JP2002172414A - Method and apparatus for draining steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the quality of material and to improve the yield ratio by preventing local overcooling of a steel plate, improving temperature controllability, and restraining temperature unevenness by immediately all at once eliminating the cooling medium staying on the top side of a high temperature steel plate after finishing of cooling. SOLUTION: In the draining method of the steel plate 5 by which residual cooling water staying on the steel plate 1 is eliminated after cooling the steel plate 1 by spraying the cooling water toward the steel plate 5 on the rolling line 1 from the cooling apparatus 4 located along the rolling line 1, fluid is sprayed to the steel plate 5 from a draining nozzle group 6 having a plurality of nozzles 7 immediately after suspending the injection of cooling water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for draining a steel sheet, and more particularly, to cooling a hot steel sheet during or after hot rolling with a cooling medium such as cooling water. The present invention relates to a method and an apparatus for draining a steel sheet, which can drastically reduce the residence time of the residual cooling water on the upper surface of the steel sheet by immediately draining the residual cooling water on the upper surface of the steel sheet immediately after the stop. .

[0002]

2. Description of the Related Art During hot rolling, between hot rolling mills, or after rolling, cooling water is used as a cooling medium to lower the temperature of a high-temperature steel sheet to produce a steel sheet having desired characteristics. However, the residual cooling water remaining on the upper surface of the hot steel sheet after cooling causes a decrease in temperature controllability, non-uniformity of material due to temperature unevenness, and defective shape of the steel sheet due to vertical temperature difference. Sometimes.

[0003] For this reason, drainage of the residual cooling water remaining on the upper surface of the high-temperature steel plate has been actively performed conventionally.

A technique for draining water on the upper surface of a high-temperature steel plate is disclosed in Japanese Patent Publication No. 59-13573 and Japanese Patent Application Laid-Open No. 9-141322.
JP, JP-A-11-123439, JP-A-11-123439
The following technology is disclosed in Japanese Patent Publication No. -138207.

[0005] The prior art 1 disclosed in Japanese Patent Publication No. 59-13573 discloses a hot-rolled steel material in which a cooling liquid is injected from a plurality of cooling banks into a hot-rolled steel material sent from a finishing mill to cool the hot-rolled steel material. In the cooling device for steel materials, between the plurality of cooling banks, a draining nozzle for ejecting high-pressure fluid toward the hot-rolled steel material is provided, so that the downstream side is not affected by the cooling liquid upstream of the nozzle. The draining nozzle is disposed.

The prior art 2 disclosed in Japanese Patent Application Laid-Open No. 9-141322 discloses that a mixture of water and air is jetted from a drain nozzle during hot-run cooling of a continuous hot strip rolling line, and stays on a steel strip. It is characterized by eliminating residual cooling water.

A prior art 3 disclosed in Japanese Patent Application Laid-Open No. 11-123439 is a drainer spray device used for removing residual cooling water remaining on a steel sheet conveyed from a line table. The water supply header is provided so as to cross the line table above, and a plurality of side spray nozzles for injecting high-pressure water onto the steel plate from the line table toward the outside in a direction perpendicular to the line are provided on the water supply header. It is a feature.

The prior art 4 disclosed in Japanese Patent Application Laid-Open No. H11-138207 discloses that two types of fluid injection nozzles having different injection widths in the width direction of the steel sheet are set so that the injection direction is directed to one edge side of the steel sheet. And, a plurality of fluid ejection nozzles having a larger ejection width are arranged so as to be located on the upstream side in the ejection direction,
A fluid is ejected from the plurality of fluid ejection nozzles onto the upper surface of the steel plate, and accompanying the injected fluid, residual cooling water remaining on the upper surface of the steel plate is removed from one edge of the upper surface of the steel plate to the other edge. Is what you do.

[0009]

SUMMARY OF THE INVENTION The present invention solves the problem of the draining method under the following circumstances.

[0010] For example, in the case where the steel sheet is stopped before the rolling mill to cool the steel sheet, even if the rolling is performed after cooling for a predetermined time, the rolling is immediately performed when the previous steel sheet is still rolling. Cannot do it.

In recent years, in particular, the rolling pitch has been shortened due to the increase in production efficiency, and the demand for high-grade steel sheets has led to the demand for high-temperature steel sheets to be cooled to a predetermined temperature before rolling, for example in controlled rolling. Since the time required for cooling is shorter than the time required for rolling, a situation occurs where the steel sheet cooled before the rolling mill stops. At this time, if the cooling water remaining on the upper surface of the steel plate particularly when the upper surface of the steel plate is cooled is left as it is, it causes supercooling, temperature unevenness, or poor shape.

Therefore, in a steel sheet cooled by a cooling device using a cooling medium such as cooling water installed on the upstream side of the finishing mill, residual cooling water staying on the upper surface of the steel sheet is removed.
Immediately after the completion of cooling, it is necessary to drain (purge) all at once.

However, the prior arts 1 to 4 are all
This is a technique for draining residual cooling water staying on the upper surface of the hot steel plate passing therethrough, and is not suitable for removing the residual cooling water on the upper surface of the stopped steel plate.

Accordingly, an object of the present invention is to remove residual cooling water that is stopped or stays on the upper surface of a steel plate that is oscillating (oscillating) at a certain place.
Immediately after cooling is complete,
An object of the present invention is to provide a method and an apparatus for draining a steel sheet, which can significantly reduce the residence time of the residual cooling water on the upper surface of the steel sheet.

[0015]

According to the first aspect of the present invention,
Injecting cooling water from the cooling device installed along the rolling line toward the steel sheet on the rolling line, cooling the steel sheet, and removing residual cooling water remaining on the upper surface of the steel sheet, In the draining method, the injection of the cooling water to the steel plate is stopped, and immediately thereafter, fluid is injected from the drainage nozzle group having a plurality of nozzles toward the steel plate, and the residual cooling that remains on the steel plate upper surface. It is characterized by eliminating water.

The invention according to claim 2 is characterized in that the draining nozzle group is provided orthogonal to the rolling line and on one side of the rolling line.

According to a third aspect of the present invention, in the method of the first aspect, the fluid may be 40
It is characterized by having a flow velocity of 3 m / sec or more at a position 1 mm away from the upper surface of the steel plate at a temperature of 0 ° C. or more.

The invention described in claim 4 is characterized in that the steel sheet is oscillated in the direction of the rolling line with a stroke equal to or longer than the nozzle interval of the draining nozzle group.

According to a fifth aspect of the present invention, the draining nozzle group is oscillated in the direction of the rolling line with a stroke equal to or longer than the nozzle interval of the draining nozzle group.

According to a sixth aspect of the present invention, the cooling device and the draining nozzle group are divided into a plurality of blocks in the direction of the rolling line, and the cooling device and the draining nozzle group of each block are set to the length of the steel plate. On / off control in accordance with

According to a seventh aspect of the present invention, there is provided a draining nozzle group installed on one side of a rolling line, and a steel sheet oscillation means, wherein a cooling device for the steel sheet is installed in the rolling line, and the draining nozzle group is provided. Has a plurality of nozzles orthogonal to the rolling line, wherein the steel sheet oscillation means, with a stroke equal to or greater than the nozzle interval of the draining nozzle group, to oscillate the steel sheet in the rolling line direction. It has.

The invention according to claim 8 is provided with a draining nozzle group installed on one side of a rolling line, and nozzle oscillation means, wherein a cooling device for a steel plate is installed in the rolling line, and the draining nozzle group is provided. Has a plurality of nozzles orthogonal to the rolling line, and the nozzle oscillation means causes the draining nozzle group to oscillate in the rolling line direction with a stroke equal to or longer than the nozzle interval of the draining nozzle group. It is characterized by the following.

