JP2000212714A - Device and method for continuous hot dip metal coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent ability for controlling the coating thickness, and to miniaturize a continuous hot dip metal coating device by providing a permanent magnet to generate the magnetic field in the thickness direction of a steel strip on a device to control the coating thickness of the steel strip coated with a molten metal. SOLUTION: Rotary drums 40a, 40b to be rotated in the direction opposite to the advancing direction of a steel strip 10 are arranged at the height of 50-1500 mm above the surface of a molten metal bath, an excessive molten metal on a surface of the steel strip 10 drawn out of the bath is wiped to adjust the coating thickness. The rotary drums 40a, 40b are formed of cylindrical non-magnetic bodies, a plurality of permanent magnets 140a, 140b are arranged on their circumferential surfaces in an annular manner so as to be opposite to the surface of the steel strip 10, and cooled by cooling water from a cooling water circulating device 80. The permanent magnets 140a, 140b are opposite to the surface of the steel strip 10 and different in polarity from each other, the eddy current is induced in the molten metal adhered to the surface of the steel strip 10, and the coating thickness is controlled by suppressing the force to lift the excessive molten metal in the case of moving the steel strip 10 from a bottom to a top.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous hot metal plating apparatus and a continuous hot metal plating method for continuously plating a running steel strip.

[0002]

2. Description of the Related Art Conventionally, when a molten steel plating is applied to a steel strip, as a general method, a steel strip heated and annealed in a heating furnace in a non-oxidizing atmosphere is led into a molten metal bath through a snout, The direction is changed by a sink roll immersed in a molten metal bath, pulled up and plated. Thickness control of steel strip plating is to obtain a predetermined plating thickness by blowing gas from a nozzle facing the steel strip surface and wiping off excess molten metal when pulled up above the molten metal bath tub. That is, a so-called gas wiping method is performed.

[0003] However, in the gas wiping method, when a plating treatment with a small amount of adhesion and a high-speed plating treatment are performed, the plating thickness is controlled by gas injection energy. Alternatively, it is necessary to increase the pressure, and the jet gas resonates in the slit at the tip of the nozzle, generating intense noise. For this reason, the working environment is significantly deteriorated. In addition, since the molten metal excessively attached is scattered from the end of the steel strip and the surface of the steel strip, clogging of the nozzle tip slit occurs, and the flow of the jet gas is disturbed, and a uniform plating thickness is obtained. It becomes difficult. Further, a large amount of oxidized dross is generated due to the scattering of the molten metal, so that a clean plating surface is impaired and the surface quality of the steel strip is deteriorated. Furthermore, in the gas wiping method, the nozzle may be changed according to the width of the steel strip on which the hot-dip metal plating is performed, and when switching the width of the steel strip to be plated, the line must be stopped to change the nozzle. There must be. As a result, various losses occur, such as a decrease in the operation rate of the line, a decrease in the yield, and a loss of energy required for holding the heating furnace.

In order to solve such a problem caused by the gas wiping method, moving magnetic field generating coils are arranged on both sides of a steel strip so as to face each other like a gas wiping nozzle. There has been proposed a method of wiping excess plating metal adhered to a steel strip by applying an electromagnetic force to the steel strip (Japanese Patent Publication No. 42-762).

[0005]

[Problems to be solved by the invention]
The moving magnetic field generating coil as described in JP-A-42-762 is larger in structure than a gas wiping nozzle. Therefore, in order to wipe off excess metal before the solidification of the plating layer on the steel strip surface progresses very much, the moving magnetic field generating coil needs to be as close as possible to the molten metal bath surface, but it is limited by the size limit. There was a problem such as a limited distance.

An object of the present invention is to provide a continuous hot-dip metal plating apparatus and a continuous hot-dip metal plating method which are excellent in controllability of plating thickness and small in size.

[0007]

According to the present invention, there is provided a continuous hot-dip metal plating apparatus comprising: a hot-dip metal plating apparatus for plating a steel strip with a molten metal; and a plating thickness control apparatus for controlling a plating thickness. The thickness control device includes a permanent magnet that generates a magnetic field in the thickness direction of the steel strip.

[0008] The continuous hot-dip metal plating apparatus of the present invention is a continuous hot-dip metal plating apparatus provided with a plating thickness control device for plating a steel strip with a molten metal and controlling the plating thickness. It is characterized in that a permanent magnet is provided so as to generate a force in the opposite direction of the steel strip.

