WO2018021635A1 - Continuous casting abnormality prediction device - Google Patents

Abstract

A continuous casting abnormality prediction device is disclosed. The continuous casting abnormality prediction device according to one embodiment of the present invention comprises: a temperature sensing unit having a plurality of thermocouples arranged at intervals in a mold receiving molten steel inside a tundish through a submerged entry nozzle; and a control unit for determining submerged entry nozzle damage and/or a slab defect, which includes at least one of mold slag mixing, a slab surface longitudinal crack, and a slab surface transverse crack, by using temperature values sensed from the plurality of thermocouples while a continuous cast process is performed.

Description

Continuous casting abnormality prediction device

The present invention relates to a continuous casting abnormality predicting apparatus, and more particularly, to a continuous casting abnormality predicting apparatus for predicting the defect of the cast during continuous casting.

In general, the continuous casting process continuously injects molten steel into a mold having a predetermined shape, and continuously discharges slag and bloom to the lower side of the mold. ) Is a process for manufacturing slabs of various types such as billets.

The continuous casting machine performing this process is a tundish that receives molten steel, a mold that receives molten steel from the tundish to mold the slabs, and cools while transferring the slabs discharged from the mold. And a cooling line with a plurality of rolls arranged in succession.

In the steelmaking process, when molten steel that satisfies the composition and temperature is contained in a ladle and transferred to the playing process, the molten steel is supplied to the mold through a tundish. Solidification of the steel begins by contact with the water-cooled copper plates in the mold. As soon as the mold exits the mold, the solidification cell becomes about 20 mm thick and then solidification proceeds by the coolant sprayed directly from the secondary cooling zone to the surface of the cast steel. At about 10-15m, the solidification is completed and the slabs are formed by cutting to the appropriate length.

Various defects occur on the surface of the cast steel. In the case of stainless steel, representative defects include mold slag incorporation, face cracks or depressions, and face cracks or depressions.

Most of these defects are known to occur at the upper end of the mold, i.e. during initial solidification.

Molten steel is fed from the tundish into the mold in an amount through the immersion nozzle. Mold powder used to secure the lubrication ability between the copper plate and the solidification cell is supplied from the top, and after melting, a slag film is formed to function as a lubrication function and a heat transfer control function. In addition, the copper plate is vibrated up and down to prevent sticking.

Therefore, heat from the molten steel passes through the solidification cell, the liquid slag film, the solid slag film, and the copper plate, and solidification proceeds. Most cast defects are caused by inadequate heat transfer behavior during this initial solidification.

Korean Unexamined Patent Publication No. 10-2013-0013738 discloses providing a thermocouple in a mold of a player, measuring the fluctuation of the mold surface in real time using the thermocouple, and stabilizing the surface of the mold effectively using the measurement result. .

Korean Patent Laid-Open Publication No. 10-1995-0012629 includes inserting a thermocouple into a mold of a player, measuring the temperature change of the mold using the thermocouple, and predicting break-out using the measured result. Is disclosed. Breakout is one of the accidents that occur during continuous casting of steel, which means that molten steel leaks as the solidification layer breaks directly under the mold during casting.

As described above, the thermocouple is inserted into the mold to measure the temperature of the mold. However, the mold slag, which is a defect in the slab frequently generated during continuous casting of stainless steel, merely detects fluctuations in the mold surface or predicts breakout. (mold slag) Unexpected failures such as mixing, face cracks or face vertical depressions, face cracks or face horizontal depressions, or immersion nozzle failure, a serious operation accident caused by increased casting time.

Embodiment of the present invention provides a continuous casting abnormality prediction device for predicting abnormalities such as cast defects and immersion nozzle failure by using the temperature of the mold during continuous casting.

According to an aspect of the invention, the temperature sensing unit having a plurality of thermocouples arranged at intervals to each other in the mold supplied to the molten steel in the tundish through the immersion nozzle; And at least one of a slab defect including at least one of mold slag incorporation, slab face vertical crack, and slab face horizontal crack using temperature values sensed from the plurality of thermocouples during the continuous casting process. Continuous casting abnormality prediction apparatus including a control unit for determining may be provided.

