JP2639884B2 - Prevention method of leakage of molten metal in continuous strip casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing molten metal from leaking from a gap between a nozzle and a roll during the production of a metal strip by continuous casting.

[0002]

2. Description of the Related Art In an apparatus of a twin-roll type having a different diameter as shown in FIG. 4 for manufacturing a metal ribbon by using a rotating roll surface as a mold, it is necessary to prevent a molten metal 4 from leaking from a gap 3 between a nozzle 2 and a roll 1. As a method for preventing this, a method has been proposed in which an inorganic sealing material 7 having elasticity, such as ceramic paper or a ceramic blanket, is sandwiched between a roll and a nozzle (for example, JP-A-63-101053). However, in the above method, an inorganic material such as a ceramic paper or a ceramic blanket and a metal element constituting the molten metal or a compound thereof (such as an oxide) reacts and the inorganic material is dissolved. The eroded inorganic material is not only a serious disadvantage because it is involved in the formed strip, but also in order to perform stable casting, the amount of the eroded inorganic material must always be continuously supplied by the amount of the eroded inorganic material. Problem arises.

When an inorganic sealing material is used as a material for preventing molten metal from leaking out, it is necessary to select a material in accordance with the alloy to be cast. Not only is it necessary, but there is not always the right material. On the other hand, when the material for preventing the molten metal from leaking is not used, the gap between the nozzle and the roll may be maintained at zero or a small gap within the range of the surface tension of the molten metal in order to prevent the molten metal from leaking. . However, when the gap between the nozzle and the roll is reduced to zero, the nozzle and the rotating roll come into direct contact, so that the nozzle is damaged or the roll is damaged. In addition, in the case where the gap is held in a small gap within the range of the surface tension of the molten metal, the gap expands out of the range of the surface tension due to a difference in thermal expansion between the nozzle and the roll during casting, and leakage of the molten metal occurs. There is a risk that it will. Therefore, it is necessary to support the molten metal by an external force so that the molten metal does not leak even if the gap is widened outside the range of the surface tension. As a method therefor, a method of supporting a molten metal by using an electromagnetic force is disclosed in Japanese Patent Application Laid-Open No. H1-11-1.
No. 70552, however, has the disadvantage that the device is not only expensive but also influenced by the material of the roll.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gap between the roll and the nozzle without using a sealing material to a certain extent, and the gap extends to a range outside the surface tension of the molten metal. Another object of the present invention is to provide a method for preventing the molten metal from leaking from the gap between the roll and the nozzle by using gas pressure as an inexpensive method for applying an external force so that the molten metal does not leak.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing a thin metal strip by continuous casting using a rotating roll surface as a mold so that molten metal does not leak from a gap between a nozzle and a roll. In the method of preventing molten metal from leaking by applying pressure with gas, use a gas in which nitrogen and / or a mixture of two or more of helium, neon, and argon are used in an arbitrary ratio. The pressure gas, which is sealed with a gas leak prevention material and is balanced with the pressure at which molten metal leaks through many small-diameter holes provided directly below the nozzle through the large-diameter hole, is uniformly fed into the gap between the nozzle and the roll. This is a method for preventing molten metal from leaking.

