JP2018061966A - Side seal device, twin roll type continuous casting apparatus, and method for producing thin slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a side seal device of a twin roll type continuous casting apparatus, while suppressing the adhesion of a bullion to side weirs, also capable of preventing the insertion of a molten metal into the sliding boundaries in the side faces of cooling rolls, capable of stably casting a thin slab and suppressing the abrasion of the side weirs to elongate the service life of the side weirs, the twin roll type continuous casting apparatus, and a method for producing a thin slab.SOLUTION: There is provided a side seal device 30 sealing the edge faces of cooling rolls 11 with side weirs 15 in a twin roll type continuous casting apparatus 10, containing: side weir pressing means 32 of pressing the side weirs 15 against the edge faces of the cooling rolls 11; and side weir vibration application means 33 of applying vibration in a direction in which the side weirs 15 are made to close to and separate from the edge faces of the cooling rolls 11.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a side seal device used in a twin roll type continuous casting apparatus for supplying a molten metal to a molten metal pool portion formed by a pair of cooling rolls and a pair of side weirs to produce a thin cast piece, and the side seal. The present invention relates to a twin-roll continuous casting apparatus provided with the apparatus and a method for producing a thin cast slab.

  As a method for producing a thin metal slab, a molten metal pool part is provided with a pair of cooling rolls having a water cooling structure inside and rotating in opposite directions, and formed by a pair of rotating cooling rolls and a pair of side weirs. The molten metal is supplied to the outer peripheral surface of the cooling roll, and solidified shells are formed and grown on the peripheral surface of the cooling roll, and the solidified shells formed on the outer peripheral surfaces of the pair of cooling rolls are pressure-bonded to each other at the roll kiss point. A twin-roll continuous casting apparatus for producing a slab is provided. Such a twin roll type continuous casting apparatus is applied to various metals.

  In the above-described twin roll type continuous casting apparatus, molten metal is continuously supplied from a molten metal container disposed above a cooling roll to a molten metal pool portion through an immersion nozzle. Molten metal is discharged toward the circumferential surface of the cooling roll from an immersion nozzle disposed in the center of the molten metal pool portion, and flows toward the pair of side weirs along the circumferential surface of the cooling roll. On the peripheral surface of the rotating cooling roll, the molten metal solidifies and grows to form a solidified shell, and the solidified shell on the peripheral surface of each cooling roll is pressure-bonded at the kiss point.

  The side weir serving as the side wall of the molten metal pool portion serves to seal and hold the molten metal in sliding contact with the side surface of the rotating cooling roll during casting of the thin cast slab. Here, the side weir is preheated before casting and heated from the outside during casting. However, since the side weir is always in sliding contact with the cooling roll, it is removed from the cooling roll and cooled. When this cooling becomes excessive, the molten metal is solidified on the side weir surface by coming into contact with the side weir at a low temperature, and the resulting solidified layer adheres to the side weir surface and grows. This is called a bullion.

The bare metal generated on the surface of the side dam in this way may grow into a thick wall and then be caught between a pair of cooling rolls and drawn together with a thin cast piece cast on the peripheral surface of the cooling roll. .
When the base metal is drawn together with the thin cast piece between the pair of cooling rolls, the base metal is pressed together with the thin cast piece between the rolls, so that the thickness is locally increased. In addition, when the ingot is bitten between the pair of cooling rolls, the phenomenon that the space between the pair of cooling rolls temporarily increases and becomes thicker over the entire width of the thin cast slab (solidification is delayed in the portion without the ingot). This may cause high temperature (so-called hot band), fluctuations in the thickness of the thin slab, concomitant quality defects such as surface defects, plate breakage, and operational troubles such as hot water leakage.

Therefore, in this twin-roll type continuous casting apparatus, in order to produce a healthy thin plate by uniformly progressing solidification on the peripheral surface of the cooling roll, the generation and growth of a metal bar formed on the side weir surface is prevented. This is one of the most important issues in the process.
Thus, for example, Patent Documents 1 and 2 propose techniques for suppressing the generation of bullion on the side weir surface.

