JP5796456B2 - Abnormality diagnosis apparatus and abnormality diagnosis method for electromagnetic field generator in continuous casting facility, and continuous casting method - Google Patents

Description

  The present invention relates to a continuous casting facility provided with an electromagnetic field generator for applying an electromagnetic field to a molten steel which is an unsolidified portion of a slab, which is disposed on a back surface of a continuous casting mold or a secondary cooling zone of a continuous casting machine. The present invention relates to an abnormality diagnosing device, an abnormality diagnosing method, and a continuous casting method for diagnosing an abnormality in a generator.

  In continuous casting of steel, non-metallic inclusions and gas bubbles contained in the molten steel injected into the mold are positively levitated and removed on the molten steel surface in the mold, and these are excellent in cleanliness. In order to obtain slabs, there are a wide variety of AC electromagnetic field generators that stir the moving steel in the mold by applying a moving magnetic field, and DC type electromagnetic field generators that reduce the flow velocity of the molten steel by applying a static magnetic field to the molten steel in the mold. It is used. In addition, since the dendritic solidified structure is melted by moving the moving magnetic field and the solidified structure is refined, and the center segregation of the slab is improved accordingly, an AC electromagnetic field for generating the moving magnetic field is generated in the secondary cooling zone. Installation of generators is also done. Note that the AC electromagnetic field generator is also called an electromagnetic stirring device because of its function.

  The electromagnetic field generator is an electromagnetic coil formed of an iron core (also referred to as a “yoke”) and a coil around which the iron core is wound, whether it is an AC type for generating a moving magnetic field or a DC type for generating a static magnetic field. Is provided. Since the coil needs to pass a large current, it is formed by a water-cooled copper pipe through which cooling water flows. Generally, the coil is connected to a bus bar for supplying power and a pipe for supplying water. A coil lead-out portion is provided.

In order to prevent cracks and damage of the coil lead-out portion and its periphery, an electromagnetic coil or the like in which at least a part of the coil lead-out portion is configured by a flexible conductor has been proposed. However, it was not possible to completely eliminate the equipment abnormality.
Thus, as a method for diagnosing an abnormality in the electromagnetic field generator, there is a technique described in Patent Document 1, for example. This technology measures the electric power supplied to an electromagnetic coil when a molten steel is continuously cast by applying an electromagnetic field of a predetermined intensity from an electromagnetic coil of an electromagnetic field generator, and measures the time series change of the measured supply power. It is something to monitor. Here, the abnormality of the electromagnetic coil is diagnosed from the change in the supplied power caused by the decrease in the resistance of the electromagnetic coil accompanying the coil deterioration.

JP 2009-39775 A

However, in the abnormality diagnosis method for the electromagnetic field generator in the continuous casting facility described in Patent Document 1, an abnormality in the coil resistance can be detected, but there is no abnormality in the coil resistance and there is an abnormality only in the insulation resistance. Cannot detect anomalies. This is because the coil resistance and the insulation resistance correlate depending on the abnormal state.
Insulation resistance refers to the insulation between the electric circuit and the ground (the ability to prevent current leakage), and does not mean the resistance of the copper tube. The case where an abnormality occurs only due to a decrease in insulation is not a factor such as a crack inside the electromagnetic coil, but it is assumed that the coil copper tube itself has deteriorated or the insulation has decreased due to moisture absorption. There is no change in the resistance itself.

  The insulation resistance of the electromagnetic coil can be measured by using an insulation resistance meter. However, since the insulation measurement is to convert the current when the test voltage is applied to the insulation resistance, it is necessary to measure at a timing that does not interfere with the electromagnetic field generation voltage. Dependent on the pitch to replace (about 2 months). That is, the insulation resistance can only be managed at a pitch at which the electromagnetic coil is replaced.

Therefore, if the insulation resistance suddenly decreases during operation, the electromagnetic coil may suddenly be replaced, or as a result of continuing to apply until the insulation is completely zero, the coil itself will burn out and coil rewinding will occur. There was a problem of reaching.
Accordingly, the present invention provides an electromagnetic field generator abnormality diagnosis device, abnormality diagnosis method, and continuous casting method in a continuous casting facility that enables insulation diagnosis of electromagnetic coils of an electromagnetic field generator installed in a continuous casting machine to be performed in a short cycle. It is an issue to provide.

In order to solve the above problems, an abnormality diagnosis device for an electromagnetic field generator in a continuous casting facility according to the present invention includes an electromagnetic field generator including an electromagnetic coil for applying an electromagnetic field to molten steel inside a slab cast by a continuous casting machine. An abnormality diagnosis device for an electromagnetic field generator in a continuous casting facility for diagnosing an insulation abnormality between the electric circuit and the ground of the abnormality, wherein the abnormality diagnosis power source for applying a constant DC voltage to the electromagnetic coil, A slab extraction detecting means for detecting that the slab has been removed from the electromagnetic field application area, and a slab extraction detecting means for detecting that the slab has been removed from the electromagnetic field application area by the slab extraction detecting means. A connection switching means for cutting off the connection to the electromagnetic field generating power source for supplying an electromagnetic field generating current to the electromagnetic coil and switching to the connection between the electromagnetic coil and the abnormality diagnosis power source; And said power source and the abnormality diagnosis of the electromagnetic coil is connected by the switching means, wherein while applying the DC voltage to the electromagnetic coil, rather than measuring the resistance of the copper tube of the electromagnetic coil, wherein said path earth And an abnormality diagnosis means for diagnosing an abnormality in the insulation resistance value of the electromagnetic coil.

