Solidification position measuring device, solidification position measuring method, quality management method for metal material, casting equipment, manufacturing equipment for metal material, and manufacturing method for metal material

Abstract

The purpose of the present invention is to continuously and automatically measure the solidification position of a cast piece by preventing damage and burnout of an electromagnetic ultrasonic sensor caused by decrease in lift-off due to variation in the thickness of the cast piece, and preventing a decrease in sensitivity of the electromagnetic ultrasonic sensor caused by increase in lift-off. The present invention is provided with: electromagnetic ultrasonic sensors (7, 8) provided on the outside of a cast sheet (1); the sensor lifting unit is used for adjusting the interval between the casting piece (1) and the electromagnetic ultrasonic sensor (7); an interval measuring means for measuring the interval between the casting piece (1) and the electromagnetic ultrasonic sensor (7); a measuring unit that estimates the solidification position in the casting strip (1) from the output of the electromagnetic ultrasonic sensor (7); and a drive control unit that drives and controls the sensor raising and lowering unit and the interval measurement unit, and that controls the position of the electromagnetic ultrasonic sensor (7) by means of the sensor raising and lowering unit on the basis of the interval measured by the interval measurement unit.

Description

Technical Field

[0001] The present invention relates to a solidification position measuring device, a solidification position measuring method, a quality management method for metal materials, casting equipment, metal material manufacturing equipment and a metal material manufacturing method. Background Art

[0002] The solidification position of a cast sheet, especially a steel cast sheet, especially the final solidification position also known as the crater end, is an important indicator in terms of quality and productivity. For example, if the casting speed is increased in order to improve productivity, the final solidification position moves to the downstream side of the casting direction. If the final solidification position exceeds the range of the cast sheet support rollers, the cast sheet expands due to the static pressure of the molten steel, resulting in problems such as deterioration of the internal quality and casting stop caused by huge protrusions. In addition, in the light pressure reduction operation used to reduce the center segregation of the cast sheet, in order to make the final solidification position located in the light pressure reduction zone, it is necessary to control the casting speed and the amount of secondary cooling water, and appropriately perform pressure reduction. In addition, it is known that the final solidification position of the cast sheet is uneven in the width direction and changes over time. It is known that the difference and shape of the final solidification position in the width direction are also important reasons for the quality of the cast sheet.

[0003] In order to meet these requirements, various methods have been proposed to understand the solidification state of the casting and the final solidification position. For example, there is a method of hammering a metal tack on the casting to confirm whether there is a molten layer or a fluidized layer in the center. In addition, there is a method of performing a heat conduction calculation during the solidification process to infer the final solidification position. In addition, there is a method of continuously measuring the surface temperature, correcting the heat conduction calculation, and performing high-precision. In addition, as a method for directly measuring the solidification position online, there is a method of directly measuring the solidification position using an electromagnetic ultrasonic sensor. For example, in Patent Document 1, the following method is disclosed: the final solidification position is detected by a transverse wave ultrasonic wave, the heat conduction calculation is corrected, and the solidification completion position is calculated based on the propagation time of the longitudinal wave ultrasonic wave.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2010-5700

[0005] Patent Document 2: Japanese Patent Application Laid-Open No. 10-122844

[0006] As such, there is a strong demand for understanding the solidification position and shape, and although electromagnetic ultrasonic measurements have been carried out, they have not been implemented to the point of automatic measurement. Although there are some issues that become obstacles to automatic measurement, the lift-off changes caused by slab thickness changes and the difficulty of automatic judgment caused by sensitivity reduction / changes are cited.

[0007] Specifically, in the solidification position measurement method using an electromagnetic ultrasonic sensor, the solidification position shape can be calculated based on the detection / correction of solidification and non-solidification and the longitudinal wave propagation time using transverse ultrasonic waves and longitudinal ultrasonic waves. The electromagnetic ultrasonic sensor is a method that can send and receive ultrasonic waves in a non-contact manner, but the interval between the measurement object and the electromagnetic ultrasonic sensor needs to be set to about 5 mm. In actual operation, the interval (lift-off) varies. For example, the lift-off varies due to changes in the thickness of the casting, local / periodic thickness changes caused by protrusions, etc.

[0008] For example, when solidification occurs above the continuous casting equipment due to sudden deceleration, casting stop, etc., a thick cast sheet may flow over. In this case, the electromagnetic ultrasonic sensor may come into contact with the cast sheet, causing damage or burning. In addition, if the electromagnetic ultrasonic sensor is damaged or falls off due to the contact, the electromagnetic ultrasonic sensor may be caught in the roller and scratch the cast sheet, or the casting roller may be damaged, or the cast sheet may be continuously damaged due to roller damage, resulting in serious failures.

[0009] On the other hand, in the case where the ferrostatic pressure disappears in the later stage of casting, the thickness of the cast piece becomes thinner and the lift-off becomes larger, and the sensitivity of the electromagnetic ultrasonic sensor cannot be ensured.

[0010] That is, if the thickness of the casting becomes thicker and the lift-off becomes smaller, the electromagnetic ultrasonic sensor may sometimes come into contact with the casting, causing the electromagnetic ultrasonic sensor to be damaged. Conversely, if the thickness of the casting becomes thinner and the lift-off becomes too large, the sensitivity of the electromagnetic ultrasonic sensor cannot be ensured, and automatic and continuous solidification position measurement cannot be performed.

[0011] In addition, the sensitivity and waveform deformation of electromagnetic ultrasonic waves are also factors that hinder automation. There are problems such as the low sensitivity of electromagnetic ultrasonic waves, which makes it impossible to ensure the S / N of the received ultrasonic waves, and manual analysis is required, or the waveform of the received and transmitted waves is deformed due to the influence of surface temperature, etc., making automatic measurement difficult. Summary of the invention

[0012] The present invention has been completed in view of the above-mentioned problems, and its purpose is to provide the following solidification position measuring device, solidification position measuring method, metal material quality management method, casting equipment, metal material manufacturing equipment and metal material manufacturing method: by preventing the electromagnetic ultrasonic sensor from being damaged or burned due to the decrease in lift-off due to the change in the thickness of the cast piece, and preventing the reduction in the sensitivity of the electromagnetic ultrasonic sensor due to the increase in lift-off, and greatly improving the S / N of the transmitting and receiving waveforms to perform automatic measurement of the received signal, the solidification position of the cast piece can be measured continuously and automatically.

[0013] (1) In order to solve the above-mentioned problems and achieve the purpose, the solidification position measuring device involved in the present invention is a solidification position measuring device for measuring the solidification position of a casting, comprising: an electromagnetic ultrasonic sensor, which is arranged on the outside of the casting; a sensor lifting unit, which adjusts the interval between the casting and the electromagnetic ultrasonic sensor; an interval measuring unit, which measures the interval between the casting and the electromagnetic ultrasonic sensor; a calculation unit, which infers the solidification position in the casting according to the output of the electromagnetic ultrasonic sensor; and a drive control unit, which drives and controls the sensor lifting unit and the interval measuring unit, and the drive control unit controls the position of the electromagnetic ultrasonic sensor through the sensor lifting unit according to the interval measured by the interval measuring unit.

[0014] (2) The solidification position measuring device according to the above (1) according to the present invention includes a sensor moving unit that moves the electromagnetic ultrasonic sensor outside the cast piece in a plane parallel to the horizontal plane of the cast piece.

[0015] (3) In addition, according to the coagulation position measuring device described in (1) or (2) involved in the present invention, the above-mentioned interval measuring unit sprays water to the measurement object, and makes the ultrasonic wave reciprocate in the water sprayed by the above-mentioned interval measuring unit, and measures the distance from the ultrasonic wave generating unit to the measurement object based on the propagation time of its reflected signal.

[0016] (4) In addition, according to the coagulation position measuring device described in any one of the above (1) to (3) involved in the present invention, the transmission and reception signal of the above electromagnetic ultrasonic sensor is a chirp signal whose frequency changes with time, and the above operation unit performs operation processing including phase operation on the above chirp signal.

[0017] (5) In addition, according to the coagulation position measuring device described in the above (4) involved in the present invention, after the above-mentioned operation processing, the above-mentioned operation unit performs waveform detection on the transmitted wave and / or the reflected wave using a time gate including the above-mentioned transmitted wave and / or the above-mentioned reflected wave, and uses the time difference of the above-mentioned transmitted wave and / or the above-mentioned reflected wave detected by the waveform to calculate the propagation time.

[0018] (6) In the coagulation position measuring device according to any one of (1) to (5) of the present invention, the electromagnetic ultrasonic sensor uses a Halbach array magnet.

[0019] (7) In order to solve the above-mentioned problems and achieve the purpose, the solidification position measurement method involved in the present invention measures the solidification position of the casting, which includes: an interval measurement step, measuring the interval between the above-mentioned casting and the electromagnetic ultrasonic sensor; an interval judgment step, judging whether the measured interval is within a specified range; an interval adjustment step, if the above-mentioned interval is not within the specified range, adjusting the above-mentioned interval according to the measured interval; and a calculation step, if the above-mentioned interval is within the specified range, using the above-mentioned electromagnetic ultrasonic sensor to infer the solidification position in the above-mentioned casting.

[0020] (8) In addition, the solidification position measuring method described in (7) above according to the present invention includes a moving step of moving the electromagnetic ultrasonic sensor within a plane parallel to the horizontal plane of the cast piece.

[0021] (9) In addition, according to the coagulation position measurement method described in (7) or (8) involved in the present invention, the electromagnetic ultrasonic sensor uses a Halbach array magnet, the receiving and transmitting signal of the electromagnetic ultrasonic sensor is a chirp signal whose frequency changes with time, and the operation step performs operation processing including phase operation of the chirp signal.

