Bulging amount measurement device, bulging amount measurement method, and slab manufacturing method

Abstract

Provided is a bulging amount measurement device capable of measuring the bulging amount of a cast slab in a non-contact manner even in an environment in which a large amount of steam is generated at a high temperature.　The present invention pertains to a bulging amount measurement device for measuring the bulging amount of a cast slab cast by a continuous casting machine, the bulging amount measurement device comprising: a two-dimensional laser distance meter that is provided on both sides in a long side direction and / or a short side direction of a cast slab in which solidification has been completed, and measures the distance to the cast slab from a plurality of positions in the short side direction and / or the long side direction; and a calculation device that calculates the bulging amount on a short side and / or a long side of the cast slab by using the distance measured by the two-dimensional laser distance meter. The two-dimensional laser distance meter emits blue laser light having a wavelength of 360-480 nm onto the cast slab.

Description

Bulging amount measuring device, bulging amount measuring method, and slab manufacturing method

[0001] The present invention relates to a bulging amount measuring device for measuring the amount of bulging in a continuously cast slab, a bulging amount measuring method, and a slab manufacturing method using the bulging amount measuring method.

[0002] Bulging occurs when a continuously cast slab expands due to the static pressure of unsolidified molten steel inside. Bulging during continuous casting can cause problems such as breakouts and deteriorate the quality of the cast slab. In continuous casting, support rolls installed in the segments of the continuous casting machine are used to suppress or prevent bulging. However, it is difficult to prevent bulging using support rolls.

[0003] For this reason, it is necessary to monitor bulging in a slab during continuous casting, and if the amount of bulging is about to exceed the limit for the occurrence of internal cracks, etc., to modify the casting conditions to prevent the occurrence of problems such as breakouts. As a technique for monitoring bulging in a slab, Patent Document 1 discloses a bulging amount measuring device that measures the amount of bulging in a slab by bringing a scanning wheel into contact with the slab during continuous casting and measuring the displacement of the scanning wheel with a microdisplacement meter.

[0004] Patent Document 2 discloses a method for measuring bulging during continuous casting using a laser displacement meter to measure the amount of bulging in a slab. According to Patent Document 2, the problem of noise caused by radiant heat can be solved by using a laser displacement meter with a cutoff filter to selectively detect a laser with a wavelength of 620 to 680 nm, and the behavior of bulging in the slab can be directly measured.

[0005] JP-A-3-71961 JP-A-2011-230139

[0006] The technology disclosed in Patent Document 1 has the problem that the pressing force of the scanning wheel becomes excessive, which may actually induce breakout. Since the scanning wheel comes into contact with the high-temperature slab, it is subject to significant thermal deformation and wear, resulting in the need to replace the scanning wheel more frequently. The technology disclosed in Patent Document 2 is a method for measuring the amount of bulging in a slab without contact using a laser displacement meter, but since the measurement is performed in a high-temperature environment where a large amount of steam is generated, it has the problem of being unable to accurately measure the amount of bulging in the slab.

[0007] The present invention was made in consideration of the problems of the prior art, and its object is to provide a bulging amount measuring device and a bulging amount measuring method that can measure the amount of bulging in a cast slab in a non-contact manner even in an environment where a large amount of steam is generated at high temperatures. Another object of the present invention is to provide a slab manufacturing method that can produce slabs with little bulging.

