JPS6055598B2 - Edge bar coat prevention device in radial cell type plating tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an edge overcoat prevention device in a radial cell type plating tank. This aims to effectively prevent abnormal adhesion of.

In a radial cell type plating device, a large-diameter rotating drum for conducting electricity is immersed in a plating solution for approximately 1 hour, and a metal strip (hereinafter simply referred to as a strip) is brought into contact with the outer periphery of the rotating drum and runs in synchronization with the rotation of the drum. This is an electroplating apparatus that conducts current through the plating liquid between the strip and an anode installed across a radial current supply gap from the strip. Due to its structure, this plating device is suitable for plating only one side, and since the conduction gap, that is, the distance between the conductive strip and the anode surface can be made small, wasteful consumption of plating power is reduced. high-speed plating with large current is possible. Generally, in this type of electroplating,
There are cases where an insoluble electrode is used as an anode, and cases where a soluble electrode whose main component is the metal to be plated is used.
In particular, when using the latter soluble anode, it is easy to replenish the metal to be plated, and there are advantages such as less gas generation on the electrode surface, so it is particularly suitable for thick plating where a large current is applied. It is considered a method.

However, with this method, the anode wears out as plating progresses, so if the plating work continues, the current gap will gradually increase, and the electrical resistance of the plating liquid will increase accordingly, resulting in a reduction in the plating power. Since the consumption increases, it is necessary to appropriately correct the variation in the current carrying gap as the anode wears out.

Therefore, in radial cell plating using soluble anodes, as shown in Figs.
'', a plurality of arcuate anode pieces 2 are arranged side by side, and the strip 3's immersion path is divided into two, front and back, and placed opposite each other.
While each arcuate anode piece 2 is sequentially fed in the width direction along the anode supports 5, 5'' which extend approximately parallel to the generatrix of the rotating drum 4, depending on the degree of wear of each anode 1, 1''. The energization gap g is corrected by replenishing and removing the current.

That is, each arcuate anode piece 2 has an arcuate shape along the outer periphery of a rotating drum (not shown), with its inner surface 2a facing the rotating drum, as shown in typical examples in FIGS. 3A, b, and c. A locking protrusion 2c is provided on the back surface 2b of the electrode surface, and the locking protrusion 2c is hooked onto the anode support 5 so that the distance between the poles between the electrode surface and the outer periphery of the rotating drum can be maintained evenly. is being used.

Further, the anode support 5 is arranged such that the distance between it and the rotating drum gradually narrows in the direction of movement of the arcuate anode pieces, and while each arcuate anode piece is moved laterally, new anode pieces are formed at both ends of the anode. By replenishing the anode and taking out the used anode, fluctuations in the current carrying gap due to anode wear are corrected. It is said that the mechanism is such that it can face the strip of By the way, in general, in electroplating, abnormal adhesion of metals due to the concentration of electrolytic current at both edges of the strip called edge overcoat has been a problem, and in this respect, radial cell type electroplating is Although the degree of damage is relatively mild, because this type of plating is performed with a high current density while the strip is being passed through at high speed, the electrolytic current is concentrated at both edges of the strip, especially at its extreme end. is difficult to ignore, and the occurrence of edge overcoat cannot be avoided, especially when plating is performed at a high current density.

If the current concentration at both edges of the strip is larger than that at the center, even if there is still some margin for the current density at the center, the current density at both edges approaches or exceeds the allowable limit, resulting in a black color known as burnt. Sponge-like electrodeposition had occurred. This edge defect did not pose a particular problem when consumers cut off both edges of the strip, but it became a serious problem for consumers who used both edges.

Therefore, if there is a risk of edge defects as described above occurring, it has been necessary to reduce the total supply current to alleviate the concentration of electrolytic current at the edge in order to avoid the occurrence. This led to a reduction in the strip threading speed, resulting in a decrease in work efficiency.

) The present invention advantageously solves the above problem by advantageously preventing the concentration of current at the edges of the strip without reducing the current input, i.e. without reducing the current density. The present invention proposes a device useful for effectively preventing the occurrence of edge overcoat.

That is, the present invention introduces a metal strip that is in contact with the outer periphery of a rotating energizing drum and runs in synchronization with the rotation of the drum with a soluble anode that separates a radial energizing gap from the metal strip into the gap. In a radial cell type plating device that performs plating by applying current through a plating liquid, the plating liquid penetrates into the current-carrying gaps from both sides of the current-carrying rotating drum in the plating liquid tank, covers the lower half of the rotating drum, and coats the metal. A semi-cylindrical edge mask that avoids concentration of electrolytic current density at both edges of the strip is provided integrally with a cover that has the same curvature as the edge mask and covers the upper half of the rotating drum; A plurality of guide rollers that use the outer circumferential surface of the rotary drum as a guide are attached to the cover, and the edge mask is installed so as to be movable forward and backward in parallel to the generatrix direction of the energizing rotary drum. It is something to do.

The cause of edge overcoat is thought to be as follows.

That is, the relationship between the strip and the anode surface in the radial cell type plating apparatus is such that the width of the anode surface is larger than the width of the strip 3, as shown in FIG. 4, and the current conduction gap g is extremely narrow. Therefore, during electrolysis, the electrode surface 1a in the area exceeding the strip width as shown by the arrow in the figure
The plating current from the strip wraps around considerably, resulting in abnormal adhesion of the plating metal to both edges of the strip. In order to solve the above problem, it may be possible to increase the current conduction gap, but this method increases the plating power consumption, so it is difficult to say that it is an appropriate countermeasure.

