JPS6021813B2 - In-mold level control device for continuous casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a level control device in a mold for molten steel in continuous casting equipment.

Recently, an automatic control system has been constructed to control the level of molten steel in the mold in continuous casting equipment using a bell detector, a controller, and an electro-hydraulic servo system, which automatically opens and closes a stopper connected to a hydraulic cylinder. The mold y is kept constant by controlling the amount of molten steel q corresponding to the drawing speed V (flow rate Q) of the mirror piece into the mold from the tundish.

The purpose of this is not only to improve the quality of the mirror piece by keeping the level of the hot water constant in the mold, but also to reduce the burden on the operator by automatically opening and closing the stopper, thus saving labor. Not only that, but it also has the effect of ensuring safety.

The operator uses the operating lever to switch modes at the start of coining (the period during which molten steel is injected into the mold from the tundish, the stopper is manually opened and closed using the operating lever, and the mold level y becomes constant in accordance with the withdrawal speed). Manual is selected in the box.

However, if you select AUTO in the mode switching box after confirming that the level has become constant and then turn on automatically, if there is a deviation in the electrical control system and hydraulic servo system, the control lever will receive a shock when the automatic turn-on occurs. (bumps) may occur, which is dangerous. Further, even when switching from automatic operation to manual operation, shocks (bumps) are dangerous.

As described above, level control has automatic mode and manual mode, but when switching between them, it is inevitable that a hydraulic shock will occur. This invention suppresses the shocks (bumps) of the hydraulic cylinder and operating lever when starting automatic operation or manual operation as described above in controlling the level in the mold of continuous casting equipment using both the hydraulic circuit and the electric circuit. The purpose of this invention is to solve the conventional problems with regard to a control device that can switch smoothly.

That is, this invention enables the stopper to be closed in an emergency without causing a bump on the stopper or the operating lever when switching from manual to automatic or from automatic to manual, and allows the hydraulic cylinder and the hydraulic circuit to be connected with a flexible hose. Equipped with a separation function, the circuit can be separated from the servo valve during manual operation, and the hydraulic silling side pressure Pc. This invention relates to in-mold level control for continuous casting equipment equipped with a circuit that applies preload to Po.

The present invention also relates to an in-mold level control device in which the preload in the circuit during hand sardination is approximately equal to the servo valve supply pressure. Furthermore, the present invention relates to an in-mold level control system that does not generate bumps in terms of electrical control by electrically adding analog memory to not only the hydraulic servo system but also the controller and the electrical control system. Furthermore, this analog memory relates to the control device which is added after the controller and at the stop function signal. Embodiments of the present invention will be described below with reference to the drawings.

Molten steel 32 is constantly poured into the tundish 31 from a ladle (not shown) in FIG. A stopper 30 is provided within the tundish 31, and this stopper 30 is adapted to move in conjunction with the hydraulic cylinder 28. By controlling the stopper function x33, the tundish 31
The amount q of hot water poured into the mold 36 is controlled via the /spout 34. At the initial stage of locking, the operator 39 drives the pinch roll system 38 to control the withdrawal speed V (pulling flow rate Q) of the coin coin 37. Therefore, while pulling the coin coin 37 at a certain withdrawal speed V, Level 3 within 36
To keep 5 constant, use tundish 31 to mold 36.
It is necessary to control the flow rate q poured inward so that it is equal to the drawing speed V, that is, the drawing flow rate Q.

During manual operation, the operator 39 closes the stop valve 29 of the hydraulic cylinder 28, simultaneously releases the hydraulic cylinder 28, and manually opens and closes the stopper 30 so that q=Q, thereby keeping the level y35 constant.

The hydraulic cylinder 28 is fixed to the side surface of the tundish 31.

In this case, the tube is fixed, but depending on the mechanism, the rod side may be fixed. mold level y3
5 is constantly detected by the level detector 12 and generates a level signal of EY, and the level detector amplifier 8 converts this signal to the level of PV.

This value is compared with the setting signal SP from the bell setting device 1 (this value is usually constant and rarely changed, so it is assumed to be constant in this explanation), and a deviation signal e (=SP - PV) is generated. 2 and is further converted into an EN signal (indicating that it will be subjected to PID calculation). The state of analog memory B6 is controlled by contact S2, and S
When 2 is open, the input EN and the output EMB are equal.

