JPH1046398A - Method for controlling plating current of electroplating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling the plating current of an electroplating equipment with the ignition and burning in the flexible conductor of the equipment prevented with a simple device. SOLUTION: The surface temp. of a flexible conductor through which a plating current is passed is measured with an IR-radiation thermometer in an electroplating equipment, and the current is controlled based on the measured values. Further, the surface temps. of the plural flexible conductors for applying a plating current to the same plating tank are measured by an IR-radiation thermometer, and the current is controlled based on the difference in surface temp. between the flexible conductors. More preferably, the current strength of the plating tank is controlled to conform to the reference current strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a plating current of an electroplating facility for a metal strip such as a steel strip (strip), and more particularly, to applying a plating current between a power supply and an electrolytic cell in the electroplating facility. Flexible conductors (hereinafter referred to as
The present invention relates to a method of controlling a plating current for preventing ignition and burning of a flexible conductor.

[0002]

2. Description of the Related Art FIG. 3 is a side view showing an example of a plating tank of an electroplating facility. In FIG. 3, 1 is a steel strip (strip), 2 is an anode (plating electrode) immersed in a plating solution,
Reference numeral 3 denotes a plating solution, 4 denotes a conductor roll, 5 denotes a rubber roll, 6 denotes a plating tank provided with rubber lining, 7a denotes an anode receiver, 8 denotes a plating solution tray, 9 denotes a plating solution overflow, and 1a denotes a transport direction of a steel strip. Is shown.

[0003] The steel strip 1 is in contact with the plating solution 3 filled in the plating tank 6 while the conductor roll 4 and the rubber roll 5 are in contact with each other.
Transported by On the other hand, the plating current is changed to the anode receiving table 7a →
The anode 2 → the plating solution 3 → the steel strip 1 → flows in the path of the conductor roll 4, and the anode 2 itself is ionized by being energized and dissolved in the plating solution 3, and the dissolved components of the anode 2 become the steel strip 1. Plated.

[0004] Fig. 4 is a perspective view showing an example of an auxiliary equipment for an electroplating tank. In FIG. _4, 7a ₁ ~7a 4 anode cradle, 7b ₁ is an anode cradle struts, 11a, 11b are bus bars (: metal rod to transmit the current from the power supply to the electrolytic cell), 12a
, 12b indicate the direction of current flow, 14 indicates a brush, 15 indicates a current collecting ring, and other reference numerals indicate the same contents as in FIG.

[0005] In FIG. 4, to show the arrangement of anode cradle 7a ₁ ～7A ₄ in the plating tank 6 is arranged on the anode cradle 7a in the plating bath of the left side _3, 7a ₄ anode 2 and the anode cradle strut 7b _2, 7b _3, wherein the 7b ₄ is short. Moreover, as the electroplating bath ancillary facilities, flexibility between the bus bar 11a and the anode cradle strut 7b ₁ ~7b _4, for ease of anode cradle post installation, a strand material, for example copper Flexible conductors 13 ₁ , 13 ₂ , 13 ₃ ,
13 ₄ are provided.

[0006] plurality of anodes 2 anode cradle 7a ₁ ~7a ₄
, And a positive DC voltage is applied to the anode 2. Current passes through the bus bar 11a from the rectifier, the flexible conductor _131-134, anode cradle strut 7b ₁ to 7-
b ₄ , is supplied to each anode 2 via the anode receiving tables 7 a _{1 to} 7 a ₄ .

The current supplied to the anode 2 is as follows: anode 2 → plating solution 3 → steel strip 1 → conductor roll 4 → current collecting ring 15 →
Return to the rectifier through brush 14 → bus bar 11b. In the electroplating equipment, a plurality of such plating tanks 6 are provided for each of the front and back surfaces of the steel strip 1. FIG. 5 shows a circuit diagram of the plating current control of the electroplating equipment.

In FIG. 5, C ₁ , C ₂ , C ₃ , C
_n is each plating equipment corresponding to each plating tank 6 (hereinafter, each plating equipment corresponding to each plating tank 6 is referred to as plating cell), 21 is a rectifier, 22 is a diode, 23 is a transformer, and 24 is a thyristor. , 25 is a current controller for each plating tank 6, 26 is a direct current detector, 27 is a full current controller, 28 is a bridle roll, 29 is a steel strip transport speed detector, for example, a tachometer generator (: PG). , 30 is a plating weight setting device, 31
Denotes an arithmetic unit, 32 denotes a current adder, 33 and 34 denote arithmetic elements,
Other symbols indicate the same contents as in FIG.

