JPH05169205A - Method for controlling casting velocity in twin roll type continuous caster - Google Patents

Abstract

PURPOSE:To quickly stabilize casting velocity and to continue the stable condition in high accuracy. CONSTITUTION:Until the casting velocity of a cast slab by a twin roll type continuous caster 1 stabilizes, a tundish wt. preset value preset with a tundish wt. setter 6a is inputted to a tundish wt. adjuster 6 outputting a tundish wt. adjusting signal to a hydraulic servo 7, and the tundish wt. adjusting signal based on the difference between the preset value and the tundish wt. detected by a load cell L is outputted. After the casting velocity stabilizes, by arranging a casting velocity adjuster 8 outputted after PIO-operating the pressure difference between the aimed casting velocity V and the detected actual casting velocity (v) with a motor revolutional detector 5a for driving the twin roll type continuous caster 1, the casting velocity can quickly be stabilized since the casting start at early time and further, as the molten steel is poured into the twin roll type continuous caster 1 from the tundish 2 based on the casting velocity, the stable casting velocity can be kept.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a casting speed control method for an overflow pouring type twin roll type continuous casting machine, and more particularly, to control a pouring amount from a ladle to a tundish based on the casting speed. The present invention relates to a casting speed control method for a twin roll type continuous casting machine.

[0002]

2. Description of the Related Art As is well known, a twin roll type continuous casting machine (hereinafter referred to as a continuous casting machine) is supplied between two parallel casting rolls and weir plates respectively arranged on both end sides thereof. A plate member (hereinafter, referred to as a slab) having a thickness corresponding to the interval between the casting rolls and a width corresponding to the length is continuously cast from the molten metal by synchronously rotating the casting rolls.

An outline of a conventional casting speed control method for a typical continuous casting machine will be described below with reference to FIG. 5 of the casting speed control system diagram.
Is a continuous casting machine composed of casting rolls 1a and 1b arranged in parallel, and the continuous casting machine 1 is driven by a motor M whose rotation is controlled by a motor controller 2. The continuous casting machine 1 is configured such that the molten steel is poured from the tundish 2 into which the molten metal is poured by adjusting the opening degree of the molten steel discharge port by raising and lowering the stopper 3a from the ladle 3.

By the way, in order to stabilize the casting quality of the slab by such a continuous casting machine 1, it is extremely important to stabilize the casting speed to a predetermined value, so that the required casting speed V can be obtained. Casting speed V = αF, molten metal amount F
= ΒW (where W is the weight of molten steel in the tundish, and α and β are constants uniquely determined from machine specifications), and the weight W of molten steel in the tundish is obtained in advance. The molten steel weight W is set as a set value, and the set value set by the weight setter 6a is input to the tundish weight controller 6 described later to maintain the molten steel weight W in the tundish 2.

More specifically, while receiving a weight detection signal from the load cell L for measuring the weight of the tundish 2 in which molten steel is being poured, the weight detection signal value and the weight setting set by the weight setting device 6a are received. By comparing the value with the value, the hydraulic servo 7 is operated to control the opening and closing of the molten steel discharge port of the ladle 3 by the stopper operating cylinder 4 to stop and open the stopper 3a, and the molten steel in the ladle 3 is poured into the tundish 2 and then the tundish. While keeping the molten steel weight W in 2 constant and maintaining the overflow interface at a predetermined height,
Molten steel is poured between the casting rolls 1a and 1b of the continuous casting machine 1 to stabilize the casting speed V at a predetermined speed, and only the height of the molten steel overflow interface in the tundish 2 determines the pouring amount. It is an element.

Of course, as is well understood from the above description, it is preferable to directly measure the height of the molten steel overflow interface, but an excellent direct measurement method is probable because the interface is wavy. Therefore, the weight W of molten steel in the tundish 2 must be substituted for the height of the overflow interface.

