JPH03188973A - Method for preventing occurrence of linear flaw in coated steel strip - Google Patents

Abstract

PURPOSE:To prevent the occurrence of linear flaws in a coated steel strip and to improve the quality of a product by repeatedly oscillating a steel strip or a coating roll in the transverse directions of the strip when the surface of the strip is coated. CONSTITUTION:A coating roll 2 is composed of a applicator roll 3 and a pickup roll 4. A steel strip 1 is held between the roll 3 and a backup roll 5 and conveyed by rotating the backup roll 5. The pickup roll 4 is rotated in a vessel 8 contg. a coating soln., the coating soln. sticking to the roll 4 is transferred to the applicator roll 3 and the strip 1 is coated with the coating soln. When the surface of the strip 1 is coated, the strip 1 or the coating roll 2 is repeatedly oscillated in the transverse directions of the strip 1. The width of flaws in the applicator roll 3 due to the edges of the strip 1 is increased, the transfer of linear flaws in the applicator roll 3 to the coated strip 1 is prevented and the quality of a product is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for preventing linear scratches on painted steel strips.

[Conventional technology]

When coating a steel strip using a coater roll, the coating is performed while the steel strip is in contact with the coater roll, and the steel strip is brought into contact with the coater roll while the steel strip is held between a backup roll and a coater roll. are doing.

That is, as shown in FIG. 2(b), the coater roll 2 is connected to the applicator roll 3. pickup roll 4
etc., but the steel strip l is the applicator roll 3
and a backup roll 5, and are driven and conveyed by the backup roll 5. Therefore, the pickup roll 4 in contact with the applicator roll 3 rotates in the coating liquid tank 8, picks up the coating liquid, transfers this coating liquid to the applicator roll 3, and transfers the coating liquid to the applicator roll 3.
The steel strip l is applied through.

[Problem to be Solved by the Invention 1] Coating of a steel strip using a conventional coater roll is carried out as described above, but in this case, as shown in FIG. During sheet threading, linear flaws 7 are generated in the applicator roll 3 at the steel strip edge portion 6 due to wear or flaws. Since the flaws 7 occur on the applicator roll 3, the steel strips to be coated are sequentially narrowed in width from a wide steel strip to a narrow steel strip.

Therefore, if the steel strip to be coated returns to a wider width due to a color change, etc., if the operation is continued, the linear flaws 7 on the applicator roll 3 will be transferred to the steel strip l, reducing the commercial value. It deteriorates significantly and cannot be used as a product.

Therefore, with this coating method, when repainting a wider steel strip, it is necessary to always replace the applicator roll, which causes problems such as a decrease in the operation rate of the coating equipment required for roll replacement and an increase in roll cost. A problem arises. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preventing linear flaws on coated steel strips, which solves these problems and extends the life of the applicator roll and improves the operation rate of the coating line.

[Means for Solving the Problems] The present invention solves the above-mentioned problems, and employs the following method. That is, this is a method for preventing linear flaws on a coated steel strip, which is characterized by repeatedly swinging the steel strip and/or a coater roll in the width direction of the steel strip when painting the surface of the steel strip.

[Effect 1] According to the present invention, as shown in FIGS. 1(a) and (b),
By repeatedly rocking the steel strip 1 and/or the coater roll 2, wear and scratches on the applicator roll 3 caused by the threaded steel strip edge 6 are diffused, and the applicator roll 3 is
This prevents linear flaws from being transferred as paint flaws on the steel strip.

Therefore, even when changing the width back to a wider steel strip, there is no need to replace the applicator roll, the life of the abfukater roll 3 can be extended, and the operation rate of the coating line can be improved. .

[Example] In the present invention, the amount by which the steel strip and/or coater roll is repeatedly oscillated in the width direction of the steel strip is preferably 5 to 100 mm. If it is less than 5 mm, the abrasion of the steel strip edge to the applicator and the diffusion of the scratches will not be sufficient and the possibility of transfer of linear scratches will increase. In addition, if it is 100mm or more,
Although it is more effective in preventing the transfer of linear flaws, the roll width is usually the maximum sheet width + about 200 mm, which is not preferable because there is a risk that the steel strip will roll out.

The oscillating pitch is 5 to 30, depending on the oscillating width and the steel strip edge deflection (preferably 3/100 mm or less).
Minutes are good. A long vibration pitch is undesirable because the edge of the steel strip passes through substantially the same position on the coater roll for a long time, increasing the probability that the edge of the steel strip will damage the coater roll.

Next, there is a method of swinging the steel strip and/or coater roll, but generally in a loading line, the steel strip is rolled on the steering roll, input side, exit side winding, return, and take-up reel. □A centering mechanism is provided so that the strip passes through the central part in the width direction, and a bias signal is applied to this steering roll and centering mechanism to swing the steel strip in the width direction. A swinging mechanism may be provided in the coater roll to swing the coater roll.

Next, the results of implementing the present invention will be explained □.

■ Processed "300" with a swing width of 5 mm and a swing pitch of 4-1 minutes. Although the machine was opened and returned four times, no linear flaws due to the steel strip edges were generated. In this case, the conventional example If so, the applicator roll had to be replaced four times.

■ 300 tons were processed with a swing width of 100 mm and a swing pitch of 30 minutes.

During this time, width return was performed three times. Results are implementation □・Example □■
There were no problems at all.

■ 300 samples were processed with a swing width of 10 mm and a swing pitch of 5 minutes.

I went back to this opening four times. Although a slight linear flaw occurred due to the edge of the copper band due to the width return, the product value was within acceptable limits.

[Effects of the Invention] The method for preventing linear flaws on coated steel strips of the present invention has the following excellent effects.

■It is possible to extend the life of the applicator roll.

■It is possible to improve product quality by reducing paint defects transferred to products.

■Since the number of roll changes is significantly reduced, line operating efficiency is greatly improved.

■Product costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the operation of the present invention, FIG. 1(a) is a plan view of the applicator roll, FIG. 1(b) is a perspective explanatory diagram of the coating situation, and FIG. 2 is an explanatory diagram of the conventional example. FIG. 2(a) is a plan view of the applicator roll, and FIG. 2(b) is a perspective explanatory view of the coating state. 1... Steel strip 2... Coater roll 3.
... Applicator roll 4 ... Pickup roll 5 ... Backup roll 6 ... Edge part 7 ... Linear flaw

Claims (1)

[Claims] 1. A method for preventing linear scratches on a coated steel strip, which comprises repeatedly swinging the steel strip and/or a coater roll in the width direction of the steel strip when painting the surface of the steel strip.