JPS626748A - Injecting device for molten metal - Google Patents

Abstract

PURPOSE:To prevent a break-out and an overflow from a casting mold by providing a circuit for cutting off a DC signal component, between an oscillator of an injecting device and a driving device. CONSTITUTION:A molten metal surface position measuring instrument 5 is provided on a casting mold 4, and also a measuring signal (a) is inputted to a regulator 9. A molten metal surface position setting device 8 inputs a reference molten metal surface position signal (b) to the regulator 9 in the same way. Between an oscillator 10 and a driving device of a sliding nozzle 1, two R-C circuits consisting of a capacitor and a variable resistor are provided. When a molten steel 2 in a tandish 3 is being injected to the casting mold 4, even if a fault is generated in the oscillator 10, namely, even if an oscillating signal (d) of DC of a high level is transmitted continuously, a phase regulator 30 pro vided with a capacitor is in the output side of the oscillator 10, and its output becomes 0V immediately. Accordingly, an opening adjustment of the nozzle 1 is returned to a controlled state before an excitation, and a break-out, etc. are prevented.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an apparatus for injecting molten metal into a predetermined container while periodically changing the opening degree of an opening adjustment part such as a sliding nozzle. For example, the present invention relates to a molten metal injection device that cuts off a DC signal component outputted by an oscillator provided to change the opening degree in the event of a failure or the like.

[Prior art]

In recent years, steel products are generally manufactured using continuous casting equipment. When pouring molten steel into a mold, continuous casting equipment measures the surface position of the molten steel injected into the mold using radiation, ultrasonic waves, thermocouples, TV cameras, etc. It is generally configured to perform continuous casting by performing level control that automatically adjusts the opening degree of the sliding nozzle so that the surface is located within a standard tolerance range with a dead zone. As shown in FIG. 7, the hot water level control in such continuous casting equipment involves, for example, installing a hot water level position measuring device 5 on the back side of the copper plate of the mold 4, detecting the hot water level position in the mold 4, and using this detected value and the hot water level. A regulator 9 into which the standard tolerance set in the surface position setting device 8 is inputted controls the flow of molten steel through the sliding nozzle 1 and the submerged nozzle 6 installed below it when the detected value is higher than the standard tolerance. A signal is given to the servo amplifier 11 to reduce the flow rate of the cylinder cylinder 12.2, and the servo amplifier 11 controls the servo valve 13. The sliding nozzle 1 is adjusted in the closing direction via the pilot cylinder 12' and the work cylinder 7 to reduce the cross-sectional area of the flow path for the molten steel 2. On the other hand, when the melt level is lower than the standard allowable range, the sliding nozzle 1 is similarly controlled via the servo cylinder 12° pilot cylinder 12' and the work cylinder 7 in order to increase the flow rate of the molten steel 2 flowing through the sliding nozzle 1. The opening force is adjusted to increase the cross-sectional area of the flow path for the molten steel 2 so that the molten metal level is always within the standard tolerance range. However, when the molten steel 2 is injected with such level control, if the injection time becomes long, for example, after approximately 30 minutes have elapsed from the start of injection, the sliding nozzle will stop working as shown by hatching in Fig. 8. 1 upper fixing plate 1
The base metal inserted into the gap between b and sliding plate 1a and the base metal that adheres to and grows at the step between the inner circumferential wall of sliding nozzle 1 and sliding plate la, causing trouble in the sliding of sliding plate 1a. Also, the sliding play H is caused by the high temperature molten steel 2.
a is heated and causes distortion, which causes sliding play) 1a
The sliding resistance of the sliding surface increases, the responsiveness of the hot water level control deteriorates, and the hot water level tends to deviate from the standard tolerance range.

In order to prevent such difficulties, an oscillator IO is provided on the input side of the servo amplifier 11 as shown by the broken line in FIG. By setting an AC signal with an amplitude larger than the dead band width, superimposing the AC signal on the output signal of the regulator 9, that is, the hot water level control signal, and applying it to the servo amplifier 11, the opening adjustment part of the sliding nozzle etc. can be adjusted. By periodically vibrating in the opening/closing direction, the metal inserted into the gap between the nozzle wall and the opening adjustment part is removed, and the metal is attached to the stepped part between the inner peripheral wall of the nozzle and the opening adjustment part.

In Japanese Patent Application No. 58-11, the applicant proposes a method for injection by suppressing growth or removing deposits from stepped portions to improve the accuracy of controlling the level of molten metal in molds, tundins, etc.
No. 1441).

[Problem that the invention seeks to solve]

When injecting molten metal by such a method, the oscillator 1
0 fails, a signal of a constant level as shown in FIG. 9(b) regardless of the output value of the regulator 9 shown in FIG. 9(al),
In other words, a DC signal may be output. In such a state, the sliding nozzle 1 mainly operates the servo amplifier 1 based on this DC signal and the hot water level control signal.
The opening degree is supposed to be adjusted by the output signal of No. 1 (see Fig. 9 (C1)), but in reality, the servo amplifier is 11
As shown in FIG. 9(d), only the portion where the output signal exceeds is effective in adjusting the opening. For this reason, as shown in Figure 9 (81), the work cylinder operates so that the sliding nozzle l is fully opened or completely open, and the hot water level control becomes abnormal and the follow-up is delayed, and the average value of the hot water level reaches the target value. However, the fluctuation may be more than ±30 fins.In this case, for example, when the molten metal level tends to rise, the molten steel 2
may overflow, resulting in a so-called oats<-flow, and when the molten metal level is on a downward trend, the molten metal level becomes lower than the molten steel spout of the immersion nozzle, resulting in insufficient cooling by the mold 4, resulting in a so-called break. There is a problem that an out occurs.

