JPH02220740A - Molten metal surface protecting cover in continuous casting device having mobile mold wall - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a molten metal surface protection cover for continuous casting equipment having moving mold walls.

Conventional technology There is a twin roll type method for continuously casting thin plates. As shown in FIG. 2, this twin roll type continuous casting "Jfi equipment" includes a pair of mold rolls (hereinafter referred to as rolls) 21A and 21B arranged parallel to each other,
A weir body 23 (only one of which is shown) is placed in contact with the end surfaces of these rolls 21A and 21B to form a molten steel reservoir 22 between both rolls 21A and 21B, and molten steel is injected into this molten steel reservoir 22. A tundish 25 having a pouring nozzle 24 for this purpose was provided. When continuously casting a thin plate with this configuration, if both rolls 21A and 21B are rotated in the direction of arrow A while molten steel is contained in the molten steel reservoir 22, the slab formed on the surface of each roll 21A and 21B is The shells are pressed together at the center of both rolls 21A and 21B to form a slab, which is continuously drawn out as a thin plate 26.

By the way, conventionally, when the surface of molten steel poured into the molten steel reservoir 22 oxidizes or the temperature decreases, oxides, shells formed on the surface, or eluates of tundishes and nozzle refractories floating on the surface of the molten steel are released into the molten metal. can become entangled in the flow, causing internal or external surface defects in the sheet. For this reason, in the past, the upper surface of the molten steel was covered with a cover, and an inert gas was injected into the cover to prevent oxidation.

It is also being considered to cover the surface of molten steel with heat insulating powder to block air and prevent a drop in temperature, and also to adsorb eluates from refractories to reduce their entrainment.

Problems to be Solved by the Invention According to the conventional method using inert gas, the volume of the space inside the cover is large and the surface area is large, so the amount of heat due to radiation is large, and the molten steel cools from the surface of the hot water, causing the hot water surface shell. There was a time when Zhao was able to do it. Additionally, when powder is used, the powder gets caught up in the flow of molten steel, making the thickness of the slab uneven, and if it becomes floating matter and gets mixed into the molten steel, it can cause internal defects, which can also lead to product defects. It becomes connected.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a surface protection cover for continuous casting equipment having a movable mold wall that can solve the above-mentioned problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the molten metal surface protection cover in the continuous casting equipment having movable mold walls of the present invention is designed to protect the molten steel formed between a pair of movable mold walls arranged parallel to each other. A heat insulating material that covers the entire surface of the molten steel poured into the reservoir is suspended, and the heat insulating material is placed downwardly from both sides parallel to the movable mold wall and at a predetermined distance from the movable mold wall surface. The immersion wall is provided with an immersion wall protruding approximately parallel to the wall.

Effect According to the above configuration, the entire surface of the molten #A molten metal surface in the molten metal pool is:
The direct contact with the heat insulating material cuts off contact with air and prevents the temperature of the molten steel from dropping. In addition, since immersion walls are provided on both sides of the heat insulating material, new molten steel flows into the area between the moving mold wall and the immersion wall, causing the surface layer of the slab shell on the surface of the moving mold wall to is remelted and uneven thickness does not occur.

Example An embodiment of the present invention will be described below with reference to FIG.

1A and IB are mold rolls (hereinafter simply referred to as rolls) that are a type of movable mold walls arranged parallel to each other.

), a pair of weir bodies (also called short side weirs, only one of which is shown in the figure) are arranged between both rolls IA and IB and in contact with both end faces of both rolls IA and IB. ) 2, a molten steel reservoir 3 is formed.

Reference numeral 4 denotes a pouring nozzle body for guiding molten steel from the tundish (not shown) into the molten steel reservoir 3, which is provided to hang down from the tundish. At the bottom of this nozzle body 4, there is a melt! 4 The entire hot water surface (hereinafter simply referred to as the hot water surface), to be more precise, the hot water surface and each roll IA.

A heat insulating material 5 having a rectangular shape in plan view and floating in contact with the hot water surface from above except for the vicinity of the contact portion (tangential portion) with 1B is held via a stopper 6 so as to be movable up and down. Further, on the lower surfaces of both sides of the heat insulating material 5, rolls IA and IB are provided parallel to the axis of the rolls IA and IB.

An immersion wall portion 7 having an inverted triangular cross section is provided at a predetermined distance from the 18 surface. Further, the position of the stopper 6 is determined so that both ends of the heat insulating material 5 do not come into sliding contact with the surfaces of the rolls IA and IB, that is, so that a predetermined gap a is secured. At this position, the heat insulating material 5 can freely follow the surface of the hot water.

Further, the hot water level is controlled so that no gap is created between the hot water level and the heat insulating material 5.

