JPH10263672A - Cooling device for hot temperature steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce a steel sheet of an uniform quality without riding over an upper draining-off roll with cooling water and flowing in the next zone by providing the upper draining-off roll having the diameter more than a specific value or a draining-off object having the height being equivalent to the diameter as a cooling water blocking means. SOLUTION: When the distance between a cooling water draining-off means and an upper draining roll Z on the lower stream side is made as L (m), the flow density of the cooling water per 1 m of the width of a steel sheet is made as Q (m<3> /sec) and the width of the steel is made as W (m), the roll diameter D of the upper draining roll 2 or the height D of draining substance having an equivalent height D is made as D>0.4 (QW/L). When the diameter D of the roll 2 or the height D of the object is not enlarged with the restriction on the equipment and even the distance L between the cooling water blocking means and the upper roll 2 on the down stream side is made in the equipment satisfying the equation, the same effect can be also obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a cooling method for cooling a hot-rolled high-temperature steel sheet, which eliminates stagnation of cooling water on the exit side of the cooling device and enables uniform cooling of the high-temperature steel sheet. The present invention relates to a cooling device to be used.

[0002]

2. Description of the Related Art Generally, hot-rolled hot steel sheets are
Cooling unevenness easily occurs during water cooling immediately after rolling. This cooling unevenness causes deformation of the steel sheet, residual stress, and variation in the material after cooling, and also causes deformation of the steel sheet, which easily causes trouble in operation. Further, the deformed steel sheet requires a refining process for removing the deformation by a press or a straightening machine later, which is disadvantageous in cost. Therefore, conventionally, various so-called uniform cooling methods have been proposed in order to eliminate cooling unevenness.

[0003] When a hot steel sheet after rolling is cooled on-line, it is general that cooling is performed by pouring cooling water from above and below the steel sheet in a horizontal state. In particular, in recent years, technologies related to controlled rolling, which combines cooling and rolling, and controlled cooling, which cools steel sheets online, have been developed.
With the advancement of these technologies, high-precision temperature control, particularly cooling stop temperature control, has become increasingly important.

[0004] However, a thick steel plate may have a large product size and a width of up to 5 m, and a large thickness of the steel plate requires a large amount of cooling water for cooling. Therefore,
In order to use this cooling water efficiently, it is important to stop the cooling water at the outlet side of the cooling device and drain the water, and how to quickly discharge the clogged cooling water from the plate edge. It is a problem.

[0005] In particular, if the water is blocked by a draining roll that restrains the steel plate from above and below, there is a risk that the cooling water will rise and get over the draining roll and flow into the next cooling zone or the rear part of the cooling device main body. . When such a situation occurs, cooling water flows into the non-cooling section, causing supercooling, which is a problem in quality control and operation.

[0006] In order to solve these problems, various studies have been made on a steel plate drainer, and for example, the following techniques have been proposed.

In Japanese Utility Model Laid-Open Publication No. 53-39508, an air nozzle is vertically movably arranged toward the upper surface of a steel plate.
A technique for draining water by jetting air is disclosed.

Japanese Patent Application Laid-Open No. 7-9023 discloses that high-pressure spray water is sprayed in the width direction of a steel sheet from an injection nozzle provided on one side of the steel sheet transferred on a table roller, and stays on the steel sheet. A method of removing remaining water from other side end surfaces of the steel sheet is disclosed.

Further, Japanese Utility Model Application Laid-Open No. 58-125611,
Japanese Utility Model Application Laid-Open No. 59-161062 discloses a method of draining water by sandwiching a steel plate between rubber rolls provided above and below and pressing.

Further, in Japanese Patent Application Laid-Open No. 60-206516 and Japanese Utility Model Application Laid-Open No. Hei 7-33406, a draining roll is arranged, and an injection nozzle is provided downstream of the roll in the width direction of the steel sheet. There has been disclosed a technique for injecting water toward a draining roll from a central portion toward both ends and draining the water.

