JP2002194588A - Method and apparatus for electroplating metal strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for electroplating, which can decrease C curling of a sheet width direction, can unifomize a coating weight in the sheet width direction, and narrow the space between the sheet and the electrodes on electroplating a continually traveling metal strip. SOLUTION: The method for electroplating a metal strip horizontally transferred in a plating bath is characterized by arranging a pair of rolls coated with an elastic material, for sandwiching the metal strip between at least one of a front and a back of an electrification unit, each consisting of an electrification roll and a backup roll, which are arranged so as to put the metal strip between themselves, and making a surface hardness of the roll arranged in the above backup roll higher than that of the roll arranged in the above electrification roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for electroplating a continuously running metal strip.

[0002]

2. Description of the Related Art Conventionally, a method for electroplating a metal strip continuously and horizontally conveyed is as shown in FIG.
The metal strip 1 is pressed between the metal roll 1 and a backup roll 3 covered with rubber or the like, thereby energizing the metal strip 1 along the electrodes 5 arranged vertically above and below the metal strip 1 between the two energized rolls 2. This is carried out by transporting the metal strip 1. The energizing roll 2 is a metal roll, and the backup roll 3 is a roll in which the surface of a metal roll is coated with an elastic material such as urethane rubber, and is disposed above and below the metal strip 1.

In such an electroplating method, it is generally considered that the greater the pressing load of the above-described energizing roll 2, the lower the energizing resistance. However, when a large pressing load is applied between the energizing roll 2 and the backup roll 3, the surface deformation of the backup roll 3 coated with rubber or the like becomes large with respect to the metal energizing roll 2, so that the metal band 1 The contact length between the upper and lower surfaces of the metal strip 1 differs from that of the upper and lower surfaces, and a bending moment indicated by an arrow in FIG. As a result, a warp (L warp) that winds around the energizing roll 2 is generated, and this L warp is restrained by the line tension, and a warp (C warp) occurs in the width direction of the metal strip 1. The occurrence of C warpage in the plating tank causes unevenness in the plating direction in the width direction. Further, since the metal strip 1 comes into contact with the electrode 5 due to the C-warping and a spark is generated, the distance between the electrodes has to be increased to some extent, which causes a problem of an increase in power cost.

As a measure for preventing the C warpage generated in the plating tank as described above, for example, in Japanese Patent Application Laid-Open No. Sho 63-210294, the backup roll is coated with a hard rubber to reduce the rubber deformation. Thus, a method for preventing the occurrence of C warpage is disclosed. JP-A-64-36790 discloses a method of detecting the distribution of the amount of plating in the plate width direction, or detecting the amount of warpage in the plate width direction, and reducing the rolling force of the backup roll when warpage occurs. It has been disclosed. Japanese Patent Application Laid-Open No. H10-68098 discloses a method for preventing the occurrence of C warpage by reducing the diameter of a backup roll and offsetting the backup roll from an energizing roll.

[0005]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open
In the method disclosed in JP-A-63-210294, it is possible to reduce the amount of C warpage that occurs by increasing the hardness of the rubber coating, but the contact length on the current-carrying roll side is also reduced. As a result, the contact state between the energizing roll and the metal strip becomes unstable. In particular, when passing through a welding point where the plate thickness changes, a problem arises in that sparks occur due to insufficient contact between the current-carrying roll and the metal strip in the current-carrying unit.

In the method disclosed in Japanese Patent Application Laid-Open No. 64-36790, when the amount of warpage is large, the reduction in the contact length between the current-carrying roll and the backup roll is reduced. Is controlled in such a direction as to reduce the contact angle, but also in this case, the contact state on the side of the current-carrying roll becomes unstable, so that a spark is generated when passing through a welding point or the like.

In Japanese Patent Application Laid-Open No. 10-68098, the difference between the contact length between the energizing roll and the metal strip and the contact length between the backup roll and the backup roll is reduced by reducing the diameter of the backup roll. However, the diameter of the backup roll must be extremely reduced. Therefore, the offset arrangement serves as a substantial countermeasure against warpage, and the offset amount must be calculated and changed according to the thickness, width, material, or initial plate shape of the metal strip. For that purpose, a mechanism for moving the roll shaft is required, and a large capital investment is required.

