JPH01178309A - Device for cooling of hot rolled steel sheet - Google Patents

Abstract

PURPOSE:To uniformize cooling effect by installing nozzles in plural lines at different heights in a cooling water header and installing V-shaped dewatering troughs and reversal V-shaped troughs for dewatering and water discharging between nozzles and a hot rolled steel sheet. CONSTITUTION:A gate 5 and slit plates 15a, 15b are installed in a cooling header 2 and plural slit nozzles 10 having different heights are arranged. Further, V-shaped and reversal V-shaped dewatering troughs 11, 12 freely shifting in the rolling direction by use of handling bars 13 are installed between the nozzles 10 and a hot rolled steel sheet 4; a water discharge trough 14 having a sufficient length is installed under the troughs 11, 12. Respective nozzles 10 automatically perform on-off operations of watering based on variations in a water level in the header 2 and the troughs 11, 12 partially interrupt cooling water through movement of the troughs 11, 12 to uniformize temps. of the sheet 4. Thus, the cooling effect is uniformized because necessary and proper watering areas are optionally and automatically set.

Description

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

There are two types of hot rolled steel plates: thick plates produced by Noah plate rolling and hot strips produced by continuous hot rolling, and the present invention can be applied to either of them. The following description will be made using a cooling device for a continuous hot rolling line as a representative example.

(Prior art) Normally, in the process of a continuous hot rolling line, a slab is first charged into a heating furnace, heated to a predetermined temperature, extracted from the heating furnace, and then subjected to rough rolling, finishing rolling, and a predetermined rolling process. After being rolled to the desired size, it is cooled to a predetermined temperature by water cooling on a conveyor table called a runout table at the rear of the exit side of the finishing rolling mill, and then rolled into a coil by a winder. It is wound up.

Cooling on the runout table was performed by colliding a rod-shaped or plate-shaped laminar water flow called laminar flow from the top surface of the hot strip to cool it to a predetermined temperature.

However, the nozzle and header that form the laminar flow and supply the cooling water have a problem in the amount of water supplied depending on the size of the nozzle attached to the ladder, in order to make the water flow collide with the hot strip in a laminar flow state as described above. There was a problem with restrictions.

Furthermore, the temperature distribution of the hot strip before cooling, particularly in the width direction of the plate, is heated from all four peripheries in the heating furnace, so when viewed in the width direction of the plate, the temperature distribution is 0-shaped, that is, from the center of the width of the plate to the ends. As the hot rolling process continues, the edge in the width direction of the sheet becomes higher.
The temperature decreases because the cooling rate to the atmosphere during rolling is fast.

Regarding the temperature distribution in the width direction of the hot strip in such a state, the temperature around the center of the width is affected by heating, and the temperature at the edges is lower due to the influence of air cooling during rolling, so the temperature is just right. An M-shaped pattern is shown.

Therefore, when finish rolling is finished and water cooling is performed on the runout table, the lower temperature center and end portions are supercooled than other portions, so the winding temperature at the end of cooling is lower in the width direction. There was a serious problem with the material and shape of the hot strip because of the non-uniformity.

Regarding the above-mentioned two problems, first of all, the problem of restrictions on the amount of water supplied to the water cooling header can be explained by referring to Figure 4. Figures 4 (a) and (b) show that Rod-shaped laminar water flow with water flow control method (hereinafter abbreviated as Vilaminar)
The header is shown, and the cooling water supplied into the header 2 by the water supply pipe 1 is evenly distributed in the width direction of the board by the nozzle 3 attached to the header 2, and is then dropped and supplied to the hot strip 4. . Also, Figure 5(a)
(b) is a plate-like laminar water flow (hereinafter abbreviated as slit laminar)
This figure shows a header, in which cooling water is temporarily stored in the header 2 from the water supply pipe 1, overflows from the weir 5, and is supplied to the nozzle 3, after which it is supplied to the hot strip 4 in the same manner as in FIG. 4 above.

In the conventional numerically implemented method described above, the size and dimensions of the nozzle 3, as shown in FIG. There was a problem in that the discharge flow rate from the nozzle 3 was restricted, and as a result, the amount of water supplied was restricted. That is, as shown in FIG. 6(a), when the amount of water filled from the nozzle becomes larger than the appropriate amount of laminar flow water determined by the typical dimensions of the nozzle, the water flow becomes turbulent and scattered due to the increase in the nozzle discharge flow rate. This results in non-uniform cooling (state 1 in FIG. 6(b)). On the other hand, if the amount of water from the nozzle becomes small, the flowing water will split (state 3 in Figure 6 (b)), causing non-uniform cooling as described above, as well as preventing lamination, which is the original purpose of the nozzle. A problem arises in that no flow is formed, resulting in a decrease in cooling capacity.

