DE102022116427A1 - Method for processing a surface of a pressing tool - Google Patents

Abstract

The invention relates to a method for processing a surface (2) of a pressing tool (1), in particular a press sheet or a press belt, in which a surface structuring (10) comprising at least one structure with an elevation (4) and a depression (3) is first produced becomes; a mask (18) is then applied to the surface (2); a metallic protective layer (11) is then applied to the surface (2) of the pressing tool (1) so that the structure is covered by the protective layer (11); and finally at least one further treatment step is carried out on the surface (2) of the pressing tool (1).

Description

The present invention relates to a method for processing a surface of a press tool, in particular a press plate or a press belt, and a press tool, for example a press plate or a press belt, for producing a workpiece having a surface structuring arranged in or on a surface of the press tool, which surface structuring has at least one structure with an elevation and a depression that is deeper in relation to the elevation, as well as a metallic protective layer, which metallic protective layer is arranged on the surface.

State of the art

Material panels, for example wood-based panels, are required for the furniture industry and for interior design, for example for laminate floors. The material panels have a core made of MDF (medium density fiberboard) or HDF (high density fiberboard), onto which core various material layers are placed at least on one side, for example an (optical) decorative layer and a protective layer (overlay layer).

In order to avoid distortion in the material panels produced, such material panels are usually provided with the same number of material layers on both sides; In order to connect the individual layers of the material panels (core, material supports, etc.) to one another, they are pressed together in a press using special pressing tools, in particular pressing sheets or endless belts. The surface of the material panels is also embossed. Hot presses are usually used to connect the various material layers made of thermoset resins, for example melamine resin, under the influence of heat by fusing the plastic materials with the surface of the core.

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

In order to improve a true-to-life replica, especially in the case of material panels with wood, tile or natural stone decor, the pressing tools are provided with a surface structure that is designed to be congruent with the decorative layer and forms a negative image of the desired surface structure. That is why the pressing tools have a 3D profile (depth structuring), which is modeled on the wood nerves of a wooden surface, for example, in order to give the decorative layer of the material board the appearance of such a wooden surface.

In order to achieve the conformal embossing of the material panels - i.e. the required accuracy of fit between the decorative layer(s) and the surface structure of the material panel - 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, which are covered with pressing plates, or in double-belt presses for endless belts, with the embossing and heating of the material plates taking place at the same time, so that the thermoset resins of the decorative and/or overlay Layers of the material plates are first melted, the surface structure corresponding to the surface structuring of the pressing tools is introduced into the external material layers, and the structured material layers are connected to the core of the material plate by subsequent hardening.

In order to produce 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 pressed sheets or endless belts. For this purpose, an etching resist is applied to the pressed sheets or endless belts, for example using a digital printer, in order to then carry out an etching process. After the etching resist has been removed, the pressing tool can be further treated, with several etching processes being carried out one after the other, preferably in the case of surface structures with particularly deep/high structures. For this purpose, an etching resist is applied to the already etched pressed sheet or endless strip and etching is carried out again until the desired deep structure has been produced. In the individual etching processes, a rough or fine structuring of the surface structuring can also be carried out, depending on which surface structure is to be given to the material plate.

Alternatively or in addition to the described etching processes or other material-removing processes, material-applying processes can also be used to produce the surface (in layers). structuring on the surface of the pressing tools can be used. Most of these processes use masks to protect the surface of the pressing tool from subsequent material application or removal. By repeatedly applying appropriate masks and then applying or removing material, surface structures of a wide variety of designs can be produced.

Regardless of the method chosen, a surface structure is ultimately created on the pressing tool, which represents the negative of the surface structure to be impressed into the material plate. Elevations in the surface structuring correspond to the depressions to be impressed in the surface structure of the material plate or depressions in the surface structuring correspond to the elevations that the surface structure of the material plate should have.