According to a ninth aspect of the present invention, the cooling device and the draining nozzle group are divided into a plurality of blocks in the rolling line direction, and the cooling device and the draining nozzle group of each block have a length of the steel plate. On / off control in accordance with

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method for draining a steel sheet according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic plan view showing a draining method of the present invention, FIG. 2 is a plan view showing a draining state by a draining nozzle group, and FIG. 3 is a view in the direction A of FIG.

In the following description, air will be described as an example of the draining fluid to be sprayed onto the steel plate. However, a fluid other than air, for example, an inert gas may be used.

In FIGS. 1 to 3, 1 is a rolling line, 2 is a rough rolling mill provided on the rolling line 1, and 3 is a rolling mill.
The finishing mill 4 provided on the rolling line 1 downstream of the rough mill 2 is a water-cooled cooling device provided along the rolling line 1 between the rough mill 2 and the finishing mill 3. .
The cooling device 4 is divided into a plurality of blocks (four blocks 4A to 4D in this example) along the rolling line 1 and is cooled toward the steel sheet 5 on the rolling line 1 which is roughly rolled by the rough rolling mill 2. Water is sprayed to cool the steel plate 4 to a predetermined temperature. Reference numeral 6 denotes a draining nozzle group for removing residual cooling water remaining on the steel plate 5, and is installed orthogonal to the rolling line 1 and on one side of the rolling line 1.

As shown in FIG. 2, the draining nozzle group 6
It has a plurality of air injection nozzles 7 and a plurality of blocks (four blocks 6 in this example) corresponding to each block of the cooling device 4.
A to 6D), and air is supplied from an air receiver 8 via a header tube 9.

According to the present invention, the steel plate is drained as follows.

When the steel sheet 5 roughly rolled by the rough rolling mill 2 moves on the rolling line 1 to the cooling device 4 and stops, cooling water is injected from the cooling device 4 toward the steel sheet 5 according to predetermined conditions. Is done. Immediately after the steel sheet 5 is cooled to the predetermined temperature and the injection of the cooling water is stopped, air is injected from the one side of the steel sheet 5 toward the upper surface of the steel sheet 5 from the drain nozzle group 6 immediately. . Thereby, the residual cooling water staying on the steel plate 5 is simultaneously removed from the upper surface of the steel plate 5.

After the cooling of the steel plate 5 is completed,
Immediately, the residual cooling water staying on the upper surface of the steel plate 5 is simultaneously removed from the upper surface of the steel plate 5, so that supercooling, temperature unevenness,
Alternatively, occurrence of a shape defect can be prevented.

The draining nozzle group 6 may be installed in parallel with the upper surface of the steel plate 5. However, if the air injection angle from the nozzle 7 is zero, the flow velocity drops greatly, so as shown in FIG. It is preferable to incline downward by an angle (θ) with respect to the upper surface of the steel plate 5 on the rolling line (conveying roller). The draining nozzle group 6 may be constituted by slit nozzles parallel to the rolling line 1 in addition to the plurality of nozzles 7.

In order to more reliably drain the residual cooling water remaining on the upper surface of the steel plate, the flow velocity of the air injected from the drainage nozzle group toward the steel plate is set to be 1 mm away from the upper surface of the steel plate at a temperature of 400 ° C. or higher. The position may be adjusted to 3 m / sec or more. This is because, in a steel plate having a temperature of 400 ° C. or higher, the residual cooling water on the upper surface of the steel plate is in a film boiling state, so that drainage is possible even with a slight flow rate of air.

FIG. 4 is a diagram showing a case where air is jetted from a nozzle having a diameter of 7 mm toward a steel plate having a surface temperature of 400 ° C. or more to drain the residual cooling water remaining on the upper surface of the steel plate. It is a graph which shows the relationship between the injection distance and the flow velocity of the air at 1 mm from the steel plate surface for every air injection pressure.

