Continuous casting equipment for casting piece and continuous casting method for casting piece

Abstract

The invention provides continuous casting equipment for a cast piece, which can restrain collision of cooling water sprayed from spray nozzles adjacent to each other in the width direction of the cast piece and restrain collapse of a film boiling state. A continuous casting facility (1) for a cast piece is provided with a cooling facility (3) for water-cooling the cast piece (S), the cooling facility (3) having two or more cooling water nozzles (32) arranged in the width direction of the cast piece (S), and the two or more cooling water nozzles (32) are arranged such that spray spraying surfaces of adjacent cooling water nozzles (32) in the width direction of the cast piece (S) do not overlap.

Description

Technical Field

[0001] The invention relates to continuous casting equipment and a continuous casting method for cast sheets. Background Art

[0002] In the continuous casting process of steel, the molten steel poured into the mold is cooled, and the cast piece drawn out is conveyed while being cooled at the output side of the mold, thereby continuously producing the cast piece. Furthermore, the cast piece is cut into a predetermined length to produce a slab, an ingot, or a billet as a raw material for rolling.

[0003] The cast piece pulled out from the mold contains unsolidified molten steel inside. The unsolidified molten steel solidifies to the center by cooling on the mold outlet side, but the properties and quality of the cast piece vary according to its solidification rate. Therefore, cooling on the mold outlet side (hereinafter referred to as secondary cooling) becomes a process that determines the properties and quality of the cast piece.

[0004] In addition, in recent years, the properties and uniformity required of steel materials have become increasingly stringent. Along with this, the quality requirements for slabs, ingots and billets have also become higher year by year, requiring high-quality cast pieces with full length and width. Therefore, in the continuous casting process, especially in the secondary cooling, it is more important than ever to cool the entire width of the cast piece uniformly.

[0005] Figure 1 It is a graph showing the relationship between the surface temperature of the cast piece during the water cooling process of the cast piece and each boiling state. Figure 1 As shown, in the initial stage of water cooling, the cast sheet is cooled in a film boiling state in which a steam film exists between the cast sheet and the water. In the film boiling state, the water and the cast sheet are not in direct contact, so the heat transfer rate, which is an indicator of cooling capacity, is low, and the surface temperature of the cast sheet also decreases slowly. However, if the surface temperature of the cast sheet reaches about 700°C, it is difficult to maintain the steam film between the water and the cast sheet, and the cast sheet is cooled in a transition boiling state in which the water is partially in contact with the cast sheet. When contact between the water and the cast sheet occurs, the flow of water near the cast sheet becomes violent due to the evaporation of the water in contact with the cast sheet, so the heat transfer rate rises sharply and the surface temperature of the cast sheet drops sharply. Afterwards, while maintaining a high heat transfer rate, it is transformed into a nucleate boiling state in which the contact between the cast sheet and the water is stably generated, and the surface temperature of the cast sheet drops sharply to about the water temperature.

[0006] Generally, the higher the temperature of the object being cooled, the more difficult it is to transform into a nucleate boiling state, and the more cooling water is required for the transformation, the higher the manufacturing cost. In addition, if a high-temperature object is cooled in a nucleate boiling state with a strong cooling capacity, large thermal stress is applied to the surface and interior of the object, and the risk of defects such as cracks increases. Therefore, in the secondary cooling of the continuous casting process where the surface temperature of the cast piece is high temperature, the casting piece is usually cooled in a film boiling state with a steam film between the cast piece and the water.

[0007] In view of the above, it can be said that it is preferable to maintain the film boiling state over the entire width in the secondary cooling of the continuous casting process. This is because when the steam film partially or entirely collapses, it shifts to the nucleate boiling state with strong cooling capacity, and the temperature difference between the film boiling state and the nucleate boiling state increases, or the cooling rate becomes too large, so it is impossible to produce a cast sheet that maintains high quality uniformly over the entire width.

[0008] As the causes of the collapse of the film boiling state, the increase of the local water density, the stagnation of cooling water on the upper surface of the cast piece, and the collision of cooling water sprayed from adjacent sprays are considered. In the past, attempts have been made to avoid the above causes and maintain the film boiling state in order to cast a cast piece with uniform quality over the entire width.

[0009] The increase in local water density can be dealt with by improving the tip of the nozzle for spraying cooling water to make the distribution of cooling water sprayed onto the casting flat. In addition, it is also effective to suppress the local concentration of cooling water by using a nozzle with a small aspect ratio of the spray spray surface and a large spray area. Here, when the spray spray surface is a rectangle, the ratio of the short side to its long side is called the aspect ratio, and when the spray spray surface is an ellipse, the ratio of the short axis to its long axis is called the aspect ratio. In addition, when the spray spray surface is a square or a circle, the aspect ratio is 1.

[0010] As a technique for preventing the retention of cooling water on the cast sheet, Patent Document 1 discloses the following technique: by spraying cooling water with the central axis of the spray tilted relative to the central axis of the nozzle, the cooling water retained between the roller pairs supporting and conveying the cast sheet can be efficiently discharged to the outside of the area, thereby maintaining the film boiling state. As a technique for preventing the collision of cooling water, Patent Document 2 discloses the following technique: by spraying cooling water with the long axis of the spray spray surface tilted at an angle θ of 5° or more and less than 45° relative to the width direction of the cast sheet, the collision of cooling water from adjacent sprays can be avoided, thereby maintaining the film boiling state.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: International Publication No. 2018 / 101287

[0014] Patent Document 2: Japanese Patent Application Publication No. 2009-255127 Summary of the invention

[0015] Problems to be solved by the invention

[0016] The purpose of the technology disclosed in Patent Document 1 is to prevent the retained water from flowing down to the downstream side of the vertical belt and the curved belt in a continuous casting device having a vertical belt and a curved belt. The technology disclosed in Patent Document 1 is insufficient to remove the cooling water retained on the cast sheet in the horizontal belt where the surface temperature of the cast sheet decreases and the film boiling state is easily collapsed. In addition, in the vertical belt and the curved belt, when the cooling water is only sprayed upward to prevent it from flowing down to the downstream side, the water is retained between the roller pairs, and the temperature deviation in the width direction is expanded. Therefore, in the vertical belt and the curved belt, a technology is also needed to smoothly discharge the cooling water sprayed on the cast sheet to the outside of the width of the cast sheet.

[0017] In addition, even when the technology disclosed in Patent Document 2 is used, when a low aspect ratio spray is used that is effective for dispersing the water volume distribution and maintaining the film boiling state, there is a case where the cooling water sprayed from adjacent nozzles collides. In addition, even when a spray nozzle with a high aspect ratio is used, when the distance between the spray nozzles is short, the cooling water collides, thereby promoting the collapse of the film boiling state.

[0018] The present invention is completed in view of the above-mentioned problems, and its purpose is to provide a continuous casting device and a continuous casting method for cast sheets, which can suppress the collision of cooling water sprayed from adjacent spray nozzles in the width direction of the cast sheet and suppress the collapse of the film boiling state.