[0011]

However, as disclosed in Japanese Utility Model Laid-Open Publication No. 53-39508, an air nozzle is disposed so as to be able to move up and down, and water is drained by jet air. In the method of spraying high-pressure spray water from the side as in the technique disclosed in Japanese Patent Publication No. However, it was difficult to remove by pushing to the edge of the plate.

The technology described in Japanese Utility Model Laid-Open No. 58-125611 and Japanese Utility Model Laid-Open No. 59-161062,
Although the techniques described in Japanese Patent Application Laid-Open Nos. 0-206516 and 7-33406 are effective in preventing leakage of cooling water from a gap generated between a drain roll and a steel plate, these techniques are not limited to these. The cooling water flowing over the rolls could not be effectively blocked.

Particularly, in recent years, quenching of a thick steel plate by strong cooling has been demanded in accordance with quality requirements, and a large amount of cooling water is injected into the steel plate for cooling. In such operations, a large amount of cooling water is particularly likely to flow over the draining rolls and cause uneven cooling of the steel sheet.

In order to prevent the cooling water from climbing over, it is sufficient to increase the diameter of the draining roll. However, it is not economical to increase the diameter unnecessarily. The cooling device constituting the zone has a problem that the space of the cooling zone is narrowed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has an apparatus for cooling a hot steel plate having an optimum diameter draining roll, an optimum cooling water blocking means, and a downstream cooling means. An object of the present invention is to provide a cooling device for a high-temperature steel sheet having a distance L between draining rolls.

[0016]

An object of the present invention is to provide an apparatus for cooling a high-temperature steel sheet by transporting a high-temperature steel sheet while constraining the steel sheet with a plurality of sets of vertical drainage rolls and injecting cooling water from above and below the steel sheet during the transportation. A cooling water blocking means for preventing cooling water injected above the steel sheet from flowing to the upstream side in the steel sheet conveying direction; the cooling water blocking means and a draining roll downstream of the cooling water blocking means. The distance between is L (m), steel plate width 1
When the cooling water flow density per m is Q (m ³ / sec) and the steel sheet width is W (m), D> 0.4 (QW / L) ^2/3 (1) The cooling device for hot steel sheets is characterized by having a draining roll having m) or a draining object having a height corresponding to D (claim 1).

The inventors set the distance L between the cooling water blocking means and the draining roll downstream thereof to 0.6 to 3.0.
(M), the cooling water density per meter of steel sheet width is 0.003 to 0.08
3 (m ³ / sec), the width of the steel plate is variable in the range of 2.0 to 5.0 (m), and the maximum liquid level of the cooling water that stays between the cooling water blocking means and the draining roll on the downstream side H (m) was investigated using a simulation test device and a real machine.

FIG. 1 shows a conceptual diagram of a cooling device on the upper surface of a steel plate. FIGS. 1A to 1E show various cooling methods.
In FIG. 1, 1 is a steel plate, 2 is a draining roll, 3 is a draining roll, 4 is a slit nozzle, 6 is a laminar nozzle, 7 is a cooling water injection nozzle, 8 is a weir, and 8 is a spray nozzle. D indicates the diameter of the draining roll, and L indicates the distance between the cooling water blocking means and the draining roll on the downstream side thereof.

That is, the means for blocking the cooling water is shown in FIG.
(A), (b) and (e) show the upstream draining roll 2, the cooling water injection nozzle 7 in FIG. 1 (c), and the weir 8 in FIG. 1 (d). Note that the cooling device below the steel plate is omitted.

In FIG. 1 (a), cooling water is supplied from a slit nozzle 4 provided in the vicinity of the upstream draining roll 2 on the upstream side and having no slit in the width direction toward the downstream draining roll 2. In this case, the cooling water is almost completely filled between the two draining rolls 2.

In FIG. 1B, cooling water is injected from a laminar nozzle 6, which is provided at the center between the rolls and has a slit shape in the width direction and has no break.

In FIG. 1C, the cooling water is sprayed from a cooling water jet nozzle 7 provided in the vicinity of the upstream draining roll 2 and near the steel plate 1 in the width direction and continuous to the downstream draining roll 2. Water is injected, and in this case,
The cooling water is substantially filled between the two draining rolls 2.