Therefore, in the present invention, a baffle plate or an edge mask is inserted near both edges of the strip to advantageously cut off the wrapping of the plated metal around the edges of the strip.

In this way, abnormal plating adhesion at both edges of the strip is completely prevented, and variations in the width of the strip can also be advantageously dealt with by installing the edge mask so that it can move forward and backward in the width direction. Preferred embodiments of the present invention will be described in detail below.

In the preferred embodiment of the present invention shown in FIGS. 5 and 6, the main structure of the radial cell is the same as that of the conventional example shown in FIGS. , number 6 is an edge mask.

This edge mask 6 has a semi-cylindrical shape and is inserted into the current carrying gap g between the outer periphery of the rotating drum 4 and the anode surface of the soluble anode 1 in the plating solution. Furthermore, this edge mask 6 is made of two guide rods 8, 8'' which pass through the side wall of the plating liquid tank and run parallel to each other via an Ω-shaped connecting rod 7 as shown in FIG. and a busher 9. By driving this busher 9, the edge mask 6 can freely move forward and backward along the axial direction of the rotating drum 4, and is supported by guide rods 8, 8''. This prevents contact and damage to the anode surface or strip during forward and backward movement, and also effectively prevents sideways wobbling due to rotation of the rotating drum. By the way, to completely prevent edge overcoat,
The mask angle θ shown in FIG. 8 is a very important factor.

In other words, when this mask angle θ becomes smaller, the plating thickness at the strip edge becomes thinner than that at the center, and conversely, it becomes impossible to completely prevent large edge overcoat, so the mask angle θ must be controlled to an appropriate value. It is important to do so, and the appropriate angle is usually about 45 degrees. Therefore, A'-B is required in the area shown in Figure 8, but simply inserting the edge mask into the current-carrying gap will prevent the plating solution from flowing as the strip passes through the strip at high speed. Since the edge mask vibrates due to the strong flow, it is difficult to always maintain the mask angle 0 at an appropriate angle, and in extreme cases, there is a risk that the edge mask will come into contact with the strip and cause surface flaws. Therefore, in this invention, as illustrated in FIGS. 5 and 6, the upper end of the semi-cylindrical edge mask 6 is provided with the same curvature as the edge mask 6 at a position where the strip cannot be prevented from running even when moving forward and backward. A cover 10 covering the upper half of the rotating drum 4 is attached integrally, and this cover 10 and an edge mask 6 are attached together.
A plurality of guide rollers 11 (in this example, two guide rollers 11 at equal intervals on the cover 10 and the edge mask 6, eight in total) are arranged inside the ring formed by the rotating drum 4 as a guide. It is.

With this structure, the edge mask can always move forward and backward in parallel to the generatrix direction of the rotating drum, so that the edge mask 6 can move toward the anode 1 or the strip 3 not only when moving the edge mask 6 but also during electrolytic treatment. Needless to say, contact with the mask can be avoided, and fluctuations in the mask angle can be effectively suppressed. Therefore, a spherical roller as shown in FIG. 9a is particularly advantageously suitable as the guide roller 11, but a cylindrical roller as shown in FIG. 9b may also be used. However, when using cylindrical rollers, in order to reduce the frictional resistance with the rotating drum during electrolysis,
It is desirable that the cylindrical roller axis be arranged parallel to the rotating drum axis. As edge masks and covers, plastics such as hard vinyl chloride and polypropylene are advantageously suitable because they need to be lightweight and have excellent resistance to corrosion by plating liquid and electrical insulation.

Thus, according to the present invention, in radial cell type electroplating in which plating is performed at high current density under high-speed sheet passing,
Edge overcoat, which conventionally was considered inevitable to occur on both edges of the strip, can be completely prevented without reducing work efficiency, greatly contributing to improved product quality.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views of typical radial cell plating equipment, Figures 3A, b, and c are front, side, and plan views of the soluble anode, respectively, and Figure 4 shows the occurrence of edge overcoat. 5 is a cross-sectional view of the preferred embodiment of the present invention, FIG. 6 is a partially cutaway view thereof, FIG. 7 is a side view thereof, and FIG. 8 is a procedure for inserting the edge mask into the current carrying gap. FIGS. 9A and 9B are diagrams showing guide rollers, respectively. 1... Anode, 2... Arcuate anode piece, 3.
...Strip, 4...Rotating drum, 5
... Anode support, 6 ... Edge mask, 7 ... Connection rod, 8 ... Guide rod, 9 ... Busher 10 ... ····cover.

Claims (1)

[Claims] 1. A metal strip that is in contact with the outer periphery of the energizing rotating drum and runs in synchronization with its rotation is placed between a soluble anode that separates a radial energizing gap from the metal strip,
In a radial cell type plating device that conducts plating by applying electricity through the plating liquid introduced into the gap, the plating liquid enters the current-carrying gap from both sides of the energizing rotating drum in the plating liquid tank, and the plating liquid enters the current-carrying gap below the rotating drum. A semi-cylindrical edge mask that covers half the circumference and avoids concentration of electrolytic current density at both edges of the metal strip is provided integrally with a cover that has the same curvature as the edge mask and covers the upper half of the rotating drum. , and a plurality of guide rollers that use the outer peripheral surface of the rotating drum as a guide are attached to the edge mask and the cover, and the edge mask is installed so that it can move forward and backward in parallel to the generatrix direction of the energizing rotating drum. An edge overcoat prevention device in a radial cell type plating tank characterized by: