JPS6117348A - Control device for molten metal level of casting mold - Google Patents

Abstract

PURPOSE:To control the molten metal level with high accuracy without receiving the influence of the sectional area of a casting mold by adjusting the pouring rate of a molten steel to the casting mold to compensate the fluctuation in a drawing speed by a control system for the pouring rate for compensation. CONSTITUTION:The drawing speed is detected by a drawing speed detector 41 and the detected drawing speed signal is fed via a signal filter circuit 42 and a signal change-over circuit 43 to a stopper controller 44. The operation of the controller 44 is delayed by a delay circuit 45. The controller 44 determines the deviation between the detected drawing speed signal and set drawing speed signal after the drawing speed is stabilized and delivers such a pouring control signal which makes zero the deviation. The molten metal is poured into the casting mold 3 at the rate at which the change of the drawing speed is compensated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] Tsumei Mizumoto relates to continuous casting equipment, and particularly to improvements in a mold level control device for controlling the level of molten metal in a mold.

[Technical background of the invention]

In continuous casting equipment, controlling the level fluctuations in the mold to a minimum keeps the quality of the slabs produced by the continuous casting machine (hereinafter referred to as the continuous casting machine), especially the surface quality of the slabs, to a good condition. This is extremely important in maintaining the In addition, stable and automatic control of the scene level can reduce the work labor of the casting worker and save labor. Therefore, various devices for controlling the scene level have been developed.

For example, molten steel injection amount control device, drawing ff1l! I control device and injection/withdrawal date switching device.

FIG. 2 is a configuration diagram of the molten steel injection amount control device.

In Figure 2, 1 is a dandysh, 2 is an immersion nozzle, and 3
is a mold, in which the molten steel in the dandysh 1 is injected into the mold 3 through the immersion nozzle 2;
A predetermined slab 4 is pulled out. Therefore, to control the hot water level 5 in the mold 3, the hot water level 5 is detected by a level sensor 6 provided in the mold 3, and this level detection signal is sent to the adjustment g17. This controller 7 determines the deviation between the level detection signal and the setting signal, and outputs a control signal to the hydraulic device 8 to make this deviation zero. This hydraulic device 8 operates a cylinder 9 to control the opening degree of the immersion nozzle 2 using a stopper 10 . As a result, the scene level 5 is controlled to a constant level. Note that the opening degree of the immersion nozzle 2 may be adjusted by operating a sliding nozzle installed in the immersion nozzle 2.

Further, FIG. 3 is a configuration diagram of the extraction amount control device.

This device sends a level detection signal from a level sensor 6 to a controller 11, and sends a control signal output from the controller 11 to a speed controller 12. And this speed control device 1
2 controls the rotational speed of the pinch roll 13 in contact with the slab 4 according to the input control signal. As a result, the drawing speed of the slab 4 is controlled and the molten metal level 5 becomes constant 7.

Furthermore, the injection/withdrawal amount switching control device is configured to mutually back up the molten steel injection amount control device and the withdrawal amount control device described above depending on the control state. When the opening degree of the nozzle is outside the limit value, the control switches to the amount of extraction.

[Problems with background technology]

However, the above device has the following problems.

That is, ■ The molten steel injection amount control device can obtain sufficient control accuracy when applied to a continuous caster for slabs and large cross-sectional area blooms. However, when applied to a continuous bloom or billet caster with a small cross-sectional area, the change in the opening of the drive device that adjusts the opening of the immersion nozzle 2 of the stopper etc. is a fraction of that of a continuous slab caster. It is necessary to make it as small as possible. For this reason, minute play in the drive device affects the opening setting accuracy, and the amount of scene level variation may be approximately several times the variation m in the shape of the slab. Therefore, sufficient stability for manufacturing slabs etc. could not be obtained.

■ The drawing control device has the advantage that the injection amount control device is not affected by the cross-sectional area of the mold. However, since the injection amount from the immersion nozzle 2 changes due to nozzle clogging or melting damage, the casting speed changes during control. As a result, the level of the molten metal cannot be controlled at a constant level, resulting in fluctuations in the solidified state of the slab in the mold 3 and fluctuations in the specific water level in the secondary cooling zone. As a result, the quality of the slab 4 tends to deteriorate.

(2) The injection/withdrawal amount switching control device has the advantage of expanding the controllable range because when one control method becomes uncontrollable, the other control method provides backup. However, since only one of the control methods is used during control, the problems of each device described above remain unsolved.

(Object of the invention) The present invention has been made based on the above circumstances, and its purpose is to improve the accuracy of the scene level regardless of the cross-sectional area of the slab and without being affected by changes in the amount of molten steel injected. It is an object of the present invention to provide a mold wet surface level control device that can highly control the wet surface level of a mold.

