JPS62103391A - Continuous electroplating method for metallic strip - Google Patents

Abstract

PURPOSE:To prevent the generation of an over-coat and under-coat to the ends of a metallic strip in the stage of subjecting the surface of the strip to continuous plating by providing auxiliary cathode plates in proximity to the ends of the strip as a cathode and controlling the value of the current flowing therein. CONSTITUTION:Electricity is conducted between the steel strip 4 and anode plates 9 disposed on both sides of the strip via conductor roll 2 as the cathode and the surface of the strip 4 is plated. The auxiliary electrodes 10, 10' are disposed in proximity to the transverse ends of the strop 4 and are respectively connected via voltage regulators 13, 13' and current controllers 15, 15' to the conductor roll 2 as the cathode. The values of the current flowing through the auxiliary electrodes 10, 10' during the plating treatment are detected by detectors 14, 14' and the voltage regulators 13, 13' are so operated as to attain the preset current values, by which the plating layer having a uniform thickness in the transverse direction of the strip 4 is formed on the strip without the over-coat of a large plating thickness or under-coat of conversely a small thickness at the transverse ends of the strip 4.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to over-plating, in which the amount of plating at the edges of the metal strip is greater than that at the center, when continuously electroplating a metal strip such as steel or aluminum. This method relates to a continuous electroplating method for metal Sl-IJ knobs, which does not cause coating or undercoat where the amount of plating is smaller than the center part, and can provide uniform plating without unevenness in the width direction. It is.

[Prior art and its problems]

For example, for continuous electroplating of steel strip,
There are two methods: a method of plating using a vertical electroplating device as shown in FIG. 2, and a method of plating using a horizontal electroplating device as shown in FIG. As shown in Fig. 2, the vertical electroplating apparatus consists of a vertical electroplating tank 1, conductor rolls 2 and 2' provided above the knob entry and exit sides, and an electroplating tank 1. Non-crawl 3 installed at the bottom of 1 and conductor roll 2
2' and the non-crawl 3, a pair of vertical electrode plates 5 are arranged parallel to the steel strip 4, with the steel strip 4 moving in the electroplating bath 1 in between.
, 5' and 6,6'. steel steel l-1) no f
4 moves downward and then upward in the electroplating bath 1 in which a plating bath is contained and flowing, and continuously while passing a pair of electrode plates 5, 5' and 6, 6'. Electroplated.

As shown in FIG. 3, the horizontal electroplating apparatus includes conductor rolls 2 and 2' provided outside the steel strip inlet and outlet sides of the horizontal electroplating tank 7, and Upper and lower 1 installed on the steel strip entry and exit sides
Pairs of dumb rolls 8a, 8a' and 8b, 8
b' and dam 0-/l/8 a, 3 a' and B
b, B b', a pair of horizontal electrode plates 5° 5' and 6, arranged parallel to the steel strip 4, with the steel strip 4 moving in the electroplating tank 1 in between. 6
It consists of '. The steel strip 4 moves through an electroplating tank 7 in which a plating bath is contained and flowing;
Electroplating is carried out continuously while passing through pairs of electrode plates 5, 5' and 6, 6'.

The problem when electroplating both sides of the steel strip 4 using this method is that, as shown in Figure 4, the plating current concentrates on the edges of the steel strip 4, causing the amount of plating on the edges to decrease. The problem is that an overcoat becomes larger than other parts.

When electroplating one side of steel stock 7″4, the fifth
As shown in the figure, in addition to overcoating the edges as described above, a problem arises in which current flows to non-plated surfaces and causes plating.

In this way, when an overcoat occurs on the edges of the steel strip, a build-up phenomenon occurs in which the edges bulge when the steel strip is wound into a coil, and the plating films on the overcoat parts become attached to each other. Problems arise such as scratches occurring due to rubbing, poor welding strength of the overcoat portion during welding, and poor appearance due to discoloration of the overcoat portion.

Therefore, in order to prevent the above-mentioned problems, the 6th
As shown in Fig. 7 and Fig. 7, the main electrode plate 9,
A narrow auxiliary electrode plate 10 with a length comparable to the length of 9'
, 10' are arranged, and the main electrode plate 9.9' and the auxiliary electrode plate 10
, 10', the plating current that was concentrated on both edges of the steel strip 1 is concentrated on the auxiliary electrode plate 10°lO', and is thus generated at the edge of the steel stock f4. Methods have been developed to prevent overcoating and to prevent plating on non-plated surfaces in the case of single-sided plating.

The above method prevents overcoating from occurring on the edges of the steel strip, but it also prevents undercoat where the amount of plating on the edges is less than on other parts, and the steel strip meandering in its width direction. When the relative distance between the edge of the steel strip and the auxiliary electrode plate changes, the current distribution at the edge changes, causing a problem of uneven plating at the edge.