In addition, the plurality of thermocouples may be arranged in the width direction on both sides of the mold within 110mm below the bath surface, which is within 210mm from the top of the mold and the molten steel is filled in the mold.

In addition, the controller may determine that the immersion nozzle is damaged when the central thermocouple temperature rises or falls lower than the remaining thermocouple temperature by comparing the central thermocouple temperature and the remaining thermocouple temperatures among the thermocouples provided on both sides of the mold.

The control unit may compare the thermocouple temperature corresponding to the edge portion of the cast casting width with the remaining thermocouple temperature among the thermocouples provided on both sides of the mold, and when the edge portion thermocouple temperature rises or falls faster than the remaining thermocouple temperature, the mold slag is mixed. It can be determined that this has occurred.

In addition, the controller may determine that vertical cracks are generated in the cast steel when the average standard deviation of the thermocouples provided on both sides of the mold is higher than a preset value.

The controller may determine that a horizontal crack occurs in the cast steel when the central thermocouple temperature of the thermocouples provided on both sides of the mold is higher than a predetermined value periodically.

Embodiment of the present invention is based on the metallurgical experience and theories related to cast defects accumulated to date to insert the thermocouple into the mold to be used in the field at all times, using the temperature data from the thermocouple to consider the characteristics of the cast defects By analyzing based on metallurgical theory related to defects, such as mold slag incorporation that occurs frequently during continuous casting of stainless steel, face cracks or face vertical depressions, face cracks or face horizontal depressions, It is possible to judge abnormality such as immersion nozzle damage, which is a serious operation accident that occurs due to the increase of casting time, and it is possible to accurately and reliably predict cast defects and operation abnormalities in real time during performance.

The embodiment of the present invention predicts abnormalities such as mold slag incorporation, face cracks or face vertical depressions, face cracks or face horizontal depressions, and immersion nozzle breakage, and warns the field operators and engineers of large operation accidents and large quality. Minimize accidents.

1 is a view showing the configuration of a continuous casting machine that can be applied to the continuous casting abnormality prediction apparatus according to an embodiment of the present invention.

2 is a control block diagram of a continuous casting failure prediction apparatus according to an embodiment of the present invention.

3 is a view for explaining the installation position of the thermocouple for the copper plate in one embodiment of the present invention.

4 is a view showing the thermocouple position and the distance from the center of the copper plate installed on the inside and the outside of the copper plate in one embodiment of the present invention.

5 is a view showing a thermocouple mounting structure in a copper plate in one embodiment of the present invention.

6 is a schematic diagram showing a schematic configuration of a continuous casting failure prediction apparatus according to an embodiment of the present invention.

7 is a view showing the position of the thermocouple used for immersion nozzle failure prediction in the continuous casting failure prediction apparatus according to an embodiment of the present invention.

8 is a view showing a warning message displayed by the continuous casting failure prediction apparatus when predicting the immersion nozzle failure according to an embodiment of the present invention.

FIG. 9 is a diagram illustrating a thermocouple position used for mold slag incorporation prediction in a continuous casting abnormality predicting apparatus according to an embodiment of the present invention.

10 is a graph showing a change in mold temperature when mold slag incorporation occurs in the continuous casting abnormality predicting apparatus according to an embodiment of the present invention.

FIG. 11 is a diagram illustrating a warning message displayed by the continuous casting abnormality predicting apparatus according to an embodiment of the present invention when predicting mold slag mixing. FIG.

FIG. 12 is a diagram illustrating a thermocouple position used for face vertical crack or face vertical depression prediction in a continuous casting abnormality predicting apparatus according to an embodiment of the present invention.

FIG. 13 is a graph illustrating a change in mold temperature when surface vertical cracks occur and do not occur in the continuous casting abnormality predicting apparatus according to an embodiment of the present invention.

