JPH0577018A - Control method for flow rate of molten metal in continuous casting - Google Patents

Abstract

PURPOSE:To provide a control method for flow rate of molten metal, in which the molten metal surface in a mold is suitably adjusted, by controlling the flow rate of the molten metal supplied from a tundish in continuos casting. CONSTITUTION:At the upper part of an immersion nozzle 6 in the tundish 1 for supplying the molten metal 16 into the mold 7, a discharging part 3 of almost the same diameter as the above nozzle is arranged, and an electromagnetic flow meter 4 at the upper side of the discharging part and a sliding nozzle 5 at the low side thereof, are fitted and at first, the flow rate of the molten metal flowing through the discharging part 3 is detected with the electromagnetic flow meter 4 and converted into a flow rate signal, and the sliding nozzle 5 is opened/closed based on this signal to control the flow rate of the molten metal in the discharging part. The flow rate of the molten metal flowing through the immersion nozzle is precisely grasped, and also the suitable flow rate control and adjustment of the molten metal surface can be executed, and the stable operation and the quality improvement of a cast slab are obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for appropriately controlling the flow rate of molten metal supplied from a tundish to a mold when supplying molten metal to a continuous casting mold.

[0002]

2. Description of the Related Art When a molten metal is supplied to a continuous casting mold for casting, a conventional method for controlling the flow rate of the molten metal supplied from the tundish to the mold is a non-contact type method for controlling the surface level of the molten metal in the mold. Measurement is performed using a displacement meter, and the flow rate from the tundish is controlled so that the surface level becomes constant based on this measurement value.

[0003]

However, in this conventional method, since the actual flow rate of the molten metal supplied to the mold cannot be measured, the flow rate is not stable and, as a result, the surface of the molten metal in the mold is consequently unstable. There was a problem that the level could not be controlled constantly.

It is also possible to directly measure the molten metal flow rate by attaching an electromagnetic flow meter to the immersion nozzle which is supplied from the tundish to the mold, but in many cases the molten metal does not fill the inside of the nozzle 4 and therefore the immersion nozzle is used. Even if an electromagnetic flow meter is attached to the, the flow rate measurement is not always accurate.

The present invention has been made to solve the above problems, and provides a molten metal flow rate control method for appropriately controlling the flow rate of molten metal supplied from a tundish to a mold in continuous casting.

[0006]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems is achieved by providing an outflow portion having substantially the same diameter as the immersion nozzle above the immersion nozzle of a tundish for supplying molten metal to a continuous casting mold. An electromagnetic flow meter is installed on the upper side of the section, and a sliding nozzle is installed on the lower side, and the flow rate of molten metal flowing down the outflow section is detected by the electromagnetic flow meter and converted into a flow rate signal, and this signal is flow rate controlled. A method for controlling the flow rate of molten metal in continuous casting, which is characterized in that the flow rate is converted into a control signal via a device, and the sliding nozzle is opened / closed by the signal to control the flow rate of the molten metal in the outflow portion.

[0007]

[Operation] An electromagnetic flow meter is an electromotive force induced by electromagnetic induction in a direction perpendicular to the magnetic field direction when the molten metal passes through a magnetic field when measuring the flow rate of the molten metal flowing in a pipe with a fixed diameter. Is a flow meter that uses as an index. In this case, if the pipe is not filled with the molten metal, the measured flow rate is not always accurate, as described in the section of the prior art.

In the present invention, an outflow portion having a diameter substantially the same as that of the immersion nozzle is provided above the immersion nozzle of the tundish for supplying molten metal, an electromagnetic flow meter is attached to the upper side of the outflow section, and a sliding nozzle is provided at the lower side. By installing the, the outflow part is constantly filled with the molten metal, and the flow rate measurement is aimed at accuracy.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a main part of a continuous casting apparatus suitable for carrying out the present invention, and FIG. 2 shows a cross section of an electromagnetic flow meter mounting part of a molten metal outflow part.

Above the immersion nozzle 6 of the tundish 1 for supplying molten metal to the continuous casting mold 7, the immersion nozzle 6 is provided.
An outflow portion 3 having substantially the same diameter as that of the outflow portion 3 is provided, an electromagnetic flow meter 4 is attached to the upper side of the outflow portion 3, and a sliding nozzle 5 is attached to the lower side. Reference numeral 2 is a hot water storage portion of the tundish 1, 16 is a poured molten metal, and 15 is a solidified shell.

The electromagnetic flow meter 4 has a magnetic pole 8 with the outflow portion 3 interposed therebetween.
Electrodes 11a and 11b for detecting the induced electromotive force 10 are attached at positions orthogonal to the magnetic field 9 of the outflow portion 3 with the a and 8b facing each other.