[0008] In view of the above circumstances, the present invention provides a method for electroplating a continuously running metal strip.
An object of the present invention is to provide an electroplating method and an electroplating apparatus capable of reducing C warpage in the plate width direction, achieving uniform deposition amount in the plate width direction, and narrowing the distance between electrodes. I do.

[0009]

Means of the present invention for solving the above problems are as follows.

(1) In a method of electroplating a metal strip conveyed horizontally in a plating tank, a part or the whole of an energizing unit composed of an energizing roll and a backup roll interposed between the metal strips is provided. In at least one of the above, a set of rolls coated with an elastic material sandwiching a metal strip, and arranged, the surface hardness of the roll disposed on the backup roll side larger than the surface hardness of the roll disposed on the energizing roll side. Electroplating a metal strip.

(2) The surface hardness difference between the roll disposed on the energizing roll side and the roll disposed on the backup roll side is 20 or more in type A durometer hardness (JIS K 6253). A) a method for electroplating a metal strip according to the above.

(3) The rolling force of a set of rolls coated with an elastic material is controlled according to the material, thickness and width of the metal strip, as described in (1) or (2) above. Electroplating method of metal strip.

(4) The C warpage of the metal strip is detected behind the plating tank. If the detected C warpage of the metal strip is different from the target C warpage, the detected C warpage of the metal strip is changed to the target C warpage. The method for electroplating a metal strip according to any one of the above (1) to (3), wherein feedback control of a rolling force of a set of rolls coated with an elastic material is performed so as to obtain a warpage amount.

(5) In an electroplating apparatus for electroplating a metal strip conveyed horizontally in a plating tank, a part or a part of an energizing unit comprising an energizing roll and a backup roll interposed between the metal strips. At least one of before and after all, a set of rolls each coated with an elastic material having a different surface hardness is disposed sandwiching the metal strip, and further, an input device for inputting the material, the thickness and the width of the metal strip. A computing device that computes the rolling force of a set of rolls covered with the elastic material based on the material of the metal strip, the thickness and the width of the metal strip input from the input device, based on the computation result of the computing device, An electroplating apparatus for a metal strip, comprising: a control device for controlling a rolling force of a pair of rolls coated with the elastic material.

(6) A shape detecting device for detecting the C-warping of the metal strip behind the plating tank, and coating with an elastic material so that the amount of C-warping of the metal strip detected by the shape detecting device becomes a target C-warping amount. A computing device that recalculates the rolling force of the set of rolls based on the recalculation result of the computing device,
The electroplating apparatus for a metal strip according to the above (5), further comprising a control device for performing feedback control of a rolling force of the pair of rolls coated with the elastic material.

[0016]

Embodiments of the present invention will be described below in detail. FIG. 3 is a diagram showing one configuration of an electroplating apparatus applied to the present invention. An energizing unit consisting of a metal energizing roll 2 on the upper side of a metal strip (hereinafter, metal strip) 1 and a backup roll 3 coated with urethane rubber on the lower side, and a high pan in which the surface hardness of upper and lower rolls is changed before and after the energizing unit A set of dam rolls 4 and 4 covered with rubber, electrodes 5 and
5 and a plating tank 6.

Electroplating is performed by flowing a plating solution 7 between the upper and lower electrodes 5 and 5 and energizing the metal strip 1 conveyed horizontally by an energizing unit. The dam rolls 4 and 4 are disposed at the entrance (metallic band intrusion) and outlet (metallic band discharge) of each plating tank 7 for the purpose of preventing the plating solution 7 from flowing into the energizing unit. Therefore, a roll coated with an elastic material is usually used.

Each energizing roll 2 and backup roll 3
A reduction cylinder (not shown) for applying a required reduction force between them, and a reduction cylinder (not shown) for applying a required reduction force between the respective upper and lower dam rolls 4, 4 are provided.

