JP5423575B2 - Steel plate cooling equipment - Google Patents

Description

  The present invention relates to cooling of a steel sheet being conveyed in a hot rolling process or a heat treatment process, for example, and particularly relates to a technique capable of efficiently cooling a steel sheet having a temperature of 950 ° C. or higher.

  In general, a steel plate rolling facility is generally configured by arranging a heating furnace, a rough rolling device, and a finishing rolling device including a plurality of rolling stands in a row along the moving direction of the steel plate. In order to facilitate rolling, the slab supplied from the casting equipment is heated to about 1200 ° C. by a heating furnace and then supplied to the rough rolling apparatus, and the rough rolling apparatus forms a roughly rolled steel sheet having a thickness of about 30 to 50 mm. Processed. Then, it is sent to a finishing rolling device through a crop shear process and a descaling process. The surface temperature of the rough rolled steel plate at this time may be about 1100 ° C. to 1150 ° C., depending on the setting of the heating furnace.

  In the finish rolling apparatus, there is a demand to perform rolling after setting the temperature of the rough rolled steel sheet to 1050 ° C. or lower in order to prevent the occurrence of scale flaws. Since the surface temperature of the rough rolled steel sheet immediately after the rough rolling is about 1100 ° C. to 1150 ° C. as described above, it is necessary to cool about 50 ° C. to 100 ° C. before finish rolling. Conventionally, the rough rolled steel sheet is temporarily stopped in front of the finish rolling apparatus and allowed to cool, and after waiting for the surface temperature of the steel sheet to be 1050 ° C. or less, it is sent to the finish rolling apparatus. There was a problem that the production efficiency was lowered.

  In order to improve production efficiency, it is only necessary to cool the steel sheet by placing a cooling device in front of the finish rolling device, but in reality, there is a descaling device, surface between the rough rolling device and the finish rolling device. Equipment such as a thermometer, an edger device, and a crop shear device has already been arranged, and there is a situation that the space is extremely limited even if a cooling device is installed. For this reason, since the space before finish rolling is limited, a cooling capacity is required such that the steel plate temperature is lowered by 40 ° C. or more in a cooling time of about 1 second.

On the other hand, various steel plate cooling devices have been proposed.
For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-240915) discloses a technique in which a plurality of cooling nozzles are arranged on a steel plate and a rod-shaped water jet is injected from each cooling nozzle to cool the steel plate. . According to the technique described in Patent Document 1, the jet collision areas of rod-shaped water jets on the steel plate are separated from each other, and the area ratio of the jet collision area to the steel plate is as low as several percent. In addition, the technique described in Patent Document 1 is applied to a steel sheet having a surface temperature of 900 ° C. or less from the description after finish rolling, and is not applied to a high-temperature steel sheet of about 1000 ° C. before finish rolling. Absent. When a rod-shaped water jet is jetted by applying this technology to a steel sheet of about 1000 ° C, water directly hits the steel sheet in the collision area of the water jet on the steel sheet, but cooling is performed efficiently. Since the water flow flows along the surface of the steel sheet, when cooling a high-temperature steel sheet of 950 ° C. or higher, a vapor film is generated due to the evaporation of water at the boundary between the water flow and the steel sheet, and cooling is performed efficiently by the influence of this vapor film. It will not be. Thus, even if the technique described in Patent Document 1 is applied to a high-temperature steel sheet, there is a problem that the cooling capacity cannot be increased.
In order to apply the technique described in Patent Document 1 to a high-temperature steel plate before finish rolling, it is necessary to install a number of cooling nozzles to supplement the cooling capacity. And the space between the finishing rolling devices are limited, the number of installed units is limited, and as a result, the cooling capacity is insufficient.

  Further, Patent Document 2 (Japanese Patent Laid-Open No. 2002-126814) discloses a plurality of components constituting a rough rolling device for the purpose of eliminating a delay time caused by waiting a steel plate for temperature adjustment before the finish rolling device. A technique for disposing a cooling device for injecting cooling water between the rough rolling stands and predicting the temperature before finish rolling to cool in advance is disclosed. However, with this method, recovery is difficult when the predicted value is off immediately before finish rolling, and a specific method for injecting cooling water by a cooling device is not disclosed.

  Further, Patent Document 3 (Japanese Patent Publication No. 60-48241) discloses a steel plate between the descaling device and the first stand of the finish rolling device, or between the first stand and the second stand of the finish rolling device. A water cooling device is disclosed that forcibly cools the central portion in the width direction that is equal to or higher than the critical temperature at which scale flaws are generated. However, due to the recent trend of high-mix low-volume production, steel plates with different widths may be supplied to the finish rolling device, and it is difficult to make the temperature in the width direction of the steel plate uniform with the device of Document 3. There is. Further, as shown in FIG. 5 of the same document, since the water cooling device is arranged immediately before the first stand of the finish rolling device, rolling is performed while the surface temperature of the steel plate is lowered, and the quality of the steel plate is thereby improved. There is a possibility of adverse effects. Moreover, the concrete installation method, such as the amount of cooling water by a cooling device, the kind of nozzle, and the distance of a nozzle and a steel plate, is not indicated.

  Furthermore, Patent Document 4 (Japanese Patent Laid-Open No. 8-238518) discloses a cooling method in which water jets are ejected from a plurality of spray nozzles onto a steel plate so that the jet regions of the water jet on the steel plate overlap each other. Is disclosed. However, in Patent Document 5, the spray angle of the spray nozzle is preferably 90 ° or less, and the relationship between the spray angle and the installation space is not studied in detail. Further, there is no disclosure about the relationship between the distance from the spray nozzle to the steel plate and the installation space. Furthermore, Patent Document 4 mainly targets cooling of a thick steel plate after finish rolling, such as a water amount for cooling a thick steel plate of 950 ° C. or higher in a short time, an installation method such as a distance between the nozzle and the steel plate, etc. No disclosure has been made. From the above, even if the technique described in Patent Document 4 is applied to the rolling equipment as it is, the problem of the installation space cannot be solved and it is not clear whether the cooling capacity can be secured.

  Further, the cooling capacity of the thick steel plate by the conventional apparatus is described in Non-Patent Document 1, and after finish rolling, the temperature range is lower than the target temperature range of the present invention, but the plate thickness of 40 mm is about 20 ° C / It is second. As shown in FIG. 22, the water cooling capacity differs from the film boiling region, transition boiling region, and nucleate boiling region depending on the surface temperature of the steel sheet. A high-temperature steel sheet having a target temperature range of 950 ° C. or higher, which is the target temperature range of the present invention, generally has a film boiling range and a low heat transfer coefficient. That is, as can be seen from a comparison with the prior art, the cooling capacity required for the purpose of the present invention is very high when the cooling temperature region is also taken into consideration. Up to now, no apparatus has been shown industrially that has a cooling capacity sufficient to reduce the temperature of a steel plate of about 40 mm in cooling time of about 1 second by 50 ° C. or more.