  As described above, in the continuous casting machine, when it is detected that the casting slab is removed from the electromagnetic field application region by the electromagnetic coil by utilizing the existence of the casting interval in which casting is temporarily interrupted, a predetermined time (5 minutes) from that point is detected. ~ 15 minutes) is determined to be during casting, and the insulation test is started. That is, the insulation test can be performed during a period when the generation of the electromagnetic field by the electromagnetic field generator is unnecessary, and the insulation test can be appropriately performed without interfering with the electromagnetic field generated by the electromagnetic field generator.

In addition, since the insulation test is performed between castings that occur several times a day, the insulation test can be performed in a short span of several times / day. As a result, it is possible to appropriately predict the insulation decrease of the electromagnetic coil and perform insulation recovery treatment. Furthermore, since the insulation test can be automatically started by detecting the timing between casting, it is efficient without requiring manpower for performing the insulation test.
Further, in the above, the slab extraction detecting means detects that the rear end portion of the slab has passed through the pinch roll based on the rotational speed of the pinch roll provided immediately downstream of the electromagnetic field application region. In this way, it is detected that the slab has escaped from the electromagnetic field application region.

  Thus, when the pinch roll is stopped from the rotating state, the rear end of the slab passes through the pinch roll, and it can be determined that the subsequent slab is not transferred, Based on the rotational speed of the pinch roll provided immediately downstream of the electromagnetic field application region by the electromagnetic coil, it is detected that the rear end portion of the slab has passed the pinch roll provided immediately downstream of the electromagnetic field application region. To do. Therefore, the start timing of the insulation test can be appropriately detected by a relatively simple method.

  Further, in the above, when detecting that the molten steel is inserted into the electromagnetic field application region, and molten steel charging detection means for detecting that the molten steel is charged into the electromagnetic field application region, And a connection return means for disconnecting the connection between the electromagnetic coil and the power supply for abnormality diagnosis and returning the connection between the electromagnetic coil and the power supply for generating electromagnetic field.

In this way, when it is detected that molten steel has been inserted into the electromagnetic field application region by the electromagnetic coil, it is determined that the casting interval has ended, the insulation test is terminated, and the electromagnetic field generation by the electromagnetic field generator is automatically resumed. . Therefore, an electromagnetic field can be appropriately applied to the molten steel inside the slab cast in normal operation.
Furthermore, in the above, the molten steel charging detection means detects that the tip of the dummy bar has reached the pinch roll based on the rotational speed of the pinch roll provided immediately downstream of the electromagnetic field application region. Thus, it is characterized in that it is detected that molten steel is inserted into the electromagnetic field application region.

Thus, when the rotation is started from the state where the pinch roll is stopped, it is possible to determine that the tip of the dummy bar has passed through the pinch roll from the state where the slab is not phase-shifted. Based on the rotational speed of the pinch roll provided immediately downstream of the electromagnetic field application region by the electromagnetic coil, it is detected that the suspended casting has been resumed. Therefore, the end timing of the insulation test can be appropriately detected by a relatively simple method.
In the above, the electromagnetic coil is arranged in a mold of a continuous casting machine.
As a result, during normal operation, an electromagnetic field is applied to the molten steel inside the slab in the mold, and when it is detected that the slab has come out of the mold, it is determined that the predetermined time is between castings, and the insulation test is performed. It can be carried out.

Further, in the above, the abnormality diagnosis means includes a minute current detection means for detecting a minute current flowing through the electromagnetic coil when a direct current voltage is applied from the abnormality diagnosis power supply, a direct current voltage value of the abnormality diagnosis power supply, and the minute current. Insulation resistance measurement means for measuring an insulation resistance value of the electromagnetic coil based on a minute current value detected by the current detection means, and monitoring a change in the insulation resistance value measured by the insulation resistance measurement means Thus, an abnormality in the insulation resistance value of the electromagnetic coil is diagnosed.
In this way, a minute current flowing through the electromagnetic coil when a DC voltage is applied is detected, and an insulation resistance value is obtained by calculation with the DC voltage value. Therefore, an electromagnetic wave with an extremely low allowable minimum insulation resistance value compared to ordinary electrical equipment is generated. An insulation test of the electromagnetic coil of the apparatus can be appropriately performed.

Further, the abnormality diagnosis method for an electromagnetic field generator in a continuous casting facility according to the present invention diagnoses an abnormality in an electromagnetic field generator provided with an electromagnetic coil for applying an electromagnetic field to molten steel inside a slab cast by a continuous casting machine. A method for diagnosing an abnormality in the insulation between the electric path and ground of an electromagnetic field generator in a continuous casting facility, wherein the electromagnetic field is not applied during the operation of the continuous casting machine, and the electromagnetic field is not applied during the electromagnetic field non-application period. Disconnect the electromagnetic coil and the electromagnetic field generating power source that supplies the electromagnetic coil with a current for generating an electromagnetic field, apply a certain DC voltage from the abnormality diagnosis power source to the electromagnetic coil, and connect the copper coil of the electromagnetic coil Instead of measuring resistance, an insulation resistance value between the electric circuit and the ground is measured to diagnose an abnormality in the insulation resistance value of the electromagnetic coil.

