JP2000119834A - Equipment for continuously manufacturing molten aluminum-molten zinc alloy plated steel plate and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide continuously manufacturing equipment capable of manufacturing a molten Al-Zn alloy plated steel plate excellent in quality, simple in the structure and hardly to generate an operational trouble. SOLUTION: Continuously manufacturing equipment is provided with a hot dip metal coating bath 1, a melting bath 2 to melt Al and Zn in a mixed condition and a transfer means 3 to transfer a molten Al-Zn liguid in the melting bath to a plating vessel, the transfer means is provided with a transfer pipe 4 provided between the melting bath and the plating vessel and a ceramic pump for transferring the molten Al-Zn liguid attached to the transfer pipe, and a molten metal suction port 40 of the transfer pipe is immersed in the melting bath. The molten metal having the same plating composition and approximately the same temperature as the plating vessel can be held in the melting bath, and thus, the molten Al-Zn liquid melted in a uniform composition can be fed into the plating vessel at an arbitrary rate without generating any fluctuation in the temperature by pumping the molten Al-Zn liquid from the melting bath and transferring it to the plating vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facility for continuously producing a hot-dip aluminum-zinc alloy-coated steel sheet and a method for producing a plated steel sheet using this facility.

[0002]

2. Description of the Related Art A hot-dip aluminum-zinc alloy-coated steel sheet represented by a so-called hot-dip 55% aluminum-zinc alloy-coated steel sheet has a corrosion resistance far exceeding that of a normal hot-dip galvanized steel sheet. Since it is low-cost and lightweight (specific gravity is less than half that of zinc), it can be said that it is a promising plated steel sheet as various material steel sheets requiring corrosion resistance.

Conventionally, such a hot-dip galvanized steel sheet having a thickness of 55% aluminum-zinc alloy has been obtained by conventional methods and hot-dip galvanizing methods obtained by a method according to a commonly used method of manufacturing a hot-dip galvanized steel sheet. It is manufactured based on. That is, this hot-dip aluminum-zinc alloy plating is performed by using a so-called hot dipping plating line as used in general hot-dip galvanizing, and putting a molten metal in which aluminum and zinc are mixed into a plating tank (a molten metal pot). However, other equipment configurations are actually implemented by making necessary equipment changes according to the melting point of the molten metal (aluminum + zinc).

[0004] As described above, the background of the fact that the hot-dip 55% aluminum-zinc alloy plating has been performed using the method and the equipment according to the hot-dip galvanizing is the demand itself of the hot-dip 55% aluminum-zinc alloy-plated steel sheet. Because there were not so many, it was pointed out that the study on the manufacturing process and the configuration of the manufacturing equipment was not sufficiently performed.

However, there are the following problems in the manufacturing process and equipment currently used for producing a 55% aluminum-zinc alloy plated steel sheet. First, in molten aluminum-zinc alloy plating, the accuracy of the composition of aluminum and zinc and the uniformity of the plating components are extremely important. For this reason, an ingot in which aluminum and zinc are uniformly mixed is used as an ingot for obtaining molten metal. It is important to prepare and melt this ingot uniformly so that there is no deviation of the components to obtain a molten metal for plating.

As a plating equipment or method for obtaining such a molten metal for plating, a melting tank for an ingot is provided separately from a plating tank, and the melting of the ingot is performed to confirm that the components of the molten metal are stabilized. After confirmation, a method of transferring to a plating tank or a method of providing a melting area in a part of a large plating tank to dissolve the ingot and moving the molten metal to a plating processing section of the plating tank can be considered.
Also, in the former method, means for transferring the molten metal from the melting tank to the plating tank is required, and as a general means for this, the molten metal overflows from the melting tank to the plating tank, or a gutter is provided. It is possible to use a method of transporting by utilizing.

[0007]

However, in the former method, the molten metal near the bath surface in the melting tank in which the bath components and the temperature are not stable is transferred to the plating tank using an overflow or a gutter. The components and temperature of the molten metal supplied to the tank are likely to be non-uniform, and when the molten metal solidifies in the gutter, there is a risk that the molten metal overflows to the surroundings. Further, in the latter method, the plating tank must be enlarged due to structural restrictions, and therefore, it is necessary to dissolve an unnecessarily large amount of molten metal, which causes a problem of increasing equipment costs and running costs. .

