JP3528796B2 - Continuous hot metal plating method for metal strip - Google Patents

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 method for metal strips, which enables easy adjustment and switching of plating bath components.

[0002]

2. Description of the Related Art One of the methods for applying metal plating to steel strips is
There is a hot metal plating method in which a steel strip is immersed in a plating bath in which a desired metal is melted, and the steel strip after plating is alloyed as necessary to form a product. FIG. 8 shows a general hot-dip galvanized steel strip manufacturing apparatus. In FIG. 7, 1 is a plating tank, a is a plating bath (molten metal bath) held in this plating tank 1, 3 is a sink roll arranged in the plating bath a, and 5 is below the plating bath surface above it. Of the support roll, 4 is a gas wiping nozzle arranged above the surface of the plating bath, 6 is a touch roll installed further above, and 7 is a snout for guiding the steel strip into the plating bath in an unoxidized state. In such a manufacturing apparatus, after the steel strip S is guided into the plating bath a through the snout 7, it is vertically changed by the sink roll 3 and guided to the upper side of the bath, and the gas wiping is performed above the bath surface. The amount of plating adhered is adjusted by the nozzle 4, and then an alloying treatment of plating is performed in an alloying treatment furnace (not shown) if necessary.

In this kind of hot-dip galvanized steel strip manufacturing apparatus, it is common to change the components of the plating bath according to the type of plating, the type of target steel strip, the purpose of use of the steel strip, and the like. For example, in the production of hot-dip galvanized steel strip, when the plated steel strip is alloyed, the Al concentration in the bath is 0.
It is necessary to adjust the components of the plating bath so that it is as low as 10 to 0.15 mass%, and if the alloying treatment is not performed, the Al concentration in the bath becomes as high as 0.18 to 0.50 mass%. For this reason, when both hot-dip galvanized steel strips (non-alloyed galvanized steel strips) and alloyed hot-dip galvanized steel strips are manufactured on the same line, the components of the plating bath are changed depending on whether or not the alloying treatment is performed. Is essential.

Generally, it is relatively easy to increase the concentration of a trace amount of a component (eg, Al) in a plating bath because a lump (ingot) having a high component ratio may be added to the plating bath. On the other hand, it is not easy to reduce the concentration of the trace amount additive component in the plating bath. Conventionally, as a method of reducing the concentration of this trace additive component, an ingot with a low concentration of the trace additive component is added to the plating bath to replenish the molten metal taken out from the plating bath as the plating layer of the steel strip. By using this method, the trace additive component in the plating bath can be gradually reduced, or most of the plating bath that is operating in a state where the trace additive component is in a high concentration is pumped out, and then the ingot with a low trace additive component concentration is used. There is a method of putting into the bath.

However, in the former method, a huge amount of time and a large amount of an adjusting material (ingot) are required to reduce the trace amount of the additive component in the plating bath to a desired concentration, and the production is performed during the adjustment of the concentration. Since the plated steel strip to be formed is manufactured in a plating bath in which the concentration of a trace amount of additive component deviates from an appropriate level, poor plating adhesion and poor alloying are likely to occur. On the other hand, in the latter method, a large fluctuation in the bath surface level of the plating bath is unavoidable and the snout is released to the atmosphere, which results in problems such as oxidation of the inner wall of the snout and generation of a large amount of ash. Virtually difficult to operate.

[0006]

In order to reduce the Al concentration in the plating bath, Japanese Laid-Open Patent Publication No. 10-280114 discloses a method for reducing the Al concentration in the plating bath at 450 ° C. A method of reacting with an oxide having a standard free energy of formation of −900 kJ / mol or more and 550 kJ / mol or less to convert it into aluminum oxide has been proposed.

However, this method requires a step of removing the aluminum oxide floating on the surface of the plating bath, and since foreign matter is mixed in the bath, it may cause a plating defect if the foreign matter is not sufficiently removed after the start of production. Therefore, it is difficult to put this method into practical use. Therefore, the object of the present invention is to solve the problems of the prior art,
It is an object of the present invention to provide a method capable of rapidly or inexpensively adjusting or switching the components of a molten metal plating bath in continuous molten metal plating of metal strips.

[0008]

As a result of various studies on the method for efficiently changing the components of the molten metal plating bath, the present inventors have found that a preparation bath for adjusting or changing the components in the bath is provided separately from the plating bath. The inventors have devised a method in which a molten metal bath is prepared in advance and the adjustment or switching of the components in the plating bath can be performed easily and at low cost by using this molten metal bath. That is, the present invention has the following features.

[1] A continuous hot-dip metal plating method for a metal strip in which a metal strip is continuously immersed in a plating bath (A) held in a plating bath to deposit molten metal on the surface of the metal strip. A molten metal bath (B) for adjusting the components of the plating bath (A) or for changing the components is prepared in a preparation bath installed separately from the bath , and the molten metal bath is also provided.
(B) bath component, the molten metal is the current operation plating bath
Next operation plating bath components when mixed with molten metal (A)
Adjust in advance so that they are close to each other, and then use the plating bath
The molten metal of (A) is transferred to the molten metal bath (B).
And about the same amount of molten metal from the molten metal bath (B)
By transferring to the plating bath (A), the bath of the plating bath (A)
Molten gold in plating bath (A) while keeping the surface level almost constant
The metal and the molten metal in the molten metal bath (B)
Plating bath (A) by mixing until almost uniform
Of the plating bath (A)
After adjusting the components or switching the components,
Equivalent to the amount of molten metal taken out from the plating bath (A)
An amount of molten metal from the molten metal bath (B) to the plating
In the plating bath (A), by transferring to the bath (A)
A method for continuous hot-dip metal plating of a metal strip, which is characterized by compensating for a decrease in molten metal.

[2] In the continuous hot metal plating method of [1 ] above, the amount of hot metal prepared in the hot metal bath (B) for adjusting or changing the components of the plating bath is set in the next-operation plating bath. A method for continuous hot-dip metal plating of a metal strip, characterized in that the amount of molten metal carried out by the metal strip to be passed is not more than the amount.

[0011]

[0012]

[3] In a continuous molten metal plating method for a metal strip, which comprises continuously immersing the metal strip in a plating bath (A) held in a plating tank to deposit molten metal on the surface of the metal strip, A small pot through which the metal band to be plated can be placed is arranged in the plating tank so that the molten metal in the small pot and the molten metal outside thereof can be separated and mixed, and the plating tank is A molten metal bath (B) for adjusting the components of the plating bath (A) or for switching the components is prepared in a separately prepared preparation bath , and the molten metal is
The bath component of the bath (B) is the molten metal currently in operation.
All of the molten metal in (A) or mixed with the molten metal in a small pot.
When combined, all or a small amount of molten metal in the plating bath (A)
The molten metal in the bath will be near the components of the next operation plating bath.
Adjusted in advance so that the molten metal in the plating bath (A) is
While transferring the molten metal to the molten metal bath (B),
The metal is transferred from the molten metal bath (B) to the plating bath (A).
By sending it, at least the plating bath surface level in the small pot
The molten metal in the plating bath (A)
Of molten metal in molten metal or small pot and molten metal bath (B)
The components of the plating bath (A) are adjusted or changed by mixing the metal and the molten metals until the two molten metals are substantially uniform, and the components of the plating bath (A) are adjusted or the components are changed.
After performing, melting from the plating bath (A) by the metal strip
Molten metal bath in an amount equivalent to the amount of metal taken out
By transferring from (B) to the plating bath (A),
A continuous hot-dip metal plating method for a metal strip, which is characterized by compensating for a reduced amount of hot metal in a bath (A) .

