JP2940082B2 - Plating current control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plating current control device for controlling a plating current of a plurality of plating tanks.

[Conventional technology]

FIG. 3 is a block diagram showing a conventional example of this type of plating current control device. In the figure, 1 is a strip to be plated, 2 is a line speed detector for detecting the line speed of strip 1, 3a to 3c are plating tanks, and 4a to 4c are plating supplied to plating tanks 3a to 3c. Plating current detectors to detect current respectively, 5a-5c are controllable rectifiers that supply plating current to plating tanks 3a-3c, 6a-6c are controllable rectifiers
Controller for controlling the output current of 5a to 5c to a predetermined value, 7a
7c is a current distributor for distributing and supplying the plating current to the controllers 6a to 6c, 8 is an adder for calculating the sum (actual current sum) of the output values of the plating current detectors 4a to 4b, 9 is PI
A controller that inputs a deviation between the output of the adder 8 and the output of the arithmetic circuit 10 and supplies a current distribution reference to the distributors 7a to 7c. Reference numeral 10 denotes a calculation circuit which calculates a deviation between the line speed and the total current reference and supplies the calculated deviation to the adder 10a. The adder 10a outputs to the PI controller 9 the deviation between the actual current sum from the adder 8 and the output of the arithmetic circuit 10 (total current reference). Numeral 11 calculates the above-mentioned total current reference from the basis weight, the strip width of the strip 1, the electrode efficiency and the line speed.

[Problems to be solved by the invention]

As described above, in the related art, a value obtained by increasing or decreasing the set total current reference according to the line speed of the strip 1 is compared with the actual current sum, and the actual current sum is feedback-controlled so that the deviation becomes zero. Therefore, there is a problem that the plating current density cannot be controlled within a predetermined range.

The present invention has been made in order to solve the above-mentioned problem, and it is an object of the present invention to provide a plating current control device capable of limiting a plating current density of each plating tank to a predetermined range and operating the whole efficiently. With the goal.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a current reference circuit for setting a reference for the sum of plating currents supplied to a plurality of plating tanks, and increases or decreases the current reference in response to an increase or decrease in line speed of a strip to be plated. A plating current control device that has an arithmetic circuit and feedback-controls the actual current sum based on a deviation between the output of the arithmetic circuit and the actual current sum, and individually performs feedback control of the plating current of each plating tank; A selection circuit for increasing or decreasing the number of plating tanks operated based on the line speed is provided, and a current limiter for limiting a plating current of each plating tank is provided.

[Action]

According to the present invention, the maximum plating current is limited by the current limiter, and the number of operable plating tanks is calculated from the comparison between the total current reference and the minimum actual current sum. By increasing or decreasing, the plating current range falls within a predetermined range.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numerals 12a to 12c denote current limiters,
The current output from each of the current distributors 7a to 7c is limited.
13 is a selection circuit, the output of the calculation circuit 10, that is,
The deviation between the line speed of the strip 1 and the total current reference is input, and the selecting operation shown in the flowchart of FIG. 2 is executed. Other configurations are the same as those in FIG.

Next, the operation of this device will be described with reference to FIG.

Now, it is assumed that the plating tanks 3a and 3b are operating. When it is determined in step ST1 that the operation state of the line is, for example, in the deceleration mode, in step ST2, the number n of plating baths currently in operation and the minimum current value (the current value of the plating bath having the minimum current density). and the product n · I _min of I _min, the total current reference correction value at the line speed is the magnitude of the .SIGMA.I (total current reference in the current line speed) are compared, in the case of ΣI <n · I _min, the step In ST3, it is determined that one of the plating tanks is stopped (n → n−1), and the power supply to the plating tank 3b is stopped. This operation is repeated until n = 1, and after n = 1, when ΔI = 0 (ST
5) The operation of the last one plating tank is stopped (ST
6).

If it is determined in step ST1 that the operation state of the line is, for example, the acceleration mode, in step ST7, the number of plating tanks (n +
1) the product of the minimum current value I _min (n + 1) · and I _min, the large and small compared with the total current reference .SIGMA.I at the current line speed, when it is ΣI (n + 1) · I min , the step
In ST8, one of the plating tanks is additionally operated (n → n + 1)
Is determined, and the operation of the plating tank 3c is started. This operation is repeated until n = n _max (ST9).

The maximum value of the plating current in each of the plating tanks 3a to 3b is limited to the limit value I _Limit of each of the current limiters 12a to 12c.

As described above, in the present embodiment, the maximum current is limited by the current limiter, and the number of plating tanks that can be operated at the current value I _min that gives the minimum current density is calculated.
Since the number of operating plating baths is adjusted, the plating current is adjusted between the limit value I _Limit of the current limiter and the above-described I _min .

〔The invention's effect〕

As described above, the present invention limits the maximum current by the current limiter, and the product of the number of operating plating tanks or the number obtained by adding one to the number of plating and the minimum current value with respect to the total current reference corrected at the current line speed. Since the number of operating units is increased or decreased according to the size, the plating current density can be kept within a predetermined range, and the operation as a whole can be operated at the maximum operating efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart of a selection circuit in the above embodiment, and FIG. 3 is a block diagram of a conventional plating current control device. In the drawing, 1... Strip, 2... Line speed detector, 3a to 3c... Plating bath, 4a to 4c.
5c: Controllable rectifier, 6a to 6b: Controller, 7a to 7b
... distributor, 8 ... adder, 9 ... PI controller, 10 ... arithmetic circuit, 11 ... current reference circuit, 12a to 12c ... current limiter, 13 ... selection circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A current reference circuit for setting a reference for the sum of plating currents supplied to a plurality of plating tanks; and an arithmetic circuit for increasing or decreasing the current reference in response to an increase or decrease in line speed of a strip to be plated. A plating current control device that feedback-controls the actual current sum based on the deviation between the output of the arithmetic circuit and the actual current sum and individually controls the plating current of each plating tank in a feedback manner. Calculating the number of operable plating tanks from the value and the above current reference, providing a selection circuit for increasing or decreasing the number of operating plating tanks, and providing a current limiter for limiting the plating current of each plating tank. A plating current control device.