JPS60133957A - Method for adjusting level of molten steel in tundish at exchanging of ladle - Google Patents

Abstract

PURPOSE:To enable always supply of a molten steel contg. less inclusions by maintaining a constant level of the molten steel on the immersion nozzle side in the stage of exchanging a ladle by means of partition plates disposed freely movably in the longitudinal and height directions of a tundish. CONSTITUTION:A pair of partition plates 5 which are freely movable in the longitudinal and height directions of a tundish 3 are disposed in said tundish and continuous casting is accomplished by supplying a molten steel to the tundish from a ladle 1. While the plates 5 are held lowered in the bottom of the tundish 3 in the stage of starting the exchange of the ladle, the plates 5 are laterally moved to an immersion nozzle 4 side according to the decreased amt. of the molten steel in the tundish 3 and even after the completion of the ladle exchange, the lateral movement is continued until the molten steel head between the plates 5 restores the adequate level. The plates 5 are thereafter ascended and reset to the home position. The specified level of the molten steel in the mounting position of the tundish is thus maintained in the stage of exchanging the ladle, by which the supply of always the molten steel contg. less inclusions is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting the level of molten steel in a tundish when replacing a ladle, and more specifically, the present invention relates to a method for adjusting the level of molten steel in a tundish when replacing a ladle in continuous casting equipment. This relates to an adjustment method that can maintain the height at an appropriate height.

Generally, in continuous casting equipment, a tundish is interposed between the continuous casting mold and the ladle, and the molten steel level in the tundish is kept constant at all times. The supply amount to the continuous casting mold below is adjusted so that the level of molten steel in the tundish remains constant. When operated in this way, the molten steel supplied from the ladle to the center of the tundish is purified by promoting the floating of inclusions before reaching the immersion nozzle in the tundish. A small amount of clean molten steel is supplied to the continuous casting mold side through the immersion nozzle.

This operation is carried out without any problems as long as the molten steel level in the tundish is maintained at a depth suitable for flotation of inclusions.

However, when replacing the ladle, this fluctuation in the molten steel level cannot be avoided. In other words, even though the supply of molten steel to the tundish is stopped until molten steel is supplied from a new replacement ladle due to the replacement of the ladle, molten steel is being supplied to the continuous casting mold, so the tundish is supplied with molten steel. The level of molten steel in the area continues to decline. If the molten steel level decreases, the above-mentioned effect of floating inclusions is impaired, causing problems in the quality of the slab. For this reason, it has been conventional practice to keep the drawing speed of slabs as low as possible in continuous equipment, or to perform complete changeovers in as short a time as possible. However, even if the drawing speed is lowered as in the former case, there is a limit in terms of the occurrence of bulging and the quality of the slab due to proper cooling, and the drawing speed cannot be slowed down. However, since continuous casting in recent years is oriented toward continuous casting, the operational load is large, and the time that can be saved in terms of work has reached its limit.

The present invention aims to solve the above-mentioned drawbacks, and specifically provides an adjustment method that can maintain the molten steel level at the tundish nozzle attachment position at a predetermined level during pot replacement.

That is, in the method of the present invention, a partition plate is attached to the tundish cover so as to be movable in the longitudinal direction and the height direction of the tundish, and when the ladle starts to be replaced, this partition plate is lowered until it reaches the bottom of the tundish, and then the molten steel in the tundish is reduced. The partition plate is moved to the immersion nozzle side according to the amount of molten steel, and the molten steel level on the immersion nozzle installation side is maintained constant in the tundish.

The method of the present invention will be explained in detail below.

First, in continuous casting equipment, molten steel is supplied to the center of the tundish through a long nozzle, etc.
Two partition plates are installed in the longitudinal direction of this tundish, especially at the position where the molten steel is supplied, that is, at the central part. These partition plates are usually attached to the tundish cover and are movable in the longitudinal direction and height direction of the tundish. In addition, during steady operation, the partition plate is not lowered to the bottom of the tundish, leaving a gap between it and the bottom of the tundish, and molten steel is supplied from the tap steel to perform continuous casting.

