Continuous casting machine and rollers for metal slabs

Abstract

The present invention relates to a continuous casting machine for steel, the continuous casting machine comprising a mold, a secondary cooling zone having a plurality of support rollers for guiding a metal strand exiting from the bottom of the mold, and a temperature measuring system configured to measure the temperature within the secondary cooling zone at a plurality of positions along the width of the strand.

Description

[Technical Field]

[0001] The present invention relates to a continuous casting machine for casting molten metal, particularly molten steel; rollers for metal slabs, blooms, billets, or strands; a method for controlling a continuous casting machine; and a computer program. [Background technology]

[0002] In continuous casting, particularly in steel, molten metal is supplied from a tundish into a mold with an open bottom. The mold is cooled, for example, by internal water cooling, which solidifies the metal in direct contact with the mold walls. This is called the primary cooling process. This solidifies a thin shell of metal close to the mold walls, and the metal, called a strand, is removed from the bottom of the mold and guided by rollers, which support the walls of the strand against the ferrostatic pressure of the still-solidifying molten metal within the moving strand. To increase the solidification rate, the strand is cooled, for example, by water cooling of the rollers and / or by a direct spray of water or air mist onto the strand as it passes through the secondary cooling zone. In most continuous casting machines, the strand exits the mold vertically or nearly vertically and is gradually bent horizontally by the rollers as it passes through the secondary cooling zone. At the edges of the secondary cooling zone, the fully solidified strands are cut, which can form semi-finished products such as blooms, billets, or rolled slabs.

[0003] In continuous casting, the solidification rate of the molten metal must be carefully controlled because such a rate significantly affects the final quality of the cast product. For example, if the solidification rate is too fast on one side of the strand, it can lead to bloom, billet, or slab deformation, resulting in a curved cross-section of the final cast product. More seriously, insufficient cooling on one side can cause molten steel breakout, which can lead to significant downtime of the continuous casting machine. Breakout occurs when the solidified shell of the strand ruptures, releasing molten metal throughout the casting equipment and the entire facility. For this reason, molds are often equipped with temperature sensors, such as thermocouples or other temperature sensors, to monitor temperature uniformity along the solidified shell at the mold walls. Temperature non-uniformity can lead to cracks, and open cracks can lead to breakout. However, the secondary cooling zone cannot be monitored in the same manner, particularly due to the harsh environmental conditions caused by high temperatures, spray water, and steam formation.

[0004] The paper by Arnulf Diener and Alfons Drastik (Archiv fur das Eisenhuttenwesen, Volume 53(1982)Nr.1, pp.3-13, doi.org / 10.1002 / srin.198205126, titled "Heat exchange between strands and guide rollers in the secondary cooling zone of a slab continuous casting machine") describes temperature measurements in an experimental setup in which a measuring bolt with multiple thermocouples was inserted into the radial holes of the guide rollers of a continuous casting machine. By using the multiple thermocouples on the measuring bolt to measure the temperature at various distances from the surface of the guide roller, it is possible to calculate the inflow and outflow of heat to and from the roller using a mathematical model. However, this was a theoretical study of the secondary cooling state, and only one measuring bolt was inserted into the guide roller.

[0005] U.S. Patent Publication 2007 / 0251663A1 discloses a casting machine for continuously casting metal, the casting machine comprising: a) a mold configured to be adapted for shaping molten metal into a metal strand; b) a cooling system located downstream of the mold, configured to be adapted for controllably cooling and substantially solidifying the strand before it exits the casting machine; and c) a temperature measuring device configured to detect the surface temperature of the strand, the temperature sensor comprising: i) a sensor configured to be adapted for detecting the temperature of the strand, including a photon sensor that measures the temperature of the strand by detecting photons emitted from the strand; and ii) a gas purge line operably coupled to the sensor, configured to deflect debris from the area of ​​the strand monitored by the temperature sensor by supplying a gas purge. The casting machine further includes a long tubular member having a first end positioned close to the strand and a second end positioned close to the sensor, the tubular member being adapted and configured to allow photons emitted by the strand to pass from the first end of the tubular member to the sensor.