The C warpage of the metal strip 1 is caused by the difference in the contact length between the upper and lower surfaces of the metal strip 1 on the upper and lower surfaces of the metal strip 1 in the power supply unit because the backup roll 3 is covered with an elastic material such as rubber. And occur. Therefore, the metal strip
By reducing the difference in the contact length between 1 and each of the rolls, it is possible to reduce C warpage, but in this case, the contact state on the energized roll side becomes insufficient, and there is a risk of spark generation. . That is, it is difficult to simultaneously perform stable energization and prevent the occurrence of C warpage in the energization unit.

Therefore, in order to correct the warpage generated in the current-carrying unit, it is necessary to apply bending deformation in the direction opposite to the bending given by the current-carrying unit from the current-carrying unit to the electrode. Here, in the dam roll 4 arranged before and after the energizing unit, the surface hardness of the backup roll contact surface side is made larger than that of the energizing roll contact surface side, so that the contact length between the upper and lower surfaces of the metal strip 1 and the dam roll 4 is increased. Since the difference occurs, bending deformation opposite to the bending generated in the energizing unit can be given, and it is possible to correct the warpage generated in the energizing unit.

In this case, in order to correct C warpage generated in the energizing unit, the difference in surface hardness between the upper and lower dam rolls is as follows:
It is preferable to set the type A durometer hardness (JIS K 6253) to 20 or more. Hereinafter, this point will be described. In this specification, unless otherwise specified, the surface hardness of the backup roll and the surface hardness of the dam roll are type A durometer hardness (JIS K 6253).

In the apparatus shown in FIG. 4, the plating solution 7 is withdrawn from one of the plating baths (6A) of the electroplating apparatus, the electrode 5 is removed, and the plating bath 6A is used to measure the warpage of the steel strip 1. A laser displacement gauge 16 is installed on a stage (movable stage) 17 movable in the width direction of the steel strip 1. The laser displacement gauge 16 was installed at an intermediate position between the energizing rolls 2 and 2 where the amount of C warpage was maximized. Using this device, φ350
75 mm surface hardness for 3 mm metal roll and backup roll 3
A roll of φ300 mm coated with urethane rubber of 20 mm was disposed. For the dam roll 4, a rubber roll of φ300 mm coated with 20 mm of Hypalon rubber having a surface hardness in the range of 70 to 100 was prepared. The steel strip 1 having a thickness of 1.2 mm and a width of 1800 mm was passed, and the amount of C warpage of the steel strip 1 when the surface hardness of the upper and lower dam rolls 4 was the same (all 75) was investigated. The surface hardness of the dam roll 4 on the backup roll 3 side is
The amount of C warpage of the steel strip 1 when a roll higher than the surface hardness of the dam roll 4 on the side was arranged was investigated. Fig. 5 shows the survey results.

In FIG. 5, the horizontal axis is the upper and lower dam rolls.
4, the surface hardness difference between the backup roll 3 and the surface hardness of the backup roll 3 side dam roll 4−the surface hardness of the energizing roll 2 side dam roll 4 is shown. The amount of C warp on the vertical axis is the upper and lower dam rolls
The C warpage generated when there is no difference in surface hardness is defined as the reference (1.0), and the C warpage generated when there is a difference in surface hardness is the C warpage generated when there is no difference in surface hardness. It is a relative ratio C1 / C0 to C0. An amount of C warp of 1.0 means that there is no C warp correcting effect, and an amount of C warp of 0 means that C warp is completely corrected.

As shown in FIG. 5, upper and lower dam rolls 4, 4
The difference in surface hardness between Type A durometer hardness (JIS K 625
It can be seen that if the value is set to 20 or more in 3), it is possible to substantially correct the C warpage generated between the energizing roll 2 and the backup roll 3.

With respect to the installation location of a set of rolls (dam rolls) 4 and 4 coated with an elastic material used for C warpage correction, if the rolls are installed on the upstream side of the power supply unit with respect to the passing direction, A bending deformation reverse to that of the energizing unit is given in the dam roll portion, and the warpage is corrected by the bending deformation between the energizing units. On the other hand, when it is installed on the downstream side, the bending deformation reverse to the bending given by the power supply unit is given by the dam roll to correct the warpage. Further, the dam roll 4 used for warp correction may be disposed both before and after the energizing unit. In this case, it is possible to perform the warp correction with a smaller rolling force than in the case where it is used either before or after.

