JP3252769B2 - Flow control method of molten steel in continuous casting mold - 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 detecting the flow of molten steel in a continuous casting mold for steel, and for controlling the flow of the molten steel by applying an electromagnetic force generated by a magnetic field.

[0002]

2. Description of the Related Art In continuous casting of steel, molten steel is discharged into a mold at a high speed through an immersion nozzle. Therefore, a flow of molten steel is generated in the mold due to the discharge flow. It has a significant effect on the surface and internal properties of the slab. For example, when the surface flow velocity of the mold surface (hereinafter, referred to as “meniscus”) is too high, or when a vertical vortex is generated in the meniscus, the mold powder is caught in the molten steel. It is also known that the floatation of deoxidized products such as Al ₂ O _{3 in} molten steel depends on the flow of molten steel. Mold powder and deoxidized products entrained in slabs are It becomes a defect of nonmetallic inclusion properties.

[0003] In addition, the flow of molten steel in a mold has the same casting conditions.
Even if the Al inside the immersion nozzle _TwoO_ThreeAdhesion, immersion
Depending on the melting loss of the nozzle and the opening of the sliding nozzle,
Changes during construction. Therefore, the flow of molten steel is detected and detected.
The strength and direction of the applied magnetic field from the flow of molten steel
Control of molten steel flow in the mold by
A number of important issues have been proposed.

For example, Japanese Unexamined Patent Publication (Kokai) No. 62-252650 (hereinafter referred to as "prior art 1") discloses that a level difference between molten steel on the left and right of an immersion nozzle is detected by a thermocouple embedded in a copper plate on a short side of a mold. There is disclosed a molten steel flow control method in which the stirring direction and the stirring thrust of the electromagnetic stirring device are controlled so as to eliminate the problem.

Japanese Patent Application Laid-Open No. 3-275256 (hereinafter, referred to as “Japanese Patent Application Laid-open
According to “prior art 2”, the temperature distribution of the copper plate on the long side of the mold is measured by a thermocouple embedded in the copper plate on the long side of the mold, and the occurrence of molten steel drift is detected from the temperature distribution on the left and right sides of the mold. A method is disclosed in which the current supplied to two DC electromagnet-type electromagnetic brake devices arranged on the back of the long side of the mold is individually controlled in accordance with the direction and degree of occurrence of the flow to control the drift of the molten steel in the mold. .

[0006] Japanese Patent Application Laid-Open No. Hei 4-284956 (hereinafter, referred to as
In “Prior art 3”, two non-contact type distance meters are provided on the meniscus between the immersion nozzle and the short side of the mold to measure the fluctuation of the level of the meniscus. A method is disclosed in which the propagation speed of a surface wave is determined from a cross-correlation function, and the discharge flow rate from an immersion nozzle is controlled by an electromagnetic stirrer so that the propagation speed is equal to or less than a predetermined value.

[0007]

In Prior Art 1 and Prior Art 2, the flow of molten steel is controlled based on the information of the temperature of the mold copper plate. However, the change in the temperature of the mold copper plate is caused only by the change in the flow state of the molten steel. It does not necessarily occur, but also occurs due to changes in the state of contact between the mold and the solidified shell, the state of inflow of the mold powder, and the like. As described above, there is a change in the temperature of the mold copper plate due to factors other than the flow of the molten steel, and therefore, the prior art 1 and the prior art 2 cannot accurately detect the flow state of the molten steel.

As will be described in detail later, from the results of investigations by the present inventors, in order to reduce mold powder and deoxidized products, it is not enough to prevent drift in the mold and to achieve a symmetrical flow. Sufficient, it has been confirmed that, among several symmetric flows, an optimal flow pattern exists.

Prior art 3 is an effective means as a flow control method, but controls only the flow velocity of the molten steel in the meniscus, and is insufficient for detecting the flow pattern of the molten steel in the mold. Similarly, the flow patterns cannot be detected even in the prior arts 1 and 2.

The present invention has been made in view of the above circumstances, and an object of the present invention is to detect a flow pattern of molten steel in a mold in continuous casting and control a magnetic field to be applied based on the detected flow pattern to optimize the flow. It is to provide a flow control method capable of maintaining a proper flow pattern.

