JP3157635B2 - Lower surface cooling device for high temperature metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for cooling a lower surface of a high-temperature metal sheet used for cooling the lower surface of a hot-rolled steel sheet in, for example, a manufacturing process of the hot-rolled steel sheet.

[0002]

2. Description of the Related Art In the process of cooling a metal plate, gas or liquid is used as a coolant. However, when quenching a high-temperature metal plate, a particularly high cooling capacity is required. It is common to use water. As a method for supplying cooling water, for example, in cooling a steel sheet after hot finish rolling, a method of supplying cooling water from a nozzle in a spray form or a water bundle (water column or water film) is generally used. ing.

In recent years, in the production process of hot-rolled steel sheets, it is important to improve the cooling capacity of a cooling device for cooling the steel sheets in order to increase the passing speed of the conveyed steel sheets and thereby increase production efficiency. It has been. As a method of improving the cooling capacity, a method of increasing the amount of cooling water and supplying cooling water to a steel sheet so as to form a water bundle as described above from a pipe-shaped pipe nozzle or a slit nozzle having a slit-shaped opening is used. Is known (Japanese Patent Publication 61-2
No. 4087), the vapor film formed on the upper and lower surfaces of the steel sheet during cooling is broken, and the cooling water is caused to directly collide with the upper and lower surfaces. When the cooling water is supplied from the pipe nozzle or the slit nozzle in the form of a water bundle, there is an advantage that a relatively low pressure can be applied to supply a large amount of stable cooling water to the steel sheet. The upper surface and the lower surface of the conveyed steel sheet are cooled by cooling devices having different structures, respectively. Among them, the structure of a conventional lower surface cooling device for cooling the lower surface will be described with reference to the drawings.

[0004] The lower surface cooling device 10 shown in FIG.
1 is formed by inserting a nozzle 12 therein.
The nozzle 12 is in the width direction of the steel plate (the direction perpendicular to the plane of FIG. 4).
Are arranged at equal pitch. The lower surface cooling device 20 shown in FIG. 5 is formed such that one end of a pipe nozzle 21 is attached to a header 22 by welding or the like.

In the manufacturing process of a hot-rolled steel sheet, it is important to obtain a uniform material over the entire hot-rolled steel sheet, and the transport direction of the steel sheet (hereinafter, referred to as a longitudinal direction).
As a technique for making the cooling of the cooling water uniform, a technique of controlling the cooling water pipe valve on / off based on a required cooling time to cool the steel sheet at a predetermined temperature is known (for example, Japanese Patent Application Laid-Open No. 55-55). 24707). In addition, as a technique for uniform cooling in the width direction of the steel sheet,
A technique for equalizing the amount of cooling water supplied from a nozzle in the width direction is known (for example, see Japanese Utility Model Publication No. Sho 62-17467).

[0006]

In the conventional lower surface cooling device 10 shown in FIG. 4, when cooling water containing bubbles is injected into the header when the cooling water is injected into the header, the bubbles are removed from the header. Is accumulated in the upper part 13 of the. In particular, in the header 11 of the lower surface cooling device 10 having the structure shown in FIG. 4, the nozzle 12 is inserted into the header 11 and the bubbles are not easily discharged, so that the bubbles are easily accumulated. Responsiveness of cooling water supply due to on / off of a control valve for controlling the pressure is reduced. When the responsiveness of the cooling water supply deteriorates, the steel plate after hot finish rolling is 5 to 20 m.
Since the steel sheet passes through the cooling equipment at a high speed of about / s, uniform cooling in the longitudinal direction cannot be performed. As a result, there is a problem that deterioration of the material of the steel sheet due to uneven cooling in the longitudinal direction is inevitable.

Further, as shown in FIG. 4, when air bubbles are accumulated in the upper portion 13 of the header 11, this portion is dried and impurities such as oil and calcium contained in the cooling water are solidified. When the mass of the impurities gradually grows, clogging occurs in the header and the pipe nozzle, and the amount of cooling water supplied from the pipe nozzles arranged in the width direction of the steel plate becomes uneven, and as a result, There is a problem that uniform cooling cannot be performed in the width direction of the steel sheet, and deterioration of the material of the steel sheet due to uneven cooling in the width direction is inevitable.

On the other hand, as shown in FIG. 5, there is a plan in which the tip of the pipe nozzle 21 is attached to the header 22 so as to eliminate a portion where air accumulates. However, there is a problem in that the mounting accuracy is poor, and the direction of the pipe nozzle fluctuates in the width direction of the steel sheet, causing cooling unevenness in the width direction. Also,
When the slit nozzle is installed as shown in FIG. 5, the nozzle is too short to form a stable film-like flow, and it is difficult to create a uniform flow in the width direction of the steel sheet, and cooling unevenness in the width direction occurs. easy.

In addition, in any of the structures shown in FIGS. 4 and 5, depending on the zone where the header is located, the cooling water injection may be stopped for a long time of several cycles in the header of the cooling device. In this way, if the injection of cooling water into the header is completely stopped for a long time, impurities contained in the cooling water precipitate in the header, clogging in the header is promoted, and uniform cooling in the width direction of the steel sheet is achieved. There is a problem that the property is impaired.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a high-temperature metal plate lower surface cooling apparatus which maintains uniform cooling in the width direction and the longitudinal direction of the high-temperature metal plate without cleaning for a long period of time. .

[0011]

According to the present invention, there is provided an apparatus for cooling a lower surface of a high-temperature metal plate according to the present invention, comprising a nozzle for supplying cooling water to the lower surface of the high-temperature metal plate in a columnar or film form. Further, in the apparatus for cooling a lower surface of a high-temperature metal plate for cooling the lower surface of the high-temperature metal plate, (1) a header provided with the nozzle and having an air vent hole formed in an upper portion;
(2) Injection means for injecting a small amount of cooling water into the header while the supply of cooling water from the nozzle to the high-temperature metal plate is stopped.

[0012] Here, the above-mentioned injecting means is arranged so that the amount of the small amount of cooling water to be injected is substantially equal to the amount of cooling water discharged from the hole, and the header and the nozzle are filled with the cooling water. It is preferable to use cooling water adjusting means for adjusting the cooling water. In addition, the size of the hole is only required to be about several mm in diameter, as long as the air only needs to escape. That is, the diameter of the hole is preferably in the range of 3 mm to 10 mm. If the diameter of the hole exceeds 10 mm, the internal pressure of the header decreases and the water level in the nozzle decreases, resulting in poor response. When the diameter is less than 3 mm, clogging of the hole is apt to occur.

[0013]

The air vent hole is formed in the upper part of the header of the lower surface cooling device of the high temperature metal plate according to the present invention. No air bubbles accumulate at the top of the header. As a result, since there is no loss time due to the discharge of accumulated air bubbles, etc., the responsiveness of cooling water supply by turning on / off the control valve that controls the supply of cooling water can be maintained well, and the high-temperature metal plate is uniformly cooled in the longitudinal direction. can do. In addition, since no air bubbles are accumulated at the top of the header as described above, a dry portion does not occur in the header, and impurities contained in the cooling water do not solidify and clogging does not occur in the header or the pipe nozzle. Therefore, the amount of cooling water supplied to the high-temperature metal plate in the width direction does not become uneven, and the uniformity of cooling in the width direction of the high-temperature metal plate does not deteriorate.

Further, even when the supply of the cooling water to the high-temperature metal plate is stopped, a small amount of the cooling water is supplied into the header. Sedimentation is reduced, and facility maintainability is improved. Further, since the lower surface cooling device for a high-temperature metal plate of the present invention supplies columnar or film-shaped cooling water to the high-temperature metal plate, it is possible to supply a large amount of cooling water to the lower surface of the high-temperature metal plate in a stable manner. As a result, it is possible to improve the capacity of the cooling equipment and thus the production efficiency.

