JP4051834B2 - Continuous casting operation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an operation method for continuous casting, and more particularly to a casting end method for determining a casting end timing of a final cast piece in continuous casting.
[0002]
[Prior art]
In the continuous casting operation, a billet or other slab is cut into a predetermined size based on a production plan. At this time, it is desirable to finish casting so that the final billet has a predetermined size so that a billet having a size outside the production plan is not generated as much as possible. Conventionally, the final billet casting completion has been largely dependent on operator judgment. In other words, when the amount of molten steel in the tundish at the end of casting is close to a predetermined amount, the operator calculates the end position of the final billet from the current cutting status and production plan. Casting was completed while contacting the foundry operator.
[0003]
[Problems to be solved by the invention]
The above-described conventional casting finishing method by the operator has the following problems.
(1) Since the determination of the final billet end position of each strand depends on the operator's judgment, the accuracy of the pouring end position is poor.
(2) The casting end position cannot be determined unless it is just before the end of casting.
(3) There are cases where it is terminated earlier than necessary, or before the scheduled position.
[0004]
The present invention has been made in order to solve the above-described problems, and by continuously calculating the pouring end position of the final slab, continuous casting is aimed at improving production efficiency and product yield. The purpose is to provide a method of operation.
[0005]
[Means for Solving the Problems]
In the continuous casting operation method according to the present invention, in the continuous casting operation, the tundish residual steel is measured by measuring the weight of the tundish residual steel and the slab drawing length of each strand while satisfying the instructed operating conditions. In the operation method of continuous casting in which the casting end timing is determined so that the steel weight is close to the target value, casting of each strand is sequentially terminated from the outer strand by the length of the fixed slab, and the next strand At the end of casting, the order in which casting is completed 30 seconds or more after the end of casting of the previous strand is examined, and the procedure for terminating the casting of the next strand using the order length as the end drawing length is taken. In the procedure, casting of each strand is finished sequentially, and in the final strand, the tundish residual steel weight falls within the target value, Final slab is characterized in that to terminate the cast to determine the slab withdrawal length of the final strand with either conditions or become standard length.
[0008]
With the above configuration, casting can be finished when the weight of the remaining tundish steel is always close to the target value, so that waste of materials is eliminated, and production efficiency and product yield in continuous casting can be improved. it can.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic view of a billet continuous casting facility showing an embodiment of the present invention. In the figure, 1 is a ladle, 2 is a tundish, 3 is a mold, 4 is a spray band, 5 is a pinch roll, 6 is a shear, 7 is a major roll, 8 is a weigh scale, 9 is a process computer, and 10 is a host. A CPU 11 is a terminal device, and 12 is a slab such as a cut billet.
[0010]
In FIG. 1, molten steel poured from a ladle 1 into a tundish 2 is guided to a mold 3, where it is cooled and solidified around to form a shell, and then pulled out by a pinch roll 5. Subsequently, the strand is cooled with cooling water from the spray band 4, supplied to the shear 6 by the pinch roll 5, the length of the slab 12 is measured by the measure roll 7, and is cut into a slab 12 having a predetermined weight. The In addition, although shown about one strand here, a cutting process is performed similarly to the above also about several strand, respectively.
[0011]
Then, the process computer 9 calculates the casting end position of the final slab in each strand based on the setting information from the host CPU 10 and the measurement information from the measure roll 7 and the weigh scale 8. At this time, the process computer 9 terminates the casting by taking into account the cutting length measurement value measured by the measure roll 7 so that the length of the final billet becomes a fixed length, or the remaining steel in the tundish is set to a predetermined weight. The casting is terminated with reference to the weight measurement value measured by the tundish weighing scale 8. In addition, the CRT of the terminal device 11 displays a casting end timing instruction screen as shown in FIG.
[0012]
FIG. 2 is a screen on which a work instruction to the operator is displayed on the CRT. Hereinafter, the procedure for finishing casting will be described based on this.
[0013]
