JPH10237698A - Method for diagnosing deterioration of iridium oxide anode and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decide the service life of an iridium oxide anode with high precision. SOLUTION: At the time of diagnosing deterioration of an iridium oxide anode used for electroplating, at least either a primary method in which representative voltage is calculated by substituting prescribed representative current density for a regression formula obtd. from current density and electrolytic voltage measured by a current detector 16 and a voltage detector 14 over plural times before the nearest operation, and when the representative voltage is higher than critical voltage, it is decided that the anode deteriorates or a secondary method in which electric currents flowed respectively through two or more contact parts 12A to 13E for energizing arranged by being away from the anode are measured by current detectors 16A to 16E, and when a part of measured current is lower than the critical current, it is decided that the anode locally deteriorates is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for diagnosing deterioration of an iridium oxide / anode which are particularly suitable for determining the life of an iridium oxide / anode used in an electroplating facility.

[0002]

2. Description of the Related Art In general, while a steel sheet is being conveyed, the steel sheet is used as a cathode (cathode) and its surface is continuously plated with a metal such as zinc or nickel. At this time, an anode coated with iridium oxide (hereinafter, also referred to as an iridium oxide anode or simply an anode) is used as the anode.

FIG. 6 is a schematic sectional view showing the structure of a main part of a conventional electroplating facility using the above-mentioned anode.

In the above-mentioned conventional electroplating equipment, a steel sheet S as a material to be plated is transported in a direction perpendicular to the plane of FIG. 6 and a predetermined interval is provided between the upper and lower surfaces of the steel sheet S. The above-mentioned anode 10 is disposed. An energizing bus bar 12 for supplying electric power is connected to the anode 10, and a predetermined electrolytic voltage is applied between the anode 10 and the steel sheet S via the bus bar 12, and the voltage is reduced. By the voltage detector 14,
The current flowing through the bus bar 12 is detected by a current detector 16.

[0005] As shown in FIG.
, The relationship between the upper and lower anodes 10 is symmetric and substantially the same, and unless otherwise noted, only one of them will be described as a representative.

FIG. 7 shows a temporal change of the electrolytic voltage at the time of plating detected by the voltage detector 14 when the steel sheet S composed of a rolled coil sequentially conveyed by the conventional electroplating equipment is continuously plated. FIG. 8 is a graph showing an example of a temporal transition of the upper current A _U and the lower current _AD flowing through the bus bar 12 similarly detected by the current detector 16. Note that the broken line in FIG. 7 corresponds to a limit voltage used for determination according to the present invention described later, and the broken line in FIG. 8 corresponds to a normal current value.

When the steel sheet S is continuously plated on several rolled coils in the conventional electroplating equipment as described above, the iridium oxide coated on the surface of the anode 10 gradually deteriorates. If this deterioration exceeds the limit, good plating cannot be obtained, so it is necessary to accurately diagnose the degree of the deterioration.
It is extremely important for maintaining the quality of plating.

Generally, as a method for diagnosing the deterioration of the iridium oxide anode 10 as described above, the anode voltage (electrolytic voltage) during operation is controlled for each coil, and when the voltage exceeds the limit voltage, the life is reached. And a method of periodically measuring the coating thickness of iridium oxide on the anode 10 and determining that the life has been reached when the remaining amount at that time falls below a limit value.

[0009]

However, the above-described method of managing the anode voltage during operation for each coil is as follows.
In the case of plating coils having different plate widths and different amounts of metal adhesion (amount of electricity), since the anode voltages are different from each other, there is large variation in the measured anode voltages for each coil as shown in FIG. However, it is difficult to determine whether the iridium oxide anode 10 has really deteriorated from this voltage change.

The method of measuring the coating thickness of iridium oxide on a regular basis has the advantage that the local deterioration can be sufficiently determined. However, when a large number of anodes are measured, the work is difficult. It takes a long time to perform this operation.

The present invention has been made in order to solve the above-mentioned conventional problems, and provides a method and an apparatus for diagnosing deterioration of an iridium oxide / anode capable of determining the life of the iridium oxide / anode with high accuracy. That is the task.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a method for diagnosing the deterioration of an iridium oxide anode for use in electroplating, which judges whether or not the iridium oxide anode has deteriorated, a plurality of times before the latest operation. From the measured current density and the electrolytic voltage, a regression equation representing the relationship between the two is obtained, a representative voltage is calculated by substituting a predetermined representative current density into the regression equation, and the representative voltage exceeds the limit voltage. When
A first method of determining that the iridium oxide anode has deteriorated as a whole, and measuring a current flowing through each of two or more current-carrying contacts disposed apart from the iridium oxide anode, and measuring a part of the contact. This problem has been solved by using at least one of the second method for determining that the iridium oxide anode has locally deteriorated when the measured current in the section falls below the limit current.

