JPS61193717A - Uniform cooling method of steel plate - Google Patents

Abstract

PURPOSE:To unify the distribution of plate temp. after its cooling and to improve the quality by providing in the plate width direction plural shielding plates on the upper part nozzle for cooling the upper face of a steel plate and by controlling so that the water distribution in the plate width direction becomes the optimal flow crown. CONSTITUTION:A cooling water is fed to a nozzle header 2 from a feeding pipe 3, spouting from nozzles 5, 6. In this case a shielding plate 4 is provided at least four places in the plate width direction and one part of the cooling water 7 spouted from the upper part nozzle 5 is discharged through a gutter 9 without colliding with a steel plate 1. The total flow distribution in the cooling zone is controlled by varying freely on each upper part nozzle header 2 the position in the plate width direction of the shielding plate 4. And it is made the maximum at the plate width center part to reduce the flow so much as the end part of the plate width and the plate width end-most part is made not to collide almost directly with the cooling water.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for uniformly cooling a steel plate running in a high temperature state.

(b) Conventional technology When performing online controlled cooling of thick steel plates after hot rolling,
There are the following two problems. The first point is that in cooling the top surface of a steel plate, cooling water jetted from a nozzle collides with the top surface of the steel plate, flows over the steel plate, forms an interference flow, and flows out from both sides of the steel plate. As shown in FIG. 3, when the same amount of water is ejected from the nozzle in the sheet width direction, the amount of cooling water flowing over the steel sheet is smallest at the center portion in the sheet width direction and becomes larger at the side portions, as shown in FIG. As a result, as shown in Figure 5, the overall cooling capacity of the cooling capacity during collision and that of the cooling water flowing over the steel plate becomes larger at the sides in the width direction of the plate, causing uneven cooling. The problem with No. 2 is that the amount of water upstream of the plate is maximum at the end in the width direction of the plate, and that the steel plate is excessively cooled by cooling from the side surface of the steel plate. As a result, the temperature distribution in the sheet width direction after normal cooling becomes non-uniform as shown in FIG.

As a measure to prevent overcooling at the edge of the steel plate, which is the second problem, a shield plate is used only at the edge (approximately 0 to 300 mm) to prevent the cooling water from directly colliding with the steel plate, and to improve the cooling capacity. A technique has been proposed to correct the
1) Figure 7 shows the temperature distribution of the steel sheet after cooling using this technique. However, by shielding only the side portions of the plate width, it is not possible to prevent the first problem, which is non-uniform cooling that occurs in the entire plate width direction.

In order to improve the first problem, it is necessary to control the nozzle water volume distribution in the sheet width direction as shown in Figure 8 so that the overall cooling capacity of the upper surface of the steel plate has the characteristics shown in Figure 10. . To do this, either change the nozzle exit shape or
The header must be divided in the board width direction and the amount of water in each section must be controlled. However, it is difficult to manufacture the nozzle and header and to maintain them, and it is also difficult to control the water volume distribution in the width direction of the plate.

(C) Problems to be Solved by the Invention The problems to be solved by the present invention are to improve non-uniform cooling in the width direction of the plate and supercooling at the extreme end when cooling a steel plate running at high temperatures. It's about finding a way.

B) Means for solving the problem The method for uniformly cooling a steel plate of the present invention is an online cooling method in which a high-temperature steel plate is cooled while running. The above problem is solved by providing a shielding plate in the cooling zone and controlling the water flow distribution in the width direction of the plate so that it has an optimum flow rate crown throughout the cooling zone.

Conventionally, two shielding plates are used to shield only the ends of the plate width to prevent overcooling.The present invention uses a plurality of shielding plates to prevent the amount of impinging water distributed over the entire width of the plate. control, corrects uneven cooling due to water flowing upstream of the plate, and achieves uniform cooling.