[0019] Means for solving problems

[0020] Means for solving the above-mentioned problems are as follows.

[0021] [1] A continuous casting device for cast slabs, comprising a cooling device for water-cooling the cast slabs, wherein the cooling device has two or more cooling water nozzles arranged along the width direction of the cast slab, and the two or more cooling water nozzles are arranged in a manner so that the spray injection surfaces of adjacent cooling water nozzles in the width direction of the cast slab do not overlap.

[0022] [2] The continuous casting equipment for cast slabs according to [1], wherein the spray injection surface of the cooling water nozzle is rectangular or elliptical, and the two or more cooling water nozzles are respectively arranged within a range that satisfies the following formula (1).

[0023] [Formula 1]

[0024]

[0025] In the above formula (1), L is the installation distance (m) of the above cooling water nozzles, θ 1 is the angle (°) between the long side direction or the long axis direction of the spray injection surface and the width direction, t 1 It is the length (m) of the short side or short axis of the above-mentioned spray injection surface.

[0026] [3] The continuous casting equipment for cast slabs according to [1], wherein the spray injection surface of the cooling water nozzle is square, and the two or more cooling water nozzles are respectively arranged within a range that satisfies the following formula (2).

[0027] L×sinθ 2 >t···(2)

[0028] In the above formula (2), L is the installation distance (m) of the above cooling water nozzles, θ 2 is an angle (°) of one side of the spray injection surface relative to the width direction, one side of the spray injection surface is a side closest to an adjacent spray injection surface among the sides of the spray injection surface, and t is a length (m) of the one side.

[0029] [4] The continuous casting equipment for cast slabs according to [1], wherein the spray injection surface of the cooling water nozzle is circular, and the two or more cooling water nozzles are respectively arranged within a range that satisfies the following formula (3).

[0030] L>D···(3)

[0031] In the above formula (3), L is the installation pitch (m) of the above cooling water nozzles, and D is the diameter (m) of the above spray injection surface.

[0032] [5] The continuous casting equipment for cast slabs according to [2], wherein the aspect ratio of the spray injection surface is 100 or less.

[0033] [6] The continuous casting equipment for cast pieces according to any one of [1] to [5], wherein the surface cooling rate of the cast piece in the cooling equipment is within the range of 0.3°C / second (sec) to 100°C / second.

[0034] [7] The continuous casting equipment for cast pieces according to any one of [1] to [6], wherein the continuous casting equipment for cast pieces comprises a control device for controlling the amount of cooling water sprayed from the cooling water nozzle and the conveying speed of the cast pieces.

[0035] [8] A method for continuous casting of a slab, comprising a cooling step for water-cooling the slab, wherein in the cooling step, cooling water is sprayed from two or more cooling water nozzles arranged along the width direction of the slab to cool the slab, and the two or more cooling water nozzles are arranged in a manner such that the spray injection surfaces of adjacent cooling water nozzles in the width direction of the slab do not overlap.

[0036] [9] The continuous casting method of a cast slab according to [8], wherein the spray injection surface of the cooling water nozzle is rectangular or elliptical, and the two or more cooling water nozzles are respectively arranged within a range that satisfies the following formula (1).

[0037] [Formula 2]

[0038]

[0039] In the above formula (1), L is the installation distance (m) of the above cooling water nozzles, θ 1 is the angle (°) between the long side direction or the long axis direction of the spray injection surface and the width direction, t 1 It is the length (m) of the short side or short axis of the above-mentioned spray injection surface.

[0040]

[10] The continuous casting method of cast slabs according to [8], wherein the spray injection surface of the cooling water nozzle is square, and the two or more cooling water nozzles are respectively arranged within a range that satisfies the following formula (2).

[0041] L×sinθ 2 >t···(2)

[0042] In the above formula (2), L is the installation distance (m) of the above cooling water nozzles, θ 2 is an angle (°) of one side of the spray injection surface relative to the width direction, one side of the spray injection surface is a side closest to an adjacent spray injection surface among the sides of the spray injection surface, and t is a length (m) of the one side.

[0043]

[11] The continuous casting method of a cast slab according to [8], wherein the spray injection surface of the cooling water nozzle is circular, and the two or more cooling water nozzles are respectively arranged within a range that satisfies the following formula (3).

[0044] L>D···(3)

[0045] In the above formula (3), L is the installation pitch (m) of the above cooling water nozzles, and D is the diameter (m) of the above spray injection surface.

[0046]

[12] The continuous casting method of a slab according to [9], wherein the aspect ratio of the spray injection surface is 100 or less.

[0047]

[13] A continuous casting method for a slab according to any one of [8] to

[12] , wherein a surface cooling rate of the slab in the cooling step is within a range of not less than 0.3°C / sec and not more than 100°C / sec.

[0048]

[14] A continuous casting method for a slab according to any one of [8] to

[13] , wherein at least one of the surface cooling rate of the slab and the temperature drop of the slab in the cooling process is controlled by controlling the amount of cooling water sprayed from the cooling water nozzle and the conveying speed of the slab.

[0049] Effects of the Invention

[0050] According to the present invention, the collision of cooling water sprayed from adjacent spray nozzles in the width direction of the cast piece can be suppressed. Thus, when the cast piece is subjected to secondary cooling, the collapse of the film boiling state can be suppressed, the temperature deviation of the cast piece surface during cooling becomes small, and the cast piece with fewer defects can be continuously cast. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] [ Figure 1 ] Figure 1 This is a graph showing the relationship between the surface temperature of the cast piece during the water cooling process of the cast piece and each boiling state.

[0052] [ Figure 2 ] Figure 2 It is a schematic cross-sectional view of a continuous casting facility of a cast slab as one embodiment of the present invention.

[0053] [ Figure 3 ] Figure 3 This is a diagram showing the spraying surface of cooling water sprayed from the cooling water nozzle on the cast slab S.

[0054] [ Figure 4 ] Figure 4 It is a schematic diagram showing a configuration example of the control device 10 .

[0055] [ Figure 5 ] Figure 5 It is a partial cross-sectional schematic diagram of a continuous casting device for casting slabs with rollers for dewatering.

[0056] [ Figure 6 ] Figure 6 It is a partial cross-sectional schematic diagram of a continuous casting device for casting sheets with a purge nozzle.

[0057] [ Figure 7 ] Figure 7 It is a partial cross-sectional schematic diagram of a continuous casting device for casting sheets with rollers for dewatering and purge nozzles.

[0058] [ Figure 8 ] Figure 8 It is a schematic cross-sectional view showing another example of the continuous casting equipment of the cast slab according to the present embodiment.

[0059] [ Fig. 9 ] Fig. 9It is a schematic cross-sectional view showing another example of the continuous casting equipment of the cast slab according to the present embodiment.