  As described above, since the insulation test is performed during a period in which the generation of the electromagnetic field by the electromagnetic field generator is unnecessary, the insulation test can be accurately performed without interfering with the electromagnetic field generated by the electromagnetic field generator. In addition, since an insulation test can be performed between castings that occur several times a day, the insulation test can be performed in a short span of several times / day, and the electromagnetic coil can be sufficiently managed.

Furthermore, the continuous casting method according to the present invention is a continuous casting method in which continuous casting is performed while applying an electromagnetic field from an electromagnetic coil of an electromagnetic field generator to molten steel inside a slab in a mold, wherein the preceding slab is removed from the mold. At the time of extraction, the application of the electromagnetic field by the electromagnetic field generator is stopped, a constant DC voltage is applied to the electromagnetic coil, and the resistance of the copper tube of the electromagnetic coil is not measured. Measure the insulation resistance value with the earth , perform an abnormality diagnosis of the insulation resistance value of the electromagnetic coil, and then resume the application of the electromagnetic field by the electromagnetic field generator when the molten steel of the subsequent slab is inserted into the mold. And casting the molten steel of the subsequent slab.

  Thus, the insulation test of the electromagnetic coil can be automatically performed during casting from casting the preceding slab to casting the subsequent slab. Therefore, compared with the case where the insulation test of the electromagnetic coil is performed at the time of exchanging the mold, the span for performing the insulation test can be greatly shortened, and the management of the electromagnetic coil can be sufficiently performed.

  According to the present invention, since the normal operation (casting) by the continuous casting machine is temporarily interrupted (between castings), an abnormality in the insulation resistance value of the electromagnetic coil constituting the electromagnetic field generator is automatically diagnosed. The insulation test can be performed with high accuracy without interfering with the electromagnetic field applied from. In addition, since it is possible to diagnose the abnormality of the electromagnetic coil in a short span of several times / day, it is possible to properly predict the insulation deterioration of the electromagnetic coil and take appropriate insulation recovery measures, and excessive maintenance. Can be suppressed and appropriate management becomes possible.

It is a side view of the continuous casting installation in which the abnormality diagnosis apparatus of the electromagnetic field generator in this embodiment was installed. It is a figure which shows an insulation test possible period. It is a figure explaining line tracking. It is a block diagram which shows the structure of an electromagnetic field generator and its abnormality diagnosis apparatus. It is a figure explaining the example of insulation resistance measurement. It is a figure which shows the effect of this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side view of a continuous casting facility in which an abnormality diagnosis device for an electromagnetic field generator in this embodiment is installed.
In the figure, reference numeral 1 denotes a continuous casting machine. The continuous casting machine 1 includes a tundish 3 filled with molten steel 2. The tundish 3 is disposed on an upper part of a mold (mold) 4, and a casting floor 5 extends horizontally at substantially the same height as the mold 4. The molten steel 2 poured into the mold 4 from the tundish 3 is cooled from the side surface of the mold 4, and is solidified from the surface to form a shell, and is drawn downward by the pinch roll 6 to become a slab 7. . The slab 7 extracted continuously is cut into a predetermined length by the torch car 8.

  A dummy barker 9 can run on the casting floor 5, and a dummy bar hoisting device 10 is installed on the casting floor 5. The dummy bar 11 has a chain link structure, and is inserted into the mold 4 at the beginning of casting. When the dummy bar 11 reaches the final position of the guide roll segment after casting is started, the dummy bar 11 is lifted by the dummy bar hoisting device 10 and placed on the dummy barker 9.

The mold 4 is provided with an electromagnetic coil 15 for applying an electromagnetic field to the molten steel 2 in the mold 4 (molten steel in the slab). The electromagnetic coil 15 constitutes an electromagnetic field generator described later, and is formed of a water-cooled copper pipe.
As an electromagnetic field generator, an AC type electromagnetic field generator that applies a moving magnetic field to stir the unsolidified phase of molten steel or slab in a mold, or a DC type that applies a static magnetic field to brake the flow of molten steel There is an electromagnetic field generator. Any of the embodiments can be applied, but here, a case where a DC type electromagnetic field generator is applied will be described.

  The abnormality diagnosis device 20 measures the insulation resistance of the electromagnetic coil 15 and diagnoses whether an abnormality that reduces the insulation resistance has occurred. The decrease in the insulation resistance of the electromagnetic coil 15 can occur when the coil copper tube itself deteriorates or when moisture is absorbed to reduce insulation. This abnormality diagnosis device 20 automatically measures the insulation resistance of the electromagnetic coil 15 and diagnoses an abnormality during the operation of the continuous casting machine 1 during which the electromagnetic field generator does not need to be applied (hereinafter, this is insulated). Called the test).