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to constantly maintain a molten metal having a constant component and temperature in a plating tank to provide a high-quality hot-dip aluminum-zinc alloy-coated steel sheet. A continuous manufacturing facility for hot-dip aluminum-zinc alloy coated steel sheets and a method for manufacturing plated steel sheets using this equipment, which has a simple structure, is durable, and does not easily cause operational troubles. To provide.

[0009]

The features of the present invention for solving such a problem are as follows. [1] A plating tank for continuously hot-dip aluminum-zinc plating of a steel sheet, a melting tank for dissolving aluminum and zinc in a mixed state, and an aluminum-zinc melt in the melting tank, Transfer means for transferring to the plating tank, the transfer means comprising: a transfer pipe provided between the melting tank and the plating tank; and an aluminum pipe attached to the transfer pipe.
A continuous pumping equipment for a molten aluminum-zinc alloy plated steel sheet, comprising a ceramic pump for transferring a zinc melt, wherein the melt suction port of the transfer pipe is immersed in a bath in a melting tank. .

[2] In the continuous production equipment according to the above [1], at least a portion of the transfer pipe constituting the transfer means, which is in contact with the aluminum-zinc melt, is made of castable ceramics. -Continuous production equipment for zinc alloy plated steel sheets. [3] In the continuous production equipment according to the above [1] or [2], the pump constituting the transfer means is a pump driven by a motor driven by fluid pressure as a driving source. Continuous steel plate manufacturing equipment.

[4] In the continuous production facility of the above [3], a transfer pipe constituting a transfer means is vertically provided in the melting tank and has a melt suction pipe at a lower end thereof; One end is connected in the middle of the melt pumping tube, and the other end is a melt transfer tube extending to the plating tank side. A rotary drive shaft arranged along the direction, which is attached to a lower end of a melt pumping impeller, wherein the rotary drive shaft is connected to a motor disposed above the melt pumping pipe section. Features A continuous manufacturing facility for hot-dip aluminum-zinc alloy plated steel sheets.

[5] In the continuous production equipment according to any one of the above [1] to [4], the melt suction port of the transfer pipe constituting the transfer means is provided at a bath surface with respect to the bath depth D of the dissolving tank. Lower D / 3-2D /
3. A continuous production facility for hot-dip aluminum-zinc alloy-plated steel sheets, wherein the equipment is open at a depth of 3. [6] A method for producing a molten aluminum-zinc alloy plated steel sheet using the continuous production equipment according to any one of [1] to [5], wherein the aluminum-zinc melt in the melting tank is continuously transferred by a transfer means. Alternatively, a method for producing a hot-dip aluminum-zinc alloy-coated steel sheet, which is intermittently transferred to a plating tank.

[0013]

1 to 3 show an embodiment of a continuous manufacturing apparatus for a hot-dip aluminum-zinc alloy-plated steel sheet according to the present invention. In the figure, 1 is a plating tank for continuously hot-dip aluminum-zinc plating of a steel sheet,
Reference numeral 2 denotes a dissolving tank for dissolving and uniformly mixing aluminum and zinc, and 3 denotes a transferring means for transferring the aluminum-zinc melt melted and mixed in the dissolving tank 2 to the plating tank 1. The transfer means 3 comprises a transfer pipe 4 and a ceramic pump 5 attached thereto.

In the equipment of the present invention, a melting tank 2 for melting the ingot and mixing aluminum and zinc is provided separately from the plating tank 1, and the melting of the ingot and the control of the molten metal temperature are performed in the melting tank 2. , And a molten metal having the same temperature as that of the plating bath and the same temperature as the plating bath 1 can be held. Also, from the dissolving tank 2 to the plating tank 1
As for the means of transferring molten metal to the plating bath, the flow control is not stable with the overflow method or the transfer method using gutters, or the molten metal near the bath surface in the melting tank where bath components and temperature are not stable is transferred to the plating tank. Since the transfer is performed, there is a possibility that the components and the temperature of the molten metal supplied to the plating tank may fluctuate. Therefore, the transfer pipe 4 and the ceramic pump 5 attached thereto are used to transfer the molten metal to the melting tank 2. By pumping the aluminum-zinc melt from the bath and transferring it to the plating tank 1, the aluminum-zinc melt dissolved in the uniform component can be supplied to the plating tank 1 at an arbitrary supply amount and temperature fluctuation (temperature drop). It can be supplied without producing any problems.