Usually, a plurality of plating tanks are arranged in the running direction of the metal band. In order to prevent the plating solution 7 from flowing into an energizing unit composed of the energizing roll 2 and the backup roll 3, the dam rolls 4 and 4 are energized. It is located before and after the unit. For the warpage correction, only a change in the surface hardness of the rubber lining the dam roll does not require any special new equipment, and can avoid excessive capital investment.

Next, a specific warpage control method will be described. In the power supply unit, a sufficient pushing load is applied to perform stable power supply. 3 to 5 kg / mm in load per unit width
, A stable energization can be performed. At this time, the C warpage generated in the energizing unit changes depending on the material, the thickness and the width of the metal strip to be conveyed.

FIG. 6 shows an example of a metal strip (sheet thickness) when a metal energizing roll with a roll diameter of 350 mm is used as an example, and a backup roll is a φ300 mm roll coated with 20 mm of urethane rubber having a surface hardness of 90 mm. The graph shows the change in C warp for a material with a thickness of 1.0 mm and a width of 1200 mm). There is no difference in hardness between the upper and lower dam rolls, and the width load is 3.5 kg / mm.

FIG. 7 shows that a metal strip having a thickness of 0.8 mm, a width of 1600 mm and a yield stress of 20 kg / mm ² is energized by the above-described energizing unit under a load of 5000 kg, and the upper and lower surfaces arranged behind it. FIG. 4 shows a change in C warpage after passing through a dam roll with respect to a change in width load of a dam roll having changed hardness. At this time, the dam roll is a φ300 mm roll coated with 20 mm of Hypalon rubber, and the surface hardness of the dam roll on the energizing roll side is set to 75 and the surface hardness on the backup roll side is set to 100 for the metal strip. When the pushing load of the dam roll is about 3000 kg, the amount of C warpage is 5 mm or less. It can be seen that by optimizing the pushing load of the dam roll portion, the C warpage generated in the energizing unit can be corrected. 6 and 7, the upward warpage is defined as a positive value.

Since the optimum value of the pushing load of the dam roll for correcting the C warp varies depending on the material, thickness and width of the metal band, the most suitable pushing of the dam roll according to the material, thickness and width of the metal band. The load (dam roll reduction force) is determined in advance, and the optimum dam roll reduction force according to the material, thickness and width of the metal band determined in advance is tabulated and accumulated in the control arithmetic unit. The information of the material, the thickness and the width of the metal band to be input to the control arithmetic unit, and based on the material, the thickness and the width of the metal band input as described above, the optimum dam roll rolling force of the metal band is determined. By controlling the dam roll reduction force to the optimum reduction force determined above by calculation by the control calculation device, stable energization and reduction of C warpage can be achieved. FIG. 8 is a diagram showing a configuration example of a table for setting an optimum dam roll rolling force in accordance with the material, thickness and width of a metal strip.

From the relationship between the dam roll pushing load and the C warpage as shown in FIG. 7, if the detected C warpage is different from the target C warping, the dam roll pushing load necessary to eliminate the deviation is calculated. You can ask. Therefore, the above relationship is stored in the control arithmetic unit in advance,
In addition, a shape detection device for detecting the amount of C warpage of the metal band is disposed behind the plating tank, and when the amount of C warpage of the metal band detected by the shape detection device is different from the target amount of C warpage, the control arithmetic unit performs the following operations. A high accuracy is achieved by recalculating the dam roll indentation load necessary to set the belt C warpage amount to the target C warpage amount, and performing feedback control to control the dam roll rolling force based on the obtained dam roll rolling force. Thus, the amount of C warpage of the metal band can be corrected. Here, the target C warpage is preferably 5 mm or less, and is usually 0 mm.