In FIG. 4, the solid line indicates that the air injection pressure is 0.1
MPa, the dotted line is the result of the air injection pressure of 0.2 MPa, and the dashed line is the result of the air injection pressure of 0.3 MPa,
A mark on each line indicates that draining is possible, and a mark X indicates that draining is not possible.

As is apparent from FIG. 4, the flow velocity of the air jetted from the draining nozzle toward the steel plate having a temperature of 400 ° C. or more was 3 m / m at a position 1 mm away from the upper surface of the steel plate.
It can be seen that if the adjustment is made at least sec, the residual cooling water staying on the upper surface of the steel sheet can be reliably removed.

The width of the steel sheet from which the residual cooling water can be removed changes depending on the injection pressure of the air from the nozzle. That is, in order to eliminate the residual cooling water on the upper surface of the steel plate having a width of 5 m, it is necessary to adjust the injection pressure of the air to 0.3 MPa. It turns out that 0.1 MPa is good.

When the steel plate 5 is drained as described above, the air from the air injection nozzles 7 does not sufficiently spread on the steel plate 5 on the installation side of the drainage nozzle group 6.
For this purpose, the steel plate 5 is preferably oscillated in the direction of the rolling line 1 with a stroke longer than the interval between the adjacent nozzles 7. The oscillation speed is controlled in accordance with the target draining time, which is performed by controlling the steel sheet transport roller in line 1 according to a command from a controller (not shown) as a nozzle oscillation means. .

Instead of oscillating the steel plate 5,
The draining nozzle group 6 can be moved in the rolling line 1 direction,
The draining nozzle group 6 may be oscillated in the direction of the rolling line 1. Also in this case, the oscillation speed is controlled according to the target draining time. This is performed by controlling the moving means (not shown) of the draining nozzle group 6 in accordance with a command from a controller (not shown) as nozzle oscillation means.

FIG. 5 shows the relationship between the distance in the rolling line direction at each distance in the width direction of the steel sheet and the flow velocity of air at 1 mm from the steel sheet surface when the distance between the air injection nozzles having a diameter of 7 mm is 500 mm. It is a graph shown for every distance of a steel plate width direction. The distance in the steel sheet width direction is a distance from the steel sheet edge on the side where the draining nozzle group is installed. The air injection pressure from the nozzle is 0.4 MPa.

In FIG. 5, A indicates that the distance in the steel sheet width direction is 0.25.
m, B: steel plate width direction distance: 0.50 m, C: steel plate width direction distance: 1.0 m, D: steel plate width direction distance: 2.0 m
m and E are steel plate width direction distances of 3.0 m, F is steel plate width direction distance of 4.0 m, and G is steel plate width direction distance of 5.0 m.

As is apparent from FIG. 5, the flow velocity of the jet air at the central portion between the nozzles close to the air jet nozzle is almost zero, and it is understood that the drainage property is extremely poor in this portion. Therefore, it is effective to oscillate the steel plate 5 in the direction of the rolling line 1 or to oscillate the drainage nozzle group with a stroke equal to or longer than the interval between the adjacent nozzles 7 in order to obtain good drainage.

As shown in FIG. 1, the cooling device 4 and the draining nozzle group 6 are divided into a plurality of blocks in the direction of the rolling line 1, and the cooling device (4A to 4D) and the draining nozzle group (6A to 6D) of each block are divided. Is turned on / off according to the length of the steel plate 5, it is not necessary to use extra cooling water and injection air, and energy can be saved.

[0044]

(Embodiment 1) Next, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 6 is a schematic plan view showing a first embodiment of the present invention.

As shown in FIG. 6, in the first embodiment, a rough rolling mill 2 and a finish rolling mill are used in a plate mill in which a rolling line 1 is provided with two rolling mills, a rough rolling mill 2 and a finishing rolling mill 3. The water draining nozzle group 6 is installed at the same position as the water-cooling type cooling device 4 installed between the device 3.

