JPH0780534A - Method for cleaning steel sheet - Google Patents

Abstract

PURPOSE:To obtain a required roughness and high glossiness by spraying a hot water on the surface of a wringer roll for longer than a specific time, cleaning the rolls and then passing the steel sheet in the cleaning process of a steel sheet after a cold rolling. CONSTITUTION:This method is provided with an alkaline degreasing, electrolytic cleaning, wringer roll and hot water cleaning processes in order to remove the rolling oil of a coil that has been rolled in the electrolytic cleaning process after a cold rolling process. The wringer roll 5 is provided for removing the alkalic solution or the like stuck onto the steel sheet 10, and is pressed against the steel sheet 10 to squeeze out the solution. At this time, if an Fe powder is stuck onto the roll 5, the Fe powder is transferred onto the steel sheet 10 to cause the cloudiness of skin-pass rolling at the time of passing a bright sheet. The wringer roll 5 is cleaned in advance by a hot water spray nozzle 9 for 10 minutes or longer when passing a bright sheet, and thereby the Fe powder stuck onto the roll can be removed. Thus, the roughness and the high glossiness required for bright steel sheets are satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a steel sheet, and in particular, a roughness Ra 0.1 required for a bright steel sheet.
The present invention relates to a steel plate cleaning method for satisfying 0.2 μm and high glossiness.

[0002]

2. Description of the Related Art Normally, in the cold rolling process, the plate thickness is 3 to
A hot rolled steel sheet of about 6 mm is rolled to a sheet thickness of 0.1 to 3.2 mm. In the electric cleaning step, alkaline degreasing, electrolytic degreasing, hot water cleaning, etc. are performed to remove the rolling oil of the cold rolled coil. Here, the alkaline degreasing is to degrease a steel sheet by immersing it in an alkaline solution, and in the electrolytic degreasing, hydrogen gas or the like is generated on the surface of the steel sheet by electrolysis to remove oil adhering to the steel sheet. After that, in order to remove the alkaline solution and the like adhering to the plate, the solution is squeezed by a ringer roll, and the steel plate is immersed in warm water of about 80 ° C. in hot water washing, and then the steel plate is dried by a dryer or the like.
After that, in the annealing step, 500 ° C to 750 ° C
In order to adjust the mechanical properties in the temper rolling process and to obtain the target steel plate surface roughness, a light reduction of about 1 to 2% is performed.

[0003]

In this process, when the bright steel sheet is temper-rolled, the rolls and the steel sheet often have fog, which may not satisfy the required surface roughness. FIG. 5: is a figure which shows the fog generation state to the conventional roll and a steel plate. As shown in FIG. 5, the temper rolling roll 8
Also, the surface of the steel sheet 10 is fogged 11. When clouding occurs on the roll and the steel plate, a very small amount of foreign matter 12 such as Fe adheres to the surface of the steel plate before rolling,
This is the cause of cloudiness. However, conventionally, it is difficult to completely remove the foreign matter such as Fe, and thus the roughness distribution of the conventional bright steel sheet has an average roughness Ra of about 1.48 at n-100, and therefore the average roughness Ra is about 1.48. The actual situation is that 20% exceeds the standard upper limit value.

[0004]

SUMMARY OF THE INVENTION The present invention advantageously solves the problems of the prior art in which a bright steel sheet is cold-rolled and then subjected to an electric cleaning process including alkali degreasing, electrolytic cleaning, and hot water cleaning. Further, in the method for producing a bright steel sheet which is temper-rolled after annealing, the surface of the ringer roll installed after the electrolytic cleaning is spray-washed with warm water for 10 minutes or more.

The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of the whole process according to the present invention. In the cold rolling process 1, a thin steel plate having a plate thickness of 5 to 6 mm has a plate thickness of 0.1 to
Roll to about 3.2 mm. Next, in the electrolytic cleaning step 2, in order to remove the rolling oil of the coil rolled in the cold rolling step 1, alkaline degreasing 3, electrolytic cleaning 4, ringer rolls 5 and hot water cleaning 6 are provided. Alkaline degreasing 3
Is to degrease a steel sheet by immersing it in an alkaline solution, and in electrolytic cleaning 4, hydrogen gas or the like is generated on the surface of the steel sheet by electrolysis to remove oil adhering to the steel sheet. Further, the ringer roll 5 removes the alkaline solution and the like adhering to the steel sheet, and finally, the steel sheet is washed with warm water by immersing it in warm water.

FIG. 2 is a perspective view showing a method for cleaning a ringer roll according to the present invention. FIG. 3 is a diagram showing the transition of the Fe content on the surface of the Ringer roll according to the present invention. The cleaning time is the time for cleaning the surface of the Ringer roll with warm water. Fe
The amount is the amount of Fe deposited on the surface of the Ringer roll per unit area. The condition for washing the surface of the ringer roll with warm water is that the water temperature is 80 ° C and the water pressure is 1.0 kg / cm.
^{2. The} amount of water is 15 l / min x 4 per nozzle.
Further, the Fe amount is obtained by sticking a tape on the surface of the Ringer roll and measuring the Fe amount attached to the tape. Usually, the Ringer roll is for removing the alkaline solution and the like adhering to the steel plate, and the roll is pressed against the steel plate to squeeze the solution, but if Fe powder is attached to the roll at this time, Fe powder is transferred to the steel plate. This causes fogging of the steel sheet during temper rolling during the passage of the bright steel sheet.