[0011]

According to a first aspect of the present invention, there is provided a method for controlling the flow of molten steel in a continuous casting mold, wherein a magnetic field is applied to a discharge flow from an immersion nozzle to continuously cast steel. the surface temperature of the solidified shell of the slab width direction is measured a plurality of points, and detects the flow pattern of the molten steel in the mold from the aging of the surface temperature at each measurement point, the molten steel at the meniscus
The direction of flow is between the immersion nozzle and the short side of the mold.
Near the boundary, the flow toward the center of the mold on the immersion nozzle side
Thus, the strength of the applied magnetic field is adjusted based on the detection result so that the flow pattern becomes a flow toward the short side of the mold on the short side of the mold .

A method for controlling the flow of molten steel in a continuous casting mold according to a second aspect of the present invention is the method for controlling the flow of molten steel in a continuous casting mold according to the first aspect of the invention, wherein the surface temperature of the solidified shell changes with time and the measurement point where the surface temperature rises and falls. The present invention is characterized in that a distribution of measurement points is obtained, and a flow pattern of molten steel in a mold is detected based on a distribution of measurement points that rise and / or a distribution of measurement points that fall.

According to a third aspect of the present invention, there is provided a method of controlling molten steel flow in a continuous casting mold according to the first or second aspect of the invention, wherein the applied magnetic field is a moving magnetic field that moves in a horizontal direction. It is a feature.

According to a fourth aspect of the present invention, there is provided a method of controlling molten steel flow in a continuous casting mold according to any one of the first to third aspects of the present invention, wherein a plurality of steel plates penetrating a long side copper plate of the mold are provided. The surface temperature of the solidified shell is measured by an optical fiber.

According to the results of investigations by the inventors, the flow pattern of molten steel in a mold is complicated by the influence of Ar gas bubbles floating in the mold and the applied magnetic field, even if the flow is symmetrical with no drift. Change and simplify its flow pattern,
It has been found that the pattern A shown in FIG. In FIG. 1, 3 is a short side of a mold, 4 is molten steel, 5 is a solidified shell, 8 is a dipping nozzle, 9 is a discharge hole, 10 is a discharge flow, 13 is a meniscus, 1
Reference numeral 4 denotes a mold powder.

In the pattern A, the discharge flow 10 from the immersion nozzle 8 reaches the solidified shell 5 on the short side 3 of the mold.
After the collision, the flow is separated into two flows, and one flow rises to the meniscus 13 along the solidified shell 5 on the short side 3 of the mold, and further the meniscus 13 is moved from the short side 3 of the mold to the center of the mold (immersion nozzle). 8), and the other flow has a flow pattern of flowing downward from the point of collision with the solidified shell 5 below the mold.

On the other hand, in pattern B, the discharge flow 10 from the immersion nozzle 8 reaches the solidified shell 5 on the short side 3 of the mold due to the floating effect of Ar gas bubbles on the discharge flow 10 or the influence of the application of a magnetic field. Instead, it is dispersed between the discharge hole 9 and the solidified shell 5 on the side of the mold short side 3 to form an ascending flow and a descending flow. In the meniscus 13, the immersion nozzle 8 and the mold short side 3 With the vicinity of the intermediate position as a boundary, the immersion nozzle 8
On the side, a flow toward the center of the mold (toward the immersion nozzle 8)
On the mold short side 3 side, the flow pattern is such that the flow is directed toward the mold short side 3 on the contrary.

The pattern C is a flow pattern in which an upward flow of the discharge flow 10 exists near the immersion nozzle 8, and appears mainly due to the floating of coarse Ar gas bubbles. In the pattern C, at the meniscus 13, the center side of the mold (immersion nozzle 8
Side) to the mold short side 3 side is the main flow.

For each flow pattern of the molten steel in the mold, the amount of defective products due to mold powder defects in thin steel products was investigated. FIG. 2 shows the result of the investigation. As shown in FIG. 2, it was found that when the flow pattern of the molten steel in the mold was pattern B, there were few mold powder defects and the slab quality was the best. The reason is considered as follows.

In the case of pattern A, a vortex which causes mold powder to be mixed into molten steel is easily generated in the meniscus between the center of the mold and a position which is 1/4 of the width of the mold from the center of the mold. When the surface flow velocity is high, the mold powder is scraped off by the molten steel surface flow, and the mixing of the mold powder due to this is likely to occur.
In the case of the pattern C, the meniscus fluctuates and disturbs due to the rising flow of molten steel near the immersion nozzle and the floating large Ar gas bubbles, mixing of mold powder occurs, and the surface velocity of the molten steel is high. In this case, a vertical vortex is generated in the vicinity of the short side of the mold, which causes the mixing of the mold powder. On the other hand, in the case of pattern B,
This is because no vortex is generated in the meniscus and no strong surface flow is generated, and the flow condition is such that mold powder is hardly involved.