The cooling device 4 has a length of 20 m and is installed from a position 10 m downstream of the rough rolling mill 2. The distance between the rough rolling mill 2 and the finishing rolling mill 3 is 50 m. The cooling device 4 is divided into four first, second, third, and fourth blocks 4A, 4B, 4C, and 4D from the upstream side every 5 m. The draining nozzle group 6 also has the first, second,
The third and fourth blocks 6A, 6B, 6C and 6D are divided into four. The air injection nozzle 7 of each block is
Rolling line 1 with a diameter of 7 mm and at 500 mm intervals
On one side, 10 per block, 4 blocks total 4
The air receivers 8 are provided, and air is supplied from the air receivers 8 via the header pipes 9. The horizontal distance between the nozzle 7 and the transport roller is 200 mm, and the vertical distance is 2 mm.
50 mm, and the inclination angle (θ) was 2 degrees.

In the first embodiment configured as described above, the steel plate was drained as follows.

The high-temperature steel sheet 5A subjected to rough rolling by the rough rolling mill 2 was carried into the rolling line 1. The high-temperature steel plate 5A has an average surface temperature of about 910 ° C. and a size of about 80 m in thickness.
m, a width of about 4.5 m, and a length of about 7.5 m. The steel plate 5A was inserted into the third and fourth blocks 4B and 4C of the cooling device 4 and was cooled to lower the average temperature by 80 ° C.
Immediately after the cooling was stopped, air was sprayed from the nozzles 7 of the third and fourth blocks 6B and 6C of the draining nozzle group 6 at an injection pressure of 0.5 MPa toward the upper surface of the steel plate 5A. During cooling and draining, the steel plate 5A was oscillated in the direction of the rolling line 1 with a stroke of 600 mm.

The steel plate 5A on the opposite side from the tip of the nozzle 7
The distance to the edge was about 5 m, and the flow rate of the jet air at a position 1 mm from the upper surface of the steel plate 5A during non-rolling was 7.2 m / sec on average by Pitot tube measurement.

As a result of draining the steel plate 5A in this manner, the residual cooling water remaining on the upper surface of the steel plate 5A was almost completely removed from the upper surface of the steel plate 5A about 8 seconds after the drainage was performed. The average surface temperature of the steel sheet 5A after reheating is about 828 ° C., and the variation of the temperature excluding the edge is up to 15 ° C.
Met. As a result of finish rolling of the steel sheet 5A by the finish rolling mill 3, there was no problem in shape, material and the like.

Subsequently, another high-temperature steel sheet 5B subjected to rough rolling by the rough rolling mill 2 was carried into the rolling line 1. This high-temperature steel plate 5B has a surface average temperature of 870 ° C. and measures dimensions of about 50 mm in thickness, about 4.6 m in width, and about 12.4 m in length.
Met. The steel plate 5B was inserted into the second to fourth blocks 4A to 4D of the cooling device 4 and cooled to reduce the average temperature by 50 ° C. Immediately after the cooling was stopped, air was sprayed from the nozzles 7 of the first to fourth blocks 6A to 6D of the draining nozzle group 6 at an injection pressure of 0.5 MPa toward the upper surface of the steel plate 5B. 600m during cooling and draining
The steel plate was oscillated in the direction of the rolling line 1 with a stroke of m.

As a result of draining in this manner,
About 8 seconds after the draining, the residual cooling water staying on the upper surface of the steel plate 5B was almost completely wiped off from the upper surface of the steel plate. Also,
The average surface temperature of the steel sheet 5B after reheating was about 821 ° C., and the variation in temperature excluding the edge was 17 ° C. at the maximum. As a result of finish rolling of this steel plate 5B by the finish rolling machine 3,
There was no problem in shape, material, etc.

