JP2021087972A - Manufacturing method of thin cast piece - Google Patents

Abstract

To provide a manufacturing method of a thin cast piece, capable of suppressing breakage of a thin cast piece, and stably starting casting in a twin-drum type continuous casting apparatus.SOLUTION: A manufacturing method of a thin cast piece includes: supplying molten metal to a molten metal accumulation part formed by a pair of rotary cooling drums and a pair of side weirs; and forming/growing coagulation shell on peripheral surfaces of the cooling drums so as to manufacture the thin case piece. When measuring a sum load as a total value of reaction force of one end side and reaction force of the other end side in a rotary axis direction of the pair of cooling drums, and performing pressure control of the pair of cooling drums according to a sum load difference as a difference between an actual measured sum load and a target sum load, pressure control of the pair of cooling drums is performed so that the actual measured sum load becomes the target sum load when the sum load difference is equal to or less than a limit value, and the pressure control of the pair of cooling drums is performed by ignoring a portion exceeding the limit value when the sum load difference exceeds the limit value.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a thin-walled slab, which supplies a molten metal to a molten metal reservoir formed by a pair of cooling drums and a pair of side weirs to produce a thin-walled slab.

As a method for producing a thin-walled metal slab, for example, as shown in Patent Documents 1 and 2, a cooling drum having a water-cooled structure inside is provided, and a molten metal reservoir formed between a pair of rotating cooling drums is provided. A molten metal is supplied to form and grow a solidified shell on the peripheral surface of the cooling drum, and the solidified shells formed on the outer peripheral surfaces of the pair of cooling drums are joined at a drum kiss point and reduced to a predetermined thickness. A manufacturing method using a twin-drum type continuous casting apparatus for manufacturing thin-walled slabs is provided. The manufacturing method using such a twin drum type continuous casting apparatus is applied to various metals.

Here, in the above-mentioned twin drum type continuous casting apparatus, in order to produce a thin-walled slab having a uniform thickness in the plate width direction, the rotation axes of the pair of cooling drums are held in parallel with each other. It is necessary to control the pressure.
For example, in Patent Document 1, the pressing forces at both ends of one cooling drum are detected and added, and a signal based on this is used so that the sum of the pressing forces at both ends of one cooling drum becomes a predetermined value. A method has been proposed in which both ends of the cooling drum of the above are moved in parallel by a hydraulic cylinder.

Further, Patent Documents 2 and 3 propose a method of switching the pressure control between the pair of cooling drums immediately after the start of casting and in the steady state.
In Patent Document 2, in the first step from the rotation start of the cooling drum until the thick portion of the thin-walled slab passes through the latest contact (drum kiss point) of the cooling drum, the cooling drum is not controlled in parallel. The pair of cooling drums are pressed in a direction close to each other at a relatively low pressure, and in the second step from after the first step until the influence of shell washing by the discharge flow of molten steel from the nozzle disappears, parallel control of the cooling drums is performed. Instead, the pressing is performed with a pressure higher than that of the first step, and in the third step after the second step, parallel control is performed so that the rotation axes of the pair of cooling drums are parallel to each other.

Further, in Patent Document 3, the thick portion of the thin-walled slab formed when the molten metal is supplied to the molten metal pool portion with the pair of cooling drums stopped at the start of casting is described as described above. In the first step from the start of rotation of the cooling drums to the passage through the recent contacts of the pair of cooling drums, the pair of cooling drums are pressed at a relatively low pressure in the direction in which the pair of cooling drums are close to each other without controlling the parallelism of the cooling drums. In the second step from after the first step until the cooling drum makes one or more rotations, one end side and the other end side of the pair of cooling drums in the rotation axis direction have the same pressure and the first step. At a predetermined pressure (second pressure) higher than the step, the pair of cooling drums press in a direction close to each other, and in the third step after the second step, in the rotation axis direction of the pair of cooling drums. The pressure is controlled so that the total value of the reaction forces on the one end side and the other end side becomes a predetermined value and the rotation axes of the pair of cooling drums are held in parallel with each other. ..

