the method according to the invention. In a further development of the invention, it can be provided that the structuring of the tool surfaces of the tools differ from one another at least in some regions. By machining the workpiece using two different tools, in particular with two different or identical machining depths, complex surface topographies can be produced, such as surface topographies that correspond to combinations, in particular in the mathematical sense modulations of topographies of different magnitudes.In addition, further processing steps using tools can be provided, wherein the tools were preferably produced using the method according to the invention. Preferably, the second tool has a periodic structure with a lateral period that is in particular smaller than the lateral period of the periodic structure of the first tool, which in the sense of the invention comprises the dimensions of the structure as well as its lateral period. Thus, it is provided in particular that the periodic structure of the second tool has a smaller lateral period than the periodic structure of the first tool. The lateral period of the periodic structure of the second tool can also be greater than or identical to the lateral period of the periodic structure of the first tool.Preferably, the press-in pressure of one processing step differs from the press-in pressure of another processing step, for example to provide the workpiece with a complex surface topography even with the structuring of a single tool. The press-in pressure used is preferably between 100 MPa and 100,000 MPa, whereby the specifically used press-in pressure is to be selected depending on the mechanical strength of the workpiece to be machined. In a further embodiment of the invention, the press-in pressure of one processing step is identical to the press-in pressure of another processing step. Preferably, the workpiece is plastically deformed by means of a vibrating movement of the tool, in particular along the processing axis. The frequency of the vibration is preferably between 20 kHz and 10 GHz and is thus in the ultrasonic range.Findings by the applicant have shown that the vibration of the tool during the pressing process reduces the springback of the workpiece material, so that the molding of the structuring of the tool onto the workpiece is improved. The workpiece is preferably machined using the tool at a temperature of at most 1200°C, in particular free from external heat input. The workpiece according to the invention preferably has a structuring that is at least partially similar to, and in particular at least partially complementary to, the structuring of the tool. The workpiece in particular has a component made of brass (CuZn) with in particular a zinc content of essentially 30% (CuZn30), which has particularly pronounced plastic deformability.Further advantages and features of the invention emerge from the claims and from the following description, in which an embodiment of the invention is explained in detail with reference to the drawings. In the drawings: Fig. 1 shows a schematically illustrated embodiment of the method according to the invention for producing a tool and a tool according to the invention, Fig. 2 shows a schematically illustrated embodiment of the method according to the invention for machining a workpiece and a workpiece according to the invention, Fig. 3 shows a further embodiment of the method according to the invention for producing a tool and a tool according to the invention, Fig. 4 shows a further embodiment of the method according to the invention for machining a workpiece and a workpiece according to the invention, Fig. 5 shows a further embodiment of the method according to the invention for producing a tool and a tool according to the invention, Fig.6 shows a further embodiment of the method according to the invention for machining a workpiece and a workpiece according to the invention, Fig. 7 shows a further embodiment of the method according to the invention for producing a tool and a tool according to the invention, Fig. 8 shows a further embodiment of the method according to the invention for machining a workpiece and a workpiece according to the invention, Fig. 9 shows a further embodiment of the method according to the invention for producing a tool and a tool according to the invention, Fig. 10 shows a further embodiment of the method according to the invention for machining a workpiece and a workpiece according to the invention, Figs. 11 to 14 show a further embodiment of the method according to the invention for producing a tool, the tool according to the invention, and a further embodiment of the method according to the invention for machining a workpiece and the workpiece according to the invention, Fig.15, 16 show a further embodiment of the method according to the invention for machining a workpiece and the workpiece according to the invention, and Fig. 17, 