FIG. 14 is a diagram illustrating a warning message displayed by a continuous casting abnormality predicting apparatus according to an embodiment of the present invention when predicting surface vertical cracks or surface vertical depressions.

FIG. 15 is a diagram illustrating a thermocouple position used for face horizontal crack or face horizontal depression prediction in a continuous casting abnormality predicting apparatus according to an embodiment of the present invention.

16 is a graph illustrating a change in mold temperature when a horizontal crack occurs in a continuous casting abnormality predicting apparatus according to an exemplary embodiment of the present invention.

FIG. 17 is a diagram illustrating a warning message displayed by a continuous casting abnormality predicting apparatus according to an embodiment of the present invention when predicting a plane horizontal crack or a plane horizontal depression.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art to which the present invention pertains. The present invention is not limited to the embodiments described below and may be embodied in other forms. Parts not related to the description are omitted in the drawings in order to clearly describe the present invention, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

1 is a view showing the configuration of a continuous casting machine that can be applied to the continuous casting abnormality prediction apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the continuous casting machine may include a ladle 10, a tundish 20, a mold 30, a transfer roll 40, and a coolant supply device 50.

The molten steel M filled in the ladle 10 is supplied to the tundish 20.

The tundish 20 serves as a buffer for temporarily storing the molten steel M between the ladle 10 and the mold 30. The molten steel M in the tundish 20 is supplied into the mold 30 by an immersion nozzle 21 extending into the mold 30. The immersion nozzle 21 is disposed in the center of the mold 30 and the molten steel M is discharged from both discharge ports.

The molten steel M supplied to the mold 30 is shaped into the slab 60 by the mold 30 and undergoes primary cooling with respect to the slab 60. The molten steel M in the mold 30 starts to solidify from the part in contact with the wall surface forming the mold 30. This is because heat is more likely to be lost by the mold 30 in which the periphery is cooled rather than the center of the molten steel M. By the way that the periphery is first solidified, the back portion along the casting direction of the cast steel 60 forms a shape in which the unsolidified molten steel 61 is wrapped by the solidification cell 62.

The slab 60 shaped by the mold 30 and manufactured by primary cooling is conveyed by the feed roll 40. While the slab 60 is conveyed by the feed roll 40, the slab 60 is secondarily cooled by the coolant provided from the coolant supply device 50.

As the feed roll 40 pulls the leading end of the cast steel 60 completely solidified, the unsolidified molten steel 61 moves together with the solidification cell 62 in the casting direction.

The uncondensed molten steel 61 is cooled by the coolant supply device 50 that sprays the coolant during the above movement. At this time, the thickness of the unsolidified molten steel 61 in the slab 60 is gradually reduced.

When the cast steel 60 reaches from one point, the cast steel 60 is filled with the solidification cell 62 of the entire thickness. The slag 60 is solidified is cut into a predetermined size by the cutter 70 at the cutting point is divided into cast pieces.

As described above, various defects such as mold slag mixing, surface vertical crack / face vertical depression, or surface horizontal crack / face horizontal depression occur on the surface of the slab 60. Most cast defects are caused by inadequate heat transfer behavior during the initial solidification of casts.

In an embodiment of the present invention, in order to predict such defects, thermocouples are inserted into a mold to analyze temperature data based on metallurgical theories related to the defects, and perform defect prediction and abnormal behavior detection in real time.

2 is a control block diagram of a continuous casting failure prediction apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the apparatus for predicting continuous casting abnormality includes a controller 100 that performs overall control.

The temperature sensing unit 110 is electrically connected to the controller 100.

The display unit 120 and the storage unit 130 are electrically connected to the controller 100.

The temperature sensing unit 110 includes a plurality of thermocouples provided in the mold 30 and sensing the temperature of the mold 30. In this case, the mold temperature may include a mold copper plate temperature.

Figure 3 is a view for explaining the installation position of the thermocouple for the copper plate in one embodiment of the present invention, Figure 4 is a thermocouple installed on the inner and outer sides of the copper plate in one embodiment of the present invention and the distance from the center of the copper plate 5 is a view showing a thermocouple mounting structure in a copper plate in one embodiment of the present invention.