[0022] (10) In order to solve the above-mentioned problems and achieve the purpose, the quality management method of metal materials involved in the present invention controls the manufacturing conditions of the next process according to the solidification position of the casting piece measured using the solidification position measurement method described in any one of the above (7) to (9).

[0023] (11) In order to solve the above-mentioned problems and achieve the purpose, the manufacturing equipment of the metal material involved in the present invention has a solidification position measuring device recorded in any one of the above (1) to (6), and manufactures the metal material while measuring the solidification position of the above-mentioned casting by the above-mentioned solidification position measuring device.

[0024] (12) In order to solve the above-mentioned problems and achieve the purpose, the casting equipment involved in the present invention is equipped with a solidification position measuring device described in any one of the above (1) to (6), and manufactures the cast piece while measuring the solidification position of the above-mentioned cast piece by the above-mentioned solidification position measuring device.

[0025] (13) In order to solve the above-mentioned problems and achieve the purpose, the manufacturing equipment of the metal material involved in the present invention includes the casting equipment described in the above (12), and manufactures the metal material from the cast piece manufactured by the above-mentioned casting equipment.

[0026] (14) In order to solve the above-mentioned problems and achieve the purpose, the manufacturing method of the metal material involved in the present invention manufactures the metal material while using the solidification position measurement method described in any one of the above (7) to (9) to measure the solidification position of the casting.

[0027] According to the solidification position measuring device, solidification position measuring method, metal material quality management method, casting equipment, metal material manufacturing equipment and metal material manufacturing method involved in the present invention, the damage and burning of the electromagnetic ultrasonic sensor caused by the reduction of lift-off due to the change of the thickness of the cast piece are prevented, and the reduction in sensitivity of the electromagnetic ultrasonic sensor caused by the increase of lift-off is prevented, and the S / N of the transmitting and receiving waveforms is greatly improved to automatically measure the received signal, thereby enabling continuous and automatic measurement of the solidification position of the cast piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a diagram showing a schematic configuration of a continuous casting facility including a solidification position measuring device according to an embodiment of the present invention.

[0029] Figure 2 It is a schematic diagram showing the structure of the solidification position measuring device as this embodiment.

[0030] Figure 3 This is a flowchart showing a coagulation position measurement control process by the coagulation position measurement device.

[0031] Figure 4 This is a flowchart showing a coagulation position measurement control process procedure in a fixed position measurement mode by the coagulation position measurement device.

[0032] Figure 5 This is a diagram showing an example of a modified configuration of a boom, an electromagnetic ultrasonic sensor, and a water column range finder.

[0033] Figure 6 This is a diagram showing an example of a modified configuration of a boom, an electromagnetic ultrasonic sensor, and a water column range finder.

[0034] Figure 7 It is a cross-sectional view showing the structure of the water column rangefinder.

[0035] Figure 8 This is an explanatory diagram for explaining the generation of longitudinal waves by an electromagnetic ultrasonic sensor.

[0036] Fig. 9 This is an explanatory diagram for explaining the generation of transverse waves by an electromagnetic ultrasonic sensor.

[0037] Fig.10 This is a diagram showing an example of the arrangement of a magnet, a longitudinal wave coil, and a transverse wave coil in an electromagnetic ultrasonic sensor.

[0038] Fig.11 It means in Fig.10 FIG. 1 is a diagram showing a modified example in which an auxiliary magnet is added to the magnet of the electromagnetic ultrasonic sensor shown.

[0039] Fig.12 The diagram shows the waveform of a received signal when the magnet of the electromagnetic ultrasonic sensor is designed as a Halbach array and when a calculation process (chirped pulse compression process) is performed or not.

[0040] Fig.13 It means use Fig.11 The magnet of the Halbach array shown here performs the received waveform of the chirped pulse compression and uses the chirped pulse compression signal and Fig.10 The figure shows the reception waveform in the case of a normal magnet.

[0041] Fig.14 This is an explanatory diagram for explaining shear wave measurement.

[0042] Fig.15 This is an explanatory diagram for explaining longitudinal wave measurement.

[0043] Fig.16 This is a diagram showing an example of automatic measurement of the full width of a cast slab.

[0044] Fig.17 This is a diagram showing an example of the pass / fail determination of a cast piece. DETAILED DESCRIPTION

[0045] The solidification position measuring device, solidification position measuring method, metal material quality management method, casting equipment, metal material manufacturing equipment and metal material manufacturing method according to the embodiments of the present invention are described with reference to the accompanying drawings. In addition, the present invention is not limited to the following embodiments, and the constituent elements in the following embodiments also include elements that can be easily replaced by those skilled in the art or substantially the same elements. In addition, the cast sheet refers to the material obtained after casting the metal material.

[0046] <Overview of continuous casting equipment>

[0047] Figure 1 1 is a diagram showing a schematic structure of a continuous casting device having a solidification position measuring device as an embodiment of the present invention. In addition, for the sake of convenience, as an example, "metal material" is "steel material", "casting equipment" is "continuous casting equipment", and "casting piece" is a steel casting piece cast by the continuous casting equipment. Figure 1 As shown, in the continuous casting equipment, the molten steel injected into the mold 101 is cooled by the mold 101, and a solidified portion 2 is formed at the portion in contact with the mold 101, thereby generating a cast piece 1 having a solidified portion 2 around and an unsolidified liquid phase portion 3 inside. Figure 1 The directions are defined in the following. X direction: the width direction of the casting, Y direction: the pulling direction of the casting, Z direction: the thickness direction of the casting and the lifting direction. The same applies to the following.

[0048] The cast sheet 1 is pulled downwardly from the mold 101 while being supported by a plurality of pairs of cast sheet support rollers 102 arranged opposite to each other below the mold 101. A secondary cooling zone is provided in the gap between the adjacent cast sheet support rollers 102 in the casting direction. The secondary cooling zone is composed of a mist nozzle, a water nozzle (not shown), etc., which blows cooling water toward the surface of the cast sheet 1. The cast sheet 1 is cooled by the secondary cooling zone while being pulled toward the downstream side in the casting direction, and is completely solidified to the center. The position completely solidified to the center is the final solidification position referred to as the end of the pit. Hereinafter, the final solidification position is sometimes referred to as the pit end position 4 or simply the solidification position 4. The solidified cast sheet 1 is cut into a specified length by a cast sheet cutter 104 provided on the downstream side of the cast sheet support rollers 102, and is carried out as a cast sheet 1A by a conveying roller 103.

[0049] Here, a solidification position measuring device is configured in the continuous casting equipment. The solidification position measuring device includes electromagnetic ultrasonic sensors 7 and 8 arranged opposite to each other with the cast sheet 1 sandwiched therebetween, and a water column rangefinder 6 as a distance measuring section for measuring the distance (lift-off) between the cast sheet and the electromagnetic ultrasonic sensor 7. The electromagnetic ultrasonic sensor 8 is a sensor for transmitting electromagnetic ultrasonic waves, and the electromagnetic ultrasonic sensor 7 is a sensor for receiving electromagnetic ultrasonic waves. The electromagnetic ultrasonic sensors 7 and 8 transmit transverse electromagnetic ultrasonic waves and longitudinal electromagnetic ultrasonic waves relative to the cast sheet 1, and receive them via the cast sheet 1. The transverse electromagnetic ultrasonic wave does not pass through the liquid phase 3, so it is possible to measure whether the cast sheet 1 is solidified or unsolidified. That is, it is possible to determine whether the measurement position is on the upstream side or downstream side of the solidification position 4. In addition, the longitudinal electromagnetic ultrasonic wave is used to calculate and infer the solidification position 4 based on the propagation time propagating in the cast sheet 1. The electromagnetic ultrasonic sensor 7 and the water column rangefinder 6 are installed below (in the -Z direction) a boom 11 disposed on the +Z direction side of the casting 1, and the electromagnetic ultrasonic sensor 8 is installed above (in the +Z direction) a boom 12 disposed on the -Z direction side of the casting 1, and can move together with the booms 11 and 12, respectively. Each boom 11 and 12 can be raised and lowered in the ±Z direction and moved in the ±X direction. The interval between the electromagnetic ultrasonic sensor 7 and the casting 1, that is, the lift-off value, is adjusted based on the lift-off value between the water column rangefinder 6 and the casting 1 measured by the water column rangefinder 6. In addition, the continuous casting equipment here is basically a mechanism that uses the lower side as a reference plane and controls the casting thickness by controlling the position of the upper roller. The lift-off value of the electromagnetic ultrasonic sensor 8 on the lower side is fixed, and the lift-off value of the electromagnetic ultrasonic sensor 7 on the upper side is adjusted and controlled.

[0050] <Structure of solidification position measuring device>

[0051] Figure 2 Schematic diagram showing the structure of the solidification position measuring device 10 according to the present embodiment. Figure 2As shown, the solidification position measuring device 10 is configured to clamp the cast sheet 1 in the Z direction (height direction) by a hanger 11 equipped with a water column rangefinder 6 and an electromagnetic ultrasonic sensor 7 as an interval measuring unit, and a hanger 12 equipped with an electromagnetic ultrasonic sensor 8. The hanger 11 is raised and lowered in the height direction by a motor 23 as a sensor lifting unit, and moves (traversely) in the X direction (width direction) by a motor 21 as a sensor moving unit. In addition, the hanger 12 moves horizontally by a motor 22 as a sensor moving unit. In addition, the sensor moving unit moves the electromagnetic ultrasonic sensors 7 and 8 to a specified measurement position in a plane parallel to the horizontal plane of the cast sheet.

