JPH0647155B2 - Surface protection cover in continuous casting equipment with moving mold walls - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a melt level protection cover in a continuous casting facility having a moving mold wall.

2. Description of the Related Art There is a twin roll type for continuously casting thin plates. In this twin roll type continuous casting equipment, as shown in FIG. 3, a pair of mold rolls (hereinafter, referred to as rolls) 21A and 21B arranged in parallel to each other and these rolls 2
A weir body 23 (only one is not shown) for contacting the end faces of 1A and 21B to form a molten steel reservoir 22 between both rolls 21A and 21B, and for injecting molten steel into this molten steel reservoir 22 And a tundish 25 having a pouring nozzle 24. When continuously casting thin plates with this configuration, when both rolls 21A, 21B are rotated in the direction of arrow A in the state where molten steel is contained in the molten steel reservoir 22, the slabs formed on the surface of each roll 21A, 21B The shells are merged and pressed at the central portions of both rolls 21A and 21B to form one cast piece, which is continuously drawn out as a thin plate 26.

By the way, conventionally, when the surface of molten steel injected into the molten steel reservoir 22 is oxidized or the temperature is lowered, oxides, shells formed on the surface, tundish floating on the surface of the molten metal, or eluates of the nozzle refractory, etc. It becomes trapped in the flow and causes internal or external surface defects in the sheet. For this reason,
Conventionally, the upper surface of the molten steel is covered with a cover, and an inert gas is injected into the cover to prevent oxidation. It is also considered that the molten steel surface is covered with a heat insulating powder to block air and prevent a temperature decrease, and to absorb the eluate of the refractory to reduce the entrainment thereof.

Problems to be Solved by the Invention According to the above-mentioned conventional inert gas, since the volume of the space in the cover is large and the surface area is large, the amount of heat due to radiation is large and the surface of the molten steel is cooled from the molten metal surface. There was a problem that In addition, when powder is used, the powder is caught in the flow of molten steel and the thickness of the cast piece becomes non-uniform, and if it becomes a suspended matter and mixes in the molten steel, it becomes an internal defect, which also leads to product defects. I will end up.

Therefore, an object of the present invention is to provide a pouring nozzle in a twin roll type continuous casting facility that can solve the above problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the first means of the present invention is to provide a molten steel pool formed between a pair of moving mold walls arranged in parallel with each other on each molten steel surface. A central heat insulating material that contacts from above is attached to the central surface of the molten metal excluding the vicinity of the contact portion with the moving mold wall, and the central heat insulating material is projected from both side edges of the central heat insulating material parallel to the moving mold wall. A side heat insulating material is provided to cover an upper space in the vicinity of a contact portion with each moving mold wall and a tip end portion of which is in sliding contact with the surface of each moving mold wall.

The second means is the same as the first means, except that the dip wall is provided substantially downward in parallel with the moving mold wall surface downward from both side edges of the central heat insulating material parallel to the moving mold wall. It is a projecting piece.

Action According to the above-mentioned configuration, the central surface, which is a large part of the molten steel surface of the molten metal pool, is prevented from contacting with the air and the temperature decrease of the molten steel is prevented by the central heat insulating material which is in direct contact. . Further, the contact portion of the molten metal surface with the wall of the moving mold is made into a smaller space by the side heat insulating material and is shielded from the outside, so that the temperature decrease and the oxidation of the molten steel are prevented as much as possible.

Embodiment One embodiment of the present invention will be described below with reference to FIG.