[Means for solving problems]

The present invention was made in view of the above circumstances, and by providing a circuit that cuts off the DC signal component between the oscillator and the servo amplifier, it is possible to safely continue controlling the hot water level even if the oscillator fails. The object of the present invention is to provide a molten metal injection device.

The melting rule injection device according to the present invention has a drive device that drives an opening adjustment section that adjusts the amount of molten metal injected into a predetermined container to keep the level of the molten metal in the predetermined container constant. In the injection device, the injection device adjusts the hot water level to a constant level while periodically changing the opening degree of the opening adjustment section by superimposing and applying a control signal from the oscillator and an alternating current signal from the oscillator. It is characterized by being equipped with a circuit that blocks DC signal components.

【Example〕

The present invention will be specifically described below based on drawings showing an embodiment of a four-strand continuous casting facility.

FIG. 1 is a schematic diagram showing an embodiment of the apparatus of the present invention, in which the molten steel 2 in the tundish 3 has, for example, four sliding nozzles 1. into the mold 4 through the immersion nozzle 6? Being the host.

The figure shows a sliding nozzle l for one strand,
? , a dipping nozzle 6, a mold 4, etc. are visible, and the other strands have a similar configuration.

Each sliding nozzle 1 is attached to the bottom of the tundish 3, and the f4 stored in the tundish 3 is
&j12 flow rate, in other words, the injection amount to control the molten metal level in the mold 4 and inject the molten steel 2 into the mold 4,
This is to adjust the As shown in FIG. 7, this sliding nozzle (2) consists of a sliding plate la and an upper fixing plate 1b which holds the sliding plate la so as to be slidable in a direction orthogonal to the flow direction of the melt m2.

A circular hole 1c approximately the same size as the circular hole of the upper fixed plate 1b is provided at the center of the sliding plate la, and a rod 7c of the work cylinder 7 is connected to one end of the circular hole 1c. The work cylinder 7 is of a double-acting type and has an oil chamber 7a for rod advancement and an oil chamber 7b for rod retraction, and the oil chamber 7a is connected to the oil chamber 12'a for rod retraction of the pilot cylinder 12'. Further, the oil chamber 7b is connected to the oil chamber 12'b for extending the rod through a joint 20, respectively.

The pilot cylinder 12' is connected to the servo cylinder 12 by sharing a rod 12c, and the servo cylinder 12 similarly has an oil chamber 12a for rod advancement and an oil chamber 12b for rod retraction. Each oil chamber 12a.

12b is connected to the load side boat of the 4-port 1-3 position switching type servo valve 13, and the other boats are connected to the pressure oil source 16 and the pump 14. The servo valve 13 is switched to a switching position 13c (or 13a) on the right side (or left side) in the figure based on a control signal e output from a servo amplifier 11, which will be described later.
The pressure oil from the pressure oil source 16 is switched to the servo cylinder 12.
This sends pressurized oil to the oil chamber 7b (or 7a) of the work cylinder 7, causing the round door c to enter (or advance), and the sliding plate 1a of the sliding nozzle 1 to move. Move it in the open (or close) direction.

A cylinder movement measuring device 15 using a variable resistor is attached to the cylinder loft 12c to measure the movement thereof, and its measurement signal f is given to the servo amplifier 11 as a feedback signal.

A known hot water level position measuring device 5 is installed inside the mold 4.
This measures the level of the molten steel 2 poured into the mold 4, and outputs a measurement signal a to the regulator 9 that controls the level. The hot water level position setting device 8 is used to set a reference hot water level position or range, and similarly outputs a signal regarding the set reference position to the regulator 9. The controller 9 calculates the deviation of the measurement signal a from the set reference position based on the manually input measurement signal a and the signal regarding the set reference position of the hot water level, and sends a control signal C to the servo amplifier to eliminate this deviation. Send to 11.

The oscillator 10 is for setting the vibration period and stroke of the sliding plate la of each sliding nozzle 1, and the frequency and amplitude of the oscillation signal d are set respectively, and the oscillation signal d is sent to the phase adjuster 30. It will be done. Note that a sine wave, a triangular wave, a rectangular wave, etc. are used as the waveform.

The phase adjuster 30 includes capacitors CI, C2, variable resistors R, . . . on the output terminal side of the oscillator 1o as shown in FIG.
R2 is provided with two R-C circuits connected in series in this order in parallel to the oscillator IO, and the variable resistor R
1 and R2 are slidably provided with contacts, which serve as output terminals.

