JPH0833916A - Method for cleaning cold rolled plate - Google Patents

Abstract

PURPOSE:To dispense with an electrolytic cleaning device, brushes and earth rolls by immersing a cold rolled plate in an alkali solution and then supplying cleaning water with a specific pressure to the surface of the plate. CONSTITUTION:A cold rolled plate 2 is passed through while immersing it in a hot dip tank 1 charged with an alkali solution. A high pressure water with 10kgf/cm<2> or more is supplied to the surface of the cold rolled plate 2 in a high pressure water cleaning tank 3. The moisture remaining on the surface of the cold rolled plate 2 is squeezed by a wringer roll 4 and, after the surface is dried by a dryer 5, the cleaned cold rolled plate 2 is sent to the next process through a blind roll 6. A rolling residue is stripped from the surface of the cold rolled plate 2 by the immersion in the alkali solution; and a full cleaning is attained as a result of supplying water with a pressure high enough to remove the stripped rolling residue. Thus, the maintenance cost is reduced.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a cold-rolled sheet that has been cold-rolled (hereinafter simply referred to as "cold-rolled sheet"),
The present invention relates to a method for cleaning a cold-rolled sheet, which removes rolling residues such as rolling oil, iron powder, and reaction products such as iron soap.

[0002]

2. Description of the Related Art In a cold rolling / annealing process, prior to annealing, a cold rolled sheet is cleaned in order to remove rolling residue attached to the cold rolled sheet after rolling. Cleaning of this cold-rolled sheet is generally performed by a step of brushing and electrolyzing using an alkaline bath.

Further, in Japanese Patent Laid-Open No. 1-319693, a cleaning device provided at the inlet side of a continuous annealing facility has a pressure of 8-12.
It is disclosed that the alkaline electrolytic cleaning is performed after the metal plate is roughly cleaned by a pressurized hot water spray of kgf / cm ² .

[0004]

In the conventional cleaning process,
Although two tanks, a rough cleaning tank and an electrolytic tank, are required as the alkaline bath, this configuration has a disadvantage that the alkaline solution must be drained at the time of maintenance / inspection of the tank, which increases the maintenance load. Further, although a brush scrubber is attached to each cleaning tank, there is a problem in that the brush scrubber causes breakage particularly at a welded joint or a plate defect.

Further, in the technique disclosed in the above publication,
As in the general cleaning process, electrolytic cleaning is indispensable, so the cold-rolled sheet is forced to contact the earth roll, which is mainly made of graphite material, due to electrification. There was a remaining problem.

Therefore, an object of the present invention is to propose a novel method for cleaning a cold-rolled sheet that solves the above problems.

[0007]

Means for Solving the Problems In removing the rolling residue adhering to the surface of a cold-rolled sheet that has undergone cold rolling, the present invention immerses the cold-rolled sheet in an alkaline solution and then cools it. A method for cleaning a cold rolled plate is characterized in that cleaning water having a pressure of 10 kgf / cm ² or more is supplied to the surface of the cold rolled plate.

Here, the pressure of the cleaning water is the injection pressure of the spray nozzle. FIG. 5 shows the degree of cleaning of the steel plate surface when the nozzle pressure was fixed at 10 kgf / mm ² and the distance between the steel plate and the nozzle (spray distance) was changed. From this, it can be seen that if this distance is in the range of 10 to 300 mm, a sufficient degree of cleaning can be obtained. In consideration of the shape of the steel plate and the flapping, it is preferable that this distance be in the range of 100 to 300 mm.

FIG. 1 shows a cold-rolled sheet cleaning facility used in the method of the present invention. This cleaning facility is provided on the outlet side of the cold rolling mill or the inlet side of the continuous annealing treatment facility in the cold rolling process, and is used for cleaning the cold rolled sheet. In the figure, reference numeral 1 is a hot dip tank in which an alkaline solution having a adjusted concentration is charged, and a cold-rolled sheet 2 discharged from a cold rolling mill is immersed in this tank 1 for preferably 1 second or more. While passing through, the high pressure water cleaning tank 3 supplies high pressure water having a pressure of 10 kgf / cm ² or more to the surface of the cold rolled plate 2. Here, the washing of the cold-rolled sheet is completed, and thereafter, the water remaining on the surface of the cold-rolled sheet is squeezed by the Ringer roll 4 and then dried by the dryer 5, and then sent to the next step through the bridle roll 6. .