[0052] The drive control unit 13 obtains the lift-off value measured by the water column rangefinder 6, and drives and controls the motors 21 to 23 based on the lift-off value and the operating information such as the casting thickness and casting width sent from the host device 110, and performs travel control and lifting control of the electromagnetic ultrasonic sensors 7 and 8 with the help of the suspension rods 11 and 12.

[0053] The measuring operation unit 14 as an operation unit gives a transmission signal to the electromagnetic ultrasonic sensor 8 via the sending unit 15 to make it send electromagnetic ultrasonic waves toward the casting 1, so that the casting 1 senses the ultrasonic waves, applies appropriate signal processing according to the ultrasonic receiving signal received by the electromagnetic ultrasonic sensor 7, and performs inference operations on the solidification position 4 and the solidification shape, and sends the operation results to the host device 110.

[0054] That is, the water column rangefinder 6 of the solidification position measuring device 10 constantly measures the lift-off value relative to the cast piece 1, and automatically controls the lifting and lowering of the electromagnetic ultrasonic sensors 7 and 8 and the horizontal movement control according to the measurement result, so as to automate the solidification position measurement. In addition, the horizontal movement can be realized based on the automatic movement through the motors 21 and 22, and can stop at any or pre-specified position and perform the measurement. The motor control can use a common pulse motor or servo motor, and its position accuracy is preferably about 1 mm or less.

[0055] The height adjustment (lift-off adjustment) of the electromagnetic ultrasonic sensor 7 also considers a structure in which the height is adjusted by only controlling the lifting and lowering of the electromagnetic ultrasonic sensor 7. However, the driving unit for height adjustment enters the continuous casting equipment, and is therefore subject to dimensional constraints (usually the roller spacing is about 30 to 70 mm), steam, heat and other harsh environments. Therefore, it is preferred that the driving unit is arranged outside the continuous casting equipment so that the entire boom can be lifted and lowered. The lifting and lowering accuracy in the height direction preferably has an accuracy of about 0.1 mm. Control can be performed by using a conventional pulse motor or servo motor. The lifting and lowering and positioning speeds can be exemplified as about 0.1 mm / s to 1 mm / s. As described above, in the case of height adjustment according to changes in the thickness of the cast sheet, it is only necessary to adjust the droop of the booms 11 and 12 caused by the horizontal movement (the front end is lowered due to elastic deformation caused by the deadweight of the boom) and the speed required for height adjustment caused by other reasons. If the speed is too slow, there is a possibility of contact without enough time for lifting and lowering. On the other hand, in the case of excessively high speed, the position control performance deteriorates, or the motor part is too large, resulting in high costs. Changes during casting are usually made with a delay of several minutes and a time scale. Therefore, it is preferred to control the position adjustment within 10 seconds to 1 minute, including changes in height / thickness of the cast piece caused by the horizontal movement. In addition, the lifting range preferably covers the nominal cast piece thickness of the casting, and can be controlled within the thickness of -20mm to +50mm.

[0056] The suspension rods 11 and 12 need to ensure sufficient straightness and rigidity when moving horizontally. Specifically, the cast slab 1 usually has a width of about 1m to 2.5m, so it is necessary to be able to carry out the measurement over the full width of the measurement object. In the case of full-width measurement, it is necessary to be able to move to the innermost part of the cast slab 1. In addition, under the assumption of left-right symmetry, a design that can move to the center as a half-width measurement is also considered, and the design can be made according to the required accuracy, segregation degree, or customer requirements.

[0057] The interval between casting segments is usually about 30 mm to 50 mm, and the segments need to be inserted into the gap. Therefore, the thickness of the suspension rods 11 and 12 in the casting direction is very thin. On the other hand, in order to cope with a 2-meter cast piece, if the retreat amount is included, it is sometimes necessary to ensure a stroke of about 3 to 4 meters in the X direction. In order to prevent deformation caused by the weight of the head, the weight of the head, or interference with the casting segment, friction, etc., sufficient rigidity is required, so rigidity needs to be ensured in the height direction.

[0058] The suspension rods 11 and 12 receive radiant heat from the cast sheet 1. At this time, the heat enters differently between the surface facing the cast sheet 1 and the opposite side. A temperature difference occurs between the surface facing the cast sheet 1 (the lower surface of the suspension rod in the case of the suspension rod 11) and the opposite side, causing the suspension rod to warp. This acts in the direction where the lift-off increases, differently from the thickness variation of the cast sheet 1, because the electromagnetic ultrasonic sensor becomes the side away from the measurement object. If the lift-off increases, the sensitivity decreases according to the lift-off characteristics of the electromagnetic ultrasonic sensor.

[0059] In addition, considering the thermal effects and maintainability when not measuring, it is desirable to retreat to a position sufficiently far away from the cast piece 1, more specifically, preferably outside the casting section or casting cavity. If it is possible to retreat outside the casting cavity, it is possible to wait without being affected by heat, steam, etc., and maintenance can be performed at any time.

[0060] In addition, as mentioned above, the roller interval is about 30 mm to 70 mm, so the sensor, the suspension rod, and the interval measuring unit need to have a size that can be inserted into the gap. However, if maintenance is also considered, it is hoped that it can be led out of the continuous casting equipment. In addition, in the case of a cantilever, if the front end drops due to weight during insertion, the electromagnetic ultrasonic sensor on the upper side contacts the cast sheet 1, or the lift in the electromagnetic ultrasonic sensor on the lower side becomes too large to maintain sensitivity, so it is preferred that the suspension rods 11 and 12 have sufficient rigidity. On the other hand, in the case of double support, it becomes advantageous for these problems. On the contrary, if the layout of the continuous casting equipment does not have room, it will be difficult to achieve. In any case, it can be appropriately determined by considering the condition of the equipment and the rigidity of the suspension rod.

[0061] <Measurement control processing>

[0062] Figure 3 FIG. 2 is a flowchart showing a measurement control process of the coagulation position by the coagulation position measurement device 10. Figure 3 As shown, first, if casting starts, the start of casting is transmitted from the upper device 110 to the drive control unit 13 and the measurement operation unit 14. If the start of casting is detected, measurement preparation is performed (step S11). During the measurement preparation, the measurement conditions (such as the measurement spacing in the width direction) are determined according to the thickness of the cast sheet, the casting width, the type of steel, etc. In addition, at this time, various cooling water flow checks and equipment integrity checks can also be performed. Then, the height of the suspension rod during insertion is determined based on the thickness of the cast sheet and adjusted. The setting of the casting thickness or the casting section opening can also be used as a reference. Specifically, the cast sheet thickness + 7mm can be exemplified, where the height is roughly adjusted to the extent that it does not contact the cast sheet 1 during the first insertion. In addition, when it is desired to adjust to the set height but cannot be adjusted, it is preferred to set a control sequence such as abnormal report and measurement termination as a lifting abnormality.

[0063] Then, the booms 11 and 12 are moved horizontally to the measurement position (step S12). With the completion of the first height adjustment step based on step S11, it is judged that the target cast piece has reached the specified position based on the operating performance indicators such as the drawing length, and the horizontal movement is performed. In the early stage of continuous casting, there is a possibility of damage to the sensor due to the movement of the dummy rod, the deviation of the initial cast piece thickness, etc. Therefore, the completion of the passage of the dummy rod or the passage of the front end of the cast piece can also be used as a trigger for the start of horizontal movement. The first measurement standby position is the position where only the interval measurement unit at the front end of the boom reaches the end of the cast piece. The casting width is transmitted in advance as the operating performance information, and the position of the interval measurement unit is known, so the position of the moving destination can be automatically calculated.

[0064] Then, it is determined whether the movement of the suspension rods 11 and 12 to the measurement standby position is completed (step S13). If the movement is not completed (step S13: No), the process proceeds to step S12. If the movement is completed (step S13: Yes), the indication value (detection value) of the water column distance meter 6 is obtained (step S14). Furthermore, based on the lift-off value L2 measured by the water column distance meter 6, it is determined whether the lift-off value L1 between the casting 1 and the electromagnetic ultrasonic sensor 7 is within a prescribed range (step S15). When the lift-off value L1 is not within the prescribed range (step S15: No), the lift-off value is adjusted (step S16), and the process proceeds to step S14. The adjustment of the lift-off value L1 is performed by controlling the lifting and lowering of the suspension rod 11.

[0065] The lift-off value may sometimes produce an error relative to the casting thickness based on the nominal value / set value due to the influence of temperature, casting speed, etc., or the displacement of the casting section, thermal expansion of the suspension rod, etc., so the height of the electromagnetic ultrasonic sensor is adjusted according to the measured interval. The interval between the casting sheet and the electromagnetic ultrasonic sensor can be 5mm±0.5mm, for example. If the interval is large, the sensitivity is reduced and it cannot be measured. If the interval is too small, the risk of contact / burning / breakage due to the change of the casting sheet thickness, etc. increases.

[0066] When the lift-off value is within the specified range (step S15: yes), the electromagnetic ultrasonic sensors 7 and 8 perform longitudinal wave measurement and transverse wave measurement (step S17). That is, a pulse current is applied to the electromagnetic ultrasonic sensor 8 to induce ultrasonic waves on the surface of the casting. In addition, the electromagnetic ultrasonic sensor 7 receives the ultrasonic wave, performs appropriate signal processing, and performs a solidification position estimation operation to calculate the solidification state and / or solidification position (step S18). The calculation result is sent to the host device 110. In addition, depending on the operating conditions, sometimes only the longitudinal wave measurement or only the transverse wave measurement is performed.

