JPH06297116A - Nozzle for continuously casting metal and method for pouring molten metal using its nozzle - Google Patents

Abstract

PURPOSE:To prevent the occurrence of troubles, such as the unstability of control for molten metal pouring rate, the contamination of the molten metal caused by involving with gas, by generating a meniscus of the molten metal in the inner part of a pouring nozzle and aggravating fluid condition, in the continuous casting by using the split type nozzle. CONSTITUTION:The nozzle for continuous casting is formed with an upper nozzle 1A at the bottom part of a tundish or a lower plate 2A of a sliding nozzle and an immersion nozzle 1B or 2B connected with the lower part of the above nozzle or plate and at the time of continuously casting the molten metal, while adjusting the supplying rate of the molten metal with a stopper device or a sliding nozzle device, the molten metal is continuously poured into the mold. Then, gas vent adjusting holes are arranged to the upper nozzle 1A at the bottom part of the tundish or the lower plate 2A of the sliding nozzle and/or the immersion nozzle 1B or 2B. While discharging the gas retained in the upper part of an inner hole zone through the gas vent adjusting holes, the molten metal is poured into the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle for continuous casting of metal and a method for pouring molten metal using the nozzle.

[0002]

2. Description of the Related Art Conventionally, an upper nozzle 1C and a dipping nozzle 1D shown in FIG. 3 are joined together, and a lower plate 2C and a dipping nozzle 2D of a sliding nozzle 5 mounted on a bottom 2 of a tundish shown in FIG. The joining of
The relationship between the joint surface of the immersion nozzle and the joint surface facing each other is generally flat or curved joint 3. Further, at the time of joining, in order to maintain the airtightness of the joined portion, a joining method is adopted in which a sealing material 6 processed with an indeterminate refractory or a flame-retardant material is sandwiched between the joining surfaces and pressure-bonded.

[0003]

However, in the above-mentioned conventional joining method, since the hot sintering and hardening type or compression densification type is adopted as the characteristic of the sealing material 6 between the joining surfaces, the hot joining The airtightness of the joint deteriorates due to shrinkage and hardening cracks, and when the molten metal passes through the nozzle, the outside air surrounding the joint is sucked in and the gas bubbles are turbid in the molten metal. As a result, not only does the flow resistance increase during hot water flow, but the gas bubbles that float up and separate from the molten metal inside the nozzle stay as gas bodies at the upper part of the inner hole zone of the nozzle. There were problems peculiar to the continuous casting nozzle formed by the split mold, such as generation of meniscus, worsening of flow condition, unstable control of pouring amount, and contamination of molten metal with gas inclusion.

Further, even when the airtightness of the joint is ensured by the pouring nozzle for continuous casting formed by the split mold, the pouring amount of the molten metal supplied into the mold is small at the beginning of casting, Therefore, it is impossible to completely discharge the gas body existing in the inner hole zone of the nozzle by the injection flow of the molten metal, and particularly when using a long nozzle, regardless of the bore diameter, it remains without being discharged. The generated gas affects the pouring control at the initial stage of casting, and there was a problem in continuous casting of metal that requires highly precise pouring amount control.

[0005]

Means for Solving the Problems That is, the gist of the present invention is as follows. (1) An upper nozzle of a tundish bottom portion and an immersion nozzle joined below the lower nozzle are formed. A continuous casting nozzle for continuously pouring molten metal into a mold while adjusting the supply amount of molten metal by a stopper device, wherein the upper nozzle and / or the immersion nozzle is provided with a degassing adjusting hole. Nozzle for continuous casting. (2) The nozzle described in (1) is arranged in a tundish, and the molten metal is poured into the mold through the nozzle while discharging the gas staying in the upper part of the inner hole band through the degassing adjustment hole. A method for pouring molten metal, comprising: Alternatively, (3) it is formed by a lower plate of a sliding nozzle and an immersion nozzle joined to the lower plate, and during continuous casting of molten metal, the amount of molten metal supplied is adjusted by a sliding nozzle device into the mold. A continuous casting nozzle for continuously pouring a lower plate or /
And a nozzle for continuous casting of metal, characterized in that a gas venting adjusting hole is provided in the immersion nozzle. In addition, the nozzle described in (4) and (3) is arranged in a tundish, and the molten metal is passed through the nozzle through a nozzle for discharging molten metal through the gas venting adjustment hole while discharging the gas accumulated in the upper part of the inner hole band. A method for pouring molten metal, characterized by pouring into molten metal.