The cleaning water in the high-pressure water cleaning tank 3 is
For example, when the water is not purified water such as circulating water in a factory, it is preferable to add a step using the rinse tank 7 to clean the cold rolled sheet surface.

Here, the high-pressure water washing tank 3 is provided with four pairs of spray nozzles 8 which are paired up and down with the passage line of the cold-rolled sheet 2 introduced into this tank interposed therebetween, preferably, Cleaning the cold-rolled plate 2 surface with a pressure of 10 kgf / cm ² or more by setting the gap between the cold-rolled plate 2 and the cold-rolled plate 2 at 10 to 300 mm and with an inclination of 60 to 80 ° with respect to the surface of the cold-rolled plate 2. It supplies water. Also, water flow rate to the plate surface of the high-pressure water at this time, 1.5 l / m ² or more suffices, but 20 since l / m ² or more to increase even effect is saturated, the 1.5 ~20l / m ² It is desirable to supply in a range. The spray nozzle 8
It is sufficient to provide about 2 to 6 pairs.

[0012]

The inventors of the present invention conducted an experiment in which high pressure water was sprayed after immersing a cold rolled sheet in an alkaline solution for 4 seconds,
The relationship between the pressure of cleaning water and the cleaning degree shown in FIG. 2 was obtained. Here, the pressure of the cleaning water is the injection pressure of the nozzle, which was measured in the range of 1 to 100 kg / mm ² in the experiment, and the allowable cleaning degree, which is the criterion of the cleaning degree, is an index of the stain of the plate. It is equivalent to the product passing level of whiteness used as.

As shown in FIG. 2, the pressure of the washing water is 10 kgf /
Satisfaction with cleanliness is obtained at cm ^{2 and} above, and further 30
It has been found that a high degree of cleaning can be stably obtained at kgf / cm ² or more. This is a result of dipping the rolling residue from the surface of the cold-rolled sheet by immersion in an alkaline solution and then supplying high-pressure water necessary to remove the stripped rolling residue. That is, it has been found here that by spraying high-pressure water after the immersion treatment in an alkaline solution, necessary and sufficient cleaning can be achieved, and the electrolytic treatment, which was conventionally indispensable, can be omitted.

Next, FIG. 3 shows the results of investigating the relationship between the immersion time in the alkaline solution and the cleaning degree with the pressure of the cleaning water being kgf / cm ² . From the figure, it was found that if the immersion time was as long as 1 second, the desired degree of cleaning could be obtained, so that it is not necessary to limit the immersion time in the alkaline solution under the normal plate passing speed. . However, the immersion time is 10
If it exceeds 10 seconds, there will be almost no difference in the degree of cleaning, while if the immersion time exceeds 10 seconds, considering that various costs related to the alkaline solution will increase, the immersion time in the alkaline solution should be 10 seconds or less. Is recommended.

As a result of the actualization according to the present invention based on the above findings, the cold-rolled plate cleaning equipment was composed only of an alkaline solution tank and a high-pressure water cleaning tank having a pressure of 10 kgf / cm ² or more. . Therefore, since the electrolytic cleaning tank and the earth roll are not required, pattern reduction and stain generation on the cold rolled sheet due to these are naturally avoided, and at the same time brushing is not required, and thus the sheet breakage can be prevented, and as a result,
Non-contact cleaning was realized. Further, when using purified water as the cleaning water, the rinse tank is not necessary, and the cleaning cost and maintenance load can be reduced by incorporating the above.

[0016]

EXAMPLE Using the equipment shown in FIG. 1, four pairs of spray nozzles were installed in the high-pressure water washing tank 3, the pressure of washing water from each nozzle was 30 kgf / cm ² , the water density was 2 l / m ² , The cold-rolled sheet was washed under the conditions of a sheet passing speed of 30 to 100 m / min.
The alkaline solution used was a degreasing detergent (concentration: 3) whose main component was Na0H.

