JPH08300121A - Level control device and level control method in continuous casting machine - Google Patents

Abstract

(57) [Abstract] [Purpose] In a continuous casting machine, it is possible to accurately and highly reliably control the molten metal level in the mold without being affected by the coating material or the structure of the sensor. [Structure] In a continuous casting machine in which molten metal is continuously supplied to a mold 2 through a downcomer 3, a nozzle 9 is installed so that a gas discharge port is immersed in the molten metal of the mold 2, and a constant flow controller is provided. A constant flow rate of the inert gas is supplied from the inert gas cylinder 14 to the nozzle 9 through the gas pipe 10. At this time, the pressure value of the gas in the gas pipe 10 is detected by the gas pressure gauge 12, and the molten metal supply amount from the downcomer pipe 3 to the mold 2 is changed according to the change in the detected value.
Adjust by 3 to make the surface level constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal level control device and a molten metal level control method in a continuous casting machine for casting metal filaments and the like.

[0002]

2. Description of the Related Art Conventionally, in a continuous casting machine, molten metal level control is performed in order to obtain a stable ingot. This level control uses a non-contact type electrical sensor such as a capacitance type sensor or an eddy current type sensor to detect the level change of the level and to set the level to a predetermined level based on this. It's something you want to hold. In addition, control using a mechanical sensor that uses a float or the like or a sensor that uses radiation is also performed. Further, a method is also used in which an inert gas is blown into a molten metal and the depth of the molten metal surface is measured by a pressure change that changes according to the blowing depth.

FIG. 2 is a sectional view and a connection diagram showing a schematic configuration of a molten metal level control device using a capacitance type sensor. A mold 2 is arranged in the lower part of a furnace 1 (or a ladle) for melting mineral materials according to the product, and the molten metal (metals such as copper, copper alloy, aluminum and iron) in the furnace is controlled by a control member 1a. While being controlled, it is introduced into the mold 2 through the downcomer pipe 3. The mold 2 is filled with the molten metal 4, and the ingot 5 is pulled out from the lower part. Above the molten metal surface of the mold 2, the capacitance type sensor 6 is provided.
Is provided, and a molten metal flow rate adjusting unit 7 is connected to the capacitance type sensor 6. This molten metal flow rate control unit 7
The adjusting member 1a is controlled by the so that the amount of the molten metal flowing into the downcomer pipe 3 (that is, the molten metal level) is adjusted.

The mold 2 is water-cooled, so that the molten metal 4 in contact with the mold 2 is also cooled and begins to solidify. With the progress of this cooling, the molten metal 4 inside which is not in contact with the mold 2 is also cooled, whereby the ingot 5 is generated. Here, in order to prevent the molten metal from coming into contact with air during casting, the surface of the molten metal 4 is covered with a coating material (for example, graphite powder) 8.

The height of the molten metal surface is constantly monitored by the capacitance type sensor 6, and the molten metal is supplied from the downcomer pipe 3 to the mold 2 so that the molten metal height of the mold 2 becomes constant based on the detection result. The amount of molten metal to be supplied is controlled by the molten metal flow rate control unit 7.

[0006]

However, the capacitance type sensor is susceptible to not only the molten metal but also other members such as a mold and a cover for controlling the atmosphere. Further, when detecting the molten metal level, since the molten metal level including the thickness of the coating material is detected, the molten metal level control based on the inaccurate molten metal level is performed. For this reason, if the thickness of the coating material is constantly changing or if there is a large difference in thickness depending on the location, the molten metal surface cannot be controlled correctly.

Further, in the case of an eddy current sensor, electromagnetic noise from equipment around the sensor may cause malfunction, which makes it difficult to obtain reliability and places many restrictions on the installation position of the sensor. Furthermore, when a mechanical sensor is used, there is a concern that a malfunction may occur due to seizure or damage to the operating part during use. Further, when a radiation sensor is used, there are problems to be solved in terms of ensuring control accuracy and safety.

Further, in the method of measuring the depth of the molten metal surface by the pressure change which changes according to the blowing depth of the inert gas blown into the molten metal, the gas flow rate is not constant,
Since the amount of pressure change due to pressure loss is not constant, accurate measurement of the molten metal surface depth cannot be performed. Therefore, the present invention provides a molten metal level control device and a molten metal level control method in a continuous casting machine capable of accurately and highly reliably controlling the molten metal level without being affected by the coating material, the structure of the sensor, and the like. Is intended.

