JPS6030555A - Continuous casting device for steel plate - Google Patents

Abstract

PURPOSE:To provide a titled device which prevents effectively the generation of a ripped surface on the surface of a steel plate by providing a pouring port so as to be submerged in the well to be formed between cooling rolls and the end walls at the end face of the rolls and regulating the range where a molten steel strikes directly against the melt surface in the stage of pouring the molten steel. CONSTITUTION:Two sheets of partition plates 11, 11 formed of refractories are provided in parallel apart at an adequate spacing from each other in the central part of the well 10 between cooling rolls 1, 1 and apart from the rolls 1. The plates 11 extend over the entire length of the rolls 1 along the axial direction thereof and the bottom end edges are dipped in the well 10 so as to be submerged therein thereby forming a pouring port to accept the molten steel flow 2 poured therein. The molten steel flow admitted onto the well 10 forms a wave on the melt surface when said flow strikes against the melt surface. However all the flow 2 falls between the plates 11 and 11 and therefore the formed wave is blocked by the plates 11, 11 and is prevented from propagating to the roll 1 side. As a result the rippled surface on the steel plate occurring in the ripples generated at the verge in contact with the roll 1 surface is decreased as far as possible.

Description

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

Generally, a method as shown in FIG. 1 is known as a continuous casting method. That is, the molten metal 2 is placed on two cooling rolls 1, 1 which are arranged parallel to each other so as to be freely rotatable in the horizontal direction.
This is a method in which a plate-shaped casting is continuously cast between the rolls 1 and 1 while supplying and cooling and solidifying the same. In this method, as shown in the figure, a cooling length is set on the cooling rollers 1, 1, and side walls 3, which store the molten metal 2 facing each other along the axial direction of the roll 1, are used for the purpose of increasing 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, and the static pressure of the molten metal can be increased by raising the water level. Cooling port to reduce molten metal leakage ~
Only 1 compared to 1! I'm letting it go for 11 hours. The molten metal 2 is cooled and solidified by contacting the cooling roll 1, and a solidified metal H5 is formed on the surface of the cooling roll 1.

By the way, according to this method, as shown in the figure, the solidified shell 7 formed on the lower fN portion of the side wall 3 and growing is connected and fixed to the solidified layer 5 formed on the cooling roll 1, and the surface of the cast steel plate 6 is fixed. There is a problem in that it causes streaks or chips. That is,
Side wall 3. High temperature hot water is stored between 3, so side wall 3
The temperature is high overall, but the lower end is cooled to 0-
Since it is located close to and facing the side wall 1, it tends to receive cold heat from the cooling roll 1 or to be cooled significantly compared to other parts by heat radiation from the outer surface of the side wall 3. 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 is finally bonded and fixed to the solidified layer 5 formed on the surface of the cooling roll 1. Although the solidified layer 5 formed by the cooling roll 1 moves as the roll 1 rotates, the solidified shell 7 formed on the side wall 3 is fixed, so a large shearing force is applied to the bonded part, and the solidified layer 5 5 repeats cutting and joining,
This results in streak-like scratches or chips on the surface of the cast plate.

Unlike the casting of slabs, which undergo a rolling process later, such scratches or breaks are fatal in the casting of steel plates, where the product comes directly from between the rolls 1 and 1. It is necessary to resolve the problem.

Therefore, the side wall 3 that causes the formation of the solidified shell 7 is removed,
As shown in Figure 2, in order to store the molten metal only between the cooling rolls 1 and 1 and prevent melt leakage from the ends of the rolls, only the end walls 8 were pressed against both ends of the rolls 1 and 1. A method was thought of.

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 wrinkles 9, ie, a wavy pattern appear on the surface, which did not exist when the side wall 3 was used. Ta. It was found that these wrinkles 9 often appeared during pouring and hardly appeared after pouring was stopped. These wrinkles 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 dry water wrinkles is the waves created by the surface of the hot water in the pool where it contacts the surface of the cooling roll. However, 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 the rolls 11, the surface of the molten metal ripples, forming waves at the point of contact with the surface of the cooling roll, but as shown in Figure 4, solidification occurs faster in areas where the waves are higher, and vice versa. There is a time lag in which solidification is delayed in areas where the waves are low, and this difference in solidified thickness appears alternately along the axial direction of the roll 1, and this appears on the steel plate as it is, that is, as wrinkles in a wavy pattern. be. It has also been found that the field wrinkles are exacerbated when emerging from between the cooling rolls 1.1.