In these Patent Documents 2 and 3, since the pair of cooling drums are simply pressed in the non-stationary state immediately after the start of casting in which the deviation in the thickness of the solidified shells is large, the solidified shells are sufficiently pressed down at the drum kiss point. It is possible to prevent the formation of an unsolidified portion in the central portion of the thickness of the thin-walled slab.

Japanese Unexamined Patent Publication No. 01-166863 Japanese Patent No. 2957040 Japanese Unexamined Patent Publication No. 2018-176251

However, as in the third step of Patent Document 1 and Patent Documents 2 and 3, the sum load, which is the total value of the reaction forces on one end side and the other end side in the rotation axis direction of the pair of cooling drums, is measured and actually measured. Even when the pressure control of the pair of cooling drums is performed according to the sum load difference, which is the difference between the sum load and the target sum load, the thin wall slab breaks during casting depending on the material of the thin wall slab. Could occur.

The present invention has been made in view of the above-mentioned situation, and in a twin-drum type continuous casting apparatus, a thin-walled slab can be produced which can suppress the breakage of the thin-walled slab and can start casting stably. The purpose is to provide a method.

As a result of diligent studies by the present inventors in order to solve the above-mentioned problems, the following findings were obtained.
In the twin-drum type continuous casting device, after the start of casting, as described above, the sum load, which is the total value of the reaction forces on one end side and the other end side in the rotation axis direction of the pair of cooling drums, is measured and actually measured. The pressure control of the pair of cooling drums is performed according to the sum load difference, which is the difference between the sum load and the target sum load.

Here, as shown in FIG. 5A, when the metal M is bitten into the pair of cooling drums 11 and 11, the reaction force temporarily increases significantly and the sum load also increases. Therefore, the pair of cooling drums 11 and 11 are controlled in a direction in which they are separated from each other.
Then, in a state where the bare metal M exists between the cooling drums, as shown in FIG. 5B, a first high temperature region 1a in which the temperature of the thin-walled slab 1 is relatively high is formed.
Then, when the metal M comes out between the cooling drums 11 and 11, the thin-walled slab 1 cannot be sufficiently pressed by the cooling drum 11, and the temperature of the thin-walled slab 1 rises further to the second high temperature. It was found that the region 1b was formed, and the thin-walled slab 1 was broken in the second high temperature region 1b.

The present invention has been made based on the above findings, and the method for producing a thin-walled slab according to the present invention melts in a molten metal reservoir formed by a pair of rotating cooling drums and a pair of side dams. A method for producing a thin-walled slab by supplying metal and forming and growing a solidified shell on the peripheral surface of the cooling drum to produce a thin-walled slab. When the sum load, which is the total value of the reaction forces on the end side, is measured and the pressure control of the pair of cooling drums is performed according to the sum load difference, which is the difference between the measured sum load and the target sum load, the sum is said. When the load difference is equal to or less than the limit value, the pressure of the pair of cooling drums is controlled so that the measured sum load becomes the target sum load, and when the sum load difference exceeds the limit value, the said It is characterized in that the pressure of the pair of cooling drums is controlled ignoring the amount exceeding the limit value.

According to the method for manufacturing a thin-walled slab having this configuration, the sum load, which is the total value of the reaction forces on one end side and the other end side in the rotation axis direction of the pair of cooling drums, is measured, and the actual sum load and the target sum load are measured. When the pressure control of the pair of cooling drums is performed according to the sum load difference, which is the difference between the above and the above, if the sum load difference exceeds the limit value, the amount exceeding the limit value is ignored. Since the pressure of the pair of cooling drums is controlled, for example, even if the reaction force temporarily increases significantly due to the biting of the bare metal and the above-mentioned sum load difference exceeds the limit value, the cooling drums. Is not separated more than necessary, and the thin-walled slab can be sufficiently pressed by the cooling drum to be cooled after the bare metal has passed, and the generation of a local high-temperature region of the thin-walled slab can be suppressed. Therefore, the breakage of the thin-walled slab can be suppressed, and the thin-walled slab can be stably cast.