[0006] U.S. Patent No. 6,470,957 discloses a process and corresponding apparatus for detecting the actual force and positional state at the contact surface between a roller and a strand when manufacturing a slab, block, or round steel. A known process for continuously casting metal strands in a continuous casting apparatus has a plurality of upright sections located opposite each other, each upright section having a bearing with corresponding guide rollers located opposite each other, and the known process further has an actuator that can steplessly set the gap between each corresponding roller, and the process includes a) detecting a value of the compressive force generated in the bearing and sending this value to a calculation unit, preferably detecting and sending the actual temperature of the bearing in addition to the compressive force; b) comparing individual measurements of the level of compressive force with respect to one roller or a pair of rollers located opposite each other; and c) using at least one of the measured relatively large values ​​as command variables for controlling at least one of the gap, casting speed, cooling water rate, molten metal supply rate, casting powder supply rate, and mold vibration.

[0007] U.S. Patent Publication 2022 / 0241850A1 discloses an ingot mold for continuous casting of metal to improve breakout detection, the mold comprising an assembly of metal plates backed with a cooling device configured to cool the metal plates by the circulation of a cooling fluid, the ingot mold having a casting axis and comprising at least one optical fiber including a plurality of Bragg filters extending into the wall of at least one metal plate, replacing thermocouples used in the prior art, at least one groove formed in the wall of at least one metal plate in a direction nonparallel to the casting axis of the ingot mold for at least a portion of its length, the groove through which the optical fiber extends, and a tongue having a shape substantially complementary to the groove and closing the groove along its entire length, the groove and the tongue having a shape suitable for the passage of the optical fiber.

[0008] International Publication No. 2016 / 072536A1 discloses a roll checker for measuring the temperature of the rolls of a continuous casting machine and for monitoring the condition of the continuous casting machine without visual inspection, the roll checker comprising: a roll checker body; a sensor unit installed on the roll checker body, which measures the gap between the rolls, the curvature of the rolls, the alignment of the rolls, and the rotation of the rolls; a temperature sensor unit installed on the roll checker body, which detects the surface temperature of the rolls; a camera unit having four cameras installed on the upper and lower sides of both sides of the roll checker body; a central processing unit installed inside the roll checker body, which processes the signals received via the sensor unit, the temperature sensor unit, and the camera unit in a synchronized manner; a transmission unit installed inside the roll checker body, which transmits the synchronization signal from the central processing unit to an external control unit; and a battery unit for supplying power to the central processing unit.

[0009] In this field, there has long been a strong demand for improved continuous casting processes that minimize breakout and improve the surface quality of continuous casting strands. [Overview of the project]

[0010] Therefore, an object of the present invention is to provide improved means for monitoring and controlling processes in which metal strands, blooms, billets, or slabs are processed, particularly continuous casting processes or combined casting and rolling processes. A further object of the present invention is to provide precise systems and methods for determining the condition of support rollers used to support or guide metal strands during continuous casting.

[0011] These objectives are satisfied or achieved by the continuous casting machine according to claim 1, by the rollers according to claim 9, by the method for controlling the continuous casting machine according to claim 15, and by the computer program according to claim 16. Preferred embodiments are described in the dependent claims and specification, as well as in the accompanying drawings.

[0012] According to a first aspect of the present invention, a continuous casting machine is provided for casting molten metal into semi-finished products in the form of blooms, billets, or slabs. This continuous casting machine is A mold configured to receive molten metal from a tundish, and having a primary cooling system for solidifying the metal shell adjacent to the mold walls during casting, A secondary cooling zone comprising a plurality of support rollers for guiding strands exiting from the bottom of the mold through the secondary cooling zone, and a secondary cooling system for cooling the strands, A temperature measuring system configured to measure the temperature within a secondary cooling zone at multiple locations along the width of the strand, and preferably at multiple locations along the length of the strand, It is equipped with.