1A and 1B are mold rolls (hereinafter, simply referred to as rolls), which are a kind of moving mold walls arranged in parallel to each other, and both rolls 1A and 1B and both rolls are located between these rolls 1A and 1B. A molten steel reservoir 3 is formed in cooperation with a pair of weir bodies (also called short side weirs, only one of which is shown) 2 arranged in contact with both end faces of 1A and 1B. Reference numeral 4 denotes a pouring nozzle main body for guiding molten steel into the molten steel reservoir 3 from this dandishes (not shown), and is provided so as to hang down from the tundish. This nozzle body 4
In the lower part of the, the heat insulation of the molten steel surface (hereinafter, simply referred to as the molten metal surface) is a rectangular central part that is in contact with the central surface of the molten metal surface from above except for the vicinity of the contact part (tangential line part) with each roll 1A, 1B. Material 5
Are held by the upper and lower stoppers 6A and 6B.
The central heat insulating material 5 can be moved by a predetermined height h between the stoppers 6A and 6B. This is to follow the fluctuation of the molten metal level. Then, the side heat insulating material 8A, which covers the upper spaces 7A, 7B near the contacting portions with the rolls 1A, 1B, upward from the side edges of the central heat insulating material 5 parallel to the rolls 1A, 1B. 8B
And the lower end surfaces 9A and 9B of the tip end thereof are in sliding contact with the surfaces of the rolls 1A and 1B. Therefore, the central portion of the molten metal surface is directly connected to the central heat insulating material 5, and the upper space 7A on both sides of the molten metal surface on the roll 1A, 1B side,
7B is covered with the side heat insulating materials 8A and 8B. Of course, the end faces of the heat insulating materials 5, 8A, 8B on the weir body 2 side are in contact with the surface of the weir body 7.

Next, each heat insulating material will be described. Central heat insulating material 5
Is composed of a ceramic fiber having a low specific gravity or a multi-cell refractory so as to float on the surface of molten steel. When a powdery refractory material is used instead of this, a fiber layer composed of fibers having a length of 5 mm or more is provided on the surface thereof so that the powder does not flow into the molten steel. By using such a material, air having a low thermal conductivity can be contained inside, and its heat insulating property is enhanced. Further, the central heat insulating material 5 may be one in which a ceramic wool or a porous refractory material is put inside a titanium alloy box which can withstand the temperature of molten steel. In addition to this structure, a high temperature combustion gas is passed inside. You may make it heat-retaining effect. Further, as the side heat insulating materials 8A and 8B, ceramic, metal, or the like is used. In addition, a graphite member having good slidability may be used for the sliding contact portions of the side heat insulating materials 8A and 8B with the rolls 1A and 1B.

Therefore, the central heat insulating material 5, which is in direct contact with the surface of the central portion, which is the majority of the molten metal surface, is cut off from contact with air and the temperature of the molten steel is prevented from decreasing. Further, the contact portion of the molten metal surface with the rolls 1A, 1B is the side heat insulating material 8A,
8B has smaller spaces 7A and 7B and is shielded from the outside, so that heat radiation and oxidation are reduced as much as possible so as not to obstruct the entrainment of molten steel.

As described above, since most of the molten metal surface is directly contacted and covered by the central heat insulating material 5, oxidation of the molten metal surface and temperature decrease can be prevented without using powder,
No foreign matter is mixed into the molten steel, and no defects occur in the cast piece, that is, the thin plate drawn from between the rolls. Further, it is more preferable to supply an inert gas into the spaces 7A and 7B in order to prevent oxidation.

Next, another embodiment will be described with reference to FIG.

This is the dipping wall 10A, which is substantially parallel to the central heat insulating material 5 in the above-described embodiment from both side edges parallel to the rolls 1A and 1B, and at a predetermined distance from the surface of the rolls 1A and 1B. 10B is projected and side heat insulating material 8A, 8B
The inert gas supply pipes 11A and 11B are connected to.

The immersion walls 10A and 10B are made of a refractory which is not easily corroded by molten steel, and are selected depending on the steel type, but alumina / graphite or zirconia is used. The immersion depth of the immersion walls 10A and 10B is, for example, in the range of about 10 mm to 100 mm, and the distance from the surface of the rolls 1A and 1B is in the range of about 10 to 40 mm from the viewpoint of stability of casting.