A continuous molten metal plating apparatus according to the present invention is a continuous molten metal plating apparatus provided with a plating thickness control device for plating a steel strip with a molten metal and controlling the plating thickness. A member is arranged opposite to the steel strip surface, and a plurality of permanent magnets are annularly arranged in the circumferential direction in the magnetic field generating member.
The continuous molten metal plating method of the present invention is a continuous molten metal plating method for plating a molten metal on a steel strip and controlling the thickness of the plating, wherein a magnetic field is generated in a thickness direction of the steel strip by a permanent magnet, and Is controlled.

According to the continuous hot-dip metal plating method of the present invention, in a continuous hot-dip metal plating method for plating a molten steel on a steel strip and controlling the thickness of the plating, a permanent magnet is used to generate a force in a direction opposite to the forward direction of the steel strip. The thickness of the plating is controlled.

[0011] A continuous hot-dip metal plating method of the present invention is a continuous hot-dip metal plating method for plating a steel strip with a hot metal and controlling the thickness of the plating, comprising a plurality of annularly arranged permanent magnets arranged in a circumferential direction. A magnetic field is generated in the thickness direction of the steel strip by the magnetic field generating member, and a force is generated in a direction in which the steel strip moves in the opposite direction to control the thickness of the plating.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) The present invention provides a plating method capable of controlling the amount of plating applied without increasing the size of a moving magnetic field generating coil and solving the problems of the gas wiping method. It is. That is, in the present invention, a pair of rotary type drums composed of a plurality of permanent magnet pieces are disposed as opposed to the steel strip surface as plating thickness control means, and an alternating magnetic field generated by rotation of the drum is used. By generating a force in the direction opposite to the running direction of the steel strip in the excess molten metal, the plating thickness on the surface of the steel strip is controlled. By such means, a uniform plating thickness can be obtained by the plating thickness control means, and the generation of oxide dross can be suppressed, whereby the quality of the plating layer can be improved and the working environment of intense noise can be improved.

(2) In the above (1), preferably,
A chamber accommodating at least a part of the running steel strip and the rotary drum is provided, and gas supply means for supplying an inert gas into the chamber is provided.

With this configuration, the quality of the plating layer on the surface of the steel strip can be improved by wiping excess molten metal in a room in an inert atmosphere.

(4) In the above (1) and (2), preferably, the steel strip is provided with a liquid pad for ejecting the molten metal through a pump as means for supporting the steel strip in a molten metal bath. is there.

With this configuration, it is possible to suppress the quality deterioration due to the surface defect caused by the roll in the bath.

(First Embodiment) A continuous hot-dip metal plating apparatus and a method thereof according to an embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 5.

FIG. 1 is a schematic diagram of a continuous hot-dip metal plating apparatus according to one embodiment of the present invention. As shown in FIG. 1, the steel strip 10 passes through a snout 22 from a heating furnace 20, and the traveling direction of the steel strip 10 is changed to a vertical direction by a sink roll 24 arranged in a molten metal bath 30. Drive upward. A shape correcting roll 26 for correcting warpage of the steel strip 10 is disposed above the sink roll 24. The plating operation is performed while the steel strip 10 passes through the molten metal bath 30.

Here, the sink roll 24 and the shape correcting roll 26 are immersed in a molten metal bath 30, and the steel strip 10 is placed above the shape correcting roll 26.
Pulled out from inside. Although the shape correcting roll 26 may be omitted, the warp of the steel strip 10 can be corrected by installing the shape correcting roll 26.

A plating thickness control device is disposed above the shape correcting roll 26, that is, on the downstream side after the steel strip 10 has passed through the molten metal bath 30. This plating thickness control device is provided with a magnetic field generating member. In this embodiment, rotary type drums 40a and 40b are provided as magnetic field generating members. Two rotary drums 40a and 40b are arranged to face the steel strip 10 surface. The two rotary drums 40a and 40b generate a magnetic field in the thickness direction of the steel strip 10. Then, a force acts in a direction opposite to the traveling direction of the steel strip 10 due to the magnetic field in the thickness direction of the steel strip 10, and it is possible to remove excess plating solution on the surface of the steel sheet 10. That is, the plating thickness can be adjusted by adjusting the magnetic field in the thickness direction of the steel strip 10 or the force in the direction opposite to the traveling direction of the steel strip 10. Further, by rotating the rotary drums 40a and 40b in the direction opposite to the traveling direction of the steel strip 10, the plating thickness can be adjusted. It is desirable that the rotary type drums 40a and 40b wipe off excess metal on the surface of the steel strip 10 drawn from the molten metal bath before solidification proceeds very much. for that reason,
It is desirable to arrange at a height of about 50 to 1500 mm from the surface of the molten metal bath 30 so as not to be too far from the molten metal bath 30. By arranging at such a position, the plating thickness can be easily controlled in a state where the excess metal on the surface of the steel strip 10 does not solidify much (a state where the viscosity is small and soft). If the distance from the molten metal bath 30 is too great, the plating thickness will be controlled in a state where the surplus metal on the surface of the steel strip 10 has solidified (a state where the viscosity is large and hard).
Here, it is also possible to control the plating thickness by adjusting the position of the rotary type drums 40a, 40b (distance from the height of the molten metal bath 30). For example,
An elevating device may be provided on the rotary drums 40a and 40b to raise and lower the rotary drums. As described above, the steel strip 10 drawn from the molten metal bath 30 is supplied to the rotary drum 40.
When passing between a and 40b, the plating thickness is controlled.