Here, in the method for producing a thin-walled slab according to the present invention, the limit value of the sum load difference is preferably in the range of 1 kN or more and 8 kN or less per 1 m of the drum width of the cooling drum.
In this case, since the limit value of the sum load difference is 1 kN or more per 1 m of the drum width of the cooling drum, the pressure can be accurately controlled so as to reach the target sum load. At the same time, since the limit value of the sum load difference is 8 kN or less per 1 m of the drum width of the cooling drum, even if the bullion is bitten, the cooling drums do not separate more than necessary, and the ground is not separated. After the gold has passed, the thin-walled slab can be sufficiently pressed by the cooling drum to be cooled. Therefore, the breakage of the thin-walled slab can be further suppressed, and the thin-walled slab can be cast more stably.

Further, in the method for producing a thin-walled slab according to the present invention, the thin-walled slab formed when the molten metal is supplied to the molten metal reservoir with the pair of cooling drums stopped at the start of casting. In the first step from the start of rotation of the cooling drums to the passage of the recent contacts of the pair of cooling drums, one end side and the other end side of the pair of cooling drums in the rotation axis direction are the same. With the pressure of, the pair of cooling drums are pressed toward each other in a direction close to each other, and in the second step from after the first step until the cooling drums make one or two rotations, the pair of cooling drums The pair of cooling drums press the one end side and the other end side in the rotation axis direction at the same pressure and at a pressure higher than that of the first step in a direction close to each other, and the third step after the second step. In the step, the sum load, which is the total value of the reaction forces on one end side and the other end side in the rotation axis direction of the pair of cooling drums, is measured, and according to the sum load difference, which is the difference between the measured sum load and the target sum load. Therefore, the pressure of the pair of cooling drums may be controlled.

In this case, the thick portion of the thin-walled slab formed when the molten metal is supplied to the molten metal pool portion with the pair of cooling drums stopped at the start of casting rotates the cooling drum. Later, in the first step until the cooling drum recently passes through the contact point, the pair of cooling drums are subjected to the same predetermined pressure (first pressure) on one end side and the other end side in the rotation axis direction of the pair of cooling drums. Since the cooling drums are pressed toward each other in a direction close to each other, the thick portion can be passed between the cooling drums relatively stably.
Further, in the second step, since the cooling drum is pressed at a predetermined pressure (second pressure) higher than that in the first step, the solidified shells can be sufficiently reduced at the drum kiss point, and the thin-walled slab can be sufficiently pressed. It is possible to suppress the formation of an unsolidified portion in the central portion of the thickness.

As described above, according to the present invention, it is possible to provide a method for producing a thin-walled slab that can suppress the breakage of the thin-walled slab and can start casting stably in the twin-drum type continuous casting apparatus. It will be possible.

It is explanatory drawing which shows an example of the twin drum type continuous casting apparatus used in the manufacturing method of the thin-walled slab which is an embodiment of this invention. It is a partially enlarged explanatory view of the twin drum type continuous casting apparatus shown in FIG. It is explanatory drawing which shows the pressure control method of the cooling drum in 1st step, 2nd step, and 3rd step. It is a graph which shows the condition of the pressure control of the cooling drum in an Example. It is explanatory drawing which shows the temperature distribution of the thin-walled slab at the time of biting a bullion in the conventional method of manufacturing a thin-walled slab.

Hereinafter, a method for producing a thin-walled slab according to an embodiment of the present invention will be described with reference to the attached drawings. The present invention is not limited to the following embodiments.
Here, in the present embodiment, molten steel is used as the molten metal, and the thin-walled slab 1 made of a steel material is manufactured. Further, in the present embodiment, the width of the thin-walled slab 1 to be manufactured is within the range of 200 mm or more and 1800 mm or less, and the thickness is within the range of 0.8 mm or more and 5 mm or less.

