JPH07185640A - Rear surface cooler for steel sheet - Google Patents

Abstract

PURPOSE:To produce a coolant which stabilizes a a boundary part for collision against flowing water, makes the temp. of a steel sheet uniform and has a good shape free from shape defects and strip cutting flaws. CONSTITUTION:A flow water control plate 1 is installed in a position (boundary part for collision) 6 where the coolants which are discharged from slit nozzles 2a, 2b collide against a steel plate 3 and flow along the rear surface of the steel sheet 3 collide each other. The flow of the coolant in a flow water progressing direction in the boundary part 6 for collision with the flow water is thereby hindered and, therefore, the meandering state undulating in the flow water direction and the flow fluctuating with time are suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for hot-rolled high-temperature steel plates, and more particularly to a bottom surface cooling device for steel plates that achieves uniform temperature distribution.

[0002]

2. Description of the Related Art In a thick plate manufacturing process, a controlled cooling method and apparatus for cooling a hot-rolled high-temperature steel sheet to a predetermined temperature online have been put into practical use for the purpose of reducing alloying elements and improving mechanical properties. , Is being produced.

As such a cooling method, for example, as disclosed in Japanese Patent Application Laid-Open No. 51-61415, a method of charging the entire steel sheet into the apparatus and simultaneously cooling it simultaneously, and Japanese Patent Application Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication No. 8-3916, there is a method of sequentially cooling from the front end toward the rear end while passing a steel plate. In each of the above methods, the upper surface of the steel sheet is cooled by cooling water supplied from a nozzle such as a spray (JP-A-60-43435) or a laminar flow (JP-A-52-85909). At the same time, the lower surface of the steel sheet is sprayed with a cooling water supplied from a spray or mist (Japanese Patent Laid-Open No. 52-85909), and a method of jetting a cooling water flow from a nozzle below the water surface (Japanese Patent Laid-Open No. 61-15927). Is cooled by.

There are many techniques for the controlled cooling method of the hot-rolled high-temperature steel sheet as described above, which have been already put into practical use.

However, in these prior arts, it is known that the unevenness of the steel sheet temperature and the defective shape are caused by the difference in the cooling rate, and the variation of the material and the stripping distortion occur. And this correction measure requires a lot of cost and man-hours. In particular, when cooled by cooling water supplied from a spray nozzle or a circular tube laminar nozzle or by cooling water ejected from a nozzle below the surface of the water, the cooling speed at the position where the cooling water of the steel plate directly collides and at other positions The difference is remarkable, and the nozzle arrangement and the like have been devised.

As a cooling method for improving the cooling uniformity in the plate width direction on the upper surface of the steel sheet, a method using a slit laminar nozzle disclosed in JP-A-56-163216 or JP-A-58-3916, and , JP-A-5
As disclosed in Japanese Patent Laid-Open No. 8-32511 and the like, measures such as providing a shield plate at the end of the steel plate are adopted.

[0007] Also, on the bottom surface, the actual opening of Sho 58-17
It has been attempted to achieve uniform cooling in the width direction by cooling using a slit nozzle as described in Japanese Patent No. 5805, Japanese Patent Laid-Open No. 58-86904, Japanese Patent Laid-Open No. 61-264137.

[0008]

However, when the slit nozzle is used to cool the lower surface of the steel plate, the cooling water discharged from the nozzle forms a flowing water region flowing along the lower surface of the plate after colliding with the steel plate. Then, when cooling is performed using a plurality of slit nozzles, the cooling water in the flowing water region collides with each other on the lower surface of the steel plate. The collision boundary of this cooling water is
Although it is desirable to form the slit nozzle in parallel with the slit nozzle, in actuality, as shown by 6 in FIG. 2, it is a meandering state that is uneven in the flowing water direction (direction orthogonal to the slit nozzle), and further changes with time. Due to the unevenness and fluctuation of the cooling capacity on the lower surface, the temperature of the steel sheet is made non-uniform. FIG. 2 is a perspective view showing a conventional cooling water collision boundary portion. In FIG.
Reference numeral 2 is a slit nozzle, 3 is a steel plate, 4 is cooling water flowing on the lower surface of the steel plate, 5 is a cooling water direct-irradiation portion, and 6 is a boundary portion formed by running water collision. Therefore, it is desired to form a stable boundary in order to make the temperature of the steel sheet uniform.