Each of the plating tanks 6 has a current control device 25 shown in FIG. Rectifier 21 is diode 2
2 、 Transformer 23 、 Thyristor 24 、 Thyristor 2
The amount of current is controlled by 4, a low voltage is applied by the transformer 23, converted into direct current by the diode 22, and the direct current is supplied to the anode 2. The current flowing through the plating tank 6 is detected by the DC current detector (DCCT) 26, a current value mc ₁ of the detected plating cell C _1, the other plating cell at a current adder 32 C _2, C ₃ , C _n detected current values mc ₂ , mc
_3, summed with mc _n, the sum mc _t of the detected current value is used for control.

On the other hand, the plating basis weight of the steel strip 1 in the electroplating equipment (total) is proportional to the sum mc _t of the detected current value of each plating cell, the total current control device so that this value is constant by 27 it is controlled such that the total mc _t between the detected current value setting the total current value (reference value) coincide. The output of the total current control device 27 is distributed as a reference current of each plating tank 6, and each plating tank 6 has a current attached to each plating tank 6 so as to correspond to this reference current value (= set current value). It is controlled by the control device 25.

With such a control system and the hardware configuration of each plating cell, a surface-treated steel strip can be stably produced. Although the electroplating equipment is configured as described above, insulating impurities called sludge are generated around the anode 2 in the plating tank 6. In this case, due to the sludge, poor contact between the anode 2 and the anode receiving table 7a occurs, and a phenomenon occurs in which current does not flow to a part of the anode 2 in the plating tank 6.

When this phenomenon occurs, current does not flow through some of the flexible conductors 13 of the plating cell that supplies current to each anode 2, and current concentrates on other flexible conductors 13 of the same plating cell. There is a problem that the Joule heat generated by the excess current causes the flexible conductor 13 to ignite. In this case, there is a method of directly measuring the current of each flexible conductor and estimating the heating state. However, since the current supplied to the anode 2 is a direct current, the current is supplied to each flexible conductor of all the plating cells for measurement. A large-scale direct current detector (DCCT) must be installed, and it is not economical in terms of equipment costs.

For this reason, conventionally, it has been necessary for the operator of the electroplating equipment to temporarily stop the operation and to operate while frequently cleaning the contact portion between the anode 2 and the anode receiving stand 7a. However, there was a problem that was reduced.

[0014]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and controls the plating current of an electroplating facility capable of reliably preventing ignition and burning of a flexible conductor of the electroplating facility with a simple apparatus. The purpose is to provide a method.

[0015]

According to a first aspect of the present invention, in an electroplating facility, the surface temperature of a flexible conductor through which a plating current is applied is measured by an infrared radiation thermometer, and the current is controlled based on the measurement result. A plating current control method for an electroplating facility, characterized in that: The second invention is
In an electroplating facility, measuring the surface temperature of a plurality of flexible conductors for supplying a plating current to the same plating tank with an infrared radiation thermometer, and controlling the current based on a difference in surface temperature between the flexible conductors. A plating current control method for an electroplating facility, characterized in that:

A third invention is a plating current control method for an electroplating facility in which a plating current value in a plating tank is controlled so as to match a reference current value, wherein a plurality of plating currents are supplied to the same plating tank. The surface temperature of the flexible conductor is measured with an infrared radiation thermometer, and when the difference | ΔT | between the maximum value and the minimum value of the surface temperature of each flexible conductor is equal to or greater than a preset value, the plating bath A plating current of an electroplating facility, wherein the plating current is reduced or limited to a certain value or less.

In the third aspect of the present invention, the reference current value is at least a target plating weight,
Alternatively, it is preferably at least a reference current value determined by a target plating weight and a steel strip transport speed (line speed).

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present invention has been made in order to solve the above problems, and monitors the surface temperature of the flexible conductor of the electroplating equipment with an infrared radiation thermometer, for example, between a plurality of flexible conductors attached to the same plating cell Then, when a temperature difference equal to or greater than the reference value occurs, the current of the plating cell is reduced or limited to a certain value or less, and an alarm is output to a facility operator.