Fig. 8 shows a pair of main electrical grid plates 9.9' as shown in Fig. 9.
An auxiliary electrode plate 10 is placed in parallel with the steel strip 1-IJ sof 4 in close proximity to the edge of the steel strip 4 that passes between This is the ratio of tin adhesion to the central portion of the edge portion on one side of the steel stock f4 in the case where the steel strip 4 is electroplated with tin. In Fig. 9, the ■ mark is when L is 10 cores, the mu mark is when L is 25 cores, the 10 mark is when L is 50 cores, and the triangle mark is when auxiliary electrode plate 9 is not arranged. . As shown in the drawing, when L is 10, an undercoat occurs in which the amount of tin deposited on the edge portions is reduced by about 15 factors compared to the center portion.

[Purpose of the invention]

Therefore, it is an object of the present invention to prevent overcoat or undercoat from forming on the edges of the gold strip during electroplating on metal IJ tabs, and to prevent uneven plating even when the metal strip meanders in its width direction. To provide a method for continuous electroplating of metal strips, which can always apply a uniform amount of plating in the width direction of the metal strip without causing the occurrence of electroplating.

[Summary of the invention]

The present inventors have discovered that by placing an auxiliary electrode plate close to both edges of a metal strip during movement in an electroplating bath, overcoating that occurs on both edges of a metal strip can be prevented. We have conducted extensive research to solve the above problems.

The present inventors first investigated the relationship between the distance between the edge of the metal knob and the edge of the auxiliary electrode plate and the plating current flowing through the auxiliary electrode plate. Figure 10 is a graph showing the relationship between the position of the auxiliary electrode plate and the current flowing through the auxiliary electrode plate. Current value 1
00%, the horizontal axis is the distance between the edge of the metal strip and the edge of the auxiliary electrode plate. As shown in FIG. 10, it was found that as the distance between the nick of the metal strip and the edge of the auxiliary electrode plate became longer, the value of the current flowing through the auxiliary electrode plate decreased.

Next, the relationship between the voltage value and current value of the auxiliary electrode plate was investigated.

FIG. 11 is a graph showing the relationship between the current flowing through the auxiliary electrode plate and its voltage when the distance between the edge of the IJ tab and the edge of the auxiliary electrode plate is 25 ML.
The vertical axis is the current value flowing in the center of the metal strip to be plated (same surface as the auxiliary electrode plate, bond part),
The percentage of current flowing through the auxiliary electrode plate, expressed as 0%, and the horizontal axis is the ratio of the voltage of the auxiliary electrode plate to the voltage of the main electrode plate. As shown in FIG. 11, it was found that as the voltage of the auxiliary electrode plate was increased, the value of the current flowing through the auxiliary electrode plate was decreased.

On the other hand, if the current flowing through the auxiliary electrode plate is controlled to a predetermined value, even if the metal strip meanders in its width direction and the distance between its edge and the edge of the auxiliary electrode plate varies, Metals) l) It has been found that uniform plating can be achieved by applying an overcoat or undercoat to the edge of the horn.

The present invention is based on the above findings, and consists of continuously guiding a metal strip into an electroplating bath containing a plating bath in which at least one electrode plate is arranged.
The metal strip is continuously plated on its surface while the tube passes through the electrode plate. l) -7
In the continuous electroplating method of the plating tank, at a position where the electrode plate is arranged in the plating tank,
An auxiliary electrode plate is disposed close to the edge of the metal strip passing through the plating bath, and a current is passed between the auxiliary electrode plate and the electrode plate to prevent overcoat from occurring on the edge portion of the metal strip. At the same time, the present invention is characterized in that the value of the current flowing through the auxiliary electrode plate is continuously detected, and the voltage of the auxiliary electrode plate is controlled so that the current value becomes a predetermined value.

[Structure of the invention]

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram illustrating one embodiment of continuous electroplating of steel strip using a vertical electroplating apparatus according to the method of the present invention; as shown in the drawing,
A pair of vertical main electrode plates 9 (only one of which is shown in the drawing) are parallel to the steel strip 4, with the steel strip 1 moving in the electroplating bath guided by the conductor rolls 2 in between. Auxiliary electrode plates 10 and 10' are arranged adjacent to both sides of the IJ tube 11. The main electrode plate 9 is connected to the anode side of a power source (not shown), and the conductor roll 2 is connected to the cathode side of the power source (not shown).
l+, steel strino f4 is connected to conductor roll 2
energized by.

Each of the supplementary JJ electrode plates 10 and 10' is connected to the conductor roll 2 via each of voltage regulators 13 and 13'. l 1 , 1.1' is a current collector taken as IQI+ of conductor roll 2.

Electronic collector 11. ．． 11' and auxiliary electrode plate] 0.10'
In the middle of the conducting wires 12, 12' connecting each of the voltage regulators] 3, 13' and current detectors 1ll, 1.
-1' is provided. Voltage regulator 13, 13'
A current controller 15, 15' is connected to each of the current detectors 14, 14' and a current controller 15, 1.
5' means conductor 16! 6'.

In advance, the auxiliary electrode plates 10 and 1 corresponding to the appropriate distance between the edge of the steel strip 1 and the auxiliary electrode plates 10 and 1 O' where overcord and undercoating do not occur at the edge of the IJ tube 4 are prepared in advance. A current value flowing through O' is determined and this current value is input into the current controllers 15 and 15'.