In order to solve these problems, proposals were made such as the Japanese Patent Publication No. 62-52014 and the Japanese Utility Model Publication No. 56-408.
14 are known. Japanese Patent Publication No. 62-52014 installs partitions that divide the header in the longitudinal direction, controls the amount of water supplied to each partition, and cools the steel plate by varying the amount of water injected in the width direction. Although the water flow control range is expanded, the nozzle itself is single. Therefore, for the reasons mentioned above, the water flow control range is naturally determined by the representative dimension of a single nozzle.

Next, in the method shown in Japanese Utility Model Application No. 56-40814, a water draining device is attached to each of a plurality of nozzles and operates independently, so that the water flow control range is certainly expanded by the number of attached nozzles. However, when cooling water is supplied into the header, the cooling water is discharged from each nozzle all at once, so the amount of cooling water is always equal to the amount of water from one nozzle multiplied by the number of nozzles.
In other words, Q = q All the cooling water discharged from the nozzle is wasted, causing economic problems.

On the other hand, as a countermeasure for uneven cooling in the width direction,
The proposal No. 35524 discloses that cooling water supplied to the ends of the steel plate in the width direction is blocked by packets. Although this method is certainly effective against overcooling at the ends of the plate in the width direction, it is difficult to apply this method to the center portion in the width direction, and it is insufficient as a countermeasure.

(Problems to be Solved by the Invention) As described above, in the prior art, the header used for cooling,
The size of the nozzle limits the amount of water supplied, resulting in limited operational freedom.Also, there is no cooling control function in the width direction of the plate, which results in uneven cooling, which adversely affects the quality of the hot strip. A series of measures such as these were necessary.

(Means for Solving the Problems) The present invention has been made to advantageously solve the above problems, and its gist is as follows: (1) In a laminar flow type cooling device, a cooling water header is used. A cooling device for hot-rolled steel sheets, characterized in that multiple rows of nozzles are arranged at different heights to automatically turn on and off water injection according to changes in the water level in the header. and (2) V-shaped or inverted V-shaped drainage gutter is superimposed between the laminar flow nozzle and the hot rolled steel plate, and each is connected to an operating rod so that it can move forward and backward independently in the direction of travel of the hot rolled steel plate. The cooling device for hot-rolled steel sheets as described in item (+) above, further comprising a drain gutter having a length greater than the width of the hot-rolled steel sheet and arranged in engagement with the lower part of the drain gutter.

It is in.

(Function) Since the header has a configuration in which multiple rows of nozzles are arranged at different heights, it is possible to increase the amount of cooling water discharged from the nozzles per header by multiple times.

Moreover, in this discharge amount control, water injection is automatically turned on and off for each nozzle having a different water surface height depending on an increase or decrease in the amount of cooling water supplied to the header, that is, a change in the water level in the header.

In addition, since the ■-shaped and inverted V-shaped drainage troughs are stacked one on top of the other and each is independently arranged to move forward and backward in the direction of steel plate movement, the cooling water supply cutoff area in the width direction can be set arbitrarily. That is, by selecting the amount of advance and retreat of the V-shaped drain gutter, the cooling water supply cut-off region to the end portion side in the width direction is determined, overcooling of the end portion side is prevented, and the temperature approaches the center portion side. In addition, by selecting the amount of advance and retreat of the inverted V-shaped drain gutter, the cooling water supply cutoff area to the center in the width direction is determined, preventing overcooling of the center and minimizing the temperature difference with other parts. Become.

On the other hand, since a drainage gutter with a length larger than the width of the hot-rolled steel plate is installed at the bottom of the drain gutter, the cooling water blocked by the drain gutter is received by the drain gutter and sent to the drain gutter. It is collected and discharged out of the line without contacting the hot rolled steel sheet at all.

(Example) Figures 1, 2, and 3 show examples of the present invention.
FIG. 1(a) and FIG. 1(b) are perspective and cross-sectional views showing the overall structure of the one-type slit lamina type.

In the figure, 1 is a water supply pipe, 2 is a header arranged perpendicular to the traveling direction of the hot-rolled steel plate, 4 is the hot-rolled steel plate, 5 is a weir installed in the header 2, 7 is a slit laminar, and 8 is a conveyance roller. , 9 is the water surface in the header, IO is the multiple slit nozzle arranged in the header 2, 11 and 12 are the V-shaped drain gutter (hereinafter referred to as the V-shaped line), and the inverted V-shaped drain gutter (
(hereinafter referred to as an inverted V-shaped gutter) is arranged in an overlapping state between the slit nozzle and the hot rolled steel plate 4, and is connected to the operating rod 13, so that each can independently move forward and backward in the direction of movement of the hot rolled steel plate 4. It is. The V-shaped line 11 and the inverted V-shaped gutter 12 partially block the cooling water from the slit nozzle in the width direction by changing the amount of advance and retreat, thereby making the temperature of the hot rolled steel plate 4 uniform in the width direction. . 14 is the V-shaped line 11 and the inverted V-shaped gutter 1
A drainage gutter is disposed at the lower part of the drain 2 and collects the cooling water cut off by the water drainer FALL and 12 and discharges it to the outside of the urn, and its length is longer than the width of the hot-rolled steel plate 4.

