JPH08257699A - Apparatus for casting metallic strip - Google Patents

Abstract

PURPOSE: To prevent the rotation together with the air and to produce a rapid cooled strip excellent in the surface characteristic in a rapid cooling method with a roll. CONSTITUTION: A shield plate 16 is arranged through a fine interval between the roll and this plate at the upstream side of the nozzle 1 onto the rapid cooling roll 4 and a combustion device 13 is arranged between the shield plate 16 and paddle. Oxidizing high temp. gas produced in this combustion device 13, e.g. CO2 +O2 , is blasted to form high concn. and high temp. atmosphere. By this method, the development of clogging of the nozzle is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal strip casting apparatus, and more particularly to a method for producing an amorphous ribbon by a roll quenching method, in which a molten metal film is sealed with a specific type of high temperature gas. The present invention relates to an apparatus capable of heating and keeping the molten metal film forming nozzle heated or heated as required.

[0002]

2. Description of the Related Art In an apparatus for continuously producing an amorphous ribbon by continuously supplying a molten metal in a film form from a nozzle onto a cylindrical rotating body which is cooled by an internal liquid and rotates at a high speed. For the purpose of improving the surface properties of the strip, at least reducing gas is supplied to a molten steel pool (hereinafter referred to as a paddle) formed between the hot water supply nozzle and the cooling roll to create a low density reducing gas atmosphere by an exothermic reduction reaction. Techniques for forming are known. For example, there are JP-A-60-37249 and JP-A-1-501924.

In these techniques, a roll is rotated at a substantially constant speed, and when the molten steel is rapidly solidified on the roll, a reducing gas such as carbon monoxide is added to the oxygen-deficient region generated in the upstream portion of the paddle. By supplying, that is, by performing reducing combustion with atmospheric oxygen and supplying a low-density reducing gas, a ribbon having a good surface property is manufactured, and all reducing gases are used.

[0004]

SUMMARY OF THE INVENTION In the prior art,
Supplying the reducing low density gas upstream of the paddle to form this gas atmosphere and / or reducing combustion atmosphere is not sufficiently effective for the following reasons. When a quenched amorphous metal ribbon is produced using a cooling roll, the cooling roll diameter is usually about 350 to 1000 mm and the peripheral speed is 10 to 40 m.
/ S. Under these conditions, the molten metal cooling rate for obtaining the amorphous ribbon is 100,000 to 1,000,000 ° C.
Since / s is required, it is generally selected from the roll temperature and the cooling capacity. A roll rotating at such a speed inevitably has a gas that is entrained around the roll surface. If manufacturing is carried out in the atmosphere, gas of atmospheric components and temperature will be accompanied. It is known that the thickness of the accompanying gas is determined by the turbulent boundary layer, and when the roll rotates at a peripheral speed of 10 m / s, the thickness of several hundreds of μm is obtained by moving a distance of about 200 mm. Therefore, as the flow rate of the gas supplied to the paddle part, for example, a gas thickness of 1000 μm,
When the peripheral speed is 10 m / s, the flow rate per unit width of the roll is 0.001 × 10 × 60 = 0.06 m ³ / min = 600 liters / min / m 2.

In order to dilute the accompanying atmospheric gas of this flow rate with the reducing gas to form an atmosphere in which the reducing gas is at least 38%, the input reducing gas flow rate is a flow rate x liter / liter in the case of the reducing gas alone. min becomes 0 = 600 + 100 × x = 38 × (600 + x), and x = 368 liter / min / m, and the paddle is supplied with a total of 968 liter / min / m of gas. In this technique, a gas which has been adjusted to 38 to 70% reducing gas in advance is used. Therefore, for example, 70% reducing gas 713 liters / min / min is used to set the paddle atmosphere to 38% reducing gas concentration by using 70% reducing gas. m
Thus, 1313 liter / min / m of gas is supplied to the paddle section.

On the other hand, the air component is 814 liters / min.
/ M or more, the oxygen content in the mixed gas is 163 liter / min / m. That is, it is difficult to form a reducing atmosphere with the conventional technique. On the other hand, the inventors
The atmosphere components and the surface defects of the ribbon were investigated. Roll diameter 400mm, width 2 in a container that can completely replace the atmosphere
A general ribbon production apparatus having an internal forced cooling roll of 0 mm was installed and a ribbon production experiment was conducted.

