JP3525840B2 - Slab measuring method in continuous casting - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called slab measuring method for determining a cutting position of a continuously cast material in continuous slab casting in which the width of a mold is changed during casting.
In particular, the present invention relates to a technique for cutting a continuously cast material having a changed width with a good yield so as to prevent the width of the cut slab from becoming insufficient.

[0002]

2. Description of the Related Art First, a slab continuous casting line to which the present invention is applied in a steel making process will be described with reference to FIG. Molten steel 25 refined in a converter or other refining equipment is cast into a mold 20 from a tundish 21 via a ladle 22. Then, the shell portion of the surface layer is solidified by the mold 20 and is pulled out downward. Immediately below the mold 20, the drawn continuous casting material 2 remains molten steel in the state where only the shell portion is solidified, and is constrained by a large number of pinch rolls 3 arranged side by side and pulled out. Then, while being spray-cooled with cooling water, the inside is solidified. Continuous casting material 2 solidified to the inside
Is straightened by the straightening device 4 and cut into a desired length by the continuous casting material cutting device 5 to form the slabs 1 one by one.

Here, since the width of the slab varies depending on the required product width, the width of the mold is often changed during casting, and the slab corresponding to this width changed portion has a tapered planar profile. Will have a part. In the taper portion generated by such a width change, the unit weight also changes corresponding to the width change.
Therefore, conventionally, a width meter for measuring the width of the slab was installed upstream of the slab cutting device in the continuous casting line, and the width of the slab changed by this width meter before cutting the continuous casting material into a slab. Of the slab is measured so that the calculated weight is calculated from the measured width of the slab, and the calculated weight is calculated.The cutting length of the slab is determined so that the calculated weight matches the required command weight. (See Japanese Patent Laid-Open No. 5-23810).

Therefore, it is possible to calculate the accurate weight reflecting the profile regardless of the profile at the time of casting, and even if the slab has a taper portion, as specified by the instruction. You can get a slab with a weight of.

[0005]

However, in the conventional method for determining the cutting length by estimating the plane profile of the slab from the measurement value of the width meter and the casting speed, the weight of each slab is made to coincide with the command weight. It is excellent in point, but the position where the width of the continuous cast material is actually changed is the mold position,
There is a problem that it is difficult to deal with another kind of problem that occurs due to the fact that the width measuring position where the width meter is installed is several tens of meters away from the position.

A specific example will be described with reference to FIG. FIG. 3A is a plan view schematically showing the width changing position and the cutting position of the continuous cast material 2 based on the initial command.
In the initial width change plan, the change of the cast width was started at the same time when the casting of the slab 1A of the continuous cast material 2 was completed and the next slab 1B
The width is changed during casting (12a), and the casting width is changed again when the casting for slabs 1B and 1C is completed (12b). Then, the slabs 1D and 1E will be cast.

Then, the cutting at the cutting positions 11a to 11d is scheduled to be performed based on the length information corresponding to each slab. However, in actual operation, the operating conditions, particularly the casting speed, often change from their initial set values due to various factors. Generally, the width of the mold is changed at a constant speed. Therefore, if the casting speed is changed during casting and the casting speed in the width changing section becomes slower than originally planned, the taper 12a at the time of initial planning (Fig.
12c (FIG. 3B) instead of (a)).

However, as described above, the width changing speed in the mold and the casting speed in continuous casting are interlocked so that the taper of the continuously cast material in the width changing portion becomes constant regardless of the casting speed in continuous casting. Even if it is possible in principle, the equipment will be expensive, and the control will be complicated, which is not realistic. Conventionally, this change is absorbed and 1B (Fig. 3
The cutting position 11b was reviewed so that the command weight planned as the profile of (a)) actually matches the actual weight that became the profile of 1b (Fig. 3 (b)), and cutting with the slab cutting device was performed. Was going on. Therefore, the subsequent slab cutting position is displaced.

On the other hand, the width change in the mold has already been completed at the time of reviewing the slab cutting position. Therefore, as shown in the profile of 1c (FIG. 3 (b)), the cutting position 11c is applied to the taper portion 12d, and the insufficient width portion 14 is generated. If this width shortage is within the allowable range of the slab width upper and lower limits, there is no particular problem, but if it is below the lower limit, it causes width defects in the rolling process, so the order from the slab is reduced. There is a problem in production control because it is necessary to remove it and make it a surplus.

A width defect exceeding the upper limit of the slab width allowable range can be easily dealt with by performing a width press or cutting an excessive portion by a width press device installed in the rolling process. However, it is difficult to deal with width defects that are below the lower limit. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a slab measuring method for cutting a slab according to a command weight without causing a slab width defect.

[0011]

SUMMARY OF THE INVENTION The present invention provides a plurality of features during casting.
In slab continuous casting that changes the width of the mold once ,
Based on the slab width and slab thickness is Ra換 calculated or width and thickness of the mold bottom to calculate the calculated weight of the slab, the cutting position such that the instructions weight that is preset with the calculated weight matches When the slab is cut, the cutting of the subsequent slab is performed based on the corrected position information of the cutting position.
The cut position is applied to the taper part that will be generated by the next width change.
The above problem is solved by a slab measuring method in slab continuous casting, which is characterized in that the next width change start point is corrected so as not to exist.