JP 2001-240915 A JP 2002-126814 A Japanese Patent Publication No. 60-48241 JP-A-8-238518

Kominato, Yoshimura, Yamamoto, “High-quality, high-performance steel plate that meets advanced manufacturing technology”, NKK Technical Report, JFE Steel Corporation, November 2002, No. 179, p. 58

  The present invention has been made in view of the above circumstances, the cooling capacity is sufficient, the temperature distribution in the width direction and the longitudinal direction of the steel sheet after cooling is small, and the apparatus itself is compact and has no wide installation space. However, an object of the present invention is to provide a cooling device that can be provided with rolling equipment and can improve the efficiency of the rolling process.

In order to achieve the above object, the present invention employs the following configuration.
The steel plate cooling device according to the present invention has a substantially conical shape from each of a plurality of spray nozzles arranged along the moving direction of the steel plate and the width direction of the steel plate with respect to one surface of the steel plate having a thickness of 20 mm or more moved in one direction. In the steel sheet cooling apparatus for injecting the water jets to cool the steel sheet, at least one rolling stand is provided on the downstream side of the cooling apparatus, and the water density of the water jets on the one surface is 2 m ³ / m ² / min or more, and the shape of the water jet is a full cone shape, a full elliptical cone shape, a long cone shape, or a mixture thereof, and the jet collision of the water jets on the one surface The plurality of spray nozzles are disposed in the steel so that the regions are at least continuous with each other along the width direction of the steel plate and are at least continuous with each other along the inclination direction with respect to the width direction of the steel plate. It is arrange | positioned at the both sides of the upper surface and lower surface of a board, and the peak of the heat transfer coefficient at the time of the said water jet colliding with the said steel plate is 6000 (W / m < ² > K) or more at maximum, and after cooling stops The surface temperature upon reheating is controlled to 950 ° C. or higher.
In the steel sheet cooling device of the present invention, the maximum spreading angle of the substantially conical water jet is in the range of 10 ° to 30 °, and the distance from the spray nozzle tip to the one surface is 200 mm or more. A range of 700 mm or less is preferable.
Note that the fact that the jet collision areas are continuous includes that the jet collision areas are in contact with each other and that the jet collision areas are overlapped with each other.
In the steel sheet cooling device of the present invention, it is preferable that the water density of the water jet on the one surface is 8 m ³ / m ² / min or more.
In the steel plate cooling device of the present invention, the plurality of spray nozzles may be arranged such that the jet collision areas of the water jets on the one surface are in close contact with each other along the moving direction of the steel plate. preferable.
In the steel sheet cooling apparatus of the present invention, the jet collision areas arranged along the inclination direction with respect to the width direction of the steel sheets overlap with an overlap width in the range of 0% to 100% of the radius of each jet collision area. It is preferable that the plurality of spray nozzles are arranged so as to be combined.
In the steel sheet cooling apparatus of the present invention, the jet collision areas arranged along the width direction of the steel sheets are overlapped with an overlap width in the range of 0% to 100% of the radius of each jet collision area. Preferably, the plurality of spray nozzles are arranged.
In the steel sheet cooling device of the present invention, the ratio (lower surface side / upper surface side) of the water amount density of the spray nozzle disposed on the upper surface side to the water amount density of the spray nozzle disposed on the lower surface side is 1 A range of 2 or less is preferable.
In the steel sheet cooling apparatus of the present invention, it is preferable that the water density in each spray nozzle is set to the same value.
Further, in the steel sheet cooling device of the present invention, a pair of draining spray nozzles are disposed on the upstream side and the downstream side in the moving direction of the steel sheet, and the plurality of spray nozzles are disposed between the draining spray nozzles. Preferably it is.

The steel plate cooling device of the present invention is suitably applied to a high temperature steel plate of 950 ° C. or higher. Here, the cooling capacity for the steel sheet can be evaluated by the heat transfer coefficient (W / m ² · K) or the cooling rate of the steel sheet. The cooling rate of the steel sheet is obtained by dividing the difference in average temperature of the cross section in the thickness direction of the steel sheet before and after cooling by the cooling time.
In the cooling device of the present invention, since the jet collision area due to the water jet is continuous at least with each other along the width direction of the steel sheet and the inclination direction with respect to the width direction, the surface temperature of the steel sheet is thereby continuously reduced. . The heat transfer coefficient is different from the film boiling region, transition boiling region, and nucleate boiling region depending on the surface temperature of the steel plate as shown in FIG. 22, and is generally a film boiling region in a high-temperature steel plate of 950 ° C. or higher. The transmission rate is low. When the temperature of the steel plate to be cooled decreases, it enters a transition boiling region and the cooling capacity tends to improve. Therefore, heat transfer is performed by gradually decreasing the temperature of one surface of the steel plate while the water jet collides with the steel plate. The rate is gradually increased and the cooling capacity can be improved.

Further, according to the cooling device of the present invention, since the maximum spread angle of the water jet and the distance from the nozzle tip to the steel plate are set in the above range, the cooling device itself can be made compact, It can be easily introduced into the rolling equipment. Moreover, by setting the maximum spread angle of the water jet to 30 ° or less, the component in the vertical direction of the water jet with respect to the steel plate can be increased, and the cooling capacity can be further increased.
Furthermore, since the water density is set to 2 m ³ / m ² / min or more, more preferably 8 m ³ / m ² / min or more, the cooling capacity can be greatly improved.

Further, according to the cooling device of the present invention, the jet collision area is in close contact with each other along the moving direction of the steel sheet, so that a plurality of continuous portions of the jet collision area along the moving direction of the steel sheet increase. The surface temperature of the is further reduced. For this reason, the heat transfer rate is further increased, and the cooling capacity can be further improved.
In addition, according to the cooling device of the present invention, since the jet collision areas arranged along the width direction of the steel plates are overlapped with each other with the above-described overlap width, there is no risk of variation in the cooling capacity in the width direction of the steel plates. It becomes possible to cool the steel plate uniformly.
In addition, the jet collision areas arranged along the inclination direction with respect to the width direction of the steel plate are overlapped with each other with the above-described overlap width, so that there is no possibility that the cooling capacity in the moving direction of the steel plate varies, and the steel plate is made uniform. It becomes possible to cool.
Moreover, according to the cooling device of the present invention, the cooling capability can be further improved by arranging the plurality of spray nozzles on both sides of the steel plate.

As described above, according to the present invention, there is a high cooling capacity, the variation in the temperature distribution in the width direction and the longitudinal direction of the steel sheet after cooling is small, and the rolling is performed even if the apparatus itself is compact and there is no wide installation space. A cooling device capable of adding a line and improving the efficiency of the rolling process can be provided.
Moreover, the cooling device of this invention can be applied suitably with respect to the steel plate whose surface temperature is 950 degreeC or more.

