JP2000290761A - Continuous hot-dipping metal coating facility and using method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a defective coating caused by metallic vapor developed in a snout in the continuous hot-dipping metal coating equipment. SOLUTION: A gas seal part 6 is arranged on the way of the inner part of the snout 2 and also, a gas exhaust tube 10 is connected with the snout part between the gas seal part and a hot-dipping metal coating bath A and the gas-containing metallic vapor in the snout can be exhausted through the gas exhaust tube 10. Further, a charging hole and a taking-out hole of a pig for cleaning the inner wall of the tube are arranged and thus, the solidified material of the metallic vapor precipitated in the gas exhaust system can easily be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous hot-dip metal plating facility capable of performing continuous hot-dip metal plating while preventing occurrence of plating defects caused by metal vapor generated in a snout, and a method of using the same. Things.

[0002]

2. Description of the Related Art In a continuous galvanizing line for steel strip,
The steel strip whose surface has been cleaned is continuously annealed in a heated and soaking zone, then cooled to a predetermined temperature in a cooling zone, and then introduced into a hot dip galvanizing tank for hot dip galvanizing. Usually, the annealing-cooling step is in a reducing atmosphere, and the steel strip that has been treated in this reducing atmosphere is introduced into the hot-dip galvanizing tank as it is. Is provided with a duct for passing a steel strip called a snout. The tip of the snout is immersed in the plating bath in the hot dip coating bath, and the steel strip that has exited the cooling zone passes through the snout and enters the hot dip coating bath as it is.

Further, a sink roll is installed in the hot dip coating tank, and a steel strip which has entered the hot dip coating tank from diagonally above through a snout is turned by the sink roll and rises vertically. The steel strip drawn out from the hot-dip plating tank in this manner is cooled after the amount of plating applied is adjusted by a basis weight adjusting means such as a gas wiping device, and then sent to a subsequent process.

Since the inside of the snout is a reducing atmosphere, an oxide film is not easily formed on the surface of the molten zinc bath at the tip of the snout extending into the hot-dip plating bath. No strong oxide film is formed on the surface, only a relatively thin oxide film is formed. Therefore, when the steel strip enters the molten zinc bath through the snout, the molten metal may be exposed to the bath surface due to vibration or the like. In this case, the molten metal in the liquid phase is vaporized in the reducing atmosphere gas in the snout until the saturated vapor pressure at the temperature being heated.

[0005] The vaporized molten metal vapor reacts with a trace amount of oxygen present in the reducing atmosphere to form an oxide, or the vaporized molten metal forms an oxide in the furnace or snout in the previous process. When the temperature reaches a region where the melting temperature is lower than or equal to the melting temperature, the metal cannot exist in a vapor state, so that the phase changes to a liquid phase or solid phase metal. In particular, in a region where the melting temperature of the metal is lower than the melting temperature of the metal in the cooling zone or the snout in the previous process, the vapor of the molten metal precipitates and becomes metal powder, and adheres to the furnace wall inner surface or the snout inner surface of the cooling zone.

[0006] When these oxides and metal powder adhere to the steel strip passing through the cooling zone or the snout, the plating becomes non-uniform or non-plated, resulting in quality defects in the plated steel sheet. Further, when the oxide falls on the molten zinc bath surface in the snout, the oxide does not redissolve because the melting temperature of the oxide is higher than the molten zinc temperature. Also, when the metal powder that has adhered to the inner surface of the snout falls onto the molten zinc bath surface in the snout, the metal powder is redissolved if the metal is almost the same as the molten metal. In the case of (1), since impurities are mixed in the metal powder, these do not often re-dissolve on the bath surface.

[0007] As described above, the foreign matters composed of oxides and metal powders which are not re-dissolved on the surface of the molten zinc bath in the snout are formed of molten zinc generated by the steel strip entering the plating bath. I move in the direction of the steel strip along the flow,
It adheres to the steel strip surface. The foreign matter thus adhered to the steel strip surface acts as a factor that inhibits the plating of the steel strip immersed in the plating bath, resulting in a reduction in the plating thickness, non-uniform plating, and non-plating. This causes quality defects in the plated steel sheet.