On the other hand, the current value flowing through the auxiliary electrode plates 10, 10' is continuously detected by the current detectors 1.4, 14', and the detected current value is passed through the conductor wires 16, 1.6' to the current 1l.
Feedback to ls 1 s, 15'. [Current side (goods) device] 5, 15' compares the detected current value fed back and a predetermined current value inputted in advance, and makes the difference between the detected current value and the predetermined current value zero. The current value is sent to the voltage regulator 13, I3'. The voltage regulators 1:3, 13' are connected to the auxiliary electrode plates 10, 10' based on the signals from the current controllers 15, 15'.
The voltage is adjusted so that the current value becomes a predetermined value.

The voltage regulators 13, 13' may be of any type other than thyristor tanks as long as they can vary the voltage and have a sufficient current capacity.

By performing the above-mentioned control, the steel strip f4
A meandering occurs between the edges of the steel strip 4 and the auxiliary electrode plate 1.
Even if the distance between the auxiliary electrode plates 10 and 10' changes, a current of a predetermined value always flows through the auxiliary electrode plates 10 and 10'.

Therefore, overcoat and undercoat formation on the edge portion of the steel strip 4 is properly prevented.

For example, when continuous tin plating is applied to a steel strip using a vertical electroplating apparatus, if no auxiliary electrode plate is placed, the area between 30 mm and 30 mm from the edge of the steel strip will be tin-plated more than the other areas. Also, an overcoat with a large amount of 94 plating occurred, but the overcoat could be prevented by the arrangement of the auxiliary electrode plate. On the other hand, in the above portion, on the contrary, an undercoat with a 14-thickness plating amount less than other portions and uneven plating occurred. However, according to the method of the present invention, undercoating was completely prevented and only a slight overcoat occurred between the edges of the steel strip. Even if the steel strip meandered 15 times from side to side, there was no change in the amount of plating deposited on the edge portions, and no uneven plating occurred.

In addition, when applying continuous single-sided electrogalvanizing only to the bottom surface of the steel strip at a point 10 degrees below the bath surface of the plating bath using a horizontal electroplating device, conventionally, the method was to apply continuous single-sided electrogalvanization from the top edge of the steel strip 25 minutes below the surface of the plating bath. However, according to the method of the present invention, undercoating does not occur on the edges of the bottom surface, and the plating that occurs on the edges of the top surface does not occur from the edge to the 10th edge. I was able to reduce it in time.

〔Effect of the invention〕

As described above, according to the present invention, when continuously electroplating a metal strip using a vertical electroplating device or a horizontal electroplating device, an overcoat or an undercoat is not formed on the edge portion of the metal strip. Not born,
Even if the metal strip meanders in the width direction, uneven plating does not occur, and a uniform amount of plating can always be applied to the metal strip in the width direction, providing an industrially outstanding effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of continuous electroplating using a vertical electroplating apparatus according to the method of the present invention, FIG. 2 is a schematic longitudinal sectional view of the vertical electroplating apparatus,
Figure 3 is a schematic vertical cross-sectional view of a horizontal electroplating device, Figure 4 is an explanatory diagram showing the concentration of plating current on the edge in case of double-sided plating, and Figure 5 is towards the non-plated side in case of single-sided plating. Figures 6 and 7 are explanatory diagrams showing the distribution of plating current when an auxiliary electrode plate is placed, and Figure 8 is an illustration showing the relationship between the edge of the steel strip and the auxiliary electrode plate. Figure 9 shows the distance between the edge of the steel strip and the auxiliary electrode plate, and Figure 1O shows the position of the auxiliary electrode plate. FIG. 11 is a graph showing the relationship between the current flowing through the auxiliary electrode plate and its voltage. In the drawing, 1...
Vertical electroplating tank, 2, 2'... contactor roll, 3... zinc roll, 4... steel steel) IJ knob, 5.5', 6
．． 6'... Electrode plate, 7... Horizontal electroplating tank, 8a, 8a', 8b, 8b'... Dam roll, 9.9'
・Main electrode plate, 10.10'...Auxiliary electrode plate, 11
, ]1'... Current collector, 12.12'... Conducting wire,
13, 13'...voltage regulator, 14, 14'...
・・Current detector, 15.15'・Current controller, 16,1
．． 6'・Conducting wire.

Claims (1)

Claims: A metal strip is successively guided into an electroplating tank containing a plating bath in which at least one electrode plate is arranged, while the metal strip passes through the electrode plate. In a continuous electroplating method for a metal strip in which the surface of the metal strip is continuously plated, at a position in the plating bath where the electrode plate is arranged,
An auxiliary electrode plate is disposed close to the edge of the metal strip passing through the plating bath, and an electric current is passed between the auxiliary electrode plate and the electrode plate to prevent overcoating from occurring at the edge of the metal strip. A continuous electroplating method for a metal strip, characterized in that the current value flowing through the auxiliary electrode plate is continuously detected, and the voltage of the auxiliary electrode plate is controlled so that the current value becomes a predetermined value. .