[0067] Then, it is determined whether there is a movement instruction (step S19). If there is a movement instruction (step S19: yes), the process is transferred to step S12 and moved to the next measurement point. On the other hand, if there is no movement instruction (step S19: no), the process is terminated and the electromagnetic ultrasonic sensors 7, 8, etc. are moved outside the continuous casting equipment.

[0068] The movement instruction is pre-set, for example, in a manner of measuring at 100 mm intervals in the width direction. By moving the electromagnetic ultrasonic sensors 7 and 8, the measurement points are discretely formed into sawtooth in the width direction relative to the cast piece 1, and the shape of one solidification position is obtained as the distribution in the width direction by full width measurement. The order of movement can also be appropriately determined by measuring from the ends of the cast piece in sequence or from the center.

[0069] In addition, the determination of the end of the measurement process based on whether there is a movement indication can also be the end of casting. Information on the end of casting or the top of the cast (upper end / tail end) exceeding the specified position can also be used as a trigger for the end of the measurement. In particular, when unsolidified molten steel is exposed at the top of the cast, the static pressure of the molten steel disappears, or the thickness of the cast changes due to solidification shrinkage, it is desirable to retreat. When retreating the boom, the height at this time can be maintained unchanged, but for example, by raising it (in the direction of increasing distance from the cast) by about 2mm to 3mm to retreat it, the risk of deviation in the width direction of the cast and tilting of the boom can be eliminated to retreat it. The retreat is completed outside the continuous casting equipment and the measurement is ended.

[0070] In addition, it is also possible to continuously measure at a specific position (fixed position measurement). In this case, there is no movement instruction for moving the measurement point. Figure 4 In the fixed position measurement, it is also considered to focus on the central position of the cast piece, or the position that particularly affects the quality of the cast piece based on experience / past performance, and it is appropriately determined according to the properties and requirements of the target cast piece.

[0071] like Figure 4 As shown, in the fixed position measurement, the same processing as that of steps S11 to S18 is performed (steps S21 to S28). In step S28, after the solidification position estimation operation is performed, it is determined whether there is a next measurement instruction (step S29). In the fixed position measurement, it is not necessary to move the boom, so when there is a next measurement instruction (step S29: Yes), it does not transfer to step S22, but transfers to step S24 to obtain the value of the water column rangefinder and perform measurement at the same position. On the other hand, due to the end of casting, etc., when there is no next measurement instruction (step S29: No), this processing is performed.

[0072] <Modification of the arrangement of the boom, electromagnetic ultrasonic sensor, and water column rangefinder>

[0073] Figure 5 and Figure 6 This is a diagram showing an example of a modified configuration of a boom, an electromagnetic ultrasonic sensor, and a water column range finder. Figure 2 In the embodiment, the electromagnetic ultrasonic sensors 7 and 8 are arranged to sandwich the casting 1 to be measured. Figure 5 As shown, a reflection measurement system based on a single electromagnetic ultrasonic sensor 7a may be used. In the case of the reflection measurement system, the suspension rod 12 and the motor 22 are not provided. In addition, the electromagnetic ultrasonic sensor 7a may be provided on the lower side of the cast piece 1.

[0074] In addition, if Figure 6 As shown in FIG. 1 , water column rangefinders 6a and 6b may be provided on both the booms 11 and 12, and a motor 24 as a sensor lifting unit may be provided on the boom 12. Compared with the reflection measurement system, the transmission measurement system has the advantage of being easy to obtain signal strength because the ultrasonic wave propagates over a short distance. Figure 2 As shown, continuous casting equipment is basically a mechanism that uses the lower side as a reference plane and controls the casting thickness by controlling the position of the upper roller. In this case, it is better to use a structure that sets the sensor height on the lower side to a fixed level and controls the height on the upper side.

[0075] <Water column distance meter>

[0076] In the case of an optical type such as a laser rangefinder as a distance measurement unit, a red laser source commonly used in commercial products is used for the red-hot cast piece to be measured. However, red laser sources are often not used properly. In addition, it is also difficult to use near the cast piece because water droplets, mist, oil mist, etc. accompanying the cooling of the cast piece block the laser used for measurement, or the optical window is contaminated.

[0077] In addition, eddy current distance meters are characterized by high accuracy and being relatively compact. On the other hand, the distance to the object to be measured is limited to a few millimeters or less, so the risk of loss and failure caused by thermal effects is likely to increase. Moreover, based on the principle of measuring the distance to the conductor, the outer packaging of the sensor is mostly plastic or ceramic. Here, plastics may have problems in terms of heat resistance and ceramics may have problems in terms of mechanical strength based on heat loads, etc.

[0078] In contrast, the water column rangefinder is most suitable as the interval measuring unit of the solidification position measuring device involved in the present invention. There are several reasons. First, the structure of transmitting ultrasonic waves through a water column is not easily affected by water vapor, water mist, etc. Moreover, due to the difference in acoustic impedance between the surface of the casting and water, reflection occurs, so the measurement can be performed regardless of the surface temperature of the casting. Even if the water in contact with the surface of the casting produces bubbles due to boiling, it is immediately washed away by the water pressure of the water column and becomes a reflection from the surface of the casting. In addition, the ultrasonic probe is often water-cooled, so it is not easy to cause loss and failure caused by thermal effects. The length of the water column can be about 50 mm as described later, and the thermal effect on the nozzle is also small. In addition, the water column rangefinder itself is small and can be used even in narrow places such as the gap between segment rolls. The overall thickness of the water column rangefinder is about 20 mm to 30 mm, which can be fully accommodated in the gap between the rollers.

[0079] Figure 7 2 is a cross-sectional view showing the structure of the water column distance meter 6. The water column distance meter 6 typically adopts Figure 7 The water column range finder 6 includes an ultrasonic probe 61 , a water supply port 62 , a water tank 63 for rectifying, a nozzle 64 , and a step 65 .

[0080] The ultrasonic probe 61 is preferably a local water immersion probe. In order to be installed in the water column, a probe that can be immersed in water can be selected. The water used in the water column also serves as cooling water for the probe. The frequency and probe size can be appropriately designed, and a probe with a center frequency of 5 MHz can be exemplified. The diameter of the probe can be exemplified as about 8 mm to 12 mm.

[0081] An appropriate amount of water is supplied to the water supply port 62 to form a water column between the object and the nozzle 64. The amount of water supplied depends on the nozzle diameter, the water distance, and especially the distance from the tip of the nozzle 64 to the cast piece 1, so it can be designed appropriately. However, as an example, when the nozzle is 8 mm and the distance between the tip of the nozzle and the cast piece 1 is 50 mm, it is preferably about 5 to 15 liters / minute.

[0082] Regarding the quality of the supplied water, it is desirable that it does not contain bubbles, dirt, etc. Bubbles in the water column become a reflection source of the ultrasonic wave, which causes the S / N ratio (Signal to Noise Ratio) to decrease or the reflection signal to be completely inaccessible. However, if there are only a small number of bubbles, there are cases where they can be removed by synchronous addition, averaging, etc.

[0083] In addition, a rectification / retention mechanism can be added to the water column nozzle to take measures against bubbles. By designing the water column nozzle so that bubbles do not accumulate near the sensor surface, the influence of bubbles that may be present can be reduced.

[0084] The nozzle diameter is preferably about 6mm to 15mm, more preferably 8 to 10mm. The flow rate is preferably about 5 to 15 liters / minute, and the flow rate and nozzle distance are designed in a laminar flow manner. The nozzle distance (water column distance) can be appropriately designed according to the nozzle diameter and the water column flow rate, and the range of 5mm to 100mm can be exemplified. Typically, about 30mm to 70mm is preferred. When it is below about 5mm, the issue of contact with the casting 1 and the thermal effect on the ultrasonic detector 61 arise. If the distance of the water column becomes larger, the flow rate needs to be increased in order to maintain a stable water column, but if the flow rate increases, it will become turbulent and the S / N ratio of the reflected signal will decrease. In addition, the need to increase the flow rate or increase the water pressure will become the cause of turbulence.

[0085] In addition, the nozzle diameter can be selected to be the same as the probe diameter. If the diameter is small, the intensity of the ultrasonic wave that can be transmitted becomes smaller, and the sensitivity / stability is reduced. By setting the nozzle diameter to the same as the probe diameter, a part of the ultrasonic signal that is slightly extended and propagated can be reflected by the step 65 as a reference echo. If the nozzle diameter becomes too large, the step echo becomes too small, or unnecessary cooling is applied to the cast piece 1 due to the need to increase the flow rate, which is undesirable.

[0086] Furthermore, by rectifying the flow, adjusting the flow rate, and degassing the bubbles in the water tank 63, the bubbles are not retained on the front surface of the ultrasonic probe 61, etc., which can prevent the scattering of ultrasonic waves, improve the S / N ratio, and stabilize the measurement. Figure 7 As shown, it can be on both sides of the ultrasonic probe 61 or on one side. It only needs to be designed appropriately according to the size that can be set.

[0087] The step 65 is provided to partially reflect the ultrasonic wave through the step 65 and to correct the temperature dependence of the sound velocity by the reflected signal. The boundary between the space for accommodating the ultrasonic probe 61 and the nozzle 64 may be the step 65, or the step may be formed by reducing the diameter compared to the nozzle 64. In addition, a protrusion or a rod-shaped component may be provided for partial reflection.