The atmosphere used in the experiment is carbon monoxide, carbon dioxide, hydrogen, water vapor, oxygen, nitrogen, helium, argon, krypton, xenon or a hydrocarbon gas alone or in a mixed gas. However, when mixed with oxygen, the concentration of flammable gas or the concentration of oxygen was adjusted so as to be out of the combustible range. Further, for oxygen concentration of 50% or more, the experiment was not conducted for safety. The ambient temperature was adjusted by an electric heater, and an experiment was conducted between room temperature and 1300K.

As a result of the above-mentioned experiment, (a) a mixed gas of carbon dioxide and oxygen, (b) a mixed gas of water vapor and oxygen, and (c) 65 as the atmosphere in which the ribbon surface can be produced most favorably.
It has been found that an oxidizing gas atmosphere component composed of carbon dioxide or oxygen in an amount of at least%, or (d) a mixed component obtained by mixing two or more of (a), (b), and (c) above is suitable.

Further, nitrogen gas has been found as a gas component which deteriorates the surface properties. The surface quality of the ribbon produced in the mixed atmosphere of carbon dioxide and oxygen at room temperature was better than that in the case where the ambient temperature was high, such as a nitrogen gas atmosphere of 800 K. Furthermore, when the temperature was 500 K or higher in the mixed atmosphere of carbon dioxide and oxygen, the surface texture at room temperature was further improved.

From the above, the effect when the temperature is raised to a low density atmosphere varies, and is not always sufficient.
It was found that the effect due to the difference in the components of the atmosphere was larger than that. That is, the oxidizing atmosphere is superior between the inert atmosphere and the oxidizing atmosphere. From the above viewpoint, the combustion exhaust gas used in the prior art after ignition and combustion has a carbon dioxide component concentration of 28%, a carbon monoxide component concentration of 15%, and oxygen of 0%.
Therefore, the effect as an oxidizing gas cannot be expected.

Further, in the prior art, since the manufacturing is carried out in the air atmosphere, since the reducing gas is supplied to the place where the ambient gas components are accompanied by the reducing gas, it is impossible to increase the concentration of the reducing gas. . Even if the simple reducing gas is supplied and burned, the maximum carbon dioxide component concentration is 28%, and the effect as the oxidizing gas cannot be expected. An object of the present invention is to provide a new technique developed for improving the ribbon surface texture.

[0012]

The present invention was developed in order to dramatically improve the surface properties of thin ribbons as compared with the effects of the prior art. The molten metal is formed on the outer periphery of a high-speed rotating roll that is internally cooled. In a device for continuously producing an amorphous ribbon by supplying the powder from a nozzle, a shielding plate is installed on the upstream side of rotation from the nozzle with a minute gap between the roll and the roll, and the space between the shielding plate and the paddle is set. A casting device for metal strips, characterized in that a supply device for supplying a mixed gas of carbon dioxide and / or water vapor and an oxygen-containing gas is provided.

As the mixed gas, carbon monoxide, hydrogen,
It is preferable to use combustion exhaust gas obtained by burning one or more combustible gases selected from the group of hydrocarbon gases with a combustion-supporting gas composed of carbon dioxide and / or steam and an oxygen-containing gas. . Such combustion exhaust gas is obtained by the combustion reaction represented by the following equation. That is, CO + (CO ₂ + O ₂ ) → CO ₂ + O ₂ H ₂ + (H ₂ O + O ₂ ) → H ₂ O + O ₂ C _m H _n + (CO ₂ + O ₂ ) → CO ₂ + H ₂ O + O ₂ C _m H _n + (H ₂ O + O ₂ ) → CO ₂ + H ₂ O + O ₂ C _m H _n + (CO ₂ + H ₂ O + O ₂ ) → CO ₂ + H ₂ O
CO ₂ + O ₂ , H ₂ O + O ₂ or CO ₂ + H ₂ due to the reaction of + O ₂ or two or more of these reactions occurring simultaneously.
O + O ₂ oxidizing gas can be produced and supplied.

Further, the supply device includes a gas combustion device, and the gas combustion device supplies a fuel gas supply pipe for supplying one or more gases selected from the group of carbon monoxide, hydrogen and hydrocarbon gas, It is preferable that a combustion-supporting gas supply pipe for supplying carbon dioxide and / or water vapor and oxygen-containing gas is additionally provided.

