JP2938358B2 - Electrolytic pickling equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic pickling apparatus for uniformizing the current density distribution of an electrolytic current, performing electrolysis, and removing scale on the surface of a steel strip.

[0002]

2. Description of the Related Art FIG. 6 shows a schematic configuration of a conventional electrolytic pickling apparatus for removing scale on the surface of a steel strip and an example of a current density distribution of an electrolytic current. In the tank 4 filled with the neutral salt electrolyte, a pair of positive electrode plates 2a, 2b separated from each other are provided.
A center roll 5b and a pair of negative electrode plates 3a and 3b separated from each other are provided. The stainless steel strip 1 introduced into the tank 4 via the deflector roll 5a firstly
It passes between the positive electrode plates 2a and 2b, is turned upward by the center roll 5b, and is then turned to the negative electrode plates 3a and 3b.
Between the tank 4 and the deflector roll 5
c to the next step.

The positive electrode plates 2a, 2b and the negative electrode plates 3a, 3
The power supply voltage E is applied between the positive electrode plates 2a and 2b, whereby the upper and lower surfaces of the stainless steel strip 1 disposed between the positive electrode plates 2a and 2b are negatively charged, and conversely, between the negative electrode plates 3a and 3b. The upper and lower surfaces of the stainless steel strip 1 disposed in the above are positively charged. As a result, the current of the power source E is reduced to the positive electrode plates 2a, 2
b, it becomes an electrolytic current and flows to the negatively charged portion of the stainless steel strip 1, further reaches the positively charged portion through the stainless steel strip 1, and becomes an electrolytic current from the positively charged portion and flows to the negative electrode plates 3a and 3b to supply power. Return to E.

At this time, due to the influence of the resistance component of the stainless steel strip 1, the current flowing from the end of the positive electrode plates 2a and 2b on the deflector roll 5a side to the stainless steel strip 1 and reaching the negative electrode plates 3a and 3b is: The current flowing through the stainless steel strip 1 from the ends of the positive electrode plates 2a and 2b on the side of the center roll 5b to the stainless steel strip 1 and reaching the negative electrode plates 3a and 3b is smaller than the current density distribution of the electrolytic current in the electrode length direction. 6
As shown in the figure, the height increases at the end of the center roll 5b, and decreases at the ends of the deflector rolls 5a and 5c.
The sign of the current density in FIG. 6 indicates the direction in which the electrolytic current flows.

In this electrolytic pickling, the negative electrode plates 3a, 3a
The positively charged portion of the stainless steel strip 1 disposed between the b and b serves as an anode surface. At the anode surface, dissolution of metal and metal oxide and generation of oxygen and the like progress by a chemical reaction, and the scale of the surface of the stainless steel strip 1 is increased. Is chemically removed.
However, where the current density of the electrolytic current in the cathode plates 3a and 3b exceeds a predetermined value, oxygen generation takes precedence, so that the dissolution reaction of the metal is suppressed and the descaling performance tends to decrease. It has been desired to make the current density distribution of the electrolytic current uniform.

Conventionally, electrolysis is performed by making the current density distribution of the electrolytic current uniform, for example, see Japanese Utility Model Application Laid-Open No. 62-1.
There is an electrode plate for electroplating described in JP-A-36580. In this method, a steel strip is drawn into a bath filled with a plating solution, and an electrode plate is disposed at a predetermined distance above and below the steel strip. An outlet is provided, and by ejecting a plating solution from the solution discharge port, the central portion of the steel strip is floated to prevent dripping. Further, when no droop occurs, the electrode plate has a predetermined curvature on its surface in the length direction of the steel strip so that the sum of the resistance of the steel strip and the plating solution resistance between the electrode plate and the steel strip is kept constant. With
The distance from each position in the length direction of the electrode plate to the steel strip is changed. In this way, by eliminating the droop of the steel strip and by making the sum of the steel strip resistance and the liquid resistance constant at each point in the length direction of the electrode plate, the current density distribution in the length direction of the electrode plate is reduced. It is uniform.

[0007]

However, in the prior art described in the above publication, a liquid discharge hole is provided in the electrode plate, and the central portion of the steel strip is floated by jetting a plating solution from the liquid discharge hole. And, the curvature is provided on the electrode plate surface to make the sum of the resistance values constant and make the current density distribution uniform, but the flying height changes depending on the weight of the steel strip, and the liquid resistance value varies for each plating solution. Because of these changes, the dimensions of the liquid discharge holes and the curvature of the surface must be set taking these factors into account.
It is not easy to form many types of electrode plates. In particular, in the case of a large-sized electrode plate having a length of several meters, it is difficult to form the electrode plate with a curved surface.

