Pressing tool and method for producing a pressing tool

Abstract

The invention relates to a pressing tool having a support structure made of sheet steel. The pressing tool is formed from a press platen or continuous strip and is designed to press material panels in heating presses. The support structure of the pressing tool has a rough structure which is produced by means of at least one processing operation and which has a depth of at least 150 µm. At least a partial region of the rough structure is rounded by means of polishing. The surface of the pressing tool has a fine structure which is produced by means of at least one processing operation. The invention further relates to a method for producing the pressing tool and to a method for producing a material panel using the pressing tool.

Description

[0001] Press tool and method for producing a press tool

[0002] The invention relates to a pressing tool for imitating wood, a method for producing a pressing tool for imitating wood and a method for producing a material plate.

[0003] Material boards, such as wood-based panels, are used in the furniture industry and for interior design, such as laminate flooring. These boards have a core made of MDF (medium-density fiberboard) or HDF (high-density fiberboard), onto which various material layers are applied on at least one side, such as a decorative (optical) layer and a protective layer (overlay layer).

[0004] To prevent warping in the manufactured material boards, such material boards are usually provided with the same number of material layers on both sides. To bond the individual layers of the material boards (core, material layers, etc.), they are pressed together in a press using special pressing tools, particularly press plates or endless belts. This also involves surface embossing of the material boards. Hot presses are typically used to bond the various material layers made of thermosetting resins, such as melamine resin, to the surface of the core under the influence of heat by fusing the plastic materials.

[0005] The decorative layers determine the pattern and color design of the material panels; however, a desired surface structure can be achieved using suitable pressing tools. For example, a wood or tile pattern can be printed on the decorative layer (decorative paper), or decorative layers with patterns and color designs can be used that are artistically designed according to the respective intended use. Overlay layers printed on the top or bottom side can also be used.

[0006] To improve a true-to-life reproduction, especially for material panels with wood, tile, or natural stone decor, the pressing tools are provided with a surface texture that conforms to the decorative layer and creates a negative image of the desired surface structure. Therefore, the pressing tools have a 3D profile (depth texture), which, for example, is modeled on the wood grain of a wooden surface, to give the decorative layer of the material panel the appearance of such a wooden surface.

[0007] To achieve the compliant embossing of the material sheets—that is, the required precision fit of the decorative layer(s) and the surface structure of the material sheet—a high quality standard is required for the production of the pressing tools. In particular, the pressing plates or endless belts are used as upper and lower tools in short-cycle presses equipped with pressing plates, or in double-belt presses for endless belts. Embossing and heating of the material sheets occur simultaneously. The thermoset resins of the decorative and / or overlay layers of the material sheets are first melted, the surface structure corresponding to the surface structure of the pressing tools is introduced into the outer material layers, and the structured material layers are bonded to the core of the material sheet by subsequent curing.

[0008] To create the desired surface structuring in or on the pressing tools, digitized image data of a decorative template can be used to apply an etching resist for structuring the press plates or endless belts. For this purpose, an etching resist is applied to the press plates or endless belts, for example using a digital printer, and an etching process is then carried out. After removing the etching resist, the pressing tool can be treated further. Preferably, for surface structuring with particularly deep / high structures, several etching processes can be carried out in succession. For this purpose, an etching resist is again applied to the already etched press plate or endless belt, and a further etching is carried out until the desired deep structure has been created.In the individual etching processes, coarse or fine structuring of the surface structure can also be carried out, depending on which surface structure is to be given to the material plate.

[0009] Alternatively or in addition to the described etching processes or other material removal processes, material application processes can also be used to create the surface structuring (layer by layer) on the surface of the pressing tools. Most of these processes involve masks (masking) to protect the surface of the pressing tool from subsequent material application or removal. By repeatedly applying appropriate masks and subsequent material application or removal, surface structuring of various designs can be created.

[0010] Regardless of the chosen process, a surface structure is ultimately created on the pressing tool, representing the negative of the surface structure to be imprinted into the material plate. In this case, elevations in the surface structure correspond to the depressions in the surface structure of the material plate to be imprinted, and depressions in the surface structure correspond to the elevations that the surface structure of the material plate is intended to have.

[0011] To further improve the true-to-life reproduction of natural surfaces, in particular wood, tile or natural stone surfaces, pressing tools are used which also have different degrees of gloss. By setting a specific degree of gloss in a selected surface area of ​​the pressing tool, it is possible to create reflections or shading in the material sheet which, for example, reinforce the impression of a natural wood, tile or natural stone surface for an observer. In the prior art, for example, thin chrome layers with different degrees of gloss are used for this purpose. First, the entire surface of the pressing tool is chrome-plated and then a further chrome layer is applied which covers either only raised or only deeper areas of the surface structure (EP 3 010 704 B1).

