JP7183632B2 - Continuous casting apparatus and continuous casting method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a continuous casting apparatus and a continuous casting method, and more particularly, to a continuous casting apparatus equipped with a means for detecting deposits of scale on rolls conveying slabs, and a continuous casting apparatus using such a continuous casting apparatus. It relates to a method of making castings.

In a continuous casting apparatus, rolls are used to sandwich and convey a slab from opposite directions, but the scale formed on the surface of the slab tends to flake off and accumulate on the surface of the rolls.

In a continuous casting apparatus, roll rotation may be abnormal due to various factors. In a continuous casting apparatus, as a method for detecting abnormal rotation of the roll, for example, Patent Document 1 discloses that a protrusion is provided along the circumference near the end of the continuous casting roll, and the roll collides with the protrusion during rotation of the roll. A configuration is disclosed that uses a detector to detect the rotation of the . In addition, in Patent Document 2, a measuring means for measuring at least two opposing gaps between a pair of rolls and a difference between at least two measured values measured by the measuring means are calculated, and the measurement at each measurement position determining means for calculating a difference from a previously measured value and determining a bearing abnormality supporting both ends of the roll when each calculated value exceeds a preset threshold value. A detection device is disclosed. As a measuring means, a roll-gap measuring device comprising a rotary encoder, an operating transformer, etc. is used, and the roll-gap measuring device is installed on a dummy bar of a continuous casting machine inserted between a pair of rolls.

JP-A-2000-102849 JP 2006-247687 A

As described in Patent Literature 1, if the roll rotation state is detected by utilizing collision of the roll with a projection or the like, the rotation state of the roll can be constantly detected while the continuous casting apparatus is operating. can be monitored and the occurrence of abnormalities can be detected. However, it is difficult to identify the cause of the abnormality in the rotation state of the roll based on the monitoring results. Possible causes of abnormal rotation of the roll include wear of the roll itself, failure of hydraulic equipment, and failure of bearings. In addition, when scale deposition occurs in association with abnormal rotation, it is also difficult to determine the degree of scale deposition based on the results of monitoring the rotational state. Therefore, when an abnormal rotation is detected, it is necessary for the manager of the continuous casting apparatus to visually check the state of the rolls and determine the presence or absence and extent of scale deposits. In addition, when scale deposits occur in connection with the abnormal rotation, it is necessary to confirm how much scale is deposited, and then determine measures to be taken, such as removal.

On the other hand, according to the method of Patent Literature 2, it is possible to selectively detect an abnormality in the bearing among various factors that may cause an abnormality in the rotational state of the roll. However, since a roll gap measuring device installed on a dummy bar is used to measure the facing gap between rolls, the roll gap is measured and abnormalities are detected only during rest periods when the continuous casting machine is not in operation. I can't. Therefore, when an abnormality occurs, it is difficult to take countermeasures at an early stage. Moreover, when an abnormality is detected by measuring the roll interval during the resting period, it is difficult to narrow down the retroactive range from when the abnormality occurred.

Furthermore, in both methods of Patent Documents 1 and 2, it is possible to detect abnormalities occurring in the rolls and bearings, but how much the abnormalities in the manufacturing equipment affect the quality of the manufactured slab. It is difficult to judge whether to give based on the detection results. The degree of influence on quality influences the urgency with which countermeasures must be taken against manufacturing facility abnormalities and the selection of countermeasures to be taken.

The problem to be solved by the present invention is to provide a continuous casting apparatus and such a continuous casting method that can selectively detect scale deposition on the rolls during operation.

In order to solve the above problems, the continuous casting apparatus according to the present invention observes the surface state of the rolls that sandwich and convey the slab from opposite directions and the surface of the slab discharged from the rolls, and obtains observation information. and based on the observation information, detects a flaw present on the contact surface, which is the surface of the slab that has passed through contact with the roll, and determines that at least one of depth and size is a threshold and determination means for determining that scale is deposited on the roll when there is a flaw exceeding the contact surface.

