JP2003170257A - Method and device for detecting slag outflow - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for detecting a slag outflow capable of preventing wrong detection owing to the open-close operation of a sliding nozzle and an influence of deposits on the sliding nozzle in the continuous casting equipment having the sliding nozzle and also capable of detecting the slag outflow without any delay of detection. <P>SOLUTION: The device is for detecting the slag outflow in the continuous casting equipment 10 having the sliding nozzle 1b. The opening of the sliding nozzle is set up after considering deposits on the sliding nozzle 1b, by which the open-close operation of the sliding nozzle 1b originating in deposits on the sliding nozzle 1b is reduced and, based on the pressure of an inert gas sealed inside the feed nozzle 4 which guides the molten metal W to the tundish 2 from the ladle 1, the slag outflow can be detected. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a slag outflow detection method and a detection apparatus. More specifically, the present invention relates to a slag outflow detection method and a detection device for detecting outflow of slag from a ladle to a tundish in a continuous casting facility having a sliding nozzle.

[0002]

2. Description of the Related Art Conventionally, in the production of materials for processing mass-produced metal products, continuous casting has been performed from the viewpoint of quality stability and yield improvement. An example of the continuous casting equipment used for such continuous casting is schematically shown in FIG. The continuous casting equipment 10 includes a ladle 1 in which the molten metal W is stored, a tundish 2, a mold 3, a first supply nozzle 4 for guiding the molten metal W from the ladle 1 to the tundish 2, and the molten metal W. A second supply nozzle 5 for guiding the tundish 2 to the mold 3 is provided.

On the surface of the molten metal W in the ladle 1, as schematically shown in FIG. 5, slag S floats and forms a layer. When the slag S flows into the tundish 2, it is cast. Before the slag S flows out of the ladle 1, it is necessary to close the sliding nozzle 1b provided at the outflow port 1a at the bottom of the ladle 1 to stop the outflow of the molten metal W because the quality of the product deteriorates. In that case, if the outflow is stopped when a large amount of the molten metal W remains in the ladle 1, the yield will be reduced.

Therefore, in order to prevent both the quality deterioration and the yield deterioration of the cast product, the slag S is removed from the ladle 1
It is necessary to accurately detect the time when the molten metal starts to flow out and stop the flowing out of the molten metal W.

As a method for detecting the outflow of the slag S, a method based on human senses such as visual sense and tactile sense has been used for a long time, but it requires skill to perform the work, and there is a problem that the detection has individual differences. Therefore, various methods and devices for automatically detecting the outflow of the slag S have been proposed.

For example, in Japanese Unexamined Patent Publication No. 6-145756, a transmitter coil and a receiver coil are arranged so as to face each other at a first supply nozzle, and an alternating current is supplied to the transmitter coil to thereby cause the receiver coil to receive the same. A method for detecting based on a change in induced voltage has been proposed, and is disclosed in Japanese Patent Laid-Open No. 10-
Japanese Patent Laid-Open No. 10-272556 proposes a method of detecting based on the fluctuation of the molten metal upper surface position detected by a microwave level meter.
A method of detecting based on the amount of X-rays transmitted through the first supply nozzle has been proposed, and JP-A-7-16412 has been proposed.
Japanese Unexamined Patent Publication No. 4 (1994) proposes a method of detecting the vibration acceleration of the vibration generated in the first supply nozzle and detecting it based on the damping rate.

However, the method proposed in Japanese Patent Laid-Open No. 6-145756 has a problem that the detection accuracy is poor because the change of the induced voltage is small.

The methods proposed in Japanese Unexamined Patent Publication No. 10-80762 and Japanese Unexamined Patent Publication No. 10-272556 have a problem that the equipment becomes large and the equipment cost becomes high. In addition, the method proposed in Japanese Patent Laid-Open No. 10-272556 also has a problem that the health of the worker may be impaired by X-rays.

In the method proposed in Japanese Patent Application Laid-Open No. 7-164124, the slug outflow is determined based on the damping rate of the vibration acceleration of the impact fluid generated when the molten metal collides with the tundish molten metal surface in the first supply nozzle. Although it is detected, this shock fluid vibration is extremely weak, and thus there is a problem that erroneous detection occurs due to the influence of noise mixed in during transmission.