Conventionally, several proposals have been made to solve such a problem, and these proposals can be roughly classified into two methods. The first method is to continuously flow a molten metal into a snout as disclosed in JP-A-2-70049, JP-A-4-120258, JP-A-5-279827, etc. It is a method of removing foreign matter that has fallen by constantly securing the metal bath surface, and in this method, a pump is provided in or on the bath as a means for updating the molten metal in the snout,
The method of flowing molten metal into the snout by this pump is adopted.

A second method is disclosed in Japanese Patent Laid-Open No. 6-4961.
As shown in Japanese Patent Publication No. 0, a gas seal portion (restricted portion) that is in contact with or not in contact with a steel strip is provided in the snout, and a reducing gas is supplied into the snout between the gas seal portion and the molten metal bath. This is a method for preventing dross from being generated on the molten metal bath surface in the snout.

[0010]

However, the first method among these prior arts does not prevent the formation of oxides and metal powders by metal vapor, and therefore, fundamentally solves the problems caused by these. In addition, the occurrence of plating defects due to oxides and metal powders is unavoidable, though to varying degrees. In addition, the second method does not prevent the generation of metal powder due to metal vapor, and therefore has the same problem as the first method.In addition, dross adheres to the steel strip at the snout portion, and this melts. If the gas stays in the portion where the metal and the gas in the snout are in contact with the steel strip, a surface defect of the plated steel sheet occurs, and means for eliminating the defect must be provided separately.

Accordingly, an object of the present invention is to solve the problems of the prior art and to provide a continuous hot-dip metal plating equipment and a method of using the same, which can effectively prevent plating defects caused by metal vapor generated in a snout. Is to do.

[0012]

In view of the above-mentioned problems in the prior art, in order to always keep the molten metal bath surface in the snout clean and prevent plating surface defects, metal vapor generated in the snout must be removed. It turns out that it is necessary to remove immediately. Therefore, in the present invention, the metal vapor generated in the snout can be quickly discharged to the outside of the snout, and the solidified metal vapor deposited in the discharge system can be easily removed. is there.

That is, the features of the present invention are as follows. [1] A continuous heat treatment furnace for continuously heat-treating a metal strip, a hot-dip bath into which the metal band heat-treated in the continuous heat-treatment furnace is introduced, and a space between the continuous heat-treatment furnace outlet and the hot-dip bath. In a continuous hot-dip metal plating facility having a snout provided, a gas seal portion is provided in the middle of the snout, and a gas exhaust pipe is connected to a snout portion between the gas seal portion and the hot-dip plating bath. A continuous hot-dip metal plating facility wherein gas containing metal vapor in a snout can be exhausted through an exhaust pipe.

[2] In the continuous hot-dip metal plating equipment of the above [1], a pipe inner wall cleaning pig loading port is provided at an arbitrary location on the gas exhaust side and an optional location on the snout connection side in the longitudinal direction of the gas exhaust pipe. Continuous hot-dip metal plating equipment characterized by having an outlet. [3] In the continuous hot-dip metal plating equipment of the above [2], a pipe inlet for cleaning the inner wall of the pipe is provided at an arbitrary location on the gas exhaust side in the longitudinal direction of the gas exhaust pipe, and the pipe is installed at an arbitrary location on the snout connection side. Continuous hot-dip metal plating equipment characterized by providing an outlet for a wall cleaning pig. [4] In the continuous hot-dip metal plating equipment of the above [2] or [3], a gas supply unit for feeding a pig pressure is provided on the inlet side of the pig for cleaning the inner wall of the pipe, and the outlet side of the pig for cleaning the inner wall of the pipe is provided on the outlet side. A continuous hot-dip metal plating facility comprising gas suction means.

[5] A method of using the continuous hot-dip metal plating equipment according to any one of the above [2] to [4], wherein a groove is formed on the outer peripheral surface along the pig moving direction at an appropriate interval. The pig for cleaning the inner wall of the pipe is inserted from the inlet of the gas exhaust pipe, and the inside of the gas exhaust pipe is pressure-fed and removed from the outlet to remove metal powder attached to the inner wall of the gas exhaust pipe. How to use continuous hot metal plating equipment. [6] The method for use according to the above [5], wherein a pipe for cleaning the inner wall of the pipe is used in which the groove on the outer peripheral surface is spirally formed with respect to the pig axis direction or formed at an appropriate inclination. How to use the equipment.

