JPS63256207A - Roll for rolling - Google Patents

Abstract

PURPOSE:To obtain a roll having various patterns and to obtain painted products having different tones by giving the surface of a rolling roll repeated patterns of plural laser beam processed traces as a unit pattern and lapping over each other. CONSTITUTION:A rolling roll is continuously rotated; fine processed traces are sequentially formed on the surface of the roll by a YAG laser beam machine installed over the roll. In that time, the machine is moved by a prescribed distance in the roll longitudinal direction per rotation of the roll. The distance is a pitch in the longitudinal direction of work-traces. A pitch in the peripheral direction is determined by a laser pulse cycle and a roll rotating speed. A unit pattern length 2 is one of important factors specifying patterns as well as work- trace heights 5 and distances 3. Unit patterns 1 having various figures and sizes are formed by changing an output and a focusing condition. Further, multiple and various patterns are given to the roll surface by changing the distance 3 between unit patterns.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rolling roll that is suitably used for manufacturing cold rolled steel sheets having excellent coating clarity and workability.

[Conventional technology]

Automotive coatings are required to be corrosion resistant and durable, and passenger cars in particular are required to have a high level of aesthetic appearance. In contrast, recently there has been a need to simplify the painting process for purposes such as improving productivity and reducing costs.

There is also a growing movement to simplify the painting process.

However, when painting becomes simpler and the thickness of the coating becomes thinner.

Since the roughness of the surface of the material sensitively affects the finished appearance, there is a strong demand for a material that can provide an appearance with excellent definition (hereinafter referred to as paint sharpness) especially after painting.

In general, in order to obtain a steel plate with excellent paint clarity, it is considered advantageous to use a steel plate with a surface in which fine roughness continues closely (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.

[Problem that the invention seeks to solve]

Conventionally, shot blasting methods have been used to impart this dullness to rolls, but the reproducibility of the form and dimensions of the dullness imparted to the AI board is poor, and depending on the conditions of the coating film, it may not always be possible. It has been difficult to stably produce steel plates with sufficient paint clarity. As one means to solve this problem,
There is a method as shown in No. 3.

That is, by using a design composed of at least one similar or different motif or a collection of motifs, which are reproduced on the surface of the rolling roll at predetermined intervals without interruption, and by keeping the dimensions of these motifs at predetermined values. This method consists of irradiating the entire roll surface with intermittent energy radiation to locally destroy the roll surface as a means of forming each motif, and the energy radiation has an output of 100 watts or more. This method uses laser radiation or electron beams with

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, giving a good coating appearance. Therefore, depending on the coating film conditions, the appearance tends to be monotonous, and there is a drawback that it is difficult to respond to the recent diversification of consumer tastes.

[Means for solving problems]

The present invention solves one or more problems of the prior art,
In order to give the steel plate a homogeneous yet diverse appearance, it was created as a result of various studies on the conditions that should be adopted for the regular pattern on the rolling rolls. A rolling roll with a unit pattern of multiple laser processing marks and a repeating pattern on its surface. Specifically, for example, the maximum length of the unit pattern is 260 μm or more and 400 μm or less.

[Action of the invention]

Figures 1a and 1b show double and triple patterns (hereinafter referred to as unit patterns) consisting of two and three machining marks obtained by partially overlapping laser pulses with the same output and focus. . As shown by the arrow 2, the maximum length is taken as the unit pattern length, and the length 2 is one of the important factors for specifying the pattern, along with the height and interval of the processed marks. FIG. 1c shows a unit pattern obtained by superimposing machining traces of different diameters using pulses of different outputs.

In the present invention, by changing the output and focus conditions,
Unit patterns 1 having various shapes and dimensions can be formed, and by adjusting the interval 3 between the unit patterns, it is possible to impart a multiplicity of processed vinegar patterns to the roll surface.

If the length 2 of each unit pattern l becomes too small, it will become different from that of a conventional monotonous pattern consisting of single processing traces.
In steel sheets obtained by rolling using rolls with these patterns, it is difficult to distinguish the color tone of the coating, so it is desirable that the maximum length is 260 μm or more; The thickness is preferably 400 μm or less because unevenness tends to occur. The best range is 2
It is 60 μm to 350 μm.

Regarding the diameter of each machining mark, the peak output range I is usually
Approximately 140-250 μm obtained in the range of Kw ~ 5 Kw
.