Therefore, an object of the present invention is to prevent the waves generated in the molten metal pool formed between the cooling rolls from spreading to the roll surface when pouring molten metal into the molten metal pool formed between the cooling rolls. 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 provided parallel to each other and spaced apart from each other to cast steel sheets while cooling molten steel, and rolls that are immersed in a pool of water to be formed between these cooling rolls and the end walls of the rolls. The molten steel is equipped with a pouring spout to restrict the range in which the molten steel directly hits the molten metal surface when pouring the molten metal, and to effectively prevent the waves generated from spreading to the rolls.

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, not showing an example of the present invention, and is basically the same as a conventional example.

As shown in the figure (two partition plates 11.11 made of refractory material are placed in the center of the pool 10 formed between the cooling rolls 1.1).
are provided parallel to each other at appropriate intervals and spaced apart from the roll 1. These partition plates 11 are the roll 1
It extends over the entire length along the axial direction of the tank, has its lower edge submerged in the pool 10, and has its upper edge supported by appropriate means to receive the molten steel flow poured from a tundish (not shown) or the like. It forms the sexual entrance. Although the surface of the partition plate 11 is flat in the illustrated example, it is also possible to provide some unevenness on the opposing surface for wave dissipation.

Therefore, the molten steel flow 2 injected into the pool 10 from the dandytsu etc. forms waves on the scene when it directly hits the scene, but since all of the molten steel flow 2 falls between the partition plates 11 and 11, no waves are formed. The waves are blocked by the partition plate 11 and are prevented from spreading to the roll 1 side.

In particular, in the case where the facing surface of the partition plate 11 is provided with unevenness, ripples between the partition plates 11 and 11 are also suppressed, and the disturbance of the hot water surface flowing outside the partition plate 11 is significantly reduced. The contact between the surface and the scene is extremely quiet and uniform. As a result, it is possible to reduce as much as possible the occurrence of hot water wrinkles on the surface of the steel sheet, which are caused by undulations occurring at the edge of contact with the surface of the roll.

FIG. 6 shows a modification of the above embodiment, and the difference from FIG. 4 is that instead of two parallel partition plates 11, an immersion nozzle 12 with its tip submerged in a pool 1o is used as appropriate. Since the rollers 1 are arranged at intervals in the axial direction, as a result, the molten steel flow 2 is continuously poured into the molten metal sump 10, so there is no impact with the molten metal sump, making the situation easier when pouring. can remain calm and calm.

As described above, according to this embodiment, it is possible to eliminate the use of the side wall 3, which causes scratches on the surface of the steel plate and breakage of the plate, and to effectively eliminate the disturbance of the scene during pouring, which causes wrinkles. Therefore, the equipment can be simplified and high-quality steel plates can be cast. In addition, the lack of molten steel static pressure caused by removing the side wall 3 can be solved by increasing the diameter of the roll 1 to raise the water level in the pool 10, or by adjusting the amount of pressure applied between the rolls 1 and 1. Can be done.

In summary, according to the present invention, the following advantages are achieved.

(1) A pouring hole is installed to submerge the hot water into the pool (the simple structure of the pool suppresses the disturbance of the scene caused by pouring the hot water and prevents waves from spreading to the roll surface, thereby preventing waves from spreading to the roll surface. The occurrence of hot water wrinkles on the surface of the steel plate can be effectively prevented.

(21111 Since scratches and breakage on the plate surface are prevented, high-quality steel plates can be obtained.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view showing a conventional continuous 14-piece vehicle;
The figure is a schematic perspective view showing another continuous casting apparatus, FIG. 3 is a plane and cross-sectional view of a steel plate obtained by the continuous casting apparatus of FIG. 2, FIG. 4 is a solidification thickness characteristic diagram against contact time, and FIG. The figure is a schematic perspective view of essential parts showing a preferred embodiment of the continuous casting apparatus according to the present invention, and FIG. 6 is a schematic perspective view of essential parts showing another preferred embodiment. 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, 11.
12 is a partition plate and an immersion nozzle, which are examples of a pouring port. Patent applicant: Patent attorney representing Ishikawajima-Harima Heavy Industries Co., Ltd.
Kinutani Nobui Figure 1 Figure 2 Figure 3 Figure 4 m 敞＊nノIt (sec)

Claims (1)

[Claims] cooling rolls that are rotatably installed parallel to each other with appropriate ridges and that cast steel sheets while cooling molten steel; A continuous casting device for steel sheets, characterized by comprising a pouring spout.