The output signal d of one variable resistor R1 is directly applied to the servo amplifier (lla) of the first strand, and its phase is inverted by the phase inversion circuit 31. )
The other variable resistor R2
The output signal can be adjusted to a signal d3 with a phase θ different from that of d, d2 by the position of the contactor of R2, and the signal d3 is directly given to the servo amplifier (llc) of the third strand, and the phase is changed by the phase inversion circuit 32. The inverted signal d4 is applied to the servo amplifier (lid) of the fourth strand. Therefore, the supply timing of pressure oil to the joint 20 is shifted for each strand, so that the load can be reduced and oil leakage from the joint 20 is prevented.

And these outputs d1. d2. dz, d4, that is, the oscillation signal d, is sent to each servo amplifier 11.

Each servo amplifier 11 (11a, 11b, 11c, 11
d) calculates the difference between the control signal C and the measurement signal f, which is a feedback signal, and adds the oscillation signal d(d+) to this calculated value.

The signal obtained by adding d21 d31 d4) is the signal that is outside the upper and lower limits of the dead zone of the entire control system and is output as the control amount [see Figure 3 (a)], and the output control Signal e is given to servo valve 13.

As a result, the work cylinder 7 and the sliding plate 1a move to eliminate the difference between the signal regarding the set reference position and the measurement signal a, as shown in FIG. Compound movements are performed in the same pattern with all different phases.

The device of the present invention is configured in this way, so that even if a failure occurs in the oscillator 10 itself while the molten steel 2 in the tundish 3 is injected into the mold 4 by the device of the present invention, it will not cause any inconvenience to the level control. do not have. In other words, due to a failure in the oscillator IO, a DC oscillation signal d with a level higher than the upper limit of the dead band is generated in the oscillator 1.
Even if the signal continues to emit from 0, since the device of the present invention is provided with capacitors C1 and C2 on the output side of the oscillator 10, the output will immediately become 0, as shown in FIG.

As a result, the hot water level control signal C from the regulator 9 and the measurement signal f from the cylinder movement measuring device 15 are input to the servo amplifier 11, but at this time, as shown in FIG.
The control signal c-f shown in FIG.
), the opening of the sliding nozzle is not controlled until the dead zone is exceeded as shown in FIG. 5(e), and the opening degree of the sliding nozzle is not controlled as shown in FIG. The sliding nozzle is shown in Figure 5(e).
As shown in the figure, the opening degree is fixed at the opening immediately before the oscillator 10 fails. Further, even when the oscillator 10 starts emitting a DC signal with a level lower than the lower limit of the dead band, the opening degree of the sliding nozzle is controlled in the same way.

For this reason, defects in hot water level control are prevented, and the average hot water level is about ±7fi from the target value, which is the normal PID before vibration.
It becomes a controlled state. This makes it possible to prevent breakouts, overflow from the mold, etc., for example.

In the above embodiment, injection is performed using a tundish equipped with four sliding nozzles, but in the present invention, the number of sliding nozzles is not affected; for example, injection is performed using a tundish equipped with one sliding nozzle. Of course, it is possible to adjust the phase in the same way even in the case of the above-mentioned cases.

Further, although the above embodiment has a configuration including a capacitor, the present invention is not limited to this, and a general DC breaker that blocks DC signals can be used. As the DC breaker, for example, a controller configured to detect the current level and not output if the detected value does not change for a predetermined period of time may be used.

Furthermore, the present invention is not limited to sliding nozzles,
Of course, a rotary nozzle in which the flow rate is adjusted by rotating the rotary plate 17 as shown in FIG. 6 can also be used. Furthermore, the present invention also applies when a sliding nozzle or rotary nozzle type injection device is attached to the injection opening of the ladle bottom layer to inject molten metal into the tundish, and this superposition is managed with a load cell to control the molten metal level height. Of course, the device can also be used.

〔effect〕

As described in detail above, in the case of the present invention, a DC breaker such as a capacitor is provided on the output side of the oscillator, so even if the oscillator etc. breaks down, hot water level control can be continued. The present invention has excellent effects such as being able to prevent breakouts, overflow from molds, etc. caused by malfunctions.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a phase adjuster and its output signal, and FIG. 3 is an explanatory diagram of the contents of a control signal for adjusting the opening degree of a sliding nozzle. FIG. 4 is a diagram showing a change in potential over time in the RC circuit, FIG. 5 is an explanatory diagram of the content of opening control of a sliding nozzle, and FIG. 6 is a diagram showing another opening adjustment section to which the present invention can be applied. 7 is an explanatory diagram of the prior art, FIG. 8 is a schematic sectional view showing a sliding nozzle, and FIG. 9 is an explanatory diagram of problems in the prior art. 1... Sliding nozzle 10... Oscillator 3
0...Phase adjuster

Claims (1)

[Claims] 1. A control signal for adjusting the level of the molten metal in the predetermined container to a constant level, and In an injection device that superimposes and applies an alternating current signal from an oscillator to adjust the hot water level to a constant level while periodically changing the opening degree of an opening adjustment section, a direct current signal component is provided between the oscillator and the drive device. A molten metal injection device characterized by being equipped with a circuit for interrupting.