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a bottom surface cooling device for a steel sheet, which can make a temperature of the steel sheet uniform and efficiently produce a coolant having a good shape without a defective shape and a stripping distortion.

[0010]

According to the present invention, a plurality of slit nozzles are arranged below a steel plate at predetermined intervals in the longitudinal direction of the steel plate and are arranged in parallel to each other in the width direction of the steel plate. A mechanism for cooling the lower surface of the steel sheet by injecting cooling water from the slit nozzle toward the lower surface of the steel sheet, and along the lower surface of the steel sheet after colliding with the lower surface of the steel sheet by being jetted from each of the adjacent slit nozzles. As the cooling water collision boundary portions where the flowing cooling water collides with each other are linear, between the adjacent slit nozzles, provided substantially vertically in parallel with the slit nozzles, vertically so as not to contact the steel plate. It is characterized in that it is composed of a movable plate-like body.

A plurality of slit nozzles are arranged below the steel plate at predetermined intervals in the longitudinal direction of the steel plate and are arranged in parallel to each other in the width direction of the steel plate, and cooling water is jetted in a plate shape from the slit nozzles. In the device for cooling the lower surface of the high-temperature steel plate, a slit nozzle is provided between adjacent slit nozzles so that the positions (boundary portions) where the cooling water flowing along the lower surface of the steel plate collides with each other after the collision of the steel plate become linear. The running water control plates that can be moved up and down in parallel and so as not to contact the steel plates are installed almost vertically. Further, it has a mechanism capable of controlling the distance between the water flow control plate and the steel plate according to the plate collision flow velocity of the cooling water.

[0012]

[Operation] After the collision of the steel plates, the flowing water control plate is installed at a position (collision boundary part) where the cooling water flowing along the lower surface of the steel plate collides with each other. Since it is hindered, it is possible to suppress the meandering state that is uneven in the flowing water direction and the flow that fluctuates with time.

By installing the flowing water control plate so as to be able to move up and down so as not to come into contact with the steel plate, there is no passage obstacle due to contact with the steel plate and the surface of the steel plate is not damaged. Also,
Since there is a mechanism that can control the distance between the water flow control plate and the steel plate according to the plate collision flow velocity of the cooling water, the effect of this water flow control plate is within the range that does not damage the passage of the steel plate due to contact with the steel plate Can be improved. That is, when the plate collision flow velocity of the cooling water is high, it is possible to make the gap between the steel plate and the water flow control plate as small as possible so that the effect of the water flow control plate can be exhibited. On the other hand, when the plate collision flow velocity of the cooling water is slow such that the flowing water collision part is stably formed in parallel with the slit nozzle, increasing the distance between the steel plate and the flowing water control plate allows the steel plate to pass through. It is possible to prevent any trouble and to prevent the water flow control plate from being damaged during the passage.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on the embodiments shown in the drawings. FIG. 1 is a conceptual view showing one embodiment of a steel plate lower surface cooling device of the present invention. The slit nozzle 2 is provided in the width direction of the steel plate. In FIG. 1, the longitudinal direction (moving direction) of the steel plate is the left-right direction of FIG. The lower surface cooling device for a steel sheet according to the present invention includes slit nozzles 2a and 2
The cooling water discharged from b flows along the lower surface of the steel plate 3 along the lower surface of the steel plate after collision, and is arranged at a position (boundary part) 6 where these two flowing water collide, in parallel with the slit nozzle 2 and substantially vertically. 1 is provided with a plate-like body (flowing water control plate) 1, and this flowing water control plate 1 is movable in the vertical direction shown by the arrow in FIG. In the present invention, the plate-like body is not particularly limited to the water flow control plate, and may be a steel plate having a plate thickness of about 10 mm. Further, the cross section of the plate-shaped body is not limited to the rectangular shape as shown in FIG. 1, and may be a triangular shape or the like. Further, in the present invention, the mechanism for moving the plate-like body in the vertical direction is not particularly limited. Needless to say, in an actual line facility, the plate-shaped members are arranged between the slit nozzles in the longitudinal direction (moving direction) of the steel plate.