First, the twin-drum type continuous casting apparatus 10 used in the method for producing a thin-walled slab according to the present embodiment will be described.
The twin drum type continuous casting apparatus 10 shown in FIG. 1 is arranged at the widthwise ends of the pair of cooling drums 11 and 11, the pinch rolls 12 and 13 supporting the thin-walled slab 1, and the pair of cooling drums 11 and 11. A tundish 18 that holds the molten steel 3 supplied to the side weir 15 provided, the molten steel pool portion 16 defined by the pair of cooling drums 11, 11 and the side weir 15, and the molten steel from the tundish 18. A dipping nozzle 19 for supplying the molten steel 3 to the pool portion 16 is provided.

In the twin drum type continuous casting apparatus 10, the solidified shells 5 and 5 grow on the peripheral surfaces of the cooling drums 11 and 11 when the molten steel 3 comes into contact with the rotating cooling drums 11 and 11 and is cooled. , The solidified shells 5 and 5 formed on the pair of cooling drums 11 and 11, respectively, are pressure-bonded to each other at the drum kiss point to cast a thin-walled slab 1 having a predetermined thickness.

Here, as shown in FIG. 2, the molten steel pool portion 16 is defined by disposing the side weir 15 on the end surface of the cooling drum 11.
As shown in FIG. 2, the molten metal surface of the molten steel pool portion 16 has a rectangular shape surrounded on all sides by the peripheral surfaces of the pair of cooling drums 11 and 11 and the pair of side weirs 15 and 15. The immersion nozzle 19 is arranged at the center of the hot water surface forming the water.

At the start of casting in the above-mentioned twin drum type continuous casting apparatus 10, a dummy sheet (not shown) is inserted between the cooling drums 11 and 11 with the pair of cooling drums 11 and 11 stopped, and the molten steel pool portion 16 is filled with a dummy sheet (not shown). The molten steel 3 is supplied toward the target.
Then, the cooling drums 11 and 11 are rotationally activated, and the thin-walled slab 1 is pulled out from the lower side of the cooling drums 11 and 11.

At this time, immediately after the start of casting, the molten steel 3 in the molten steel pool portion 16 solidifies, the thickness of the thin-walled slab 1 becomes thicker, and a hump-shaped thickened portion is formed.
Further, in the molten steel pool portion 16, shell washing occurs in which the discharge flow of the molten steel 3 from the immersion nozzle 19 flushes the solidified shell 5. This shell washing does not occur when the height of the molten metal in the molten steel pool portion 16 becomes high.

Therefore, in the present embodiment, the pressure control of the cooling drums 11 and 11 is carried out as follows.

First, from the state where the pair of cooling drums 11 and 11 are stopped, the pair of cooling drums 11 and 11 are rotationally started, and the thick portion of the thin-walled slab 1 is the latest contact (drum kiss point) of the pair of cooling drums 11 and 11. ), As shown in FIG. 3A, the hydraulic cylinders 21A and 21B arranged on one end side and the other end side of the pair of cooling drums 11 and 11 in the rotation axis direction. The pair of cooling drums 11 and 11 are pressed toward each other at a predetermined pressure (first pressure). In the present embodiment, as shown in FIG. 3A, the hydraulic cylinders 21A and 21B are arranged on the cooling drum 11a on the moving side, and the cooling drum 11a on the moving side is moved toward the cooling drum 11b on the fixed side. It is configured to press. The first pressure is aimed at a value as high as possible within a range that does not affect the start-up of the cooling drum 11, but the specific values are mainly the width, diameter, molten metal type, and drum maximum of the cooling drum 11. It is determined by the driving force. In reality, it is difficult to obtain an appropriate value by prior calculation, etc., so an appropriate value is obtained and set in an actual test.