[0013] This enables the continuous casting machine of the present invention to directly or indirectly monitor the strand temperature, preferably in real time, during the continuous casting process. This makes it possible to control the casting process in response to temperature measurements in the secondary cooling zone of the continuous casting machine, which has previously been impossible to achieve on an industrial scale. In conventional casting machines, temperature is measured in the mold, but not after the strand leaves the mold, at least until the exit of the casting machine, i.e., until the slab is cut. The temperature profile of the strand in the secondary cooling zone is generally predicted by a numerical model. In the prior art, such models could only be verified occasionally and at limited locations, for example, by disabling one water spray in the secondary cooling zone and replacing it with a thermocouple or pyrometer. However, this has the obvious drawback that the cooling system is not intact, and in addition, the measurement may be inaccurate due to the influence of steam in the secondary cooling zone. Therefore, such temperature measurements were not suitable for continuous use during the casting process and were only suitable for experimental setups for testing new metal compositions or new casting conditions, for example, to construct strand temperature profile models that could be used as a substitute for real-time temperature measurements during the casting process.

[0014] In contrast, the present invention provides a system for continuously or continuously acquiring temperature data at multiple locations within a continuous casting machine, particularly at multiple locations within a secondary cooling zone, by measuring the temperature at multiple locations along the width of a moving strand. Preferably, the temperature is measured continuously or at a predetermined sampling rate during the casting process. The sampling rate at which the temperature is measured during the casting process is, for example, 1 second. -1 ~200 seconds -1 A range, preferably 10 seconds -1 ~60 seconds -1 It may also be within that range.

[0015] Real-time temperature measurement at the strand surface is extremely effective in minimizing strand defects by adapting cooling on demand for specific steel grades or other specific casting parameters such as desired casting speed and mold width. This is especially important for steel grades that are prone to cracking due to suboptimal cooling or temperature during casting. Therefore, productivity can be improved by using a continuous casting machine and the associated methods for controlling it. This is because, while many steel grades have been cast using specific parameters based on past data and experience to avoid defects, if the temperature is measured with greater precision during the casting operation, it may be found that different amounts of cooling medium should be used or the casting speed can be increased. This not only reduces costs associated with poor quality but also improves productivity. Furthermore, since the casting machine can optimize the energy and water used by implementing an optimal cooling strategy, the present invention is also environmentally beneficial.

[0016] By measuring the temperature along the width of the strand within the secondary cooling zone, it is further possible to create a temperature map of the strand surface or its vicinity, particularly a two-dimensional (2D) map of such temperature. Such a temperature map can not only be correlated to the temperature of the entire strand, but can also be used to detect surface defects in the strand, such as cracks or dents. Furthermore, such a temperature map can be used to evaluate the condition of the support rollers, particularly the condition of the support rollers with respect to alignment and / or deformation, i.e., to evaluate the so-called machine condition. This allows the present invention to detect if the support rollers are undesirably deformed, curved, or broken on or throughout their surface. This provides very useful information, because a roller that is undesirably curved or misaligned, i.e., a roller that is not sufficiently parallel to an adjacent roller, applies force to the moving strand, causing cracks at the solidification leading edge in the strand. This is because the solidified shell, being pushed by curved or misaligned rollers, causes uneven solidification in the liquid metal core within the strands moving further downstream in the secondary cooling zone.

[0017] By evaluating the mechanical condition of rollers, particularly support rollers, while the casting machine is in operation, the cost and time required for maintenance can be significantly reduced. In the prior art, testing the mechanical condition is performed using a dedicated device called a roll gap checker, which is supplied from time to time through a secondary cooling zone when the casting machine is not in operation, i.e., when it is not at operating temperatures. However, compared to operating conditions, some deformation of the rollers may be missed or mismeasured. In addition, this process for testing the mechanical condition is time-consuming and reduces productivity. The present invention provides a means for testing the mechanical condition, particularly the mechanical condition of support rollers, while a continuous casting machine is in operation. By measuring online in this way, production downtime for machine control is reduced. Furthermore, by replacing rollers only when they are damaged, better predictive maintenance is possible, and therefore costs are reduced. Thus, the present invention optionally utilizes the knowledge that the measured temperature is related to the condition of the support rollers in terms of deformation, wear, and alignment. Therefore, temperature measurement provides a valuable opportunity to take preventative measures to control and improve strand quality, such as surface quality, and especially to reduce the occurrence of internal cracks.

[0018] Therefore, the temperature measurement system can provide at least two types of information: firstly, it can provide real-time information about the cooling state of the moving strand, which can be used to infer information about the solidified shell of the strand and to better control the casting process in order to avoid casting defects; and secondly, it can provide information about the condition of the support roller itself, particularly with respect to wear, alignment, and deformation.

