JP3048704B2 - Continuous pickling method for steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adding a continuous pickling of a steel strip, and more particularly to a method for removing rust or yellow discoloration on a steel sheet surface generated at the time of a low speed passing area at the end of the continuous pickling or at the time of stopping the passing. It relates to a simple addition method.

[0002]

2. Description of the Related Art A steel strip after hot rolling is passed through a continuous pickling line to remove iron oxide adhering to the surface. However, the end portion of the steel sheet often turns yellow when the low-speed sheet passing area or at the end of the continuous sheet passing line at the end of the continuous sheet passing line, which is a problem in product quality. These yellow discolorations are a kind of rust, and the steel strip whose scale has been removed by pickling is generated by the combination of water and oxygen in the air, or it appears on the steel strip surface after pickling. The attached iron salt is generated by, for example, reacting with oxygen in the presence of sufficient water to produce ferric hydroxide.

Conventionally, the following method has been employed as a method for removing or preventing the occurrence of yellow discoloration thus generated. (B) Wash thoroughly with clean rinsing water to prevent iron salts from remaining on the steel strip surface. (B) In order to prevent the surface of the steel strip from drying and being oxidized by contact with the atmosphere during low-speed passing, the steel strip is kept moist until it is instantaneously dried by a dryer. (C) The generated yellow discoloration is continuously removed with a brush, a chemical, or the like, or is removed by spraying a pickling bath solution as shown in Japanese Utility Model Laid-Open No. 62-41072. (D) Discoloration is suppressed by spraying a rinsing liquid containing a steel sheet discoloration inhibitor as disclosed in JP-A-59-185786. And so on.

[0004]

In these prior arts, if the generated yellow discoloration is intense, it is difficult to remove it, and a measure for removing it with a brush or the like is not enough. However, there is a disadvantage that the commercial value is significantly reduced. An object of the present invention is to solve rust or yellow discoloration on the steel sheet surface generated in the final stage of continuous pickling of a steel strip by a simple method, remove rust or yellow discoloration, and remove the rust or yellow discoloration to obtain the same steel strip surface quality as a stationary part. It is an object of the present invention to provide a continuous pickling addition method which can guarantee the pickling.

The gist of the present invention is as follows. That is, in the continuous pickling addition method for removing rust or yellow discoloration on the steel strip surface generated at the time of a low-speed passing area or when the passing of the steel strip is stopped in a line for continuously pickling the steel strip , Reverse the rust or yellow discoloration
After the part is immersed again in the pickling tank, the acid solution attached to the reverse passing plate material is removed at the pickling tank entrance side, and then , the normal rotation is again performed to pickle and remove the rust or yellow discolored part. The method is a continuous pickling addition method for a steel strip.

An embodiment of the present invention will be described with reference to the accompanying drawings. In FIG. 1, the steel strip 2 after hot rolling is immersed in a pickling tank 4 of a continuous pickling line in order to remove iron oxide adhering to its surface, and proceeds from left to right in the figure. After the acid solution is squeezed out by the ringer roll 7 on the pickling tank outlet side, the clean water is sprayed by a plurality of rinsing sprays 8 and rinsed, and the adhered clean water is squeezed again by the ringer roll 11 on the rinsing outlet side. After the dryer 1
It is dried instantly in 2 and becomes a product. However, rust or yellow discoloration often occurs in the steel strip that has undergone these pickling steps, which may lower the commercial value of the product. In the present invention, the following pickling addition method is employed to remove this yellow discoloration.

[0007] As described above, when a yellow discolored portion occurs at the low speed passing area of the steel strip at the end of pickling or when the sheet is stopped, the progress of the steel strip 2 is reversed and the yellow discolored part is pickled again. Immerse in tank 4. Thus the steel strip 2 with a yellow discoloration proceeds in Figure from right to reverse traveling to the left, yellow discoloration disappears been pickled. During reverse movement, the acid solution 5 adhering to the steel strip surface is pickled.
At the entry side of the tank 4, it is squeezed by the ringer roll 6 on the entry side of the pickling tank, and is completely washed by the newly provided spray roll 14. When the removal of the yellow discolored portion due to the reverse rotation of the steel strip is completed, the steel strip is wound again in the normal direction, and a good product from which the yellow discolored portion has been removed can be obtained.

Conventionally, many methods have been adopted for the treatment of the yellow discolored portion generated at the end of the pickling of a steel strip after hot rolling in the low-speed passing area or at the time of stopping the passing of the steel strip. In view of the above, the present invention has adopted the method of reversing the steel strip and pickling the yellow discolored portion again, so that the following effects can be obtained. (A) The quality of the yellow discolored portion was equal to that of the steady portion. (B) The same quality as the stationary part can be assured by a simple pickling addition method of reversing and pickling again. However, this additional work can be performed with a slight increase in equipment such as a rinsing sprayer and dryer. The work is extremely easy and ends.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a pickling equipment for a steel strip and a pickling apparatus for explaining a pickling addition method according to the present invention.

[Explanation of symbols]

 2 Steel strip 4 Pickling tank 6 Ringer roll on pickling tank inlet 7 Ringer roll on pickling tank outlet 8 Rinse spray 10 Ringer roll 11 Ringer roll (rinse outlet side) 12 Dryer 14 New rinse spray

Claims (1)

(57) [Claims] 1. A continuous continuous pickling additional process for removing rust or yellowing on the steel strip surface which is generated when stopping the low-speed communication leaf area or passing plate in line for pickling a steel strip, the steel strip Reverse the passing direction to rust or discolor yellow
After the part is immersed again in the pickling tank, the acid solution attached to the reverse passing plate material is removed at the pickling tank entrance side, and then , the normal rotation is again performed to pickle and remove the rust or yellow discolored part. Characteristic method of continuous pickling of steel strip.