That is, a level detection rod 8 is provided protruding from the upper surface of the heat insulating material 5, and a level detector 9 detects the vertical position of the horizontal support part 8a of the level detection rod 8 on the fixed side of the continuous casting equipment. Then, the level value is input to a hot water level control device (not shown), and for example, when the hot water level is low, the hot water amount is increased, and when the hot water level is high, the hot water amount is decreased, so that the hot water level is kept at an almost constant position. will be maintained. In addition, rolls IA, IB and insulation material 5
In order to prevent air from being drawn into the molten steel through the gap a, an inert gas supply pipe 10 for spraying an inert gas such as N2 gas or A gas is arranged in the gap a. , the heat insulating material 5 floats on the surface of the hot water,
For example, pressed alumina fibers are used, and a ceramic coating (for example, zirconia coating) 11 is applied to the molten steel side surface of the heat insulating material 5 from the immersion wall 7 to the outer end surface to extend the service life. The goal is to That is, if the coating 11 were not present, the heat insulating material 5 would be melted by heat, float in the molten steel, and gradually melt into the molten steel, so this is prevented.

In the above configuration, when casting is started, the entire surface of the molten metal is cut off from air by the heat insulating material 5 that is in direct contact with it and prevents the temperature of the molten steel from decreasing. And at this time,
The amount of molten steel injected is controlled via a level detector 9 so that the molten metal level is always at an appropriate position. In this way, since the entire surface of the molten metal is covered by the heat insulating material 5 in direct contact with the surface of the molten steel, oxidation of the molten metal surface and temperature drop can be prevented without using powder, thereby preventing foreign matter from entering the molten steel. The inert gas is supplied from the inert gas supply pipe 10 to the gap a between the heat insulating material 5 and the rolls IA and 1B. Oxidation of molten steel is reliably prevented.

Also, when rolls IA and IB rotate in the direction of arrow A,
As the slab shell 12 formed on the surface moves downward, the molten steel in the vicinity also moves downward due to its viscosity.
In order to compensate for the moved molten steel, new molten steel flows upwardly over the immersion wall portion 7, as shown by arrow B. For this reason, a turbulent area is created at the boundary between the flows in opposite directions, and the heat of the new molten steel causes the roll I
A.

This makes it possible to remelt the surface of the slab shell 12 formed on the surface of the rolls IA and IB, thereby eliminating uneven thickness of the slab shell 12 formed on the surfaces of the rolls IA and IB.

In addition, by rectifying the flow of molten steel in the width direction, the entrainment of molten steel in section b is stabilized, and the slab shell 1 is transferred from the immersion wall 7 of the heat insulating material 5 to the lower surface of the rolls IA and IBIIl.
2 does not occur, so there is no entrainment phenomenon of the slab shell.Furthermore, this immersion wall portion 7 prevents the nozzle body
This prevents the molten steel ejected from directly colliding with the slab shell 12 on the surfaces of the rolls IA and 1B, thereby preventing thickness unevenness and damage to the slab shell 12.

By the way, in each of the above embodiments, the weir body 2 is
Although the description has been made assuming that the weir body 2 is brought into sliding contact with the end surfaces of the rolls IA and IB from the side, for example, the weir body 2 may be brought into sliding contact with the device from above the ends of the rolls IA and IB.
Although the explanation has been made assuming that the nozzle body 4 supports and guides, the weir body 2 may support and guide. Furthermore, although twin roll type casting equipment has been described in each embodiment, it is obvious that it can be applied to belt type or caterpillar type continuous casting equipment instead of roll casting equipment.

Effects of the Invention According to the above structure of the present invention, since the curved surface is covered by the heat insulating material in direct contact with the heat insulating material, oxidation of the molten metal surface and temperature drop can be prevented without using powder. There are no foreign substances mixed in, and the slabs or thin plates that are pulled out from between the pair of movable mold walls do not have any defects.Moreover, because immersion walls are provided on both sides of the heat insulating material, the movable mold walls The inflow of new molten steel into the area between the moving mold wall and the immersion wall prevents the surface layer of the slab shell on the moving mold wall surface from being remelted and causing thickness unevenness.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a hot water surface protection cover according to an embodiment of the present invention, and FIG. 2 is an overall cross-sectional view of a conventional example. IA, IB...roll, 3...molten steel reservoir, 5...
Heat insulation material, 7... Immersion wall part, 8... Hot water level detection rod, 9.
...Level detection meter. Agent Yoshihiro Morimoto R KafA, 1B ---o-ru 3-11dan 11 look 5-Insulation material day-Level detection needle f! JI drawing 2nd figure

Claims (1)

[Claims] 1. A heat insulating material covering the entire surface of the molten steel poured into the molten steel reservoir formed between a pair of movable mold walls arranged parallel to each other is suspended, and the heat insulating material is connected to the moving mold wall. 1. A hot water surface protection cover for a continuous casting equipment having a movable mold wall, characterized in that an immersion wall portion is provided downwardly from parallel both sides and approximately parallel to the surface of the movable mold wall at a predetermined interval.