JP2938313B2 - Pouring method at the end of ladle injection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pouring method at the end of ladle pouring, and more particularly to a pouring method capable of reducing slag flowing out of a ladle into a tundish and minimizing the amount of remaining hot water. .

[0002]

2. Description of the Related Art As is well known, for example, in continuous casting of slag, molten steel is once injected into a tundish from a ladle and then supplied to a mold from the tundish. The slag in the ladle flows into the tundish. When cast as it is, slag may be mixed as inclusions in the obtained slab, and the quality of the slab may be significantly impaired. As a technique for preventing slag from being mixed in, Japanese Patent Application Laid-Open No. 61-119358 and Japanese Patent Application Laid-Open No. 2-4174 are disclosed.
No. 4 has been proposed.

[0003] The former uses a tundish having a structure in which a tundish is divided into two in the width direction and is divided into a hot water receiving chamber and a hot water discharging chamber. This is a casting method in which ladles are arranged at both ends of the hot water receiving chamber and molten steel is poured alternately.However, as a slag stopper is inserted as a countermeasure for slag outflow at the end of injection of the previous ladle, it leads to an increase in cost, and In addition, it is difficult to reliably engage the slag stopper with the nozzle on the ladle, and the outflow of the slag cannot be completely stopped.

[0004] In order to prevent slag from being mixed in the tundish, pouring is stopped with the molten steel remaining in the ladle before the vortex is generated, and the remaining steel and the slag in the ladle are refined while being hot. It is a method of recharging the furnace (converter). However, the existing steel works usually do not have a logistics structure that allows the remaining steel to be recharged to the refining furnace while hot, making this possible. To do so requires a large amount of equipment remodeling costs. Also, the yield of molten steel per charge is low.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inexpensive pouring method which can reliably prevent slab from being mixed when pouring from a ladle into a tundish and can drastically improve molten steel yield. And

[0006]

SUMMARY OF THE INVENTION The present invention has been made to advantageously solve the above-mentioned object, and its gist is as follows. (1) The relationship between the remaining amount of ladle hot water and the vortex generation limit injection amount is described. It is characterized by grasping the remaining hot water amount from the load cell of the ladle, grasping the injection amount at that time from the load cell value change per unit time, and pouring into the tundish at the injection flow rate in the area where vortex does not occur. Pouring method at the end of ladle injection. (2) The method according to (1), wherein a tundish capable of receiving hot water simultaneously from a plurality of ladles is used.

[0007]

Next, the present invention will be described with reference to an embodiment shown in FIG. 1a is a front ladle for supplying molten steel 2a to a tundish 5 via a long nozzle 3 and an SN plate 4 provided on the long nozzle 3. Reference numeral 6 denotes an immersion nozzle provided in the tundish 5 for injecting the molten steel 2 a into the mold 7. Reference numeral 8 denotes a slab.

Reference numeral 9 denotes a load cell for detecting the amount of remaining hot water in the ladle 1a. Reference numeral 10 denotes a molten steel decrease amount calculator per unit time based on a signal from the load cell 9, which grasps the molten steel injection amount from the long nozzle 3. Reference numeral 11 denotes a computer, which stores in advance the relationship between the remaining amount of ladle hot water and the vortex generation limit injection amount shown in FIG.

Thus, the computer 11 receives the current remaining molten metal amount from the load cell 9 and the molten steel injection amount data from the molten steel reduction amount calculator 10 one by one. Is calculated (FIG. 1) and compared with the current injection amount, and an SN plate opening / closing signal is output so that the injection amount becomes high in the operation region. The open / close signal is converted through the signal converter 12, and the SN
An input to the hydraulic unit changes the opening of the SN plate 4. This control is repeatedly executed to control the injection amount according to the amount of molten steel remaining.

Here, FIG. 2 shows a mode in which two ladles are arranged on the tundish 5, but when only the ladle 1a is arranged, the amount of molten steel injected at the end of injection of the ladle 1a is shown in FIG. Set in the operation area of. At this time, the weight of the molten steel in the tundish 5 is reduced, and the molten metal level is lowered. However, if it is desired to reduce the level of the molten metal level, a change in the molten metal level can be reduced by setting the drawing speed of the slab 8 low.