In FIG. 1D, cooling water is supplied from a slit nozzle 4 provided in the vicinity of the upstream draining roll 2 on the upstream side and having no slit in the width direction toward the downstream draining roll 2. A weir 8 is provided between the slit nozzle 4 and the downstream draining roll 2 for injecting water and blocking the cooling water that has rebounded from the downstream draining roll 2 and returned. Also in this case, the cooling water is substantially filled between the two draining rolls 2.

FIG. 1E shows the cooling of the steel sheet 1 by spraying cooling water from a number of spray nozzles 9.

In each of these examples, the body that drains water is a draining roll. However, the present invention is not limited to this. The draining rolls are stacked in multiple stages to increase the height of the weir. It may be a raised one, or one in which a weir is provided on a draining roll.

The inventors conducted experiments on these various cooling methods and determined how the maximum liquid surface height H was represented.

FIG. 2 shows the result.

In FIG. 2, the horizontal axis represents (QW / L) ^2/3 , and the vertical axis represents the maximum liquid level height H (m). The data in the black squares are from the simulation test apparatus, and the data in the black circles are from the implementation. That is, the liquid level maximum height H is
Normally, parameters (QW
/ L) A linear relationship with ^2/3 was first discovered by the inventors. C in FIG. 2 is a coefficient representing a gradient between the horizontal axis and the vertical axis. The value of the coefficient C obtained with the simulated paper mold apparatus was 0.32 to 0.34. Based on this data, the maximum height H of the liquid surface was measured by installing a draining roll having a diameter of 300 mm on the actual machine, and the parameter (QW /
L) It has a linear relationship with ^2/3, and the coefficient C was found to be 0.4. Therefore, from FIG. 2, in the present invention, C = 0.4 which is the data of the actual machine is adopted, and H = 0.4 (QW / L) ^2/3 (2) is obtained as an equation representing the liquid level maximum height H. Was. Therefore, if the diameter of the draining roll or the height of the draining body is determined by the formula (2), the cooling water does not pass over the draining roll or the draining body.

In the case where the diameter of the draining roll or the height of the draining object cannot be made large due to restrictions on facilities, etc.,
The same effect can be obtained even if the distance L between the cooling water blocking means and the draining roll on the downstream side satisfies the expression (1) (claim 3).

Recently, a cooling device used for cooling a thick steel plate has a slit nozzle for injecting cooling water from a nozzle installed near the upstream draining roll in the direction of progress of the steel sheet to the downstream draining roll. However, the inventions of claims 1 and 3 are particularly effective in such equipment (claims 2 and 4).

Further, at the end of the plate downstream of the draining roll,
By arranging a purge spray for purging cooling water staying on the steel sheet toward the other end of the steel sheet (claim 5),
Even if the cooling water leaks, the cooling water staying on the steel plate can be quickly purged out of the steel plate, and the occurrence of uneven cooling due to the stay of the cooling water can be prevented.

In addition, a backup roll is installed at the center of the draining roll in contact with the upper part thereof (claim 6), thereby preventing the draining roll from bending.
Leakage of cooling water from between the steel plate and the draining roll can be prevented.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a diagram showing an example of the embodiment of the present invention. In FIG. 3, 1 is a steel plate, 2 is a draining roll, 3 is a draining roll, 4 is a slit nozzle,
Is a circular tube nozzle. In this cooling device, while the steel sheet 1 immediately after rolling is transported between the 20 sets of the draining rolls 2 and the draining rolls 3, the upper side is cooled by the cooling water from the slit nozzle 4, and the lower side from the circular pipe nozzle 5. Is cooled on-line by the cooling water. FIG. 4 shows a part of these devices in an enlarged manner. In FIG. 4, two water draining rolls 2 and 3 and a cooling zone for one zone are shown.

In FIG. 4 et seq., The same components as those in the previous figures are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 4, 10 is a hydraulic cylinder, and 14 is cooling water. The pitch of each draining roll is 1 m.