[0016]

1 to 4 show an embodiment in which the present invention is applied to a continuous hot-dip galvanizing equipment for steel strip. FIG. 1 is a cross-sectional view of a snout and a hot-dip galvanizing tank. FIG. 2 is a partially enlarged sectional view of a gas seal portion provided in a snout, FIG. 3 is a front view showing a snout and a part of a gas exhaust pipe, and FIG. 4 is an explanatory view showing substantially the entire gas exhaust pipe. It is.

In the drawing, 1 is a continuous annealing furnace (continuous heat treatment furnace) having a cooling zone on the outlet side, 2 is a snout, 3 is a hot-dip bath, 4 is a sink roll, 5 is a gas wiping device, and a steel strip. S is heat-treated (annealing-cooling) under predetermined conditions in a continuous annealing furnace 1, passed through a snout 2, guided to a hot-dip plating tank 3, further changed in direction by a sink roll 4, and turned into a hot-dip plating tank 3. After being guided upward, the gas wiping device 5 adjusts the basis weight of the plating, and then is guided to the next step.

In such a continuous hot-dip galvanizing facility, a gas seal portion 6 is provided in the snout 2 in the middle thereof. The gas seal unit 6 of the present embodiment is provided with a gas seal device 7 including a seal plate 8 arranged so as to surround a steel strip S passing therethrough. Usually, the snout 2 is composed of an upper member 20 on the continuous annealing furnace side and a lower member 21 on the hot-dip plating tank side, and the lower member 21 whose lower end side is immersed in the plating bath A of the hot-dip plating tank 3.
Has a material and structure with enhanced corrosion resistance to molten metal, but because it cannot withstand long-term continuous use,
It is designed to be replaced regularly.

The gas sealing device 7 in the present embodiment
Is installed at the connection between the upper member 20 and the lower member 21 of the snout 2, more specifically, at the flange portion 22 of the connection. This is because the gas seal portion 6 (gas seal device 7) is provided at the connection between the upper member 20 and the lower member 21 of the snout 2 so that the upper member 2 that is not periodically replaced is provided.
Since the metal vapor does not diffuse to the 0 side, there is no danger that metal powder will adhere to the inner surface. On the other hand, even if metal powder due to metal vapor adheres to the inner surface of the lower member 21, This is because the metal powder can be removed at the time of the periodic replacement because the metal powder is replaced.

It is desirable from the viewpoint of gas sealing properties that the gap between the steel plate S and the tip of the sealing plate 8 constituting the gas sealing device 7 be as small as possible. If the width is excessively narrow, the steel strip may be in contact with the steel strip due to the meandering of the steel strip. Therefore, the sealing plate 8 does not come into contact with the steel strip to be passed in consideration of the maximum threading width and the maximum meandering width of the steel strip. It is necessary to make such a configuration. Normally, the interval between the end of the seal plate 8 and the standard threading position of the steel strip S is set to about 20 mm in consideration of the thickness of the steel strip, the maximum catenary and the meandering width of the steel strip depending on the tension, and the like. Is done.

In this embodiment, the seal plate 8 is configured to be rotatable (the opening degree can be adjusted), so that the seal plate 8 can be rotated.
The distance between the tip of the steel strip S and the steel strip S can be changed. The seal plate 8 is preferably made of a heat-resistant metal such as stainless steel. As the gas seal device 7 provided in the gas seal portion 6, various types other than those shown in the present embodiment can be employed. For example, a roll type seal device having a driving device, a metal band, A sealing device or the like that detects the position of the passing plate and follows the position may be used.

A gas outlet 9 is provided in the snout portion (the lower member 21 of the snout 2 in this embodiment) closer to the hot-dip bath than the gas seal portion 6, and a gas exhaust pipe 10 is provided in the gas outlet 9. The gas exhaust port 9 and the gas exhaust pipe 10 allow the gas containing the metal vapor in the snout (the snout portion closer to the hot-dip plating tank than the gas seal portion 6) to be exhausted.