[0019] Integrating the temperature measurement system as part of one or more support rollers has the added advantage that the existing secondary cooling system remains unchanged, except for adjusting the continuous casting process in response to temperature measurements within the secondary cooling zone. Thus, the temperature measurement system forms an integral part of the casting machine. Some prior art has proposed performing temperature measurements using devices placed between support rollers. Any such auxiliary device negatively impacts the quality of the strand by adversely affecting the local cooling state; therefore, this change must be compensated for, and this compensation must be feasible.

[0020] A continuous casting machine is configured to cast semi-finished products such as billets, blooms, or slabs of metal, preferably steel. Such a casting machine is typically configured to continuously cast semi-finished products without downtime, except for maintenance of the casting machine. For casting billets and blooms, the open-bottomed mold has a circular or rectangular horizontal cross-section, such as circular, elliptical, polygonal, or rectangular, resulting in the corresponding cross-section of the strand. In such a casting machine, the support rollers will have a contour corresponding to the cross-section of the strand. Thus, in the case of a round strand, the support rollers will have a concave outer surface. In a continuous slab casting machine, the mold has at least a substantially rectangular cross-section. The present invention is also applicable to continuous casting machines that combine casting and rolling processes. The continuous casting machine of the present invention is preferably a continuous steel casting machine. The casting speed, that is, the speed at which the strand exits the bottom of the mold and is transported through the secondary cooling zone, is typically 0.3 m / min to 10 m / min, preferably 0.5 m / min to 6 m / min, more preferably 0.5 m / min to 2 m / min, for continuous slab casting machines, and 3 m / min to 6 m / min for thin slab casting machines. In the case of billets, the casting speed is typically 0.5 m / min to 6.0 m / min.

[0021] In one embodiment, the continuous casting machine is a continuous slab casting machine for steel, and has a mold with an open bottom, as is known in the art, and having at least a substantially rectangular cross-section, the corners of which may be rounded. Preferably, the horizontal cross-section of the mold is formed such that the strands exiting from the bottom of the mold have at least a substantially rectangular cross-section.

[0022] In a continuous casting machine for casting billets, blooms, or slabs, the direction in which the strand moves through the secondary cooling zone is generally referred to as the casting direction or conveying direction, and the extension of the strand in that direction is its length. The width direction of the strand is perpendicular to the conveying direction, and the width indicates the length of the wider side or extension of the strand, in particular. The thickness of the strand indicates the length of the narrower side or extension of the strand, especially for strands with a rectangular cross-section. The width and thickness directions indicate the width and thickness of the cross-section of the strand, in particular.

[0023] The secondary cooling zone comprises a plurality of support rollers, which are preferably arranged on two opposite sides of the strand or on four sides of the strand, and the axial direction of the support rollers extends at least substantially perpendicular to the casting direction. At the position where the strand exits from the bottom of the mold, since only a relatively thin shell has solidified, the support rollers support the strand and maintain its shape. The liquid central part of the strand gradually solidifies when passing through the actively cooled secondary cooling zone. The secondary cooling system may include one or both of a direct cooling system and an indirect cooling system. The direct cooling system is a spray system that directly sprays a cooling medium, particularly water, onto the strand surface by means of a series of water sprays or air mist sprays arranged between the rolls. The indirect cooling system includes an internal cooling system inside the roller. Such an internally cooled roller has ducts for a cooling medium that is pumped through the roller, particularly along the axial direction of the roller. For example, the ducts for the cooling medium may be arranged in the central part of the roller extending along the axis of the roller. When heat is removed from the strand only by the internally cooled support rollers without providing a direct spray system onto the strand surface, this is referred to in the art as "dry-casting".

[0024] The support rollers may be arranged in a plurality of segments or groups, and each segment or group includes 4 to 10 rollers, preferably 6 to 8 rollers. The support rollers within one segment may be arranged within a single cycle of the internal cooling medium such that the flow rate of the internal cooling medium is controlled together for all the rollers of the segment. Also, the spray cooling nozzles arranged between the rollers of each segment may be arranged within a single cycle. The control system of the casting machine may be able to control the amount of heat removed by adjusting the amount of cooling medium used individually for each cycle or for each segment of the rollers.