Here, the roll is provided at least on the lower side in the direction of gravity with respect to the cast slab being conveyed, and when the cast slab passes through the roll, the surface that was present on the lower side in the direction of gravity is The contact surface may be observed by the observing means and judged by the judging means.

The continuous casting apparatus further includes cutting means for cutting the cast slab downstream of the rolls, and the observing means is a camera provided downstream of the cutting means. It is preferable that the cut surface of the cast slab obtained by is photographed, and the determination means detects flaws present on the edge of the cut surface.

The continuous casting apparatus further has a weigher that makes the cast slab stay and measures the mass of the cast slab. , the observation information may be acquired.

In the continuous casting method according to the present invention, continuous casting is performed using the above-described continuous casting apparatus, and when the determining means determines that scale has accumulated on the roll, measures are taken against the scale accumulation. It is something to do.

In the continuous casting apparatus according to the above invention, the surface condition of the cast slab discharged from the rolls is observed, and scratches exceeding predetermined thresholds in depth and size are formed on the contact surface after coming into contact with the rolls. If so, it is determined that scale has accumulated. If a certain amount of scale accumulates on the roll, the surface of the cast slab discharged from the roll will be damaged. Therefore, by detecting the flaws on the contact surface of the slab, it is possible to selectively detect scale deposition on the rolls by distinguishing them from other abnormal factors that do not cause the occurrence of flaws. In addition, since the surface condition of the cast slab discharged from the rolls is observed, the presence or absence of scale deposition is monitored while the continuous casting equipment is in operation, and if scale deposition occurs, it is immediately detected. can do.

The formation of scratches on the contact surface of the slab does not occur unless a certain amount of scale is deposited. It is possible to detect scale build-up that reaches an amount that affects the quality of the slab as a product, distinguishing it from the slight build-up of scale on the roll. By measuring the depth and size of the scratches, the degree of scale deposition can be evaluated in more detail.

Here, the roll is provided at least on the lower side in the direction of gravity with respect to the slab being conveyed, and the surface that was present on the lower side in the direction of gravity when the slab passes through the roll is the contact surface, When the observation by the observation means and the determination by the determination means are performed, it is possible to sensitively detect scale deposition on the lower roll in the direction of gravity, which can greatly affect the quality of the cast slab. Due to the weight of the slab, scale is particularly likely to be caught between the roll and the slab located on the lower side in the direction of gravity, and the caught scale tends to cause deep and large scratches on the surface of the slab. be.

The continuous casting apparatus further has a cutting means for cutting the cast slab downstream of the rolls, and the observation means is a camera provided downstream of the cutting means, and the cast slab obtained by cutting with the cutting means. When the cut surface is photographed and the determination means detects flaws present on the edge of the cut surface, the observation means can be installed with a simple configuration. In addition, the flaws formed on the contact surface of the slab can be easily and accurately detected as defects or depressions at the edges in the observed image of the cut surface.

The continuous casting apparatus further has a weigher that makes the cast slab stay and measures the mass of the cast slab, and the observation means obtains observation information for the cast slab while staying on the weigher. In this case, the observation information is acquired while the slab is stationary for mass measurement, thereby obtaining high-quality observation information that enables highly accurate detection of flaws.

In the continuous casting method according to the present invention, casting is performed using the continuous casting apparatus having the observation means and determination means as described above. Scale build-up on the roll can be selectively detected using the formation of scratches on the surface as an indicator. When scale deposits are detected, the manager of the continuous casting apparatus or the like can quickly take measures such as scale removal.

1 is a side view showing a schematic configuration of an upstream portion of a continuous casting apparatus according to one embodiment of the present invention; FIG. FIG. 4 is a top view showing a schematic configuration of a downstream portion of the continuous casting apparatus; It is a figure explaining image|photography of the cut surface of a slab with a camera. It is an example of the obtained photographed image. It is a figure explaining the detection method of the crack in a picked-up image.