  In the continuous casting equipment 1, when the steel type is changed, the casting is temporarily interrupted by replacing the tundish 3 or the like. In this way, the timing of once interrupting casting always occurs several times a day for about 5 to 15 minutes per time. This period is called casting. Since casting is a period in which casting is not performed, it is not necessary to generate an electromagnetic field by the electromagnetic field generator. Therefore, if this gap is used, the insulation resistance of the electromagnetic coil 15 of the electromagnetic field generator can be measured and an abnormality diagnosis can be performed.

  FIG. 2 is a diagram illustrating an insulation test period during which the abnormality diagnosis apparatus 20 performs an insulation test. When casting is interrupted, after casting the preceding slab 7a, a subsequent casting slab 7b is cast with a predetermined period of casting. Further, in the continuous casting machine 1, at the start of casting, the dummy bar 11 is first charged, and then the molten steel 2 is injected to generate the cast piece 7. Therefore, on the line, as shown in FIG. 2, after the preceding cast slab 7 a is transported, the dummy bar 11 is transported at a predetermined interval, and the succeeding cast slab 7 b is transported without being spaced from the dummy bar 11. Will be.

  The application of the electromagnetic field by the electromagnetic field generator may be performed only during the casting period (the period when the molten steel 2 is filled in the mold 4). That is, the other period (period in which the molten steel 2 is not filled in the mold 4 and period in which the dummy bar 11 is inserted in the mold 4) is an electromagnetic field non-application period (insulation test possible period).

  In the present embodiment, in the electromagnetic field non-application period (insulation test possible period) shown in FIG. 2, the dummy bar 11 is inserted into the mold 4 after the preceding slab 7 a is removed from the mold 4, which is an electromagnetic field application region by the electromagnetic coil 15. The period until charging is the insulation test period. The timing of the insulation test period is detected by line tracking based on the rotation speed of the first pinch roll 6 arranged immediately downstream of the mold 4. The rotation speed of the first pinch roll 6 can be detected by a speed pulse output from the rotation detector (PLG) 12 installed in the first pinch roll 6.

When the preceding slab 7a is completely removed from the mold 4 and the rear end of the preceding slab 7a passes through the first pinch roll 6 as shown in FIG. 3A, the rotation of the first pinch roll 6 is Stop. Therefore, when the rotation of the first pinch roll 6 is stopped, it is determined that the preceding slab 7a has passed through the mold 4, and this timing is set as the insulation test start timing.
Further, when the dummy bar 11 is inserted into the mold 4 in order to insert the molten steel 2 of the subsequent cast slab 7b into the mold 4, the tip of the dummy bar 11 is the first as shown in FIG. When the first pinch roll 6 is reached, the first pinch roll 6 starts rotating from a stopped state. Therefore, when the first pinch roll 6 starts to rotate, it is determined that the dummy bar 11 is inserted into the mold 4, and this timing is set as the insulation test end timing.

Hereinafter, the configuration of the abnormality diagnosis apparatus 20 will be specifically described.
FIG. 4 is a block diagram showing the configuration of the electromagnetic field generator and its abnormality diagnosis device 20.
In FIG. 4, reference numeral 16 denotes an electromagnetic field generator, which includes an electromagnetic coil 15 and an electromagnetic field generating power supply device 17. The electromagnetic field generating power supply device 17 is installed in an electric chamber or the like away from the continuous casting machine 1 and supplies a predetermined direct current corresponding to casting conditions to the electromagnetic coil 15 as an electromagnetic field generating current. .

The abnormality diagnosis device 20 includes a DC voltage generator 21, a connection changeover switch 22, a line control device 23, a current sensor 24, and a signal processing device 25.
The DC voltage generator 21 is applied to the electromagnetic coil 15 during the insulation test period from when the test start signal output from the signal processing device 25 is input to when the test end signal output from the signal processing device 25 is input. A DC voltage having a constant value (for example, 500 V) is generated as a test voltage for the insulation resistance test.
The connection changeover switch 22 is connected to the electromagnetic coil 15 and the electromagnetic field generating power supply device 17 and to the electromagnetic coil 15 and the DC voltage generator 21 in accordance with the connection switching signal output from the signal processing device 25. Switch.

The line control device 23 inputs the rotation speed of the first pinch roll 6 detected by the rotation detector (PLG) 12 and tracks the slab 7. Then, the insulation test start timing and insulation test end timing are detected by the tracking, and a line tracking signal representing these timings is output to the signal processing device 25.
The current sensor 24 detects a minute current flowing through the electromagnetic coil 15 when a DC voltage is applied from the DC voltage generator 21 to the electromagnetic coil 15. The measurement range of the current sensor 24 is set to 0 to 100 mA.

  The signal processing device 25 inputs the line tracking signal from the line control device 23, outputs a test start signal to the DC voltage generator 21 at the insulation test start timing, and connects the electromagnetic coil 15 and the electromagnetic field to the connection changeover switch 22. A connection switching signal for switching from the connection with the generating power supply device 17 to the connection between the electromagnetic coil 15 and the DC voltage generator 21 is output. Similarly, the signal processing device 25 outputs a test end signal to the DC voltage generator 21 at the insulation test end timing, and connects to the connection changeover switch 22 from the connection between the electromagnetic coil 15 and the DC voltage generator 21. A connection switching signal for switching the connection between the coil 15 and the electromagnetic field generating power supply device 17 is output.