By using the above-described current control method, it is possible to prevent overheating, ignition and burning of the flexible conductor, and to produce a plated product stably. The present invention
It is preferably applied to continuous electroplating of metal strips such as steel strips,
Further, it is preferably applied to electric pure metal plating such as electric tin-based plating, electric nickel-based plating, electric zinc-based plating, and electrochromic plating, and electric alloy plating, but the type of plating is not limited.

FIG. 1 shows an example of a plating current control method for an electroplating facility according to the present invention. In FIG. 1, 40 ₁ , 40 ₂ ,
40 _3, 40 ₄ is an infrared radiation thermometer, the temperature comparator 42 is an alarm output signal of the anode contact failure 41, 43 current limiter,
R indicates infrared rays, and other symbols indicate the same contents as in FIGS. In the present invention, for example, the flexible conductor 13
The surface temperature of ₁ , 13 ₂ , 13 ₃ , 13 ₄ is measured by infrared radiation thermometer 40
_1, 40 _2, 40 _3, detected in 40 _4, and sends the temperature information to the temperature comparator 41.

The temperature comparator 41 constantly compares this temperature. The anode 2 and each of the anode receivers 7a ₁ , 7a ₂ , 7a ₃ , 7a
By the time insulating sludge does not exist between the _4, current flowing through the flexible conductor 13 ₁ four being measured by an infrared radiation thermometer 40 _{1-40 4,} 13 _2, 13 _3, 13 ₄ is substantially Equally, the temperature of each flexible conductor is also kept substantially constant.

However, these four anode receivers 7a ₁ , 7a
_If sludge exists between any one of the anodes ₂ , 7 a ₃ , and 7 a ₄ , no current flows through the anode pedestal 7 a and the flexible conductor 13 connected to the anode pedestal 7 a
As a result, no current flows, and no Joule heat is generated in the flexible conductor 13, and the temperature of the flexible conductor 13 decreases.

On the other hand, the reference current value (= set current value) of the plating tank 6 is basically the same unless the target plating weight, the steel strip conveying speed (line speed), and the like change, so that they are the same. The current flows excessively through the other flexible conductors 13 in the plating cell and the temperature rises, and a temperature difference occurs between the flexible conductor 13 through which no current flows and the flexible conductor 13 through which the current flows excessively.

Further, when current interruption due to sludge occurs in the two anode supports 7a among the four anode supports 7a, the flexible conductor 13 in which no current flows and the flexible conductor 13 in which current flows are formed. Is further increased. In the present invention, for example, the temperature comparator 41 calculates the difference between the maximum temperature and the minimum temperature of the plurality of flexible conductors 13 ₁ , 13 ₂ , 13 ₃ , and 13 _{4 in} the same plating cell C _1, and calculates the temperature difference. | ΔT | is a preset value (= |
[Delta] T | when an abnormal set value of the detection) above, the current limiter 43 shown in FIG. 1, by limiting the current of the plating cell C ₁ reduction or below a certain value, overheating of the flexible conductor 13, fire, Burnout can be prevented.

When two flexible conductors are attached to the same plating cell C ₁ , the difference between the two surface temperatures |
ΔT | may be used. In the present invention, as if to limit the current of the plating cell C ₁ to the predetermined value or less,
Wherein the | [Delta] T | when setting the abnormality detection is a margin setting value, or, for example, if the reference current value the the plating cell C ₁ drops in succession the abnormality detecting simultaneously or phases are illustrated You.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. The plating current control method of the electroplating equipment shown in FIG. 1 described above was employed, and tin was used as the anode 2 and the steel strip 1 was subjected to electrotin plating. Plating current I of the plating cell C ₁ shown in FIG. 1 when this, the flexible conductor 13 _1, 13 _2, 1
3 _3, 13 plating current I ₁ flowing through the _4, I _2, I _3,
I _4, each flexible conductors detected by the infrared radiation thermometer
13 and the difference between the maximum value and the minimum value of the surface temperature of each of the flexible conductors 13, T ₁ , T ₂ , T ₃ , T ₄ = | Δ
FIG. 2 shows the time lapse of T |.