18 show a further embodiment of the method according to the invention for machining a workpiece and the workpiece according to the invention. Fig. 1 shows an embodiment of the method according to the invention for producing a tool 10 using three images of the tool 10. In Fig. 1, the left-hand illustration shows the tool 10 in its still unmachined state as a tool blank 11, which in the exemplary embodiment shown is essentially a cylinder made of tungsten carbide-cobalt hard metal (WC-Co) and was produced via spark erosion. The subsequent machining of a workpiece 12 is to take place through the cover surface 13 of the tool 10, so that the cover surface 13 of the tool blank 11 is provided with a surface shown in Fig.1, which is also referred to as diamond-like carbon (DLC). For the inventive production of the tool 10, the tool blank 11 is provided in a laser processing device 14, which is only shown schematically in the central illustration of Fig. 1 for reasons of clarity. The laser processing device 14 has an optics module 15, which splits an incident laser beam in the exemplary embodiment shown in Fig. 1 into two partial beams 17, 18 and directs them in the direction of the cover surface 13 of the tool blank 11 to be structured as the tool surface 13. Depending on the application, up to nine laser beams can be used as partial beams. In the exemplary embodiment shown, pulsed laser radiation with pulse durations of 1 ps, thus ultrashort pulses, and with a pulse energy of 100 µJ is used.The two partial beams 17, 18 directed toward the tool blank 11 are aligned at a finite angle to one another such that the partial beams 17, 18 interfere with one another in an interference region 19. The tool blank 11 is arranged in the laser processing device 14 such that the interference region 19 is arranged essentially on the top surface 13 of the tool blank 11 as the working surface. The interference pattern formed by the interfering partial beams 17, 18 depends essentially on the angle formed by the partial beams 17, 18, their polarization, and the wavelength of the laser radiation used, so that the interference pattern can be adapted as needed by changing these parameters.The impacting, interfering partial beams 17, 18 structure the top surface 13 of the tool blank 11, with the structuring essentially corresponding to the intensity maxima of the interference pattern. Through the use of ultrashort pulsed laser radiation, the structuring of the tool 10, and thus its manufacture, is essentially purely ablative, i.e., without introducing heat into the top surface 13 of the tool blank 11, since the pulse duration of the laser radiation is so short that no thermal interaction of the laser radiation with the material of the tool blank 11 occurs. In this respect, this type of processing is also referred to as cold ablation. This allows comparatively fine structural patterns in the micro- and / or nanoscale range to be realized while simultaneously avoiding thermal tool damage.Due to the interfering partial beams 17, 18, topographical structures form in the interference region 19, creating a structuring of the top surface 13 of the tool blank 11. For structuring, 50 pulses are superimposed in the illustrated embodiment. If structuring of the tool blank 11 beyond the interference region 19 of the partial beams 17, 18 is desired, the tool blank 11 can be moved relative to the interference region 19, which includes translational and / or rotational movements and is illustrated by the arrows shown in gray in Fig. 1. For this purpose, the laser processing device 14 is designed such that the interference region 19 of the partial beams 17, 18, which in this respect corresponds to a focus region, is movable relative to the cover surface 13 of the tool blank 11 to be structured.For example, this is achieved by deflecting the two partial beams 17, 18 by means of mirrors controlled by servo motors in the sense of F-theta optics (not shown in Fig. 1). Alternatively or additionally, the tool blank 11 can be moved in translation, for example, by linear guides not shown in Fig. 1. With appropriate guidance, a rotation of the tool blank 11 relative to the laser processing device is also possible in this way, in particular about its axis of extension. By moving the interference region 19 relative to the cover surface 13 of the tool blank 11, a structuring of the cover surface 13 beyond the interference region 19 is possible by successively processing the cover surface 13 by means of the interfering partial beams 17, 18, in particular by scanning part or all of it. In the embodiment of Fig.1, the structuring leads to a tool profile 20 of the tool 10, and thus to a surface topography with linear structural elements 21, which are shown greatly enlarged in the right-hand illustration in Fig. 1 for reasons of clarity. The tool profile 20 of the cover surface 13 of the tool 10 perpendicular to the direction of extension