[0007]

By the way, as is well understood from the above description, the most important casting condition is the casting speed V. That is, in the continuous casting machine, the molten metal is solidified by contact with the casting rolls, and the solidified shell is cast as a slab having a thickness based on the distance between the two casting rolls. The level and the speed of rotation of the casting roll must be synchronized.

For example, if the molten metal level is too high compared to the rotation speed of the casting rolls, the shell becomes too thick, and since the continuous casting machine does not have the rolling ability, the shell becomes too thick, resulting in continuous casting due to overload. The machine went down,
The slab cannot be cast. On the other hand, conversely, if the molten metal level is too low compared to the rotation speed of the casting roll, the unsolidified portion remains even at the most adjacent position of the casting roll, and the shell of the shell breaks due to reheat and breakout occurs. ..

Therefore, although the molten metal level in the continuous casting machine 1 must be controlled to be kept constant in accordance with the casting speed V, a difference between the stable casting speed v and the required casting speed V is obtained. The operator determines that the molten steel weight W in the tundish having a larger capacity than that of the continuous casting machine 1 is given as a set value each time, and the molten steel is poured into the continuous casting machine 1.

Further, since the tundish has a large capacity, it is not possible to quickly adjust the pouring of molten steel, which is very troublesome. In addition, the height of the overflow interface changes depending on the molten steel temperature. In addition, the expected casting speed cannot be obtained due to the weight change of the tundish due to the consumption of refractory bricks, etc., so it takes a long time to reach the target casting speed. Inevitably, there was also a problem to be solved that the yield of cast slabs was reduced.

Therefore, an object of the present invention is to provide a casting speed control method for a continuous casting machine which can reliably maintain a target casting speed by automatic control after it is quickly stabilized at a predetermined casting speed. is there.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and therefore, in order to solve the above problems, a casting speed control method for a continuous casting machine according to claim 1 of the present invention. The feature of the main means adopted by is that the molten metal in the ladle is supplied to the tundish, and the molten metal is poured between the two casting rolls rotating from the tundish to continuously cast slabs. In the casting speed control method of the continuous casting machine to compare the casting speed obtained by detecting the rotation speed of the casting roll and the preset target casting speed,
The deviation of the casting speed obtained by this comparison is PID-calculated to obtain a weight control value, the weight control value is compared with the detected tundish weight, and based on the deviation of the tundish weight obtained by this comparison. It is where the amount of molten metal supplied from the ladle to the tundish is automatically adjusted.

The main means adopted by the casting speed control method for a continuous casting machine according to claim 2 of the present invention is that the molten metal in the ladle is supplied to the tundish and rotated from the tundish. In a casting speed control method of a continuous casting machine in which molten metal is poured between two casting rolls to continuously cast a slab, a preset target tundish is set until the casting speed becomes stable immediately after the start of casting. The weight is compared with the detected tundish weight, and the amount of molten metal supplied from the ladle to the tundish is manually adjusted based on the deviation of the tundish weight obtained from this comparison, and the casting speed is stable immediately after the start of casting. After that, the casting speed obtained by detecting the rotation speed of the casting roll is compared with a preset target casting speed, and the deviation of the casting speed obtained by this comparison is compared. PID is calculated to obtain a weight control value, the weight control value is compared with the detected tundish weight, and the amount of molten metal supplied from the ladle to the tundish is based on the deviation of the tundish weight obtained by this comparison. Is to adjust automatically.

The main means adopted by the casting speed control method for a continuous casting machine according to claim 3 of the present invention is that the molten metal in the ladle is supplied to a tundish and rotated from the tundish. In the casting speed control method of the twin roll type continuous casting machine in which the molten metal is poured between the two casting rolls to continuously cast the slab, it is preset until the casting speed is stable immediately after the start of casting. The target tundish weight was compared with the detected tundish weight, and the amount of molten metal supplied from the ladle to the tundish was manually adjusted based on the deviation of the tundish weight obtained by this comparison. After the casting speed became stable, the number of rotations of the casting roll was changed so that the molten metal level in the twin roll type continuous casting machine became constant, and the changed casting roll was changed. When a speed deviation occurs between the actual casting speed and the target casting speed based on the rotation speed of the reel, the target tundish weight is changed in proportion to the speed deviation to change the pouring amount to the twin roll type continuous casting machine. By doing so, the molten metal level in the twin roll type continuous casting machine is automatically adjusted.