Next, when replacing the ladle, at the same time as the replacement begins, the partition plate is lowered to the bottom of the tundish, leaving a gap with the bottom of the tundish. The molten steel supply position from the steel is separated from the immersion nozzles on both sides. In this state, each partition plate is moved in the longitudinal direction so as to separate from each other and approach each immersion nozzle. The moving speed of the partition plate is controlled so that the molten steel level ゛□ on the side where the immersion nozzle is installed in the tundish can be maintained at an appropriate height.When the molten steel level is adjusted and poured in this way, the molten steel level is maintained at 1. The ladle can be easily replaced while the pot is still being poured.

Therefore, the 11th ffl(a), (1)), (C), +(
j), (e) and (f) and Figure 2 18) and (
The following is a more detailed explanation of 1)) and ゛.

FIGS. 1(a), (11), (C), (d), (e) and <r> are detailed explanatory diagrams of the present invention, and during normal operation, FIG. The two partition plates 5 are located at the center of the tundish 3, that is, at a position close to the position of the vessel where molten steel is supplied from the ladle, and continuous casting is performed by supplying molten steel from t11 with a gap left between it and the bottom of the tundish. Take steel 1
Figure 1 (1) at the beginning of the exchange
), the partition plate 5 is lowered to the bottom of the tundish while remaining in the same position, and is attached to the bottom of the tundish to eliminate the gap.

As shown in FIG. 1(C), the pair of partition plates 5 are laterally moved toward the sesame nozzle 4 in a direction in which they are separated from each other by υ while keeping their tips attached to the bottom of the tundish. The question of whether the molten steel head of each pair of cutting plates 5 can be recovered to the proper level even after the pot replacement is completed is shown in Fig. 1(d) ((+The cutting plates 5 continue to move horizontally. When operation is reached,
In other words, when the molten steel heads of the pair of partition plates 5 are recovered, the partition plates 5 rise in the same position as shown in No. 11!1(e). In addition, during regular operation □, Figure 1 m
The partition plate 5 is returned to its original position near the center edge as shown in ``During continuous casting operation, this process is repeated to replace the steel.

Further, the pair of partition plates 5 are attached to the tundish so as to be movable in the longitudinal direction and the height direction of the tundish as described above. As shown in FIGS. 2(a) and 2(b), it is constructed in a flat plate shape so that it can be brought into close contact with the tundish 3. Each partition plate 5 is fixedly supported on the tundish cover 8 by a partition plate support device 6, and furthermore, the partition plate support device 6 is connected to the tundish cover 8 vertically and horizontally by a drive device 7 that drives each partition plate vertically and horizontally. It is configured so that it can be moved in any direction.

As explained in detail above, the method of the present invention allows the molten steel level to be adjusted to an appropriate height when replacing the ladle via a pair of mounting plates disposed within the tundish so as to be movable in the longitudinal direction and height direction.

Therefore, when replacing the steel stock, molten steel with few inclusions can always be supplied as in the conventional example, and continuous casting operation can be performed under the same conditions as during regular operation.

[Brief explanation of the drawing]

FIG. 1 (a), (1)), (C), ((1), (e) and m are an example of the implementation process of the method of the present invention during steady operation, when the steel stock exchange starts, during the steel stock exchange, Explanatory diagrams for the completion of ladle crossing, completion of molten steel head recovery, and movement during regular operation, etc., Figure 2 (a
t and (b) are a vertical cross-sectional view and a cross-sectional view of an example of a partition plate. Code 1...Number of molten steel fi2...Long nozzle 3...Tandish 4...Immersion nozzle 5...Partition plate (refractory) 6 ...Partition plate support device 7...Partition plate vertical and horizontal drive device 8...
...Tanditshu Cover Patent Applicant Kawasaki Steel Co., Ltd. Agent Patent Attorney Yoshikatsu Matsushita Lawyer Fumihiro Soe Shima Figure 111 (^) Figure 111 (b) Figure 111 (d) Figure 111 (e,) Figure 1 (±) 1I2rI! I(a) (b)

Claims (1)

[Claims] A partition plate is attached so as to be movable in the longitudinal direction and height direction of the tundish, and when the ladle starts to be replaced, this partition plate is lowered until it reaches the bottom of the tundish.Then, the partition plate is moved to the immersion nozzle according to the amount of molten steel reduced in the tundish. A method for adjusting the level of molten steel in a tundish when replacing a ladle, characterized by moving the molten steel to the side and maintaining a constant level of molten steel on the immersion nozzle installation side within the tundish.