A continuous casting facility 10 as shown in FIG.
In order to prevent the oxidation of the molten metal W due to the entrainment of air (oxygen), the inert gas is often enclosed intermittently in the first supply nozzle 4, but the pressure of this enclosed inert gas is slag outflow. There is also proposed a detection method that pays attention to the fact that it fluctuates due to the above (for example, see Japanese Patent Publication No. 6-88127).

However, in the method of Japanese Patent Publication No. 6-88127, when the continuous casting equipment 10 is used intermittently, a gap is created at the joint between the ladle and the first supply nozzle, and the inert gas is filled. There is a problem in that the outflow of slag cannot be detected because of the leakage of water and nozzle clogging.

Further, in order to set the amount of hot water in the tundish 2 within a predetermined range, the sliding nozzle 1b is controlled within the range between the upper limit value and the lower limit value, as shown in FIG. Therefore, when the sliding nozzle 1b is opened / closed, the pressure of the inert gas fluctuates rapidly, resulting in erroneous detection.
Therefore, in order to prevent erroneous detection due to the opening / closing operation of the sliding nozzle 1b, the detection is not performed within a certain time after the opening / closing operation of the sliding nozzle 1b. That is, so-called mask processing is performed.
However, when such mask processing is performed, there is a problem that the detection of slag outflow is delayed when the outflow of slag is started within the period of this mask processing.

Further, when the opening / closing control as shown in FIG. 6 is performed, there is a problem that a predetermined amount of hot water cannot be supplied to the tundish 2 due to the deposit on the sliding nozzle 1b, as shown by the dotted line in FIG.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and in a continuous casting facility having a sliding nozzle, erroneous detection due to the opening / closing operation of the sliding nozzle and a substance adhering to the sliding nozzle. It is an object of the present invention to provide a slag outflow detection method and a detection device capable of detecting the outflow of slag with no detection delay while preventing the influence.

[0015]

The slag outflow detection method of the present invention is a method for detecting slag outflow in a continuous casting facility having a sliding nozzle, in which the opening of the sliding nozzle is set in consideration of deposits on the sliding nozzle. The opening and closing operation of the sliding nozzle due to the deposits on the sliding nozzle is reduced, and the slag of the slag is introduced based on the pressure of the inert gas enclosed in the supply nozzle that guides the molten metal from the ladle to the tundish. It is characterized by detecting outflow.

In the slag outflow detection method of the present invention,
It is preferable to set the opening of the sliding nozzle to a value obtained by performing a predetermined correction on the value calculated based on the weight of the tundish and the drawing speed of the cast metal.

Further, in the slag outflow detection method of the present invention, it is preferable that the slag outflow is started when the pressure fluctuation of the inert gas exceeds the threshold value. In that case, it is more preferable that the threshold value is a predetermined multiple of the standard deviation of the pressure detection value of the inert gas within a predetermined time after the start of the slag outflow detection operation.

Furthermore, in the slag outflow detection method of the present invention, it is preferable to judge the quality of the equipment immediately before the start of the slag outflow detection operation. In that case, if the pressure fluctuation of the inert gas when the sliding nozzle is opened and closed is within a predetermined range, it is determined that the equipment is defective.

On the other hand, the slag outflow detection device of the present invention is a slag outflow detection device in a continuous casting facility having a sliding nozzle, and is a slag outflow detection device for injecting an inert gas into a supply nozzle for introducing molten metal from a ladle to a tundish. A pressure detecting means for detecting the pressure, a molten metal amount detecting means for detecting the molten metal amount of the tundish, a drawing speed detecting means for detecting the drawing speed of the cast metal, and a control judging portion, and the control judging portion controls And a determination unit, the control unit has a sliding nozzle control means, calculated based on the detection values of the molten metal amount detection means and the drawing speed detection means, a predetermined for the opening of the sliding nozzle The opening of the sliding nozzle is controlled to the corrected opening,
The determination unit includes a molten metal residual amount determination unit and a slag outflow determination unit, and is configured to start the slag outflow detection operation when the molten metal residual amount of the ladle reaches a predetermined value.