In Patent Document 1, by vibrating the side weir slidably contacted with the end face of the cooling roll, the solidified shell (metal) adhering to the inner surface of the side weir is quickly dropped, and the entrainment in the thin cast slab is suppressed. However, a twin-roll type continuous casting apparatus has been proposed that can stably produce a uniform thin-walled slab without breaking the thin-walled slab. Here, as the vibration direction of the side weir, the up-down direction or the left-right direction along the end surface of the cooling roll is illustrated.
In Patent Document 2, a vibration exciter that vibrates the side weir in the sliding contact surface with the end face of the cooling roll is provided, and the side weir is vibrated during the unsteady state of the casting, and the side weir is vibrated during the steady state period. A method for stopping the vibration has been proposed.

JP-A-60-184450 JP 05-237603 A

  Incidentally, in both Patent Documents 1 and 2, the vibration direction of the side weir is in the sliding surface between the side weir and the end face of the cooling roll, and the end face of the cooling roll and the side weir are always in contact with each other. Heat was inevitable, the temperature of the side weir decreased, and the formation and growth of metal on the surface of the side weir could not be sufficiently suppressed.

  In the present invention, the side surface of the cooling roll is suppressed while suppressing the adhesion of the metal to the side weir, which is one of the most important factors hindering stable casting in the twin-roll continuous casting process with a relatively simple configuration. Prevents the insertion of molten metal into the sliding boundary with the side weir, can stably cast thin-walled slabs, and further suppress the side weir wear and extend the life of the side weir It is an object of the present invention to provide a side seal device, a twin-roll continuous casting device, and a method for producing a thin-walled slab in a continuous twin-roll continuous casting device.

  In order to solve the above problems, a side seal device according to the present invention supplies molten metal to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side weirs via an immersion nozzle, and the cooling In a twin roll type continuous casting apparatus that forms and grows a solidified shell on a peripheral surface of a roll to produce a thin cast piece, a side seal device that seals an end face side of the cooling roll with the side weir, Side dam pressing means that presses the side dam toward the end face of the cooling roll, and side dam vibration applying means that vibrates the side dam in the direction of approaching and separating from the end face of the cooling roll. It is characterized by.

  According to the side seal device having this configuration, the side weir is vibrated in the direction of approaching and separating from the end surface of the cooling roll while ensuring the sealing performance to stably hold the molten metal in the molten metal pool portion. The contact between the side weir and the cooling roll is relaxed, the amount of heat extracted from the side weir to the cooling roll is reduced, the side weir can be maintained at a high temperature, and the generation and growth of metal on the surface of the side weir is suppressed. It becomes possible.

In addition, by vibrating the side weir in the direction of approaching and separating from the end face of the cooling roll, the metal attached to the surface of the side weir can be released into the molten metal pool part, and the metal grows thick. Can be suppressed.
Furthermore, by causing the side weir to vibrate toward and away from the end face of the cooling roll, the sliding contact between the side weir and the end face of the cooling roll is alleviated, and wear of the side weir can be suppressed. Can extend the life of the side weir.

Here, in the side seal device according to the present invention, the side weir vibration applying means may be configured to vibrate the side weir in a direction perpendicular to the end face of the cooling roll.
In this case, the configuration of the side dam vibration applying means becomes relatively simple, and the generation and growth of the bare metal can be reliably suppressed by vibrating the side dam.

In the side seal device of the present invention, the side dam vibration applying means may be configured to vibrate so that the vibration width of the side dam gradually decreases from the upper side to the lower side of the end face of the cooling roll.
In this case, the vibration width can be increased in the vicinity of the molten metal surface of the molten metal pool portion where the metal is likely to be generated due to a decrease in temperature, and the generation and growth of the metal can be suppressed. Further, the molten metal can be reliably held by reducing the vibration width below the end face of the cooling roll where the molten metal head pressure is large and the molten metal is likely to be inserted. Thereby, casting can be performed stably.

  The twin roll continuous casting apparatus according to the present invention supplies molten metal to a molten metal pool formed by a pair of rotating cooling rolls and a pair of side weirs, and forms a solidified shell on the peripheral surface of the cooling roll. A twin-roll continuous casting apparatus for producing a thin-walled slab by growth, characterized in that it comprises the above-described side seal apparatus.

  According to the twin roll type continuous casting apparatus having this configuration, since the above-described side seal device is provided, the generation and growth of the metal on the surface of the side weir can be suppressed, and the molten metal in the molten metal pool portion can be suppressed. Can be reliably held, and the production of a thin cast piece can be performed stably.

  The method for producing a thin cast piece according to the present invention supplies molten metal to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side weirs, and forms a solidified shell on the peripheral surface of the cooling roll. A thin-walled slab manufacturing method for manufacturing a thin-walled slab by applying vibration in a direction in which the side weir is approached and separated from an end surface of the cooling roll using the side seal device described above. It is a feature.

