JPS583451B2 - Cooling method for high-temperature plate-shaped objects - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling method for uniformly and rapidly cooling a high-temperature plate-like object using a liquid (mainly water) from both sides of the plate-like object.

The above-mentioned high-temperature plate-like object is, for example, a hot-rolled steel plate that is still hot after coming out of a hot rolling mill, or a steel plate that has been heated at around room temperature to an AC1 transformation point or an AC3 transformation point or higher.

Furthermore, the above-mentioned accelerated cooling is defined as cooling a high-temperature plate to a predetermined temperature in a short period of time in order to save time and cooling space, and accelerated cooling to improve strength or toughness or to refine other structures. It includes either one or both cases of improving the quality of the material.

A method of cooling a high-temperature plate-like object from both its upper and lower surfaces has been conventionally used. For example, as shown in FIGS. A large number of upper headers 2 are installed in the direction perpendicular to the direction (indicated by arrows) 7, and the lower part width direction of the steel plate 1, that is,
A cooling device in which a number of lower headers 3 are installed in a direction perpendicular to the line direction, each with a water supply valve 4 interposed therebetween, is in practical use.

However, in recent years, the width of the board is more than 1500mm and the thickness is 6mm.
Alternatively, steel plates of 9 mm or more are being cooled at a considerably high cooling rate, and in this case, conventional cooling devices such as those shown in FIGS. 1 and 2 are insufficient.
It is not possible to cool the steel material uniformly.

The reason for this is that when cooling with a nozzle at the bottom of the steel plate,
The cooling water that hits the back side of the steel plate falls down due to gravity, but when cooling with a nozzle on the top of the steel plate, the cooling water that hits the surface of the steel plate flows over the top of the steel plate and flows down from the left and right end faces of the steel plate.

Therefore, it is considered that the upper surface of the steel plate is not only cooled by the collision of the cooling water but also cooled by the cooling water flowing over the upper surface of the steel plate.

As the amount of cooling water flowing on the upper surface of the plate increases and the width of the plate becomes wider, the cooling ability due to the flow becomes impossible to ignore.

The flow is close to zero at the center of the plate width, becomes faster as it approaches the edge of the plate, and the cooling capacity increases as it approaches the edge of the plate.

Furthermore, regarding the flow in the longitudinal direction of the plate, it is the same up to a certain length from the center in the longitudinal direction of the plate, but at the front and rear ends of the plate, the cooling water flows down, so the cooling capacity changes as well. .

The state of these changes in cooling capacity is shown in FIG.

In the conventional cooling system shown in Figs. 1 and 2, the amount of cooling water per unit area of the steel plate is applied uniformly in the width direction and longitudinal direction from a fixed header that spans the width direction of the steel plate. Such problems arise.

Therefore, in order to uniformly cool the plate surface, it is necessary to distribute the cooling power caused by the collision of the cooling water on the top surface of the plate so as to correct the distribution of the cooling power due to the flow.

The second problem with the prior art is that the point of impact of the cooling water supplied from the header through the nozzle on the steel plate is specified in the width direction of the plate.

In other words, regarding cooling of the upper surface of the steel plate, cooling water collides with the upper surface of the plate directly under the nozzle of the upper header provided in the width direction of the plate, but the cooling water collides with the upper surface of the plate other than directly below the nozzle, that is, the gap between the nozzles. Cooling water will not collide with the upper surface of the plate where it is located.

On the other hand, problems similar to those described above occur regarding cooling of the lower surface of the steel plate, but in addition, since cooling of the lower surface of the steel plate is performed by a header installed between the rollers that support or convey the steel plate, stiff rollers The lower surface of the steel plate in the vicinity of the contact area will not be cooled.

To prevent this, the steel plate may be cooled while reciprocating in the longitudinal direction of the plate, but the above-mentioned problem still occurs.

As a way to solve the problem of the cooling water collision point being identified in the board width direction, it is conceivable to provide another header in the gap between the headers. Although the gap between cooling water collisions becomes denser and the above problem is alleviated to some extent, uniform cooling in the width direction of the plate is not achieved, and the steel plate obtained by such cooling does not cool in the direction parallel to the width direction. A linear hardened portion is observed, which is not preferable.

Note that cooling is also performed on the runout table in a hot strip mill using the header arrangement shown in Figures 1 and 2 above, but this is because the target plate thickness is thin.
The above problems do not occur because the temperature of the entire plate tends to be uniform during the slow cooling process after cooling and winding, or because the threading speed on the runout table is extremely high. .

This invention has been made to solve the above problems, and includes a cooling system that consists of an upper header group and a lower header group arranged perpendicular to the direction of the reciprocating movement while reciprocating a high-temperature plate-like object. In the method of cooling the high-temperature plate-like object in a zone, the amount of cooling liquid supplied from the widthwise end and the longitudinal end of the upper header group is constricted to the center of the cooling zone, and the amount of the cooling liquid supplied from the upper header group is It is characterized in that the group is caused to reciprocate so as to have at least a widthwise component.

In the present invention, it goes without saying that the cooling zone does not necessarily refer to the entire area where the upper header and lower header are installed, but may include any part of the above area depending on the width and length of the steel plate to be cooled. It is also possible to use parts.

