JP7207357B2 - Method for pickling metal plate and method for manufacturing metal plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a metal plate pickling method capable of preventing sludge from adhering to ringer rolls and preventing deterioration of pickling ability, and a metal plate manufacturing method using the pickling method.

In the manufacturing process of a metal plate, pickling is performed by immersing the metal plate in an acid solution for the purpose of removing surface scale after heat treatment. In general, pickling involves immersing a metal plate in a bath filled with an acid solution, pulling it out after a certain period of time, and performing post-treatment such as washing with water. Since the metal plate coming out of the pickling bath has the acid solution attached to it, if the metal plate is transported to the post-treatment process as it is, the acid solution will be brought into the post-treatment process. For this reason, a process of removing the acid solution from the metal plate after pickling is adopted.

Patent Literature 1 proposes a method of squeezing (squeezing out) the pickling liquid adhering to the strip steel sheet that has left the pickling tank between ringer rolls.

JP-A-63-307287

In the conventional method of pickling a metal plate, pickling is performed by a ringer roll after leaving the pickling tank, but with continued use, the sludge adhered to the metal plate adheres to the ringer roll, degrading the pickling ability. There was a problem that occurred. If acid is brought into the post-treatment bath, it is necessary to increase the post-treatment bath immersion time, causing line slowdown.

The present invention aims to provide a metal plate pickling method capable of preventing sludge from adhering to a ringer roll and preventing deterioration of pickling ability, and a metal plate manufacturing method using the pickling method. aim.

In order to solve the above problems, the present invention has found the following.

That is, the sludge sticking to the ringer roll is caused by the sludge brought from the pickling tank adhering and accumulating on the ringer roll. In particular, as shown in FIGS. 4a and 4b, it is considered that the ringer roll 2A and the liquid puddles 10 at the ends of the metal plate 1 are the cause. Therefore, by spraying a cleaning liquid on the ringer roll's peripheral surface placed between the pickling tank exit side and the post-treatment tank, the acid solution containing the sludge adhering to the roll's peripheral surface is washed away and the sludge is prevented from sticking. found to be important.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] A method for pickling a metal plate, wherein after the metal plate is immersed in an acid solution, the metal plate is squeezed with an acid solution by at least a pair of ringer rolls arranged to sandwich the carried-out metal plate. 1. A method for pickling a metal plate, comprising spraying a cleaning liquid onto the circumferential surface of said ringer roll from at least one nozzle arranged facing the longitudinal direction of said ringer roll.
[2] The method for pickling a metal plate according to [1], wherein the cleaning liquid is a post-treatment liquid.
[3] The metal plate is carried out in the horizontal direction, and the cleaning liquid is sprayed onto the peripheral surface of at least the upper roll of the ringer rolls arranged with the metal plate sandwiched between the upper and lower sides. ] or the method for pickling a metal plate according to [2].
[4] The method for pickling a metal plate according to any one of [1] to [3], wherein the cleaning liquid is sprayed from the delivery side of the ringer roll.
[5] The method for pickling a metal plate according to any one of [1] to [4], wherein the nozzle is a spray nozzle.
[6] Any one of [1] to [5], wherein the injection flow rate of the cleaning liquid at the central portion in the longitudinal direction of the ringer roll is larger than the injection flow rate of the cleaning liquid at the end portions in the longitudinal direction of the ringer roll. A method for pickling a metal plate according to claim 1.
[7] A method for producing a metal plate, characterized by using the method for pickling a metal plate according to any one of [1] to [6].

The present invention can prevent a decrease in pickling ability due to sludge sticking to the ringer roll after pickling, so it can prevent an increase in processing time due to frequent roll replacement and a decrease in the pH of the post-treatment tank. The manufacturing cost can be significantly reduced, and the industrial utility value is extremely high.

FIG. 1 is a perspective view of a nozzle and a ringer roll after pickling, illustrating one embodiment of the present invention. 2 is a side view of FIG. 1. FIG. FIG. 3 is an overall view of a pickling tank, a post-treatment tank, and a ringer roll for explaining one embodiment of the present invention. FIG. 4a is a perspective view showing a ringer roll after pickling of the prior art and a pooled portion at the edge of the metal plate, and FIG. 4b is a front view seen from the X direction of FIG. 4a.

Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to the following embodiment. Components in the following embodiments include components that can be easily replaced by those skilled in the art, or components that are substantially the same.