of the structural elements 21 corresponds approximately to a sinusoidal course, in which depressions 22 and elevations 23 of the same size are arranged one behind the other at a fixed distance Δd, which is referred to as the lateral period in the sense of the invention, and wherein there is a continuous transition between the depressions 22 and elevations 23; this is illustrated in Fig. 1 by solid lines. The lateral period Δd between a depression 22 and an adjacent depression 22 is 10 μm in the exemplary embodiment shown.The elevations 23 are arranged in the same lateral period ∆d. The tool 10 shown on the right in Fig. 1 is provided with linear structural elements 21 over its entire surface 13 and is thus finished. The finished tool 10 shown on the right in Fig. 1 is then used as a stamping tool or stamping die in a stamping device not shown in Fig. 2 and is placed opposite the workpiece 12 to be machined so that the top surface 13 of the tool 10 faces the workpiece 12. In the embodiment of Fig. 2, the workpiece 12 is a sheet made of brass (CuZn30). By pressing the tool 10 with the aforementioned tool profile 20 with a contact pressure of 1.500 MPa is applied to the workpiece 12, thereby along a machining axis 24 arranged perpendicular to the workpiece surface 13, an at least partial molding of the tool profile 20 onto the workpiece 12 takes place as a plastic deformation, wherein the workpiece 12 is provided with a workpiece profile 25 that corresponds at least partially to the tool profile 20, in particular is at least partially complementary to it. In the left-hand illustration of Fig. 2, the machining axis 24 is indicated by a large gray arrow. In the embodiment shown, a full-surface structuring of the workpiece 12 is desired, wherein the structured cover surface 13 of the tool 10 is significantly smaller than the surface of the workpiece 12 to be structured. Therefore, after this processing step, the tool 10 is moved relative to the workpiece 12, whereupon a new embossing takes place with the aforementioned contact pressure.This process is then repeated until the workpiece 12 is structured over its entire surface. This process is also referred to as stitching and is illustrated in the left-hand illustration by the small grey arrows. The fully structured workpiece 12 is shown on the right in Fig. 2, from which it can be seen that the workpiece profile 25 is at least partially complementary to the tool profile 20 in that the workpiece profile 25 has depressions 22 which are arranged in the same lateral period Δd as the depressions 22 of the tool profile 20. Fig. 3 shows a further possibility for producing a tool 10 with a tool profile 20 which differs from that of the embodiment in Fig. 1. For this purpose, the tool 10 is initially processed as a tool blank 11 by means of the laser processing device 14 in a manner similar to the embodiment in Fig.1 is provided on its top surface 13 over its entire surface with a tool profile 20 with linear structural elements 21 as first depressions 22, so that in this regard, reference is made to the above statements to avoid repetition. In contrast to the exemplary embodiment in Fig. 1, the pulse energy of the laser radiation is 80 µJ and 20 individual pulses are superimposed for structuring. The resulting first tool profile 20 in the third illustration in Fig. 3 is qualitatively similar to the tool profile 20 according to Fig. 1, but in contrast to this, has a smaller lateral period ∆d of 6 µm. After this first structuring, the tool 10 is in the transition from the one shown in Fig.3 third representation to the fourth representation rotated by 90° about its extension axis A and again provided in the laser processing device 14, so that a further, full-surface structuring of the cover surface 13 is subsequently carried out with the same parameters of the first structuring. As a result, the tool 10 shown on the right in Fig. 3 has a tool profile 20 with a columnar structuring with elevations 23, which are arranged one behind the other in a first direction R1 with a first lateral period Δd of 6 μm, and which are also arranged one behind the other in a second direction R2, which is arranged perpendicular to the first direction R1, with a second lateral period Δd of likewise 6 μm.Since two adjacent elevations 23 of the tool profile 20 are each separated by a depression 22, the tool profile 20 has first depressions 22 along the first direction R1, which are arranged in the first lateral period Δd, and second depressions 22 along the second direction R2, which are arranged in the second lateral period Δd, whereby only one lateral period Δd is shown in Fig. 3. The area of ​​the second depressions 22 overlaps the area of ​​the first depressions 22 and the first depressions and the second depressions 22 are produced in separate work steps. The tool 10 shown on the right in Fig. 3 is placed as a stamping die opposite the workpiece 12 to be