JP2720135B2 - Slab cutting control method in continuous casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention, in b le over-time in the continuous casting,
Those related to how to control the slab cut length for cutting the cutting weight of slab billets such as a target street.

[0002]

2. Description of the Related Art In continuous casting, in general, molten steel is poured into a mold and cooled at the same time. When a solidified liquid is formed from the outer periphery, the solidified liquid is guided by a group of support guide rolls and pulled out by a pinch roll. During the drawing process, cooling is gradually performed by the cooling spray device provided in the secondary cooling zone, and solidification proceeds from the outer peripheral portion of the slab. For example, in the case of a curved continuous caster, at a location where solidification progresses to a predetermined thickness, it is bent to approximately 90 degrees at a predetermined curvature.

[0003] Thereafter, the slab is cut into a predetermined length by a cutting machine and carried out to a subsequent step. In this cutting step, means for measuring the slab pull-out movement amount, for example, a measure roll, is arranged before the cutting machine, and cutting is performed by the cutting machine when the measured drawing-out movement amount matches the cutting target length. In this case, the target cutting length is determined so that the weight of each slab becomes a predetermined value according to the requirements of the next step or the like.

[0004] Various control methods for cutting the slab weight to a desired value have been proposed. For example, JP-A-62-2
Japanese Patent No. 26385 discloses a method in which a coefficient for correcting a relationship between a hot dimension and a cold dimension is obtained from the surface temperature of a slab, the amount of drawing movement by a measure roll is grasped, and cutting is performed.
In Japanese Patent No. 313641, the slab surface temperature, the casting speed, and the number of times the mold is used are detected and grasped as factors affecting the slab cross-sectional shape.
A method has been proposed in which a correction coefficient for correcting a unit weight per a predetermined length is calculated, and a required cutting length according to a target weight is obtained.

[0005]

In a recent continuous casting facility, a slab such as a light pressure reduction device or a cross-section forming device is used in a slab drawing process between a mold and a cutting machine, mainly for the purpose of improving the quality of the slab. A rolling-down device has been provided, and a rolling-down that causes a reduction in the cross-sectional area of a slab has been applied. Under these conditions, when cutting to a predetermined weight for each slab described above, it is only necessary to determine the hot dimension from the slab surface temperature, assuming a continuous caster without the two proposed slab reduction devices. In the method of determining the coefficient that corrects the relationship between the temperature and the cold size, grasping the amount of drawing movement and cutting, and the method of taking into account the casting speed and the number of times the mold is used in the calculation of the correction coefficient, the reduction in the slab drawing process There is a problem that a predetermined weight cannot be obtained for each slab because the influence of the reduction of the slab cross-sectional area is not taken into account.

[0006] The present invention provides a way to cut and accurately grasp the change in weight per unit length, even if there is a reduction of the slab area due reduction in slab drawing process.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a mold and a slab cut.
Change in weight per unit length of slab in drawing process between cutters
Slab pressure reduction devices such as light pressure reduction devices and section forming devices
In cutting a slab in a continuous casting machine having
Before and after the slab reduction device, the slab is drawn per unit time.
The amount of removal movement was measured, and the slab pressure reduction device was used based on the measured values.
The elongation percentage of the cast slab is determined, and the casting
Find the weight per unit length of the slab and determine the weight of the cast slab after cutting.
The feature is to find the cutting length of the slab so that it becomes a constant value
This is a method for controlling slab cutting in continuous casting.

[0008]

[0009]

[0010]

In order to determine the cutting length so that the weight of the slab after cutting becomes a predetermined value, it is premised that the weight per unit length of the slab at the time of cutting is accurately obtained. Normally, when there is no slab reduction device that affects the slab cross-sectional area in the slab drawing step, the weight per slab unit length is obtained as follows.

Weight per unit length of slab (W) = Nominal cross-sectional area of mold × Density of steel × Mold use history correction coefficient × Steel type correction coefficient × Casting speed correction coefficient × Slab temperature correction coefficient

The weight per unit length of the slab when there is a slab reduction device that affects the slab cross-sectional area in the slab drawing process of the present invention is obtained as follows.

Assuming that the slab moving amount per unit time before the slab reduction device is L ₀ and that after the slab reduction device is L ₁ , the elongation rate (E) of the slab by the slab reduction device is Indicated by 1.

[0014]

E = L ₁ / L ₀

Taking this elongation into account, the weight per unit length of the slab (W ') can be obtained by equation (2).

[0016]

## EQU2 ## W '= W / E

As described above, according to the present invention, the weight per unit length of the slab at the time of cutting is accurately obtained even when there is a slab reduction device that affects the slab cross-sectional area in the slab drawing process. The cutting length can be determined so that a predetermined weight can be obtained for each slab.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a control structure of cutting weight control according to an embodiment of the present invention. The continuous casting machine 1 has a curved structure, and includes a tundish 2, a mold 3, a roll group 4 such as a support roll and a pinch roll for stably injecting molten steel, a secondary cooling unit 5 for spray cooling, The apparatus is provided with a group of pressing devices 6, such as a pressing device and a forming pressing device, a cutting machine 7, and the like. The molten steel in the overheated state is injected from the tundish 2 into a mold 3 having a predetermined standard and cast. The mold 3 has a water-cooled structure,
The injected molten steel contacts the mold wall to form a solidified shell.
A slab including an unsolidified portion having a solidified shell formed from the mold 3 is guided by a support roll and simultaneously pulled out by a pinch roll. During the drawing process, the growth rate of the solidified shell is controlled while passing through the secondary cooling section 5, and the solidified shell is reduced by a reduction amount specified by the rolling reduction device group 6 at a predetermined solidified thickness.

Thereafter, the sheet passes through the horizontal drawing section and reaches the cutting machine, where it is cut into a predetermined length.

Rolls 8 and 9 for measuring the amount of slab withdrawal per unit time are installed on the entrance side of the drafting device group 6 such as the light drafting device and near the cutting machine downstream from the drafting device group 6, respectively. The number of rotations of the measuring rolls 8 and 9 is detected by pulse oscillators 10 and 11.

The detected signals are input to an arithmetic unit 12 such as a process computer, and the slab drawing movement amount per unit time before and after the drafting device and the slab elongation rate by the drafting device are calculated from both. The arithmetic unit 12 corrects the weight per unit length of the slab calculated by the conventional method with the slab elongation. Then, the obtained weight per slab unit length after the reduction device is tracked by the measuring roll 9 to the cutting position in association with the slab portion, so that the slab weight after cutting becomes a predetermined value. The slab cutting length is determined and cut by the cutting machine 7.

[0023]

According to the present invention, the weight per unit length of a slab at the time of cutting can be grasped with high accuracy, the slab weight after cutting can be obtained with extremely high accuracy relative to a required value, and continuous casting can be performed. The product yield in is improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a cutting weight control configuration in a continuous casting machine according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous casting machine 3 Mold 5 Secondary cooling part 6 Rolling-down apparatus group 7 Cutting machine 8, 9 Roll for measuring slab pull-out movement amount

Claims (1)

(57) [Claims] 1. A continuous casting machine having a slab pressure reduction device such as a light pressure reduction device or a cross-section molding device that causes a change in weight per unit length of a slab in a drawing step between a mold and a slab cutting machine. Before cutting, the amount of drawing movement per unit time of the slab before and after the slab reduction device was measured, and the elongation percentage of the slab by the slab reduction device was determined from the both measured values. The cast length in continuous casting is characterized in that the weight per unit length of the slab at the time of cutting is determined in consideration of the rate, and the cut length of the slab is determined so that the weight of the slab after cutting becomes a predetermined value. One-sided cutting control method .