A continuous casting apparatus and a continuous casting method according to one embodiment of the present invention will be described below with reference to the drawings.

[Overview of Continuous Casting Apparatus and Continuous Casting Method]
1 and 2 schematically show a continuous casting apparatus 1 according to one embodiment of the present invention. 1 is a side view of the upstream portion, and FIG. 2 is a top view of the downstream portion.

In the continuous casting apparatus 1 , a slab B made of a metallic material continuously cast by a mold 2 is transported downward from above by a roll group 10 . In the roll group 10, a plurality of rolls including support rolls 11 (11a, 11b), guide rolls 12 (12a, 12b), and pinch rolls 13 (13a, 13b) are arranged side by side along the transport path of the cast slab B. It is The rolls 11, 12, and 13 are conveyed while facing the upper rolls 11b, 12b, and 13b arranged on the upper side in the direction of gravity with respect to the conveyed slab B, and the upper rolls 11b, 12b, and 13b, respectively. It has lower rolls 11a, 12a and 13a arranged on the lower side in the gravitational direction with respect to the cast slab B. Furthermore, in addition to the upper and lower rolls, the rolls 11, 12, and 13 face each other laterally with respect to the conveying direction D of the slab B, that is, on the front side and the back side of the paper surface of FIG. It has a pair of side rolls (not shown) arranged as one.

A drive shaft 13c is connected to an upper pinch roll 13b that constitutes the pinch roll 13 provided most downstream in the roll group 10, and is driven to rotate. The lower pinch roll 13a, the support roll 11, and the guide roll 12 are not driven in axial rotation and function as driven rolls. By axially rotating the upper pinch roll 13b in the conveying direction D for conveying the slab, the slab B is sandwiched between the upper pinch roll 13b and the lower pinch roll 13a and pulled out in the conveying direction D. The cast slab B sandwiched by the rolls 11, 12, and 13 from opposite directions is conveyed in the conveying direction D by the pinch roll 13 withdrawing and the other rolls 11 and 12 being driven to rotate. A water cooling device (not shown) is arranged in the vicinity of the roll group 10 and jets water to the slab B conveyed by the roll group 10 to cool the slab B. As shown in FIG.

A roller table 21 having a plurality of transport rollers arranged in parallel is provided downstream of the pinch rolls 13 . The roller table 21 continuously conveys the slab B pulled out by the pinch rolls 13 and discharged from the roll group 10 along the conveying direction D. A torch car 22 is provided as a cutting means at a portion on the upstream side of the roller table 21 . The torch car 22 is equipped with a gas cutting device, and cuts (fuses) the slab B into pieces of a predetermined length. The present continuous casting apparatus 1 is a two-strand type apparatus, and each component from the mold 2 to the roller table 21 is arranged side by side. can be done.

A transfer device 23 is provided at the downstream end position of the roller table 21 . The transfer device 23 can lift and convey the cast strip B that has been cut by the torch car 22 and has reached the downstream end of the roller table 21 . The transfer device 23 can lift the slab B from the roller table 21 and move it to a weighing machine 42 provided downstream of the roller table 21 . The cast strip B that has reached the downstream end of the roller table 21 is lifted by the transfer device 23 and placed on the placing surface 42 a of the weighing machine 42 .

The weighing machine 42 is a device that measures the weight of an object placed on the placement surface 42a. After the slab B is placed on the placement surface 42a of the weighing machine 42, the transfer device 23 is once separated from the slab B and is in a state where it does not come into contact with either the slab B or the placement surface 42a. In this state, the slab B is made to stay still on the mounting surface 42a for a predetermined staying time. The residence time is the time required for weight measurement by the weighing machine 42, and the weight (mass) of the cast slab B stationary on the mounting surface 42a is measured. Then, based on the weight, it is determined whether or not the slab B having a predetermined cross-sectional area and length has been manufactured.

