JP2010149132A - Method for measuring level of molten steel in mold of continuous casting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring the level of a molten steel in a mold of a continuous casting apparatus using a vortex flow type level indicator free from the need of hot compensation and applicable even to the one for autostart. <P>SOLUTION: Regarding a method where the level of a molten steel in the mold 11 of the continuous casting apparatus is measured using a vortex flow type level indicator 10, a detector 12 in the vortex flow type level indicator 10 is fixed to a beforehand set installment place, a simulation molten metal surface material magnetically equivalent to a molten steel surface is charged to the inside of the mold 11, while performing elevation, the height position of the surface of the simulation molten metal surface material is detected by the vortex flow type level indicator 10. The output standard properties showing relation between the height position of the molten steel surface in the mold 11 and the output value of the detector 12 are beforehand obtained. Before continuous casting is started, while changing the position of the detector 12, a specific position at which the output value output from the detector 12 is coincident with the output value, in the case the molten steel is not present in the mold 11, estimated from the output standard properties is obtained, and the detector 12 is fixed to the specified position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for measuring a molten steel level in a mold of a continuous casting facility using an eddy current level meter.

For example, in the continuous casting equipment 100 shown in FIG. 3, the molten steel 104 is injected from the ladle (ladder) 102 to the tundish 103 by opening the ladle molten steel discharge operation end 101, and then from the tundish 103 through the immersion nozzle 105. The molten steel 104 is poured into the mold 106 to continuously produce the slab 107. In the continuous casting process, the molten steel surface level position (molten steel surface level) 108 in the mold 106 is detected by a molten steel level meter 109, and the detected molten steel surface level 108 signal is a molten steel level meter amplifier 110. Is input to the molten steel level control calculation unit 111. Further, the molten steel level control calculation unit 111 performs a control output to the stopper drive control device 112 based on the inputted molten steel surface level 108 signal. In response to this control output, the stopper drive control device 112 controls the stopper drive device 113 made of a hydraulic cylinder or the like to adjust the molten steel 104 flowing into the mold 106 from the tundish 103 by moving the stopper 114 made of refractory up and down. Then, the molten steel surface level 108 in the mold 106 is controlled to be stable.

Here, as the molten steel level meter, a vortex type level meter having a small (fast) and high accuracy is often used. However, since the detector of the eddy current level meter is installed at a preset installation location above the mold, the magnetic coupling with the mold is stronger than the molten steel surface, and the positional relationship between the detector and the mold Changes, the magnetic environment received by the detector changes, and the output value indicating the molten steel surface level in the mold measured by the detector also changes. In addition, when using an eddy current level meter during actual continuous casting operation, the detector is removed from the installation location when continuous casting is completed, and is reattached to the installation location before the next continuous casting is started. . As a result, the mounting position of the detector at the installation location inevitably changes minutely every time continuous casting is performed, and the magnetic environment received by the detector also changes every time continuous casting is performed. There arises a problem that reproducibility cannot be obtained in the relationship between the molten steel level and the output value of the detector. For this reason, it is not possible to perform auto-start that automates the initial stage of casting during continuous casting operation using the molten steel surface level measured by the eddy current level meter. Before installation and continuous casting, the molten steel level of the molten steel injected into the mold is measured using another level meter, and the output value corresponding to the measured molten steel level is an eddy current level meter. Therefore, it is necessary to perform hot correction of the eddy current level meter.

Therefore, in Patent Document 1, a data table indicating the relationship between the distance from the detector to the molten steel surface level and the output value of the detector by attaching the detectors of the eddy current level meter to a plurality of positions at the installation site is provided in advance. In addition, an electrode sensor is installed in the mold to detect that the molten steel level of the injected molten steel has reached a preset height position, and the molten steel level in the mold is preset. From the data table when the measured value Vm output from the eddy current level meter and the molten steel surface level are at a preset height position when it is detected by the electrode sensor that it has reached the height position. It is disclosed that a normalization coefficient composed of Vm / Vd is obtained from the obtained data value Vd, and hot correction of the eddy current level meter is performed by multiplying the measured value of the eddy current level meter by the normalization coefficient.

