Extrusion tool with color effect and method for manufacturing an extrusion tool with color effect

Abstract

The invention relates to a method for producing an extrusion tool (4), wherein an extrusion tool (4) is provided, which has an extrusion face (5) configured for contacting a workpiece (6), and wherein at least one defined structure region (A, B) of the extrusion face (5) is irradiated by means of an ultrashort-pulse laser having a pulse duration of ≤ 10 picoseconds, in which defined structure region (A, B) a periodic three-dimensional structure (11) having an average structure period (P) of P ≤ 1.5 micrometers and an average structure depth (T) of T ≤ 1 micrometer is produced.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an extrusion tool and to an extrusion tool comprising an extrusion surface for contacting a workpiece, wherein the extrusion surface has a structured surface in at least one defined structural region, which can be transferred onto the workpiece by pressing. Furthermore, this invention relates to the application of such an extrusion tool and workpieces comprising wood, particularly coated wood, or plastic having a surface that includes a structured surface in at least one defined structural region. Background Technology

[0002] This type of workpiece—which includes wood, coated wood, or plastic—is, for example, laminate flooring or laminated material boards used in the furniture industry. It is known that the visible surfaces of such workpieces are structured to mimic, for example, certain natural surfaces. For example, structured surfaces that mimic the surfaces of concrete, stone, etc., can be achieved. Different methods are known to produce such structured surfaces, such as laser removal or etching methods.

[0003] Document EP 2 289 708 B1 discloses, for example, a method for manufacturing surface structures of metal pressure plates, continuous belts, or cylindrical pressure rollers using lasers.

[0004] Besides mimicking natural surfaces, it is also desirable for the visible surfaces of workpieces to have varying degrees of gloss, ranging from matte to glossy. This can also be achieved through the purposeful structuring of the surface.

[0005] Document DE 10 2007 055 053 A1 discloses, for example, an extrusion tool in the form of a pressure plate, which includes a structured extrusion surface with multiple gloss levels. The structured surface includes a mountain-like surface with valley-like depressions and peak-like protrusions. By means of the pressure plate or its extrusion surface, a material sheet, such as a laminate, can be manufactured, whereby the material sheet has a structured surface with multiple gloss levels configured on the extrusion surface.

[0006] Furthermore, it is desirable to apply different colors to the visible surfaces of the workpiece. To date, pigments (e.g., inks, varnishes, pigments) have been used, which are applied to the surface, for example, by means of suitable printing methods. However, such methods are relatively expensive, especially if these methods are to be combined with the aforementioned surface structuring. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an improved solution for producing colored surfaces on workpieces, including those made of wood or plastic.

[0008] This objective is achieved by the method described above, which involves the following steps: providing an extrusion tool having an extrusion surface configured to contact a workpiece; irradiating at least one defined structural region with an ultrashort pulse laser having a pulse duration of PD ≤ 10 picoseconds to generate a periodic three-dimensional structure in at least one defined structural region of the extrusion surface, having an average structural period (P) of P ≤ 1.5 micrometers and an average structural depth (T) of T ≤ 1 micrometer. This results in a surface structured such that color effects can be achieved through light diffraction. The periodic structure can be physically considered as an optical grating. In this way, color effects can be generated by laser structuring without the application of pigments. The desired coloring can be achieved by individually changing the average structural period or in combination with the average structural depth and / or the geometry of the three-dimensional structure.

[0009] Advantageously, a first coating with a thickness of at least 1 micrometer can be applied to the extrusion surface before irradiation, wherein a periodic three-dimensional structure is formed on the first coating. This allows a protective layer to be applied to the extrusion tool, for example, to protect it from wear, corrosion, etc.

[0010] Advantageously, the extrusion tool used has a basic structure on the extrusion surface for mimicking a natural surface, which can be transferred to the workpiece, wherein a periodic three-dimensional structure is generated on the basic structure. This allows for the mimicry of a natural surface, having areas including defined coloring. The basic structure can be designed, for example, to mimic a wood or stone surface.

[0011] Advantageously, the location and / or shape and / or size and / or average structural period and / or average structural depth of at least one defined structural region can be determined based on the basic structure of the extruded surface. Natural surfaces often have very distinctive appearances, such as distinctive striations and knots in the case of wood. The periodic three-dimensional structure to be produced according to the invention can now be generated based on this distinctive appearance. Thus, for example, the periodic three-dimensional structure can be applied only to regions of the basic structure configured to generate or mimic knots. The shape and size of the defined structural region, and its location on the extruded surface, can correspond here to, for example, the shape, size, and location of the knot to be mimicked. The average structural period and / or average structural depth can be selected, for example, based on the desired coloring.

[0012] The extrusion tool may have a metallic material in at least one defined structural region of the extruded surface and / or the first coating may have a metallic material, wherein a method for generating laser-induced periodic surface structures is applied to generate periodic three-dimensional structures. This method can generate so-called "laser-induced periodic surface structures" (LIPSS). The laser wavelength here determines the period of the optical grating. The distance between the individual LIPSS approximately corresponds to the wavelength of the applied laser.

[0013] To achieve reliable coloring, the ultrashort pulse laser preferably has a wavelength of λ≤1064 nm.