FIG. 1 is a schematic side view showing an example of a rolling device provided with a cooling device according to an embodiment of the present invention. FIG. 2 is a diagram showing a jet state of a water jet in the spray nozzle according to the present invention, wherein A is a perspective view showing an example of a full cone spray nozzle in which the water jet has a conical shape, and B is a water jet. It is a perspective view which shows the example of the elliptical spray nozzle used as an elliptical cone shape, and C is a perspective view which shows the example of the elliptical spray nozzle whose water jet becomes a long cone shape. FIG. 3 is a schematic plan view showing an example of the arrangement of the spray nozzles and the jet collision area of the cooling device according to the embodiment of the present invention. FIG. 4 is a graph showing the relationship between the maximum spread angle of the water jet and the distance from the tip of the spray nozzle to one surface of the steel plate. FIG. 5 is a schematic plan view showing another example of the arrangement of the spray nozzles and the jet collision area of the cooling device according to the embodiment of the present invention. FIG. 6 is a schematic plan view showing another example of the arrangement of the spray nozzles and the jet collision area of the cooling device according to the embodiment of the present invention. FIG. 7 is a schematic plan view showing still another example of the arrangement of the spray nozzles and the jet collision area of the cooling device according to the embodiment of the present invention. FIG. 8 is a schematic plan view showing still another example of the arrangement of the spray nozzles and the jet collision area of the cooling device according to the embodiment of the present invention. FIG. 9 is a schematic side view showing the configuration of the cooling device used in Experimental Example 1. FIG. 10 is a graph showing the relationship between the temperature of the steel sheet and the cooling time (cooling frequency). FIG. 11 is an enlarged view of FIG. FIG. 12 is a graph showing the relationship between the cooling time and the heat transfer coefficient in the first cooling. FIG. 13 is a graph showing the relationship between the cooling time and the heat transfer coefficient in the second cooling. FIG. 14 is a graph showing the relationship between the temperature of the steel sheet and the cooling time. FIG. 15 is a diagram showing the relationship between the temperature of the steel plate before cooling and the temperature drop of the steel plate when cooled by injecting a water jet from the lower surface side of the steel plate, and is a plot when the steel plate thickness is 40 mm. FIG. FIG. 16 is a diagram showing the relationship between the temperature of the steel plate before cooling and the temperature drop of the steel plate when cooled by jetting a water jet from the upper surface side of the steel plate, and is a plot when the steel plate thickness is 20 mm. FIG. FIG. 17 is a diagram showing the relationship between the temperature of a steel plate before cooling and the temperature drop of the steel plate when cooled by jetting a water jet from the lower surface side of the steel plate, and is a plot when the steel plate thickness is 20 mm. FIG. FIG. 18 is a diagram showing the relationship between the temperature of the steel plate before cooling and the temperature drop of the steel plate when cooled by jetting a water jet from the upper surface side of the steel plate, and is a plot when the steel plate thickness is 20 mm. FIG. FIG. 19 is a diagram showing the relationship between the temperature of the steel plate before cooling and the temperature drop of the steel plate when water jet is cooled from the lower surface side of the steel plate, and the maximum spread angle of the steel plate water jet is 15 It is a plot diagram when the distance from the nozzle tip to the steel plate is 440 mm. FIG. 20 is a schematic diagram showing the relationship between the arrangement of the nozzle and jet collision area and the heat transfer coefficient when the steel plate is cooled using the cooling device of the first embodiment. FIG. 21 is a schematic diagram showing the relationship between the arrangement of the nozzle and jet collision area and the heat transfer coefficient when the steel plate is cooled using the cooling device of Comparative Example 1. FIG. 22 is a schematic diagram showing the relationship between the steel sheet surface temperature and the heat transfer coefficient during water cooling.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings referred to in the following description are for explaining the configuration of the steel sheet cooling device according to the present invention, and the size, thickness, dimensions, etc. of each part shown in the figure are the dimensional relationships of the actual cooling device. May be different.
The present invention is intended to cool a rolled steel plate having a temperature of 950 ° C. or higher or a thick steel plate having a thickness of about 20 to 150 mm (hereinafter collectively referred to as a steel plate) before finish rolling or during finish rolling. Applicable when cooling is performed by jets of water from the spray nozzle (for example, a cooling medium such as water or a mixture of water and air, referred to as “water” in the present invention) from the upper surface side and the lower surface side. It is.

  FIG. 1 shows an example of rolling equipment equipped with the cooling device of the present embodiment. As shown in FIG. 1, this rolling equipment is roughly composed of a rough rolling device 1, a finish rolling device 2, and a cooling device 3 according to the present invention. A heating furnace (not shown) is provided on the upstream side of the rough rolling apparatus 1, and the steel slab before rolling is heated to about 1200 ° C. to 1250 ° C. by this heating furnace. This heating facilitates rolling of the steel slab and prevents the occurrence of scratches in the narrow width processing. The rough rolling apparatus 1 is configured by arranging a plurality of rough rolling rolls in a line along the moving direction of the steel plate 4. FIG. 1 shows only the final rough rolling roll 1a of the rough rolling apparatus. The rough rolling device 1 is rolled until the steel slab before rolling has a thickness of about 30 to 50 mm.

  On the downstream side of the rough rolling apparatus 1, a descaling apparatus, an edger apparatus, a crop shear apparatus, a steel plate surface thermometer, and the like (not shown) are arranged.

  Furthermore, nozzle boxes 3a and 3b of the cooling device 3 according to the present invention are arranged in front of the finish rolling device 2. In FIG. 1, nozzle boxes 3a, 3b are arranged on the upper surface 4a side and the lower surface 4b side of the steel plate 4, and are configured so that a water jet can be injected from the upper surface 4a side and the lower surface 4b side. A plurality of spray nozzles 3 c are installed in the nozzle boxes 3 a and 3 b along the moving direction and the width direction of the steel plate 4.

  FIG. 1 shows a part of the finish rolling device 2. The finish rolling device 2 is configured by arranging a plurality of rolling stands in a line along the moving direction (rolling direction) of the steel plate 4. FIG. 1 shows the rolling roller 2a of the first stage rolling stand F1 and the rolling roller 2b of the second stage rolling stand F2.

  Next, the cooling device 3 according to the present invention will be described in detail. As shown in FIG. 1, the cooling device 3 according to the present invention includes nozzle boxes 3a and 3b provided with a plurality of spray nozzles 3c, supply pipes (not shown) for supplying water to the spray nozzles 3c, It is comprised from the pressurization pump (not shown) arrange | positioned in the upstream of piping, and the control apparatus (not shown) which controls a pressurization pump. This control device can freely set the supply pressure of water to the spray nozzle 3c for each spray nozzle.

  As shown in FIG. 2, the spray nozzle 3c constituting the cooling device may be a full cone spray nozzle in which the water jet has a conical shape (FIG. 2A), or an elliptic spray nozzle in which the water jet has an elliptical cone shape. (FIG. 2B), an oval spray nozzle in which the water jet has a long conical shape (FIG. 2C), or the spray nozzles shown in FIGS. 2A to 2C may be mixed. .