Patent Document 2 also uses a eddy current level meter and a thermocouple level meter to measure the molten steel surface level in the mold at the initial casting stage, where the eddy current level meter cannot be applied, using a thermocouple level meter. When the molten steel level in the mold rises, hot correction of the eddy current level meter using the thermocouple level meter can be performed to switch from the thermocouple level meter to the eddy current level meter. It is disclosed.
Furthermore, in Patent Document 3, a specific frequency of a sound wave that resonates at a specific molten steel surface level in the mold is obtained in advance, and a sound wave of a specific frequency is constantly transmitted toward the mold from the start of casting, The sound wave reflected at the specific frequency is received and the intensity level is constantly measured. The molten steel surface level at the time when the intensity level exceeds a predetermined threshold is defined as the specific molten steel surface level. It is disclosed that hot correction of an eddy current level meter is performed at a molten steel surface level.

JP 2002-331342 A JP 2003-251445 A JP 2006-192473 A

However, in the invention described in Patent Document 1, an electrode sensor for actually measuring the molten steel surface level is required, and when the auto start is started, the electrode sensor becomes a consumable because it is immersed in the molten steel. There is a problem that an error occurs in the hot correction of the eddy current level meter in a situation where the rising speed of the molten steel surface level is fast because there is a time difference between the detection time of this and the processing end time. On the other hand, in the invention described in Patent Document 2, the molten steel surface level in the casting mold required for auto-start is in a range that can be measured with an eddy current level meter, and is more responsive than the eddy current level meter. However, there is a problem that an error occurs in the hot correction of the eddy current type level meter by using the thermocouple type level meter which is bad.

Further, in the inventions described in Patent Documents 2 and 3, since the hot correction of the eddy current level meter is performed with one actually measured value, there is a problem that the error increases as the distance from the actually measured value increases as shown below. .
When measuring the molten steel level, attach a detector of the eddy current level meter to the installation location, and calibrate the eddy current level meter (relationship of the output value from the detector to the distance between the detector and the molten steel level). Is obtained). The reference characteristic Vn obtained at that time is shown in FIG. Here, when mounting the detector at the installation position and starting continuous casting, if the position of the mounted detector is closer to the copper plate of the mold than at the time of calibration, the detector and the molten steel surface level The characteristic indicating the relationship of the output value from the detector with respect to the distance is Vb. When the position of the attached detector is moved away from the copper plate of the mold as compared with the time of calibration, the characteristic is relative to the distance between the detector and the molten steel surface level. The characteristic indicating the relationship between the output values from the detector is Va.

For this reason, for example, when the position of the attached detector is away from the copper plate of the mold as compared with the time of calibration, the hot correction of the eddy current level meter measures the level of one molten steel in the mold. The molten steel level meter amplifier so that the output value of the detector based on the characteristic Va corresponding to the measured molten steel surface level (for example, −100 mm) matches the output value of the detector based on the reference characteristic Vn. adjust. For this reason, as shown in FIG. 4, the characteristic Va becomes a characteristic Vac shifted upward (high power side) over the entire region, and the characteristic Vac and the reference characteristic Vn are identical except for the actually measured molten steel surface level. In addition, the difference increases as the distance from the measured molten steel surface level increases.

Furthermore, as in Patent Documents 1 to 3, when the molten steel surface level is measured using another level gauge, the degree of freedom in mold design is reduced due to the need to secure the installation space for the other level gauge, Since an auxiliary device (for example, an electromagnetic stirring device in a mold) is attached to the, a problem arises that it is not possible to secure an installation space for another level meter. In addition, when another level meter can be installed, in addition to the cost increase due to the combined use of the level meter, a strong magnetic field is generated when an electromagnetic stirring device in the mold is installed. It is necessary to take measures against noise due to the influence of the device, and there is a problem that device management becomes complicated.

The present invention has been made in view of such circumstances, and provides a method for measuring the molten steel level in a mold of a continuous casting facility using a vortex type level meter that is not required for hot correction and can also be applied to auto start. Objective.