In the slag outflow detection device of the present invention,
It is preferable that the determination unit further includes equipment quality determination means, and is configured to determine the quality of the equipment immediately before the start of the slag outflow detection operation.

[0021]

Since the present invention is configured as described above, it is possible to detect the outflow of slag by eliminating the influence of the opening / closing operation of the sliding nozzle caused by the deposits on the sliding nozzle.

Further, according to the preferred embodiment of the present invention, since the presence or absence of equipment failure of the casting equipment is judged before the slag outflow detection, it is possible to eliminate the inability to detect the slag outflow due to the equipment failure.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described based on the embodiments with reference to the accompanying drawings, but the present invention is not limited to such embodiments.

FIG. 1 shows a schematic diagram of a slag outflow detection device (hereinafter simply referred to as a detection device) to which a slag outflow detection method according to an embodiment of the present invention is applied. In the present embodiment, a case where the continuous casting equipment 10 described in the section of the related art is used as the continuous casting equipment will be described as an example.

As shown in FIG. 1, the detection device A includes a pressure sensor (pressure detection means) 20 for detecting the gas pressure (hereinafter, simply referred to as pressure) of the sealed inert gas, and the tundish 2 inside. A scale (molten metal amount detecting means) 30 for detecting the weight of the molten metal, a speedometer (drawing speed detecting means) 40 for detecting the drawing speed of the cast metal K from the mold 3, an opening control of the sliding nozzle 1b and other controls The main components are a control determination unit 50 that performs various determinations, an output unit 60 that outputs the determination result, and an alarm device 70.

The pressure sensor 20 outputs an electric signal having an intensity corresponding to the pressure of the enclosed inert gas to the control determination section 50, and the gas supply pipe 6 for supplying the inert gas into the first supply nozzle 4. It is installed in a predetermined position.

The weighing scale 30 is a load cell, which is installed at the bottom of the tundish 2 and outputs an electric signal having an intensity corresponding to the weight of the molten metal in the tundish 2 to the control determination section 50, for example, a load cell.

The speedometer 40 controls and determines the pulse signal at an interval corresponding to the rotation speed of the touch roller 41, which is brought into contact with the cast metal K so as to rotate according to the drawing of the cast metal K cast by the mold 3. An output to the unit 50, for example, a rotary encoder.

The control determination section 50 is provided with a control section 51 for controlling the opening / closing operation of the sliding nozzle 1b and other controls, and a determination section 52 for making various determinations described later.

The sliding nozzle control means 51a of the control unit 51 controls the weight scale 30 and the speed from the start of continuous casting until the remaining amount of molten metal in the ladle 1 reaches a predetermined amount and the slag outflow detection operation is started. The opening of the sliding nozzle 1b calculated based on each output signal of the total 40 is adjusted to the opening corrected by the opening correction formula, and the ladle 1 of the molten metal W is adjusted.
The amount of outflow from the tundish 2 to the tundish 2 is controlled. Here, the opening degree correction formula is based on the calculated opening degree of the sliding nozzle 1b.
In consideration of the degree to which the opening of b is blocked by the adhered matter, the opening is corrected to be larger than the calculated opening by a predetermined amount. In this case, the opening degree correction formula is used to adjust the opening degree of the sliding nozzle 1b in accordance with the growth because the deposits on the sliding nozzle 1b grow over time. The opening correction formula is determined by, for example, an experiment.

Specifically, the control of the sliding nozzle 1b by the sliding nozzle control means 51a eliminates the deviation of the actual amount of hot water of the tundish 2 obtained from the weight scale 30 from the optimum amount of hot water (target value), and Speedometer 4
The opening of the sliding nozzle 1b is calculated so that the amount of hot water flowing out from the tundish 2 calculated based on the output of 0 is calculated, and then the calculated opening is corrected by the opening correction formula. It is done by taking a degree.