[0006]

The function of the present invention will be described in detail below. As a result of various studies to solve the problems in the conventional technique, the present inventors have shown that, as shown in FIG. When a pouring nozzle is used, when the molten metal is passed through the nozzle, it is easy to suck the outside air from the joint surfaces 3 of the divided parts, and the molten metal injection flow becomes a multi-phase flow in which gas bubbles are turbid, and the flow resistance in the nozzle is reduced. It was clarified that the flow condition of the molten metal becomes more and more unstable, not only by increasing the number, but by creating a gas chamber that stays at the top and forming a secondary meniscus inside the pouring nozzle. Further, in the above-mentioned situation, it was also found that even if the opening of the stopper is opened larger than the theoretical opening of the required supply amount, the molten metal pouring amount is not easily recovered.

On the basis of the above examination results, when the split type pouring nozzle for continuous casting is used in the continuous casting process of metal, the nozzle is sucked from the joint portion 3 or left without being discharged in the initial stage of casting. In order to continuously or intermittently discharge the gas accumulated in the upper part of the inner hole zone, the upper nozzle 1A of the tundish bottom 2 according to the present invention and the dipping nozzle 1B joined below the tundish bottom 2 according to the present invention are provided. The continuous casting nozzle provided with the degassing adjustment hole 6 is arranged in the tundish 1,
Degassing was performed by a vacuum device through the degassing adjustment hole 6. As a result, the gas accumulated in the upper part of the inner hole zone of the nozzle was successfully discharged, the opening of the stopper 4 was stabilized at almost the theoretical opening, and highly accurate pouring amount control was continued for a long time. Then, the effectiveness of the present invention was found. This means that, as shown in FIG. 2, the relationship between the upper nozzle 1A and the dipping nozzle 1B is replaced by the lower plate 2A of the tundish bottom 2 or the ladle bottom sliding nozzle 5 and the dipping nozzle 2B joined under the lower plate 2A. Is also the same.

[0008]

【Example】

Example 1 In the manufacturing process of low carbon aluminum killed steel that is continuously cast by the two-strand method, when pouring molten steel whose supply amount is controlled by a stopper device into a mold from a tundish, both strands are split-type pouring nozzles. A comparative experiment of pouring control was performed, one of which was a nozzle with a gas venting adjusting hole 6 according to the present invention, and the other was of a conventional specification.
In the experiment, the mold sizes and casting speeds of both strands were set to the same conditions, no gas was vented in the conventional example, and in the present invention, the gas in the nozzle was discharged by a vacuum suction device through a gas venting adjustment hole for casting.

As a result, the pouring amount control stopper opening of the conventional example tends to increase with the passage of time while repeatedly fluctuating cyclically, whereas in the present invention, the stopper opening remains substantially constant, The change over time from the beginning to the end of casting is extremely small and stable control is achieved.

Example 2 In this example, in addition to the experimental conditions of Example 1, a long pouring nozzle, in which the immersion depth of the nozzle in the mold is deepened by about 30%, is arranged in the tundish 1, and The experiment was done. As a result, as shown in FIG. 5, the pouring amount control stopper 4 of the conventional example is in a state in which the pouring amount of molten steel required for a predetermined casting speed cannot be poured while rapidly opening a large opening within a short time. , Slowing down the casting speed, and stopper 4
It was an abnormal casting that required intervention such as recovery operation by intentionally operating. On the other hand, in the present invention, when casting was performed while continuously sucking gas through the gas venting adjustment hole 6, stable pouring amount control was possible without any problems until the end of charging.

[0011]

As described above, according to the present invention, even if the continuous casting nozzle for metal is a split type pouring nozzle having a joint portion, the molten metal can be supplied with high precision and controlled. It is possible to pour molten metal into the mold in a stable amount.

[Brief description of drawings]

FIG. 1 is a nozzle for continuous casting of a tundish having a stopper device, which is provided with a gas venting adjusting hole according to the present invention.

FIG. 2 is a nozzle for continuous casting having a venting hole according to the present invention in a tundish having a sliding nozzle device.

FIG. 3 is a conventional continuous casting nozzle of a tundish having a stopper device.

FIG. 4 is a conventional continuous casting nozzle for a tundish having a sliding nozzle device.

