JPS6021171A - Continuous casting device for broad and thin plate - Google Patents

Abstract

PURPOSE:To cast a thin plate product which has a uniform thickness and good quality by immersing a pouring nozzle of an inverted Tee shape into the molten metal in a dam vessel for reserving the molten metal in the upper part of a rotary casing mold and installing divergently the discharge ports of the nozzle toward both short side walls of the dam vessel. CONSTITUTION:A dam vessel 4 consisting of respectively a pair of long-side walls and short-side walls 3a, 3b is provided in the upper part of a casting roll 1b and a molten metal is properly supplied from a tundish 5 via a pouring nozzle 6 into the vessel 4 to cast a thin plate with a roll 7b. The nozzle 6 consists of a passage 10 in a vertical direction and passages 9a, 9b in a horizontal direction. The passages 9a, 9b are provided toward the direction of the short side walls 3a, 3b of the vessel 4 so as to have a gradually increasing sectional area as said passages are brought close to the discharge ports 7a, 7b thereof and the passages 9a, 9b are positioned on the narrow gap of the roll 7b. The fluctuation in the thickness, formation of a fin, the deterioration in the surface characteristic and internal quality, etc. occuring in the generation of the soldified shell in the side dam are thus prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for directly and continuously casting a wide thin plate from molten metal, particularly molten steel, using a synchronously rotating mold.

In continuous steel casting, proposals have been made to manufacture wide thin plates directly by casting instead of conventional thick slabs. For example, an invention that attempts to directly manufacture a thin plate from molten steel using a synchronously rotating mold consisting of continuous twin rolls or twin belts is disclosed in Japanese Patent Application Laid-Open No. 55-75862 and Japanese Patent Application Laid-open No. 5
It is described in 8-32548 and the like. In these systems, cooled casting rolls or casting bells 1- that rotate in opposite directions are arranged horizontally in parallel with a predetermined narrow gap, and the thin slab is continuously extracted downward through this narrow gap. In this way, wide thin plates can be continuously cast. There are various problems inherent in direct continuous casting of thin sheets using such rotary molds, but in particular, it is difficult to uniformly supply hot water of the same temperature to the mold surface in the narrow gap of the rotary mold, and the thin sheet slabs to be cast are A solidified shell of irregular shape is formed due to the flow and temperature changes of the hot water on both sides and the center, resulting in a thin sheet with uniform thickness, little lamination, good internal quality and edge shape, and little hot water hari. The basic problem is that the finished product is difficult to cast.

JP-A-57-956+3 and JP-A-58-3255
Publication No. 1 discloses, as prescriptions for dealing with such problems, a prescription in which an inert gas blowing means is provided in the side dam to stir hot water, and a prescription in which a heating means is attached to the side dam. However, in the former case, there is a risk that air bubbles will be trapped within the slab and bubble defects will occur inside the thin plate product, and in the latter case, the structure of the side dam will inevitably become complicated.

The present invention was made with the aim of solving this problem from a different perspective from the inert gas blowing and external heating. A rotary mold consisting of a pair of casting rolls or a casting belt, a pair of long side walls facing in parallel across the narrow gap above the rotary mold, and a pair of short side walls facing perpendicularly to the narrow gap. In a wide thin plate continuous casting device consisting of a dam container that forms a pool of molten metal, and an injection nozzle whose lower end is immersed in the molten metal of the dam container and whose upper end communicates with the molten metal supply source, the injection nozzle is shaped like an inverted T. Formed in a mold and installed with its outlet facing toward both short side walls of the dam container, so that the hot water discharged from the injection nozzle forms a flow toward both short side walls of the dam container. The present invention provides a wide thin plate continuous casting apparatus characterized by the following.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the wide thin plate continuous casting apparatus of the present invention will be specifically explained below with reference to the drawings. FIG. 1 is a schematic longitudinal section showing an example of an apparatus using twin synchronously rotating casting rolls according to the present invention, FIG. 2 is a schematic cross section taken along the line nu, and FIG. A schematic cross section taken along the line arrow is shown. This device consists of a rotary mold consisting of cooled casting rolls la and lb that rotate in opposite directions and are arranged in parallel with a predetermined narrow gap δ (Fig. 3), and a narrow gap δ above the rotary mold. A dam container 4 that forms a pool of water with a pair of long side walls 2a, 2b facing in parallel across the narrow gap δ and a pair of short side walls 3a, 3b facing perpendicularly to the narrow gap δ;
The apparatus of the present invention is particularly characterized by the structure of the injection nozzle 6, which has a lower end immersed in the molten metal and an upper end communicating with the molten metal supply source (tende sauce 5).

That is, this injection nozzle 6 is formed in an inverted T-shape, and its discharge lowers a and 7b are connected to both short side walls 3a of the dam container 4.
, 3b, and the hot water discharged from the injection nozzle 6 is installed so that a flow is formed in the direction of both short side walls 3a, 3b of the dam container 4.

To explain more specifically, the dam container 4 forms a pool having a large inner width corresponding to the width W of the thin slab 8 to be cast, and is connected to the shafts of the casting rolls la and lb. Vertical long side walls 2a, 2b in the same direction and casting roll 1
Vertical short side walls 3a, 3b perpendicular to the axis of a+ ib
It has a rectangular parallelepiped shape surrounded by. This long side wall 2a
, 2b have a slight gap between their bottom and the surfaces of the casting rolls la, Ib, and a gap δ above the surfaces of the casting rolls la, lb that are about to reach the gap δ. They stand upright and are equidistant from each other. On the other hand, the short side walls 3a, 3b have lower edges shaped along the circumferences of the casting rolls la, lb, with a slight gap from the surfaces of the casting rolls la, lb, and have an inner width W. It is still standing upright.