The position and number of the gas exhaust ports 9 are arbitrary. However, in the present embodiment, the gas exhaust ports 9 are provided at two places in the width direction of the lower member 21 constituting the snout 2. A portion near the end of the gas exhaust pipe 10 is connected to the gas exhaust port 9 via a connection pipe 13. The gas exhaust pipe 10 is not provided with a special gas suction means such as a blower, and the gas exhaust pipe 10 is usually connected to a chimney (not shown) for air emission. In the facility of the present invention, the gas (gas containing metal vapor) in the snout can be easily discharged through the gas exhaust port 9 and the gas exhaust pipe 10 by the furnace pressure difference and the chimney draft force without using any special gas suction means. it can. In order to effectively obtain the above-mentioned chimney draft force, the height of the chimney to which the gas exhaust pipe 10 is connected is 2 mm.
It is preferably 0 m or more.

Simulation results of the sealing effect of the gas seal portion 6 installed in the snout 2 and the exhaust effect of the gas exhaust pipe 10 show that, for example, when the line speed of the steel strip S is about 120 mpm, When there is no gas seal portion in the snout or a gas exhaust pipe for exhausting gas from the snout as in the equipment of the present invention, the gas in the snout is stirred upward along with the steel strip passing therethrough, thereby moving upward. However, as in the present invention, the gas seal portion 6 is provided on the way in the snout 2.
When the gas exhaust port 9 (and the gas exhaust pipe 10 connected thereto) is provided in the snout portion on the hot-dip plating tank side with respect to the gas seal portion 6, the upper and lower portions of the gas seal portion 6 are included. It has been found that the gas in the snout flows downward and is easily exhausted from the gas exhaust port 9.

The gas flow in the snout 2 is as follows.
The pressure difference between the inside of the continuous annealing furnace and the exhaust side of the gas exhaust pipe 10 is 5
When the water column is equal to or larger than the mm water column, the gas is formed stably, and the gas in the snout 2 is smoothly exhausted from the gas exhaust port 9 below the gas seal portion 6. On the other hand, if the pressure difference becomes excessively large, the amount of gas flowing through the gas seal portion 6 becomes too large, so that the amount of gas in the furnace may increase in operation, or the control of the furnace pressure may be hindered. In order to cause a problem, it is preferable that the pressure difference be about 5 to 10 mm water column. However, it is needless to say that unless the pressure is higher than the atmospheric pressure, air flows in from each seal portion of the apparatus, which is not preferable.

On the other hand, the gas exhausted from the snout 2 through the gas exhaust pipe 10 contains metal vapor.
When this metal vapor is cooled during exhaustion by the gas exhaust pipe 10, it precipitates and becomes a solid phase metal. It is necessary to collect and remove the solid phase metal (metal powder) that accompanies the gas with a filter or a cyclone. Therefore, a dust removal device (such as a filter or a cyclone) is provided downstream of the gas exhaust pipe 10. (Not shown) is provided to remove and collect metal powder contained in the gas.

However, a part of the metal vapor solidified during the exhaust by the gas exhaust pipe 10 adheres and accumulates on the inner wall of the pipe, and if left undisturbed, the gas exhaust pipe 10 is clogged.
As a method of removing the metal powder attached to the inner wall of the pipe, a method of blowing a gas at a high speed into the pipe and peeling out the attached metal powder with the gas pressure to remove the metal powder is also considered.
A sufficient removal effect cannot be expected only by blowing such a gas. Therefore, in the facility of the present invention, the gas exhaust pipe 10
In order to remove the metal powder adhering to the inner wall of the pipe by feeding a pig for cleaning the inner wall of the pipe into the inside, the gas exhaust pipe 10 has a structure capable of feeding the pig for cleaning the inner wall of the pipe to the inside thereof.

The gas exhaust pipe 10 is provided with an inlet 11 and an outlet 12 for a pipe inner wall cleaning pig at an arbitrary location on the gas exhaust side and an optional location on the snout connection side in the longitudinal direction. In the present embodiment, as shown in FIG. 4, the charging port 11 is provided on the gas exhaust side in the gas exhaust pipe longitudinal direction.
However, an outlet 12 is provided at the pipe end on the snout connection side. A lid is detachably attached to the inlet 11 and the outlet 12 so as to be detachable or openable.