[Summary of the invention]

The present invention outputs a drawing speed signal by a drawing control means according to the scene level in the mold, adjusts the drawing speed of the cast material to be drawn from the mold, and changes in the drawing speed of the casting material at this time. is compensated for by adjusting the amount of molten steel injected into the mold, and further, the amount of molten steel injected is adjusted in response to an independent operation mode selection signal from the operating end to maintain the level of the molten steel. It is a level control device.

[Embodiments of the invention]

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of a mold molten metal level control device according to the present invention will be described with reference to FIG. FIG. 7 is a block diagram of a mold level control device.

Note that the same parts as in FIGS. 2 and 3 are given the same reference numerals. In other words, 1 is a dandyish, 2 is an immersion nozzle, 3 is a mold, 4 is a slab which is a cast object, 5 is a scene level, 6 is a level sensor, 8 is a hydraulic system,
9 is a cylinder, 1o is a stopper, 12 is a speed control device, and 13 is a pinch roll.

Now, 20 is a scene main control device, and this hot water level main control device 20 adjusts the drawing speed of the slab 4 to reach the scene level 5.
A drawing amount control system 3o keeps the amount of molten steel injected into the mold 3 constant. It has a main injection agricultural control system (hereinafter referred to as a compensation injection amount control system) 40 that adjusts and compensates. In addition, extraction 1I
The operation by the i11 control system 30 and the compensation injection amount control system 4o is referred to as cooperative control. Furthermore, this device 120 includes an auxiliary injection amount control system (hereinafter referred to as an independent injection amount control system) 50 that adjusts the amount of molten steel injected into the mold 3 according to the molten metal level and independently controls the scene level. It is provided. Note that this individual injection amount control system 5o operates particularly during the period from the start of casting to the separation of the dummy bar.

That is, from the start of casting to the separation of the dummy bar, the withdrawal amount control system 3o cannot be applied in order to increase the casting speed. And the device! In 20, the extraction amount control system 3
0 and the single injection amount control system 50 without bumping.

Specifically, the withdrawal amount control system 30 receives the level sensor 6 and the level detection signal from the level sensor 6, calculates and determines the deviation between this level detection signal and the level setting No. 1g, and calculates this deviation. A drawing speed regulator 31 that performs PID calculation such as zero and outputs a drawing speed control signal.
is provided in the drawing speed control signal sending line of this drawing speed controller 31, and normally sends the drawing speed control signal from the controller 31 to the speed control device 12, and gradually reduces the drawing speed control signal when switching between automatic and manual switching. and disconnect the extraction speed control signal sending line. In other words, it is comprised of a deviation limiting circuit 32 having a bumpless switching function, a speed control device 12, and a pinch roll 13.

On the other hand, the compensation injection amount control system 40 includes a drawing speed detector 4 that detects the drawing speed of the slab 4 from the rotational speed of the pinch rolls 13.
1, and a signal filter circuit 4 that performs signal processing such as nozzle removal and averaging of the extraction speed detection signal from this detector 41.
2, and the signal switching circuit 43 from this signal filter circuit 42
A stopper that receives a drawing speed detection signal passing through the stopper, calculates the deviation between this detection signal and the drawing speed setting signal, performs PID calculation processing to make this deviation zero, and outputs an injection control signal to the hydraulic device 8. It consists of 44 controllers. Reference numeral 45 denotes a delay circuit, which delays the start of operation of the stopper adjuster 44 due to the following circumstances. That is, the stopper 10 is locked when the automatic operation of the cooperative control is activated, but since there is a change in the scene level just before this activation, the withdrawal speed is temporarily changed. Therefore, the stopper adjuster 44 is made to operate after the drawing speed is stabilized.

The independent injection amount control system 50 includes a level sensor 6, a stopper controller 44, a hydraulic device 8, a cylinder 9, and a rib 10.
It is composed of.

The signal switching circuit 43 has a function of switching the process signal (level detection signal and withdrawal speed detection signal) to the stopper controller 44, and outputs the withdrawal speed detection signal to the coordination 11 Jill poem. I! Send 1 section to 44 in total,
Also, when controlling the individual injection amount, the level detection signal can be set to a stopper.
This is what I send to Setkei 44. 60 is an operation panel, and this operation panel 60 includes a selection mode switch (extraction operation mode, independent operation mode) for operating the extraction amount control system 30, the individual injection amount control system 50, and the cooperative control individually, and Automatic-
A manual changeover switch is provided. 61 is a switching timing circuit, which is especially used for the independent injection amount control system 5.
When an independent operation mode selection signal is sent from the operating beard 60 to switch from the independent operation mode of 0 to the cooperative control operation, or conversely from the cooperative control operation to the operation of the independent injection amount control system 50, scene level 5 is allowed. It detects that it has entered the range by receiving a signal from the level sensor 6, etc., and upon this detection, sends a cooperative control command and an individual injection amount control command to the sequence control circuit 62, and also indicates switching of these controls. The signal is sent to the deviation control circuit 32, signal switching circuit 43, etc.

