JPH0456799A - Plating solution circulating device for continuous electroplating device - Google Patents

Abstract

PURPOSE:To prevent air from being entrained by a plating soln. flowing in a return pipe by dipping the lower end of the return pipe in the plating soln. in a soln. circulating tank and providing a flow control valve at the lower end of the return pipe to fill the return pipe with the soln. at all times. CONSTITUTION:The lower end of a plating soln. return pipe 11 is dipped in the soln. in a lower plating soln. circulating tank 8, and a flow control valve 16 is fixed to its tip. The conical seat and valve of the control valve 16 are formed by the combination with an orifice valve seat 18 provided at the lower end of a case 13. The amt. of the soln. to be returned is automatically controlled by the control valve 16 in accordance with the height of the soln. in the return pipe 11. When the return pipe 11 is not filled with the soln., the control valve 16 is firmly attached to the orifice valve seat 18 from the lower part, and the soln. is returned to the circulating tank 8 only through a small hole 20. The control valve 16 begins to open as the soln. surface in the return pipe 11 is raised.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to plating on the return trip when a surface treatment solution, especially an electroplating solution, etc. is circulated between a plating tank and a plating/liquid circulation tank. The present invention relates to a plating solution circulation device in a continuous electroplating apparatus that prevents deterioration of the solution.

<Prior art> A typical example of circulating a plating solution is disclosed in Japanese Patent Application Laid-open No. 57-198.
As shown in Japanese Patent No. 298, it is as shown in FIG. In FIG. 9, the steel plate 1 is energized when passing between a pair of current-carrying rolls 5 and bank-up rolls 6, and electricity is being applied between the electrodes 4 disposed in the plating solution tank 2 via the dam rolls 7. is electroplated. The plating solution is supplied from the lower plating solution i source 8 to the plating solution tank 2 of the plating apparatus by a circulation pump 9 disposed on the liquid supply pipe IO, and the plating solution 1 overflowing from the plating solution tank 2 is
2, - After the upper plating solution reservoir is stored in the tank 3, it flows down the plating solution return pipe 11 and is collected in the lower circulation tank 8.

The purpose of circulating the plating solution 12 in this way is to supply metal ions for plating to the plating apparatus. Ions are replenished, and by circulating the plating solution 12, a fresh plating solution is constantly supplied to the plating apparatus.

By the way, in recent years, galvanized steel sheets 1 have been increasingly electroplated with iron-based metals to improve paintability, but the plating solution circulation system shown in FIG. The following problems occur. That is, the iron ions (Fe") contained in the plating solution 12 and used for plating are oxidized during the circulation of the plating solution and changed to Fe", which requires extra chemicals to supply [e2]. Moreover, an increase in p e 3 + leads to deterioration in plating quality such as poor appearance.

At present, in order to reduce Fe'' to Fe'', expensive equipment such as an electrolytic reduction device is provided. The main reason for this is that iron ions come into contact with air during the circulation of the plating solution, causing oxidation.

In particular, in the return pipe 11 to the circulation tank 8, the plating solution 1
2 is returned to the circulation tank 8 by gravity from the plating device, so a large amount of air is entrained in the vertical pipe portion of the return pipe 11, and at this time, the problem is that significant oxidation is unavoidable. There is.

<Problems to be Solved by the Invention> An object of the present invention is to provide a device for preventing air entrainment in the plating solution flowing through the return pipe, and thereby preventing oxidation of iron ions in the plating solution, in a plating solution circulation type continuous electroplating device. This is what we propose.

<Means for Solving the Problems> The present invention was achieved as a result of various studies based on the idea that it is effective to fill the return pipe with plating solution to prevent air entrainment. The gist of this is as follows.

In the present invention, the upper plating solution receiver that receives the plating solution overflowing from the plating solution tank is arranged so that the plating solution can be circulated between the tank and the lower plating solution circulation tank that stores the plating solution to be supplied to the plating solution tank. A plating solution circulation device in a continuous plating apparatus connected by a solution return pipe, wherein the plating solution return pipe is provided so that its lower end is immersed in the plating solution in the plating solution circulation tank, and the plating solution return pipe is connected by a plating solution return pipe. The upper plating solution receiver is provided at the lower end of the pipe with a flow control valve that is opened and closed depending on the plating solution level in the tank, so that the plating solution return pipe can always be filled with the plating solution. This is a plating solution circulation device in an electroplating device.