FIG. 3 is a plan view showing a relationship between an arrangement example of the spray nozzle 3c and a jet collision area caused by a water jet jetted from the spray nozzle toward the steel plate. Here, a jet collision area | region refers to the area | region where the full cone water jet injected from the spray nozzle collides directly with the upper surface or lower surface of a steel plate. Moreover, the example shown in FIG. 3 is an example using a full cone type spray nozzle. The same applies to FIGS. 5 to 8 below.
As shown in FIG. 3, the spray nozzles 3 c are arranged in four rows along the width direction of the steel plate 4 and are arranged in four rows along the inclination direction with respect to the width direction of the steel plate 4, for a total of 16 pieces. Is arranged. The inclination direction with respect to the width direction of the steel sheet in FIG. 3 is a direction inclined by 60 ° with respect to the width direction. Moreover, each spray nozzle 3c is arrange | positioned at substantially equal intervals. When the center points of the spray nozzles 3c arranged in this way are connected by a line, a substantially equilateral triangle is formed as shown in FIG.

  As shown by the dotted lines in FIG. 3, the jet collision regions M due to the water jets from the spray nozzles 3 c arranged as described above are in contact with each other along the width direction of the steel sheet and the inclination direction with respect to the width direction. In close contact with each other along the moving direction of the steel plate. In this way, the jet collision areas M are in contact with each other because the spray nozzles 3c are arranged at a predetermined interval, and the water jets ejected by the spray nozzles 3c have a solid cone shape with a certain spread angle. Therefore, as shown in FIG. 1, the water jet spreads to the area between the spray nozzles 3 c from the spray nozzle 3 c to the steel plate 4.

In order to bring the jet collision areas M into contact with each other as shown in FIG. 3 on the steel plate, the relationship between the maximum spread angle of the water jet and the distance from the tip of the spray nozzle to the steel plate may be controlled. For example, in the case where the area of the collision region of the water jet is not changed and the diameter of the circle of the jet collision portion is about 100 mm, the maximum spreading angle of the water jet is set as x as shown in FIG. When the distance from the tip of the spray nozzle to the steel plate is y, the spread angle and the distance may be adjusted so that y = 5933.4x− ^1.0155 .

  In the present embodiment, it is preferable to set the maximum spread angle of the water jet within a range of 10 ° to 30 °. By setting the maximum spread angle to 10 ° or more, there is no need to extremely narrow the interval between spray nozzles. Further, by setting the maximum spread angle to 10 ° or more, the jet collision areas do not become too narrow, and at least the jet collision areas can be brought into contact with each other. On the other hand, by setting the maximum spread angle to 30 ° or less, the velocity component in the vertical direction of the water jet with respect to the upper surface or the lower surface of the steel plate can be increased, and the ability of water to directly collide with the steel plate is improved. In addition, heat is efficiently exchanged between the water and the steel sheet, and the heat transfer coefficient is improved.

Moreover, in this embodiment, it is preferable to set the distance from a spray nozzle front-end | tip to a steel plate in the range of 200 mm or more and 700 mm or less.
By setting the distance to 200 mm or more, the nozzle and the steel plate do not interfere with each other even when a deformed steel plate is sent directly under the nozzle. Furthermore, by setting the distance to 700 mm or less, even when the nozzle is installed on the lower surface side of the steel plate, the distance between the nozzle and the steel plate can be reliably made to collide with the steel plate without being too far away. .

Also, water flow rate of the water jet by each spray nozzle is preferably in the ^2m 3 / ^{m 2} / min or ^more, and more preferably to 8m 3 / ^{m 2} / min or more. By setting the water density to 2 m ³ / m ² / min or more, a sufficient amount of water can be supplied to one side or the other side of the steel plate, and cooling is efficiently performed between the water and the steel plate. Heat transfer rate is improved.
Further, when water jets are jetted from both the upper surface side and the lower surface side of the steel plate, the water amount density on the upper surface side and the lower surface side may be made to coincide or may be set to different values. When setting to different values, it is preferable that the ratio of the water density (lower surface side / upper surface side) is in the range of 1 or more and 2 or less. On the upper surface side, when the water after colliding with the steel sheet as a water jet flows as a water stream on the steel sheet, a certain amount of cooling effect can be expected. can do.

  Control of the water density may be achieved by controlling the supply pressure of water supplied to each spray nozzle. Although the optimum range of the supply pressure varies depending on the performance of the spray nozzle, it may be set, for example, in the range of 0.005 MPa to 0.5 MPa.

3 are in contact with each other and are not overlapped. Therefore, the overlapping width of the jet collision areas M arranged along the width direction and the inclination direction of the steel plate 4 is 0% of the radius of each jet collision area M, respectively.
The radius of the jet collision area M is determined by the maximum spread angle of the water jet and the distance from the nozzle tip to the steel plate, but is preferably in the range of 60 mm to 180 mm, and more preferably in the range of 80 mm to 140 mm.

Hereinafter, the effects of the present embodiment will be described while pointing out problems that have not been solved by the prior art.
When cooling a hot steel plate with a water jet from a spray nozzle, the water may cause a boiling phenomenon when it comes into contact with the hot steel plate, and the steel plate may not be cooled efficiently. For example, when a large amount of water jets collide from each spray nozzle on the upper surface side of the steel plate, it is cooled in the jet collision area, but the cooling water that became the plate water after the collision is generated between this cooling water and the steel plate. There is also a concern that the water vapor is discharged without sufficiently contributing to cooling. Further, when there is a large amount of water on the plate, the water jet from each spray nozzle cannot sufficiently reach the surface of the steel plate, and sufficient cooling efficiency may not be obtained.
On the other hand, on the lower surface side of the thick steel plate, when a large amount of water jet is collided from each spray nozzle, the jet collision region is cooled, but the cooling water after the collision is the water vapor generated on the surface of the hot steel plate and Since it is separated from the steel plate by gravity and does not contribute to cooling, sufficient cooling efficiency may not be obtained.

  According to the cooling device of the present embodiment against the above phenomenon, the above-described phenomenon is alleviated by efficiently allowing the water jet to reach the steel plate surface in a certain region of the steel plate surface, and sufficient cooling capacity is stabilized. The cooling efficiency can be increased by securing it. That is, by injecting a water jet having a maximum spread angle of 10 ° or more and 30 ° or less, the vertical component in the water jet is increased, thereby enabling the water jet to efficiently collide with the steel sheet, and cooling. Can be performed efficiently.

  Further, when cooling is performed by injecting a water jet onto the steel sheet, the heat transfer coefficient, which is an index of the cooling capacity, tends to increase as the surface temperature of the steel sheet decreases as described above. That is, if the water jet is further injected in a state where the surface temperature of the steel sheet is lowered, the cooling capacity is further improved. By the way, since the steel plate heated to 950 ° C. or higher has a large internal energy, the surface temperature is temporarily lowered only by spraying water with a single spray nozzle, but it is recovered by the heat inside the steel plate. In some cases, the film heats up to the film boiling region temperature and the heat transfer rate cannot be increased.