[0009]

In order to achieve the above object, the present invention is a continuous casting machine in which a molten metal is continuously supplied to a mold, in which a gas releasing portion is immersed in the molten metal of the mold. A nozzle, a gas supply means for supplying a constant flow rate of an inert gas from a gas source storing the inert gas to the nozzle, and a detection means for detecting the pressure of the inert gas supplied from the gas supply means. Provided is a melt level control device comprising: a flow rate adjusting means for adjusting a molten metal supply amount to the mold according to a change in gas pressure detected by the detecting means.

Further, the nozzle may have a structure in which a cylindrical cover is coaxially provided at least at the gas discharge portion. Further, the above-mentioned object is to continuously discharge a constant flow rate of the inert gas from the nozzle into the molten metal in the mold, and detect the gas pressure value in the path communicating with the nozzle at that time. It is also achieved by a molten metal level control method in which the molten metal amount introduced into the mold is adjusted so that the molten metal level in the mold becomes constant.

[0011]

According to the above means, the gas supply means supplies the inert gas at a constant flow rate to the nozzle, and the gas is discharged from the nozzle into the molten metal in the mold. The gas pressure value in the path such as a pipe communicating with the nozzle, which is detected by the detection means, varies depending on the height of the molten metal surface. This fluctuation represents a fluctuation in the height of the molten metal surface because a constant flow rate of gas is being sent to the nozzle. Therefore, the level of molten metal in the mold can be kept constant by measuring the gas pressure value in the path communicating with the nozzle and adjusting the amount of molten metal supplied to the mold according to the measurement result.

At this time, the cylindrical cover provided coaxially with the discharge portion of the nozzle is not affected by the molten metal introduced through the downcomer pipe, and the gas discharged from the nozzle is entrained in the molten metal. Can be prevented. Further, in the case of the above-mentioned molten metal level control method, the amount of pressure change due to the pressure loss can be made constant by continuously discharging a constant flow rate of the inert gas into the molten metal in the mold from the nozzle.
As a result, the fluctuation of the gas pressure value in the path communicating with the nozzle accurately corresponds to the fluctuation of the height between the molten metal surface in the mold and the gas discharge position. Therefore, by detecting the fluctuation of the gas pressure value and adjusting the amount of molten metal introduced into the mold based on the detection result, the level of the molten metal in the mold is kept constant.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view and a connection diagram showing a schematic configuration of a continuous casting machine and a molten metal level control apparatus showing a molten metal level control apparatus in a continuous casting machine according to the present invention. Since the structure of the continuous casting machine is the same as that of FIG. 2, the description thereof is omitted here, and the same reference numerals are used for the same members in the drawing.

The present embodiment is based on the use of an inert gas as a means for measuring the depth of the molten metal surface. FIG.
As shown in, a nozzle 9 is inserted into the molten metal 4,
A gas pipe 10 (path) is connected to the nozzle 9. The gas pipe 10 is branched on the way, and a constant flow controller 11 (gas supply means) is connected to one side and a gas pressure gauge 12 (detection means) is connected to the other side. The gas pressure gauge 12 includes a molten metal flow rate control unit 13 (flow rate control means) for controlling the amount of molten metal supplied to the mold 2.
Is connected. Further, an inert gas cylinder 14 (argon, nitrogen or the like is used as the inert gas) is connected to the constant flow controller 11 through a pipe.

It is desirable that the nozzle 9 is installed at the center of the mold away from the solidification interface so that gas is not entrained as much as possible. However, since the downcomer pipe 3 is in the center, it is brought close to the inner wall of the mold, and the nozzle cover 15 is covered on the tip of the nozzle 9 so that the molten metal flowing from the downcomer pipe 3 does not directly hit the nozzle 9. Further, by providing the nozzle cover 15, the nozzle 9 can be installed at a location relatively close to the solidification interface, and the degree of freedom with respect to the installation location of the nozzle 9 can be increased. Of course, the nozzle cover 15 may be omitted.

In the above construction, the molten metal is supplied from the furnace 1 to the mold 2 through the downcomer 3, and the ingot 5 is taken out as the mold 2 is cooled as described above. In this state, the inert gas is output from the inert gas cylinder 14 and continuously fed to the nozzle 9 via the gas pipe 10 while being adjusted to a constant flow rate (for example, 1 liter / min or less) by the constant flow controller 11. Be done. Since the nozzle 9 is inserted so that its tip reaches the inside of the molten metal 4 (for example, immersed at a depth of about 100 mm from the molten metal surface), the pressure loss in the gas pipe 10 becomes constant, and the gas is released. The amount of change in hydrostatic pressure that occurs according to the distance from the tip of the nozzle 9, which is a part, to the molten metal surface can be detected as the amount of molten metal surface change.

