JP2938368B2 - Method and apparatus for removing foreign matter from continuous hot-dip metal plating bath surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing foreign matter from a continuous hot-dip metal plating bath surface, and more particularly, to foreign matters on a continuous hot-dip metal plating bath surface suitable for removing foreign matters deposited on a plating bath surface in a snout. The present invention relates to a removing method and apparatus.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a conventional continuous hot-dip metal plating apparatus. In FIG. 3, 1 is a steel strip, 2 is a snout, 8 is a foreign substance, 9 is a reductive annealing furnace, 10 is a plating bath, 11 is a sink roll, and 12 is a plating tank. Generally, in a continuous hot-dip metal plating apparatus having a reducing annealing furnace installed in a plating line, as shown in FIG.
And a plating bath 10 that fills a plating tank 12, a tubular snout 2 is provided, and a structure in which a steel strip 1 passes through the inside thereof is adopted. Then, the upper end of the snout 2 is placed in a reducing annealing furnace 9.
And the lower end is immersed in the plating bath 10 to fill the inside of the snout 2 with a reducing gas, thereby sealing the steel strip 1 from the atmosphere. The steel strip 1 immersed in the plating bath 10 is conveyed through the bath in the direction of the arrow from the time of immersion and turned upward by the sink roll 11 to be plated.
It is continuously plated until it is carried out from the factory.

However, the reducing gas contains a small amount of an active gas such as oxygen or moisture. The active gas reacts with the molten metal on the surface of the plating bath 10 to form oxide dross. When this deposits on the surface (bath surface) of the plating bath 10 in the snout 2, it adheres to the surface of the steel strip 1 immediately before plating. Dross floating on the surface of the bath includes products generated as described above, as well as products that float because the specific gravity is lower than the molten metal after the reaction in the bath, but these are collectively called foreign substances here. .

[0004] The problem is that the steel strip 1 which is continuously fed in the direction of the arrow while the foreign matter 8 deposited on the bath surface in the snout 2 is still attached has a remarkably high quality of the plated surface. It will be damaged. For this reason, the usual method is to stop the plating line regularly or as needed, lower the bath surface or raise the snout 2, expose the foreign matter 8 in the snout 2, and then discharge and remove the foreign matter 8 to the outside of the snout 2. However, this method requires frequent interruptions of the plating operation and requires a long time to set up and start the plating operation line, which greatly reduces the productivity.

[0005]

On the other hand, there have been proposed some techniques for removing foreign substances deposited on the bath surface of the snout without stopping the plating line. For example, JP
As disclosed in Japanese Patent Application Publication No. 188766, a cylindrical member having a spiral groove which is supported and rotated is provided in a cylinder in contact with the bath surface in the snout, and the member is rotated to remove foreign matter on the bath surface in the snout. There is a method of removing upward by taking in a spiral groove. However, foreign substances having a size exceeding the groove width cannot be taken in, and the contact area between the member and the bath surface cannot be made large. Therefore, it takes a long time to collect foreign substances generated anyway. Therefore, it is difficult to put the steel strip to practical use because surface defects of the steel strip occur.

For example, as disclosed in Japanese Patent Application Laid-Open No. 61-186463, molten metal is discharged from a discharge port provided on one side in the snout width direction toward the steel strip width direction. There is also a method of moving and collecting foreign matter on the bath surface of the snout to the opposite side. However, a reliable and simple recovery means has not yet been established, and this is also difficult to put to practical use.

[0007] As described above, the technology for removing foreign matter on the bath surface in the snout without stopping the plating line has not yet been established. Accordingly, the present invention has been made in view of the above-described various problems of the prior art, and it is possible to completely remove foreign matters deposited on a bath surface of a snout without stopping a plating line, and thus, a plated steel strip free from product defects due to foreign matter adhesion. It is an object of the present invention to provide a method and an apparatus for removing foreign substances from the surface of a continuous hot-dip metal plating bath capable of producing the same.

[0008]

SUMMARY OF THE INVENTION According to the present invention, at least a part of the curved pipe is formed by intermittently protruding and retracting a suction port of a curved pipe having a discharge port outside a snout from a bath to a bath surface of the snout. This is a method for removing foreign substances on the continuous molten metal plating bath surface, wherein foreign substances on the bath surface inside the snout are discharged outside the snout while always being filled with the molten metal liquid.

