JPH07223014A - Nozzle header - Google Patents

Abstract

PURPOSE:To obtain a nozzle header with which a necessary time to stop water is shortened and variation of ejected water between plural nozzles is reduced by mounting plural tubular bodies for introducing air on an upper header which is formed on the outside in the upper part of a lower cylindrical header. CONSTITUTION:The plural tubular bodies 4 for introducing air are mounted in the upper header 8. The length of the tubular bodies 4 is made higher than the height of water column corresponding to the static pressure in the lower header 7. When the cooling-water supply to the plural nozzles 3 for ejecting water downward is stopped, the pressure in the lower header 7 is eliminated and air flows quickly into the chamber through the tubular bodies 4 mounted on the upper header 8. Then, the water in the upper header 8 is replaced and replaced region is quickly extended round the tubular bodies 4, so the time until the water ejected from each nozzle 3 is stopped is shortened and equalized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device used in processes such as hot rolling and thick plate rolling, and more particularly to improvement of a nozzle header used for cooling the upper surface of a material to be cooled.

[0002]

2. Description of the Related Art In so-called controlled cooling, in which a steel sheet is hot-rolled and subsequently cooled to obtain a desired material, a laminar flow is ensured so as to secure a space above the steel sheet without lowering the cooling capacity on the upper surface of the steel sheet. Cooling is generally performed. Further, as is well known, in the hot rolling of the steel sheet, the slab is heated and then rolled, but the steel sheet is cooled during the rolling to cause a temperature difference in each part of the steel sheet. When the above-mentioned controlled cooling of steel plates with this temperature difference is performed, the cooling rate such as controlling the flow rate of cooling water from each cooling nozzle, changing the water amount density, stopping water supply from a part of a group of nozzles, etc. Control is generally performed, and the nozzle header that achieves the appropriate control has been continuously developed. A part of the achievements was filed as a patent and utility model registration application.
No. 4 and Japanese Utility Model Publication No. 61-6966 have been proposed as the nozzle header disclosed.

An example of the most commonly used nozzle header at present is shown in FIG. 4, in which a plurality of hairpin type nozzles 6 are welded to the top end of a cylindrical header 2. The cooling water 13 drops from the nozzle 6 onto the steel plate on the table roller. However, the problem with this type of nozzle header is that the water discharged from the nozzles 6 does not stop instantly and uniformly when a stop command is issued, and some nozzles continue to discharge water for several seconds. Therefore, there is a problem in performing highly controlled cooling.

In order to solve this drawback, the present applicant has developed the nozzle header disclosed in Japanese Utility Model Publication No. 62-41964 and shown in FIG. In this nozzle header, an upper header 8 formed of a cylindrical lower header 7, a roof-shaped member 1 and an outer surface of the lower header 7 is superposed, and further the lower header 7 is penetrated to pass the upper header 8 to the inside of the lower header 7. A plurality of nozzles 3 hanging downward are attached, and communication holes 9 are formed in the lower header 7 and the upper header 8.
Is opened.

In this nozzle header, when the water supply to the lower header 7 is stopped, the cooling water 13 inside the nozzle 3 immediately drops, and the cooling water accumulated in the upper corner of the upper header 8 also escapes from the nozzle 3. Instead, the jet of the cooling water 13 is stopped by the air entering the upper corner portion. As a result, the cooling water can be stopped considerably faster than the nozzle header shown in FIG.

In this nozzle header, however, the space above the upper end of the nozzle 3 in the upper header 8 formed by the outer surfaces of the roof-shaped member 1 and the lower header 7 serves as a connecting pipe, and the space between the nozzles 3 is increased. Although the variation in stopping the cooling water is suppressed, this communication pipe effect also sucks air by the nozzle 3 that first loses water, and the nozzle 3 and the water in the space of the upper header 8 formed by the roof-shaped member 1 absorb the air. Substituting, the effect that the water of the nozzle 3 stops sequentially is utilized.
Therefore, the time from the actual stop of the cooling water supply to the stop of the water injection from the nozzles 3 varies from 0.5 seconds to a maximum of about 1 second among the nozzles.

[0007]

In view of the above situation, the present invention further enhances the function of the nozzle header described in Japanese Utility Model Publication No. 62-41964 to improve the water retention time between a plurality of nozzles in the header axial direction. It is an object of the present invention to provide a nozzle header that reduces variations and has a short water stop time.

[0008]

Means for Solving the Problems
Various studies have been conducted on the nozzle header performance described in JP-A 2-41964. At that time, in order to measure the pressure distribution in the upper header formed between the roof-shaped member and the outer surface of the lower header, the manometer 5 shown in FIG. 2 was attached. It was found that the water discharged from each nozzle 3 stopped almost immediately. The present invention has been made based on this discovery, and has a cylindrical lower header, an upper header formed on the upper outer surface thereof, a plurality of communication holes opened between the upper header and the lower header, and the upper header. In a nozzle header formed by a plurality of nozzles ejecting cooling water downward, a plurality of pipe bodies for introducing air are attached to the upper header. Further, regarding a concrete implementation, the present invention is the nozzle header according to claim 1, wherein the length of the pipe body is higher than a water column height corresponding to a static pressure of water in the lower header. .