The determination unit 52 determines whether or not there is equipment failure in the continuous casting equipment 10 based on the output signal of the pressure sensor 20 and the output signal of the speedometer 40. Molten metal residual amount determination means 52b for determining whether or not the residual amount of molten metal in the pot 1 has reached a predetermined amount, and slag outflow determination for determining whether or not slag is flowing out based on the output signal of the pressure sensor 20. And means 52c.

The equipment quality judgment unit 52a is specifically based on the fluctuation of the pressure of the enclosed inert gas detected by the pressure sensor 20 when the sliding nozzle 1b is opened and closed to change the outflow amount of the molten metal W. It is to determine whether or not there is equipment failure such as nozzle clogging of the sliding nozzle 1b or gas leakage in the continuous casting equipment 10. Note that this determination is made immediately before the slag outflow detection operation.

More specifically, when there is no equipment failure, the detection value of the pressure sensor 20 also changes in response to opening and closing of the sliding nozzle 1b, as shown in FIG. 2 (a). 2B, the detection value of the pressure sensor 20 hardly changes even if the sliding nozzle 1b is opened and closed, as shown in FIG. 2B. Therefore, the equipment quality determination means 52a determines that the equipment is defective if the variation in the detection value of the pressure sensor 20 when the sliding nozzle 1b is opened and closed falls within a preset evaluation range J, and falls within the evaluation range J. If not, the equipment is judged to be good. Here, the evaluation range J is 1 to 1 of the standard deviation of the pressure fluctuation width of the inert gas after the sliding nozzle control means 51a instructs the sliding nozzle 1b to be closed.
In the triple range, it is appropriately set based on the operation results.

The molten metal residual quantity determining means 52b obtains the total amount of the cast metal K drawn based on the output signal of the speedometer 40, calculates the residual amount of the molten metal in the ladle 1 from the total drawn amount, and the residual molten metal It is determined whether or not the amount has reached the molten metal amount at which detection of slag outflow is started.

The slag outflow determining means 52c performs a predetermined process on the detection value of the pressure sensor 20 to determine whether or not the slag is outflowing.

Specifically, since the pressure of the enclosed inert gas depends on the density of the fluid flowing out of the ladle 1, when the slag S having a density different from that of the molten metal W begins to flow out, it is shown in FIG. 3 (a). Thus, the pressure of the inert gas changes rapidly. Therefore, as shown in FIG. 3B, the detected gas pressure is subjected to a predetermined process to extract the fluctuation thereof, and the time when the fluctuation exceeding the threshold value is detected is detected as the slag outflow starting point.

More specifically, the detected pressure of the inert gas is filtered to remove high frequency components, and the variation is extracted by the difference and the interval integration, and a variation exceeding the threshold value occurs. The time point is determined as the slag outflow starting point. Here, the threshold value is 3 to 4 times, preferably 3.2 times the standard deviation of the pressure value detected within a predetermined time, for example, 120 seconds from the time when the gas pressure for slag outflow determination is detected. It is said that
Here, the period of time is within the above-mentioned time, because the change in gas pressure when the slag starts to flow out is similar to the change in gas pressure when the sliding nozzle 1b is closed, so that the opening / closing operation of the sliding nozzle 1b causes the gas to change. This is because the delay time until the pressure changes and becomes stable is 5 to 6 times. The change in gas pressure due to the operation of the sliding nozzle is excluded from the calculation of the standard deviation. In addition, 3 to 4 times, preferably 3.2 times the standard deviation indicates that statistically, it is obvious that the value exceeds 3 times the standard deviation, and slag mixing and sliding nozzle 1b opening / closing are obvious. This is because it is abnormal.

The control determination unit 50 having such a function is provided in the computer having the output unit 60, for example, and the control unit 51 and the determination unit 52 are provided with the respective units 52a to 52c.
It is realized by storing a program corresponding to the function, that is, a control program including a sliding nozzle control program, a facility quality determination program, a molten metal remaining amount determination program, a slag outflow determination program, and the like.

The output means 60 is, for example, a printer or a CRT.
The alarm device 70 is a display or the like, and issues an alarm in response to a command from the control unit 51.

Next, the detection device A having such a configuration
The slag outflow detection by will be described with reference to the flowchart shown in FIG. In addition, reference numeral S1 in FIG.
-S12 shows a step number.