[0060] [ Fig.10 ] Fig.10 It is a schematic cross-sectional view showing another example of the continuous casting equipment of the cast slab according to the present embodiment. DETAILED DESCRIPTION

[0061] The present invention is described below through the embodiments of the present invention. The embodiments shown below illustrate the device and method for realizing the technical idea of ​​the present invention. The technical idea of ​​the present invention does not limit the material, shape, structure, configuration, etc. of the components to the following embodiments. In addition, since the drawings are schematic, it should be noted that the relationship and ratio between the thickness and the plane size are different from the actual situation, and there are also cases where the relationship and ratio of the sizes between the drawings are different.

[0062] Figure 2 It is a schematic cross-sectional view of a continuous casting device for a cast piece according to an embodiment of the present invention. The continuous casting device 1 for a cast piece according to an embodiment of the present invention comprises the following components as main components: a mold 2 for cooling molten steel poured from a pouring tundish (not shown) to form a shell shape of the cast piece; a cooling device 3 for cooling the cast piece drawn out from the mold; a thermometer 4 for measuring the temperature of the cast piece at the output side of the cooling device 3; and a control device 10 for controlling the operation of the cooling device 3. In the following description, Figure 2 In the figure, the long side on the upper right side of the slab is recorded as side 1, the short side on the front side of the paper is recorded as side 2, the long side on the lower left side is recorded as side 3, and the short side on the back side of the paper is recorded as side 4.

[0063] [Mold 2]

[0064] Molten steel produced by a refining facility located at a different location from the continuous casting facility 1 for casting pieces is injected into the mold 2. The injected molten steel is cooled by the mold 2, and solidifies from the contact surface between the molten steel and the mold 2 toward the inner layer to form a shell shape. In the following description, the molten steel formed into a shell shape is described as a casting piece S, including a completely solidified state. The casting piece S extracted from the mold 2 is supported and conveyed by the casting piece support roller 5 provided on the output side of the mold 2, and is cooled by the cooling device 3. As the mold 2, a known mold can be used.

[0065] [Cooling equipment 3]

[0066] The cooling equipment 3 has a water-cooling device 31 for water-cooling the cast piece S under prescribed cooling conditions. The water-cooling device 31 has cast piece support rollers 5 and cooling water nozzles 32 for supporting and conveying the cast piece S. The cast piece support rollers 5 are paired on the 1 side and the 3 side of the cast piece S and are arranged at a certain interval in the casting direction. Between the adjacent cast piece support rollers 5 in the casting direction, two or more cooling water nozzles 32a on the 1 side and two or more cooling water nozzles 32c on the 3 side are arranged in pairs with the cast piece S in between at a prescribed interval in the casting direction. Cooling water W is sprayed toward the cast piece S from the cooling water nozzles 32. By feeding the cast piece S into the cooling equipment 3, the cast piece S is conveyed in the casting direction while being secondarily cooled by the cooling water W sprayed from the cooling water nozzles 32. In the following description, a cooling section with a pair of cast piece support rollers 5 in the casting direction as one unit is recorded as a cooling zone, and the unit of the cooling section is counted as a "zone". In Figure 2 In FIG. 1 , the cooling areas are depicted as a total of 19 areas, but the present invention is not limited thereto and the number of cooling areas may be more or less than 19 areas.

[0067] Figure 2 The continuous casting equipment 1 of the cast piece shown is a vertical bending type continuous casting equipment, characterized in that the cooling equipment 3 is composed of a vertical belt 6 for water-cooling the cast piece S in a vertical posture pulled out from the mold 2, a bending belt 7 for water-cooling while bending the cast piece S through the cast piece support roller 5, and a horizontal belt 8 for water-cooling the cast piece S bent into a horizontal posture by the cast piece support roller 5. In this embodiment, the vertical bending type continuous casting equipment is used as an example for description, but it is not limited to the vertical bending type continuous casting equipment, and can also be applied to a vertical type continuous casting equipment having only the vertical belt 6 in the cooling equipment 3, a bending type continuous casting equipment having only the bending belt 7 and the horizontal belt 8, and a horizontal type continuous casting equipment having only the horizontal belt 8.

[0068] The operating parameters of the water cooling device 31 include the amount of cooling water W sprayed from the cooling water nozzle 32 (cooling water amount), the amount of compressed air (compressed air amount), and the conveying speed of the cast piece S. The more cooling water there is, the greater the cooling speed and temperature drop of the cast piece S can be. In addition, the slower the conveying speed of the cast piece S, the greater the temperature drop of the cast piece S can be. Therefore, by controlling at least one of the conveying speed and the amount of cooling water of the cast piece S, at least one of the surface cooling speed and temperature drop of the cast piece S can be controlled, and the cast piece S with the desired material can be cast. In addition, by adding compressed air to the cooling water W sprayed from the cooling water nozzle 32, the cooling capacity and the surface distribution of the cooling water W can be adjusted. For the target characteristics and the aging degradation of the equipment and the slight changes in the nozzle configuration, the appropriate conditions can be maintained by adjusting the compressed air amount.

[0069] As an operating parameter of the water cooling device 31, the balance of the cooling water amount in each cooling zone may be changed (for example, the cooling water amount may be increased in the cooling zone on the upstream side, and the cooling water amount may be reduced in the cooling zone on the downstream side, etc.). Thus, the cooling rate may be controlled according to the temperature zone of the cast slab S. Furthermore, the number of cooling zones to which cooling water is sprayed may be changed. By changing the number of cooling zones used, the temperature drop of the cast slab S may be controlled while keeping the cooling rate the same.

[0070] Furthermore, the ratio between the amount of cooling water W sprayed from the cooling water nozzle 32a on the 1st surface side and the amount of cooling water W sprayed from the cooling water nozzle 32c on the 3rd surface side can also be changed. In this way, the shape defects caused by the difference in the temperature drop between the 1st surface and the 3rd surface of the casting S can be controlled. In addition, the amount of cooling water can also be changed according to the composition of the casting S. This is because the heat transfer coefficient changes according to the composition of the casting S, and the cooling state changes. In addition, when changing the amount of cooling water, the amount of compressed air and the conveying speed of the casting S can also be changed. The cooling capacity and the surface distribution of the cooling water W are controlled by changing the amount of compressed air, and the temperature history of the casting S is controlled by changing the conveying speed of the casting S. Thus, the cooling conditions can be fine-tuned to improve the quality of the cast casting.

[0071] The operating parameters of the water cooling device 31 can be changed according to the progress of casting. In particular, the front end and the rear end of the casting piece S are also cooled from the front end surface and the rear end surface and are prone to become unstable parts. Therefore, by fine-tuning the operating parameters of the water cooling device 31 for these parts, it is possible to help ensure the quality of the entire length and width and improve the yield rate of the unstable parts.