[0015]

According to the casting speed control method for the continuous casting machine according to the first aspect of the present invention, the PID calculation of the deviation between the casting speed obtained from the detected rotation speed of the casting roll and the preset target casting speed is performed. The weight control value is calculated,
Since the amount of molten metal supplied from the ladle to the tundish is adjusted based on the deviation between the weight control value and the detected tundish weight, the molten metal is supplied from the tundish to the continuous casting machine based on the casting speed.

According to the casting speed control method for the continuous casting machine of the second aspect of the present invention, the tundish detected as the preset target tundish weight is detected before the casting speed is stabilized immediately after the start of casting. The weight is compared, the amount of molten metal supplied to the tundish from the ladle is adjusted based on the deviation of the tundish weight obtained by this comparison, and after the casting speed immediately after the start of casting is stabilized, As in the case of 1, the amount of molten metal supplied from the ladle to the tundish is adjusted.

Further, according to the casting speed control method of the continuous casting machine according to the third aspect of the present invention, the number of revolutions of the casting roll is changed according to the level of the molten metal in the continuous casting machine. When the level is maintained constant and a speed deviation occurs between the actual casting speed and the target casting speed based on the changed number of revolutions of the casting roll, the target tundish weight is changed according to this speed deviation and the tundish has a predetermined value. Since the amount of molten metal changed from the ladle is poured to pour a certain amount of molten metal, the molten metal is injected from the tundish into the continuous casting machine in order to eliminate the speed deviation, and thereby the molten metal level of the continuous casting machine is increased. Although it gradually changes, the rotational speed of the casting roll is automatically adjusted to the target casting speed in accordance with this change.

[0018]

Embodiments of the present invention will be described below with reference to the casting speed control system diagram of a continuous casting machine and the control flow diagram of FIG. Those having the same reference numerals will be described. However, this embodiment is different in that a system for interlocking the tundish weight controller of the casting speed control system and the motor controller for controlling the motor for driving the continuous casting machine is additionally provided in this embodiment, so that the difference is made. I will only explain the points.

That is, the system shown in the alternate long and short dash line is the same as the control system of the conventional continuous casting machine. In the present embodiment, in the case of manual operation, the tundish weight set value input from the tundish weight setting device 6a is output to the tundish weight controller 6 by switching the switch S as shown in FIG. In the case of automatic, the detected rotation speed v of the motor M detected by the input motor rotation detector 5a
And a speed deviation from the target casting speed V set and input by the target casting speed setter 8a is PID-calculated and the PID calculation result is output to the tundish weight controller 6 by reverse switching of the switch S. A controller 8 is added.

Therefore, an output based on the comparison between the PID calculation result and the tundish weight detected by the load cell L is input from the tundish weight controller 6 to the hydraulic servo 7 and operated by the operation of the hydraulic servo 7. The stopper operating cylinder 4 operates the stopper 3a.

Next, the control procedure from when the molten metal in the tundish 2 is 0 until the casting speed is stable and the stable casting speed is maintained will be described with reference to FIG. First, in the _1-1 step, at the start of casting, the output terminal of the casting speed controller 8 is connected to the input terminal of the tundish weight setting device 6a by manually switching the switch S, and the tundish weight setting device 6a is used. The set value of the set tundish weight is input to the tundish weight controller 6.

[0022] In the first _-2 step, the control output is outputted from the tundish weight adjusting meter 6 to the hydraulic servo 7 M
The stopper 3a is raised according to V, and molten steel is poured from the ladle 3 into the tundish 2.