Next, +5a and 15b are slit plates arranged with water surface heights higher than the weir 5 in the header 2, 16 is a cooling water passage partitioned by stiff slit plates, and 17 is supplied from the water supply pipe 1 into the header 2. 18 is a cooling water outlet of a slit nozzle formed by a plurality of slits 10;
9 indicates the cooling water passage width (water film thickness), and 20 indicates the height interval of the slit plates forming the slit nozzle.

The cooling water 17 continuously supplied into the header 2 by the water supply pipe 1 is continuously supplied to the plurality of slits 10 in the form of overflowing the weir 5, and after being rectified within the plurality of slits 10, becomes the slit laminar 7. The cooling water then falls and flows out from the cooling water outlet 18 below the plurality of slits 10. FIG. 1(b) schematically shows the flow of cooling water when the amount of cooling water supplied into the header 2 changes.

First, when the amount of cooling water is small, it falls and flows out through the innermost side of the multiple slits 10 as shown in Figure 1 (b-1), and when the amount of cooling water is large, it flows out as shown in Figure 1 (b-2). As the water surface 9 rises, the water overflows the slit plate 15a and flows down through the adjacent passage 16 in the same manner as described above. In this way, the water level 9 rises and falls depending on the amount of cooling water supplied,
As a result, although the appearance is good, the representative dimensions of the passage 16 change, which inevitably expands the water flow control range. Note that the width 19 of the plurality of passages 16 formed by the plurality of adjacent slit plates +5a and 15b is set so that a stable laminar flow can be obtained at the minimum amount of water required for operation, and The number of the plurality of passages 16 formed by the plurality of slit plates 15a and 15b is an integer value obtained by dividing the maximum amount of water required for operation by the minimum amount of water also required, that is, N = QffiaX /Q1n where N: passage number (integer value) Q rmax : Required maximum amount of water Q win ' Given by the required minimum amount of water. Note that the above formula is just a basic formula, and the width 19 and number of the passages 16 are not particularly defined as long as they are set so as to stably obtain a laminar flow. Further, the height interval 20 between the plurality of slit plates 15a and 15b installed adjacent to each other is appropriately determined according to the amount of water to be controlled and to prevent cooling water from overflowing from the header 2 and leaking to the outside. Furthermore, in order to stably obtain the laminar 70-, the slit plates 15a, 1
5b, it is desirable to set an arbitrary angle 21 from the vertical direction depending on the amount of water to flow.

On the other hand, the V-shaped gutter II and the inverted V-shaped gutter 12 are shown in FIG.
), it is attached below the discharge port 18 below the plurality of slits 10 via the operating rod 13, and is attached adjacent to the outlet of the V-shaped gutter 11 and the inverted V-shaped 1d12. The drainage gutter 14 can be installed with ease. V-shaped gutter 1
1. The operating rods 13 attached to the inverted V-shaped gutter 12 slide and move independently in the conveying direction of the hot strip 4. Depending on the movement distance of this operating rod 13, the V-shaped gutter 11
, the inverted V-shaped gutter 12 controls the length 22 of the slit laminar 7 in the board width direction, and cuts (moves) unnecessary cooling water at any position in the width direction.

That is, the upper example of FIG. 1 (d-1) is a V-shaped gutter I.
+ shows a state in which the central part of the board width is widely masked, and the lower example in FIG. There is. In the figure, 22 indicates the supply width in the sheet width direction of the slit laminar, 23 indicates excess cooling water whose supply onto the hot rolled steel plate 4 is cut off by the V-shaped gutter 11 and the inverted V-shaped gutter 12, and the drain gutter 14 and is discharged outside the line. This prevents overcooling of the center or end portions in the width direction of the plate, and as a result, the temperature distribution in the width direction of the plate after cooling can be made uniform.

FIGS. 2 and 3 show another embodiment of the present invention using a pipe laminar, showing the structure of a header and a nozzle, and the drain gutter and drainage gutter are the same as those in FIG. 1, so illustration thereof is omitted.

