JPH05277683A - Cast slab cooling method for continuous casting - Google Patents

Abstract

PURPOSE:To produce a cast slab which can prevent a bulging of cast slab at high speed casting and has a good surface quality. CONSTITUTION:As a gap of adjoining short side rolls 3,3 is made narrowest possible and a cooling water flow b, which is sprayed into the outer roll gap G1 from the flat shaped cooling water spraying nozzle 10 arranged in the outer roll gap G1, is throttled by the roll gap to make diffusing spray at the cast slab side roll gap G2, the cast slab 1 is efficiently cooled by synergistic effect consisting of a cooling water spraying on a large area of the cast slab 1 and an indirect cooling to the cast slab 1 through the short side roll 3,3 cooled by cooling water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a method for cooling a slab in a continuous casting method in a roller apron zone immediately below a mold.

[0002]

2. Description of the Related Art In a continuous casting method, a slab that passes through a roller apron strip immediately below a mold has a thin solidified shell and has a high temperature. Therefore, bulging occurs between the slab support rolls forming the roller apron strip. It is likely to occur, which may lead to a breakout accident.

Therefore, conventionally, in the roller apron band, the purpose of accelerating the solidification of the slab and preventing bulging is
Outside the space between each slab support rolls, a sprinkler for cooling the slab is installed.While the continuous casting equipment is operating, cooling water is always sprayed from the sprinkler to the slab surface. The slab is designed to be cooled.

Here, a cooling device for a cast piece in the continuous casting method which has been conventionally used will be specifically described.
That is, FIG. 6 and FIG. 7 are a schematic view of a slab cooling device used in a conventional slab cooling method as viewed from the top and a schematic view of the same device as viewed from the side.
Reference numeral 1 denotes a slab that has passed through a mold (not shown). A plurality of slab support rolls 4 forming a roller apron band are arranged on the peripheral surface of the slab 1 in the drawing direction (direction of arrow a in FIG. 7). It is set up.

Specifically, the slab support roll 4 includes a plurality of long side rolls 2 on the long side of the slab and a plurality of long side rolls 2 on the short side of the slab, which are perpendicular to the drawing direction of the slab 1. The short side rolls 3 are rotatably arranged at predetermined intervals.

Reference numeral 5 denotes a plurality of sprinklers connected to a sprinkler (not shown), which is located between the adjacent long side rolls 2 and 2 and between the adjacent short side rolls 3 and 3 at the rear outside. Each of them is arranged so that the cooling water sprayed from the tip end opening of the water sprinkling pipe 5 hits the surface of the cast slab 1 and can be cooled.

In the drawings, reference numerals 6 and 7 denote bearings for the long side roll 2 and the short side roll 3, respectively.

Next, a conventional method for cooling a slab using the slab cooling device having the above structure will be described. That is, the cast piece 1 coming out of the mold (not shown) is pulled out at a predetermined speed in the direction shown by the arrow a in FIG. 7 by the cast piece drawing device. At this time, the long side rolls forming the cast piece support roll 4 are drawn. The surface of the cast slab 1 is cooled by cooling water 8 sprayed from a sprinkling pipe 5 connected to a sprinkling device disposed on the outer rear side between the rolls 2 and 2 and the short side rolls 3 and 3.

[0009]

However, as is clear from FIG. 7, for example, in the case of the short-side roll 3, the casting is performed in a direction perpendicular to the drawing direction of the slab 1 shown by the arrow a. Since the short side rolls 3 are arranged at predetermined intervals on one short side, the short side vertical surface of the slab 1 is part of the height H of the short side roll 3 when viewed from the direction of the water spray pipe 5. Therefore, the cooling water is directly sprayed only to the exposed portion which is visible from the sprinkling pipe 5 side.

Therefore, the cooling water does not directly impinge on the slab surface partially covered by the height H of the short side roll 3, and only the exposed portion of the slab 1 seen from the sprinkler pipe 5 side is locally exposed. Since the cooling is performed, the cooling efficiency was very poor in terms of the cooling efficiency of the entire cast piece 1.