[0012] EP 2 839 970 A1 discloses a method for producing a hydrophobic or superhydrophobic surface topography of a pressing tool in the form of a press plate, endless belt, or embossing roller. To improve the cleaning properties of the material plates produced with the pressing tools, a microstructuring on the surface is provided.

[0013] EP 2 060 658 A2 discloses a method for processing a structured surface of an embossing tool, in which the surface is fully coated with a first metallic coating to simulate wood pores. EP 2 289 708 A1 discloses a method for producing a surface structure of a metallic press plate, endless belt, or embossing roller using at least one laser, as well as a device for applying the method. A deep structure is created using the laser.

[0014] Press tools, e.g., in the form of press plates, endless belts, or embossing rollers, feature a structured pressing surface and are used, for example, in the woodworking industry to produce furniture, laminates, or panels—in other words, general material boards. The material boards are pressed with the structured pressing surface of the press tool, so that the workpieces receive structured surfaces corresponding to the structured pressing surface.

[0015] A disadvantage of the existing processes, however, is that the design options are limited. For example, the imitation of wood has so far been incomplete, and achieving the desired antique look—that is, the appearance of wear—is particularly difficult. Unlike replicating a wood or stone look, the texture does not necessarily follow the pattern. Older natural floors exhibit heavily rounded and unevenly arranged and shaped areas.

[0016] The object of the present invention is therefore to overcome the disadvantages of the prior art and to provide a pressing tool and a method for producing a pressing tool by means of which the imitation of wood as a material is better achieved and a degree of wear is easier to produce.

[0017] This object is achieved by a pressing tool, a method for producing a pressing tool device and a method for producing a workpiece according to the claims.

[0018] According to a first aspect of an embodiment, a pressing tool for imitating wood, which has a supporting structure made of sheet steel, is formed from a press plate or endless belt and is designed for pressing material panels in heating presses. A supporting structure is understood to mean a load-bearing region of the pressing tool, which is arranged on the unstructured and preferably flat surface of the pressing tool and which is not penetrated by the coarse structure. The supporting structure preferably has a thickness of at least 500 μm, preferably at least 2000 μm, or particularly preferably between 2000 and 5000 μm.The supporting structure of the pressing tool has a coarse structure produced by at least one processing operation with a depth of at least 150 pm, at least a partial area of ​​the coarse structure is rounded by laser polishing and thus corresponds to a wood grain, and the surface of the pressing tool has a fine structure produced by at least one processing operation.

[0019] According to a second aspect of the embodiment, a method for producing a pressing tool for imitating wood comprises the steps of producing a coarse structure with a depth of at least 150 μm on the support structure of the pressing tool by at least one processing step, rounding at least a partial area of ​​the coarse structure by laser polishing so that the partial area (4) of the coarse structure (2) corresponds to a wood grain, and producing a fine structure on the surface of the pressing tool by at least one processing step. Here, the pressing tool also has a support structure made of sheet steel, is formed from a press sheet or endless belt, and is designed for pressing material panels in heating presses.

[0020] According to a third aspect of the embodiment, in a method for producing a material plate having a structured surface by pressing, such a pressing tool is used for pressing the material plate.

[0021] It has been shown that the pressing tool and the methods of the first embodiment allow the overall appearance of a workpiece, e.g., the pressed laminate, to be highly customized, and, for example, to imitate heavily worn wood. Furthermore, knots can be better recreated in their natural appearance.

[0022] The further embodiments may relate to any of the aforementioned aspects.

[0023] According to a further embodiment, the coarse structure has a depth of between 150 pm and 2000 pm. A depth of between 150 pm and 1500 pm is particularly preferred. The laser can be directed at the coarse structure at different angles. Preferably, the laser can be guided over the coarse structure with adjustable parameters, such as removal rate and with adjustable speed as well as variable distance. Particularly preferably, certain areas of the coarse structure, such as sharp edges or larger areas of the coarse structure, can be selectively machined. The laser can be controlled according to a 3D data set or a grayscale file of the desired rounding of the pressing tool. For example, more areas to be machined would appear darker in the grayscale file. In the case of the grayscale file, certain laser setting parameters can preferably be assigned to individual grayscale values.