[0014] For ultrashort pulse lasers, either circularly polarized or linearly polarized laser beams can be used. Depending on the laser beam used, different structurally different LIPSS can be produced. Linearly polarized laser beams, for example, produce linear or elongated LIPSS, while circularly polarized laser beams produce essentially triangular LIPSS, each viewed from a top view of the surface. The different shapes of the LIPSS result in corresponding colors being visible from different viewing angles.

[0015] To ensure sufficient, however not excessive, material removal by the laser, the energy flux density of the ultrashort pulse laser is preferably equal to or greater than the removal threshold of the metallic material. The removal threshold is material-dependent and can be assumed to be known.

[0016] According to another advantageous embodiment of the invention, the extrusion tool may have a metallic or ceramic material or plastic in at least one defined structural region of the extrusion surface, and / or the first coating may have a metallic or ceramic material or plastic. To generate a periodic three-dimensional structure, a method for laser interference structuring using at least two superimposed laser beams is applied. This allows for the fabrication of periodic structures using alternative methods. Laser interference structuring has the advantage over the methods described above for generating laser-induced periodic surface structures because it is independent of the material of the extrusion tool or the first coating. Methods for generating laser-induced periodic surface structures require a metallic surface, while laser interference structuring can also be used with other materials.

[0017] By applying three superimposed laser beams, more complex geometries can be produced. Two superimposed laser beams can essentially produce (in a top view) linear structures, while three laser beams can produce essentially (in a top view) triangular structures. "Essentially linear" and "essentially triangular" should be understood here as meaning that the structure does not necessarily have a geometrically perfect "linear or triangular" shape, but rather that the shape can be manufactured with a certain degree of natural deviation. In a top view, a "linear" structure could be, for example, a long cuboid whose longer side is much longer than its shorter side. In a top view, a "triangular" structure could be, for example, a pyramid or a truncated pyramid.

[0018] For reliable coloring, the ultrashort pulse laser preferably has a wavelength λ ≤ 1064 nm, particularly preferably in the range of 1030 ± 5 nm to 1064 ± 5 ​​nm, or in the range of 515 ± 5 nm to 532 ± 5 nm, or in the range of 343 ± 5 nm to 355 ± 5 nm. Similar to the case above in the LIPSS method, the laser wavelength here also determines the structural period. The given wavelength ranges cover the infrared, green, and ultraviolet ranges.

[0019] Ultrashort pulse lasers can have pulses with a repetition rate of ≤2 MHz, preferably ≤1 MHz. Alternatively or additionally, the seed laser of the ultrashort pulse laser can generate pulses with a frequency of ≥40 MHz. This can improve the productivity of structure manufacturing.

[0020] Advantageously, at least two structural regions can be defined on the extrusion surface, within which different periodic three-dimensional structures can be generated. This can result in regions with different colors.

[0021] At least a portion of the resulting periodic three-dimensional structure can be coated with a preferably abrasion-resistant second coating, wherein the thickness of the second coating is determined such that the resulting periodic three-dimensional structure is retained in the second coating. The layer thickness is therefore preferably less than the average structure depth T and preferably ≤1 micrometer. This allows for the application of an abrasion-resistant layer to the structured surface, for example. This ensures that the structure is retained for a longer period, thereby allowing for longer use of the extrusion tool. The second coating can be advantageous, for example, in the manufacture of laminate flooring, because it applies a strong mechanical load to the extrusion tool.

[0022] Preferably, the extrusion tool is a pressure plate, pressure belt, or pressure roller applied to a workpiece, which includes wood or plastic, preferably laminate flooring, or furniture components, particularly cabinets, doors, worktops, and tables. Thus, many common products can be colored.

[0023] This objective is further achieved using the extrusion tool described at the beginning, resulting in a structured surface comprising a periodic three-dimensional structure with an average structural period of P ≤ 1.5 micrometers and an average structural depth of T ≤ 1 micrometer.

[0024] Preferably, the periodic three-dimensional structure has a substantially linear or substantially triangular shape in a top view and / or at least one of the following geometric formations: a cone, a truncated cone, a pyramid, a truncated pyramid, wherein the pyramid and / or truncated pyramid preferably has triangular basic faces. This provides an advantageous structure that allows the coloring to be identified from different perspectives.

[0025] A second, abrasion-resistant coating can be applied to at least one structural region of the extruded surface, wherein the thickness of the second coating is determined such that the periodic three-dimensional structure is retained within the second coating. Preferably, the thickness is therefore less than the average structural depth T of the periodic three-dimensional structure and is preferably ≤1 micrometer. This protects the periodic three-dimensional structure from abrasion and allows the color to be retained for a long time.

[0026] The extrusion tool can have a basic structure on the extrusion surface to mimic a natural surface, which can be transferred to a workpiece, wherein a periodic three-dimensional structure is formed on the basic structure. This allows for the production of a mimicry of a natural surface, which includes defined colored areas.

[0027] The extrusion tool is preferably used to process a workpiece, wherein the extrusion tool is pressed onto the surface of the workpiece, thereby creating an imprint in the workpiece surface by means of a periodic three-dimensional structure, which is substantially complementary to the periodic three-dimensional structure of the extrusion tool, wherein the workpiece is preferably made of wood or plastic, such as laminate flooring or laminated material board.

