JPH0119993B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a method for temporarily storing molten metal in the injection device by adjusting the opening degree of an opening adjustment section such as a sliding nozzle provided in the injection device. Regarding the method of pouring the molten metal into other containers, molds, etc.
More specifically, the present invention relates to a method of pouring molten metal that prevents solidification, adhesion, etc. of molten metal in the opening adjustment section and improves control accuracy.

[Prior art]

When injecting the molten metal in the tundish of a continuous casting machine into the mold, the surface position of the molten metal injected into the mold is measured using radiation, ultrasonic waves, thermocouples, and TV.
Continuous casting is performed by measuring the level using a camera, etc., and automatically adjusting the opening degree of the sliding nozzle so that the level is within the standard tolerance range with a dead zone based on the measured value. The method is well known. As shown in FIG.
This detects the level of the hot water inside the mold 4, and if this detected value is higher than the standard tolerance set in the level setting device 8, the sliding nozzle 1 installed on the lower surface of the tundish 3
and a regulator 9 to reduce the flow rate of the molten metal 2 through the submerged nozzle 6 mounted thereunder.
The control signal obtained by Similarly, the servo cylinder 1 is used to reduce the cross-sectional area of the flow path, and to increase the flow rate of the molten metal 2 flowing through the sliding nozzle 1 when the melt level is lower than the standard allowable range.
2. Adjust the sliding nozzle 1 in the opening direction via the pilot cylinder 12' and the work cylinder 7 to increase the cross-sectional area of the flow path for the molten metal 2, so that the molten metal level is always within the standard tolerance range. It is adjusted as follows. However, when pouring molten metal 2 with such level control, if the pouring time becomes long, for example, approximately
After 30 minutes have passed, the upper fixing plate 1b of the sliding nozzle 1 is fixed as shown by hatching in Fig. 8.
The base metal inserted into the gap between the sliding plate 1a and the sliding plate 1a and the base metal that adheres to and grows on the step between the inner peripheral wall of the sliding nozzle 1 and the sliding plate 1a, causing trouble in the sliding of the sliding plate 1a, In addition, the sliding plate 1a is overheated by the high-temperature molten metal 2, causing distortion, which increases the sliding resistance of the sliding surface of the sliding plate 1a, worsening the responsiveness of the hot water level control, and causing the hot water level to become lower than the reference level. It is easy to fall outside of the permissible range. To explain this in detail, the opening command signal is output from the servo amplifier 11 in order to eliminate the difference in the hot water level position with respect to the standard tolerance determined by the regulator 9 (hereinafter referred to as hot water level deviation) [Figure 9a] In response to Figure 9b
Against the movement of the servo cylinder 12, which operates as shown in Fig. 1, the sliding resistance increased due to the metal inserted into the gap between the upper fixed plate 1b and the sliding plate 1a, the metal that has adhered, grown, and thermal strain. As shown in FIG. 9c, the work cylinder 7 does not follow the direction faithfully and
As shown in Figure d, the control accuracy of the hot water level position decreases,
There was a problem that the hot water level was outside the standard tolerance range.

In order to solve such problems, the applicant of this application filed the patent application
The method of No. 58-111441 is proposed. As shown in FIG. 10, this method uses an oscillator 10 in addition to the control device shown in FIG. The opening degree of the sliding nozzle is changed periodically, and this periodic change causes the attachment and growth of metal to the step between the sliding plate and the nozzle wall above it, and the contact between the upper fixed plate and the sliding plate. This method improves the accuracy of hot water level control by suppressing the insertion of metal into the gap or by removing deposits from the stepped portion.

[Problem that the invention seeks to solve]

However, the sliding nozzle becomes distorted due to heat during injection, and this distortion increases the sliding resistance of the sliding nozzle. Therefore, when injecting for a long time, the method of Japanese Patent Application No. 111441/1986 is recommended. However, there was still the problem that the responsiveness of the hot water level control deteriorated.

[Means for solving problems]

The present invention has been made in view of such circumstances, and the opening adjustment section detects the resistance received when changing the opening, superimposes a detection signal and a signal for controlling the hot water level, and performs control based on this superimposed signal. By changing the opening degree of the opening adjustment part, it is possible to prevent metal adhesion and solidification around the opening adjustment part, and even if thermal distortion occurs in the opening adjustment part, the mold The object of the present invention is to provide a method of pouring molten metal that can control the level of hot water in a tundish or the like with high precision.