3 to 5, the z-direction (depth direction) position of the thermocouple 111 of the temperature sensing unit 110 is 210 mm, for example, at the upper end of the mold 30. This position corresponds to 110 mm, for example, below the meniscus level at which the molten steel M in the mold is full. The reason for determining this position is the position that can stably represent the initial coagulation thermal behavior in one example directly under the tap surface, and the 100 mm point, and also the position of the immersion nozzle, which is one of the functions of an embodiment of the present invention, directly below the surface. This is because it is around 100 mm.

In addition, the width direction of the thermocouple 111 is installed in the width of the tension bolt (tension bolt) position of the tension bolt (tension bolt) position of the mold 30, as an example, the interval is installed in 150mm intervals. Accordingly, the thermocouples 111 are arranged in the long side width direction of the mold 30, thirteen thermocouples 111 are provided per one mold surface, and the same number of thermocouples 111 are provided on the opposite surface. For example, the thermocouples 111 may be arranged in the width direction on both long sides of the mold 30 within 210 mm from the top of the mold 30 and within 110 mm below the bottom surface.

Hereinafter, for convenience of description, the first surface of the mold 30 provided with the thermocouple 111 is referred to as an inside surface and a second surface that is the opposite surface is referred to as an outside surface.

A total of 26 thermocouples 111 on both sides are installed, 13 per side of the mold 30.

The thermocouple 111 mounts a plug 113 by processing holes in the back plate 112 and the mold 30 attached to the mold 30. The thermocouple 111 is inserted into the plug 113, and the tip of the thermocouple 111 contacts the mold 30 at a proper pressure by the force of the fixing pin 114 and the spring 115.

In addition, an O-ring 116 is installed between the plug 113 and the mold 30 and between the plug 113 and the back plate 112 to prevent the cooling water from penetrating into the thermocouple 111.

Referring back to FIG. 2, the control unit 100 mixes mold slag, which is frequently generated during continuous casting of stainless steel, by using temperature data detected through the thermocouple 111 of the temperature sensing unit 110. It predicts abnormalities such as cracking defects in slabs such as crack or face longitudinal depression, face cracks or face horizontal depression, and immersion nozzle failure, which is a serious operation accident caused by increased casting time.

The storage unit 130 stores reference temperature data for determining each of the defects of the cast steel. In addition, the storage unit 130 previously stores reference temperature data for determining the immersion nozzle damage.

The controller 100 uses the temperature data sensed through the thermocouple 111 of the temperature sensing unit 110 and predicts the defect of the cast iron and the immersion nozzle in consideration of the reference temperature data stored in the storage unit 130.

The controller 100 generates a screen corresponding to the predicted result, and provides the generated screen to the display unit 120.

The display unit 120 may display various information according to the control signal of the controller 100.

The display unit 120 may display a screen for warning a worker of a cast iron defect or immersion nozzle damage predicted by the controller 100. On-site operators and engineers can recognize cast defects or immersion nozzle breakages and take appropriate action according to the situation, thus minimizing large operation accidents and large quality accidents.

6 is a schematic diagram showing a schematic configuration of a continuous casting failure prediction apparatus according to an embodiment of the present invention.

Referring to FIG. 6, the thirteen thermocouples 111 provided on the inside surface of the mold 30 from the temperature sensing unit 110 and the thirteen thermocouples 111 provided on the outside surface are controlled by respective compensation leads ( 100 is connected to a connector / panel which plays a role of signal conversion. The connector / panel converts an electromotive force (mV) corresponding to the temperature data of the thermocouple 111 provided in the mold 30 into a digital temperature value to communicate a communication protocol between a PC and a programmable logic controller (PLC) such as Profibus. By using a dedicated PLC corresponding to the main processor of the controller 100. This dedicated PLC uses the thermocouple temperature to predict cast defects such as mold slag mixing, face cracks or face depressions, face cracks or face depressions, and immersion nozzle failure, and provides predicted results for field operators and engineers. Be warned so you know. Such a warning operation is implemented by displaying a warning screen on a dedicated PC corresponding to the display unit 120 using Ethernet communication. This dedicated PLC can be connected to the operation PLC controlling the continuous casting process, and can receive operation data from the operation PLC.