To further improve a true-to-life reproduction of natural surfaces, especially wood, tile or natural stone surfaces, pressing tools are used that also have different levels of gloss. By setting a specific level of gloss in a selected surface area of the pressing tool, it is possible to create any reflections or shades in the material plate, which, for example, reinforce the impression of a natural wood, tile or natural stone surface for a viewer. For this purpose, in the prior art, for example, thin chrome layers with different degrees of gloss are used, with the entire surface of the pressing tool being chrome-plated first and then a further chrome layer being applied, which either only covers raised or only deeper areas of the surface structure ( EP 3 010 704 B1 ).

However, with all known methods for processing the surface of pressing tools, it proves to be extremely difficult and time-consuming to protect contours and structures of the surface structuring that are particularly worthy of protection from further treatment steps that are carried out on the surface of the pressing tool. In particular, selective treatment of individual areas of the surface structuring cannot be achieved in practice, since - particularly due to the dimensions of the tools used - those areas of the surface structuring that have already been fully formed and/or treated are usually also necessarily treated. This is particularly a problem with surface structures with coarse and fine structures, since the production of these coarse and fine structures usually takes place in different processing steps and only those areas of the surface of the pressing tool that have either only coarse structures or only fine structures may be processed. In practice, however, it is unavoidable that the processing of the fine structures also affects (already formed and/or treated) coarse structures - for example, when polishing fine structures, there is often an (unwanted) change in the level of gloss in the area of the coarse structures.

A higher level of detail or quality in one area of surface structuring is therefore usually accompanied by a loss of detail or quality in another area of surface structuring. Even by particularly carefully matching the size of the tools used to a characteristic size of the structures of the surface structuring area to be treated, this problem cannot be completely avoided; In most cases, such coordination is not possible at all due to the very small characteristic size of the fine structures. In any case, this problem makes the manufacturing process of corresponding pressing tools complex and cost-intensive.

Task of the invention

The present invention is therefore based on the object of creating a method for processing a surface of a pressing tool, which allows simple and cost-effective production of such pressing tools.

Furthermore, a pressing tool for producing a workpiece, in particular a material plate, is to be created, the surface structuring of which has different structures, for example coarse and fine structures, with any level of detail and quality.

Further objects of the invention emerge from the disclosure of this application.

Presentation of the invention

1. a. Herstellen einer Oberflächenstrukturierung in oder auf der Oberfläche des Presswerkzeugs, wobei die Oberflächenstrukturierung zumindest eine Struktur mit einer Erhebung und einer - bezogen auf die Erhebung tieferliegenden - Vertiefung umfasst;
2. b. Aufbringen einer Maske auf die Oberfläche derart, dass zumindest ein die zumindest eine Struktur aufweisender Teilbereich der Oberflächenstrukturierung nicht von der Maske bedeckt ist;
3. c. Aufbringen einer metallischen Schutzschicht auf die Oberfläche des Presswerkzeugs derart, dass der Teilbereich der Oberflächenstrukturierung, insbesondere vollständig, von der Schutzschicht bedeckt ist;
4. d. Durchführen zumindest eines weiteren Behandlungsschrittes an der Oberfläche des Presswerkzeugs, wobei der von der metallischen Schutzschicht bedeckte Teilbereich der Oberflächenstrukturierung gegen die Wirkung des zumindest einen weiteren Behandlungsschrittes geschützt ist.

An object on which the invention is based is achieved by a method for processing a surface of a pressing tool, in particular a press sheet or a press belt, which method comprises at least the following steps:

1. a. Producing a surface structuring in or on the surface of the pressing tool, the surface structuring having at least one structure with an elevation and a - related to the elevation deeper - deepening includes;
2. b. Applying a mask to the surface in such a way that at least a portion of the surface structuring having the at least one structure is not covered by the mask;
3. c. Applying a metallic protective layer to the surface of the pressing tool in such a way that the partial area of the surface structuring is, in particular completely, covered by the protective layer;
4. d. Carrying out at least one further treatment step on the surface of the pressing tool, wherein the portion of the surface structuring covered by the metallic protective layer is protected against the effect of the at least one further treatment step.

In general, the pressing tools according to the invention are those with the help of which a workpiece, in particular a material plate of the type described in more detail at the beginning, can be pressed or produced, with a surface of the workpiece having a surface structure corresponding to the surface structuring of the pressing tool after pressing .