[0088] When the ultrasonic wave reflected by the step 65 returns to the ultrasonic probe 61, an echo (step echo) is generated. The step echo is used to perform water temperature correction. The ultrasonic sound velocity changes according to the water temperature, so the distance Ld cannot be calculated only by the echo from the casting 1. In contrast, by using the step echo, it can be obtained with high accuracy.

[0089] Here, the distance to the casting 1 is Ld. If the measured propagation time is Td, the speed of sound is V(C), and the water temperature is C, the desired distance Ld can be expressed as Ld=Td / V(C). The speed of sound is dependent on the water temperature, and thus an error due to V(C) (temperature dependence) occurs. In order to prevent this error, it is necessary to keep a speed of sound table in advance, measure the water temperature and refer to the table, and calculate the water distance based on the speed of sound corresponding to the temperature, which makes the system / calculation complicated.

[0090] In contrast, in the distance measurement using the step 65 of the present embodiment, the distance from the ultrasonic probe 61 to the step 65 is set to L, and the distance from the ultrasonic probe 61 to the cast piece 1 is set to Ld. In addition, the propagation time of the echo from the step 65 is set to T, and the propagation time of the echo from the cast piece 1 is set to Td. The distance from the ultrasonic probe 61 to the step 65 is a known value determined by the machining accuracy and is actually a constant. The distance Ld can be obtained by the following formula using the propagation time T of the step echo and the distance L to the step 65.

[0091] Ld=L / T×Td

[0092] According to this formula, the distance Ld can be expressed without including the temperature influence term, and the distance measurement can be performed independently of the water temperature. The propagation time of the step echo and the propagation time from the casting 1 are obtained with the same degree of accuracy, and the influence of the temperature dependence of the speed of sound is eliminated.

[0093] By setting ultrasonic detection gates for both the step echo and the echo from the cast piece 1 and acquiring them simultaneously, it is possible to perform real-time water temperature correction. Therefore, it is preferable to process the acquired waveforms using a personal computer or the like and perform distance measurement.

[0094] In addition, in the acoustic wave measuring device and the temperature correction method thereof described in Patent Document 2, the propagation time of the echo from the step is obtained in advance for temperature correction, and then the propagation time of the echo from the measurement object is measured to perform temperature correction. In contrast, in the present embodiment, the temperature correction is performed by simultaneously acquiring the step echo and the echo from the casting 1 by utilizing the fact that partial reflection from the step is often generated. By acquiring them simultaneously, it is possible to frequently perform measurement with temperature correction applied with high accuracy when the water temperature changes, etc. Since the propagation time and the time of the step echo are measured simultaneously, the result is higher in accuracy than the pre-measurement method.

[0095] Furthermore, by using the distance measurement method using the water column distance meter 6 of the present embodiment, it was confirmed that the absolute value error was within 0.1 mm in the range of 20 mm to 50 mm from the nozzle 64 to the cast piece 1 .

[0096] <Positional relationship between water column distance meter and electromagnetic ultrasonic sensor>

[0097] A water column rangefinder 6 is arranged in front of the electromagnetic ultrasonic sensor 7, and the distance between the casting piece 1 and the electromagnetic ultrasonic sensor is often measured, so that Figure 7 Configured as shown.

[0098] like Figure 7 As shown, the electromagnetic ultrasonic sensor 7 is mechanically combined with the water column range finder 6, so it is sufficient to know the relative position in advance. Typically, the difference between the front end surface of the electromagnetic ultrasonic sensor 7 and the front end position of the nozzle 64 is about 30 mm to 50 mm. It can be appropriately set according to the stability of the water column 66 and the constraints of the installation structure.

[0099] <Electromagnetic ultrasonic sensor>

[0100] Electromagnetic ultrasonic waves are ultrasonic vibrations induced in a conductor by the interaction between the eddy current induced in the conductor by the pulse signal of a large current that energizes the coil and the static magnetic field, which generates the Lorentz force. The eddy current generated by electromagnetic induction flows along the surface of the conductor. The Lorentz force is generated according to Fleming's left-hand law, so Figure 8 As shown, if a magnetic field parallel to the surface of the conductor is applied, a longitudinal wave is generated, such as Fig. 9 As shown, if a magnetic field perpendicular to the surface of the conductor is applied, transverse waves can be generated.

[0101] like Fig.10 As shown, the electromagnetic ultrasonic sensor can generate longitudinal waves and transverse waves respectively by arranging three magnets 30, longitudinal wave coils 41 and transverse wave coils 42. Fig.10 Among the magnets 30 of the electromagnetic ultrasonic sensor shown, a set of magnets 30 can generate a magnetic field for a transverse wave and a magnetic field for a longitudinal wave with respect to the cast piece 1 .

[0102] With respect to the casting 1, a longitudinal wave coil 41 is arranged in a range where the horizontal component is dominant, and a transverse wave coil 42 is arranged in a range where the vertical component is dominant. A schematic diagram of the magnetic lines of force is shown together between the magnetic poles, but on the surface of the casting 1, a longitudinal wave ultrasonic wave is generated by the magnetic flux of the horizontal component, and a transverse wave is generated by the magnetic flux of the vertical component. More specifically, according to Fleming's left-hand rule, in a longitudinal wave, a Lorentz force is generated in the up and down directions in the figure by the interaction between the horizontal magnetic field and the eddy current induced on the surface (vertical to the paper). It becomes a sparse wave relative to the propagation direction of the ultrasonic wave, thereby generating a longitudinal wave. In a transverse wave, an eddy current perpendicular to the paper is generated in the horizontal direction in the figure, and vibrations based on the Lorentz force in the direction perpendicular to the steel are generated in the same manner, becoming a shear wave (transverse wave) relative to the propagation direction.

[0103] By making the width of each magnet about 20mm (casting width direction) × 30mm (casting drawing direction) × 40mm (height), it is possible to construct a small sensor with a casting width of 100mm and a drawing direction of about 30mm that can generate both longitudinal and transverse waves. It also includes a cooling water channel and a water cooling jacket for maintaining the water channel, and can be formed into a small electromagnetic ultrasonic sensor placed in the casting section (typically a φ200mm roller and a roller interval of 50mm).

[0104] In addition, the pole width also affects the number of turns and line width of the coil. If the pole width is reduced, the coil needs to be thinner on the transmitting side, resulting in the impedance of the coil (especially the DC resistance part) increasing, being unable to withstand the applied current, and being unable to obtain the optimal number of turns. On the receiving side, the number of turns used for detection also needs to be reduced, which reduces sensitivity.

[0105] And, if Fig.11 As shown in FIG. 1 , a magnet of a Halbach array may be formed by adding auxiliary magnets 31 between the magnetic poles to make the magnetic poles orthogonal. By adding auxiliary magnets 31 with equal magnetic pole spacing, the magnetic field can be strengthened and the sensitivity can be improved without changing the magnet size. Specifically, adding auxiliary magnets 31 of the same size to replace Fig.10 The isolator (non-magnetic / non-conductive) in the arrangement of the magnet 30 shown. As a result, the magnetic field strength is increased by about 25%, and the sensitivity can also be improved. The improvement in measurement sensitivity is effective in automatic measurement. If the waveform is not clear (low S / N), automatic judgment cannot be made, and the judgment based on manual analysis and missing measurement is retained.

[0106] Next, a flat or racetrack-shaped coil that matches the pole spacing is placed on the front surface of the magnet. The coil material can be properly designed, and the enameled wire can be flat-rolled or patterned through a flexible printed substrate. If a flexible printed substrate is used, it has the following advantages: it eliminates the production of coils under manual work, reduces characteristic deviations, and can reduce the total thickness to reduce actual lift-off. The wire diameter and space of the coil can be appropriately determined, but the sending side hopes to increase the thickness of the copper foil and the wire diameter as much as possible so that a large current can be applied. Increasing the number of turns increases the number of windings, thereby increasing the induced eddy current, but there is a trade-off that the current that can be applied becomes smaller due to the increase in the impedance of the coil. It is sufficient to determine the balance between the two through experiments or calculations. On the receiving side, it is hoped to increase the number of turns as much as possible.

[0107] The coil and the magnet are housed in a water-cooling jacket. The main body of the water-cooling jacket is preferably made of SUS. By using non-magnetic materials, both mechanical strength and water cooling efficiency can be achieved without affecting the magnetic field distribution. The side opposite to the casting 1 is called the front surface panel, which needs to be designed to be a static magnetic field generated by a magnet and an electromagnetic field generated by a current pulse applied to the coil. Therefore, the front surface panel is considered to be a non-magnetic SUS plate or ceramic with a thickness of about 0.2 mm. In particular, a thin SUS plate has both heat resistance, toughness, and wear resistance, and is non-magnetic, so the electromagnetic field is easier to pass through, and the sensitivity is also less affected. Although ceramics are non-magnetic and non-conductive, they have poor processability and poor strength from the perspective of toughness. In order to obtain practical strength, it is necessary to ensure a thickness of 1 mm to 2 mm, which results in a larger lift-off. Therefore, it is preferred to use a thin non-magnetic SUS plate.

[0108] The electromagnetic ultrasonic sensor constructed in this way is brought close to a predetermined position relative to the object to be measured, and a current pulse is applied to the transmitting coil to generate electromagnetic ultrasonic waves. The generated ultrasonic waves propagate in the cast piece 1 as the object to be measured, causing the surface (receiving surface) of the cast piece 1 to vibrate. On the receiving surface, a current is induced on the surface by the propagated vibration and the static magnetic field generated by the electromagnet on the receiving side, and the change in the surface current is detected as an electrical signal by the receiving coil. The received electrical signal is amplified by a preamplifier with an appropriate frequency band and gain, and is acquired by a PC or the like.