As shown in FIG. 2, after the power supply to the plating cell C ₁ is turned on, a contact failure occurs at the anode support 7a ₁ , and after a lapse of time, a contact failure also occurs at the anode support 7a ₂ . did. Along with this, flexible conductor 1
3 _3, 13 current flows through the ₄ I _3, I ₄ is raised, the flexible conductor 13 ₃ detected by the infrared radiation thermometer, 13 ₄ of the surface temperature T _3, T ₄ also rises, the surface temperatures of the flexible conductor 13 When the difference between the maximum value and the minimum value of | = ΔΔT | reaches the set value for abnormality detection, the current limiter 43 shown in FIG. 1 is activated, the current I of the plating cell C ₁ is reduced, and the plating cell C ₁
The ignition and burning of the flexible conductor 13 could be prevented.

According to the present invention, the surface temperature of each flexible conductor that supplies current to the plating cell is detected, and based on the result, the occurrence of electrical contact failure in the plating tank is detected, and the current of the plating cell is detected. Because it was controlled, sludge deposition occurs between the anode and the anode support, current is concentrated on a specific flexible conductor, the temperature of the flexible conductor increases, and even if there is a risk of burning, Since the current of the plating cell is controlled by reducing or limiting due to the temperature abnormality,
Stable operation without worrying about troubles.

Further, by measuring the surface temperature using an infrared radiation thermometer, it is not necessary to install a large-scale DC current detector for each flexible conductor of all the plating cells, and it is easily damaged locally. The average temperature of the flexible conductor can be measured, and the temperature history of the flexible conductor can be directly managed, so that maintenance is easy.

In particular, in the third invention of the present invention, as a basic principle, the temperature of the flexible conductor corresponding to the anode cradle in which the electrical contact failure has occurred is lower than that during normal energization, In addition, since the temperature of other flexible conductors rises, the difference between the maximum value and the minimum value of the surface temperature of each flexible conductor = | ΔT | Ignition and burning in the conductor can be reliably prevented.

[0031]

According to the present invention, ignition and burning of a flexible conductor in an electroplating facility, which has been a problem in the past, can be reliably prevented with a simple apparatus, and an improvement in productivity can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a plating current control method for an electroplating facility of the present invention.

FIG. 2 is a graph showing a current of a plating cell, a current of each flexible conductor, a surface temperature of each flexible conductor, and a time course of a difference between a maximum value and a minimum value of each surface temperature.

FIG. 3 is a side view showing an example of a plating tank of an electroplating facility.

FIG. 4 is a perspective view showing an example of an auxiliary equipment for an electroplating tank.

FIG. 5 is a circuit diagram of plating current control of an electroplating facility.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Steel strip (strip) 2 Anode 3 Plating solution 4 Conductor roll 5 Rubber roll 6 Plating tank 7a Anode support 7b Anode support columns 11a and 11b Bus bar 13 ₁ , 13 ₂ , 13 ₃ , 13 ₄ Flexible conductor 21 Rectifier 25 Current control Device 26 DC current detector 27 Total current control device 28 Bridle roll 29 Steel strip transport speed detector 30 Plating weight setting device 31 Computing device 32 Current adder 40 ₁ , 40 ₂ , 40 ₃ , 40 ₄ Infrared radiation thermometer 41 temperature comparator 42 the alarm output signal 43 current limiter R infrared _{C 1, C 2, C 3} , C n plating cell

Claims (3)

[Claims] 1. A plating current for an electroplating facility, wherein the surface temperature of a flexible conductor through which a plating current flows is measured by an infrared radiation thermometer, and the current is controlled based on the measurement result. Control method. 2. In an electroplating facility, the surface temperature of a plurality of flexible conductors for applying a plating current to the same plating tank is measured by an infrared radiation thermometer, and based on a difference in surface temperature between the respective flexible conductors, A plating current control method for an electroplating facility, comprising controlling a current. 3. A plating current control method for an electroplating facility in which a plating current value of a plating tank is controlled to be equal to a reference current value, wherein a plurality of flexible conductors for supplying a plating current to the same plating tank. Is measured with an infrared radiation thermometer, and when the difference | ΔT | between the maximum value and the minimum value of the surface temperature of each of the flexible conductors is equal to or greater than a preset value, the plating current of the plating tank is reduced. A plating current control method for an electroplating facility, wherein the plating current is reduced or limited to a certain value or less.