JPH0421824Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Field of industrial application) This invention is based on Zn plating and Ni plating of the strip.
This invention relates to an insoluble anode type continuous electroplating device commonly used for electroplating various alloys such as -Zn and Fe-Zn, and particularly relates to improvements in an electroplating device equipped with a jet nozzle for forcibly injecting plating liquid between anodes.

(Prior Art) Currently, as a continuous electroplating device for strips, for example, as shown in FIG.
A commonly used type of device is one in which a strip (cathode) S is passed between 2 and 2, and the plating metal in the plating liquid is electrically broken onto the surface of the strip during the passing process. It has become common practice to provide a jet nozzle 3 for forcibly injecting plating liquid between the electrodes 2 in a countercurrent or forward direction with respect to the direction in which the strip passes. The purpose of the jet nozzle is to first of all force the plating liquid between the electrode 2 and the strip S (hereinafter referred to as the gap) to accelerate the renewal of the plating liquid and reduce the thickness of the boundary layer near the strip interface. The aim is to improve the critical current density by reducing the current density. The limiting current density is the limit plating current value that can maintain good plating quality without causing abnormal deposits such as so-called burns and burnt. Increasing this density is important not only in terms of quality but also in the production process. This is also useful for increasing the capacity of the equipment and speeding up the line, in other words, improving production capacity.

The jet nozzle also quickly expels O ₂ gas generated on the electrode surface 2' and H ₂ gas generated on the strip surface during the plating operation from the electrode gap C, lowering the electrical resistance between the electrodes and lowering the plating voltage. In other words, one aim is to improve power efficiency.

(Problems to be Solved by the Present Invention) Generally, in electroplating devices including this jet nozzle combination type, the strips S and the strips S and 2 are provided on the strip-opposing surfaces (electrode surfaces) 2' and 2' of the electrodes 2, 2, respectively. spark prevention plate 4 to prevent direct contact with
It is customary to install 4. Strips usually flap considerably during threading due to poor flatness or curling during winding.
The purpose of the spark prevention plate is to prevent contact between the strip S and the electrode 2 due to this flapping. When the slit tip and the electrode come into contact, sparks will fly between them and cause major damage to both.

The spark prevention plate 4 is normally provided with a plurality of rows of flat plates made of an insulating material such as Bakelite, spanning the entire width of the electrode 2, as shown in FIG.

However, if such a spark prevention plate 4 is present, even if the jet nozzle 3 is used, the effect will not be as high as expected. In other words, in electroplating, the smaller the distance e between the electrodes, the more advantageous it is in terms of power efficiency.For this reason, recently, so-called close electrolysis, in which the distance e between the electrodes is set extremely small, has been practiced. However, especially in the case of such close electrolysis, the spark prevention plate 4 greatly impairs the effectiveness of the jet nozzle 3. That is, the spark prevention plate 4 running in the electrode width direction obstructs the flow of the plating liquid blown from the jet nozzle 3, reduces its flow velocity, and allows some of it to escape in the electrode width direction. This results in an uneven flow velocity distribution of the plating liquid. Non-uniform flow velocity distribution in the gap between electrodes is a problem, especially when electroplating alloys such as Ni-Zn and Fe-Zn, as it causes uneven plating.

In particular, in a device using a horizontal plating tank (hereinafter referred to as a horizontal plating device), even if a blowing operation using the jet nozzle 3 is performed, the upper electrode 2
The spark prevention plate attached to ₁ (hereinafter referred to as the upper spark prevention plate) 4 ₁ The gas O ₂ and H ₂ generated between the poles are trapped in the blind spot behind 1, that is, the area where the effect of plating liquid flow does not reach. Accumulated g
will occur. Such a gas pool g disables the corresponding electrode surface and causes the plating electrode to rise. For this reason, especially in the case of a horizontal plating device, it is difficult to expect a significant improvement in electrode efficiency by using a jet nozzle. .

The present invention aims to solve the above-mentioned problems by improving the spark prevention plate to minimize the unevenness of the flow velocity distribution of the inter-electrode plating liquid due to this, and to prevent gas accumulation due to the upper spark prevention plate. The aim is to eliminate this occurrence as much as possible.

(Means for solving the problem) That is, the plating device of the present invention is a plating device combined with a jet nozzle, and the spark prevention plate 5
For example, as shown in FIG. 1, the electrode is divided into a plurality of pieces in the width direction of the electrode, and the plurality of divided pieces 5 ₁ are arranged so as to be displaced back and forth in the strip threading direction so as not to be adjacent to each other. do.

(Function) The spark prevention plate 5 based on the present invention allows the blowing flow from the jet nozzle 3 to pass through both sides of each divided piece 5 ₁ ... in the electrode width direction as in the conventional case. Escape to is effectively prevented. Therefore, by adopting this method, the flow velocity distribution of the plating liquid between the electrodes can be made as uniform as possible even in the case of close electrolysis, and the problem of uneven plating deposition in alloy electroplating can be effectively solved. be.