[0023] In the first _-3 step, the cast state by a continuous casting machine 1 is confirmed whether or not stabilized, resetting the tundish weight setting the set value of the first _-1 step is performed in the case of No Then, the steps 1 to ₂ are repeated, and in the case of Yes, the output terminal of the casting speed controller 8 and the input terminal of the tundish weight setting device 6a are switched by the switch S to detect the casting speed. It is connected to the differential pressure output side between the target value and the target casting speed value set by the target casting speed setting device 8a, and the mode is switched to the next automatic mode.

In the 2 _-1 step, the target casting speed V is input to the casting speed controller 8 by the target casting speed setting device 8a, and the process proceeds to the 2 _-2 step.

In step _2-2 , the rotation speed of the motor M detected by the motor rotation detector 5a, that is, the rotation speed of the casting roller 1b, that is, the actual casting speed v is input to the casting speed controller 8.

The second in _-3 step, the pressure difference (V-v = Δv) weight control is input to the tundish weight adjusting meter 6 from the output M of the target casting speed V and the actual casting speed v
V is MV = 100 / P [1 + 1 / T ₁ S + T _D S / (1
+ T _D / m) S] × Δv
Then, the MV obtained by this calculation is input to the tundish weight controller 6 and the process proceeds to the 2 _-4 step. The letter P used in the above equation is the proportional band,
T ₁ is the integration time, S is the operator, T _D is the derivative time, and m is the derivative gain.

In a second _-4 step and tundish weight adjusting meter 6 outputs a control output by comparing the tundish weight measurement value detected by the MV and the load cell L to the hydraulic servo 7, the following second _-1 ~ Repeat _steps 2-4.

As described above, the stopper 3a is opened and closed by the stopper operating cylinder 4 operated by the hydraulic servo 7 controlled based on the actual casting speed. Therefore, compared with the conventional control method based on the tundish weight. Casting of slabs can be performed with higher accuracy, and as mentioned above, since the manual mode is controlled before the casting state stabilizes, there is no disturbance due to overshooting as in the past, so it is faster than in the past. Since it is stable, the defective rate of the slab is also reduced.

Next, another embodiment according to the present invention will be described with reference to FIG. 3 of a casting speed control system diagram of a continuous casting machine, the rotation speed of a casting roll, the molten metal level in the tundish, and the molten metal level in the continuous casting machine. With reference to FIG. 4 of the situation explanatory diagram, the same components and components having the same functions as those of the conventional example will be described with the same reference numerals. However, like this embodiment, this embodiment will be described only with respect to the points different from the conventional one.

That is, the system shown in the alternate long and short dash line is almost the same as the control system of the continuous casting machine according to the conventional example. In this example,
The tundish tare setter 6b for setting the tare weight of the tundish 2 is input to the circuit communicating from the load cell L to the tundish weight controller 6, and the continuous casting machine 1 further has a level of molten metal injected therein. And a motor controller 5 based on the output signal from the molten metal level controller 10 and the molten metal level detector 9 for detecting the molten metal level signal. Tundish Weight Controller 6
In addition, a casting speed controller 8 which outputs a control signal respectively and has a structure described later is added.

The casting speed controller 8 comprises one control device controlled by software, has a casting speed setting function and a ratio calculation function, and more specifically has a target casting speed setting section 8a. One of the output signals from this point is output via the first ratio calculator 8b, this output is compared with the molten metal detection level signal from the molten metal level detector 9, and the molten metal level deviation is the molten metal level controller 10 Entered in.

Then, the output signal from the molten metal level controller 10 is compared with other output signals output from the target casting speed setting unit 8a, and the deviation thereof is input to the motor controller 5 to change the rotation of the motor M. Therefore, the molten metal level in the continuous casting machine 1 is maintained within a predetermined range. As the molten metal level detector 9, for example, an image processing device is used.