FIG. 9 is a schematic diagram showing an example of a continuous electroplating facility provided with an electroplating apparatus according to an embodiment of the present invention. Embodiments of the present invention will be further described with reference to FIG. In FIG. 9, reference numeral 6 denotes a plating tank, and 15 plating tanks are arranged continuously in the transport direction of the metal strip 1. An energizing unit composed of an energizing roll 2 and a backup roll 3 is arranged before and after the plating tank 6. The energizing roll 2 is a metal roll, and the backup roll 3 is a roll coated with an elastic material. The rolling load between the backup roll and the energizing roll is not shown.
It can be adjusted using.

A pair of dam rolls 4 are arranged on the entrance side and the exit side of each plating tank 6, respectively. For the dam roll 4, use a roll coated with an elastic material.
The surface hardness of the dam roll 4 on the backup roll 3 side is harder than the surface hardness of the dam roll 4 on the energizing roll 2 side. The difference in hardness is preferably 20 or more. The rolling force between the pair of dam rolls can be adjusted using a rolling device (rolling cylinder) not shown. 8 is a pay-off reel, 9 is an electrolytic degreasing device, 10 is an input device, 11 is a control arithmetic device, 12 is a shape detecting device for detecting C warpage of the metal band 1 by a laser displacement detection method, and 13 is a fluorescent X-ray. This is an adhesion amount measuring device for measuring the adhesion amount of plating of the metal band 1 using the method.

The control arithmetic unit 11 has a material of a metal band,
The optimum pushing load (dam rolling force) of the dam roll according to the sheet thickness and the sheet width is accumulated. The control arithmetic unit 11 calculates and calculates the optimum rolling force of the dam roll based on the information on the material, thickness, and width of the metal strip 1 sent from the input device 10, and reduces the rolling force of the dam roll (not shown). Using the device, it is possible to control the rolling force of each dam roll to the rolling force determined above. In the apparatus shown in FIG. 9, the exit side dam rolls 4, 4 of the last plating tank 6 are also arranged so that the rolling force can be controlled by the control arithmetic unit 11. This is to correct the warpage generated in the energizing unit arranged downstream of the last plating tank 6.

A C-curve target value of the metal band 1 is input to the control arithmetic unit 11 in advance, and the C-warp amount of the metal band 1 detected by the shape detecting device 12 can be input. When the C warpage amount of the metal strip 1 detected by the shape detecting device 12 is different from the target C warpage amount, the control arithmetic unit 11 brings the detected C warpage amount close to the target C warpage amount, that is, eliminates a deviation between the two. It is possible to perform a feedback control so that the dam roll reduction force required for the above is calculated again and the dam roll reduction force is changed to the above determined roll reduction force. by this,
It becomes possible to correct the amount of C warpage of the metal strip 1 with high accuracy.

In the present equipment, the metal strip 1 is paid out from the pay-off reel 8, and after the oil adhering to the surface of the metal strip is washed by the electrolytic degreasing device 9, the zinc plating is performed in the plating tank (electroplating tank) 6. Is applied. At this time, the width load between the backup roll and the energizing roll is set to a rolling force capable of stably energizing all the energizing units. Further, based on the data of the material, thickness, and width of the metal band 1 input from the input device 10, the rolling operation of the dam roll is calculated by the control calculation device 11, and based on the calculation result, a reduction device (not shown) is used. The rolling force of the dam rolls 4, 4 is controlled to the rolling force calculated as described above.

As described below, the rolling force of the dam roll can be feedback-controlled. That is, the shape detection device 12 arranged behind the final plating tank
To detect the C warpage of the metal strip 1. When the amount of C warpage of the metal band 1 detected by the shape detection device 12 is different from the target value of the C warpage of the metal band 1, the rolling force of the dam roll required to reduce the deviation between the two is recalculated and obtained. Feedback control for controlling the rolling force of the dam roll based on the obtained rolling force is performed.

The metal strip 1 electrogalvanized as described above is subjected to a chemical conversion treatment in a chemical conversion treatment tank 14 and then wound up by a tension reel 15.

