JPH02142657A - Apparatus for controlling continuous casting process - Google Patents

Abstract

PURPOSE:To facilitate control at the time of continuously operating by providing gradient control means, which continuously executes the control to increasing rate of molten metal surface level, at the time of starting the continuous casting. CONSTITUTION:As a first molten metal surface level detecting means 10, a molten metal surface level sensor, which has good responsibility but narrow detecting range and easily develops variation of offset, is used. As a second molten metal surface level detecting means 12, a molten surface level sensor, which wide detecting range and to offset but some problem at point of the responsibility, is used. Then, at the time of starting up, by using a detector changing means 22, the molten metal surface level can be continuously measured with the second molten metal surface level detecting means 12 since low molten metal surface level. When the molten metal surface level comes to the detecting range of the first molten metal surface level detecting means 10, the second detecting means 12 is changed over to the first detecting means 10 and at the same time, the offset is corrected. Therefore, at the time of starting up, the molten metal surface rising speed is precisely controlled with the gradient control means 24 based on the level of the detecting means 12, and after shifting to continuous operation, the control means 20 executes the molten metal surface level control based on the molten metal surface level detected with the detecting means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting process control device for appropriately controlling a molten metal level in a continuous casting process.

[Conventional technology]

In continuous casting of steel, aluminum alloys, etc., molten metal is injected from above into a mold with open top and bottom, cooled from the side of the mold and partially solidified from the surface, and then sandwiched between rolls from below. Casting is performed continuously by cooling while drawing.

The level of hot water inside the mold is an important factor that greatly affects the quality of the product, so it must be precisely controlled. Therefore, the amount of hot water injected into the mold is controlled by PID control according to the hot water level detected by a sensor described below.

Several types of means for detecting the level of hot water inside a mold have been put into practical use. One of them is a vortex-type hot water level sensor. A transmitting coil and a receiving coil are installed above the hot water surface, and by passing a high-frequency current through the transmitting coil, an eddy current is generated on the surface of the hot water.This allows the strength and weakness of the current generated on the receiving coil side to be detected by the sensor and the hot water surface. The water level is detected by using the distance between the In addition, in a hot water level sensor using a temperature sensing element such as a thermocouple (for example, see Japanese Patent Application Laid-Open No. 62-54562), a large number of thermocouples are embedded in the depth direction in a copper plate on the side of the mold, and each thermocouple is The water surface level is calculated from the temperature indicated by . There are also systems that use T-rays to detect the hot water level.

The above-mentioned sensors are capable of continuously detecting the hot water level, but the electrode type hot water level sensor (Japanese Patent Laid-Open No. 17961
(described in Publication No. 2).

In addition, as a means to increase or decrease the amount of hot water injected into the mold, a tundish or gutter for temporarily storing or supplying hot water is installed above the mold, and a hole is installed at the bottom of the gutter to supply hot water to the mold. There are methods that increase and decrease the amount of injection by raising and lowering a rod-shaped stopper that can be installed and plug the hole, and methods that adjust the injection amount by restricting the supply path that supplies hot water to the mold with a sliding nozzle (SN) plate. .

By the way, when starting the operation of this continuous casting process, the bottom of the mold is covered with the head of a dummy par, hot water is injected, and when a predetermined level is reached, the dummy par is gradually pulled out from the bottom, and continuous operation begins. A transition will be made. In this case, when starting to pull out the dummy par, not only does the hot water level reach a predetermined level;
It is necessary that the elapsed time after the start of injection is within a predetermined range and that the coagulation state is appropriate. If this condition is not met,
If the formation of the solidified shell is insufficient, the solidified shell will break and a so-called breakout will occur, or conversely, the dummy par head will seize and the separation will be 11iI. In order to prevent such problems, a method of controlling the injection amount to achieve a predetermined level in a predetermined time is disclosed in, for example, JP-A-56-
68570, JP 58-84652, JP 62-54562, and JP 62-183.
It is described in Publication No. 952.

[Problem to be solved by the invention]

The more precisely the rate of rise of the hot water level at the start of operation can be controlled, the higher the product yield at the start of operation, and the smoother the transition to continuous operation thereafter, which improves productivity. do. For precise control, it is better for the control to be continuous, and for this purpose, it is necessary to continuously detect the hot water level from a low hot water level to the hot water level in continuous operation and feed it back to the control. can be said to be the best.

Examining the above-mentioned literature from the above perspective, we find that
The method described in Japanese Patent No. 8-84652 does not perform feedback control from the knee hot water level until the hot water level reaches the hot water level during continuous operation, and therefore there is no description of a hot water level detection means for this purpose.

