JPH1192901A - Hot dip metal coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot dip metal coating device of an aerial pot system by which stable plating operation can be tealized. SOLUTION: The hot dip metal coating device has a holding vessel 3 of a hot dip metal coating bath 4 which executes hot dip metal coating to a metallic strip 1 by making the metallic strip 1 enter the bath from a lover part thereof and a first magnetic field generator 2 which is disposed at a lower end part of the holding vessel, generates an alternating magnetic field penetrating the metallic strip in a board thickness direction and holds the hot dip metal coating bath 4. In this case, a second magnetic field generator 6 which generates the alternating magnetic field penetrating the metallic strip in the board thickness direction is installed above the holding vessel 3 by holding the metallic strip 1 therebetween. Further, a coating weight controller 5 for controlling thickness of the hot dip metal coating on a metallic strip surface may be installed above the holding vessel by holding the metallic strip therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-dip metal plating apparatus for plating a surface of a metal strip, and more particularly to a hot-dip metal plating method for passing a metal strip from below and performing plating while holding a hot-dip metal plating bath. Related to the device.

[0002]

2. Description of the Related Art Conventionally, in hot-dip metal plating of a metal strip, a metal strip is continuously immersed from above the plating bath into a hot-dip metal plating bath, and further upward by a sink roll provided in the hot-dip metal plating bath. It has been performed by a sink roll type hot metal plating method in which the direction is changed and pulled up, and a pair of gas wiping nozzles is used to adjust the thickness of the hot metal plating layer attached to the surface.

However, in the above-described hot-dip metal plating method, it is difficult to switch the bath components frequently due to the large capacity of the plating bath, and maintenance of the sink roll immersed in the plating bath is complicated. There are problems such as abrasion due to contact between the metal strip and the sink roll, dross floating in the hot-dip metal plating bath being caught between the metal strip and the sink roll, resulting in poor product quality such as poor surface quality. there were.

[0004] In order to solve such a problem, as a plating method that does not require equipment that comes into contact with a metal band in a bath such as a sink roll, a so-called air-pot type molten metal plating apparatus that holds a molten metal plating bath in the air. There has been proposed a hot-dip metal plating method using the same. For example, JP-A-5-86446
In the publication, a moving magnetic field applying device is provided with a metal strip moving upward, and the molten metal supplied through a passage immediately below the moving magnetic field applying device is subjected to electromagnetic force of the moving magnetic field applying device. There is disclosed a molten metal plating method for a metal strip that flows upward by force and prevents the molten metal from flowing out by electromagnetic force of a high-frequency magnetic field applying device provided with a metal strip immediately below a passage therebetween.

[0005]

The adoption of such an aerial pot type molten metal plating apparatus makes it possible to reduce the capacity of the plating bath and to switch the bath components in a short time. In addition, maintenance can be reduced by eliminating the equipment in the bath, and the occurrence of poor quality on the surface of the metal strip can be expected to be reduced.

However, in order to stably hold the plating bath using the method described in Japanese Patent Application Laid-Open No. 5-86446, the distance between the metal strip and the lower opening of the molten metal holding container is made as small as possible. There is a need. However, if the interval is too small, when the steel strip is warped or the steel strip vibrates, the steel strip and the molten metal holding container come into contact with each other and a flaw is generated on the steel strip surface. Since these flaws become patterns after hot-dip metal plating, they were considered to be a cause of poor quality of the steel strip. In addition, this contact caused wear and breakage at the opening of the molten metal holding container, and the repair and replacement of the molten metal holding container frequently occurred.

Further, when the steel strip vibrates when it is discharged from the molten metal plating bath, there is a problem that the plating bath surface vibrates and a vibration pattern is generated in the plating layer adhered to the steel strip surface. . Further, when controlling the amount of plating by a plating amount control device such as a gas wiping device, the steel strip may come into contact with the plating amount control device due to warpage of the steel strip or vibration of the steel strip. For this reason, quality deterioration of the steel strip occurs, and maintenance of a plating adhesion amount control device such as a wiping nozzle is required, and productivity is greatly impaired.