Hereinafter, using the temperature data sensed through the thermocouple to predict cast defects, such as mold slag incorporation, surface vertical crack or surface vertical depression, surface horizontal crack or surface horizontal depression, and immersion nozzle failure in more detail.

7 is a view showing the position of the thermocouple used for immersion nozzle failure prediction in the continuous casting failure prediction apparatus according to an embodiment of the present invention.

Referring to FIG. 7, if the refractory of the immersion nozzle 21 during the continuous casting is broken by thermal erosion or chemical erosion with mold slag, if the operator does not immediately sense it, it will result in a large operation accident and quality accident. If such immersion nozzle breakage occurs, it should be immediately detectable.

Regarding the failure prediction of the immersion nozzle 21, the thermocouples on the central side of the two surfaces (outside and inside) where the thermocouples 111 are installed in the mold 30, for example, three central thermocouples represented by rectangular boxes, respectively. Predicting breakage of the immersion nozzle 21 using a total of six thermocouples.

When the immersion nozzle 21 is broken, the molten steel M is ejected to the place where the immersion nozzle 21 is damaged, and the temperature of the thermocouple 111 around the immersion nozzle 21 is rapidly raised or lowered. This principle is used to predict immersion nozzle failure.

First, the temperature values of each of the three thermocouples 111 at the center side are sensed at each side (fixed side and loose side) of the mold used for immersion nozzle breakage prediction.

The average value of four temperature values except the maximum value and the minimum value among these six temperature values is obtained. When this average value is called a reference value, the alarm value is a value obtained by subtracting the reference value from the temperature values respectively detected from the six thermocouples 111.

When the alarm value exceeds a preset value (surge parameter value, for example, 5 degrees) for thermocouple jump determination (alarm value> spike parameter value), it is determined that the thermocouple temperature rise alarm condition is satisfied. That is, it is determined that the thermocouple temperature has risen sharply.

In addition, if the alarm value is less than the preset value (descent parameter value, for example, -5 degrees) for thermocouple descent determination (alarm value <descent parameter value), the thermocouple temperature descent alarm condition is satisfied. To judge. That is, it is determined that the thermocouple temperature has dropped sharply. The sudden parameter value and the sudden parameter value may be stored in the storage 130 in advance.

If any one of the total of six thermocouples, each of the three mold double-sided center thermocouples, satisfies any one of the thermocouple temperature rise alarm conditions and the thermocouple temperature drop alarm conditions, it is determined that the immersion nozzle 21 is broken.

8 is a view showing a warning message displayed by the continuous casting failure prediction apparatus when predicting the immersion nozzle failure according to an embodiment of the present invention.

Referring to FIG. 8, when any one of the six thermocouples satisfies any one of the thermocouple temperature rising alarm conditions and the thermocouple temperature falling alarm conditions, it is determined that the immersion nozzle 21 is broken, and the immersion nozzle is damaged. A warning message is displayed to warn the operator of the immersion nozzle breakage. The warning message contains information such as "Danger nozzle damage risk".

FIG. 9 is a diagram illustrating a thermocouple position used for mold slag incorporation prediction in a continuous casting abnormality predicting apparatus according to an embodiment of the present invention, and FIG. 10 is a mold slag in a continuous casting abnormality predicting apparatus according to an embodiment of the present invention. It is a graph showing the change of mold temperature when mixing occurs.

9 and 10, when the molten steel flowing out of the immersion nozzle 21 reaches the mold short side part (slice edge part) during continuous casting and the strength of the molten steel suddenly becomes too strong. , The mold slag existing on the molten steel is incorporated into the molten steel.

Therefore, when the molten steel flows in the slab short side part as described above, the temperature of the thermocouple located in the slab short side part is rapidly rising or falling.