As described above, by setting the flow pattern of the molten steel in the mold to the pattern B, it is possible to prevent a decrease in the quality of the slab, to reduce a product downgrade rate, and to improve a slab cleanup rate. . However, as described above, even if the casting conditions are the same, the flow pattern of the molten steel in the mold changes during casting. If the flow pattern can be detected during casting, if the flow pattern deviates from the predetermined flow pattern, the intensity of the applied magnetic field can be changed to return to the predetermined flow pattern.

The inventors have found that the flow pattern of molten steel in a mold can be detected by measuring the surface temperature of the solidified shell in the mold. That is, the surface temperature of the solidified shell near the meniscus of the mold increases at a position corresponding to the upward flow of the molten steel, and the position of the high surface temperature changes in accordance with the change in the flow pattern. For example, in the case of the pattern A, an upward flow is formed near the short side of the mold, so that the surface temperature near the short side of the mold increases. This is because the discharge flow has a higher temperature than the molten steel in the mold, so at the position where the discharge flow rises, the temperature of the molten steel rises and the flow of molten steel promotes heat transfer, increasing the amount of heat transmitted to the solidified shell and increasing the surface temperature. This is because the temperature increases.

However, the surface temperature of the solidified shell does not change only due to the influence of the flow of molten steel, but also changes depending on the state of contact between the mold and the solidified shell, the state of inflow of the mold powder, and the like. Therefore, if the molten steel flow is simply detected from the distribution of the absolute value of the solidified shell surface temperature in the slab width direction, it may be detected erroneously. That is, an accurate flow pattern cannot be detected unless the influence on the surface temperature of the solidified shell due to factors other than the flow of molten steel is removed.

The inventor of the present invention uses the time-dependent change of the temperature at each measurement point for measuring the surface temperature, that is, the rate of temperature rise or fall every certain time as an index, to obtain solidification caused by factors other than the flow of molten steel. It has been found that the influence on the shell surface temperature can be minimized and an accurate flow pattern can be detected. This is because the change in the surface temperature of the solidified shell due to factors other than the flow of molten steel occurs relatively slowly.

At this time, the distribution of the measurement points where the surface temperature rises and the measurement points where the surface temperature falls is determined, and if the flow pattern is detected based on the distribution of the measurement points that rise and / or the distribution of the measurement points that fall, the further increase in It turned out that it can be detected accurately.
This is because when the flow pattern changes, the surface temperature of the solidified shell changes with a distribution.

As the magnetic field applied to the discharge flow, it is preferable to use a moving magnetic field in which the magnetic field moves in the horizontal direction. In the moving magnetic field, by selecting and applying an appropriate magnetic field strength,
This is because the molten steel flow velocity and the flow pattern can be freely controlled as compared with the static magnetic field generated by the direct current.

For the measurement of the surface temperature of the solidified shell, it is preferable to use a plurality of optical fibers penetrating the copper plate on the long side of the mold and an optical thermometer connected to the optical fibers. Since the surface of the solidified shell can be directly measured by the optical fiber, the accurate surface temperature can be continuously measured.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.
FIG. 3 is a schematic view of a front section of a continuous casting machine mold part showing one embodiment of the present invention, and FIG. 4 is a schematic view of a side section.

Referring to FIGS. 3 and 4, a tundish 6 is disposed above a mold 1 composed of opposed mold long sides 2 and opposed mold short sides 3 provided inside the mold long sides 2. ing. At the bottom of the tundish 6 is a fixing plate 2
0, a sliding plate 21, and a rectifying nozzle 22, and a submerged nozzle 8 is disposed on the lower surface side of the sliding nozzle 7, and a molten steel outflow hole 26 from the tundish 6 to the mold 1 is provided. Is formed.
The molten steel 4 injected into the tundish 6 from a ladle (not shown) is provided at the lower part of the immersion nozzle 8 via the molten steel outflow hole 26, and the discharge hole 9 immersed in the molten steel 4 in the mold 1. Thus, the discharge flow 10 is injected into the mold 1 toward the short side 3 of the mold. Then, the molten steel 4 is cooled in the mold 1 to form a solidified shell 5, and is drawn out below the mold 1 to become a cast slab.