The present invention is not limited to the above-described embodiment. For example, in this draining apparatus, for a short high-temperature steel plate, for example, the first and second blocks and the third and fourth blocks simultaneously drain one sheet at a time. It is also possible. (Embodiment 2) Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 7 is a schematic plan view showing a second embodiment of the present invention.

As shown in FIG. 7, the second example is a rough rolling mill 2 and a finishing mill 2 in a plate mill provided with two rolling mills, a rough rolling mill 2 and a finishing rolling mill 3, on a rolling line 1. The draining nozzle group 6 is installed at the same position as the water-cooled cooling device 4 installed between the mill 3.

The cooling device 4 has a length of 20 m and is installed from a position 10 m downstream of the rough rolling mill 2. The distance between the rough rolling mill 2 and the finishing rolling mill 3 is 50 m. The cooling device 4 is divided into four first, second, third, and fourth blocks 4A, 4B, 4C, and 4D from the upstream side every 5 m. The draining nozzle group 6 also has the first, second,
The third and fourth blocks 6A, 6B, 6C and 6D are divided into four. The air injection nozzle 7 of each block is
Rolling line 1 with a diameter of 7 mm and at 500 mm intervals
On one side, 10 per block, 4 blocks total 4
The air receivers 8 are provided, and air is supplied from the air receivers 8 via the header pipes 9. In the second embodiment, the draining nozzle group 6 can be oscillated in the rolling line direction with a stroke of 600 mm.

In the second embodiment configured as described above, the steel plate was drained as follows.

The high-temperature steel sheet 5C subjected to rough rolling by the rough rolling machine 2 was carried into the rolling line 1. The high-temperature steel plate 5C had an average surface temperature of about 930 ° C. and dimensions of about 90 mm in thickness, about 4.5 m in width, and about 6.2 m in length. This steel plate 5C is inserted into the third and fourth blocks 4B and 4C of the cooling device 4,
Cooling was performed to lower the average temperature by 100 ° C. Immediately after the cooling was stopped, air was injected from the nozzles 7 of the third and fourth blocks 6B and 6C of the draining nozzle group 6 at an injection pressure of 0.5 MPa toward the upper surface of the steel plate 5C. When draining, 6
The draining nozzle group 6 was oscillated in the direction of the rolling line 1 with a stroke of 00 mm.

The steel plate 5C on the opposite side from the tip of the nozzle 7
The distance to the edge was about 5 m, and the flow velocity of the blast air at a position 1 mm from the upper surface of the steel plate 5C performed during non-rolling was 7.2 m / sec on average by Pitot tube measurement.

As a result of draining the steel plate 5C in this manner, the residual cooling water remaining on the upper surface of the steel plate 5C was almost completely wiped off from the upper surface of the steel plate 5C about 8 seconds after the drainage was performed. The surface average temperature of the steel sheet 5C after reheating is about 83
The variation in temperature except for 1 ° C. and the edge was 13 ° C. at the maximum. As a result of finish rolling of the steel sheet 5C by the finish rolling mill 3, there was no problem in shape, material and the like.

Subsequently, another high-temperature steel sheet 5D subjected to rough rolling by the rough rolling mill 2 was carried into the rolling line 1. This high-temperature steel plate 5D has an average surface temperature of 850 ° C. and a thickness of about 37
mm, a width of about 4.6 m, and a length of about 18 m. This steel plate 5D is connected to the first to fourth blocks 4A to 4D of the cooling device 4.
And cooled to reduce the average temperature by 30 ° C. Immediately after the cooling is stopped, the injection pressure of 0.5 from the nozzles 7 of the first to fourth blocks 6A to 6D of the draining nozzle group 6 is increased.
Air was sprayed toward the upper surface of the steel plate 5D at MPa. At the time of draining, the draining nozzle group 6 was oscillated in the direction of the rolling line 1 with a stroke of 600 mm.