[0015]

In the present invention, the shielding plate separates and blocks the accompanying air on the roll, and the gas supply portion is installed on the downstream side of the shielding plate, so that almost all of the accompanying air is cut off. Therefore, the supply gas component is supplied to the paddle portion without being diluted with air. Further, if the entrained air is simply shut off, a depressurized area is generated on the wake side of the shield plate, so that the atmosphere flows in from the surroundings, and as a result, the situation is the same as when the shutoff is not performed. According to the present invention, the shielding plate is used to separate and block the air that is entrained around the rolls, and the gas supply portion is installed on the downstream side thereof, so that the inflow of air from the surroundings can be completely prevented.

Further, in order to obtain the component gas discovered by the inventors at a high temperature, a combustion device was attached. For example, in order to obtain a high-concentration carbon dioxide atmosphere at high temperature, a combustible substance that produces carbon dioxide gas by a combustion reaction may be burned with oxygen. Carbon monoxide is a flammable gas as a raw material. At this time, if air is used as the combustion-supporting gas, it is impossible to prevent nitrogen from being mixed into the high-temperature gas. Also,
If high-purity oxygen is used as a combustion-supporting gas, the combustion gas temperature will be as high as 2000 K or more, and the problem of heat resistance of the combustion device and the supply device will be almost unsolvable.

The inventors have found that the state of atmospheric combustion is extremely close to
As a means for obtaining stable combustion, a mixed gas having an oxygen concentration of about 15 to 40% is made from the target gas and oxygen,
We have adopted a technology that uses this gas as a combustion-supporting gas in the same way as air. According to this means, the combustion of the raw material gas can be treated in the same way as the combustion in the atmosphere or the combustion in the air accompanied by slight oxygen enrichment. Therefore, a high-concentration high-temperature gas of 1000K to 1800K, which is a normal combustion gas temperature, can be manufactured very easily.

Although the example of carbon dioxide gas has been described above,
Combustion by adding a mixed gas of steam and oxygen to hydrogen gas, combustion by adding a mixed gas of carbon dioxide and oxygen gas to hydrocarbon gas, or combustion by adding a mixed gas of steam and oxygen gas, It is obvious that the same applies to combustion with the above mixed gas.
As described above, it is possible to relatively easily obtain a high-concentration and high-temperature ribbon property improving gas atmosphere.

As a result of the above, the surface properties of the ribbon are remarkably improved as compared with the production in the air and the production in a high temperature and low density atmosphere.

[0020]

EXAMPLE FIG. 1 shows an example of the present invention. The thin strip manufacturing apparatus melts and holds a metal having a predetermined component by an electric furnace (not shown) for melting and keeping heat, and supplies the metal to a tundish 2 with a casting nozzle 1 located under the electric furnace. The molten metal 3 is supplied to the tip of the nozzle through the molten metal passage in the tundish and is rapidly cooled by the cooling roll 4 to form the rapidly cooled ribbon 5. The rapidly cooled ribbon 5 is wound into a coil by a winding device (not shown) to be a product.
A shield plate 16 parallel to the roll axis is provided upstream of the paddle, and the gas burner 13 is burned in the atmospheric gas production box 15.

The atmosphere gas production box 15 has, for example, a slit-shaped opening at a portion facing the paddle, and the high-concentration high-temperature gas atmosphere is supplied to the paddle portion without being diluted with air from the opening. The combustion gas pipe 6 and its flow rate adjusting valve 9 are attached to the burner 13. On the other hand, combustion supporting gas is supplied from the pipes 7 and 8. For example, the carbon monoxide gas is supplied from the pipe 6, the carbon dioxide gas is supplied from the pipe 7, the oxygen gas is supplied from the pipe 8, and the flow rate adjusting valve 1
0, 11, and 12 are adjusted, mixed, and supplied to the gas burner 13.