The dust rise height 5 from the unprocessed wire in the cross section is also about 2 to 20 μm.
, and these may be overlapped with each other to form a unit pattern with a maximum length of preferably at least 260 μm. The degree of overlap 4 is an important element for obtaining the complex color tone of the present invention, and is preferably at least 10% or more of the diameter of each processed trace, and if it exceeds about 80%, it approaches a simple circular pattern. The undesirable interval 3 between individual unit patterns is about 200 μm or less. When the surface of the roll of the present invention is worn during rolling and the difference in unevenness decreases, the pattern on the steel plate to which this is transferred becomes flat, and there is a strong tendency that complex color tones cannot be obtained. It is preferable to coat the uneven surface of the roll with a hard metal such as Ni or Cr to a thickness of 5 μm to 15 μm. Furthermore, in order to further harden the part of the dust that has been melted by the laser energy, for example, quenching heat treatment of the surface layer, ion blasting, ion beam mixing, etc. may be added after processing.

When the patterned roll of the present invention is used as a work roll of a skin-pass rolling mill, it is possible to transfer the clearest pattern onto a steel plate.

As for work rolls, the roll of the present invention is generally used as either the upper or lower roll to perform dry or wet skin pass rolling (reduction ratio of about 0.5 to 0.2%).

If necessary, the rolls of the present invention can be used for both the upper and lower rolls.

〔Example〕

The rolling roll is continuously rotated, and a YAG laser device installed on the top of the roll creates fine machining marks one after another on the roll surface. At this time, the laser device has a roll of 1
When it rotates, it moves by a certain width in the longitudinal direction of the roll.

This width becomes the pitch in the longitudinal direction of the machining trace.

Further, the pitch in the circumferential direction of the roll is determined by the laser pulse period and the roll rotation speed. In this application, one or more YAG laser devices are used.

A laser beam was irradiated so that the individual machining marks had a predetermined overlap with each other, and this unit pattern was regularly imparted to the roll surface. The roll size and laser processing conditions are shown in Table 1 below.

Table 1 Laser Processing Conditions This roll was assembled into a work roll for skin pass rolling, and wet skin pass rolling was performed at a rolling reduction of 1.0%.

On the other hand, as a comparison material, skin pass rolling was carried out under the same conditions using a dull roll formed by shot blasting and a roll onto which a simple regular pattern consisting of approximately circular processing marks was formed by laser irradiation.

The obtained steel plate was coated with a thin coating of two coats and two bakes under the conditions shown in Table 2. The image clarity of each steel plate was then visually compared.

Table 2 Painting conditions In order to check the degree of variation due to conditions between individuals in the visual test, multiple preliminary tests were conducted on specific people at different times, but each person's evaluation of sharpness was It was confirmed that the reproducibility was quite high. In other words, 5 is the most favorable, 4 is favorable, 3 is fair, 2 is somewhat favorable, and 1 is unfavorable.
When five or more samples were given a five-point rating at the same time, there was almost no difference in the two-rank ratings when evaluating the same sample at different times.

The results of the sharpness evaluation are shown in Table 3. As a result of the sharpness evaluation, the roll of the present invention and the roll made by the conventional laser dull had a significantly higher coating sharpness evaluation than the roll made by shot blasting. There is clearly a difference in rank.

On the other hand, the steel plate obtained using the roll of the present invention has a slightly higher average rating than the conventional laser dull processed material, but the steel plate obtained using the roll of the present invention has a fluctuation in the evaluation. This is due to the difference in individual evaluation of sharpness,
Alternatively, this may be due to large differences in taste. In addition, it was found that the laser dull processed materials showed better evaluations than the conventional shot materials in terms of properties such as press workability and paint adhesion, both in the conventional example and the inventive example.

〔Effect of the invention〕

The present invention provides rolls with various patterns and makes it possible to obtain coated products with different tones, compared to conventional laser dull rolls that only produce regular but somewhat monotonous patterns. It is a product that has a value suitable for an era where tastes are diversified, and has great industrial benefits.

[Brief explanation of drawings]

FIGS. 1a, 1b, and 1c are diagrams showing an enlarged plane and an enlarged cross section of a unit pattern of a roll according to the present invention. 1: Unit pattern 2: Unit pattern length 3: Interval between unit patterns 4: Overlapping portion 5: Processing mark height Patent applicant Nippon Steel Corporation representative Patent attorney Nobuaki Sugi ' No. t81 Kabo 1b figure System 1c diagram 8ze-~8 8yuφ

Claims (2)

[Claims] (1) A rolling roll with a unit pattern consisting of a plurality of laser processing marks with mutually overlapping parts, and a repeating pattern of this pattern on the surface. (2) Maximum length of unit pattern is 260 μm or more and 400 μm
A rolling roll according to claim (1) below.