Therefore, an object of the present invention is to provide an electrolytic pickling apparatus which can solve the above-mentioned problems and can make the current density distribution of the electrolytic current uniform with a simple structure.

[0009]

In order to achieve the above object, an electrolytic pickling apparatus according to claim 1 of the present invention comprises a pickling tank filled with an electrolytic solution through which a steel strip passes. A pair of positive electrode plates for electrolysis disposed in the pickling tank at predetermined distances from both the front and back surfaces of the steel strip and opposed to each other with the steel strip interposed therebetween; A predetermined distance from each side surface of the steel strip in the tank, respectively, and are disposed to face each other across the steel strip, and,
A pair of negative electrode plates for electrolysis disposed at a predetermined distance from the positive electrode plate toward the steel strip passing direction, and an electrolytic acid for removing scale on the surface of the steel strip by electrolysis. In the washing apparatus, at least the negative electrode plate, by a predetermined setting of the electrode area on the surface facing the steel strip, by reducing the portion of the high current density of the electrolytic current flowing between the steel strip, I do.

In the electrolytic pickling apparatus according to a second aspect of the present invention, the electrode area is set by covering at least a surface of the negative electrode plate facing the steel strip with an insulating member having a predetermined area. It is characterized by doing. In the electrolytic pickling apparatus according to a third aspect of the present invention, the insulating member is an insulating tape.

Further, the electrolytic pickling apparatus according to claim 4 of the present invention is characterized in that the electrode area is set at least by forming a through hole having a predetermined area in the negative electrode plate. .

[0012]

According to the above structure, according to the electrolytic pickling apparatus of the present invention, at least the electrode area of the surface of the negative electrode plate facing the steel strip is reduced by the electrolytic flow between the negative electrode plate and the steel strip. The setting is made so that the portion where the current density of the current is high is lowered. The current density distribution is calculated, for example, by calculation, and the electrode area is set to be small at the place where the current density is high.
Set the electrode area large where the current density cloth is low,
The level of the current density at each position in the electrode length direction between the negative electrode plates is changed by changing the electrode area to achieve a uniform current density distribution.

According to the electrolytic pickling apparatus of the present invention, at least the surface of the negative electrode plate facing the steel strip is covered with an insulating member having a predetermined area to change the electrode area. . The area where the current density is high is covered with an insulating member having a large area, and the area where the current density cloth is low is covered with an insulating member having a small area or is not covered with an insulating member.

According to the electrolytic pickling apparatus of the third aspect of the present invention, an insulating tape is used as an insulating member so that the electrode area can be easily changed. Further, according to the electrolytic pickling apparatus according to claim 4 of the present invention, the electrode area is changed by providing a through-hole having a predetermined area at least in the negative electrode plate. A through-hole with a large area is provided at a place where the current density is high, and a through-hole with a small area is provided at a place where the current density is low, or the through-hole is not provided, thereby achieving a uniform current density distribution.

[0015]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic side view of a first embodiment of an electrolytic pickling apparatus according to the present invention, and FIG. 2 is a schematic front view of an electrode portion and a current density distribution. As shown in FIG. 1, the steel strip, for example, the stainless steel strip 1 annealed after the cold rolling is performed is introduced downward into the tank 4 filled with the neutral salt electrolyte through the deflector roll 5a. The tension is applied by a center roll 5b provided in the tank 4 and the tank 4 is bent upward and
It is drawn out from the inside and is sent out to the washing and drying processing apparatus of the next step via the deflector roll 5c. In the tank 4 between the deflector roll 5a and the center roll 5b, a pair of positive electrode plates 2a and 2b are kept parallel to the stainless steel strip 1 while maintaining a predetermined distance above and below the stainless steel strip 1, respectively. Arranged at a predetermined angle, the center roll 5b
In the tank 4 between the deflector roll 5c and the stainless steel strip 1, a pair of negative electrode plates 3a and 3b are held above and below the stainless steel strip 1 at a predetermined distance in the same manner as the positive electrode plates 2a and 2b. And are arranged at a predetermined angle so as to be parallel to. Then, the positive electrode plates 2a and 2b and the negative electrode plate 3
DC power E is supplied between a and 3b.