[0028] This objective is further achieved by utilizing the workpiece described at the beginning, namely, a structured surface comprising a periodic three-dimensional structure having an average structural period of P ≤ 1.5 μm and an average structural depth of T ≤ 1 μm, and the periodic three-dimensional structure being manufactured by a pressing extrusion tool having an extrusion surface comprising substantially complementary periodic three-dimensional structures.

[0029] Advantageously, at least a portion of the three-dimensional structure may be coated with a preferably abrasion-resistant third coating, wherein the thickness of the third coating is determined such that the periodic three-dimensional structure is retained within the third coating. Alternatively or additionally, the third coating may be optically transparent. Because light can pass through the transparent layer onto the periodic three-dimensional structure, the thickness of the transparent layer may, if possible, be greater than the average structural depth of the periodic three-dimensional structure.

[0030] The workpiece can have a basic structure on its surface to mimic a natural surface, wherein a periodic three-dimensional structure is formed on the basic structure. This allows for the imitation of a natural surface, which includes defined colored areas. Attached Figure Description

[0031] To better understand the present invention, the following figures further illustrate the invention.

[0032] Each is shown in an extremely simplified, schematic view:

[0033] Figure 1 An extrusion apparatus with an extrusion tool and a workpiece is shown;

[0034] Figure 2 a shows an extrusion tool having a first surface structure;

[0035] Figure 2 b shows an extrusion tool with a second surface structure;

[0036] Figure 3 An extrusion tool having two structural regions, each comprising a surface structure according to the invention, is shown.

[0037] Figure 4 Exemplary apparatus for implementing the method according to the invention is shown;

[0038] Figure 5 The workpiece shown includes multiple structural regions in an exemplary embodiment of the invention.

[0039] It should be noted that in different described embodiments, the same parts are given the same reference numerals or the same component names, and the disclosure contained throughout the specification can be applied, in meaning, to the same parts that have the same reference numerals or the same component names. Furthermore, the location descriptions selected in the specification, such as, for example, upper, lower, side, etc., relate to the directly described and illustrated figures, and these location descriptions can be applied, in meaning, to the new location if the location changes. Detailed Implementation

[0040] exist Figure 1 The extrusion device 1 is shown schematically and simplified. The extrusion device 1 includes an extrusion punch 2 and a workpiece receiving portion 3. An extrusion tool 4 is disposed on the side of the extrusion punch 2 facing the workpiece receiving portion 3. The extrusion tool 4 may be, for example, a pressure plate made of metal. On the surface facing the workpiece receiving portion 3, the extrusion tool 4 has an extrusion surface 5 for contacting a workpiece 6. The workpiece 6 may be disposed on the workpiece receiving portion 5, such that the workpiece is located between the extrusion tool 4 and the workpiece receiving portion 3.

[0041] A structured surface can be provided on the extrusion surface 5, which can be pressed into the workpiece surface 7 of the workpiece 6 facing the extrusion tool 4 by means of the extrusion punch 2. This creates a structured surface on the workpiece 6 that is substantially complementary to the structured surface of the extrusion tool 4. In the example shown, the structured surface extends over the entire extrusion surface 5. However, it is also natural that only a portion of the extrusion surface 5 can be structured.

[0042] The extrusion device 1 may include a suitable guide mechanism 9 for guiding the extrusion punch 2. Furthermore, the extrusion device 1 may include a suitable force generating mechanism 8 for operating the extrusion punch 2. The force generating mechanism 8 is preferably electrically actuated. To control the force generating mechanism 8, the extrusion device 1 may include a control unit 10. The force generating mechanism 8 may include, for example, a suitable hydraulic, mechanical, or pneumatic actuator. The control unit 10 may drive the force generating mechanism 8 to move the extrusion punch 2 toward the workpiece 6 and to press the extrusion tool 4 against the workpiece surface 7 with a sufficiently large pressure F, such as by... Figure 1 As indicated by the arrow in the diagram. The pressure F can vary depending on the material of workpiece 6 and the surface structure of the extrusion surface 5.

[0043] exist Figure 2 In diagrams a+2b, two different extrusion tools 4 are shown in their top views of the extrusion surface 5. Each of these extrusion tools 4 has an extrusion surface 5, which includes a basic structure for mimicking a natural surface. Figure 2 The extrusion tool 4 shown in a has, for example, an extrusion surface 5 configured to mimic the basic structure of wood. Figure 2 The extrusion tool 4 shown in b has, for example, an extrusion surface 5 configured to mimic the basic structure of stone.

[0044] The basic structure can be, for example, by means of in Figure 1 The extrusion device 1 shown is pressed into the workpiece surface 7 of the workpiece 6. As mentioned at the beginning, the basic structure shown, which is alternatively or additionally configured to imitate a natural surface, may also have surface structures for achieving a specific gloss level. In addition to the basic structure for imitating wood or stone, other structured surfaces may also be provided for imitating other preferably natural surfaces.