(e) Example The schematic structure of an apparatus for carrying out the method of the present invention is shown in FIGS. 1 and 2. Cooling water flows from water supply pipe 3 to nozzle header 2
and is ejected from nozzles 5 and 6. The shielding plates 4 are provided at four or more locations in the plate width direction. As a result, the cooling water 7 jetted from the upper nozzle 5 does not collide with the steel plate 1.
It is discharged through the gutter 9. The position of the shielding plate 40 in the width direction is as follows:
It can be freely changed for each upper nozzle header 2, and the total flow rate distribution in the cooling zone is controlled as shown in Fig. 8. However, the optimum water flow distribution as shown in Fig. 8 is It is determined in advance based on the feed speed, cooling temperature range, plate material, etc. As shown in FIG. 2, the shield plate 4 can freely block the cooling water 7 by the movable arm 10, and its position in the width direction of the plate can also be changed.

As shown in FIG. 1, a portion of the cooling water 7 spouted from the upper nozzle 5 is blocked in the plate width direction and discharged from the gutter 9, but the remaining part directly collides with the steel plate 1 and then flows onto the plate. The water becomes running water and flows out from the side of the steel plate 1. Upper nozzle
The position of the shielding plate 4 is changed for each header 2, and the distribution of the amount of impinging cooling water in the plate width direction throughout the cooling zone is controlled as shown in FIG. Maximize the flow rate at the center of the plate width, reduce the flow rate at the ends of the plate width, and avoid direct collision of cooling water at the extreme ends of the plate width to prevent overcooling. As a result, the distribution of the amount of cooling water flowing on the plate toward the plate side is as shown in Figure 9, and the cooling capacity distribution in the plate width direction, which is the sum of the cooling capacity at the time of collision and the cooling capacity by the water upstream of the plate, is as follows: It becomes uniform as shown in FIG.

The steel plate l is conveyed by the table roller 8. (f) Effect The plate temperature distribution after controlled cooling before implementing the method of the present invention is shown in Figure 6, and the mechanical test results of the product at that time are shown in Figure 6. 12
Each is shown in the figure. An increase in strength on the side of the plate can be seen due to uneven cooling.

As a result of implementing the present invention, the plate temperature distribution after cooling became uniform as shown in Figure 11, and the product mechanical test results also had less variation as shown in Figure 13, resulting in a significant quality improvement.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an apparatus for carrying out the method of the invention. Second
The figure is a side view of a part of FIG. 1. FIG. 3 is a distribution diagram of the amount of cooling water in the width direction of the plate when controlled cooling is performed using the conventional method. FIG. 4 is a water flow distribution diagram upstream of the plate in the width direction when controlled cooling is performed using the conventional method. Figure 5 is an overall cooling capacity distribution diagram in the board width direction when controlled cooling is performed using the conventional method. FIG. 6 is a temperature distribution diagram of the plate after cooling in the width direction of the plate when controlled cooling is performed using the conventional method. FIG. 7 is a temperature distribution diagram of the board after cooling in the board width direction when only the board side width cutting is performed. FIG. 8 is a cooling water flow distribution diagram in the plate width direction when the method of the present invention is implemented. FIG. 9 is a 4ζ enemy distribution diagram upstream of the board in the board width direction when the method of the present invention is implemented. FIG. 10 is an overall cooling capacity distribution diagram in the board width direction when the method of the present invention is implemented. FIG. 11 is a temperature distribution diagram of the plate after cooling in the width direction when the method of the present invention is carried out. FIG. 12 is a graph showing the product mechanical test results when controlled cooling is performed using the conventional method. 13th
The figure is a graph showing the product mechanical test results when the method of the present invention was implemented. 1: Steel plate 2: Nozzle header 3; Water supply pipe
4: Shielding plate 5: Upper nozzle 6: Lower nozzle 7: Cooling water 8: Table/roller 9: Gutter
10: Movable arm patent applicant Sumitomo Metal Industries, Ltd. (5 others) Figure 2 Mizusuke exposed side t and r yid ■id center yid 4 return kIs

Claims (1)

[Claims] In the online cooling method, which cools a high-temperature steel plate while running, shielding plates are installed at at least four locations in the width direction of the upper nozzle for cooling the top surface of the steel plate, and the water volume distribution in the width direction of the plate is adjusted to the optimum flow rate crown in the entire cooling zone. A method for uniformly cooling a steel plate, which is characterized by controlling the temperature so that