JP2000263204A - Device for controlling weight of tundish for continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the molten steel weight in a tundish and to improve the control precision of the molten steel surface in a mold by detecting a factor for changing the pouring quantity of the molten steel adding the correction to the molten steel pouring quantity and pouring the molten steel from a ladle. SOLUTION: The speed of rollers for carrying a cast slab is detected with a first detector to detect the casting speed of the mold. The changing quantities of the width direction and the thickness direction of the space in the mold during casting are detected with a second and a third detectors while co-operating with a mold width changing device and a mold thickness changing device to detect the width and the thickness of the cast slab. In a correcting value arithmetic operating part, the changing quantity from the detected casting speed, the changing quantity from the detected width of the cast slab and the changing quantity from the detected thickness of the cast slab, are obtd., respectively. The correcting calculation is executed by using each changing quantity in these. The obtd. corrected value is transmitted to an adder and added to a command value of the molten steel pouring quantity to correct the molten steel quantity to be poured into the tundish from the ladle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tundish weight control device for a continuous casting machine.

[0002]

2. Description of the Related Art A general tundish weight control device in a continuous casting machine will be described with reference to FIG.
The molten steel injection amount adjuster 21 for adjusting the molten steel injection amount from the ladle 20 to the tundish 30, the first control device 22 for controlling the molten steel injection amount adjuster 21, and the weight detector 31 of the tundish 30 And a second control unit 23 that outputs a command value of molten steel injection amount from the ladle 20 to the tundish 30 to the first control unit 22 based on the comparison result. I have.

The tundish weight control is performed by a weight detector 3
The second control device 23 is implemented by PID feedback control for operating the molten steel injection amount adjuster 21 via the first control device 22 in accordance with the deviation between the measured value of the molten steel weight in the tundish from 1 and the target value. ing.

[0004]

In such a tundish weight control device, generally satisfactory control accuracy can be obtained, but the control is slow in response to disturbance.

[0005] This is because, when the mold level control of the continuous casting machine is the injection amount control by the stopper, the weight fluctuation in the tundish changes the flow coefficient of the stopper. And even if the stopper opening degree is constant, if the weight of the tundish is unstable, the injection amount of molten steel is also unstable.

An object of the present invention is to provide a tundish weight control device capable of improving the control accuracy of tundish weight.

[0007]

SUMMARY OF THE INVENTION The present invention provides an adjusting device for adjusting the amount of molten steel injected from a ladle into a tundish, a first control device for controlling the adjusting device, and a tundish weight detector. And a second controller for outputting a command value of molten steel injection amount from the ladle to the tundish to the first controller based on the comparison result. In the tundish weight control device, the change in the factor that changes the amount of molten steel injected from the tundish into the mold in the post-molding process is detected, and the amount of molten steel injected from the ladle into the tundish is corrected. An additional feedforward control system is provided.

[0008] The feedforward control system includes:
A first detector for detecting the casting speed of the mold, a second detector for detecting the width of the slab during casting, and a third detector for detecting the thickness of the slab during casting. Calculating means for calculating a correction value for the molten steel injection amount command value from detection values from the first to third detectors and adding the calculation result to an output of the first control device. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1, the same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description is omitted.

The present invention is based on the following findings.

(1) In the tundish weight control, if the amount of molten steel poured into the mold 40 from the inside of the tundish 30 and the amount of molten steel injected into the tundish 30 from the ladle 20 are always balanced, a stable state can be obtained. .

(2) The reason why this state is unbalanced is largely due to the fact that the amount of molten steel poured into the mold 40 from the inside of the tundish 30 changes due to the process after the mold 40 of the continuous casting machine.

(3) Therefore, a change in a factor that changes the amount of molten steel poured out of the tundish 30 is detected, and the amount of molten steel injected from the ladle 20 into the tundish 30 is corrected, so that a more stable amount is obtained. Tundish weight control becomes possible.

In the present embodiment, a feedforward control system is provided for detecting and correcting a change in a factor that changes the amount of molten steel injected into the amount of molten steel injected from the ladle 20, based on the above knowledge. It is characterized by the following.