In other words, EM old = EN, and its output EMB is the input EN
It has a function that follows changes in . When S2 is opened, the analog memory output EMB continues to hold the previous value and has a function of showing a constant value regardless of changes in the input EN.

That is, depending on the state of the S2 contact (closed), the value is instantly held or the input is set to the output. The adder 7 adds the output EM old from the memory B6 and the memory input EN, and outputs the deviation thereof, that is, ER. The stopper relationship X33 is constantly detected by the relationship detector 14 attached to the hydraulic cylinder 28 and is given as an ES signal.

This signal is proportionally level-converted by the correlation detector amplifier 4 and becomes an EX signal, which is sent to the analog memory A3 and the summing amplifier 5.

Analog memory A3 has the same concept as analog memo IJB6, and is controlled by contact S, and when S is closed, input EX and output EMA are the same.

That is, EX=EMA, and the output EMA follows the change in EX. When S, the output EMA
has the function of continuing to hold its previous value, becoming unrelated to changes in input EX, and indicating a constant value. Analog memory A
ER is added to the output EMA of No. 3 and the output of the adder 5 to form EE (EE=ER+EMA), which is sent to the summing amplifier 5.

The general operation of analog memory will now be briefly explained with reference to FIG.

When contact S is closed, output Y follows X and Y=X.

When S becomes a link from this state, the analog memory 41 retains the value at the moment when S becomes a link, and continues to hold this value until S becomes a link.

Furthermore, when S closes, Y immediately follows X, resulting in Y:X.

Here, if we make X correspond to EX, Y to EM, and S to S, we can explain the analog memory A3.

Further, if X is made to correspond to EN, Y to EM old, and S to S2, the analog memory B6 can be explained.

The summing amplifier 5 combines this signal with the output E of the correlation detector amplifier 4.
X is calculated, and a control current 1 proportional to a gain of 9 times the deviation (EE-EX) is generated and sent to the electro-hydraulic servo valve 15.

Here, the summing amplifier 5 has the same functions as a general servo amplifier, such as gain and zero point adjustment. The electrohydraulic servo valve 15 sends a flow rate proportional to this control current 1 to the hydraulic circuit, and controls each solenoid valve.
From this state, the hydraulic cylinder 28 is controlled (driven). A stop valve 29 disposed near the hydraulic cylinder 28 is used to free the hydraulic cylinder 28 during an emergency or manual operation so that an operator 39 can operate the lever, and is closed during automatic control by the electro-hydraulic servo valve 15. ing.

The filter 26 prevents dust from entering the hydraulic circuit when the flexible hose 27 is attached and detached at the initial and final stages of casting.

The counterbalance valve 25 prevents the stopper 30 from falling due to its own weight, and is set appropriately. In order to attach and detach the flexible hose 27 from the hydraulic cylinder 28 before starting casting or after finishing casting, the hydraulic circuit pressure Pc. P
It is necessary to lower D, and this can be achieved by selecting the pressure relief mode in the mode switching box 10.

When the pressure relief mode is entered, SoL2 of the switching valve A16 is energized as shown in Fig. 3, and at the same time, Sob of the switching valve B17 is deenergized to open the pilot check valve 40, and the flow is opened to the tank T2. By doing so, the circuit pressure is lowered and the flexible hose can be easily attached and detached.

At this time, SoL4 of the switching valve C18 remains energized, and the inlet boat of the pressure reducing valve 222 is connected to T2 and is not operated and blocked by the check valve 224.

In addition, SoL6 of the switching valve DI9 is excited, and the pressure reducing valve 1
21 also does not operate. 23 is a check valve 1.

Furthermore, the stop valve 29 is open, making attachment and detachment easier.

At the time of removal, the SoL of the switching valve Ai6 is energized, so the AB boat of the electro-hydraulic servo valve 15 is connected in the circuit, and the pressures P^ and P8 are the same pressure, and are separated from the hydraulic cylinder 28 side in the circuit and have no influence. It looks like this. When the flexible hose 27 is attached and manual mode is selected in the mode switching box 10, the hydraulic system changes as follows.

The SoL of the gate valve AI6 is excited, and the SoL of the gate valve B17 is excited.
L3 is energized, SoL4 of the sliding door valve C18 is energized,
Roughly, Sob of the switching valve DI9 is excited.

Therefore, pilot check valve 40 is closed, and check valve 2
24 is closed, the pressure reducing valve 121 becomes effective (setting possible state), and its set pressure is applied to Pc.