Further, the present invention provides a foreign matter reservoir provided by partitioning a part of a snout outer bath surface, a suction port provided so as to be able to protrude and retract from the bath to the snout inner bath surface, and a foreign matter reservoir in the snout outer bath surface. A curved pipe having a discharge port immersed in the bath surface, a retracting drive means for driving a retracting operation of the suction port, and a transfer means for transferring molten metal in the curved pipe to the foreign matter storage side. It is a device for removing foreign substances from the continuous hot metal plating bath surface.

[0010]

According to the present invention, the suction port of a curved tube having a discharge port outside the snout is intermittently protruded and retracted from the bath to the bath surface of the snout so that at least a part of the curved tube is always molten metal liquid. The foreign substances on the bath surface of the snout are discharged to the outside of the snout while being filled, so that the foreign materials that are continuously and easily and quickly deposited on the bath surface of the snout without breaking the seal of the snout and without obstructing the plating work at all. Can be discharged out of the snout.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an example of the apparatus of the present invention suitable for carrying out the method of the present invention, and FIG. The same members as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. 1 and 2, 3 is a suction port, 4 is a curved pipe, 5 is a transfer means such as a pump, 6 is a protruding / retracting drive means such as a piston cylinder, 7 is a foreign matter reservoir, and 31 is a throat of the suction port 3. The connection hole, 32 is the periphery of the suction port, 41 is the lowest part of the curved pipe, 42 is the discharge port, and 71 is the return hole. In addition, the suction port 3 is opened wider than the cross section of the curved tube 4, and the connection hole 31 is located below the suction port peripheral edge 32, and the lower end of the suction port peripheral edge 32 to
The connection hole 31 is inclined.

That is, as shown in FIG. 1 and FIG. 2, the apparatus of the present invention includes a foreign matter reservoir 7 provided by partitioning a part of the outer bath surface of the snout 2, and a protruding / retreating bath from the bath to the inner bath surface of the snout 2. A curved pipe 4 having a suction port 3 provided so as to be able to be disposed and a discharge port 42 immersed in the bath surface of the foreign substance reservoir 7;
A retracting drive means 6 for driving the retracting operation of the pipe, a transporting means for transporting the molten metal in the curved tube 4 to the foreign matter reservoir 7 side,
Therefore, by operating the apparatus of the present invention in the following procedure, foreign matter deposited on the inner bath surface of the snout 2 without breaking the seal of the steel strip 1 from the atmosphere. Can be easily and quickly removed from the snout 2.

First, the retracting drive means 6 is operated to move the suction port 3
Is exposed on the bath surface in the snout 2, and foreign matter 8 deposited on the bath surface is surrounded by the suction port peripheral edge 32 together with the bath liquid. Then, the molten metal in the curved tube 4 is transferred to the foreign matter reservoir 7 by the transfer means 5. At this time, the curved pipe 4 is drawn from the suction port 3 through the connection hole 31.
The level of the bath liquid taken into the bath is lowered while foreign substances are floating on the surface. When the liquid level reaches the lowest part 41 of the curved pipe, the foreign substances 8 having a lower specific gravity than the molten metal are partially removed. Most of what remains in the liquid starts to float in the liquid toward the transfer means 5 side. Here, the retreating drive means 6 is operated in the reverse direction so that the suction port 3 is immersed in the bath, so that a new bath liquid flows into the curved pipe 4, and the remaining foreign matter 8 is sent to the transfer means 5 by the force. While flushing, it merges with the molten metal liquid being transferred earlier. That is, the foreign matter 8 taken in together with the bath liquid from the suction port 3 passes through the curved tube 4, enters the foreign matter reservoir 7 from the discharge port 42 immersed in the foreign matter reservoir 7, and quickly floats on the bath surface in the foreign matter reservoir 7. I do. Then, the molten metal liquid that does not contain the foreign matter 8 returns to the plating bath 10 from the return hole 71.