FIGS. 1 and 2 are diagrams illustrating the case where the present invention is applied to the twin-roll method and the single-roll method, respectively, but the present invention is not limited to these two methods. In the figure, a nozzle 2 is installed at an angle to a roll 1 so that a constant gap 3 can always be maintained between the nozzle and the roll. The periphery of the nozzle is filled with a certain amount of gas, and in order to prevent the gas from leaking to the surroundings, the nozzle is surrounded by a material 6 that is impervious or impervious to gas. Cloth made of strong inorganic fibers. Preferable examples of the gas leak preventing material 6 include a material obtained by shaving a refractory brick according to a roll R, and a material obtained by wrapping a ceramic blanket with a metal foil such as a stainless steel foil. A number of small-diameter holes 8 for introducing gas into the gap between the nozzle and the roll are formed in the brick 5 immediately below the nozzle, and a large-diameter hole 9 is formed on the opposite side of the hole to the roll side. Are formed at right angles to the hole, so that the gas flows uniformly from the small-diameter hole. One end of the large-diameter hole is a blind, and the other end is connected to a gas cylinder or a compressor via a gas pressure regulator (not shown) by a hose or the like (FIG. 3). Any gas can be used as long as the pressure can be maintained, but those which violently react with the molten metal or those harmful to the human body are not preferred. Therefore, nitrogen or helium, neo
And argon are preferred. When the molten metal 4 is poured into the tundish, the molten metal enters the nozzle 2 and comes into contact with the roll 1. At that time, the molten metal tends to enter the gap between the nozzle and the roll. However, this gap 3 is sealed with the molten metal and the gas leak preventing material 6 around the nozzle,
Further, since gas is fed from the small-diameter hole through the large-diameter hole at a predetermined pressure, pressure is applied to this gap. This pressure is the static pressure of the molten metal, the viscous force of the roll,
The leakage of the molten metal can be prevented by balancing the surface tension and the like of the molten metal with the total pressure (the pressure at which the molten metal tends to leak).

[0007]

EXAMPLE A metal ribbon was manufactured using the twin-roll apparatus of different diameters shown in FIG. 1 and changing the conditions within the experimental conditions shown in Table 1. The results are shown in Tables 2, 3 and 5 and 6.

[0008] As shown in FIGS. 5 and 6, the gas pressure has an appropriate range. If the gas pressure is too high, the molten metal is scattered, that is, a so-called bubbling phenomenon occurs. Plugged in or leaked.
The appropriate range varies depending on the gap amount between the nozzle and the roll, but hardly changed even when the casting speed was changed.
At a gap of 0.5 mm, even when the gas pressure was set to 0, no hot water was found. In addition, the strips obtained under the proper conditions have the disadvantages (entanglement) caused by the sealing material that has been recognized in the past.
Did not occur at all. Although in the illustrated embodiment mentioned those using N ₂ gas as a gas, Ar, neon some have <br/> even in a mixed gas thereof, the same result is obtained.

[0009]

[Table 2]

[0010]

[Table 3]

[0011]

According to the present invention, since no molten metal leakage prevention material is used,
Not only does the material of the leakage preventing material need not be selected, but also stable casting can be performed for a long time, and there is no defect caused by the leakage preventing material of the molten metal.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment applied to a different diameter twin roll method.

FIG. 2 is an explanatory view of an embodiment applied to a single roll method.

FIG. 3 is an explanatory view showing a gas inflow state of a nozzle portion.

FIG. 4 is an explanatory view of a conventional twin-roll device with a different diameter using a sealing material.

FIG. 5 is an explanatory diagram showing experimental results of the example.

FIG. 6 is an explanatory diagram showing experimental results of the example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roll 2 Nozzle 3 Gap 4 Molten metal 5 Brick 6 Gas leak prevention material 7 Sealing material 8 Gas introduction hole (small diameter) 9 Gas introduction hole (large diameter)

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-101053 (JP, A) JP-A-62-77152 (JP, A) JP-A-58-154442 (JP, A) JP-A-59-154 125244 (JP, A)

Claims (1)

(57) [Claims] When a metal strip is manufactured by continuous casting using the surface of a rotating roll as a mold, a pressure is applied to the gap by a gas to prevent the molten metal from leaking from a gap between the nozzle and the roll. In the leak prevention method, as the type of gas, use a gas in which one or two or more of nitrogen, helium, neon, and argon are mixed in an arbitrary ratio, and the gap is sealed with a molten metal and a gas leak prevention material around the nozzle. A pressure gas that balances the pressure at which the molten metal tends to leak through a large number of small-diameter holes provided directly under the nozzle through a large-diameter hole, and uniformly sends a pressure gas into the gap between the nozzle and the roll. Prevention law.