JPS5943558B2 - Etzi bar coat prevention electroplating method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electroplating method for preventing edge overcoat of a strip, and in particular to an electroplating method and apparatus that uses a gas-liquid mixture to control the electrical conductivity of the edge portion according to the strip width. be.

Generally, Ni, Cr, Sn, Zn, C on the surface of the steel strip.
As a method for producing plating layers such as U and alloy compositions thereof, an electrolytic treatment method is generally used.

In this case, it is basically necessary to place the opposing electrodes in appropriate positions and widths. However, because strips are passed continuously, it is difficult to pass through the same position, and it is common for strips of different widths to be passed through several times depending on the structure of the product. It is.

In this case, it is difficult to change the opposing electrode (usually the anode) continuously, regardless of whether it is a soluble or insoluble/specific anode. Generally, multi-divided electrodes are used and control is performed by turning them on and off, or by using divided energization. Since these methods are insufficient, and also because of the complexity of the work, a method is used in which a baffle plate is inserted between the anode and the cathode to prevent current flow.

This is a method in which the position of the end of the plate is detected using an EPC (Edge Position Control) or the like, and a mechanical current flow obstruction such as a baffle plate is inserted. Such mechanical methods are primarily used when the anode is dimensionally stable.

In this case as well, it is impossible to completely cover the edges,
In addition, being close to a moving object increases the risk of contact, and especially when changing from a narrow material to a wide material, the speed of operation after detection becomes a problem, so it is necessary to This creates an edge overcoat.
In order to prevent edge overcoat, a uniform current density that quickly responds to such a moving strip is required, but in addition to variations in the strip position, changes in the current density of the strip and on the front and back sides are also important. The difference in the amount of current applied (differential plating thickness) causes a difference in the degree of concentration of current at the edge portion, and mechanical edge position control is insufficient.

It is an object of the present invention to provide an electroplating method and apparatus which solves these conventional problems and requires less edge overcoat.

The present invention was discovered based on the foaming phenomenon in conventional electrolytic work.

That is, when performing close electrolysis using an insoluble electrode, a large amount of gas is generally generated on the surface of the insoluble electrode. If this generated gas is not removed quickly, for example, if the product is immersed in a static bath, the voltage will increase significantly and the area weight will decrease.
That is, the conductivity is inhibited by the amount of voltage increase. In order to avoid this, if the liquid is jetted from the anode surface to the strip of the counter electrode, the conductivity will be good and the liquid resistance will be reduced by an amount that brings about uniform electrodeposition and low voltage. Furthermore, if the amount of liquid is increased, the eject effect of the liquid jet will suck in external gas (generally air), causing a voltage increase greater than that in a static bath, and causing even more severe and uneven plating. It was done. The present invention was completed by utilizing these phenomena, and its main points are (1) The metal strip is held in space without being immersed in the electrolyte, and the electrode surface facing the metal strip is In an electroplating method in which electricity is applied while spraying an electrolytic solution, a gas or a gas is applied in advance to a predetermined position in the vicinity of the end of the metal strip surface facing from the end of the electrode surface and in the outflow path where the electrolytic solution flows toward the end. An electroplating method for preventing edge overcoat, characterized in that electroplating is carried out while spraying an electrolytic solution containing.

(2) In an electroplating device that injects electricity while injecting electrolyte from an electrode surface facing the metal strip while holding the metal strip in a space without immersing it in the electrolyte, to inject the electrolyte onto the electrode surface. an electrode having a nozzle hole for injecting gas or an electrolytic solution pre-containing gas, and provided so that the gas or gas-liquid injection nozzle hole is located at the end in the strip width direction. The edge overcoat prevention electroplating device is characterized in that the edge overcoat prevention electroplating device is arranged opposite to the metal strip. The details of the present invention will be explained below based on embodiments shown in the drawings.

FIG. 1 shows a specific example of an electrolytic device for carrying out the present invention.
FIG. 2 is a schematic diagram illustrating an example.

In FIG. 1, 1 is a box-shaped electrolytic cell with a liquid reservoir 2 at the bottom, 3 is a plurality of conductor rolls for guiding and energizing the strip, and 5 is placed at upper and lower positions in the electrolytic cell 1.
are electrode pads arranged almost symmetrically across the strip 4 between the upper and lower conductor rolls 3.