[0045] exist Figure 3 The extrusion tool 4 is shown in an exemplary embodiment of the invention, and also in a top view of the extrusion surface 5. The extrusion surface 5 has a basic structure for mimicking wood, extending substantially over the entire extrusion surface 5, as already shown in the figure. Figure 2As shown in section a. According to the invention, at least one defined structural region A, B, comprising a structured surface, is further provided on the extrusion surface 5, which includes a periodic three-dimensional structure 11 having an average structural period of P ≤ 1.5 micrometers and an average structural depth of T ≤ 1 micrometer. The structured surface of the defined structural region can be transferred to the workpiece 6 by pressing, for example by means of... Figure 1 The extrusion device 1 shown in the figure.

[0046] An optical grating can be generated through a periodic three-dimensional structure 11 of a given size, on which color effects can be produced by the diffraction of light. The defined structural regions thus appear colored to a person. The visible color is essentially related to the average structural period P. The physical effects of diffraction are known and therefore will not be described further here.

[0047] In accordance with Figure 3 In the illustrated example, a first rectangular structural region A and a second rectangular structural region B spaced apart from it are exemplary provided on the extrusion surface 5, their periodic three-dimensional structures 11 being different from each other. This allows for the creation of different areas with different coloring. For better identification, detail views A and B are shown for structural regions A and B respectively. Naturally, the shapes of structural regions A and B are not limited to rectangular shapes, but rather, structural regions can generally have any shape. However, in principle, the two structural regions A and B can also include the same periodic three-dimensional structure 11 to achieve the same coloring.

[0048] It is also possible to have only one unique structural region with a uniform structure. The structural region can, for example, extend across the entire extrusion surface 5 of the extrusion tool 4. If at least two structural regions A and B, each comprising a different structure 11, are provided, these structural regions can, for example, be directly adjacent to each other. Naturally, more than two structural regions with the same or different periodic three-dimensional structures 11 can also be provided on the extrusion surface 5. This can be advantageous, for example, for representing text or logos, such as for trademarks. For example, each letter of a text can be a separate structural region with a structure according to the invention (see, for example, see...). Figure 5 This allows for the display of text in color.

[0049] Within the scope of this invention, the average structural period P can be understood as the average distance between two consecutive three-dimensional structures 11, as depicted in details A and B. The periodic three-dimensional structures 11 of the first structural region A have a substantially triangular shape in the top view. The structural period P can here be defined, for example, as the distance between the midpoints of two consecutive triangular structures. The triangular structure has the advantage that the coloring is visible from three viewing directions. The periodic three-dimensional structures 11 of the second structural region B have a substantially elongated or linear shape in the top view. The coloring is visible here from two directions, oriented substantially perpendicular to the longitudinal direction of the linear structure.

[0050] In addition to the triangular and linear structures shown, the periodic three-dimensional structure 11 can naturally also have other shapes, such as the following geometric formations: cones, truncated cones, pyramids, truncated pyramids, wherein the pyramids and / or truncated pyramids preferably have triangular basic faces. However, the list is not exhaustive, and other shapes may also be provided.

[0051] exist Figure 3 The left side of the diagram shows a cross-section of the extrusion tool 4 along section line SS. It is clearly visible in the cross-sectional view that the surface structure of the first structural region A differs from the remaining basic structure of the extrusion surface 5. The first structural region A is used for coloring, while the remaining basic structure of the extrusion surface 5 is used to mimic the wood surface. However, structural region A can also be superimposed on the surface structure used to mimic the wood surface, thus the coloring is additionally used to mimic the wood surface. The average structural depth T of the three-dimensional structure 11 is also depicted here. The average structural depth T is ≤1 micrometer. The basic structure used to mimic the wood surface can have a greater depth compared to this. The average structural depth T should be understood within the scope of this invention as the average distance between the free end of the periodic three-dimensional structure 11 away from the extrusion surface 5 and its base connected to the extrusion tool 4.

[0052] A periodic three-dimensional structure 11 can, for example, be generated on the basic structure of the extrusion surface 5, wherein the position and / or shape and / or size and / or average structural period P and / or average structural depth T of at least one defined structural region are determined according to the basic structure of the extrusion surface 5. If the basic structure is designed, for example, to mimic wood, then the periodic three-dimensional structure 11 can be applied only to the regions of the basic structure, configured to mimic knot holes. The shape and size of the defined structural region and the position of the structural region on the extrusion surface 5 can correspond here to, for example, the shape, size, and position of the knot hole to be mimicked. The average structural period P and / or average structural depth T can, for example, be determined according to the desired coloring, which should be transferred to the workpiece 6 in the region of the knot hole.

[0053] The extrusion surface 5 of the extrusion tool 4 may be coated with an anti-wear second coating in at least the area of ​​the at least one structural region. Here, the layer thickness is determined such that the periodic three-dimensional structure 11 is preserved. The layer thickness is therefore preferably less than the average structural depth T and preferably ≤1 micrometer. This improves the wear resistance of the extrusion surface 5 and thus the durability of the extrusion tool 4, ensuring that the coloring effect is not lost when the surface structure is transferred to the workpiece.

[0054] Subsequently according to Figure 4 An exemplary embodiment of the method for manufacturing the extrusion tool 4 according to the present invention is further illustrated.

