JPS60135600A - Electrolytic treating device for steel strip - Google Patents

Abstract

PURPOSE:To perform efficiently an electrolytic treatment with high current density by providing plural electrode pairs which have different polarities and sandwich the steel strip traveling in an electrolyte from above and below, disposing current shielding plates so as to intervene between the electrodes on the outside circumference from both side edges of the steel strip and changing alternately the polarities of the plural electrode pairs. CONSTITUTION:Two sets of electrode pairs 131, 13'1, 132, 13'2 which are in proximity to each other and have different polarities are provided so as to sandwich, from abov and below, a steel strip 10 which travels while the strip is immersed in the electrolyte 11 in an electrolytic cell. Electrical shielding plates 151, 152 having an insulating characteristic are disposed on both side ends of the strip 10 so as to overlap partly on the strip 10 and to intervene between the upper and lower electrodes 131, 13'1, 132, 13'2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolytic treatment apparatus for steel strips, and more particularly to an improvement in an electrolytic treatment apparatus using an indirect energization method.

For electrolytic pickling, electrolytic degreasing, etc. of steel strips, an indirect energization type electrolytic treatment apparatus shown in FIG. 1 has conventionally been widely used. In the figure, 1 is an electrolytic cell filled with an electrolytic solution (hydrochloric acid, sodium orthosilicate, etc.). Feed rolls 2s and 22 are disposed at the inlet and outlet of the electrolytic cell 1, and the steel strip 1O is continuously passed through the electrolyte by the feed rolls. In the electrolytic cell 1, there is a band 1
(+) electrode 31 and (-) electrode on the lower surface side along i41O
Electrodes 31' are alternately arranged, and similarly, (+) electrodes 32 and (-) electrodes 32' are alternately arranged on the upper surface side of the steel strip 1O. In addition, 4 in the figure is an electrolytic power source, which is connected to the (+) electrode and the (-) electrode, respectively, as shown.

In the electrolytic treatment apparatus using the indirect energization method shown in FIG.
1.32 and flows through the electrolyte to band 110. Next, the electrolytic current flowing through the band U410 passes through the electrolyte (-
) reaches the electrodes 31, 32- and returns to the respective electrolytic power sources 4. At that time, the surface of the steel strip 1O, for example, the (+) electrode 31.
The surface of the steel strip facing 32 becomes polarized, and when the electrolytic solution reaches a voltage that electrolyzes, electrolysis occurs on the surface of the steel strip, and electricity flows from the surface of the steel strip in proportion to the current density. Hydrogen gas (H2) is generated. Moreover, the (-) electrode 31-. 32
The steel strip surface facing - has (+) polarity, and oxygen gas (0
2) occurs. Then, the scale on the surface of the steel strip is removed by the synergistic effect of the physical cleaning effect of hydrogen gas and oxygen gas and the chemical pickling effect or degreasing effect of electrolyte such as hydrochloric acid or ol-1-sodium phosphate. Scaling is performed, and the oil film is degreased and cleaned.

By the way, in the above-mentioned conventional electrolytic treatment apparatus using the indirect energization method, electrolysis occurs simultaneously on both the upper and lower surfaces of the steel strip 10 facing the (+) electrode and the (-) electrode, and therefore, one set of electric circuits is used to treat the steel strip 10. Although it has the advantage of being able to generate electrolytic action at four locations on the surface, it has the following problems.

That is, from the (+) electrodes 3s and 32 through the steel strip 10 (
-) When current flows to the electrodes 31-, 32-, since the electrical resistance of the steel strip is large, the voltage required to flow a predetermined current becomes high, and power consumption increases.

Therefore, in order to avoid the problems of the above-mentioned indirect energization type electrolytic treatment apparatus, a direct energization type electrolytic treatment apparatus as shown in FIG. 2 or 3 has recently been adopted. In this direct energization method, an energizing roll (commonly known as a contactor roll) is used in place of the feed rolls 21 and 22 in FIG. 1, and a current is passed directly from the contactor roll to the steel strip.