According to the cooling device of the present embodiment against such a phenomenon, the plurality of jet collision areas on the steel plate are brought into contact with each other along the width direction of the steel plate and the direction inclined by 60 ° with respect to the width direction. As a result, the jet collision area is in close contact with each other along the moving direction of the steel sheet, which allows the water jet to collide continuously with the steel sheet and is cooled by one water jet. Since the steel plate can be cooled before the surface temperature is increased by the next water jet, the heat transfer rate can be increased and the cooling capacity of the steel plate can be further improved. More specifically, the heat transfer coefficient can be 6000 (W / m ² · K) or more.

  Moreover, the variation in the temperature in the width direction of the steel plate after cooling can be reduced by bringing the plurality of jet collision regions by the water jet on the steel plate into contact with each other along the width direction of the steel plate.

Therefore, according to the cooling apparatus of this embodiment, it becomes possible to cool efficiently the steel plate whose temperature is 950 degreeC or more. By incorporating this cooling device into a conventional rolling device, the delay time can be eliminated and the productivity of the rolled steel sheet can be greatly improved.
That is, the steel slab heated to about 1200 ° C. to 1250 ° C. by the heating furnace is rolled by the rough rolling apparatus shown in FIG. It is cooled to a temperature of about 1150 ° C. Then, by cooling the steel sheet by injecting water jets from the upper surface side and the lower surface side of the steel sheet by the cooling device, the steel sheet can be cooled to about 50 ° C. to 100 ° C. in a short time. The temperature can be about 1000 ° C. to 1050 ° C. Since the steel plate thus cooled to 1050 ° C. or less can be immediately sent to the next finish rolling process, the productivity of the rolling process can be improved. Moreover, since the temperature of the steel plate is about 1050 ° C. at the maximum, it becomes 1000 ° C. or less in the finish rolling process, and scale generation can be prevented.

Next, various arrangement examples of the spray nozzle applicable to the cooling device of the present embodiment will be described with reference to FIGS. In the arrangement examples shown in these drawings, conditions such as the maximum spread angle of the water jet, the distance from the nozzle tip to the steel plate, the water density, and the like are the same as those described in FIG.
FIG. 5 shows another example of the arrangement of the spray nozzles. The spray nozzles 3c in this example are arranged along the width direction of the steel plate 4 and arranged in four rows along the inclination direction with respect to the width direction of the steel plate, as in the case of FIG. In addition, the number of arrangement columns changes according to the installation space. The inclination direction with respect to the width direction of the steel plate in FIG. 5 is a direction inclined to a range of more than 60 ° and not more than 75 ° with respect to the width direction. Each spray nozzle 3c is arrange | positioned at equal intervals along the width direction of a steel plate, and is arrange | positioned at equal intervals along the inclination direction with respect to the width direction. When the center points of the spray nozzles arranged in this way are connected by a line, a substantially isosceles triangle is formed as shown in FIG.

  As shown by the dotted lines in FIG. 5, the jet collision regions M due to the water jets from the spray nozzles 3 c arranged as described above overlap with each other along the width direction of the steel plate, and in the inclined direction with respect to the width direction of the steel plate. Are in close contact with each other along the moving direction of the steel sheet. The overlapping width of the jet collision areas M along the width direction of the steel sheet is preferably in the range of 100% or less, exceeding 0% of the radius of each jet collision area M, and more preferably in the range of 0% or more and 40% or less. . The radius of the jet collision area M is determined by the maximum spread angle of the water jet and the distance from the nozzle tip to the steel plate, but is preferably in the range of 60 mm to 180 mm, and more preferably in the range of 80 mm to 140 mm.

  According to the arrangement of the spray nozzles 3c shown in FIG. 5, since the jet collision areas M overlap each other along the width direction of the steel plate, the water density of the water jet can be partially increased, and the cooling capacity Can be further improved.

  FIG. 6 shows another example of the arrangement of the spray nozzle 3c. As in the case of FIG. 3, the spray nozzles 3c in this example are arranged in four rows along the width direction of the steel plate 4, and are arranged in four rows along the inclination direction with respect to the width direction of the steel plate. 16 are arranged. The inclination direction with respect to the width direction of the steel sheet in FIG. 6 is a direction inclined to a range of 30 ° to 60 ° with respect to the width direction. The spray nozzles 3c are arranged at equal intervals along the width direction of the steel plate, and are arranged at equal intervals along the inclination direction with respect to the width direction of the steel plate. When the center points of the spray nozzles 3c arranged in this way are connected by lines, they become a substantially equilateral triangle or a substantially isosceles triangle.

  The jet collision areas M due to the water jets from the spray nozzles 3c arranged as described above are overlapped with each other along the width direction of the steel sheet and the inclination direction thereof, as indicated by the dotted lines in FIG. The overlapping width of the jet collision areas M along the width direction of the steel sheet is preferably in the range of 100% or less, more preferably in the range of 0% to 40%, exceeding 0% of the radius of each jet collision area. Further, the overlapping width of the jet collision areas M along the inclined direction of the width direction of the steel sheet is preferably in the range of 0% to 100%, exceeding 0% of the radius of each jet collision area. A range is more preferred. Note that the overlap width along the width direction and the overlap width along the inclination direction of the width direction may be matched or may be set to different values. The radius of the jet collision area M is the same as that in FIG.

  According to the arrangement of the spray nozzles 3c shown in FIG. 6, since the jet collision area M is overlapped along the width direction of the steel sheet and the inclination direction of the width direction, the water volume density of the water jet is partially increased. And the cooling capacity can be further improved.

  FIG. 7 shows still another example of the arrangement of the spray nozzle 3c. As in the case of FIG. 3, the spray nozzles 3c in this example are arranged in four rows along the width direction of the steel plate 4, and are arranged in four rows along the inclination direction with respect to the width direction of the steel plate. 16 are arranged. The inclination direction with respect to the width direction of the steel plate in FIG. 7 is a direction inclined to a range of 30 ° or more and less than 60 ° with respect to the width direction. The spray nozzles 3c are arranged at equal intervals along the width direction of the steel plate, and are arranged at equal intervals along the inclination direction with respect to the width direction. When the center points of the spray nozzles arranged in this way are connected by a line, a substantially isosceles triangle is formed as shown in FIG.

  As shown by the dotted lines in FIG. 7, the jet collision regions M due to the water jets from the spray nozzles 3 c arranged as described above are in contact with each other along the width direction of the steel plate and along the inclination direction with respect to the width direction of the steel plate. Are superimposed on each other. The overlapping width of the jet collision areas M along the inclination direction of the width direction of the steel sheet is preferably set to a range of 100% or less exceeding 0% of the radius of each jet collision area, and a range of 0% or more and 60% or less. More preferred. The radius of the jet collision area M is the same as that in FIG.

  According to the arrangement of the spray nozzles 3c shown in FIG. 7, since the jet collision areas are overlapped with each other along the width direction of the steel sheet, the water density of the water jet can be partially increased, and the cooling capacity can be further increased. Can be improved.