The basic structure of the plating tank 1 is the same as that of a conventionally known plating tank, and includes a snout 6, a sink roll 7, a heating device 8 (such as an induction heating device) for maintaining the temperature of the molten metal, and the like. It has a configuration. The dissolving tank 2 is
It has a heating device 9 (such as an induction heating device) for maintaining the temperature of the molten metal, and is usually provided adjacent to the plating tank 1.

FIG. 2 shows the details of the transfer means 3. The transfer means 3 includes a transfer pipe 4 provided between the melting tank 2 and the plating tank 1, and an aluminum pipe attached to the transfer pipe 4. A pump 5 made of ceramic for transferring the zinc melt, and the melt suction port 40 of the transfer pipe 4 is immersed in a bath in the dissolution tank 2. The transfer pipe 4 is
A melt pumping pipe section 41 which is vertically installed in the melting tank 2 and has a melt suction port 40 at a lower end, and a melt pumping pipe section 4 at one end.
1 and a melt transfer pipe 42 whose other end extends toward the plating tank 1.

The ceramic pump 5 is
The motor 10 is driven by a motor 10 using a fluid pressure such as air pressure (usually, air pressure) as a drive source. In the present embodiment, the rotary drive shaft 14 disposed along the vertical direction in the melt pumping pipe portion 41 is used. And an impeller 13 for pumping the melt attached to the lower end of the cylinder. And the rotary drive shaft 14
Is a motor 10 disposed above the melt pumping tube 41.
(A motor using a fluid pressure as a drive source), and the driving force of the motor 10 rotates the impeller 13 via the rotary drive shaft 14.

When the pump 5 is composed of the impeller 13 as described above, it is needless to say that the impeller 13 is made of ceramics, but at least a portion of the rotary drive shaft 14 which is in contact with the aluminum-zinc melt. It must be made of ceramics. Here, the term "made of ceramics" includes a structure in which ceramics are coated on the outside of a core material for maintaining strength (for example, a metal core material).

The motor 10 includes a casing 18 provided at an upper end of a melt pumping pipe 41, a rotating blade 19 rotatably provided inside the casing 18, and
A drive fluid is blown into the casing portion 18, and a fluid blowout port 20 for rotating the rotary blade 19 with the drive fluid and a fluid discharge port 21 for letting out the blown fluid are provided. The upper end of the rotary drive shaft 14 that penetrates the casing 18 is connected to the rotary blade 19. According to such a motor 10, the fluid inlet 20
The rotating blades 19 are rotated by a driving fluid (for example, a gas such as air or nitrogen gas, a liquid, etc.) blown from the inside, and the impeller 13 constituting the pump 5 is rotated via the rotary driving shaft 14.

In the case where an electric motor is used as the motor for driving the pump 5, even if the pump 5 cannot be practically driven due to, for example, solidification of molten metal or suction of foreign matter in the transfer pipe, this is not necessary. Pump 5 regardless of
Pump 5 (for example, impeller 13)
May be damaged. Therefore, in the equipment of the present invention, it is important to provide a system that automatically stops the transfer (rotation) when a certain load is applied to the drive mechanism for transferring the molten metal. The most suitable motor for driving the pump 5 is a motor 10 using a fluid pressure such as a gas pressure as a drive source. By using the motor 10 having such a fluid pressure as a driving source, the motor 10 automatically stops driving the pump 5 when a certain load is applied to the motor 10 due to the above-described trouble in pump operation. However, this prevents the pump 5 from being damaged.