[0008] Means for solving the above problems are as follows. [1] A bulging amount measuring device for measuring the amount of bulging in a slab cast by a continuous casting machine, the bulging amount measuring device comprising: a two-dimensional laser range finder provided on both sides of the slab in the long side direction and / or short side direction after solidification is completed, the two-dimensional laser range finder measuring the distance to the slab at a plurality of positions in the short side direction and / or long side direction; and a calculation device calculating the amount of bulging on the short side and / or long side of the slab using the distance measured by the two-dimensional laser range finder, the two-dimensional laser range finder emitting blue laser light having a wavelength of 360 nm or more and 480 nm or less toward the slab. [2] The bulging amount measuring device according to [1], in which the two-dimensional laser range finder continuously measures the distance to the slab, and the calculation device continuously calculates the amount of bulging. [3] The bulging amount measuring device according to [1] or [2], in which the two-dimensional laser range finder emits laser light of laser class 3B or higher. [4] The bulging amount measuring device according to any one of [1] to [3], further comprising a chiller device, wherein the two-dimensional laser range finder has a light-emitting unit that emits laser light, a light-receiving unit that receives the laser light reflected by the slab, and a cooling unit that cools the light-receiving unit, and the chiller device circulates cooling water through the cooling unit. [5] A bulging amount measuring method for measuring the amount of bulging in a slab continuously cast by a continuous casting machine, comprising: a measuring step of measuring distances to the slab from both sides in the short side direction and / or short side direction of the slab that has completed solidification using a two-dimensional laser range finder, at a plurality of positions in the short side direction and / or long side direction, and a calculating step of calculating the amount of bulging on the short side and / or long side sides of the slab using the distances measured by the two-dimensional laser range finder, wherein in the measuring step, blue laser light having a wavelength of 360 nm or more and 480 nm or less is emitted to the slab. [6] The bulging amount measuring method according to [5], wherein the measuring step continuously measures the distance to the slab, and the calculating step continuously calculates the bulging amount.[7] A method for manufacturing a slab using the bulging amount measurement method described in [5] or [6], comprising: a slab formation step of cooling molten steel poured into a mold to form a slab; a cooling water amount control step of controlling the amount of cooling water in a secondary cooling zone of the continuous casting machine in accordance with the bulging amount calculated in the calculation step; a cooling step of cooling the slab in the secondary cooling zone whose cooling water amount is controlled in the cooling water amount control step; and a cutting step of cutting the slab cooled in the cooling step to a predetermined length.

[0009] By using a two-dimensional laser distance meter with a blue laser having a wavelength of 360 nm or more and 480 nm or less, it is possible to measure the distance to the slab even in an environment where high temperatures and large amounts of steam are generated, and to calculate the amount of bulging in the slab.

[0010] Fig. 1 is a cross-sectional schematic diagram showing an example of the configuration of continuous casting equipment including a bulging amount measuring device according to this embodiment. Fig. 2 is a schematic diagram showing an example of the configuration of a two-dimensional laser range finder. Fig. 3 is a graph showing the relationship between the temperature of a high-temperature object and spectral radiance. Fig. 4 is a schematic diagram showing an example of the configuration of a calculation device. Fig. 5 is a cross-sectional schematic diagram showing the relationship between the shape of the short side of a cast slab and cooling in a secondary cooling zone.

[0011] The present invention will be described in detail below through embodiments of the present invention. First, the following embodiments show preferred examples of the present invention, and the present invention is not limited to these embodiments. FIG. 1 is a cross-sectional schematic diagram showing an example of the configuration of a continuous casting facility 10 including a bulging amount measurement device 40 according to this embodiment. FIG. 2 is a schematic diagram showing an example of the configuration of a two-dimensional laser distance meter 42. The bulging amount measurement device, bulging amount measurement method, and slab manufacturing method according to this embodiment will be described using FIGS. 1 and 2 .

[0012] The continuous casting equipment 10 includes a mold 12, a tundish 14 installed above the mold 12, a plurality of strand support rolls 16 arranged in a row below the mold 12, a bulging amount measuring device 40, and a cooling water control device 70. Although not shown, a ladle for accommodating molten steel 20 is installed above the tundish 14, and the molten steel 20 is poured into the tundish 14 from the bottom of the ladle.

[0013] An immersion nozzle 22 is installed at the bottom of the tundish 14, and molten steel 20 is poured into the mold 12 through the immersion nozzle 22. The molten steel 20 solidifies as it is cooled and heat is removed from the inner surface of the mold 12, forming a solidified shell 24. This results in the formation of a slab 28 having the solidified shell 24 as its outer shell and an unsolidified layer 26 made of molten steel 20 inside. Cooling the molten steel 20 by the mold 12 corresponds to the slab formation step in the slab manufacturing method according to this embodiment.

[0014] In the gaps between adjacent strand support rolls 16 in the casting direction, multiple secondary cooling zones 30, each equipped with spray nozzles (not shown), are installed along the casting direction from directly below the mold 12. The strand 28 is cooled as it is withdrawn by cooling water sprayed from the spray nozzles in the secondary cooling zones 30. While the strand 28 is transported by the strand support rolls 16 and passes through the multiple secondary cooling zones 30, the solidified shell 24 is cooled, and solidification of the unsolidified layer 26 progresses until solidification of the strand 28 is complete.