On the upper side surface between the draining rolls 2 and 3, the slit nozzle 4 moves from the slit nozzle 4 in the advancing direction of the steel plate 1 from the upstream draining roll 2 on the upstream side in the sheet conveying direction to the downstream draining roll 2 on the downstream side. 0.033 m ³ / sec of cooling water per 1 m width is flowing along the steel plate 1. On the other hand, the lower surface is 150mm
Water is jetted from a circular nozzle 5 provided at a pitch and submerged in water, and is cooled by a water flow generated by the accompanying flow.

In these 20 sets of draining rolls 2 and 3, the draining roll 3 also serves as a transport roll and is of a fixed type. It is possible to move up and down the draining roll 2 up and down,
Controllable at 0.5 mm pitch.

Further, the gap between the draining roll 2 and the draining roll 3 is set to be equal to or less than the thickness of the steel plate 1. When the steel plate 1 passes, the draining roll 2 is pressed against the pressing force of the hydraulic cylinder 10. The steel plate 1 is lifted up against it, and a pressing force is applied to the steel plate 1 by the reaction force, so that the steel plate 1 is restrained.

In this embodiment, the cooling intensity can be controlled by thinning out the cooling water in a plurality of cooling zones. For example, the zone of the slit nozzle 4 and the zone of the circular tube nozzle 5 may be alternately turned on and off to intermittently cool. In this case, it is necessary to surely drain the water in the draining rolls 2 and 3 so that the cooling water does not flow from the zone where the cooling water is turned on to the adjacent zone where the cooling water is turned off.

For this reason, in this embodiment, the roll diameter D of the draining roll 2 is determined according to the equation (1).

If the diameter D of the draining roll 2 cannot satisfy the expression (1) due to the limitation of equipment, etc., the cooling water blocking means and the draining roll downstream of the cooling water blocking means are not provided. The interval is selected so that the distance L satisfies the expression (1).

FIG. 5 illustrates another embodiment of the present invention. The device in FIG. 5 differs from the equipment in FIG. 4 in that a backup roll 11 is provided in contact with the upper part of the draining roll 2 and at the center thereof.
When the steel plate 1 is constrained by the upper constraining roll 2, the reaction force causes the upper constraining roll 2 to bend, and a gap is formed between the upper constraining roll 2 and the cooling water leaks from the gap.
By providing the backup roll 11, the amount of deflection of the upper constraining roll 2 is reduced, and the leakage of cooling water is reduced.

The necessity of the backup roll 11 is determined by the plate width and the required restraining force, the diameter of the draining roll 2, and the like. When the load is applied from both ends of the draining roll 2, the draining roll 2 is determined. The amount of deflection is obtained elastically and the backup roll 11 needs to be provided if this number is several mm or more.

FIG. 6 shows still another embodiment of the present invention. The device in FIG. 6 is different from the device in FIG. 5 in that a header 12 is provided on the downstream side of the draining roll 2, and from the draining spray nozzle 13, at an angle of 45 ° in the traveling direction of the steel plate 1 and in the transport direction of the plate. In opposition, and
Draining spray of 100 liter / min is sprayed from the end of the plate in the width direction of the plate toward the other end.

Even if there is some leakage of the cooling water, almost all of the water is purged from the steel plate by the drainer spray nozzle 13, so that supercooling or the like does not occur.

FIG. 7 shows another embodiment of the present invention. (A) in FIG. 7 shows that the auxiliary draining roll 15 is further stacked on the top draining roll 2. According to this configuration, in terms of the operation and effect of the present invention, the diameter of the draining roll 2 is such that the draining roll 2 and the auxiliary draining roll 15
This is the same as D, which is the sum of the diameters of, and water can be drained effectively. In this case, the use of a rubber lining roll having good drainage properties as the auxiliary drainer rolls 15 further improves the drainage properties.

In this case, the combination of the draining roll 2 and the auxiliary draining roll 15 corresponds to the "draining object" described in the claims.

FIG. 7B shows an example in which the auxiliary drainer rolls 15 are stacked in multiple stages to increase the height of the "water drainer". Also in this case, the combination of the water draining roll 2 and the multi-stage auxiliary draining rolls 15 corresponds to a “draining object” described in the claims.

