JPH06154981A - Method and device for controlling cutting of cast slab in continuous casting - Google Patents

Abstract

PURPOSE:To enable cutting in target by arranging a drawing shifting quantity measuring means of a cast slab before and after rolling reduction device in a continuous casting machine, obtaining extending ratio of the cast slab by rolling reduction and the wt. per unit length of the cast slab at the time of cutting under consideration of this extending ratio and deciding the cutting length so as to become the prescribed cutting wt. CONSTITUTION:In this continuous casting machine 1, the cast slab rolling reduction device of a light rolling reduction device and a cross sectional surface forming device, etc., bringing about variation of the wt. per unit length of the cast slab in the drawing process between a mold 3 and a cast slab cutter 7 is provided. At the time of cutting the cast slab, the drawing shifting quantities of the cast slab per unit time before and after the cast slab rolling reduction device are measured and the extending ratio of the cast slab with the cast slab rolling reduction device is obtd. from both measured values. Under consideration of this extending ratio, the wt. per unit length of the cast slab at the time of cutting is obtd., and the cutting length of the cast slab is obtd. so that the cast slab wt. after cutting becomes the prescribed value. By this method, the wt. per unit length of the cast slab at the time of cutting can be grasped in the high precision and the cast slab wt. after cutting is obtd. to the demanded value in the high precision and the product yield is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a cutting length of a slab for cutting a slab such as a brame or a billet in a continuous casting according to a target cutting weight. .

[0002]

2. Description of the Related Art Generally, in continuous casting, molten steel is poured into a mold, cooled at the same time, and when a solidification liquid is produced from the outer periphery, the molten steel is guided by a group of support guide rolls and is pulled out by a pinch roll. In the process of drawing, the cooling spray device provided in the secondary cooling zone gradually cools and solidification proceeds from the outer peripheral portion of the slab. For example, in the case of a curved-type continuous casting machine, the solidified product is bent at a position having a predetermined thickness and having a predetermined thickness, and is bent at a predetermined curvature of about 90 degrees.

Thereafter, the cast slab is cut into a predetermined length by a cutting machine and is carried out to a post process. In this cutting step, a means for measuring the amount of slab withdrawal movement, such as a measure roll, is arranged in front of the cutting machine, and cutting is performed by the cutting machine when the measured amount of withdrawal movement coincides with the target cutting length. In this case, the cutting target length is generally determined so that the weight of each slab becomes a predetermined value due to the requirements of the next process or the like.

Various control methods have been proposed for cutting such a slab weight in a targeted manner. For example, JP-A-62-1
In Japanese Patent No. 26385, there is a method of obtaining a coefficient for correcting the relationship between the hot dimension and the cold dimension from the surface temperature of a slab, grasping the amount of pulling movement by a measure roll, and cutting.
In Japanese Patent No. 313641, the slab surface temperature, the casting speed, and the number of times of mold use 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 to obtain a required cutting length according to a target weight.

[0005]

In a continuous casting facility in recent years, the main purpose of improving the quality of the slab is to remove the slab of a light reduction device, a cross-section forming device, etc. in the slab drawing process between the mold and the cutting machine. A reduction device has been arranged to apply a reduction that reduces the cross-sectional area of the slab. Under such conditions, when cutting each of the above-mentioned cast pieces so as to have a predetermined weight, it is possible to simply measure the temperature from the cast piece surface temperature on the premise of a continuous casting machine that does not have the above-mentioned two proposed cast piece reduction devices. The coefficient for compensating the relationship between the coldness and the coldness is determined, the method of cutting after grasping the amount of drawing movement, and the method of adding the casting speed and the number of times of mold use to the calculation of the correction coefficient depend on 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 cross-sectional area of the slab is not taken into consideration.

The present invention provides a method and apparatus for accurately grasping the change in weight per unit length and cutting even when there is a reduction in the cross-sectional area of the cast product due to reduction in the cast product drawing process.