[0072] In addition, for the stable portion other than the front end portion and the rear end portion, the operating parameters of the water cooling device 31 can also be finely adjusted according to the casting progress. Even if the characteristics of the stable portion vary in the length direction due to the component segregation of the cast piece S, a cast piece that is uniform over the entire length can be obtained by finely adjusting the operating parameters of the water cooling device 31.

[0073] The cooling rate is preferably capable of various changes according to the material, operating conditions, and equipment conditions. When the surface cooling rate exceeds 100°C / second, the surface is martensitic in most cases, and defects such as cracks are generated on the surface of the casting. Therefore, the surface cooling rate is preferably less than 100°C / second. In addition, if the surface cooling rate is less than 0.3°C / second, it becomes a cooling rate almost the same as that of standing cooling, and the production efficiency is reduced. In addition, as the cooling rate decreases, the segregation inside the casting deteriorates, and the quality of the casting also deteriorates. Therefore, the surface cooling rate is preferably above 0.3°C / second.

[0074] from Figure 1As can be seen from the graph shown, the film boiling state always changes to the nucleate boiling state. Therefore, the injection of cooling water W to the cast piece S should be stopped when the surface and back temperatures of the cast piece S are 500°C or higher, preferably 600°C or higher. In addition, after the injection of cooling water W, when the surface and back temperatures of the cast piece S become sufficiently high again due to internal heat recovery, cooling water W may be injected again. The cooling rate is increased by the re-injection, thereby increasing production efficiency and improving the quality of the cast piece.

[0075] As the cooling water nozzle 32, it is preferable to use a nozzle that can uniformly spray cooling water at a predetermined flow rate. In the present embodiment, a spray nozzle is used as the cooling water nozzle 32, but it is not limited to a spray nozzle, and a slit-type nozzle, a multi-hole jet nozzle, a mist nozzle, a fog nozzle, or the like can also be used. In addition, as the cooling water nozzle 32, a single-fluid nozzle that sprays only a liquid (generally water) can be used, and a two-fluid nozzle that sprays a mixed fluid of a liquid (generally water) and a gas (generally air) can also be used.

[0076] Nozzles that only spray air do not produce boiling transition phenomenon, but can also be arranged or staggered near the cooling water nozzle 32, and air can be sprayed from the nozzle to achieve improved drainage, water removal, etc. In addition, the cooling water nozzle 32 is preferably a nozzle that can make various changes to the cooling water volume and compressed air volume according to the target cooling speed.

[0077] When the cooling water W sprayed from the cooling water nozzle 32 collides with the cast piece S, if the cooling water W sprayed from the adjacent cooling water nozzle 32 collides with the cast piece S, the momentum in the horizontal direction changes to the momentum in the vertical direction at the collision portion, and the vertical downward flow therein destroys the steam film, and the film boiling state partially collapses. In addition, in the spray having a rectangular spray injection surface, the horizontal component of the momentum of the cooling water W sprayed in the long side direction is larger than that of the cooling water W sprayed in the short side direction. Therefore, the cooling water W sprayed from the adjacent cooling water nozzles 32 needs to avoid collision in the long side direction.

[0078] Figure 3 This is a diagram showing the spraying surface of cooling water sprayed from the cooling water nozzle on the cast slab S. Figure 3 (a) is a diagram showing a rectangular spray injection surface. Consider that the spray injection surface on the cast piece S is a rectangle with a short side length of t 1 (m), the length of the long side is t 2(m) cooling water nozzle 32. According to the geometric relationship, in order to avoid the collision of the long side direction of the spray injection surface, the cooling water nozzle 32 needs to be set in a manner that the spray injection surfaces of the cooling water nozzles 32 adjacent in the width direction of the cast sheet S do not overlap. Specifically, the cooling water nozzle 32 is set within the range that the setting spacing of the cooling water nozzles 32 adjacent in the width direction of the cast sheet S, the angle of the long side direction relative to the width direction of the cast sheet, and the length of the short side of the spray injection surface satisfy the following formula (1). By setting the cooling water nozzle 32 within the range that satisfies the following formula (1), the collision of the long side direction of the cooling water W sprayed from the cooling water nozzles 32 adjacent in the width direction of the cast sheet S can be suppressed, and the collapse of the film boiling state can be suppressed. It should be noted that the same is true for the case of a cooling water nozzle whose spray injection surface on the cast sheet S is an ellipse. The long side direction of the following formula (1) can be changed to the long axis direction, and the length of the short side can be changed to the length of the short axis.

[0079] [Formula 3]

[0080]

[0081] In the above formula (1), L is the installation distance of the cooling water nozzle (m), θ 1 is the angle (°) between the long side of the spray jet surface and the width of the slab, t 1 is the length of the short side of the spray injection surface (m).

[0082] When the spray injection surface on the casting S is rectangular or elliptical, the aspect ratio of the injection surface is preferably 100 or less. By using a spray with a small aspect ratio of the spray injection surface, the spray injection surface becomes wider, and the local concentration of cooling water can be suppressed to maintain the film boiling state for a longer time. The aspect ratio of the spray injection surface is more preferably 50 or less, and further preferably 30 or less.

[0083] In addition, when the same amount of water is sprayed using nozzles with the same length of the long side, it is preferred to use a nozzle with a small aspect ratio and a large short axis size. The area of ​​the spray spray surface of the nozzle with a small aspect ratio and a long short side becomes larger, so the water density is reduced, which can suppress the local concentration of cooling water. On the other hand, if the aspect ratio is too small, the amount of water flowing in the direction of the spray long axis is reduced, and the cooling water W is easy to stay on the casting S. Therefore, the aspect ratio is preferably 2 or more, more preferably 5 or more, and more preferably 10 or more.

[0084] In addition, the angle θ in the long side direction 1 It is preferably less than 45° so that the cooling water W sprayed onto the slab S can be quickly discharged to the outside of the slab. 1If the angle θ is 45° or more, when the speed of the cooling water W in the longitudinal direction is decomposed into the slab conveying direction and the slab width direction, the speed component in the conveying direction becomes larger than that in the slab width direction, which is not preferred. 1 More preferably, it is 30° or less.

[0085] Figure 3 (b) is a diagram showing a square spray injection surface. When the spray injection surface on the cast piece S is square, the collision of cooling water can be suppressed by arranging the cooling water nozzles 32 so that the installation spacing of the cooling water nozzles 32 adjacent to each other in the width direction of the cast piece S, the angle of one side of the spray injection surface relative to the width direction of the cast piece, and the length of one side of the spray injection surface satisfy the range of the following formula (2).

[0086] L×sinθ 2 >t···(2)

[0087] In the above formula (2), L is the installation distance (m) of the cooling water nozzles 32, θ 2 is the angle (°) of one side of the spray jet surface relative to the width direction of the cast piece, and t is the length (m) of one side of the spray jet surface. Here, one side of the spray jet surface refers to the side of the spray jet surface that is closest to the adjacent spray jet surface. Figure 3 In the spray injection surface 20 of (b), the one side direction refers to the direction of the side 21 closest to the adjacent spray injection surface 22. In the spray injection surface 22, the one side direction refers to the direction of either the side 23 or the side 24 closest to the adjacent spray injection surfaces 20 and 25.