[0015] The bulging amount measuring device 40 is provided downstream of the solidification completion position where solidification of the slab 28 is completed and upstream of the slab cutter 32, and measures the amount of bulging on the narrow side of the solidified slab 28. The solidification completion position of the slab 28 is the position where the temperature at the center of the slab 28 becomes lower than the liquidus temperature and the central solid fraction of the slab 28 becomes 1.

[0016] FIG. 2(A) is a schematic perspective view showing an example of the arrangement of the two-dimensional laser range finder 42, and FIG. 2(B) is a schematic cross-sectional view of the light receiving unit 44. As shown in FIG. 2(A), the bulging amount measuring device 40 includes two two-dimensional laser range finders 42, a computing device 50, and a tiller device 48. The two-dimensional laser range finders 42 are provided on both sides of the long side direction C of the slab 28. The two-dimensional laser range finder 42 emits a band-shaped laser beam that spreads in the short side direction D of the slab 28 (hereinafter, the short side direction D may be referred to as the thickness direction) and measures the distance from the two-dimensional laser range finder 42 to the short side of the slab 28 at multiple positions in the thickness direction. This measurement process is the measurement step in the bulging amount measuring method and slab manufacturing method according to this embodiment.

[0017] The two-dimensional laser rangefinder 42 has a light-emitting unit 43, a light-receiving unit 44, a frame unit 45, and a cooling unit 46. The frame unit 45 is a housing that houses the light-emitting unit 43, the light-receiving unit 44, and the cooling unit 46. The light-emitting unit 43 emits a band-shaped laser beam that spreads in the thickness direction of the slab 28. Blue laser beams with a wavelength of 360 nm or more and 480 nm or less are used as the laser beams output from the light-emitting unit 43. By using blue laser beams with a wavelength of 360 nm or more and 480 nm or less, it is possible to avoid the influence of electromagnetic radiation from the slab 28, which is a high-temperature object, and to measure the distance to the slab 28 even in a high-temperature environment where a large amount of water vapor is generated.

[0018] 3 is a graph showing the relationship between the temperature of a high-temperature object and the spectral radiance. The horizontal axis of FIG. 3 represents the temperature (°C) of the high-temperature object, and the vertical axis represents the spectral radiance (W·sr －１ ・m －３ The graph shown in FIG. 3 is a profile of the spectral radiance of electromagnetic waves with wavelengths of 405 nm and 660 nm at each temperature, calculated using Planck's radiation law shown in the following equation (1):

[0019] L(λ,T)=2C1 / λ ５ ×(1 / exp(C2 / λT)-1) (1) In the above formula (1), L(λ, T) is the spectral radiance (W·sr －１ ・m －３) and means the radiant flux per unit wavelength width, per unit cubic angle, and per unit radiation area at wavelength λ. λ is the wavelength (m) of the electromagnetic wave radiated from a high-temperature object, and T is the absolute temperature (K) of the high-temperature object, but in the graph they are converted to temperature (°C). C1 and C2 are the first and second constants of radiation shown in the following equations (2) and (3).

[0020] C1 = c ２ ×h=5.9548×10 －１７ (W.m. ２ ) (2) C2 = c × h / k = 0.014388 (m K) (3) In the above equations (2) and (3), c is the speed of light in a vacuum (m s －１ ), h is Planck's constant (J·s), and k is Boltzmann's constant (J·K －１ )

[0021] 3, it can be seen that the electromagnetic waves emitted from a high-temperature object contain a large amount of electromagnetic waves with a wavelength of 660 nm, but contain almost no electromagnetic waves with a wavelength of 405 nm. Therefore, by using a blue laser light with a wavelength of 360 nm or more and 480 nm or less, it is possible to avoid the influence of electromagnetic waves emitted from the slab 28, which is a high-temperature object, and to measure the distance to the slab 28 with high accuracy.

[0022] The laser light output from the light emitting unit 43 is preferably a high-power laser light of laser class 3B or higher. By using a high-power laser light of laser class 3B or higher, scattering of the laser light by water vapor can be suppressed even in an environment where a large amount of water vapor is generated, and the distance to the slab 28 can be measured with even higher accuracy.