In order to confirm the effect of the present invention, the stability of the flowing water collision boundary portion (hereinafter referred to as "boundary portion") 6 is varied by varying the plate collision flow velocity of the cooling water and the distance between the steel plate and the flowing water control plate. I checked about. Here, the slit of the slit nozzle is 5 mm (a in FIG. 1), and the thickness of the running water control plate 1 is 5 mm.
mm (b in FIG. 1) and 0.1 above the slit nozzle 2.
An acrylic plate instead of the steel plate 3 was installed at the position of m (c in FIG. 1), and the flow state of the boundary portion 6 was observed from above. The result is shown in FIG. Here, in FIG. 3, ◯: conditions for forming a boundary that is stable and parallel to the slit nozzle, Δ: conditions for forming a slightly uneven boundary,
And x mark: a condition for forming a large meandering boundary portion,
Is shown.

As shown in FIG. 3, even if the flowing water control plate is not provided, even if the boundary portion is uneven and the boundary portion is largely meandering, a stable boundary portion can be provided by installing the flowing water control plate. Can be formed. It is also recognized that the distance between the flow control plate and the steel plate that stabilizes the boundary portion depends on the plate collision flow velocity of the cooling water.

FIG. 4 shows the plate from the plate center portion of the steel plate immediately after cooling at the boundary between the case where the flow water control plate of the present invention is installed and the case where the flow water control plate is not installed (comparative example outside the scope of the present invention). It is a graph which shows the temperature distribution in the width direction to the end.
In FIG. 4, ● indicates the presence of the flow control plate (example of the present invention), and ○ indicates the absence of the flow control plate (comparative example). The plate thickness of the steel plate was 40 mm, and the plate collision flow velocity of the cooling water was 3.75 m / s. Forced cooling with cooling water was performed only on the lower surface of the steel sheet, and the upper surface was allowed to cool. It can be seen from FIG. 4 that the temperature is more uniform when the flow control plate is installed. This is because the boundary part was stabilized by installing the flow control plate.

[0018]

As described above, according to the present invention, since the temperature of the steel sheet is made uniform, the shape defect and the stripping strain are reduced, the plate straightening rate can be reduced, and the cooling material having a good steel plate shape can be obtained. Can be efficiently and industrially produced.

[Brief description of drawings]

FIG. 1 is a conceptual view showing one embodiment of a steel plate lower surface cooling device of the present invention.

FIG. 2 is a perspective view showing a flowing water collision boundary portion when the flowing water control plate of the present invention is not provided.

FIG. 3 is a graph illustrating the effect of the water flow control plate according to the embodiment of the present invention.

FIG. 4 is a graph showing the temperature distribution in the steel plate width direction with and without the flow control plate of the present invention.

[Explanation of symbols]

 1 Flowing water control plate 2, 2a, 2b Slit nozzle 3 Steel plate 4 Cooling water flowing on the lower surface 5 Cooling water direct exposure part 6 Boundary part formed by running water collision

Claims (3)

[Claims] 1. A plurality of slit nozzles are provided below the steel plate at predetermined intervals in the longitudinal direction of the steel plate and are arranged in parallel to each other in the width direction of the steel plate. A mechanism that cools the lower surface of the steel plate by spraying cooling water toward it, and cooling in which cooling water sprayed from each of the adjacent slit nozzles collides with the lower surface of the steel plate and then flows along the lower surface of the steel plate. From the plate-shaped body that is vertically movable parallel to the slit nozzles and is vertically movable so as not to come into contact with the steel plate, between adjacent slit nozzles so that the water collision boundary portion becomes linear. A bottom surface cooling device for a steel sheet, which is characterized by: 2. Each of the two slit nozzles and the plate is controlled according to the magnitude of the flow rate of the cooling water jetted from the two slit nozzles adjacent to each other and the distance between each of the two slit nozzles and the steel plate. The device of claim 1 for controlling the distance to and from the feature. 3. The mechanism according to claim 1, further comprising a mechanism capable of controlling a distance between the flowing water control plate and the steel plate according to a flow velocity when the cooling water jetted from the slit nozzle collides with the steel plate. apparatus.