A method for injecting molten metal according to the present invention is a method in which molten metal is injected into a predetermined container by periodically changing the opening degree of an opening adjustment section of an injection device that enables adjustment of the amount of molten metal injected. , the opening adjustment section detects the resistance received when periodically changing the opening, and changes the amplitude of the change based on this detected value, and further adjusts the level of the hot water in the container. is detected, and the amplitude of the change is changed based on this detected value and the detected value of the resistance.

〔Example〕

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, in which molten steel 2 in a tundish 3 is injected into a mold 4 via a sliding nozzle 1 and an immersion nozzle 6. The sliding nozzle 1 is attached to the bottom of the tundish 3 and controls the flow rate of the molten steel 2 stored in the tundish 3, in other words, the level of the molten steel in the mold 4.
is injected into the mold 4. This sliding nozzle 1 is as shown in FIG. 8 mentioned above.
A sliding plate 1a and an upper fixed plate 1 that holds the sliding plate 1a so as to be slidable in a direction perpendicular to the flow direction of the molten steel 2.
It consists of b.

An upper fixed plate 1 is located at the center of the sliding plate 1a.
A circular hole 1c of approximately the same size as the circular hole b is provided,
A rod 7c of the work cylinder 7 is connected to one end thereof. The work cylinder 7 is a double-acting type and has an oil chamber 7a for rod advancement and an oil chamber 7b for rod retraction, and the advancement oil chamber 7a is an oil chamber 12'a for rod retraction of the pilot cylinder 12'. In addition, the oil chamber 7b for entering and exiting is the oil chamber 12' for advancing the rod.
b, and are connected in communication with each other. The rod 7c of the work cylinder 7 is attached with a cylinder movement measuring device 20 that uses a variable resistance to measure its movement, that is, the position of the sliding plate 1a of the sliding nozzle 1, and its measurement signal is g is given to the excitation signal optimum setting control device 17.

Also, between the advancing oil chamber 7a of the work cylinder 7 and the retreating oil chamber 12'a of the pilot cylinder 12', and between the advancing oil chamber 7b of the work cylinder 7 and the advancing oil chamber 12' of the pilot cylinder 12'. A pressure detector 1 is installed in the hydraulic piping that communicates with 12'b.
8 and 19 are respectively interposed.

These pressure detectors 18 and 19 detect the pressure of the hydraulic oil supplied to both the oil chambers 7a and 7b of the work cylinder 7, thereby adjusting the sliding resistance in both the reciprocating directions of the sliding plate 1a of the sliding nozzle 1. , and the respective detection signals h,
i is given to the excitation signal optimum setting control device 17.

Pilot cylinder 12' is servo cylinder 1
2 and are connected by sharing the rod 12c. Similarly, the servo cylinder 12 has an oil chamber 1 for advancing the rod.
2a and an oil chamber 12b for rod retraction, each oil chamber 12a, 12b is connected to the load side port of a 4-port 3-position switching type servo valve 13, and the other ports of the servo valve 13 are connected to a pressure oil source 16 and tank 1
Connected to 4.

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 sent to the oil chamber 12b (or 12a) side of the servo cylinder 12, thereby sending the pressure oil to the oil chamber 7b (or 7a) of the work cylinder 7, and the rod 7c is withdrawn. (or advance) and move the sliding plate 1a of the sliding nozzle 1 in the opening direction (or closing direction).

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

The mold 4 is equipped with a well-known hot water level position measuring device 5, which measures the hot water level position of the molten steel 2 injected into the mold 4, and uses the measurement signal a to control the hot water level. output to the controller 9 and the excitation signal optimum setting control device 17. Further, the hot water level position setting device 8 is for setting the standard hot water level position or range, and the signal b regarding the set standard position is also sent to the regulator 9 and the excitation signal optimum setting control device 17.
Output to. The controller 9 determines the deviation of the measurement signal a from the set reference position based on the input measurement signal a and the signal b 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 emits a signal d for periodically vibrating the sliding plate 1a of the sliding nozzle 1, and the vibration period and vibration width of the sliding plate 1a are determined by the excitation given from the oscillator 10 to the servo amplifier 11. It is defined by the frequency, amplitude and waveform of signal d. The amplitude of this excitation signal d is determined by the measurement signal a from the hot water level position detector 5, the signal b from the hot water level position setting device 8, and the measurement signal from the movement measuring device 20 of the rod 7c of the work cylinder 7. g, and the detection signals h and i of the pressure detectors 18 and 19, is determined by the excitation signal optimum setting control device 17,
oscillator 10.