[0023] Referring again to Figure 2, the light receiving unit 44 receives the laser light reflected by the slab 28. When the distance from the two-dimensional laser range finder 42 to the slab 28 changes, the laser light reflected by the slab 28 also changes. The two-dimensional laser range finder 42 measures the distance from the two-dimensional laser range finder 42 to the short side of the slab 28 by detecting the change in the laser light received by the light receiving unit 44.

[0024] The cooling unit 46 is provided adjacent to the light receiving unit 44 and cools the light receiving unit 44. The cooling unit 46 is composed of a water pipe through which cooling water supplied from a chiller device 48 passes and a heat sink, and cools the light receiving unit 44 by circulating the cooling water through the water pipe. By providing the cooling unit 46 and the chiller device in this way to cool the light receiving unit 44, it becomes possible to measure the distance to the slab 28 with even higher accuracy even in a high-temperature environment.

[0025] The calculation device 50 calculates the amount of bulging on the narrow side of the slab 28 using the distances at multiple positions in the thickness direction measured by the two-dimensional laser distance meter 42. This bulging amount calculation process is the calculation step in the bulging amount measurement method and slab manufacturing method according to this embodiment.

[0026] The calculation device 50 preferably continuously calculates the amount of bulging of the slab 28. Here, "continuously" means that the amount of bulging of the slab 28 is calculated at a frequency of 200 ms to 5 min. In this embodiment, the frequency of calculation every 5 min or less means that the amount of bulging is calculated at least once for a slab 29 that is cut to a predetermined length. The amount of bulging of the slab 28 is significantly affected by the cooling conditions in the secondary cooling zone 30. For example, even if some of the spray nozzles in the secondary cooling zone 30 become clogged, disrupting the cooling balance and increasing the amount of bulging of the slab 28, by continuously monitoring the amount of bulging of the slab 28, the abnormality can be detected early and a prompt response can be taken.

[0027] Referring again to FIG. 1 , the computing device 50 calculates the amount of bulging in the slab 28 and outputs the calculated amount of bulging to the cooling water control device 70. The cooling water control device 70 is, for example, a general-purpose computer such as a workstation or a personal computer. The cooling water control device 70 is connected to the secondary cooling zone 30 and controls the amount of cooling water sprayed from the spray nozzles of the secondary cooling zone 30 in accordance with the calculated amount of bulging so as to reduce the amount of bulging in the slab 28. This control process is the cooling water amount control step in the slab manufacturing method according to this embodiment.

[0028] In the secondary cooling zone 30, which is controlled so as to reduce the amount of bulging, the solidified shell 24 of the slab 28 is appropriately cooled, solidification of the unsolidified layer 26 proceeds, and solidification of the slab 28 is completed. This cooling treatment is the cooling step in the slab manufacturing method according to this embodiment.

[0029] Downstream in the casting direction, a plurality of transport rolls 18 are installed for continuing to transport the slab 28. A slab cutter 32 for cutting the slab 28 is disposed above the transport rolls 18. After solidification is complete, the slab 28 is cut into slabs 29 of a predetermined length by the slab cutter 32. This cutting process is the cutting step in the slab manufacturing method according to this embodiment. In this way, slabs 29 with a small amount of bulging can be manufactured using the continuous casting equipment 10.

[0030] Fig. 4 is a schematic diagram showing an example of the configuration of the arithmetic unit 50. The arithmetic unit 50 in the bulging amount measuring device 40 according to this embodiment will be described with reference to Fig. 4 .

[0031] The arithmetic device 50 is, for example, a general-purpose computer such as a workstation or a personal computer. The arithmetic device 50 has a control unit 52, an input unit 54, an output unit 56, and a storage unit 58. The control unit 52 is, for example, a CPU, and functions as an acquisition unit 60 and a calculation unit 62 by executing a program stored in the storage unit 58.

[0032] The input unit 54 is, for example, a keyboard, a touch panel integrated with a display, or the like. The output unit 56 is, for example, an LCD or CRT display, or the like. The storage unit 58 is, for example, an updatable flash memory, a built-in hard disk or a hard disk connected via a data communication terminal, an information recording medium such as a memory card, and a read / write device for the same. The storage unit 58 stores programs and data for realizing each function of the arithmetic unit 50. The storage unit 58 stores an arithmetic formula used to calculate the width dimension W of the slab 28 and an arithmetic formula used to calculate the amount of bulging. These arithmetic formulas stored in the storage unit 58 are, for example, created in advance by an operator and stored in the storage unit 58 via the input unit 54.