FIG. 2 shows a rotary type drum 40.
FIGS. 5A and 5B show perspective views of the structures of FIGS. 5A and 5B, and FIG. Rotary drum 40
a and 40b have a cylindrical structure, and a permanent magnet 140 is provided on the circumferential surface of the drum so as to face the steel strip 10.
a and 140b are annularly arranged. In this embodiment, the material of the rotary drums 40a and 40b is a non-magnetic material. As the non-magnetic material, for example, copper or the like can be used. By making the material of the rotary drums 40a and 40b non-magnetic, the permanent magnets 140a and
There is no adverse effect on the 0b magnetic field. It is desirable that the rotary drums 40a and 40b be cooled. By providing a cooling device for the rotary drums 40a and 40b, permanent magnet performance can be maintained, and stable magnetic characteristics can be obtained. For example, in the present embodiment, cooling water is passed through the cooling water circulating device 80 inside the rotary type drums 40a and 40b to cool the permanent magnets 140a and 140b whose magnetic properties are degraded at high temperatures, thereby improving magnet performance. Has stabilized.

The permanent magnets 140a and 140b are
The surfaces facing each other have different polarities. For example, the permanent magnet 140a of the rotary drum 40a is
Pole, the permanent magnet 140b of the rotary drum 40b is S
When the polarity is the polarity, a magnetic field is generated in the direction from the rotary drum 40a to the rotary magnetic drum 40b.
That is, a magnetic field is generated in the thickness direction of the steel strip 10. Steel strip 1
An eddy current is induced in the molten metal adhered to the surface of the steel strip 10 by the magnetic field perpendicular to zero. The magnetic field generated by the rotary drums 40a and 40b acts on the eddy current, so that a force (steel) is used to suppress the force of lifting the excess molten metal caused when the steel strip 10 moves upward from below. The force in the direction opposite to the movement of the band 10) acts, and the plating thickness can be controlled. Here, by rotating the rotary type drums 40a and 40b, a moving magnetic field acts, and the above-described force is generated, thereby making it easy to control the plating thickness. A plurality of permanent magnets 140a, 140b annularly arranged on the circumferential surface of the rotary drums 40a, 40b
When the rotary drums 40a and 40b rotate, the permanent magnets 140a and 140b closest to the steel strip 10 only need to have different polarities, and the adjacent magnets on one drum surface have the same or different polarities. May be. That is, a magnetic field may be generated in the thickness direction of the steel strip 10 by the permanent magnet. As described above, since the wiping is performed by the magnetic force of the permanent magnet, there is no noise or the like generated from the slit portion of the nozzle in the gas wiping method. Furthermore, adaptation to high-speed plating equipment is possible. In addition, since the wiping is performed by the magnetic force of the permanent magnet, the molten metal on the surface of the steel strip does not scatter, the generation of oxide dross is suppressed, a clean plating surface can be obtained, and the quality of the steel strip surface is improved. can do. Further, since a permanent magnet is used as the magnetic field generating means, the rotary drums 40a, 40b
Is simple, and the diameter of the device can be reduced.

As shown in FIG. 5, the rotary drum 4
Numerals 0a and 40b are rotatably supported by bearings, and have driving means 70 for driving the rotation speed at a variable speed via a spindle or the like. The rotary drums 40a and 40b have a gap 6 between them and the steel strip 10.
0, and an adjusting means 65 for the gap 60 is provided.

By increasing the number of revolutions, that is, the frequency, of the rotary drums 40a and 40b, the induced electromotive force induced on the surface of the steel strip 10 increases, and the eddy current on the surface of the steel strip 10 increases. As a result, the scraping force acting on the excess molten metal adhering to the surface of the steel strip 10 increases, and the plating thickness decreases. Conversely, by reducing the number of revolutions of the rotary drums 40a and 40b, the induced electromotive force induced on the surface of the steel strip 10 decreases, and the steel strip 1
The eddy current on the zero surface decreases, the scraping force acting on the excess molten metal adhering to the surface of the steel strip 10 decreases, and the plating thickness increases. As described above, the plating thickness can be easily controlled by adjusting the number of rotations of the rotary drums 40a and 40b.