[0088] Figure 3 (c) is a diagram showing a circular spray injection surface. When the spray injection surface on the cast piece S is circular, the collision of cooling water can be suppressed by arranging the cooling water nozzles 32 within a range where the installation interval of the adjacent cooling water nozzles 32 in the width direction of the cast piece S and the diameter of the spray injection surface satisfy the following formula (3).

[0089] L>D···(3)

[0090] In the above formula (3), L is the installation pitch (m) of the cooling water nozzles 32, and D is the diameter (m) of the spraying surface of the spray.

[0091] The degree of local concentration of cooling water can also be evaluated by the water density defined by flow rate / injection area. Since the water density of the injected cooling water is positively correlated with the boiling transition temperature, the film boiling state can be maintained for a long time by reducing the water density. In order to stabilize the film boiling state, the local water density of the cooling water in the continuous casting device 1 of the cast sheet is preferably set to 1000 L / (m2 ×min) or less, more preferably 800L / (m 2 ×min) or less, more preferably 600L / (m 2 ×min) or less.

[0092] [Thermometer 4]

[0093] The thermometer 4 may be a device that scans the temperature in the width direction of the cast piece S to measure the surface temperature of the cast piece S, or may be a device that is arranged in a single or multiple manner in the width direction of the cast piece S to measure the surface temperature of the cast piece S. By using the thermometer 4 to measure the surface temperature of the cast piece S cooled by the cooling device 3, it is possible to confirm whether the cast piece S can be cooled as expected.

[0094] Refer again Figure 2 ,exist Figure 2 In the embodiment, the thermometer 4 is provided at the output side of the cooling device 3, but the thermometer 4 may be provided in the cooling device 3 as long as the temperature of the steel plate after cooling by the water cooling device 31 can be measured. In this case, a plurality of thermometers 4 may be arranged in a row with respect to the conveying direction of the cast piece S to measure the temperature of the cast piece S in each cooling area.

[0095] Furthermore, the thermometer 4 may be provided at the input side of the cooling device 3 and the input side of the casting mold 2 to measure the initial temperature of the casting S and the injection temperature of the molten steel. This is because the calculation accuracy of the cooling rate is improved when the temperature measurement result at the input side of the cooling device 3 is taken into account. A single or multiple thermometers 4 may be provided in the cooling device 3 to measure the temperature of the casting S during water cooling. When the temperature measurement result inside the cooling device 3 is taken into account, the calculation accuracy of the cooling rate can be improved, and its time history can also be grasped.

[0096] In addition, the molten steel temperature information and the temperature measurement results of the cast piece S can also be combined, and the cooling rate in water cooling can be calculated by performing heat transfer calculation and heat transfer simulation to confirm whether the cast piece S can be cooled as expected. In addition, it is also possible to confirm whether the cast piece S is uniformly cooled by measuring the in-plane temperature distribution of the cast piece S during or after water cooling. In addition, it is also possible to confirm whether the cast piece S is loaded into the cooling device 3 with a uniform in-plane temperature distribution by measuring the in-plane temperature distribution of the cast piece S before water cooling. Based on these calculation results, the operating parameters of the cooling device 3 and the operating conditions of the continuous casting device 1 of the cast piece can also be changed.

[0097] [Control device 10]

[0098] Next, the control device 10 will be described. Figure 41 is a schematic diagram showing a structural example of the control device 10. The control device 10 is an information processing device such as a personal computer. In addition to obtaining dimensional information such as the temperature of the molten steel and the thickness of the cast piece S from the upper computer 11, the control device 10 also obtains information related to the target range of the cooling amount and the target range of the cooling rate required to obtain the desired material. Then, the control device 10 calculates the operating conditions of the continuous casting equipment 1 for achieving the target cooling amount and the target cooling rate of the cast piece, and determines the operating parameters of each device.

[0099] The control device 10 includes a control unit 12 and a storage unit 13. The control unit 12 is, for example, a CPU, and by executing a program read from the storage unit 13, the control unit 12 functions as a calculation unit 14 and an output unit 15. The storage unit 13 is, for example, an information recording medium such as a flash memory that can update records, a hard disk built in or connected via a data communication terminal, or a memory card, and a read / write device thereof. The storage unit 13 records programs for the control unit 12 to execute various functions, data used by the programs, and the like.

[0100] The calculation unit 14 performs heat transfer calculation based on the internal model, and determines the number of cooling zones to be used, the amount of cooling water, the amount of compressed air, and the conveying speed of the slab S so as to satisfy the target cooling amount and the target cooling speed set as the cooling conditions. The command values ​​of the amount of cooling water, the amount of compressed air, and the conveying speed of the slab S determined in this way are output from the output unit 15 to the water cooling device 31. In the water cooling device 31, based on the command values ​​of the amount of cooling water, the amount of compressed air, and the conveying speed of the slab S, the operating pressure and the number of operating units of the cooling water pump, the operating pressure and the number of operating units of the air compressor, the number of headers provided on the upstream side of the cooling water nozzle 32, the opening of the flow regulating valve, and the rotation speed of the slab support roll 5 are generated to determine the operating conditions of the water cooling device 31.

[0101] Any one or all of the number of cooling zones used, the amount of cooling water, the amount of compressed air, and the conveying speed of the cast piece S may also be predetermined by a table based on information such as the composition, size information, and target material of the cast piece S, and sent as a command to the water cooling device 31. In addition, in order to be able to cope with changes in conditions during operation, it is preferable to set adjustment parameters so that the number of cooling zones used, the amount of cooling water, the amount of compressed air, and the conveying speed of the cast piece S can be changed midway.

[0102] [Continuous casting method of cast slab]

[0103] Next, use Figure 21. The continuous casting method of the slab S shown in the continuous casting equipment 1 is described. First, molten steel produced by a refining equipment located at a different place from the continuous casting equipment 1 of the slab is poured into the mold 2 through a pouring tundish (not shown). The injected molten steel is cooled by the mold 2, solidified from the contact surface between the molten steel and the mold 2 toward the inner layer, and forms the outer shell shape of the slab S.

[0104] The cast piece S drawn out from the mold 2 is supported by the cast piece support rollers 5 provided on the delivery side of the mold 2 and is cooled by the cooling device 3 while being conveyed. In this cooling process, the number of zones to be used, the amount of cooling water, the amount of compressed air, and the conveying speed are calculated and set by the control device 10 according to the size of the cast piece S and the characteristics of the target cast piece S. However, in this embodiment, the description is made on the cooling process from Figure 2 The slab S is cooled by spraying water and air in all areas shown.