Therefore, at the time of passing the bright material, it is necessary to remove the Fe powder adhering to the roll by cleaning the ringer roll 5 by jetting it from the hot water spray nozzle 9 in advance as shown in FIG. If the washing time of the Ringer roll is 1 to 10 minutes, F on the roll surface
e amount has remained at a high value as about 40-50 mg / m ^2, it decreases below 10 mg / m ² in 10 to 20 minutes. When the cleaning is continued for further 20 minutes or more, the Fe amount on the roll surface becomes almost zero.

In the present invention, the cleaning time is set to 10 minutes or more, and the maximum amount of Fe adhering to the roll surface is 14.2 mg / m ² . Desirably, the cleaning time is set to 20 minutes or more to reduce the amount of Fe attached to the roll surface to zero. Then, in the annealing step 7 shown in FIG. 1, heat treatment is performed at 500 ° C. to 750 ° C.
Next, 1-2% to adjust mechanical properties in temper rolling process 8.
Perform light reduction with. When the bright steel sheet is manufactured by the method of the present invention, the roughness Ra0.1 required for the bright steel sheet is small because the Fe content on the ringer roll surface is small or does not exist.
.About.0.2 .mu.m and high gloss can be satisfied.

According to the present invention, it is possible to satisfy the roughness Ra of 0.1 to 0.2 μm required for the bright steel sheet. FIG. 4A shows the roughness distribution of the conventional bright steel sheet. n =
At 100, the average roughness Ra is about 1.48,
Therefore, about 20% of the whole exceeds the standard upper limit value, while FIG. 4 (B) shows the roughness distribution of the bright steel sheet according to the present invention. This is the case where the roll was washed for 10 minutes or more by the above-mentioned method, and the average roughness Ra was n = 100.
Is 1.28 and σ = 0.18, so the standard upper limit value does not exceed 0.2 μm. If the roll is washed for more than 20 minutes by the above method, the standard upper limit value is of course 0.2.
The result does not exceed μm.

[0010]

As described above, the roughness Ra of 0.1 to 0.2 μm required for the bright steel sheet according to the present invention.
In addition, it is possible to obtain a steel sheet that satisfies the high glossiness, and it has an extremely excellent industrial effect.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an entire process according to the present invention,

FIG. 2 is a perspective view showing a method for cleaning a ringer roll according to the present invention,

FIG. 3 is a diagram showing a transition of Fe content on the surface of a Ringer roll according to the present invention;

FIG. 4 is a diagram showing a roughness distribution of a bright steel sheet according to the related art and the present invention,

FIG. 5 is a diagram showing a conventional state in which fogging occurs on rolls and steel plates.

[Explanation of symbols]

 1 Cold Rolling Process 2 Electrolytic Cleaning Process 3 Alkaline Degreasing 4 Electrolytic Cleaning 5 Ringer Roll 6 Hot Water Cleaning 7 Annealing Process 8 Temper Rolling Roll 9 Hot Water Spray Nozzle 10 Steel Plate 11 Cloudy

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Minor Hanada, Kimitsu 1 Kimitsu, Chiba Prefecture, Nippon Steel Co., Ltd. Kimitsu Works, Ltd. (72) Inventor, Yoichi Nagano 1 Kimitsu, Chiba Prefecture, Nippon Steel Co., Ltd. Company Kimitsu Works (72) Inventor Hiroshi Fujimine 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Co., Ltd. Kimitsu Works Co., Ltd. (72) Inventor Hiroshi Iwahana 1 Kimitsu City, Chiba Prefecture Nippon Steel Co., Ltd. Inside the Kimitsu Works (72) Inventor Yoshiaki Tanno 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Co., Ltd. Inside the Kimitsu Works (72) Katsuhei Sakamoto, Kimitsu City, Chiba Prefecture Kimitsu, Nippon Steel Co., Ltd. In-house (72) Inventor Akito Nishimuta 1 Kimitsu, Kimitsu-shi, Chiba Shin-Nippon Steel Corporation Kimitsu In-house (72) Inventor, Miyoshi Kimitsu-shi, Chiba In the address 1 Nippon Steel Co., Ltd. Kimitsu Works (72) inventor, Kimitsu City, Chiba Prefecture, Kiyoshi Izuru Hino Kimitsu address 1 Nippon Steel stock company in Kimitsu

Claims (1)

[Claims] 1. A method for cleaning a steel sheet, comprising cold-rolling, washing, annealing and temper rolling the steel sheet. In the steel sheet washing step, hot water is sprayed onto the ringer roll surface for 10 minutes or more to wash the roll, and then the steel sheet is washed. A method for cleaning steel plates, characterized by passing through steel plates.