JPH0333800B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a plating control system for controlling the concentration of metal ions in an electrolyte when electroplating metals, steel plates, etc.

<Prior Art> In the plating process of plating the surface of a steel plate, controlling the composition of the plating solution is one of the most important issues. Conventionally, various methods have been devised to control the composition of the plating liquid, such as control using a combination of a PH meter and a hydrometer.

In recent years, as the composition of plating solutions has become more complex, methods are being adopted to incorporate online analyzers to directly measure the composition of electrolyte solutions and to feed back the results.

<Problems to be Solved by the Invention> The plating liquid is usually controlled by adding acid and several types of metals, but this method has the following disadvantages.

(1) There is a large amount of wasted time after the metal is added until the result can be measured.

(2) Online analyzers use a sampling method, but the time interval between obtaining analysis values is long. Furthermore, there is a high probability that the analyzer will break down.

Therefore, it has been impossible to control the plating liquid with good controllability.

The present invention has been made in view of these points, and an object of the present invention is to realize a plating control system that improves controllability without being affected by the time delay in changing the composition of the plating solution after metal ions are introduced. shall be.

<Means for Solving the Problems> The configuration of the present invention that solves the above problems is as follows.

That is, the present invention provides a plating control system in which a plating liquid shower is applied to a steel plate for electroplating, and the used liquid is collected in a circulation tank and used again as a plating liquid shower. Q=α・K∫i(t)dt
(However, i(t) is the plating current, α is the feedback correction coefficient, and K is a constant including the plating efficiency), and the amount of metal ions corresponding to the amount of metal consumed Q is fed to the It is characterized by comprising means for charging metal ions into a circulation tank, and an arithmetic and control device that corrects the feedback correction coefficient α based on the difference between a target concentration and a measurement value of an analyzer that detects metal ion concentration provided in the circulation tank. This is a mesh control system.

<Function> The plating control system of the present invention detects changes in metal ions in the plating liquid as changes in the plating current and controls the introduction of metal ions in a feedforward manner based on the integrated value of the plating current. Errors caused by feed forward control are corrected based on the analysis value obtained from the analyzer output.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 1 is a circulation tank filled with plating liquid, 2 is a pump that pumps plating liquid to a shower chamber (described later), R1 to R3 are shower chambers, and S1 to S3 are installed in each shower chamber. Showers R01 to R03 are rollers that sandwich the steel plate 3 between them.

In the figure, the steel plate 3 advancing from the left side is plated (for example, nickel plated) while passing through each of the shower chambers R1 to R3, and exits from the right side.

Reference numeral 4 denotes a sampling type analyzer for measuring the concentration of metal ions in the plating solution, for example, a titrator is used.

5 is a tank in which predetermined metal ions are stored; 6
is a control valve that controls the electrolyte flow rate from the tank 5, and a predetermined amount of the metal ion liquid in the tank 5 is injected into the circulation tank 1, and the metal ion concentration in the circulation tank 1 is maintained constant. dripping

The operation of the device configured as described above will be explained as follows.

In the apparatus shown in the figure, the plating liquid in the circulation tank 1 is pumped to the shower chambers R1 to R3 by the pump 2, and the steel plate 3 passing through each shower chamber R1 to R3 is pumped to the shower chambers R1 to R3.
Sprinkle on. At this time, a potential is applied to the steel plate 3 via the rollers R01 to R03 in each of the shower chambers R1 to R3, so electroplating is performed using the same principle as if the steel plate 3 were placed in a plating solution.
The surface of the steel plate 3 is plated with metal. The plating liquid sprinkled on the steel plate 3 falls below each of the shower chambers R1 to R3 and is returned to the circulation tank 1, but the metal ions are reduced by the amount of plating. Therefore, it is necessary to inject the metal ion liquid previously stored in the tank 5 into the circulation tank 1 to keep the metal ion concentration in the circulation tank 1 substantially constant. The present invention is characterized in that the system is configured to keep the metal ion concentration in the circulation tank 1 constant.

In normal operating conditions, the amount of plating and the plating current can be considered to be in a proportional relationship. Therefore,
The integrated value of the plating current within a certain fixed period corresponds to the amount of metal consumed during that period. That is, the consumed metal amount Q is expressed by the following equation.