  FIG. 8 shows still another example of the arrangement of the spray nozzle 3c. The spray nozzles 3c in this example are arranged along the width direction of the steel plate 4 and arranged in four rows along the inclination direction with respect to the width direction of the steel plate, as in the case of FIG. The inclination direction with respect to the width direction of the steel sheet in FIG. 8 is a direction inclined to a range of more than 60 ° and not more than 80 ° with respect to the width direction. Each spray nozzle 3c is arrange | positioned at equal intervals along the width direction of a steel plate. Moreover, each spray nozzle 3c is arrange | positioned at equal intervals along the inclination direction with respect to the width direction of a steel plate. When the center points of the spray nozzles 3c arranged in this way are connected by a line, a substantially parallelogram is formed as shown in FIG.

  As shown by the dotted lines in FIG. 8, the jet collision area M due to the water jet from the spray nozzles 3 c arranged as described above is in contact with each other along the width direction of the steel plate and along the inclination direction with respect to the width direction of the steel plate. Touching the zigzag.

  According to the arrangement of the spray nozzles 3c shown in FIG. 8, the jet collision area M is in contact along the width direction of the steel sheet and is in contact with the zigzag along the inclination direction in the width direction. Since the contact time of the water jet with respect to the moving steel sheet becomes longer as a whole, and the moving speed of the steel sheet is relatively slow, the cooling capacity can be effectively increased.

(Experimental example 1)
An experiment for confirming the cooling capacity was performed using the test apparatus shown in FIG.
A test apparatus 11 shown in FIG. 9 includes a base 12, a test piece stage 13 on which the test piece S is reciprocated in the horizontal direction in the drawing on the base 12, and a nozzle fixed above the base 12. The box 14 is schematically configured. The nozzle box 14 is provided with 23 full cone spray nozzles 15. The spray nozzles 15 are arranged in four rows along the moving direction of the test piece stage 13, and are arranged in four to five rows along a direction orthogonal to the moving direction. The arrangement of the spray nozzles 15 is the same as that shown in FIG. The nozzle pitch in the width direction of the steel sheet was 100 mm, and the nozzle pitch in the rolling direction was 120 mm.

The maximum spread angle of the water jet by the spray nozzle 15 is set to 15 ° to 30 °, the distance L from the nozzle tip to the upper surface of the test piece is set to 200 mm to 490 mm, and the supply pressure to the nozzle is 0.36 MPa to 0.00. The water density is set to 4 MPa and the water density is set to 9.1 m ³ / m ² / min to 12.8 m ³ / m ² / min. Further, the moving speed of the test piece stage 13 is set in a range of 52 m / min to 82 m / min. And the width W of the injection area | region when a water jet is injected with respect to the test piece S is set to about 580 mm along the moving direction of the sample piece stage 13. The test piece stage 13 is configured to reciprocate the test piece S by folding it back outside the injection region. The cooling time for one pass is 0.42 to 0.67 seconds.

  The test piece S is a steel plate having a length of 300 mm, a width of 100 mm, and a thickness of 20 mm or 40 mm. And it is installed on the test piece stage 13 with one surface facing the nozzle box 14 side. The test piece S is previously heated to 1250 ° C.

  Using the above test apparatus, cooling experiments were performed under various cooling conditions. In the experiment, the test piece stage 13 was reciprocated on the base 12 and the test piece S was cooled by spraying a water jet m from each spray nozzle 15. And the surface temperature of the test piece S, the temperature of 1 mm depth from the surface, and the temperature of 9.5 mm depth from the surface were each measured over time. Detailed cooling conditions are shown in Table 1, and test results are shown in FIGS.

FIG. 10 shows the experimental results of Test Example 1. In FIG. 10, the horizontal axis is the cooling time, and the vertical axis is the temperature of the steel plate (test piece). As shown in FIG. 10, when the test piece stage is reciprocated six times and water jets are continuously injected onto the test piece 12 times in total, the temperature of the steel sheet (temperature of 1 mm and 9.5 mm depth from the surface) is 1250 ° C. It turns out that it falls to 400 degrees C or less.
FIG. 11 shows an enlarged view of FIG. As shown in FIG. 11, at the moment when the water jet collides, the temperature at a depth of 1 mm once suddenly decreases, but it can be seen that the temperature has increased again. In addition, it can be seen that the temperature decrease of 9.5 mm becomes larger after the water jet collides, and the decrease gradually becomes constant. The temperature decrease width at this time is approximately 43 ° C. The reason why the temperature at a depth of 9.5 mm decreases at a constant speed before and after the collision of the water jet is due to the effect of air cooling.
As is clear from FIG. 11, when the temperature of the steel plate surface (depth 1 mm) decreases rapidly, the heat inside the steel plate (depth 9.5 mm) is transferred to the steel plate surface, and the temperature near the surface recovers to some extent. In addition, it can be seen that the temperature inside the steel plate slightly decreases, and the temperature gradually decreases as a whole steel plate.

  12 and 13 show the analysis results of the experimental data in FIGS. 10 and 11. 12 and 13 are graphs showing the relationship between the heat transfer coefficient and the cooling time. FIG. 12 is a graph at the time of the first water jet collision (cooling), and FIG. 13 is a graph at the time of the second water jet collision (cooling).

  In the curve shown in FIG. 12, four peaks are recognized, and the first to fourth peaks in order from the left are the water in each of the spray nozzles arranged in four rows along the moving direction of the test piece. It corresponds to a jet collision. In addition, four peaks are recognized in the curve shown in FIG. 13. Among these, the first to third peaks in order from the left are the spray nozzles arranged in four rows along the moving direction of the test piece. This corresponds to the collision of water jets.

As shown in FIG. 12, as the cooling time increases, the maximum value of the peak of the curve gradually increases, and the heat transfer coefficient is 10,000 (W / m ² ) when the water jet from the spray nozzle in the last row collides.・ You can see that K) is exceeded. The reason why the heat transfer coefficient gradually increased in this way is considered to be that the surface temperature of the steel sheet gradually decreased as the surface temperature of the steel sheet collided successively with the water jets in the first to fourth rows. .

FIG. 13 is a graph showing the relationship between the heat transfer coefficient during the second cooling and the cooling time. Compared with FIG. 12, the heat transfer coefficient is already 10000 (W / m ² .multidot. It can be seen that it has reached 15000 (W / m ² · K) over K). This is because the temperature of the steel sheet decreased by nearly 40 ° C. by the first cooling.

  In FIG. 14, the initial steel plate temperature is set to 1100 ° C., the plate thickness is set to 40 mm, and the temperature distribution in the steel plate is calculated based on the results of FIGS. The relationship between the cooling time and the steel plate temperature is shown. In the figure, the result of half the plate thickness is shown. Moreover, the average temperature of each measurement temperature is calculated. As shown in FIG. 14, the temperature drop at the time of cooling increases as the portion is closer to the surface of the steel plate, and it can be seen that the same behavior as in FIGS. 10 and 11 is exhibited regardless of the thickness of the steel plate. Moreover, it turns out that an average fall temperature is about 43 degreeC and is a behavior almost the same as the case of FIG.