As described above, when plating operation is performed using an aerial pot type hot metal plating apparatus, it is necessary to prevent the vibration of the steel strip and the warpage of the steel strip in order to stably obtain high plating quality. It was an important issue. In some cases, an alloying furnace is installed downstream of the molten metal plating apparatus, that is, above the molten metal plating apparatus, for alloying the molten metal plating layer. Ancillary equipment such as a pass line roll installed to stabilize the traveling direction of the metal strip and an auxiliary seal to prevent contamination by leaked molten metal shall be installed vertically in the hot pot type hot metal plating equipment. And the height of the entire plating apparatus is inevitably increased. For this reason, when attempting to change from a sink roll type hot-dip plating apparatus to an aerial pot type hot-dip metal plating apparatus, in an alloying furnace installed in accordance with a conventional sink roll type hot-dip metal plating bath, a predetermined In order to perform alloying annealing, it was sometimes necessary to perform a large-scale remodeling in which the alloying furnace was moved further upward.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is easy to change a molten metal plating apparatus from a sink roll system to an air pot system without requiring a significant transfer of an alloying furnace. It is an object of the present invention to provide an aerial-pot-type hot-dip metal plating apparatus that is capable of realizing a stable plating operation.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a holding container for a hot-dip metal plating bath in which a metal band moving upward is penetrated from below and hot-dip metal plating is applied to the metal band, and a lower end portion of the holding container. And a magnetic field generator for generating an alternating magnetic field penetrating in the thickness direction of the metal strip and holding the molten metal plating bath, wherein the metal strip is interposed above the holding vessel. A second magnetic field generator for generating an alternating magnetic field penetrating in the thickness direction of the metal band, or a plating amount control device for controlling the thickness of the molten metal plating on the surface of the metal band with the metal band interposed therebetween. It is a metal strip hot-dip metal plating apparatus characterized by being provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A molten metal plating apparatus for a metal strip according to the present invention comprises: a holding vessel 3 for accommodating a molten metal plating bath 4;
In order to hold the molten metal plating bath 4, the holding vessel 3
A first magnetic field generator 2 disposed at the lower end of the metal strip 1 to generate an alternating magnetic field that penetrates the metal strip 1 in the thickness direction, and a second magnetic field that generates an alternating magnetic field that penetrates the metal strip in the thickness direction of the metal strip. And a magnetic field generator 6.

In the present invention, it is preferable to further provide a plating adhesion amount control device 5 for controlling the thickness of the molten metal plating on the surface of the metal band with the metal band 1 interposed therebetween immediately above the holding container 3. Further, an alloying furnace 9 for alloying the molten metal plating layer may be provided downstream of the molten metal plating apparatus. Further, it is preferable that an auxiliary sealing device 7 for sealing the leaked molten metal and an accompanying device of a pass line roll 8 for stabilizing the traveling direction of the metal strip are installed on the upstream side of the molten metal plating apparatus. . FIG. 1 shows an example of a hot-dip metal plating apparatus of the present invention.

The holding container 3 has openings on the upper and lower sides and accommodates a molten metal plating bath 4 for applying a molten metal plating to the metal strip 1. Then, the holding container 3 penetrates the metal strip 1 that moves substantially vertically upward into the molten metal plating bath 4 in the holding container 3 from the lower opening to apply the molten metal plating. In the present invention, the molten metal to be provided for plating can be supplied from an external sub-pot using piping, or can be circulated between the holding container 6 using the sub-pot.

The hot-dip metal plating bath 4 in the holding vessel 3 is provided with an electromagnetic field generated by a first magnetic field generator 2 disposed at the lower end of the holding vessel 3 and generated by an alternating magnetic field penetrating in the thickness direction of the metal strip 1. Held by force. First magnetic field generator 2
By applying an alternating magnetic field that penetrates the metal strip 1 in the thickness direction of the metal strip 1, an induced current circulating in the width direction of the metal strip 1 is generated below the molten metal plating bath 4. Due to the action of the induced current and the alternating magnetic flux, an upward electromagnetic force is generated at the lower part of the molten metal plating bath, thereby preventing the molten metal plating bath 4 from leaking from the holding container 3.

The first magnetic field generator 2 preferably has a structure in which electromagnets each having a coil wound around an iron core are disposed on both sides of the metal strip 1. In the present invention, in order to suppress the vibration of the metal strip 1 and the warpage in the traveling direction, the metal strip 1 penetrates in the thickness direction of the metal strip 1 above the holding container 3 with the metal strip 1 discharged from the molten metal plating bath 4 interposed therebetween. A second magnetic field generator 6 for generating an alternating magnetic field is provided.