[0013] The present invention also relates to an iridium oxide / anode deterioration diagnosis apparatus for judging whether or not an iridium oxide / anode used for electroplating has deteriorated. Voltage detecting means for detecting an applied electrolytic voltage is provided, and two or more current-carrying contact portions are provided at a distance from the anode, and current detecting means for detecting a current flowing through each contact portion is provided. The above-mentioned problem is similarly solved by adopting the configuration provided.

That is, in the first method according to the present invention, the current density and the electrolysis density actually measured for each coil when plating a certain number of coils, for example, a plurality of times before the most recent operation. The voltage is plotted to obtain a regression equation representing the relationship between the two. Then, a predetermined representative current density (for example, determined as an average current density in the plating equipment) used as a criterion for determination is substituted into the regression equation, and a corresponding representative voltage is calculated. When the predetermined threshold voltage is exceeded, it is determined that the iridium oxide anode has reached the end of its life.

As described above, by using the representative voltage, it is possible to determine the overall deterioration of the anode with high accuracy. In addition, since the representative voltage is calculated using a regression equation always created based on the latest data, deterioration can be determined based on the temporal transition of the relationship between the current density and the electrolytic voltage in an actual plating facility. Even when the equation is not a straight line as described below, it is possible to determine the appropriate anode life for each facility.

In the second method according to the present invention,
A plurality of current-carrying contacts connected to the same power supply are installed separately from each other in the width direction of the anode, and the current flowing through each contact is measured to reduce the current drop caused by local deterioration. However, when it is sensed from the current value in some of the contact portions, it is determined that the degree of deterioration of a part of the anode has exceeded the limit and the life has been reached.

In the present invention, since the first and second methods are used alone or in combination to perform the deterioration diagnosis, the deterioration of the iridium oxide anode can always be diagnosed with high accuracy. It has become possible.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view, corresponding to FIG. 6, showing a main part of an electroplating facility according to an embodiment of the present invention.

The electroplating equipment of the present embodiment continuously electroplates zinc and nickel on a rolled steel sheet S which is sequentially conveyed in units of coils, and is different from the conventional equipment shown in FIG. Similarly, iridium oxide anodes 10 are provided on the upper and lower sides of the steel sheet S, respectively. The anode 10 has, for example, a thickness of about 10 mm,
Titanium (Ti) of about 300-400mm each
A substrate having a surface coated with iridium oxide (IrO ₂ ) having a thickness of about 10 to 20 μm was arranged and fixed on a base member vertically and horizontally in plural numbers.
It has a size of about mm × 1000 mm.

In this embodiment, the anode 10
In addition, five contact portions 12A to 12E of the energizing bus bar 12 are provided so as to divide the width direction into a plurality of ranges, and the anode 1 is connected via the contact portions 12A to 12E.
0 is electrically connected to a power source (not shown), and current detectors 16A to 16E for detecting currents flowing through the respective contact portions 12A to 12E are respectively provided. 16A to 16E enable each current to be detected online. The rest of the hardware configuration is substantially the same as the conventional equipment shown in FIG.

In the present embodiment, the material to be plated is a rolled steel sheet S which is sequentially conveyed in coil units, and while plating the steel sheet, at least one of the first method and the second method described in detail below is used. One of them is selected by selecting means (not shown), and the deterioration diagnosis of the iridium oxide anode 10 is executed.

First, the first method will be described. In the first method, each time a steel sheet S of a new coil is plated, the current density (A / d) actually measured for each of a fixed number of coils plated before (before the latest operation).
m ² ) and the electrolysis voltage (V) are plotted as shown by ● in FIG. 2, and a regression equation given by the following equation representing the relationship between the two is obtained. The number of coils for obtaining this regression equation can be, for example, 50.

Vi = f (Ai) (1)

Here, f represents a function, and i represents the number of the coil that has been plated or is being plated during the most recent (latest) operation.

When the above regression equation is obtained, as shown conceptually in FIG. 3, the case where this equation is a straight line, the representative current density _AT is substituted into this regression equation Vi, and the obtained voltage is represented by the representative voltage. and V _T. The representative current density A _T is used as a criterion for determination, and can be set at an arbitrary constant value. Here, since the number of coils is large, the average current density in the facility obtained from the past results is calculated. Has adopted. However, the present invention is not limited to this, and a maximum value and a minimum value may be used.

In the present embodiment, each time a new coil is electroplated by the first method as described above, the relationship between the current density and the electrolytic voltage measured for a fixed number of coils before that is used. A regression equation corresponding to the equation (1) is created, and the representative voltage is sequentially calculated in the same manner as in FIG. 3, and the transition of the value is monitored.

[0028] Figure 4, in this way the representative voltage V _T which is calculated, is plotted against the horizontal axis represents time (number of coils). From this Figure 4, when representing the electrolysis voltage of the anode 10 as a time shift of a representative voltage V _T,
Since data having no variation as in the related art shown in FIG. 7 is obtained, it is possible to stably and accurately grasp the temporal change of the electrolytic voltage.

[0029] Further, the representative voltage V _T, in accordance with iridium oxide is coated on the anode 10 is gradually deteriorated, since the regression equation of the slope becomes larger, so that gradually increases.