[0055] First, an extrusion tool 4 is provided, which has an extrusion surface 5 configured to contact a workpiece 6. According to... Figure 1 and Figure 2 An exemplary extrusion tool 4 has already been described. Subsequently, a periodic three-dimensional structure 11, as described above, with an average structural period of P ≤ 1.5 micrometers and an average structural depth of T ≤ 1 micrometer is generated in at least one defined structural region of the extrusion surface 5, preferably on the basic structure. This generation is achieved by irradiating the defined structural region with an ultrashort pulse laser having a pulse duration of ≤ 10 picoseconds. Because the structural period P is related to the wavelength of the laser, the ultrashort pulse laser preferably has a wavelength λ ≤ 1064 nanometers.

[0056] Alternatively, a first coating with a thickness of at least 1 micrometer can be applied to the extruded surface 5 before irradiation, and a periodic three-dimensional structure 11 can be generated on the first coating in a defined structural region.

[0057] Within the scope of this invention, two different methods can be applied to generate periodic three-dimensional structures 11. The first method is so-called laser interferometry structuring, and the second method is the so-called LIPSS method. Both methods are known in principle in the prior art.

[0058] If the extrusion tool 4 has a metallic, ceramic, or plastic material in at least one defined structural region of the extrusion surface 5 (or if the first coating has a metallic, ceramic, or plastic material), then, in order to generate a periodic three-dimensional structure 11, a method for laser interference structuring using at least two superimposed laser beams can be applied, for example. Figure 4 An exemplary and schematic laser device 12 for implementing laser interference structuring is shown in the figure.

[0059] The laser device 12 may include a laser source 13 for generating a seed laser beam L1, a beam generating mechanism 14 for generating suitable sub-laser beams L2 and L3, and a carrier 15 for setting the portion to be irradiated, here the extrusion tool 4. The beam splitting mechanism 14 may include, for example, a focusing lens 16, a diffractive optical element 17 (DOE), an aperture 18, a prism 19, and a steering mirror 20 for each sub-laser beam L2 and L3. To achieve as many degrees of freedom as possible during irradiation by the extrusion tool 4, the beam generating mechanism 14 may be movable, for example, in the vertical direction, here along the Z-axis, and the carrier 15 may be movable, for example, in the horizontal plane, here in the XY plane, such as by means of... Figure 4 As indicated by the arrow in the image.

[0060] Additionally, it is advantageous that the focusing lens 16 is movable relative to the aperture 17 in the vertical direction, specifically along the Z-axis. Furthermore, the steering mirror 20 is movable in the horizontal direction, specifically along the X-axis, and rotatable about a horizontal axis, specifically the Y-axis. The seed laser beam L1 can be split into two (or more) sub-laser beams L2 and L3 by the prism 19. The sub-laser beams L2 and L3 can then be refocused onto the extrusion surface 5 of the extrusion tool 4 by the steering mirror 20, so as to interfere on the extrusion surface 5. Figure 4 The middle detail C shows a close-up of the superposition of two sub-laser beams L1 and L2.

[0061] By linearly moving and simultaneously rotating the steering mirror 19, different structural periods P can be generated on the extrusion surface 5. The movement of the movable components can be achieved, for example, by a suitable actuator, which can be driven by a suitable (not shown) control unit. Naturally, the embodiments shown should be understood as exemplary only and not as limiting. For example, more than two superimposed (sub)laser beams L2, L3…Li can also be used to generate periodic three-dimensional structures 11.

[0062] The wavelength λ of the laser primarily determines the average structural period P of the periodic three-dimensional structure 11 to be generated. The wavelength λ is therefore preferably λ ≤ 1064 nm. For example, wavelengths λ in the range of 1030 ± 5 nm to 1064 ± 5 ​​nm (infrared range), 515 ± 5 nm to 532 ± 5 nm (green range), or 343 ± 5 nm to 355 ± 5 nm (ultraviolet range) can be used. Besides the wavelength λ, the incident angle α of the two sub-laser beams L2 and L3 can affect the generated structural period P.

[0063] As in Figure 4As shown in detail C, the structure 11 produced on the extrusion surface 5 is generated by the interference of at least two superimposed sub-beams L2, L3. The wavelength λ and the incident angle α are also shown here. The interference of the sub-laser beams L2, L3 here has an interference maximum value I_max and an interference minimum value I_min in the region of the extrusion surface 5, as schematically indicated. The energy flux density of the laser or sub-laser beams L2, L3 is preferably determined such that the interference maximum value I_max is located at or slightly above a material-specific removal threshold of the material of the extrusion surface 5, in order to produce localized material removal, while the interference minimum value I_min is located below the removal threshold and therefore does not result in material removal.

[0064] The resulting periodic three-dimensional structure 11 can have an average structural period P of, for example, 300-1500 nm. The average structural depth T can be, for example, 100-400 nm. The ratio between the structural depth T and the structural period P (the so-called aspect ratio) is preferably ≤0.3. In the case of interference structuring, alternative or additional wavelengths λ can also influence the average structural period P by changing the incident angle α of the two sub-laser beams L2, L3.

[0065] The applied ultrashort pulse laser can, for example, have a repetition rate of ≤2 MHz, preferably ≤1 MHz. Alternatively or additionally, the seed laser L1 of the ultrashort pulse laser can generate pulses with a frequency of ≥40 MHz.