The fluid used for the drive source of the motor 10 may be a gas such as air or nitrogen, a liquid such as water, or the like, regardless of the type. Further, in order to supply the aluminum-zinc melt having a uniform composition and temperature to the plating tank 1, the melt suction port 40 at the lower end of the melt pumping pipe 41 is provided with a bath depth D of the melting tank 2. Against the bath
It is preferable that the opening is provided at a depth position of / 3 to 2D / 3, that is, a depth position in the range of X shown in FIG. Since the aluminum-zinc melt at this depth position has particularly uniform components and a stable temperature, pumping the aluminum-zinc melt from this depth position makes it possible to obtain aluminum-zinc having a particularly uniform component and temperature. The melt can be supplied to the plating tank side.

It is preferable that the transfer pipe 4 be made of castable ceramics at a portion that comes into contact with the aluminum-zinc melt. 3A and 3B show a specific cross-sectional structure. FIG. 3A shows a structure suitable for a transfer pipe portion that is not immersed in the aluminum-zinc melt bath (for example, the upper portion of the melt transfer pipe portion 42 or the melt pumping pipe portion 41). The transfer pipe 4 has an inner pipe portion 11a made of castable ceramics in contact with the molten metal, and a metal (for example, stainless steel) reinforcing outer pipe portion 11b provided outside thereof. Also,
FIG. 3B shows a structure suitable for a transfer pipe portion (for example, a lower portion of a melt pumping pipe section 41) immersed in a bath of an aluminum-zinc melt. The inner tube portion 12a and the outermost tube portion 12c that are in contact with each other are made of castable ceramic, and the inner tube portion 12a and the outermost tube portion 12c
A metal (for example, stainless steel) reinforcing outer pipe portion 12b is provided between the outer pipe portion 12b and the outer pipe portion 12b.

The molten metal of aluminum-zinc is highly corrosive to other metals, and even if a metal such as stainless steel is used in a portion of the transfer pipe 4 which comes into contact with the molten metal, it is not suitable for long-term use due to erosion. I can't stand it. For this reason, in the apparatus of the present invention, the castable ceramics are provided in the portion of the transfer tube that contacts the molten metal, ie, the inner tube portion 11a in FIG. 3A and the inner tube portion 12a and the outermost tube portion 12c in FIG. On the other hand, for the outer tube portion 11b in FIG. 3A and the outer tube portion 12b in FIG.

The castable ceramics used for the inner tube portion 11a, the inner tube portion 12a, and the outermost tube portion 12c have poor wettability with molten metal and have a property of repelling molten metal.
Also, the castable ceramic itself is aluminum,
Since it is made of silica, carbon, nitrogen, etc., it does not form a eutectic alloy with the molten metal and does not cause a decrease in melting point. Therefore, the rate of erosion by the molten metal is significantly lower than that of metal materials . Further, the reason why metal is used for the outer tube portions 11b and 12b is that the castable ceramics constituting the inner tube portion 11a, the inner tube portion 12a, and the outermost tube portion 12c are weak in impact resistance and resistant to physical shock. This is because a material having impact resistance is required as the strength retaining member because it is weak. Since this portion does not come into contact with the molten metal, a normal metal material such as stainless steel can be used.

Inner tube part 11 made of castable ceramics
a, since the inner tube portion 12a and the outermost tube portion 12c and the metal outer tube portions 11b and 12b have different coefficients of thermal expansion, in a structure in which these tubes having different coefficients of thermal expansion are brought into direct contact with each other, they are transferred by molten metal When the tube 4 is heated, the tube may be deformed. Therefore, an adhesive between the inner pipe portion 11a and the outer pipe portion 11b, and between each of the inner pipe portion 12a and the outer pipe portion 12b, and between the outer pipe portion 12b and the outermost pipe portion 12c as a buffer material. Preferably, a layer is provided so that the adhesive layer can absorb the difference in thermal expansion between the inner tube and the outer tube and between the outer tube and the outermost tube.

In the apparatus of the present invention having the above-described structure, the rotational driving force of the motor 10 is
Is transmitted to the impeller 13 forming the impeller 13, the impeller 13 rotates, and by the rotation of the impeller 13, the aluminum is introduced into the melt pumping pipe 41 from the melt suction port 40.
After the zinc melt is sucked in, the aluminum-zinc melt rises in the melt pumping tube 41 and then flows into the plating tank 1 through the melt transfer tube 42. In the present embodiment, a sensor 15 for measuring the plating bath surface level is provided above the plating bath 1, and the driving of the pump 5 is controlled according to the plating bath surface level measured by the sensor 15.
For example, by operating the pump 5 intermittently or adjusting the transfer amount of the molten metal, the plating bath surface level of the plating tank 1 can be kept constant.

Next, a method for producing a hot-dip aluminum-zinc alloy-plated steel sheet using the above-described facility of the present invention will be described. The ingot A of aluminum-zinc is automatically supplied to the melting tank 2 at regular intervals by a crane 16 or the like. The steel sheet S coming out of the heating furnace is passed through the snout 6 into the plating tank 1 and is immersed in the aluminum-zinc melt in the plating tank 1. After the steel sheet S is turned upward by the sink roll 7 in the plating tank 1, it is pulled out above the plating tank 1, and the amount of plating applied is adjusted by gas wiping from a gas wiping nozzle 17 or the like.

Although the amount of molten metal in the plating tank 1 is reduced by plating the steel sheet S, the decrease is detected by the sensor 15 for measuring the plating bath surface level, and the pump 5 is operated based on this. Then, the molten metal is transferred from the melting tank 2 to the plating tank 1. The transfer of the molten metal is performed, for example, in a pattern as shown in FIG. In FIG.
The upper figure shows the change of the bath level of the melting tank 2, and
The lower figures shown in (1) and (2) are from melting tank 2 to plating tank 1 respectively.
3 shows a transition of a pattern of a transfer amount of the molten metal to the substrate. Immediately after the ingot A is charged, the temperature of the molten metal in the melting tank 2 drops, and this temperature drop does not hinder the transfer of the molten metal to the plating tank 1 itself. Supplying to No. 1 is not preferable from the viewpoint of ensuring plating quality. For this reason, for a certain period immediately after the ingot is charged, it is preferable not to transfer the molten metal as shown in the pattern (1) of FIG. 4 or to reduce the transfer amount sufficiently as shown in the pattern (2). .

In the melting tank 2, the supplied ingot A is melted and the temperature of the molten metal is controlled, and the molten metal which is the same as the plating component and has substantially the same temperature as the plating tank 1 is held.
The transfer of the molten metal from the melting tank 2 to the plating tank 1 is performed by the transfer pipe 4 having the melt suction port 40 immersed in the bath of the melting tank 2 and the ceramic pump 5 attached thereto. In addition, it is possible to transfer the aluminum-zinc melt dissolved in the uniform component while controlling the transfer amount arbitrarily and without causing the temperature fluctuation of the molten metal.

Since the pump 5 constituting the transfer means 3 is made of ceramics, it has corrosion resistance to high-temperature molten metal and can withstand long-term use. In addition, since the pump 5 is driven by the motor 10 which uses a fluid pressure such as air as a driving source, the pump 5 cannot be practically driven due to, for example, solidification of molten metal or suction of foreign matter in the transfer pipe. When the load is applied, the motor 10 automatically stops driving the pump 5, so that damage to the pump 5 can be prevented.

A transfer pipe 4 constituting the transfer means 3
Uses castable ceramics for the inner tube portion 11a, the inner tube portion 12a, and the outermost tube portion 12c that come into contact with the molten metal, and uses a metal material for the outer tube portions 11b and 12b. It can sufficiently withstand mechanical shocks. When the melt suction port 40 of the transfer pipe 4 is opened at a depth of D / 3 to 2D / 3 below the bath surface with respect to the bath depth D in the dissolving tank, this depth position is set. In the aluminum-zinc melt, the components are uniform and the temperature is stable.
The zinc melt can be supplied to the plating tank 1.

There are no particular restrictions on the hot-dip aluminum-zinc alloy-plated steel sheet to be manufactured by the apparatus of the present invention.
Hot-dip aluminum-galvanized alloy steel sheet containing 30 to 95 wt% of zinc, especially hot-dip aluminum with a high aluminum content in a plating film represented by a hot-dip 55% Al-Zn alloy-plated steel sheet (so-called galvalume)
It is particularly suitable for producing a zinc alloy plated steel sheet.

[0033]

As described above, according to the equipment of the present invention,
It is possible to manufacture high quality hot-dip aluminum-zinc alloy coated steel sheet by always maintaining the molten metal of a certain component and temperature in the plating tank, and the structure is simple and durable. There is an advantage that troubles are less likely to occur.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the facility of the present invention.

FIG. 2 is an explanatory view showing a transfer pipe portion provided with a pump and a motor which constitute transfer means of the equipment of FIG. 1;

FIG. 3 is a sectional view of a transfer pipe constituting a transfer means of the equipment of FIG. 1;

FIG. 4 is a graph showing an example of the transition of the bath surface level of the melting tank of the equipment of the present invention and the transition of the amount of the molten metal transferred from the melting tank to the plating tank.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plating tank, 2 ... Dissolution tank, 3 ... Transfer means, 4 ... Transfer pipe, 5 ... Pump, 6 ... Snout, 7 ... Sink roll, 8
... heating device, 9 ... heating device, 10 ... motor, 11a ... inner tube, 11b ... outer tube, 12a ... inner tube, 12b ... outer tube, 12c ... outermost tube, 13 ... impeller, 14 ... Rotary drive shaft, 15 sensor, 16 crane, 17 gas wiping nozzle, 18 casing part, 19 rotating blades, 20 fluid inlet, 21 fluid outlet, 40 melt inlet, 41 Melt pumping pipe section, 42: melt transfer pipe section, S: steel plate, A: ingot

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuyuki Ishida 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Teruhisa Kuwana 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Toshihiko Oi 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Kazumi Jiromaru 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Nippon Kokan Co., Ltd. 4K027 AA02 AA22 AB44 AB48 AD05 AD08 AE02 AE06 AE08

Claims (6)

[Claims] 1. A plating tank for continuously hot-dip aluminum-zinc plating of a steel sheet, a melting tank for melting aluminum and zinc in a mixed state, and an aluminum-zinc melt in the melting tank And a transfer pipe provided between the dissolving tank and the plating tank, and a ceramic for transferring the aluminum-zinc melt attached to the transfer pipe. A continuous manufacturing facility for a hot-dip aluminum-zinc alloy-plated steel sheet, comprising: a pump made of stainless steel; 2. A hot-dip aluminum-zinc alloy-plated steel sheet according to claim 1, wherein at least a portion of the transfer tube constituting the transfer means that comes into contact with the aluminum-zinc melt is made of castable ceramics. Continuous production equipment. 3. The continuous production of a molten aluminum-zinc alloy plated steel sheet according to claim 1, wherein the pump constituting the transfer means is a pump driven by a motor driven by a fluid pressure. Facility. 4. A transfer pipe constituting transfer means, which is suspended in a melting tank and has a melt suction port at a lower end, and one end of which is located in the middle of the melt pumping pipe. And a melt transfer pipe part having the other end extending to the plating tank side, and a pump constituting a transfer means is provided with a rotary drive shaft arranged vertically along the melt pumping pipe part. 4. The molten aluminum according to claim 3, comprising a melt pumping impeller attached to a lower end, wherein the rotary drive shaft is connected to a motor disposed above the melt pumping tube. -Continuous production equipment for zinc alloy plated steel sheets. 5. A method according to claim 1, wherein the melt suction port of the transfer pipe constituting the transfer means has a bath depth D / 3 to 2D below the bath depth D of the dissolving tank.
The continuous manufacturing equipment for a hot-dip aluminum-zinc alloy-plated steel sheet according to claim 1, wherein the opening is provided at a depth of. 6. A method for producing a molten aluminum-zinc alloy plated steel sheet using the equipment according to claim 1, wherein the aluminum-zinc melt in the melting tank is transferred by a transfer means. A method for producing a hot-dip aluminum-zinc alloy-plated steel sheet, which is continuously or intermittently transferred to a plating tank.