Pc and Po become equal because SoL of the switching valve AI6 is excited and the stop valve 29 is open.

In this state, the operator 39 uses the operating lever 13 to open and close the stopper 30 via the hydraulic cylinder 28, so that the molten steel 3 flows from the tundish 31 into the mold 36 via the nozzle 34.
2 is injected and the amount of hot water is controlled according to the drawing flow rate to reach level y35.
The function X33 is sequentially controlled so as to keep constant.

Here, the set pressure of pressure reducing valve 1 21 (so-called Pc≠Po)
The feature is that it is kept at the same level as the pressure P^ (=PB: when operated manually) of the electro-hydraulic servo valve 15. During manual operation, the pressure P^(=PB) of the servo valve 15 is the supply pressure P
．． It is known that it can be used as a proverb. (Because the servo valve 15 is unloaded and the load boats A and B are short-circuited) If the piping between the switching valve A16 and the hydraulic cylinder 28 is long and Pc and Po are quite low values, the switching valve AI at automatic closing.
When SoL 6 of switch valve DI9 is excited, Pc. P. A of servo valve 15.
Pc. until the B boat pressure (P^.PB) is trapped. P. Depending on the length of the line to the cylinder, etc., the hydraulic cylinder 28 will move. Therefore, by applying a pressure of P at the maximum in manual mode to this circuit and keeping it contained, it is possible to reduce the shock (bump) when switching from manual mode to automatic mode.

Also, during automatic closing, the ejector bell Y35 is quite stable and no large force is applied to the stopper 3, and even if it is applied, it is small hydraulically, but the preload setting is determined by the counterbalance valve 25 and the piping length. The difference can be arbitrary depending on the above conditions.

During manual operation, the operator 39 opens the stop valve 29 and sequentially opens and closes the stop valve 30 using the operating lever 13. In this state, the control current 1 to the servo valve 15 is
If it is not always at home, a bump will occur when the stop valve 29 is closed and the automatic operation is turned on.

That is, when the control current 1 to the servo valve 15 is generated, the A. of the servo valve 15 is generated. At the moment when an imbalance in the flow rate occurs in boat B and the switching valve SoL of the switching valve AI6 is switched, a force is applied to move the hydraulic cylinder 28, resulting in a shock (bump).

The analog memory A3 and the analog memory B6 were invented to always keep the control current 1 at zero during manual operation, and will be briefly explained below.

When the operator 39 selects manual mode using the mode switching box 10 and opens the stop valve 29 for manual operation, each switching valve is in the above state through the electric control panel 11, and at the same time the analog memories S and S2 are The contacts of A3 and analog memory B6 are closed.

Even if a deviation e occurs between the signal SP of the level setter 1 and the actual level signal PV and the output EN of the PID controller 2 is generated, the output EMB of the analog memory 86 will still follow EN'. Since EMB=EN, the output of adder 7 becomes ER=EN-EMB=EN-EN=0.

In other words, the SP of the level setter 1 and the actual level value PV
This shows that the output ER of the adder 7 will be zero even if there is a slight difference in .

Further, in the manual state, the signal EX obtained from the correlation detector 14 via the correlation detector amplifier 4 is S of the analog memory A3.
, are closed, the analog memory A3 outputs Ex as is, and EMA=EX.

Here, since the output of the adder 7 is ER=0, the input of the summing amplifier 5 is EE=EMA+ER=EX+0=EX Furthermore, the signal EX from the correlation detector amplifier 4 is input to the summing amplifier 5. As a result, the control current 1, which is the output of the summing amplifier 5, becomes zero. Therefore, during manual operation, the servo valve 15 is set to the A. When the automatic control is performed using the servo system, the operator 39 must move the control lever 1, which is not attached to any of the B boats and is set to the neutral position.
3, the actual hot water level bell 36 is brought close to the value set by the level setting device 1 (that is, SP≠PV), the stop valve 29 is closed, and the mode in the mode switching box 10 is set to automatic. .

A signal is sent from the switching box 10 to the electric control panel 11, and the contacts S, S2 of analog memories A3 and B6 instantly open, and at the same time, the SoL to SoL activation signals of each switching valve are transmitted to the hydraulic circuit. It becomes automatic mode.

In the automatic mode state, SoL of the switching valve A16 is excited and the load boat A. of the servo valve 15 is activated. B is each Po. Pc
At the same time as connecting to the line, SoL of switching valve DI9 enters, and the inlet boat of pressure reducing valve 121 is connected to tank T2, and P
Cuts are made from the c and Po lines.