[0105] A predetermined amount of cooling water W and compressed air A are sprayed from the cooling water nozzles 32 arranged in 19 pairs, and the slab support rolls 5 are rotated at a predetermined speed. These parameters are set by the control device 10 so as to obtain the target slab characteristics, and commands are issued to the cooling water nozzles 32 and the slab support rolls 5. By cooling the slab S with the cooling device 3, a slab S having the desired characteristics can be cast. The slab S that has undergone this cooling process is supplied to the subsequent process.

[0106] As mentioned above, although embodiment of this invention was described, this invention is not limited to this, Various changes and improvements are possible. Figure 5 FIG. 1 is a schematic partial cross-sectional view of a continuous casting apparatus for casting sheets with rollers for removing water. Figure 5 As shown, a water removal roller 33 may be provided on the output side of the water cooling device 31 of the continuous casting equipment 1 of the cast piece to remove the cooling water W retained on the cast piece S. Thus, it is possible to prevent the cast piece S from being partially or entirely cooled due to the cooling water W retained on the cast piece S, thereby preventing the desired cooling amount and desired characteristics of the part or the entire surface from being obtained.

[0107] In order to obtain good dewatering performance, the pressing force of the dewatering roller 33 on the cast sheet S is preferably 4 tons or more. The pressing force of the dewatering roller 33 on the cast sheet S is more preferably 6 tons or more, and further preferably 8 tons or more. On the other hand, if the pressing force of the dewatering roller 33 on the cast sheet S is too large, the dewatering roller 33 is bent due to elastic deformation, and a gap is generated between the cast sheet S and the dewatering roller 33, and the dewatering performance is deteriorated. Therefore, the pressing force of the dewatering roller 33 on the cast sheet S is preferably 20 tons or less.

[0108] As a mechanism for applying a pressing force by the dewatering roller 33, a mechanism that can apply a certain pressing force such as a spring type, air pressure, or oil pressure can be used. From the purpose of adjusting the deflection of the dewatering roller 33, a mechanism that can maintain a certain pressing force is preferred, and a mechanism that can change the pressing force in the longitudinal direction of the cast piece S is more preferably used.

[0109] Furthermore, the casting support rolls 5 may also serve as dewatering rolls. In this case, the pressing force of the casting support rolls 5 is not limited to the above range. This is because pressing the casting S with the casting support rolls 5 can sometimes produce a high-quality casting.

[0110] Figure 6 FIG. 1 is a schematic partial cross-sectional view of a continuous casting apparatus for casting sheets with a purge nozzle. Figure 6 As shown, a purge nozzle 34 may be provided instead of the dewatering roller 33, and the cooling water W retained on the casting S may be removed by spraying a dewatering purge 35. The dewatering purge 35 may be a liquid, a gas, or a mixed fluid thereof. However, when a liquid is used as the dewatering purge 35, the sprayed portion thereof is cooled, and the in-plane temperature deviation of the casting S may be enlarged. Therefore, it is preferred to use a gas as the dewatering purge 35. From the viewpoint of production cost, it is more preferred to use air as the dewatering purge 35.

[0111] Figure 7 The figure is a schematic partial cross-sectional view of a continuous casting apparatus for casting sheets with a water removal roller and a purging nozzle. Figure 7 As shown, the water removal roller 33 and the purging nozzle 34 may be used together. In addition, one or both of the water removal roller 33 and the purging nozzle 34 may be arranged on the input side of the water cooling device 31 to remove the cooling water W leaking from the water cooling device 31. In this way, it is possible to suppress the temperature of the cast piece S to be lowered when it is sent to the cooling device 3, or the cooling water W from flowing into other devices (such as the casting mold 2) located on the upstream side and the surrounding of the cooling device 3.

[0112] Furthermore, not limited to the input and output sides of the water cooling device 31, either or both of the water removal roller 33 and the purging nozzle 34 may be arranged on the input and output sides of each cooling area to divide each cooling area. When a different amount of water is sprayed on each cooling area, the temperature history of the steel plate can be grasped by dividing the area with different amounts of cooling water.

[0113] In addition, all cooling water nozzles 32 of the cooling device 3 do not need to satisfy the above formula (1), formula (2) or formula (3), as long as two or more cooling water nozzles 32 adjacent to each other in the width direction of the cast piece satisfy the above formula (1), formula (2) or formula (3). Thus, compared with a continuous casting device for a cast piece that does not have any cooling water nozzles 32 that satisfy the above formula (1), formula (2) or formula (3), it is possible to suppress the collision of cooling water and suppress the collapse of the film boiling state.

[0114] Figure 8 2 is a schematic cross-sectional view showing another example of a continuous casting device for a cast slab according to the present embodiment. Figure 8 As shown, a cooling water nozzle 36 is provided in the continuous casting equipment 40 of the cast piece, and the cooling water nozzle 36 can spray cooling water in an amount that changes the boiling state into a nucleate boiling state to both the input and output sides of the water cooling device 31, and the cast piece S is cooled using these cooling water according to the characteristics of the target cast piece S. In this way, a cooling water nozzle 36 that sprays cooling water in an amount that changes the boiling state into a nucleate boiling state can also be provided on the input and output sides of the water cooling device 31. In addition, Figure 8 , the cooling water nozzles 36 are provided on both sides of the input and output sides of the water cooling device 31, but the present invention is not limited thereto, and the cooling water nozzles 36 may be provided on either side of the input and output sides. Figure 8 3 shows an example in which the cooling water nozzles 36 are provided in three regions on the input side and three regions on the output side of the water cooling device 31 , but the present invention is not limited thereto and the cooling water nozzles 36 may be provided in regions other than the three regions.

[0115] Fig. 9 2 is a schematic cross-sectional view showing another example of a continuous casting device for a cast slab according to the present embodiment. Fig. 9 As shown, in the continuous casting equipment 50 for casting slabs, the cooling water nozzle 32 and the cooling water nozzle 36 capable of spraying cooling water in an amount sufficient to convert the boiling state into a nucleate boiling state are arranged in the same cooling area. In this way, the cooling water nozzle 32 and the cooling water nozzle 36 can also be arranged in the same cooling area, and by combining the cooling of the cooling water nozzle 32 and the cooling of the cooling water nozzle 36, a cooling that becomes a more colorful temperature history record can be achieved. Fig. 9 2 shows an example in which the cooling water nozzles 32 and the cooling water nozzles 36 are arranged in the same cooling area in two areas. The present invention is not limited to this, and the cooling water nozzles 32 and the cooling water nozzles 36 may be arranged in the same cooling area in areas other than two areas.

