JP2528774B2 - Cooling device for hot rolled steel sheet - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a cooling device which is arranged above a hot-rolled steel sheet and jets cooling water from above the hot-rolled steel sheet.

[0002]

2. Description of the Related Art The functions required for this type of cooling device are:
The water quantity distribution in the width direction of the steel sheet (cooling water ejected from each nozzle) is uniform, and water passing from the header and stopping are switched in a short time. If this function is not satisfied, the temperature of the steel sheet when winding the hot-rolled steel sheet becomes non-uniform in the longitudinal direction and the width direction, and it is not possible to manufacture a hot-rolled steel sheet having uniform mechanical properties.

Considering the cooling control of the hot-rolled steel plate among the necessary functions described above, conventionally, as shown in FIG. 10, four to five headers 1 are replaced by one water supply pipe 2. Although water was being supplied, in order to perform precise control, it is necessary to supply water to one or two headers 1 with one water supply pipe 2 as shown in FIG. However, with such a structure shown in FIG. 11, it is impossible to supply water from both sides as shown in FIG. 10 of the related art, and water is supplied from one side inevitably to make the water amount in the header width direction uniform. It will be an even more difficult situation.

Therefore, various headers have been conventionally manufactured as means for making the water amount in the header width direction uniform. For example, the one shown in FIG. 12 is a double-sided water supply type header structure which is actually used at present.
The idea of this header is that in the header main pipe 1a, cooling water is supplied from the water supply pipe 2 in the direction perpendicular to the header 1 in order to reduce the speed pressure of the cooling water discharged from the water supply pipe 2 in the longitudinal direction of the header main pipe 1a. The water supply pipe 2 is provided with an opening 2a so as to be discharged.

Further, the one shown in FIG. 13 has a similar one-sided water supply type header structure.
With the double pipe structure inside, the cooling water is supplied from both sides of the header 1 toward the central part to obtain the same effect as in FIG.

Next, from the viewpoint of shortening the switching time at the time of water passage and stop, the variation of the switching time at the time of water passage and stop causes uneven cooling temperature in the longitudinal direction of the hot-rolled steel sheet. Water flow to minimize variations
Efforts are being made to minimize the time to switch outages.
The operating time of the automatic switching valve is greatly affected by the length of the switching time, but there is an upper limit of the characteristic of the valve in reducing the operating time. Further, even if the valve operating time is the shortest, the switching time (particularly the switching time from water passage to stop) is not shortened due to the characteristics of the header.

The influence of the header structure on the switching time will be described with reference to FIG. 14. First, when the header and nozzle shown in FIG. The siphon effect works in the nozzle, and the cooling water in the nozzle and in the header is discharged from the nozzle as shown in FIG. During this time, it takes 3 to 4 seconds.

Therefore, one of the present inventors was
In No. 139913, only the nozzles at both ends of the header have a low rising height and a lower end jetting position, and due to the siphon effect, cooling water is discharged from both end nozzles that do not hit the hot rolled steel sheet, I proposed to stop the discharge of the cooling water of the plant early.

[0008]

However, as shown in FIG.
13 and the header structure shown in FIG. 13 are not sufficient to obtain a uniform water amount in the width direction.
Although the one disclosed in Japanese Patent No. 39913 can obtain a considerable effect as compared with the conventional header, it is still not sufficient.

The present invention has been made in view of the above-mentioned problems of the conventional header, and the water amount distribution in the width direction of the steel sheet is uniform, and the water flow from the header and the stop can be switched in a short time. An object of the present invention is to provide a cooling device for a hot-rolled steel sheet.

[0010]

In order to achieve the above object, a cooling device for a hot-rolled steel sheet according to the present invention has one end connected to an upper portion of a header arranged above the hot-rolled steel sheet and the other end. Is a cooling device in which a large number of inverted U-shaped nozzles are installed side by side in the width direction of the hot-rolled steel sheet so that the header is a double pipe structure including inner and outer pipes. However, among these, a large number of water supply holes are opened along the longitudinal direction of both sides of the inner pipe, and a straight pipe having a length equal to or larger than the hole diameter is attached to these water supply holes. The diameter of the water supply hole is gradually reduced from the water supply side toward the rear end.

In the cooling device for hot rolled steel sheet according to the present invention, a vertical air vent pipe having a length equal to or greater than a water column corresponding to the internal pressure of the header during water passage is attached to the upper part of the header of the cooling device having the above-mentioned structure. It has a different structure.

[0012]

In the cooling device for a hot rolled steel sheet according to the present invention, the cooling water supplied from the inner pipe collides with the inner walls on both sides of the outer pipe from the water supply hole through the straight pipe, and then the water distribution is uniform over the longitudinal direction. Then, it becomes a laminar flow flow from the nozzle and flows out. At this time, the uniformity of the water amount distribution is further improved by making the diameter of the water supply hole smaller from the water supply side toward the rear end.