[0109] <Chirped pulse compression and signal processing>

[0110] In the process of electromagnetic ultrasonic transmission and reception, the so-called chirped pulse compression technology can be used. Chirped pulse compression refers to the use of a signal with a waveform whose frequency changes with time (also commonly referred to as a chirped signal or a linear frequency modulation signal. In this specification, it is referred to as a chirped signal) in transmission, and performing arithmetic processing on the waveform of the received signal, including correlation operations on the waveform of the above-mentioned transmission signal. By using this chirped pulse compression processing as the processing of electromagnetic ultrasonic transmission and reception, it is possible to reduce noise and improve time resolution.

[0111] Fig.12 The diagram shows the waveform of the received signal when the magnet of the electromagnetic ultrasonic sensor is a Halbach array and chirped pulse compression is performed. Waveform L1 is a waveform when chirped pulse compression is not performed, and waveform L2 is a waveform when chirped pulse compression is performed.

[0112] In this embodiment, the waveform after the chirped pulse compression (i.e., the above-mentioned operation processing) is further processed by waveform detection at the first gate (the time width before and after including the time T1 of receiving the transmitted wave) and the second gate (the time width before and after including the time T2 of receiving 1.5 reciprocating waves), and propagation time measurement based on the time difference.

[0113] In the existing ultrasonic transmission and reception method, even if chirped pulse compression is used, the detection of the transmission signal is the highest sensitivity. Therefore, in the existing measurement of the coagulation position, the ultrasonic propagation time needs to be manually noise-removed after the electromagnetic ultrasonic measurement, or the appropriate waveform needs to be extracted for judgment, etc., making it difficult to measure automatically.

[0114] The propagation time of ultrasound waves is physically defined as the time from the transmission of ultrasound waves to the reception of ultrasound waves. However, electromagnetic ultrasound waves are transmitted using high-frequency pulses with large currents, so large electromagnetic wave noise is generated at the moment of transmission and leaks into the received signal. Therefore, it is difficult to determine the transmission origin, and it is difficult to calculate the propagation time based only on the received waveform.

[0115] For actual use, it is necessary to determine a reference of the transmission time (transmission origin: T0), and the transmission origin is determined by, for example, the following method.

[0116] 1) Decision based on offline simulation samples

[0117] Ultrasonic waves are transmitted and received using samples with known plate thickness and sound velocity. The transmission origin can be calculated from the position of the received waveform. However, if there is a sound velocity error, etc., it will cause a total deviation.

[0118] 2) Online measurement using thin slabs

[0119] Sometimes the transmission origin can be corrected by measuring under a thin slab. If the slab is thin, the attenuation becomes smaller, so it is easy to detect multiple reflection waveforms. If the 1-time transmission waveform is set as T1 wave, and the 1.5-time reciprocating transmission waveform reflected on the surface of the slab is set as T2 wave, then, for example, using the time T1 of the peak of the T1 wave and the time T2 of the peak of the T2 wave, the transmission origin T0 can be calculated by T0=T1-(T2-T1)÷2. The following is an explanation of the case where the peak position of the waveform is used to calculate the time, but even in the case of zero crossing, envelope processing, etc., the calculation can be performed using roughly the same idea.

[0120] In addition, considering the risk of contact, the sensitivity can be improved by measuring with a short approach, and the transmission origin is also corrected as a condition for the appearance of the T2 wave. It is known that if the approach is about 1mm, the sensitivity will increase by about 6dB. However, there is a risk of damage due to contact and damage / burning of the sensor due to increased heat load, so it is of course difficult to use frequently.

[0121] If the transmission origin T0 is determined in this way, the propagation time Δt can be calculated as T1-T0 in normal measurement. However, the propagation time calculation method based on a fixed transmission origin still has problems.

[0122] First, the transmission origin may change due to individual differences in pulse generators, frequency characteristics, and deviations in the frequency characteristics of coils. It also changes over time, so it is necessary to regularly confirm and recalibrate the transmission origin. When the transmission origin changes, the propagation time shifts, resulting in misjudgment of the coagulation position.

[0123] In addition, when the surface temperature of the slab changes, especially when it is below the Curie point due to supercooling, the electromagnetic ultrasonic wave waveform that is transmitted and received may be deformed. At this time, the phase changes and the apparent propagation time changes. Of course, when peak detection is performed, if the phase changes, the propagation time changes, and the measurement will produce errors.

[0124] Usually, when electromagnetic ultrasound is used to measure the coagulation position, low-frequency ultrasound of tens of kHz to several 100kHz (assuming less than 500kHz) is used. The change in peak position caused by the phase change at this time becomes a change of about 1 / 2 wave of the main frequency, so in the case of 100kHz, it becomes a change of several μs. This is several times larger than the propagation time change usually measured, and thus becomes an abnormal value.

[0125] In ultrasonic flaw detection, zero crossing can be used as signal detection. However, in the measurement of the coagulation position using electromagnetic ultrasonic waves in which the accuracy of propagation time is important, it is more preferable to use the peak detection method described above.

[0126] Therefore, in this embodiment, the sensitivity of transmission and reception is greatly improved by adopting the Halbach array, so that the propagation time measurement without deviation can be performed regardless of the change of the transmission origin or the waveform / phase change using one reflection (a waveform of 1.5 reciprocating times in transmission measurement).

[0127] The time of the directly transmitted wave is set as T1, and the time of the waveform reflected once on the upper and lower surfaces is set as T2, and the propagation time Δt is calculated as Δt = (T2-T1) ÷ 2. According to this process, even if the transmission origin changes, the propagation time Δt can be calculated as the time difference between the time T1 of the 1st transmitted wave and the time T2 of the 1.5th reciprocating wave. In addition, even if the waveform deformation occurs, the detected waveform becomes similar. The reason is that T2 becomes smaller due to the attenuation of propagation. These results can be obtained by detecting each peak and calculating the propagation time Δt.

[0128] Here, the magnets used in the conventional electromagnetic ultrasonic wave generation are simply arrayed magnets, and have low sensitivity, so that the T2 waveform cannot be observed frequently. Fig.13 The received waveform (waveform L2) when the sensor head based on the Halbach array magnet and the chirped pulse compression process are used in combination, and the received waveform (waveform L2) when the sensor head based on the Halbach array magnet and the chirped pulse compression process are used in combination Fig.10 FIG. 1 is a diagram of a received waveform (waveform L3) in the case of a sensor head with a normal magnet and chirp pulse compression processing.

[0129] exist Fig.13 In the example, the position of time T1 can be confirmed together with waveforms L2 and L3. However, the position of time T2 can be confirmed in waveform L2 of the magnet using the Halbach array, but cannot be confirmed in waveform L3. Therefore, when the Halbach array is not used, the transmission origin needs to be defined in advance, but as mentioned above, the transmission origin sometimes changes, and the propagation time cannot be obtained with high accuracy in the existing method.

[0130] In contrast, when chirped pulse compression and a Halbach array magnet are used, the times T1 and T2 can be distinguished, and the propagation time Δt can be obtained by Δt = (T2-T1) ÷ 2. In addition, envelope processing can also be considered for phase changes, but envelope processing is equivalent to low frequency, so the time resolution deteriorates.

[0131] In addition, in the continuously cast slab, the surface is sometimes overcooled. This overcooling is caused by nozzle clogging, poor cooling spray, and the fall of the front end piece, which leads to local uneven flow. In addition, it is also caused by the flow of cooling water in the split part (seat part of the split roll) of the continuous casting drawing roll.

[0132] In addition, when the measurement is performed under the condition of partial supercooling, a single peak can be confirmed in the part without supercooling, and if the transmission origin is determined in advance, it can be obtained from the transmission origin and the peak position of time T1. In contrast, in the supercooled part, the waveform is different, specifically, it is sometimes not a single peak, and it becomes a waveform with the same amplitude on the positive side and the negative side. When the peak position is obtained, the peak on the rear side of the waveform is detected, so the propagation time is calculated to be long.

[0133] In contrast, in this embodiment, the peak values ​​of the T1 wave and the T2 wave are extracted respectively to find the time difference. The waveforms of multiple reflections become similar, so it is sufficient to apply gating to the positions where the respective waveforms appear and perform maximum value extraction. Thus, the propagation time can be automatically calculated in the area of ​​phase change such as the supercooling part.

[0134] By improving the transmission and reception sensitivity using the Halbach array in this manner, it is possible to automatically calculate the propagation time even for a measurement target having temperature non-uniformity and surface magnetic properties variations such as an actual cast slab.

[0135] When a single ultrasonic sensor is used to transmit and receive ultrasonic signals, the time for receiving a single reflected wave may be T1 and the time for receiving a second reflected wave may be T2.

[0136] Together with the above-mentioned traverse mechanism and lifting control mechanism, the Halbach array is adopted and the propagation time calculation process based on the signal processing is used to automate the electromagnetic ultrasonic measurement and the solidification measurement in the continuous casting machine.

[0137] <Shear wave measurement>

[0138] Fig.14 This is an explanatory diagram for explaining the shear wave measurement. In the case of the shear wave measurement, the shear wave does not pass through the unsolidified liquid phase, so when the solidification position 4 is not reached, the shear wave can be received on the receiving side. When the solidification position 4 is reached, the shear wave cannot be received on the receiving side. Therefore, it can be determined that when the shear wave is received, the casting 1 is completely solidified, and when the shear wave is not received, the casting 1 is not solidified.

