JP2790314B2 - Horizontal plating tank - Google Patents

Description

The present invention relates to a horizontal plating tank suitable for plating a metal strip (hereinafter, referred to as a strip) at a high current density and at a high strip traveling speed.

<Prior Art> Many techniques have been disclosed which enable high-speed processing at high current density in strip electroplating.

In order to enable high current density processing, i) how to remove the gas generated by the high current density from the strip surface or electrode surface, ii) how to increase the limit current density, or The most important point is how to prevent the reduction in plating efficiency caused by insufficient supply of plating metal ions.

As a method of removing gas from the strip surface or the electrode surface, or increasing the limiting current density, a so-called counter flow, that is, having the effect of forcibly circulating the plating solution in a direction opposite to the strip traveling direction is effective. It has been known and implemented since ancient times. In other words, in order to increase the limiting current density, it is important to increase the relative speed between the plating solution and the strip in order to increase the supply of plating metal ions at the strip interface. It is advantageous.

In order to effectively perform the counterflow in the electrolytic treatment of the strip, a tubular plating tank having a rectangular cross section having side walls surrounding the edges of the strip is provided on the side surfaces of both electrodes provided opposite to both surfaces of the strip. A method for performing this is disclosed, for example, in Japanese Patent Publication No. 50-8020.

However, although the technique disclosed in Japanese Patent Publication No. 50-8020 aims to increase the line speed, as the strip speed increases, the amount of plating solution that is pulled by the strip and taken out to the outlet side in the strip traveling direction increases. For this reason, the supply amount of the plating solution is insufficient, and liquid shortage (that is, a state where the plating solution is not sufficiently supplied between the electrode and the strip) is likely to occur at the electrode end on the entry side in the strip traveling direction.

Therefore, it is necessary to overcome the force of the strip to take out the plating solution to the output side and to give a plating solution discharge amount that does not cause the solution to run out. It is necessary to provide a high supply liquid flow rate by the liquid supply pump.

<Problems to be Solved by the Invention> If the plating bath disclosed in Japanese Patent Publication No. 50-8020 is to be used at a high plating solution flow rate in an actual plating line, the following structure is required on the plating solution discharge side (strip entry side). There is a problem above.

The plating solution flow spouted from the upper surface discharge port is blocked by the rolls, rises, and flows down to the side of the strip. For this reason, the flow rate of the plating solution at the center of the discharge port is significantly reduced as compared with the side, and a difference in plating quality such as plating thickness is caused.

The catenary amount of the strip increases due to the weight of the plating solution blocked, and the catenary amount varies depending on the flow rate of the plating solution, so that the distance between the electrodes cannot be reduced.

The present invention solves these problems of the prior art and provides a horizontal plating tank capable of maintaining a uniform plating solution flow velocity distribution in a width direction of a plating solution discharge side and efficiently eliminating bubbles accompanying plating. It is intended to be.

<Means for Solving the Problems> In order to achieve the above object, according to the present invention, a cylindrical cross-section comprising a pair of insoluble anodes and side seals disposed opposite to both surfaces of a passing strip. In the plating tank, there is a liquid supply nozzle for ejecting a plating solution parallel to the strip surface from the strip outlet side to the inlet side so as to face the strip passing direction, and the upstream side of the plating tank and the In a horizontal plating tank having an energizing roll and a backup roll on the downstream side of the liquid supply nozzle, respectively, adjusting the liquid level in the tank between the upstream energizing roll and the backup roll and a strip entry side opening of the plating tank. A horizontal plating tank is provided, wherein a liquid tank having a possible drain port is provided in communication with the opening.

 Hereinafter, the present invention will be described in more detail.

1 and 2 are a partial sectional side view of a horizontal plating tank and a cutaway perspective view of a liquid tank part showing an embodiment of the present invention.

Strip 1 is electroplated while running from left to right in FIG.

The insoluble anode 2 is provided in a plating tank 3 having a cylindrical cross section so as to oppose both upper and lower surfaces of the running strip 1, and the entire surface of the opposing surface of the strip 1 may be a current-carrying surface. May be used to restrict the energized surface.