The sequence control circuit 62 controls the operation of each circuit of the hot water level main control device 20 according to a predetermined sequence of scene level control.

Next, the operation of the apparatus configured as described above will be explained. When the molten steel of the dandysh 1 is injected into the mold 3 through the immersion nozzle 2, the molten steel solidifies and becomes a slab 4 from the mold 3. A dummy bar is connected to the tip of the slab 4 and then pulled out. The slab 4 at the start of this casting is drawn out while the casting speed is increased.

When the dummy bar reaches the pinch roll 13, the dummy bar is separated. Until the dummy bar is separated, the pulling speed varies significantly due to dummy bar slippage, etc.

Therefore, at the start of casting, the sequence control circuit 62
The individual injection amount control system 50 operates independently according to the command.

That is, the hot water level 5 is detected by the level sensor 6, and this level detection signal is sent to the stopper controller 44 via the signal switching circuit 43. The valve controller 44 determines the deviation between the level detection signal and the level setting signal, and sends an injection control signal to the hydraulic system 8 that sets this deviation to zero. As a result, the cylinder 9 operates, the opening degree of the immersion nozzle 2 is adjusted, and the amount of molten steel injected is controlled.

Then, when the dummy bar is disconnected and the cooperative control operation (withdrawal operation mode) is selected on the operation panel 60, the switching timing circuit 61 detects that the hot water level 5 falls within the permissible range. When this detection is made, the switching timing circuit 6
1, a cooperative control command is issued to the sequence control circuit 62, and the fact of switching is sent to the deviation limiting circuit 32, signal switching circuit 43, etc. At this time, the position of the stopper 10 is temporarily determined by the sequence control circuit 62.

Then, the level detection signal output from the level sensor 6 is sent to the drawing speed detector 31 via the signal switching circuit 43. This drawing speed controller 31 determines the deviation between the drawing speed setting signal and the level detection signal, calculates and obtains a drawing speed control signal that makes this deviation zero, and controls the speed using this signal via the deviation limiting circuit 32. The data is sent to the device 12. As a result, the rotation speed of the pinch roll 13 is adjusted and the slab 4
The withdrawal speed is controlled. As a result, the hot water level 5 is controlled to be constant.

However, the drawing speed may fluctuate due to clogging, erosion, etc. of the immersion nozzle 2. Therefore, the compensation injection amount control system 40 for compensating the drawing speed operates simultaneously with the above-mentioned drawing m control system 30. That is, the drawing speed is detected by the drawing speed detector 41, and this drawing speed detection signal is sent to the stopper controller 44 via the signal filter circuit 42 and the signal switching circuit 43. At this time, the start of the operation of the stopper controller 44 is delayed by the delay circuit 45. Then, after the drawing speed becomes stable, the valve controller 44 determines the deviation between the drawing speed detection signal and the drawing speed setting signal, and sends out an injection control signal that makes this deviation zero. As a result, molten steel of ω is injected into the mold 3 to compensate for the change in the drawing speed.

In the above manner, the scene level 5 is controlled to be constant.

Next, the operation when switching from automatic mode to manual mode will be explained. When a switching operation from automatic mode to manual mode is performed by operation WA60, a manual switching command is issued from sequence control circuit 62 to each circuit via switching timing circuit 61.

Therefore, if there is a deviation between the drawing speed detection signal and the drawing speed setting signal and this deviation is reset all at once when switching to the manual mode, the drawing speed will change suddenly. However, the deviation limiting circuit 32 gradually resets (bumps) the drawing speed control signal to the speed control device 12. Therefore, variations in drawing speed are limited.

Further, switching from cooperative control to independent injection amount control is performed as follows. That is, when the operation of the independent operation mode of switching to the independent injection amount control system 50 is performed on the operation panel 60, the switching timing circuit 61 detects that the hot water level 5 has entered the permissible range, and upon this detection, A single injection amount control command is issued to the sequence control circuit 62. At this time, the withdrawal amount control system 30 is disconnected, but the deviation limit circuit 3
2, it does not reset instantly and switches to bumpless mode.

In this way, in the apparatus of the present invention, the extraction amount control system 30
During this control, the injection rate control system 40 controls the flow of molten steel into the mold 3 to compensate for fluctuations in the drawing speed caused by clogging and melting of the immersion nozzle 2. Since the injection m is adjusted to compensate, the advantage of not being affected by the cross-sectional area of the mold for controlling the withdrawal amount is taken advantage of, and even when casting with a mold with a small cross-sectional area, the level 5 can be maintained. Can be controlled with high precision.