  According to the twin roll type continuous casting apparatus of this configuration, the side weir is vibrated in the direction of approaching and separating from the end face of the cooling roll using the above-described side seal device, so the surface of the side weir The generation and growth of bullion can be suppressed. In addition, since the side weir is pressed against the end face side of the cooling roll by the side weir pressing means, an excessive gap is not generated between the end face of the cooling roll and the side weir due to vibration, and the molten metal in the molten metal pool portion Can be securely held. Therefore, it is possible to stably manufacture the thin cast slab.

  As described above, according to the present invention, the side surface of the cooling roll is suppressed while suppressing the adhesion of the metal to the side weir, which is one of the most important factors hindering stable casting in the twin-roll continuous casting process. Prevents the insertion of molten metal into the sliding boundary with the side weir, can stably cast thin-walled slabs, and further suppress the side weir wear and extend the life of the side weir A side seal device, a twin-roll continuous casting device, and a method for producing a thin-walled slab can be provided.

It is explanatory drawing which shows an example of the twin roll type continuous casting apparatus used for the manufacturing method of the thin cast slab which is embodiment of this invention. It is a partially expanded explanatory view of the twin roll type continuous casting apparatus shown in FIG. It is a cross-sectional explanatory drawing of the molten steel pool part of the twin roll type continuous casting apparatus shown in FIG. It is upper surface explanatory drawing of the twin roll type continuous casting apparatus shown in FIG. It is explanatory drawing of the side seal apparatus provided with the parallel displacement mechanism. It is explanatory drawing of the side seal apparatus provided with the inclination movement mechanism. It is a model figure at the time of examining the limit gap in which insertion of molten steel occurs. It is a graph which shows the relationship between the limit gap in which insertion of molten steel and a molten steel head occur. It is a graph which shows the limit gap in a side seal device provided with a translation mechanism. It is a graph which shows the limit gap in the side seal device provided with the inclination movement mechanism.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following embodiments, the target metal to be cast will be described as steel. In addition, this invention is not limited to the following embodiment.
Here, the thin-walled slab 1 manufactured in this embodiment is a steel material such as carbon steel, Si-containing steel containing Si in a range of 0.6 mass% to 7.0 mass%, and stainless steel. .
Moreover, in this embodiment, the width | variety of the thin cast slab 1 manufactured is set to the range of 200 mm or more and 1800 mm or less, and the thickness is set to the range of 0.8 mm or more and 5 mm or less.

A twin roll type continuous casting apparatus 10 used in the method for manufacturing a thin cast piece according to this embodiment will be described with reference to FIGS. 1 to 6.
A twin-roll continuous casting apparatus 10 shown in FIG. 1 includes a pair of cooling rolls 11, 11, pinch rolls 12, 12, 13, 13 that support the thin cast piece 1, and a pair of cooling rolls 11, 11. A tundish 18 for holding the molten steel 3 supplied to the molten steel pool portion 16 defined by the side weir 15 disposed at the end in the width direction and the pair of cooling rolls 11 and 11 and the side weir; An immersion nozzle 19 for supplying the molten steel 3 from the tundish 18 to the molten steel pool section 16 is provided.

  In this twin roll type continuous casting apparatus 10, the solidified shells 5, 5 grow on the peripheral surfaces of the cooling rolls 11, 11 when the molten steel 3 comes into contact with the rotating cooling rolls 11, 11 and is cooled. The solid cast shells 5, 5 formed on the pair of cooling rolls 11, 11 are pressed against each other at the roll kiss point, thereby casting the thin cast piece 1 having a predetermined thickness.

Here, as shown in FIG. 2, the molten steel pool portion 16 is defined by arranging the side weir 15 on the end face of the cooling roll 11.
As shown in FIGS. 2 and 4, the hot water 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 rolls 11, 11 and the pair of side weirs 15, 15. An immersion nozzle 19 is disposed in the center of the rectangular hot water surface.
Moreover, as shown in FIG. 3, the contact part with the molten steel 3 of the side dam 15 has comprised the substantially inverted triangular shape. When the temperature of the side weir 15 is lowered, a bare metal is generated at this contact portion.