The excitation signal optimum setting control device 17 is constituted by a microcomputer system or an analog calculation device, and is configured from an oscillator 10 to a servo amplifier 11.
Set the frequency (defines the vibration period of the sliding plate 1a), amplitude (defines the vibration width of the sliding plate 1a), and waveform (sine wave, rectangular wave, triangular wave, etc.) of the excitation signal d given to the The frequency and waveform are set by an operator, for example.

The vibration amplitude of the sliding plate 1a is given in advance to the vibration signal optimum setting control device 17 in the form of a conversion table or calculation formula as shown in FIGS. 2 and 3. That is, the vibration width of the sliding plate 1a of the sliding nozzle 1, which is detected as a change in the operating pressure by both pressure detectors 18 and 19, varies as shown in FIG. If the dynamic resistance is large, the amplitude will be large to some extent, and the deviation (specifically As shown in FIG. 3, the amplitude of the vibration of the sliding plate 1a according to the difference between the signals a and b is set to be relatively large if the deviation in the level of the hot water is large. Then, for example, the set value of the vibration width of the sliding plate 1a is determined by weighted averaging the vibration width according to the sliding resistance at a ratio of 7/10 and the vibration width according to the hot water level deviation at a ratio of 3/10. The amplitude (voltage) of the signal corresponding to this is set in the oscillator 10.

Therefore, for example, if the molten steel 2 adheres to and solidifies in the sliding gap or the stepped portion of the sliding nozzle 1 and the sliding resistance increases, or if the sliding plate 1a etc. is distorted due to the heat of the molten steel 2, the sliding becomes difficult. When the resistance increases, and furthermore when the deviation in the level of the molten metal in the mold 4 becomes large, the sliding plate 1a is vibrated with a larger vibration amplitude.

On the other hand, the waveform of the excitation signal d is a sine wave, a triangular wave,
Any type of wave such as a rectangular wave may be used, but in general, if a sine wave is used, the hydraulic system will operate smoothly and troubles will be less likely to occur. Further, regarding the frequency of the excitation signal d (vibration period of the sliding plate 1a), 0.2 to 1.2 Hz is preferable for a sine wave, 0.2 to 0.6 Hz for a rectangular wave, and 0.2 to 1.0 Hz for a triangular wave. This is the excitation signal d
When the frequency of is below the above-mentioned lower limit, the sliding plate 1a
This is because, since the movement of the molten steel 2 is slow, it is not effective in preventing adhesion and solidification of the molten steel 2 on the sliding plate 1a, and conversely, when the above-mentioned upper limit is exceeded, the operation of the hydraulic system cannot follow. Regarding the amplitude of the excitation signal d, the amplitude of the sliding plate 1a controlled by this is 1 to 20.
Set it to be mm. This means that when the amplitude is less than 1 mm, the molten steel 2 at the sliding nozzle 1
This is because it is not effective in preventing adhesion and solidification, and conversely, if it is 20 mm or more, the adjustment of the molten metal level in the mold 4 will be adversely affected.

The servo amplifier 11 calculates the difference between the control signal c given from the regulator 9 and the measurement signal f from the movement measuring device 15 of the cylinder rod 12c of the work cylinder 12, which is a feedback signal, and adds the excitation signal d to this difference. The signal thus obtained is output as a control amount, and the output control signal e is sent to the servo valve 13. As a result, the sliding plate 1a of the sliding nozzle 1 performs a compound movement based on the movement to eliminate the difference between the signal b regarding the set reference position and the measurement signal a, and the excitation signal d from the oscillator 10.

[Function] Next, examples of the method of the present invention will be described in detail. In a Bloom continuous casting machine, molten steel 2 of steel type SWCH12A, for example, contained in a tundish 3 is injected into a mold 4 using a sliding nozzle 1 with an inner diameter of 60 mmφ, and the slab is pulled out at a drawing speed of 0.6 m/min. there was. The level position of the molten steel 2 injected into the mold 4 is measured by the level position measuring device 5, and this measurement signal a is sent to the regulator 9 and the vibration signal optimum setting control device 17. Based on the measurement signal a and the signal b related to the set reference position, the regulator 9 adjusts the opening degree so that the sliding plate 1a is in the closing (or opening) direction when the hot water level is higher (or lower) than the reference position. A control signal c is sent to the servo amplifier 11.