(C) in FIG. 7 shows the draining roll 8
And the weir 8 is provided in sliding contact with the water draining roll 2 and the weir 8 together.

In any case, D in FIG.
Corresponds to the height of the draining object, and the height of the draining object is selected so that D satisfies the expression (1).

[0050]

【Example】

(Example 1) Using the equipment shown in FIG. 1, a width of 5 m and a length of 30
m, 25mm thick hot rolled steel sheet immediately after rolling
Cooling was performed by passing through at pm. In this example, in order to obtain a required cooling rate, the cooling water above the steel plate between the rolls was turned on and off every other zone. That is, the cooling water of the slit nozzle 4 was stopped one by two. With respect to the cooling water at the lower part of the steel plate, the cooling water from the circular tube nozzle 5 is stopped and jetted every other zone so that the cooling from the circular tube nozzle 5 is performed at the place where the cooling by the slit nozzle 4 is performed. The upper and lower surfaces of the steel sheet were cooled in the same zone. The gap between the draining rolls 2 and 3 was -1.5 mm, ie, 23.5 mm. The roll diameter D of the draining roll 2 was determined using the maximum plate width of 5 m for the calculation. As described above, the cooling water flow density per 1 m of the steel sheet width from the slit nozzle 4 is Q = 0.033 m ³ / sec. In this case, the distance between the draining rolls 2 is 1
m, the distance L between the cooling water blocking means and the draining roll downstream of the cooling water blocking means was set to (1-D / 2-D / 2). From these conditions, when the maximum liquid level height H is calculated using the equation (2), H becomes 0.132 m. Therefore, the diameter D of the draining roll 2 was set to 0.14 m. Then, the cooling water did not get over the draining roll 2.

At this time, when the temperature distribution of the steel sheet on the entry side was measured by a scanning radiation thermometer, it was 850 ° C. ± 15 ° C. When the temperature distribution was measured by a scanning radiation thermometer at a position 20 m downstream of the cooling device, the temperature distribution was 500
C. ± 10 ° C., and no cooling unevenness occurred.

At this time, there was no large C warpage deformation in the width direction of the sheet, no particularly large deformation occurred even after cooling in the cooling floor, and the product was obtained without performing any special correction. When the hardness distribution in the sheet width direction was examined after cooling, there was no particularly large difference in hardness distribution. From this, it is determined that there was no large cooling unevenness.

(Embodiment 2) The cooling device shown in FIG.
A high-temperature steel plate having a width of 5 m, a length of 30 m and a thickness of 16 mm immediately after rolling was cooled. In this example, in order to obtain a required cooling rate, the cooling water above the steel plate between the rolls was turned on and off every other zone. That is, the cooling water of the slit nozzle 4 was stopped one by two. As for the cooling water at the lower part of the steel plate, the cooling water from the pipe nozzle 5 is stopped every other zone.
The steel plate was jetted and cooled from the circular tube nozzle 5 where cooling by the slit nozzle 4 was performed, so that both upper and lower surfaces of the steel plate were cooled in the same zone. The gap between the top and bottom draining rolls was -1.5 mm in plate thickness, that is, 14.5 mm.

The flow rate density of cooling water per 1 m of steel sheet width from the slit nozzle 4 was set to Q = 0.025 m ³ / sec. In this case, since the distance between the draining rolls 2 is 1 m, the distance L between the cooling water blocking means and the draining roll downstream of the cooling water blocking means is represented by (1-D / 2-D / 2). And From these conditions, when the maximum liquid level height H is calculated using the equation (2), H = 0.108 m. Therefore, the diameter D of the draining roll 2 was set to 0.11 m. Then, the cooling water did not get over the draining roll 2.

However, in the case of this embodiment, the first embodiment
Since the diameter of the draining roll 2 is smaller than that of
Bending occurred, and cooling water leaked from a gap created between the draining roll 2 and the steel plate 1. Therefore, in the present embodiment, this bending was prevented by providing the backup roll 11 having a width of 500 mm and a diameter of 250 mm at the center of the draining roll 2.

