JPS6224162B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling device for hot rolled steel sheets, such as hot thick plate rolling equipment or hot continuous thin plate rolling equipment, which enables uniform cooling in the width direction of hot rolled steel sheets. .

Generally, in a hot rolling facility, a hot rolled steel sheet leaving a finishing mill is water-cooled on a conveyance line to a predetermined temperature under strict temperature control for the purpose of improving material quality. If uneven cooling occurs in the width direction of the sheet during this cooling process, it may cause sheet distortion or non-uniformity of the material, so uniform cooling throughout the entire hot rolled steel sheet is critical to the quality of the product steel sheet. This is becoming one of the problems.

Typical cooling methods for hot-rolled steel sheets include hairpin lamina cooling using rod-shaped laminar water, which has been widely used in the past, and slit lamina cooling using plate-shaped laminar water, which is currently attracting attention due to its extremely high cooling efficiency. In either method, the current situation is that sufficient uniform cooling cannot be achieved even if cooling water is poured evenly in the width direction of the plate. In other words, in the conventional slit lamina cooling method, as shown in FIG. In this case, the cooling rate distribution 4 in the board width direction increases from the center of the board width toward the ends, and furthermore, it tends to increase rapidly near the ends, resulting in large cooling unevenness. This is because, in addition to the essential cooling effect caused by the collision of the laminar flow cooling water 2 with the hot-rolled steel plate 3, the cooling water that has ridden on the hot-rolled steel plate 3 after the collision, so-called plate riding water 5, is transferred to the edge of the hot-rolled steel plate 3. The cooling effect (Ve
>Vc), and the thickness of the plate water 5 is thinner at the edges of the hot rolled steel plate 3 than at the center (he<hc), and the laminar flow cooling water 2 injected is thinner at the thinner end of the plate water 5. This is because secondary factors such as the tendency to penetrate the steam film formed on the surface of the hot-rolled steel sheet 3 and come into direct contact with the hot-rolled steel sheet are strongly at play. Therefore, in order to achieve uniform cooling, some kind of positive means is required, and one possible way to do this would be to adjust the flow rate in the plate width direction so that the cooling rate distribution is constant. In the case of slit lamina cooling, even if the discharge pressure is distributed in the width direction of one nozzle, it becomes uniform after the cooling water is discharged.

In addition, if the difference in discharge pressure distribution is increased or if a partition plate or the like is installed in the nozzle 1 to divide it, cuts will occur in the slit laminar water, which will conversely deteriorate the uniform cooling performance in the width direction of the plate. It is extremely difficult to obtain a flow rate distribution in the width direction of the plate, as it may sometimes be stored away.

On the other hand, as a practical cooling method, as shown in FIG.
There is also a method to achieve uniform cooling by relying only on the cooling effect of the flow of water to avoid overcooling at the ends. Difficult to fine-tune.

The present invention was proposed to solve such conventional problems, and in order to achieve uniform cooling in the width direction of a hot rolled steel sheet, cooling water is uniformly injected, and compared to the center of the sheet width. To provide a cooling device for a hot-rolled steel sheet, which stops the injection of slit lamina cooling water to the edge of the sheet which is supercooled by heating, and cools this part weakly with hairpin lamina cooling water, thereby making it possible to uniformly cool the sheet in the width direction. The purpose is to

Hereinafter, the cooling device according to the present invention will be explained in detail based on the embodiments shown in FIGS. 3 to 5.

FIG. 3 is a schematic configuration diagram showing a cooling device according to the present invention, in which a hot rolled steel sheet 13 after hot rolling is placed in a cooling zone provided on a conveyance line (not shown) for the purpose of improving material quality. cooled down. In the present invention, a slit nozzle 11a and a hairpin nozzle 11b are installed above and below (not shown) the hot-rolled steel plate 13 in the cooling zone, and the slit laminar cooling water 12 flows from the nozzles 11a and 11b.
a and hairpin lamina cooling water 12b are injected to start cooling. That is, we focused on the fact that if the slit laminar cooling water 12a is uniformly injected in the width direction of the sheet from the water injection nozzle of the slit nozzle 11a installed above the hot rolled steel sheet 13, both ends in the width direction of the sheet will be overcooled and uneven cooling will occur. , the width of the slit lamina cooling water 12a is made narrower than the board width to avoid overcooling both ends, to prevent overcooling, and the slit lamina cooling water 12a is poured to both ends of the board where it is not injected, so that it is narrower than the board width. Hairpin lamina cooling water 12b with low cooling efficiency is injected from the hairpin nozzle 11b. Therefore, both ends of the hot-rolled steel sheet 13 are cooled by the synergistic effect of the weak cooling of the hairpin lamina cooling water 12b and the flow in the sheet width direction of the sheet riding water 15 injected at the center, and the central portion of the sheet is cooled. It is possible to make the cooling rate distribution 14 of the slit lamina cooling width and the hairpin lamina cooling width substantially uniform.