Further, in the case where the vertical air vent pipe is attached to the upper part of the header, when the water is passed or stopped, the air intrudes substantially uniformly in the longitudinal direction of the header. It can be stopped in a short time.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in FIGS. FIG. 1 is a drawing showing a first embodiment of the present invention, (a) is a schematic front view, (b) is a sectional view taken along the line bb of (a), and FIG. 2 shows a second embodiment of the present invention. The same view as FIG. 1, FIG. 3 is a cross-sectional view showing the structure of the inner pipe constituting the header, FIG. 4 is an explanatory view of the water supply hole formed in the inner pipe, and FIG. 5 is the effect of the straight pipe attached to the inner pipe. In the drawings to be described, (a) is a velocity vector diagram at the nozzle inlet, and (b) is a diagram showing the pressure at the nozzle inlet.

As shown in FIGS. 1 and 2, the cooling device for hot-rolled steel sheet according to the present invention comprises a header 1 and an inner pipe 3 and an outer pipe 4.
A plurality of inverted U-shaped nozzles 5 are arranged side by side in the longitudinal direction of the header 1 in the outer tube 4 of these, like the conventional cooling device. On the other hand, the inner pipe 3 is provided with a large number of water supply holes 3a in the longitudinal direction of both sides thereof, and in these water supply holes 3a, as shown in FIG. 3, a straight pipe 6 having a length L equal to or larger than the hole diameter is provided. It is attached.

That is, the water supply hole 3a is for making the water amount distribution in the longitudinal direction of the header 1 uniform by the synergistic effect with the straight pipe 6, and the hole diameter of the water supply hole 3a is determined by the cooling water amount. However, the length of the straight pipe 6 depends on the water supply hole 3a.
If it is less than the hole diameter, the amount of water on the side opposite to the water supply side becomes larger than that on the water supply side, and it becomes impossible to obtain a uniform water amount distribution in the longitudinal direction of the header 1.

That is, in the present invention, by attaching the straight pipe 6 to the water supply hole 3a opened in the inner pipe 3, the velocity vector at the inlet of each nozzle 5 is shown by a white arrow as shown in FIG. 5 (a). As shown in the drawing, the nozzles 5 are directed toward the respective nozzles 5 side, the collision with the end face wall of the outer tube 4 is eliminated, and the inlet pressure of the nozzles 5 is substantially uniform over the longitudinal direction of the header 1 as shown in FIG. It becomes uniform, and as a result, the distribution of water amount becomes uniform.

Incidentally, Japanese Unexamined Patent Publication No. 50-59810 discloses a fluid ejecting device having a double pipe structure which is very similar to the embodiment of the present invention described above. In the dispersion pipe, the length of the straight pipe 6 in this embodiment is equal to 0 (zero). Therefore, when the length of the straight pipe 6 is equal to 0 as described above, the velocity vector of the cooling water flowing out from the hole formed in the inner pipe is as shown in FIG.
As it moves toward the end wall of the outer tube, the velocity vector at each nozzle inlet becomes horizontal as shown by the white arrow, and the cooling water collides with the end wall, so that the nozzle inlet pressure is As shown in b), the pressure on the end face wall side of the header becomes larger than the pressure on the water supply side, and as a result, the water amount distribution of the water ejected from each nozzle is not uniform.

In addition, when the apparatus described in Japanese Patent Laid-Open No. 50598/1975 is applied to an actual machine, it is necessary to install a plurality of branch pipes from the introduction pipe to the dispersion pipe in the entire width direction.
If this branch pipe is provided above, there is a drawback that the responsiveness of cooling water ON-OFF is deteriorated by the volume of the header and the branch pipe. Also, when installing this branch pipe in the lateral direction,
There is a problem that the headers cannot be installed densely due to the restriction of the installation space between the headers, and as a result, the overall cooling capacity cannot be increased.

Further, in the present embodiment, the diameter of the water supply hole 3a formed in the inner pipe 3 (inner diameter of the straight pipe 6) is reduced from the water supply side toward the rear end, as shown in FIG. The water distribution in the longitudinal direction of the header 1 is made more uniform.
In addition, it is ideal that the diameter of the water supply hole 3a (the inner diameter of the straight pipe 6) is gradually reduced from the water supply side toward the rear end, but in the experiments by the present inventors, the third and subsequent holes from the water supply side were used. Even with the same diameter, a sufficiently uniform water amount distribution was obtained (see FIG. 7).

In FIG. 2, reference numeral 7 denotes vertical air bleeding pipes attached to the upper portion of the outer pipe 4, for example, having a length equal to or greater than the water column corresponding to the internal pressure of the header during cooling water passage. Therefore, in the embodiment shown in FIG. 2, when the water supply valve is closed, air intrudes into the header 1 substantially uniformly in the longitudinal direction of the header 1 and the drainage of each nozzle 5 is performed simultaneously and for a short time. Can be stopped. In addition,
Reference numeral 8 in FIGS. 1 and 2 denotes a perforated plate.