Also in this embodiment, when the temperature distribution of the steel sheet on the entry side was measured by a scanning radiation thermometer, it was found to be 850 ° C. ± 1.
5 ° C. When the temperature distribution was measured by a scanning radiation thermometer at a position 20 m downstream of the cooling device, the temperature distribution was 500 ° C. ± 10 ° C., and no cooling unevenness occurred.

At this time, there was no large C warpage deformation in the width direction of the sheet, no particularly large deformation occurred even after cooling in the cooling floor, and the product was obtained without performing any special correction. When the hardness distribution in the sheet width direction was examined after cooling, there was no particularly large difference in hardness distribution. From this, it is determined that there was no large cooling unevenness.

(Embodiment 3) The cooling device shown in FIG.
A high-temperature steel plate having a width of 5 m, a length of 30 m and a thickness of 40 mm immediately after rolling was cooled. In this example, in order to obtain a required cooling rate, the cooling water above the steel plate between the rolls was turned on and off every other zone. That is, the cooling water of the slit nozzle 4 was stopped one by two. Regarding the cooling water at the lower part of the steel plate, the pitch of the circular pipe nozzle 5 was 100 mm, and
It was stopped and jetted every other zone, so that cooling from the circular tube nozzle 5 was performed at the place where cooling by the slit nozzle 4 was performed, and both upper and lower surfaces of the steel plate were cooled in the same zone. The gap between the top and bottom draining rolls was -1.5 mm, ie, 38.5 mm.

The cooling water flow density per 1 m of the steel sheet width from the slit nozzle 4 was Q = 0.05 m ³ / sec. In this case, since the distance between the draining rolls 2 is 1 m, the distance L between the cooling water blocking means and the draining roll downstream of the cooling water blocking means is represented by (1-D / 2-D / 2). And From these conditions, when the maximum liquid level height H was calculated using the equation (2), H = 0.181 m. Therefore, the diameter D of the draining roll 2 was 0.19 m. Then, the cooling water did not get over the draining roll 2.

In this embodiment, the width is 500 mm and the diameter is 25 mm.
By providing the 0 mm backup roll 11 at the center position of the draining roll 2, bending of the draining roll 2 is prevented, and leakage of cooling water from between the draining roll 2 and the steel plate 1 is prevented. I have.

The cooling water that has leaked to some extent is quickly removed from the steel plate 1 by a purge spray jetted from the drainage spray nozzle 13 of the header 12 at an injection rate of 100 liter / min, and stays on the steel plate 1 to be retained. It did not cause cooling.

Also in this embodiment, when the temperature distribution of the steel sheet on the entry side was measured by a scanning radiation thermometer, it was found to be 850 ° C. ± 1.
5 ° C. When the temperature distribution was measured by a scanning radiation thermometer at a position 20 m downstream of the cooling device, the temperature distribution was 500 ° C. ± 10 ° C., and no cooling unevenness occurred.

At this time, there was no large C warpage deformation in the width direction of the sheet, no particularly large deformation occurred even after cooling on the cooling floor, and the product was obtained without performing any special correction. When the hardness distribution in the sheet width direction was examined after cooling, there was no particularly large difference in hardness distribution. From this, it is determined that there was no large cooling unevenness.

(Comparative Example) Example 1 was repeated except that the diameter of the draining roll 2 was changed to 100 mm using the apparatus shown in FIG.
The operation was performed under the same conditions as described above.

That is, a width of 5 m, a length of 30 m, and a thickness of 25
The high-temperature steel sheet immediately after the rolling of mm was passed at a transport speed of 40 mpm to perform cooling. In this comparative example, in order to obtain the required cooling rate, the cooling water above the steel plate between the rolls was turned on and off every other zone. That is, the cooling water of the slit nozzle 4 was stopped one by two. With respect to the cooling water at the lower part of the steel plate, the cooling water from the circular tube nozzle 5 is stopped and jetted every other zone so that the cooling from the circular tube nozzle 5 is performed at the place where the cooling by the slit nozzle 4 is performed. West,
Both upper and lower surfaces of the steel plate were cooled in the same zone. The gap between the draining rolls 2 and 3 is -1.5 m
m, that is, 23.5 mm.