[0024] According to a further embodiment, one or more coatings are applied to the support structure over the entire surface or part of the surface, and the surface of the pressing tool is formed by the surface of the uppermost full-surface coating or by the uppermost partial surfaces of the partial coatings. In the method, one or more coatings are applied to the support structure over the entire surface or part of the surface before the coarse structure is produced.

[0025] According to a further embodiment, at least one region of the surface of the pressing tool has a first degree of gloss.

[0026] According to a further embodiment, at least one further region of the surface of the pressing tool has a second degree of gloss which differs from the first degree of gloss.

[0027] According to a further embodiment, each of the coatings is either metallic, ceramic or plastic-containing.

[0028] According to a further embodiment, at least one of the coatings is a chromium layer or a nickel-plated or nickel-containing coating.

[0029] According to a further embodiment, at least one region of at least one coating is formed by laser processing, matte etching, sandblasting, or chemical treatment. According to a further embodiment, the edges of at least one coating are broken by heavy polishing.

[0030] According to a further embodiment, at least one of the processing steps comprises one or more of pressing, embossing, etching, polishing, laser machining, grinding, milling and applying a further coating or a combination thereof.

[0031] According to a further embodiment, at least one coating is applied to the support structure by chemical deposition.

[0032] The embodiments show possible embodiment variants, whereby the invention is not limited to the specifically illustrated embodiment variants thereof, but rather any combinations of the individual embodiment variants with each other are also possible.

[0033] For a better understanding of the invention, it is explained in more detail using the following figures.

[0034] They show in a highly simplified, schematic representation:

[0035] Fig. 1 shows an example of a pressing tool according to an embodiment,

[0036] Fig. 2 shows an example of a coarse structure according to an embodiment,

[0037] Fig. 3 shows an example of a rounded coarse structure according to an embodiment, and Fig. 4 shows an example of a fine structure according to an embodiment.

[0038] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or identical component designations, whereby the disclosures contained in the entire description can be transferred mutatis mutandis to identical parts with identical reference symbols or identical component designations. The position information chosen in the description, such as top, bottom, side, etc., also relates to the directly described and illustrated figure, and these position information must be transferred mutatis mutandis to the new position in the event of a position change. Fig. 1 shows a pressing tool 1 for imitating wood, with a structure applied thereto, which transfers the structure to the workpiece when a workpiece is pressed with the pressing tool 1, for example in a heating press. In this way, the structure, which corresponds, for example, to the grain of wood, can be transferred to the workpiece.This gives the workpiece a wooden appearance, i.e. it looks like wood.

[0039] To create this structure on the pressing tool 1, the pressing tool 1, which may be, for example, a press plate or an endless belt, is machined. This processing can be performed by one of sandblasting, chemical treatment, pressing, embossing, etching, polishing, laser machining, grinding, milling, and coating application, or by a combination of several of these.

[0040] Fig. 2 shows a cross-sectional view of a coarse structure 2 produced by at least one machining operation on the support structure of the pressing tool 1. The machining depth is at least 150 pm. The machining depth can be between 150 pm and 2000 pm, with a depth between 150 pm and 1500 pm being particularly preferred.

[0041] Any processing can be done by one of sandblasting, chemical treatment, pressing, embossing, etching, polishing, laser processing, grinding, milling and applying coatings or by a combination of several of these.

[0042] Fig. 2 also shows that the coarse structure 2 has sharp edges in some places 3 or is very angular.

[0043] Fig. 3 shows a cross-section of a rounded coarse structure 2 of the pressing tool 1. At least one partial area of ​​the coarse structure 2 has been rounded by laser polishing. The laser polishing rounds off the edges of the coarse structure 2 or partial areas thereof, which makes it possible to give the coarse structure 2 or partial areas thereof a softer appearance. Another advantage here is that the feel changes, and the softer edges improve the similarity to wood. The relief of the coarse structure 2 is rounded by laser polishing. Either the relief of the entire coarse structure 2 of the pressing tool 1 is rounded by laser polishing, or only the reliefs of partial areas of the coarse structure 2 of the pressing tool 1.

[0044] During laser polishing, thin surface layers of the structure are rounded by the principle of remelting and smoothing the then liquid material due to interfacial tension. Solid-state lasers, for example, can be used for laser polishing. Depending on the condition of the surface to be rounded, pulsed lasers with pulse durations of a few hundred nanoseconds or continuous lasers can be used.

[0045] Using a laser for polishing enables automated rounding of three-dimensional surfaces with equivalent rounding quality. Compared to manual polishing, this results in higher processing speeds. Furthermore, reproducibility is ensured, meaning all press tools can be identical.