For comparison, the conventional method shown in FIG.
As shown in FIG. 5, a cleaning equipment including an electrolytic cleaning tank 9, a brush scrubber 10 and an earth roll 11 is used in place of the high pressure water cleaning tank 3, and a current density: 4 to 20 A / dm.
^2. Washing was performed under the same plate passing speed under the electrolytic conditions of alkali concentration: 1.5 to 5.0%.

The cleanliness of the cold-rolled sheet that had been subjected to each cleaning treatment was evaluated. The cold-rolled sheet washed according to the present invention gave a sufficiently good evaluation, and because there is no electrolytic cleaning tank, it is an earth roll. There was no worry of stains due to the above, and the plate did not break because it was a non-contact type. On the other hand, with the cold-rolled sheet washed according to the conventional method, even if the degree of washing that satisfied the acceptance standard of the product was obtained at first, the soiling gradually occurred due to the earth roll when the operation was continued. For example, the whiteness, which is an index of cleanliness,
It was found to reduce by 5-10% before and after the earth roll. Further, in the conventional method, the plate was broken at the welding point or the plate defect portion by the brush scrubber at a rate of about half that of the entrance side plate.

Here, the degree of cleaning is evaluated by sticking a mending tape on the cold-rolled sheet, peeling it off, dividing the tape, and stacking three tapes, and measuring the whiteness with a color difference meter. Went by.

Also in terms of cost, from FIG. 1, considering the actual equipment not including the rinse tank, the electrolytic cleaning tank,
Economical effects such as omission of brushes, rinse tanks and earth rolls, reduction of alkaline and electric power consumption, reduction of dumpout, reduction of maintenance cost, extension of repair pitch, improvement of equipment utilization rate can be expected.

In FIG. 1, the structure in which the hot dip tank in the conventional cleaning equipment is combined with the high-pressure water cleaning tank has been described, but the equipment used in the present invention is not limited to this, and includes a hot dip tank. When all the conventional devices are omitted, or when only the brush or only the electrolytic cleaning tank is omitted from the conventional device, they may be replaced with high-pressure water cleaning tanks.

[0022]

INDUSTRIAL APPLICABILITY The present invention can eliminate the electrolytic cleaning device, the brush, the earth roll, and the rinse tank, which have been indispensable in the past, in cleaning the cold-rolled sheet after cold rolling. Problems such as rupture of plate welds and dumping out of electrolytic cleaning tank are eliminated, and maintenance costs are reduced and maintenance pitches are extended by reducing work such as brush replacement and roll replacement, and the economic efficiency of equipment utilization is improved. Effect can be expected. Further, since non-contact cleaning can be realized, quality defects such as stains on the plate surface can be reduced and yield can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cleaning facility used in the method of the present invention.

FIG. 2 is a graph showing the relationship between the pressure of washing water and the degree of washing.

FIG. 3 is a graph showing a relationship between immersion time in an alkaline solution and cleaning degree.

FIG. 4 is a schematic view showing a conventional cleaning facility.

FIG. 5 is a graph showing the relationship between spray distance and cleaning degree.

[Explanation of symbols]

 1 Hot Dip Tank 2 Cold Rolled Plate 3 High Pressure Water Cleaning Tank 4 Ringer Roll 5 Dryer 6 Bridle Roll 7 Rinse Tank 8 Spray Nozzle 9 Electrolytic Cleaning Tank 10 Brush Scrubber 11 Earth Roll

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kazuo Akaoka, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Steel Works (72) Kazuya Miyagawa, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Steel Works (72) Inventor Toshiki Isobe 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Co., Ltd. Chiba Steel Works

Claims (1)

[Claims] 1. In removing the rolling residue adhered to the surface of the cold-rolled sheet that has been cold-rolled, the cold-rolled sheet is immersed in an alkaline solution, and then the surface of the cold-rolled sheet is
A method for cleaning a cold-rolled plate, which comprises supplying cleaning water having a pressure of 10 kgf / cm ² or more.