On the other hand, the cooling device according to the present invention has means for adjusting the width of the slit lamina cooling water 12a and the width of the hairpin lamina cooling water 12b in order to achieve uniform cooling corresponding to various board widths. This will be explained based on the embodiment shown in FIG. 4. Below the slit nozzle 11a and hairpin nozzle 11b installed in parallel in the board width direction, there is a drainage plate 16 that receives the slit lamina cooling water 12a and the hairpin lamina cooling water 12b, respectively. and 17
Receiving troughs 18 and 19 are installed to catch the cooling water whose flow direction has been changed by the drainage plates 16 and 17 and to discharge it to the outside of the line without letting it fall onto the hot rolled steel plate 13. Therefore, the hot-rolled steel plate 13 is in the range where the drain plates 16 and 17 receive the slit lamina cooling water 12a and the hairpin lamina cooling water 12b.
The width of the cooling water 12a, 12b that is injected into the space is limited. In this embodiment, the arrangement of the drainage plate 16 for the slit lamina cooling water 12a and the drainage plate 17 for the hairpin lamina cooling water 12b is such that the slit lamina cooling water 12a is received by the drainage plate 16, as shown in FIGS. 4b and 4c. There is no drainage plate 17 for the hairpin lamina cooling water 12b in the area where the hairpin lamina cooling water 12b is poured, and the hairpin lamina cooling water 12b is injected onto the hot rolled steel plate 13.
In order to prevent the hairpin lamina cooling water 12b from being injected in the range where the slit lamina cooling water 12a is being injected, the respective drain plates 16 and 17 are installed.
is located. Therefore, the slit lamina cooling water 12a and the hairpin lamina cooling water 12 are distributed in the board width direction.
Either laminar flow cooling water is poured onto the hot-rolled steel plate 13 without overlapping the numbers b. Furthermore, the drain plates 16 and 17 are configured to be able to slide in the width direction (arrow) of the various hot rolled steel sheets 13 while maintaining the above-mentioned positional relationship. The water injection width of the hairpin lamina cooling water 12a can be arbitrarily adjusted according to the difference in the width of the hairpin lamina cooling water 12a, and the water injection width of the hairpin lamina cooling water 12b can also be automatically adjusted accordingly. .

FIG. 5 is an explanatory diagram showing another device for adjusting the water injection width of the laminar flow cooling water 12a in the cooling device according to the present invention, in which the receiving gutter 18 for the slit laminar cooling water 12a and the hairpin laminar cooling water 12
The structure is simplified by integrating the receiving gutter 19 for b.

As described above in detail based on the embodiment shown in the drawings, the hot rolled steel sheet cooling device according to the present invention has a simple structure and uses laminar flow cooling water to maintain a constant cooling rate distribution across the sheet width. This configuration makes it possible to adjust the flow rate of the hot-rolled steel sheet, and produces effects such as no cooling unevenness in the width direction of the hot-rolled steel sheet, no sheet distortion, and improved quality.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of conventional cooling methods;
FIG. 3 is a schematic configuration diagram of the cooling device according to the present invention, and FIGS. 4 a to 4 c show the main parts for adjusting the width of cooling water in the cooling device according to the present invention, where a is a front view thereof, and b 5 is a longitudinal cross-sectional view of a, c is a cross-sectional view taken along the line A-A of b, and FIGS. a is its front view, b is a vertical cross-sectional view of a, c is b
FIG. 11a...Slit nozzle, 11b...Hairpin nozzle, 12a...Slit lamina cooling water, 12b...
Hairpin lamina cooling water, 13...Hot rolled steel plate, 14...
Cooling rate distribution, 15... Plate water board, 16, 17... Drain plate, 18, 19... Receiving gutter.

Claims (1)

[Claims] 1. A slit laminar nozzle is provided for injecting slit laminar cooling water into an area narrower than the sheet width of the hot rolled steel sheet in a cooling zone on a conveyance line for hot rolled steel sheets after hot rolling, and the slit laminar cooling water is Hairpin nozzles for injecting hairpin lamina cooling water, which has a lower cooling efficiency than slit lamina cooling, are arranged at both ends of the plate where water is not injected, and the width of cooling water injection by the slit nozzle and hairpin nozzle can be freely adjusted. A cooling device for hot-rolled steel sheets.