An unloading roller table 43 is provided downstream of the weighing machine 42 , and the cast slab B determined to have a predetermined mass by mass measurement by the weighing machine 42 is transferred by the transfer device 23 . , are accumulated on the carry-out roller table 43 . The cast slab B accumulated on the unloading roller table 43 is conveyed to a device for the next process, such as a rolling mill, by a cast slab carriage 44 .

The continuous casting apparatus 1 further has a flaw detection device 30 . The flaw detection device 30 includes a camera 31, a light source 32, and an analysis terminal 33, as shown in FIGS.

The camera 31 functions as observation means for observing the state of the surface of the slab B and acquiring observation information. Here, the camera 31 is arranged on the side of the weighing machine 42 so as to photograph the end surface B1 of the cast slab B staying on the mounting surface 42a of the weighing machine 42 . Here, the end surface B1 of the slab B is one of the surfaces of both ends in the longitudinal direction of the slab B and corresponds to the cut surface cut by the torch car 22 . When the cast slab B is placed on the mounting surface 42a of the weighing machine 42, the camera 31 is positioned in front of the position where the end surface B1 of the cast slab B is arranged, with the photographing direction A extending in the longitudinal direction of the cast slab. They are aligned and arranged, and the end face B1 of the slab B can be photographed. In addition, the camera 31 is a network camera, and can transfer the photographed image to the analysis terminal 33, and control such as setting of photographing conditions can be performed from the analysis terminal 33.

Similarly to the camera 31, the light source 32 is also installed on the side of the weighing machine 42, and covers the area including the end surface B1 of the cast slab B staying on the mounting surface 42a of the weighing machine 42, which is photographed by the camera 31. , emit light L. Irradiation of the light L enables the camera 31 to clearly photograph the end surface B1 of the slab B mounted on the mounting surface 42a. As a specific light source 32, for example, an LED lighting device can be used.

The analysis terminal 33 is composed of a computer, and can acquire images from the camera 31 and control photographing conditions. In addition, the analysis terminal 33 functions as determination means for analyzing the captured image as observation information acquired from the camera 31 . That is, the flaws on the surface of the cast slab B are detected based on the photographed image, and the presence or absence of scale deposition on the upstream roll group 10 is determined based on the detection result of the flaws. The details of the analysis are detailed below. The analysis terminal 33 executes the analysis process without being affected by the heat from the slab B, and is located away from the continuous casting line, for example, to control the line so that the manager can monitor and operate it. installed in the room.

[Detection of scale deposition by image analysis]
As described above, the continuous casting apparatus 1 includes the camera 31 and the flaw detection device 30 including the analysis terminal 33 functioning as determination means. Then, based on the photographed image acquired by the camera 31, the analysis terminal 33 determines whether scale is deposited on the rolls 11, 12, and 13 constituting the roll group 10. FIG.

In the continuous casting apparatus 1, the slab B drawn from the mold 2 is gradually cooled and solidified while passing through the roll group 10 from upstream to downstream, but maintains a high temperature state of approximately 800° C. or higher. . Oxidation occurs on the surface of the hot slab B and scale is formed. When the cast slab B with such scales formed on the surface thereof is conveyed to the roll group 10 by sandwiching it between pairs of rolls 11, 12, and 13 facing each other, friction with the rolls 11, 12, and 13 causes Scales may flake off from the surface of the billet B in some cases. The peeled off scale easily adheres to the surfaces of the rolls 11 , 12 , 13 . When the peeled-off scales adhere to each other, the scales are deposited on the surfaces of the rolls 11 , 12 , and 13 . Scale build-up reduces the distance between opposing rolls. If the rolls 11, 12, and 13 rotate while sandwiching the slab B in that state, the rotation state of the rolls 11, 12, and 13 will change from the state in which scale is not deposited. Then, normal continuous casting cannot be performed, and the quality of the slab B to be manufactured may be affected. Also, an excessive load is applied to the roll group 10 .