  In addition, after the signal processing device 25 outputs the test start signal and the connection switching signal at the insulation test start timing, when a predetermined time has elapsed in which it can be determined that the electromagnetic coil 15 and the DC voltage generator 21 are securely connected, The current detected by the current sensor 24 is acquired, and the insulation resistance of the electromagnetic coil 15 is measured.

  The insulation resistance is measured by calculating the applied voltage [V] / measured current [A] based on the measured current of the current sensor 24 and the applied voltage of the DC voltage generator 21. The insulation resistance measurement time is about 1 minute. That is, as shown in FIG. 5A, a test voltage DC500V is applied to the electromagnetic coil 15 for 1 minute, and a minute current flowing through the electromagnetic coil 15 at that time is measured by the current sensor 24 as shown in FIG. 5B. And obtain the insulation resistance. In this embodiment, since the measurement range of the current sensor 24 is 0 to 100 mA (0.1 A), when the test voltage is DC 500 V, the measurement range of the insulation resistance is 0.005 MΩ (5 kΩ) to ∞.

  Then, the signal processing device 25 determines whether or not the measured insulation resistance value is equal to or less than the intervention threshold Ra (for example, 0.02 MΩ) of the burnout caution area of the electromagnetic coil 15. At this time, if the insulation resistance value exceeds the intervention threshold Ra in the burnout caution area, it is determined that the insulation is not lowered and the casting is continued. On the other hand, when the insulation resistance value is equal to or lower than the intervention threshold Ra in the burnout caution area, the insulation is lowered, and it is determined that there is a possibility of burnout if it is used as it is, and a predetermined insulation recovery treatment is performed.

  The minimum allowable insulation resistance of a motor that is a general electric device is represented by (applied voltage × 1/1000) MΩ, and is 0.4 MΩ in the case of a 400 V motor. On the other hand, since the coil copper pipe of the electromagnetic coil 15 of the electromagnetic field generator 16 is water-cooled, the inside of the copper pipe is always filled with pure water, and the allowable minimum insulation resistance is about 0.02 MΩ. Therefore, here, the burnout caution area intervention threshold Ra is set to 0.02 MΩ, which is the allowable minimum insulation resistance value of the electromagnetic coil 15.

Here, it is determined whether or not the measured insulation resistance value is equal to or less than the intervention threshold Ra in the burnout caution area. However, the insulation resistance at the next insulation test is based on the insulation resistance measurement data for a certain period in the past. A value may be predicted, and it may be determined whether or not the predicted insulation resistance value is equal to or less than the intervention threshold Ra in the burnout caution area.
In the above, the DC voltage generator 21 corresponds to the abnormality diagnosis power source, the connection changeover switch 22 corresponds to the connection changeover means and the connection return means, and the line control device 23 corresponds to the slab extraction detection means and the molten steel charging detection means. Correspondingly, the current sensor 24 corresponds to the minute current detection means, and the signal processing device 25 corresponds to the abnormality diagnosis means and the insulation resistance measurement means.

Next, the continuous casting method in this embodiment is demonstrated.
The mold 4 of the continuous casting machine 1 is provided with an electromagnetic coil 15 of an electromagnetic field generator 16. In normal operation, the molten steel 2 is applied to the molten steel 2 injected into the mold 4 by the electromagnetic coil 15. 2 is cast. That is, during normal operation, the connection changeover switch 22 of the abnormality diagnosis device 20 is in the state shown by the solid line in FIG. 4, and the electromagnetic coil 15 and the electromagnetic field generating power supply device 17 are connected.

In the case where the tundish 3 is exchanged for the purpose of changing the steel type, for example, when the tundish 3 is changed from the state where the normal operation is performed in this way, the casting is temporarily interrupted and the casting is performed after providing a casting interval of about 5 to 15 minutes. Is resumed. This casting time varies depending on the continuous casting equipment and the steel type configuration to be operated, but always occurs several times a day.
At this time, when the casting is interrupted, the cast piece 7 formed by solidification of the molten steel 2 from the inside of the mold 4 is completely removed, and the rear end portion of the cast piece 7 is provided on the downstream side of the mold 4. When the pinch roll 6 is passed, the rotation of the first pinch roll 6 is stopped. Then, the line control device 23 detects this from the speed pulse of the rotation detector (PLG) 12 and performs signal processing on the line tracking signal indicating that the rear end portion of the slab 7 has passed through the first pinch roll 6. Output to the device 25.

  When the signal processing device 25 acquires the line tracking signal, the signal processing device 25 outputs a connection switching signal for switching the connection switching switch 22 to a state indicated by a broken line in FIG. As a result, the connection between the electromagnetic coil 15 and the electromagnetic field generating power supply device 17 is disconnected, and the electromagnetic coil 15 and the DC voltage generator 21 are connected. At the same time, the signal processing device 25 outputs a test start signal to the DC voltage generator 21. As a result, a DC voltage of 500 V is applied as a test voltage for 1 minute from the DC voltage generator 21 to the electromagnetic coil 15.