On the surface of the positive electrode plate 2a facing the stainless steel strip 1, at both ends in the electrode width direction, the center roll 5b is wider than the deflector roll 5a, as shown in FIG. An insulating member such as an insulating tape 6a,
6b is deposited. Similarly, on the opposite surface of the negative electrode plate 3a to the stainless steel strip 1, the insulating tapes 7a and 7b are provided at both ends in the electrode width direction so that the center roll 5b has a larger area than the deflector roll 5c. Is attached. As in the conventional example shown in FIG. 6, the current density distribution in the electrode length direction usually has the positive electrode plates 2a, 2b and the negative electrode, whose polarity switches due to the resistance component of the stainless steel strip 1. Since the current density increases on the center roll 5b side of the plates 3a, 3b, the insulating tapes 6a to 7b are attached to the center roll 5b side with a larger area so as to suppress this. Positive electrode plate 2b disposed below stainless steel strip 1
Similarly, the stainless steel strip 1 is used for the negative electrode plate 3b.
An insulating tape having a large area on the side of the center roll 5b is attached to the surface facing the center roll 5b.

At this time, the adhesion area of the insulating tape is set so that the current density distribution in the electrode length direction becomes uniform. For example, FIG. 3 shows the current density distribution in the electrode length direction of the positive electrode plate 2a when the attachment area of the insulating tape 6a is changed. FIG. 3A shows a front view of the surface of the positive electrode plate 2a (2b) facing the stainless steel strip 1 in the state of the masks 1 to 3, and the state of the mask 1 is positive at the leading end in the line traveling direction. The electrode width direction of the electrode plate 2a is divided into 1: 2: 1, and insulating tapes 6a and 6a are provided on outer portions when straight lines are drawn from each division point to each corner at the rear end in the line traveling direction.
6b is attached. Similarly, the mask 2 state is
The width direction of the positive electrode plate 2a at the front end in the line traveling direction is divided into 3: 2: 3, and the state of the mask 3 is similarly divided into 1: 1 and the insulating tapes 6a and 6b are respectively attached.

The current density distribution J when the adhesion area of the insulating tapes 6a and 6b is changed as described above is calculated as follows. First, the current density J ₀ (A / m ² ) at each position X (m) in the electrode length direction in a state without a mask when the insulating tape 6a is not attached is calculated based on the following equations (1) and (2). And calculate. _{J 0 = J 1 αL · cosh} (αX) / sinh (αL) ... (1) α = (2 ρ s / ρl 1 l 2) 1/2 ... (2) where, J ₁ is the average current density (A / m ²⁾ represents, determined by dividing the quantity of electricity density (C / dm ²⁾ at a given time, [rho is liquid resistance (Ωm), ρ _s is a steel sheet resistance (Omega
m) and l ₁ indicate the steel plate thickness (m), l ₂ indicates the distance between the electrode and the steel plate (m), and L indicates the electrode length (m).

Then, an insulating tape 6a is attached as shown in FIG. 3A, and the current density J (A
/ M ² ) is calculated based on the following equation (3). J = J ₀ (1−Rvt / L) (3) Here, R represents the mask ratio in the electrode width direction at the leading end in the line traveling direction of the positive electrode plate 2a. 1 and in the mask 1 state, R =
0.5. v represents the line speed (mpm), t
Indicates that the rear end of the positive electrode plate 2a in the line traveling direction is t = 0.
Represents the time when the head moves in the line traveling direction at the line speed v, and each position X in the electrode length direction is calculated from vt. Then, the effective electrode width ratio in the electrode width direction at each position X in the electrode length direction is obtained by (1−Rvt / L).

When the adhesion area of the insulating tape 6a is changed as shown in the states of the masks 1 to 3, and in the formulas (1) to (3), for example, each value is set as shown below, the values in the electrode length direction can be obtained. The current density distribution J changes according to the state of the masks 1 to 3, as shown in FIG. When there is no mask, a large value in the electrode length direction, that is, the center roll 5b
On the side, high current density is shown, and above the average current density, oxygen generation takes precedence and the descaling performance decreases.
Then, as the area covered from the mask 1 to the mask 3 increases, the high current density on the center roll 5b side decreases.