[4] In the continuous hot-dip metal plating method of [3 ] above, the amount of molten metal prepared in the molten metal bath (B) for adjusting the components of the plating bath or switching the components is set to A method for continuous hot-dip metal plating of a metal strip, characterized in that the amount of molten metal carried out by the metal strip to be passed is not more than the amount.

[0015]

[5] Plating bath held in the plating tank
The metal strip is continuously immersed in (A) and melted on the surface of the metal strip.
For continuous molten metal plating method of metal strip to which molten metal is attached
The plated metal strip can pass through the inside.
A small pot is placed in the plating tank,
It is possible to separate and mix molten metal and molten metal outside it.
And a preparation tank installed separately from the plating tank
For adjusting the components of the plating bath (A) or switching the components
Molten metal bath for preparing molten metal bath (B)
A come method, the molten metal in the small pot was separated from a small pot outside the molten metal, in a state that implement the current operation using only the molten metal in a small pot, the molten metal of the small pot outside The molten metal in the molten metal bath (B) is mixed in advance, and when the next operation is started, the molten metal in the small pot and the molten metal outside the small pot are mixed so that the plating bath (A) 2. A method for continuous hot-dip metal plating of a metal strip, which comprises adjusting or switching the components of.

[6] Plating bath held in the plating tank
The metal strip is continuously immersed in (A) and melted on the surface of the metal strip.
For continuous molten metal plating method of metal strip to which molten metal is attached
The plated metal strip can pass through the inside.
A small pot is placed in the plating tank,
It is possible to separate and mix molten metal and molten metal outside it.
And a preparation tank installed separately from the plating tank
For adjusting the components of the plating bath (A) or switching the components
Molten metal bath for preparing molten metal bath (B)
A method for continuous hot dip metal plating of a metal strip, which comprises performing a plating operation according to the following steps (a) to (e). (A) Molten metal in the small pot, with the molten metal in the small pot separated from the molten metal outside the small pot, and with the molten metal having components near the next operation plating bath component existing outside the small pot. Step (b) in which the operation is performed using only the molten metal in the molten metal bath (B) prepared for the next operation when the operation in the step (a) shifts to the next operation. Step (c) of adjusting the components of the molten metal in the small pot or changing the components by mixing to make a bath component near the next operation plating bath component (c) A small pot in which the components are adjusted or changed in the step (b) In the state where the molten metal inside and the molten metal outside the small pot are mixed, the step (d) in which the next operation is performed on the entire plating bath (A) When transitioning from the next operation in the step (c) to the next operation , Small After separating the molten metal in the small pot from the molten metal outside the small pot, the molten metal in the molten metal bath (B) prepared for the next operation is mixed with the molten metal in the small pot to produce the next operation plating bath. Step (e) of adjusting the components of the molten metal in the small pot or changing the components by using a bath component in the vicinity of the components (e) Only the molten metal in the small pot whose components have been adjusted or changed in the step (d) is used. The process of performing the next operation

[7] Plating bath held in the plating tank
The metal strip is continuously immersed in (A) and melted on the surface of the metal strip.
For continuous molten metal plating method of metal strip to which molten metal is attached
The plated metal strip can pass through the inside.
A small pot is placed in the plating tank,
It is possible to separate and mix molten metal and molten metal outside it.
And a preparation tank installed separately from the plating tank
For adjusting the components of the plating bath (A) or switching the components
Molten metal bath for preparing molten metal bath (B)
A method for continuous hot dip metal plating of a metal strip, which comprises performing a plating operation according to the following steps (a) to (e). (A) By separating the molten metal in the small pot from the molten metal outside the small pot, and by mixing it with the molten metal in the small pot on the outside of the small pot during the next period of operation, near the components of the next operation plating bath In the state in which a molten metal having a plating bath component that becomes the component of (1) is present, operation is performed using only the molten metal in the small pot (b) The operation in the step (a) is shifted to the next operation At this time, the step (c) of adjusting or changing the components of the plating bath (A) by mixing the molten metal inside the small pot with the molten metal outside the small pot (c) Step (d) of performing the next operation in the entire plating bath (A) (d) When transitioning from the next operation in the step (c) to the next operation, the molten metal in the small pot is separated from the molten metal outside the small pot. After that, the molten metal in the molten metal bath (B) prepared for the next operation is mixed with the molten metal in the small pot to form a bath component in the vicinity of the next operation plating bath component. Step (e) of adjusting the ingredients of the molten metal or switching the ingredients (e) Performing the next-generation operation using only the molten metal in the small pot whose ingredients are adjusted or changed in the step (d)

[8] The continuous molten gold according to any one of the above [5] to [7]
In the metal plating method, the bath components of the molten metal bath (B) are
The molten metal is the entire molten metal in the current operation plating bath (A).
Or plating bath when mixed with molten metal in a small pot
All of the molten metal in (A) or the molten metal in the small pot is
Adjust in advance so that it is close to the components of the plating bath
A continuous hot-dip metal plating method for a metal strip, comprising: [9] The continuous hot-dip metal plating method according to any one of the above [5] to [7]
In order to adjust or change the components of the plating bath
The amount of molten metal prepared in the molten metal bath (B)
Melting carried out by a metal strip that runs through the operating plating bath
Continuous molten gold of metal strip characterized by containing less than the amount of metal
Metal plating method. [10] The continuous molten metal plating method according to [6] or [7 ] above
The molten metal in the plating bath (A) to the molten metal bath (B)
While sending it, approximately the same amount of molten metal is poured from the molten metal bath (B).
By transferring to the bath (A), at least a small pot
Plating bath while keeping the level of the plating bath surface inside
Mixing the molten metal of (A) with the molten metal of the molten metal bath (B)
Method for continuous hot dip metal plating of metal strip characterized by performing
Law. [11] In the continuous molten metal plating method according to any one of the above [5] to [10] , the molten metal in the plating bath (A) and the molten metal in the molten metal bath (B) are mixed to form a plating bath (A After adjusting the components or switching the components, the amount of molten metal equivalent to the amount of molten metal carried out from the plating bath (A) by the metal strip is transferred from the molten metal bath (B) to the plating bath (A). The continuous molten metal plating method for a metal strip, comprising:

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the case where a steel strip is plated with molten metal. First of the present invention
In the continuous hot-dip metal plating method, the preparation bath for adjusting or switching components in the plating bath is installed separately from the plating bath holding the plating bath (A) to prepare the molten metal bath (B). This is a method of adjusting or switching the components in the plating bath by mixing the molten metal of the molten metal bath (B) and the molten metal of the plating bath (A). FIG. 1 shows one embodiment of this continuous hot-dip metal plating method.

Generally, the apparatus for producing hot-dip galvanized steel strip is
Plating bath 1 in which plating bath A for continuously dipping steel strip S is held, sink roll 3 arranged in plating bath A for converting the traveling direction of steel strip S to a vertical direction, and plating bath A
A gas wiping nozzle 4 that blows gas onto the surface of the steel strip S at a position where the steel strip S is pulled up to remove the excessively adhered plating metal, and adjusts the amount of plating deposit, and the steel strip S above and below the gas wiping nozzle 4. It comprises a support roll 5 and a touch roll 6 for supporting the movement, and a snout 7 for guiding the steel strip S into the plating bath A in an unoxidized state.

