JPH01284419A - Cooling device for hot steel sheet - Google Patents

Abstract

PURPOSE:To uniformize the cooling in a plate width direction and to improve the quality of a steel sheet by dividing a laminar flow nozzle header into the headers which cool the end part in the plate width direction and a center part and arranging these headers in the length direction alternately. CONSTITUTION:A nozzle header is functionally divided into the headers 3, 5 selectively cooling the end part and center part, and end part headers 3a, 3b and center part headers 5a, 5b are adjacently arranged respectively. In this case, the controller 17 for adjusting a water pouring amt. is arranged together with a thermometer 16. The water 19 on a hot steel sheet 1 is flowed in the plate progressing direction, collided with the laminar flow water of the end part header 3b of the downstream and a stagnation point 20 is generated. However no residence is generated because a free flow passage 21 is secured at the center part. A header 5 uniformizes the cooling of the whole plate width to compensate for the cooling of the center part and the quality in the plate width direction of a steel sheet is improved.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a cooling device for hot steel sheets.

(Conventional technology) In the hot rolling process, a slab is first charged into a heating furnace, heated to a predetermined temperature, extracted from the heating furnace, and then rough-rolled, finished-rolled, and then rolled to a predetermined size using a rolling mill. After that, it is subsequently cooled to a predetermined temperature by water cooling on a runout table, and wound into a coil using a down coiler. In the runout table, rod-shaped or plate-shaped laminar water called laminar flow collides with the hot steel plate from the top and bottom surfaces to cool it to a predetermined temperature.

(Problem to be Solved by the Invention) However, especially on the upper surface of the laminar flow cooling, the cooling water discharged from the laminar flow cooling from 7 groups may remain in the form of stagnation on the upper surface of the hot steel plate. Since a large amount of heat remains in the central portion in the sheet width direction, there is a problem in that the central portion in the sheet width direction is relatively overcooled, which particularly deteriorates temperature uniformity in the sheet width direction.

This phenomenon will be explained using FIG. 4. In the figure, laminar water is injected onto the hot steel plate 1 from the pipe laminar nozzle 22 in the direction perpendicular to the plane of the paper. This laminar water collides with the adjacent downstream laminar water as the hot steel plate 1 is conveyed, and a stagnation point 20 is generated. At this time, this stagnation pattern forms a convex mountain shape in the center as shown in Fig. 4, so that the medium-heated part in the width direction of the hot steel plate 1 is relatively supercooled compared to the other parts. It became.

This problem is caused by the flow of water on the board, and controlling this is the basis of countermeasures. Conventionally, as a countermeasure, for example, as described in Japanese Patent Publication No. 62-42967, a cooling nozzle of 7 gou was arranged in a mountain shape with a convex central part in the width direction of the board, and the water flowing in from the upstream on the board was spread across the board width. There is a method of flowing smoothly to the left and right ends of the board in the width direction, without letting it stay in the center. However, in this method, the pattern of the laminar water coming out of the nozzle in the board width direction is mountain-shaped, so the collision points of the board and the laminar water, that is, strong cooling points, are distributed in a mountain shape in the board width direction. There is a drawback that the timing of intense cooling of the central hole portion in one direction and the end portion of the plate is shifted, causing a temperature distribution, and this problem becomes particularly apparent when the rolling speed is slow.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 57-121818, cooling headers are arranged diagonally alternately with respect to the width direction of the board to prevent water on the board from accumulating in the center of the board in the direction of the width of the board. However, this method has the disadvantage that the pitch of the headers in the operator's direction is restricted, especially since it is necessary to alternately arrange adjacent headers diagonally in opposite directions.
It became difficult to achieve the desired cooling capacity, and no effective countermeasures were taken.

In this way, in the conventional technology, there is no method to ensure temperature uniformity in the width direction of the board by controlling the flow of water on the board without being subject to equipment constraints such as the pitch of cooling lugs, and as a result, the temperature distribution is This causes serious problems such as material defects in the width direction and shape defects.

(Means for Solving the Problems) The present invention has been made in view of the above problems, and its gist is that in a laminar flow type cooling device for hot steel plates, a laminar flow nozzle is supplied with 7 gou to the sheet width. The cooling zone is characterized in that its functions are divided into a header that selectively cools the directional ends and a header that selectively cools the center, and these lugs are arranged alternately over the entire length of the cooling zone. This is a cooling device for heated steel plates.

(Function) The present invention divides the cooling function in the board width direction by dividing the header into the center part and the end part of the board, and arranges these headers alternately over the entire length of the cooling zone, thereby creating a gap between both headers. A free flow path for water on the plate is formed in the section corresponding to , and as a result, the phenomenon of accumulation in the center of the plate width is prevented. In addition, under conditions where water on the board tends to accumulate in the center,
Temperature adjustment in the width direction of the board is possible by stopping the water supply to only the 7 parts in the center of the board.