In this state, the SoL of the switching valve B17 and the switching valve CI8
SoL remains energized.

Therefore, in this state, the hydraulic cylinder 28, the stopper opening
33 is the load boat AB due to the control current 1 of the servo valve 15.
will be automatically switched and controlled. When the power is turned on automatically, the contact S of the analog memory A3 opens instantly, so the analog memory A3 stores and holds the immediately previous value EX, that is, the stopper function x.

Further, since the contact S2 of the analog memory B6 is opened in the same way, the analog memory B6 stores and holds the immediately previous EMB, that is, the output EN of the controller 2 immediately before automatic entry.

Here, these values are assumed to be Efu, average, EMBo, and ENo.

In addition, the signals of each part immediately before being automatically used in these control systems are as follows. SPo: Set output signal value of the level setter 1 immediately before automatic input PVo: Measured output signal value e of the level detector amplifier 8 immediately before automatic input
o: Deviation signal value SPo-PVo immediately before automatic input
=eoEYo: Level detector 1 just before being automatically turned on
2 measurement signal value ENo: Output value of Pm controller 2 immediately before automatic input EMB: Output value of analog memory B6 immediately before automatic input = ENoERo: Adder 7 immediately before automatic input Output value ENo - EMB = zero EEo:
Output value E of analog memory A3 immediately before being automatically loaded
Sum of output values ERo of adder 7 to EM: Output value of analog memory A3 immediately before automatic input EF: Output value of correlation detector amplifier 4 immediately before automatic input F: Automatic Stopper opening L just before automatic injection: Input current value of the electro-hydraulic servo valve immediately before automatic injection L=0 Jo: Mold hot water level just before automatic injection Bell qo: Automatic injection Flow rate of molten steel injected into the mold immediately before Q: Drawing flow rate immediately before automatic injection Vo: Pulling speed immediately before automatic injection ESo: Measured signal value of opening detector 14 immediately before automatic injection During automatic closing, no shock (bump) occurs due to the preload effect of the hydraulic circuit and the action of the analog memory circuit.

Furthermore, since it is automatically turned on at the time when SPo becomes the main PVo, the automatic control system automatically opens and closes the stopper 30 without major disturbance, and stable automatic control is performed.

Consider a case where the molten steel level 35 changes due to some disturbance (for example, a change in the drawing speed) during this automatic control.

At this time, the stopper function 33 must be automatically corrected to control the injection amount q from the tundish 31 into the mold 36. This state will be briefly explained.

Now, if the drawing speed is increased (Vo→Vo+△V) and the drawing flow rate is increased (Qo→Qo+ΔQ), the welding height level will temporarily decrease.

(enemy→yoichi△y). In order to return the level to its original state &o and keep it constant, the stopper function must be opened (Yagura → Ne + △x). When the level drops, its position is sensed by the bell detector 12, and the signal is output via the level detector amplifier 8.
Vo minus ΔPV, and since SPo is constant, the deviation is eo+Δeo. (eo is equivalent to △PV) This eo + △eo is converted by controller 2 and its output is ENo
+△EN. Since the output of the analog memory B6 holds the value ENo immediately before automatic input, the output of the adder 7 is calculated and becomes equal to the value of ΔEN.

Further, the output of the analog memory A3 holds the immediately previous value Ef (=EMAo: EXo corresponds to the stopper function) at the time of automatic input.

Therefore, (stopper related command input) to the summing amplifier 5 is △
EN0EMAo=△EN+E Suddenly, the control current △1, which has been operationally amplified by the summing amplifier 5, is sent to the servo valve to move the hydraulic cylinder 28 until the output of the pressure detector amplifier 4 becomes E10△EN. Then, when they match, the servo valve control current is made zero to stabilize the system.

In other words, it is equivalent to giving a new stopper function command of △EN in response to a change in △V (that is, a change in the drawing flow rate △Q), and automatically follows the function by △×, resulting in △ By modifying the relationship of x, it is possible to establish an automatic control system that automatically follows the level up by △y and returns to the original level.