Outflow portion 3 from hot water storage portion 2 of tundish 1
The molten metal flowing down is first filled in the outflow portion 3, then passes through the sliding nozzle 5, flows down the immersion nozzle 6, and is supplied to the mold 7.

The induced electromotive force 10 generated between the electrodes 11a and 11b of the electromagnetic flow meter 4 due to the flow of the molten metal when flowing down the outflow portion 3 is first input to the flow rate control device 13 via the converter 12 as a flow rate signal. Is converted into a control signal that is the target flow rate, and then the sliding nozzle 5 is driven by the sliding nozzle driver 14 based on this signal.
Is opened and closed to a target opening degree, and the flow rate of the molten metal in the outflow portion 3 is controlled.

As an embodiment of the present invention, in the continuous casting apparatus shown in FIGS. 1 and 2, the horizontal cross section is 250 mm × 16.
Molten steel having a common steel composition and a molten metal temperature of 1521 ° C. was supplied from a tundish to a 00 mm mold for continuous casting.

As Comparative Example 1, the immersion nozzle 6 shown in FIG.
The sliding nozzle 5 is attached to the upper part of the mold, the surface level of the molten metal in the mold is measured using the non-contact type level detector 17, and the flow rate from the tundish 1 is adjusted based on the measured value so that the surface level becomes constant. Continuous casting was performed using a conventional continuous casting apparatus controlling the temperature.

As Comparative Example 2, in the continuous casting apparatus shown in FIG. 1, the continuous casting apparatus shown in FIG. 4 in which the sliding nozzle 5 is attached to the upper side of the outflow part 3 and the electromagnetic flow meter 4 is attached to the lower side. Used for continuous casting.

As a target value for casting in the above three examples, the surface level of the molten metal in the mold was controlled so as to maintain 100 mm from the top surface of the mold. The implementation results are shown in FIGS. 5 (a), (b), and (c). In FIG. 5, the vertical axis represents the variation value from the target molten metal surface level value of 100 mm, and the horizontal axis represents the elapsed time.

In the case of the present embodiment, as shown in FIG. 5 (a), the level of the surface of the molten metal changes within ± 1 mm with respect to the target 100 mm position from the top surface of the mold. The molten metal supplied is controlled stably.

On the other hand, in the case of Comparative Example 1, FIG.
As shown in (b), it fluctuates within a range of ± 5 mm with respect to the target level, and it cannot be said that the control is stable.

Further, in the case of Comparative Example 2, as shown in FIG. 5 (c), the molten metal level fluctuates significantly by ± 20 mm or more with respect to the target level due to unstable control, and stable flow rate measurement is performed. I couldn't.

[0021]

As described above, according to the present invention, an electromagnetic flow meter is installed on the upper side of the outflow part, and a sliding nozzle is installed on the lower side to sufficiently fill the outflow part with molten metal and measure the molten metal flow rate. Therefore, it is possible to accurately grasp the flow rate and perform appropriate flow rate control and molten metal level adjustment.
It is possible to achieve stable operation and improve the quality of the slab.

[Brief description of drawings]

FIG. 1 is a side view showing a main part of a continuous casting apparatus suitable for carrying out the present invention.

FIG. 2 is a cross-sectional view showing details of an electromagnetic flow meter mounting portion of a molten metal outflow portion.

FIG. 3 is a side view showing a continuous casting apparatus used in Comparative Example 1.

FIG. 4 is a side view showing a continuous casting apparatus used in Comparative Example 2.

FIG. 5 is a drawing showing the results of carrying out molten surface control stability tests of Examples and Comparative Examples.

[Explanation of symbols]

 1 Tundish 2 Tundish Hot Water Storage Section 3 Tundish Outflow Section 4 Electromagnetic Flowmeter 5 Sliding Nozzle 6 Immersion Nozzle 7 Mold 8a, 8b Magnetic Pole 9 Magnetic Field 10 Induced Electromotive Force 11a, 11b Electrode 12 Converter for Electromagnetic Flowmeter 13 Flow Control Device 14 Sliding nozzle driver 15 Solidification shell 16 Molten metal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Kobayashi 1 Kimitsu, Kimitsu-shi, Chiba Shin Nippon Steel Co., Ltd. Kimitsu Steel Works

Claims (1)

[Claims] 1. An outflow part having substantially the same diameter as that of the immersion nozzle is provided above the immersion nozzle of a tundish for supplying molten metal to a continuous casting mold, and an electromagnetic flow meter is provided on the upper side of the outflow part.
Further, a sliding nozzle is attached to the lower side, the flow rate of the molten metal flowing down the outflow portion is detected by an electromagnetic flow meter, and this is converted into a flow rate signal, and the signal is converted into a control signal via a flow rate control device, A method for controlling the flow rate of molten metal in continuous casting, wherein the sliding nozzle is opened and closed by the signal to control the flow rate of molten metal in the outflow portion.