JPS63192545A - Continuous casting mold level control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a level control device for molten steel in a mold in a continuous casting process.

[Conventional technology]

A continuous caster is equipment that continuously produces slabs, billets, etc. from molten steel, and as shown in Figure 3, the molten steel is passed through a ladle 31.
and is injected into a mold 33 through a tundish 32. Injected into mold 33.

The molten steel whose surface layer has solidified in the mold 33 is pulled out by pinch rolls 34, and after being completely cooled, it is cut into a predetermined length by a cutter 35 to form a slab 36 and sent to a rolling process.

In this continuous casting process, the level of the molten steel in the mold 33 is generally controlled (hereinafter referred to as mold level control) for the purpose of improving the quality and yield of the slab 36.

Figure 4 shows, for example, the 20th Academic Conference of the Society of Instrument and Control Engineers (
The structure of the conventional mold level control device shown in pages 351 to 352 of the proceedings of the publication (July 29th to 31st, 1988) is shown, and FIG. 5 shows the mold level control device shown in FIG. 4. This is a control block diagram of the device, and in FIGS. 4 and 5, ■ is a target value setting device that determines the target value of the level of molten steel 37 in the mold 33, 2 is a PID controller, 3 is a hydraulic servo valve, and 4 is a control block diagram of the device. 5 is a hydraulic cylinder, 5 is a stopper opening degree detector, 6 is a stopper for adjusting the amount of molten steel 37 injected from the tundish 32 into the mold 33, and 7 is a level detector.

In the mold level control device configured as described above, the mold level y in the mold 33 is detected by the level detector 7, and the detected mold level measurement value y
' is sent to the comparator 8.

The comparator 8 calculates the target value y'r set in the target value setting device 1.
and mold level measurement value y', and sends the level deviation e to the PID controller 2. The PID controller 2 adjusts the opening degree of the stopper 7 (hereinafter referred to as
This is called the stopper opening degree. ) command value U. is calculated, and this stopper opening command value uD is sent to the comparator 9. The comparator 9 compares the stopper opening command value u0 with the stopper opening measurement value U' detected by the stopper opening detector 5, and sends the deviation signal to the hydraulic servo valve 3. The stopper opening degree measurement value U' measured by the degree detector 5 is the stopper opening degree command value U. Hydraulic cylinder 4 is equal to
The stopper opening degree U is adjusted by changing the oil supply amount q supplied to the mold 33 so that the mold level y in the mold 33 always matches the target value yr even if the slab withdrawal speed v fluctuates. is maintained at a certain level.

[Problem that the invention seeks to solve]

During actual casting with a continuous casting machine, the flow rate gain of the stopper 6, which is a characteristic of the object controlled by the mold level control device, is set to 1.
This is due to melting of the stopper and adhesion of alumina.

It fluctuates greatly due to shedding, etc.

On the other hand, in order to obtain the desired control performance in the mold level control device, it is necessary to adjust the control parameters of the PID controller 2 according to the characteristics of the controlled object.

However, in the conventional mold level control device described above, since the control parameter 10 of the PID controller 2 is fixed, the control performance is significantly deteriorated due to a 1 change in the flow rate gain of the stopper 6, and sometimes molten steel overflows from the mold 33. However, there are problems in quality control of slabs or operational problems.

This invention was made to solve this problem, and provides a continuous casting mold level control that can prevent the control performance from deteriorating even if the flow rate gain of the stopper changes during casting. The purpose is to propose a device.

[Means for solving problems]

The continuous casting mold level control device according to the present invention includes a flow rate gain estimating means for estimating a flow rate gain of a molten steel injection amount adjustment stopper using measured values of a mold level, a stopper opening degree, and a slab withdrawal speed; Using the flow rate gain estimate estimated by the estimation means, the following formula is used, where KIO is a positive constant and the correction value u0 of the output u0 of the feedback control means is
′.

[For production]

In this invention, the output of the feedback control system is automatically compensated for changes during casting in the flow rate gain of the stopper that adjusts the amount of molten steel injected into the mold.
Prevent deterioration of control performance.

〔Example〕

FIG. 1 is a control block diagram showing one embodiment of the present invention, and in the figure, numerals 1 to 11 and 33 are exactly the same as those in the conventional example shown in FIG. 12 is a slab withdrawal speed detector for detecting the slab withdrawal speed V; 13 is a slab withdrawal speed detector 12. A flow rate gain estimator inputting signals from the level detector 7 and the stopper opening detector 5, 14 is P
This is a gain compensator that inputs signals from the rDiliJ meter 2 and the flow rate gain estimator 13 and outputs a signal to the comparator 9.

The operation of the continuous casting mold level control device configured as described above will be explained.