Further, as the cast slab support roll 4 constituting the roller apron band, a roll having a diameter of about 150 mm is usually used, and the interval (roll interval) between the upper roll end and the lower roll end of a series of roll groups is Since the installation of the sprinkler is set to around 40 mm so that there is no support, in the conventional cooling method, the portion directly cooled between the pair of upper and lower rolls in the drawing direction of the slab 1 is about 1/5 or less. Therefore, the cooling performance of the slab becomes insufficient during high-speed casting, and there is a high risk of bulging of the slab.

The present invention has been made in order to solve the above-mentioned problems, and improves the cooling capacity by enlarging the area of the slab support roll which hits the slab of the cooling water between the rolls, thereby improving the high speed casting. An object of the present invention is to provide a method for cooling a slab in a continuous casting method capable of preventing bulging of the slab at the time.

[0013]

In order to achieve the above-mentioned object, in the present invention, in the method for cooling a slab in a roller apron zone in a continuous casting method, the interval between adjacent rolls is narrowed as much as possible, and The cooling water is sprayed over the entire width of the roll in the outer roll gap formed between the adjacent rolls, and after passing through the narrowest part of the roll gap between the adjacent rolls, the cooling water is applied to the slab surface and the slab side. It is intended to cool the slab surface by diffusing and spraying into the space formed by the roll gap.

[0014]

According to the above construction, the slab that passes through the roller apron strip through the mold is cooled to the entire roll width within the outer roll gap between the adjacent rolls of the slab support rolls that compose the roller apron strip. When water is sprayed, in the first stage, the cooling water outflow width spreads over the entire roll width to cool each roll peripheral surface forming the outer roll gap, and this cooling water then cools the rolls between the adjacent rolls. It passes through the narrowest part of the gap, is squeezed and accelerated, and reaches the opposite slab-side roll gap side. At this time, the cooling water diffuses and reaches the slab surface. Therefore, the cooling area of the slab can be increased, and at the same time, the adjacent rolls are also cooled, so that the indirect cooling effect by the roll on the slab is also combined, and the width direction and the drawing direction of the slab in the roller apron band immediately below the mold It is possible to achieve strong cooling, and to prevent bulging by promoting uniform solidification of the slab.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for cooling a slab in a continuous casting method according to the present invention will be described in detail below with reference to the drawings. Figure 1
FIG. 2 is a schematic view of a slab cooling device used in the practice of the present invention as seen from above, and FIG. 2 is a schematic view of the same device as seen from the same side. In these drawings, FIG.
The same or corresponding parts as those in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIGS. 1 and 2, reference numeral 9 denotes a cooling water supply pipe corresponding to a conventional water sprinkling pipe.
A flat nozzle 10 for jetting cooling water is detachably disposed at the tip of the.

As shown in detail in FIG. 3, the flat nozzle 10 narrows the gap between the adjacent short side rolls 3 and 3 as much as possible, and within the outer roll gap G1.
The nozzle hole is set so that the tip of the nozzle hole faces the roll gap.

Here, the narrower the roll gap between the short side rolls 3 and 3, the more efficiently the strong cooling can be carried out.
From the viewpoint of reducing the load on the water supply equipment, it is desirable to set the roll diameter to 2 mm or less, and the roll diameter is the narrowest part of the roll gap between adjacent rolls (roll center line connecting the centers of adjacent short side rolls). It is preferable that the diameter of the cooling water flowing out from the position is small because it can shorten the reaching distance to the surface of the slab and improve the cooling performance.

Further, it is also effective to incorporate a compressed air supply port in the flat nozzle 10 so as to promote diffusion and dispersion of cooling water on the surface of the slab.

When it is necessary to control the cooling ability by changing the cooling capacity in the width direction of the slab, a plurality of flat nozzles are installed in the width direction of the slab, and the water amount is controlled for each flat nozzle. To do so.