Next, the signal processing device 25 acquires a minute current detected by the current sensor 24 when a DC voltage is applied, and calculates the insulation resistance of the electromagnetic coil 15 based on the DC voltage value and the minute current value detected by the current sensor 24. Find the value.
Then, after the measurement time of 1 minute has elapsed, it is determined whether or not the measured insulation resistance value is equal to or less than the intervention threshold Ra (for example, 0.02 MΩ) in the burnout caution area of the electromagnetic coil 15. At this time, if the measured insulation resistance value exceeds the threshold value Ra, it is determined that the insulation reduction has not occurred in the electromagnetic coil 15 and that it can be used as it is.

  Thereafter, the dummy bar 11 is inserted into the mold 4 to resume casting, and when the leading end of the dummy bar 11 reaches the first pinch roll 6, the first pinch roll 6 starts to rotate from the stopped state. Then, the line control device 23 detects this from the speed pulse of the rotation detector (PLG) 12 and outputs a line tracking signal indicating that the tip of the dummy bar 11 has passed through the first pinch roll 6 to the signal processing device 25. Output to.

  When the signal processing device 25 acquires this line tracking signal, the signal processing device 25 outputs a connection switching signal for switching the connection switching switch 22 to the state indicated by the solid line in FIG. Thereby, the connection between the electromagnetic coil 15 and the DC voltage generator 21 is disconnected, and the electromagnetic coil 15 and the electromagnetic field generating power supply device 17 are connected. As a result, a DC current can be supplied from the electromagnetic field generating power supply device 17 to the electromagnetic coil 15.

In this way, the insulation resistance of the electromagnetic coil 15 is measured using the space between the castings. Thereby, for example, when the insulation resistance measurement of the electromagnetic coil 15 can be performed only at the timing of replacing the mold 4, the measurement can be performed several times a day, whereas the measurement is performed once every two months. Therefore, the electromagnetic coil 15 can be managed with a short span.
Therefore, when the insulation resistance value of the electromagnetic coil 15 intervenes in the burnout caution area of the electromagnetic coil 15, the insulation recovery treatment can be performed, and the electromagnetic coil 15 can be prevented from being burned.

  Moreover, the timing which becomes between casting is detected automatically by line tracking, and the connection between the electromagnetic coil 15 and the electromagnetic field generating power supply device 17 and the connection between the electromagnetic coil 15 and the DC voltage generator 21 are automatically detected at this timing. Therefore, the insulation test of the electromagnetic coil 15 can be performed even during casting as short as 5 to 15 minutes.

  Even if the time between castings is automatically detected by line tracking, if you try to measure insulation resistance manually using a hand-held insulation resistance meter between castings, the coil power supply is shut off to prevent electric shock. It is very difficult to carry out the measurement from the start to the end of insulation resistance measurement in 15 minutes. In addition, it is inefficient to place a measurer between castings that are only several times a day. In this embodiment, since the insulation resistance measurement is automatically started at the timing when the generation of the electromagnetic field is not necessary, without manual intervention, the insulation test can be efficiently performed with a small casting interval in continuous casting.

  Further, the insulation test start timing is the timing at which the slab 7 comes off the mold 4, and the slab 7 has come off from the mold 4 when the rear end portion of the slab 7 has passed through the first pinch roll 6. To detect. In this way, it is possible to detect the timing at which casting is properly performed by line tracking. Similarly, the end timing of the insulation test is set to the timing at which the molten steel 2 of the subsequent cast piece is inserted into the mold 4, and the molten steel 2 of the subsequent cast piece is obtained when the leading end of the dummy bar 11 reaches the first pinch roll 6. Is detected in the mold 4. In this way, it is possible to detect the timing at which the casting interval is appropriately terminated by line tracking.

  At this time, based on the rotational speed of the first pinch roll 6, the rear end portion of the slab 7 has passed through the first pinch roll 6, and the leading end portion of the dummy bar 11 has reached the first pinch roll 6. Therefore, the insulation test start timing and the insulation test end timing can be appropriately detected by a relatively simple method. In addition, since a rotation detector (PLG) generally installed on a pinch roll is used, there is no need to newly provide a line tracking sensor or the like.

  Furthermore, when measuring the insulation resistance, a minute current when a test voltage of DC 500 V is applied is measured using a minute current sensor whose measurement range is set to 0 to 100 mA. Therefore, it is possible to measure a very low insulation resistance value of 0.005 MΩ (5 kΩ), and the minimum allowable insulation resistance 0.02 MΩ in the electromagnetic coil 15 can be appropriately monitored.

  For measuring the insulation resistance of the electromagnetic coil of the electromagnetic field generator, an analog insulation resistance meter has been used instead of a commercially available digital insulation resistance meter. Commercially available digital insulation resistance meters are manufactured for the purpose of determining whether there is a certain insulation resistance value or more, that is, soundness, and there is little need to measure a region with low insulation resistance. Therefore, the measurement range of a commercially available digital insulation resistance meter is set to a range of about 0.1 MΩ to 100 MΩ, which is inappropriate for monitoring the insulation resistance of the electromagnetic coil. However, since the analog insulation resistance meter has a lower measurement accuracy of the insulation resistance than the digital insulation resistance meter, it is difficult to appropriately monitor the insulation resistance of the electromagnetic coil.