The long side walls 2a, 2b thus form a wall that prevents hot water from flowing in one opposite direction on the roll surface which is about to go into the gap δ, while the other.

The short side walls 3a and 3b form walls that prevent hot water from flowing beyond the width of the slab onto the roll surface in the axial direction of the roll.

The injection nozzle 6 is used to inject hot water into the dam container 4 from the upper tundish 5.
As shown in FIG. 4 as an example of its shape, it has a vertical passage 10 and horizontal passages 9a and 9b extending from below the vertical passage 10 to both sides. It is made of hardened refractory material. That is, the vertical passage 10 and the horizontal passages 9a, 9b form an inverted T-shaped hot water passage, and the horizontal passages 9a, 9
b denotes discharge lowers a, 7b that open vertically and gradually increase in cross-sectional area as they approach discharge lowers a, 7b;
It is connected to These discharge lowers a and 7b have a mold cross section corresponding to an inverted triangle (
It has a substantially inverted triangular discharge cross section, corresponding to the lower cross section of the dam container 4 shown in FIG.

The injection nozzle 6 having such a structure is arranged as shown in FIGS.
The dam container 4 is placed so as to face the direction of the short side walls 3a, 3b of
The upper end of the injection nozzle 6 is connected to the bottom of the tongue pusher 5.

During casting operation, the dam container 4 is moved from the tank pusher 5 under conditions such that a certain amount of hot water remains in the dam container 4.
Hot water is injected into the dam via the injection nozzle 6, and the discharge lowers a and 7b of the injection nozzle 6 are immersed below the surface of the molten metal in the dam container 4.

Due to the installation structure of the injection nozzle 6, the field flowing into the dam container 4 during the casting operation is from the two discharge lowers a and 7b to the short side walls 3a facing each other within the container 4.
, 3b will be ejected symmetrically.

Therefore, the vicinity of the inner walls of the short side walls 3a and 3b are supplied with high temperature hot water from within the tandem shower 5. As a result, during the casting operation, the thin plate slab to be cast is unevenly stripped inside the dam vessel 4 on both sides! ! ) Is the increase in volume due to heat supplementation by continuous supply of high-temperature hot water? Therefore, it is possible to effectively prevent the formation of solidified shells on the inner surfaces of the short side walls 3a and 3b.

Moreover, if the cross section of the discharge lower a, 71) is shaped into an inverted triangle with the above-mentioned relationship, turbulence in the flow of hot water toward the narrow gap δ can be reduced, and the shape of the solidified shell can be reduced. It is possible to prevent deterioration over time that adversely affects the quality of slabs. Furthermore, if the horizontal passages 9a and 9b inside the injection nozzle 6 are formed so that their diameters gradually increase as they approach the discharge lowers a and 7b, the discharge streams 5 are prevented from becoming a constricted jet stream.

In this way, the occurrence of solidified shells of indeterminate shape in the Zyde dam, which had been a problem in the continuous casting of thin plates using synchronous rotary molds, can be avoided without the need for supplying heat sources from other sources or introducing stirring gas.

Therefore, it can be effectively and conveniently prevented.

The present invention solves a number of problems such as the occurrence of solidified shells in Zyde dams, variations in plate thickness, generation of hot water burrs, and deterioration of surface quality and internal quality.

FIG. 5 shows a wide thin plate continuous casting apparatus of the present invention which is substantially the same as the previous example except that casting healds 10a and 1Ob are used in place of the casting rolls la and Ib of FIGS. 1 to 3. The same effect as described above can also be obtained by installing the injection nozzle 6 having the above-described structure in a rotary mold consisting of casting healds 11a and llb arranged in parallel with a predetermined narrow gap and rotating in opposite directions. .

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view showing an example of a wide thin plate continuous casting apparatus of the present invention, FIG. 2 is a schematic sectional view taken along the line If-II in FIG. 1, and FIG. FIG. 4 is a schematic cross-sectional view taken along the line M, FIG. 4 is an external perspective view showing an example of an injection nozzle, and FIG. 5 is a schematic longitudinal cross-sectional view showing another example of the wide thin plate continuous casting apparatus of the present invention. la, lb...casting roll. 2a, 2b...long side wall, 3a, 3b...short side wall. 4. Dam container, 5. Tongue push. 6... Injection nozzle, 7'a, 7b... Discharge port. 8. Wide thin slab. Figure 3 Figure 4 n

Claims (3)

[Claims] (1) A rotary mold consisting of a pair of casting rolls or casting belts arranged in parallel with a predetermined narrow gap and rotating in opposite directions, and facing in parallel with the narrow gap above the rotary mold. A dam container that forms a pool of water by a pair of long side walls and a pair of short side walls facing orthogonally to the narrow gap, and a lower end of the dam container is immersed in the molten metal and an upper end communicates with a molten metal supply source. In a wide thin plate continuous casting apparatus consisting of an injection nozzle, this injection nozzle is formed into an inverted T-shape, and its discharge ports are installed facing the direction of both short side walls of the dam container, and the casting nozzle is discharged from this injection nozzle. A wide thin plate continuous casting apparatus characterized in that hot water forms a flow toward both short side walls of a dam container. (2) Claim 1, in which the discharge port of the injection nozzle has a substantially inverted triangular discharge cross section so as to correspond to the mold cross section corresponding to an inverted triangle formed above the narrow gap of the one-rotation mold.
Continuous casting equipment for wide thin plates as described in Section 2. (3) The internal passage cross-sectional area of the injection nozzle approaches the discharge port (
A wide thin plate continuous casting apparatus according to claim 1 or 2, which is expanded in scope.