However, under the same conditions as in Example 3, a purge by the draining spray nozzle 13 was added.

In this case, the diameter of the draining roll 2 is smaller than the maximum liquid level height H = 0.132. Therefore, in this case, the cooling water flows over the draining roll 2 and flows into the adjacent zone, and cannot be removed by purging with the draining spray nozzle 13 that has flowed. Since this cooling water was always present in the adjacent zone, the central portion of the steel sheet 1 was selectively supercooled.

At this time, when the temperature distribution on the entrance side was measured by a scanning radiation thermometer, it was 850 ° C. ± 15 ° C. When the temperature distribution was measured by a scanning radiation thermometer at a position 20 m downstream of the cooling device, the temperature was 400 ° C. to 5 ° C.
At 10 ° C., large cooling unevenness occurred. At this time, C warpage deformation was observed in the plate width direction. When the plate was conveyed to a cooling floor and cooled to room temperature, a shape defect occurred. Therefore, a refining process for removing this deformation with a leveler and a press straightening machine was required. In addition, when the hardness distribution in the width direction of the plate was examined after cooling, the hardness was high at the center of the plate,
So-called baking unevenness was observed.

[0069]

As described above, in the present invention, the distance between the cooling water blocking means and the draining roll on the downstream side is L (m), and the cooling water flow density per 1 m of the steel sheet width is Q. (M ³ / sec), when the width of the steel sheet is W (m), D> 0.4 (QW / L) ^2/3 (1) A draining roll having a diameter D (m) of the following size is provided. The cooling water does not flow over the draining roll and flow into the next zone. Therefore, in an online cooling device that continuously cools a thick steel plate, uniform cooling without cooling unevenness is possible. Therefore, it is possible to stably produce a homogeneous steel sheet with little variation in the material inside the steel sheet. In addition, since there is no large deformation of the steel plate during and after cooling and no trouble in passing the steel plate, continuous operation is not hindered.

Further, since no large thermal distortion is generated even after cooling, a refining step by a leveler or a press is unnecessary, and a low-cost production of a thick steel plate is possible.

Further, since the draining roll can be designed economically, the equipment cost can be reduced.

When the diameter of the draining roll cannot be increased due to facility restrictions, the distance L between the cooling water blocking means and the draining roll downstream thereof satisfies the expression (1). The same effect can be obtained even with a simple facility.

Recently, a cooling device used for cooling a thick steel plate has a slit nozzle for injecting cooling water from a nozzle installed near the upstream draining roll in the traveling direction of the steel sheet toward the downstream draining roll. Is used, but the above invention is particularly effective in such equipment).

Further, at the end of the plate on the downstream side of the draining roll,
By arranging a purge spray that purges the cooling water staying on the steel sheet toward the edge of the other steel sheet, even if the cooling water leaks, the cooling water staying on the steel sheet can be quickly removed from the steel sheet. Purging can be performed, and generation of uneven cooling due to stagnation of cooling water can be prevented.

In addition, by installing a backup roll in contact with the upper part of the draining roll at the center thereof, bending of the draining roll is prevented, and cooling water leaks from between the steel plate and the draining roll. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a maximum liquid level of cooling water staying between draining rolls.

FIG. 3 is a diagram showing another example of the embodiment of the present invention.

FIG. 4 is a detailed view of the embodiment shown in FIG.

FIG. 5 is a diagram showing another example of the embodiment of the present invention.

FIG. 6 is a diagram showing another example of the embodiment of the present invention.

FIG. 7 is a diagram showing another example of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel plate 2 Draining roll 3 Draining roll 4 Slit nozzle 5 Circular nozzle 6 Laminar nozzle 7 Cooling water injection nozzle 8 Weir 9 Spray nozzle 10 Hydraulic cylinder 11 Backup roll 12 Header 13 Drain spray 14 Cooling water

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoshi Ueoka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Akira Tagane 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Within Nippon Kokan Co., Ltd. (72) Inventor Isao Takahashi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd.