As a result of draining in this way,
About 8 seconds after the draining, the residual cooling water remaining on the upper surface of the steel plate 5D was almost completely wiped off from the upper surface of the steel plate. Also,
The average surface temperature of the steel sheet 5D after reheating was about 818 ° C., and the variation in temperature excluding the edge was 19 ° C. at the maximum. As a result of finish rolling this steel plate 5D by the finish rolling mill 3,
There was no problem in shape, material, etc. (Comparative Example) Next, a comparative example will be described with reference to the drawings.

FIG. 8 is a schematic plan view showing a comparative example.

As shown in FIG. 8, the comparative example is a rough rolling mill 2 and a finishing rolling mill 3 in a plate mill in which a rolling line 1 is provided with two rolling mills, a rough rolling mill 2 and a finishing rolling mill 3.
The draining nozzle 10 was installed on the downstream side of the water-cooled cooling device 4 installed between the two. The length of the cooling device 4 is 20
m, and is installed from a position 10 m downstream of the rough rolling mill 2. The distance between the rough rolling mill 2 and the finishing rolling mill 3 is 5
0 m. The diameter of the draining nozzle 10 was 20 mm, and two nozzles were installed on both sides of the rolling line 1.

In the comparative example configured as described above, the steel plate was drained as follows.

The high-temperature steel sheet 5E subjected to rough rolling by the rough rolling mill 2 was carried into the rolling line 1. This high temperature steel plate 5E
Has a surface average temperature of about 880 ° C. and a size of about 4
It was 5 mm, about 4.5 m wide and about 14 m long. The steel plate 5E was inserted into the cooling device 4 and cooled by the cooling device 4 so as to lower the average temperature by 60 ° C. After cooling off,
Since the previous steel plate was being rolled by the finishing mill 3,
After the cooling was stopped, the cooling device 4 was kept waiting for about 90 seconds. After the finish rolling of the previous steel sheet, air is discharged from the draining nozzle 10 at the outlet side of the cooling device 4 at a jet pressure of 1.5 MPa to the steel sheet 5E.
Draining was performed by spraying toward the upper surface of the. But,
From the temperature distribution measured after the double heating, the surface temperature of the steel sheet 5E was about 798 ° C., about 20 ° C. lower than the target temperature.
The temperature variation excluding the edge was 55 ° C. at the maximum.
Further, the hardness of the steel material 5E after the completion of the rolling was varied, and was out of the standard.

From these results, the following became clear.

According to the present invention, as in the comparative example, water is not drained immediately after finishing a predetermined time after finishing cooling, but immediately before finish rolling. By draining the water, the residence time of the residual cooling water on the upper surface of the steel plate can be significantly reduced.
Accordingly, local supercooling of the steel sheet can be prevented, temperature controllability can be improved, temperature unevenness can be suppressed, the material can be made uniform, and the yield can be improved. Further, the time lag between the cooling of the steel sheet and the finish rolling is reduced, which leads to an improvement in productivity.

[0070]

As described above, according to the present invention, cooling water is injected from a cooling device installed along a rolling line toward a steel sheet on the rolling line to cool the steel sheet, and then the steel sheet is cooled. In the method for draining steel sheet, which eliminates residual cooling water remaining on the upper surface, immediately after the injection of cooling water to the steel sheet is stopped, fluid is injected from the group of drainers having multiple nozzles toward the upper surface of the steel sheet. By,
The residual cooling water retained on the upper surface of the steel plate can be drained all at once. Therefore, local supercooling can be prevented, temperature controllability can be improved, temperature unevenness can be suppressed, and material uniformity and yield can be improved. Further, since a time lag between cooling and rolling of the steel sheet is reduced, useful effects such as improvement in productivity are brought.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a draining method of the present invention.

FIG. 2 is a plan view showing a draining state by a draining nozzle group.