The molten steel outflow hole 26 of the fixing plate 20 is provided with a porous brick 23 fitted therein.
Ar gas is blown into the molten steel outflow hole 26 from the porous brick 23 in order to prevent Al ₂ O _{3 from} adhering to the wall surface of the steel. The blown Ar gas passes through the immersion nozzle 8 together with the molten steel 4 and flows into the mold 1 through the discharge hole 9.
It floats on the meniscus 13 through the molten steel 4 inside, penetrates the mold powder 14 added on the meniscus 13, and reaches the atmosphere.

On the back side of the mold long side 2, a magnetic field generator 11 and a magnetic field generator 12 divided into two parts on the left and right sides in the width direction of the mold long side 2 with the immersion nozzle 8 as a boundary, are provided.
The center positions 1 and 12 in the casting direction are defined as a range between the lower end position of the discharge hole 9 and the lower end position of the mold 1, and are arranged to face each other across the long side 2 of the mold. The magnetic field generators 11 and 12
Are connected to the magnetic field power supply control device 19, and the intensity of the magnetic field applied by the magnetic field power supply control device 19 is individually controlled.
The magnetic field strength of the magnetic field generators 11 and 12 may be the one which is generally used industrially with a maximum magnetic field strength of about 0.2 Tesla to 0.4 Tesla.

The magnetic field applied from the magnetic field generators 11 and 12 may be a static magnetic field by a direct current, but is preferably a moving magnetic field in which the magnetic field moves in the horizontal direction as described above. In the case of a moving magnetic field, not only the magnetic field strength but also the moving direction of the magnetic field can be individually controlled, so that the flow control is further facilitated. In the moving magnetic field, the direction of movement of the moving magnetic field is from the mold short side 3 side to the immersion nozzle 8 side, so that the discharge flow 10 is decelerated, and conversely, the movement direction is from the immersion nozzle 8 side to the mold short side 3 side. Thus, the discharge flow 10 is accelerated. In the case of a moving magnetic field, it is not necessary to oppose the magnetic field generators 11 and 12 with the long side 2 of the mold interposed therebetween, and the discharge flow 10 can be controlled simply by arranging it on the back side of one long side 2 of the mold. However, in the case where the magnetic field strength is reduced only on one back surface, a moving magnetic field generator having a high magnetic field strength must be provided.

A plurality of through holes are provided in the copper plate on the long side 2 of the mold in the width direction of the long side 2 of the mold to serve as measurement points 15 for measuring the surface temperature of the solidified shell 5 in the mold 1. Each measurement point 1
In 5, an optical fiber 16, the other end of which is connected to a thermometer main body 17, is disposed so as to substantially abut the solidified shell 5, and a signal received by the optical fiber 16 is converted into a temperature by the thermometer main body 17. The measuring points 15 are arranged side by side in the horizontal direction, and the distance between the measuring points 15 is preferably 200 mm or less, and the distance from the meniscus 13 is preferably 300 mm or less. If the distance between the measurement points 15 exceeds 200 mm, the number of the measurement points 15 is too small to make the detection of the flow pattern inaccurate, and the distance from the meniscus 13 is 300 mm.
When the temperature exceeds the above, the surface temperature of the solidified shell 5 is affected by the discharge flow 10 flowing in the horizontal direction, and similarly, the detection of the flow pattern becomes inaccurate.

The surface temperature measured by the thermometer main body 17 is sent to a data analyzer 18 to analyze the rate of rise and fall of the surface temperature at each measurement point 15. At the same time, the distribution of the measurement points 15 with similar surface temperature changes in the width direction of the mold long side 2 is analyzed. Then, based on these analysis data, the data analyzer 18 detects the flow pattern of the molten steel in the mold 1 and sends a signal of the detected flow pattern to the magnetic field power supply controller 19. The magnetic field power supply control device 19 controls the magnetic field generation device 1 based on the transmitted flow pattern signal.
The intensity of the magnetic field applied from 1 and 12 is individually controlled, and the flow pattern is controlled to become the pattern B. The adjustment of the magnetic field strength is performed by increasing or decreasing the current supplied to the magnetic field generators 11 and 12. In the case of a moving magnetic field (using an AC power supply), the intensity of the magnetic field can be adjusted by changing the frequency of the current. The control method of the flow pattern is as follows: when the pattern A is reached, the magnetic field strength is increased to decelerate the discharge flow 10, and when the pattern C is reached, the magnetic field intensity is decreased or accelerated to discharge. If the speed of the stream 10 is increased, both patterns can be set to the pattern B. Before starting the casting, the discharge angle and cross-sectional area of the discharge hole 9 of the immersion nozzle 8, the immersion depth of the immersion nozzle 8, the mold 1 of the molten steel 4 per unit time,
Casting is started by appropriately selecting casting conditions such as an injection amount into the inside, an applied magnetic field intensity, and an Ar gas blowing amount, and setting a molten steel flow pattern in the mold 1 as a pattern B.