When scale is deposited on the surface of any one of the rolls 11, 12, and 13, the surface of the cast slab B, which is in a high-temperature and soft state, is scratched by contact with the scale when passing through the roll, and the surface is scratched. A wound is formed. Therefore, in the slab B discharged from the roll group 10, if scratches are formed on the contact surface, which is the surface that has come into contact with the rolls 11, 12, and 13, the surface of the slab B is damaged. It can be detected that scale build-up is occurring on the surfaces of the rolls 11, 12, 13.

FIG. 4 shows an example of a photographed image obtained by photographing the end surface B1 of the cast slab B staying on the mounting surface 42a of the weighing machine 42 from the front using the camera 31. As shown in FIG. The end surface B1 of the slab B is brightly observed as a substantially rectangular area. In the photograph, the upper and left and right edges are observed to be almost straight, while the lower edge has an irregular shape that is recessed toward the inside of the surface, slightly to the left of the center. A concave structure can be seen. This concave structure corresponds to scratches formed on the bottom surface B2 (the surface in contact with the mounting surface 42a) of the cast slab B by the scales deposited on the rolls 11, 12, and 13. As shown in FIG. If scale accumulates on the rolls 11, 12, 13, scratches will continue to be formed on the surface of the cast slab B along the longitudinal direction at the same position unless the scale is removed. Therefore, by observing the end surface B1, which is a cut surface obtained by cutting with the torch car 22, scratches formed on the bottom surface B2 along the longitudinal direction of the slab B can be detected.

Here, a method for automatically detecting the presence or absence of flaws and scale deposits by analyzing a photographed image of the end surface B1 of the cast slab B will be described. FIG. 5 shows an enlarged view of the image of FIG. 4, and each step of analysis for the image will be described.

First, the photographed image obtained by the camera 31 is converted into two colors so that the flaw can be easily detected. Then, a corner specifying step is performed to specify the position corresponding to the corner of the bottom surface B2 of the cast slab B in the image. For example, in the image, after approximating the upper side and the left and right sides of the end face B1 of the slab B with straight lines, the approximate straight line corresponding to the upper side is arranged at the position corresponding to the lower side, and the straight line and the left and right sides correspond to It suffices to identify the intersection point with the approximate straight line to be the corner of the bottom surface B2. In FIG. 5, the positions of the detected corners are indicated by circles and reference numerals 1. FIG.

Next, a pixel correspondence process is performed. Here, the correspondence relationship between the number of pixels on the image and the actual length of the slab B is specified. That is, it estimates how many millimeters one pixel corresponds to. For this purpose, the number of pixels occupied by the slab B is counted along the long side direction (horizontal direction) of the slab B in the image, as indicated by a double-headed straight line and reference numeral 2 in FIG. The number of pixels is counted at a plurality of locations (for example, 10 locations) in the short side direction (longitudinal direction) of the slab B, and the average value is calculated. Then, by dividing the length of the long side of the actual slab B, which is known according to the casting conditions such as the shape of the mold 2, by the average value of the obtained number of pixels, one pixel in the image is obtained. You can estimate the actual length you want.

Next, a flaw detection step is performed. First, the two corners of the bottom surface B2 detected in the corner detection step are connected by a straight line to form a reference line. A reference line is also displayed in FIG. This reference line can be regarded as the position of the bottom surface B2 when no scratches are formed. When the reference line is obtained, the reference line is compared with the position of the actual lower edge of the slab B on the image at each portion along the reference line. If a region where the bottom edge is located above the reference line is continuous over a certain length along the reference line, it can be determined that the region has a scratch. . In FIG. 5, it can be determined that the area indicated by the ellipse and reference numeral 3 has a flaw.