Next, the results of experiments conducted to confirm the effects of the present invention will be described. FIG. 7 is an application of the embodiment of the present invention shown in FIG. 2, and FIG.
9 is the one to which the device shown in FIG. 12 is applied, and the horizontal axis is the nozzle number and the vertical axis is the value obtained by dividing the flow rate by the average flow rate.

As is apparent from FIGS. 7 to 9, when the cooling device of the present invention is used, the fluctuation amount of the water amount distribution in the longitudinal direction of the header is reduced to 1 / 6.5 as compared with the conventional device. I was able to. Moreover, when the time from the time when the water supply valve was closed to the time when the drainage from all the nozzles was stopped was compared from the header water passing state using the apparatus of FIGS. It took 5 seconds, but Fig. 7
In the example apparatus of the present invention, the time was 2.1 seconds.

As described above, when the apparatus of the embodiment of the present invention is used, it is possible to shorten the time until the drainage is stopped from all the nozzles after the water distribution in the header longitudinal direction is made uniform and the water supply valve is closed. It turned out that this can be achieved.

[0025]

As described above, when the device of the present invention is used, the water amount distribution in the width direction of the steel sheet is uniform, and moreover, water flow from the header and stop can be switched in a short time.
The distribution of water content in the longitudinal and width directions of the hot-rolled steel sheet becomes uniform,
It is possible to manufacture a hot-rolled steel sheet having uniform mechanical properties.

[Brief description of drawings]

1A and 1B are drawings showing a first embodiment of the present invention, in which FIG. 1A is a schematic front view, and FIG. 1B is a sectional view taken along line bb of FIG.

FIG. 2 is a view similar to FIG. 1 showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a structure of an inner pipe forming a header.

FIG. 4 is an explanatory view of a water supply hole opened in the inner pipe.

5A and 5B are diagrams for explaining the effect of a straight pipe attached to an inner pipe, in which FIG. 5A is a velocity vector diagram at the nozzle inlet, and FIG. 5B is a diagram showing pressure at the nozzle inlet.

FIG. 6 is a drawing similar to FIG. 5 in the case of the device described in Japanese Patent Application Laid-Open No. 50-59810.

7 is a drawing showing the experimental results when the embodiment of the present invention shown in FIG. 2 is applied, in which the horizontal axis is the nozzle number and the vertical axis is the value obtained by dividing the flow rate by the average flow rate.

FIG. 8 is a drawing showing the experimental results when the apparatus described in Japanese Patent Application Laid-Open No. 50-59810 is applied, in which the horizontal axis is the nozzle number and the vertical axis is the value obtained by dividing the flow rate by the average flow rate.

9 is a drawing showing the experimental results when the apparatus shown in FIG. 12 is applied, in which the horizontal axis is the nozzle number and the vertical axis is the value obtained by dividing the flow rate by the average flow rate.

FIG. 10 is an explanatory diagram of a header water supply pipe of a conventional device.

FIG. 11 is an explanatory view of a header water supply pipe of the device of the present invention.

FIG. 12 is a view showing a structure of a conventional header for double-sided water supply.

FIG. 13 is a view showing a structure of a header in the case of conventional one-sided water supply.

FIG. 14 is a diagram showing an influence of a header structure on a switching time.

[Explanation of symbols]

 1 Header 3 Inner pipe 3a Water supply hole 4 Outer pipe 5 Nozzle 6 Straight pipe 7 Vertical air vent pipe

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Tsutomu Kitamura 1850 Minato, Wakayama, Wakayama Sumitomo Metal Industries, Ltd. Wakayama Works (72) Inhito Miyamoto, 1850 Minato, Wakayama, Wakayama Sumikin Management Co., Ltd. (56) References Japanese Unexamined Patent Publication No. 56-91922 (JP, A) Actually opened 59-138467 (JP, U) Actually opened 56-102657 (JP, U)

Claims (3)

(57) [Claims] 1. An inverted U-shaped nozzle, one end of which is connected to an upper portion of a header disposed above a hot-rolled steel sheet, and the other end of which is mounted so as to hang down to a position adjacent to a side surface of the header, In a cooling device in which a large number of hot-rolled steel sheets are arranged side by side in the width direction, the header is constituted by a double pipe composed of an inner pipe and an outer pipe, and a large number of water supply holes are formed along both longitudinal directions of the inner pipe. A cooling device for a hot-rolled steel sheet, wherein a straight pipe having a length equal to or larger than a hole diameter is attached to the. 2. The cooling device for a hot-rolled steel sheet according to claim 1, wherein the diameter of the water supply hole is set to become smaller in order from the water supply side toward the rear end. 3. A vertical air vent pipe having a length equal to or greater than a water column corresponding to the internal pressure of the header during water passage is attached to the upper portion of the header.
Cooling device for the hot-rolled steel sheet described.