JPS6030730B2 - Cooling equipment for hot rolled steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for cooling continuously hot-rolled steel strip.

The continuously hot-rolled steel strip (hot strip) is cooled on a hot run table at the exit side of the rolling mill.

The main purpose of this cooling is to ensure a predetermined winding temperature, but depending on the type of steel, the temperature history during cooling has a large effect on the material. For example, for certain types of steel, the speed from finishing temperature to 75,000 is 6,000/sec.
The following slow cooling is performed, and the temperature from 750℃ to the coiling temperature is 10℃.
A cooling pattern that performs rapid cooling of 0 qo seconds or less is required. In order to adopt such a special cooling pattern, the following operation is generally used in the conventional method.
Figures 1A and 1B show cooling devices that are widely used in the auxiliary industry.In the figure, 1 is a header pipe;
is equipped with a large number of pipe nozzles 2, and the cooling water 6 is always flowed out, and when cooling is not required, the pipe nozzle 2 is
As shown in the figure, the shielding plate 3 is moved under the cooling water 6 using the fluid pressure cylinder 5 to cause the cooling water 6 to flow into the gutter 4. When cooling, the shielding plate 3 is retracted as shown in Figure B to cool the water. Sprinkle water 6. In this case, the water supply to each tube 1 is 1
This is done through a common water supply pipe. In the zone where rapid cooling is required, cooling water is discharged from a large number of header pipes, and in the slow cooling zone, the header pipes to which water should be discharged are selected and water is thinned out. However, according to such a method, the maximum cooling capacity of the quenching zone is determined by the number of header tubes, so there is a limit to the cooling capacity.

■Even if the number of header tubes is thinned out in the slow cooling zone, the amount of water discharged per header tube remains the same.
There have been problems with the hot rolled steel plate directly under the nozzle, such as problems with the material quality. The present invention was made to solve the above problems, and the cooling water tank installed at the top of the cooling zone is divided into a plurality of banks in the direction of travel of the hot rolled steel plate, and the bottom surface of the cooling water tank is A cooling device for a hot-rolled steel sheet, characterized in that a large number of nozzles equipped with water stop valves are arranged, and the cooling pattern of the hot-rolled steel sheet is controlled by controlling the water level of each bank and selecting the number of flowing water nozzles. This is only a summary, and will be explained in detail below with reference to embodiments shown in FIGS. 2 to 7.

FIG. 2 is an explanatory diagram of the configuration of the apparatus of the present invention, and FIG. 3 is a control system diagram. In FIG. 2, numeral 7 indicates a hot rolled steel strip running in a cooling zone, and a cooling water tank 8 is installed above this cooling zone. As shown in the figure, this cooling water tank 8 is provided with a partition plate 9 in the traveling direction of the hot-rolled steel strip to form a plurality of banks 10, 11, 12, 13, and 14 (five chambers in this example). Reference numeral 15 designates a number of slit nozzles that are opened at the bottom of each bank 10 to 14, and each nozzle 15 is equipped with a water stop valve 16 so that each nozzle 15 can be opened and closed independently.

17 is a water level gauge provided in each bank 10-14, 18 is a water supply pipe, and this water supply pipe 18 is provided with a short water supply pipe 19 having a valve 20 for supplying water to each bank 10-14.

In FIG. 3, reference numeral 21 denotes a control device, into which, for example, a predetermined desired cooling pattern and the corresponding control water level layer of each bank are inputted.

On the other hand, signals from the water level gauges 17 of each bank are also input, and each valve 20 and each nozzle water stop valve 16 are controlled thereby. FIG. 4 shows an example of a cooling pattern, where the a curve shows the first half slow cooling-the second half rapid cooling, and the b curve shows the first half rapid cooling-the second half gradual cooling.

b in FIG. 4 by the apparatus of the present invention shown in FIGS. 2 and 3.
When obtaining a curved cooling pattern, the control water position can be adjusted to the highest, intermediate, or
The water level is controlled by setting the lowest three levels, and the number of nozzles used is controlled by operating the water stop valve 16 to control the winding temperature.

That is, in the rapid cooling zone, strong cooling is possible by controlling the water level of the bank to the highest value and flowing a water amount d greater than the water amount C defined by the number of installed nozzles as shown in FIG.
On the other hand, in the slow cooling zone, slow cooling is performed by controlling the water level in the bank to a desired minimum value within the range that allows for rectification, and at the same time operating a water stop valve to control the number of nozzles in use. That is, point e in Figure 5 shows the case where slow cooling is performed by controlling only the number of nozzles used, but by combining this with water level control, compared to the case where only the number of nozzles used is controlled. point f while obtaining the same cooling effect.
As a result, the number of nozzles can be increased to 1,000, and the amount of water per nozzle can be reduced. As a result, rapid cooling in the vicinity of the impact point of falling water on the nozzle can be suppressed, and problems with materials can be solved. Figure 6 further explains the relationship shown in Figure 5. In the rapid cooling zone, the water level of the bank in that zone is controlled (high) with respect to the average cooling capacity c when the number of nozzles used is kept constant at maximum. in case of,
The average cooling capacity increases to d, while in the slow cooling zone, the local cooling capacity near the nozzle falling water impact point increases from point e to point f.
This shows that it is possible to alleviate the

FIG. 7 shows another embodiment of the invention. In this example, instead of the slit nozzle 15, a predetermined number of known pipe lamina nozzles 21 are provided on the bottom of the cooling water tank 8 of the above embodiment via a water stop valve 16', and the other parts are the same as the above embodiment. It remains the same, can be operated in the same way, and has the same effect. Although the embodiments have been described in detail above, it goes without saying that the number of banks and the number of nozzles are not limited to those shown in the embodiments and can be set arbitrarily. or,
According to the apparatus of the present invention, it goes without saying that not only cooling with a special cooling pattern but also a cooling pattern for controlling the winding temperature can be easily implemented.

[Brief explanation of drawings]

FIGS. 1A and 1B are explanatory diagrams of a conventional cooling device, FIGS. 2 and 3 are explanatory diagrams of an embodiment of the present invention, FIG. 4 is an explanatory diagram of two examples of cooling patterns, and FIGS. FIG. 6 is an explanatory diagram of the operation and effect of the apparatus of the present invention, and FIG. 7 is a schematic diagram for explaining the main part of another embodiment of the present invention. 8...Cooling tank, 10-14...Bank, 15.
...Nozzle, 16...Water stop valve, 17...Water level gauge. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 The cooling water tank installed at the top of the cooling zone is divided into multiple banks in the direction of travel of the hot-rolled steel plate, and a number of nozzles equipped with water stop valves are placed on the bottom of the cooling water tank, and each bank is A cooling device for hot-rolled steel sheets, characterized in that the cooling pattern of the hot-rolled steel sheets is controlled by controlling the water level and selecting the number of flowing water nozzles.