Figure 2 shows the arrangement of vibrator nozzles 6a and 6b with different water surface heights inside the box-type header 2.
is a partially cutaway view showing the configuration, and FIG. 2(b) is an explanatory cross-sectional view. In FIG. 2(b), the water surface 9 is the vibrator nozzle 6.
Since it is located above the top of the nozzle 6a, cooling water is supplied from the nozzle 6a in the form of a laminar flow. When the amount of water supplied from the water supply pipe 1 increases, the water level 9 rises, and when it becomes above the top of the nozzle 6b, the cooling water also flows down from the nozzle 6b as a laminar flow. Conversely, when the amount of water supplied from the water supply pipe 1 decreases, the water level in the ladder 2 gradually decreases, first the laminar flow stops from the nozzle 6b, and as the water level 9 further decreases, the water level in the ladder 2 gradually decreases. The laminar flow also stops from the nozzle 6a.

In this way, since multiple rows of nozzles 6a and 6b are provided that automatically turn on and off water injection depending on the level of the cooling water level in the header, the degree of freedom in cooling is greatly improved.

Fig. 3 shows a round header 2 in which nozzles 6a and 6b are arranged at different radial positions, Fig. 3(a) is a partial external view, and Fig. 3(b) is a cross section taken along line F-F. It is a diagram. In FIG. 3(b), since the water surface 9 is above the mounting position of the nozzle 6a, a laminar flow is formed and water is injected only from the nozzle 6a. When the amount of water supplied from the water supply pipe 1 increases, the internal water level 9 of the header 2 rises, and when it becomes higher than the mounting position of the nozzle 6b, a good laminar 70- is formed and water is injected from the nozzle 6b as well. Conversely, when the amount of water supply decreases, the water level 9 inside the header 2 decreases accordingly, and the laminar flow from the nozzle 6b stops, and when the water level 9 further decreases, the laminar flow from the nozzle 6b finally stops as well. . That is, as in the case of FIG. 2, water injection from the nozzle is automatically turned on and off depending on the height of the cooling water level in the header.

(Effects of the Invention) As described above, the cooling device of the present invention expands the controllable water volume setting range compared to conventional cooling devices, making it possible to perform uniform cooling at any speed and speed, thereby improving operational efficiency. In addition to increasing the degree of freedom, the water injection area in the width direction can be set arbitrarily, so the water injection area can be set and cooled even in the width direction temperature distribution of the hot rolled steel sheet to be cooled, allowing uniform cooling in the width direction. achieved. As a result, it is possible to manufacture hot rolled steel sheets with extremely little variation in quality. In addition, equipment costs are low because the structure is not complicated.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention, Fig. 1 (a) is a perspective explanatory view showing the overall configuration, and Fig. 1 (b-1) (b-2) are side sectional views showing the cooling water inside the cooling device. FIG. 1(C) is a sectional view showing an example in which the slit plate is arranged at an angle. FIG. 1(d-1) (d-2) is a partial plan view of FIG. 1(a). Figure 2 shows how the water injection area changes with the V-shaped gutter and the inverted V-shaped gutter. FIGS. 2 and 3 are explanatory diagrams showing other embodiments of the present invention, and showing the configuration of a header and a nozzle section. Figure 4,
FIG. 5 shows the configuration of a conventional cooling device, FIG. 4 shows a vibrating laminar type, and FIG. 5 shows a slit laminar type. FIG. 6 is an explanatory diagram showing the conditions for stably obtaining a laminar water flow in a conventional device. 1... Water supply pipe, 2... Header, 3... Nozzle,
4... Hot strip, 5... Weir, 6... Pipe laminar, 7... Slit laminar, 8... Conveyance roller, 9... Water surface, 10... Multiple slits, 11
・-V-shaped drain gutter, 12... Inverted V-shaped drain gutter, 1
3... Operating rod, I4... Drain gutter, I5... Slit plate, + 6-... Passage, l 7-... Cooling water, ) 8.
... Nozzle discharge port, 19... Passage width, 20... Height interval, 21... Slit plate angle, 22... Length in the plate width direction of the slit laminar, 23... Surplus water.

Claims (2)

[Claims] (1) In a laminar flow type cooling device, a hot rolled product characterized in that a cooling water header is provided with multiple rows of nozzles at different heights that automatically turn on and off water injection according to changes in the water level in the header. Steel plate cooling device. (2) In a laminar flow type cooling device, multiple rows of nozzles are arranged in the cooling water header at different heights to automatically turn water injection on and off according to changes in the water level in the header.
Between the laminar flow nozzle and the hot rolled steel plate, there is a V-shaped/inverted V shape.
The character-shaped drainage troughs are stacked one on top of the other, and each is connected to an operating rod so that it can move forward and backward independently in the direction of travel of the hot rolled steel plate, and
1. A cooling device for a hot-rolled steel sheet, characterized in that a drainage gutter having a length greater than the width of the hot-rolled steel sheet is disposed in engagement with a lower portion of the drain gutter.