  On the other hand, in the present embodiment, a current sensor 24 that can measure a minute current (0 to 100 mA) by applying a test voltage using the DC voltage generator 21 as an insulation resistance meter for measuring an electromagnetic coil is used. Adopts a configuration that measures a minute current when a DC voltage is applied. Thereby, it can be accurately monitored whether or not the insulation resistance value of the electromagnetic coil 15 exceeds the minimum allowable insulation resistance of 0.02 MΩ.

  In addition, long-term management of the insulation resistance measurement data obtained by the insulation test makes it possible to appropriately predict that the insulation resistance will decrease during operation, so that the planned electromagnetic field generator 16 can be replaced. It becomes. As a result, it is possible to avoid the problem that the electromagnetic coil 15 is suddenly replaced or the insulation itself becomes 0 and the coil itself is burned out, and excessive maintenance can be suppressed. .

FIG. 6 is a diagram showing the effect of this embodiment.
As shown in FIG. 6, in the conventional method in which the insulation test of the electromagnetic coil 15 is performed at the timing when the mold 4 is replaced, the pitch at which the insulation test is performed is α (1 time / 2 months pitch). For this reason, in this conventional method, the insulation reduction of the electromagnetic coil is predicted based on the insulation resistance measurement data acquired at the pitch α.

  When the next insulation resistance measurement data a2 is predicted when the insulation resistance measurement data a1 is acquired, if the predicted insulation resistance value exceeds the intervention threshold Ra (0.02 MΩ) of the burnout caution area, the electromagnetic Even if the coil is continuously used, it is determined that there is no problem. However, after obtaining the insulation resistance measurement data a1, it is possible that the insulation resistance suddenly decreases for some reason. In this case, the insulation resistance value enters the burnout warning area before the next insulation test is performed. Resulting in. As a result, the insulation recovery process is not in time, and in the worst case, the coil itself may burn out, leading to coil rewinding.

On the other hand, in this embodiment, since the insulation test of the electromagnetic coil 15 can be performed at a timing between casting during normal operation, the pitch for performing the insulation test is β (several times / one day pitch). Compared with the conventional α (1 time / 2 months pitch), it is greatly shortened.
For this reason, even if the insulation resistance measurement data b1 is acquired, the insulation resistance measurement data b2 is an intervention in the burnout caution area because the insulation test is performed in a short span even if the insulation resistance starts to drop sharply for some reason. When the threshold value Ra (0.02 MΩ) or less is reached, insulation recovery treatment can be performed. Thus, since the insulation recovery treatment can be performed before the electromagnetic coil is burned out, the electromagnetic coil can be reused.

Furthermore, since the insulation reduction of the electromagnetic coil can be appropriately predicted and the electromagnetic field generator can be replaced systematically, it is possible to avoid the need for sudden replacement, and the continuous casting machine A decrease in operating rate can be minimized.
As described above, after the insulation test of the electromagnetic coil 15 is performed, an electromagnetic field is applied from the electromagnetic coil 15 to the molten steel 2 in the mold 4 at the timing when the molten steel 2 of the subsequent slab is inserted into the mold 4. The subsequent casting is cast while applying the electromagnetic field. Here, the timing at which the electromagnetic field is applied from the electromagnetic coil 15 is determined based on, for example, the insulation test end timing.

The dimensions of the dummy bar 11 are known. Therefore, if the conveyance speed of the dummy bar 11 is known, the timing at which the tip of the succeeding cast slab reaches the first pinch roll 6 based on the timing at which the tip of the dummy bar 11 reaches the first pinch roll 6. That is, the timing at which the molten steel 2 of the subsequent slab is inserted into the mold 4 can be obtained.
Thus, unnecessary electromagnetic field application can be avoided by applying the electromagnetic field from the electromagnetic coil 15 at the timing when the molten steel 2 of the subsequent cast slab is inserted into the mold 4.

  In the present embodiment, the case where the electromagnetic coil 15 of the electromagnetic field generator 16 is disposed in the mold 4 has been described. However, the present invention is also applied to a case where the electromagnetic coil is disposed in the secondary cooling zone on the downstream side of the mold 4. Can be applied. In this case, the timing at which the slab 7 exits the electromagnetic field application region by the electromagnetic coil 15 is the insulation test start timing, and the timing at which the dummy bar 11 is inserted into the electromagnetic field application region is the insulation test end timing. The insulation test start timing and insulation test end timing are detected based on the rotation speed of a pinch roll provided immediately downstream of the electromagnetic field application region.