Insofar as material panels are to be produced in particular, which are to be used, for example, as floor or wall panels or in furniture production, these are primarily large-format pressing tools that have at least an edge length of more than one meter. Furthermore, they can also be pressing tools that are used for pressing plastic films, release films, PVC surfaces or LVT (Luxury Vinyl Tiles), whereby the size of the pressing tools in these cases depends on the respective end products. It is also possible to use the pressing tools in question to produce credit cards, passports, credit cards or plastic cards, i.e. workpieces with security features.

According to step a. In the method according to the invention, the surface structuring is first produced by introducing it into the surface of the pressing tool and/or applying it to the surface of the pressing tool; This can be done by means of material-applying and/or material-removing processes, as are already known from the prior art, for example by means of sintering, printing or etching processes. It is essential that the surface structuring produced in this step has at least one structure, which structure consists of at least one elevation and at least one depression; further structures can be produced in further successive steps. The at least one structure and the further structures can be, for example, a coarse structure or a fine structure, with this distinction being made on the basis of the characteristic sizes of the respective structures. Typically, the characteristic magnitude of the fine structures is significantly smaller than the characteristic magnitude of the coarse structures.

In any case, a structure, regardless of whether it represents a coarse or a fine structure, always includes at least one elevation and at least one depression that is deeper in relation to this elevation; In other words, the structure includes at least one mountain and one valley or a contour of the at least one structure includes at least one higher area and one lower area. The surface structuring of the surface of the pressing tool is preferably produced in several individual steps, for example in a first step (all) coarse structures and in a second step (all) fine structures of the surface structuring can be produced. The process steps b. until d. and all further process steps described below can be carried out either between these individual steps or after completion of all individual steps, i.e. after production of the entire surface structuring with all structures, in particular coarse and fine structures. Alternatively, a pressing tool with a corresponding surface structure can also be provided.

In step b. In the method according to the invention, a mask is applied to the surface or to the surface structuring of the pressing tool, so that at least that partial area of the surface structuring, which partial area has at least one structure, remains free. Accordingly, the at least one structure is according to step b. not covered by the mask.

After applying the mask, which can also be applied in several steps, the surface of the embossing tool, namely in particular the partial area of the surface, can undergo a treatment, for example activated, degreased and/or polished. Preferably, the subarea is selected so that it contains only coarse structures or only fine structures of the surface structuring.

In the next process step, step c., a metallic protective layer is applied to the partial area of the surface of the pressing tool, so that the at least one structure - i.e. both the elevation and the depression and also the transition area between the elevation and depression - is completely covered by the protective layer. However, the mask prevents the metallic protective layer from contacting and/or connecting to the surface of the embossing tool outside the partial area. The protective layer protects the structures of the surface structuring in the partial area from subsequent mechanical, galvanic, physical, thermal and/or chemical treatments.

In step d. the surface of the pressing tool is subjected to at least one further treatment step. Depending on the nature of this treatment, it may be beneficial to remove the mask from the surface before this step. Due to the protective layer, the structures located in the partial area, i.e. at least the at least one structure and/or preferably several/all coarse structures or fine structures of the surface structuring, are protected from the effect of this further treatment step. However, the areas of the surface that are not covered by the protective layer, in particular the surface structuring (this does not necessarily have to be present on the entire surface), can be polished, etched, irradiated, treated electrolytically or in any other way without impairment. In particular, the areas of the surface or the surface structuring that are not covered by the protective layer can also be subjected to several treatment steps without the structures lying under the protective layer or the protective layer itself being affected.

The at least one further treatment step can also be a step in producing the surface structuring. In particular, it can be provided that initially in step a. Only the rough structures of the surface structuring are produced, these rough structures are then covered with the metallic protective layer and then in step d. to produce further surface structuring structures, such as fine structures. Analogously, the fine structures can first be produced and protected by the protective layer and then the coarse structures can be introduced into the surface of the pressing tool.