Claims (9)

[Claims] An apparatus for cooling a high-temperature steel sheet by conveying a high-temperature steel sheet while restraining the high-temperature steel sheet with a plurality of sets of up-and-down draining rolls, and injecting cooling water into the steel sheet from above and below during the conveyance,
The cooling water blocking means for preventing the cooling water injected on the upper side of the steel sheet from flowing to the upstream side in the sheet conveying direction is provided, and the distance between the cooling water blocking means and the downstream draining roll is provided. Is defined as L (m), the flow rate density of cooling water per meter of steel sheet width is Q (m ³ / sec), and the steel sheet width is W (m). D> 0.4 (QW / L) ^2/3 (1) A cooling device for a high-temperature steel plate, comprising a draining roll having a diameter D (m) of a certain size or a draining object having a height corresponding to D. 2. An apparatus for cooling a high-temperature steel sheet by conveying a high-temperature steel sheet while constraining the high-temperature steel sheet with a plurality of sets of upper and lower draining rolls, and injecting cooling water from above and below the steel sheet during the conveyance,
It has a slit nozzle that injects cooling water from the nozzle installed near the upstream draining roll in the steel sheet traveling direction to the downstream draining roll, and the cooling water injected above the steel sheet is in the steel sheet transport direction. A cooling water blocking means for preventing the water from flowing to the upstream side, and the distance between the cooling water blocking means and the draining roll on the downstream side is defined as L
(M), the cooling water flow density per 1 m of steel sheet width is Q (m ³
/ Sec), and when the width of the steel sheet is W (m), D> 0.4 (QW / L) ^2/3 (1) Corresponds to a draining roll or D having a diameter D (m) of the following size: An apparatus for cooling a high-temperature steel sheet, comprising a drainer having a height. 3. An apparatus for cooling a high-temperature steel sheet by transporting a high-temperature steel sheet while constraining the high-temperature steel sheet with a plurality of sets of upper and lower draining rolls, and injecting cooling water from above and below the steel sheet during the transportation.
The cooling water blocking means for preventing the cooling water injected on the upper side of the steel plate from flowing to the upstream side in the transport direction of the steel plate is provided, and the diameter of the draining roll or the height of the draining object is D (m),
The flow rate density of cooling water per meter of steel sheet width is Q (m ³ / sec),
Assuming that the width of the steel plate is W (m), the distance L (m) between the cooling water blocking means and the draining roll on the downstream side is D> 0.4 (QW / L) ^2/3 (1) A cooling device for a high-temperature steel sheet, characterized by satisfying the following expression. 4. An apparatus for cooling a high-temperature steel sheet by conveying a high-temperature steel sheet while constraining the high-temperature steel sheet with a plurality of sets of upper and lower drainers, and injecting cooling water into the steel sheet from above and below during the conveyance, wherein the high-temperature steel sheet is upstream. With a slit nozzle that injects cooling water from the nozzle installed near the side draining roll to the downstream draining roll, the cooling water injected above the steel sheet does not flow to the upstream side in the steel sheet transport direction Cooling water blocking means, the diameter of the draining roll or the height of the draining body is D (m), the cooling water flow density per 1 m of the steel sheet width is Q (m ³ / sec), Board width to W
(M), the distance L (m) between the cooling water blocking means and the draining roll downstream thereof satisfies D> 0.4 (QW / L) ^2/3 (1) A cooling device for a high-temperature steel sheet, characterized in that: 5. A purge spray for purging cooling water remaining on a steel plate toward another plate edge at a plate edge downstream of the draining roll. The cooling device for a high-temperature steel sheet according to any one of the above. 6. The cooling device for a high-temperature steel sheet according to claim 1, wherein a backup roll is provided at a central portion of the draining roll so as to be in contact with an upper portion thereof. . 7. The hot steel sheet according to claim 1, wherein the draining body has a draining roll and one or more auxiliary draining rolls stacked thereon. Cooling system. 8. At least one of the auxiliary draining rolls,
The high-temperature steel plate cooling device according to claim 7, which is a rubber lining roll. 9. The apparatus for cooling a high-temperature steel sheet according to claim 1, wherein the draining body has a draining roll and a weir placed thereon.