Using this device, a width of 200 mm and a thickness of 40
A quenched amorphous ribbon having a composition of Fe 78% -Sil 3% -B 9% of μm was prepared. The roll 4 is an internally water-cooled Cu alloy having a diameter of 1000 mm and a water cooling width of 30 mm. The roll speed was 40 m / s. Using the burner / atmosphere manufacturing box 15 and the shielding plate 16 of the present invention, the burner 13 burns carbon monoxide gas at 50 liter / min with oxygen gas at 30 liter / min and carbon dioxide at 120 liter / min mixed gas at 150 liter / min. Let The main combustion was a combustion condition equivalent to 1.2 times the theoretical air ratio. Combustion was completely performed, and the temperature, carbon dioxide concentration, carbon monoxide concentration, and oxygen concentration in the atmosphere gas production box 15 were measured with commercially available measuring devices, respectively, and the temperature was 1500 K, carbon dioxide concentration 95%, and oxygen concentration 4 %, Carbon monoxide concentration is only 5
The ppm and nitrogen concentration were 1%. Further, the atmosphere temperature, carbon dioxide concentration, oxygen concentration, and nitrogen concentration at the site near the paddle and at a distance of about 1 mm are 1300K and 9%, respectively.
It was 0%, 5% and 5%. Since high-temperature gas is released into the atmospheric space, it is presumed that some atmospheric entrainment will occur. The gas concentration decreased by 200 K due to heat removal from the cooling roll. As a result, the surface texture of the ribbon is the surface roughness Ra.
Then, it was extremely smooth as 0.1 to 0.4 μm. Also,
Almost no gas pockets due to gas entrainment were observed.

Even when hydrogen gas (H ₃ 50 liters / minute) is burned with a mixed gas of oxygen gas (O ₂ 30 liters / minute) and steam (120 liters / minute), the ribbon properties are:
The surface roughness Ra was 0.1 to 0.4 μm, which was extremely smooth. Moreover, gas pockets due to gas entrainment were hardly observed. Further, dew condensation on the roll portion that did not come into contact with the ribbon was considered, but dew condensation did not occur because the gas temperature was high. However, dew condensation was observed on the peripheral devices.
Propane gas is used as the hydrocarbon gas, oxygen gas,
The same result was obtained when the mixture was burned with a mixed gas of carbon dioxide gas.

Next, a comparative example will be described. CO38
Platemaking was carried out by supplying ˜70% and the air surrounding it by the means disclosed in the prior art. As a result, the surface texture of the ribbon was 0.4 to 0.8 μm in terms of surface roughness Ra. In addition, some gas pockets due to gas entrainment were observed.

[0025]

According to the present invention, the target composition gas can be supplied at a high temperature and a high concentration to the space in which the air entrained by the roll is shut off, so that the surface properties of the production ribbon can be produced extremely smooth. Became possible. Further, as a secondary effect, it was possible to prevent the cold gas from hitting the nozzle tip, so that the nozzle tip was not cooled and nozzle clogging did not occur. Further, it is not necessary to compensate the molten metal temperature for suppressing nozzle clogging, and low temperature melting can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example of the present invention.

[Explanation of symbols]

1 Nozzle Tip 2 Tundish 3 Molten Metal 4 Cooling Roll 5 Quenching Amorphous Thin Strip 6 Carbon Monoxide Gas Pipe 7 Carbon Dioxide Gas Pipe 8 Oxygen Gas Pipe 9, 10, 11, 12 Flow Control Valve 13 Burner 15 Atmosphere Gas Production Box 16 Shield

Claims (3)

[Claims] 1. An apparatus for continuously producing an amorphous ribbon by supplying molten metal from a nozzle to the outer periphery of a high-speed rotating roll which is internally cooled, and a shielding plate with a minute gap between the roll and the roll. Is installed on the upstream side of rotation from the nozzle, and a supply device for supplying a mixed gas of carbon dioxide and / or water vapor and an oxygen-containing gas is provided between the shield plate and the paddle. Casting equipment. 2. The mixed gas comprises one or more combustible gases selected from the group consisting of carbon monoxide, hydrogen, and hydrocarbon gases, carbon dioxide and / or steam and an oxygen-containing gas. The apparatus for casting a metal strip according to claim 1, which is a combustion exhaust gas obtained by burning with gas. 3. The supply device comprises a gas combustion device, and the gas combustion device supplies a fuel gas supply pipe for supplying one or more gases selected from the group of carbon monoxide, hydrogen, and hydrocarbon gas, The apparatus for casting a metal strip according to claim 1, further comprising a combustion-supporting gas supply pipe for supplying carbon dioxide and / or water vapor and oxygen-containing gas.