(Example) FIG. 1 is a diagram schematically showing the basic arrangement of a laminar water supply mechanism in a cooling device of the present invention.

The end header 3 is arranged in contact with the center part 7 and 5 as a pair, the end header 3 is placed around the widthwise end of the hot steel plate 1, and the center header 5 is placed in the center arrow part of the hot steel plate 1. Continuously supply laminar water from the pipe laminar nozzle 4.6.

FIG. 2 shows a portion of the cooling device according to the invention, with two end headers 3a, 3bL and two central headers 5a, 5'.

are arranged adjacent to each other with an interval of 1. From the cooling water supply main pipe 7 to the end cooling 7 cooling water branch pipes 8 to the goos 3a and 3h.
10. Cooling water is supplied to the central fn headers 5a, 5b through the on-off valves 12.14, cooling bark W9.11, and on-off valves 13.15. The temperature distribution in the board width direction is measured with the thermometer 16, and the controller 17 increases or decreases the amount of water injected from each header based on the actual temperature measured from the thermometer 16, a pre-given temperature target, and an allowable value for the temperature difference in the width direction. The on-off valves 12, 13, 14, and 15 are individually controlled.

Figure 3 shows the above-mentioned end 7 goo; 3 and center header 5
This shows the laminar water pattern on the hot steel plate 1,
In the figure, the heated steel plate 1 flows from left to right toward the page, and is continuously cooled to a predetermined temperature by laminar water. The plate water 19 on the hot steel plate 1 in such a state flows in the same direction as the conveyance of the thermal cap 1, collides with the laminar flow water from the M1 section header 3b on the adjacent flow side, and reaches a stagnation point 20. occurs.

However, since the free flow path 21 for the board water 19 is secured exactly in the center of this part, the large stagnation of the board water in the center as shown in FIG. 4 does not occur and the board water remains stable. Flows sequentially downstream. Therefore, the occurrence of temperature distribution in the width direction of the plate, which has been a problem in the past, is suppressed. In addition, since the center header 5 adjacent to the downstream side of the end header 3 has only the end header 3, the central part in the board width direction tends to be insufficiently cooled. The controller 17 compensates for insufficient cooling based on the detected temperature distribution of the controller 16.
Laminar water is supplied onto the hot steel plate 1 as needed by a signal from the on-off valve 13, so that the temperature distribution in the width direction of the plate is uniform.
The amount of laminar water injected is controlled by adjusting the opening of 15.

The spacing between the end header and the center part is 100.
It is preferable to set it as mmff1-300+am.

In other words, if the diameter is less than 100 mm, the free flow path will be narrow and the stagnation in the center of the water on the plate will not be sufficiently eliminated;
The above large interval is not preferable because the quenching points are too far apart.

Although the above embodiments have shown the case of a pipe laminar nozzle, they can be similarly applied to the case of a slit laminar nozzle.

(Effects of the Invention) As described above, the temperature distribution in the width direction of the board, which conventionally occurred due to the retention of water in the center of the board, can be reduced by thinning out the nozzles in the center of the header. Furthermore, in the center of the board width, where cooling tends to be insufficient, a dedicated central cooling header is placed as an auxiliary, making it possible to control the temperature of the entire board width, resulting in excellent performance. As a result, the material quality in the width direction of the plate can be made uniform and the cooling shape can be stabilized.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the basic arrangement of the seven cooling channels in the cooling device of the present invention, Fig. 2 is a diagram showing an embodiment of the invention, and Fig. 3 is the flow of water on the plate due to the cooling header arrangement shown in Fig. 2. FIG. 4 is a diagram showing stagnation of water on a plate due to a conventional cooling header. 1... Heat steel plate, 2... Table roller, 3.3a
. 3b... End header, 4... Pipe lamina nozzle, 5.5a, 5b... Lug to center, 6... Pipe lamina nozzle, 7... Cooling water supply main pipe, 8. 9
．． 10.11...Cooling water branch pipe, 12.13.14.1
5... Opening/closing valve, 16... Thermometer, 17... Controller, 19... Board water, 20... Stagnation point, 21
...Free flow path, 22...Pipe lamina nozzle.

Claims (1)

[Claims] (1) In a laminar flow cooling system for hot steel sheets, the function of the laminar flow nozzle header is divided into a header that selectively cools the ends in the width direction of the sheet and a header that selectively cools the center. A cooling device for a hot steel plate, characterized in that cooling zones are arranged alternately over the entire length.