JP-A-56-68570 and JP-A-62-183
Publication No. 952 also does not contain any clear description regarding such level detection means. Japanese Unexamined Patent Publication No. 62-54562 describes a hot water level detection means that continuously detects hot water level over a wide range and is composed of temperature sensing elements buried at appropriate intervals in the casting direction. Continuous control of the rising rate of the hot water level using this method is described.

However, there is a slight time delay when detecting the level using the thermosensor, and precise control after reaching the continuous operation level is not easy.

On the other hand, although there is no problem with the time delay in detecting the hot water level using the eddy current sensor mentioned above, it has the disadvantage that not only the detection range is not wide, but also bias is likely to occur due to shadows from temperature and the surrounding electromagnetic environment. ing.

Therefore, a first object of the present invention is to provide a continuous casting process control device that solves the above-mentioned problems at startup, provides a high yield at startup, and facilitates maintenance of quality thereafter.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the continuous casting process control device of the present invention. In the figure, the continuous casting process control device of the present invention includes a first melt level detection means 10 for detecting a melt level near the appropriate melt level during continuous operation in a continuous casting mold 50; Injected hot water amount increasing/decreasing means 14 increases or decreases the amount of hot water poured into the mold, and the first hot water level detecting means 10 adjusts the hot water level in the mold to the appropriate hot water level in accordance with the hot water level detected by the first hot water level detecting means 10. In a continuous casting process control device comprising a hot water level control means 20 for controlling an injection amount increase/decrease means, the hot water level is at least in a range lower than the range of the hot water level detected by the first hot water level detection means 10. A second molten metal surface level detection means 12 for detecting the level;
The second hot water level detection means 1 is selected when the hot water level exceeds a predetermined value.
2 to the first hot water level detecting means 10, and correcting the measured value of the first hot water level detecting means 10 with the measured value of the second hot water level detecting means 12 at the time of switching. The present invention is characterized in that it includes a device switching means 22 and a gradient control means 24 that continuously controls the amount of increase in the level of the molten metal at the start of continuous casting.

The following margins [Function] As the first hot water level detection means 10, a hot water level sensor, such as an eddy current sensor, which has good responsiveness but does not have a wide detection range and is prone to offset fluctuations, is used, and a second hot water level detection means 10 is used. If a hot water level sensor, such as a thermal lightning pair, which has a wide detection range and no offset but has a problem with responsiveness is used as the means 12, then the detector switching means 22 will set the second hot water level at startup. The detection means 12 can continuously measure the hot water level from a low level, and when it enters the detection range of the first hot water level detection means 10, the offset is corrected at the same time as switching. Therefore, at startup, the rising speed of the hot water level is precisely controlled by the slope control means 24 based on the hot water level detected by the second hot water level detection means 12, and after transition to continuous operation, the bias is corrected for the first hot water level detection means 12. Based on the hot water level detected by the hot water level detection means 10, the hot water level control means 20 precisely controls the hot water level.

〔Example〕

FIG. 2 is a diagram showing an example in which the control/arithmetic device according to the present invention is applied to a continuous steel casting process.

In this figure, a ladle 302 filled with molten steel is placed above the tundish 305, and the molten steel in the ladle 302 is poured into the tundish 305 through a sliding nozzle 303 at its bottom. The amount of molten steel in the tundish 305 is measured by measuring the entire weight of the tundish 5305 with a weight scale 304, and is kept at a constant value by feeding back to the opening degree of the sliding nozzle 303 via the tundish weight control device 301 that performs PID calculation. is maintained.

The molten steel in TANDAI SHU 5305 is TANDAI SHU 305.
When the stopper 143 that closes the bottom hole is driven by the cylinder 142 and moves upward, it is injected into the mold 501.

The bottom of the mold 501 is also open, and the molten steel therein is cooled by the side wall of the mold 501 to which cooling water is supplied, solidifies from the outside, and is continuously drawn out by the pinch rollers 402 while being further cooled. Since the inside of the mold 501 is empty at the start of casting, a dummy par (not shown) is used.
The bottom of the mold 501 is closed, and when the hot water level in the mold 501 reaches a predetermined value, the dummy par is gradually pulled out from below, and continuous operation begins. At the top of the mold is 1
A 54-flow type hot water level sensor 102 consisting of a pair of coils is provided, and its signal is converted to hot water level 1 by a clear stream level meter calculation device 101 and sent to a control calculation device 201. on the other hand,
Fourteen thermocouples 122 are embedded in the side wall of the mold in the depth direction, and the thermocouple level meter calculation device 121 converts the hot water level to level 2, which is sent to the control calculation device 201. Pinch roll drive device 401 drives pinch roll 402 according to a control signal from control calculation device 201.