Here, the PID controller 2 functions to match SPo and PVo, which are the final target levels, using not only a proportional band and a differential constant but also an integral constant. Theoretically, in order to generate Δx, the output of the controller 2 will not be generated unless a certain amount of deviation occurs in the input of the PID controller 2. This means that a deviation must occur between the SP of the level setter 1 and the actual level PV.
The proportional gain of the PID controller 2 is high to some extent, and if an integral element is added to the deviation, the deviation can be kept at a constant level of 4. In other words, in order to generate △x and correct △y, if the value of the controller 2 is set appropriately, it will be possible to control it.Even if some steady-state deviation remains between the bell setting SP and the actual level PV, it is normal. Process control becomes possible.

On the other hand, when the drawing speed decreases and becomes Vo - ΔV, the operation should be considered in the completely opposite way.

In this way, during automatic control, control can be performed in the same manner as in a system composed of subordinate controllers. Here, the switching valve C18 is for emergency closing, and while it excites SoL4 during automatic operation, it also has the role of fully closing the stopper 30 that operates the hydraulic cylinder 28 in an emergency. .

Briefly, in automatic operation, when you press the on/off switch on the mode switching box 10, the switching valve A is activated via the electric control panel 11.
I6 becomes neutral and the Sob of the switching valve B17 is surprised to be energized, the pilot check 40 is opened and the Po line is connected to the tank, and the SoL4 of the switching valve C18 is also deenergized and the supply pressure P2 passes through the flow rate control valve 20 to the switching valve. C183 are connected to Pc through the pressure reducing valve 222 and check valve 224, and the hydraulic cylinder 28 is pushed down, resulting in the stopper 3
0 is closed.

The flow control valve 20 sets the closing speed, and the pressure reducing valve 222 sets the closing pressure. Also, at this time, SoL of the switching valve DI9 is excited.

When switching from automatic operation to manual operation, the control current 1 of the servo valve 15 is almost zero during automatic control, the SoL of the switching valve A16 is excited, and the switching valve AI9
Preload is applied by SoL5, and furthermore, So et al., So
Considering the above-mentioned manual conditions such as the fact that L4 is also excited, the servo valve 15 is completely disconnected and a preload effect is added to instantaneously bring Pc=Po, allowing switching without shock (bump). If it is manual, contact S of analog memory A3 and B6
,, S2 is in the above state and ready for automatic injection, and at the same time, the operator 39 opens the stop valve 21 and can manually operate the lever. To change from manual state to automatic state, close the stop valve 29 and press S of level setter 1.
If P and PV are roughly close to each other, injection can be made at any time.

When casting is completed, the pressure release mode is selected and the flexible hose 20 is removed.

According to this invention, as detailed above, in the hydraulic circuit, preload is applied to the cylinder circuit during manual operation, and the preload in the circuit is up to the supply pressure of the servo valve 15, but the piping length to the hydraulic cylinder and the load are Considering this, the effect of preload is large and allows switching without causing bumps.

In addition, analog memory is added to the electrical circuit to prevent bumps from occurring during switching, and as bump countermeasures are taken from both electrical and hydraulic aspects, it has an extremely significant effect in terms of safety. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a control system according to an embodiment of the present invention. However, it does not indicate a specific control mode. Figure 2 is an explanatory diagram of the operation of the analog memory, and Figure 3 is an illustration of each mode of each switching valve.
It is a comparison diagram of the deep state of the sole/do that can be driven.
2... PID controller, 3... Analog memory, 4... Relationship detector amplifier, 6...
Analog memory, 12...Level detector, 15
......Electro-hydraulic servo valve, 28...Hydraulic cylinder, 30...Stopper, 31...
・Tanditshu, 32... Molten steel, 35...
...Level y, 36""" mold. Figure scales 2nd figure chrysanthemum 3rd figure

Claims (1)

[Claims] 1. Opening and closing are automatically controlled by an automatic control system using a level detector, a controller, and an electro-hydraulic servo system, and connected to a hydraulic cylinder that controls the level of molten steel injected into the mold from the tundish. In the in-mold level control device for continuous casting equipment equipped with a stopper, the operating circuit for the hydraulic cylinder includes a switching valve that can be selectively disconnected from the circuit for the servo valve, and the operating circuit includes a switching valve that can be selectively disconnected from the circuit for the servo valve. It includes a preload circuit which is provided separately from the hydraulic cylinder and is connected to the inlet and outlet of the hydraulic cylinder and can supply a preload within the circuit up to approximately 1/2 of the supply pressure of the servo valve, and further includes a preload circuit after the controller and the opening of the stopper. An in-mold level control device for continuous casting equipment, characterized in that an analog memory is added after each detector amplifier.