[0066] If the extrusion tool 4 has a metallic material in at least one defined structural region of the extrusion surface 5 (or optionally, the first coating has a metallic material), then the alternative is to follow... Figure 4 Laser interference structuring can be used to generate periodic three-dimensional structures 11. Methods for generating laser-induced periodic surface structures can be applied. Laser-induced periodic surface structures are also known by the name "laser-induced periodic surface structures" (LIPSS). This method is therefore also called the LIPSS method. The physical basis of the LIPSS method is known in principle in the prior art and therefore will not be described in detail here.

[0067] The surface irradiation is preferably achieved using an ultrashort pulse laser with an energy flux density that is located at or slightly below the material-specific removal threshold of the metal material of the extrusion tool 4.

[0068] The distance between the individual LIPSSs (average structural period P) roughly corresponds to the wavelength λ of the applied laser. The individual LIPSSs can vary considerably in characteristics and geometry. In the case of the LIPSS method, the structural period P can be intentionally influenced, for example, by varying the laser wavelength λ (e.g., from 1030 nm to 515 nm).

[0069] Besides the laser wavelength λ, another fundamental influencing factor is laser polarization. For example, in the LIPSS method, either circularly polarized or linearly polarized laser beams can be used for ultrashort pulse lasers. Figure 3 The linear or elongated LIPSS shown in detail B can be produced, for example, by illumination using a linearly polarized laser beam. If the polarization is changed to circular, then a triangular LIPSS can be produced, as shown, for example in... Figure 3 As shown in detail A.

[0070] The constructed LIPSS structure forms an optical grating for the incident light beam, which is diffracted on this grating. The diffracted light superimposes, generating colored interference fringes that collectively form a spectrum. When white light is used, as with a prism, a continuous spectrum is generated, where the spectrum is divided into its wavelength components. If monochromatic light (light of a specific wavelength) reaches the optical grating, it is also diffracted and interfered with, but it is not decomposed. This effect can be used for security marking. Marks introduced in this way can be read using only a light source of a defined wavelength (matching the structural period P of the LIPSS). The LIPSS can therefore be considered an encoding, and the matching light source can be considered a key.

[0071] Based on the one-dimensionality of linear LIPSS, the resulting color spectrum is related to the viewing angle and the angle of incidence. A triangular LIPSS has the advantage that it is presented from three viewing directions. Therefore, a relatively constant color spectrum can be achieved using this triangular LIPSS, which is relatively independent of the viewing angle.

[0072] exist Figure 5An exemplary workpiece 6 is shown. Workpiece 6 preferably comprises a wood material, such as, for example, solid wood, wood fiber material, or wood shavings. Known wood fiber materials are, for example, medium-density fiberboard (MDF), high-density fiberboard (HDF), medium-hard fiberboard (HFM), or hardboard (HFH). In the case of wood shavings, they are distinguished, for example, between long-pressed particleboard (OSB), flat-pressed board (P1-P7 series), and extruded board (ES and ET), based on the orientation and size of the shavings. Workpiece 6 may include, for example, a coated wood material. The coating may comprise a paper impregnated with melamine resin. The coating may be pressed onto the wood material. Workpiece 6 may also include, for example, a suitable plastic. Suitable plastics are, for example, so-called luxury vinyl floor tiles (LVT). Workpiece 6 may be, for example, laminated flooring or laminated material boards, or furniture or part of furniture.

[0073] On the visible workpiece surface 7, in the illustrated example, there are a third structural region C, a fourth structural region D, a fifth structural region E, and a sixth structural region F. Each structural region CF has a structuring according to the invention, which includes a periodic three-dimensional structure 11 having an average structural period P of P ≤ 1.5 micrometers and an average structural depth T of T ≤ 1 micrometer. The structural region CF can be manufactured by pressing with a suitable extrusion tool 4, the extrusion surface 5 of which includes substantially complementary periodic three-dimensional structures 11.

[0074] like Figure 5 As indicated, the structural region CF, which is structured according to the invention, can also be provided with a suitable basic structure to mimic a defined natural surface, such as a stone surface, as indicated. The basic structure for mimicking the natural surface can preferably be superimposed on the structural region CF, thereby providing a colored appearance on the natural surface of the workpiece 6. As already described according to the extrusion tool, the position, shape, and size of the structural region CF can be determined, for example, based on the basic structure. Thus, the structural region can, for example, match the shape, size, and position of features of the surface to be mimicked, such as the knots on a wood surface.

[0075] The third structural region C here has, for example, an S-shaped form. The S-shape represents any shape. The third structural region C can have, for example, a periodic three-dimensional structure 11 of a triangle, as indicated by point-like surfaces. The fourth structural region D here has, for example, the shape of the letter "A", the fifth structural region E has the shape of the letter "B", and the sixth structural region F here has the shape of the letter "C".

[0076] The letters represent any characters. The fourth, fifth, and sixth structural regions DF can, for example, each have a linear or elongated periodic three-dimensional structure 11, as indicated by the dashed surface. In the same structure, the letters appear in the same color. In the case of different structures, especially in the case of different structural periods P, the letters can also appear in different colors.