[0116] Fig.10 2 is a schematic cross-sectional view showing another example of a continuous casting device for a cast slab according to the present embodiment. Fig.10As shown, a cooling water nozzle 37 is arranged in the continuous casting equipment 60 of the cast sheet, and the cooling water nozzle 37 only sprays the amount of water that changes the boiling state into the nucleate boiling state to a part of the cooling water nozzle in the water cooling device 31. In this way, the cooling water nozzle 37 can also be arranged in a part of the cooling water nozzle in the water cooling device 31. This is because, if the collision of cooling water can be suppressed in the part, the collapse of the film boiling state can be suppressed. In addition, the cooling water nozzle 36 that can spray the amount of water that changes the boiling state into the nucleate boiling state can be a single-fluid nozzle that only sprays air, a single-fluid nozzle that only sprays water, or a double-fluid nozzle that sprays a mixed fluid of water and air.

[0117] The cast piece S extracted from the casting mold 2 is generally conveyed while being pressed down by the cast piece support rollers 5 after being cooled. This is because by pressing down the cast piece S, internal segregation can be reduced and the quality of the cast piece can be improved. Therefore, the continuous casting method of the cast piece of the present embodiment can also be combined with a known cast piece pressing technology, thereby further improving the quality of the cast piece produced. At this time, it is preferred that the operating parameters of the water cooling device 31 and the operating parameters related to the known cast piece pressing technology are coupled to each other.

[0118] In addition, in the continuous casting equipment 1 of the cast piece of the present embodiment, an example is shown in which the cast piece support rolls 5 are arranged on the 1st and 3rd surface sides of the cast piece S, but the present invention is not limited thereto, and the cast piece support rolls 5 may be arranged on the 2nd and 4th surface sides. By supporting and pressing the 2nd and 4th surface sides with the rolls, it is possible to suppress the expansion in the width direction caused by the pressing of the cast piece support rolls 5 from the 1st and 3rd surface sides.

[0119] Example

[0120] Next, the instructions will use Figure 2 The continuous casting equipment 1 of the cast piece shown is an embodiment of manufacturing a slab of a raw material for rolling by cooling the continuously cast cast piece S with a cooling device 3. In the continuous casting equipment 1 of the cast piece, the cooling device 3 is arranged on the downstream side of the mold 2, and 19 pairs of cooling water nozzles 32 and 20 pairs of cast piece support rollers 5 constituting a water cooling device 31 are arranged inside the cooling device 3. The cooling water nozzle 32 is configured to be replaceable with a rectangular spray nozzle, a square spray nozzle, and a circular spray nozzle, and is replaced according to the casting conditions.

[0121] A thermometer 4 is set at a position 5m away from the output side of the cooling device 3 to the downstream side, and the surface temperature distribution of the casting S in the width direction after passing through the cooling device 3 is measured. For the temperature distribution in the width direction of the casting S measured by the thermometer 4, the value obtained by subtracting the minimum value from the maximum value is evaluated as the temperature deviation value in the casting S, and when the temperature deviation value is less than 50°C, the temperature deviation is regarded as qualified. In addition, for the slab manufactured by cutting the cast casting S, the micro cracks on the surface of the slab are tracked and investigated in the inspection of the subsequent process. In addition, the number of segregation grains in the thickness center of the casting is investigated. In addition, in the subsequent process, the steel strip after the slab is hot and cold rolled is inspected, and it is tracked and investigated whether defects are found in the steel strip after cold rolling. Furthermore, a heat transfer simulation based on the temperature measurement results of the thermometer 4 is implemented to calculate the surface cooling rate of the casting S. The casting conditions and evaluation results of the casting S in this embodiment are shown in the following Table 1. In addition, in Table 1, the angle is θ in the case of a rectangle. 1 , which is θ in the case of a square 2 In addition, the length is t in the case of a rectangle. 1 , which is t in the case of a square and the diameter D in the case of a circle.

[0122]

[0123] The evaluation results of the cast pieces of Inventive Examples 1-6 were all qualified, and high-quality slabs could be obtained uniformly over the entire width and length. No defects were confirmed in the steel strip after cold rolling, and the steel strip became a product that could be shipped. In Inventive Example 4, no defects were confirmed in the steel strip after cold rolling, and the temperature deviation was less than 50°C, but the temperature deviation was larger than that of Inventive Example 2. This is because the injection angle θ 1 The speed component of the spray water in the conveying direction becomes larger, and the cooling water sprayed on the casting cannot be quickly discharged outside the casting, resulting in a local overcooling portion. In addition, even under the same conditions, the temperature deviation in the width direction is smaller when the rectangular spray nozzle is used than when the circular or square spray nozzle is used. This result is because the cooling water W in the long axis direction with a fast flow rate can be quickly discharged outside the width of the casting S by using the rectangular spray nozzle.

[0124] When a rectangular spray nozzle is used, the temperature deviation is smallest when a spray nozzle with an aspect ratio of 30 is used. If the aspect ratio is small, the drainage effect of the cooling water W is reduced. On the other hand, if the aspect ratio is large, the cooling water W is locally concentrated, and the temperature deviation becomes large. From this result, it is confirmed that the aspect ratio of the spray injection surface has an optimal value.

[0125] Inventive Example 7-9 is a casting example in which rectangular, square, and circular spray nozzles are used, and the water density is increased. In Inventive Example 7-9, the temperature deviation is less than 50°C and is qualified, but many tiny cracks are generated on the surface of the slab. The tiny cracks are caused by the excessive cooling rate, and the surface layer of the casting S is martensited. However, the temperature deviation of Inventive Example 7-9 is qualified, so no defects are confirmed in the steel strip after cold rolling, and it becomes a product that can be shipped.

[0126] Inventive Examples 10-12 are casting examples in which a rectangular, square or circular spray nozzle is used, and the water density is reduced. In Inventive Examples 10-12, the temperature deviation is less than 50°C and is qualified, but the number of segregated grains in the center of the thickness of the cast piece increases. The increase in the number of segregated grains in the center of the thickness of the cast piece is because the cooling rate is too low, and the temperature gradient inside the cast piece S becomes smaller. However, the temperature deviation of Inventive Examples 10-12 is qualified, so no defects are confirmed in the steel strip after cold rolling, and it becomes a product that can be shipped.

[0127] Comparative Example 1 is a case where a flat spray nozzle is used, and it is a casting example in which the spray angle is reduced and the above formula (1) is not satisfied. In Comparative Example 1, the temperature deviation is 90°C, and it is impossible to produce a slab that is uniform across the entire width, and defects occur in the steel strip after rolling. Therefore, the steel strip produced from this slab cannot be shipped. This is because the cooling water W sprayed from adjacent nozzles interferes with each other, and the film boiling state collapses in this part, and the cooling capacity is improved.

[0128] Comparative Example 2 is a case where a rectangular spray nozzle is used. It is a casting example in which the injection angle is increased and the above formula (1) is not satisfied. In Comparative Example 2, the temperature deviation is 218°C, and it is impossible to produce a slab that is uniform over the entire width, and defects occur in the steel strip after rolling. Therefore, the steel strip manufactured from this slab cannot be shipped. This is because the cooling water W on the casting S cannot be discharged outside the width of the casting S, and the cooling water W is retained on the casting S, thereby partially transforming the film boiling state into the nucleate boiling state.