machined according to Fig. 4, whereby the cover surface 13 faces the workpiece 12. The machining of the workpiece 12 by the tool 10 is carried out by a contact pressure of 1.200 MPa along the machining axis 24, so that the columnar tool profile 20 is partially molded complementarily onto the workpiece 12, with the result that the workpiece 12 has a workpiece profile 25 with depressions 22 which, similar to the elevations 23 of the tool 10, are arranged one behind the other in two mutually perpendicular directions R1, R2, each with a lateral period ∆d of 6 µm. The full-surface machining of the workpiece 12 takes place as already described in connection with Fig. 2 in the sense of stitching, which is illustrated by the gray arrows in the left-hand illustration of Fig. 4. The right-hand illustration in Fig. 4 shows the workpiece 12 machined over its entire surface with the tool 10 with the workpiece profile 25 already mentioned. In the embodiment in Fig. 5, the structuring of the tool 10 as a tool blank 11 takes place in two processing steps, similar to the embodiment in Fig. 3.First, the cylindrical tool blank 11 made of tungsten carbide-cobalt hard metal (WC-Co) is provided in the laser processing device 14, which structures the top surface 13 of the tool blank 11 with a first group of recesses 22 in a first processing step. This first processing step is carried out using laser radiation with a pulse duration of 100 fs and a pulse energy of 20 µJ, with three partial beams 17, 18, 26 interfering with one another and ten individual pulses being superimposed. The laser processing device 14 is then moved relative to the tool blank 11 in such a way that structuring occurs again until the entire top surface 13 of the tool blank 11 is structured and the tool profile 20 shown in the central illustration of Fig. 5 is formed.Due to the aforementioned structuring parameters, the tool profile 20, after structuring the tool 10, has a periodic arrangement of depressions 22, also called sinks. The tool profile 20 has three axes along the top surface 13 of the tool 10, along which axes the depressions 22 are arranged in the same lateral period ∆d, the lateral periods ∆d of the depressions 22 each being 1 µm. For the purposes of the invention, this arrangement of depressions 22 is also referred to as a hexagonal arrangement. The fully structured tool 10 after the first work step is shown in the central illustration of Fig. 5, wherein the dimensions of the depressions 22 are not shown to scale but greatly enlarged for reasons of clarity.In a subsequent work step, the tool profile 20 is provided with a further structure, the area of ​​which overlaps the area of ​​the first structure. For this purpose, the parameters of the laser processing device 14 are changed so that the second structure is carried out using laser radiation with a pulse duration of 100 fs, a pulse energy of 30 µJ, and two interfering laser beams 17, 18, wherein the structure is carried out by a superposition of ten pulses before the laser processing device 14 is moved relative to the tool 10 in the manner already mentioned in order to structure the tool 10 over its entire surface. The second structure of the tool results in the formation of linear structural elements 21 as depressions 22, which are arranged one behind the other with a lateral period ∆d of 2 µm.By superimposing the first structuring with the hexagonally arranged depressions 22 in a first lateral period ∆d of 1 µm with the second structuring with linear structural elements 21 in a second lateral period of 2 µm, the tool profile 20 has a periodic, but at the same time hierarchical structuring, which is shown in the right-hand illustration of Fig. 5, and which has the linear depressions 22 according to the second structuring as the dominant element, wherein in the areas not machined as part of the second structuring, the hexagonal arrangement of the depressions 22 according to the first structuring is formed with a smaller lateral period ∆d compared to the second structuring.5, the tool 10 is placed opposite a brass sheet (CuZn30) to be stamped, serving as the workpiece 12. The tool 10 is then applied to the workpiece 12 along the machining axis 24 with a contact pressure of 3,500 MPa, while the tool 10, acting as a stamping die, is vibrated at a frequency in the ultrasonic range to optimize the stamping process. This results in a complete stamping of the tool profile 20 onto the workpiece 12, which thus has a workpiece profile 25 complementary to the tool profile 20. Due to the smaller surface of the tool 10 compared to the surface of the workpiece 12, the full-surface structuring of the workpiece 12 is achieved by successively moving the tool 10 relative to the workpiece 12 in the sense of the aforementioned stitching, which is represented by the gray arrows in the left-hand illustration of Fig. 6. The finished, fully structured workpiece 12 is shown in Fig.6 