On the other hand, the ladles 1a and 1a shown in FIG.
When operating with the two ladles of b, the molten steel injection amount in the last stage of injection of the front ladle 1a is performed in the operation region of FIG. 1 and the injection amount is reduced according to the remaining hot metal amount. At this time, the weight of the molten steel in the tundish 5 is reduced, but by supplying this amount from the rear ladle 1b, the molten steel level in the tundish 5 does not decrease, and therefore, the slab drawing speed does not decrease continuously. Operation becomes possible.

In FIG. 2, the load cells 9 to SN hydraulic units 13 are arranged only on the front ladle 1a side, but the same ones are arranged on the rear ladle 1b side for operation. Omitted).

Next, a specific operation example will be described. (Invention) In FIG. 2, the ladle 1a is charged with 250t of low-carbon aluminum killed steel (the ladle 1b is not used) and the capacity is 6
Using a tundish 5 of 0 t, a slab 8 of 245 mm × 1400 mm was cast. The remaining amount of molten steel in the load cell 9 is 14 ton based on the relationship shown in FIG.
Until it reaches 10 t / min.
Injection was performed at an injection rate of 5 ton / min until ton, and then injection was performed at an injection rate of 2 ton / min. The operation status at this time is shown in FIG.

(Comparative Example) In FIG. 2, 250 tons of low-carbon aluminum killed steel was inserted into the ladle 1a (without using the ladle 1b), and a tundish 5 having a capacity of 60 t was used.
A slab 8 of 400 mm was cast. The remaining molten metal was measured by the load cell 9 and the injection was performed at an injection rate of 10 t / min until the end.
The operation status at this time is shown in FIG.

FIGS. 4 (a) and 4 (b) show the remaining hot water amount and quality results as a result of the operation as described above. According to the present invention, the outflow of the slag 2b into the tundish at the end of the ladle injection can be reduced to almost zero, and the slab quality is greatly improved. In addition, since the amount of remaining molten metal can be reduced to almost zero, the yield of molten steel can be greatly improved.

[0016]

As described above, according to the method of the present invention in which the pouring amount at the end of ladle injection is equal to or less than the vortex generation limit injection amount, the outflow slag can be made almost zero and the final molten steel remaining metal amount can be made almost zero. The molten steel yield can be improved. In addition, there is no need to use a slag stopper, and the distribution structure in the factory does not need to be improved, which is economically advantageous.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a relationship between a ladle residual hot water amount and a vortex generation limit injection amount.

FIG. 2 is a device layout diagram showing an example of an apparatus for implementing the present invention.

FIG. 3 is an explanatory diagram showing an operation example according to the present invention and a comparative operation example.

FIG. 4 is an explanatory diagram showing operation results in an operation example of the present invention and a comparative example.

[Explanation of symbols]

Reference Signs List 1 ladle 2a molten steel 2b slag 3 long nozzle 4 sliding nozzle plate 5 tundish 6 immersion nozzle 7 mold 8 cast piece 9 load cell 10 molten steel reduction calculator 11 computer 12 signal converter 13 SN hydraulic unit

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hidemi Watanabe 5-3 Tokai-cho, Tokai-shi, Aichi Prefecture Nippon Steel Corporation Nagoya Works (56) References JP-A-5-38558 (JP, A) JP-A-5-38562 (JP, A) JP-A-6-23503 (JP, A) JP-A-7-323356 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 11 / 10 B22D 11/16 104 B22D 11/18 B22D 41/50 540 B22D 41/56

Claims (2)

(57) [Claims] 1. The relationship between the remaining amount of ladle hot water and the limit injection amount of vortex generation is determined, the remaining hot water amount is grasped from the load cell of the ladle, and the injection amount at that time is grasped from a change in the load cell value per unit time to generate vortex. A pouring method at the end of ladle pouring, characterized by pouring into a tundish at a pouring flow rate in a region not to be filled. 2. The method according to claim 1, wherein a tundish capable of simultaneously receiving hot water from a plurality of ladles is used.