[0033] Next, the processing executed by the acquisition unit 60 and the calculation unit 62 will be described. The two-dimensional laser rangefinder 42 measures the distance from the two-dimensional laser rangefinder 42 to the short side of the cast slab 28 at a plurality of positions in the thickness direction, and outputs distance information indicating the distance to the acquisition unit 60. When the acquisition unit 60 acquires distance information indicating the distance from the two-dimensional laser rangefinder 42 to the short side of the cast slab 28, it outputs the distance information to the calculation unit 62. The acquisition unit 60 may store the distance information acquired from the two-dimensional laser rangefinder 42 in the storage unit 58 in association with the time of acquisition. In this case, it is preferable to create tracking information that associates the time of acquisition of the distance information with the position of the cast slab 28 in the casting direction, and store the tracking information in the storage unit 58.

[0034] When the calculation unit 62 acquires distance data for a plurality of positions in the thickness direction from the acquisition unit 60, the calculation unit 62 reads out the following equation (4), which is an arithmetic formula for calculating the width dimension W of the slab 28, from the storage unit 58. When distance information is stored in the storage unit 58, the calculation unit 62 reads out the distance information and the following equation (4) from the storage unit 58.

[0035] W=L0-(L1+L2) (4) In the above formula (4), W is the width dimension (mm) of the slab 28, L0 is the distance (mm) between the two two-dimensional laser range finders 42 provided on both sides of the slab 28, and L1 and L2 are measurement values ​​(mm) measured by the two two-dimensional laser range finders 42. L0 is measured in advance when the two two-dimensional laser range finders 42 are installed, and is stored in the storage unit 58 together with the above formula (4).

[0036] The calculation unit 62 calculates the width dimension W of the slab 28 using the above formula (4) and one of the distance information (L1, L2) acquired from the two two-dimensional laser range finders 42. The calculation unit 62 performs this calculation process for a plurality of positions in the thickness direction of the slab 28, and calculates the width dimension W of the slab 28 at the plurality of positions. In this embodiment, the plurality of positions in the thickness direction of the slab 28 may include at least three positions: the upper end, the center, and the lower end in the thickness direction of the slab 28. Once the width dimension W of the slab 28 at these three positions is calculated, the amount of bulging on the narrow side of the slab 28 can be calculated.

[0037] When the amount of bulging on the short sides of the slab 28 is defined as the difference between the width dimension W at the thickness center and the width dimension W at the top end, the amount of bulging (top end) is calculated by the following formula (5). Similarly, when the amount of bulging is defined as the difference between the width dimension W at the thickness center and the width dimension W at the bottom end, the amount of bulging (bottom end) is calculated by the following formula (6). The amount of bulging may also be defined as the difference between the width dimension W at the thickness center and the average value of the width dimensions W at the top end and bottom end. In this case, the amount of bulging (average) is calculated by the following formula (7).

[0038] Bulging amount (upper end) = width dimension W (center) - width dimension W (upper end) (5) Bulging amount (lower end) = width dimension W (center) - width dimension W (lower end) (6) Bulging amount (average) = width dimension W (center) - (width dimension W (upper end) + width dimension W (lower end)) / 2 (7)

[0039] The calculation unit 62 calculates the width dimension W of the slab 28 at the top end, center, and bottom end in the thickness direction of the slab 28, and then calculates the amount of bulging using these width dimensions W and equations (5) to (7) for the amount of bulging, which correspond to the definition of the amount of bulging. In this way, the calculation unit 62 calculates the amount of bulging on the narrow side of the slab 28. The calculation unit 62 may display the calculated amount of bulging on the output unit 56.

[0040] In this way, by using the bulging amount measurement method and bulging amount measurement device 40 according to this embodiment, it becomes possible to measure the amount of bulging of the slab 29 even in an environment where a large amount of steam is generated at high temperatures. Because it becomes possible to measure the amount of bulging of the slab 29 online, it becomes possible to eliminate the effort of inspecting the slab 29 (checking the amount of bulging), which was previously performed after the slab was manufactured.