[0077] Similar to the application of a third coating to the extrusion tool 4, the resulting periodic three-dimensional structure 11 can also be coated onto the workpiece 6. This third coating can, for example, be abrasion-resistant. The thickness of the third coating should be determined such that the resulting periodic three-dimensional structure 11, particularly the structural period P and structural depth T, is retained or unchanged, or only negligibly altered, thereby preserving the color. An abrasion-resistant third coating is advantageous, for example, in the case of laminated flooring, which is subjected to strong mechanical stress. This improves the durability of the color. Preferably, the thickness of the third coating is ≤1 micrometer.

[0078] Alternatively or additionally, the third coating can also be optically transparent. Because light can pass through a transparent coating onto the periodic three-dimensional structure, the thickness of the transparent third coating can, if possible, be greater than the average structural depth T of the periodic three-dimensional structure. This means that the periodic three-dimensional structure does not necessarily have to be contained within the transparent third coating. This can, for example, result in higher wear resistance.

[0079] The various embodiments illustrate possible implementation variations, wherein it should be noted that the invention is not limited to the specific implementation variations shown herein, but different combinations of the various implementation variations are also possible and such variations based on the teachings of the invention for technical processing may be within the capabilities of those skilled in the art.

[0080] The scope of protection is determined by the claims. However, the specification and drawings can be used to design the claims. A single feature or combination of features from the different embodiments shown and described can represent an independent inventive solution on its own. The purpose based on an independent inventive solution can be obtained from the specification.

[0081] In the specific specification, the information given for the range of values ​​can be understood as including all and all of the subranges from which they are derived. For example, the information 1 to 10 can be understood as including all subranges that originate from the lower boundary 1 and the upper boundary 10. That is, all subranges begin at the lower boundary 1 or greater and end at the upper boundary 10 or less, such as 1 to 1.7, 3.2 to 8.1, or 5.5 to 10.

[0082] For the sake of clarity, it should be noted that, for better understanding of the structure, some elements are shown not to scale and / or enlarged and / or reduced.

[0083] List of reference numerals

[0084] 1. Extrusion device

[0085] 2 Extrusion punch

[0086] 3. Workpiece receiving section

[0087] 4 Extrusion tools

[0088] 5 Extrusion surface

[0089] 6 workpieces

[0090] 7. Workpiece surface

[0091] 8 force generating mechanisms

[0092] 9 guiding institutions

[0093] 10 control units

[0094] 11 Periodic three-dimensional structures

[0095] 12 laser devices

[0096] 13 laser sources

[0097] 14 beam generation mechanisms

[0098] 15 load-bearing components

[0099] 16-Focusing Lens

[0100] 17 diffractive optical elements

[0101] 18 apertures

[0102] 19 prisms

[0103] 20-turning reflector

[0104] L1 Seed Laser Beam

[0105] L2-L3 sub-laser beams

[0106] I_max is the maximum value of interference.

[0107] I_min minimum interference value

[0108] AF structural region

[0109] α angle of incidence

[0110] λ wavelength

Claims

1. A method for manufacturing an extrusion tool (4), characterized in that, Implement the following steps: - Provide an extrusion tool (4) having an extrusion surface (5) configured to contact a workpiece (6). - By irradiating at least one defined structural region (A, B) of the extruded surface (5) with an ultrashort pulse laser having a pulse duration of ≤10 picoseconds, a periodic three-dimensional structure (11) with an average structural period (P) of P ≤1.5 micrometers and an average structural depth (T) of T ≤1 micrometer is generated in the at least one defined structural region (A, B).

2. The method according to claim 1, characterized in that, Before irradiation, the extruded surface (5) is coated with a first coating having a layer thickness of at least 1 micrometer, and the periodic three-dimensional structure (11) is generated on the first coating.

3. The method according to claim 1 or 2, characterized in that, The extrusion tool (4) has a basic structure on the extrusion surface (5) for mimicking a natural surface, the basic structure being transferable to the workpiece (6), wherein the periodic three-dimensional structure (11) is generated on the basic structure.

4. The method according to claim 3, characterized in that, The location and / or shape and / or size and / or average structural period (P) and / or average structural depth (T) of the at least one defined structural region (A, B) are determined based on the basic structure of the extruded surface (5).

5. The method according to any one of claims 1 to 4, characterized in that, The extrusion tool (4) has a metallic material in at least one of the defined structural regions (A, B) of the extrusion surface (5) and / or the first coating has a metallic material, and a method for generating a laser-induced periodic surface structure is applied in order to generate the periodic three-dimensional structure (11).

6. The method according to claim 5, characterized in that, The ultrashort pulse laser has a wavelength of λ≤1064 nanometers.

7. The method according to claim 5 or 6, characterized in that, The ultrashort pulse laser is applied using either a circularly polarized laser beam or a linearly polarized laser beam.

8. The method according to any one of claims 5 to 7, characterized in that, The energy flux density of the ultrashort pulse laser is equal to or greater than the removal threshold of the metallic material.

9. The method according to claim 1 or 2, characterized in that, The extrusion tool (4) has a metal or ceramic material or plastic in at least one of the defined structural regions (A, B) of the extrusion surface (5), and / or the first coating has a metal or ceramic material or plastic, wherein a method for laser interference structuring using at least two superimposed laser beams (L2, L3) is applied to generate the periodic three-dimensional structure (11).