[0139] <Longitudinal wave measurement>

[0140] Fig.15This is an explanatory diagram for explaining the longitudinal wave measurement. In the case of longitudinal waves, the ultrasonic wave propagates regardless of the presence or absence of a liquid phase. The axial temperature Tc is calculated based on the propagation time Δt of the longitudinal wave, the thickness D of the cast 1, the longitudinal wave sound velocity C (T), the surface temperature Ts, and the ultrasonic transmission model. Then, based on the thermal conductivity calculation table for each characteristic of the cast slab obtained in advance, the elapsed time ty from solidification is calculated, and the casting speed Vc of the cast slab 1 is used to infer the solidification position 4 by the following formula.

[0141] Coagulation position = position of electromagnetic ultrasonic sensor - Vc × ty

[0142] In addition, in the heat conduction calculation table, the relationship between the information related to the axial temperature Tc and the time ty from solidification is obtained. The above heat conduction calculation table is a table in which the heat conduction calculation results based on the steel type to be measured, the cooling conditions and other operating conditions are stored in a database. Fig.15 As shown in the example, with respect to the horizontal axis being "the difference between the solidus temperature and the axial temperature Tc (in °C)" and the vertical axis being "the time elapsed from the start of solidification ty (in minutes)", multiple curves are formed that reflect the differences in the above-mentioned operating conditions. When measuring the solidification position, an appropriate curve is selected for each operating condition (it can also be in the form of a relational expression). In addition, the operating conditions such as the casting speed and the amount of cooling water can be changed, and the longitudinal wave propagation time under the conditions can be directly compared with the solidification position calculated by heat conduction calculation, and the correction coefficient is used as an experimental formula. If the measured longitudinal wave propagation time is substituted into the experimental formula, the solidification position can be calculated.

[0143] <Automatic measurement in the width direction>

[0144] When one lift-off adjustment and electromagnetic ultrasonic measurement are completed, a movement instruction to the next measurement position is given, thereby enabling automatic measurement of the full width of the cast piece 1. Measurement is performed while the electromagnetic ultrasonic sensor is moved horizontally in the width direction, so that Fig.16 As shown in FIG. 1 , the measurement interval in the width direction is determined in advance and the measurement is performed at the position. The cast piece 1 moves in the casting direction, so if the electromagnetic ultrasonic sensor moves in the width direction of the cast piece 1, the measurement point becomes a zigzag shape. After the full width measurement in one direction is completed, the data is set as one group, and the solidification position shape of each group can be calculated (refer to Fig.16 (b)).

[0145] <Automatic measurement in the width direction>

[0146] The measured solidification position and solidification position shape are made to correspond to the cast piece (slab) as a semi-finished product, and the pass or fail judgment of the slab is performed. As described above, the measurement is performed in the width direction, and the solidification position is calculated as a distribution in the width direction. The solidification position / solidification position shape is associated with each slab. Then, a group of data of the solidification position / solidification shape in the width direction is associated with one slab, and the pass or fail judgment is performed. Usually, one slab is inconsistent with one group, and the pass or fail judgment of one slab is performed based on the pass or fail judgment results of more than one group for one slab.

[0147] exist Fig.17 In (a), the two groups associated with one slab are both qualified (OK), so the slab is judged to be qualified (OK). Fig.17 In (b), one of the two groups associated with one slab is OK and the other is NG, so that one slab is determined to be NG.

[0148] The pass / fail judgment of each group is specifically performed based on whether the coagulation position does not deviate from a preset range, and whether the coagulation position shape is included in a specified range.

[0149] In the determination of the solidification position, for example, if the solidification is separated from the light pressure zone, the light pressure is not properly performed, so it is inappropriate. In addition, if only a part in the width direction becomes a state of delayed solidification, the alloy components contained in the molten steel are segregated in the area of ​​delayed solidification, resulting in undesirable conditions such as deterioration of center segregation, so the difference in the solidification position in the width direction becomes an important quality indicator. Therefore, in the case of a solidification position shape that becomes a part of the solidification delay, it is considered that the quality is not suitable and it is considered unqualified.

[0150] In addition, as the result of continuous measurement, it can also be fed back to the operation process, and the cooling conditions such as the change of the secondary cooling mode, the adjustment of the casting speed, the casting section opening mode / light pressure reduction conditions, etc. can be fed back in real time. As the so-called dynamic control of casting, high-quality casting can be achieved by feedback control of the solidification position to the operating conditions. In the case of quality problems such as the measured solidification position shape exceeding the specified range, it can be immediately controlled to the appropriate casting / operating conditions, and it is expected to improve quality and improve the yield rate.

[0151] In addition, for slabs with quality problems, the destination was changed and crushed in the past. However, these countermeasures reduce the yield rate and have a great impact on the cost. In addition, the existing measurement in slab quality assurance is manual measurement or point measurement, so it is difficult to guarantee the slab as a unit, resulting in a large number of inappropriateness such as inappropriateness in each charging and each continuous casting. In contrast, by making judgments on a slab-by-slab basis, the casting conditions can be changed / corrected immediately.

[0152] Moreover, for slabs with quality problems, the impact can also be minimized by changing the processing of the subsequent process. As an example, in the case of an inappropriate solidification position, central segregation and porosity are suspected. In the case of a slab whose solidification position deviates from the specified value, there is a possibility that quality improvement can be achieved through additional heating treatment processes and forging processes. In particular, the forging process has the effect of rendering the voids (pores) in the central part harmless by pressing down with strong force, but since it is an additional process, it requires cost. In contrast, it is possible to balance cost and yield by using the results of the solidification position measurement and applying it only to slabs with problems. In addition, ultrasonic flaw detection of the slab can be carried out to more accurately evaluate / determine the quality and other response measures.

[0153] In the past, the solidification position could not be automatically measured due to the thickness variation of the slab, and the measurement frequency was low due to manual measurement, so it was not possible to measure all the slab-related shapes, and there were restrictions such as the measurement example in the stable state of casting was representative of the casting. Therefore, it was impossible to cope with unexpected acceleration and deceleration, changes in operating conditions, etc. As a result, unqualified slabs were sent to the next process, or excessive removal (downgrading) was performed for safety reasons.

[0154] In contrast, the present embodiment automates the measurement, thereby reliably grasping the solidification position / solidification position shape for all slabs and performing pass / fail determination. As a result, the internal quality of the slabs can be improved, the yield can be increased, and defectives can be suppressed.

[0155] In addition, it was confirmed that although the solidification position shape obtained in this embodiment has some bumps, the solidification position exists within the management range. The results obtained are consistent with other quality indicators such as the actual slab macro, confirming that there is no problem with the quality. In addition, the time required for the measurement is 1 group and 4 and a half minutes of measurement. (17-point measurement 1 point measurement 6 seconds = 102 seconds, movement 10 seconds × 16 times of movement = 160 seconds, a total of 262 seconds (4 minutes and 22 seconds), if the casting speed is set to 1.1m / minute, the measurement of 1 group becomes 4.8m, which is within the range of the length of the slab and can be established with 1 slab. In the existing manual solidification position measuring instrument, the width direction measurement takes about 20 minutes, and it is impossible to make a judgment on each slab.

[0156] <Concept of the solidification position measurement device>

[0157] Next, the concept of the solidification position measuring device is explained. In the past, it was difficult to continuously and automatically measure the solidification position and the solidification state of the cast piece because: due to the thickness change of the cast piece, etc., the electromagnetic ultrasonic sensor comes into contact with the cast piece, and there is a high possibility of major failures such as burning / damage, or the electromagnetic ultrasonic sensor breaks and is caught in the roller. The distance between the cast piece and the electromagnetic ultrasonic sensor, that is, the lift-off, is usually about 4mm to 6mm, and contact is easy to occur due to changes in the thickness of the cast piece and the opening of the roller. On the contrary, there is also the following situation: when the thickness of the cast piece becomes thinner, the lift-off value becomes larger due to thermal deformation of the suspension rod supporting the electromagnetic ultrasonic sensor, and it becomes impossible to measure.

[0158] Furthermore, the thickness of the cast piece varies for each run. Generally, casting / running is performed based on the nominal cast piece thickness of 220 mm, 250 mm, and 300 mm, but the opening pattern of the casting section, the soft reduction conditions, the cooling conditions, and the casting speed vary for each steel grade or manufacturing conditions, and the degree of solidification shrinkage also varies for each steel grade. As a result, even with the same nominal cast piece thickness, the thickness of the cast piece varies by about several millimeters.

[0159] In addition, the following operation is usually performed: the thickness of the final slab is expanded by several millimeters in the middle of casting, and then the opening is gradually reduced by taking into account the light pressure and solidification shrinkage of the segment opening control, and the final slab thickness is controlled. However, in the operation of continuous casting, sometimes there are various reasons such as ladle replacement, deceleration for inserting a partition metal piece for continuous casting of different steel grades, deceleration caused by signs of steel leakage, sudden deceleration caused by operating failure, and temporary stop of casting. In such a sudden deceleration or casting stop, solidification sometimes occurs on the upstream side of the continuous casting equipment. As a result, the thickness of the cast sheet is sometimes several millimeters thicker than expected. This is because: since solidification has been completed inside, it cannot be reduced to the specified thickness in the reduction based on the casting segment. When the casting is restarted or returned to the normal casting speed, the thickened part remains pulled as it is. Furthermore, there is a possibility of reaching the sensor position and contacting the cast sheet.

[0160] As described above, the lift-off of the electromagnetic ultrasonic sensor is usually 4 to 6 mm. However, due to the variation in the thickness of the cast piece, there is a risk of contact with the cast piece, damage to the sensor, or entanglement.