[0041] The calculation unit 62 in the control unit 52 preferably outputs the calculated amount of bulging to the cooling water control device 70. FIG. 5 is a cross-sectional schematic diagram showing the relationship between the shape of the narrow sides of the cast slab 28 and the cooling in the secondary cooling zone 30. The shape of the narrow sides of the cast slab 28 is significantly affected by the secondary cooling of the cast slab 28. For example, when the secondary cooling of the narrow sides is stronger than that of the long sides, the amount of contraction in the central portion of the cast slab 28 in the thickness direction increases. Therefore, as shown in FIG. 5, the shape of the narrow sides of the cast slab 28 becomes a concave shape in which the width dimension W at the center is shorter than the width dimensions W at the upper and lower ends in the thickness direction. The amount of bulging of a cast slab 28 whose narrow sides are concave becomes a negative value in all of the above equations (5) to (7).

[0042] In contrast, if the secondary cooling on the long side is stronger than on the short side, the amount of shrinkage in the widthwise central portion of the slab 28 increases, and the width dimension W at the upper and lower ends in the thickness direction decreases. As a result, the shape of the short side of the slab 28 becomes a bulging shape in which the width dimension W at the center is longer than the width dimension W at the upper and lower ends in the thickness direction. The amount of bulging of a slab 28 whose short side has a bulging shape becomes a positive value in all of the above equations (5) to (7).

[0043] Therefore, if the amount of bulging in the slab 28 is a negative value, the amount of cooling water on the narrow side of the secondary cooling zone 30 can be reduced and the amount of cooling water on the long side can be increased. On the other hand, if the amount of bulging in the slab 28 is a positive value, the amount of cooling water on the narrow side of the secondary cooling zone 30 can be increased and the amount of cooling water on the long side can be reduced. By adjusting the amount of cooling water sprayed from the spray nozzles in the secondary cooling zone 30 in this way, the amount of bulging in the narrow side direction of the slab 28 can be made close to zero.

[0044] Referring again to Figure 4, the cooling water control device 70 determines whether the amount of bulging acquired from the calculation unit 62 is a positive value, a negative value, or zero. If the acquired amount of bulging is a positive value, the cooling water control device 70 controls the amount of cooling water in the secondary cooling zone 30, and implements at least one of increasing the amount of cooling water on the short side and decreasing the amount of cooling water on the long side. The amounts of cooling water increased and decreased by the cooling water control device 70 are determined in advance.

[0045] On the other hand, if the acquired amount of bulging is a negative value, the cooling water control device 70 controls the amount of cooling water in the secondary cooling zone 30, and implements at least one of decreasing the amount of cooling water on the short side and increasing the amount of cooling water on the long side. Furthermore, if the acquired amount of bulging is 0, the cooling water control device 70 does not change the amount of cooling water in the secondary cooling zone 30.

[0046] In this way, the amount of cooling water in the secondary cooling zone 30 is repeatedly controlled by the cooling water control device 70, and the amount of cooling water sprayed from the spray nozzles in the secondary cooling zone 30 is adjusted so that the amount of bulging in the slab 28 approaches zero. This reduces the amount of bulging in the slab 28, making it possible to manufacture a high-quality slab 29 with a small amount of bulging.

[0047] If the amount of bulging of the slab 29 becomes large, the slab needs to be prepared using a grinder or the like, which increases the cost of manufacturing the slab. In contrast, if it is possible to manufacture slabs with a small amount of bulging, the need to prepare the slab using a grinder or the like will be eliminated, which will prevent the increase in the cost of manufacturing the slab from increasing.

[0048] In the bulging amount measuring device 40 according to the present embodiment, two-dimensional laser distance meters 42 are provided on both sides of the long side direction C of the slab 28 to measure the amount of bulging on the short side sides of the slab 28, but this is not limiting. Two-dimensional laser distance meters 42 may also be provided on both sides of the short side direction D to measure the amount of bulging on the long side sides of the slab 28. It is then preferable to control the amount of cooling water in the secondary cooling zone 30 using the cooling water control device 70 so that the measured amount of bulging on the long side sides of the slab 28 is reduced. Furthermore, two-dimensional laser distance meters 42 may be provided on both sides of the long side direction C and on both sides of the short side direction D to measure the amount of bulging on the short side and long side sides of the slab 28. The amount of bulging on the long side sides of the slab 28 can also be measured using the same procedure as for the short side sides.