The gas exhaust pipe 10 of the present embodiment comprises a horizontal pipe section 100, a vertical pipe section 101, and a horizontal pipe section 102 from the snout connection side to the gas exhaust side, and a curved pipe is provided between these pipe sections. Parts 103 and 104 are interposed. An inlet pipe 14 is continuously provided on the upper end extension of the vertical pipe portion 101, and the upper end of the inlet pipe 14 constitutes the inlet 11. In such a structure, the curved tube portion 1
04 and the horizontal pipe portion 102 are out of the range of the pipe inner wall cleaning by the pipe inner wall cleaning pig, but most of the adhesion of the metal powder to the pipe inner wall due to the deposition of the metal vapor contained in the gas is caused by the vertical pipe portion 101 and There is no particular problem because it occurs in the pipe on the upstream side. In addition, a gas supply unit 15 is provided in the charging port 11 for injecting a gas for pig feeding, and a gas suction unit (not shown) for assisting the pig feeding is provided on the outlet 12 side. I have.

On the extension of the lower end of the vertical tube portion 101, a discharge portion 16 (discharge portion) for dropping / discharging the metal powder so that the metal powder separated from the inner wall of the vertical tube portion does not clog the tube. Pipes). In addition, this discharging unit 1
At the connection between the gas exhaust pipe 10 and the gas exhaust pipe 10 (the curved pipe section 103), a guide 17 is provided to prevent the pipe inner wall cleaning pig that is pressure-fed in the gas exhaust pipe 10 from entering the exhaust section 16. ing. The guide 17 may have any configuration as long as it can smoothly guide the pipe inner wall cleaning pig in the direction of the horizontal pipe section 100 and can drop and discharge the metal powder into the discharge section 16 without any problem. For example, a metal plate having a width of about several mm may be fixed by welding. Also, in the case where there is another branch pipe such as the discharge section 16 for monitoring the inside of the pipe, and there is a possibility that the pig for cleaning the inner wall of the pipe may enter the branch pipe as it is, as described above. Preferably, a guide is provided.

In the equipment of the present invention, the inlet 11 (or outlet 12) may be provided on either the gas exhaust side or the snout connection side of the gas exhaust pipe 10, but the metal powder adhering to the inner wall of the pipe is efficiently removed. In order to remove the pig, it is preferable that the pig for cleaning the inner wall of the pipe is pressure-fed in the gas exhaust pipe 10 in the direction opposite to the gas exhaust direction. It is preferable to provide the outlets 12 on the snout connection side, respectively. Also, as in the present embodiment, the gas exhaust pipe portion on the gas exhaust side (vertical pipe portion 101)
In a facility where the pipes rise upward, a considerable amount of gas pressure is required to pump the loaded pipe for cleaning the inner wall of the pipe from the snout connection side to the gas exhaust side. Burden is required. Therefore, from this point as well, as in the present embodiment, the pig inlet 11
Is preferably provided on the gas exhaust side and the pig outlet 12 is provided on the snout connection side.

There is no particular limitation on the material and shape of the pipe inner wall cleaning pig used in the facility of the present invention, but a pig whose whole or at least the outer surface is made of rubber is particularly preferable from the viewpoint of pumpability in the pipe. It is. The pig may have any shape such as a sphere, an oval, a barrel, and a shell.

In order to efficiently remove metal powder adhering to the inner wall of the pipe by feeding the pig for cleaning the inner wall of the pipe in the gas exhaust pipe 10, the outer surface of the pig removes the metal powder adhering to the inner wall of the pipe. Preferably, the action of scraping off and the action of scraping off metal powder attached to the pipe inner wall by the dynamic pressure of the gas blown at high speed from between the pig and the pipe inner wall are combined, and a synergistic effect of such action By this effect, metal powder attached to the inner wall of the gas exhaust pipe can be efficiently removed. In order to obtain the above effect, it is necessary to optimize the gap between the pig and the inner wall of the pipe.
mm <[gas exhaust pipe inner diameter−pig outer diameter] ≦ 5 mm.