is shown on the right, wherein, as already mentioned, the workpiece profile 25 is designed to complement the tool profile 20. Fig. 7 shows a further embodiment of the method for producing the tool 10 by structuring a cylindrical tool blank 11 made of a tungsten carbide-cobalt hard metal (WC-Co), in which the blank is provided in the laser processing device 14, similar to the previous embodiments. The structuring is carried out using linearly polarized laser radiation with a pulse duration of 5 ps and a pulse energy of 50 µJ, with 200 pulses being superimposed for structuring. According to the left illustration of Fig. 7, it can be seen that the structuring is carried out by means of two partial beams 17, 18 which interfere with one another, wherein the linear polarization P of the partial beams 17, 18 is selected in such a way that the polarization plane is arranged parallel to the cover surface 13 of the tool blank 11 to be structured.As a result of the structuring of the tool blank 11, the tool profile 20 has sinusoidal, linear structural elements 21 as a group of depressions 22, which are arranged one behind the other in a lateral period ∆d of 6 µm, similar to the exemplary embodiment in Fig. 1. In the exemplary embodiment in Fig. 7, this - primary - structuring is superimposed by a further - secondary - structuring, which is formed due to the polarization of the interfering partial beams 17, 18. This secondary structuring arises due to the linear polarization of the partial beams 17, 18 described above and causes the additional generation of likewise linear structural elements 21 as a further group of depressions 22, which have structural sizes, in particular a lateral period ∆d, which approximately corresponds at most to the wavelength of the laser radiation used.The depressions 22 of the secondary structuring are arranged essentially at an angle of 0° relative to the linear polarization of the partial beams 17, 18 and at an angle of 90° relative to the depressions 22 of the primary structuring. The extension directions of the linear structural elements 21 of the secondary structuring are therefore arranged essentially perpendicular to the polarization of the partial beams 17, 18. The production of the first group of depressions 22 as primary structuring and the second group of depressions 22 takes place in a single work step by the aforementioned superposition of 200 pulses and due to the polarization of the partial beams 17, 18. The tool 10 is structured over its entire surface in the manner already mentioned; the fully structured tool 10 is shown in the right-hand illustration of Fig. 7. With the device according to Fig.7, a sheet of brass (CuZn30) is then machined as a workpiece 12 according to the left illustration of Fig. 8, in which the tool 10 is pressed onto the workpiece 12 as a stamping die with a contact pressure of 2,000 MPa along the machining axis 24, wherein at the same time the tool 10 is vibrated with frequencies in the ultrasonic range along the machining axis 24 in order to optimize the molding process.The tool profile 20 is thus not molded in its entirety, but only partially as a complementary structure onto the workpiece profile 25, wherein the workpiece profile 25 has the primary structuring with the linear structural elements 21 arranged one behind the other in a lateral period ∆d of 6 µm, and also the secondary structuring superimposed thereon with the linear structural elements 21 arranged perpendicular to the first structuring with dimensions that are essentially smaller than the wavelength of the laser radiation. To the applicant's knowledge, the creation of this - superimposed - structuring as a workpiece profile 25 on brass (CuZn30) is not possible with direct processing using laser radiation, but only with the molding process described above, since in the latter case, no melting dynamics occur when creating the structuring on the workpiece profile.The machining of the workpiece 12, and thus the creation of the superimposed structuring on the workpiece profile 25, takes place in a single pressing or embossing step. The full-surface structuring of the workpiece 12 then takes place in the sense of stitching, as already described. The fully structured workpiece 12 is shown on the right in Fig. 8. Fig. 9 shows a further embodiment of the invention, in which the tool blank 11 is structured analogously to the embodiment in Fig. 7, in particular also with laser radiation with a pulse duration of 5 ps and a pulse energy of 50 µJ.The structuring is carried out by means of two interfering partial beams 17, 18, wherein the linear polarization P of the partial beams 17, 18 is selected such that the polarization axes of the partial beams 17, 18 again each enclose an angle of 0° relative to the top surface 13 of the tool blank 11 to be structured; the polarization axes of the partial beams 17, 18 are therefore each aligned parallel to the top surface 