The method of pickling a metal plate according to the invention is shown schematically in FIG. The arrow D indicates the transport (running) direction of the metal plate 1, and assumes transport in the horizontal direction (perpendicular to gravity). An example of the metal plate 1 is a hot-rolled steel strip. The ringer rolls 2A to 2C are arranged so as to sandwich the metal plate 1 from above and below, and are rotated in the conveying direction of the metal plate 1 to remove acid. Here, the nozzles 3A to 3C are arranged facing the longitudinal direction of the ringer rolls 2A to 2C, respectively, and can spray the cleaning liquid W onto the peripheral surfaces of the ringer rolls. When the metal plate 1 is conveyed, the cleaning liquid W sprayed from the nozzles 3A to 3C, for example, removes the acid liquid adhering to the ringer rolls 2A to 2C from the liquid puddles 10 at the edges of the metal plate 1 into the pickling tank 8. It washes away with the sludge brought in from the

Water may be used as the cleaning liquid W to be sprayed onto the ringer rolls 2A to 2C, but it is preferable to use the post-treatment liquid as the cleaning liquid W when the post-treatment liquid is other than water. As the post-treatment liquid, there is, for example, an alkaline cleaning liquid. The type of the alkaline cleaning liquid is not particularly limited, and may be one commonly used for neutralizing acid solutions.

2 is a side view of FIG. 1. FIG. Of the ringer rolls 2A to 2C, the cleaning liquid W may be sprayed onto at least the upper roll, and it is more preferable to spray the cleaning liquid W onto both the upper and lower rolls. The effects of the present invention can be obtained even when the cleaning liquid W is not sprayed onto the lower roll. This is because the amount of sludge deposited on the lower roll is smaller than the amount of sludge deposited on the upper roll.

In addition, it is considered that the nozzles 3A to 3C can be arranged on either the entrance side or the exit side of the ringer rolls 2A to 2C to avoid sludge adhesion. If the post-treatment tank is a water washing tank, bringing in water adhering to the steel sheet is not a particular problem, and spraying the washing liquid W from the outlet side can reduce the concentration of the acid adhering to the steel sheet. It is preferable to install a nozzle on the exit side of the roll.

Here, the ringer roll entrance side means the entrance side of the metal plate 1 with respect to the ringer rolls 2A to 2C, and the ringer roll exit side means the exit side of the metal plate 1 from the ringer rolls 2A to 2C. In addition, "injecting the cleaning liquid W from the delivery side of the ringer rolls" means that a ringer It means that the cleaning liquid is sprayed on the peripheral surface range corresponding to the roll exit side.

In addition, in order to wash away the acid solution from the liquid puddles 10 at the edge portions of the metal plate 1, the injection flow rate of the cleaning liquid W may be the same at the longitudinal end portions and the longitudinal central portion of the ringer rolls 2A to 2C. It is further preferable to adjust the flow rate of the cleaning liquid W so that the acid liquid that has been washed out flows out of the ringer rolls 2A to 2C more by increasing the injection flow rate at the central portion in the longitudinal direction than at the end portions in the longitudinal direction. For example, a plurality of nozzle heads are installed in each of the nozzles 3A to 3C, and the injection flow rate of the nozzle head facing the longitudinal center of the ringer rolls 2A to 2C is changed to the nozzle head facing the longitudinal ends of the ringer rolls 2A to 2C. By making the injection flow rate higher than the injection flow rate of , the acid solution containing sludge can be flowed to the outside of the roll. Preferably, the number of nozzle heads is 3 or more, and the injection flow rate is 20 to 60 L/min at the central portion in the longitudinal direction of the ringer rolls 2A to 2C and 0 to 40 L/min at the end portions in the longitudinal direction.

A spray nozzle is preferred as the nozzle for the cleaning liquid, but other means can also be used. For example, shower nozzles.

In the above embodiment, the metal plate is immersed in the acid solution and then carried out in the horizontal direction. Alternatively, the metal plate may be carried out in the vertical direction. When the metal plate is carried out in the vertical direction, the cleaning liquid is applied to the peripheral surface of at least one of the ringer rolls arranged to sandwich the metal plate in the same manner as when the metal plate is carried out in the horizontal direction. You should be able to inject it.

A method for manufacturing a metal plate according to the present invention will be described based on examples. In addition, the present invention is not limited to the following examples.

Hot-rolled steel strips were pickled using a water washing tank and ringer rolls 2A to 2C and 4 to 7 as the pickling tank 8 and the post-treatment tanks 9A to 9C shown in FIG.