J ₁ : average current density (A / m ² ) = 20 (C / dm ² ) /
(L / v60) ρ: liquid resistance (Ωm) = 0.0670 ρ _s: steel resistance ^{(Ωm) = 7 × 10 -7} l 1: steel plate thickness ^{(m) = 1.5 × 10 -3} l 2: electrode・ Distance between steel plates (m) = 8 × 10 ⁻² L: electrode length (m) = 3.78 v: line speed (mpm) = 80 When each value is set as described above, the insulating tape 6a
The current density distribution becomes uniform and the spikes (pointed portions) of the current density can be suppressed by selecting a mask ratio in the middle between the mask 1 and the mask 2 for the adhesion area of the mask 1. In the first embodiment, the optimum adhesion area of the insulating tape 6a is appropriately selected according to the liquid resistance value, the thickness of the steel sheet, the line speed, and the like, and a predetermined adhesion area for making the current density distribution uniform is set. .

Next, the operation of the first embodiment will be described.
The stainless steel strip 1 travels along each roll at a predetermined speed, for example, 80 m / min, and the surface of the stainless steel strip 1 passing between the negative electrode plates 3a and 3b is positively charged to form an anode surface. On the anode surface, reactions such as dissolution of metal and generation of oxygen proceed by a chemical reaction, and scale on the surface of the stainless steel strip 1 is chemically removed. When the values such as the liquid resistance value, the steel plate thickness, and the line speed are set as described above, the insulating tape 6a having a mask ratio around the middle between the mask 1 and the mask 2 is attached to each electrode. As shown in FIG. 2 (B), spikes in the current density in the electrode length direction are suppressed, the current density distribution becomes uniform, excessive oxygen generation on the anode surface of the stainless steel strip 1 is suppressed, and Electrolytic pickling is continued without reducing the scale performance.

As described above, in the first embodiment, since the insulating tape is attached to each electrode at a predetermined mask ratio, the current density distribution of the electrolytic current can be made uniform with a simple configuration, and Excessive oxygen generation on the anode surface of the steel strip 1 can be suppressed, and electrolytic pickling can be performed without lowering the descaling performance. Since a portion having a high current density can be suppressed low, power consumption can be reduced. Further, even if the liquid resistance, the line speed and the like are changed, it is only necessary to change the adhesion area of the insulating tape 6a, so that it is possible to flexibly cope with a change in the pickling process.

Next, a second embodiment of the electrolytic pickling apparatus according to the present invention will be described with reference to the front view of the positive electrode plate 2a (2b) shown in FIG. The basic configuration is the same as that of the first embodiment, and is different from the first embodiment in that the electrodes 2a to 3b are provided with through holes instead of the insulating members. For example, as for the positive electrode plate 2a (2b), as shown in FIG. 4, the area of the penetrated portion of the positive electrode plate 2a at the front end side in the line traveling direction is larger than that at the rear end side in the line traveling direction. As described above, through-hole 8 is provided in positive electrode plate 2a. The shape of the through hole 8 is set so that the current density distribution becomes uniform. That is, as in the first embodiment, the ratio between the through hole 8 and the non-through hole in the electrode width direction at each position X in the electrode length direction is calculated, and the current density is calculated by the equation (3) based on the effective electrode width ratio. The distribution J is obtained, and the area of the through hole 8 is set according to the liquid resistance, the line speed, and the like so that the current density distribution J becomes uniform. Each electrode is formed with a through hole 8 having the same shape, each of the positive electrode plates 2a, 2b is provided with a through hole having a plane-symmetric shape, and each of the negative electrode plates 3a, 3b is formed with a plane symmetry. A through-hole is provided so that the area penetrated on the side of the center roll 5b increases.

As described above, in the second embodiment, by providing the through holes 8 having a predetermined shape in each electrode, the current density distribution of the electrolytic current can be made uniform with a simple configuration. As in the example, excessive oxygen generation on the anode surface can be suppressed, and electrolytic pickling can be performed without lowering the descaling performance. In addition, the formation of the through holes 8 can prevent gas accumulation and sludge accumulation on the electrode surface, and can perform electrolysis efficiently. In the second embodiment, the electrode width at the front end in the line traveling direction has the same shape as the conventional one, and a spike in the current density occurs at the front end in the line traveling direction where the polarity of the electrode switches, but the spike is within a narrow range. Therefore, the effect of spikes can be minimized, and the descaling performance can be maintained at a high level.

In each of the above embodiments, the electrolytic pickling is performed in the tank 4 filled with the neutral salt solution, but an acidic solution such as nitric acid or sulfuric acid may be used instead of the neutral salt. . Also,
The shapes of the insulating tape 6a and the through-hole 8 are not limited to the above-described embodiment, and may be a predetermined curved shape.
In addition, an insulating member and a through-hole of any shape of a circle or a corner,
A plurality may be provided at predetermined intervals corresponding to the current density distribution of the electrolytic current. Further, instead of the insulating tape 6a, an effective area of the electrode may be set by applying an insulating paint to the electrode portion. Alternatively, an effective area of the electrode may be set by sandwiching a U-shaped insulating plate between the edges of the electrode.