As described above, the side weir 15 has a sealing action that is in sliding contact with the end surface of the cooling roll 11 and prevents leakage of the molten steel 3 from the end of the cooling roll 11.
It is important that the side weir 15 stably holds the molten steel 3 and does not adversely affect the formation of the solidified shell 5 on the peripheral surface of the cooling roll 11. For this reason, as the material constituting the side weir 15, a heat-resistant material having poor reactivity with the molten steel 3 is used. For example, graphite, boron nitride, aluminum nitride, silicon nitride, alumina, silica, etc. Composite materials are used.

Then, as shown in FIG. 4, the side weir 15 is brought into sliding contact with the end face of the cooling roll 11 by the side seal device 30.
The side seal device 30 includes a side dam holder 31 that supports the side dam 15, a pressing mechanism 32 that presses the side dam 15 toward the end face of the cooling roll 11, and the side dam 15 close to the end face of the cooling roll 11. A vibration imparting mechanism 33 that imparts vibration in the separating direction and a heating mechanism (not shown) that heats the side weir 15 are provided.

  As the pressing mechanism 32, for example, an existing pressing device such as a hydraulic cylinder can be used. In this embodiment, as shown in FIG. 4, a hydraulic cylinder is used as the pressing mechanism 32. Note that there may be one hydraulic cylinder or a plurality of hydraulic cylinders.

  As the vibration applying mechanism 33, for example, an existing vibration device such as an electromagnetic induction type or an eccentric motor type can be used. In the present embodiment, as the vibration applying mechanism 33, an eccentric motor type vibration device that rotates the eccentric weight with an electric motor to apply vibration is used. Note that when one eccentric weight is rotated, the applied vibration becomes a rotational motion. Therefore, the two eccentric weights are synchronously rotated in opposite directions, and the vibration is applied only in the horizontal direction.

  Here, as the vibration imparting mechanism 33, as shown in FIG. 5, the side weir 15 is moved in parallel in a direction orthogonal to the end face of the cooling roll 11 and vibrated, and as shown in FIG. It is possible to use an inclined vibration system that vibrates so that the vibration width of the weir 15 gradually decreases from the upper side to the lower side of the end face of the cooling roll 11.

  In the tilt vibration system, as shown in FIG. 6, a support shaft 35 extending in the horizontal direction perpendicular to the axis O is provided below the axis O of the cooling roll 11, and the support shaft 35 is provided with the support shaft 35. The lower end of the side dam holder 31 is supported. For this reason, when vibration is applied by the vibration applying mechanism 33, the side dam holder 31 swings around the support shaft 35 as a fulcrum, and the vibration width of the side dam 15 gradually decreases from the upper side to the lower side of the end surface of the cooling roll 11. It will vibrate with inclination.

In the present embodiment, the vibration applying mechanism 33 vibrates the side weir 15 in the direction in which the side weir 15 approaches and separates from the end face of the cooling roll 11, so that a minute gap D is formed between the end face of the cooling roll 11 and the side weir 15. Will occur.
Here, even when a minute gap D is generated between the end face of the cooling roll 11 and the side weir 15, the gap D is appropriate in order to suppress the insertion of the molten steel 3 and securely hold the molten steel 3. It is necessary to set the vibration width of the vibration applying mechanism 33 so as to be within the range.

Below, the result of having examined the vibration width (gap D) of the side weir 15 is demonstrated.
As shown in FIGS. 7A and 7B, even if a minute gap D is generated between the end face of the cooling roll 11 and the side weir 15, the gap D is caused by the surface tension of the molten steel 3. It is suppressed to be plugged in. However, when the depth of the molten steel pool portion 16 increases, the molten steel 3 is inserted into the gap D by the head pressure.

Plug limit clearance D _L where insertion of the molten steel 3 occurs, the balance of the surface tension σ and head pressure, represented by the formula (1) and (2) below.
ρgH = σ / R (1)
D _L = −2R cos θ (2)
Here, ρ: molten steel density (kg / m ³ ), g: gravitational acceleration (m / s ² ), H: molten steel head (m), σ: surface tension (N / m), D _L : insertion limit gap (M), R: radius of curvature of molten steel surface (m), θ: wetting angle (°) between side weir and molten steel.