The above equipment has 15 plating tanks,
The number of plating tanks is not limited to 15 but may be one. In the case of one tank, at least one of the energizing units before and after at least one of the energizing units arranged on the upstream side and the downstream side of the plating tank, dam rolls having different hardness differences between the upper and lower sides as defined in the present invention are arranged. I just need. When two or more plating tanks are provided, at least one of before and after at least one of the energizing units arranged on the upstream side and the downstream side of at least one plating tank has a hardness difference between the upper and lower sides defined in the present invention. If different dam rolls are arranged, the effect of correcting C warpage can be obtained. In order to sufficiently exhibit the effects of the present invention, the hardness difference between the upper and lower sides defined in the present invention is defined in at least one of before and after at least one of the energizing units arranged on the upstream side and the downstream side of each plating tank. Are preferably arranged.

In the above-described apparatus, rolls having different hardness differences between the upper and lower sides of the dam roll are provided. However, another set of rolls coated with an elastic material installed for warpage correction is provided without disposing rolls having different hardness differences on the dam roll. A roll may be arranged between the energizing unit and the plating tank. When a dam roll is not used, another set of rolls may be arranged between the energizing unit and the plating tank.

[0041]

Embodiments of the present invention will be described below. (Example 1) Using the electroplating apparatus shown in FIG.
An example in which a steel strip 1 having a width of 2 mm and a width of 1800 mm is passed at a line speed of 150 mpm and electrogalvanized is shown below. Energizing roll
2 is a backup roll using a 350 mm metal roll
For 3, a rubber roll of φ300 mm coated with urethane rubber of 20 mm was used. Each roll body length is 2150mm. The surface hardness of the backup roll 3 is 90. Also, a rubber roll of φ300 mm coated with 20 mm of Hypalon rubber was used for the dam roll 4. The roll body length is 2150mm. Steel strip
The surface hardness of dam roll 4 on energizing roll 2 side is 75
The surface hardness of the dam roll 4 on the backup roll 3 side was set to 95. As a comparative example, the surface hardness of the dam roll 4 on the backup roll 3
The same as the surface hardness of 75. The rolling force between the energizing roll and the backup roll was 2.7 kg / mm, and the rolling force between the upper and lower dam rolls was 1.4 kg / mm.

In order to measure the shape of the steel strip 1 in the plating tank, as shown in FIG. 4, the plating solution 7 was not put in the plating tank 6A to be measured, and the electrode 5 was removed. 1
Laser displacement meter 16 on movable stage 17 movable in the width direction of
Was installed. The installation location was between the energizing rolls 2 and 2 where the amount of C warpage was maximized.

FIG. 10 shows the measurement results of the plate shape (C warpage) when dam rolls 4 and 4 having a hardness of 95 and 75 according to the present invention are combined. FIG. 10 also shows the measurement results of the plate shape (C warpage) when dam rolls 4 and 4 having a hardness of only 75 are used, which is a conventional method. In FIG. 10, the downward displacement amount of the steel strip with respect to the reference position is a positive value based on the positions of both ends of the steel strip. In the conventional method, C warpage of about 12 mm at the maximum occurs, whereas in the method of the present invention, the dam rolls 4 and 4
Since the plate shape is corrected by the above, there is almost no C warpage.

Further, the steel strip 1 was electrogalvanized (target adhesion amount: 20 g / m ² per side) using each of the dam rolls, and sampled at 10 locations in the width direction of the steel strip 1 to obtain fluorescent light.
The X-ray was used to measure the amount of galvanized coating. In the conventional method, there was a variation of ± 19% in the width direction, whereas in the method of the present invention, the variation was ± 3%.
In the method of the present invention, since the C warpage was eliminated, the variation in the attached amount could be significantly reduced.

Although the present embodiment is an example in which the upper and lower dam roll surfaces are coated with a hypalon rubber, the elastic material to be coated can be a wide range of elastic resin materials as well as the hypalon rubber.