A hot-rolled steel strip having a thickness of 1.6 to 7.0 mm and a width of 762 to 1880 mm and manufactured by a conventional method is immersed in a pickling tank 8 for 60 seconds, pickled by ringer rolls 2A to 2C, and then subjected to a post-treatment tank. Transferred to 9A-9C. The pickling tank 8 contains about 10-15% hydrochloric acid, and the post-treatment tanks 9A to 9C are composed of three washing tanks. Each ringer roll can be sandwiched between upper and lower rolls to drain water. Ringer rolls 2A to 2C and 4 to 7 have a roll diameter of 500 mm (upper) and 350 mm (lower), and three sets of ringer rolls 2A to 2C are installed after the pickling bath. As the ringer rolls 2A to 2C after the pickling tank are used longer, the sludge brought in from the hydrochloric acid tank adheres to the ringer rolls, resulting in a decrease in pickling ability and a decrease in the pH of the post-treatment tank. Therefore, in order to prevent the sludge from sticking to the sludge adhering part 11 and to suppress the pH drop of the post-treatment tanks 9A to 9C, a spray nozzle that can spray at positions of 450 mm and 750 mm to the left and right from the center of the ringer rolls 2A to 2C respectively. 3A-3C were installed. First, in order to wash away the sludge attached to the ringer rolls 2A to 2C, the flow rate of the spray was 20 L/min and sprayed onto the peripheral surface of the upper roll of the ringer rolls. I was able to In addition, when the amount of sludge adhered to the sludge adhered portion 11 was checked before and after the change from non-use to use of the spray nozzles 3A to 3C, the amount of sludge adhered decreased from 100 g to 30 g after one month of use ( Invention example 1). In addition, by adjusting the injection flow rate at the central portion of the ringer rolls 2A to 2C to 30 L/min and the injection flow rate at the longitudinal end of the ringer rolls to 20 L/min, and spraying to the ringer rolls, further suppressing sludge adhesion. It was possible to further reduce the line deceleration time (Invention Example 2). On the other hand, the comparative example was used for one month without washing the ringer roll. Table 1 shows the implementation conditions, the amount of sludge adhered, and the evaluation. The amount of sludge adhered was measured by subtracting the amount of roll wear from the difference in roll weight before and after use. As evaluation criteria, the case where the adhesion amount was 20 g or less was evaluated as ⊚, the case where the adhesion amount exceeded 20 to 60 g was evaluated as ◯, and the case where the adhesion amount exceeded 60 g was evaluated as X.

In the comparative example, the amount of sludge adhered could not be reduced, and the evaluation was x. On the other hand, both Inventive Examples 1 and 2 were able to significantly reduce the amount of sludge adhered. In particular, in Invention Example 2 in which the injection flow rate of the cleaning liquid at the central portion of the ringer roll is higher than the injection flow rate at the longitudinal end portions of the ringer roll, the sludge deposition amount can be further reduced than in Invention Example 1 where there is no difference in the injection flow rate. rice field.

1 Metal plate (hot-rolled steel strip)
2A-2C ringer roll 3A-3C nozzle (spray nozzle)
4 to 7 Ringer roll 8 Pickling tank (3 tanks)
9A to 9C post-treatment tank (rinsing tank)
D Running direction of metal plate (conveying direction)
W washing liquid 10 liquid pool 11 sludge adhering part

Claims (6)

A method for pickling a metal plate in which, after a metal plate is immersed in an acid solution, the metal plate is squeezed with an acid solution by at least a pair of ringer rolls arranged to sandwich the carried-out metal plate, wherein the ringer A cleaning liquid is jetted onto the peripheral surface of the ringer roll from at least one nozzle arranged facing the longitudinal direction of the roll, and the injection flow rate of the cleaning liquid at the central portion in the longitudinal direction of the ringer roll is equal to the length of the ringer roll. A method for pickling a metal plate, wherein the injection flow rate of the cleaning liquid is greater than that at the end of the direction . 2. The method of pickling a metal plate according to claim 1, wherein the cleaning liquid is a post-treatment liquid used in a post-treatment tank . 3. The cleaning liquid is sprayed onto the peripheral surface of at least the upper roll of the ringer rolls arranged with the metal plate sandwiched therebetween. The method for pickling a metal plate according to 1. 4. The method for pickling a metal plate according to claim 1, wherein the cleaning liquid is sprayed from the delivery side of the ringer roll. 5. The method for pickling a metal plate according to claim 1, wherein said nozzle is a spray nozzle. A method for manufacturing a metal plate, characterized by using the method for pickling a metal plate according to any one of claims 1 to 5 .

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