In the plating solution circulation device of the present invention, an orifice valve seat is provided at the lower end of the plating solution return pipe, and an orifice flow rate control valve connected to a guide and having a small hole is provided above. The control valve is provided so that it can be tightly contacted from below the orifice valve seat with a compression coil spring placed between the orifice valve seat and the eastward guide, or the orifice valve is provided with a small hole in the lower end of the plating solution return pipe. It is preferable that the upper plating liquid receiver is connected by a chain to a float placed in the tank and that the flow rate control valve is provided so as to be able to come in close contact with it from above the orifice valve seat. be.

<Function> The flow control valve installed at the lower end of the plating solution return pipe opens and closes the upper plating solution receiver depending on the plating solution level in the tank, so the plating solution return pipe is always kept full of plating solution. . As a result, entrainment of air in the vertical portion of the return pipe is prevented, and oxidation of iron ions in the plating solution can be eliminated.

<Examples> Hereinafter, the structure and operation of the present invention will be explained in detail based on examples.

An embodiment of the present invention will be described based on FIGS. 1 to 3. The feature of the present invention is that the lower end of the plating solution return pipe 11 is immersed in the solution in the lower plating solution circulation tank 8. By installing a flow control valve 16 at the tip of the plating solution return pipe 11, which automatically adjusts the amount of the return liquid according to the liquid filling height in the plating solution return pipe 11,
This is because the return pipe 11 is always filled with plating solution.

Reference numeral 13 denotes a case of a flow rate control I valve 16, which forms a part of the return pipe 11 and is connected to the return pipe 11 by a flange.

The flow control valve 16 is combined with an orifice valve seat 18 provided at the lower end of the case 13 to form a conical seat and a valve. Incidentally, the small hole 20 provided in the flow rate control valve 16 is a liquid discharge hole for draining the liquid remaining in the return pipe 11 when the liquid circulation is stopped. 15 is a guide for operating the flow control valve 16 vertically. Its planar shape is
The guide 15 has a shape as shown in FIG. 3, and has a pressure receiving area of "'A1". 14 is a bolt for connecting the flow control valve 16 and the guide 15.

Further, 17 is a compression coil spring, and the orifice valve seat 18
and the guiding guide 15, and the initial set load (Wc) can be changed by the adjustment slot 9, until the hydraulic pressure acting on the flow control valve 16 reaches the initial set load (Wc). The flow control valve 16 is connected to the orifice valve seat 1.
8 from below. FIG. 4 shows the characteristics of the load W and deflection (δ) of the compression coil spring.

Next, the operation of the device according to the present invention will be explained.

Plating 81 occurs in the return pipe 11 during circulation of the plating solution 12.
Filling the tank 2 means creating a level difference between the liquid level in the lower circulation tank 8 and the liquid level in the return pipe 11, so if a back pressure corresponding to the level difference is applied, good. The present invention focuses on this point, and as described above, attempts to achieve the objective by attaching the flow control valve 16 to the lower end of the return pipe 11.

First, when the return pipe ll is not filled with liquid, the flow rate control valve 16 comes into close contact with the orifice valve seat 18 from below due to the reaction force of the compressed fill spring 17, and returns to the circulation tank 8. The flow rate is only the amount of liquid passing through the small hole 20. The flow rate passing through this small hole 20 is
1 is filled with liquid (i.e., the water head difference is large,
Even in the state where the discharge flow rate is the highest, the amount is very small compared to the circulation flow rate by the circulation pump 9.

Therefore, when the flow rate control valve 16 is closed, there is no ability to discharge all of the circulating flow rate, so the liquid level in the return pipe 11 gradually rises. Accordingly, the pressure received by the flow control valve 16 increases, and when the initial set load (Wc) of the compression coil spring 17 is exceeded, the flow control valve 16 begins to open. When the flow rate control valve 16 opens, the internal pressure of the case 13 between it and the guide guide 15 becomes equal to the pressure applied by the liquid level in the Wi ring tank 8, but instead, the upper surface area of the guide guide 15 increases. A
I" becomes a pressure receiving surface, and the amount of compression of the compression coil spring 17 increases due to the receiving pressure, so as the liquid level in the return pipe 11 rises, the opening degree (L) of the flow rate control valve 16 increases. It gradually becomes larger. In addition, the amount of liquid discharged (Q) also increases accordingly. The relational expression is as follows.