(Example 2) A steel strip having a sheet width of 1600 mm, a sheet thickness of 0.8 mm and a yield stress of 20 kg / mm ² was passed at a line speed of 150 mpm by the continuous electroplating equipment shown in FIG. went. Roll diameter φ350 mm, body length 2150 mm for energizing roll 2
Using a metal roll, the backup roll 3 is coated with 20 mm of urethane rubber and has a roll diameter of φ300 mm and a body length of 2150 m
m, and the surface hardness of the backup roll 3 is 90
It is. The width load between the backup roll and the energizing roll is 3 kg / mm that enables stable energization in all energizing units. As the dam roll 4, a φ300 mm roll coated with 20 mm of Hypalon rubber is used, and the roll body length is 2150 mm. For the steel strip 1, the surface hardness of the dam roll 4 on the side of the energizing roll 2 was set to 75, and the surface hardness of the dam roll 4 on the side of the backup roll 3 was set to 98.

Further, based on the data of the material, thickness and width of the steel strip input from the input device 10, the control processor 11 determines the optimum rolling force of the dam roll, and the rolling force of the dam roll is calculated as the rolling force ( 3,000 kg), and the C detector of the steel strip 1 is detected by the shape detector 12 behind the final plating tank, and the control arithmetic unit 11 reduces the roll of the dam so that the detected amount of C warp becomes the target amount of C warp. The force was obtained by recalculation, and feedback control for controlling the rolling force of the dam roll to the rolling force obtained above was performed. The target C warpage amount is “0 mm”.

As the conventional method 1, electrogalvanizing was performed under the same conditions as the above-mentioned method of the present invention except that the surface hardness of the dam roll 4 was set to the same upper and lower 75. In addition, plate width 1 as conventional method 2
A steel strip 1 with a thickness of 600 mm, a thickness of 0.8 mm, and a yield stress of 20 kg / mm ² is passed through at a line speed of 150 mpm, with a roll diameter of 350 mm and a body length of 2150 m.
20 mm energizing roll 2 and urethane rubber with a surface hardness of 90
When energization is performed using the backup roll 3 having a coated roll diameter of 300 mm and a body length of 2150 mm, and the warpage amount of the steel strip 1 detected from the shape detection device 12 is different from the target C warpage amount (0 mm), the energizing unit is used. Feedback control was performed to increase or decrease the indentation load of the part, and electrogalvanizing was performed. At this time, the width load at the power supply unit was 2.2 kg / mm.

FIG. 11 shows an example of the result of measuring the C warpage of the steel strip 1 by the shape detecting device 12 when the electroplating is performed by each of the above methods. In FIG. 11, the upward displacement amount of the steel strip with respect to the reference position is set to a positive value based on the central position in the steel strip width direction. It can be seen that the conventional method 1 has a maximum C warp of about 20 mm, whereas the conventional method 2 and the method of the present invention hardly generate a C warp.

Table 1 shows the variation in the amount of zinc plating applied in the width direction of the steel strip 1 and the state of occurrence of sparks, which were measured using the plating amount measuring device 13.

[0051]

【table 1】

With respect to the plating amount, the conventional method 1 had a variation of ± 19% in the width direction in contrast to the conventional method.
In the method 2 and the method of the present invention, the variation in the adhesion amount is within ± 3%. On the other hand, sparks are generated in the conventional method 2, whereas no spark is generated in the method of the present invention. In other words, by applying the present invention, it is possible to realize both the stable energization and the flattening of the shape of the steel strip without making excessive capital investment compared to the conventional method.

[0053]

According to the present invention, it is possible to reduce the C warpage generated in the plating tank during the electroplating of the metal strip conveyed in the horizontal direction, and it is possible to make the plating adhesion amount uniform in the sheet width direction. And the quality and yield can be improved. In addition, it is possible to prevent the occurrence of sparks due to contact with the electrodes, and to reduce the space between the electrodes, thereby making it possible to reduce the power cost and the production cost.

[Brief description of the drawings]

FIG. 1 is a view showing a main part of an electroplating apparatus referred to for describing an electroplating method of a metal strip.

FIG. 2 is a view for explaining a bending moment acting on the upper and lower surfaces of a metal strip sandwiched between an energizing roll and a backup roll in the energizing unit of the electroplating apparatus of FIG.