[0049] Next, an example will be described in which a two-dimensional laser rangefinder was used to measure the width W of the top, center, and bottom ends of a slab cast in a continuous casting machine. The two-dimensional laser rangefinder shown in Figures 2 and 3 was installed in front of a slab cutter, and a band-shaped laser beam with a wavelength of 405 nm spreading in the thickness direction of the slab was emitted onto the slab on the short side, measuring the distances to the top, center, and bottom ends of the slab on the short side in the thickness direction. The width W of the slab at the top, center, and bottom ends in the thickness direction of the slab was calculated using these measurements and the above formula (4).

[0050] For each slab whose width dimension W was calculated, an operator measured the width dimensions of the slab at the top, center, and bottom ends in the thickness direction using a tape measure, and the width dimension W calculated from the measurements of the two-dimensional laser rangefinder was compared with the measured values. The results are shown in Table 1 below.

[0051]

[0052] As shown in Table 1 above, the width dimension W calculated from the measurements taken by the two-dimensional laser distance meter and the actual measured values ​​showed the same tendency (a concave shape in which the width dimension at the center is shorter than the upper and lower ends). From these results, it was confirmed that by using the bulging amount measuring device 40 according to this embodiment, it is possible to measure the distance to the slab even in an environment where a large amount of steam is generated at high temperatures, and as a result, it is possible to calculate the width dimension W of the slab and the amount of bulging of the slab.

[0053] REFERENCE SIGNS LIST 10 Continuous casting equipment 12 Mold 14 Tundish 16 Strand support roll 18 Conveyor roll 20 Molten steel 22 Submerged nozzle 24 Solidified shell 26 Unsolidified layer 28 Strand 29 Slab 30 Secondary cooling zone 32 Strand cutting machine 40 Bulging amount measuring device 42 Two-dimensional laser distance meter 43 Light emitting unit 44 Light receiving unit 45 Frame unit 46 Cooling unit 48 Chiller unit 50 Calculation unit 52 Control unit 54 Input unit 56 Output unit 58 Storage unit 60 Acquisition unit 62 Calculation unit 70 Cooling water control device

Claims

1. A bulging amount measuring device for measuring the amount of bulging in a slab cast by a continuous casting machine, comprising: a two-dimensional laser distance meter provided on both sides of the long side and / or short side of the slab that has completed solidification, and measuring the distance to the slab at multiple positions in the short side and / or long side directions; and a calculation device that calculates the amount of bulging on the short side and / or long side of the slab using the distance measured by the two-dimensional laser distance meter, wherein the two-dimensional laser distance meter emits blue laser light having a wavelength of 360 nm or more and 480 nm or less onto the slab.

2. A bulging amount measuring device according to claim 1, wherein the two-dimensional laser distance meter continuously measures the distance to the slab, and the calculation device continuously calculates the amount of bulging.

3. A bulging amount measuring device as described in claim 1 or claim 2, wherein the two-dimensional laser distance meter emits laser light of laser class 3B or higher.

4. A bulging amount measuring device as described in any one of claims 1 to 3, further comprising a chiller device, wherein the two-dimensional laser distance meter has an emitting section that emits laser light, a light receiving section that receives the laser light reflected by the cast piece, and a cooling section that cools the light receiving section, and the chiller device circulates cooling water through the cooling section.

5. A bulging amount measurement method for measuring the amount of bulging in a slab continuously cast by a continuous casting machine, comprising: a measurement step for measuring the distance to the slab from both sides of the long side and / or short side directions of the slab that has completed solidification at multiple positions in the short side and / or long side directions using a two-dimensional laser distance meter; and a calculation step for calculating the amount of bulging on the short side and / or long side sides of the slab using the distances measured by the two-dimensional laser distance meter, wherein in the measurement step, blue laser light having a wavelength of 360 nm or more and 480 nm or less is emitted onto the slab.

6. A bulging amount measuring method according to claim 5, wherein in said measuring step, the distance to said slab is continuously measured, and in said calculating step, said bulging amount is continuously calculated.

7. A method for manufacturing a slab using the bulging amount measuring method according to claim 5 or claim 6, comprising: a slab forming step of cooling molten steel poured into a mold to form a slab; a cooling water amount control step of controlling the amount of cooling water in the secondary cooling zone of the continuous casting machine in accordance with the bulging amount calculated in the calculation step; a cooling step of cooling the slab in the secondary cooling zone whose cooling water amount is controlled in the cooling water amount control step; and a cutting step of cutting the slab cooled in the cooling step to a predetermined length.

Images