In the method for measuring the molten steel level in the mold of the continuous casting equipment according to the present invention in accordance with the above object, the method of measuring the molten steel level in the mold of the continuous casting equipment using a vortex type level meter,
The detector of the eddy current type level meter is fixed at a preset installation location, and a simulated molten metal surface magnetically equivalent to the molten steel surface is inserted into the mold and moved up and down while moving the simulated molten metal surface. The height position of the surface is detected by the eddy current level meter, and the output reference characteristic indicating the relationship between the height position of the molten steel surface in the mold and the output value of the detector is obtained in advance.
Before starting continuous casting, the output value output from the detector while changing the position of the detector matches the output value when no molten steel is present in the mold as expected from the output reference characteristics. The specific position to be obtained is obtained, and the detector is fixed to the specific position.

In the method for measuring a molten steel level in a mold of a continuous casting facility according to the present invention, the position of the detector can be changed by adjusting a horizontal distance between the detector and the mold.

In the method for measuring the molten steel level in the mold of the continuous casting equipment according to the present invention, the eddy current level meter in which the detector is fixed at the specific position is the height position of the molten steel surface in the mold at the start of continuous casting. It can be used as a molten steel level meter for autostart to measure.

In the method for measuring the molten steel level in the mold of the continuous casting equipment according to the present invention, before starting the continuous casting, the position of the detector of the eddy current level meter is changed, and the output value output from the detector is the output standard. Since the detector is fixed at a specific position that matches the output value expected from the characteristics, the height position of the molten steel surface in the mold is set to the start point of continuous casting using the eddy current level meter without hot correction. Can be measured continuously from the end to the end.

In the method for measuring the molten steel level in the mold of the continuous casting equipment according to the present invention, when the position of the detector is changed by adjusting the horizontal distance between the detector and the mold, the position adjustment of the detector can be easily and accurately performed. It can be carried out.

In the method for measuring the molten steel level in the mold of the continuous casting equipment according to the present invention, when the eddy current level meter with the detector fixed at a specific position is used as the molten steel level meter for auto start, the molten steel in the mold at the start of continuous casting Since the change in the height position of the hot water surface can be accurately measured with good responsiveness, the auto start can be performed reliably and stably.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory view of a detector of an eddy current type level meter to which the molten steel level measuring method in a mold of a continuous casting facility according to an embodiment of the present invention is applied, and FIG. 2 is an embodiment of the present invention. It is explanatory drawing of the molten steel level measuring method in a mold of the continuous casting equipment which concerns on this.

As shown in FIG. 1, the eddy current level meter 10 to which the molten steel level measuring method in the mold of the continuous casting equipment according to one embodiment of the present invention is applied is the height of the molten steel surface in the mold 11 of the continuous casting equipment. A detector 12 for detecting the position, a detector holding means 13 for fixing the detector 12 to a preset installation location with respect to the mold 11, and a height position of the molten steel surface detected by the detector 12. It has an eddy current level meter amplifier 14 that outputs a signal to be shown toward a molten steel level control calculation unit (not shown) of the continuous casting facility.

Furthermore, the eddy current type level meter 10 is configured to set the height position of the surface of the simulated molten metal surface while charging and lowering the simulated molten metal material (not shown) magnetically equivalent to the molten steel surface in the mold 11. Detected by a detector 12 fixed at a preset installation location, and obtained and stored an output reference characteristic indicating the relationship between the height position of the molten steel surface in the mold 11 and the output value of the detector 12. A data storage unit having a function, a calibration command unit having a function of outputting a command signal for starting measurement of the height position of the molten steel surface in the mold 11 by the detector 12 before the start of continuous casting, and a command In response to the signal, the output reference characteristic is read from the data storage unit, and the output value V indicating the height position of the molten steel surface in the mold 11 output from the detector 12 is estimated from the output reference characteristic. _Detector to _{ensure that} it matches the output value V _n∞ when no molten steel is present. A specific position determination unit having a function of operating the holding means 13 to adjust a horizontal distance between the detector 12 and the mold 11 to obtain a specific position (specific horizontal position) and outputting a signal of the specific position; In response to the position signal, the operation of the detector holding means 13 is stopped, and the detector position calibrating means 15 having a calibration end unit having a function of fixing the detector 12 to a specific position is provided. Here, the detector position calibration means 15 can be formed, for example, by mounting a program that expresses each of the above functions on a microcomputer.