In addition, in the case of this spark prevention plate 5, there is no large blind spot behind it as in the conventional case, and therefore the generation of gas accumulation due to the upper spark prevention plate is effectively reduced, thereby improving power efficiency. can be expected.

In terms of power efficiency, the spark prevention plate 5 based on the present invention has the following advantages over the conventional one.

That is, with the spark prevention plate structure based on the present invention, it is possible to secure the same function as the conventional two-row arrangement of spark prevention plates 4, for example, with a two-row staggered arrangement as shown in FIG. In the staggered row arrangement, if the length l of the divided pieces 5 ₁ . It becomes half. In other words, in the spark prevention plate 5 based on the present invention, the shielding area is reduced by half compared to the conventional one, and this can also contribute to improving power efficiency as in the case of the gas reservoir g.

Here, regarding the spark prevention plates based on the conventional and the present invention described above, the effective area A of the electrode surface 2' is
(Based on the spark prevention plate and the gas accumulation g caused by it) is compared and calculated by giving specific numerical values, and the result is as follows.

[Electrode and spark prevention plate specifications]

・ Electrode: 2000 mm width x 800 mm length (standard size) ・ Spark prevention plate: Conventional type and one based on this invention = 35 mm [For conventional spark prevention plate] Length of gas reservoir g d = 1.5 l ( Plating liquid flow rate between electrodes
1 to 2 l at about 0.5 m/sec), A = 2000 x (35 + 35 + 1.5) x 2 = 350 x 10 ³ (mm ² ) [In the case of the spark prevention plate based on the present invention] d = 0.5 l (between poles) Plating liquid flow rate: 0.5l or less (same as above)
As, A = 2000 × (35 + 35 × 0.5) = 105 × 10 ³ (mm ² ) In the case of this invention, the ineffective area A is only 30% of the conventional one, and if you look at this in terms of effective area, it is an increase of 20%, The improvement in power efficiency resulting from this is enormous.

(Example) Divided piece 5 of spark prevention plate 5 based on the present invention ₁
The most basic arrangement is the two-row staggered arrangement shown in FIG. 1 above. In other words, the single spark prevention plate 4 that spans the entire width of the conventional spark prevention plate 4 is divided into an appropriate number (nine in the illustrated example) in the width direction, and the divided parts are alternately shifted in the front and rear directions. The number of divisions (the number of division pieces 5 ₁ . . . ) is preferably increased as much as possible within a range in which each division piece has an appropriate shape as described below.

Various other variations are possible for the arrangement, some of which are shown in Figures 2A and 2D. That is, the arrangement is conceptually based on the conventional one or more spark prevention plates 4 spanning the entire width, divided as described above, and each divided piece is displaced in the front and back direction. Just think of the possible shapes. However, in either case, the divided pieces 5 ₁ ... should not be adjacent to each other, but should maintain an appropriate distance L (the distance between adjacent pieces when viewed in the width direction) from front to back. The above-mentioned interval L has an important meaning in order to guide the plating liquid as smoothly as possible without impairing the uniformity of the flow, and from that point of view, it should be at least 2 x l or more. is recommended.

It should be noted that the arrangement should be such that the total sum of the lengths l of the divided pieces in each part is constant in the width direction, which is natural from the above-mentioned viewpoint. This makes the length of the effective folding surface of the electrode, that is, the length of the part not covered by the divided pieces 5 ₁ . It's for a reason.

As mentioned above, there are many possible arrangements that satisfy the conditions of the present invention. However, when applying the present invention, it is necessary to determine the arrangement according to the equipment conditions such as the size of the electrodes, the distance between the electrodes, the flow rate of the plating liquid between the electrodes, etc. An appropriate one may be selected and used from among them, taking into account the spark prevention function of the spark plug.

Divided piece 5 ₁ ...For each piece, the planar shape is basically rectangular, and its width W and length l are as follows.
From the viewpoints of strength against collision with the strip, attachment to the electrode surface, and reduction of the ineffective area of the electrode surface, it is preferable that w=10 mm or more and l=about 10 to 50 mm, respectively.

The thickness t (see Fig. 3A) is preferably at least 1 mm or more in order to maintain the original spark prevention function, and preferably 10 mm or less in consideration of the effect on the flow of the interplating liquid.

Needless to say, the material of the divided pieces is an insulating material, and they may be attached to the electrode surface by any means such as adhesive, screwing, or fitting.