As shown in FIG. 10, when mold slag incorporation occurs during continuous casting, a thermocouple located at an edge in the cast slab width causes rapid fluctuations in molten steel flow as shown by an arrow, thereby rapidly increasing the mold temperature.

In one embodiment of the present invention, this phenomenon is used to predict mold slag incorporation.

Since the cast slab width is always changed, it is possible to receive data on the cast slab width currently cast from the operation PLC shown in FIG. 6. Data on the cast casting width may be stored in advance in the storage unit 130.

Knowing the cast casting width, it is possible to determine the thermocouple close to the edge of the cast steel not exceeding the cast casting width, and to determine the mold slag incorporation using the determined thermocouple temperature.

Regarding the prediction of mold slag incorporation, among the thermocouples installed on both sides (outside and inside) of the mold 30, a thermocouple close to the edge of the slab not exceeding the slab casting width based on the slab casting width, for example, a square A total of four thermocouples, two thermocouples represented by boxes, are used to predict mold slag incorporation.

First, among the thermocouples provided on each side (fixed side and loose side) of the mold 30, the temperature values of the remaining thermocouples are detected except for a total of four thermocouples corresponding to the edge portions of the cast slab width, and the average value of the detected temperature values is detected. Obtain When this average value is referred to as a reference value, the alarm value is a value obtained by subtracting the reference value from the temperature values respectively detected from four thermocouples corresponding to the edge portion of the casting width of the thermocouple.

When the alarm value exceeds a preset value (spiking parameter value, for example, 5 degrees) for thermocouple rising judgment (alarm value> zooming parameter value), it is determined that the thermocouple temperature rising alarm condition is satisfied. That is, it is determined that the thermocouple temperature has risen sharply.

In addition, if the alarm value is less than the preset value (descent parameter value, for example, -5 degrees) for thermocouple descent determination (alarm value <descent parameter value), the thermocouple temperature descent alarm condition is satisfied. To judge. That is, it is determined that the thermocouple temperature has dropped sharply. The sudden parameter value and the sudden parameter value may be stored in the storage 130 in advance.

Of the thermocouples provided on each side of the mold 30 (Fixed side and Loose side), any one of the four thermocouples corresponding to the edge of the cast slab width is any one of the thermocouple temperature rising alarm condition and the thermocouple temperature drop alarm condition. If one is satisfied, it is determined that mold slag mixing has occurred.

FIG. 11 is a diagram illustrating a warning message displayed by the continuous casting abnormality predicting apparatus according to an embodiment of the present invention when predicting mold slag mixing. FIG.

Referring to FIG. 11, any one of a total of four thermocouples corresponding to the edge portion of the cast slab among the thermocouples provided on each side of the mold 30 is any one of a thermocouple temperature rise alarm condition and a thermocouple temperature drop alarm condition. If satisfactory is determined, it is determined that mold slag mixing has occurred, and a warning message for warning mold slag mixing is displayed to warn the operator of mold slag mixing. The warning message includes information such as “mold slag mixing detection in the peripheral corner”.

In addition, a warning message can be displayed by dividing the position of the thermocouple. A warning message can be displayed for each mold surface on which mold slag is mixed. For example, the warning message may include information such as "risk of mixing left mold slag", "risk of mixing right mold slag", and "risk of mixing left and right mold slag".

12 is a view showing the position of the thermocouple used for the surface longitudinal crack or surface longitudinal depression prediction in the continuous casting abnormality prediction apparatus according to an embodiment of the present invention, Figure 13 is a continuous casting abnormality prediction according to an embodiment of the present invention This is a graph showing the change of mold temperature when face cracks occur in the device.

12 and 13, surface vertical cracks are caused by non-uniformity of the solidification cell 62 during metallurgical initial solidification in the mold. In this case, the nonuniformity of the coagulation cell 62 causes nonuniformity of heat transfer from molten steel to the mold copper plate, so that the temperature of the thermocouple in the mold 30 is greatly varied.