In FIG. 2, 51 and 52 are contactor rolls. A negative voltage is applied to these contactor rolls, and electrodes 3
+ and 32 are provided, respectively. Also, (10) electricity +1
Nozzles 61 and 62 are arranged at the ends of u3t and 32, respectively. The nozzles 6+, 62 are connected to the belt uA, which is suspended in contact with a conductor roll as shown in the figure.
10 and the (+) electrodes 31, 32, an electrolytic solution is spouted out between the electrodes 31 and 32. A current flows from the band m10 to the hot electric poles 3 and 32 through the electrolytic solution spouted out in this way, and electrolytic treatment is performed on the surface of the steel band.

In the direct energization method shown in FIG. 2, since the resistance when the current flows through the steel strip 1O is small, a large current can be passed at a low voltage and a large current density can be obtained. Therefore,
4) The energization time is short and the total length of the equipment can be shortened when the power consumption is the same as in the case of the indirect energization method, so it has the advantage that the same electrolytic effect can be obtained with less equipment cost. However, the direct energization method of FIG. 2 has the disadvantage that electrolysis is performed only on one side of band #41O.

On the other hand, in the direct energization method shown in Fig. 3, the strip MIO is fed through contactor roll pairs 71 to 73, and between each conductor roll, the (+) N poles arranged on the strip steel 1O and both above and below it are fed. 3r and 32, an electrolytic solution is ejected from nozzles 61 and 62 to perform electrolytic treatment. In this case, the second
Unlike the case shown in the figure, the electrolytic treatment is performed on both the upper and lower sides of the steel strip 1○, but since the electrical resistance of the band mio is included between the conductor roll pair 7 and the (+) electrode 3, Compared to the conventional case, a high voltage is required, and power consumption inevitably increases. However, compared to the indirect energization method shown in FIG. 1, the current density is much higher by 1q. For this reason, the direct energization methods shown in FIGS. 2 and 3 are both called high current density methods (High5-Current Density, abbreviated as 1-icD methods).

Note that the above-mentioned HCD method has another problem that will be added below.

In order to prevent seizure and decrease the yield, a 3% solution of sodium orthosilicate is used for the electrolysis d= to reduce silicon oxide (SiO2) to approximately 2 m'j/Td ~ 4 ml.
/Go is given. That is, a trace amount of 5102 is present on the surface of the steel strip.
By adding , it is possible to avoid seizure during annealing. In this case, S + 02 has the property of adhering in proportion to the current density in the (-) polarity of the steel strip.

By the way, in the direct energization method shown in FIG. 2 or 3, the steel strip has (-) polarity and the current density is high, so a large amount of 8+02 adheres. As a result, for example, when tin plating is performed in the next step, there is a problem that the plating performance is inhibited. Therefore, in order to control the amount of SiO2 deposited, a certain proportion of 6-soda is added as an electrolyte. - A method of adding and mixing with sodium silicate has also been proposed. Furthermore, in the HCD system of FIGS. 2 and 3, the conductor roll also has (-) polarity. Therefore, SiO2 also adheres to the conductor roll, deteriorating the conductivity and causing an increase in voltage.

In order to avoid this, if the polarity of the conductor roll is switched to (10), S l 02 will not adhere to the steel strip, resulting in seizure during annealing. Due to these circumstances, the fourth
As shown in the figure, conductor rolls of (-) polarity and (
In addition to the +) electrode 5s and 31, a (+) polar conductor roll 8 and (=) electrode 31- are used in combination, and the 51
A method for controlling the amount of 02 deposited has been proposed. However, this method has the problem of an unavoidable increase in equipment costs.

The present invention has been made in view of the above circumstances, and by improving the indirect energization type electrolytic treatment equipment, it is possible to efficiently process steel strips at high current density without causing the problems of the direct energization type. The present invention provides an electrolytic treatment device.