Here, while the supply of the cooling water from the nozzle to the high-temperature metal plate is stopped, the amount of the cooling water discharged from the hole formed in the upper part of the header and the small amount injected into the header from the injection means. When the amount of cooling water is made substantially equal and the header and the nozzle are filled with cooling water, the effect of preventing clogging in the header and the pipe nozzle can be obtained with a minimum amount of cooling water.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the apparatus for cooling a lower surface of a high-temperature metal plate of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a lower surface cooling device for a high-temperature metal plate of this embodiment, and FIG. 2 is a longitudinal sectional view of the lower surface cooling device for a high-temperature metal plate in FIG. FIG. 3 is a schematic view showing an entire cooling device for a hot-rolled steel sheet using the lower surface cooling device for a high-temperature metal plate shown in FIG.

First, with reference to FIG. 3, a process of cooling a hot finish-rolled steel sheet will be described. The steel plate 30 is cooled by the cooling device 40 that cools the upper and lower surfaces of the steel plate 30 until it reaches the coiler 32 after being processed by the hot finishing mill 31. In the cooling device 40, the cooling water flows from the water injection system main pipe 41 adjacent to the steel sheet transport line to the upper cooling header 45 and the lower cooling header 51 via the control valve 43, which is turned on and off by the valve control device 42, and the branch pipe 44. It is supplied to the steel plate 30 in the form of a column from the pipe nozzles 47 and 52.

Next, referring to FIG. 1 and FIG.
0, a lower surface cooling device for a high-temperature metal plate that cools the lower surface of a steel plate will be described. The lower surface cooling device 50 for the high-temperature metal plate includes:
Column-shaped lower surface cooling header 51 and lower surface cooling header 51
Are provided with a plurality of pipe nozzles 52, which are arranged at equal pitches in the width direction of the steel plate 30. In addition, cooling water from the outside is provided on the side wall of the lower surface cooling header 51.
There is provided a branch pipe 44 for injecting the water into the pipe. Further, a small hole 51a for removing air bubbles contained in the cooling water is formed in an upper portion of the lower surface cooling header 51, and as long as the lower surface cooling header 51 is supplied with the cooling water, the small hole 51a is provided. The structure is such that no air bubbles accumulate inside. Since air bubbles do not accumulate inside the lower surface cooling header 51, there is a delay until the ON signal is output to the control valve 43 (see FIG. 3) by the valve controller 42 (see FIG. 3) and the supply of the cooling water is started. Does not occur. Therefore, the accuracy of uniformly cooling the longitudinal direction of the steel plate is improved.

Since the small holes 51a for bleeding air are formed in the upper part of the end side wall of the lower surface cooling header 51,
The cooling water 54 discharged together with the air is not supplied to the steel plate 30 irrespective of whether the control valve 43 is turned on or off, and there is no disturbance that causes a temperature difference in the width direction of the steel plate 30.
In order to completely discharge the air, it is desirable that the small holes 51 a be provided at the uppermost portion of the lower surface cooling header 51. In this case, the cooling water 54 discharged from the small holes 51a is
By providing a plate or the like that shields the water from being supplied to the lower surface of the steel plate 0, it is possible to prevent the cooling water 54 from being supplied to the steel plate 30. Since the size of the small hole 51a is only required to allow the air to escape, it is sufficient if the diameter is about several mm. Specifically, the diameter of the small hole 51a is preferably in the range of 3 mm to 10 mm. In addition, the diameter of the small hole 51a is 10 m.
If it exceeds m, the internal pressure of the lower surface cooling header 51 decreases and the water level in the pipe nozzle 52 decreases, resulting in poor responsiveness. If the diameter of the small hole 51a is less than 3 mm, the small hole 51a is likely to be clogged.

Here, the density of the cooling water is ρ, the length of the pipe nozzle 52 projecting from the lower surface cooling header 51 to the outside is h, the pressure loss at the pipe nozzle 52 is ΔP, and the cooling water discharge speed from the small hole 51a. Where v is the area of the small hole 51a, Q is the volume flow rate of the cooling water injected into the lower surface cooling header 51 from the S, and g is the gravitational acceleration. Q = S × v and h = v ² / 2g−ΔP / ρg so that air bubbles are not accumulated in the lower surface cooling header 51 with the minimum amount of cooling water and the lower surface cooling header 5
1 and the pipe nozzle 52 can be filled with cooling water.