In each of the above embodiments, an insulating member is attached to each of the negative electrode plate portion and the positive electrode plate portion or through holes are provided. However, an insulating member is attached only to the negative electrode plate portion. Also, by providing a through hole, the current density distribution of the electrolytic current in the negative electrode plate can be made uniform as shown in FIG. 5, and excessive oxygen generation on the anode surface of the stainless steel strip 1 can be achieved. Can be suppressed to some extent, and the descaling performance can be improved.

[0028]

As described above, in the invention according to the first aspect, at least the electrode area of the negative electrode plate on the surface facing the steel strip has a high current density of the electrolytic current flowing between the electrode and the steel strip. It is set to lower the site. As a result, the current density distribution can be made uniform, and the acid generated on the anode surface of the steel strip can be suppressed, so that pickling properties can be increased and descaling performance can be improved. Further, it is possible to achieve a reduction in power consumption by effectively using the current. Furthermore, since the electrode surface is used uniformly, it is possible to avoid local consumption of the electrode.

Then, in the invention according to claim 2,
The electrode area is changed by covering the surface of the electrode on the steel strip side with an insulating member having a predetermined area. Therefore, it is possible to achieve a uniform current density distribution with a simple configuration. In the invention according to claim 3, an insulating tape is used as the insulating member. Thus, even if the liquid resistance, the line speed, and the like are changed, the adhesion area can be changed only by replacing the insulating tape, and it is possible to flexibly cope with a change in the pickling process.

In the invention according to claim 4,
The electrode area is changed by forming a through hole having a predetermined area in the electrode. Therefore, it is possible to achieve a uniform current density distribution with a simple configuration. Further, since the through holes are provided, accumulation of gas and accumulation of sludge on the electrode surface can be avoided, and electrolysis can be performed efficiently, so that descaling performance is further improved.

[Brief description of the drawings]

FIG. 1 is a schematic side view of an electrolytic pickling apparatus according to the present invention.

FIG. 2A is a schematic front view of an electrode unit according to the first embodiment of the present invention. (B) is a distribution diagram showing the current density in the electrode length direction.

FIG. 3A is an explanatory diagram showing a mask shape.
(B) is a distribution diagram showing the current density when the mask ratio is changed.

FIG. 4 is an explanatory view of an electrode according to the electrolytic pickling apparatus of the second embodiment.

FIG. 5 is a distribution diagram showing a current density when an insulating member is attached to only the negative electrode plate or a through hole is formed.

FIG. 6 is an explanatory view showing a conventional electrolytic pickling apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stainless steel strip 2a, 2b Positive electrode plate 3a, 3b Negative electrode plate 4 Bath 6a-7b Insulating tape 8 Through hole

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshiya Hagiwara 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works (72) Inventor Yoshihiro Satake 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Inside Chiba Works (72) Inventor Hiroshi Saito 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Works Chiba Works (58) Fields investigated (Int. Cl. ⁶ , DB name) C25F 7/00 C25F 1/06

Claims (4)

(57) [Claims] 1. An acid pickling tank filled with an electrolytic solution through which a steel strip passes, and the pickling tank is separated from the front and back surfaces of the steel strip by a predetermined distance in the pickling tank, and sandwiches the steel strip. A pair of positive electrode plates for electrolysis disposed opposite to each other, while being separated from the both sides of the steel strip by a predetermined distance in the pickling tank, and facing each other across the steel strip. And a pair of negative electrode plates for electrolysis disposed at a predetermined distance from the positive electrode plate in the steel strip passing direction side, and a scale on the surface of the steel strip is electrolyzed. In the electrolytic pickling apparatus that removes at least the negative electrode plate, at least a portion where the current density of the electrolytic current flowing between the steel strip and the steel strip is high, by a predetermined setting of the electrode area on the surface facing the steel strip. An electrolytic pickling apparatus characterized by lowering the temperature. 2. The electrolytic pickling according to claim 1, wherein the electrode area is set by covering at least a surface of the negative electrode plate facing the steel strip with an insulating member having a predetermined area. apparatus. 3. The electrolytic pickling apparatus according to claim 2, wherein the insulating member is an insulating tape. 4. The electrolytic pickling apparatus according to claim 1, wherein the electrode area is set by forming at least a through hole having a predetermined area in the negative electrode plate.