As shown in Figure 13, looking at the mold temperature results of the cast slab with the face vertical cracks and the good slab did not occur, the mold temperature standard deviation of the slab with face vertical cracks is 3.8 degrees the mold of the good cast without face cracks It can be seen that it is about twice as large as the temperature standard deviation of 1.9 degrees.

In one embodiment of the present invention, using this characteristic to predict the risk of the surface longitudinal crack or surface longitudinal depression of the cast using a standard deviation (degree of instability) of a certain time of the mold temperature.

Most of the vertical cracks of the surface of the cast steel is generated in the center of the cast steel, the width of the cast steel is mostly 1000mm or more, so in one embodiment of the present invention, the thermocouple for determining the vertical crack in the surface of the mold, each of the two sides of the center of the mold on both sides of the mold (5) For example, a thermocouple having a cast width of 600 mm) may be used. A total of 10 thermocouples are used to predict the occurrence of surface longitudinal cracks or surface longitudinal depressions.

The standard deviation used for the prediction of surface longitudinal crack or surface longitudinal depression is calculated using the following equation [1].

식 [1]

Formula [1]

Where xk is the measured value of the kth individual and N is the number of samples.

For example, the standard deviation is calculated based on the temperature data from an evaluation time criterion (for example, one minute) to the determination time point based on the current determination time to determine whether there is a surface vertical crack or surface vertical depression.

The specific determination method is as follows.

First, the temperature values of 10 thermocouples in total (five fixed side and loose side), including two from each side of the mold and two from the center (-300mm, -150mm, 0,150mm, 300mm) are respectively detected. Standard deviation values for a certain time are calculated for each thermocouple temperature. Calculate the average of the standard deviations for each thermocouple on each side (mean of the standard deviation values of each fixed side thermocouple and the mean of the standard deviation values of the loose side).

If the average standard deviation value calculated for each side is compared with the standard deviation parameter value (for example, 2.5 degrees) for judging the occurrence of the vertical crack or the surface longitudinal depression, the average standard deviation value exceeds the standard deviation parameter value. Face cracks or face vertical depression occurred on the fixed side or loose side.

At this time, it is determined whether the vertical crack or the surface vertical depression occurs in each surface.

FIG. 14 is a diagram illustrating a warning message displayed by a continuous casting abnormality predicting apparatus according to an embodiment of the present invention when predicting surface vertical cracks or surface vertical depressions.

Referring to FIG. 14, an average standard deviation value, which is an average value of standard deviations calculated for five thermocouples for each side of the mold 30, is used to determine a standard deviation parameter value for determining surface vertical crack or surface vertical depression. If exceeded, it is determined that face cracks or face depressions have occurred on the fixed side or fixed side, and a warning message is displayed to alert the operator.

The warning message may include "detailed duty free crack detection" information.

The warning message can be divided and warned by the side where the vertical crack occurrence is predicted. For example, a warning message may contain information such as “Inside Side Crack Hazard”, “Outside Side Vertical Hazard Hazard”, or “Inside and Outside Side Hazard Hazard”.

FIG. 15 is a diagram illustrating thermocouple positions used for predicting surface horizontal crack or surface horizontal depression in a continuous casting abnormality predicting apparatus according to an embodiment of the present invention, and FIG. 16 is a continuous casting abnormality prediction according to an embodiment of the present invention. This is a graph showing the change of mold temperature when the surface crack occurs in the device.

15 and 16, the plane transverse depressions are formed at the beginning of solidification in the mold. The plane transverse cracks will be accompanied by the plane transverse depressions. When the horizontal lateral depression occurs, if the position where the depression is located is located in the thermocouple, the mold temperature is greatly reduced because heat is not transferred from the molten steel to the mold copper plate due to the depression effect. If the depression position moves downward as the casting progresses, and the cast steel comes into contact with the thermocouple, the mold temperature rises to normal again, and if the depression occurs at regular intervals, the mold temperature also changes at regular intervals.