  FIG. 15 shows the analysis result of Test Example 1 in Table 1. FIG. 15 is a result of a cooling test in a high temperature region during reciprocation of the stage, in which the test apparatus shown in FIG. In FIG. 15, the horizontal axis represents the steel sheet temperature at a depth of 0.5 mm below the surface before the start of each cooling, and the vertical axis represents the amount of temperature drop due to each cooling.

  As shown in FIG. 15, it can be seen that the temperature drop amount reaches a maximum of 52 ° C. when the temperature of the steel sheet becomes 1050 ° C. or less. Further, even when the steel plate temperature is 1050 ° C. or higher, a temperature drop of about 38 ° C. is shown, and it can be seen that a sufficient cooling capacity of 40 ° C./second or higher is obtained at the cooling rate.

  Next, FIG. 16 shows the analysis result of Test Example 2 in Table 1. FIG. 16 shows a cooling test result in a high temperature range when a water jet is jetted from above the steel plate as shown in FIG. 9 and the stage is reciprocated. In FIG. 16, the steel plate temperature at a depth of 0.5 mm below the surface before the start of each cooling is taken on the horizontal axis, and the temperature drop due to cooling each time is taken on the vertical axis.

As shown in FIG. 16, when a water jet is injected from the upper surface side of a steel plate, it turns out that the amount of temperature drops of a steel plate has reached 66 degrees C at the maximum. This result shows that the cooling efficiency is superior to the case of FIG. This is because when the water jet is jetted from the upper surface side of the steel plate, the water after colliding with the upper surface becomes a water flow and flows on the upper surface of the steel plate, and this water on the plate contributes to the cooling effect. Conceivable. On the other hand, when the water jet is jetted from the lower surface side of the steel plate as shown in FIG. 15, the water that collided with the lower surface is immediately separated from the lower surface of the steel plate by the action of gravity, so the cooling capacity is considered to be slightly reduced. It is done.
15 and 16, according to this test example, a cooling rate of 40 ° C./second or more is ensured by one cooling, and before finish rolling, for example, in a very short section between about 1 and 2 table rolls. This shows that the temperature can be adjusted simply by installing a cooling device.

  From the results of FIG. 15 and FIG. 16 described above, in order to balance the cooling capacity on the upper surface side and the lower surface side when water jets are jetted simultaneously from the upper surface side and the lower surface side of the steel sheet, the cooling capacity on the upper surface side is slightly It should be suppressed. Specifically, the ratio (lower surface side / upper surface side) of the water amount density of the spray nozzle disposed on the upper surface side of the steel sheet to the water amount density of the spray nozzle disposed on the lower surface side is in the range of 1 or more and 2 or less. Set it.

  Next, FIG. 17 shows the analysis result of Test Example 3 in Table 1. FIG. 17 shows the results of a cooling test in a high temperature region during reciprocation of the stage, with the test apparatus shown in FIG. In FIG. 17, the horizontal axis represents the steel sheet temperature at a depth of 0.5 mm below the surface before the start of each cooling, and the vertical axis represents the amount of temperature drop due to cooling each time.

  As shown in FIG. 17, it is understood that a temperature drop of 21 ° C. is achieved at the minimum regardless of the temperature of the steel sheet, and a sufficient cooling capacity of 40 ° C./second or more is obtained at the cooling rate.

  Next, FIG. 18 shows the analysis result of Test Example 4 in Table 1. FIG. 18 shows the results of a cooling test in a high temperature region when the stage is reciprocated by causing a water jet to be jetted from above the steel plate as shown in FIG. In FIG. 18, the steel plate temperature at a depth of 0.5 mm below the surface before the start of each cooling is taken on the horizontal axis, and the temperature drop due to cooling each time is taken on the vertical axis.

  As shown in FIG. 18, even when the water jet is jetted from the upper surface side of the steel plate, it can be seen that the temperature drop is at least 24 ° C. regardless of the temperature of the steel plate. . It can be seen that the temperature drop of the steel sheet reaches 34 ° C. at the maximum. This result shows that the cooling efficiency is superior to the case of FIG. As in the case of FIGS. 15 and 16, when a water jet is jetted from the upper surface side of the steel plate, the water after colliding with the upper surface flows as a water flow on the upper surface of the steel plate. This is considered to contribute to the cooling effect.

  From the results of FIG. 17 and FIG. 18 described above, even when a cooling device is installed between the first rolling stand F1 and the second rolling stand F2 of the finish rolling device, water is simultaneously applied from the upper surface side and the lower surface side of the steel plate. When jetting a jet, it is understood that the cooling capacity on the upper surface side needs to be slightly suppressed in order to balance the cooling capacity on the upper surface side and the lower surface side. Specifically, the ratio of the water density on the upper surface side to the lower surface side (lower surface side / upper surface side) may be set in the range of 1 to 2.

FIG. 19 shows the results of Test Example 5. In Test Example 5, a cooling experiment was performed with the nozzle conditions the same as in Test Examples 3 and 4, and the moving speed of the test piece was the same as in Test Examples 1 and 2.
It can be seen that even under the conditions of FIG. 19, a temperature drop of 40 ° C. or higher is almost achieved. Therefore, it has been found that even when the distance from the nozzle tip to the steel plate is about 490 mm, sufficient cooling capacity can be obtained by adjusting the nozzle spreading angle.

(Experimental example 2)
The test apparatus used in Experimental Example 1 was used as the cooling apparatus of Example 1.
The cooling device of Comparative Example 1 was assembled in the same manner as the cooling device of Example 1 except that the nozzle pitch in the rolling direction was 200 mm.

  Using the cooling devices of Example 1 and Comparative Example 1, a cooling experiment of the rolled steel sheet was performed. A rolled steel plate having a width of 1500 mm, a length of 80 m, and a thickness of 40 mm was prepared, and the steel plate was heated to 1100 ° C. Then, the temperature of the steel plate was measured while passing under the cooling device at a plate passing speed of 45 m / min. The nozzle conditions were the same as those of Test Example 1 in Table 1. From the measurement results, the behavior of the heat transfer coefficient was investigated. The results are shown in FIGS.

  As shown in FIG. 20, in the cooling device of Example 1, it can be seen that a peak of the heat transfer coefficient appears every time the steel sheet passes through the nozzle row, and this peak value gradually increases. Moreover, in the valley part between peaks, the reduction | decrease of a heat transfer rate has decreased, and it is thought that this has contributed to the raise of a peak value. The reason for the decrease in the heat transfer coefficient in the valley between the peaks is that the jet collision area is in contact with each other along the inclined direction with respect to the width direction of the steel sheet, so that the jet collision area is along the rolling direction. This is probably because the number of continuous parts increased, and the steel sheet was constantly cooled by the water jet, and the heat transfer coefficient was increased even in the valleys.