In the apparatus for producing such a hot-dip galvanized steel strip, in the present invention, the preparation tank 2 is provided separately from the plating tank 1.
And a molten metal bath B for adjusting the components of the plating bath A or for changing the components is prepared in the preparation tank 2. And
The components of the plating bath A are adjusted or the components are switched by mixing the molten metal of the plating bath A and the molten metal of the molten metal bath B (generally, the total amount of the molten metal in both baths is mixed substantially uniformly). In the embodiment of FIG. 1, a preparation tank 2 is provided adjacent to the plating tank 1 in which the plating bath A is held.
While holding the molten metal bath B therein, the preparation bath 2 and the plating bath 1 are connected by two molten metal transfer pipes 8a and 8b each equipped with a pump 9a and 9b, and one of the molten metal baths is melted. From the preparation tank 2 to the plating tank 1 with the metal transfer pipe 8a, from the plating tank 1 to the preparation tank 2 with the other molten metal transfer pipe 8b,
The molten metal can be transferred respectively.

Then, in the preparation tank 2, when adjusting or switching the plating bath component of the current plating operation to the plating bath component of the next plating operation, by mixing with the molten metal of the plating bath A of the current plating operation, A molten metal bath B having a molten metal amount and a bath component capable of becoming a desired plating bath component is prepared, and when adjusting or switching to the plating bath component in the next plating operation, the plating bath A is supplied by the molten metal transfer pipes 8a, 8b. By transferring the molten metals in the (plating bath 1) and the molten metal bath B (preparation bath 2) to each other, the molten metals in both baths are mixed until they are substantially uniform, and thereby the bath components of the plating bath A are mixed. Adjust or switch. As described above, the molten metal bath B for adjusting the components of the plating bath A or for changing the components is prepared in advance in the preparation tank 2, and the molten metal is mixed with the molten metal of the plating bath A to melt the steel strip S. It becomes possible to adjust or switch the components of the plating bath in a short time without depending on the metal brought out.

Here, when the molten metal of the plating bath A and the molten metal of the molten metal bath B are mixed by the method of the present invention, the bath components of the molten metal bath B are the same as the current operating plating bath A.
By adjusting in advance so that it will be in the vicinity of the components of the next operation plating bath when mixed with the molten metal of (1), it is only necessary to mix the molten metals of both baths (that is, to mix the total amount of both molten metals substantially uniformly). It is desirable because the plating bath A can be easily adjusted or switched to a desired component.

As a method of mixing the molten metals in both baths, the total amount of the molten metal in one bath (plating bath A or molten metal bath B) is added to the other bath (molten metal bath B or plating bath A).
After a certain amount of molten metal is returned to the one of the above baths after stirring and mixing, it is possible to wind up the dross by stirring and to generate the plating defects of the steel strip, and Considering the problem such as ash peeling from the snout 7 due to the change, the molten metal in both baths is exchanged with each other by using a transfer pipe or the like as in the embodiment of FIG. The method of mixing while maintaining the above is preferable. That is, this method will be described by taking the embodiment of FIG. 1 as an example. While the molten metal of the plating bath A is transferred to the molten metal bath B by the molten metal transfer pipe 8b, approximately the same amount of molten metal is transferred to the molten metal transfer pipe 8a. By transferring from the molten metal bath B to the plating bath A, the molten metal of the plating bath A and the molten metal bath B is mixed while keeping the bath surface level of the plating bath A substantially constant.

After adjusting the components of the plating bath A or switching the components as described above, the amount of reduction of the molten metal in the plating bath A due to the removal by the steel strip S (the removal of the molten metal as the plating layer) is usually If the molten metal is supplied from the molten metal bath B in the preparation tank 2 to the plating bath A for replenishment instead of the method of charging the ingot, the remaining molten metal in the molten metal bath B can be effectively used. Therefore, it is preferable. In this case, the bath component of the molten metal bath B is substantially the same as that of the plating bath A during operation, and therefore, the concentration change of the bath component does not occur as in the case where an ingot is charged, which is very effective. In the embodiment of FIG. 1, such molten metal transfer is performed by the molten metal transfer pipe 8a.

Further, the amount of molten metal prepared as the molten metal bath B in the preparation tank 2 is an amount necessary to bring the molten metal into the vicinity of the components of the next operation plating bath when the molten metal is mixed with the molten metal of the current operation plating bath. In addition, it is desirable to adjust the amount of molten metal to be equal to or less than the amount of molten metal carried out by the steel strip that is passed through the next-generation operation plating bath. This is because the molten metal bath B is adjusted to such an amount of molten metal so that the bath component and amount of the optimum amount of molten metal bath for the preparation tank 2 can be obtained when adjusting or switching the plating bath components for the next operation. This is because it becomes easier to prepare B. In the method of the present invention, when mixing the molten metal of the plating bath A and the molten metal of the molten metal bath B, it is most preferable to uniformly mix the total amount of both baths, but it is not always limited to this. However, the components of the mixed plating bath A in the plating bath 1 and the molten metal bath B in the preparation bath 2 after mixing may be different.

In the second continuous molten metal plating method of the present invention, a small pot through which the metal strip to be plated can pass is arranged in the plating tank, and the molten metal in the small pot and the outside thereof are placed. The molten metal bath (B) can be separated and mixed with the molten metal bath of (B) and a preparation bath for adjusting or changing the components in the plating bath is installed separately from the plating bath holding the plating bath (A). By preparing and mixing the molten metal in the molten metal bath (B) with all of the molten metal in the plating bath (A) or the molten metal in the small pot,
It is a method of adjusting or switching the components of the plating bath.

FIGS. 4A to 4C show three embodiments of this continuous hot metal plating method, and these embodiments will be described below. In this continuous hot-dip metal plating method, a preparation tank 2 is installed separately from the plating tank 1, and a molten metal bath B for adjusting the components of the plating bath A or for changing the components is prepared in the preparation bath 2 first. It is similar to the first continuous hot dip metal plating method of the present invention described above, but further, a small pot 10 through which a metal strip to be plated can pass.
Is placed in the plating tank 1 so that the molten metal inside the small pot 10 and the molten metal outside the small pot can be separated and mixed. Then, the molten metal in the small pot 10 in a state of being separated from the molten metal in the plating bath A or the molten metal on the outside is mixed with the molten metal in the molten metal bath B (usually, both molten metals are mixed). Is mixed substantially uniformly) to adjust the components of the plating bath A or switch the components.

In each of the embodiments shown in FIGS. 4 (a) to 4 (c), the small pot 10 is arranged in the plating tank 1, and the sink roll 3 is arranged inside the small pot 10 and introduced into the plating tank 1. The steel strip S is immersed in the plating bath A in the small pot 10. In order to enable the molten metal in the small pot 10 and the molten metal outside thereof to be separated and mixed, the small pot 1
0 can be moved up and down in the plating tank 1, and the molten metal in the small pot 10 reaches the position where the upper edge (upper side wall upper end) of the small pot is higher than the bath surface in the plating tank 1.
Is separated from the molten metal outside the small pot, and the small pot 10 is lowered to a position where the upper edge of the small pot is lower than the bath surface in the plating tank 1 so that the outside of the small pot melts. It will be mixed with the metal.

The structure for allowing the molten metal in the small pot 10 and the molten metal outside the small pot to be separated and mixed is not limited to this embodiment. An opening or a gate that can be opened and closed is provided at the bottom or side wall of the small pot 10, and the molten metal in the small pot 10 and the molten metal outside the small pot 10 can be separated and mixed by opening or closing the opening or the gate. You may do it. Similarly, while the small pot 10 is fixed, the height of the side wall of the small pot 10 is variable, and the molten metal in the small pot 10 is extended by extending the side wall of the pot to a position where the upper end of the side wall is higher than the bath surface in the plating tank 1. Is separated from the molten metal outside the small pot, and the molten metal inside the small pot 10 is separated from the molten metal outside the small pot by reducing the pot side wall to a position where the upper end of the side wall is lower than the bath surface in the plating tank 1. It may be mixed. Also, in the method of vertically moving the small pot 10 as in the present embodiment and the method of changing the height of the side wall of the pot as well, in order to appropriately mix the molten metal in the small pot 10 and the molten metal outside thereof. Alternatively, the small pot 10 may be provided with an openable / closable opening or a gate.

