JP2001321806A - Laser beam dull roll and method for working it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam dull roll for reducing the local wear of a back-up roll and a method for working it. SOLUTION: In a work roll for cold-rolling on which laser beam dulling is performed, this laser dull roll has the hole diameter or/and hole depth of a dull part in roll edge parts smaller than those in the roll center part. In the method for laser beam dulling the work roll for cold-rolling, at the initial laser beam working or non-grinding/laser beam reworking, by defocusing a laser beam in the roll edge parts where contact rate with a steel sheet is lower and making the hole diameter or/and hole depth smaller than those in the roll center part, the local wear of the back-up roll is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser dull roll and a laser dull processing method for reducing a friction coefficient of a roll edge portion having a low contact ratio with a steel sheet in laser dull processing.

[0002]

2. Description of the Related Art Conventionally, in the so-called non-grinding re-laser processing, in which initial dulling is performed or dull rolls that have been used and worn are ground again without grinding, so-called non-grinding re-lasing, uniform processing is performed over the entire width. Further, a range similar to the initial laser processing was also performed on a range (hereinafter, referred to as a processing width) in a roll axis direction to be processed at the time of re-laser processing.

[0003]

In such a conventional technique, the roll edge portion having a low contact ratio with the steel sheet has less wear and a high coefficient of friction over a long period of time as compared with the roll center portion. A portion corresponding to the work roll edge portion is locally worn, causing slip defects on the work roll, and in some cases, spalling. Therefore, a processing method for reducing local wear of the backup roll is desired.

[0004] The present invention has been made in view of such problems of the prior art, and has as its object to provide a laser dull roll capable of reducing local wear of a backup roll, and a method of processing the same. .

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is that, in a cold rolled work roll subjected to laser dulling, the roll edge portion has a dull hole diameter and / or a hole depth greater than a roll center portion. In the laser dull roll characterized by having a small, and laser dull processing,
Edge parts with a low contact ratio with the steel plate during initial laser processing and non-grinding re-laser processing are defocused with laser light and the hole diameter or / and hole depth are made smaller than the roll center part, so that the edge part This is to reduce the coefficient of friction. Further, at the time of re-laser processing, a laser dull processing method in which the processing width is made narrower than that of the initial laser processing so as to reduce the increase in the friction coefficient of the edge portion and to reduce the local wear of the backup roll.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 shows the trajectory of the laser processing head at the time of initial processing and reprocessing for a roll to be processed. FIG. 2 is a conceptual diagram showing a cross section of the roll surface before use at the time of the initial processing in which the processing as shown in FIG. 1 is performed. In the edge portion, the laser processing head defocuses (distances to the workpiece). The hole diameter and the hole depth are smaller than those of the center part. In the present invention, at the time of dulling, the object can be achieved if at least one of the hole diameter and the hole depth of the dull is smaller at the roll edge portion than at the roll center portion.

FIG. 3 shows the distribution of the friction coefficient in the roll width direction before use at the time of the initial processing in which the processing as shown in FIG. 1 is performed. By reducing the friction coefficient of the edge portion having a low contact ratio with the steel sheet, local wear of the backup roll can be reduced.

As described above, according to the present invention, the wear of the backup roll can be reduced locally at the edge portion of the work roll for cold rolling by suppressing the increase in the coefficient of friction by defocus laser processing.

[0009]

The working pattern of the initial laser dull roll is
Maximum defocus distance 1mm, defocus processing range: 7
0 mm, processing width: 1340 mm, the re-laser processing pattern after rolling and the defocus processing conditions were the same as the initial laser processing, and the processing width was 1200 mm.

FIG. 4 shows the profile of the backup roll when rolling is performed for about one month under these conditions. In addition, the profile of the prior art is also shown for comparison. As can be seen from the figure, the defocusing of the edge portion reduced the uneven wear of the backup roll, and solved the problem with the work roll.

[0011]

According to the present invention, in the roll processing method using laser dull, the work roll edge is defocused and the processing width is narrower than the initial processing at the time of re-lasing, thereby increasing the friction coefficient of the edge. Therefore, the local wear of the backup roll can be reduced, the rate of occurrence of flaws on the work roll is reduced, and the roll basic unit is improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a trajectory of a processing head (condensing lens) with respect to a processing roll.

FIG. 2 is a diagram illustrating a cross-sectional view of a roll surface before use during initial laser processing.

FIG. 3 is a diagram showing a distribution of a coefficient of friction in a roll width direction before use during initial laser processing.

FIG. 4 is a diagram showing a profile of a backup roll when the conventional technology and the technology of the present invention are applied.

Claims (3)

[Claims] 1. A laser dull roll having a dull hole diameter and / or a hole depth smaller at a roll edge portion than at a roll center portion in a cold rolled work roll subjected to laser dulling. 2. A laser dulling method for a work roll for cold rolling, wherein the laser beam is defocused at a roll edge portion having a low contact ratio with a steel plate during initial laser processing or non-grinding re-laser processing. 2. The method for processing a laser dull roll according to claim 1, wherein the local wear of the backup roll is reduced by making the hole diameter and / or the hole depth smaller than the roll center portion. 3. The method for processing a laser dull roll according to claim 2, wherein, in the re-laser processing, a processing width is smaller than a processing width before the re-processing.