On the other hand, as shown in FIG. 21, in the cooling device of Comparative Example 1, as in Example 1, the peak of the heat transfer coefficient appears every time the steel sheet passes through the nozzle row. Thus, it can be seen that the peak value does not gradually increase and shows a substantially constant peak value. Further, in the valley portion between the peaks, the phenomenon of heat transfer coefficient is large and almost 0, which is considered to be a cause of the peak value not being increased.
The drop in the heat transfer coefficient in the valley between the peaks is large because the jet collision area is separated along the rolling direction of the steel sheet, so there is a time during which the water jet does not collide. In this case, it is considered that the surface temperature of the steel plate once cooled again rises due to the heat inside the steel plate, resulting in a low heat transfer coefficient.

  From the above, it can be seen that it is necessary to increase the heat transfer coefficient that the jet collision area is always in contact along the inclination direction with respect to the width direction of the steel sheet.

(Experimental example 3)
A full cone type spray nozzle was prepared, and this spray nozzle was arranged in arrangement patterns A to D. The distance from the nozzle tip to the upper surface of the steel sheet is in the range of 150 mm to 800 mm, the water density is in the range of 3 m ³ / m ² / min to 8 m ³ / m ² / min, and the maximum spread angle of the water jet is 5 ° to A range of 35 ° was set. Thus, the cooling devices of Examples 2 to 10 and Comparative Examples 2 to 5 were assembled.

The spray nozzle arrangement pattern A is the same as the arrangement pattern shown in FIG. 3, and the radius of the jet collision area is 50 mm. The arrangement pattern B is the same arrangement as the arrangement pattern shown in FIG. 5, wherein the radius of the jet collision area is 50 mm, the overlapping width in the width direction is 20% of the radius of the jet collision area, and the inclination with respect to the width direction is In this arrangement, the direction angle is 64 °.
The arrangement pattern C is the same arrangement as the arrangement pattern shown in FIG. 7, the angle of the inclination direction with respect to the width direction is 45 °, the radius of the jet collision area is 50 mm, and the overlapping width in the inclination direction is jet collision. The arrangement is 60% of the radius of the region.
The arrangement pattern D is the same arrangement as the arrangement pattern shown in FIG. 6, wherein the radius of the jet collision area is 50 mm, the overlap width in the width direction is 20% of the radius of the jet collision area, and the inclination with respect to the width direction is In this arrangement, the direction angle is 45 °, and the overlapping width in the inclined direction is 70% of the radius of the jet collision area.

  Using the cooling devices of Examples 2 to 10 and Comparative Examples 2 to 5, cooling experiments on rolled steel sheets were performed. A rolled steel plate having a width of 1500 mm, a length of 80 m, and a thickness of 40 mm was prepared, and the steel plate was heated to 1000 ° C. to 1200 ° C. Then, the temperature of the steel plate was measured while passing under the cooling device at a plate passing speed of 50 m / min. The results are shown in Tables 2 and 3.

  As shown in Tables 2 and 3, according to Examples 2 to 10, it can be seen that the cooling capacity and uniformity are excellent.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the arrangement of the spray nozzle has been described by taking a full cone spray nozzle as an example. However, the present invention is not limited to this, and an elliptic spray nozzle or an oval spray nozzle may be applied.

  Further, in the steel sheet cooling device of the present invention, a pair of draining spray nozzles are disposed on the upstream side and the downstream side in the moving direction of the steel sheet, and the plurality of spray nozzles are disposed between the draining spray nozzles. Also good. For example, a flat spray nozzle may be used as the draining spray nozzle. With this configuration, the water flow from the plurality of spray nozzles is blocked by the water jet from the spray nozzle for draining, and drained along the width direction of the steel plate without flowing along the moving direction of the steel plate or the opposite direction. Therefore, the steel sheet can be cooled more uniformly.

4 ... Steel plate 4a ... Upper surface (one surface)
4b ... Bottom (one side)
3c ... Spray nozzle M ... Jet collision area

Claims (9)

The steel plate is sprayed with a substantially full conical water jet from a plurality of spray nozzles arranged along the moving direction of the steel plate and the width direction of the steel plate on one surface of the steel plate having a thickness of 20 mm or more moved in one direction. In the steel sheet cooling device that cools
Having at least one rolling stand on the downstream side of the cooling device;
The water density of the water jet on the one surface is 2 m ³ / m ² / min or more,
The shape of the water jet is a full cone shape, a full elliptical cone shape, a long cone shape or a mixture of these,
The jet collision areas of the water jets on the one surface are at least mutually continuous along the width direction of the steel sheet,
The plurality of spray nozzles are disposed on both sides of the upper surface and the lower surface of the steel plate so as to be continuous with each other at least along the inclination direction with respect to the width direction of the steel plate,
The peak of the heat transfer coefficient when the water jet collides with the steel plate is 6000 (W / m ² · K) or more at the maximum,
A steel sheet cooling apparatus characterized by controlling a surface temperature to 950 ° C. or higher when reheating after cooling is stopped.   The maximum spreading angle of the substantially jet-shaped water jet is in the range of 10 ° or more and 30 ° or less, and the surface temperature when reheated after cooling is stopped is controlled to 950 ° C. or more. The steel sheet cooling device according to claim 1.   The distance from the spray nozzle tip to the one surface is in the range of 200 mm to 700 mm, and the surface temperature when reheated after cooling is stopped is controlled to 950 ° C or higher. Or the cooling device of the steel plate of Claim 2.   The surface temperature when the plurality of spray nozzles are arranged so that the jet collision areas of the water jets on the one surface are in close contact with each other along the moving direction of the steel sheet, and the reheating is performed after the cooling is stopped. The steel sheet cooling device according to any one of claims 1 to 3, wherein the temperature is controlled to 950 ° C or higher.   The plurality of spray nozzles are arranged so that the jet collision areas arranged along the width direction of the steel plates are overlapped with an overlap width in a range of 0% to 100% of the radius of each jet collision area. The steel sheet cooling device according to any one of claims 1 to 4, wherein the surface temperature when the recuperation is stopped after cooling is stopped is controlled to 950 ° C or higher.   The plurality of spray nozzles are overlapped so that jet collision areas arranged along an inclination direction with respect to the width direction of the steel sheet overlap with each other with an overlap width in a range of 0% to 100% of the radius of each jet collision area. The surface temperature according to any one of claims 1 to 5, wherein the surface temperature is controlled to be 950 ° C or higher when reheated after cooling is stopped. A cooling device for steel plates at 950 ° C or higher.   The ratio of the water density of the spray nozzle arranged on the upper surface side and the water density of the spray nozzle arranged on the lower surface side (lower surface side / upper surface side) is in the range of 1 to 2, and cooling is stopped. The steel sheet cooling device according to claim 6, wherein the surface temperature when reheated after that is controlled to 950 ° C or higher.   8. The water density in each spray nozzle is set to the same value, and the surface temperature when reheated after cooling is stopped is controlled to 950 ° C. or higher. The steel plate cooling device according to any one of the above. A pair of draining spray nozzles is arranged on the upstream side and the downstream side in the moving direction of the steel plate,
The plurality of spray nozzles are disposed between the spray nozzles for draining water, and the surface temperature when reheated after cooling is stopped is controlled to 950 ° C or higher. The steel sheet cooling device according to claim 8.

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