Method and Apparatus for Structuring a Surface for an Embossing Tool

Abstract

The invention concerns a method of structuring a surface for an embossing tool, in which a tool blank with a surface is provided and in which an embossing structure is formed on the surface of the tool blank, which is intended for embossing a predetermined material. The task of proposing a method for structuring a surface for an embossing tool, in which a process-precise structuring, in particular with high resolution, is achieved and the method is simplified, is solved by printing structural material onto the tool blank by a 3D printing method in order to provide the embossing structure and the embossing structure comprises the structural material printed by the 3D printing method. The invention also concerns an embossing tool, an apparatus for structuring a surface for an embossing tool and a digital printing template.

Claims

1. A method for structuring a surface for an embossing tool, comprising: providing a tool blank with a surface, and forming an embossing structure on the surface of the tool blank for embossing a predetermined material, wherein: structural material is printed by a 3D printing process onto the tool blank to provide the embossing structure; and the embossing structure comprises the structural material printed by the 3D printing process.

2. The method according to claim 1, wherein: the structural material printed by the 3D printing process comprises metal, metal compounds, or a combination thereof.

3. The method according to claim 1, wherein: the structural material printed by the 3D printing process comprises a wax, a UV-curable ink, or a combination thereof, and wherein the structural material has a pasty consistency.

4. The method according to claim 1, wherein: a coating is applied to at least one of the structural material printed by the 3D printing process or the surface of the tool blank by an electrochemical treatment.

5. The method according to claim 4, wherein: the coating comprises Cr, Ni, Cu Zn, or a combination thereof.

6. The method according to claim 1, wherein: the 3D printing process comprises printing the structural material in layers.

7. The method according to claim 1, wherein: the embossing structure has a height relative to the surface of the tool blank of 10 m to 200 m.

8. The method according to claim 1, wherein: the structural material printed by the 3D printing process is at least partially removed after printing, during printing, or a combination thereof by ablation, thermal treatment, chemical treatment, or a combination thereof.

9. The method according to claim 8, wherein: at least one part of regions of the embossing structure from which the structural material was at least partially removed is filled by a supporting material.

10. An embossing tool for embossing a predetermined material, comprising: an embossing structure formed on a surface for embossing a predetermined material, wherein: the embossing structure comprises structural material printed on the surface by a 3D printing process.

11. The embossing tool according to claim 10, wherein: the embossing tool is designed as a roll, roll shell, plate, or a combination thereof.

12. The embossing tool according to claim 10, wherein: the embossing tool is adapted for at least one of hot embossing or cold embossing.

13. An apparatus for structuring a surface for an embossing tool, comprising: a retaining device for holding a tool blank with a surface, structuring means for structuring the surface, wherein: the structuring means are arranged for a 3D printing process for printing structural material onto the tool blank to form an embossing structure on the surface, and the embossing structure comprises the structural material printed by the 3D printing process.

14. The apparatus according to claim 13, further comprising coating means for coating at least one of the structural material printed by the 3D printing process or the surface of the tool blank by an electrochemical treatment.

15. A non-transitory computer-readable medium comprising a digital printing template to direct at least one processor to pattern a surface for an embossing tool by a method according to claim 1.

16. A non-transitory computer-readable medium comprising a digital printing template to direct at least one processor to pattern a surface for an embossing tool by a method according to claim 2.

17. A non-transitory computer-readable medium comprising a digital printing template to direct at least one processor to pattern a surface for an embossing tool by a method according to claim 3.

18. A non-transitory computer-readable medium comprising a digital printing template to direct at least one processor to pattern a surface for an embossing tool by a method according to claim 4.

19. A non-transitory computer-readable medium comprising a digital printing template to direct at least one processor to pattern a surface for an embossing tool by a method according to claim 6.

20. A non-transitory computer-readable medium comprising a digital printing template to direct at least one processor to pattern a surface for an embossing tool by a method according to claim 8.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Further advantageous exemplary forms of the invention can be found in the following detailed description of some exemplary forms of the present invention, in particular in connection with the figures.

[0043] FIGS. 1a-c schematic views of structured surfaces of state of the art embossing tools,

[0044] FIGS. 2a-d example of the execution of the invention method and embossing tool according to the invention,

[0045] FIG. 3 an example of the implementation of the device according to the invention, and

[0046] FIG. 4 different examples of a storage medium for a digital template according to the invention.

DESCRIPTION OF THE INVENTION

[0047] FIG. 1a-c first show schematic views of structured surfaces 2 of embossing tools 4, how these are generated by means of state-of-the-art structuring processes.

[0048] FIG. 1a shows a surface 2 with a structure introduced by mechanical engraving over a graver. The graver (not shown) is used to create recesses 6, the shape of which is typically determined by the shape of the graver and which, in particular, is tapered in depth as shown in FIG. 1a and, in particular, pointed.

[0049] FIG. 1b shows a surface 2 with a structure introduced by laser engraving or direct laser ablation. Laser ablation is used to remove material directly from surface 2 to create 6 recesses. The shape of the recesses 6 depends on the properties of the material of the surface under the influence of laser radiation during ablation and is particularly rounded in depth or rather in the depth profile as shown in FIG. 1b.

[0050] FIG. 1c shows a surface 2 with a structure introduced by etching methods. A stencil material is first applied to surface 2 (not shown) and, in particular, structured by exposure and partially removed. In the removed areas, the surface 2 is attacked with an etching solution so that recesses 6 are formed. The shape of the recesses 6 is determined by the etching attack on the material of surface 2 and is typically rounded in depth or rather the depth profile. Also, as indicated in FIG. 1c, undercuts of the template and the surface may occur.

[0051] The state of the art processes described here have in common that material is removed from the surface to be structured in order to provide an embossed structure.