Returning to FIG. 3, the structure of the control valve 43 will be described. The control valve 43 (see FIG. 3) is provided with a clearance so as not to be completely closed, and a very small amount of cooling is performed while the OFF signal is output from the valve control device 42 (see FIG. 3). Water cooling header 5
1 can be supplied. For this reason, even when the supply of the cooling water to the steel plate 30 is stopped, the cooling water flows inside the lower surface cooling header 51, so that the inside of the lower surface cooling header 51 dries and the impurities contained in the cooling water solidify. Thus, no clogging occurs in the header. For this reason, it is possible to maintain a uniform cooling water amount in the width direction without performing cleaning for a long period of time, thereby improving the accuracy of uniform cooling in the width direction and improving the facility maintenance. Instead of the above clearance, a bypass through which a small amount of cooling water always flows may be formed.

Although the apparatus for cooling the lower surface of a high-temperature metal sheet of this embodiment is shown as a device for cooling the lower surface of a hot-rolled steel sheet with columnar cooling water, the present invention is not limited to this. It may be used for equipment for cooling, or may be used for equipment for cooling other metal plates. Further, in this embodiment, the case where the cooling water is supplied from only one of the lower surface cooling headers has been described,
A small hole may be provided in a lower surface cooling header having a plurality of cooling water injection paths. The number of small holes is not limited to one, and a plurality of small holes may be provided.

[0023]

As described above, the apparatus for cooling a lower surface of a high-temperature metal plate of the present invention has a structure in which air bubbles are discharged into the header and air bubbles are not accumulated therein, and the response to the on / off operation of the control valve is achieved. Even when used without washing for a long time, the clogging in the header is small, so that the uniformity of cooling in the width direction and the longitudinal direction of the high-temperature metal plate can be maintained even when used for a long time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of an apparatus for cooling a lower surface of a high-temperature metal plate according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a lower surface cooling device for a high-temperature metal plate of FIG. 1;

FIG. 3 is a schematic diagram showing an entire cooling device for a hot-rolled steel sheet using the lower surface cooling device for a high-temperature metal plate of FIG. 1;

FIG. 4 is a schematic configuration diagram showing a conventional lower surface cooling device.

FIG. 5 is a schematic configuration diagram showing a conventional lower surface cooling device.

[Explanation of symbols]

 Reference Signs List 30 steel plate 43 control valve 50 lower surface cooling device for high-temperature metal plate 51 lower surface cooling header 51a small hole 52 pipe nozzle

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshi Kuwako 1 Kawasaki-cho, Chuo-ku, Chiba City Kawasaki Steel Corporation Chiba Works (56) References JP-A-49-129609 (JP, A) JP-A-51 -91009 (JP, A) JP-A-62-174319 (JP, A) Japanese Utility Model Laid-Open No. 1-72909 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C21D 1/00, 9 / 52,9 / 573 B21B 45/02

Claims (2)

(57) [Claims] 1. A high-temperature metal plate lower surface cooling device for cooling a lower surface of a high-temperature metal plate, comprising: a nozzle for supplying cooling water to the lower surface of the high-temperature metal plate in a columnar or film-like shape. A header having an air vent hole formed at an upper portion thereof, and an injection means for injecting a small amount of cooling water into the header while the supply of cooling water from the nozzle to the high-temperature metal plate is stopped. An apparatus for cooling a lower surface of a high-temperature metal plate. 2. The cooling device according to claim 1, wherein an amount of the small amount of cooling water to be injected is substantially equal to an amount of cooling water discharged from the hole, and the header and the nozzle are filled with the cooling water. 2. The lower surface cooling device for a high-temperature metal plate according to claim 1, wherein the cooling device is cooling water adjusting means for adjusting cooling water.