JPH0224176B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting apparatus for steel sheets, and in particular, to a device that prevents waves generated on the surface of a pool formed between cooling rolls from affecting the steel sheet being cast. Concerning continuous casting equipment for steel plates.

Generally, a method as shown in FIG. 1 is known as a continuous casting method. That is, a molten metal 2 is supplied onto two cooling rolls 1, 1 which are arranged parallel to each other so as to be freely rotatable in the horizontal direction, and while the molten metal 2 is cooled and solidified, a plate-shaped metal is placed between the rolls 1, 1 downwardly. This is a method of continuously casting castings. In this method, as shown in the figure, side walls 3, which store the molten metal 2 facing each other along the axial direction of the roll 1, are used to set the cooling length on the cooling rolls 1 and to increase the static pressure of the molten metal.
3 are arranged. That is, the cooling length can be set by changing the distance between the side walls 3, 3, and the static pressure of the molten metal can be increased by raising the water level. The lower end of the side wall 3 is slightly spaced apart from the cooling roll 1 to reduce leakage of molten metal. The molten metal 2 is cooled and solidified by contacting the cooling roll 1, and a solidified layer 5 is formed on the surface of the cooling roll 1.

By the way, according to this method, as shown in the same figure, the solidified shell 7 formed at the lower end of the side wall 3 and growing is connected and fixed to the solidified layer 5 formed on the surface of the cooling roll 1, and streaks are formed on the surface of the cast steel plate 6. There is a problem of causing scratches or chips. That is, since high-temperature hot water is stored between the side walls 3 and 3, the temperature of the side wall 3 as a whole is high, but since its lower end is close to and facing the cooling roll 1, the temperature of the side wall 3 is high. 1, or by heat dissipation from the outer surface of the side wall 3, it tends to be cooled significantly compared to other parts. Therefore, a solidified shell 7 is gradually formed on the inner surface of the lower end of the side wall from the portion in contact with the cooling roll 1, and grows larger over time. The solidified shell 7 formed at the lower end reaches the boundary 4 with the cooling roll 1, and finally becomes bonded and fixed to the solidified layer 5 formed on the surface of the cooling roll 1. Solidified layer 5 formed by cooling roll 1
moves with the rotation of the roll 1, but since the solidified shell 7 formed on the side wall 3 is fixed, a large shearing force is applied to the bonded part, and the solidified layer 5 is repeatedly cut and bonded, and the surface of the cast plate is This can result in streaky scratches or chips.

Unlike the casting of slabs, which undergoes a rolling process later, such scratches or plate breaks occur when the rolls 1, 1
This problem must be solved because it is fatal in the case of casting steel plates, where the material that comes out from the gap is used as a product as it is.

Therefore, in order to remove the side wall 3 that causes the formation of the solidified shell 7 and store the molten metal only between the cooling rolls 1 and 1 as shown in FIG. End walls 8 on both end faces of
A method was devised in which a chisel was pressed.
This is an attempt to solve this problem on a priority basis, considering the seriousness of scratches and plate breakage caused by repeated cutting and joining of the solidified layer 5, rather than the effect on the steel plate due to a decrease in the static pressure of the molten metal.

However, as shown in FIG. 3, the steel plate 6 obtained by this method has a phenomenon in which a wavy pattern appears on the surface, which does not exist when the side wall 3 is used, and a cast slab. Slag entrainment 13 on the surface was observed. It was found that these hot water lines 9 often appeared during pouring, but hardly appeared after pouring was stopped. These hot water wrinkles and slag entrainment also significantly impair the quality of the steel sheet, and there has been a long-awaited desire to eliminate them.

As a result of intensive research, the inventors of the present invention have discovered that the cause of the hot water wrinkles is the waves that the hot water surface of the hot water pool makes at the edge of contact with one surface of the cooling roll. That is, the thickness of the coagulated layer 5 formed on the surface of the roll increases as the contact time with the surface of the roll increases, but the rate of increase is large at the beginning of contact and becomes relatively slow thereafter. Therefore, when molten metal is poured into the pool between rolls 1 and 1, the surface of the molten metal ripples,
Waves are formed at the edge of contact with one surface of the cooling roll,
As shown in Fig. 4, there is a time difference in which solidification occurs quickly where the waves are high and solidification is delayed where the waves are low, and this difference in solidified thickness alternates along the axial direction of the roll 1. This appears on the steel plate as it is, in the form of undulating water lines. It has also been found that these water wrinkles are exacerbated when coming out from between the cooling rolls 1 and 1.