Overall, using the method according to the invention, a selective treatment of individual areas of the surface structuring can be achieved, while contours and structures of the surface structuring that are particularly worthy of protection are reliably protected from the effect of this treatment, which can preferably be carried out over the entire surface, i.e. on the entire surface of the pressing tool can. A method for processing pressing tools is thus created which enables a simple and cost-effective production of a surface structuring, with all structures of the surface structuring having a very high level of detail and quality.

The said surface structuring of the pressing tool is not a structuring that is already present in the vast majority of industrially or handcrafted objects due to manufacturing inaccuracies. Rather, it usually involves a large number of individual structures that are intentionally introduced into the surface of the pressing tool in order to form a complex shape that corresponds to a specific template.

In a preferred embodiment of the method according to the invention, the surface structuring of the pressing tool is selected according to a surface structure of a natural wood or stone plate or a tile.

As a result, the workpieces that are pressed or produced using the pressing tool can be given the most natural feel and appearance possible. In particular, the surface structuring of a pressing tool produced according to this preferred embodiment is such that the workpiece processed with this pressing tool is given or impressed with a surface structure, which surface structure promotes the impression of a natural wood or natural stone slab.

In a further preferred embodiment of the method according to the invention, the metallic protective layer comprises at least one chromium layer or the metallic protective layer is formed by a chromium layer. This chromium layer is preferably applied to the surface of the pressing tool by means of electrolytic deposition.

In this way, the protective layer according to the invention can be applied to the partial area particularly easily and precisely. In addition, it can be ensured that even structures with a particularly small characteristic size and/or complex design, in particular fine structures, are covered completely and contour-following by the protective layer.

In a further preferred embodiment of the method according to the invention, the protective layer is formed by a hard chrome layer. This hard chrome layer can be one, preferably have a uniform layer thickness of at least 5 µm, preferably in the range from 5 µm to 50 µm, particularly preferably in the range from 10 µm to 20 µm.

As a result, the structures of the surface structuring covered by the protective layer are protected in a particularly reliable manner from mechanical force and the resulting deformation. By forming the protective layer as a hard chrome layer with a layer thickness of more than 50 µm, particularly reliable wear protection can also be guaranteed. The layer thickness of the hard chrome layer is particularly preferably not more than 0.5 mm.

In a further preferred embodiment of the method according to the invention, the mask prevents electrolytic deposition of chromium on the surface of the pressing tool covered by the mask.

Especially when the protective layer is formed by a chromium layer applied to the surface of the pressing tool by means of electrolytic deposition, the use of a mask according to this preferred embodiment enables a particularly simple and precise application of the protective layer. In particular, all areas of the surface of the pressing tool that lie outside the partial area can first be provided with this mask, so that full-surface chrome plating can then be carried out. This means that only the area not covered by the mask is covered with the protective layer; However, in all areas of the surface covered by the mask of this preferred embodiment, electrolytic deposition of chromium is reliably prevented.

In a further preferred embodiment of the method according to the invention, the mask is designed to be resistant to chromic acid.

This makes the mask or parts of the mask reusable. In particular, it becomes possible to leave parts of the mask on the surface after the metallic protective layer has been applied in order to prevent electrolytic deposition of chromium on certain parts of the surface of the pressing tool covered by the mask in one of the subsequent treatment steps. This further develops the processing method according to the invention.

In a further preferred embodiment of the method according to the invention, producing the surface structuring in or on the surface of the pressing tool includes at least a first structuring step, preferably several structuring steps. The at least one structure of the surface structuring is preferably a coarse structure or a fine structure. Preferably, the metallic protective layer is applied to the surface of the pressing tool after the first structuring step in such a way that only a portion of the surface structuring having the coarse structure or the fine structure is covered by the protective layer.

By only covering the coarse structures with the protective layer, it can be ensured that the fine structures, whose characteristic size is generally at least an order of magnitude smaller than that of the coarse structures, can be treated and/or shaped in any way without this the coarse structures that have already been treated and/or formed can be affected. The same applies if only the fine structures are covered by the protective layer; In this case, the coarse structures can be treated and/or shaped without the fine structures being affected. The partial area of the surface structuring is preferably selected in such a way that all coarse structures or all fine structures are covered by the protective layer and are therefore protected from the effects of further treatment steps.