[0007]

The present invention comprises:

(1) Casting in a continuous casting machine having a slab reduction device such as a light reduction device or a cross-section forming device that causes a change in the weight per unit length of the slab in the drawing process between the mold and the slab cutting machine. In cutting the piece, measuring the amount of drawing movement per unit time of the slab before and after the slab reduction device,
Obtaining the elongation of the slab by the slab reduction device from the both measured values, the weight per unit length of the slab at the time of cutting in consideration of the elongation to determine the weight of the slab after cutting to a predetermined value. Is a slab cutting control method in continuous casting, characterized in that the cutting length of the slab is obtained so that

(2) In a continuous casting machine equipped with a slab reduction device between the mold and the slab cutting machine, means for measuring the amount of drawing movement of the slab per unit time before and after the slab reduction device, for example, The continuous casting machine is characterized in that major rolls are arranged.

[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 determined. Usually, when there is no slab reduction device that influences the slab cross-sectional area in the slab drawing process, the weight per unit length of the slab is obtained as follows.

Weight per unit length of slab (W) = nominal cross section of mold × steel density × mold usage history correction coefficient × steel type correction coefficient × casting speed correction coefficient × slab temperature correction coefficient

The weight per unit length of the slab when the slab drawing apparatus of the present invention has a slab reduction device that affects the slab cross-sectional area is determined as follows.

Letting L _{0 be} the amount of slab movement per unit time before the slab reduction device and L ₁ after the slab reduction device, the elongation rate (E) of the slab by the slab reduction device is several Indicated by 1.

[0014]

[Equation 1] E = L ₁ / L ₀

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

[0016]

[Equation 2] W ′ = W / E

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

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a control configuration 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 for stably pouring molten steel, a mold 3, a roll group 4 such as support rolls and pinch rolls, a secondary cooling unit 5 for spray cooling, and a light A rolling down device group 6 including a rolling down device, a molding rolling down device, and the like, a cutting machine 7, and the like are provided. The molten steel in an overheated state is poured from the tundish 2 into a mold 3 having a predetermined standard and cast. The mold 3 has a water-cooled structure,
The poured molten steel contacts the mold wall to form a solidified shell.
A slab containing a non-solidified portion in which a solidified shell is formed is guided from the mold 3 by a support roll and simultaneously pulled out by a pinch roll. The growth rate of the solidified shell is controlled while passing through the secondary cooling unit 5 in the process of being drawn out, and when the solidified shell has a predetermined solidified thickness, it is rolled down by the rolling down amount designated by the rolling down device group 6.

After that, when it passes through the horizontal drawing section and reaches the cutting machine, it is cut into a predetermined length.

[0021] Rolls 8 and 9 for measuring the amount of slab withdrawal per unit time are installed on the entrance side of the rolling down device group 6 such as the light rolling down device and in the vicinity of the cutting machine downstream of the rolling down device group 6. The rotation speeds of the measuring rolls 8 and 9 are detected by the pulse oscillators 10 and 11.

These detected signals are input to the arithmetic unit 12 such as a process computer, and the amount of slab withdrawal movement per unit time before and after the reduction unit and the slab elongation rate by the reduction unit are calculated from both. The calculation device 12 corrects the weight per unit length of the slab calculated by the conventional method by the slab elongation rate. Then, the weight per unit length of the obtained slab after the reduction device is tracked to the cutting position in association with the slab site by the measuring roll 9, so that the slab weight after cutting becomes a predetermined value. The slab cutting length is obtained 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, and the weight of the slab after cutting can be obtained with extremely high accuracy with respect to the required value. The product yield in.

[Brief description of drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous casting machine 3 Mold 5 Secondary cooling part 6 Reduction equipment group 7 Cutting machine 8,9 Roll for measuring the amount of slab drawing movement

Claims (3)

[Claims] 1. A continuous casting machine having a casting reduction device such as a light reduction device or a cross-section forming device that causes a change in weight per unit length of the casting in the drawing process between the casting mold and the cutting device. When cutting the, the drawing movement amount per unit time of the slab before and after the slab reduction device is measured, the elongation rate of the slab by the slab reduction device is determined from the both measured values, and the elongation Casting in continuous casting characterized by determining the cutting length of the slab so that the weight per unit length of the slab at the time of cutting takes into consideration the rate and the weight of the slab after cutting becomes a predetermined value One-side cutting control method. 2. A continuous casting machine equipped with a slab reduction device between a mold and a slab cutting machine, wherein means for measuring the amount of withdrawal movement of the slab per unit time are arranged before and after the slab reduction device. A continuous casting machine characterized by that. 3. The continuous casting machine according to claim 2, wherein the means for measuring the amount of drawing movement of the slab per unit time is a major roll.