Furthermore, fluctuations in the drawing speed due to clogging and melting damage of the submerged nozzle 2, which were drawbacks of drawing amount control, are compensated for by the compensation injection amount control means 40, so fluctuations in the solidification state of the slab in the mold 3, This does not cause fluctuations in the specific water content of the slab 4, and the quality of the slab 4 will not be deteriorated.

Furthermore, it is possible to switch between cooperative control and independent injection amount control depending on the casting state (particularly at the start of casting). Therefore, the molten metal level can be controlled in response to disturbance fluctuations during pouring and fluctuations in operating conditions. Switching between cooperative control and independent injection amount control can also be performed bumplessly, and this switching allows for
There will be no negative impact on the quality of the product.

Further, the provision of the deviation control circuit 32 enables the switching between automatic and manual coordination control to be performed bumplessly, and this switching does not adversely affect the quality of the slab 4.

Further, the hot water level main control device 20 can be easily configured using a general digital controller and can be realized at low cost.

It should be noted that the stopper controller 44 does not operate by continuously receiving the extraction speed detection signal, but may be controlled by, for example, sampling the signal.

Further, the drive device for controlling the opening degree of the immersion nozzle 2 is not limited to the stopper 10.

(Effects of the Invention) According to the present invention, the drawing control means adjusts the drawing speed of the cast material, and the main injection amount control means adjusts the amount of molten steel injected to compensate for fluctuations in the drawing speed during this control, thereby leveling the molten metal level. In addition, it has an auxiliary injection amount control means, and the switching from the drawing m @ Ohira means to the auxiliary injection amount control means is performed bumplessly, so that regardless of the cross-sectional area of the slab, It is possible to provide a mold surface level control device that can control the mold surface level with high precision without being affected by changes in the injection m.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of a mold level control device according to the present invention, Fig. 2 is a block diagram of a conventional erosion injection m control device, and Fig. 3 is a block diagram of a conventional withdrawal amount control device. FIG. 1...Dandish, 2...Immersion, immersion nozzle, 3...
・Mold, 4... Slab, 5... Molten metal level, 6...
Level sensor, 8... Hydraulic system, 9... Cylinder,
10...S1-Tuber-112...Speed control device, 1
3... Pinch roll, 20... Hot water level main control device, 3
0... Drawing amount control system, 31... Drawing speed controller, 3
2... Deviation control circuit, 40... Compensation injection amount control system,
41... Drawing speed detector, 42... Signal filter circuit, 43... Signal switching circuit, 44... Stopper controller, 45... Delay circuit, 50... Independent injection amount control system, 60...Operation panel, 61...Switching timing circuit,
62...Sequence control circuit. Applicant's agent Patent attorney Takehiko Suzue No. 2! ! I Written amendment to the third-cause procedure 1989/2015 Manabu Shiga, Commissioner of the Japan Patent Office 1, Indication of the case Patent application No. 137835/1983 2, Name of the invention Mold water level control device 3, Nagisa incident to be amended Related Patent Applicant (412) Nippon Kokan Co., Ltd. 4, Agent 6, Specification Subject to Amendment 7, Contents of Amendment (1) “Modern Level Fluctuation” in Lines 3 to 5 of Page 5 of the Specification "The amount could not be obtained." should be corrected as follows. In some cases, the measured surface level fluctuation meter measured several times the amount of fluctuation in the slab level. Therefore, sufficient stability for producing bloom billets and the like could not be obtained. (2) “Stopper adjuster 4” on page 9, line 16 of the same book.
4" is corrected to "Stotno 4 adjustment meter 44." (3) In the first line of page 10 of the same book, "Stop horn 4 adjuster 44" is corrected to "Stopper adjuster 44." (4) "Selection mode switch (withdrawal operation mode, independent operation mode)" in lines 14 to 15 of page 10 of the same book is changed to "selection mode switch (withdrawal operation mode, injection amount control mode, cooperative control mode)". correct.

Claims (1)

[Claims] A drawing control means for detecting a level of hot water in a mold in a continuous casting apparatus, and outputting a drawing speed signal of a piece to be cast to be pulled out from the mold in accordance with the level of the hot metal, thereby controlling the speed at which the piece to be cast is pulled out. Then, a variation in the drawing speed of the cast object caused by the control of the drawing control means is detected, and this detection signal is received via a signal switching circuit which is normally set to the drawing operation mode, so that the drawing speed is changed according to the drawing speed variation. a main injection amount control means for outputting a molten steel injection amount control signal to control the amount of molten steel injected into the mold; A bumpless switching means for switching a switching circuit to set the independent operation mode, and a signal switching circuit which is set to the independent operation mode by the bumpless switching means, take in a detection signal of the level of the molten metal in the mold. A mold surface level control device comprising: auxiliary injection amount control means for controlling the amount of molten steel injected into the mold using a molten steel injection amount control signal according to the molten metal level.