The side seal 4 is provided between the upper and lower ends of the insoluble anode 2 in the width direction of the strip 1, and the pair of insoluble anodes 2 is provided.
And a plating space are formed so that the plating solution does not flow out from both sides in the width direction of the strip 1.

The liquid supply nozzle 5 is for supplying a plating solution from the downstream side of the strip 1 to the upstream side so as to face the direction in which the strip 1 passes, and is provided downstream of the pair of insoluble anodes 2 in the passing direction. The strip 1 is provided in contact with the side end, and opens toward the upper surface and the lower surface of the strip 1, respectively. Reference numeral 6 denotes a liquid supply header.

An energizing roll 10 and a backup roll 11 are provided on the entry side of the strip 1 in the traveling direction. A liquid tank 12 is provided between these rolls and the opening of the plating tank 3 on the entry side of the strip 1.
Is provided in communication with the opening.

The side surface of the liquid tank 12 where the strip 1 enters includes the surfaces of the energizing roll 10 and the backup roll 11, and is provided with a side plate 12a which is in contact with the outer peripheral surfaces and ends of these rolls in a sealed state.

A pair of side plates 12b is provided on a surface of the liquid tank 12 which is perpendicular to the side plates 12a. A drain port 13 having an adjusting plate 13a that can slide up and down to adjust the liquid level in the liquid tank 12 is provided behind the opening surface of the side plate 12b on the side of the strip 1 on the plating tank 3. I have.

The lower surface of the drain port 13 has an opening center line L as shown in FIG.
(Essentially a strip bus line).

The liquid tank 12 only needs to have a volume sufficient to uniformly discharge resistance of the plating solution discharged from the plating tank 3.

FIG. 3 is an explanatory view showing another embodiment of the present invention.
The description other than the liquid tank 12 is the same as the above description, and thus the description is omitted.

Between the strip 1 outlet opening of the preceding plating tank 3a and the strip 1 inlet opening of the subsequent plating tank 3b,
A liquid tank 120 is provided in communication with the openings.

In the case where there are three or more plating tanks, the same tank as the liquid tank 120 provided between the two tanks may be provided between the plating tanks. According to such a structure, when the plating tanks are continuously arranged, the side plate 120a on the side surface of the liquid tank 120 on which the strip 1 is inserted.
Is preferable because it does not require a complicated shape like the side plate 12a in FIG.

Next, an operation example of the horizontal plating tank of the present invention will be described with reference to FIGS.

When the plating solution is pressure-fed and ejected from the solution supply nozzle 5 by a pump (not shown) in a countercurrent direction to the traveling direction of the strip 1, the plating solution flows in the plating tank 3 toward the strip 1 entry side, and flows through the solution tank 12. Then, the liquid is discharged from the drain port 13.

On the other hand, the strip 1 is introduced into the plating tank 3 from between the energizing roll 10 and the backup roll 11 through the liquid tank 12 and plated under predetermined conditions, and then passes between the energizing roll 8 and the backup roll 9. Is discharged.

Here, if the height of the liquid level adjusting plate 13a is adjusted so that the amount of the plating solution in the liquid tank 12 becomes a predetermined amount according to the plating conditions, the predetermined passing speed and the ejection of the plating solution from the liquid supply nozzle 5 are achieved. In terms of volume, the plating liquid flow on the upper surface of the strip 1 in the plating tank 3 flows in the liquid tank 12 as shown by a solid arrow in FIG. Also, the strip 1 in the plating tank 3
The plating solution flow on the lower surface once descends in the liquid tank 12 and then rises in the liquid tank 12 as shown by the dashed arrow in FIG.
Is discharged from

As described above, the plating tank 3 is placed in the liquid tank 12
By adjusting the liquid level, the plating liquid flow velocity distribution on the upper, lower, and width directions of the strip 1 in the plating tank 3 can be made uniform.

<Example> Hereinafter, the present invention will be specifically described based on examples.

Example 1 Using a horizontal plating tank shown in FIG. 1, a steel strip having a thickness of 0.7 mm and a width of 1000 mm was plated using a Zn-Ni plating solution under the following conditions.