FIG. 3 is a view as viewed in a direction A in FIG. 2;

FIG. 4 shows the air injection distance when air is jetted from a nozzle having a diameter of 7 mm toward a steel plate having a surface temperature of 400 ° C. or higher to drain remaining cooling water remaining on the upper surface of the steel plate. 4 is a graph showing the relationship between the air flow velocity at 1 mm from the steel plate surface and the air injection pressure for each air injection pressure.

FIG. 5 shows an interval between air jet nozzles having a diameter of 7 mm of 500 m.
6 is a graph showing, for each distance in the steel sheet width direction, the relationship between the distance in the rolling line direction at each distance in the steel sheet width direction and the flow rate of air at 1 mm from the steel sheet surface when m is set.

FIG. 6 is a schematic plan view showing a first embodiment of the present invention.

FIG. 7 is a schematic plan view showing a second embodiment of the present invention.

FIG. 8 is a schematic plan view showing a comparative example.

[Explanation of symbols]

 1: Rolling line 2: Rough rolling mill 3: Finish rolling mill 4: Cooling device 4A to 4D: Block of cooling device 5, 5A, 5B, 5C, 5D, 5E: Steel plate 6: Drain nozzle group 6A to 6D: Drain nozzle Group block 7: Air injection nozzle 8: Air receiver 9: Header tube 10: Conventional drainer nozzle

Continued on the front page (72) Inventor Hisashi Morisaka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Akira Tagane 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Inside Steel Pipe Co., Ltd.

Claims (9)

[Claims] 1. A cooling device installed along a rolling line injects cooling water toward a steel plate on the rolling line to cool the steel plate and remove residual cooling water remaining on the upper surface of the steel plate. Eliminating, in the method of draining the steel sheet, immediately after stopping the injection of the cooling water to the steel sheet, immediately spray the fluid toward the steel sheet from a drain nozzle group having a plurality of nozzles, the residual cooling water A method for draining a steel sheet, comprising removing the steel sheet from an upper surface thereof. 2. The draining method according to claim 1, wherein the draining nozzle group is provided at right angles to the rolling line and on one side of the rolling line. 3. The method according to claim 1, wherein the fluid is 3 m / sec at a position 1 mm away from the upper surface of the steel plate at a temperature of 400 ° C. or higher.
3. The draining method according to claim 1, wherein the draining method has the above flow velocity. 4. The steel plate is oscillated in the direction of the rolling line by a stroke equal to or longer than the nozzle interval of the draining nozzle group.
The method for draining water according to any one of the above. 5. The method according to claim 1, wherein the draining nozzle group is oscillated in the rolling line direction by a stroke equal to or longer than the nozzle interval of the draining nozzle group. Draining method as described. 6. The cooling device and the draining nozzle group are divided into a plurality of blocks in the rolling line direction, and the cooling device and the draining nozzle group of each block are turned on / off according to the length of the steel plate. The method according to any one of claims 1 to 5, wherein the method is controlled. 7. A set of draining nozzles installed on one side of a rolling line, and a steel sheet oscillation means, wherein a cooling device for the steel sheet is installed on the rolling line, and the set of draining nozzles is It has a plurality of nozzles orthogonal to each other, and the steel sheet oscillation means is characterized in that the steel sheet is oscillated in the rolling line direction with a stroke equal to or longer than the nozzle interval of the water draining nozzle group, apparatus. 8. A milling nozzle group installed on one side of a rolling line, and a nozzle oscillation means, a cooling device for a steel plate is installed on the rolling line, and the draining nozzle group is connected to the rolling line. A steel plate having a plurality of nozzles orthogonal to each other, wherein the nozzle oscillation means oscillates the draining nozzle group in the rolling line direction with a stroke equal to or longer than the nozzle interval of the draining nozzle group. Drainer. 9. The cooling device and the draining nozzle group are divided into a plurality of blocks in the rolling line direction, and the cooling device and the draining nozzle group of each block are
9. The drainer according to claim 7, wherein on / off control is performed according to the length of the steel plate.