[0052] FIG. 2a-c show schematic views of how to structure a surface 8 for an embossing tool.

[0053] FIG. 2a first shows the surface 8 of a tool blank before structuring. The surface 8, for example, can be a metallic surface and in particular a surface based on Fe, Cr, Ni, Cu and/or Zn or their compounds or steel. In particular, the surface 8 is nickel-plated. The surface 8 is a surface of a tool blank and can be, for example, a surface of a plate, a roll or a roll shell.

[0054] An embossing structure is formed on the surface 8 of the tool blank, which is intended for embossing a given material. By a 3D printing process structural material is printed onto the tool blank to provide the embossed structure. The structural material is selectively applied to the surface. In this way elevations 10 are formed on the surface 8. In this example, the 3D printing process involves applying the structural material layer by layer, with the embossed structure comprising the structural material printed by the 3D printing process.

[0055] In FIG. 2b the surface 8 is shown after a first layer of structural material has been applied, the structural material forming elevations 10. The applied material may comprise or consist of metallic materials such as, in particular, steel, nickel, copper, zinc, chromium and their alloys and composite materials, with further metallic compounds with iron, nickel, copper, zinc and/or chromium also being possible. In the example shown, a combination of wax and UV-curable ink is applied by printing as a structural material for the elevations 10. The combination of wax and UV-curable ink has a pasty consistency, which means that the material can be printed reliably on the one hand and does not run on the surface on the other, so that the elevations 10 can be formed with a high resolution.

[0056] The structural material is applied in layers, so that in particular an embossed structure with a varying depth profile can be formed. The surface 8 of FIG. 2b is shown schematically in FIG. 2c after several layers of structural material have been applied and the elevations 10 are further developed. The elevations 10 show a height from 10 m to 1000 m, especially from 30 m to 200 m or 40 m to 100 m. The thickness of the individual layers applied is from 1 m to 10 m, in particular from 5 m to 10 m. In order to improve the accuracy of the embossed structure and to smooth the surface of the printed structural material, the structural material can optionally be partially removed again, in particular by means of ablation such as laser ablation.

[0057] It is conceivable that the surface 8 structured in this way with elevations 10 from FIG. 2c is already used as the embossing structure of an embossing tool insofar as the specified material to be embossed can be embossed by a corresponding surface, in particular with regard to the hardness of the printed structural material. In particular, such a use is conceivable if metallic structural materials are applied to the surface.

[0058] In the example shown in FIG. 2d, the exposed surface 8 of the tool blank and the structural material or rather the elevations 10 comprising the combination of wax and UV-curable ink are provided with a coating 12, whereby the coating 12 has a higher hardness than the printed structural material. This allows the embossing structure to be used for embossing harder materials and increases the service life of the embossing tool. The coating can also be smoothed.

[0059] To apply the coating 12 electrochemical methods can be used. If the surface 8 and/or the printed structural material or elevations 10 have electrically insulating properties, the surface 8 and/or the printed structural material or elevations 10 can be made accessible for electrochemical treatment via an activator. For example, the surface 8 and the printed structural material are exposed to a solution with an activator, especially in a bath with a solution comprising Pd. In particular, an electrically conductive coating of Cu and/or Ni is applied to facilitate an electrochemical treatment. An electrochemical treatment for the application of one or more coatings in the form of electroplating can be carried out, in particular chromium plating and/or nickel plating.

[0060] Several layers can be applied, e.g. chromium plating and/or nickel plating can be preceded by the application of Cu, Zn and/or Ni to improve the adhesion of the chromium plated and/or nickel plated layer. In particular, after a Cu layer has been applied to the activated surface 8 and/or elevations 10, a Zn layer is applied and nickel plating is carried out so that the outermost layer of the embossed structure is formed by the nickel plated layer. The embossed structure obtained in this way then essentially has a nickel-plated surface and can be used for embossing hard materials.

[0061] In another design, the surface or structural material is coated with 1 m-10 m Ni, preferably 2 m to 3 m Ni, and a Cr layer with a thickness of 1 m to 20 m, preferably 4 m to 6 m, is applied to the Ni layer. In this way the outer layer is formed of the chrome plating.

[0062] In an optional, not shown implementation, the structural material printed on surface 8 can be at least partially removed after application of the coating 12. This is particularly advantageous if the structural material printed on the surface does not have sufficient hardness and/or heat resistance for embossing, in particular hot embossing. For example, by the 3D printing process a structural material comprising a wax is applied which, after the coating has been applied, is softened or melted and removed by heating. A supporting material can be introduced into the resulting cavities under the coating 12, which, for example, has a higher hardness and/or heat resistance than wax.

[0063] FIG. 3 shows a device 14 for structuring a surface for an embossing tool 16, whereby in particular the method according to the invention can be carried out via the device. The device comprises a receiving means 18 for receiving a tool blank with a surface and structuring means 20 for structuring the surface. The structuring agents 20 are set up for a 3D printing process for printing structural material onto the tool blank. For example, structuring means 20 include a 3D printing device with a print head that can selectively output 22 material to print 24 structural material. Hereby an embossed structure 26 can be formed on the surface, the embossed structure 26 comprising the structural material 24 printed by the 3D printing process.

[0064] FIG. 4 finally shows different execution examples of storage media, on which an example of the execution of a digital template can be stored, which contains information on how to structure a surface for an embossing tool according to the invention. The storage medium may, for example, be a magnetic, electrical, optical and/or other storage medium. For example, the storage medium may be part of a processor, such as a (non-volatile or volatile) program memory of the processor, or part of it. Examples of a storage medium are a flash memory 410, an SSD hard disk 411, a magnetic hard disk 412, a memory card 413, a memory stick 414 (e.g. a USB stick), a CD-ROM or DVD 415 or a floppy disk 416.