Further, the servo amplifier 11 is given an excitation signal d from the oscillator 10. The frequency, amplitude (voltage), and waveform of this excitation signal d are set by the excitation signal optimum setting control device 17, and the frequency and waveform are selected and set through appropriate acquisition, and the amplitude is determined by each input signal as described above. The vibration width of the sliding plate 1a is first determined based on a, b, g, h, i, etc., and the amplitude (voltage) of the excitation signal d corresponding to this determined vibration width is set in the oscillator 10. .

Now, the frequency of the excitation signal d given from the oscillator 10 to the servo amplifier 11 is set to 1 Hz, and the waveform is set to a sine wave. The servo amplifier 11 is the regulator 9
A control signal c, which is the difference between the measurement signal a of the hot water level position measuring device 5 and the setting signal b of the hot water level position setting device 8 given from The long wavelength signal shown in FIG.

The reference amplitude (for example, the amplitude at the start of injection) of the excitation signal d is set to be slightly larger than the dead zone width of the entire control system. Therefore, even when the hot water level is maintained at the value set by the hot water level position setting device 8, the work cylinder 7, and therefore the sliding plate 1a, vibrate with an amplitude corresponding to the difference.

Now, from the servo amplifier 11 to the work cylinder 7
If the width of the dead zone between them is within the range of the two broken lines shown in FIG.
The work cylinder 7 changes its position at a period corresponding to the period of the difference signal between the control signal c and the measurement signal f while repeating short period vibrations as shown in FIG. 4b. The servo valve 13 operates according to the control signal e to open the oil chamber 12 for advancing the rod of the servo cylinder 12.
a. Pressure oil is alternately supplied to the oil chamber 12b for rod retraction, and the servo cylinder 12 operates the rod 12c as shown in FIG. 5a. This allows the fifth
As shown in FIG. b, the work cylinder 7 is substantially operated and the sliding plate 1 of the sliding nozzle 1
a periodically opens its opening and moves in the closing (or opening) direction while changing in the closing direction. Due to such movement of the sliding plate 1a of the sliding nozzle 1, the molten steel 2 enters the gap between the wall of the sliding nozzle 1 and the sliding plate 1a, solidifies, and the inner peripheral wall of the sliding nozzle 1 and the sliding plate The adhesion and solidification of the molten steel 2 to the step between the molten steel 1a and the molten steel 1a is controlled, and even if it does adhere, it easily falls off, which improves the responsiveness of the control.In addition, the control has no apparent dead zone. As a result, the hot water level is controlled almost to the reference hot water level position set by the hot water level position setting device 8, and the hot water level deviation, which was conventionally about ±7 mm, has been improved to about ±1.5 mm.

By the way, while the above-mentioned level control is being performed, for example, the molten steel 2 may enter the gap between the sliding parts of the sliding nozzle 1 and solidify, or the sliding plate 1a may be distorted by the heat of the molten steel 2. When the sliding resistance of the sliding plate 1a increases and the control accuracy decreases, the increase in sliding resistance is detected by both pressure detectors 18 and 19, and the detection signals h and i are Since the vibration signal is given to the vibration signal optimum setting control device 17, control is performed to increase the vibration width of the sliding plate 1a, as described above.
On the other hand, even when the hot water level changes, it is detected by the hot water level position measuring device 5, and the measurement signal a is given to the excitation signal optimum setting control device 17, so that the deviation of the hot water level is ±3 mm. If the vibration amplitude exceeds that level, control is performed to increase the vibration amplitude of the sliding plate 1a. Then, the excitation signal optimum setting control device 17 takes a weighted average of both at a ratio of 7:3, and calculates the amplitude (voltage) corresponding to the vibration width of the sliding plate 1a.
is set in the oscillator 11 as the amplitude of the excitation signal d.

By performing the above-described control, the amplitude of vibration of the sliding plate 1a increases. Specifically, the amplitude of the excitation signal d shown in FIG. 4a becomes larger than the dead band width of the entire control system shown by the two broken lines.
Substantially, the sliding plate 1a periodically changes its opening degree based on the sliding resistance, centering on the opening degree for controlling the hot water level. Therefore, the control signal e given from the servo amplifier 11 to the servo valve 13 exceeds the dead zone and vibrates upward and downward to a greater extent than shown in FIG. 4b, and the amplitude of vibration of the sliding plate 1a increases. .