6 in the figure is a pump. FIG. 2 is an enlarged view showing one example of an electrode pad, in which an electrolyte spray nozzle 7 is bored in the front surface facing parallel to the strip 4 of the electrode pad 5, which is formed entirely in the shape of a hollow box. There is. Therefore, when an electrolyte is supplied inside the electrode pad 5 and injected from the nozzle 7 toward the strip, the electrolyte flows, for example, as shown by the arrow in FIG. Since static pressure is generated and the pair of pads are facing each other, static pressure is generated on both sides of the strip 4, so the strip is stably held between the pads, preventing vibration and correcting shape defects. Ru.

On the other hand, if the front surface 14 of the electrode pad 5 facing the strip 4 is given properties as an electrode, the space between the pad 5 and the strip 4 is filled with electrolyte, and electrolytic treatment is performed on the strip surface. The desired plating layer is produced.

According to the electrolytic device constructed as described above, since the conductor rolls 3 can be provided above and below the electrode pads 5, the strip resistance during energization is reduced, and the strip is stably maintained by the injected electrolyte. Since the electrolyte flow rate between the strip and the electrode is high, a fresh solution is always supplied, and ions are supplied and diffused sufficiently. The gas generated during electrolysis is efficiently removed by the electrolytic solution successively supplied from the pad, so the current density can be greatly increased at low voltage, allowing for efficient electrolytic treatment.

The electrolyte near the ends flows towards the ends of the strip, and the objective can be achieved by entraining the gas in this region and at the ends targeted by the edge overcoat. The above example shows an example in which a static pressure electrode pad is installed in a vertical electrolytic cell, but the present invention also applies to cases where a dynamic pressure electrode pad is used, a case where a static pressure or dynamic pressure pad is used in a horizontal electrolytic cell, etc. can be similarly applied.

However, from the viewpoint of stably supporting the strip and sealing the electrolyte between the electrode and the strip, a hydrostatic electrode pad is more preferable. The present invention provides a nozzle hole (hereinafter referred to as an electrolyte injection hole) for injecting an electrolyte onto the surface of an electrode pad of such an electrolytic device, and a nozzle hole for injecting a gas or an electrolyte containing gas (hereinafter referred to as a gas injection hole). As a result, by injecting electrolyte onto the metal strip surface and performing electroplating while injecting gas or electrolyte containing gas near the end of the metal strip surface. It is possible to prevent edge overcoat and produce a galvanized steel plate with a uniform coating amount.

The structure of the electrode pad of the present invention and its effects will be explained below with reference to the drawings.

First, a method for preventing edge overcoat of plating using fluid holding electrodes that applies static pressure between the electrodes when plating a strip while spraying an electrolytic solution between the electrodes will be explained.

A plan sectional view of the electrolyzer in this case is shown in FIG.

A fluid retaining electrode 5 is disposed opposite the strip 4, and a similar electrode (not shown) is also disposed opposite the strip 4 on the opposite side of the strip 4. The electrode 5 is hollow, and when plating liquid is supplied from the electrolyte supply pipe 11, the plating liquid is injected from the electrolyte injection hole 7 and flows as shown by the arrow, creating a static pressure P between the electrode surface 14 and the opposite electrode strip 4. occurs, and electrolysis can be performed while stably holding the strip.

In such an electrode, the present invention is characterized by a method and apparatus for injecting gas or an electrolytic solution containing gas from the end of the electrode to the vicinity of the end of the strip.