From the above formulas (1) and (2), the insertion limit gap _DL is expressed by the following formula (3).
D _L = (− 2σ cos θ / ρg) / H (3)

As the target steel, (3) the gravitational acceleration g = 9.8m / ^{s 2.} In addition, to calculate the limit gap _{D L} plug enter the physical properties of the molten steel in the formula. In addition, each physical property value is a reference value described in “Japan Society for the Promotion of Science 140th Committee, Japan Iron and Steel Institute, 'Handbook of Physico-chemical Properties at High Temperatures', September 1988”. Using.
Molten iron density ρ = 7000 kg / m ^{3 (} see p. 2 of the reference)
Surface tension of molten iron σ = 1.8 N / m (see p.145 of reference)
Wetting angle θ = 130 ° (contact angle of molten iron on alumina, see p. 173 in the reference)

Relationship of the molten steel head and insertion limit clearance _{D L} (unit: mm) are shown in Figure 8. Limit clearance D _L invasion of molten steel 3, as shown in FIG. 8, because it depends on the molten steel head, becomes narrower as the lower. If the vibration width due to the vibration of the side weir 15 is too large, the molten steel 3 is inserted into the gap D between the side weir 15 and the side surface of the cooling roll 11, so the vibration width needs to be suppressed within a predetermined range.

As shown in FIG. 5, in the case of the parallel vibration system in which the side weir 15 is vibrated in parallel with the direction orthogonal to the end face of the cooling roll 11, the molten steel head is the largest in the side weir 15 as shown in FIG. 9. as smaller than would part of the insertion limit clearance D _L, will set the oscillation width.

For example, when a thin steel slab is manufactured using a cooling roll 11 having a diameter of 600 mm and a molten steel pool portion 16 having a molten metal surface height of 45 ° as a central angle of the cooling roll 11, the molten steel head becomes the largest at the roll kiss point. 212 mm (= 300 mm × sin (45 °)).
At this time, as shown in FIG. 9, the gap D where the molten steel 3 is not inserted is a maximum of 0.10 mm.

As shown in FIG. 6, in the case of the inclined vibration method in which the vibration width of the side weir 15 is vibrated so as to gradually decrease from the upper end to the lower end of the cooling roll 11, as shown in FIG. as is smaller than insertion limit the gap D _L in the molten steel head will set the oscillation width.

For example, when a thin steel slab is manufactured using a cooling roll 11 having a diameter of 600 mm and a molten steel pool portion 16 having a molten metal surface height of 45 ° as a central angle of the cooling roll 11, the molten steel head becomes the largest at the roll kiss point. 212 mm (= 300 mm × sin (45 °)).
As an example in which the vibration width is inclined in the vertical direction, the inclined vibration was set under the following conditions. A support shaft 35 is provided at a position 38 mm below the kiss point (250 mm below the molten metal surface as a reference), and the side weir 15 is vibrated so that the amplitude at the molten metal surface position is 0.30 mm as a rotational movement around this. The relationship between the molten steel head and the gap D at this time is shown in FIG.

The side weir 15 vibrates in a direction approaching and separating from the side surface of the cooling roll 11, but the vibration width at a depth of 0 mm (water surface) position is 0.30 mm, whereas the depth is 50 mm. The vibration width at the position is 0.24 mm, the vibration width at the depth 100 mm position is 0.18 mm, and the vibration width at the depth 200 mm position is 0.08 mm. Thus, as shown in FIG. 10, it becomes smaller than the insertion limit the gap D _L in each of the molten steel head, so that the insertion of the molten steel 3 can be suppressed.

Further, the frequency of vibration when the side weir 15 is vibrated in the direction of approaching and separating from the end face of the cooling roll 11 is desirably in the range of 5 to 200 Hz, and particularly in the range of 10 to 120 Hz. More preferred. If the vibration frequency is less than 10 Hz, the time during which the side weir 15 approaches the end face of the cooling roll 11 during vibration becomes longer, and adhesion of the metal on the surface of the side weir 15 begins to occur. When the vibration frequency becomes higher than 120 Hz, a small vibration mechanism cannot obtain a sufficient vibration width, and a large vibration mechanism having a strong vibration capacity is required to obtain a necessary vibration width, which causes an excessive amount of equipment. This is to cause an increase in size.
The vibration acceleration when evaluating the vibration acceleration on the basis of the gravitational acceleration (9.8 m / s ² ) is desirably 10 G or less in order to avoid an increase in the size of the excitation mechanism. The vibration acceleration is obtained by the following equation (4) derived from the simple vibration equation.
Vibration acceleration [G] = (1/2 g) × (vibration width [μm] × 10 ⁻⁶ ) × {2π × (frequency [Hz])} ²
= 2.01 × 10 ⁻⁶ × (vibration width [μm]) × (frequency [Hz]) ² (4)
For example, the vibration acceleration for obtaining a simple vibration with a vibration width of 100 μm and a vibration frequency of 200 Hz is about 8.0 G, and the vibration acceleration for obtaining a simple vibration with a vibration width of 300 μm and a vibration frequency of 120 Hz is about 8.7 G.