In the present embodiment, a refractory rod 24 immersed in the meniscus 13 to a depth of about 100 mm, and a pressure receiving sensor 25 for detecting the force acting on the refractory rod 24
The surface flow velocity was measured from the force acting on the refractory rod 24 by the surface flow of the molten steel 4 at several places of the meniscus 13 to confirm whether the flow pattern had a predetermined pattern. Since the three flow patterns have different surface flow velocity distributions, the flow patterns can be inferred. still,
The refractory rod 24 and the pressure receiving sensor 25 are provided for confirmation, and are not necessarily required for implementing the present invention.

In the above description, the magnetic field generators 11 and 12 are divided in the width direction of the mold long side 2 with the immersion nozzle 8 as a boundary. It can also be implemented with a generator. In that case,
When a moving magnetic field is used, it is necessary to connect the magnetic field power supply control device 19 in advance so that the moving directions of the left and right magnetic fields are opposite to each other with the immersion nozzle 8 as a boundary. However, flow control is slightly more difficult with one magnetic field generator than with the divided magnetic field generators 11 and 12.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the continuous casting machine shown in FIGS. 3 and 4 will be described below.

The slab size is 250 mm in thickness and 1800 in width.
mm, and carbon steel was cast at a drawing speed of 2.5 m / min. The applied magnetic field was a moving magnetic field, and the center of the magnetic field generator in the casting direction was 150 mm from the lower end of the discharge hole. The flow rate of Ar gas into the molten steel outlet is 9 Nl / m.
in. The copper plate on the long side of the mold was provided with through holes through which optical fibers were passed at 50 mm intervals at a position 130 mm from the upper end (at a position 50 mm from the meniscus), and the surface temperature of the solidified shell was measured as a measurement point of the surface temperature.

FIG. 5 shows two measurement points A and B.
5 shows an example of a temperature change. As shown in FIG.₁−Δ
At T, the temperature at point B was higher than the temperature at point A.
Time T ₁The temperature at point A starts to rise immediately before
Temperature begins to fall, and at time T₁A before and after
And the temperature at the two measurement points of point B are reversed,
Later, time T₁At + ΔT, both points A and B remain reversed
Temperature was stable.

FIG. 6 shows the change over time of the temperature at each measurement point of the entire mold long side width before and after the time T ₁ . In FIG. 6, the mark ● represents a measurement point 15 at which there is no temperature change around time T ₁ , the mark ◎ represents a measurement point 15 at which the temperature has risen, and the symbol × represents a measurement point 15 at which the temperature has dropped. As shown in FIG. 6, the measurement points where the temperature has risen are distributed on the short side 3 of the mold, and the measurement points where the temperature has fallen are distributed at an intermediate position between the immersion nozzle 8 and the short side 3 of the mold. It can be seen that the ascending measurement point and the descending measurement point show a characteristic distribution. FIG.
5 also shows two measurement points A and B shown in FIG.

FIG. 7 shows the result of detecting the flow pattern of molten steel in the mold based on the above temperature analysis results. As shown in FIG. 7, at time T ₁ −ΔT, pattern B and time T ₁ +
At ΔT, pattern A was detected.

FIG. 8 shows the measurement at the same time with a refractory rod.
It is a figure which shows the distribution of the surface flow velocity of the molten steel in a casting mold. Time T
₁For -ΔT, the boundary is located at an intermediate position between the immersion nozzle and the short side of the mold.
On the immersion nozzle side, the flow is directed toward the center of the mold.
On the short side of the mold, the flow toward the short side of the mold, that is, the pattern
B was flowing. However, time T₁The table for + ΔT
The surface flow is a flow from the short side of the mold to the center of the mold.
A. Thus, the distribution of surface flow of molten steel
From time T₁At −ΔT, pattern B, time T ₁+ ΔT
Is confirmed as pattern A, and is detected from the surface temperature measurement.
Prove that the pattern is accurate.