Once the presence of a flaw is detected in this manner, the depth of the detected flaw is then estimated. At this time, the position of the deepest flaw in the flaw, that is, the position where the lower edge of the slab B is farthest upward from the reference line is detected, and the number of pixels corresponding to the depth of the flaw at that position is detected. to measure Then, using the correspondence relationship between the number of pixels and the actual length obtained by the pixel correspondence process, the depth of the scratch is converted from the number of pixels to the actual depth. Further, the depth threshold stored in the analysis terminal 33 is compared in advance, and if the depth obtained through the above conversion is larger than the threshold, the rolls 11, It is determined that scale is deposited on 12 and 13. Here, the threshold value is determined by prior tests and past achievements, when there is scale deposition that has a non-negligible effect on the rotation state of the rolls 11, 12, and 13 and the quality of the resulting slab B. , the minimum value of the depth of flaws formed on the surface of the slab B, and stored in the analysis terminal 33 .

Here, instead of the depth of the flaw, the area of the flaw may be used as a parameter for determining the presence or absence of scale deposition. In that case, in the image, the number of pixels in the area sunken above the reference line is measured, converted to an actual area, and if the value is greater than a pre-stored area threshold, the roll It is determined that the rolls 11, 12, and 13 forming the group 10 have accumulated scale. Determination based on the area of the scratch may be used together with determination based on the depth.

In the image of FIG. 5, the flaw is observed on the lower edge of the end surface B1, which means that the flaw is formed on the bottom surface B2 of the cast slab. That is, it indicates that scale is deposited on any of the lower rolls 11a, 12a, and 13a.

When analysis terminal 33 determines in the flaw detection step that scale has accumulated on rolls 11, 12, and 13 based on the depth and/or area of flaws formed on the surface of slab B, Optionally, an alarm step is then performed. In other words, the screen of the analysis terminal 33 and the alarm device connected to the analysis terminal 33 generate an alarm by means of visual information and sound, and the operator of the continuous casting apparatus 1 is notified that scale has accumulated on the rolls 11, 12, and 13. is happening. The administrator who received the notification takes action against the buildup of scale on the rolls 11 , 12 , and 13 . For example, once the casting by the mold 2 and the transportation by the roll group 10 are stopped, the surfaces of the rolls 11, 12, and 13 constituting the roll group 10 are visually checked to identify the scale deposition locations. and remove the scale. In addition, as a treatment, even if the scale is not necessarily removed, for example, depending on the result of visual observation, etc., only confirmation is included.

As described above, the surface of the slab B discharged from the roll group 10 is observed, and the formation of scratches on the surface is used as an index to detect scale deposition on the rolls 11, 12, and 13, thereby enabling continuous casting. The presence or absence of scale deposition can be continuously monitored without stopping the operation of the apparatus 1 . As a result, any buildup of scale can be detected early and necessary action taken before it leads to serious anomalies.

Major anomalies that can occur in the rolls 11, 12, 13 include deposition of scales on the rolls 11, 12, 13, abrasion of the surfaces of the rolls 11, 12, 13, hydraulic equipment, Failure of the device for driving the rolls 12, 13, failure of the bearings supporting the rolls 11, 12, 13, etc. can be considered. However, among these major abnormal factors, the only one that can damage the surface of the slab B is the deposition of scale on the rolls 11, 12, and 13 substantially. Therefore, by using the formation of scratches on the surface of the slab B as an indicator of abnormality detection, it is possible to selectively detect scale deposition on the rolls 11, 12, and 13 by distinguishing it from other abnormalities. can.