In a further preferred embodiment of the method according to the invention, the protective layer remains on the surface of the pressing tool after carrying out the at least one further treatment step or even after carrying out all further treatment steps.

In particular, the application of the protective layer can not only serve the purpose of protecting the underlying structures from further treatment steps, but can also contribute to the further shaping of the surface structuring itself and / or to protecting the surface structuring from wear if the pressing tools are used as intended for pressing workpieces become.

In a further preferred embodiment of the method according to the invention, the protective layer is at least partially removed from the surface of the pressing tool after carrying out the at least one further treatment step or after carrying out all further treatment steps.

This means that when the pressing tool is used as intended, the surface can be damaged chenstructuring directly, i.e. directly, with the workpiece to be pressed, in particular with an outer material layer of the workpiece, brought into contact and impressed into it. This makes it possible to form a very precise impression of the surface structure and consequently also to produce an extremely true-to-original surface structure in the workpiece to be pressed; The protective layer cannot distort this surface structure.

In a further preferred embodiment of the method according to the invention, the protective layer is removed by electrolytic removal of the chromium layer. In this case, those areas of the surface of the pressing tool that should not be removed can be masked beforehand. In a further preferred embodiment, areas of the protective layer can also be covered by the masking in order to leave it on the surface of the pressing tool at least until a further processing step.

In this way, the protective layer can be removed from the surface of the pressing tool particularly easily and efficiently. In addition, the material of the protective layer is available for applying further protective layers to the same or other pressing tools. The method according to the invention according to this preferred embodiment is therefore characterized by particularly high resource efficiency.

In a further preferred embodiment of the method according to the invention, the areas on the surface not covered by the protective layer are matt etched or mechanically processed in a subsequent treatment step in order to produce a matt-appearing surface and/or coated with a further chromium layer.

This makes it possible to easily change the degree of gloss of the additional chrome layer applied, for example in areas or over the entire surface. The method according to this preferred embodiment therefore facilitates the production of pressing tools with matt chrome layers.

In a further preferred embodiment of the method according to the invention, the at least one further treatment step comprises polishing, in particular electropolishing, and/or etching, in particular matt etching, of the surface of the pressing tool. Additionally or alternatively, the at least one further treatment step can include a full-surface or partial gloss level adjustment, wherein the gloss level adjustment is carried out by applying at least one metallic coating to the surface of the pressing tool and/or by mechanical or chemical treatment of the surface of the pressing tool.

The method according to the invention according to this preferred embodiment is characterized by high flexibility in the surface design of the pressing tool, but at the same time ensures that areas of the surface structuring that should not undergo a specific surface design are reliably protected from the effect of these further treatment steps.

In a further preferred embodiment of the method according to the invention, the surface structuring is produced using an etching process.

Accordingly, the surface structuring is introduced into the surface of the embossing tool by means of the etching process and usually using an etching resist. In this way, the surface structuring can also be produced in several individual steps.

In a further preferred embodiment of the method according to the invention, the protective layer is only present on part of the surface structure or the surface of the pressing tool.

This allows further treatment of the uncovered parts of the surface structure or the surface.

An object on which the invention is based is further achieved by a pressing tool, in particular a pressing sheet or press belt, for producing a workpiece, such as a material plate, the pressing tool having a surface structuring arranged in or on a surface of the pressing tool, which surface structuring has at least one structure with an elevation and a depression - located deeper in relation to the elevation, and a metallic protective layer, which metallic protective layer is arranged on the surface in such a way that the structure is covered by the protective layer but at least part of the surface, in particular the surface structuring, is not covered by the protective layer is.

In principle, all of the above statements also apply to this pressing tool according to the invention. In particular, the partially present protective layer enables the protection of at least one structure of the surface structuring, in particular all fine and/or coarse structures, before the effect of further treatment steps that are carried out on the pressing tool. In addition, the protective layer protects the underlying structures, i.e. the part of the surface structure covered by it, from wear during the intended use of the pressing tool for producing or pressing the workpieces.