  According to the present embodiment configured as described above, the side weir 15 is closely spaced from the end surface of the cooling roll 11 while ensuring the sealing performance to stably hold the molten steel 3 in the molten steel pool portion 16. Since the contact between the side weir 15 and the cooling roll 11 is relaxed by oscillating in the direction in which the heat is generated, the amount of heat removed from the side weir 15 to the cooling roll 11 is reduced, and the side weir 15 can be maintained at a high temperature. In addition, it is possible to suppress the generation and growth of bullion on the surface of the side weir 15.

In addition, the vibration applying mechanism 33 causes the side weir 15 to vibrate in a direction in which the side weir 15 approaches and separates from the end surface of the cooling roll 11, thereby releasing the metal attached to the surface of the side weir 15 into the molten steel pool portion 16. It is possible to suppress the bullion from growing thick.
Furthermore, by causing the side weir 15 to vibrate in the direction of approaching and separating from the end face of the cooling roll 11, sliding contact between the side weir 15 and the end face of the cooling roll 11 is alleviated, and wear of the side weir 15 is suppressed. And the life of the side weir 15 can be extended.

  In the present embodiment, as shown in FIG. 5, when the parallel vibration method is used in which the side weir 15 is vibrated in a direction perpendicular to the end surface of the cooling roll 11, the configuration of the vibration applying mechanism 33 is relatively long. It becomes simple and the side dam 15 can be vibrated to reliably suppress the generation and growth of the metal.

  Further, in the present embodiment, as shown in FIG. 6, in the case of the inclined vibration method in which the vibration width of the side weir 15 is vibrated so as to gradually decrease from the upper end to the lower end of the cooling roll 11, The vibration width can be increased in the vicinity of the molten metal surface of the molten steel pool portion 16 where gold is likely to be generated, and generation and growth of the metal can be suppressed. Moreover, since the head pressure of the molten steel 3 becomes large below the end face of the cooling roll 11, the molten steel 3 can be reliably sealed by reducing the vibration width.

As mentioned above, although the manufacturing method of the thin cast slab which is this embodiment which is embodiment of this invention was demonstrated concretely, this invention is not limited to this, The range which does not deviate from the technical idea of the invention It can be changed as appropriate.
For example, in the present embodiment, as shown in FIG. 1, a twin roll type continuous casting apparatus provided with pinch rolls has been described as an example. However, the arrangement of these rolls and the like is not limited, and the design may be changed as appropriate. May be.

  In the following, the results of experiments conducted to confirm the effects of the present invention will be described.

  A thin cast piece having a thickness of 2 mm was cast at a cooling roll diameter of 600 mm, a cooling roll width of 800 mm, a molten steel depth of 212 mm in the molten steel pool, and a cooling roll peripheral speed of 50 m / min. The composition of this thin cast slab is 0.05% C, 0.6% Si, 1.5% Mn, 0.03% Al, balance Fe and impurities in mass%. The liquidus temperature of the steel having this composition was 1517 ° C., and the molten steel temperature poured into the molten steel pool portion so that the superheat degree was 30 to 50 ° C. was 1547 to 1567 ° C.

(Invention Example 1)
The side weir was slidably contacted with the side surface of the cooling roll with a preheating temperature of 1250 ° C. and a pressing force of a pressing mechanism (hydraulic cylinder) of 3 kN. Then, as shown in FIG. 5, the side weir was vibrated in the direction of approaching and separating from the end surface of the cooling roll by a parallel vibration method in which the side weir was vibrated in parallel to the direction orthogonal to the end surface of the cooling roll. . The frequency at this time was 50 Hz, and the vibration width was 100 μm. The vibration acceleration is about 0.5G.

(Invention Example 2)
The side weir was slidably contacted with the side surface of the cooling roll with a preheating temperature of 1250 ° C. and a pressing force of a pressing mechanism (hydraulic cylinder) of 3 kN. Then, as shown in FIG. 6, the side weir is moved close to and away from the end surface of the cooling roll by an inclined vibration method that vibrates so that the vibration width of the side weir gradually decreases from above the end surface of the cooling roll. Vibrating in the direction of Specifically, vibrations were applied to the side weirs by rotational movement around a support shaft provided 38 mm below the roll kiss point. The frequency at this time was 100 Hz. The vibration width was 0.30 mm at the hot water surface position and 0.05 mm at the roll kiss point. The vibration acceleration at the molten metal surface position is about 6.0G.