13 of the tool blank 11 and also perpendicular to the polarization axes of the partial beams 17, 18 in the embodiment of Fig. 7. Analogous to the embodiment of Fig. 7, the structuring of the tool blank 11 is carried out by a superposition of 200 laser pulses. The fully structured tool 10 is shown in Fig.9 on the right, wherein the tool profile 20 thereof has a primary structuring with a first group of sinusoidal, line-shaped structural elements 21 as depressions 22, which are arranged in a lateral period ∆d of 6 µm and in this respect corresponds to the primary structuring of the embodiment according to Fig. 7. Due to the linear polarization P of the partial beams 17, 18, the tool profile 20 has a secondary structuring with line-shaped structural elements 21, which overlay the primary structure and which are formed in the order of magnitude of at most the wavelength used. Due to the alignment of the linear polarization vectors P of the partial beams 17, 18, the secondary structuring with the line-shaped structural elements 21 as depressions 22 is arranged parallel to the direction of extension of the primary structuring and thus perpendicular to the secondary structuring of the embodiment according to Fig. 7.The structuring of the tool blank 11, including the primary and secondary structuring, takes place in a single work step. Fig. 9 shows the fully structured tool 10 on the right. With the tool 10 manufactured according to Fig. 9, the workpiece 12, here an example of a sheet made of brass (CuZn30), is machined and structured as shown in Fig. 10. The structuring is achieved by a contact pressure of the tool 10 on the workpiece of 2,000 MPa along the machining axis 24 and a simultaneous vibration of the tool 10 along the machining axis 24 at a vibration frequency in the ultrasonic range. This results in a partial molding of the tool profile 20 onto the workpiece profile 25, wherein the workpiece profile 25 has a structure complementary to the tool profile 20, so that reference is made in this regard to the above description of the tool profile 20 according to Fig. 9.The full-surface machining of the workpiece 12 takes place by means of the stitching process already described, which is shown by the gray arrows in the right-hand illustration of Fig. 10. The fully machined workpiece 12 is shown on the right in Fig. 10. Figs. 11 to 14 show a further embodiment of the invention. According to Fig. 11, a tool blank 11 made of a tungsten carbide-cobalt hard metal (WC-Co) is provided with a tool profile 20 with linear structural elements 21 as depressions 22 with a lateral period ∆d of 10 µm, analogous to the embodiment in Fig. 1. With the tool 10 thus produced, a full-surface structuring of a sheet of brass (CuZn30) as workpiece 12 is then carried out in a first processing step, as already described in connection with Fig. 2, wherein, in deviation from the embodiment of Fig. 2, a contact pressure of 1,000 MPa is now used along the processing axis 24.The fully structured workpiece 12 is shown on the right in Fig. 12. After the full-surface structuring of the workpiece 12, the tool 10 is rotated by 90° around its extension axis A according to Fig. 13 such that the linear structural elements 21 are now aligned perpendicular to the structural elements 21 of the workpiece 12. This is shown in the right-hand illustration of Fig. 13. In this orientation, the tool 10 is subjected to a contact pressure of 1,000 MPa along the extension axis 24 on the workpiece 12 in a second processing step, so that a superimposed structuring of the workpiece 12 is formed as a workpiece profile 25, which can be seen as a checkerboard pattern in the exemplary embodiment shown. Fig. 14 shows the workpiece 12 on the left that has not yet been fully structured in the second processing step.The full-surface structuring of the workpiece 12 is achieved by the stitching already explained; the fully structured workpiece 12 is shown on the right in Fig. 14. The – superimposed – structuring of the workpiece profile 25 is therefore obtained by a single tool 10 with a single, primary structuring in two successive processing steps, wherein the tool 10 is rotated by 90° about its extension axis A between the processing steps. Figs. 15 and 16 show a further embodiment of the invention, which is based on a fully structured tool 10 according to Fig. 1 and which is shown in the left-hand illustration of Fig. 15. The tool profile 20 has linear structural elements 21 as depressions 22 with a depth of 10 µm compared to the unstructured area of ​​the cover surface 13, wherein the depressions 22 are arranged one behind the other in a lateral period ∆d of 10 µm.A brass sheet (CuZn30) as workpiece 12 is subjected to an initial contact pressure of 1,500 MPa along the machining axis 24 by the tool 10 produced in this way, as shown in the central illustration of Fig. 15. This results in an incomplete molding of the tool profile 20 onto