That is, the electrolytic treatment apparatus for steel strip according to the present invention approaches a steel strip immersed in an electrolytic solution and runs so as to sandwich it from above and below,
A plurality of pairs of electrodes having different polarities on the upper and lower sides are provided along the longitudinal direction of the steel strip, and a current shielding plate is provided between the electrodes provided on the upper and lower sides on the outside from both side edges of the steel strip. , and the polarity of the plurality of electrode pairs is alternately changed.

Hereinafter, the present invention will be explained in detail with reference to FIGS. 5 to 7.

FIG. 5 is an explanatory diagram showing an electrolytic treatment apparatus for steel strip according to an embodiment of the present invention, and FIG. 6 (A> is Vl - V in FIG. 5).
l 41! FIG. In these figures,
11 is an electrolytic cell filled with an electrolytic solution (hydrochloric acid, ortho-silicic acid sorter, etc.). Feed rolls 121, 122 are disposed at the inlet and outlet of the electrolytic cell 1, and the steel strip 1O is continuously passed through the electrolyte by the feed rolls. In the electrolytic cell 1, two pairs of electrodes 1 are placed adjacent to the steel strip 1O so as to sandwich it from above and below.
3+, 131- and 132.132- are arranged. Are these electrode pairs each electrolytic type? +! 141°14
Connected to 2. Further, as shown in FIG. 6(A), insulating electrical shielding plates 151.
152 is disposed interposed between the upper and lower electrodes, partially overlapping the steel strip 1O.

Comparing the electrolytic treatment apparatus of the above embodiment with the conventional electrolytic treatment apparatus using the indirect energization method explained in FIG. This is the most important feature of the present invention. That is, in the above embodiment, the electrolytic currents are respectively (
+) flows to the electrodes 131, 132 and through the electrolyte to the band 1i
110, the electrolyte passes through the electrolyte again to each of the opposing electrodes 131-. 132-, power supply 141.1
By returning to the steel strip 42, electrolysis occurs on both the upper and lower surfaces of the steel strip 1O. Therefore, in this case, the direction in which the current flows in the steel strip is perpendicular to the surface of the steel strip 1O, and the cross section of the steel strip in which the current flows is significantly larger than in the case of Fig. 1. Therefore, the resistance when current flows through the steel strip becomes extremely small. Further, in the case of FIG. 1, almost no reactive current flows directly between the electrodes. As a result, an extremely high current density is obtained, which shortens the electrolysis time or the overall length of the equipment (conventional
/4 to 1/2), it is possible to reduce the equipment cost and solve the problems with the conventional indirect energization method.

Furthermore, since the current density can be increased, the electrolytic efficiency is increased, and a hot caustic tank and brush roll for rough cleaning are not required, so that equipment costs can be reduced. Furthermore, since the voltage rise is small, power consumption is low, resulting in significant energy savings. In particular, the power consumption in the case of ultra-thin plate tin gauges is 1/4 to 1/1 that of conventional ones.
2 or less.

By the way, as a result of reversing the polarity of the vertically opposed electrodes as described above, there is a concern that in the embodiment shown in FIG. Ru. If current were to flow directly between the upper and lower electrodes without flowing through the strips 15i110, the electrical efficiency would be extremely low.

Therefore, in the above embodiment, electric shielding plates 151 and 152 are provided overlapping each other at both ends of the steel strip 1O to prevent such reactive current.

In this case, as shown in FIG. 6(B), the electric shielding plate 151-. If 152- is used and shielding plates are interposed on both upper and lower sides of the steel strip side end, a greater effect can be obtained.

On the other hand, according to the electrolytic treatment apparatus of the above embodiment, electrolysis occurs on both the upper and lower surfaces of the steel strip 1O, and the electrolytic treatment is performed, so that the electrolytic treatment of the strip steel is performed as in the conventional 1-1 CD method (direct energization method). The problem that electrolytic treatment can only be performed on one side does not occur. Furthermore, by appropriately switching the cleanliness of the above-described embodiments, it is possible to avoid the problem that occurs in the conventional HCD system, such as S1○2 adhering to the electrodes and causing an increase in voltage. Similarly, since electrodes with (''~) polarity and electrodes with (-) polarity are arranged alternately,
Excessive adhesion of SiO2 to the band uA10 is also prevented, and as in the case of the conventional indirect energization method shown in FIG. 1, approximately 2■/Tlt~4 Il+! ? It has the advantage that a suitable amount of /rrr can be obtained. Therefore, conventional H
It is no longer necessary to separately provide an electrode for controlling the amount of 3i○2 deposited as in the case of the CD method, and it is possible to reduce equipment costs and save energy accordingly.