In addition, restricting the amount of cooling water supplied from the width direction and longitudinal direction ends of the group of upper headers in the cooling zone to the center of the cooling zone means that the cooling water is This means that the amount of cooling water supplied to the end portions is small, and naturally includes cases where the amount of cooling water supplied to the board width and end portions in the longitudinal direction of the board is O.

This invention will be explained by way of examples and with drawings.

FIG. 4 is a schematic plan view of an embodiment of the invention.

As shown in the figure, the cooling device of this embodiment is
That is, two groups of upper headers arranged in a direction perpendicular to the direction of movement of the steel plate 1 are configured to reciprocate a certain distance in the width direction of the plate.

That is, one side end of the 2 groups of upper tubes to which cooling water is supplied from the main cooling water pipe 5 is connected to the cooling water supply pipe 7 via the water supply valve 4, and the cooling water supply pipe 7 is connected to the cooling water supply pipe 7 through the water supply valve 4. The pipe 7 is connected to the cooling water main pipe 5 via a flexible hose 6.

The other side ends of the two groups of upper headers are each fixed to a beam member 8 that is supported movably in the width direction.

A roller 9 is rotatably attached to the cooling water supply pipe 7, and an eccentric cam 10 which is rotatable by a drive device (not shown) is brought into contact with the roller 9.

Therefore, when the eccentric cam 10 is rotated, the two groups of upper headers reciprocate a certain distance in the width direction of the plate.

In order to cool the steel plate 1 with the two groups of upper headers having the above structure, the second group of upper headers is reciprocated as described above while the steel plate 1 is moved reciprocally with respect to the line, and the amount of cooling water supplied to the central part of the plate is adjusted. The amount of cooling water supplied to the four ends, that is, the width of the board and the ends in the longitudinal direction of the board, should be increased.

(See Figures 5 and 6) In this way, in order to reduce the amount of cooling water supplied to the edge of the plate in the width direction, it is necessary to It is sufficient to reduce the nozzle diameter at the end or close the nozzle at the end.On the other hand, to reduce the amount of cooling water supplied to the end of the board in the longitudinal direction of the board, use the water supply valve of the header corresponding to the end. 4 should be narrowed down or closed more than the center one.

By cooling the steel plate in this manner, there will be no areas in the width direction where the cooling water does not collide, and the four ends of the plate will not be overcooled.

In the above embodiment, the upper header 2 is moved back and forth in the width direction of the plate, but this movement is not particularly limited as long as it has a component in the width direction of the plate, and for example, circular movement or the like may be performed.

By the method of this invention, 2 5 m × 3 m 2
0. While reciprocating a steel plate of O x 19 mm by about 1 m at a feed rate of 1 5 m /min, it was cooled under conditions of a distance between upper headers of 225 mm and a distance between nozzles of 225 mm, and cooling was stopped when the predetermined temperature was reached. .

The temperature distribution of the steel plate at this time is shown in FIGS. 7 and 8.

As is clear from the figure, the temperature of the steel plate is uniform over the entire surface of the plate.

At this time, the cooling water supply state in the board width direction is reduced to 1/3 of the range of 300 mm at the board edge to 1/3 of the center area, and the cooling water supply state in the board longitudinal direction is reduced to 2 m at the front end and rear end of the board. This is a case where the range is reduced to 1/3 of the central area.

(Refer to FIGS. 5 and 6) As explained above, according to the present invention, by appropriately reducing the amount of cooling water to the ends in the width direction and longitudinal direction of the board, supercooling of the ends of the board can be prevented. Not only is this eliminated, but by reciprocating the upper header so that it has a component in the plate width direction, the cooling water also collides with the corresponding plate part between the nozzle intervals, and as a result,
An extremely useful effect is brought about in that cooling in the width direction of the plate can be performed with a higher degree of uniformity than in conventional cooling methods.

[Brief explanation of the drawing]

1 and 2 are a schematic plan view and a sectional view of a conventional cooling method, FIG. 3 is a diagram showing a supercooled state of the plate end, and FIG.
The figure is a schematic plan view of an embodiment of the present invention, FIG. 5 is a diagram showing the plate length and the flow rate distribution of cooling water from the upper header in the same method, and FIG. 6 is a diagram showing the plate width and upper header in the same method. FIG. 7 is a diagram showing the relationship between the plate length and humidity, and FIG. 8 is a diagram showing the relationship between the plate width and temperature. In the drawings, 1... steel plate, 2... upper header, 3
... Lower header, 4 ... Water supply valve, 5 ... Cooling water main, 6 ... Flexible hose, 7 ... Cooling water supply pipe, 8 ... Beam material, 9 ... Roller , 10... Eccentric cam.

Claims (1)

[Claims] 1. A method for cooling a high-temperature plate-like object in a cooling zone consisting of an upper header group and a lower header group arranged perpendicular to the direction of the reciprocating movement while reciprocating the high-temperature plate-like object. , The amount of cooling liquid supplied from the width direction end portion and the longitudinal direction end portion of the upper header group is narrowed to the center of the cooling zone, and the upper header group is reciprocated so as to have at least a width direction component. A method for cooling a high-temperature plate-like object, characterized by moving it.