The magnetic force is increased by reducing the gap 60 between the rotary drum and the steel strip 10.
As a result, the scraping force acting on the excess molten metal increases, and the plating thickness decreases. Conversely, increasing the gap 60 reduces the magnetic force. As a result, the scraping force acting on the excess molten metal is reduced, and the plating thickness is increased. As described above, the rotary drum 40
The plating thickness can be easily controlled by adjusting the gap between a and 40b.

By such means, the rotary drum 4
The plating thickness can be reduced by increasing the number of rotations of Oa and 40b or reducing the gap with the steel strip. Conversely, the plating thickness can be increased by lowering the number of rotations of the rotary drums 40a and 40b or by increasing the gap with the steel strip.

The rotary type drum 40 described above
The adjustment of the plating thickness is also possible in the adjustment of the arrangement height of the a and 40b.

The eddy current induced in the molten metal on the surface of the steel strip 10 passes through the molten metal and is also induced in the steel strip 10 itself. The eddy current induced in the steel strip 10 itself is
Force in a direction that hinders the direction of travel of the vehicle. Thereby, the rotary type drums 40a and 40b can also have a function of holding the back tension on the steel strip 10 in the plating thickness control unit.

Steel strip 1 drawn from molten metal bath 30
0 and the rotary drums 40a, 40b are disposed in the chamber 42. The inert gas is supplied to the heating furnace 20 and the chamber 42 from the inert gas supply device 44 so as to be slightly higher than the outside pressure.
As the inert gas, a mixed gas of H ₂ + N ₂ (a mixed gas of hydrogen and nitrogen) or the like can be used. Further, a gas shield mechanism 46 is disposed at an opening of the chamber 42 from which the steel strip 10 is carried out. The gas pressure in the chamber 42 is adjusted by ejecting an inert gas from the shield mechanism. I have. Since the wiping operation can be performed in the chamber as described above, the atmosphere can be controlled and the plating surface quality can be improved. In addition, because it is wiping work in the chamber,
A clean working environment can be realized.

As described above, the alternating magnetic field is induced in the molten metal adhering to the surface of the steel strip 10 by the pair of rotary drums disposed opposite to the surface of the steel strip 10, and the magnetic force is generated by the steel strip 10. When moving out from the molten metal bath 30 and moving upward from below, the plating thickness can be controlled by acting to suppress the force for lifting the molten metal, and the plating thickness control depends on the magnetic force. From
The problem of the conventional gas wiping method using gas injection from a nozzle can be solved.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG.

FIG. 3 is a schematic view of a continuous hot-dip metal plating apparatus used in this embodiment. The continuous hot-dip metal plating apparatus is different from the first embodiment in that the steel strip 1 having passed through the snout 22 is used.
0 is immersed in the molten metal bath 30;
The traveling direction can be changed vertically by the middle sink roll 24. In this embodiment, the configuration is such that the sink roll in the molten metal bath 30 is not used. The steel strip 10 that has passed through the snout 22 is immersed in the molten metal bath 30 and the molten metal bath 3
The traveling direction of the steel strip 10 is inverted with a semicircular trajectory and guided vertically upward. With this configuration, since the sink roll 24 in the molten metal bath 30 is not used, quality deterioration due to the occurrence of surface defects due to contact with the roll of the steel strip 10 can be suppressed.

Third Embodiment A third embodiment of the present invention will be described below with reference to FIG.

FIG. 4 is a schematic diagram of a continuous hot-dip metal plating apparatus used in this embodiment. The continuous hot-dip metal plating apparatus is different from the first embodiment in that the steel strip 1 having passed through the snout 22 is used.
0 is immersed in the molten metal bath 30;
Although the traveling direction can be changed vertically by the inside sink roll 24, in this embodiment, the configuration is such that the sink roll in the molten metal bath 30 is not used. Further, the liquid pad 50
By adopting the structure described above, a configuration that does not use a roll in a molten metal bath can be realized.

The steel strip 10 having passed through the snout 22 is immersed in a molten metal bath 30, the traveling direction of the steel strip 10 is reversed with a semicircular orbit in the molten metal bath 30, and is guided vertically upward. The upward movement of the steel strip 10 is maintained in the plate width direction by the molten metal ejected by the fluid pad 50 arranged in the molten metal bath. Molten metal that is ejected from the fluid pad and maintains the deflection in the plate width direction is supplied by the pump 51.