FIG. 3 is a diagram showing an example of arrangement of main facilities of the electroplating apparatus according to the embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating an electroplating apparatus used in Example 1.

FIG. 5 is a diagram showing the relationship between the surface hardness difference between upper and lower dam rolls and the amount of C warpage correction.

FIG. 6 is a diagram showing a change in a warpage amount with respect to a yield stress of a metal band.

FIG. 7 is a diagram illustrating a change in the amount of warpage with respect to a change in a pushing load of a dam roll.

FIG. 8 is a diagram showing a configuration example of a table for setting an optimum dam roll rolling force according to a material, a plate thickness, and a plate width of a metal strip.

FIG. 9 is a schematic diagram illustrating an example of an arrangement of main facilities of a continuous electroplating facility including an electroplating apparatus according to an embodiment of the present invention, and a control flow of dam roll rolling force.

FIG. 10 is a diagram showing C warpage measurement results of the method of the present invention and the conventional method in Example 1.

FIG. 11 is a diagram showing C warpage measurement results of the method of the present invention and the conventional method in Example 2.

[Explanation of symbols]

 1 Metal strip 2 Power supply roll 3 Backup roll 4 Dam roll 5 Electrode 6, 6A Plating tank (Electroplating tank) 7 Plating solution 8 Payoff reel 9 Electrolytic degreasing tank 10 Input device 11 Control computing device 12 Shape detector 13 Adhesion amount measuring device 14 Chemical treatment tank 15 Tension reel 16 Laser displacement gauge 17 Movable stage

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Munehiro Ishioka 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4K024 AA05 AB01 BA02 BC01 CB03 CB10 CB26 GA16

Claims (6)

[Claims] Claims: 1. A method for electroplating a metal strip conveyed horizontally in a plating tank, wherein a part of or a whole of an energizing unit composed of an energizing roll and a backup roll arranged with the metal strip interposed therebetween is disposed. A pair of rolls coated with an elastic material sandwiching a metal strip is arranged on at least one of the rolls, and the surface hardness of the roll arranged on the backup roll side is made larger than the surface hardness of the roll arranged on the energizing roll side. A method for electroplating a metal strip. 2. The method according to claim 1, wherein a difference in surface hardness between the roll disposed on the energizing roll side and the roll disposed on the backup roll side is 20 or more in type A durometer hardness (JIS K 6253). A method for electroplating a metal strip as described. 3. The metal strip according to claim 1, wherein a rolling force of a set of rolls coated with an elastic material is controlled based on a material, a thickness, and a width of the metal strip. Electroplating method. 4. A C-warp of the metal strip is detected behind the plating tank, and when the detected C-warp amount of the metal strip is different from the target C-warp amount, the detected C-warp of the metal strip is detected.
4. The method for electroplating a metal strip according to claim 1, wherein the rolling force of a pair of rolls coated with an elastic material is feedback-controlled so that the amount of warpage is equal to a target amount of C warpage. . 5. An electroplating apparatus for electroplating a metal strip conveyed horizontally in a plating tank, wherein a part or all of an energizing unit including an energizing roll and a backup roll arranged with the metal strip interposed therebetween. At least one of before and after, a set of rolls each coated with an elastic material having a different surface hardness is disposed sandwiching the metal strip, further, an input device for inputting the material, the thickness and the width of the metal strip, A computing device that computes the rolling force of a set of rolls coated with the elastic material based on the material of the metal strip, the thickness and the width of the metal strip input from the input device, based on a computation result of the computing device, An electroplating apparatus for a metal strip, comprising: a control device for controlling a rolling force of a set of rolls coated with an elastic material. 6. A shape detecting device for detecting C warpage of the metal strip behind the plating tank, and the metal material is covered with an elastic material so that the amount of C warpage detected by the shape detecting device becomes a target C warpage amount. An arithmetic device that recalculates the rolling force of a set of rolls, and a control device that performs feedback control of the rolling force of the set of rolls coated with the elastic material based on the recalculation result of the arithmetic device, An apparatus for electroplating a metal strip according to claim 5.