The detector holding means 13 supports the detector 12, supports the support member 16 horizontally, fixes the vertical position of the detector 12, and moves the detector 12 in the horizontal direction with respect to the mold 11. And a servo controller 21 for operating the servo mechanism 17. The servo mechanism 17 includes a screw screw 19 that is rotated by a motor 18, and a female screw portion 20 that is provided on the support member 16 and is screwed with the screw screw 19. The servo controller 21 has a function of outputting an operation signal of the motor 18 so that the deviation between the output value V of the detector 12 and V _n∞ becomes 0, and a function of driving the servo mechanism 17 by manual operation. I have. The servo controller 21 can be formed, for example, by mounting a program that exhibits the above functions on a microcomputer.

Then, the measuring method of the molten steel level in a mold of the continuous casting equipment which concerns on one embodiment of this invention is demonstrated.
First, the detector 12 of the eddy current level meter 10 is fixed at a predetermined installation location, and a simulated hot water surface magnetically equivalent to the molten steel surface is inserted into the mold 11 and moved up and down while being simulated. It is detected by the detector 12 the height position of the surface of the face material, seeking output reference characteristic V _n indicating the relationship between the output value of the detector 12 and the height position of the molten steel surface in the mold 11, the detection The data is stored in the data storage unit of the instrument position calibration means 15.

When starting continuous casting, first, as shown in FIG. 1, the detector 12 is attached to the detector holding means 13 and disposed above the mold 11. Next, for example, a calibration start switch provided in the calibration command section of the detector position calibration means 15 is turned on, and a command signal for starting the measurement of the height position of the molten steel surface in the mold 11 is output by the detector 12. Then, the height position of the molten steel surface in the mold 11 is measured by the detector 12. Since no molten steel exists in the mold 11, the output value V _∞ when the molten steel does not exist in the mold 11 is obtained from the detector 12.

Here, the position of the detector 12 is different from the position of the detector when the calculated output reference characteristic V _n indicating the relationship between the output value of the detector 12 and the height position of the molten steel surface in the mold 11 ing. For example, as shown in FIG. 2, if the detector 12 is away to one of the copper plate of the mold 11 from the position of the detector when the calculated output reference characteristic V _n is molten steel surface in the mold 11 relationship between the height position and the output value of the detector 12 is approaching to one of the copper plate of the mold 11 from the position of the detector when the next characteristic Va, the detector 12 has determined the output reference characteristic V _n In this case, the relationship between the height position of the molten steel surface in the mold 11 and the output value of the detector 12 becomes the characteristic Vb, which is different from the output reference characteristic Vn. Since the magnetic properties of the molten steel are equivalent to the magnetic properties of the copper plate forming the mold 11, when the molten steel surface level is 0, that is, when the molten steel contacts the detector 12, the detector 12 and the mold 11 are used. Even if the distance from the copper plate is different, the output value from the detector 12 is the same. When the molten steel surface level is −∞, that is, when the molten steel is not present in the mold 11, output values (V _a∞ , V _a∞ , which vary depending on the distance from the detector 12 to the detector 12 and the copper plate of the mold 11. _Vb∞ ) is obtained.

Therefore, the output value V _∞ when no molten steel is present in the mold 11 output from the detector 12 is the output value V _n∞ when no molten steel is present in the mold 11 predicted from the output reference characteristic V _n. Is different. For this reason, the specific position determination unit of the detector position calibration means 15 receives the command signal, reads the output reference characteristic V _n from the data storage unit, and outputs the output value V _{∞ of the} detector 12 from the output reference characteristic V _n. The detector holding means 13 is operated so as to match the expected output value V _n∞ to adjust the horizontal distance between the detector 12 and the mold 11. For example, in the case of the output value V _∞ <output value V _N∞, to indicate the characteristics Va detector 12 is away from the one of the copper plate of the mold 12 from the position of the detector 12 when the calculated output reference characteristic, output value V _∞ is the detector 12 such that the V _N∞ moves the detector 12 so as to approach the one of the copper plate of the mold 12. On the other hand, when the output value V _∞ > the output value V _n∞ , since the detector 12 approaches the one copper plate of the mold 12 from the position of the detector 12 when the output reference characteristic is obtained, the characteristic Vb is shown. detector 12 as the value V _∞ is the V _N∞ moves the detector 12 away from one of the copper plate of the mold 12. Then, a specific horizontal position of the output value V _∞ is equal to the output value V _N∞, and outputs a signal at a particular position.