Q=CπDL (2gH)” C; Flow coefficient D; Orifice plate hole diameter L; Valve opening degree (lift 1 g; gravitational acceleration H, liquid filling height. 5 shows the relationship between the liquid filling height (H) of the plating solution 12 and the draining liquid flow rate (Q) of the plating solution 12. In FIG. , H2 indicate the upper and lower limits of the liquid filling height during normal plating solution circulation (see Figure 1).That is, the liquid filling height is Hc.
Until Hc is reached, the flow control valve 16 is closed, so the discharge is only through the small hole 20 provided in the flow control valve 16, but when Hc is exceeded, the flow control valve 16 opens, so the above equation The flow rate Q shown in is discharged, and suddenly plating solution 1
The amount of drained fluid in case 2 will be large. This drainage flow rate characteristic is 1. It is determined by the opening degree L of the flow control valve 1G, that is, the spring characteristics of the compression coil spring 17. Now, assuming that the variation in the circulating flow rate is known, the upper limit H1 of the liquid filling height is the height at which the plating receiver does not overflow the circulating liquid from tank 3, and the lower limit H2.
If the characteristics of the compression coil spring are taken into account so that the height of the return pipe is such that the return pipe is filled with the plating solution, the return pipe 11 can be kept filled with the plating solution 12 at all times.

Next, another embodiment of the present invention will be described based on the drawings. As shown in FIGS. 6 and 7, a flow rate control valve 16' is provided in the return pipe 11, and during the circulation of the plating solution, the upper plating receiver is By controlling the liquid level in the tank 3 to keep it constant, the return pipe 11 is always filled with the plating solution.

21 is a float, and a flow control valve 16' is connected to the lower part of the float via a chain 22 in a hanging manner.

The flow control valve 16' constitutes a conical seat and valve in combination with an orifice valve seat 18'. Incidentally, the plurality of small holes 20' provided in the orifice valve seat 1B' are liquid discharge holes, and the function thereof will be described later.

15' is a guide for vertically operating the flow control valve 16'.

Next, the operation of the device according to the present invention will be explained. Filling the return pipe 11 with liquid during circulation of the plating solution means that the amount of circulating liquid can be discharged while maintaining a constant level difference between the liquid level in the circulation tank 8 and the plating liquid level in the return pipe ll. That means you can do it. The present invention
Focusing on this point, the purpose is to be achieved by equipping the return pipe 11 with a simple device.6 When the return pipe 11 is not filled with the plating solution 12, the float 21 is , the plating liquid receiver is in a state where it has landed in the tank 3, and accordingly, the flow rate control valve 16 comes into close contact with the orifice valve seat 18' from above due to its own weight, and the amount of liquid returning to the circulation tank 8 is controlled by the small hole. 20'. The diameter and number of the small holes 20' are determined as follows. That is, the discharge flow rate (Q6) through the small hole 20' is determined by the following formula based on the difference (H) between the liquid level in the tank 3 and the circulation tank 8 in the plating liquid receiver, as in the previous embodiment. It is.

Qa = Ca 'A++' (2・g−H)
0・'Cd; Flow coefficient A4 i Small hole cross-sectional area table 1↑−π/4・d”−n(n;
(number of small holes) g; gravitational acceleration H; liquid filling height Here, in the device according to the present invention, the total cross-sectional area of the small holes (A4) is determined so that Q4 is a slightly smaller flow rate than the circulation flow rate by the circulation pump 9. ing. By discharging most of the circulating flow through this small hole 20' and reducing the flow rate adjustment range by opening and closing the float-type flow control valve 16', the flow control valve 16' is able to follow the 8-ring flow rate fluctuation. The purpose is to improve. Also, the 8th
When handling different types of plating solutions in the Plating Solution V8 ring device, quality problems may occur if the solutions mix with each other, so it also serves to drain all the solution remaining in the return pipe when the solution circulation is stopped.

Therefore, when the flow rate control valve 16' is closed, there is no ability to discharge all of the circulating flow rate, so the return pipe ll
Inside, the liquid level will gradually rise.

Finally, the liquid exceeds the upper end of the return pipe 11 and the plating liquid receptacle accumulates in the lower part of the tank 3. Accordingly, the pressure received by the upper surface of the flow control valve 16' increases due to the hydraulic pressure caused by the liquid level difference "H", but on the other hand, the float 21 gradually becomes submerged in the liquid. This results in a buoyant force that tends to lift the flow control valve 16'. The buoyant force is the downward load, that is, the receiving pressure on the flow control valve 16', the chain 22, the guide 15', and the flow control valve 16'.
When the weight exceeds the sum of the weight of the float 21 and the weight of the float 21, the float 21 floats up, and the flow control valve 16' is lifted up to open the orifice hole 23 provided in the orifice valve seat 18'.
More liquid will be drained.

Thereafter, as the liquid level in the tank 3 rises, the opening degree (L) of the valve body 16 gradually increases, and the discharged flow rate (Q,) increases accordingly. The relational expression is as follows.