In addition, the following effects can be obtained by applying the electrolytic treatment apparatus of the above embodiment to specific electrolytic treatment.

For example, in the case of electrolytic pickling, there are limits to the application of the HCD method depending on the type and concentration of the electrolyte, the material and lifespan of the conductor roll, but since the electrodes in the above example are treated as consumables, they can be used in a very wide range of applications. Applicable. In some cases, by combining mechanical descaling with equipment for pickling mild steel plates, it is possible to reduce the size of the pickling tank to 1/4 to 1/2 or less.

In addition, when applied to electrolytic cleaning equipment, the line speed is 2500 m/min, whereas the conventional line speed is 1000 m/min because it can obtain a high current density. It is also possible to achieve a line speed of 71/min. Furthermore, there is a possibility of continuous operation with a cold rolling mill (tandem cold mill).

Furthermore, it has become possible to connect NMS and AL (cold) continuously, and in particular, the line speed of AP is currently 100m/+n.
The maximum speed is 200 m/min, but at least 200 m/min is fully possible.

FIG. 7 is an explanatory diagram showing an electrolytic treatment apparatus according to another embodiment of the present invention. In this embodiment, there are three feed rolls 12r.
, 122, 123 to adopt a vertical structure, but other basic configurations are the same as the embodiment shown in FIG. In this case, in the figure, the (+) electrode and the (-) electrode are placed back to back, and it appears that current flows directly between them, but the surface of each electrode that does not face the steel strip is covered with an electrically insulating cover. For example, the electrode 13 may be lined with rubber.
- energization is prevented between. Further, in this case, the electrical shielding plates 151 and 152 have a mechanism that can follow the meandering that occurs when the steel strip 1O is passed through, and also have a structure that can follow changes in the width of the steel strip 10.

The embodiment shown in FIG. 7 can also provide various effects similar to those described with respect to the embodiment shown in FIG.

As detailed above, the steel strip electrolytic treatment apparatus according to the present invention is capable of efficiently electrolyzing a steel strip at a high current density even though it is an indirect energization method, and is capable of efficiently electrolyzing a steel strip at a high current density, which is different from the conventional direct energization method. This can bring about remarkable effects, such as avoiding problems that may arise.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a conventional electrolytic treatment apparatus for steel strip using an indirect energization method; Figures 2, 3, and 4 are explanatory diagrams showing a conventional electrolytic treatment apparatus using a direct energization method; The figure is an explanatory diagram showing an electrolytic treatment apparatus for steel strip according to an embodiment of the present invention, FIG. 6 (A> is a cross-sectional view taken along the line Vl-Vl in FIG. 4, and FIG. A sectional view showing a modification thereof, and FIG. 7 are explanatory views showing an electrolytic treatment apparatus for steel strip according to another embodiment of the present invention. 11... Electrolytic cell, 121.122.123. ...Feed roll, 131,132...(+) electrode, 13t-. 132'...(-) electrode, 141.142...Electrolysis power source, 151.15+-, 152,152-...・Electrical shielding plate. 15-

Claims (1)

[Claims] A plurality of pairs of electrodes are provided along the longitudinal direction of the steel strip, which are close to each other so as to sandwich the steel strip immersed in an electrolytic solution and run from above and below, and have different polarities at the top and bottom, and are arranged on both sides of the steel strip. An apparatus for electrolytic treatment of steel strip, characterized in that a current shielding plate is disposed between the electrodes provided above and below on the outside from the edge, and the polarity of the plurality of electrode pairs is alternately changed.