(Invention Example 3)
The side weir was slidably contacted with the side surface of the cooling roll with a preheating temperature of 1100 ° C. and a pressing force by a pressing mechanism (hydraulic cylinder) of 3 kN. Then, as shown in FIG. 6, the side weir is moved close to and away from the end surface of the cooling roll by an inclined vibration method that vibrates so that the vibration width of the side weir gradually decreases from above the end surface of the cooling roll. Vibrating in the direction of Specifically, vibrations were applied to the side weirs by rotational movement around a support shaft provided 38 mm below the roll kiss point. The frequency at this time was 50 Hz. The vibration width was 0.30 mm at the hot water surface position and 0.05 mm at the roll kiss point. The vibration acceleration at the molten metal surface position is about 1.5G.

(Conventional example)
The side weir was slidably contacted with the side surface of the cooling roll with a preheating temperature of 1250 ° C. and a pressing force of a pressing mechanism (hydraulic cylinder) of 3 kN. In addition, vibration was not provided with respect to the side weir.

In Invention Examples 1 and 2, it was possible to stably cast the thin-walled slab without confirming the generation of a bare metal even after 18 minutes had elapsed from the beginning of casting and the end of casting.
Further, in Invention Example 3, as in Invention Examples 1 and 2, stable metal casting could be confirmed without the generation of metal during casting. By adopting the tilt vibration system, it is possible to suppress the generation and growth of bullion even if the preheating temperature is lowered.

  On the other hand, in the conventional example, the ingot was bitten 15 seconds after the start of casting, and the intrusion of the ingot was also confirmed in the thin cast piece. In addition, after 5 minutes from the start of casting, the ingot was bitten. At this time, the slab thickness of 2 mm usually increased locally, reached a maximum of 3.1 mm, and the uniform shape was damaged. It was estimated that the solid metal was formed by rolling the solidified layer formed on the side weir surface between the rolls together with the thin slab.

  From the above results, according to the present invention, it was confirmed that the generation and growth of the metal on the surface of the side weir can be suppressed.

DESCRIPTION OF SYMBOLS 1 Thin wall slab 3 Molten steel 5 Solidified shell 11 Cooling roll 15 Side dam 16 Molten steel pool part (molten metal pool part)
30 Side seal device 32 Pressing mechanism (side dam pressing means)
33 Vibration imparting mechanism (side weir vibration imparting means)

Claims (5)

A molten metal is supplied to a molten metal pool portion formed by a pair of rotating cooling rolls and a pair of side weirs via an immersion nozzle, and a solidified shell is formed and grown on the peripheral surface of the cooling roll, thereby forming a thin cast slab. In the twin roll type continuous casting apparatus for manufacturing the side roll device, the end surface side of the cooling roll is sealed with the side weir,
Side dam pressing means that presses the side dam toward the end face of the cooling roll; and side dam vibration applying means that vibrates the side dam in the direction of approaching and separating from the end face of the cooling roll. A side seal device characterized by that.   2. The side seal device according to claim 1, wherein the side dam vibration applying unit vibrates the side dam in parallel with a direction orthogonal to an end face of the cooling roll.   2. The side seal device according to claim 1, wherein the side dam vibration applying unit vibrates the side dam so that the vibration width of the side dam gradually decreases from the upper side to the lower side of the end face of the cooling roll. A twin-roll type that supplies a molten metal to a molten metal pool formed by a pair of rotating cooling rolls and a pair of side weirs, and forms and grows a solidified shell on the peripheral surface of the cooling roll to produce a thin cast slab. A continuous casting device,
A twin roll continuous casting apparatus comprising the side seal device according to any one of claims 1 to 3. A thin slab for supplying a molten metal to a molten metal pool formed by a pair of rotating cooling rolls and a pair of side weirs, and forming and growing a solidified shell on the peripheral surface of the cooling roll to produce a thin slab A manufacturing method of
A thin cast slab characterized by using the side seal device according to any one of claims 1 to 3 to vibrate the side weir in a direction to approach and separate from an end face of the cooling roll. Manufacturing method.

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