Further, it has been found that when the calculated weight is calculated, it is preferable to make a correction according to the shrinkage of the continuously cast material from the lower end of the mold to the cutting device.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A slab measuring method of the present invention will be described with reference to FIG. FIG. 1 (a) is already shown in FIG.
This is the same as the plan view schematically showing the width changing position and the cutting position based on the initial command of the continuous cast material 2 described in (a), and the description thereof will be omitted here.

A feature of the present invention is that the profile of the continuously cast material is estimated based on the actual results of the change in the mold lower end width when the casting middle width is changed, and the slab having the weight corresponding to the command weight is obtained. The cutting position of the next slab is determined based on this information.
The point is to review the next width change so that the taper portion caused by the change is not applied . That is, as an example, as shown in FIG. 1B, when the casting of the 1a portion of the continuously cast material is finished and the 1b portion is cast, the casting speed of the continuous casting changes and the tapered portion is initially planned. 12a (Fig. 1
In the case where the shape of 12c (FIG. 1 (b)) is obtained instead of the profile of (a)), according to the present invention, when the width change is completed 13a
Will review the next slab width change plan.

First, the commanded weight planned as the profile of 1B (FIG. 1A) and the actual weight actually having the profile of 1b (FIG. 1B) are matched so that the cutting position 11b is adjusted. Make a review. Next, the cutting position 11c is changed so that the slab weight of the 1c slab becomes the command weight. Then, the next width change start position is also reviewed, and the cutting position 11c of the subsequent slab 1c is
The taper part 12d caused by the next width change is not applied
Thus, the new cutting position 11c shown in FIG. 1B is set as the width change start position.

By doing so, it is possible to avoid cutting in the middle of the taper portion during the width change unlike the prior art. Therefore, it is possible to avoid the conventional lack of width in the slab 1c after being actually cut. The present invention is characterized in that the calculated weight is calculated based on the profile of the continuously cast material in the high temperature portion in the unsolidified state immediately after the molding.

On the other hand, the temperature of the continuous casting material is 900 to 1000 ° C. near the cutting device which actually cuts the continuous casting material.
The slab cutting is done at that temperature. Therefore, in calculating the calculated weight in the present invention, it is preferable to consider the shrinkage rate of the slab in consideration of the temperature at the time of cutting the slab.

[0018]

[Example] Applying the slab measuring method of the present invention to a continuous casting line, and when the casting width change in the mold is completed, the calculated weight of the slab is calculated from the slab width and the slab thickness converted from the width of the lower end of the mold. Then, the position where the calculated weight and the preset command weight match is taken as the newly corrected cutting position, and the width change start position for the next slab width is corrected based on the information of the newly corrected cutting position. I decided to do it. The results of applying the present invention are shown in Table 1.

[0019]

[Table 1]

On the other hand, for comparison, a width gauge for measuring the width of the slab is installed upstream of the slab cutting device, and the width of the slab changed by the width gauge before cutting the continuous cast material into the slab. Of the slab is measured so that the calculated weight is calculated by estimating the planar profile from the measured width value and the casting speed, and the cut length of the slab is adjusted so that the calculated weight matches the required command weight. The operation was carried out by applying the conventional driving plan that determines The applied results are shown in Table 2 as a conventional example.

[0021]

[Table 2]

As is clear from the results shown in Tables 1 and 2, it is clear that the application of the present invention can completely eliminate the insufficient width of the slab, which has been a problem in the past. Also, Table 1
In the example of the present invention shown in FIG. 6, it was confirmed that the accuracy of the width change plan of the present invention can be further improved by taking the shrinkage factor into consideration when obtaining the calculated weight.

[0023]

By applying the present invention, it becomes possible to cut the continuously cast material with the width changed in the continuous casting line with a good yield and to prevent the width of the cut slab from becoming insufficient. It became possible to eliminate slab defects.

[Brief description of drawings]

FIG. 1 is a plan view of a continuously cast material for explaining a slab width changing method of the present invention.

FIG. 2 is a side view of a continuous casting line.

FIG. 3 is a plan view of a continuously cast material for explaining a conventional slab width changing method.

[Explanation of symbols] 1, 1a-1e, 1A-1E slab 2 Continuous cast material 3 pinch rolls 4 straightening machine 5 Continuous casting material cutting device 6 transport rolls 7 width meter 11a to 11d cutting position 12a ~ 12d Casting width change part 13a, 13b Casting width change end point 14 Insufficient width (negative width) 20 mold 21 tundish 22 Ladle 25 Molten steel

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B22D 11/05 B22D 11/126 B22D 11/16 104

Claims (2)

(57) [Claims] 1. A slab calculation weight is calculated based on the slab width and slab thickness converted from the width and thickness of the lower end of the mold in continuous slab casting in which the width of the mold is changed a plurality of times during casting. Then, the cutting position is corrected so that the calculated weight matches the preset command weight, and the subsequent stroke is corrected based on the position information of the corrected cutting position .
Tapered part where the cutting position of lab is generated by the next width change
A method for measuring a slab in continuous casting of a slab, characterized in that the starting point of the next width change is corrected so that it does not take a long time. 2. The slab for continuous casting according to claim 1, wherein, when calculating the calculated weight, correction is made according to shrinkage of the continuous cast material from the lower end of the mold to the cutting device. Measuring method.