[0161] Therefore, the variation of cast slab thickness is measured by setting the cast slab thickness by adjusting the roll opening of the casting section or by visual observation. Since the measurement involves manual operation, it is not possible to measure continuously, and it is not realistic to measure all runs / all slabs.

[0162] It is also considered to have an interval measuring unit for measuring the distance between the cast piece and the electromagnetic ultrasonic sensor, but there is no distance sensor that can be set between the casting rolls, is heat-resistant, and can be used for a long time in harsh environments such as steam, oil mist, grease, scale, dust, etc., and has an appropriate measurement range and accuracy.

[0163] In addition, continuous casting is a device that produces cast pieces by continuously injecting molten steel into a mold and pulling it out. However, in the final stage of continuous casting, the injection of molten steel is stopped and the casting is pulled out. At this time, the static pressure of the molten steel disappears, so the cast piece becomes thinner. If the cast piece becomes thinner, the lift-off becomes larger, the efficiency of transmission and reception decreases, and the sensitivity of electromagnetic ultrasonic transmission and reception decreases.

[0164] In addition, the surface temperature of the cast piece is very high, reaching about 1000°C, and the hanger is subjected to strong radiant heat. In addition, since it is necessary to travel in a narrow width such as the gap between the casting sections, it needs to be made thin, and a sufficient size must be ensured in the height direction to ensure rigidity. Therefore, a temperature difference is generated above and below the hanger, and a difference in thermal expansion occurs. Usually, the temperature on the cast piece side becomes high, so the cast piece side stretches, and thermal expansion occurs in the direction in which the lift-off of the electromagnetic ultrasonic sensor becomes larger. Setting the height based on the thickness of the cast piece, etc., cannot reflect the warping of the hanger, and the lift-off is larger than the reference / assumption, resulting in reduced measurement sensitivity, reduced accuracy due to deterioration of SN, or complete inability to measure.

[0165] In the present embodiment, for the casting, an electromagnetic ultrasonic sensor is provided on a suspension rod which can be lifted and lowered and moved horizontally by a sensor lifting unit and a sensor moving unit, and an interval measuring unit for measuring the interval between the casting and the electromagnetic ultrasonic sensor is provided. By means of the interval measuring unit, the interval between the casting and the electromagnetic ultrasonic sensor is regularly measured, and the position of the electromagnetic ultrasonic sensor is controlled to prevent the electromagnetic ultrasonic sensor from contacting with the casting, being damaged, or being unable to measure due to a reduction in sensitivity caused by lifting changes, thereby enabling continuous measurement and evaluation of the solidification position of the casting.

[0166] <Quality Management Methods for Metal Materials>

[0167] The solidification position measurement method of the above-mentioned embodiment can also be applied to a quality management method for metal materials, for example. In the quality management method for metal materials, the manufacturing conditions of the next process are controlled according to the solidification position of the casting piece measured using the solidification position measurement method, and the quality of the metal material is managed based on the solidification position measurement result.

[0168] <Casting equipment, metal material manufacturing equipment>

[0169] The solidification position measuring device involved in the above-mentioned embodiment can also be applied to casting equipment such as continuous casting equipment. Moreover, in a metal material manufacturing equipment equipped with the above-mentioned casting equipment, the metal material can be manufactured from the cast pieces manufactured by the above-mentioned casting equipment. Here, the casting equipment refers to the case where there is only one device for casting metal materials or the case where multiple devices are combined.

[0170] In addition, the solidification position measuring device according to the above-mentioned embodiment can also be applied to a metal material manufacturing facility. In addition, in the metal material manufacturing facility, the metal material can be manufactured while measuring the solidification position of the cast piece by the solidification position measuring device.

[0171] <Method for producing metal materials>

[0172] The solidification position measurement method according to the above-mentioned embodiment can also be applied to a method for manufacturing a metal material, for example. In the method for manufacturing a metal material, the solidification position of the casting is measured using the solidification position measurement method while manufacturing the metal material. As a result, a metal material of a predetermined quality can be manufactured.

[0173] According to the solidification position measuring device, solidification position measuring method, metal material quality management method, casting equipment, metal material manufacturing equipment and metal material manufacturing method involved in the above-described embodiment, the solidification position of the casting can be measured continuously and automatically by preventing the electromagnetic ultrasonic sensor from being damaged or burned due to a decrease in lift-off due to a change in the thickness of the casting, and preventing the electromagnetic ultrasonic sensor from being reduced due to an increase in lift-off.

[0174] In addition, in the present invention, it is most preferred that the above-mentioned effect can be reliably obtained when the "metal material" is a "steel material". In addition, it is most preferred that the above-mentioned effect can be obtained to the maximum extent when a "continuous casting device" is adopted as the "casting device".

[0175] The above specifically describes the solidification position measuring device, solidification position measuring method, metal material quality management method, metal material manufacturing equipment and metal material manufacturing method involved in the present invention through the methods and embodiments for implementing the invention, but the gist of the present invention is not limited to these records, and should be interpreted broadly based on the records of the scope of protection requested by this application. In addition, technical solutions that have been variously changed and modified based on these records are of course also included in the gist of the present invention.

[0176] Description of Reference Numerals

[0177] 1, 1A…casting sheet; 2…solidification part; 3…liquid phase part; 4…solidification position (end position of the pit); 6, 6a, 6b…water column rangefinder; 7, 7a, 8…electromagnetic ultrasonic sensor; 10…solidification position measuring device; 11, 12…suspending rod; 13…drive control part; 14…measurement operation part; 15…transmitting part; 21-24…motor; 30…magnet; 31…auxiliary magnet; 41…longitudinal wave coil; 42…transverse wave coil; 61…ultrasonic detector; 62…water supply port; 63…water tank; 64…nozzle; 65…step; 66…water column; 101…casting mold; 102…casting sheet support roller; 103…conveyor roller; 104…casting sheet cutting machine; 110…upper device; L1-L3…waveform; T1, T2…time; Δt…propagation time.

Claims

1. A solidification position measuring device for measuring the solidification position of a casting, characterized in that: have: An electromagnetic ultrasonic sensor is arranged on the outside of the casting sheet; A sensor lifting unit, for adjusting the interval between the casting sheet and the electromagnetic ultrasonic sensor; a spacing measuring unit for measuring the spacing between the casting sheet and the electromagnetic ultrasonic sensor; a computing unit for inferring a solidification position in the casting according to an output of the electromagnetic ultrasonic sensor; and a driving control unit for driving and controlling the sensor lifting unit and the interval measuring unit, The driving control unit controls the position of the electromagnetic ultrasonic sensor through the sensor lifting unit according to the interval measured by the interval measuring unit.

2. The coagulation position measuring device according to claim 1, characterized in that: have: The sensor moving means moves the electromagnetic ultrasonic sensor outside the cast piece in a plane parallel to the horizontal plane of the cast piece.

3. The coagulation position measuring device according to claim 1 or 2, characterized in that: The interval measuring unit sprays water toward the measurement object, and makes ultrasonic waves reciprocate in the water sprayed by the interval measuring unit, and measures the distance from the ultrasonic wave generating unit to the measurement object based on the propagation time of the reflected signal.

4. The coagulation position measuring device according to any one of claims 1 to 3, characterized in that: The transceiver signal of the electromagnetic ultrasonic sensor is a chirp signal whose frequency changes with time. The operation unit performs operation processing including phase operation on the chirp signal.

5. The coagulation position measuring device according to claim 4, characterized in that: After the calculation processing, the calculation unit performs waveform detection on the transmitted wave and / or the reflected wave using a time gate including the transmitted wave and / or the reflected wave, and calculates the propagation time using the time difference of the transmitted wave and / or the reflected wave detected by the waveform.

6. The coagulation position measuring device according to any one of claims 1 to 5, characterized in that: The electromagnetic ultrasonic sensor uses a Halbach array magnet.

7. A method for measuring the solidification position of a casting, characterized in that: include: a step of measuring the interval between the casting sheet and the electromagnetic ultrasonic sensor; an interval determination step, determining whether the measured interval is within a specified range; an interval adjustment step, when the interval is not within a prescribed range, adjusting the interval according to the measured interval; as well as The calculation step is to estimate the solidification position in the cast piece using the electromagnetic ultrasonic sensor when the interval is within a predetermined range.

8. The method for measuring the coagulation position according to claim 7, characterized in that: include: The moving step moves the electromagnetic ultrasonic sensor in a plane parallel to the horizontal plane of the casting sheet.

9. The coagulation position measurement method according to claim 7 or 8, characterized in that: The electromagnetic ultrasonic sensor uses a Halbach array magnet. The transceiver signal of the electromagnetic ultrasonic sensor is a chirp signal whose frequency changes with time. The operation step performs operation processing including phase operation on the chirp signal.

10. A quality management method for metal materials, characterized in that: The manufacturing conditions of the next step are controlled based on the solidification position of the cast piece measured by the solidification position measuring method according to any one of claims 7 to 9.

11. A metal material manufacturing device, characterized in that: A solidification position measuring device according to any one of claims 1 to 6, The metal material is manufactured while the solidification position of the cast piece is measured by the solidification position measuring device.

12. A casting device, characterized in that: A solidification position measuring device according to any one of claims 1 to 6, The cast piece is manufactured while the solidification position of the cast piece is measured by the solidification position measuring device.

13. A metal material manufacturing device, characterized in that: A casting device according to claim 12, A metal material is produced from the cast sheet produced by the casting apparatus.

14. A method for manufacturing a metal material, characterized in that: A metal material is produced while measuring the solidification position of a cast piece using the solidification position measuring method according to any one of claims 7 to 9.

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