Further, in the present invention, a preparation tank 2 is provided adjacent to the plating tank 1 in which the plating bath A is held.
While holding the molten metal bath B therein, the preparation bath 2 and the plating bath 1 are connected by two molten metal transfer pipes 8a and 8b each equipped with a pump 9a and 9b, and one of the molten metal baths is melted. From the preparation tank 2 to the plating tank 1 with the metal transfer pipe 8a, from the plating tank 1 to the preparation tank 2 with the other molten metal transfer pipe 8b,
The molten metal can be transferred respectively.

Then, in the preparation tank 2, when adjusting or switching the plating bath component of the current plating operation to the plating bath component of the next plating operation, the molten metal of the plating bath A of the current plating operation (of the plating bath A) A molten metal bath B having the amount of molten metal and a bath component capable of forming a desired plating bath component by mixing all of the molten metal or the molten metal in the small pot 10) is prepared, and is added to the plating bath component of the next plating operation. At the time of adjustment or switching, the molten metal of the plating bath A (the entire molten metal of the plating bath A or the molten metal in the small pot 10) and the molten metal of the molten metal bath B are mutually exchanged by the molten metal transfer pipes 8a and 8b. By transferring them, the molten metals in both baths are mixed until they are substantially uniform, whereby the bath components of the plating bath A are adjusted or switched.

Here, the embodiment shown in FIG. 4 (a) is a case where the molten metal in the small pot 10 of the plating bath A and the molten metal in the molten metal bath B are mixed. With the molten metal in the small pot 10 separated from the molten metal outside by raising the small pot 10, the molten metal in the pot 10 and the molten metal in the molten metal bath B are mutually exchanged by the molten metal transfer pipes 8a and 8b. By being transferred to each other, the molten metals of both are mixed until they are substantially uniform, and thereby the pot 1
Adjust or switch the bath components of the plating bath within 0.

The embodiment shown in FIG. 4B is a case where all of the molten metal in the plating bath A and the molten metal in the molten metal bath B are mixed, and the small pot 10 is lowered in the plating tank 1 to make a small amount. By transferring the molten metal in the plating bath A and the molten metal in the molten metal bath B to each other by the molten metal transfer pipes 8a and 8b in a state where the molten metal in the pot 10 and the molten metal outside thereof are mixed. , The molten metals in both baths are mixed until they are substantially uniform, and thereby the bath components of the entire plating bath A are adjusted or switched.

The embodiment shown in FIG. 4C is also a case where all the molten metal in the plating bath A and the molten metal in the molten metal bath B are mixed. In this case, first, the molten metal in the small pot 10 is mixed. Is separated from the molten metal on the outside thereof, the molten metal on the outside of the small pot and the molten metal in the molten metal bath B are mixed in advance, and when the components of the plating bath A are adjusted or switched, The molten metal and the molten metal outside thereof are mixed, and the plating bath components can be adjusted or switched more quickly than in the embodiments of FIGS. 4 (a) and 4 (b). That is, the small pot 10 is raised in the plating tank 1 to separate the molten metal in the small pot 10 from the molten metal outside thereof, and the current plating operation is performed using only the molten metal in the small pot 10. In this state, the molten metal in the plating bath outside the small pot and the molten metal in the molten metal bath B are transferred to each other by the molten metal transfer pipes 8a and 8b in advance to mix the molten metals in both baths, thereby making the small pot The molten metal on the outside was mixed with a predetermined bath component (later the small pot 10
Of the molten metal in the small pot 10 and the molten metal in the small pot 10 are lowered by lowering the small pot 10 when switching to the next plating operation. By mixing with the molten metal on the outside, the bath components of the entire plating bath A are adjusted or switched.

As described above, by preparing the molten metal bath B for adjusting the components of the plating bath A or changing the components in advance in the preparation tank 2 and mixing the molten metal with the molten metal of the plating bath A, At this time, by using the small pot 10 installed in the plating tank 1, it becomes possible to adjust or switch the components of the plating bath in a short time without depending on the molten metal carried out by the steel strip S. Further, the small pot 10 in the plating tank 1 is appropriately used, and the small pot 10
It is possible to perform plating operation using only the plating bath inside
It is also advantageous to produce small quantities of any plated steel sheet.

Here, when the molten metal of the plating bath A and the molten metal of the molten metal bath B are mixed by the method of the present invention, the bath components of the molten metal bath B are the same as the current operating plating bath A.
All of the molten metal of No. 1 or when mixed with the molten metal in the small pot 10, all of the molten metal of the plating bath A (when the next plating operation is performed using the entire plating bath A) or the small pot 1
The molten metal in the plating bath A (when the next plating operation is performed using only the plating bath in the small pot 10) in the vicinity of the components in the next operation plating bath is The plating bath A can be simply formed by mixing all of the molten metal in the plating bath A or the molten metal in the small pot 10) with the molten metal in the molten metal bath B (that is, uniformly mixing the total amount of both molten metals). It is desirable because it can be adjusted or switched to a desired component.

The molten metal of the plating bath A (plating bath A
The entire amount of the molten metal in one bath (the plating bath A or the molten metal bath B) is mixed with the other in the small pot 10) and the molten metal in the molten metal bath B. After transferring to a bath (molten metal bath B or plating bath A) and stirring and mixing, a predetermined amount of molten metal may be returned to one of the baths. Considering the problems such as the occurrence of plating defects of the above and the peeling of ash from the snout 7 due to the change of the plating bath surface level, the molten metals in both baths are mutually exchanged by using a transfer pipe or the like as in each embodiment of FIG. A method of mixing the two baths while keeping the bath amounts of the both baths substantially constant by exchanging them is preferable. That is, this method will be described by taking the embodiment of FIG. 4 as an example. While the molten metal in the plating bath A is transferred to the molten metal bath B by the molten metal transfer pipe 8b, almost the same amount of molten metal is transferred to the molten metal transfer pipe 8a. By transferring the molten metal bath B to the plating bath A by means of, the plating bath A (or the plating bath in the pot 10) is kept at a substantially constant bath surface level.
And the molten metal in the molten metal bath B are mixed.

After the components of the plating bath A are adjusted or the components are switched as described above, the molten metal in the plating bath A is taken out by the steel strip S (the molten metal is taken out as the plating layer) (the plating operation is performed in a small pot). When only the plating bath in 10 is used, the depletion amount of the molten metal in the small pot 10 is not determined by a normal ingot feeding method.
Replenishment is performed by transferring molten metal from the molten metal bath B in the preparation tank 2 to the plating bath A (the plating bath in the small pot 10 when the plating operation is performed using only the plating bath in the small pot 10). This is preferable because the molten metal remaining in the molten metal bath B can be effectively used. In this case, the bath component of the molten metal bath B is substantially the same as that of the plating bath A during operation, and therefore, the concentration change of the bath component does not occur as in the case where an ingot is charged, which is very effective. In the embodiment of FIG. 4, such molten metal transfer is accomplished by the molten metal transfer tube 8
a.