As is apparent from the above description, according to the apparatus of the present invention, since at least a part of the curved pipe 4 is always filled with the bath liquid, the steel strip 1 in the snout 2 is completely removed from the atmosphere. The foreign material 8 deposited on the bath surface of the snout 2 can be removed to the outside of the snout 2 while keeping the seal. In addition, since the planar shape of the suction port 3 is arbitrary and the opening area can be made as large as possible, even a foreign substance of a large size can be easily taken in, and the arrangement position is such that the steel strip 1 can be transported in the snout 2. It may be selected appropriately within a range that does not hinder,
In addition, since the movement of the suction port 3 can be a simple moving movement, there is no need to stop the plating line, and the foreign matter removing operation itself can be performed easily and quickly. Regarding the compartment of the foreign material reservoir 7, it is sufficient to arbitrarily select a position where the collection work of the foreign material 8 can be easily performed. If an appropriate place cannot be obtained in the plating tank 12, the foreign material reservoir 7 is set as a separate container. It is also possible to provide molten metal outside the plating tank 12 and to return the molten metal to the plating bath 10 by piping from there. In addition,
It is preferable that the material of the suction port 3 and the curved tube 4 immersed in the plating bath 10 and the foreign material reservoir 7 be SUS316L (stainless steel) or steel subjected to surface spraying. Intrusion drive means 6
For example, a motor drive using a gear in addition to a known piston cylinder can be used. In the example of FIG. 1, in order to fix the moving direction of the suction port 3, the suction port periphery 32 is fixed.
Are arranged along the inner surface of the snout 2. However, various modifications can be made to the fixing method, such as providing a separate guide means.

When the apparatus of the present invention described with reference to FIG. 1 is applied to a continuous hot-dip metal plating line, the production of plated steel strip is improved by 2% as compared with before the present invention, and the occurrence of surface defects is increased. The rate was drastically reduced to 1/5, and the effect of the present invention clearly appeared.

[0016]

As described above, according to the present invention, the suction port of the curved pipe having the discharge port outside the snout is intermittently protruded and retracted from the bath to the bath surface of the snout to at least allow the curved pipe to enter and exit. Foreign substances on the bath surface of the snout are discharged out of the snout while always filling a part with the molten metal solution, so that the snout seal is not broken and the plating operation is not interrupted at all, and continuously, easily and quickly. Since foreign substances deposited on the inner bath surface can be discharged out of the snout, the productivity of continuous hot-dip metal plating is improved, and the rate of occurrence of surface defects on the steel strip due to the adhesion of foreign substances can be greatly reduced, resulting in more stable quality. This is a remarkably excellent effect that highly efficient products can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of the apparatus of the present invention suitable for carrying out the method of the present invention.

FIG. 2 is a plan view taken along the arrow AA in FIG. 1;

FIG. 3 is a sectional view of a conventional continuous hot-dip metal plating apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel strip 2 Snout 3 Suction port 4 Curved pipe 5 Transfer means 6 Elevation drive means 7 Foreign substance storage 8 Foreign substances 9 Reducing annealing furnace 10 Plating bath 11 Sink roll 12 Plating tank 31 Connection hole 32 Suction port periphery 41 Minimum part of curved pipe 42 Outlet 71 Return hole

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Motomi Imamura 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works (56) References JP-A-63-219559 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) C23C 2/00-2/40

Claims (2)

(57) [Claims] 1. A snout, wherein a suction port of a curved tube having an outlet outside a snout is intermittently protruded and retracted from a bath to a bath surface of the snout so that at least a part of the curved tube is always filled with a molten metal liquid. A method for removing foreign matter from a continuous hot-dip metal plating bath, comprising discharging foreign matter from an inner bath surface to the outside of a snout. 2. A foreign matter reservoir provided by partitioning a part of a snout outer bath surface, a suction port arranged so as to be able to protrude and retract from the snout inner bath surface from inside the bath, and a foreign object reservoir immersed in the foreign matter reservoir inner bath surface. A curved pipe having a discharge port for discharging, a retracting drive means for driving the retracting operation of the suction port, and a transport means for transporting the molten metal in the curved pipe to the foreign matter storage side. Foreign matter removal device for hot metal plating bath surface.