Even if the inner diameter of the gas exhaust pipe and the outer diameter of the pig are in the above-mentioned relationship, if the gap between the pig and the inner wall of the pipe is relatively narrow due to the small difference between the two, the distance between the pig and the inner wall of the pipe can be reduced. Clogging (biting) of the metal powder may occur in between, which may hinder smooth movement of the pig. To prevent this,
For example, as shown in FIG. 5, it is effective to provide grooves 19 along the pig moving direction (longitudinal direction) at appropriate intervals on the outer peripheral surface of a rubber-made (all or at least the outer surface is made of rubber) pig, as shown in FIG. The groove 19 forms a gap between a part of the outer peripheral surface of the pig and the inner wall of the pipe, and the action of gas flowing through the gap (groove) causes clogging (biting) of metal powder between the outer surface of the pig and the inner wall of the pipe. ) Can be prevented.

When the groove 19 is provided spirally or at an appropriate inclination with respect to the axial direction of the pig as shown in FIG. 5, a rotational force is applied to the pig during pressure feeding by the groove 19. Thus, the effect of removing the metal powder attached to the inner wall of the pipe can be further enhanced. Although the width and the interval of the grooves 19 are arbitrary, for example, by providing the grooves 19 having a width of about 2 mm at a pitch of about 20 mm in the circumferential direction of the pig, the pigs are extremely smoothly pumped in the gas exhaust pipe 10. be able to.

Next, a method of using the equipment of the present invention will be described by taking this embodiment as an example. In the continuous hot-dip plating operation in the facility of the present invention, the inlet 11 and the outlet 12 of the pig for cleaning the inner wall of the pipe provided in the gas exhaust pipe 10 are normally closed and connected to the snout 2 (lower member 21). The gas (gas containing metal vapor) inside the snout portion below the gas seal portion 6 (on the side of the hot-dip plating bath) than the gas seal portion 6 is exhausted through the gas exhaust pipe 10. As described above, the gas in the snout 2 is naturally exhausted through the gas exhaust pipe 10 due to a difference in pressure between the continuous annealing furnace and the exhaust side of the gas exhaust pipe 10, and passes through a filter or a dust removing device such as a cyclone. After the metal powder is removed, it is released to the atmosphere.

During such a hot-dip plating operation, metal powder adhering to the inner wall of the gas exhaust pipe 10 is cleaned and removed at regular intervals. In this case, the gas exhaust pipe 10
A pig 18 for cleaning the inner wall of the pipe is inserted into the inside, and a gas for pressure feeding is supplied from the gas supply unit 15 to the back of the pig.
While the gas in the pipe in front of the pig is sucked from the two sides by the gas suction means, the pig is fed under pressure. This pipe inner wall cleaning pig 18
Is a vertical pipe portion 101-1 on which metal powder is particularly likely to adhere and accumulate due to cooling of a gas containing metal vapor in the gas exhaust pipe 10.
The metal powder adhering to the inner wall of the pipe is removed by sequentially passing through the curved pipe section 103-horizontal pipe section 100 by the above-described operation, and the outlet 12 is removed together with the metal powder accompanying the compressed gas flow.
Taken out of Further, a part of the removed metal powder is also discharged from the discharge part 16 below the vertical tube part 101.

The gas exhaust pipe 10 is cleaned by the pig 18 for cleaning the inner wall of the pipe at a rate of about once every four months, for example, so that the gas exhaust pipe 10 is not clogged by the adhesion of metal powder. In addition, the plating operation can be stably performed for a long period of time. If the inside of the pipe is not regularly cleaned by the pig as described above, it is necessary to remove the metal powder attached to the pipe inner wall over about 12 hours to prevent clogging with the metal powder, Therefore, according to the facility of the present invention, such a complicated cleaning operation during the operation is not required at all.

The hot-dip metal plating equipment to which the present invention is applied includes not only hot-dip galvanizing equipment, but also hot-dip aluminum plating equipment, hot-dip aluminum-zinc alloy plating equipment, and all kinds of hot-dip plating equipment. . Further, the type of the metal band to be plated is not limited.