In a preferred embodiment of the pressing tool according to the invention, the surface structure of the pressing tool corresponds to a surface structure of a natural wood or stone plate. Accordingly, the surface structure of natural wood or stone panels serves as a template for the surface structuring, which is the surface structuring of the pressing tool.

As a result, the workpieces that are pressed or produced using the pressing tool can be given the most natural feel and appearance possible. This promotes the impression of a natural wood or natural stone slab, which means that the workpieces processed or pressed or produced with the pressing tool are of higher quality.

In a preferred embodiment of the pressing tool according to the invention, the protective layer comprises at least one chromium layer or the protective layer is formed by a chromium layer. The protective layer is preferably formed by a hard chrome layer with a layer thickness of at least 5 μm, preferably in the range from 5 μm to 50 μm, particularly preferably 10 μm to 20 μm.

By using a chrome layer, the structures of the surface structuring covered by the protective layer are protected in a particularly reliable manner from mechanical force and the resulting deformation. By forming the protective layer as a hard chrome layer with a layer thickness of more than 50 µm, particularly reliable wear protection can also be guaranteed. The layer thickness of the hard chrome layer is particularly preferably not more than 0.5 mm.

In order to enable an exact, true-to-original molding of the surface structuring into the surface of the workpieces, the surface structuring is produced according to a preferred embodiment of the pressing tool according to the invention by means of a material-removing process, in particular by means of an etching process, and/or by means of a material-applying process, in particular by means of a printing process .

Short description of the characters

• 1 eine schematische Darstellung eines Pressblechs mit einer Oberflächenstrukturierung in einer axonometrischen Ansicht,
• 2 eine schematische Darstellung des Pressblechs aus 1 in einer Schnittansicht, und
• 3A-3C einige der Schritte zur Bearbeitung einer Oberfläche des Presswerkzeugs aus 1.

The invention is described below as an example using the embodiment variants shown in the figures. The following statements are therefore exemplary and are intended to explain the idea of the invention, but in no way represent it in a restrictive or even conclusive manner. This shows:

• 1 a schematic representation of a pressed sheet with a surface structuring in an axonometric view,
• 2 a schematic representation of the pressed sheet 1 in a sectional view, and
• 3A-3C some of the steps for processing a surface of the pressing tool 1 .

Ways of carrying out the invention

1 shows a pressing tool 1 designed as a pressed sheet with a surface 2. If the pressing tool 1 is used as intended for the production or pressing of workpieces, a surface structuring 10 arranged on the surface 2 serves ( 2 ) to give a workpiece, in particular a material plate, a certain surface structure in order to reinforce or create the impression of a natural wood, tile or natural stone surface for a viewer of the workpiece. For this purpose, the surface structuring 10 of the pressing tool 1 is selected according to a specific template, for example corresponding to a natural wooden surface. In the course of the manufacturing process of the pressing tool 1 or the processing of its surface 2, the surface structuring 10 must therefore be introduced into or applied to the surface 2 of the pressing tool 1 in such a way that the surface structure true to the original is created by molding the surface structuring 10 into the workpiece .

2 shows a schematic detailed view of the pressing tool 1 in a highly simplified sectional view, the surface structuring 10 being formed from several individual layers 15, which individual layers 15 are applied to a core 14 of the pressing tool 1 by means of a material-applying process. Overall, this results in several structures, each of which has at least one elevation 4 and at least one depression 3 that is deeper in relation to the elevation 4. In other words, the elevation 4 of a structure is further apart from the core 14 of the pressing tool 1 than the depression 3 of the structure. These structures of the surface structuring 10 represent, so to speak, the negative those forms of the surface structure that are to be produced in the workpieces to be machined with the pressing tool 1.

How out 2 and 3A As can be seen, the surface structuring 10 has coarse structures 16 and fine structures 17, with the coarse structures 31 and fine structures 17 differing from one another by a characteristic size of their structures. In the exemplary embodiment shown, for example, the surface structuring 10 in the section shown comprises five elevations 4, the centrally located elevation 4 having more than eleven individual layers 15 and is therefore part of a coarse structure 31, and the four outer elevations 4 each having significantly fewer, namely between four and six, individual layers 15 and can therefore be attributed to a fine structure 17.