Q=α·K∫i(t)dt (1) Here, i(t) is the plating current, α is the feedback correction coefficient, and K is a constant including the plating efficiency. Further, K changes depending on the type of steel plate. This amount of consumed metal Q is also the amount of metal that must be replenished into the plating solution. Let this metal amount be FF. Therefore, the amount of metal Q obtained using equation (1)
By replenishing the plating solution in a feed-forward manner, the metal ion concentration in the plating solution can be kept almost constant.

In the present invention, although not shown in the figure, an ammeter is connected between the rollers R01 to R03 serving as electrodes and their power source, and the output thereof is integrated to obtain an integrated plating current value. Then, this plating current integrated value is defined as the amount of metal consumed Q, and the amount of metal corresponding to this amount Q is
FF is replenished from the tank 5 to the circulation tank 1 via the control valve 6 by feedforward control.
Note that in order to realize this feedforward control, ordinary control equipment may be used.

By the way, the above-mentioned control is performed successfully when the metal amount and the integrated value of the plating current are in an accurate proportional relationship, but in reality they are not in an accurate proportional relationship. The exact metal ion concentration in the circulation tank 1 depends on the output of the analyzer 4. Therefore, if the result PV of the measurement value of the analyzer 4 can be reflected in the metal ion injection control, more accurate metal ion concentration control can be performed.

Therefore, in the present invention, a method is added to correct the constant α in equation (1) using the value FB (=SV-PV) obtained from the analyzer output. Here, SV is the target concentration. The frequency with which the value of the constant α is modified depends on each case. This correction operation is performed by an arithmetic and control device (not shown) that receives the output of the analyzer 4. As the arithmetic and control device, for example, a control computer or a microcomputer is used. The arithmetic and control device adjusts the control valve of the tank 5 according to the corrected amount of metal,
A predetermined amount of metal ions is injected into the circulation tank 1.

In other words, the quick response of the control is achieved by feedforward control using the accumulated current value, and the reliability of the control is improved.
Accuracy takes into account feedback control in which the constant α in equation (1) is modified based on the analyzer output. With such a configuration, metal ion concentration control can be performed with both quick response and accuracy.

FIG. 2 is a diagram showing operating waveforms of each part when the system of the present invention is operated.

In this figure, a shows the waveform of the plating current I,
b is a diagram showing the integrated value ΣI of the plating current I, c is a diagram showing the metal input amount Q, and d is a diagram showing the measured value PV of the analyzer.

From the first plating current integrated value S1, the first metal input amount Q1 is determined, and from the first measurement value PV1 of the analyzer 4, the constant α in the above equation (1) is determined.
The correction amount is calculated, and the next metal input amount Q2 is corrected.

By repeating such operations, metal ion concentration control is performed. In addition, analyzer 4
It is not necessary to correct the late deposit amount based on the measured value every time, and the correction amount may be obtained by averaging several sampled values of the measured value.

The features of the present invention are listed below.

(1) Even if analysis values for metal ions cannot be obtained, metal injection control can be continued by integrating the plating current.

(2) When the plating conditions change, the input amount can be changed in a feed forward manner.

(3) Based on the difference with the analysis results, the weight of the feed forward amount can be automatically corrected so that the deviation becomes smaller.

(4) Process waste time can be easily reflected.

<Effects of the Invention> As explained in detail above, according to the present invention,
Changes in metal ions in the plating liquid are detected as changes in the plating current, and metal ion injection control is performed in a feed-forward manner using the integrated value of the plating current, and errors caused by this feed-forward control are analyzed by metal ion analysis. Since the correction is made based on the analytical value obtained from the meter output, it is possible to realize a plating control system with improved controllability without being affected by the time delay of the plating liquid composition change after metal ion injection. can.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a diagram showing operation waveforms of each part of the embodiment of FIG. 1. 1... Circulation tank, 2... Pump, 3... Steel plate, 4... Analyzer, 5... Tank, 6... Control valve, S1-S3... Shower, R1-R3... Shower room, R01- R03... Laura.

Claims (1)

[Claims] 1 In a plating control system in which a plating liquid shower is applied to a steel plate for electroplating, and the used liquid is collected in a circulation tank and used again as a plating liquid shower, the amount of metal consumed Q = α・K from the integrated value of plating current. ∫i(t)dt (however, i(t)
is the plating current, α is the feedback correction coefficient, K
is a constant including the plating efficiency) and inputs an amount of metal ions corresponding to the consumed metal amount Q into the circulation tank by feed forward control; A plating control system comprising: an arithmetic and control device that corrects the feedback correction coefficient α based on the difference between the measured value of the analyzer and the target concentration.