(1) Start continuous casting. (Step 1)

(2) Tundish 2 from scale 30
The weight of the molten metal inside and the drawing speed from the speedometer 40 are input to the control determination unit 50. (Step 2)

(3) The control unit 51 calculates the opening of the sliding nozzle 1b based on the molten metal weight and the drawing speed input to the sliding nozzle control means 51a. (Step 3)

(4) The control section 51 controls the sliding nozzle 1 calculated by the sliding nozzle control means 51a.
The opening of b is corrected by the opening correction formula. (Step 4)

(5) The controller 51 adjusts the opening of the sliding nozzle 1b to the corrected opening. (Step 5)

(6) The determination unit 52 calculates the remaining amount of molten metal in the ladle 1 based on the drawing speed input to the remaining molten metal determination output means 52b. (Step 6)

(7) The determination unit 52 causes the molten metal remaining amount determination output means 52b to determine whether or not the calculated molten metal remaining amount has reached a predetermined amount. (Step 7)

(8) In the judgment of (7), when it is judged by the molten metal remaining amount judging means 52b that the predetermined amount has not been reached, the process returns to (6) and the operations thereafter are repeated.

(9) In the determinations of (7), when it is determined by the molten metal remaining amount determining means 52b that the predetermined amount has been reached, the process proceeds to the next step (step 8).

(10) The gas pressure of the enclosed inert gas from the pressure sensor 20 is input to the control determination unit 50. (Step 8)

(11) The judging section 52 judges the presence or absence of equipment failure based on the gas pressure input to the equipment quality judging means 52a. (Step 9)

(12) If the equipment quality determination means 52a determines that equipment failure exists in the determinations in (11) and (11), the control unit 51 issues an alarm and stops casting if necessary. (Step 10)

(13) In the judgment of (11), when it is judged by the equipment quality judging means 52a that there is no equipment defect, the process proceeds to the next step (step 11).

(14) The gas pressure of the enclosed inert gas from the pressure sensor 20 is input to the control determination unit 50. (Step 11)

(15) The judging section 52 judges whether or not there is slag outflow based on the gas pressure input to the slag outflow judging means 52c.

(16) If the slag outflow determining means 52c determines that the slag outflow has not occurred in the determinations in (15), the process returns to (14) and the subsequent steps are repeated.

(17) If the slag outflow determining means 52c determines that the slag outflow has occurred in the determinations (17) and (15), the controller 51 causes the casting to stop. (Step 12)

As described above, in this embodiment, the opening of the sliding nozzle 1b, which is calculated based on the weight of the molten metal and the drawing speed, is corrected by the opening correction formula. It is possible to suppress a decrease in the amount of hot water supplied to the tundish 2, or it is possible to avoid clogging of the opening portion due to deposits on the sliding nozzle 1b. Therefore, the sliding nozzle 1b caused by the deposits on the sliding nozzle 1b
It is possible to eliminate the opening / closing operation of (1) and thereby reduce the dead zone due to so-called mask processing. Along with this, the accuracy of detecting the outflow of slag is improved.

Since the presence or absence of equipment failure of the continuous casting equipment 10 is determined prior to the slag outflow detection operation,
Undetectable slag outflow due to equipment failure can be eliminated.

The present invention has been described above based on the embodiments, but the present invention is not limited to such embodiments, and various modifications can be made.

For example, in the present embodiment, the opening of the sliding nozzle 1b is corrected by the opening correction formula. However, for example, an opening correction map is stored in the control determination unit 50 and the map is referred to. The opening may be corrected.

[0063]

As described in detail above, according to the present invention,
It is possible to obtain the excellent effect that the slag outflow can be detected by eliminating the influence of the opening / closing operation of the sliding nozzle caused by the deposits on the sliding nozzle.

Further, according to the preferred embodiment of the present invention, since the presence or absence of equipment defect of the casting equipment is judged immediately before the slag outflow detection, it is possible to eliminate the inability to detect the slag outflow due to the equipment defect. Is obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a slag outflow detection device applied in a slag outflow detection method according to an embodiment of the present invention.