The second magnetic field generator 6 preferably has a structure in which electromagnets each having a coil wound around an iron core are provided on both sides of the metal band 1 with the metal band 1 interposed therebetween. When an alternating magnetic field penetrating the metal strip 1 in the thickness direction of the metal strip 1 is applied by the second magnetic field generator 6, an induced current is generated in the metal strip 1, and a secondary magnetic field due to the induced current is generated. A repulsive force acts on the metal band due to interference with the alternating magnetic field. The repulsive force acting on the metal strip is received from each of the electromagnets arranged on both sides of the metal strip. Further, the closer the metal strip 1 is to the electromagnet, the smaller the leakage magnetic flux is, and the greater the repulsion acting on the metal strip.

For this reason, when the metal strip is shifted from the center (reference position) and approaches one of the electromagnets, the metal strip receives a strong repulsive force from the electromagnet and is pushed to the center between the electromagnets. Such repulsion by the second magnetic field generator 6 can correct the vibration of the metal band and the warpage in the traveling direction. At the position discharged from the molten metal plating bath 4, the vibration of the metal band,
If the warpage in the traveling direction can be corrected, the interval between the metal strip 1 and the lower opening of the molten metal holding container 3 can be set to be small, and the holding of the molten metal is dramatically stabilized.

Further, when an alternating magnetic field penetrating the metal strip 1 in the thickness direction is applied to the metal strip 1 at a position discharged from the molten metal plating bath 4 by the second magnetic field generator 6, an induced current generated in the metal strip is generated. As a result, the metal strip generates heat. The heat value depends on the input power, but may be larger than the heat input in a normal-length alloying furnace. Therefore, when the molten metal plating apparatus is changed from the sink roll method to the air pot method, the shortage of the input heat due to the decrease in the furnace length of the alloying furnace is caused by the heat generated by the application of the alternating magnetic field by the second magnetic field generator 6. Can be supplemented by

By installing such a second magnetic field generator 6 on the inlet side of the alloying furnace, the furnace length of the alloying furnace can be reduced, and even in the case of conversion from a sink roll system to an air pot system, There is also an effect that the remodeling of the lower end of the alloying furnace is sufficient and the remodeling of the alloying furnace does not require a significant remodeling. Furthermore, if the vibration of the metal strip 1 is prevented by the second magnetic field generator 6, the bath surface vibration of the molten metal plating bath 4 is eliminated, and the generation of a vibration pattern generated in the plating layer is prevented.

A plating amount control device 5 for controlling the thickness of the molten metal plating layer adhered to the surface is provided above the molten metal holding container 3 with the metal strip 1 discharged from the molten metal plating bath interposed therebetween. Is done. As the plating adhesion amount control device 5, for example, a gas wiping device that controls the thickness of the molten metal plating layer attached to the surface of the metal strip by using gas injected from a pair of nozzles is preferable. Also, a plating adhesion amount control device of a method of controlling the adhesion amount by an electromagnetic force may be used,
Further, a mechanical roll drawing may be used.

If the vibration and warpage of the metal strip 1 are corrected by the second magnetic field generator 6, the contact between the plating amount control device 5 and the metal strip 1 is eliminated, and the quality of the metal strip surface is poor due to the contact. Is also resolved. The installation positions of the second magnetic field generator 6 and the plating adhesion amount controller 5 may be any positions where the metal strip is discharged from the molten metal plating bath 4.
The position is not limited to the position shown in FIG. If the problem of the scatter of the molten metal can be solved, the second magnetic field generator 6 may be installed just above the holding container 3 on the entry side of the plating adhesion amount controller 5.

[0022]

EXAMPLE Using a hot-dip hot-dip galvanizing apparatus shown in FIG. 1, hot-dip galvanizing was applied to a steel strip 1 having a thickness of 1.0 mm and a width of 1200 mm at a conveying speed of 100 mpm. A power of 2 kHz and 900 kW is applied to the first magnetic field generator 2 to apply galvanizing to the steel strip in the molten metal plating bath 4 while preventing the molten zinc from flowing down. The amount of hot-dip galvanized coating deposited on the surface of the steel strip was controlled by a gas wiping device provided immediately above the plating bath 4 as a coating weight control device 5. Next, the second magnetic field generator 6 installed on the exit side of the gas wiping device 5 was operated to correct the vibration and warpage of the steel strip. Electric power of a frequency of 400 Hz and 300 kW was supplied to the second magnetic field generator 6.