[0009]

According to the present invention, when the steel sheet is controlled and cooled on the hot rolling line, a cylindrical lower header, an upper header formed on the upper outer surface of the lower header, and a plurality of communication holes opened between the upper header and the lower header. And a nozzle header formed of a plurality of nozzles for ejecting cooling water downward from the upper header, and a plurality of pipes for introducing air into the upper header are attached to the nozzle header. The time from the stop of the supply of the cooling water to the actual stop of the jetting is further shortened as compared with the conventional case, and the variation in the stop time between the nozzles is eliminated. Further, in the present invention, since the length of the pipe body of the nozzle header is set to be higher than the height of the water column corresponding to the static pressure of water in the lower header, the length of the pipe body is higher than that of the pipe body during use of the nozzle header. It is possible to eliminate the waste of cooling water due to the jetting of water.

The reason why the cooling water is stopped instantaneously is that the pressure in the lower header disappears, air quickly flows into the room from the pipe attached to the upper header, and the water in the upper header is replaced with water. Since the region spreads quickly around the tube, the time until the water exiting each nozzle is short and uniform. Hereinafter, the content of the present invention will be specifically described with reference to FIGS. 1 and 3 in Examples.

[0011]

FIG. 1 shows an example of a nozzle header according to the present invention, in which (a) is a side sectional view and (b) is a front sectional view. In this embodiment, the inner diameter of the tubular body 4 for introducing air is 5 mm.
Using a φ stainless steel tube, the three tube bodies 4 were arranged on a cylindrical lower header 7 having an inner diameter of 100 mmφ and a length (cooling width) of 2000 mm. Attaching the tube body 4 to the upper header 8 is 1/6, 1 / from the end to the cooling width.
The positions are 3 and 1/3, and the functional range of each tube 4 is the same. The length of the tubular body 4 was set to 600 mm because the static pressure of water in the lower header during use is about 0.05 Mpa.

Although the steel sheet after hot rolling was cooled online using the above nozzle header, it was necessary to stop the cooling water during the controlled cooling process, and the supply of cooling water to the nozzle header was stopped. did. As a result at that time, FIG. 3 shows the time from when the supply of the cooling water is stopped until the water jet from each nozzle 3 is actually stopped. From FIG. 3, it can be seen that the water stops in order from the nozzle 3 located near the tube body 4. In this example, the time from when the water in the first nozzle 3 stopped until the water in the last nozzle 3 stopped was 0.5 seconds or less. Therefore, the cooling variation in the width direction of the steel sheet is significantly reduced.

As is clear from this embodiment, the cooling water stops in order from the nozzles 3 in the vicinity of the pipes 4. Therefore, by increasing the number of the pipes 4, the space between the nozzles 3 is further increased. It is possible to reduce variations until the water is stopped.
Further, in this embodiment, the stainless steel tube having the inner diameter of 5 mmφ is used for the tube body 4, but the material is not limited to this and may be any material such as metal, plastic, and rubber. However,
Since the environment of use is high temperature and high humidity, a material with corrosion resistance is preferable (a steel pipe plated with aluminum may be used). Regarding the inner diameter of the tubular body, it is necessary to secure a certain thickness in order to reduce the air inflow resistance.
An inner diameter of about 5 mm is sufficient. Rather, from the viewpoint of prevention, it is desirable to have an inner diameter of 5 mmφ or more.

[0014]

As described above, by applying the cooling water stopping method and the nozzle header according to the present invention, the responsiveness / simultaneity of stopping the cooling water is remarkably improved in the controlled cooling on the hot rolling line. . As a result, a heat-treated steel sheet having excellent quality can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a view of a nozzle header according to the present invention, (a)
Is a side sectional view, and (b) is a front view.

2A and 2B are diagrams showing an experiment that became a hint of the nozzle header according to the present invention, in which FIG. 2A is a side sectional view and FIG. 2B is a front view.

FIG. 3 is a diagram showing a result when a nozzle header according to the present invention is used.

4A and 4B are views showing a commonly used nozzle header, in which FIG. 4A is a side sectional view and FIG. 4B is a front view.

5A and 5B are views showing a structure of a known nozzle header which is a basis of the present invention, FIG. 5A is an overall explanatory view, FIG. 5B is a partial sectional view of a front surface, and FIG. is there.

[Explanation of symbols]

 1 Roof-shaped member 2 Cylindrical header 3 Nozzle 4 Tubular body 5 Manometer 6 Hairpin type nozzle 7 Lower header 8 Upper header 9 Communication hole 10 Steel plate 11 Cooling water supply pipe 12 Cooling water supply pump 13 Cooling water

Claims (2)

[Claims] 1. A cylindrical lower header, an upper header formed on the upper outer surface thereof, a plurality of communication holes opened between the upper header and the lower header, and a plurality of jetting cooling water downward from the upper header. A nozzle header formed of a plurality of nozzles, wherein a plurality of tubes for introducing air are attached to the upper header. 2. The nozzle header according to claim 1, wherein the length of the tube body is higher than the height of a water column corresponding to the static pressure of water in the lower header.