The amount of the molten metal prepared as the molten metal bath B in the preparation tank 2 is such that when the molten metal is mixed with all of the molten metal in the current operation plating bath A or the molten metal in the small pot 10, All or a small pot of molten metal A
It is desirable to adjust the amount of the molten metal in the inside to the amount required to bring it to the vicinity of the components of the next operation plating bath, and to be equal to or less than the amount of molten metal carried out by the steel strip threaded in the next operation plating bath. This is because the molten metal bath B is adjusted to such an amount of molten metal so that the bath component and amount of the optimum amount of molten metal bath for the preparation tank 2 can be obtained when adjusting or switching the plating bath components for the next operation. This is because it becomes easier to prepare B. In the method of the present invention, the plating bath A
In mixing the molten metal of (the entire plating bath or the plating bath in the small pot 10) and the molten metal of the molten metal bath B, it can be said that it is most preferable to uniformly mix the total amount of both baths, It is not necessarily limited to this, and the plating components in the plating bath 1 after mixing and the molten metal bath B in the preparation bath 2 may have different bath components.

Further, in the method of the present invention, by performing the plating operation according to the following steps (a) to (d), efficient operation using the small pot 10 can be performed. (A) In a state where the molten metal in the small pot 10 is separated from the molten metal outside the small pot, and the molten metal having a component near the next operation plating bath component is present outside the small pot 10, the small pot 10 (B) Performing an operation (plating operation) using only the molten metal in the inside of the molten metal in the molten metal bath B prepared for the next operation at the time of shifting from the operation in the step (a) to the next operation. By mixing with the molten metal in the pot 10 to form a bath component near the next operation plating bath component, the small pot 1
Step (c) of adjusting or switching the components of the molten metal in 0. A state in which the molten metal in the small pot 10 whose components have been adjusted or switched in the step (b) and the molten metal outside the small pot are mixed. Then, in the step (d) of performing the next operation in the entire plating bath A, when the molten metal in the small pot 10 is separated from the molten metal outside the small pot at the time of shifting from the next operation in the step (c) to the next operation , The molten metal in the molten metal bath B prepared for the next operation is mixed with the molten metal in the small pot 10 to form a bath component in the vicinity of the next operation plating bath component. (E) a step of performing the component adjustment or the component switching of the step (e) a step of performing the next next operation using only the molten metal in the small pot 10 of which the component adjustment or the component switching was performed in the step (d)

Further, by performing the plating operation according to the following steps (a) to (e), the efficient operation using the small pot 10 can be performed. (A) By separating the molten metal in the small pot from the molten metal outside the small pot, and by mixing it with the molten metal in the small pot on the outside of the small pot during the next period of operation, near the components of the next operation plating bath In the state in which a molten metal having a plating bath component that becomes the component of (1) is present, operation is performed using only the molten metal in the small pot (b) The operation in the step (a) is shifted to the next operation At this time, the step (c) of adjusting or changing the components of the plating bath (A) by mixing the molten metal inside the small pot with the molten metal outside the small pot (c) Step (d) of performing the next operation in the entire plating bath (A) (d) When transitioning from the next operation in the step (c) to the next operation, the molten metal in the small pot is separated from the molten metal outside the small pot. After that, the molten metal in the molten metal bath (B) prepared for the next operation is mixed with the molten metal in the small pot to form a bath component in the vicinity of the next operation plating bath component. Step (e) of adjusting the ingredients of the molten metal or switching the ingredients (e) Step of performing the next operation using only the molten metal in the small pot whose ingredients have been adjusted or changed in the step (d). It is especially useful for small-scale production (products plated using only small pots).

[0044]

[Example] [Example 1] Plating tank 1 having a capacity of 173 tons
In the hot dip galvanizing equipment as shown in FIG. 1, which is provided with a preparation tank 2 having a maximum capacity of 130 ton which is provided adjacent to the hot dip galvanizing bath A having an Al concentration of 0.20 mass% by a plating bath A. Plated steel sheet (hereinafter "GI")
, And plating bath A with an Al concentration of 0.13 mass%
A case of continuously producing an alloyed hot-dip galvanized steel sheet (hereinafter referred to as “GA”) according to is described. The steel strip and the plating conditions are 0.8
t (mm) x 1600 w (mm), total plating amount on both sides 8
It is set to 0 g / m ² .

First, a case where GI is manufactured in a plating bath A having an Al concentration of 0.20 mass% and the GA is manufactured by switching the plating bath A to an Al concentration of 0.13 mass% will be described. Maximum capacity of 130t
When preparing a molten metal bath B composed of molten zinc of on (hereinafter, simply referred to as “molten metal bath B”), if the Al concentration of this molten metal bath B is adjusted to 0.037 mass% in advance, The desired Al concentration in the plating bath A can be set to 0.13 mass% simply by mixing all the amounts of the molten zinc in the plating bath A and the molten metal bath B when switching the bath components of the plating bath A. Further, the molten metal bath B prepared in the preparation tank 2 is pure Z
In the case of n (Al concentration: 0 mass%), 9 in the preparation tank 2.
If a molten metal bath B of 3.2 tons is prepared, the Al concentration of the plating bath A can be adjusted to a desired Al concentration of 0.13 mass by simply mixing the total amount of each molten zinc of the plating bath A and the molten metal bath B.
It can be%.

The operation in this case will be described with reference to FIG. 2. When the GI is produced in the plating bath A having an Al concentration of 0.20 mass% as shown in FIG.
The component concentration of the plating bath A was adjusted by introducing the ingot into the plating bath, and during this period, the preparation bath 2 was filled with a molten metal bath B (a molten zinc bath having an Al concentration of 0.037 mass% for 130 t).
On, or a molten zinc bath of pure Zn 93.2 ton) is prepared. Then, the plating bath A has an Al concentration of 0.13 mass
When the GA is manufactured by switching to%, the process shown in FIG.
Molten metal transfer pipes 8a, 8b equipped with a pump as shown in FIG.
Of each of the molten baths of the plating bath A and the molten metal bath B by transferring them to each other (preferably, while keeping the bath surface level of the plating bath A substantially constant). The molten zinc is mixed almost uniformly. As a result, the Al concentration of the plating bath A can be set to a desired 0.13 mass% as described above.

After such a mixing operation of molten zinc in both baths,
As shown in FIG. 2 (c), the production of GA begins, but as shown in FIG. 2 (c), the amount of molten zinc (Al concentration 0.13 mass%) corresponding to the amount of molten zinc taken out from the plating bath A by the steel strip S is provided in the preparation tank. The molten metal bath B of No. 2 is supplied to the plating bath A through the molten metal transfer pipe 8a. Specifically, when 130 ton of molten zinc having an Al concentration of 0.037 mass% was prepared in the molten metal bath B, until pure galvanized steel strip with a steel strip weight of about 5100 ton was produced, and pure Zn was added to the molten metal bath B. When 93.2 ton of molten zinc is prepared, the steel strip weight is about 37.
Until the production of 00 ton plated steel strip, molten zinc was supplied from the molten metal bath B of the preparation tank 2 to the plating bath A, and thereafter, the bath amount and the component concentration of the plating bath A were maintained by introducing the ingot. Become.

Similarly, switching from GA manufacturing to GI manufacturing can be easily performed. That is, Al
When GA is manufactured in a plating bath A having a concentration of 0.13 mass% and the GI is manufactured by switching the plating bath A to an Al concentration of 0.20 mass%, for example, in the preparation tank 2, an Al concentration of 3.5 mass% is used. If 3.7 tonnes of molten zinc is prepared, the Al concentration in the plating bath A can be adjusted to a desired value by simply mixing all the amounts of each molten zinc in the plating bath A and the molten metal bath B when the components of the plating bath A are switched. It can be 20 mass%.