The stopper driving device 141 moves the cylinder 142 and drives the stopper 143 according to the stopper opening signal from the control calculation device 20177-. The control calculation device 201 performs control calculations as will be described later and sends control signals to each device. The eddy current level meter calculation equipment 101 can input a calibration signal from the outside to correct the bias amount.

FIG. 3 is a diagram showing the movement of the old control/arithmetic device 2 of FIG. 2 at the start of casting. Column (1) in the figure is the deepest hole in Kundeitz 305, and column (2) is the stopper 14.
The third column shows the level of molten steel in the mold 501, and the fourth column shows the control state of the pinch roll 402. In addition, X on the right side of the third column indicates the measurement range of the eddy current type hot water level sensor 102, and Y indicates the measurement range of the thermocouple type hot water level sensor 102.
2 measurement range.

Control at the start of casting will be explained below with reference to FIGS. 2 and 3. Immediately before the start of casting, the bottom of the mold 501 is covered with the head of the dummy par, as described above. A ladle 302 filled with molten steel is a tundish 30
5, and when a predetermined control target value is set in the tundish weight control device 3, the sliding nozzle 303 opens and molten steel is injected into the tundish weight control device 305, and the molten steel is injected into the tundish weight control device 3. As shown in the figure, the level increases. The level of the tandish 5305 is set to the value “v” set in the tandish weight control device 301.
When VQl is reached, a control start signal is output, and the control arithmetic unit 201 starts a series of sequences. First, the opening degree of the stopper 143 is set to 5TOI (column M (2)), and molten steel is injected into the mold 501.
(Column (3))

When an electrode sensor (not shown) detects that the hot water level in the mold 501 has reached the LOI, the opening degree of the stopper 143 is set to 5TO2, which is smaller than 5TOI (column (2)). The hot water level inside mold 5 is L0.
3 ((3rd) column), when the thermocouple level sensor 122 detects that the level has become 3 ((3) column B), the control of the hot water level in the mold 501 shifts to gradient control ((3rd) column B). This calculates SV for each control period using the following equation, and performs PID control using this as the hot water level setting value.

Therefore, the hot water level rises continuously, and it is guaranteed that it reaches LO2 after the time TOI has elapsed. When the hot water level reaches LO2, the pinch roller 402 starts driving (column (4)), and the dummy par is pulled out.

When the hot water level further rises and reaches a predetermined value, the control shifts to constant value control ((3rd) column C) and enters continuous operation.

As shown in X and Y on the right side of column (3), the vortex type hot water level sensor 102 is located 20+nm to 200m from the top of the mold.
The thermocouple type hot water level sensor 122 has a range of 2 m.
A range from 0 mm to 350 mm can be measured. When the hot water level reaches a position 200 mm from the top, the thermocouple sensor 122 is automatically switched to the eddy current sensor 102, and at the same time, the bias of the indication of the eddy current sensor 102 is changed based on the indication from the thermocouple sensor 122 at that time. is corrected.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a continuous casting process control device that is capable of precise boiling-up control at startup and is easy to control during continuous operation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing a control state by the device shown in FIG. 2. 50, 501
...Mold, 102... Eddy current type hot water level sensor, 122... Thermocouple type hot water level sensor.

Claims (1)

[Claims] 1. A first melt level detection means (10) for detecting a melt level near the appropriate melt level during continuous operation in a continuous casting mold (50); ) and the first hot water level detection means (10) to adjust the hot water level in the mold to the appropriate hot water level according to the hot water level detected by the first hot water level detection means (10). In the continuous casting process control device, the continuous casting process control device includes at least the first hot water level detecting means (10) and a hot water level control means (20) for controlling the injected hot water amount increasing/decreasing means to maintain the level.
), which detects a hot water level in a lower range than the range detected by the second hot water level detecting means (12) at the start of continuous casting. ), and when the hot water level exceeds a predetermined value, the second hot water level detecting means (12) is switched to the first hot water level detecting means (10), and the corresponding one at the time of switching is selected. a detector switching means (22) for correcting the measured value of the first hot water level detecting means (10) with the measured value of the second hot water level detecting means (12); A continuous casting process control device comprising a gradient control means (24) that continuously controls the amount of increase in the level of the molten metal.