Further, the other output signal is compared with the rotation detection value from the motor rotation detector 5a, and the deviation thereof is output via the second ratio calculating section 8c. Then, this output is compared with the input signal of the molten metal amount setting device 6a in the tundish for setting the molten metal amount in the tundish, and the molten metal amount deviation is input to the tundish weight controller 6, and this molten metal amount deviation and the above-mentioned The deviation between the detected value from the load cell L and the set value of the tare of the tundish 2 by the tundish tare setter 6b, that is, the molten steel weight, is compared, and the comparison result is input to the hydraulic pressure servo 7 for controlling the opening / closing of the stopper 3a. Is configured.

Therefore, when the molten metal level detector 9 detects the molten metal level in the continuous casting machine 1 and a molten metal level deviation occurs between this detected value and the set value by the target casting speed setting unit 8a, the deviation is detected. Based on the second ratio calculation unit 8c
The tundish weight adjuster 6 is actuated in accordance with the deviation in the weight of the molten metal in the tundish 2, and the opening and closing of the stopper 3a is controlled by this so that the molten metal is poured from the ladle 3 into the tundish 2. Then, based on this, the injection amount from the tundish 2 to the continuous casting machine 1 changes due to overflow, and accordingly, the motor controller 5 causes the motor M to drive the casting roll 1 via the motor M.
Since the rotation speeds of a and 1b are changed, the molten metal level in the continuous casting machine 1 is continuously maintained at a predetermined height. That is, the actual casting speed continues to be maintained at the target casting speed.

In this case, since the amount of molten metal in the tundish 2 is much larger than the amount of molten metal in the continuous casting machine 1, for example, the fluctuation cycle due to the disturbance of the molten metal in the continuous casting machine 1 is 1 to 1.
Although it takes about 2 seconds, the fluctuation period due to the disturbance of the molten metal in the tundish 2 is as long as about 20 to 30 seconds, but as shown in FIG. In addition, the molten metal level in the continuous casting machine 1 continues to be maintained constant after the stable state is reached.

[0036]

As described in detail above, the first aspect of the present invention
According to the casting speed control method of the present invention, the weight control value is obtained by the PID calculation of the deviation between the casting speed obtained from the detected rotation speed of the casting roll and the preset target casting speed, and the weight control value Since the amount of molten metal supplied from the ladle to the tundish is automatically adjusted based on the detected deviation of the tundish weight, the molten metal supplied is based on the casting speed, and the stable casting speed v As a result of eliminating the need for the operator to judge the difference from the required casting speed V, it is extremely easy to carry out continuous casting with stable DT.

According to the casting speed control method of the second aspect of the present invention, after the casting speed is stabilized, the amount of molten metal supplied from the ladle to the tundish is automatically adjusted as in the first aspect. Until the casting speed becomes stable immediately after the start of casting, the preset target tundish weight and the detected tundish weight are compared, and the ladle to tundish is changed based on the deviation of the tundish weight obtained by this comparison. As the amount of molten metal supplied is adjusted manually, overshooting is eliminated as in the past,
It becomes possible to stabilize the casting speed more quickly, and it is possible to reduce the production amount of slabs of unstable quality.

Further, according to the casting speed control method of the third aspect of the present invention, the number of revolutions of the casting roll is changed according to the molten metal level in the continuous casting machine, so that the molten metal level in the continuous casting machine is kept constant. If there is a speed deviation between the actual casting speed and the target casting speed based on the maintained and changed casting roll speed, the target tundish weight is changed according to this speed deviation and a predetermined amount of molten metal is added to the tundish. The amount of molten metal changed from the ladle is poured to pour the molten metal, and the molten metal is injected from the tundish into the continuous casting machine to eliminate the speed deviation, which causes the molten metal level of the continuous casting machine to gradually change. In response to this change, the rotation speed of the casting roll is automatically adjusted to the target casting speed, so there is no risk of the continuous casting machine running out of operation or breakout, and high efficiency is achieved. It is possible to cast the excellent cast finished products of quality.

