JPH0341270B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for surface processing a rolling roll, which is suitably used for cold-rolled steel sheets with excellent paint clarity. [Conventional technology] Automobile coatings are required to be corrosion resistant and durable, and passenger cars in particular are required to have an even higher level of aesthetics, but in recent years there has been a movement to simplify the coating process in order to improve productivity and reduce costs. is also becoming stronger. However, as painting becomes simpler and the thickness of the paint film becomes thinner, the roughness of the material surface more sensitively affects the finished appearance. There is a strong demand for the supply of materials that can be used. In general, in order to obtain a steel plate with excellent paint clarity, it is advantageous to use a steel plate having a surface with closely continuous fine roughness (hereinafter referred to as dullness). In order to impart dullness to a steel plate, a method is adopted in which a work roll of a temper rolling mill or the like is provided with dullness in consideration of the transfer rate, and the dullness is transferred by temper rolling or the like. Traditionally, in order to add this dal to a roll,
Shot blasting, electrical discharge machining, etc. have been used, but the reproducibility of the shape and dimensions of the unevenness imparted to the steel plate is poor, and depending on the coating conditions, it is not always possible to apply sufficient coating. It has been difficult to stably produce steel plates with good image clarity. As one means to solve this problem,
There is a method as shown in Japanese Patent Application Laid-open No. 54-61043. That is, by using a design made up of at least one similar or different motif or a collection of motifs, which are copied without interruption at predetermined intervals on the surface of the rolling roll, and by adjusting the dimensions of these motifs to a predetermined value. This method consists of irradiating the entire roll surface with intermittent energy radiation to destroy the roll surface as a means of forming each motif, and as energy radiation,
Laser radiation with a power of more than 100 watts,
Alternatively, there is a method using an electron beam. [Problems to be solved by the invention] With this method, a highly regular repeating pattern is obtained on the roll surface, and the regular pattern is also transferred to the steel plate rolled using this roll, resulting in a good painted appearance. On the other hand, due to strong regularity, it tends to have a monotonous appearance depending on the coating conditions.Moreover, as the coating process is simplified and the coating thickness becomes thinner, streaky patterns become more noticeable. The drawback was that it was difficult to respond to the diversification of customer preferences. [Means for Solving the Problems] The present invention solves the problems of the prior art as described above, and in order to give a steel plate a homogeneous yet diverse appearance, regular patterns on the rolling rolls are used. This was achieved as a result of various studies on the conditions that should be adopted, and its characteristics include that by repeatedly irradiating the surface of a rolling roll with two or more types of laser light, two or more types of laser light can be applied to the surface of the roll. A method for surface processing a rolling roll, characterized in that a pattern is formed by repeatedly forming machining marks in units of machining marks with an interval of 260 μm or more. Specifically, for example, the height of the raised machining marks is 3 to 10 μm. [Operation] FIG. 1 schematically shows an example of a pattern on the surface of a roll processed according to the present invention. The upper half of Figure 1 shows a plan view, and the lower half shows a cross section of the pattern. The shaded area indicates the height of the unprocessed portion from the roll surface. Figure 1 shows one deep hole with a small diameter and high bulge, and one shallow hole with a large diameter and small bulge.
An example is shown in which a single unit pattern is formed by arranging the laser beams, but in the present invention, since two or more types of laser beams are used, any unit pattern can be easily obtained. For example, a unit pattern consisting of a plurality of holes with different diameters and the same degree of protrusion, a combination of holes with the same diameter but different protrusion heights, or as shown in Figure 1,
Repeated patterns can be obtained by various combinations, such as unit patterns made by combining different diameters and depths. In the present invention, the distance between two or more types of machining marks (indicated by A or B in Figure 1) is preferably 260 μm or more, and if it is less than this, the sharpness of the obtained steel plate will be lower than that of conventional materials. It becomes difficult to tell the difference. Here, the evaluation of image sharpness was based on a five-level visual evaluation method, as will be described later. The raised height of the machining mark (A or B in Fig. 1) is 1 to 20 μm, preferably 3 to 10 μm. If the raised height is 1 μm or less, dullness on the steel plate will be difficult to form. If it exceeds this, there is a disadvantage that this part will be subject to increased wear. still,
In order to prevent wear on the raised parts, known methods such as quench hardening by heating after processing, coating with coin metals such as Cr and Ni, ion plating, and ion beam mixing can be used. . [Example] A rolling roll is continuously rotated, and a YAG laser device installed on the top of the roll is used to sequentially create fine machining marks on the roll surface. At this time, the laser device moves in the longitudinal direction of the roll with a constant width when the roll makes one revolution. This width becomes the pitch in the longitudinal direction of the machining mark. Further, the pitch in the circumferential direction of the roll is determined by the laser pulse period and the roll rotation speed. In the present invention, a plurality of YAG laser devices are used to sequentially inscribe a unit pattern consisting of machining marks of two or more types of diameters or different heights on the roll surface. Note that the roll shape and processing conditions are
Shown in the table. This roll was assembled into a work roll of a temper rolling mill, and wet temper rolling was performed at a rolling reduction of 1.0%.

【table】

[Table] On the other hand, as a comparison material, skin pass rolling was performed under the same conditions using a dull roll formed by shot blasting and a roll provided with a regular pattern consisting of approximately circular processing marks by laser irradiation. The resulting steel plates were subjected to visual comparison of sharpness under the conditions shown in Table 2, with two coats and two bakes applied to the steel plates. In addition, in order to check the degree of variation due to individual conditions in the visual test, multiple preliminary tests were conducted on specific people at different times, and the sharpness evaluations of each person showed that the reproducibility was quite high. It was confirmed that there is a sex. Therefore, the most preferable one is 5.
When five or more samples were given a five-point rating at the same time, with 4 being favorable, 3 being average, 2 being somewhat unfavorable, and 1 being unfavorable, the evaluation of the same samples at different times resulted in a rank of 2. There were almost no differences in the evaluations.

[Table] Table 3 shows the sharpness evaluation results. As a result of the sharpness evaluation shown in Table 3, the steel plate obtained using the roll surface-treated according to the present invention (invention material) and the steel plate obtained using the conventional laser dull processing roll (laser dull processing material) were found. ), the evaluation of the coated surface was significantly higher than that of the steel plate obtained by shot blasting rolls (shot blasted material), and a significant difference was clearly recognized. On the other hand, the material of the present invention has a slightly higher rating on average than the conventional laser dull processed material, but there is a large variation in the evaluation within the material of the present invention, which is due to the individual's personal preference for image sharpness. This is also due to the large difference in evaluation or preference.

【table】

〔Effect of the invention〕

Although the present invention is regular, only a somewhat monotonous pattern can be obtained, and because the pattern is too regular, a striped pattern is observed on the surface of the steel sheet when painting a thin film. Compared to Dalroll,
Rolls with various patterns are obtained. By using this, coated products with different tones can be obtained, creating value suitable for an era of diversified tastes, and having great industrial benefits.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a laser-processed pattern on a roll according to the present invention.

Claims (1)

[Claims] 1. By repeatedly irradiating the surface of a rolling roll with two or more types of laser beams, two or more types of machining marks are formed on the surface of the roll, and the interval between the machining marks is 260 μm.
A method for surface processing a rolling roll, characterized in that a pattern is formed by repeating the above items as units. 2 The height of the machining marks is 3~
A method for surface processing a rolling roll according to claim 1, wherein the surface treatment method is 10 μm.