The operation in this case will be described with reference to FIG. 3. When GA is manufactured in the plating bath A having an Al concentration of 0.13 mass% as shown in FIG.
The component concentration of the plating bath A is adjusted by charging the ingot into the plating bath, and during this period, 3.7 ton of the molten zinc bath B having an Al concentration of 3.5 mass% is prepared in the preparation tank 2. When the GI is manufactured by switching the plating bath A to an Al concentration of 0.20 mass%, the molten metal transfer pipes 8a and 8b equipped with a pump are used as shown in FIG. And each molten zinc in the molten metal bath B are transferred to each other (preferably, while being kept at a substantially constant bath surface level in the plating bath A), the molten zinc in both baths is made substantially uniform. Mix. As a result, the Al concentration of the plating bath A can be set to a desired 0.20 mass% as described above.

After such a mixing operation of molten zinc in both baths,
As shown in FIG. 3 (c), according to the amount of molten zinc carried out from the plating bath A by the steel strip S, a corresponding amount of molten zinc (Al concentration 0.20 mass%) is prepared in the preparation tank. The molten metal bath B of No. 2 is supplied to the plating bath A through the molten metal transfer pipe 8a. Specifically, when 3.7 ton of molten zinc having an Al concentration of 3.5 mass% is prepared in the molten metal bath B, the molten zinc bath in the preparation tank 2 is manufactured until a plated steel strip having a steel strip weight of about 150 ton is manufactured. The molten zinc is supplied from B to the plating bath A, and thereafter, the bath amount and the component concentration of the plating bath A are maintained by introducing the ingot.
Further, in this case, it can be applied even when a small amount of GI is produced.

[Embodiment 2] Preparation of a plating tank 1 having a capacity of 173 tons (of which the capacity of the small pot is 73 tons) equipped with a small pot 10 which can be vertically moved up and down, and a maximum capacity of 130 tons provided adjacent thereto. In the hot-dip galvanizing equipment having the bath 2 as shown in FIG. 4, the GI by the plating bath A having an Al concentration of 0.20 mass% based on the method of the present invention.
Of aluminum and G by plating bath A with Al concentration of 0.13 mass%
A case of continuously producing A will be described. In addition,
As the steel strip and plating conditions, the representative steel strip size is 0.8t
(Mm) x 1600w (mm), total plating amount on both sides 80
g / m ² .

First, a case will be described in which GI is manufactured in the plating bath A having an Al concentration of 0.20 mass% and the GA is manufactured by switching the plating bath A to an Al concentration of 0.13 mass%. First, when the GI is manufactured by using only the plating bath in the small pot 10 in a state where the molten zinc in the small pot 10 is separated from the molten zinc outside the small pot, the Al concentration of the molten zinc in the small pot 10 is increased. Is 0.20 mass% and the Al concentration of the molten zinc outside the small pot 10 can be adjusted to 0.13 mass% for GA production. When preparing a molten metal bath B made of molten zinc having a maximum capacity of 130 tons in the preparation tank 2, if the Al concentration of this molten metal bath B is adjusted to 0.091 mass% in advance, GA production At the time of switching the bath components of the plating bath A at the time of shifting to No. 3, by simply mixing the total amount of the molten zinc in the small pot 10 and the molten zinc in the molten metal bath B, the Al concentration of the molten zinc in the small pot 10 can be set to a desired value of 0. 13 mass% (10 small pots
The same Al concentration as the outer molten zinc) can be used.
Further, the molten metal bath B prepared in the preparation tank 2 is pure Zn (Al
In the case of concentration: 0 mass%), 39.3 to
If the molten metal bath B of n is prepared, the Al concentration of the molten zinc in the small pot 10 can be adjusted to a desired value by simply mixing all of the molten zinc in the small pot 10 and the molten zinc in the molten metal bath B. .13mass% (Al same as molten zinc outside the small pot)
Concentration).

The operation in this case will be described with reference to FIG. 5. As shown in FIG. 5A, GI is manufactured in a plating bath with an Al concentration of 0.20 mass% held in a small pot 10. In the meantime, the molten metal bath B (Al concentration of 0.
130ton of molten zinc bath of 091mass%, or pure Zn
A molten zinc bath of 39.3 tons) is prepared. When the plating bath A is switched to an Al concentration of 0.13 mass% to manufacture GA, molten metal transfer pipes 8a and 8b equipped with a pump are used as shown in FIG. The molten zinc in the bath and the molten zinc in the molten metal bath B are transferred to each other (preferably, while the bath surface level of the plating bath in the pot 10 is maintained substantially constant). The molten zinc is mixed almost uniformly. This allows
As described above, the Al concentration of the molten zinc in the small pot 10 can be set to a desired 0.13 mass%. After such mixing of the baths, the small pot 10 is lowered so that the molten zinc in the small pot 10 and the molten zinc outside thereof (A
1 concentration 0.13 mass%) are mixed. As a result, the entire operation of the plating bath A can be used for the next operation, that is, the production of GA. The molten zinc in the small pot 10 and the molten metal outside thereof may be mixed either before or after the molten metal in the plating bath and the molten zinc in the molten metal bath B are mixed.

After such a mixing operation of molten zinc in both baths,
As the production of GA begins, as shown in FIG. 5 (c), the amount of molten zinc (Al concentration 0.13 mass%) corresponding to the amount of molten zinc carried out from the plating bath A by the steel strip S is prepared in the preparation tank. The molten metal bath B of No. 2 is supplied to the plating bath A through the molten metal transfer pipe 8a. Specifically, when 130 ton of molten zinc having an Al concentration of 0.091 mass% is prepared in the molten metal bath B, until the plated steel strip having a steel strip weight of about 5100 ton is produced, the molten metal bath B contains pure Zn. If 39.3 tons of molten zinc is prepared, the weight of the steel strip is about 15
Until the production of 60 ton plated steel strip, molten zinc was supplied from the molten metal bath B of the preparation tank 2 to the plating bath A, and thereafter, the ingot was charged to maintain the bath amount and the component concentration of the plating bath A. Become.

Further, the switching from the GI manufacturing to the GA manufacturing can be performed as follows. That is, a case where GI is manufactured in the plating bath A having an Al concentration of 0.20 mass% and the GA is manufactured by switching the plating bath A to the Al concentration of 0.13 mass% will be described.
With the molten zinc in the small pot 10 separated from the molten zinc outside the small pot, the Al concentration of the molten zinc in the small pot 10 is set to 0.20 mass%, and the GI is produced using only the plating bath in the small pot 10. carry out. On the other hand, the molten zinc outside the small pot 10 has an Al concentration adjusted in advance to 0.0789 mass%. As a result, when switching the bath components of the plating bath A at the time of shifting to GA production, the molten zinc in the small pot 10 and the molten zinc outside thereof are simply mixed to increase the Al concentration of the molten zinc in the plating bath (A). It can be desired 0.13 mass%. Al of molten zinc outside the small pot
The concentration is adjusted, for example, by supplying molten zinc having a predetermined Al concentration from the molten metal bath B.

The operation in this case will be described with reference to FIG. 6. As shown in FIG. 6A, GI is manufactured in a plating bath with an Al concentration of 0.20 mass% held in a small pot 10. In the meantime, the molten zinc outside the small pot 10 is
At the time of production transition, by mixing with molten zinc in the small pot 10, the Al concentration is adjusted so as to become a component in the vicinity of the plating bath component for GA production. The adjustment of the Al concentration of the molten zinc outside the small pot is performed, for example, from a molten zinc bath B having a predetermined Al concentration prepared in the preparation tank 2 in a virtual line (molten metal transfer pipe 8 ') in FIG. Is supplied to the plating bath outside the small pot and mixed with the plating bath outside the small pot. When the plating bath A is switched to an Al concentration of 0.13 mass% to manufacture GA, the small pot 10 is used as shown in FIG. 6 (b).
By lowering the molten zinc (A
1 concentration of 0.20 mass%) and molten zinc outside thereof (Al concentration of 0.0789 mass%) are mixed. As a result, the Al concentration of the molten zinc in the plating bath A is set to the desired 0.13 mass%.
Therefore, the whole of the plating bath A can be used for the next operation, that is, the production of GA.