In the above embodiment, for the sake of convenience of explanation, the case where only the gap between the adjacent short side rolls 3 and 3 is made as narrow as possible has been illustrated. However, in addition to this, the long side rolls arranged on the long side of the cast slabs. The gaps on the 2 and 2 sides may be made as narrow as possible and the flat nozzles similar to those described above may be installed. Furthermore, both the short side rolls 3 and 3 and the long side rolls 2 and 2 may have the gap as small as possible. However, the flat nozzles 10 may be narrowed and the flat nozzles 10 may be arranged in the roll gaps.

Next, the operation of the cooling device having the above structure will be described with reference to FIG.
When the cooling water is jetted at a predetermined pressure from 0, the outflow width of the cooling water spreads over the entire width of the flat nozzle 10 as shown by the arrow c in FIG. 4, and the short side as shown by the arrow b in FIG. Rolls 3,
After passing through the gap No. 3, the flow path of the cooling water is narrowed by this roll gap and accelerated, and is jetted in a diffused state to the slab side roll gap G2 side and reaches the surface of the slab 1.

At this time, the surface of the cast slab 1 is not only directly cooled by the contact of cooling water, but in addition, the outer roll gap G1 and the cast slab side roll gap G2 provide the peripheral surfaces of the short side rolls 3 and 3. Is cooled by the contact of cooling water, so that the surface of the slab 1 is indirectly cooled by these short side rolls 3, 3.

Experiments carried out to confirm the effect of the method for cooling a slab according to the present invention will be described. 1 to 5 low carbon aluminum killed steel with 50 tons of heat
At a casting speed of m / min, as shown in FIGS. 1 and 2, among the long-side rolls and the short-side rolls forming the roller apron band disposed immediately below the mold, particularly, the gap between the adjacent short-side rolls is narrowed. (Roll gap is 1 mm), the tip portion of the flat nozzle described above is arranged in the outer roll gap, and the flat nozzle (per one) has a water injection amount of 50 to 100 liters / minute and a thickness. 105 mm, width 10
00 mm slabs were produced.

As a result of the production of the ingot under the above conditions, the bulging amount of the cooled ingot after casting was measured, and the bulging index calculated from this measurement result is as shown in FIG. As is clear from the measurement data shown in the figure, in the conventional cooling method of the slab (comparative example), the average casting speed was 3
At m / min or more, occurrence of bulging on the short side roll side was observed, and it is clear that the bulging amount also increased as the casting speed increased.

On the other hand, in the cooling method according to the present invention (the present invention), at a casting speed of 4 m / min or less, there is no bulging on the short-side roll side, and even at a casting speed of 5 m / min, it is slightly It can be reduced to a bulging amount of 1 mm or less, which is superior to the conventional example, and in particular, in the case of high speed casting, it is clear that the present invention is significantly superior to the comparative example. is there.

[0027]

As described above, according to the present invention, it is possible to prevent the bulging of the slab during high-speed casting, and to produce the slab with good surface quality.

[Brief description of drawings]

FIG. 1 is a schematic view of a slab cooling device applied to the practice of the present invention as seen from the top.

FIG. 2 is a schematic view of a slab cooling device applied to the implementation of the present invention as viewed from the side.

3 is a cross-sectional view showing an enlarged main part of FIG.

4 is a sectional view taken along line XX of FIG.

FIG. 5 is a diagram showing an experimental result by a method for cooling a cast piece according to the present invention and a method for cooling a cast piece according to a conventional method.

FIG. 6 is a schematic view of a slab cooling device used in a conventional slab cooling method as viewed from above.

FIG. 7 is a schematic side view of a slab cooling device used in a conventional slab cooling method.

[Explanation of symbols]

 1 slab 2 long side roll 3 short side roll 4 slab support roll 9 cooling water supply pipe 10 flat nozzle

Claims (1)

[Claims] 1. A method for cooling a slab in a roller apron band in a continuous casting method, in which a gap between adjacent rolls is narrowed and the entire roll width in an outer roll gap formed between the adjacent rolls is cooled. Water is sprayed, after passing through the narrowest part of the roll gap between the adjacent rolls, the cooling water is diffused and sprayed into the space formed by the slab surface and the slab side roll gap, thereby the slab surface A method for cooling a slab in a continuous casting method, characterized in that the slab is cooled.