10. The method according to claim 9, characterized in that, Three superimposed laser beams are applied to generate the periodic three-dimensional structure (11).

11. The method according to claim 9 or 10, characterized in that, The ultrashort pulse laser has a wavelength λ ≤ 1064 nm, wherein it is preferably applied in the range of 1030 ± 5 nm to 1064 ± 5 ​​nm, or in the range of 515 ± 5 nm to 532 ± 5 nm, or in the range of 343 ± 5 nm to 355 ± 5 nm.

12. The method according to any one of claims 1 to 11, characterized in that, The ultrashort pulse laser has pulses with a repetition rate of ≤2 MHz, preferably ≤1 MHz, and / or the seed laser of the ultrashort pulse laser generates pulses with a frequency of ≥40 MHz.

13. The method according to any one of claims 1 to 12, characterized in that, At least two structural regions (A, B) are defined on the extrusion surface (5), and different periodic three-dimensional structures (11) are generated in the structural regions.

14. The method according to any one of claims 1 to 13, characterized in that, At least a portion of the resulting periodic three-dimensional structure (11) is coated with a second coating that is preferably wear-resistant, wherein the thickness of the second coating is determined such that the periodic three-dimensional structure (11) is retained, wherein the thickness of the second coating is preferably ≤1 micrometer.

15. The method according to any one of claims 1 to 14, characterized in that, The extrusion tool (4) is a pressure plate, pressure belt or pressure roller, and the extrusion tool is configured to be applied to a workpiece (6), the workpiece comprising preferably coated wood or plastic, preferably laminate flooring, plastic flooring, especially LVT, or furniture workpieces, especially cabinets, doors, workbenches, tables.

16. An extrusion tool (4), comprising an extrusion surface (5) for contacting a workpiece (6), wherein, The extrusion surface (5) has a structured surface in at least one defined structural region (A, B), the structured surface being transferable to the workpiece by pressing, characterized in that the structured surface comprises a periodic three-dimensional structure (11) having an average structural period (P) of P ≤ 1.5 micrometers and an average structural depth (T) of T ≤ 1 micrometer.

17. The extrusion tool (4) according to claim 16, characterized in that, The periodic three-dimensional structure (11) includes a structure having a substantially linear shape in a top view and / or includes a structure having a substantially triangular shape in a top view and / or includes at least one of the following geometric formations: a cone, a truncated cone, a pyramid, a truncated pyramid, wherein the pyramid and / or the truncated pyramid preferably has a triangular basic face.

18. The extrusion tool (4) according to claim 16 or 17, characterized in that, There are at least two defined structural regions (A, B), and the periodic three-dimensional structures (11) of the defined structural regions are different.

19. The extrusion tool (4) according to any one of claims 16 to 18, characterized in that, The extruded surface (5) is coated with a second coating, preferably wear-resistant, in at least one region of the at least one structural region (11), wherein the thickness of the second coating is determined such that the periodic three-dimensional structure (11) is preserved, wherein the thickness of the second coating is preferably ≤1 micrometer.

20. The extrusion tool (4) according to any one of claims 16 to 19, characterized in that, The extrusion tool (4) has a basic structure on the extrusion surface (5) for mimicking a natural surface, the basic structure being transferable to the workpiece (6), wherein the periodic three-dimensional structure (11) is formed on the basic structure.

21. The use of the extrusion tool (4) manufactured by the method according to any one of claims 1 to 15 or the extrusion tool (4) according to any one of claims 16 to 20 for machining a workpiece (6), characterized in that, The extrusion tool (4) is pressed onto the workpiece surface (7) of the workpiece (6), thereby creating an imprint in the workpiece surface (7) of the workpiece (6) by means of the generated periodic three-dimensional structure (11), which is substantially complementary to the periodic three-dimensional structure (11) of the extrusion tool (4), wherein the workpiece (6) is preferably made of wood or plastic, preferably coated, such as laminate flooring, plastic flooring, especially LVT, or laminate board.

22. Workpiece (6), including: Wood materials, especially coated wood materials, or plastics, preferably laminated flooring, laminated boards, or furniture components; The workpiece has a workpiece surface (7) comprising at least one defined structural region with a structured surface, characterized in that the structured surface comprises a periodic three-dimensional structure (11) having an average structural period (P) of P ≤ 1.5 micrometers and an average structural depth (T) of T ≤ 1 micrometer, and the periodic three-dimensional structure (11) is manufactured by a pressing extrusion tool (4), the extrusion surface (5) of which comprises substantially complementary periodic three-dimensional structures (11).

23. The workpiece (6) according to claim 22, characterized in that, At least two structural regions (CFs) are identified, wherein the periodic three-dimensional structures (11) of the structural regions are different.

24. The workpiece (6) according to claim 22 or 23, characterized in that, At least a portion of the three-dimensional structure (11) is coated with a preferably wear-resistant third coating, wherein the thickness of the third coating is determined such that the periodic three-dimensional structure (11) is preserved and / or the third coating is optically transparent.

25. The workpiece (6) according to any one of claims 22 to 24, characterized in that, The workpiece (6) has a basic structure on the workpiece surface (7) for imitating a natural surface, wherein the periodic three-dimensional structure (11) is formed on the basic structure.

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