In addition, even if the rotation state of the rolls 11, 12, 13 is slightly affected by adhesion of scales to the rolls 11, 12, 13, as long as the quality of the slab B obtained as a product is not affected. , no immediate action is required. If even a slight amount of scale that does not affect the quality of the cast slab B adheres to it, it is notified by an alarm or the like, and if measures such as visual confirmation and removal are performed, the operation efficiency of the continuous casting apparatus 1 will be improved. decreases. However, as described above, flaws, which are quality abnormalities, are detected on slab B, which is the product itself. It is possible to selectively detect scale deposits that have reached such a degree as to give .DELTA. Furthermore, as described in the flaw detection step, the depth and area of the actual flaw are compared with the threshold value, and if the threshold value is exceeded, it is determined that scale deposition has occurred. Depending on the settings, the degree of scale build-up to be addressed can be selected according to product type and the like. If the degree of scale deposition can be evaluated in more detail not only from the magnitude relationship with the threshold value, but also from the depth and area of the scratch, an alarm, etc., will be issued and the scale deposition that should be dealt with by the administrator. can be set more flexibly. It should be noted that the determination of the degree of scale deposition based on the results of scratch detection and the determination of the necessity of treatment based on the determination results may not necessarily be performed automatically by the analysis terminal 33. Based on the photographed image displayed on the screen of the analysis terminal 33, the analysis result, and the like, the determination and part of the determination may be performed.

In FIG. 5, a scratch is formed on the lower edge of the end face B1, and by detecting the scratch, it can be determined that scale has accumulated on the lower rolls 11a, 12a, and 13a. Accumulation of scale is more likely to occur on the lower rolls 11a, 12a, and 13a where scale is likely to be caught by the weight of the slab B than on the upper rolls 11b, 12b, and 13b and the side rolls. In addition, the deposited scale tends to form scratches with a large depth and area on the surface of the slab B. Therefore, when the slab B passes through the roll group 10, the bottom surface B2 existing on the lower side in the gravitational direction is easily damaged. Therefore, as described in the analysis method above, the corner of the slab B on the bottom surface B2 side is detected in the corner detection step, and in the flaw detection step, the edge surface is detected based on the reference line defined by the position of the corner. By detecting the presence of scratches on the lower edge of B1, it is possible to sensitively detect scale deposition using the detection of scratches as an index. In addition, since analysis of the presence or absence of scratches on the upper edge and side edges can be omitted, scale deposition can be easily detected. In this way, when the slab B passes through the roll group 10, the bottom surface B2, which was in contact with the lower rolls 11a, 12a, and 13a, is used as a contact surface for observation by the camera 31 and for determination of the presence or absence of scratches. By doing so, the deposition of scale can be detected efficiently. In addition, as described above, the main abnormal factors other than scale deposition, which have a correlation with the rotation abnormality of the rolls 11, 12, 13, such as wear of the rolls 11, 12, 13, are scratches on the surface of the slab B. However, even if there are other factors that cause scratch formation, if the formation of scratches is more serious on the bottom surface B2 than on other surfaces, scale formation It can be determined that the damage is caused by deposition.

In the continuous casting apparatus 1, the end surface B1 is photographed by the camera 31 as the flaw detection device 30, and the photographed image is used as observation information. The observation means for doing so is not limited to the camera 31 . However, by using the camera 31 as an observation means, it is possible to detect the formation of scratches on the surface of the hot cast slab B with high sensitivity and accuracy with a simple configuration.

The surface of the slab B to be photographed by the camera 31 is not particularly limited, either. When the surface is photographed from the front, the existence of the flaw is detected by the difference in the state of reflection and scattering of the light L between the flaw formed on the contact surface and the surrounding flat portion. It will be. For example, the scratched portion will be observed with a different brightness and color than the surrounding flat portion. When a flaw is detected based on information such as brightness and color distribution on an image, the flaw detection sensitivity tends to be low. However, as described above, when photographing the end surface B1, which is a surface that intersects the contact surface, the scratches formed on the contact surface along the longitudinal direction of the cast slab B are removed from the surrounding edges. It can be detected by information on the distribution of shapes, which is called structure. In this case, it is possible to detect flaws with higher sensitivity and more clearly than when information on brightness and color distribution is used. The parameters used as indicators for determining the presence or absence of scale deposits on the rolls 11, 12, and 13 by comparison with a predetermined threshold value include the site to be observed in the cast slab B, the observation direction, the type of observation means, At least one of the depth and size of the scratch may be used depending on the circumstances. The size of the scratch may be evaluated using at least one of the scratch area (cross-sectional area or opening area), width, and length as an index. If the actually obtained measurement value for the selected parameter exceeds a preset threshold value, it can be determined that scale has accumulated on the rolls 11 , 12 , 13 . In particular, by using the depth of the scratches as an indicator, it is possible to sensitively detect the state in which the scales are highly piled up on the surfaces of the rolls 11, 12, and 13. FIG.