Next, after the first step described above, in the second step until the cooling drums 11 and 11 make one or two rotations, as shown in FIG. 3A, the pair of cooling drums 11 and 11 rotate. The hydraulic cylinders 21A and 21B arranged on one end side and the other end side in the axial direction press the pair of cooling drums 11 and 11 toward each other at a predetermined pressure (second pressure). The second pressure is aimed at a value as high as possible within a range that does not cause damage such as deformation to the surface of the cooling drum 11, but mainly the width, diameter, surface shape, surface material, and molten metal of the cooling drum 11. It is determined by the type, and in reality, it is set by obtaining an appropriate value in an actual test as in the case of the first pressure. Here, the second pressure in the second step is set higher than the first pressure in the first step.

Next, in the third step after the second step, as shown in FIG. 3B, the total value of the reaction forces on one end side and the other end side of the pair of cooling drums 11 and 11 in the rotation axis direction (that is, The pressure is controlled so that the sum load) becomes a predetermined value and the rotation axes of the pair of cooling drums 11 and 11 are held in parallel with each other. Specifically, as shown in FIG. 3B, hydraulic cylinders 21A and 21B are arranged on the cooling drum 11a on the moving side, and load cells 22A and 22B are arranged on the cooling drum 11b on the fixed side. The reaction force signal measured by the load cells 22A and 22B is transmitted to the reaction force control unit 24 so that the reaction force control unit 24 moves forward and backward in the hydraulic cylinders 21A and 21B so that the sum load becomes a predetermined value. Give a command. As a result, the rotation axes of the pair of cooling drums 11 and 11 are held in parallel with each other, and the thin-walled slab 1 having a controlled plate thickness is manufactured. The predetermined value of the sum load is mainly aimed at maintaining the stability of operation within the range satisfying the quality of the thin-walled slab 1, but mainly from the width, diameter, and type of molten metal of the cooling drum 11. It is decided. In reality, as with the first pressure and the second pressure, an appropriate value is obtained and set in an actual test.

Here, in the third step, as described above, the sum load, which is the total value of the reaction forces on one end side and the other end side of the pair of cooling drums 11 and 11 in the rotation axis direction, is measured and combined with the measured sum load. The pressure of the pair of cooling drums 11 and 11 is controlled according to the sum load difference, which is the difference from the target sum load.

At this time, when the bare metal is caught between the pair of cooling drums 11 and 11, the total value (sum load) of the reaction forces on one end side and the other end side of the pair of cooling drums 11 and 11 in the rotation axis direction. ) Increases, and the sum load difference, which is the difference between the measured sum load and the target sum load, increases.
When the pressure of the pair of cooling drums 11 and 11 is controlled according to the increase in the sum load due to the biting of the bullion, the cooling drums 11 and 11 when the bullion comes out between the pair of cooling drums 11 and 11. As a result, the thin-walled slab 1 cannot be sufficiently pressed, and the temperature of the thin-walled slab 1 may rise and break.

Therefore, in the present embodiment, the sum load, which is the total value of the reaction forces on one end side and the other end side of the pair of cooling drums 11 and 11 in the rotation axis direction, is measured, and the difference between the actually measured sum load and the target sum load. When the pressure control of the pair of cooling drums 11 and 11 is performed according to the sum load difference, the limit value of the sum load difference is set, and if the sum load difference is less than or equal to the limit value, the measured sum load is measured. The pressure of the pair of cooling drums 11 and 11 is controlled so that is the target sum load, and when the sum load difference exceeds the limit value, the amount exceeding the limit value is ignored and the pair of cooling is performed. It is configured to control the pressure of the drums 11 and 11.

Here, the limit value of the sum load difference needs to be smaller than the difference between the sum load detection upper limit value and the target sum load and larger than the detection lower limit of the sum load change.
The limit value of the sum load difference is set in order to suppress the pressure control of the cooling drums 11 and 11 against a sudden increase in the sum load such as the biting of the bullion, even within the above range. The upper limit of the limit value of the sum load difference is preferably 8 kN or less per 1 m of the drum width of the cooling drum 11, and more preferably 5 kN or less. On the other hand, in order to control the pressure of the cooling drums 11 and 11 more accurately so as to achieve the target sum load, the lower limit of the limit value of the sum load difference may be set to 1 kN or more per 1 m of the drum width of the cooling drum 11. It is preferably 3 kN or more, and more preferably 3 kN or more.