[0030] Therefore, in the present embodiment, by performing the operation described above for each of plating steel sheet S of a new coil, sequentially continue to calculate a representative voltage V _T, the broken line value of the V _T is 4 When the threshold value _VL is exceeded, it is determined that the life of the iridium oxide anode 10 has reached its life. Note that the limit voltage _VL is determined in advance based on past performance data.

According to the above-described first method, each time a new coil is plated, a current density and an electrolytic voltage actually measured when plating a certain number of coils before that are plotted to plot both of them. After obtaining the regression equation representing the relationship, the representative voltage at the representative current density of the equipment is calculated using the regression equation, and this voltage is used for the life judgment. Diagnosis can be performed.

Next, the second method will be described. This second method also involves each time each coil is electroplated,
Each of the contact portions 12A to 12 of the bus bar 12 shown in FIG.
By measuring the current flowing through E with the current detectors 16A to 16E, if the measured current at some of the contact portions is below the limit value, the deterioration of iridium oxide locally progresses, and the service life is reached. It is determined that it has been performed. FIG. 5 shows the temporal transition of the current values A1 to A5 actually measured by the current detectors 16A to 16E, respectively, and the broken line shows the normal value. From this figure, it can be seen that the deterioration has progressed near the two contact portions 12A and 12E since the current values A1 and A5 have decreased.

[0033] Thus, by detecting the current drop that occurs in a part of the contact portion of the bus bar 12, the local anode 10 does not come appear as rising transition of the representative voltage V _T by the first method Deterioration can be accurately diagnosed.

According to the present embodiment described in detail above, for the overall deterioration of the anode, the first method is used to reduce the electrolysis voltage during operation for each of a certain fixed number of coils in the most recent operation. After obtaining the regression equation by plotting the values, the electrolytic voltage (representative voltage) at the representative current density is calculated using the regression equation, and this value is monitored (monitored). Is reduced, and as a result, the entire anode life can be accurately determined.

In addition, for the partial deterioration of the anode, the second
According to the method described above, the current flowing through the contact portions 12A to 12E of the bus bar 12 which is arranged by dividing the anode in the width direction is measured online and monitored, so that partial degradation that does not appear as a voltage rise can be accurately performed. The life of the anode can now be determined.

Further, the combined use of the first and second methods makes it possible to simultaneously determine the lifetime of the iridium oxide anode 10 for both total deterioration and partial deterioration.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, the number of contact portions of the bus bar is not limited to the number shown in the above embodiment. The anode 10
The specific configuration, size, and the like are not limited to those described in the above embodiment.

[0039]

As described above, according to the present invention,
The life of the iridium oxide anode can be determined with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main part of an electroplating facility according to an embodiment of the present invention.

FIG. 2 is a diagram conceptually showing how to obtain a regression equation.

FIG. 3 is a diagram conceptually showing a method of obtaining a representative voltage from a regression equation.

FIG. 4 is a diagram showing a change in the electrolytic voltage of the anode calculated according to the present invention.

FIG. 5 is a diagram showing a transition of a current flowing through each contact portion measured according to the present invention.

FIG. 6 is a schematic sectional view showing a main part of a conventional electroplating facility.

FIG. 7 is a diagram showing transition of a conventional anode electrolysis voltage;

FIG. 8 is a diagram showing a transition of a current flowing through a conventional bus bar.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Iridium oxide anode 12 ... Bus bar for electric conduction 12A-12E ... Contact part 14 ... Voltage detector 16 ... Current detector S ... Steel plate

Claims (3)

[Claims] 1. A method for diagnosing iridium oxide anode deterioration, which determines whether or not the iridium oxide anode used for electroplating has deteriorated, comprising the steps of: measuring current density and electrolytic current measured a plurality of times before the most recent operation; From the voltage, a regression equation representing the relationship between the two is obtained, a predetermined representative current density is substituted into the regression equation to calculate a representative voltage, and when the representative voltage exceeds the limit voltage, the iridium oxide anode A first method of determining that the entire battery has deteriorated, and measuring the current flowing through each of two or more current-carrying contacts disposed separately from the iridium oxide anode, and measuring the measured current at some of the contacts. Is below the limit current,
A method for diagnosing deterioration of an iridium oxide anode, wherein at least one of a second method for determining that the iridium oxide anode has locally deteriorated is used. 2. The method according to claim 1, wherein when the electroplating is continuous plating in which a plurality of rolled coils are sequentially plated, a current density and an electrolytic voltage measured for each coil are used to determine the regression equation. A method for diagnosing deterioration of an iridium oxide anode. 3. An apparatus for diagnosing deterioration of an iridium oxide anode for use in electroplating, which determines whether or not the iridium oxide anode has deteriorated, wherein the electrolysis applied between the iridium oxide anode and the material to be plated. A voltage detecting means for detecting a voltage is provided, two or more current-carrying contacts are provided at a distance from the anode, and current detecting means for detecting a current flowing through each contact is provided. An iridium oxide / anode deterioration diagnosis device, characterized in that: