JP2000210761A - Continuous casting method, molten metal pouring mechanism and molten metal pouring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous steel casting method by which the time for pouring the molten steel into a tundish can be extended in the state of closing a sliding nozzle. SOLUTION: When the molten steel in the tundish 1 is supplied into a mold from a molten steel pouring hole 3 provided at the bottom part through an upper nozzle 4, sliding nozzle 5 and immersion nozzle 6 and continuously cast, the upper nozzle 4 is heated to >=800 deg.C by a heater 21 provided inside the upper nozzle 4 and the sliding nozzle 5 is heated to >=500 deg.C by the heater provided inside the sliding nozzle 5, or the gas heated to >=600 deg.C through the sliding nozzle 5 is supplied into the molten steel, thereby the molten steel is poured into the tundish 1 in the state of closing the sliding nozzle 5, while stirring the molten steel, and then the sliding nozzle 5 is opened to start the casting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting method, a molten metal injection mechanism for injecting molten metal from a molten metal holding container such as a ladle, and a molten metal injection method.

[0002]

2. Description of the Related Art In continuous casting of steel, it is known that if molten steel is poured from a ladle into a tundish and then cast into a mold, the amount of inclusions at the tip of a slab decreases. However, the temperature around the sliding nozzle, which controls the flow rate of molten steel from the tundish to the mold, is low,
When closing the sliding nozzle and pouring molten steel into the tundish, the temperature of the molten steel that has accumulated around the sliding nozzle drops and gradually solidifies.If the time required for pouring is long, open the sliding nozzle after pouring. However, the molten steel may not flow out to the mold. Therefore, the time required for pouring molten steel is limited to a short time, and there is a problem that a desired amount cannot be poured.

In order to solve this problem, a method of reducing the temperature drop of molten steel around a slide nozzle by using a sliding nozzle having gas injection holes and injecting Ar gas into a tundish and stirring the molten steel while pouring the molten steel has been implemented. However, at present, an extension of the pouring time sufficient to pour the desired amount has not been achieved.

Japanese Patent Application Laid-Open No. 9-57429 proposes a method in which a sliding nozzle is heated from a dipping nozzle side by a rod-shaped heater. However, the present inventors have studied and found that a heater is installed in an outflow path of molten steel. Therefore, at the start of casting, the amount of heat required to melt the heater is taken away from the molten steel, so that clogging of the immersion nozzle occurs,
There is a problem that the composition of the molten steel may change.

Further, when a small amount of steel is melted, a method of closing the sliding nozzle, holding the molten steel, performing processing, opening the sliding nozzle, flowing out the molten steel and casting the molten steel in order to adjust and mix the components in the tundish. However, there is a problem that the time for holding and treating the molten steel is limited to a short time for the above-described reason, and the purpose cannot be sufficiently achieved.

On the other hand, a molten metal holding container used for metal production, for example, a ladle for molten steel used for steel production, uses a sliding plate having a nozzle hole, such as a slide valve, a sliding nozzle or a rotary nozzle, to form a molten steel. And a nozzle having a mechanism for adjusting the injection start / stop and the injection amount.

Conventionally, in order to prevent the molten steel from solidifying and clogging in the nozzle hole between the receiving steel and the start of the flow of molten steel, the nozzle hole is filled with a granular refractory before receiving the steel. Material is filled.

In such a filler, the refractory in the upper layer forms a sintered layer before the steel is received due to the residual heat of the ladle or the preheating to the steel reception. By growing this sintered layer to an appropriate thickness, the filler is prevented from floating and separating by the molten steel flow, the molten steel is prevented from penetrating and solidifying into the filler, and the nozzle is slid. By sliding the moving plate, the sintered layer is destroyed by the weight of the molten steel, and the nozzle hole can be opened.

However, when the formation of the sintered layer is insufficient, the filler floats and separates at the time of receiving the steel, and there is a problem that the molten steel permeates and solidifies the filler, so that the nozzle hole is not opened. On the other hand, if the sintered layer is too thick, there is a problem in that even if the nozzle hole is opened, the sintered layer of the molten steel of its own weight cannot be destroyed and does not open.

In order to solve such a problem, for example, Japanese Unexamined Patent Publication No. 10-58127 discloses that a filling layer is composed of (1) an upper filling layer and a lower filling layer, and (2) each filling layer is made of SiO. ₂ is a filler composed mainly of, it is disclosed that (3) the upper part filler is a mixture of 1 to 15% by weight of further glass beads filler mainly composed of SiO ₂ in outer percentage ing. By adjusting the amount of glass beads added to the molten steel temperature, the degree of sintering of the SiO ₂ -based filler, particularly the upper packed layer, can be finely controlled in accordance with each use condition and operating condition, It is stated that the nozzle opening ratio can be increased.

In Japanese Patent Application Laid-Open No. 10-109157, the filler filled in the nozzle holes is covered with a sheet-like refractory, and the sheet-like refractory is made of a material which is softened and deformed by heating. (1) A structure in which a sheet-like refractory is further covered on a sheet-like refractory (2) A hollow cup is arranged at a lower portion in a nozzle hole, and gas is blown into a sliding plate at the time of opening. (3) Weirs are provided around the nozzle opening at the bottom of the ladle to prevent the impact of molten steel flowing into the nozzle hole when receiving steel. By doing so, the separation and floating of the filler at the time of receiving steel, the intrusion of molten steel into the filler filled in the nozzle hole is prevented, or the sintered layer of the filler is prevented from becoming too thick, and the nozzle hole is In case of blockage, Filling structure and opening methods may be removed braking manner filler is disclosed.

However, Japanese Unexamined Patent Application Publication No. 10-581
No. 27 and Japanese Patent Application Laid-Open No. 10-109157, fillers and sheet-like refractories are mixed into molten steel at the start of molten steel injection from a nozzle, and harmful non-metallic inclusions and molten steel such as carbon pickup are mixed. Cause contamination. In the technique disclosed in Japanese Patent Application Laid-Open No. H10-58127, a filler containing SiO ₂ as a main component is employed in consideration of this point. However, the filler temporarily drops and mixes into molten steel. This is unavoidable and is still inadequate. After all, it is the present situation that the inconvenience caused by the presence of the filler has not been solved by the conventional technology, and ultimately, a technique of opening the nozzle hole of the ladle without using such a filler is desired. ing.

Meanwhile, in continuous casting, a phenomenon occurs in which alumina adheres to and grows on the inner wall side of the nozzle for injecting molten metal in the tundish and the inner wall of the immersion nozzle during casting. This is because molten metal, for example, aluminum as a deoxidizer added to steel is reoxidized by slag in a ladle or free oxygen in the molten metal to become alumina (Al ₂ O ₃ ),
This is to adhere to the inner surface of the immersion nozzle or the like.

If the adhesion of alumina is too thick, casting will be hindered, and eventually casting must be stopped. In addition, when large alumina adhered to the inner wall of the immersion nozzle is peeled off and enters the mold, it may become a large inclusion and lead to defects in the cast slab.

To solve this problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 58-151948, nozzle blockage is prevented while blowing inert gas from the tip of the stopper and the immersion nozzle, and continuous casting for a long time is performed. Technology that allows for

However, when the argon gas is simply blown in this way, the gas expands greatly in the molten metal, and when the molten metal flows into the mold and the argon bubbles float in the mold, the argon bubbles burst and the mold powder is removed. Highly likely to induce entrapment. If the argon gas flow rate is reduced to avoid this, the possibility of nozzle clogging increases, so that a certain argon gas flow rate must be secured.

If the gas flow rate is large in addition to the powder entrainment as described above, the gas cannot completely float in the mold,
It may remain in the slab and lead to surface defects called "bros".

As described above, when argon gas is simply blown, it is necessary to restrict the flow rate for reasons of operation and quality, and as a result, the casting length is continuously reduced so that nozzle blockage due to alumina does not occur. We still have to regulate.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a continuous casting method capable of extending a time for pouring molten steel into a tundish with a sliding nozzle closed. The purpose is to provide.

Further, without using a nozzle filler,
An object of the present invention is to provide a molten metal injection mechanism and a molten metal injection method capable of reliably opening a nozzle of a molten metal holding container and preventing contamination of the molten metal caused by mixing of a nozzle filler into the molten metal. And

Further, in a tundish having a molten metal outflow hole at the bottom, the quality of the cast slab is not deteriorated.
An object of the present invention is to provide a continuous casting method capable of preventing nozzle blockage.

[0022]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have obtained the following knowledge. First, from the viewpoint of prolonging the time for pouring molten steel into the tundish with the sliding nozzle closed, the following four points can be cited.

(1) In order to reduce heat loss from the upper nozzle portion (mainly, heat storage loss of the upper nozzle portion) in the path for guiding the molten steel to the sliding nozzle for controlling the flow of the molten steel, a heater is incorporated in the upper nozzle, It is effective to heat to a predetermined temperature or more even during preheating.

(2) In order to reduce the heat loss (heat storage loss of the plate and heat dissipation loss to the back surface) of the sliding nozzle surface which is estimated to have the largest heat dissipation, a heater is incorporated in the sliding nozzle plate and preheating is performed. At times, it is effective to heat to a predetermined temperature.

(3) A sliding nozzle having a gas injection hole is used to heat a gas such as an argon gas to be blown to agitate the molten steel and to reduce sensible heat lost by the molten steel when the gas is heated by the molten steel. The Ar gas blown during the pouring is heated and blown into the tundish and stirred.

(4) The pouring time can be further extended by combining two or three of these, rather than performing them alone.

Also, without using a nozzle filler,
From the viewpoint of reliably opening the nozzle of the molten metal holding container, it has been found that heating around the nozzle hole of the molten metal holding container is effective.

Further, in order to prevent the nozzle from being clogged without deteriorating the quality of the slab, the inert gas is not simply blown into the molten metal flowing through the molten metal outflow nozzle, but is heated and then injected. I found something to do.

The present invention has been made based on these findings, and provides the following (1) to (18).

(1) A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle, and an immersion nozzle to continuously perform casting. Providing a heater inside the upper nozzle, heating the upper nozzle to 800 ° C. or higher by the heater, and pouring molten steel into the tundish with the sliding nozzle closed.
Thereafter, the casting is started by opening the sliding nozzle.

(2) A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle and an immersion nozzle to continuously perform casting. A heater is provided inside the sliding nozzle, the surface temperature of the tundish side is heated to 500 ° C. or more with the sliding nozzle closed, and molten steel is poured into the tundish, and then the sliding nozzle is opened to perform casting. Starting a continuous casting method.

(3) A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle, and an immersion nozzle to continuously perform casting. While the sliding nozzle is closed, a gas heated to 600 ° C. or higher is supplied to the molten steel through the sliding nozzle to stir the molten steel, and the molten steel is poured into the tundish, and then the sliding nozzle is opened. A continuous casting method characterized by starting casting.

(4) A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle, and an immersion nozzle to continuously perform casting. A heater is provided inside the upper nozzle and the inside of the sliding nozzle, and the upper nozzle is heated to 800 ° C. or more and the sliding nozzle is heated to 500 ° C. or more with the heater in a state where the sliding nozzle is closed. Continuous casting method characterized by pouring molten steel into a steel sheet and then opening a sliding nozzle to start casting.

(5) A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle, and an immersion nozzle to continuously perform casting. A heater is provided inside the sliding nozzle, and when the sliding nozzle is closed, the surface temperature on the tundish side is set to 50.
While heating to 0 ° C. or higher, and supplying the gas heated to 600 ° C. or higher to the molten steel through the sliding nozzle and stirring the molten steel, the molten steel is poured into the tundish, and then the sliding nozzle is opened to perform casting. Starting a continuous casting method.

(6) A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at the bottom thereof through an upper nozzle, a sliding nozzle, and an immersion nozzle to continuously perform casting. A heater is provided inside the upper nozzle and inside the sliding nozzle, and the upper nozzle is heated to 800 ° C. or more by a heater in a state where the sliding nozzle is closed, and is heated to 600 ° C. or more via the sliding nozzle. A continuous casting method comprising: pouring molten steel into the tundish while stirring the molten steel by supplying the molten gas to the molten steel; and then opening a sliding nozzle to start casting.

(7) A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle, and an immersion nozzle to continuously perform casting. Providing a heater inside the upper nozzle and inside the sliding nozzle, heating the upper nozzle to 800 ° C. or higher, the sliding nozzle to 500 ° C. or higher by a heater in a state where the sliding nozzle is closed, and Continuous casting method characterized in that the molten steel is poured into the tundish while stirring the molten steel by supplying a gas heated to 600 ° C. or higher to the molten steel, and then a sliding nozzle is opened to start casting. .

(8) A molten metal injection mechanism which is provided at a lower portion of the molten metal holding container and injects the molten metal stored in the molten metal holding container, wherein the upper nozzle is provided at a molten metal outlet of the molten metal holding container. A fixing plate having a nozzle hole fixed to a lower portion of the upper nozzle, a sliding member having a sliding plate that slides on the fixing plate and opens and closes a molten metal outlet, and a sliding member fixed to the sliding plate. A molten metal injection mechanism comprising: a lower nozzle that moves together with a moving plate; and a heating unit that heats at least one of the sliding plate and the upper nozzle.

(9) The molten metal injection mechanism according to (8), wherein the heating means has an electric heating element provided in the upper nozzle so as to go around the outer periphery of the nozzle hole.

(10) In the above (8) or (9), the heating means has an electric heating element provided around the outer periphery of the nozzle hole in the fixing plate. mechanism.

(11) In any one of the above (8) to (10), molten steel does not enter at least one of the molten metal contact surfaces at the nozzle closed position of the sliding plate or at a position near the fixed plate of the upper nozzle. A molten metal injection mechanism having a fine diameter of the order and having a large number of holes formed therein for injecting gas whose temperature has been raised in advance into the molten metal.

(12) A molten metal injection method for injecting molten metal from a molten metal holding container using the molten metal injection mechanism according to any one of (8) to (11), wherein molten steel is used as the molten metal. When the liquidus temperature of the molten steel is _TL , the temperature of the molten steel contact surface of the upper nozzle and the fixed plate is T
_{L. A} method for injecting molten metal, comprising heating to a temperature of -550 ° C or higher.

(13) A method for injecting molten metal from a molten metal holding container using the molten metal injection mechanism of (11) above, wherein molten steel is used as the molten metal, and the temperature of a gas blown into the molten steel is set to 600 ° C. or more. A method for injecting a molten metal.

(14) The molten metal injection mechanism according to any one of (8) to (11) is provided in a ladle as a molten metal holding container, and the molten metal is directly injected from the ladle into the continuous casting mold. A method for injecting a molten metal, characterized in that:

(15) In the method of the above (12) or (13), the molten metal holding container is a ladle, and the molten steel is poured directly from the ladle into a continuous casting mold. Injection method.

(16) A continuous casting method in which a molten metal in a tundish is supplied to a mold through a molten metal outflow nozzle provided at a bottom portion of the tundish through a molten metal outflow nozzle to perform continuous casting, wherein the molten metal outflow nozzle is provided. A preheated inert gas is blown into the molten metal flowing out of the nozzle hole of the nozzle from an arbitrary position.

(17) The continuous casting method according to the above (16), wherein the heating temperature of the gas is 800 ° C. or more.

(18) The continuous casting method according to the above (16) or (17), wherein the distance between the heating device for heating the gas and the gas blowing section is set to within 1000 mm.

[0048]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a schematic sectional view showing a continuous casting facility to which a first embodiment of the present invention is applied. The molten steel 2 flows into the tundish 1 from a ladle 11 disposed thereon via a long nozzle 12. A molten steel outlet 3 is formed at the bottom of the tundish 1, and an upper nozzle 4 is fitted therein. A sliding nozzle 5 for opening and closing the nozzle hole and adjusting the flow rate of the molten steel is provided below the upper nozzle 4, and a dipping nozzle 6 is provided below the sliding nozzle 5. Then, molten steel is continuously supplied from the immersion nozzle 6 to the mold (mold) 7,
The molten steel becomes a slab in a semi-solid state in the mold, and is drawn out while being guided by a roll (not shown) to form a slab completely solidified. Although only one molten steel outlet 3 of the tundish 1 is shown in FIG. 1, it is actually provided at two locations on both sides of the bottom of the tundish 1.

Next, the structure around the sliding nozzle in the continuous casting facility for carrying out the first method of the present embodiment will be described. As shown in FIG. 2, the tundish 1 is provided with a refractory 1a and a steel shell 1b outside the refractory 1a.
Is fitted. The nozzle hole 4 is provided in the upper nozzle 4.
An electric heater 21 is built in the vicinity of a, and power is supplied to the electric heater 21 from a power source (not shown) via a wiring 22. In addition, the temperature of the heater 21 is the thermocouple 2
3 is controlled by a controller (not shown) based on the signal from the controller 3.

The sliding nozzle 5 provided below the upper nozzle 4 is provided with a fixed plate 5 fixed to the upper nozzle 4.
a, and a sliding plate 5b slidably provided thereunder and to which the immersion nozzle 6 is fixed.
The sliding nozzle 5 is a sliding plate 5
b has a function of opening and closing the nozzle hole 4a and a flow rate adjusting function by adjusting the position of the nozzle hole 5c formed by sliding horizontally. A plug 24 having a number of holes through which argon gas is blown toward the nozzle hole 4a when the nozzle hole 4a is closed is provided in the stopper portion of the sliding plate 5b. Is supplied with argon gas.

In order to carry out the present method with such an apparatus configuration, first, power is supplied to the electric heater 21 and the upper nozzle 4 is supplied.
Is preheated, and the temperature is set to 800 ° C. or higher. Next, with the sliding nozzle 5 closed, the molten steel is supplied from the ladle 11 into the tundish 1 to start pouring the molten steel. When the molten steel in the tundish 1 reaches a predetermined height, the supply of the molten steel is stopped, and if necessary, the components are adjusted. Then, the sliding nozzle 5 is opened to transfer the molten steel in the tundish 1 to the mold 7. Supply.

In this case, the upper nozzle 4 is set to 800
° C or higher, the occurrence of nozzle clogging due to the temperature drop of the molten steel remaining between the nozzle hole 4a and the sliding nozzle 5 is suppressed, and the molten steel is tanned with the sliding nozzle 5 closed. The time for pouring into the dish 1 can be lengthened. If the heating temperature of the upper nozzle 4 is lower than 800 ° C., the effect of extending the pouring time is insufficient.

Next, the structure around the sliding nozzle in the continuous casting facility for implementing the second method of the present embodiment will be described. As shown in FIG. 3, here, the electric heater 26 is incorporated in the lower part of the plug 24 inside the sliding plate 5b instead of the electric heater 21 embedded in the upper nozzle 4 of the first embodiment. Except for this, the configuration is the same as the equipment of the first embodiment. The electric heater 26 is supplied with power from a power source (not shown) via a wiring 27. The temperature of the heater 26 is controlled by a controller (not shown) based on a signal from the thermocouple 28.

In order to carry out the present method with such an apparatus configuration, first, while the sliding nozzle 5 is closed, power is supplied to the electric heater 26 to preheat the sliding plate 5b, and the temperature is set to 500 ° C. or higher. . Next, the molten steel is supplied from the ladle 11 into the tundish 1 with the sliding nozzle 5 kept closed, and the pouring of the molten steel is started. When the molten steel in the tundish 1 reaches a predetermined height, the supply of the molten steel is stopped, and if necessary, the components are adjusted. Then, the sliding nozzle 5 is opened to transfer the molten steel in the tundish 1 to the mold 7. Supply.

In this case, since the sliding plate 5b is heated to 500 ° C. or higher at the time of preheating, nozzle clogging due to a drop in the temperature of the molten steel remaining between the nozzle hole 4a and the sliding nozzle 5 may occur. It is possible to prolong the time for pouring molten steel into the tundish 1 while the sliding nozzle 5 is closed while suppressing the movement. The heating temperature of the sliding plate 5b is 5
If the temperature is lower than 00 ° C., the effect of extending the pouring time is insufficient.

Next, the structure around the sliding nozzle in the continuous casting facility for carrying out the third method of this embodiment will be described. As shown in FIG. 4, here, except that the electric heater 29 is provided near the plug 24 in the gas pipe 25 instead of the electric heater 21 embedded in the upper nozzle 4 of the first embodiment. It has the same configuration as the equipment of the first embodiment. The electric heater 29 is supplied with power from a power source (not shown) via a wiring 30. The temperature of the heater 29 is controlled by a controller (not shown) based on a signal from the thermocouple 31.

In order to carry out the present method with such an apparatus configuration, while the sliding nozzle 5 is closed, a power is supplied to the heater 29 and an argon gas heated to 600 ° C. or more is blown from the plug 24 to the ladle. The molten steel is supplied into the tundish 1 from 11 and the pouring of the molten steel is started. When the molten steel in the tundish 1 reaches a predetermined height, the supply of the molten steel is stopped, and if necessary, the components are adjusted. Then, the sliding nozzle 5 is opened to transfer the molten steel in the tundish 1 to the mold 7. Supply.

In this case, since the argon gas blown from the plug 24 at the time of preheating is heated to 600 ° C. or higher, the nozzle due to the temperature drop of the molten steel staying from the nozzle hole 4a to the sliding nozzle 5 The occurrence of clogging is suppressed, and the time for pouring molten steel into the tundish 1 with the sliding nozzle 5 closed can be lengthened. If the temperature of the argon gas to be blown is lower than 600 ° C., the effect of increasing the pouring time is insufficient.

Next, the structure around the sliding nozzle in the continuous casting facility for carrying out the fourth method of this embodiment will be described. As shown in FIG. 5, here, an example is shown in which the heater 21 in the first embodiment and the heater 26 in the second embodiment are used in combination.

In the present method, with the sliding nozzle 5 closed, first, power is supplied to the electric heater 21 to preheat the upper nozzle 4, the temperature is set to 800 ° C. or higher, and the electric heater 26 is further supplied with power to perform sliding. The plate 5b is preheated to a temperature of 500 ° C. or higher. Next, the molten steel is supplied from the ladle 11 into the tundish 1 with the sliding nozzle 5 kept closed, and the pouring of the molten steel is started. When the molten steel in the tundish 1 reaches a predetermined height, the supply of the molten steel is stopped, and if necessary, the components are adjusted. Then, the sliding nozzle 5 is opened to transfer the molten steel in the tundish 1 to the mold 7. Supply.

In this case, the molten steel is poured into the tundish 1 with the upper nozzle 4 heated to 800 ° C. or higher and the sliding plate 5b heated to 500 ° C. or higher. The effect of suppressing the occurrence of nozzle clogging due to the temperature drop of the molten steel staying before reaching can be enhanced as compared with the case where these are individually performed, and the molten steel is placed in the tundish 1 with the sliding nozzle 5 closed. The time for pouring into the container can be further lengthened.

Next, the structure around the sliding nozzle in the continuous casting facility for carrying out the fifth method of this embodiment will be described. As shown in FIG. 6, here, an example is shown in which a heater 26 in the second embodiment and a heater 29 in the third embodiment are used in combination.

In the present method, while the sliding nozzle 5 is closed, first, power is supplied to the electric heater 26 to preheat the sliding plate 5b, and the temperature is reduced to 50%.
0 ° C or higher. Next, the molten steel is supplied from the ladle 11 into the tundish 1 while the argon gas heated to 600 ° C. or more is blown from the plug 24 by supplying power to the heater 29, and pouring of the molten steel is started. When the molten steel in the tundish 1 reaches a predetermined height, the supply of the molten steel is stopped, and if necessary, the components are adjusted. Then, the sliding nozzle 5 is opened to transfer the molten steel in the tundish 1 to the mold 7. Supply.

In this case, the sliding plate 5b
Is heated to 500 ° C. or higher, and molten steel is poured into the tundish 1 while blowing argon gas heated to 600 ° C. or higher, so that the molten steel stays between the nozzle hole 4 a and the sliding nozzle 5. The effect of suppressing the occurrence of nozzle clogging due to the temperature drop of the molten steel can be enhanced as compared with the case where these are individually performed, and the time for pouring the molten steel into the tundish 1 with the sliding nozzle 5 closed is longer. can do.

Next, the structure around the sliding nozzle in the continuous casting facility for carrying out the sixth method of this embodiment will be described. As shown in FIG. 7, here, an example is shown in which the heater 21 in the first method and the heater 29 in the third method are used in combination.

In the present method, with the sliding nozzle 5 closed, power is first supplied to the electric heater 21 to preheat the upper nozzle 4, and the temperature is set to 800 ° C. or higher.
Next, power is supplied to the heater 29 so that
The molten steel is supplied from the ladle 11 into the tundish 1 while blowing argon gas heated to a temperature of not less than ° C., and the pouring of the molten steel is started. When the molten steel in the tundish 1 reaches a predetermined height, the supply of the molten steel is stopped, and if necessary, the components are adjusted. Then, the sliding nozzle 5 is opened to transfer the molten steel in the tundish 1 to the mold 7. Supply.

In this case, while the upper nozzle 4 is heated to 800 ° C. or higher, molten steel is poured into the tundish 1 while blowing argon gas heated to 600 ° C. or higher. 5
The effect of suppressing the occurrence of nozzle clogging due to the temperature drop of the molten steel staying before reaching can be enhanced as compared with the case where these are individually performed, and the molten steel is tundished with the sliding nozzle 5 closed. The time for pouring into 1 can be further lengthened.

Next, the structure around the sliding nozzle in the continuous casting facility for carrying out the seventh method of the present invention will be described. As shown in FIG. 8, here, an example is shown in which the heater 21 of the first embodiment, the heater 26 of the second embodiment, and the heater 29 of the third embodiment are all used.

In the present method, with the sliding nozzle 5 closed, first, the electric heater 21 is supplied with power to preheat the upper nozzle 4, the temperature is set to 800 ° C. or higher, and the electric heater 26 is further supplied with power to slide. The plate 5b is preheated to a temperature of 500 ° C. or higher. Next, while supplying power to the heater 29 and blowing argon gas heated to 600 ° C. or more from the plug 24, the ladle 1
The molten steel is supplied from 1 into the tundish 1 and pouring of the molten steel is started. When the molten steel in the tundish 1 reaches a predetermined height, the supply of the molten steel is stopped, and if necessary, the components are adjusted. Then, the sliding nozzle 5 is opened to transfer the molten steel in the tundish 1 to the mold 7. Supply.

In this case, the upper nozzle 4 is heated to 800 ° C. or more, and the sliding plate 5b is heated to 500 ° C.
In the heated state, the molten steel is poured into the tundish 1 while blowing argon gas heated to 600 ° C. or more, so that the molten steel remaining between the nozzle hole 4 a and the sliding nozzle 5 is removed. The effect of suppressing the occurrence of nozzle clogging due to a temperature drop can be enhanced as compared with the case where these are individually performed and the case where two of them are combined, and the molten steel is placed in the tundish 1 with the sliding nozzle 5 closed. The time for pouring into the garment can be further lengthened.

Next, a modification of the second method will be described. In the second method, the heater 26 is provided below the argon gas blowing plug 24. However, as shown in FIG. 9, the heater 2 is disposed between the plug 24 and the nozzle hole 5c.
6 may be provided. In this case, the sliding plate 5b is preheated by the heater 26, and then,
With the sliding nozzle 5 kept closed, the injection of molten steel is started while blowing argon gas from the plug 24, and when the molten steel in the tundish 1 reaches a predetermined height, the supply of molten steel is stopped, and the sliding is stopped. The sliding nozzle 5 is opened by sliding the plate 5b. However, as shown in FIG. 10, the heater 26 passes through the position of the nozzle hole 4a during the opening of the sliding nozzle 5, so that the sliding plate 5b is opened. At this time, there is added an effect that the solidified film of the molten steel is prevented from being formed and the molten metal cannot be poured. That is, when the temperature between the nozzle hole 5c of the sliding plate 5b where the nozzle 24 is present and the nozzle hole 5c is low, a solidified film is instantaneously formed when the sliding plate 5b slides, and pouring is impossible. However, such a risk can be avoided by actively heating the portion with the heater 26.

In the above first embodiment, the illustrated device configuration is merely an example, and the present invention is not limited thereto. For example, although the sliding nozzle is of a type that slides the sliding plate linearly, a rotary nozzle that rotates the sliding plate may be used. Further, the sliding nozzle may have a structure in which a sliding plate is sandwiched between an upper plate and a lower plate. Furthermore, the gas blown when pouring molten steel is not limited to argon gas, and any gas that does not adversely affect molten steel can be used.

(Second Embodiment) This embodiment shows a configuration in which a ladle is used as a molten metal outflow container, and molten steel can be injected from the ladle without using a nozzle filler.

FIG. 11 is a sectional view showing an example of a molten metal injection mechanism according to this embodiment. A molten steel pouring mechanism 41 is provided at the bottom of the ladle 40. This molten steel injection mechanism 41
Is a sliding member 45 including an upper nozzle 42, a fixed plate 43, and a sliding plate 44 slidably provided on the fixed plate 43.
And a lower nozzle (collector nozzle) 46 provided below the sliding plate 44. The sliding member 45 and the lower nozzle 46 constitute a rotary nozzle. These are provided with nozzle holes 47, and the nozzle holes 47 are opened and closed by moving the sliding plate 44. A receiving nozzle 48 is provided between the upper nozzle 42 and the bottom of the ladle 40.

An electric heating element 49 a is provided in the upper nozzle 42 so as to go around the outer periphery of the nozzle hole 47.
Further, a similar electric heating element 49 b is provided in the fixing plate 43 so as to go around the outer periphery of the nozzle hole 47. The electric heating elements 49a and 49b include zirconia,
It is preferably made of molybdenum silicide (trade name: Kanthal).

When the liquidus temperature of the molten steel is set to _TL , it is preferable that _TL− 55 is set to such an extent that the electric heating elements 49 a and 49 b are energized and the metal does not grow in the nozzle hole 47.
By heating to a temperature of 0 ° C. or higher, nozzle clogging can be prevented.
7, the molten steel can be immediately injected. Therefore, it is not necessary to fill the nozzle hole 47 with a filler such as a granular refractory, and the contamination of the molten steel caused by mixing the nozzle filler into the molten steel can be prevented.

FIG. 12 is a sectional view showing another example of the injection mechanism for molten metal or the like in the present embodiment. Here, a gas blowing unit 50 is further provided in the configuration of FIG. The gas blowing section 50 has a fine diameter such that molten steel does not enter the molten metal contact surface of the sliding plate 44 at the nozzle closed position, and has a large number of holes for blowing gas preheated into the molten metal. ing.

By injecting a gas whose temperature has been raised in advance from the fine holes of the gas injection section 50, it is possible to suppress the start of growth of the metal on the contact surface of the molten steel, and to more effectively prevent nozzle clogging. Can be prevented.

The blowing gas may be any gas that does not adversely affect the molten steel, but is preferably a rare gas such as Ar. In addition, from the viewpoint of effectively suppressing metal growth, A
As a blowing condition such as r, the flow rate is 1.0 liter / mi.
n or more, and a heating temperature of 600 ° C. or more are preferable. The same effect can be obtained by providing such a gas blowing portion on the molten steel contact surface in the vicinity of the fixing plate 43 of the upper nozzle 42.

Next, a description will be given of equipment for performing continuous casting by injecting molten steel from the ladle 40 provided with the molten steel injecting mechanism 41 as described above.

In FIG. 13, a ladle 40 having the above-described molten steel injection mechanism 41 is disposed above a tundish 52,
An air seal pipe 51 is connected to a lower nozzle of the molten steel injection mechanism 41, and the air seal pipe 51 is immersed in molten steel in a tundish 52. Immersion nozzles 53 are attached at two places to the bottom of the tundish 52, and these immersion nozzles 53 are inserted into a mold 54. In this state, the nozzle hole of the molten steel injection mechanism 41 is opened, and the molten steel L is injected from the ladle 40 to the tundish 52 via the air seal pipe 51. Tundish 5
The molten steel L supplied to 2 is supplied from the immersion nozzle 53 to the mold 54 and is extracted as a steel slab 55. In this case, as described above, it is possible to open the nozzle hole of the molten steel injection mechanism 41 without the presence of a filler such as a granular refractory or the like. Does not occur.

In FIG. 14, the tundish is omitted, the ladle 40 is arranged above the mold 54, and an air seal pipe 51 is connected to the lower nozzle of the molten steel injection mechanism 41. Is inserted inside. In this state, the nozzle hole of the molten steel injection mechanism 41 is opened, and the molten steel L supplied to the mold 54 from the ladle 40 via the air seal pipe 51 is pulled out as a steel slab 55. As described above, the molten steel injection mechanism 41 does not require a granular filler, so that it is possible to directly inject molten steel from a ladle into a mold without providing a tundish for floating separation of inclusions. By using no filler, even when the molten steel is injected into the mold without providing a tundish, the cleanliness of the molten steel supplied to the mold can be made higher than before. Further, by omitting the tundish in this way, it is possible to expect a reduction in the cost of refractories and the like.

In this embodiment, the case where molten steel is used as the molten metal has been described. However, other metals can be similarly applied.

(Third Embodiment) In this embodiment, continuous casting is performed while supplying an inert gas which has been heated in advance when the molten steel flows out from a molten steel outflow nozzle provided at the bottom of the tundish.

FIG. 15 is a sectional view showing a molten steel outflow portion of a tundish applied to the embodiment of the present invention. A molten steel outflow portion 61 is provided at the bottom of the tundish 60. The molten steel outflow portion 61 is composed of an upper nozzle 62 that fits with the refractory material 69 of the tundish 60, a fixed plate 63, a sliding plate 64, and a rectifying nozzle 65, and is provided so as to be in contact with the lower surface of the upper nozzle. Sliding nozzle 66
And an immersion nozzle 67 provided to be in contact with the lower surface of the sliding nozzle 66.

The upper nozzle 62, the fixed plate 63, the sliding plate 64, the rectifying nozzle 65, and the immersion nozzle 67 make the sliding plate 64 contact the lower surface of the fixed plate 63 by a driving hydraulic cylinder (not shown). As a result, a molten steel outflow hole 70 from the tundish 60 to the mold 68 is formed.

The upper nozzle 62 is made of a porous brick.
One end of the gas pipe 71 is attached. Further, a gas heating device 72 is provided in the middle of the gas pipe 71, and a gas is heated by the gas heating device 72 from a gas supply source (not shown) provided at the other end, and the upper nozzle 62 is provided.
And the heated gas is supplied from the upper nozzle 62 to the molten steel flowing through the nozzle hole. As the blowing gas, any gas that does not affect the molten steel can be applied, but a rare gas such as Ar is preferable.

As shown in FIG. 16, an electric heater 82 is provided inside a tube 81, and the gas heating device 72 is supplied with electric power from a power source (not shown) via a lead wire 83. It has become. Then, the inert gas supplied from the gas inlet 85 of the tube 81 is heated by the electric heater 82 and discharged from the gas outlet 86.
The temperature of the inert gas at that time is controlled by a control unit (not shown) based on a signal of a thermocouple 84 provided near the gas outlet 86.

When casting molten steel from the tundish 60 into the mold 68 to perform continuous casting, first,
The sliding nozzle 66 is opened. Thus, the molten steel in the tundish 60 flows through the molten steel outflow hole (nozzle hole) 70 of the molten steel outflow portion 61. At this time, the inert gas heated by the gas heating device 72 is supplied to the upper nozzle 62 via the gas pipe 71. The inert gas supplied to the upper nozzle 62 passes through the pores of the upper nozzle 62 and is blown into molten steel flowing in the nozzle holes.

When the gas thus heated is used,
The volume expansion coefficient after being blown into the molten steel is smaller than at room temperature, the gas bubbles are miniaturized, and the number of gas bubbles increases. At this time, assuming that the radius of the gas bubble is R, the volume V of the gas bubble is expressed as V = 4/3 × π × R3. Therefore, when the gas bubble radius is １ ／, the number of bubbles is quadrupled.

[0091] By making the air bubbles finer, entrainment of the mold powder caused by the burst of the air bubbles floating in the mold is effectively prevented, and the number of gas air bubbles is increased. The number of alumina trapped in the gas bubbles also increases. Therefore, nozzle blockage can be effectively prevented without deteriorating the quality of the slab.

From this viewpoint, the higher the set temperature for heating the gas, the better,
According to experiments by the present inventors, it was confirmed that nozzle clogging can be effectively prevented at 800 ° C. or higher. Since the diameter of the gas bubble heated to 800 ° C. or more is about の of that at room temperature, the number of bubbles is about four times.

The gas heating device 72 is preferably installed at a position within about 1000 mm from the gas blowing section. This is a gas heating device and a gas blowing part (refractory)
Since it is extremely difficult to connect directly to the tundish due to the structure of the tundish, it must be connected by piping, but if the piping is long at this time, once the heated gas passes through the heating device, the temperature will drop and heating will occur. Tests have shown that such inconveniences are unlikely to occur because of reduced efficacy.
mm is a preferable range. Tests have also confirmed that heat loss can be minimized if it is within 1000 mm.

Although the present embodiment has been described with reference to the case of continuous casting of molten steel, other molten metals can be applied. Although gas is blown into the nozzle hole from the upper nozzle, another position may be used as long as gas can be blown into the nozzle hole. Further, the heating device is not limited to the structure shown in FIG. 16, and various devices can be adopted.

[0095]

Embodiments of the present invention will be described below. The first to seventh examples relate to the first embodiment. (First Example) A test was conducted on a tundish having a capacity of 40 t and two strands. In this tundish, when the superheat degree of the molten steel (molten steel temperature-molten steel solidification temperature) is 20 ° C. only by stirring by blowing argon gas, the pouring amount is 15 tons, and the longest pouring time is 90 seconds in pouring time. Was. For longer pouring times,
No molten steel flowed out. An upper nozzle incorporating an electric heater was incorporated into the tundish. Turn the upper nozzle of this tundish from 500 ° C to 1
After preheating to 200 ° C., 40 t of molten steel having a superheating degree of 20 ° C. was poured into the tundish over 240 seconds, and the slide nozzle was opened to confirm the outflow of the molten steel, and the slide nozzle was closed. Table 1 shows the results. In Table 1, ○ indicates that the molten steel flowed out, and X indicates that the molten steel did not flow out.

[0096]

[Table 1]

As shown in Table 1, the upper nozzle temperature was set to 800
When the temperature was not lower than ° C., the molten steel flowed out even when the pouring time was 240 seconds. From this result, by preheating the upper nozzle to 800 ° C. or higher, the conventional limit of the pouring time was 9
It was confirmed that 0 seconds could be extended to 240 seconds.

(Second Embodiment) An electric heater was incorporated in a sliding plate of a sliding nozzle of the same tundish as in the first embodiment. 400 ° C to 1000 ° C by the electric heater of this sliding plate
After preheating to ° C., the molten steel with a superheat degree of 20 ° C. of 40 t was poured into the tundish over 240 seconds, and the slide nozzle was opened to confirm the outflow of the molten steel, and the slide nozzle was closed. Table 2 shows the results. In Table 2, ○ and × indicate Table 1.
Is the same as

[0099]

[Table 2]

As shown in Table 2, when the sliding plate temperature was 500 ° C. or more, the pouring time was 24 hours.
Even at 0 seconds, molten steel flowed out. From this result, it was confirmed that by preheating the sliding plate to 500 ° C. or higher, the conventional limit of the pouring time of 90 seconds can be extended to 240 seconds.

(Third Embodiment) A heater for heating an argon gas was installed in the middle of an Ar gas pipe for stirring molten steel in the same tundish as in the first embodiment. Since the temperature of the argon gas drops in the piping, a heat insulating material was wound at a position about 150 mm from the argon gas blowing plug attached to the sliding plate of the piping as far as the heater could be attached. The temperature of this tundish is 300 ° C
The molten steel with a superheat degree of 20 ° C. of 40 t was poured in over 240 seconds while blowing argon gas heated to 1000 ° C. from above, the slide nozzle was opened, the outflow of the molten steel was confirmed, and the slide nozzle was closed. Table 3 shows the results. In addition,
○ and × in Table 3 are the same as in Table 1.

[0102]

[Table 3]

As shown in Table 3, the argon gas temperature was 6
When the temperature was set to 00 ° C. or more, molten steel flowed out even when the pouring time was 240 seconds. From this result, the argon gas temperature was set to 600
It was confirmed that the temperature of 90 ° C. or more can be extended to 240 seconds from 90 seconds which was the conventional limit of the pouring time.

(Fourth Embodiment) In the first strand of the same tundish as in the first embodiment, an electric heater is incorporated only in the upper nozzle, and in the second strand, an electric heater is installed in the sliding plate of the upper nozzle and the sliding nozzle. Was incorporated. The upper nozzle of both strands was heated to 800 ° C. at the electric heater temperature, and the slide nozzle of the second strand was heated to 500 ° C. at the electric heater temperature, and then the tundish was heated for 40 t
Pour molten steel with superheat degree of 20 ° C over 240 seconds,
The slide nozzle was opened and the outflow of molten steel was confirmed. Table 4 shows the results. In addition, ○ and × in Table 4 are the same as in Table 1.

[0105]

[Table 4]

As shown in Table 4, 90 seconds, which was the limit of the conventional pouring time, could be extended to 240 seconds only by heating the upper nozzle, but it was increased to 300 seconds by combining the heating of the sliding nozzle. It was confirmed that the time could be further extended.

(Fifth Embodiment) In the first strand of the same tundish as in the first embodiment, an electric heater is incorporated only in the sliding plate of the sliding nozzle, and in the second strand, an electric heater is incorporated in the sliding plate. An argon gas heating heater was attached in the middle of the molten steel stirring argon gas pipe. With respect to the attached heater for heating an argon gas, the same curing as in Example 3 was performed. Sliding slip of both strands is 500 at electric heater temperature
C., and while blowing argon gas heated to 600.degree. C. for the second strand, 40 t of molten steel with a superheat degree of 20.degree. C. was poured into the tundish over 240 seconds, and the slide nozzle was opened to melt the molten steel. After confirming the outflow, the slide nozzle was closed. Thereafter, the slide nozzle was opened and closed every 30 seconds to check outflow of molten steel. Table 5 shows the results. In addition, ○ and × in Table 5 are the same as those in Table 1.

[0108]

[Table 5]

As shown in Table 5, 90 seconds, which was the limit of the conventional pouring time, was reduced to 24 seconds only by heating the slide nozzle.
Although it could be extended to 0 seconds, it was confirmed that the pouring time could be further extended to 330 seconds by combining the sliding nozzle heating and the argon gas heating.

(Sixth Embodiment) Only the heater for argon gas heating is arranged in the middle of the argon gas pipe for stirring the molten steel in the first strand of the same tundish as in the first embodiment, and the molten steel is stirred in the second strand. A heater for heating the argon gas was attached in the middle of the argon gas pipe for use, and an electric heater was incorporated in the upper nozzle. Example 3 for the attached heater for heating argon gas
The same curing was applied. The upper nozzle of the second strand is heated to an electric heater temperature of 800 ° C., and 40 tons of molten steel having a superheat degree of 20 ° C. is poured into the tundish over 240 seconds while blowing argon gas heated to 600 ° C. for both strands. The slide nozzle was opened, the outflow of molten steel was confirmed, and the slide nozzle was closed. Since then
The slide nozzle was opened and closed every 30 seconds, and the outflow of molten steel was confirmed. Table 6 shows the results. In Table 6, the circles and crosses are also shown in Table 1.
Is the same as

[0111]

[Table 6]

As shown in Table 6, 90 seconds, which was the limit of the conventional pouring time, could be extended to 300 seconds by only argon gas heating, but it was reduced to 330 seconds by combining the upper nozzle heating and argon gas heating. It was confirmed that the pouring time could be further extended.

(Seventh Embodiment) In the first strand of the same tundish as in the first embodiment, an electric heater is incorporated in the upper nozzle, and an argon gas heating heater is installed in the middle of the argon gas pipe for stirring molten steel. ,
In the second strand, an electric heater was incorporated in the upper nozzle and the sliding plate, and a heater for heating an argon gas was attached in the middle of an argon gas pipe for stirring molten steel. With respect to the attached heater for heating an argon gas, the same curing as in Example 3 was performed. The upper nozzle of both strands was heated to 800 ° C. at the electric heater temperature, and the sliding nozzle of the second strand was heated to 500 ° C. at the electric heater temperature, and both strands were blown with argon gas heated to 600 ° C. 40 tons of molten steel superheat 20 in the tundish
The molten steel at a temperature of ° C. was poured over 240 seconds, the slide nozzle was opened, and the outflow of the molten steel was confirmed, and the slide nozzle was closed. Thereafter, the slide nozzle was opened and closed every 30 seconds to check outflow of molten steel. Table 7 shows the results. In addition, ○ and × in Table 7 are the same as those in Table 1.

[0114]

[Table 7]

As shown in Table 7, the simultaneous use of the upper nozzle heating and the argon gas heating could extend the conventional limit of the pouring time of 90 seconds to 330 seconds. It was possible to further extend the pouring time to 390 seconds by combining with argon gas heating.

The following eighth to tenth embodiments relate to the second embodiment. (Eighth Embodiment) Injection of molten steel was performed using the molten metal injection mechanism shown in FIG. As the heating elements 49a and 49b, molybdenum silicide (trade name: Kanthal) was used, and as a power supply for nozzle heating, a ladle-mounted small power supply was used. In this example, the surface temperature of the molten steel contact surface of the upper nozzle 42 immediately before receiving the steel was 1000 ° C. No filler such as granular refractory (stuffed sand) was filled in the nozzle hole 47 at all.

After holding the steel for 30 minutes until the opening, the sliding plate 44 of the sliding member 45 of the rotary nozzle was moved from the closed state to the open state. The nozzle of the ladle was opened without any problems, and pouring of the tundish prepared in advance was started.

Ninth Embodiment The molten steel was injected using the molten metal injection mechanism shown in FIG. Here, Ar gas, which had been heated before 5 minutes before the opening, was flown from the gas blowing section 50 received at the closed position on the upper surface of the sliding plate 44 of the sliding member 45. The temperature of the Ar gas is 600 ° C. and the flow rate is 1.0
1 / min. The other device configurations were the same as in the eighth embodiment. In this example, the surface temperature of the molten steel contact surface of the upper nozzle 42 immediately before receiving the steel was 1200 ° C.
No filler such as granular refractory (stuffing sand) was filled in the nozzle hole 47 at all.

[0119] After 30 minutes from the steel receiving to the opening, the sliding plate 44 of the sliding member 45 of the rotary nozzle was moved from the closed state to the open state. The nozzle of the ladle was opened without any problems, and pouring of the tundish prepared in advance was started.

(Tenth Embodiment) The molten steel was injected under the conditions described in the eighth and ninth embodiments, and FIG.
Continuous casting was performed using the equipment shown in FIG. The size of the steel slab 55 was 250 mm thick x 2100 mm width, and the casting was performed at a casting speed of 0.8 m / min. In the nozzle hole 47 of the ladle 40, granular refractory (stuffing sand)
No filler material was used, but the nozzle hole 47 was opened without any problem, and the total tapping amount of the ladle 40 of 260 T was completely cast. The cleanliness of the bottom slab was good in each case, and FIG.
Even when a tundish was not used as in the above, the same or higher cleanliness was obtained as when the opening was made with a filler using a tundish.

The following eleventh example relates to the third embodiment. (Eleventh Embodiment) Here, molten steel was continuously cast using a two-strand tundish having a structure as shown in FIG. Capacity 4 as tundish
A ladle having a capacity of 250 tons / heat was used as a ladle. Mold width is 9 for both strands
The width was 50 mm, and the width was not changed during casting. The thickness of the slab was 250 mm, and the steel type was low carbon aluminum killed steel. In addition, replacement of the immersion nozzle during casting was not performed.

The Ar gas was supplied to the molten steel flowing through the nozzle hole through the upper nozzle 62, and the flow rate was set before the gas heating device 72.
It was changed to 2 Nl / min. Further, the set temperature of the gas is set to 500 ° C., 600 ° C.,
It was changed at three levels of 0 ° C. After the completion of casting in each case, the immersion nozzle was removed, the alumina adhesion rate in the nozzle was measured, and the presence or absence of nozzle blockage was confirmed. For comparison, a normal temperature Ar gas was blown into the molten steel flowing through the nozzle hole via the upper nozzle without using a gas heating device.
Table 8 shows the results.

[0123]

[Table 8]

In the embodiment No. 1 to No. In No. 3, the case where the gas temperature is varied while the gas flow rate during casting is constant is compared. In all of these, no nozzle blockage occurred, but No. 2 heated to 500 and 600 ° C. 1 and No. No. 2 was heated to 800 ° C., while the alumina deposition amount of No. 2 was 27% and 14%. In No. 3, the amount of alumina attached was 0 despite the same casting time, and it was confirmed that aluminum hardly adhered. Therefore, it was confirmed that the heating temperature of the blowing gas is preferably 800 ° C. or higher.

In the embodiment No. In Nos. 4 to 7, the gas temperature was set to 800 ° C., and the gas flow rate was reduced as compared with the case where the gas was at room temperature (Comparative Examples Nos. 8 to 11). N
o. It was confirmed that the adhesion of alumina during the same casting time was significantly reduced in all of the samples Nos. 4 to 7 as compared with the case where the room temperature gas was supplied. Also, if the casting time was within 250 minutes, there was no alumina adhesion. No. 3 with an extended casting time. 6 and no. In No. 7, although slight alumina adhesion was observed, it was confirmed that the nozzle was not closed. On the other hand, in the comparative example, the adhesion of alumina became thicker in proportion to the casting time, and when the casting time exceeded 200 minutes, nozzle clogging occurred even if the Ar gas flow rate was increased.

[0126]

As described above, according to the present invention,
Nozzle clogging due to the temperature drop of molten steel remaining between the nozzle hole and the sliding nozzle due to heating of the upper nozzle, etc. is suppressed, and in continuous steel casting, the pouring time at the start of casting is extended. It is possible to do. This reduces the amount of defective slab at the tip of the slab,
An extremely large effect can be obtained.

In addition, in the molten metal injection mechanism installed at the lower part of the molten metal holding container such as a ladle, a heating means for heating at least one of the sliding plate and the above-mentioned nozzle is provided, so that the nozzle filler is used. Thus, the opening of the nozzle of the molten metal holding container can be reliably performed, and contamination of the molten metal caused by mixing of the nozzle filler into the molten metal can be prevented.

Further, since a preheated gas is blown into the molten metal flowing out of the nozzle hole of the molten metal outflow nozzle from an arbitrary position of the molten metal outflow nozzle, the quality of the cast slab is deteriorated in the tundish having the molten metal outflow hole at the bottom. Without this, nozzle blockage can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a continuous casting facility to which a first embodiment of the present invention is applied.

FIG. 2 is a diagram showing a structure around a sliding nozzle in a continuous casting facility for performing the first method according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a structure around a sliding nozzle in a continuous casting facility for performing a second method according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a structure around a sliding nozzle in a continuous casting facility for performing a third method according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a structure around a sliding nozzle in a continuous casting facility for performing a fourth method according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a structure around a sliding nozzle in a continuous casting facility for performing a fifth method according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a structure around a sliding nozzle in a continuous casting facility for performing a sixth method according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a structure around a sliding nozzle in a continuous casting facility for carrying out a seventh method of the first embodiment of the present invention.

FIG. 9 is a view showing an apparatus according to another structure for performing the second method according to the first embodiment of the present invention.

FIG. 10 is a diagram showing a state in which the sliding plate is slid halfway in the apparatus of FIG. 9;

FIG. 11 is a sectional view showing an example of a molten metal injection mechanism according to a second embodiment of the present invention.

FIG. 12 is a sectional view showing another example of the molten metal injection mechanism according to the second embodiment of the present invention.

FIG. 13 is a diagram showing equipment for performing continuous casting by injecting molten steel into a mold via a tundish from a ladle provided with the molten steel injecting mechanism of FIG. 11 or 12;

FIG. 14 is a diagram showing equipment for performing continuous casting by directly injecting into a mold without using a tundish from a ladle provided with the molten steel injecting mechanism of FIG. 11 or FIG.

FIG. 15 is a sectional view showing a molten steel outflow portion of a tundish applied to the implementation of the third embodiment of the present invention.

FIG. 16 is a schematic diagram showing the structure of a gas heating device used in the device of FIG.

[Explanation of symbols]

1; tundish 2; molten steel 3; molten steel outlet 4; upper nozzle 5; sliding nozzle 5a; fixed plate 5b; sliding plate 6; immersion nozzle 7; mold (mold) 21; electric heater 26 incorporated in the upper nozzle; Electric heater 29 incorporated in the sliding plate; Electric heater provided in the argon gas pipe 40; Ladle 41; Molten steel injection mechanism 42; Upper nozzle 43; Fixing plate 44; Sliding plate 46; Lower nozzle 49a, 49b; Electric heating element 50; Gas blowing section 51; Air seal pipe 52; Tundish 53; Immersion nozzle 54; Mold 55; Steel slab 60; Tundish 61; Molten steel outlet 62; Upper nozzle 66; Sliding nozzle 67; 68; mold 70; molten steel outflow hole (nozzle hole) 71; gas piping 72; gas heating device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B22D 41/36 B22D 41/36 41/42 41/42 41/50 540 41/50 540 41/60 41 / 60 (72) Inventor Kyoji Watanabe 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Taichi Kuranaga 1-2-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. 72) Inventor Yasunori Muraki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Kiyofumi Shibuya 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Takashi Osako 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hiroshi Maeda 1-2-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Seigo Kuwano 2-2-1 Otemachi, Chiyoda-ku, Tokyo Shinagawa Kawabashi Brick Co., Ltd. (72) Inventor Masahiro Moriwaki 2-2-1 Otemachi, Chiyoda-ku, Tokyo Shinagawa White Brick Inside (72) Inventor Morin Yoshikawa 2-2-1 Otemachi, Chiyoda-ku, Tokyo Shinagawa White Brick Co., Ltd.

Claims (18)

[Claims] 1. A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle, and a dipping nozzle to perform continuous casting, A heater is provided inside the upper nozzle, the upper nozzle is heated to 800 ° C. or higher by the heater, molten steel is poured into the tundish with the sliding nozzle closed, and then the sliding nozzle is opened to perform casting. A continuous casting method characterized by starting. 2. A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom thereof through an upper nozzle, a sliding nozzle, and a dipping nozzle to continuously perform casting, A heater is provided inside the sliding nozzle, the surface temperature of the tundish side is heated to 500 ° C. or more in a state where the sliding nozzle is closed, molten steel is poured into the tundish, and then the sliding nozzle is opened to perform casting. A continuous casting method characterized by starting. 3. A continuous casting method in which molten steel in a tundish is supplied from a molten steel outlet provided at a bottom thereof to a mold via an upper nozzle, a sliding nozzle and a dipping nozzle to continuously perform casting, While the sliding nozzle is closed, a gas heated to 600 ° C. or higher is supplied to the molten steel through the sliding nozzle to agitate the molten steel, and the molten steel is poured into the tundish, and then the sliding nozzle is opened to perform casting. Starting a continuous casting method. 4. A continuous casting method in which molten steel in a tundish is supplied from a molten steel outlet provided at a bottom thereof to a mold via an upper nozzle, a sliding nozzle, and a dipping nozzle to continuously perform casting, A heater is provided inside the upper nozzle and the inside of the sliding nozzle, and the upper nozzle is heated to 800 ° C. or higher by the heater in a state where the sliding nozzle is closed, and the open / close nozzle is heated to 500 ° C. or higher. A continuous casting method characterized by pouring molten steel and then opening a sliding nozzle to start casting. 5. A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle, and an immersion nozzle to perform continuous casting, A heater is provided inside the sliding nozzle, and while the sliding nozzle is closed, the surface temperature on the tundish side is heated to 500 ° C. or more, and a gas heated to 600 ° C. or more is supplied to the molten steel through the sliding nozzle. A continuous casting method, wherein molten steel is poured into the tundish while stirring the molten steel, and then a sliding nozzle is opened to start casting. 6. A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom portion thereof through an upper nozzle, a sliding nozzle and an immersion nozzle to continuously perform casting, Heaters are provided inside the upper nozzle and inside the sliding nozzle, and the upper nozzle is heated to 800 ° C. or more by a heater in a state where the sliding nozzle is closed, and 60 ° C. is passed through the sliding nozzle.
A continuous casting method, wherein a molten steel is poured into the tundish while a gas heated to 0 ° C. or more is supplied to the molten steel and the molten steel is stirred, and then a sliding nozzle is opened to start casting. 7. A continuous casting method in which molten steel in a tundish is supplied to a mold from a molten steel outlet provided at a bottom thereof through an upper nozzle, a sliding nozzle, and an immersion nozzle to continuously perform casting, A heater is provided inside the upper nozzle and inside the sliding nozzle, and the upper nozzle is heated to 800 ° C. or higher by the heater in a state where the sliding nozzle is closed, the sliding nozzle is heated to 500 ° C. or higher, and the sliding nozzle is heated. A continuous casting method comprising: pouring molten steel into the tundish while stirring the molten steel by supplying a gas heated to 600 ° C. or higher to the molten steel, and then opening a sliding nozzle to start casting. 8. A molten metal injection mechanism installed at a lower portion of the molten metal holding container for injecting the molten metal stored in the molten metal holding container, comprising: an upper nozzle provided at a molten metal outlet of the molten metal holding container; A fixing plate having a nozzle hole fixed to a lower portion of the upper nozzle,
A sliding member having a sliding plate that slides on the fixed plate and opens and closes the molten metal outlet; a lower nozzle fixed to the sliding plate and moving with the sliding plate; And a heating means for heating at least one of the nozzles. 9. The molten metal injection mechanism according to claim 8, wherein the heating means has an electric heating element provided around the outer periphery of the nozzle hole in the upper nozzle. 10. The molten metal injection mechanism according to claim 8, wherein the heating means has an electric heating element provided on the fixing plate so as to go around the outer periphery of the nozzle hole. . 11. A small diameter such that molten steel does not penetrate at least one of the molten metal contact surfaces of the sliding plate at the nozzle closing position or at a position near the fixed plate of the upper nozzle, and the temperature of the molten metal is increased in advance. The molten metal injection mechanism according to any one of claims 8 to 10, wherein a large number of holes are formed for blowing the gas. 12. The method according to claim 8, wherein:
A molten metal injection method for injecting molten metal from a molten metal holding container using the molten metal injection mechanism according to the item, wherein the molten metal is used as the molten metal, and the temperature of the molten steel contact surface of the upper nozzle and the fixed plate is set to molten metal injection method characterized by heating the liquidus temperature when the T _L, the T _L -550 ° C. or higher. 13. A molten metal injection method for injecting molten metal from a molten metal holding container using the molten metal injection mechanism according to claim 11, wherein molten steel is used as the molten metal, and the temperature of an inert gas blown into the molten steel is set at 600 ° C. A molten metal injection method characterized by the above. 14. The method according to claim 8, wherein
A molten metal pouring method, comprising: providing the molten metal pouring mechanism according to the above paragraph in a ladle as a molten metal holding container, and pouring the molten metal directly from the ladle into a mold for continuous casting. 15. The method according to claim 12, wherein the molten metal holding container is a ladle, and molten steel is directly injected from the ladle into a continuous casting mold. . 16. A continuous casting method in which a molten metal in a tundish is supplied to a mold from a molten metal outlet through a molten metal outlet through a molten metal outlet, and casting is continuously performed. A continuous casting method characterized by blowing a preheated gas into a molten metal flowing out of a nozzle hole of the nozzle from an arbitrary position. 17. The continuous casting method according to claim 16, wherein the heating temperature of the gas is 800 ° C. or higher. 18. The continuous casting method according to claim 16, wherein a distance between a heating device for heating the gas and a gas blowing unit is set to be within 1000 mm.