When a signal at a specific position is input to the calibration end section of the detector position calibration means 15, the calibration end section stops the operation of the detector holding means 13 and fixes the detector 12 at a specific horizontal position. Thereby, the position of the detector 12 coincides with the position of the detector 12 when the output reference characteristic V _n is obtained, and the relationship between the height position of the molten steel surface in the mold 11 and the output value of the detector 12. _Corresponds to the output reference characteristic V _n . As a result, the height position of the molten steel surface in the mold 11 can be accurately measured continuously from the start point to the end of continuous casting using the eddy current level meter 10 without performing hot correction. . Since the eddy current level meter 10 can accurately measure the change in the height position of the molten steel surface in the mold 11 with high responsiveness, it can also be used as a molten steel level meter for auto start. Can be performed reliably and stably.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above-described embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included.
For example, while offline, using a mold or a simulated mold, the height position of the surface of the simulated molten metal surface is detected with an eddy current level meter while inserting the simulated molten metal surface into the mold or the simulated mold and moving up and down, The output reference characteristic may be obtained.
Further, the attached handwheel screw instead of the motor, the output value in the case when the molten steel into a mold, which is expected from the output value V _∞ and output reference characteristic is outputted from the detector 12 does not exist V _N∞ provided display respectively displaying a position of the detector by operating the handwheel so that the output value V _∞ is equal to the output value V _N∞ may be moved to a specific position.
The position adjustment of the detector of the present invention is performed in a horizontal plane including the point _where the output reference characteristic V _n is obtained. The method for adjusting and installing the detector according to the present invention does not limit the adjusting means. For example, the method is performed by driving the servo mechanism 17 by manual operation using a servo controller 21 as shown in FIG. Alternatively, it may be installed and adjusted by an operator by hand.

It is explanatory drawing of the detector of the eddy current type level meter to which the molten steel level measuring method in the casting_mold | template of the continuous casting equipment which concerns on one embodiment of this invention is applied. It is explanatory drawing of the molten steel level measuring method in a mold of the continuous casting equipment which concerns on one embodiment of this invention. It is explanatory drawing of the detector of the conventional eddy current type level meter which measures the molten steel level in the casting_mold | template of a continuous casting installation. It is explanatory drawing which shows the method of the conventional hot correction | amendment of an eddy current type level meter.

Explanation of symbols

10: Eddy current level meter, 11: Mold, 12: Detector, 13: Detector holding means, 14: Eddy current level meter amplifier, 15: Detector position calibration means, 16: Support member, 17: Servo mechanism, 18 : Motor, 19: Screw screw, 20: Female screw part, 21: Servo controller

Claims (3)

In the method of measuring the molten steel level in the mold of the continuous casting equipment using a vortex type level meter,
The detector of the eddy current type level meter is fixed at a preset installation location, and a simulated molten metal surface magnetically equivalent to the molten steel surface is inserted into the mold and moved up and down while moving the simulated molten metal surface. The height position of the surface is detected by the eddy current level meter, and the output reference characteristic indicating the relationship between the height position of the molten steel surface in the mold and the output value of the detector is obtained in advance.
Before starting continuous casting, the output value output from the detector while changing the position of the detector matches the output value when no molten steel is present in the mold as expected from the output reference characteristics. A method for measuring a molten steel level in a mold of a continuous casting facility, wherein a specific position to be obtained is obtained and the detector is fixed at the specific position. 2. The continuous casting equipment according to claim 1, wherein the position of the detector is changed by adjusting a horizontal distance between the detector and the mold. Of molten steel level in mold. 3. The method for measuring molten steel level in a mold of a continuous casting facility according to claim 1, wherein the eddy current level meter in which the detector is fixed at the specific position is placed in the mold at the start of continuous casting. A method for measuring a molten steel level in a mold of a continuous casting facility, characterized by being used as a molten steel level meter for auto-start that measures the height position of the molten steel surface of steel.

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