The molten metal (zinc) used for plating
Was discharged from the sub-pot installed outside to the front and back surfaces of the steel strip in the holding container via a pipe. The case where the second magnetic field generator is operated and the hot dip galvanizing is applied is the present invention, and the case where the second magnetic field generator is applied and the hot dip galvanizing is applied is the comparative example. The vibration and warpage of the steel strip were measured on the entry side of the steel strip, and the results are shown in Table 1.

[0024]

[Table 1]

From Table 1, it can be seen that in the comparative example, the steel strip had a vibration of ± 10 mm and a warpage of ± 5 mm with respect to the center position, but in the present invention, the operation of the second magnetic field generator 6 caused the steel strip to operate. Vibration of ± 0.5 mm and warpage of ± 2 mm, significantly reducing the vibration of the steel strip. In the example of the present invention, even when the distance between the steel strip 1 and the lower end opening of the holding vessel 3 is set to 18 mm to 5 mm, there is no contact between the steel strip and the holding vessel, and quality defects due to the vibration of the molten metal plating bath 4 occur. Did not.

The present invention example in which the second magnetic field generator 6 is operated to perform galvanizing and the comparative example in which the second magnetic field generator is not operated to perform galvanizing are described below. The number of times of contact between the gas wiping device 5 and the steel strip 1 generated during the hot-dip galvanizing operation was measured and is shown in FIG. From FIG. 2, in the example of the present invention in which the second magnetic field generator 6 was activated, the number of contacts was significantly reduced as compared with the comparative example in which the second magnetic field generator 6 was not activated.

Further, the heat generated in the steel strip by the alternating magnetic field applied by the installed second magnetic field generator 6 can reduce the amount of heat to be supplied to the alloying furnace, and even if the furnace length of the alloying furnace is shortened, It was found that there was no problem in alloying the plating layer. When replacing the conventional sink roll method with a hot pot type molten metal plating apparatus, it was necessary to move the inlet position of the alloying furnace 9 designed by the conventional sink roll method by 1000 mm upward, but the second magnetic field With the introduction of the generator 6, alloying was possible even if the furnace length was shortened while the position of the inlet of the alloying furnace 9 was unchanged.

[0028]

According to the present invention, the vibration and warpage of a metal strip to be subjected to hot-dip metal plating are corrected,
A hot-plated metal strip of high plating quality can be stably manufactured. In addition, productivity is improved, and an industrially remarkable effect of enabling production of a hot-dip metal-plated metal strip in an economically advantageous manner is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a hot-dip metal plating apparatus of the present invention.

FIG. 2 is a graph showing a comparison of the number of contacts between a steel strip and a gas wiping device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal strip (steel strip) 2 first magnetic field generator 3 holding vessel 4 molten metal plating bath 5 coating weight control device (gas wiping device) 6 second magnetic field generator 7 auxiliary sealing device 8 pass line roll 9 alloy Furnace

 ──────────────────────────────────────────────────の Continuing on the front page (72) Kazuya Miyagawa 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Chiba Works of Kawasaki Steel Corp. (72) Toshitane Matsukawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi Address Kawasaki Steel Corporation Chiba Works (72) Inventor Norio Tomura 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Kawasaki Steel Corporation Chiba Works (72) Inventor Atsushi Ando 5 Ishizu Nishimachi, Sakai City, Osaka Prefecture Nisshin Steel Co., Ltd.Technical Research Laboratory (72) Inventor Yasutaka Kawaguchi 5th Ishizu Nishimachi, Sakai City, Osaka Nisshin Steel Co., Ltd.Toyo Construction Headquarters 22 Hiroshima Works of Mitsubishi Heavy Industries, Ltd. (72) Inventor Tsutomu Kawamizu 4-6-22 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Company Hiroshima within the Institute

Claims (2)

[Claims] 1. A holding container for a molten metal plating bath for injecting a metal band moving upward from below and applying a molten metal plating to the metal band, and a plate thickness of the metal band disposed at a lower end of the holding container. A magnetic field generator that generates an alternating magnetic field penetrating in the direction and holds the molten metal plating bath, wherein the metal band is penetrated in the thickness direction of the metal band with the metal band interposed above the holding container. A molten metal plating apparatus for a metal strip, comprising: a second magnetic field generator for generating an alternating magnetic field. 2. The molten metal plating apparatus according to claim 2, further comprising a plating amount control device provided above the holding container, for controlling a molten metal plating thickness on the front and back surfaces of the metal band with the metal band interposed therebetween. The hot-dip metal plating apparatus for metal strips according to claim 1, wherein: