JP4952265B2 - Steel strip electroplating equipment and electroplating method - Google Patents

Description

  The present invention relates to an electroplating facility and an electroplating method for performing electroplating on a steel strip obtained by cold rolling.

  Electroplating technology that applies electroplating (for example, electrotin plating, electrogalvanization, electrocopper plating, etc.) to steel strips obtained through cold rolling, annealing, and temper rolling processes provides steel strips continuously. However, it is possible to perform electroplating, and a great effect can be obtained for cost reduction. In the technology that is generally adopted, Fe oxide (so-called scale) generated before the plating process adheres to the steel strip, and in order to perform uniform and good electroplating, the scale must be removed from the steel strip. Don't be.

A technique for removing the scale chemically by immersing a steel strip in an acidic aqueous solution (so-called pickling) is widely used. An acidic aqueous solution used for pickling (hereinafter referred to as a pickling solution) is a strongly acidic aqueous solution in which sulfuric acid, hydrochloric acid, or the like is dissolved. If this pickling solution is brought into the next plating solution in a form remaining on the surface of the steel strip, it becomes difficult to control the concentration of each component of the plating solution.
Therefore, the pickling liquid remaining in the steel strip after pickling is washed away with water to wash the steel strip (so-called water washing), thereby preventing the pickling solution from being taken out. In addition, a water washing apparatus that uses both water washing and brush removal has been put into practical use.

The washed steel strip is fed to the electroplating section. At that time, various foreign matters (that is, Fe oxide, Fe hydroxide, etc. generated by pickling) adhere to both the upper and lower surfaces of the steel strip. These foreign substances are extremely small and small in quantity, and even if they are attached to the steel strip, if they are electroplated as they are, they will not be a negative effect of uniform electroplating.
However, when the steel strip is transported by the transport roll, the foreign matter is caught between the steel strip and the transport roll on the surface of the steel strip that contacts the transport roll, and adheres to the transport roll. The foreign matter adhering to the transport roll is initially a very small particle and a small amount, but gradually accumulates during operation and is further transferred from the transport roll to the surface of the steel strip. At that time, since the steel strip and the conveying roll are pressed at the contact portion, the foreign matter is firmly pressed against the surface of the steel strip. As a result, there arises a problem (so-called non-plating) that the electroplating layer is not formed on the portion where the foreign matter is firmly attached, resulting in a decrease in yield.

In particular, when an aqueous solution of methanesulfonic acid is used as a tin plating solution in electrotin plating, the influence of Fe hydroxide (that is, Fe (OH) ₃ ) on the occurrence of non-plating becomes significant.
In order to prevent this non-plating, the conveyance roll must be periodically cleaned. However, when the worker removes the foreign matter using the care jig, the operation must be stopped from the viewpoint of safety, so that the productivity is inevitably lowered.

Thus, various techniques for preventing foreign matter from being transferred from the transport roll to the steel strip have been studied.
For example, Patent Document 1 discloses a technique for spraying a cleaning liquid onto a surface of a bridle roll and removing foreign matter with a wiper. In this technique, the cleaning liquid is sprayed and removed by a wiper at a portion where the bridle roll is not in contact with the steel strip. However, the wear of the wiper is not always constant, and foreign matter cannot be removed in the locally worn portion. If the wiper is changed frequently, it is possible to stably remove the foreign matter, but when replacing the wiper, the operation must be stopped from the viewpoint of safety, so the productivity is lowered. Is inevitable.
Japanese Utility Model Publication No. 62-103489

  It is an object of the present invention to provide an electroplating equipment and an electroplating method capable of preventing foreign matters from firmly adhering to the surface of a steel strip by simple means and performing an efficient and uniform electroplating. To do. In particular, an object of the present invention is to provide an electroplating equipment and an electroplating method capable of preventing non-plating when an aqueous solution of methanesulfonic acid is used as a plating solution.

  The present invention is an electroplating facility for continuously performing electroplating on a steel strip, a pickling device, a water washing device, a transport roll disposed on the outlet side of the water washing device and in contact with the steel strip, A water jet nozzle that sprays cleaning water from the entrance side of the steel strip to the part where the transport roll comes into contact with the steel strip discharged from the water washing device, and electroplating that applies electroplating to the surface of the steel strip transported from the transport roll A steel strip electroplating facility.

Further, the present invention provides an electroplating method in which electroplating is continuously performed on a steel strip, in which the steel strip is pickled, then washed with water, and further, the steel strip is applied to a portion where the transport roll contacts the washed steel strip. This is a steel strip electroplating method in which cleaning water is sprayed from the entrance side of the steel strip and then the surface of the steel strip is electroplated.
The electroplating equipment and the electroplating method of the present invention exert a great effect when applied to electrotin plating or when an aqueous solution of methanesulfonic acid is used as a plating solution. Use soft water or pure water as washing water. However, it is preferable to use soft water from the viewpoint of cost. The flow rate of the washing water is preferably 1 ml / m ² or more per unit area of the portion of the conveyance roll that contacts the steel strip. Moreover, it is preferable to apply to what the conveyance roll was coat | covered with rubber | gum.

  According to the present invention, it is possible to prevent the foreign matter from firmly adhering to the surface of the steel strip by a simple means and perform uniform and good electroplating. In particular, when an aqueous solution of methanesulfonic acid that is easily affected by foreign matters such as iron hydroxide is used as a tin plating solution, it exhibits a great effect in preventing non-plating. As a result, it is possible to improve the yield and productivity of electroplating.

FIG. 1 is a layout diagram schematically showing an example of an electroplating facility to which the present invention is applied. An arrow a in FIG. 1 indicates the traveling direction of the steel strip 1. In addition, the upper surface of the steel strip 1 shown in FIG. 1 is described as an upper surface, and the lower surface is described as a lower surface.
The steel strip 1 used in the present invention is obtained by processes of cold rolling, annealing, and temper rolling, and scales are formed on both upper and lower surfaces thereof. Remove. The acid which dissolves in the pickling solution is not particularly limited, and conventionally known sulfuric acid, hydrochloric acid and the like are used.

However, as described above, the Fe hydroxide adhering to the surface of the steel strip (ie Fe (OH) ₃ ) is an obstacle to uniform and good electroplating, and in particular, electrotin plating using methanesulfonic acid as a tin plating solution. However, there was a problem that non-plating due to Fe hydroxide appeared remarkably.
On the other hand, if the present invention is applied, it is possible to prevent the foreign matter from firmly adhering to the surface of the steel strip 1 by simple means, and even when electrotin plating is performed using methanesulfonic acid as a tin plating solution. And it becomes possible to perform favorable electroplating. Therefore, the present invention can provide a great effect when applied to the case where the steel strip 1 is electroplated with methanesulfonic acid as a tin plating solution.

  Since the pickling liquid adheres to the steel strip 1 from which the scale has been removed by the pickling apparatus 2, the pickling liquid is washed away by the water washing apparatus 3. The water used in the water washing apparatus 3 uses soft water or pure water in order to ensure the cleanliness of the surface of the steel strip, but it is preferable to use soft water from the viewpoint of cost. By washing the steel strip 1 by disposing the water washing device 3 on the outlet side of the pickling device 2, the pickling solution is prevented from being taken out by the steel strip 1. The water washing device 3 may use a combination of water washing and brush removal.

  A conveying roll 4 is disposed on the exit side of the water washing apparatus 3. The transport roll 4 contacts the lower surface of the steel strip 1. The transport roll 4 transports the steel strip 1 and usually applies a driving force to prevent the steel strip 1 from slipping. Further, a water injection nozzle 5 is disposed on the entrance side of the steel strip 1 of the transport roll 4. The water injection nozzle 5 injects cleaning water to a portion where the outer peripheral surface of the transport roll 4 is in contact with the lower surface of the steel strip 1. The number of water spray nozzles 5 is appropriately determined according to the dimensions of the cleaning roll 4.

  In this way, the cleaning water enters from the entry side between the lower surface of the steel strip 1 and the outer peripheral surface of the transport roll 4 to form a water film on the outer peripheral surface of the transport roll 4. As a result, it is possible to prevent foreign matter from adhering to and accumulating on the transport roll 4 (particularly, the coating roll described later easily adheres to foreign matter), and to prevent the foreign matter from being firmly bonded to the surface of the steel strip 1. Moreover, it can prevent that a foreign material adheres to the various rolls (for example, other conveyance rolls etc.) arrange | positioned after that.

The cleaning water sprayed from the water spray nozzle 5 uses water from which Ca has been removed (so-called soft water) or pure water from the viewpoint of ensuring the cleanliness of the surface of the steel strip. However, it is preferable to use soft water from the viewpoint of cost.
The flow rate of the washing water is preferably 1 ml / m ² or more per minute per unit area (1 m ² ) of the surface of the transport roll 4 with which the steel strip 1 contacts. The reason is that if the flow rate of the cleaning water is too small, adhesion and accumulation of foreign matters cannot be prevented. More preferably, it is 1.5 ml / m ² or more per minute. The upper limit of the flow rate of the washing water is not particularly limited. However, if the cleaning water is excessively supplied, the steel strip 1 is lifted from the transport roll 4 and slip occurs during the transport. Therefore, the flow rate of the cleaning water is set in a range in which the meandering of the steel strip 1 can be prevented according to the dimensions of the steel strip 1 and the transport roll 4.

The material of the transport roll 4 is not particularly limited. However, in order to prevent the occurrence of wrinkles due to slip between the steel strip 1 and the transport roll 4, it is preferable to coat the outer peripheral surface of the transport roll 4 with acid-resistant rubber (for example, urethane rubber). .
Next, the steel strip 1 is fed to an electroplating apparatus that electroplates the surface. FIG. 1 shows an example in which electroplating is performed on each side. In FIG. 1, it is conveyed to the electroplating apparatus 7 (henceforth a lower surface electroplating apparatus) which electroplates a lower surface. At this time, since there is no strong adhesion of Fe hydroxide on the lower surface of the steel strip 1, non-plating does not occur, and a uniform electroplating layer can be formed on the lower surface of the steel strip 1.

  Further, the steel strip 1 is fed to an electroplating apparatus (hereinafter referred to as an upper surface electroplating apparatus) that performs electroplating on the upper surface. Although foreign matter may remain on the upper surface of the steel strip 1, the adhesion of these foreign matters is not strong, and after the pickling and water washing, it is already very small and small amount, and in particular, the electricity is applied one side at a time. In the case of plating, the cleaning effect when applying electroplating to the lower surface is also added, and the electroplating is hardly affected. Therefore, a uniform and good electroplating layer can be formed on the upper surface of the steel strip 1.

  As described above, by applying the present invention, it is possible to prevent the foreign matter from firmly adhering to the surface of the steel strip by a simple means and to perform uniform and good electroplating. In particular, when electrotin plating is performed using an aqueous solution of methanesulfonic acid as a tin plating solution, a great effect of preventing non-plating can be obtained.

The steel strip 1 (width 1000 mm, transport speed 350 m / min) was electroplated with the equipment shown in FIG. The pickling solution used was an aqueous solution of sulfuric acid. The transport roll 4 (diameter 400 mm, barrel length 1320 mm) was used whose outer peripheral surface was covered with urethane rubber, and six water jet nozzles 5 were arranged in the direction of the rotation axis of the transport roll 4. The amount of washing water was 1.5 ml / m ² per minute per unit area (1 m ² ) of the surface of the conveying roll 4 with which the steel strip 1 contacts. This is an invention example.

On the other hand, as a comparative example, electrotin plating of the steel strip 1 was performed without using the water jet nozzle 5 of the facility shown in FIG. Except that the amount of washing water is zero, the conditions are the same as those of the invention example, so the description is omitted.
The inventive example and the comparative example were each operated continuously for 2 days, and the presence or absence of non-plating was examined visually. As a result, the non-plating occurrence rate of the inventive example was zero (that is, there was no non-plating), whereas the non-plating rate of the comparative example was 2.1%.

The non-plating rate is a value calculated by the following equation (1).
Non-plating rate (%) = 100 x non-plating weight (ton) / total plating weight (ton) (1)

It is an arrangement figure showing typically an example of electroplating equipment to which the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel strip 2 Pickling device 3 Flushing device 4 Roll for conveyance 5 Water jet nozzle 6 Meandering correction device 7 Bottom surface electroplating device

Claims (12)

  An electroplating facility for continuously performing electroplating on a steel strip, a pickling device, a water washing device, a transport roll disposed on the outlet side of the water washing device and in contact with the steel strip, and the transport A water jet nozzle that sprays cleaning water from the entrance side of the steel strip to a portion that comes into contact with the steel strip discharged from the water washing apparatus, and electroplating on the surface of the steel strip conveyed from the conveyance roll And an electroplating apparatus for applying a steel strip.   The electroplating equipment for steel strip according to claim 1, wherein the electroplating is electrotin plating.   The electroplating equipment for steel strip according to claim 2, wherein the tin plating solution used in the electrotin plating is an aqueous solution of methanesulfonic acid.   The steel strip electroplating facility according to any one of claims 1 to 3, wherein the transport roll is coated with rubber.   The steel plate electroplating equipment according to any one of claims 1 to 4, wherein the washing water is soft water or pure water. The steel according to any one of claims 1 to 5, wherein a flow rate of the washing water is 1 ml / m ² or more per unit area of a portion of the conveying roll that contacts the steel strip. Band electroplating equipment.   In the electroplating method in which the steel strip is continuously electroplated, the steel strip is pickled, then washed with water, and the conveyance roll comes into contact with the washed steel strip from the entrance side of the steel strip. A method of electroplating a steel strip, wherein the surface of the steel strip is electroplated after spraying cleaning water.   The method of electroplating steel strip according to claim 7, wherein the electroplating is electrotin plating.   The steel strip electroplating method according to claim 8, wherein an aqueous solution of methanesulfonic acid is used as a tin plating solution used in the electrotin plating.   The steel strip electroplating method according to any one of claims 7 to 9, wherein the transport roll is coated with rubber.   The method of electroplating a steel strip according to any one of claims 7 to 10, wherein soft water or pure water is used as the washing water. The steel according to any one of claims 7 to 11, wherein the flow rate of the washing water is 1 ml / m ² or more per unit area of a portion of the conveying roll that contacts the steel strip. Band electroplating method.

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