(1) The pouring end position is calculated at the end of pouring molten steel from the ladle into the tundish. This calculation is performed by the process computer 9 as described above.
[0014]
(2) When performing the above calculation, the following conditions are set in the upper CPU 10 in advance, and the calculation is performed so as to satisfy this condition.
(1) Remaining molten steel in the target tundish residual tundish is to prevent noro from flowing into the mold from the tundish and reducing the quality of the slab. In the embodiment, the weight of the target tundish residual steel is 5.0 to 7.0 tons.
{Circle around (2)} Usually, casting is finished from the outermost strand. This is because inclusions are likely to be mixed into the outer strand due to a decrease in temperature. In the embodiment, the process is terminated in the order of the sixth, first, fifth, second, fourth, and third strands.
(3) End interval In order to prevent the end work from competing, a time interval is set for each strand. In the embodiment, it is 30 seconds.
[0015]
(3) Calculation procedure First, the outer sixth strand is targeted. From FIG. 2, when the current PC length (extraction length) is 929.43 m and another 5 m needs to be extracted to take an order, the end timing is the PC length of 934.43 m. Therefore, at this time, the remaining steel for the remaining 5 m is required. The required amount of steel remaining in the tundish for this sixth strand is calculated as follows.
Necessary amount of remaining steel = 5 m x cross-sectional area of slab x specific gravity of slab
Next, the first strand is targeted according to the instructed order. From FIG. 2, it is assumed that the current PC length is 922.27 m, and the PC lengths corresponding to the subsequent orders are 928.50 m and 933.50 m. The order that ends in 30 seconds or more after the elapse of the time until the sixth strand is scheduled to be pulled out is 934.43 m, and the end PC length of the first strand is 933.50 m. At this time, the remaining (933.50−922.27) = 11.33 m is drawn out, so the remaining steel is required. That is, the required amount of steel remaining in the tundish for the first strand is
Necessary amount of remaining steel = 11.23 m x cross-sectional area of slab x specific gravity of slab.
Thereafter, the other strands are processed in the same manner, and the end timing for each strand is determined. Further, the fifth strand requires 16.25 m, the second strand 21.75 m, the fourth strand 24.28 m, and the third strand 23.41 m.
[0017]
And the estimated tundish residual steel weight can be calculated by adding the necessary residual steel amount of each strand and subtracting it from the current molten steel weight in the tundish. The pouring end position of the final slab of each strand is determined so that the estimated tundish residual steel weight falls within the target tundish residual steel weight of 5.0 to 7.0 tons.
In the example, the necessary remaining steel weight is 20.8 tons in total, and if casting is finished when the 943.80 m scheduled to end the third strand is finished, the estimated tundish remaining steel weight will be 6.2 tons, Within the value.
In addition, if the calculated estimated tundish remaining steel amount is excessive or insufficient, it will be dealt with by deleting or adding orders. It is also easy to configure the final billet length to be a fixed length.
[0018]
(4) If the operator changes the instruction content, the estimated tundish remaining steel amount is recalculated accordingly.
[0019]
【The invention's effect】
As described above, according to the present invention, since the casting end timing of the final slab can be accurately calculated, it is possible to promptly and properly perform the operator's work instruction, and the amount of remaining tundish steel Can be reduced (appropriate), and production efficiency and product yield can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of the present invention.
FIG. 2 is a casting end timing instruction screen displayed on a CRT.
[Explanation of symbols]
1 Ladle 2 Tundish 3 Mold 4 Spray belt 5 Pinch roll 6 Shear 7 Major roll 8 Weigh scale 9 Process computer 10 Upper CPU
11 Terminal device 12 Cast slab

Claims (1)

In continuous casting operation, while measuring the tundish residual steel weight and the slab drawing length of each strand while satisfying the instructed operating conditions, cast so that the tundish residual steel weight is close to the target value. In the continuous casting operation method to determine the finish timing
An order in which casting of each strand is finished in sequence with the length of the fixed slab drawn from the outer strand, and at the end of casting of the next strand, casting is finished 30 seconds or more after the lapse of time from the end of casting of the previous strand. Then, the order length is set as the final drawing length, and the casting of the next strand is finished. In this procedure, casting of each strand is finished sequentially, and the remaining tundish steel weight reaches the target value in the final strand. A continuous casting operation method characterized in that casting is terminated by determining a drawing length of a slab of a final strand on the condition that it fits or a final slab is fixed .

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