  DESCRIPTION OF SYMBOLS 1 ... Continuous casting machine, 2 ... Molten steel, 3 ... Tundish, 4 ... Mold, 5 ... Cast floor, 6 ... Pinch roll, 7 ... Cast slab, 7a ... Pre-cast slab, 7b ... Subsequent slab, 8 ... Torch car DESCRIPTION OF SYMBOLS 9 ... Dummy barker, 10 ... Dummy bar hoisting device, 11 ... Dummy bar, 12 ... Rotation detector (PLG), 15 ... Electromagnetic coil, 16 ... Electromagnetic field generator, 17 ... Power supply device for electromagnetic field generation, 20 ... Abnormality diagnostic device , 21 ... DC voltage generator (abnormality diagnosis power supply), 22 ... connection changeover switch, 23 ... line control device, 24 ... current sensor, 25 ... signal processing device

Claims (8)

Diagnosis of abnormality of electromagnetic field generator equipped with electromagnetic coil for applying electromagnetic field to molten steel inside slab cast by continuous casting machine, abnormality diagnosis device for insulation between electric path and ground of electromagnetic field generator in continuous casting equipment Because
An abnormality diagnosis power source for applying a constant DC voltage to the electromagnetic coil;
A slab extraction detecting means for detecting that the slab has escaped from the electromagnetic field application region by the electromagnetic coil,
When the slab extraction detecting means detects that the slab has escaped from the electromagnetic field application region, disconnects the electromagnetic coil and the electromagnetic field generating power source that supplies the electromagnetic coil with a current for generating an electromagnetic field, Connection switching means for switching to connection between the electromagnetic coil and the abnormality diagnosis power supply;
Rather than measuring the resistance of the copper coil of the electromagnetic coil in a state where the electromagnetic coil and the abnormality diagnosis power source are connected by the connection switching means and the DC voltage is applied to the electromagnetic coil, the electric circuit and An abnormality diagnosis device for an electromagnetic field generator in a continuous casting facility , comprising: an abnormality diagnosis unit that measures an insulation resistance value with respect to the ground and diagnoses an abnormality in an insulation resistance value of the electromagnetic coil. The slab extraction detecting means is
Based on the rotational speed of the pinch roll provided immediately downstream of the electromagnetic field application region, it is detected that the rear end portion of the slab has passed the pinch roll, and with this, the slab comes out of the electromagnetic field application region. The abnormality diagnosis device for an electromagnetic field generator in a continuous casting facility according to claim 1, wherein the abnormality is detected. Molten steel charging detection means for detecting that molten steel is charged in the electromagnetic field application region;
When it is detected by the molten steel charging detection means that molten steel is charged in the electromagnetic field application region, the connection between the electromagnetic coil and the abnormality diagnosis power supply is cut off, and the electromagnetic coil and the electromagnetic field generating power supply An abnormality diagnosis device for an electromagnetic field generator in a continuous casting facility according to claim 1, further comprising: a connection return means for returning the connection. The molten steel charging detection means includes
Based on the rotational speed of the pinch roll provided immediately downstream of the electromagnetic field application region, it is detected that the tip of the dummy bar has reached the pinch roll, and with this, the molten steel is inserted into the electromagnetic field application region. The abnormality diagnosis device for an electromagnetic field generator in a continuous casting facility according to claim 3, wherein the abnormality is detected.   The said electromagnetic coil is arrange | positioned at the casting_mold | template of a continuous casting machine, The abnormality diagnosis apparatus of the electromagnetic field generator in the continuous casting installation of any one of Claims 1-4 characterized by the above-mentioned. The abnormality diagnosis means includes
A minute current detecting means for detecting a minute current flowing in the electromagnetic coil when a DC voltage is applied from the abnormality diagnosis power source;
Insulation resistance measuring means for measuring an insulation resistance value of the electromagnetic coil based on a DC voltage value of the abnormality diagnosis power source and a minute current value detected by the minute current detecting means,
The continuity according to any one of claims 1 to 5, wherein an abnormality of the insulation resistance value of the electromagnetic coil is diagnosed by monitoring a change in an insulation resistance value measured by the insulation resistance measuring means. An abnormality diagnosis device for an electromagnetic field generator in a casting facility. Diagnosis of abnormality of electromagnetic field generator equipped with electromagnetic coil for applying electromagnetic field to molten steel inside slab casted by continuous casting machine, method for diagnosing abnormality of insulation between electric circuit and ground of electromagnetic field generator in continuous casting equipment Because
During operation of the continuous casting machine, during the electromagnetic field non-application period in which application of the electromagnetic field by the electromagnetic field generator is not required, connection between the electromagnetic coil and an electromagnetic field generating power source for supplying an electromagnetic field generating current to the electromagnetic coil is performed. Cutting, applying a constant DC voltage from the power supply for abnormality diagnosis to the electromagnetic coil, and measuring the resistance of the copper coil of the electromagnetic coil, measuring the insulation resistance value between the electric circuit and the ground, An abnormality diagnosis method for an electromagnetic field generator in a continuous casting facility, characterized by diagnosing an abnormality in an insulation resistance value of an electromagnetic coil. A continuous casting method of continuously casting while applying an electromagnetic field from an electromagnetic coil of an electromagnetic field generator to molten steel inside a slab in a mold,
When the preceding slab is extracted from the mold, the electromagnetic field application by the electromagnetic field generator is stopped, a constant DC voltage is applied to the electromagnetic coil, and the resistance of the copper coil of the electromagnetic coil is not measured, Measure the insulation resistance value between the electric circuit and the ground of the electromagnetic field generator , perform an abnormality diagnosis of the insulation resistance value of the electromagnetic coil, and then, when the molten steel of the subsequent slab is inserted into the mold, the electromagnetic field generation A continuous casting method, wherein the application of an electromagnetic field by the apparatus is resumed to cast the molten steel of the subsequent cast slab.

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