2A and 2B are detection waveforms of a gas pressure of an enclosed inert gas when a sliding nozzle is opened and closed, in which FIG. 2A shows a waveform in a poor equipment state, and FIG. 2B shows a waveform in a good equipment state. Show.

FIG. 3 is an explanatory diagram of a slag outflow principle based on a gas pressure change of an enclosed inert gas, in which (a) shows a graph such as a detection waveform of gas pressure and (b) shows detected gas. The graph of the pressure fluctuation extraction waveform etc. which extracted the pressure fluctuation is shown.

FIG. 4 is a flowchart showing an example of a slag outflow detection procedure.

FIG. 5 is a schematic view of a conventional continuous casting facility.

FIG. 6 is a graph schematically showing an opening / closing pattern of a sliding nozzle in the same equipment.

[Explanation of symbols]

1 ladle 1b sliding nozzle 2 tundish 3 molds 4 First supply nozzle 5 Second supply nozzle 10 Continuous casting equipment 20 Pressure sensor (pressure detection means) 30 Weight scale (molten metal amount detection means) 40 Speedometer (withdrawal speed detection means) 50 Control determination unit 51 control unit 52 Judgment unit 52a Equipment quality judging means 52b Molten metal remaining amount determination means 52c Slag outflow determination means 60 Output means 70 Alarm means A Slag outflow detector S slug W molten metal

Continued front page    (72) Inventor Takahiro Miyazaki             39 Motomoto-cho, Tokai City, Aichi Prefecture Daido Steel Co., Ltd.             Ceremony Company Chita Factory F-term (reference) 4E004 FA10 FB10 HA01 MB09 MB19                       PA06

Claims (8)

[Claims] 1. A method for detecting slag outflow in a continuous casting facility having a sliding nozzle, wherein the opening of the sliding nozzle is set to an opening that considers the deposit on the sliding nozzle, and the deposit on the sliding nozzle is set accordingly. A method for detecting outflow of slag, which is characterized by reducing the opening / closing operation of the sliding nozzle, and detecting the outflow of slag based on the pressure of the inert gas sealed in the supply nozzle that guides the molten metal from the ladle to the tundish. . 2. The opening of the sliding nozzle is set to a value obtained by applying a predetermined correction to a value calculated based on the weight of the tundish and the drawing speed of the cast metal. Slag outflow detection method. 3. The slag outflow detection method according to claim 1, wherein the slag outflow is started when the pressure fluctuation of the inert gas exceeds a threshold value. 4. The slag outflow detection according to claim 3, wherein the threshold value is a predetermined multiple of a standard deviation of the pressure detection value of the inert gas within a predetermined time after the start of the slag outflow detection operation. Method. 5. The slag outflow detection method according to claim 1, wherein the quality of the equipment is judged immediately before the start of the slag outflow detection operation. 6. The slag outflow detection method according to claim 5, wherein if the pressure fluctuation of the inert gas when the sliding nozzle is opened and closed is within a predetermined range, it is determined that the equipment is defective. 7. A slag outflow detection device in a continuous casting facility having a sliding nozzle, comprising pressure detection means for detecting the pressure of an inert gas sealed in a supply nozzle for introducing molten metal from a ladle to a tundish.
A molten metal amount detecting means for detecting the molten metal amount of the tundish,
It comprises a drawing speed detecting means for detecting the drawing speed of the cast metal, and a control judgment part, the control judgment part has a control part and a judgment part, the control part has a sliding nozzle control means, and the molten metal The opening of the sliding nozzle is controlled to an opening obtained by performing a predetermined correction on the opening of the sliding nozzle, which is calculated on the basis of the detection values of the amount detecting means and the drawing speed detecting means, and the determining unit is the molten metal. A slag outflow detection device, comprising: a remaining amount determination means and a slag outflow determination means, wherein the slag outflow detection operation is started when the remaining amount of molten metal in the ladle reaches a predetermined value. 8. The slag outflow detection device according to claim 7, wherein the determination unit further has equipment quality determination means, and is configured to determine the quality of the equipment immediately before the start of the slag outflow detection operation. .