By performing such control, even if the molten steel 2 adheres to and solidifies around the sliding plate 1a of the sliding nozzle 1, it easily falls off, so the sliding resistance of the sliding plate 1a decreases, and the original state is restored. control accuracy is maintained.

By the way, when the above-mentioned control to increase the vibration amplitude of the sliding plate 1a is performed, there may be a danger depending on the position and vibration amplitude of the sliding plate 1a, but the rod of the work cylinder 7 7c
Since the movement amount measuring device 20 of the work cylinder 7 constantly measures the position of the rod 7c of the work cylinder 7, that is, the position of the sliding plate 1a, and provides the measurement signal g to the excitation signal optimum setting control device 17, the work cylinder 7 Alternatively, if an unreasonable force is applied to the sliding plate 1a, the excitation signal optimum setting control device 17 limits the width of the excitation signal d to the oscillator 10.

In the above explanation, molten steel is taken as an example, but other molten metals may also be used.
2' is used, but it may be driven using only the servo cylinder 12, or the servo valve 13
There is no problem in driving the work cylinder 7 by connecting it to the work cylinder 7.

The present invention is not limited to a sliding nozzle, and as shown in FIG.
It may be a rotary type nozzle that adjusts the flow rate by rotating a rotary plate 107 that has an opening.

In addition, the vibration mechanism of the opening degree adjustment section is not limited to a hydraulic device, but may also be performed using an electric device, or may be vibrated mechanically. Furthermore, if a pouring device such as a sliding nozzle or rotary nozzle is attached to the pouring opening in the bottom layer of the ladle and the molten metal is injected into the tundish, and the weight is managed by a load cell to control the molten metal level, the opening The method of the present invention can also be used when the mold level is controlled by keeping the adjustment part constant and changing the slab drawing speed or the weight of molten metal in the tundish, or when these are combined. Of course, the method of the present invention can be used not only in the case of automatic injection control but also in the case of manual injection.

〔effect〕

As described in detail above, the present invention periodically changes the opening of the opening adjusting section based on the resistance that the opening adjusting section receives when changing the opening, centering on the opening set for hot water level control. molten metal is injected,
It is possible to suppress the insertion of bare metal and the adhesion and growth of the bare metal around the opening adjustment part, or to make the deposits fall off, and even when thermal distortion occurs in the opening adjustment part, it is possible to control the hot water level. It has excellent effects such as preventing a drop in responsiveness and controlling the hot water level with high precision.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention,
Figures 2 and 3 are graphs showing how to set the excitation signal, Figure 4 is a graph showing a control signal for controlling the molten metal level in the molten metal injection method of the present invention, and Figure 5 is a graph showing the control signal according to the present invention. A graph showing the hot water level control state, FIG. 6 is a schematic diagram showing another opening adjustment section to which the method of the present invention can be applied, FIG. 7 is an explanatory diagram of the conventional molten metal injection method, and FIG. A schematic diagram showing the structure of the opening adjustment part (sliding nozzle) and the state of solidification and adhesion of molten metal, Figure 9 is a graph showing the level control state of the conventional method, and Figure 10 is a graph of the other conventional method. FIG. 3 is an explanatory diagram of a method for injecting molten metal. 1... Sliding nozzle, 1a... Sliding plate, 17... Excitation signal optimum setting control device, 1
8, 19...Pressure detector, 20...Movement measuring device.

Claims (1)

[Scope of Claims] 1. A method for injecting molten metal into a predetermined container by periodically changing the opening degree of an opening adjustment section of an injection device that enables adjustment of the injection amount of molten metal, wherein the opening degree A method for injecting molten metal, characterized in that the adjustment section detects the resistance received when the opening degree is periodically changed, and changes the amplitude of the change based on the detected value. 2. In a method of injecting molten metal into a predetermined container by periodically changing the opening degree of an opening adjustment part of an injection device that enables adjustment of the injection amount of molten metal, the opening adjustment part adjusts the opening degree. 1. A method for pouring molten metal, comprising: detecting the resistance received when periodically changing the temperature and the level of the molten metal in the container; and changing the amplitude of the change based on each detected value.