[0129] Comparative Examples 3 and 4 are casting examples in which square or circular spray nozzles are used, and the nozzle spacing is shortened and does not satisfy the above formula (2) or (3). In Comparative Examples 3 and 4, the temperature deviation is 86°C and 92°C, respectively, and it is impossible to produce a slab that is homogeneous over the entire width, and defects occur in the steel strip after cold rolling. Therefore, the steel strip produced from this slab cannot be shipped. This is because the cooling water W sprayed from adjacent spray nozzles interferes with each other, and the cooling capacity is improved only in this part.

[0130] Description of Reference Numerals

[0131] 1 Continuous casting equipment for cast sheets

[0132] 2. Casting

[0133] 3 Cooling equipment

[0134] 4 Thermometer

[0135] 5 Casting support roller

[0136] 6 Vertical belt

[0137] 7 Bending belt

[0138] 8 Horizontal belt

[0139] 10 Control Device

[0140] 11 Upper Computer

[0141] 12 Control Unit

[0142] 13 Storage

[0143] 14 Operation unit

[0144] 15 Output

[0145] 20 Spray spray surface

[0146] 21 Edge

[0147] 22 Spray spray surface

[0148] 23 Edge

[0149] 24 Sides

[0150] 25 Spray spray surface

[0151] 31 Water cooling device

[0152] 32 Cooling water nozzles

[0153] 32a Cooling water nozzle

[0154] 32c Cooling water nozzle

[0155] 33 Water removal roller

[0156] 34 Purge nozzle

[0157] 35 Water removal and purge

[0158] 36 Cooling water nozzle

[0159] 37 Cooling water nozzle

[0160] 40 Continuous casting equipment for casting sheets

[0161] 50 Continuous casting equipment for casting sheets

[0162] 60 Continuous casting equipment for casting sheets

[0163] S Casting

[0164] W Cooling water

Claims

1. A continuous casting device for casting slabs, comprising a cooling device for water cooling the casting slabs, wherein: The cooling device has two or more cooling water nozzles arranged along the width direction of the cast slab. The two or more cooling water nozzles are arranged so that spray injection surfaces of the cooling water nozzles adjacent to each other in the width direction of the cast slab do not overlap.

2. The continuous casting device of the cast sheet according to claim 1, wherein: The spraying surface of the cooling water nozzle is rectangular or elliptical. The two or more cooling water nozzles are respectively arranged within the range satisfying the following formula (1): [Formula 1] In the formula (1), L is the installation interval of the cooling water nozzles (m), θ1 is the angle (°) of the long side or long axis direction of the spray injection surface relative to the width direction, and t1 is the length of the short side or short axis of the spray injection surface (m).

3. The continuous casting device of the cast sheet according to claim 1, wherein: The spray spray surface of the cooling water nozzle is square. The two or more cooling water nozzles are respectively arranged within the range satisfying the following formula (2): L×sinθ2>t···(2) In the formula (2), L is the setting spacing of the cooling water nozzles (m), θ2 is the angle (°) of one side of the spray injection surface relative to the width direction, one side of the spray injection surface is the side closest to the adjacent spray injection surface among the sides of the spray injection surface, and t is the length of the one side (m).

4. The continuous casting device of the cast sheet according to claim 1, wherein: The spray spray surface of the cooling water nozzle is circular. The two or more cooling water nozzles are respectively arranged within the range satisfying the following formula (3): L>D···(3) In the formula (3), L is the installation pitch (m) of the cooling water nozzles, and D is the diameter (m) of the spray injection surface.

5. The continuous casting device of the cast sheet according to claim 2, wherein: The aspect ratio of the spray injection surface is 100 or less.

6. The continuous casting device of cast slabs according to any one of claims 1 to 5, wherein: The surface layer cooling rate of the cast slab in the cooling device is within a range of 0.3° C. / sec to 100° C. / sec.

7. The continuous casting device of cast slabs according to any one of claims 1 to 5, wherein: The continuous casting equipment of the cast piece includes a control device that controls the amount of cooling water sprayed from the cooling water nozzle and the conveying speed of the cast piece.

8. The continuous casting device of cast slabs according to claim 6, wherein: The continuous casting equipment of the cast piece includes a control device that controls the amount of cooling water sprayed from the cooling water nozzle and the conveying speed of the cast piece.

9. A continuous casting method for a cast sheet, comprising a cooling step of water cooling the cast sheet, wherein: In the cooling step, cooling water is sprayed from two or more cooling water nozzles arranged along the width direction of the cast piece to cool the cast piece. The two or more cooling water nozzles are arranged so that spray injection surfaces of the cooling water nozzles adjacent to each other in the width direction of the cast slab do not overlap.

10. The continuous casting method of a cast slab according to claim 9, wherein: The spraying surface of the cooling water nozzle is rectangular or elliptical. The two or more cooling water nozzles are respectively arranged within the range satisfying the following formula (1): [Formula 2] In the formula (1), L is the installation interval of the cooling water nozzles (m), θ1 is the angle (°) of the long side or long axis direction of the spray injection surface relative to the width direction, and t1 is the length of the short side or short axis of the spray injection surface (m).

11. The continuous casting method of a cast slab according to claim 9, wherein: The spray spray surface of the cooling water nozzle is square. The two or more cooling water nozzles are respectively arranged within the range satisfying the following formula (2): L×sinθ2>t···(2) In the formula (2), L is the setting spacing of the cooling water nozzles (m), θ2 is the angle (°) of one side of the spray injection surface relative to the width direction, one side of the spray injection surface is the side closest to the adjacent spray injection surface among the sides of the spray injection surface, and t is the length of the one side (m).

12. The continuous casting method of a cast slab according to claim 9, wherein: The spray spray surface of the cooling water nozzle is circular. The two or more cooling water nozzles are respectively arranged within the range satisfying the following formula (3): L>D···(3) In the formula (3), L is the installation pitch (m) of the cooling water nozzles, and D is the diameter (m) of the spray injection surface.

13. The continuous casting method of a cast slab according to claim 10, wherein: The aspect ratio of the spray injection surface is 100 or less.

14. The continuous casting method of a cast slab according to any one of claims 9 to 13, wherein: The surface layer cooling rate of the cast slab in the cooling step is within a range of 0.3° C. / sec to 100° C. / sec.

15. The continuous casting method of a cast slab according to any one of claims 9 to 13, wherein: By controlling the amount of cooling water sprayed from the cooling water nozzle and the conveying speed of the cast piece, at least one of the surface layer cooling speed of the cast piece and the temperature drop amount of the cast piece in the cooling step is controlled.

16. The continuous casting method of a cast slab according to claim 14, wherein: By controlling the amount of cooling water sprayed from the cooling water nozzle and the conveying speed of the cast piece, at least one of the surface layer cooling speed of the cast piece and the temperature drop amount of the cast piece in the cooling step is controlled.

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