Q, = c, ・π・D・L・ (2・g, H) o, s
co; flow coefficient D; orifice valve seat hole diameter L; valve opening degree (lift amount) g; gravitational acceleration H; liquid filling height As is clear from the old model, the discharged flow rate (Ql)
is proportional to the valve opening (L) of the flow control valve 16',
The larger the valve opening degree is, that is, the higher the float 21 floats, the larger the discharge flow rate (Q,) becomes. However, when the discharge flow rate (Q,) becomes larger than the (wI recirculation flow rate Q,), the liquid in the return pipe 11 Since the amount decreases, the plating solution filling height (H) gradually decreases, and accordingly, the valve opening degree (L) also decreases and the discharge flow rate (Qゎ) also decreases. From this, the valve opening degree (L) is determined by the discharge flow rate (
The opening is stabilized at a balance between Q, ) and (circulation flow rate -Q4). That is, according to the apparatus according to the present invention, during the circulation of the plating solution, it is possible to discharge the circulating flow rate while always filling the return pipe with the solution.

Here, if the circulating flow rate is large, the size of the small hole 20' cannot be made large due to space constraints, etc., and the discharged flow rate may not be able to reach the required flow rate.
It is also possible to provide a plurality of return pipes 11, lla as shown in FIG. 8 and to discharge most of the circulating flow through the other return pipe.

<Effects of the Invention> As described above, according to the present invention, by attaching a liquid discharge valve with a simple structure to the end of the return pipe, the return pipe can be filled with liquid, and air entrainment can be prevented. can. Therefore, oxidation of the plating solution due to air entrainment can be prevented, and the amount of chemicals input into the plating solution can be reduced.In addition, the capacity of the Fe'° reduction device to maintain plating quality 9 can be reduced, making it possible to reduce equipment costs. It is possible to significantly reduce the

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the entire device according to an embodiment of the present invention, FIG. 2 is a partially enlarged view showing part A in FIG. 1, and FIG.
The figure is a plan view taken along arrow B-B in Fig. 2, Fig. 4 is a graph showing the relationship between the load and deflection of the compression coil spring, and Fig. 5 is a graph showing the relationship between the plating solution filling height and the flow rate control valve according to the present invention. , a graph showing the relationship with the plating solution drainage flow rate, FIG. 6 is a schematic sectional view showing the entire apparatus according to another embodiment of the present invention, and FIG. 7 is a partial enlarged view showing part A in FIG. 6. 8 are schematic cross-sectional views showing the entire apparatus according to a modification of FIG. 6, and FIG. 9 is a schematic cross-sectional view showing the entire apparatus according to the conventional example. 1... Steel plate, 2... Plating solution tank, 3...
- Plating solution receiver is tank, 4... electrode, 5... energizing roll, 6... backup roll, 7... dam roll, 8... plating solution circulation tank, 9... plating solution circulation pump , lO...Liquid sending pipe, 11...Return pipe, 12...Plating solution, 13...Case,
14... Bolt, 15... Guidance guide,
16-...Flow control valve, 17...Compression coil spring,
18... Orifice valve seat, 19... Adjustment nut,
20...Small hole, 21...Float, 22
...Che7.23...Orifice hole・

Claims (1)

[Claims] 1. The plating solution can be circulated between an upper plating solution receiving tank that receives plating solution overflowing from the plating solution tank and a lower plating solution circulation tank that stores the plating solution supplied to the plating solution tank. A plating solution circulation device in a continuous plating apparatus connected by a plating solution return pipe as described above, wherein the plating solution return pipe is provided so that its lower end is immersed in the plating solution in the plating solution circulation tank, A flow control valve that is opened and closed depending on the plating solution level in the upper plating solution receiving tank is provided at the lower end of the plating solution return pipe, so that the plating solution return pipe can always be filled with plating solution. Plating solution circulation device in continuous electroplating equipment. 2. An orifice valve seat is provided at the lower end of the plating solution return pipe, and an orifice flow control valve connected to the guide guide and having a small hole is provided above, and the flow control valve is connected to the orifice valve seat and the guide guide. 2. The plating solution circulation device according to claim 1, wherein said orifice valve seat is provided in close contact with said orifice valve seat from below by a compression coil spring disposed between said orifice valve seats. 3. An orifice valve seat with a small hole is provided at the lower end of the plating solution return pipe, and a chain connects the float placed in the upper plating solution receiving tank to the flow control valve, and the flow control valve is connected to the orifice. The plating solution circulation device according to claim 1, wherein the plating solution circulation device is provided so as to be able to come into close contact with the valve seat from above.