These differences in the characteristic size of the individual structures of the surface structuring 10 result in challenges in the production of the respective structures as well as in the processing of the surface 2 of the pressing tool 1. For example, it can happen that fine structures 17 during the production or processing of Coarse structures 31 are completely destroyed; Conversely, the processing or production of fine structures 17 often leads to unwanted deformations of the coarse structures 31. In particular, treatment steps that are to be carried out over the entire surface 2 of the pressing tool 1, such as full-surface polishing, are therefore generally not suitable for production and processing appropriate pressing tools 1 suitable. In addition, selective protection of individual structures can also make sense if only certain areas of the surface 2 are to be subjected to a subsequent treatment step in order to be absolutely sure that the structure worthy of protection does not experience the effect of this subsequent treatment step.

For this reason, the method according to the invention provides for the application of a metallic protective layer 11 to the surface of the pressing tool 1, in such a way that a partial area of the surface structuring 2 is covered by the protective layer 11, the partial area being a structure to be protected, for example, before subsequent treatment steps - here the rough structure 31 - has. For this purpose, after producing a (at least preliminary) surface structuring 2 ( 3A) a mask 18 is applied to the surface 2 of the pressing tool 1 in such a way that at least the partial area of the surface structuring 10 containing the coarse structure 31 to be protected remains free ( 3B) . The metallic protective layer 11 is then applied to the free partial area, for example by electrolytic deposition of a hard chromium layer, so that the coarse structure 31 to be protected is completely covered by the protective layer 11 and protected from the effect of a subsequent treatment step ( 3C ).

In the exemplary embodiment shown, the protective layer 11 ensures that the coarse structure 31 to be protected can no longer be shaped or treated further. The subsequent treatment step, which should preferably be carried out over the entire surface of the pressing tool, can be, for example, polishing (such as electropolishing) and/or etching (such as matt etching) of the surface 2 of the pressing tool 1. Alternatively or additionally, the gloss level can also be adjusted. In the exemplary embodiment shown, for example, a gloss level adjustment was carried out by applying several bright chrome platings 13 to individual elevations 4 of the fine structure 17; Subsequently, by polishing the surface 2, in particular individual or all bright chrome platings 13 and/or the metallic protective layer 11, a sectional matting of a finally applied, full-surface further chrome layer 12 can be achieved.

Due to the metallic protective layer, these further treatment steps no longer have any effect on the structures underneath the protective layer; Before or between the further treatment steps, the mask 18 can of course be removed again from the surface 2 of the pressing tool 1 and/or the surface 2 can be pretreated in any way.

The metallic protective layer 11 can be removed again from the surface 2 of the pressing tool 1 after the surface structuring 10 has been completed. Alternatively, the protective layer 11 can also remain on the surface 2 of the pressing tool 1 in order to protect particularly exposed areas of the surface structuring 10 from wear during the intended use of the pressing tool 1.

Reference symbol list

1

Press tool

10

Surface structuring

11

metallic protective layer

12

another (full-surface) chrome layer

13

Bright chrome plating

14

core

15

Single layers

16

Rough structure

17

Fine structure

18

mask

2

surface

3

deepening

4

survey

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 3010704 B1 [0010]

Claims (20)