According to the method for manufacturing the thin-walled slab 1 according to the present embodiment having the above configuration, it is the total value of the reaction forces on one end side and the other end side of the pair of cooling drums 11 and 11 in the rotation axis direction. When the sum-load difference exceeds the limit value when the sum-load is measured and the pressure of the pair of cooling drums 11 and 11 is controlled according to the sum-load difference, which is the difference between the measured sum-load and the target sum-load. Since the pressure of the pair of cooling drums 11 and 11 is controlled ignoring the amount exceeding the limit value, for example, the reaction force temporarily greatly increases due to the biting of the bare metal, and the above-mentioned Even if the sum load difference of the above exceeds the limit value, the pair of cooling drums 11 and 11 will not be separated more than necessary, and the thin-walled slab 1 will be sufficiently separated by the pair of cooling drums 11 and 11 after the bare metal has passed. It can be pressed and cooled, and the local temperature rise of the thin-walled slab 1 can be suppressed. Therefore, the breakage of the thin-walled slab 1 can be suppressed, and stable casting can be performed.

In the present embodiment, when the limit value of the sum load difference is set to 1 kN or more per 1 m of the drum width of the cooling drum 11, the sum load temporarily increases due to a sudden event such as biting of the bullion. However, it is possible to further prevent the pair of cooling drums 11 and 11 from being separated more than necessary, and when the state returns to a steady state, the thin-walled slab 1 can be sufficiently pressed by the pair of cooling drums 11 and 11. This makes it possible to more stably cast the thin-walled slab 1.
Further, in the present embodiment, when the limit value of the sum load difference is set to 8 kN or less per 1 m of the drum width of the cooling drum 11, the pressure control of the pair of cooling drums 11 and 11 can be performed more accurately. Casting of the thin-walled slab 1 can be performed more stably.

Further, in the present embodiment, the pair of cooling drums 11 and 11 are rotated and started from the state where the pair of cooling drums 11 and 11 are stopped, and the thick portion of the thin-walled slab 1 is formed by the pair of cooling drums 11 and 11. In the first step until the contact (drum kiss point) is passed recently, the hydraulic cylinders 21A and 21B arranged on one end side and the other end side of the pair of cooling drums 11 and 11 in the rotation axis direction provide a predetermined pressure ( When the pair of cooling drums 11 and 11 are pressed toward each other by the first pressure), the thick portion of the thin-walled slab 1 is relatively stably passed between the cooling drums 11 and 11. be able to.

Further, in the present embodiment, after the above-mentioned first step, in the second step until the cooling drums 11 and 11 make one or two rotations, one end side of the pair of cooling drums 11 and 11 in the rotation axis direction and The hydraulic cylinders 21A and 21B arranged on the other end side press the pair of cooling drums 11 and 11 toward each other at a predetermined pressure (second pressure) to apply the second pressure in the second step. , When the pressure is set higher than the first pressure in the first step, the solidified shells can be sufficiently reduced at the drum kiss point, and the formation of an unsolidified portion in the central portion of the thickness of the thin-walled slab is suppressed. it can.

Although the method for producing a thin-walled slab according to the embodiment of the present invention has been specifically described above, the present invention is not limited to this, and can be appropriately changed without departing from the technical idea of the invention. is there.
In the present embodiment, the twin drum type continuous casting apparatus shown in FIG. 1 has been described as an example, but the present invention is not limited thereto.
Further, the pressing method of the cooling drum is not limited to the one shown in FIG. 3, and any configuration may be used as long as the pressure control can be performed as shown in the embodiment.

The results of experiments carried out in order to confirm the effects of the present invention will be described below.
Using the twin-drum type continuous casting apparatus shown in FIG. 1, a thin-walled slab made of carbon steel having a carbon content of 0.05 mass% was produced.
Here, the diameter of the cooling drum was set to 600 mm, and the width of the cooling drum was set to 400 mm. Further, the slab thickness of the steady casting was set to 2.0 mm.
Then, as shown in FIG. 4, the first step, the second step, and the third step were set, and the pressure control of the cooling drum was performed by the method described in the column of the embodiment.