[0040]

As described above, according to the first aspect of the present invention, the gas in the snout containing the metal vapor generated from the molten metal bath is quickly discharged during the operation of the continuous hot-dip plating. Therefore, plating defects caused by metal vapor generated in the snout can be effectively prevented. According to the invention according to claims 2 to 4 of the present application, even if metal powder adheres to the inner wall of an exhaust pipe system for exhausting gas containing metal vapor from the snout due to deposition of metal vapor. This can be efficiently removed by a simple cleaning operation, and the hot-dip plating operation can be stably performed for a long period of time. Further, according to the invention according to claims 5 and 6 of the present application, the above-described cleaning operation of the exhaust pipe system can be particularly efficiently performed.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a snout and a hot-dip plating tank in a cross-section, showing an embodiment of the equipment of the present invention.

FIG. 2 is a partially enlarged sectional view of a gas seal portion in FIG.

FIG. 3 is a front view showing a snout and a part of a gas exhaust pipe in the embodiment shown in FIG. 1;

FIG. 4 is an explanatory view showing substantially the entire gas exhaust pipe in the embodiment shown in FIG. 1;

FIG. 5 is a plan view showing a pipe inner wall cleaning pig used in the facility of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Continuous annealing furnace, 2 ... Snout, 3 ... Hot-dip plating tank, 4
... Sink roll, 5 ... Gas wiping device, 6 ... Gas sealing part, 7 ... Gas sealing device, 8 ... Seal plate, 9 ... Gas exhaust port, 10 ... Gas exhaust pipe, 11 ... Inlet, 12 ... Outlet, 13 ... connecting pipe, 14 ... inlet pipe, 15 ... gas supply section, 16 ... discharge section, 17 ... guide, 18 ... pipe inner wall cleaning pig, 19 ... groove, 20 ... upper member, 21 ... lower member, 2
2 ... flange portion, 100, 102 ... horizontal tube portion, 101
... vertical tube section, 103, 104 ... curved pipe section, A ... hot-dip plating bath

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keishi Yamashita 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Masayuki Hatakeyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Takayuki Fukui 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4K027 AA02 AA22 AB42 AD08 AD10 AE04 AE36 AE37

Claims (6)

[Claims] 1. A continuous heat treatment furnace for continuously heat-treating a metal strip, a hot-dip plating tank into which the metal strip heat-treated in the continuous heat-treatment furnace is introduced, In a continuous molten metal plating equipment having a snout provided therebetween, a gas seal portion is provided in the middle of the snout, and a gas exhaust pipe is connected to a snout portion between the gas seal portion and the molten plating bath, A continuous hot-dip metal plating facility wherein gas containing metal vapor in a snout can be exhausted through the gas exhaust pipe. 2. A pipe inlet / outlet for a pipe inner wall cleaning pig is provided at an arbitrary location on a gas exhaust side and an arbitrary location on a snout connection side in a longitudinal direction of a gas exhaust pipe. 2. The continuous hot-dip metal plating equipment described in 1. 3. An inlet for a pipe inner wall cleaning pig is provided at an arbitrary location on the gas exhaust side in the longitudinal direction of the gas exhaust pipe, and an outlet for the pipe inner wall cleaning pig is provided at an arbitrary location on the snout connection side. The continuous hot-dip metal plating equipment according to claim 2, wherein: 4. A gas supply section for feeding a pig under pressure on the inlet side of the pig for cleaning the inner wall of the pipe, and gas suction means is provided on an outlet side of the pig for cleaning the inner wall of the pipe. Or the continuous hot-dip metal plating equipment according to 3. 5. A method for using a continuous hot-dip metal plating facility according to claim 2, 3 or 4, wherein the pipe for cleaning the inner wall of the pipe has grooves formed along the direction of movement of the pig at appropriate intervals on the outer peripheral surface. The method is characterized in that the pig for cleaning the inner wall of the pipe is inserted from the inlet of the gas exhaust pipe, the inside of the gas exhaust pipe is pressure-fed, and removed from the outlet to remove metal powder attached to the inner wall of the gas exhaust pipe. How to use continuous hot metal plating equipment. 6. The continuous hot-dip metal plating equipment according to claim 5, wherein a pipe for cleaning the inner wall of the pipe is used in which the groove on the outer peripheral surface is spirally formed with respect to the pig axis direction or formed with an appropriate inclination. How to use