In order to detect scale deposits on the rolls 11, 12, and 13, there is no particular limitation on the position in the continuous casting apparatus 1 at which flaws in the cast slab B are detected. In order not to detect flaws that may be formed due to factors other than deposition, it is necessary to complete detection of flaws at a stage prior to performing subsequent processing, such as rolling, after continuous casting. Above all, in order to accurately observe the surface state of the slab B by an observation means such as a camera 31 and provide high-quality observation information to the analysis terminal 33, the observation by the observation means is carried out so that the slab B is observed in the roll group 10. It is preferable to perform this operation while stationary rather than while being transported by the roller table 21 . After the torch car 22 that cuts the slab B, the slab B stays on the mounting surface 42a of the weighing machine 42 described above as a period during which the stationary slab B can be observed such as photographing. In addition to the period during which the cast slab B is lifted from the roller table 21 by the transfer device 23 and moved toward the weighing machine 42, a period can be mentioned. However, the slab B being transported by the transfer device 23 is in a high temperature state of about 800° C., and a large amount of scale is formed on the surface. Surface scales interfere with accurate detection of flaws. On the other hand, if the slab B is cooled before it reaches the weighing machine 42, the thermal shock causes the scale to flake off from the surface of the slab B, making it easier to accurately detect surface flaws. Therefore, it is preferable to acquire the observation information at the position of the weighing machine 42 .

Although the embodiments of the present invention have been described above, the present invention is not particularly limited to these embodiments and can be modified in various ways.

1 continuous casting device 2 mold 10 roll group 13 pinch roll 13a lower pinch roll 13b upper pinch roll 21 roller table 22 torch car (cutting means)
23 transfer device 30 flaw detection device 31 camera (observation means)
32 light source 33 analysis terminal (determining means)
42 weighing machine 42a placement surface B slab B1 end face (cut surface) of slab
B2 Bottom surface of slab D Conveying direction L Light

Claims (5)

A roll that sandwiches and conveys the cast slab from the opposite direction,
a weighing machine that allows the cast slab to stay and measures the mass of the cast slab ;
Observation means for observing the state of the surface of the cast slab discharged from the roll and staying in the weighing machine to obtain observation information;
Based on the observation information, flaws present on the contact surface, which is the surface of the cast slab that has come into contact with the roll, are detected, and if at least one of depth and size exceeds a threshold value, the flaw is detected on the contact surface. and determination means for determining that scale is deposited on the roll when the scale is present in the continuous casting apparatus. The roll is provided at least on the lower side in the direction of gravity with respect to the cast slab that is conveyed,
2. Observation by said observation means and determination by said determination means are performed with the surface that was on the lower side in the direction of gravity as said contact surface when said cast slab passes through said rolls. Continuous casting apparatus according to. The continuous casting apparatus further has a cutting means for cutting the cast slab downstream of the rolls,
The observation means is a camera provided at a later stage than the cutting means, and photographs a cut surface of the cast slab obtained by cutting with the cutting means,
3. The continuous casting apparatus according to claim 1, wherein said determining means detects flaws present on the edge of said cut surface. 4. Any one of claims 1 to 3, wherein the cast slab determined to have a predetermined mass by the mass measurement by the weighing machine is conveyed to an apparatus for the next process of continuous casting. Continuous casting equipment according to the paragraph. Continuous casting is performed using the continuous casting apparatus according to any one of claims 1 to 4,
A continuous casting method according to claim 1, characterized in that, when the determination means determines that scale has accumulated on the roll, a measure is taken to deal with the accumulation of scale.

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