That is, a gas injection hole 8 connected to a gas or an electrolyte supply pipe 13 containing a gas is provided at the end of the electrode corresponding to the end in the width direction of the strip, and a gas or a gas containing the gas is provided through the gas injection hole 8. When the electrolyte is injected, a gas-liquid mixed flow 10 of the plating liquid injected from the electrolyte injection port 7 of the electrode 5 and the injected gas is formed, which is injected near the end of the strip 4 and flows out in the direction of the arrow. . Injecting the gas-liquid mixture only near the ends of the strip in this way reduces the electrical conductivity of the gas-liquid mixture during electrolysis. It can be prevented. In addition, a plurality of gas injection holes 8 are provided at the widthwise ends of the electrodes corresponding to the widthwise ends of the strips, and by adjusting the gas jetting from these gas outlets, the strip facing the electrodes is heated. It can accommodate positional variations or strip width variations. For example, when dealing with variations in board width, if the strip width is narrow, the gas injection holes are closed in order from the extreme end of the electrode, and only the gas injection holes located near the ends of the strip are opened. On the other hand, if the strip width is wide, this can be dealt with by closing the gas injection holes in order from the center of the strip and opening only the end gas injection holes located near the ends of the strip. .

The above-mentioned gas injection amount can be adjusted using the on-off valve 9 as shown in Fig. 3.
In addition to the method of moving the strip width in the direction of the force, it can be arbitrarily adjusted by opening/closing with a solenoid valve or in other known directions. Next, a method for preventing edge overcoating in plating using fluid holding electrodes that applies dynamic pressure between the electrodes when plating a strip while injecting an electrolytic solution between the electrodes will be described.

FIG. 4 shows a plan sectional view of the electrolyzer.

Electrode pads 5 are arranged on both sides facing the strip 4, and a plating liquid is sprayed from the liquid jet hole 7 provided on the surface of the electrode pad facing the strip to stably hold the strip by dynamic pressure. Electrolysis can be performed.

The present invention is also characterized by a method and apparatus for injecting gas or an electrolytic solution containing gas from the end of the electrode to the end of the strip in such an electrolytic device.

In FIG. 4, plating liquid injection holes 7 are provided on the surface of the electrode pad 5 facing the strip, extending in the width direction of the strip, and both are connected to a plating liquid supply pipe 11. The liquid is injected to form a liquid stream 12. Furthermore, a gas supply pipe 1 is connected to a gas pressure cutter 16 at a plurality of gas injection holes 8 located at the ends of the electrodes corresponding to the ends in the width direction of the strip.
Gas is injected by supplying gas from 5. This gas is injected near the end of the strip and the gas-liquid mixture flow 1
0 is formed and the conductivity during electrolysis is reduced, so edge overcoating of plating can be prevented.

Furthermore, by controlling the gas ejection from a plurality of gas injection holes 8 provided in the width direction of the anode end by arbitrarily opening and closing the gas on-off valve 17 provided in the gas supply pipe group 15, the strip facing the electrode is controlled. As in the case of the electrolytic method, edge overcoat can be effectively prevented in response to variations in the position of the strip or variations in the width of the strip.

Furthermore, in this electrolyzer, instead of the gas injection hole 8, a gas injection nozzle connected to the gas supply pipe 15 is provided inside the end of the electrode pad, and the electrolytic solution containing gas is injected from the injection hole 8. You can also do it.

Further, other examples of electrode pads used in the present invention will be explained.

As shown in FIG. 5, it is also possible to provide a chamber 18 or 19 inside the pad 5 that is connected to the gas injection hole 8 and supplies gas or an electrolyte containing gas. In the case of room 18, it is a small room following gas injection hole 8, and room 1
9 shows a structure in which the inside of the pad is divided into separate rooms. A gas-liquid mixture containing gas is obtained by supplying gas from A to the circulation path B that supplies the electrolytic solution using a known method. In the case of FIG. 6, the hollow part of the electrode pad 5 is divided into a chamber for supplying only the electrolytic solution and a chamber 18 for supplying the gas-liquid mixture. In either structure, the shape of the gas injection hole can be determined by the structure of the electrode pad, electrolytic conditions, fluid conditions, etc.

Further, as a mixing method in the case of a gas-liquid mixture, gas is supplied from a part of the circulation system by a known method.

For example, gas is supplied before the suction port of a circulation pump, and a fine gas-liquid mixture is obtained by the pump. Alternatively, a method of generating gas by directly introducing pressurized gas or supplying an electrolytic solution in which gas is dissolved under pressure can be applied. The electroplating method and device for preventing edge overcoating according to the present invention have been described above. However, the present invention also relates to an electroplating method in which a strip is passed through a strip while an electrolytic solution is injected between counter electrodes in a space. This method is characterized in that plating is performed while injecting gas or an electrolytic solution containing gas to the surface.