Therefore, when the rolls 1A and 1B rotate in the direction of arrow A, the molten steel in the vicinity of the slab shell 12 also moves downward due to the downward movement of the slab 12; In order to make up for it, as shown by arrow B, new molten steel flows over the immersion walls 10A and 10B and flows upward. For this reason, a turbulent flow region is generated at the boundary between the flows in the opposite directions, and the rolls 1A, 1
This enables remelting of the surface of the slab shell 12 formed on the B surface, thus eliminating the uneven thickness of the slab shell 12 formed on the surfaces of the rolls 1A and 1B.

In the case of this configuration, in the same manner as in the above-described embodiment, it is possible to prevent the oxidation of the molten metal surface and the temperature decrease, and at the same time, the inert gas is provided in the space 7A, 7B above the contact portion of the molten metal surface with the rolls 1A, 1B. Therefore, the molten steel on the surface of the molten metal can be reliably prevented from oxidizing, and because of the immersion walls 10A and 10B, new hot molten steel from the nozzle body 4 flows backward in the vicinity of the surface of the molten metal. It is possible to maintain the temperature of the molten metal surface a of the rolled-in portion at a temperature at which the shell does not occur, and to regenerate the surface layer portion (the surface where solidification is progressing, that is, the shell inner surface) of the cast shell 12 generated on the surface of the rolls 1A and 1B. Slab shell 12 for melting
Eliminates uneven thickness. Further, the molten steel spouted from the nozzle body 4 is directly fed to the rolls 1A and 1A by the immersion walls 10A and 10B.
This prevents the slab shell 12 from colliding with the slab shell 12 on the B surface and becoming uneven or damaged in the shell thickness.

By the way, in the above-mentioned respective embodiments, the weir body 2 is set to the roll 1
Although it has been described that the end faces of A and 1B are slidably contacted from the side, for example, the dam body 4 may be placed and slidably contacted from above the ends of the rolls 1A and 1B. Further, although the center heat insulating material 5 is described as being supported and guided by the nozzle body 4, it may be supported and guided by the weir body 2. further,
Although the twin roll type has been described in each example,
Needless to say, it can be applied to a belt-type or caterpillar-type continuous casting facility instead of the roll.

Effects of the Invention According to the configuration of the present invention, since most of the molten metal surface is directly contacted and covered by the central heat insulating material, it is possible to prevent oxidation of the molten metal surface and temperature decrease without using powder. No foreign matter is mixed into the molten steel, and no defects occur in the cast piece, that is, the thin plate drawn from between the rolls.

Also, if a dip wall is provided at the side edge of the heat insulating material in the center, new molten steel flows into the part between the roll and the dip wall, which causes the surface layer of the cast shell on the roll surface to re-melt and cause uneven thickness. It can be lost.

[Brief description of drawings]

FIG. 1 is a sectional view of a molten metal surface protection cover in one embodiment of the present invention, FIG. 2 is a sectional view of a molten metal surface protection cover in another embodiment of the invention, and FIG. 3 is an overall sectional view of a conventional example. is there. 1A, 1B ... Mold roll, 4 ... Nozzle body, 5
…… Central heat insulating material, 7A, 7B …… Space, 8A, 8B…
… Side insulation, 10A, 10B …… immersion wall, 11A, 11B …… Supply pipe.

Claims (2)

[Claims] 1. A molten steel pool formed between a pair of moving mold walls that are arranged in parallel to each other, from the top to the central surface of the molten metal except for the vicinity of the contact portion of the molten steel surface with each moving mold wall. A central heat insulating material to be contacted is attached, and the central heat insulating material is projected from both side edges parallel to the moving mold wall of the central heat insulating material to cover the upper space in the vicinity of the contact portion with each of the moving mold walls and its tip is A surface protection cover in a continuous casting facility having a moving mold wall, characterized in that a side heat insulating material is provided in sliding contact with the surface of the moving mold wall. 2. An immersion wall is provided so as to project downward from both side edges of the central heat insulating material parallel to the moving mold wall and substantially parallel to the moving mold wall surface at a predetermined interval. Item 1. A molten metal surface protection cover in a continuous casting facility having a moving mold wall according to Item 1.