After mixing the molten zinc inside and outside the small pot 10 as described above, GA production is started. At this time, as shown in FIG. 6 (b), molten zinc having an Al concentration of 0.13 mass% is placed in the preparation tank 2. A bath B is prepared, and an amount of molten zinc corresponding to the amount of molten zinc carried out from the plating bath A by the steel strip S (A
It is also possible to supply (1 concentration 0.13 mass%) from the molten metal bath B of the preparation tank 2 to the plating bath A through the molten metal transfer pipe 8a.

Similarly, switching from GA manufacturing to GI manufacturing can be easily performed. That is, Al
When GA is manufactured in the entire plating bath A having a concentration of 0.13 mass% and the GI is manufactured using only the small pot 10 by switching the plating bath A to an Al concentration of 0.20 mass%, for example, preparation If 1.5 ton of molten zinc having an Al concentration of 3.5 mass% is prepared in the tank 2, the small pot 10 is raised when the components of the plating bath A are changed so that the molten zinc in the small pot 10 is separated from the molten zinc outside thereof. By separating and mixing all the molten zinc in the small pot 10 and the molten zinc in the molten metal bath B in this state, the Al concentration of the molten zinc in the small pot 10 can be set to a desired 0.20 mass%. it can.

The operation in this case will be described with reference to FIG. 7. When GA is produced in the whole plating bath A having an Al concentration of 0.13 mass% as shown in FIG. Plating bath A by putting an ingot into the plating bath
Is adjusted, and during this period, 1.5 ton of the molten zinc bath B having an Al concentration of 3.5 mass% is prepared in the preparation tank 2. When the GI is manufactured by switching the plating bath A to the Al concentration of 0.20 mass%, the small pot 10 is raised to separate the molten zinc in the small pot 10 from the molten zinc outside the small pot 10. As shown in (b), the molten metal transfer pipes 8a and 8b provided with a pump are used to transfer the molten zinc in the small pot 10 and the molten zinc in the molten metal bath B to each other (preferably, the small pot). The molten zinc in both baths is mixed substantially uniformly by transporting while maintaining the inner surface level of the plating bath substantially constant). Thereby, as described above, the Al concentration of the molten zinc in the small pot 10 is set to a desired 0.20 mass.
It can be%.

After such a mixing operation of molten zinc in both baths,
The production of GI starts, but as shown in FIG. 7 (c), the amount of molten zinc taken out from the small pot 10 by the steel strip S is equivalent to that of molten zinc (Al concentration 0.20 mass%).
Is supplied from the molten metal bath B of the preparation tank 2 to the plating bath in the small pot 10 through the molten metal transfer pipe 8a. Specifically, when 1.5 ton of molten zinc having an Al concentration of 3.5 mass% is prepared in the molten metal bath B, the steel strip weight is about 60 ton.
Until the galvanized steel strip is manufactured, the molten zinc bath B in the preparation tank 2
It is possible to supply molten zinc to the plating bath in the small pot 10. Therefore, it can be said that this method is also suitable for small-scale production of GI. In addition, when GI is further manufactured in the plating bath in the small pot, the bath amount and the component concentration of the plating bath in the small pot 10 may be maintained by adding an ingot, or the preparation tank 2 may have a large number of components in advance. Molten zinc may be prepared and supplied.

[0061]

As described above, according to the present invention, it is possible to inexpensively and rapidly adjust or switch the components of the plating bath in the continuous molten metal plating of the metal strip, and particularly to switch the components of the plating bath in a small-volume production. Greatly effective when needed. Further, the second continuous hot-dip metal plating method of the present invention is useful especially when the plating bath components are switched in small-quantity production.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a first continuous hot metal plating method of the present invention.

FIG. 2 is an explanatory view showing an example of operation when switching from the production of galvanized steel sheet to the production of alloyed galvanized steel sheet in the first continuous hot-dip galvanizing method of the present invention.

FIG. 3 is an explanatory view showing an operation example in switching from the production of alloyed hot dip galvanized steel sheet to the production of hot dip galvanized steel sheet in the first continuous hot-dip galvanizing method of the present invention.

FIG. 4 is an explanatory view showing an embodiment of a second continuous hot metal plating method of the present invention.

FIG. 5 is an explanatory view showing an example of operation in switching from the production of galvanized steel sheet to the production of galvannealed steel sheet in the second continuous hot-dip galvanizing method of the present invention.

FIG. 6 is an explanatory view showing another operation example when switching from the production of galvanized steel sheet to the production of alloyed galvanized steel sheet in the second continuous hot-dip galvanizing method of the present invention.

FIG. 7 is an explanatory view showing an operation example in switching from the production of alloyed hot dip galvanized steel sheet to the production of hot dip galvanized steel sheet in the second continuous hot-dip galvanizing method of the present invention.

FIG. 8 is an explanatory view showing an implementation status of a conventional hot metal plating method.

[Explanation of symbols]

1 ... Plating tank, 2 ... Preparation tank, 3 ... Sink roll, 4 ... Gas wiping nozzle, 5 ... Support roll, 6 ... Touch roll, 7 ... Snout, 8a, 8b, 8 '... Molten metal transfer pipe, 9a, 9b … Pump, 10… Small pot, A… Plating bath, B… Molten metal bath

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-232236 (JP, A) JP-A-2-179858 (JP, A) JP-A-59-123753 (JP, A) JP-A-2- 104648 (JP, A) JP-A-8-333664 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 2/00 C23C 2/40

Claims (11)