This makes it possible to significantly reduce the influence of various disturbances other than the molten metal 4. Further, since the device connected to the nozzle 9 can be installed at a position apart from the mold 2 with respect to the nozzle 9, the unstable factors of control due to temperature change can be drastically reduced and the durability of the device can be improved. Become. The pressure in the gas pipe 10 is constantly monitored by the gas pressure gauge 12, and when the height of the molten metal surface in the mold 2 rises, the measured pressure value increases, and when the height of the molten metal surface decreases, the measured pressure value decreases. Therefore, the molten metal flow rate control unit 13 is operated using the output signal of the gas pressure gauge 12 to reduce the amount of the molten metal introduced from the downcomer pipe 3 into the mold 2 in accordance with the increase in the pressure measurement value, and the pressure measurement value Downcomer 3 according to the decrease of
The amount of molten metal introduced from the mold to the mold 2 is adjusted. By this adjustment, the height of the molten metal 4 can be maintained at a constant level.

In the above embodiment, argon or nitrogen was used as the inert gas, but any gas may be used as long as it does not cause an undesired change when it reacts with the liquid.

[0019]

As is clear from the above, according to the present invention, a nozzle in which the gas releasing portion is immersed in the molten metal of the mold,
A gas source for storing an inert gas, a gas supply means for supplying a constant flow rate of the inert gas from the gas source to the nozzle, and a pressure of the inert gas in a path from the gas supply means to the nozzle. Since the detecting means for detecting the value and the flow rate adjusting means for adjusting the molten metal supply amount to the mold according to the fluctuation of the gas pressure detected by the detecting means, the coating material is not used, Moreover, the control accuracy of the molten metal surface can be improved without being affected by the structure of the sensor and the like. Further, it is possible to reduce the work involved in the casting work and improve the productivity.

Further, a constant flow rate of an inert gas is continuously discharged from the nozzle into the molten metal in the mold, the gas pressure value in the path communicating with the nozzle at that time is detected, and based on this detection result According to the molten metal level control method in which the molten metal amount to be introduced into the mold is adjusted so that the molten metal level in the mold becomes constant, similarly, no coating material is used, and due to the structure of the sensor, etc. It is possible to improve the control accuracy of the molten metal surface without being affected by Further, it is possible to reduce the work involved in the casting work and improve the productivity.

[Brief description of drawings]

FIG. 1 is a cross-sectional view and a connection diagram showing a schematic configuration of a continuous casting machine and a molten metal level control apparatus showing a molten metal level control apparatus in a continuous casting machine according to the present invention.

FIG. 2 is a sectional view and a connection diagram showing a schematic configuration of a molten metal level control device using a continuous casting machine and a capacitance type sensor.

[Explanation of symbols]

 2 mold 3 downcomer pipe 4 molten metal 9 nozzle 10 gas pipe 11 constant flow controller 12 gas pressure gauge 13 molten metal flow rate control unit 14 inert gas cylinder 15 nozzle cover

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Kagawa 3550 Kidayomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Cable Ltd. Tsuchiura Plant

Claims (3)

[Claims] 1. A continuous casting machine in which a molten metal is continuously supplied to a mold, a nozzle in which a gas releasing portion is immersed in the molten metal of the mold, and an inert gas from a gas source which stores the inert gas. Gas supply means for supplying a constant flow rate to the nozzle, detection means for detecting the pressure of the inert gas supplied from the gas supply means, and the mold according to the fluctuation of the gas pressure detected by the detection means A melt level control device for a continuous casting machine, comprising: 2. The molten metal level control device in a continuous casting machine according to claim 1, wherein the nozzle has a cylindrical cover coaxially provided at least at a gas discharge portion. 3. A constant flow rate of an inert gas is continuously discharged from a nozzle into the molten metal in the mold, the gas pressure in a gas passage communicating with the nozzle is detected, and based on the detection result, the inside of the mold is detected. A method for controlling a molten metal level in a continuous casting machine, which comprises adjusting the amount of molten metal introduced into the mold so that the molten metal level becomes constant.