[Brief description of drawings]

FIG. 1 is a casting speed control system diagram of a continuous casting machine according to an embodiment of the present invention.

FIG. 2 is a flow chart of casting speed control of the continuous casting machine according to the embodiment of the present invention.

FIG. 3 is a casting speed control system diagram of a continuous casting machine according to another embodiment of the present invention.

FIG. 4 is a control status explanatory diagram of a rotation speed of a casting roll, a molten metal level in a tundish, and a molten metal level in a continuous casting machine of a continuous casting machine according to another embodiment of the present invention.

FIG. 5 is a casting speed control system diagram of a continuous casting machine according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Continuous casting machine, 1a, 1b ... Casting roll, 2 ... Tundish, 3 ... Ladle, 3a ... Stopper, 4 ... Stopper operating cylinder, 4a ... Pressure detector, 5 ... Motor controller, 5a ... Motor rotation detector , 6 ... Tundish weight controller, 6a ... Tundish weight setting device or amount of molten metal in tundish, 6b ... Tundish tare setting device, 7 ... Hydraulic servo, 8 ... Casting speed controller or casting speed controller, 8a ... Target casting speed setting device or target casting speed setting unit, 8b ... First ratio calculating unit, 8c ... Second ratio calculating unit, 9 ... Molten level detector, 10 ... Molten level controller, L ... Load cell, M ... Motor, S ... switch.

Claims (3)

[Claims] 1. A twin roll type continuous casting machine for supplying molten metal in a ladle to a tundish and pouring the molten metal between two casting rolls rotating from the tundish to continuously cast a slab. In the casting speed control method, the casting speed obtained by detecting the rotation speed of the casting roll is compared with a preset target casting speed, and the deviation of the casting speed obtained by this comparison is calculated by PID to obtain a weight control value. It is characterized by comparing this weight control value with the detected tundish weight, and automatically adjusting the amount of molten metal supplied from the ladle to the tundish based on the deviation of the tundish weight obtained by this comparison. Casting speed control method for twin roll continuous casting machine. 2. A twin roll type continuous casting machine for supplying molten metal in a ladle to a tundish and pouring the molten metal between two casting rolls rotating from the tundish to continuously cast a slab. In the casting speed control method of, until the casting speed immediately after the start of casting is stable, the preset tundish weight is compared with the detected tundish weight, and based on the deviation of the tundish weight obtained by this comparison. While manually adjusting the amount of molten metal supplied from the ladle to the tundish, after the casting speed is stable immediately after the start of casting, the casting speed obtained by detecting the rotation speed of the casting roll and the preset target casting speed are The weight control value is calculated by PID calculation of the deviation of the casting speed obtained by this comparison, and this weight control value is compared with the detected tundish weight. A method for controlling a casting speed of a twin roll type continuous casting machine, comprising automatically adjusting the amount of molten metal supplied from the ladle to the tundish based on the deviation of the tundish weight obtained by this comparison. 3. A twin roll type continuous casting machine for supplying molten metal in a ladle to a tundish and pouring the molten metal between two casting rolls rotating from the tundish to continuously cast a slab. In the casting speed control method of, until the casting speed immediately after the start of casting is stable, the preset tundish weight is compared with the detected tundish weight, and based on the deviation of the tundish weight obtained by this comparison. The amount of molten metal supplied from the ladle to the tundish is manually adjusted, and after the casting speed is stabilized immediately after the start of casting, the rotation speed of the casting roll is adjusted so that the molten metal level in the twin roll type continuous casting machine becomes constant. Change
When a speed deviation occurs between the actual casting speed and the target casting speed based on the changed number of rotations of the casting roll, the target tundish to change the pouring amount to the twin roll type continuous casting machine in proportion to the speed deviation. By changing the weight,
A method for controlling a casting speed of a twin roll type continuous casting machine, comprising automatically adjusting a molten metal level in the twin roll type continuous casting machine.