FIG. 5 is a comparative evaluation result of temporal characteristics of stopper opening.

[Explanation of symbols]

1A Inventive Nozzle for Tundish with Stopper Device 1B Inventive Immersion Nozzle for Tundish with Stopper Device 2A Inventive Lower Plate for Tundish with Sliding Nozzle Device 2B Lower Plate for Sliding Nozzle Device and Inventive Invention for Joining Nozzle 1C Conventional upper nozzle of tundish with stopper device 1D Conventional tundish immersion nozzle with stopper device 2C Conventional lower plate of tundish with sliding nozzle device Lower plate of 2D sliding nozzle device and conventional immersion nozzle for joining 1 t Dish 2 Tundish bottom 3 Joining surface 4 Stopper 5 Sliding nozzle 6 Sealing material 7 Gas venting adjustment hole 8 Tanning nozzle for sliding nozzle

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[Procedure amendment]

[Submission date] August 10, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

On the basis of the above examination results, when the split type pouring nozzle for continuous casting is used in the continuous casting process of metal, the nozzle is sucked from the joint portion 3 or left without being discharged in the initial stage of casting. In order to continuously or intermittently discharge the gas accumulated in the upper part of the inner hole zone, the upper nozzle 1A of the tundish bottom 2 according to the present invention and the dipping nozzle 1B joined below the tundish bottom 2 according to the present invention are provided. A continuous casting nozzle provided with a gas venting adjusting hole 7 is arranged in the tundish 1,
Degassing was performed by a vacuum device through the degassing adjustment hole 7 . As a result, the gas accumulated in the upper part of the inner hole zone of the nozzle was successfully discharged, the opening of the stopper 4 was stabilized at almost the theoretical opening, and highly accurate pouring amount control was continued for a long time. Then, the effectiveness of the present invention was found. This means that, as shown in FIG. 2, the relationship between the upper nozzle 1A and the immersion nozzle 1B is replaced by the lower plate 2A of the tundish bottom 2 or the sliding nozzle 5 at the bottom of the ladle and the immersion nozzle 2B joined below the plate. Is also the same.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Example 2 In this example, in addition to the experimental conditions of Example 1, a long pouring nozzle, in which the immersion depth of the nozzle in the mold is deepened by about 30%, is arranged in the tundish 1, and The experiment was done. As a result, as shown in FIG. 5, the pouring amount control stopper 4 of the conventional example is in a state in which the pouring amount of molten steel required for a predetermined casting speed cannot be poured while rapidly opening a large opening within a short time. , Slowing down the casting speed, and stopper 4
It was an abnormal casting that required intervention such as recovery operation by intentionally operating. On the other hand, in the present invention, when casting was performed while continuously performing gas suction through the gas venting adjustment hole 7 , stable pouring amount control could be performed without any problems until the end of charging.

[Procedure 3]

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[Correction method] Change

[Correction content]

[Figure 1]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

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[Fig. 2]

[Procedure Amendment 5]

[Document name to be corrected] Drawing

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[Correction method] Change

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[Figure 3]

[Procedure correction 6]

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[Figure 4]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akira Itoyama 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Corporate Technology Development Division

Claims (4)

[Claims] 1. An upper nozzle at the bottom of a tundish and a submerged nozzle joined below the lower nozzle. When continuously casting molten metal, the amount of molten metal fed into a mold is adjusted by a stopper device. A continuous casting nozzle for continuously pouring molten metal, characterized in that an upper nozzle and / or a dipping nozzle is provided with a gas venting adjusting hole. 2. The nozzle according to claim 1 is arranged in a tundish, and the molten metal is discharged to the mold through the nozzle while discharging the gas staying at the upper part of the inner hole band through the gas venting adjusting hole. A method for pouring molten metal, characterized by pouring. 3. A lower plate of a sliding nozzle and a submerged nozzle which is joined to the lower plate, and when the molten metal is continuously cast, the amount of the molten metal supplied is adjusted by a sliding nozzle device into the mold. A continuous casting nozzle for continuously casting molten metal, characterized in that a lower plate and / or a dipping nozzle is provided with a gas venting adjusting hole. 4. The nozzle according to claim 3 is arranged in a tundish, and the molten metal is discharged to the mold through the nozzle while discharging the gas staying at the upper part of the inner hole band through the gas venting adjusting hole. A method for pouring molten metal, characterized by pouring.