the workpiece profile 25, with only half of the structural depth of the tool profile 20, which is referred to as the machining depth in the sense of the invention. The machining depth therefore does not correspond to the full depth of the recesses 22 of the tool profile 20. As a result, the workpiece profile 25 has comparatively sharp-edged plateaus, each with a width of 5 µm, which are separated from one another by grooves as recesses 5 µm wide and 5 µm deep.To the applicant's knowledge, such a workpiece profile 25 cannot be produced by direct structuring using laser radiation, since the melting dynamics that occur in this process lead to a rounding of the workpiece profile and impair it. The full-surface structuring of the workpiece 12 is carried out by stitching; the fully structured workpiece 12 is shown on the right in Fig. 15. Fig. 16 illustrates a further embodiment of the processing of a sheet made of brass (CuZn30) as workpiece 12 with the workpiece 12 shown on the left in Fig. 15, wherein the structuring of the workpiece 12 is carried out with a contact pressure of 3,500 MPa along the processing axis 24, which is greater than with the method in Fig. 15, and with simultaneous vibration of the tool 10 as an embossing die with frequencies in the ultrasonic range along the processing axis 24.This results in a complete molding of the tool profile 20 onto the workpiece profile 25, so that the full structural depth of 10 µm of the tool profile 20 is molded. The machining depth of the method according to Fig. 16 is thus, due to the greater contact pressure, greater than the machining depth of the method according to Fig. 15. The workpiece profile 25 ultimately has a structure with sinusoidal, linear structural elements 21 that have a depth of 10 µm and a lateral period ∆d of 10 µm. The workpiece profile 25 is therefore corresponding, in particular complementary, to the tool profile 20. The full-surface structuring of the workpiece 12 is carried out by stitching and is shown as a result on the right in Fig. 16. Figures 17 and 18 illustrate a further embodiment of the method according to the invention for machining a workpiece 12, which is, for example, a sheet of brass (CuZn30).The tool 10 used for this purpose is shown on the left in Fig. 17 and has a tool profile 20 with a full-surface structure with columnar elevations 23, wherein a depression 22 is formed as a structural element 21 between two adjacent elevations 23. The depressions 22 themselves are arranged periodically one behind the other in two mutually perpendicular directions. In this respect, the tool profile corresponds to that of the exemplary embodiment according to Fig. 3. Quantitatively, and in contrast to the exemplary embodiment in Fig. 3, the depressions 23 each have a depth of 10 µm compared to the unstructured area of ​​the workpiece 10 and are arranged one behind the other in lateral periods ∆d of 10 µm each. The tool 10 is used as an embossing die with a comparatively low contact pressure of 1,000 N / mm², as shown in the center of Fig. 17.200 MPa along the machining axis 24 onto the workpiece 12, so that, as already described, only a partial molding of the tool profile 20 onto the workpiece profile 25 takes place. In the present exemplary embodiment, the tool profile 20 is only molded up to half of the structural geometry of 10 µm, which corresponds to the machining depth. This results in the workpiece profile 25 having sharp-edged depressions 22 with a diameter of 5 µm, wherein the depressions 22 are arranged in a cubic periodic pattern. To the applicant's knowledge, such workpiece profiles 22, in particular their sharp-edged depressions 22, cannot be produced by direct laser structuring. The full-surface machining of the workpiece 12 takes place by stitching, as already described. The fully machined workpiece 12 is shown on the right in Fig. 17. In Fig.18, another sheet of brass (CuZn30) is machined and structured as workpiece 12 with the embossing die as tool 10 according to Fig. 17, wherein, in contrast to Fig. 17, a comparatively high contact pressure of 3,500 MPa along the machining axis 24 is used with an additional vibration of the tool 10 during the embossing process with frequencies in the ultrasonic range in order to obtain the most complete possible molding of the tool profile 20 onto the workpiece profile 25. In the present embodiment, the tool profile 20 is molded to the full structural depth of 10 µm, resulting in a columnar topography whose recesses 22 have a depth of 10 µm and are arranged one behind the other in two mutually perpendicular, lateral periods ∆d of 10 µm each. The workpiece profile 25 is thus designed to complement the tool profile 20.The full-surface machining of the workpiece 12 is performed by stitching, as already described and indicated by the gray arrows in the left-hand illustration of Fig. 18. The fully machined workpiece 12 is shown on the right in Fig. 18.