[0046] Furthermore, laser polishing places minimal mechanical stress on the press tool 1 because it is a non-contact process. This eliminates grinding or polishing waste, and no grinding or polishing agents need to be incorporated into the surface.

[0047] Fig. 3 shows that some of the previously sharp edges or angular areas 3 have been rounded; these are marked as rounded areas 4.

[0048] Fig. 4 shows a cross-sectional view of a fine structure 5 produced on the rounded coarse structure 2. The fine structure 5 is produced by at least one machining operation on the surface of the pressing tool 1.

[0049] Here, too, any processing can be performed by one of sandblasting, chemical treatment, pressing, embossing, etching, polishing, laser processing, grinding, milling, and coating application, or by a combination of several of these. To produce such a pressing tool 1, the coarse structure 2 is first produced on the support structure of the pressing tool 1 by at least one processing step. Subsequently, at least a portion of the coarse structure 2 is rounded by laser polishing. Then, a fine structure 5 is produced on the surface of the pressing tool 1 by at least one processing step.

[0050] As already explained above, each of the processing operations can be carried out by one of sandblasting, chemical treatment, pressing, embossing, etching, polishing, laser machining, grinding, milling and coating application or by a combination of several of these.

[0051] Alternatively, or in addition to the above-described method, one or more coatings can be applied to the supporting structure over the entire surface or over part of the surface. The surface of the pressing tool 1 is then formed by the surface of the uppermost full-surface coating or by the uppermost partial surfaces of the partial coatings. In this case, several partial surfaces can form a total surface area.

[0052] The coating or coatings can be applied before the coarse structure 2 is produced, so that the coarse structure 2 is produced in the coatings. However, the coatings can also be applied after the coarse structure 2 has been produced in the support structure of the pressing tool 1. Coatings can even be applied after rounding by polishing and before the fine structure 5 is produced. Finally, coatings can also be applied after the fine structure 5 has been produced.

[0053] This allows a first degree of gloss to be created in one or more areas of the surface of the finished pressing tool 1. This area or areas can be areas in which a coarse structure 2 has been rounded, but they can also be areas that were no longer altered by the rounding.

[0054] Alternatively, the gloss levels can also be achieved through processing. Each of these processes can be achieved through one of sandblasting, chemical treatment, pressing, embossing, etching, polishing, laser processing, grinding, milling, and the application of coatings, or through a combination of several of these.

[0055] By applying different coatings or by applying different treatments to a coating, at least one further area of ​​the surface of the pressing tool 1 can have a second gloss level that differs from the first gloss level. Two different gloss levels can also be created by treating one or more areas and leaving one or more areas untreated or uncoated.

[0056] Each of these coatings can be metallic, ceramic, or plastic-containing. Plastic-containing coatings are described, for example, in DE 10 2019 127 659 A1, which describes paint or plastic layers preferably comprising polyetheretherketone or polyetheretherketone, optionally with the addition of mineral particles.

[0057] At least one of the coatings may be a chromium layer or a nickel-plated or nickel-containing coating. Furthermore, one or more areas of the coatings may be formed by laser machining, matte etching, sandblasting, or chemical treatment. Furthermore, the edges of at least one coating may be broken by heavy polishing. This polishing may also be laser polishing.

[0058] Each of the coatings described above can also be applied by chemical deposition. As already described, each coating can be applied to the supporting structure without a structure, to the coarse structure, to the (partially) rounded coarse structure, and also to the fine structure.

[0059] Finally, it should be mentioned again that each of the processing operations described here can be carried out by one of sandblasting, chemical treatment, pressing, embossing, etching, polishing, laser processing, grinding, milling and application of coatings or by a combination of several of these.

[0060] In order to produce a workpiece, ie a material plate, with the press tool thus produced, a method for producing a material plate with a structured surface by pressing is used, wherein a press tool as described above is used to press the material plate.

[0061] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not restricted to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with each other are also possible and this variation possibility lies within the skill of the person skilled in the art in this technical field due to the teaching of technical action by means of the objective invention.

[0062] The scope of protection is determined by the claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying these independent inventive solutions can be derived from the description.

[0063] All information on value ranges in this description is to be understood as including any and all sub-ranges thereof, e.g. the information 1 to 10 is to be understood as including all sub-ranges, starting from the lower limit of 1 and the upper limit of 10, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

[0064] For the sake of clarity, it should be noted that some elements have been shown not to scale and / or enlarged and / or reduced in size to better understand the structure.