With this configuration, since the sink roll 24 in the molten metal bath 30 is not used, a decrease in quality due to occurrence of surface defects due to contact with the roll of the steel strip 10 can be suppressed. Further, since no rolls are arranged in the molten metal bath 30, stoppage of the line due to replacement of the rolls is suppressed, and continuous operation can be performed for a long time.

According to the embodiment described above, the plating thickness can be controlled with the rotary type drum smaller than the moving magnetic field generating coil, eliminating the problem of the conventional gas wiping method, and the roll in the plating bath can be eliminated. Thus, continuous operation can be performed for a long time, and the effect of improving the yield can be obtained.

[0038]

According to the present invention, it is possible to obtain a small-sized continuous hot-dip metal plating apparatus and a continuous hot-dip metal plating method with excellent controllability of plating thickness.

[Brief description of the drawings]

FIG. 1 is a schematic view of a continuous hot-dip metal plating apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a rotary drum structure according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a continuous hot-dip metal plating apparatus according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of a continuous hot-dip metal plating apparatus according to an embodiment of the present invention.

FIG. 5 is a top view of a rotary drum structure according to an embodiment of the present invention.

DESCRIPTION OF SYMBOLS 10 ... steel strip, 20 ... heating furnace, 22 ... snout, 24 ... sink roll, 26 ... shape correction roll, 30 ... molten metal bath, 32 ... molten metal, 40 a, 40 b ... rotary drum, 42 ... chamber, 44 ... inert gas supply device,
46: gas shield mechanism, 50: liquid pad, 51: pump, 60: gap, 65: gap adjusting means, 70
... Rotary drum driving means, 80 ... Cooling water circulation device, 140a, 140b ... Permanent magnet.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruo Yamaguchi 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (72) Inventor Nao Hashimoto 3-chome, Sachimachi, Hitachi-shi, Ibaraki No. 1 F term in Hitachi, Ltd. Hitachi Plant (reference) 4K027 AA02 AA22 AC59 AD15 AD29 AE23

Claims (9)

[Claims] 1. A continuous molten metal plating apparatus provided with a plating thickness control device for plating a steel strip with a molten metal and controlling a plating thickness, wherein the plating thickness control device applies a magnetic field in a thickness direction of the steel strip. A continuous hot-dip metal plating apparatus comprising a permanent magnet to be generated. 2. A continuous molten metal plating apparatus provided with a plating thickness control device for plating a steel strip with a molten metal and controlling a plating thickness, wherein the plating thickness control device applies a force in a direction in which the steel strip advances. A continuous hot-dip metal plating apparatus, wherein a permanent magnet is provided so as to generate the pressure. 3. A continuous molten metal plating apparatus provided with a plating thickness control device for plating a steel strip with a molten metal and controlling the plating thickness, wherein the plating thickness control device has a magnetic field generating member facing the steel strip surface. Wherein a plurality of permanent magnets are annularly arranged in the circumferential direction in the magnetic field generating member. 4. The continuous hot-dip metal plating apparatus according to claim 3, wherein the magnetic field generating members are arranged as rotary drums opposite to the steel strip surface. 5. The continuous hot-dip metal plating apparatus according to claim 4, wherein a driving device for rotating and driving each of the rotary drums, a lifting and lowering device for lifting and lowering each of the rotary drums, and each of the rotary type plating devices A continuous hot-dip metal plating apparatus provided with at least one of interval adjusting devices for adjusting an interval between drums. 6. A continuous molten metal plating method for plating a molten steel on a steel strip and controlling the thickness of the plating, wherein a magnetic field is generated in a thickness direction of the steel strip by a permanent magnet.
A continuous hot-dip metal plating method comprising controlling the thickness of plating. 7. A continuous molten metal plating method for plating a molten metal on a steel strip and controlling the thickness of the plating, wherein a force is generated in a direction opposite to the forward direction of the steel strip by a permanent magnet.
A continuous hot-dip metal plating method comprising controlling the thickness of plating. 8. A continuous molten metal plating method for plating a molten metal on a steel strip and controlling the thickness of the plating, wherein the steel strip is provided by a magnetic field generating member having a plurality of annularly arranged permanent magnets arranged in a circumferential direction. A continuous hot-dip metal plating method comprising: generating a magnetic field in the thickness direction of the steel strip; 9. The continuous hot-dip metal plating apparatus according to claim 8, wherein the magnetic field generating member is a rotary drum, a step of rotating and driving each of the rotary drums, and a step of lifting and lowering each of the rotary drums. And controlling the thickness of the plating by at least one of the steps of adjusting the interval between the rotary drums.