(57) [Claims] 1. A plating bath (A) held in a plating tank.
In a continuous molten metal plating method for a metal strip, in which a metal strip is continuously immersed in the molten metal to adhere the molten metal to the surface of the metal strip, a plating bath (A) is provided in a preparation bath installed separately from the plating bath. Preparing a molten metal bath (B) for component adjustment or component switching , and forming the molten metal bath (B)
The molten metal of the current operation plating bath (A)
So that it will be near the components of the next operation plating bath when mixed with
It is adjusted in advance and the molten metal in the plating bath (A) is added to the molten metal bath (B).
Of molten metal while transferring it to the molten metal bath.
By transferring from (B) to the plating bath (A),
Plating bath while keeping the bath surface level of bath (A) substantially constant
Both the molten metal of (A) and the molten metal of the molten metal bath (B)
By mixing until the molten metal of the
The components of the plating bath (A) were adjusted or the components were switched, and the components of the plating bath (A) were adjusted or the components were switched.
After that, hold the molten metal from the plating bath (A) with a metal strip.
The molten metal bath is provided with an amount of molten metal corresponding to the amount of squeeze out.
By transferring from (B) to the plating bath (A),
A continuous molten metal plating method for a metal strip, which is characterized by compensating for a reduced amount of molten metal in a plating bath (A) . 2. The amount of molten metal prepared in the molten metal bath (B) for adjusting the components of the plating bath or switching the components,
The method for continuous hot-dip metal plating of a metal strip according to claim 1 , wherein the amount of the molten metal carried out by the metal strip passed through the next operation plating bath is set to be equal to or less than that. 3. A plating bath (A) held in a plating tank.
In the continuous molten metal plating method of a metal strip, in which the metal strip is continuously immersed in the metal strip to adhere molten metal to the surface of the metal strip, a small pot through which the metal strip to be plated can pass is provided in the plating tank. Is arranged in the small pot so that the molten metal in the small pot and the molten metal outside the small pot can be separated and mixed, and the composition of the plating bath (A) is adjusted in a preparation bath installed separately from the plating bath. A molten metal bath (B) for preparing or switching components , and the molten metal bath (B)
Of the bath components of the current operation plating bath (A)
When all of the molten metal or mixed with the molten metal in a small pot is mixed
Of the molten metal in the plating bath (A) or in a small pot
In advance so that the molten metal is in the vicinity of the components of the next operation plating bath
After being adjusted, the molten metal in the plating bath (A) is added to the molten metal bath (B).
Of molten metal while transferring it to the molten metal bath.
By transferring from (B) to the plating bath (A),
Keep the plating bath surface level in a small pot at a constant level
All of the molten metal in the plating bath (A) or in a small pot
Melt both the molten metal and the molten metal in the molten metal bath (B)
By mixing until metal is substantially uniformly performs component adjustment or component switching of the plating bath (A), was subjected to component adjustment or component switching of the plating bath (A)
After that, hold the molten metal from the plating bath (A) with a metal strip.
The amount of molten metal corresponding to the amount of squeeze out is stored in the molten metal bath (B).
From the plating bath (A) to the plating bath
A continuous hot-dip metal plating method for a metal strip, which is characterized by compensating for the reduced amount of hot metal in (A) . 4. The amount of molten metal prepared in the molten metal bath (B) for adjusting the components of the plating bath or switching the components,
The method for continuous hot dip metal plating of a metal strip according to claim 3 , wherein the amount of molten metal carried out by the metal strip passed through the next operation plating bath is set to be equal to or less than that. 5. A plating bath (A) held in a plating tank.
The metal strip is continuously immersed in the molten metal on the surface of the metal strip.
Of continuous metal plating method for metal strips
A small pot through which the metal strip to be plated can pass
Is placed in the plating tank, and the molten metal in the small pot is
And the molten metal outside it can be separated and mixed.
In addition, in the preparation tank installed separately from the plating tank,
Melting for adjusting components of plating bath (A) or for changing components
By the continuous hot dip metal plating method which prepares the metal bath (B)
There, the melt metal in the small pot was separated from a small pot outside the molten metal, in a state that implement the current operation using only the molten metal in a small pot, the molten metal bath and a small pot outside of the molten metal The molten metal of (B) is mixed in advance, and when shifting to the next operation, the molten metal inside the small pot and the molten metal outside the small pot are mixed to adjust the components of the plating bath (A). Alternatively, a method for continuous hot-dip metal plating of a metal strip , which comprises switching components. 6. A plating bath (A) held in a plating tank.
The metal strip is continuously immersed in the molten metal on the surface of the metal strip.
Of continuous metal plating method for metal strips
A small pot through which the metal strip to be plated can pass
Is placed in the plating tank, and the molten metal in the small pot is
And the molten metal outside it can be separated and mixed.
In addition, in the preparation tank installed separately from the plating tank,
Melting for adjusting components of plating bath (A) or for changing components
By the continuous hot dip metal plating method which prepares the metal bath (B)
There are the following (a) ~ continuous molten metal plating process of the metal band and performing a plating operation in accordance with steps (e). (A) Molten metal in the small pot, with the molten metal in the small pot separated from the molten metal outside the small pot, and with the molten metal having components near the next operation plating bath component existing outside the small pot. Step (b) in which the operation is performed using only the molten metal in the molten metal bath (B) prepared for the next operation when the operation in the step (a) shifts to the next operation. Step (c) of adjusting the components of the molten metal in the small pot or changing the components by mixing to make a bath component near the next operation plating bath component (c) A small pot in which the components are adjusted or changed in the step (b) In the state where the molten metal inside and the molten metal outside the small pot are mixed, the step (d) in which the next operation is performed on the entire plating bath (A) When transitioning from the next operation in the step (c) to the next operation , Small After separating the molten metal in the small pot from the molten metal outside the small pot, the molten metal in the molten metal bath (B) prepared for the next operation is mixed with the molten metal in the small pot to produce the next operation plating bath. Step (e) of adjusting the components of the molten metal in the small pot or changing the components by using a bath component in the vicinity of the components (e) Only the molten metal in the small pot whose components have been adjusted or changed in the step (d) is used. The process of performing the next operation 7. A plating bath (A) held in a plating tank.
The metal strip is continuously immersed in the molten metal on the surface of the metal strip.
Of continuous metal plating method for metal strips
A small pot through which the metal strip to be plated can pass
Is placed in the plating tank, and the molten metal in the small pot is
And the molten metal outside it can be separated and mixed.
In addition, in the preparation tank installed separately from the plating tank,
Melting for adjusting components of plating bath (A) or for changing components
By the continuous hot dip metal plating method which prepares the metal bath (B)
There are the following (a) ~ continuous molten metal plating process of the metal band and performing a plating operation in accordance with steps (e). (A) By separating the molten metal in the small pot from the molten metal outside the small pot, and by mixing it with the molten metal in the small pot on the outside of the small pot during the next period of operation, near the components of the next operation plating bath In the state in which a molten metal having a plating bath component that becomes the component of (1) is present, operation is performed using only the molten metal in the small pot (b) The operation in the step (a) is shifted to the next operation At this time, the step (c) of adjusting or changing the components of the plating bath (A) by mixing the molten metal inside the small pot with the molten metal outside the small pot (c) Step (d) of performing the next operation in the entire plating bath (A) (d) When transitioning from the next operation in the step (c) to the next operation, the molten metal in the small pot is separated from the molten metal outside the small pot. After that, the molten metal in the molten metal bath (B) prepared for the next operation is mixed with the molten metal in the small pot to form a bath component in the vicinity of the next operation plating bath component. Step (e) of adjusting the ingredients of the molten metal or switching the ingredients (e) Performing the next-generation operation using only the molten metal in the small pot whose ingredients are adjusted or changed in the step (d) 8. A bath component of a molten metal bath (B) is melted.
Metals are currently in operation All or a small amount of molten metal in the plating bath (A)
Of the plating bath (A) when mixed with the molten metal in the bath
All of molten metal Of molten metal in parts or small pots
The feature is that it is adjusted in advance so that it is close to the bath components.
The continuous molten gold of the metal strip according to claim 5, 6 or 7.
Metal plating method. 9. A method for adjusting the composition of a plating bath or switching the composition
The amount of molten metal prepared in the molten metal bath (B) for
Taken out by a metal strip that runs through the plating bath in the next operation
The amount of molten metal is less than or equal to the amount of molten metal.
Is a continuous hot-dip metal plating method for metal strips according to item 7. 10. The molten metal in the plating bath (A) is a molten metal.
While transferring to the bath (B), about the same amount of molten metal is molten metal bath
By transferring from (B) to the plating bath (A),
Keep the plating bath surface level in a small pot at a constant level
Melting of molten metal from the plating bath (A) and molten metal bath (B)
The method of claim 6 or 7, wherein the molten metal is mixed.
A continuous hot-dip metal plating method for a metal strip as described. 11. Plating with a metal band after the components of the plating bath (A) are adjusted or the components are switched by mixing the molten metal of the plating bath (A) with the molten metal of the molten metal bath (B). The amount of molten metal equivalent to the amount of molten metal carried out from the bath (A) is transferred from the molten metal bath (B) to the plating bath (A), thereby compensating for the reduced amount of molten metal in the plating bath (A). 6. The method according to claim 5,
The continuous hot-dip metal plating method for metal strips according to 6, 7, 8, 9 or 10 .