The slab withdrawal speed detector 12 detects the slab withdrawal speed V and sends the slab withdrawal speed measurement value V' to the flow rate gain estimator 13. Further, the measured value y' of the mold level of the molten steel in the mold 33 detected by the level detector 7 and the measured value U' of the stopper opening degree detected by the stopper opening degree detector 5 are also sent to the flow rate gain estimator 13.

The flow rate gain estimator 13 is based on the slab withdrawal speed measurement.
, Mold level measurement 4fold y' and stopper opening measurement J
Based on Ju', the estimated flow rate gain value is estimated and sent to the gain compensator 14.

On the other hand, the gain compensator 14 uses the deviation e between the target value y set in the target value setting device 1 and the mold level measurement value y' detected by the level detector 7, and the predetermined control parameter 10. PIDi [stopper opening command value u0 calculated by cylinder needle 2 is also input.

The gain compensator 14 corrects this stopper opening command value u0 based on the estimated flow rate gain value TI according to the following equation (1) to obtain a stopper opening command correction value U. ' is output to the comparator 9. Here, 1° is a positive constant, and a typical value of 1 is used for the stopper flow rate gain.

That is, by correcting the stopper opening degree command value u0 using equation (1), the closed loop characteristics of the control system can be maintained constant despite fluctuations in the flow rate gain of the stopper 6.

Comparator 9 is the stopper opening command correction value U. ' is compared with the stopper opening measurement value U' detected by the stopper opening detector 5, the deviation signal is sent to the hydraulic servo valve 3, and the hydraulic servo valve 3 supplies oil to bring the mold level y to a predetermined level yr. The supply amount q is sent to the hydraulic cylinder 4 and the stopper opening degree of the stopper 6 is adjusted.

FIG. 2(a) shows the results of a numerical experiment of the control performance when mold level control is performed according to the above embodiment when a variation of 1 occurs in the flow rate gain of the stopper 6. At the time of this Atsushi (11 great wishes), the flow rate gain of the stopper was increased by 1 to 3000 in steps.

It was changed sequentially from 4000 to 5000. In addition, Figure 2 (
b) shows the control performance of the mold level control according to the conventional example shown in FIG. 5 for comparison.

As shown in FIG. 2(b), in the conventional mold level control, as the flow rate gain increases by 1, the mold level control performance deteriorates, especially when the flow rate gain increases by 1.
When the value is 000, the control performance is unstable.

On the other hand, as shown in Fig. 2(a), in the case of this embodiment, the mold level fluctuates slightly immediately after the flow gain changes by 1, but it quickly returns to the target value y, resulting in stable control performance. can be kept.

〔Effect of the invention〕

As explained above, this invention automatically compensates the control system for changes during casting in the flow rate gain of the stopper that adjusts the amount of molten steel injected into the mold. This has the effect that mold level control can be performed with stable control performance at all times.

Furthermore, since the mold level can be kept constant even if the flow rate gain of the stopper varies by 1, it also has the effect of improving the quality of the slab and improving the yield.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing an embodiment of the present invention, and FIG.
Figures (a) and (b) respectively show the control performance characteristics, (a) is the control performance characteristic diagram of the above embodiment, (, b) is the control performance characteristic diagram of the conventional example, and Figure 3 is the control performance characteristic diagram of the continuous casting machine. An explanatory diagram showing the configuration of
FIG. 4 is a configuration diagram of a conventional mold level control device, and FIG. 5 is a control block diagram of the conventional example. 1...Target value setter, 2...
...PID controller, 3...Hydraulic servo valve, 4...Hydraulic cylinder, 5...
...Stopper opening degree detector, 6...Stopper, 7...Level detector, 12...
...... Slab drawing speed detector, 13...
...Flow rate gain estimator, 14...Gain compensator, 33...Mold. Agent Patent Attorney Muneharu Sasaki Diagram 2 (a) (b) B-Question (Excerpt) Diagram 3 Diagram 4 Procedural Amendment (Voluntary) May 8, 1939

Claims (1)

[Claims] The mold level is detected, and the detected mold level measurement value is sent to the feedback control means, and the molten steel injection amount adjustment stopper opening (hereinafter referred to as stopper opening) is adjusted so that the mold level measurement value and the target level value match. Flow rate gain estimating means for estimating the flow rate gain of a molten steel injection rate adjustment stopper using the measured values of the mold level, stopper opening degree, and slab withdrawal speed, in a mold level control device for a continuous casting process that adjusts the rate of molten steel injection rate. Using the estimated flow rate gain value ■_1 estimated by the flow rate gain estimating means, the following formula u_0'=(K_10/■_1)u_0 where K_10: correction value u of the output u_0 of the feedback control means using a positive constant
A continuous casting mold level control device comprising: gain compensation means for calculating _0'.