In the third step, in Example 1-3 of the present invention, the limit value of the sum load difference (per 1 m of the drum width of the cooling drum) is set as shown in Table 1, and when the sum load difference exceeds the limit value. Performed pressure control of a pair of cooling drums, ignoring the amount exceeding the limit value.
On the other hand, in the comparative example, the pressure control of the pair of cooling drums was performed according to the measured sum load difference without setting the limit value of the sum load difference.

Then, in Examples 1-3 and Comparative Examples of the present invention, the number of times of casting, the number of times thin-walled slabs were broken, the breaking rate, the decrease in reaction force after the bullion was bitten, and the casting situation were evaluated. The evaluation results are shown in Table 1.

In the comparative example in which the pressure of the pair of cooling drums was controlled according to the measured sum load difference without setting the limit value of the sum load difference, the breaking rate was as high as 63%, and stable casting was performed. I couldn't. In addition, the reaction force decreased significantly immediately after the bullion was bitten.
On the other hand, the present invention in which the limit value of the sum load difference is set, and when the sum load difference exceeds the limit value, the pressure of the pair of cooling drums is controlled ignoring the excess of the limit value. In Example 1-3, the breaking rate was low. In Example 1 of the present invention in which the limit value of the sum load difference was set to a relatively large value of 10 kN, there was a slight decrease in the reaction force after the bullion was bitten.

From the above results, according to the thin-walled slab manufacturing method according to the present invention, in the twin-drum type continuous casting apparatus, the thin-walled slab can be suppressed from breaking and the casting can be started stably. It was confirmed that the manufacturing method of

1 Thin-walled slab 3 Molten steel (molten metal)
5 Solidification shell 10 Twin drum type continuous casting equipment 11 Cooling drum 15 Side weir 16 Molten steel pool part (molten metal pool part)

Claims (3)

A thin-walled slab for producing a thin-walled slab by supplying molten metal to a molten metal reservoir formed by a pair of rotating cooling drums and a pair of side dams and forming and growing a solidified shell on the peripheral surface of the cooling drum. It is a manufacturing method of
The sum load, which is the total value of the reaction forces on one end side and the other end side in the rotation axis direction of the pair of cooling drums, is measured, and the sum load difference, which is the difference between the measured sum load and the target sum load, is described. When controlling the pressure of a pair of cooling drums
When the sum load difference is equal to or less than the limit value, the pressure of the pair of cooling drums is controlled so that the measured sum load becomes the target sum load.
A method for producing a thin-walled slab, which comprises controlling the pressure of the pair of cooling drums when the sum load difference exceeds the limit value, ignoring the amount exceeding the limit value. The method for producing a thin-walled slab according to claim 1, wherein the limit value of the sum load difference is within a range of 1 kN or more and 8 kN or less per 1 m of the drum width of the cooling drum. The thick portion of the thin-walled slab formed when the molten metal is supplied to the molten metal reservoir with the pair of cooling drums stopped at the start of casting is formed after the rotation of the cooling drum is started. In the first step until the recent contact of the cooling drums is passed, one end side and the other end side of the pair of cooling drums in the rotation axis direction are pressed at the same pressure so that the pair of cooling drums are close to each other. Press toward
In the second step from after the first step until the cooling drum makes one or two rotations, one end side and the other end side of the pair of cooling drums in the rotation axis direction have the same pressure and the first step. At a pressure higher than one step, the pair of cooling drums press in a direction close to each other,
In the third step after the second step, the sum load, which is the total value of the reaction forces on one end side and the other end side in the rotation axis direction of the pair of cooling drums, is measured, and the actual sum load and the target sum load are combined. The method for producing a thin-walled slab according to claim 1 or 2, wherein the pressure of the pair of cooling drums is controlled according to the difference in sum load.

Images