[0065] 1 Press tool 2 Coarse structure

[0066] 3 Sharp edges or angular areas

[0067] 4 rounded places

[0068] 5 Fine structure

Claims

Patent claims Pressing tool (1) for imitating wood, which has a supporting structure made of sheet steel, is formed from a press sheet or endless belt and is designed for pressing material plates in heating presses, wherein the supporting structure of the pressing tool (1) has a coarse structure (2) produced by at least one processing operation and has a depth of at least 150 pm, at least a partial area (4) of the coarse structure (2) is rounded by laser polishing and thus corresponds to a wood grain, and the surface of the pressing tool (1) has a fine structure (5) produced by at least one processing operation. Pressing tool (1) according to one of the preceding claims, wherein the coarse structure (2) has a depth between 150 pm and 2000 pm, particularly preferably a depth between 150 pm and 1500 pm.Press tool (1) according to one of the preceding claims, wherein the relief of the entire coarse structure (2) of the press tool (1) is rounded by laser polishing. Press tool (1) according to one of the preceding claims, wherein one or more coatings are applied to the support structure over the entire surface or over part of the surface, and the surface of the press tool (1) is formed by the surface of the uppermost full-surface coating or is formed from the uppermost partial surfaces of the partial coatings. Press tool (1) according to one of the preceding claims, wherein at least one region of the surface of the press tool (1) has a first degree of gloss. Press tool (1) according to one of the preceding claims, wherein at least one further region of the surface of the press tool (1) has a second degree of gloss that differs from the first degree of gloss.

7. Press tool (1) according to one of the preceding claims, wherein each of the coatings is either metallic, ceramic or plastic-containing.

8. Press tool (1) according to one of the preceding claims, wherein at least one of the coatings is a chromium layer or a nickel-plated or nickel-containing coating.

9. Press tool (1) according to one of the preceding claims, wherein at least one region of at least one coating is formed by laser processing, matte etching, sandblasting or chemical treatment.

10. Press tool (1) according to one of the preceding claims, wherein the edges of at least one coating are broken by strong polishing.

11. Press tool (1) according to one of the preceding claims, wherein at least one of the processing steps comprises one or more of pressing, embossing, etching, polishing, laser processing, grinding, milling and applying a further coating or a combination thereof.

12. Press tool (1) according to one of the preceding claims, wherein at least one coating is applied to the support structure by chemical deposition.

13. A method for producing a pressing tool (1) for imitating wood, wherein the pressing tool (1) has a supporting structure made of sheet steel, is formed from a pressing sheet or endless belt and is designed for pressing material plates in heating presses, the method comprising: Producing a coarse structure (2) with a depth of at least 150 pm on the support structure of the pressing tool (1) by at least one machining operation, Rounding at least one partial area (4) of the coarse structure (2) by laser polishing, so that the partial area (4) of the coarse structure (2) corresponds to a wood grain, and Producing a fine structure (5) on the surface of the pressing tool (1) by at least one processing.

14. The method according to claim 13, wherein the production of the coarse structure (2) produces a coarse structure (2) with a depth between 150 pm and 2000 pm, particularly preferably with a depth between 150 pm and 1500 pm.

15. Method according to one of claims 13 to 14, further comprising, before producing the coarse structure (2): full-surface or partial-surface application to the support structure of one or more coatings, whereby the surface of the pressing tool (1) is formed by the surface of the uppermost full-surface coating or is formed from the uppermost partial surfaces of the partial-surface coatings.

16. The method according to any one of claims 13 to 15, further comprising producing a first degree of gloss in at least one region of the surface of the pressing tool (1).

17. The method according to any one of claims 13 to 16, further comprising producing in at least one further region of the surface of the pressing tool (1) a second degree of gloss which differs from the first degree of gloss.

18. A method according to any one of claims 13 to 17, wherein each of the coatings is either metallic, ceramic or plastic.

19. A method according to any one of claims 13 to 18, wherein at least one of the coatings is a chromium layer or a nickel-plated or nickel-containing coating.

20. The method according to any one of claims 13 to 19, further comprising forming at least one region of at least one coating by laser machining, matte etching, sandblasting or chemical treatment.

21. The method according to any one of claims 13 to 20, further comprising breaking the edges of at least one coating by heavy polishing.

22. The method according to any one of claims 13 to 21, wherein at least one processing comprises one or more of pressing, embossing, etching, polishing, laser machining, grinding, milling and applying a further coating or a combination thereof.

23. The method according to any one of claims 13 to 22, further comprising applying at least one coating to the support structure by chemical deposition.

24. A method for producing a material plate having a structured surface by pressing, wherein a pressing tool (1) according to one of claims 1 to 12 is used to press the material plate.

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