EP-4126443-B1 - METHOD FOR SURFACE TEXTURING OF A DRESSING ROLLER

Inventors

• VOGT, OLIVER
• JUNGE, Fabian
• Cetinkaya, Burak William

Dates

Publication Date

20260513

Application Date

20210317

Claims (10)

1. Method for surface texturing a skin pass mill roll (7) for skin passing a metal sheet, in particular a steel strip, wherein a skin pass mill roll (7) is provided and a pattern is generated on the roll surface by means of laser pulses (1) from a pulsed laser, wherein a sequence of overlapping laser pulses (1) is directed at the roll surface to produce a sequence of cup-shaped depressions that merge into one another, whereby directing a sequence of laser pulses onto the roll surface means that successive pulses strike spatially one after the other at different positions on the roller surface, characterized in that : two successive overlapping laser pulses have a pulse spacing (d) that is between 0.75 and 1.25 of a pulse radius, wherein the sequence of laser pulses is repeatedly interrupted in a targeted manner or changed in its pulse energy for the formation of a repeating pattern.
2. Method according to claim 1, wherein the pulsed laser is a short-pulse laser, preferably an ultrashort-pulse laser.
3. Method according to claim 1, wherein the sequence of laser pulses for forming a deterministically repeating pattern is repeatedly interrupted in a targeted manner or its pulse energy is changed.
4. Method according to one of the preceding claims, wherein at least in one region of the pattern, preferably across the entire area of the pattern, each pair of two successive overlapping laser pulses has the same pulse spacing (d).
5. Method according to one of the preceding claims, wherein material structures (9, 10, 11, 12, 15, 14, 15) bounded by the pattern with a sequence of smoothing laser pulses having a smoothing laser pulse energy that is lower than a pattern pulse energy, i.e., a pulse energy of the sequence of laser pulses with which the pattern is generated.
6. Method according to claim 5, wherein the smoothing laser pulse energy is 60 percent or less of the pattern pulse energy.
7. Method according to one of claims 5 or 6, wherein an entire skin pass area of the skin pass roll is processed sequentially with overlapping pulses, wherein the smoothing pulse energy is set for processing an area (9, 10, 11, 12, 15, 14, 15) and the pattern pulse energy is set for processing the pattern.
8. Method according to one of claims 5 to 7, wherein an entire skin pass area of the skin pass roll (7) is completely processed during processing with a sequence of overlapping pulses (8) in such a way that within a pattern boundary each pattern pulse (8) is overlapped with at least four, preferably exactly four, pulses, each of which is either a pattern pulse or a smoothing pulse.
9. Method according to one of the preceding claims, wherein the cup-shaped depressions recesses are between 6 in and 14 µm.
10. Method according to one of the preceding claims, wherein the cup-shaped recesses have a diameter of between 20 and 80 µm.

Description

The invention relates to a method for surface texturing of a dressing roller for dressing a metallic sheet according to the preamble of claim 1 (see e.g. DE 10 2012 017703 A1 ). In the production of metallic sheets, for example steel sheets, especially steel sheets made from steel strip, a targeted adjustment of the surface topography is relevant in many application areas. It is known in practice that sheet metal can be tempered to achieve specific surface topographies. To obtain the desired surface topography of the tempered sheet metal, a specific texturing of the tempering rollers is applied, among other methods. This means that the outer surface of the tempering roller, which comes into contact with the sheet metal, for example, the steel strip, is given a specific surface texture. In order for the surface topography of a sheet, for example made from a steel strip, to meet the highest standards, the intended surface texture of the tempering roller must consequently be produced as accurately and reproducibly as possible. A typical procedure is to provide a dressing roller, the surface of which is then subjected to targeted structuring. A known group of methods for structuring a roller surface, more precisely and equivalently within the scope of the present invention: roller shell surface, comprises methods for structuring using a pulsed laser. For example, it is known to effect material removal on the surface of a skin-treating roller using a pulsed laser, preferably a short-pulse or ultrashort-pulse laser. In methods of this type, a pattern is created on the roller surface by directing laser pulses of a pulsed laser onto the roller surface and causing a temporary melting of the material present on the surface at the point of impact. Part of the melted material evaporates, and the unevaporated part solidifies again. In the EP 2 892 663 B1 It is described that a deterministic surface structure, meaning in particular not a stochastic surface structure, is formed on a roller, wherein the depressions have a multitude of overlapping pits, which are arranged, for example, in such a way that they define a double-I-shaped, H-shaped, cross-shaped, C-shaped or X-shaped material structure in the roller surface. Against the background of the steadily increasing demands on the homogeneity of the strip surface and the reproducibility and uniformity of the roughness parameters combined with the highest possible cleanliness, the task arises to provide a process that is further developed compared to known methods, with which improved surface properties of the dressed sheets are made possible. Furthermore, a generic method for texturing is exemplified in the EP 2 689 883 A1 described. The problem is solved by a method for surface texturing of a dressing roller with the features of claim 1. The invention relates to a method for surface texturing of a tempering roller. In particular, tempering rollers for tempering a metal sheet are concerned. The metal sheet can, in particular, be a steel strip. The method initially provides that a tempering roller is supplied and a pattern is generated on the roller surface by means of laser pulses from a pulsed laser. The outer surface of a skin-treating roller is made of steel, for example. The roller is, for example, at least on its outer surface, preferably entirely, made of a steel material, preferably a classic cold-rolled steel with a chromium content of up to 3%. The plan is to create a pattern on the roller surface. Laser pulses from a pulsed laser are used to create the pattern. A short-pulse laser, preferably an ultrashort-pulse laser, can be used as a pulsed laser. The term "short-pulse laser" refers to a pulsed laser with pulse durations in the nanosecond range and pulse widths greater than 100 picoseconds. The term "ultrashort-pulse laser" refers to a pulsed laser with pulse durations of less than 100 picoseconds. A suitable ultrashort pulse laser is, for example, a short pulse laser which has a pulse repetition frequency between 10 kHz and 2.5 MHz and/or a wavelength between 930 and 1090 nm, preferably with a pulse duration between 0.4 ps and 100 µs, particularly preferably 1 ps and 10 µs. For example, it may be provided that the pulsed laser has an average power output of between 10 and 150 watts, in particular between 15 and 100 watts, and most preferably between 20 and 70 watts. The desired pattern is generated on the roller surface using a pulsed laser. According to the invention, this is achieved by directing a sequence of laser pulses onto the roller surface. The sequence of laser pulses comprises successive, overlapping pulses. Due to the overlap of successive pulses, a sequence of cup-shaped depressions is formed, which also overlap each other. According to the invention, two successive, overlapping laser pulses have a pulse interval of between 0.75 and 1.25 times the pulse radius. In the context of this invention, directing a sequence of laser pulses onto the roll