Regarding the end faces 50 and 51 of the divided piece 5 ₁ ...,
Although it is of course possible to have a right-angled shape as shown in FIG. 3A, it is especially advantageous for the front-rear end face 50 to be tapered or arcuate as shown in FIG. 3A to D. This depends on the size of the gas pocket g that forms behind the spark prevention plate (divided piece) of the upper electrode during operation. In other words, in the case of the conventional spark prevention plate 4 (end face perpendicular) spanning the entire width of the electrode, the size of the gas reservoir g (length in the front-rear direction) d is determined by the plating liquid flow rate.
At 0.5 mm/sec, it is about 15 to 20 mm, but on the other hand, for the spark prevention plate 5 with the split structure described above, under the same conditions, the values for each end face shape shown in Fig. 3 are approximately the same as those shown in the same figure. . End face perpendicular (third
As shown in Figure A, the effect of reducing gas accumulation is obvious compared to the conventional one, but the effect is even more pronounced with tapered end faces and arcuate end faces, and especially in the case of arcuate end faces, there is almost no gas accumulation. In the case of a tapered end surface, the smaller the taper angle θ, the higher the effect. Tapered end faces and arcuate end faces are also effective in ensuring smooth flow of plating liquid.
From this point of view, it is highly recommended.

Next, we will show concrete results regarding the implementation effects of this invention. A plating device using a jet nozzle using a horizontal plating tank (electrode size: 2000 mm x 1000 mm, line speed: 80 m/min, jet nozzle jet flow rate: 1
m ³ /min), the fourth
The l, t, and L (distance between rows) shown in the figure are each 30 mm,
Conventional spark prevention plates 4 arranged in two rows of 5 mm and 600 mm, and w, l, shown in Fig. 1 and Fig. 3 A,
We tried the spark prevention plate 5 of the present invention in a two-row staggered arrangement with t and L of 50 mm, 30 mm, 5 mm, and 600 mm, respectively. The results were as follows.

・ When performing alloy plating (Ni-Zn system, Fe-Zn system), when we reduced the inter-electrode distance e to 20 mm and applied proximity electrolysis, the uniformity of the inter-electrode plating liquid flow was greatly impaired in the conventional example, resulting in poor product quality. Although significant depositing unevenness was observed in the plated plate, there was no such depositing unevenness at all in the example of the present invention, and a homogeneous plated plate was obtained. Incidentally, in both the conventional example and the example of the present invention, no spark was observed due to contact of the electrode strips.

・ In this case, the plating voltage (current density:
80A/dm ² ) required 16.5V in the conventional example, but
In the present example, only 14.4V was required, and the power efficiency was improved by 13%. This effect is due to the reduction of the electrode ineffective area due to the gas accumulation g caused by the spark prevention plate and the upper spark prevention plate.

- In addition to the above, in the present example, the thickness of the boundary layer at the strip interface is reduced compared to the conventional example,
An improvement in limiting current density was also observed. Regarding this point, it is thought that the spark prevention plate having a split structure as in the present invention provides appropriate agitation to the plating liquid flow.

Although all of the above explanations have been made regarding the case of a horizontal plating device, the spark prevention plate structure based on the present invention can of course be similarly applied to a vertical plating tank type plating device.

(Effects of the invention) As is clear from the above detailed explanation, by adopting the spark prevention plate structure based on the present invention, the concealed area of the electrode can be reduced, and gas accumulation between the upper electrodes in a horizontal plating tank can be reduced. Not only can a large reduction in electric power consumption in plating operation be achieved, but also the uniformity of the interpolar plating liquid flow based on the jet nozzle blowing can be effectively improved. In particular, it is possible to prevent uneven plating in alloy electroplating, and therefore the present invention has extremely high industrial utility value.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the electrode surface of the upper electrode showing the most basic example of the arrangement of the divided pieces of the spark prevention plate according to the present invention, and FIGS. Figure 3 shows an example of
Figures 1 to 2 are side views showing various examples of the end shape of the divided piece as above, Figures 4 and 4 are side views and side views of the electrode surface of the upper electrode showing a conventional spark prevention plate, Figure 5 The figure is an explanatory diagram showing the general structure of a jet nozzle combination type plating device (horizontal plating device). In the figure, 1... plating tank, 2... electrode, 3... jet nozzle, 4... conventional spark prevention plate, 5...
Spark prevention plate based on the present invention, 5 ₁ ...divided piece.

Claims (1)

[Scope of utility model registration request] This is a plating device in which plating liquid is blown from a jet nozzle 3 in a countercurrent or forward flow with respect to the strip passing direction between a pair of insoluble anodes 2, 2, which are disposed facing each other across the strip S passing line in a plating tank 1. An insulating spark prevention plate 5 is provided on the side of the insoluble anode facing the strip to prevent direct contact with the strip, and the spark prevention plate 5 is divided into a plurality of parts in the width direction of the anode. An electroplating device characterized in that the divided pieces 5 ₁ are arranged so as to be displaced back and forth in the strip passing direction so as not to be adjacent to each other.