As shown in FIG. 16, it can be seen that the mold temperature of the slab in which the plane lateral depression occurred is greatly reduced at a constant cycle.

In one embodiment of the present invention, by using such a characteristic to predict the risk of the surface transverse crack or surface transverse depression of the cast.

In an embodiment of the present invention, the thermocouple for determining the plane horizontal crack or the plane horizontal depression may use the same thermocouple as the plane longitudinal crack or the plane longitudinal depression determination. That is, predicting the occurrence of surface transverse cracks or surface transverse depressions using a total of ten thermocouples of five mold double-sided central thermocouples represented by rectangular boxes.

The specific determination method is as follows.

First, the temperature values of 10 thermocouples in total, including five on each side (fixed side and loose side) including two from the center and two from the center, are sensed (-300mm, -150mm, 0,150mm and 300mm), respectively.

The temperature difference between the temperature value of each thermocouple before a predetermined time (for example, the temperature value of each thermocouple 5 minutes ago) and the current temperature value of each thermocouple is respectively calculated, and each of the absolute values of the calculated temperature differences is calculated. If any of the above-described temperature parameter values (for example, 5 degrees) is exceeded for determining the plane horizontal crack or the plane horizontal depression, it is determined that the plane horizontal crack or the plane horizontal depression has occurred.

At this time, it is possible to determine the occurrence of the horizontal crack or the surface horizontal depression by dividing by each surface. That is, it is possible to determine whether or not the surface horizontal crack or the surface horizontal depression occurs.

FIG. 17 is a diagram illustrating a warning message displayed by a continuous casting abnormality predicting apparatus according to an embodiment of the present invention when predicting a plane horizontal crack or a plane horizontal depression.

Referring to FIG. 17, if there is a thermocouple in which the absolute value of the temperature difference value between the previous temperature value and the current temperature value of the thermocouple among the five central sides of each mold 30 exceeds a preset temperature parameter value, It is determined that the surface crack or surface horizontal depression has occurred on the surface corresponding to the thermocouple, and a warning message is displayed to warn the operator.

The warning message may include "depression (crack) detection by face value" information.

The warning message can be classified and warned by the side where the side crack is predicted. For example, a warning message may contain information such as "Inside Side Crack Hazard", "Outside Side Side Hazard Hazard", or "Inside and Outside Side Hazard Hazard".

Claims (6)

A temperature sensing unit having a plurality of thermocouples arranged at intervals from each other in a mold supplied with molten steel in a tundish through an immersion nozzle; And Determination of at least one of cast defects including at least one of mold slag incorporation, slab face cracks and slab face cracks using the temperature values detected from the plurality of thermocouples during the continuous casting process, and immersion nozzle breakage Continuous casting abnormality prediction device comprising a control unit. The method of claim 1, And the plurality of thermocouples are arranged in the width direction on both long sides of the mold within 110 mm from the upper end of the mold and within 110 mm below the surface of the molten steel filled with molten steel in the mold. The method according to claim 1 or 2, The controller compares the center thermocouple temperature and the remaining thermocouple temperature of the thermocouples provided on both sides of the mold, and when the central thermocouple temperature rises or falls faster than the remaining thermocouple temperature, the continuous casting abnormality predicting device. The method according to claim 1 or 2, The control unit compares the thermocouple temperature corresponding to the edge portion of the cast casting width with the remaining thermocouple temperature among the thermocouples provided on both sides of the mold, and when the edge portion thermocouple temperature rises or falls faster than the remaining thermocouple temperature, mixing of the mold slag occurs. Continuous casting abnormality prediction device judged to be. The method according to claim 1 or 2, The control unit is a continuous casting abnormality prediction device that determines that the vertical crack is generated in the slab if the average standard deviation of the thermocouples on the mold both sides of the mold is higher than the predetermined value. The method according to claim 1 or 2, The control unit is a continuous casting abnormality prediction device that determines that the horizontal crack is generated in the slab when the temperature of the central thermocouple of the thermocouple provided on both sides of the mold is periodically higher than the predetermined value.

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