During operation of the continuous casting machine, the tundish 30
There are the following three changes in the process that change the amount of molten steel to be poured from the steel.

Change in casting speed Change in width of cast slab during casting Change in thickness of cast slab during casting Therefore, in the present embodiment, the casting speed of mold 40 is used as a detector for detecting the above process change. A first detector 11 for detecting Vc, a second detector 12 for detecting a width Wm of the slab during casting, and a third detector 13 for detecting a thickness Tm of the slab during casting. And And the first
To the second based on the detection values from the third detectors 11 to 13
A correction value calculating section 14 for calculating a correction value for the molten steel injection amount command value from the control device 23, and an adder 15 for adding the calculation result to the output of the first control device 23, that is, the molten steel injection amount command value. As arithmetic means. In addition,
The first detector 11 detects a casting speed by detecting a speed of a roller that conveys a slab. The second and third detectors 12 and 13 are provided on the mold 40, respectively.
By detecting the amount of change in the width direction and the thickness direction of the space in the mold 40 during casting in cooperation with a mold width changing device and a mold thickness changing device (not shown), the width W of the slab is obtained.
m and thickness Tm are detected.

On the other hand, the correction value calculation unit 14 performs the following calculation. First, the change d from the casting speed Vc
Obtaining ^{VC = Vc n -Vc n-1} , the amount of change from the width Wm of the slab ^{dWm = Wm n -Wm n-1} , the amount of change dTm = Tm ⁿ -Tm ^{n- 1} from the thickness Tm of the slab, respectively .

Next, a correction value calculation of the following equation (1) is performed using the above change amount.

Correction value = α (dVc × Wm × Tm) + β
(Vc × dWm × Tm) + γ (Vc × Wm × dTm) where α is a casting speed correction coefficient, β is a slab width correction coefficient,
γ is a correction coefficient of the slab thickness, is set in the range of 0 to 1, and the initial value is 1.

In FIG. 1, for the sake of simplicity, the calculation elements for each change amount are shown outside the correction value calculation unit 14, but the calculation for each change amount is performed within the correction value calculation unit 14. Will be In addition, when a mold width changing device or a mold thickness changing device is not provided, the above formula (1) is satisfied by using preset values of the width Wm and the thickness Tm.

The correction value obtained by the above calculation is added to the output of the second control unit 23, that is, the molten steel injection amount command value by the adder 15, so that the amount of molten steel injected from the ladle 20 to the tundish 30 is added. Is corrected.

[0022]

As described above, according to the present invention, the weight of molten steel in a tundish can be stabilized by performing feedforward control of process disturbance in addition to conventional PID control. Then, since the weight of the molten steel in the tundish is stabilized, the flow coefficient of the stopper for adjusting the amount of molten steel in the tundish is also stabilized, and the accuracy of controlling the level of the molten metal in the mold can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a tundish weight control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional tundish weight control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 1st detector 12 2nd detector 13 3rd detector 14 Correction value calculation part 15 Adder 20 Ladle 21 Molten steel injection amount adjuster 22 1st control device 23 2nd control device 30 Tundish 31 Weight detector 40 Mold

Claims (2)

[Claims] 1. An adjusting device for adjusting an injection amount of molten steel from a ladle to a tundish, and a first device for controlling the adjusting device.
And the detected value from the tundish weight detector and the target value are compared, and based on the comparison result, the molten steel injection amount command value from the ladle to the tundish is output to the first control device. A weight control device for a tundish for a continuous casting machine having a second control device, wherein a change in a factor that changes the amount of molten steel poured from the tundish into the mold in a process after the molding is detected, and A weight control device for a tundish for a continuous casting machine, comprising a feedforward control system for correcting the amount of molten steel injected into a tundish. 2. The weight control device according to claim 1, wherein
The feedforward control system comprises: a first detector for detecting a casting speed of a mold; a second detector for detecting a width of a slab during casting; and detecting a thickness of a slab during casting. And a correction value calculation for the molten steel injection amount command value from the detection values from the first to third detectors, and adds the calculation result to the output of the first control device. A weight control device for a tundish for a continuous casting machine, comprising a calculating means.