Therefore, the current supplied to the magnetic field generator is increased.
To increase the strength of the moving magnetic field on the left and right of the immersion nozzle, and discharge
The flow was slowed down. While continuing casting in this state, the above point A
And the results of measuring the temperature change at two measurement points, point B
The results are shown in FIG. Point A immediately after changing the supplied current
Temperature decreases, the temperature at point B increases, and time T
₁Stabilized in the same state as -ΔT. At the meniscus
Time T of surface flow distribution ₁-T
It was confirmed with a fire rod.

As a result of rolling the slab obtained in this example into a thin steel sheet, the amount of mold powder defects was low,
High yields could be achieved. 6 and 7
Are the same as those in FIGS. 3 and 4.

[0045]

According to the present invention, the flow pattern of molten steel in a continuous casting mold can be accurately detected, and as a result, a predetermined flow pattern can be obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a flow pattern of molten steel in a mold.

FIG. 2 is a diagram illustrating a relationship between a flow pattern of molten steel in a mold and an amount of occurrence of a product defect.

FIG. 3 is a schematic front sectional view of a continuous casting machine mold part showing an example of an embodiment of the present invention.

FIG. 4 is a schematic side cross-sectional view of a mold part showing an example of an embodiment of the present invention.

FIG. 5 is a diagram showing temperature transitions at two measurement points in the example.

FIG. 6 is a diagram showing each measurement point for each time-dependent change in temperature from the results of temperature measurement in Examples.

FIG. 7 is a diagram showing a change in a flow pattern detected from a temperature analysis result in the example.

FIG. 8 is a diagram showing the distribution of the surface flow velocity of molten steel in a mold measured with a refractory rod in an example.

FIG. 9 is a diagram showing temperature transitions at two measurement points after the intensity of the magnetic field is increased in the example.

[Explanation of symbols]

 Reference Signs List 1 mold 2 mold long side 3 mold short side 4 molten steel 5 solidified shell 6 tundish 7 sliding nozzle 8 immersion nozzle 9 discharge hole 10 discharge flow 11 magnetic field generator 12 magnetic field generator 13 meniscus 14 mold powder 15 measurement point 16 optical fiber 17 temperature Main unit 18 Data analyzer 19 Magnetic power supply controller

────────────────────────────────────────────────── ─── Continued on the front page (72) Noriko Kubo, Inventor Nippon Kokan Co., Ltd. 1-2-1, Marunouchi, Chiyoda-ku, Tokyo (56) References JP-A-7-241649 (JP, A) JP-A Sho57 JP-A-81941 (JP, A) JP-A-4-46658 (JP, A) JP-A-6-182511 (JP, A) JP-A-10-272546 (JP, A) JP-A-3-275256 (JP, A) JP-A-57-149052 (JP, A) JP-A-6-23503 (JP, A) JP-A-62-124055 (JP, A) JP-A-8-187557 (JP, A) 206800 (JP, A) JP-A-9-168847 (JP, A) JP-A-62-252650 (JP, A) JP-A-4-2844956 (JP, A) JP-A-10-263777 (JP, A) Patent flat 10-193047 (JP, a) JP flat 10-109145 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ , DB name) B22D 11/16 104 B22D 11/115

Claims (4)

(57) [Claims] When a steel is continuously cast by applying a magnetic field to a discharge flow from an immersion nozzle, the surface temperature of a solidified shell in a slab width direction in a mold is measured at a plurality of points. The flow pattern of the molten steel in the mold is detected from the change over time in the surface temperature, and the direction of the flow of the molten steel in the meniscus is
The immersion nozzle is located near the middle position between the
On the mold side, the flow is toward the center of the mold.
So that the flow pattern becomes a flow toward the short side of the mold ,
A method for controlling the flow of molten steel in a continuous casting mold, wherein the intensity of a magnetic field to be applied is adjusted based on a detection result. 2. The change of the surface temperature of the solidified shell with time,
Determining a distribution of measurement points at which the surface temperature increases and a measurement point at which the surface temperature decreases, and detecting a flow pattern of the molten steel in the mold based on the distribution of the measurement points that increase and / or the distribution of the measurement points that decrease. Item 4. The method for controlling molten steel flow in a continuous casting mold according to Item 1. 3. The method for controlling the flow of molten steel in a continuous casting mold according to claim 1, wherein the applied magnetic field is a moving magnetic field that moves in a horizontal direction. 4. The molten steel in a continuous casting mold according to claim 1, wherein the surface temperature of the solidified shell is measured by a plurality of optical fibers penetrating the copper plate on the long side of the mold. Flow control method.