Method for processing a surface (2) of a pressing tool (1), in particular a press sheet or a press belt, which method comprises at least the following steps: a. Producing a surface structuring (10) in or on the surface (2) of the pressing tool (1), wherein the surface structuring (10) comprises at least one structure with an elevation (4) and a depression (3) that is deeper in relation to the elevation (4). ; b. Applying a mask (18) to the surface (2) in such a way that at least a portion of the surface structuring (10) having the at least one structure is not covered by the mask (18); c. Applying a metallic protective layer (11) to the surface (2) of the pressing tool (1) in such a way that the partial area of the surface structuring (10) is covered by the protective layer (11); d. Carrying out at least one further treatment step on the surface (2) of the pressing tool (1), the partial area of the surface structuring (10) covered by the metallic protective layer (11) being protected against the effect of the at least one further treatment step. Procedure according to Claim 1 , characterized in that the surface structuring (10) of the pressing tool (1) is selected according to a surface structure of a natural wood or stone plate. Procedure according to one of the Claims 1 or 2 , characterized in that the protective layer (11) comprises at least one chromium layer or is formed by a chromium layer, the chromium layer being applied to the surface (2) of the pressing tool (1) by means of electrolytic deposition. Procedure according to Claim 3 , characterized in that the protective layer (11) is formed by a hard chrome layer with a layer thickness of at least 5 µm, preferably in the range from 5 µm to 50 µm, particularly preferably 10 µm to 20 µm. Procedure according to one of the Claims 3 or 4 , characterized in that the mask (18) prevents electrolytic deposition of chromium on the surface (2) of the pressing tool (1) covered by the mask (18). Procedure according to one of the Claims 3 until 5 , characterized in that the mask (18) is designed to be resistant to chromic acid. Procedure according to one of the Claims 1 until 6 , characterized in that producing the surface structuring (10) in or on the surface (2) of the pressing tool (1) comprises at least a first structuring step and that the at least one structure of the surface structuring (10) is a coarse structure (16) acts, wherein the metallic protective layer (11) is applied to the surface (2) of the pressing tool (1) after the first structuring step in such a way that only a partial area of the surface structuring (10) having the coarse structure (16) is covered by the protective layer (11). is. Procedure according to one of the Claims 1 until 7 , characterized in that the protective layer (11) remains on the surface (2) of the pressing tool (1) after carrying out the at least one further treatment step. Procedure according to one of the Claims 1 until 7 , characterized in that the protective layer (11) is at least partially removed from the surface (2) of the pressing tool (1) after carrying out the at least one further treatment step. Procedure according to Claim 9 , characterized in that the removal of the protective layer (11) occurs by electrolytic removal of the chromium layer. Procedure according to one of the Claims 8 until 10 , characterized in that the parts of the protective layer (11) remaining on the surface (2) are etched matt in a subsequent treatment step and coated with a further chrome layer (12). Procedure according to one of the Claims 1 until 11 , characterized in that the at least one further treatment step comprises polishing and/or etching the surface (2) of the pressing tool (1). Procedure according to one of the Claims 1 until 12 , characterized in that the at least one further treatment step comprises a gloss level adjustment, wherein the gloss level adjustment by applying at least one metallic coating to the surface (2) of the pressing tool (1) and / or by mechanical or chemical treatment of the surface (2) of the pressing tool ( 1) takes place. Procedure according to one of the Claims 1 until 13 , characterized in that the surface structuring (10) is produced using an etching process. Procedure according to one of the Claims 1 until 14 , characterized in that the protective layer (11) is only present on part of the surface structuring (10) or the surface (2) of the pressing tool (1). Pressing tool (1) for producing a workpiece, in particular pressed sheet or press belt, having a surface structuring (10) arranged in or on a surface (2) of the pressing tool (1), which surface structuring (10) has at least one structure with an elevation (4) and a depression (3) which is lower in relation to the elevation (4), and a metallic protective layer (11), which metallic protective layer (11) is arranged on the surface (2) in such a way that the structure of the protective layer (11) but at least part of the surface (2), in particular the surface structuring (10), is not covered by the protective layer (11). press tool (1). Claim 16 , characterized in that the surface structure (10) of the pressing tool (1) corresponds to a surface structure of a natural wood or rock plate. Pressing tool (1) according to one of the Claims 16 or 17 , characterized in that the protective layer (11) comprises at least one chromium layer or is formed by a chromium layer. press tool (1). Claim 18 , characterized in that the protective layer (11) is formed by a hard chrome layer with a layer thickness of at least 5 µm, preferably in the range from 5 µm to 50 µm, particularly preferably 10 µm to 20 µm. Pressing tool (1) according to one of the Claims 16 until 19 , characterized in that the surface structuring (10) is produced by means of an etching process and/or by means of a material-applying process, in particular by means of a printing process.

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