Therefore, it is an object of the present invention to prevent the waves generated on the molten metal surface from spreading to the roll surface when pouring molten metal into the pool formed between the cooling rolls, and to prevent the waves caused by this from spreading to the steel plate surface. An object of the present invention is to provide a continuous casting apparatus for steel sheets that can effectively prevent the occurrence of hot water wrinkles.

According to the present invention, the above object is achieved as follows. In other words, there are cooling rolls that are rotatably arranged parallel to each other and spaced apart from each other to cast a steel plate while cooling molten steel, and a roll shaft that is immersed in a puddle that is to be formed between the cooling rolls and the end wall of the roll. Equipped with a spout consisting of a pair of partition plates installed over the entire length in the direction, it controls the range in which molten steel directly hits the molten metal surface when pouring hot water, and effectively prevents the waves generated from spreading to the rolls. It was designed to cut it off.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a continuous casting apparatus according to the present invention will be described below with reference to the accompanying drawings.

FIG. 5 is a schematic perspective view of a continuous casting apparatus showing one implementation of the present invention, which is basically the same as the conventional example.

As shown in the figure, two partition plates 11, 11 made of refractory material are placed in parallel in the center of a pool 10 formed between the cooling rolls 1, 1 with an appropriate interval.
Moreover, it is provided apart from the roll 1. These partition plates 11 extend along the entire length along the axial direction of the roll 1, and their lower edges are immersed in the pool 10, and their upper edges are supported by suitable means, such as a tundish (not shown). It forms a hot water inlet that receives the molten steel flow poured from the pipe. In the illustrated example, the surface of the partition plate 11 is flat, but at least the opposing surface may be provided with unevenness for wave dissipation.

Therefore, the molten steel flow 2 injected into the molten metal pool 10 from a dump station or the like forms waves on the molten metal surface when it directly hits the molten metal surface, but all of the molten steel flow 2 is injected into the partition plate 11,
11, so the waves formed hit the partition plate 1.
1 and the spread to the roll 1 side is cut off. In particular, when the facing surface of the partition plate 11 is provided with unevenness, the ripples between the partition plates 11 and 11 are also suppressed, so that the turbulence of the hot water surface outside the partition plate 11 is significantly reduced, and the surface of the roll 1 and the hot water surface are The contact edge is extremely quiet and even. As a result, roll 1
It is possible to reduce as much as possible the occurrence of hot water wrinkles on the steel plate surface caused by hot water waves that occur at the contact edge with the surface,
In addition, slag on the free surface of molten steel can be removed by the partition plate 11.
Since it does not come into contact with the roll 1, it is possible to prevent slag from getting caught.

In this way, according to this embodiment, the use of the side wall 3, which causes scratches on the surface of the steel plate and breakage of the plate, is eliminated, and the turbulence of the molten metal surface during pouring, which causes molten metal wrinkles, is effectively eliminated. Therefore, the equipment can be simplified and high-quality steel plates can be cast. In addition, the lack of molten steel static pressure due to the removal of side wall 3 is due to
This problem can be solved by increasing the diameter of the roll 1 to raise the water level in the water reservoir 10, or by adjusting the amount of pressure applied between the rolls 1, 1.

In summary, the present invention exhibits the following excellent effects.

(1) A simple structure consisting of a pouring port consisting of a pair of partition plates that extends along the entire length of the roll so that it is submerged in a pool of water, suppresses disturbances in the surface of the melt caused by pouring over the entire length of the roll. It is possible to prevent the wave from spreading to the roll surface, thereby effectively preventing the generation of hot water wrinkles on the surface of the steel sheet and the entrainment of slag caused by this.

(2) Since scratches and breakage on the surface of the steel plate are prevented, high-quality steel plates can be obtained.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view showing a conventional continuous casting device, Fig. 2 is a schematic perspective view showing another continuous casting device, and Fig. 3 is a plane and cross section of a steel plate obtained by the continuous casting device shown in Fig. 2. 4 is a solidification thickness characteristic diagram with respect to contact time, and FIG. 5 is a schematic perspective view of essential parts showing a preferred embodiment of the continuous casting apparatus according to the present invention. In the figure, 1 is a cooling roll, 2 is molten steel or a molten steel flow, 6 is a steel plate, 10 is a pool formed between the cooling rolls, and 11 is a partition plate forming a pouring port.

Claims (1)

[Claims] 1. Cooling rolls that are freely rotatable parallel to each other and spaced apart from each other for casting steel sheets while cooling molten steel; 1. A continuous casting apparatus for steel sheets, characterized in that it is equipped with a pouring spout consisting of a pair of partition plates provided over the entire length.