Claims

Patent claims 1. Method for producing a tool (10) for machining a workpiece (12), in particular a punching or forming tool, in which a metallic tool blank (11) is provided in a laser machining device (14) and the laser machining device (14) structures the tool blank (11) on a tool surface (13) by means of interference of at least two laser beams (17, 18, 26), wherein the at least two laser beams (17, 18, 26) at least temporarily have pulse durations of at most 15 ps and wherein the structuring on the tool surface (13) produces a tool profile (20) with at least one depression (22).Method according to claim 1, characterized in that the at least one depression (22) is produced with a dimension, in particular with a depth relative to an unstructured region of the tool surface (13), of between 10 nm and 50 µm, in particular between 100 nm and 15 µm.

3. Method according to one of claims 1 or 2, characterized in that at least two depressions (22) are produced with substantially identical dimensions, in particular with substantially identical depths.

4. The method according to one of claims 1 to 3, characterized in that at least one group of depressions (22) is produced in a periodic pattern on the tool surface (13).

5. The method according to claim 4, characterized in that the group of depressions (22) is produced in the periodic pattern on the tool surface (13) with a lateral period (Δd) between 10 nm and 50 µm, in particular between 100 nm and 15 µm, in at least one direction along the tool surface (13).

6. The method according to one of claims 1 to 5, characterized in that at least one group of depressions (22) is produced on the tool surface (13) with a linear profile and / or with a rectangular, preferably square basic shape and / or with a circular basic shape.Method according to one of claims 1 to 6, characterized in that at least two first depressions (22), in particular a first group of depressions (22), are produced with a first lateral period (∆d) between 10 nm and 50 µm, in particular between 100 nm and 15 µm, and at least two second depressions (22), in particular a second group of depressions (22), are produced with a second lateral period (∆d), wherein in particular the second lateral period (∆d) is smaller than the first lateral period (∆d).

8. The method according to claim 7, characterized in that the region of the second depressions (22), in particular of the second group of depressions (22), at least partially overlaps the region of the first depressions (22), in particular of the first group of depressions (22).

9. The method according to one of claims 7 or 8, characterized in that the production of the first depressions (22), in particular of the first group of depressions (22), and the production of the second depressions (22), in particular of the second group of depressions (22), take place in a single work step or in separate work steps. 10.Method according to claim 9, characterized in that the first depressions (22), in particular the first group of depressions (22), are produced by means of interference of the at least two laser beams (17, 18, 26), wherein the second depressions (22), in particular the second group of depressions (22), are produced by means of interference of at least two laser beams (17, 18, 26) and / or by means of a single laser beam (17, 18, 26).

11. Method according to one of claims 1 to 10, characterized in that the tool blank (11) is coated before and / or the tool (10) is coated after structuring.

12. Tool (10), in particular a punching or forming tool, structured according to a method according to claims 1 to 11.

13. Tool (10) according to claim 12, characterized in that the tool (10) has at least one component made of a hard metal comprising a plurality of hard material particles and a binder matrix, and / or at least one component made of a thermally treated tool steel.

14. Tool (10) according to one of claims 12 or 13, characterized in that the tool (10) has, at least in some regions on the tool surface (13), a hard material layer, preferably a carbon layer, most preferably a tetrahedral, hydrogen-free carbon layer.Method for machining a workpiece (12) by means of a tool which is produced by a method according to one of claims 1 to 11, in particular by means of a tool (10) according to one of claims 12 to 14, wherein the workpiece (12) is plastically deformed at least in regions by means of the tool (10) and is provided with a workpiece profile (25) which corresponds at least in regions to the tool profile (20).

16. Method according to claim 15, characterized in that the workpiece (12) is plastically deformed by means of the tool (10) in at least two machining steps, wherein in a first machining step the tool (10) plastically deforms the workpiece (12) along a machining axis (24) with a first machining depth and wherein. in a second machining step, the tool (10) plastically deforms the workpiece (12) along the machining axis (24) with a second machining depth, and wherein in particular the first machining depth differs from the second machining depth.

17. The method according to claim 16, characterized in that the first machining step is carried out with a first tool (10) and the second machining step is carried out with a second tool (10), wherein the first tool (10) and / or the second tool (10) were manufactured using a method according to one of claims 1 to 11.

18. The method according to claim 17, characterized in that the second tool (10) has a periodic structure with a lateral period (Δd) which is in particular smaller than the lateral period (Δd) of the periodic structure of the first tool (10). 19.Method according to one of claims 16 to 18, characterized in that the pressing pressure of one processing step differs from the pressing pressure of another processing step.

20. Method according to one of claims 15 to 19, characterized in that the workpiece (10) is plastically deformed by means of a vibrating movement of the tool (10), in particular along the processing axis (24).

21. The method according to any one of claims 15 to 20, characterized in that the workpiece (12) is machined by means of the tool (10) at a temperature of at most 1200°C, in particular free from external heat input.

22. A workpiece (12) machined using a method according to any one of claims 15 to 21.

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