Anode length: Total length 1000mm, effective length 500mm Anode width: 1200mm Anode-strip distance 15mm Passing speed: 120m / min Strip entrance side energizing roll axis-plating tank entrance 300m
m 400 m between plating tank outlet and strip exit side energizing roll axis
m The results are shown in Table 1 and FIG. The solid line and the broken line in FIG. 4 show the flow velocity distribution on the upper side and the lower side of the strip on the strip entry side of the plating tank, respectively.

(Comparative Example) Chrome plating was performed under the same conditions as in Example 1 except that the same steel strip as in Example 1 was used and the same plating tank from which the liquid tank 12 was removed was used.

The results are shown in Table 1 and FIG. The solid line and the broken line in FIG. 5 show the flow velocity distribution on the upper side and the lower side of the strip on the strip entry side of the plating tank, respectively. In the comparative example, leakage of the plating solution occurred as shown by the meshes in FIG.

By using the plating solution of the present invention, the plating solution flow rate distribution in the width direction on the strip entry side could be maintained uniformly on the upper and lower surfaces of the strip. In addition, the generated gas was completely discharged.

<Effects of the Invention> Since the present invention is configured as described above, the outflow resistance of the plating solution discharge portion (strip entry side) of the plating tank is reduced, so that the plating solution flow rates on the upper, lower, and width directions of the strip. The distribution can be kept uniform, and the plating quality can be improved.

Further, according to the present invention, a counter flow can be reliably provided by a plating solution supply pump having a remarkably small capacity as compared with the related art, and power consumption can be reduced. Further, since the relative speed between the strip and the plating solution in the vicinity of the strip surface can be increased, the effect of improving the limiting current density can be obtained, and the effect of preventing a decrease in the cathode efficiency due to the lack of plating metal ions is also remarkable.

Further, since the flow rate and the flow velocity of the plating solution between the electrodes can be increased, the discharge property of the gas generated between the electrodes is improved.

Since there is no obstruction in the plating solution discharge portion (strip entry side) of the plating tank, the discharge of gas generated between the gaps is improved.

Also, at the plating solution outlet (strip entry side)
Since the weight of the plating solution is not applied to the strip, the amount of catenary is reduced, and the distance between the electrodes can be reduced.

Further, the operability is improved because the flow rate and flow rate of the plating solution between the electrodes do not depend on the line speed.

[Brief description of the drawings]

FIG. 1 is a partial sectional side view of a horizontal plating tank showing one embodiment of the present invention. FIG. 2 is a cutaway perspective view of a liquid tank portion schematically showing a flow of a plating solution in the liquid tank. FIG. 3 is an explanatory view showing another embodiment of the present invention. FIG. 4 is a graph showing a plating solution flow velocity distribution in the plate width direction on the strip entry side of the plating tank. FIG. 5 is a graph showing a plating solution flow velocity distribution of a comparative example. FIG. 6 is a view showing a state of leakage of a plating solution in a comparative example. DESCRIPTION OF SYMBOLS 1... Strip, 2... Insoluble anode, 3,3a, 3b... Plating tank, 4... Side seal, 5... Liquid supply nozzle, 6. Roll, 9,11 Backup roll, 12,120 Liquid tank, 12a, 12b, 120a Side plate, 13 Drain port, 13a Liquid level adjustment plate, L Center line of opening

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Horita 1-chome, Kawasaki-dori, Mizushima, Kurashiki-shi, Okayama Pref. 1 Kawasaki Steel Corporation Research and Development Headquarters (56) References JP-A-60-14995 (JP, A) JP-A-63-24095 (JP, A) JP-A-2-85396 (JP, A) 61-207595 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C25D 7/00-7/12

Claims (1)

(57) [Claims] In a plating bath having a tubular section having a pair of insoluble anodes and side seals disposed on both sides of a strip passing therethrough so as to face a strip passing direction from a strip exit side. It has a liquid supply nozzle for ejecting plating solution parallel to the strip surface toward the entry side,
In a horizontal plating tank having an energizing roll and a backup roll on the upstream side of the plating tank and on the downstream side of the liquid supply nozzle, respectively, the upstream energizing roll and the backup roll,
A horizontal plating tank, wherein a liquid tank having a drainage port capable of adjusting the liquid level in the tank is provided in communication with the opening between the strip inlet side opening of the plating tank and the opening.