The reason why this method was applied to the electrolysis method is that by injecting the electrolyte between the counter electrodes in space, the outflow resistance of the injected electrolyte is small, and the flow rate of the electrolyte is very high, so the liquid replacement is sufficient. It has the advantage that a good plated product can be obtained even when plating is carried out at a high current density, and in particular, it has the advantage that prevention of edge overcoat can be easily controlled.

In other words, in the conventional method of electroplating with the strip immersed in an electrolytic solution, in which gas is injected at the end of the strip, the injected gas rises due to buoyancy, so it may rise depending on the flow state of the electrolytic solution. As the edge overflows, it may float toward the center of the strip, and it is not always sufficient to control the injection of uniform gas corresponding to a portion of the edge over. On the other hand, in the present invention, the direction of the plating liquid injected from the electrode surface facing the strip is always controlled from the center of the strip to the front and back of the strip traveling direction, or to both ends of the strip. By injecting gas at the end of the strip in the outflow path, it is possible to control the amount of edge overcoat in the target area at all times.

As explained above, the present invention was developed with an eye to the fact that the presence of air bubbles in the electrolytic solution reduces the current conductivity. The following effects can be obtained by electroplating using an electrolytic device having an electrode provided with a nozzle hole for spraying an electrolytic solution.

(1) Edge overcoating of plating can be easily prevented by controlling the injection of air bubbles only near the ends of the metal strip during electroplating.

(2) It is a compact electrolysis device with an electrode having an electrolyte injection hole and a gas injection hole on the electrode surface, and has good workability.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram illustrating the state in which the electrode of the present invention is arranged in an electrolysis device, Fig. 2 is an enlarged view of an example in which the electrode of the present invention is arranged opposite to a metal strip, and Fig. 3 is a schematic diagram illustrating the electrode of the present invention disposed opposite to a metal strip. Figures 4, 5, and 6 are diagrams explaining one example, and Figures 4, 5, and 6 are diagrams explaining other examples of the present invention. 1... Electrolytic cell, 2... Liquid reservoir, 3...
...Conductor roll, 4...゛...゛Metal strip, 5...゜...゛Electrode pad, 6...Pump, 7...Electrolyte injection hole, 8... ... Gas injection hole, 9 ... Gas or gas-liquid intake opening/closing valve, 10 ... Gas-liquid mixed flow, 11 ......
Electrolyte supply pipe, 12...Liquid flow, 13
...Gas or gas/liquid inlet, 14...
... Electrode surface, 15 ... Gas or gas-liquid supply pipe,
16... Gas or gas-liquid pressure pipe, 17.
...Gas or gas-liquid on-off valve, 18...
Gas or gas-liquid supply chamber, 19... Gas or gas-liquid supply chamber.

Claims (1)

[Scope of Claims] 1. Electricity is supplied while the metal strip is traveling in a space without being immersed in the electrolytic solution, and while the metal strip is being held, an electrolyte is injected from an injection hole provided on an electrode surface facing the metal strip. In the plating method, a gas or an electrolytic solution containing gas is injected near the end of the metal strip surface facing from the end of the electrode surface, and at any position in the outflow path where the electrolyte flows toward the end. An electroplating method for preventing edge overcoat, which is characterized by electroplating. 2 A gas injection hole is provided to inject a plurality of gases or an electrolyte containing gas in a direction corresponding to the width of the metal strip at the end of the electrode, and electricity is generated while arbitrarily controlling the amount injected from the gas injection hole. A method of plating according to claim 1. 3 Injecting the electrolytic solution onto the electrode surface in an electroplating device that supplies electricity while injecting the electrolytic solution from an injection hole provided on the electrode surface placed opposite the metal strip while holding the metal strip in a space without immersing it in the electrolytic solution. and a gas injection hole for injecting gas or an electrolyte containing gas, and the gas injection hole for injecting gas or an electrolyte containing gas is located at the end in the width direction of the strip. An electroplating device for preventing edge overcoat, characterized in that an electrode is placed facing a metal strip.