[0025] The support rollers may include both a drive roller, also referred to as a guide roller, and a non-drive roller, also referred to as a loose roller. Both the drive roller and the non-drive roller may be internally cooled, particularly water-cooled.

[0026] The temperature measurement system of the present invention is configured to measure the temperature within the secondary cooling zone at a plurality of positions along the width direction of the strand. These positions may be distributed along a direction perpendicular to the conveyance direction, for example, along the axial direction of the roller. The position where the temperature is measured is preferably on or near the strand surface. The temperature measurement system can determine the temperature of the strand surface at a plurality of positions along its width by either directly measuring the temperature of the strand surface or measuring the temperature of one or more support rollers in direct contact with the strand surface. The temperature measurement system may include temperature sensors at a plurality of positions along the width of the strand, particularly 3 to 500 positions distributed along the width of the strand, preferably 5 to 200 positions distributed along the width of the strand, more preferably 10 to 80 positions distributed along the width of the strand. Thereby, the temperature profile of the strand along its width can be obtained, and detailed information regarding the cooling state of the strand is provided. These positions are preferably arranged at equal intervals from each other. During casting, as the strand passes through the temperature measurement system and moves in the conveyance direction, temperature measurement values along the conveyance direction, that is, along the length of the strand, are acquired over time. Thereby, a 2D temperature map can be obtained. However, in some embodiments, the temperature measurement system is also configured to measure the temperature at a plurality of positions along the length direction of the strand. Thereby, the temperature profile across the width and length of the strand can be acquired with a very high temporal resolution.

[0027] Temperature measurement may be performed at a distance of 0 mm to 200 mm from the surface of the strand, preferably 0.5 mm to 20 mm, and more preferably 1 mm to 10 mm. In one embodiment, the temperature measurement system is configured to measure the temperature on one or both sides of the strand, particularly on the longer side extending along the width direction of the strand.

[0028] According to one embodiment, the temperature measurement system comprises a roller, particularly a support roller, which is configured to be positioned in direct contact with the strand within a secondary cooling zone during continuous casting, and the roller is provided with a plurality of temperature sensors distributed along the axial direction of the roller. There may be 3 to 500, preferably 5 to 200, and more preferably 10 to 80 temperature sensors distributed along the axial direction of the roller. By distributing the temperature sensors along the entire axial direction of the roller, the width of the strand can be determined because the temperature drops significantly beyond the width of the strand. In one embodiment, the temperature sensors are also distributed in the circumferential direction of the roller.

[0029] Hereinafter, rollers equipped with temperature sensors or other sensors, especially support rollers, are also referred to as "instrumented rollers."

[0030] By providing a temperature sensor in or on a roller that contacts the surface of the strand, useful information regarding the temperature of the strand surface, preferably information related to the temperature profile along the width direction and optionally along the length direction (the direction in which the strand is transported), as well as information regarding the condition of the roller itself, particularly information regarding the condition of the roller itself related to alignment, wear and deformation, may be collected.

[0031] In one embodiment, the roller is a support roller, preferably a non-driven roller. In another embodiment, the roller is a driven roller. The roller may or may not be internally cooled, particularly water-cooled. In one embodiment, a temperature sensor is provided on one or more support rollers in the secondary cooling zone.

[0032] By measuring the temperature at multiple locations along the axial direction of the support roller, the condition of the support roller, particularly its alignment and / or deformation, i.e., the so-called machine condition, can be evaluated. This may be done by analyzing a temperature map of the strand surface. This allows for the detection of undesirable deformation, bending, or breakage of the support roller.

[0033] The temperature sensor is preferably embedded within the support roller. This protects the temperature sensor from the harsh conditions in the secondary cooling zone, allows for more accurate measurements, and extends the lifespan of the temperature sensor. The temperature sensor may be embedded within the roller, for example, at a distance of 0.5 mm to 20 mm, preferably 1 mm to 10 mm, from the outer surface of the roller. The sensor may also be embedded within a notch on the roller surface, in which case the notch may extend along the axial direction of the roller. The sensor may also be embedded within a channel instead of a notch, the channel not opening towards the outer surface of the roller, and at least a portion of the channel extending along the axial direction of the roller. The channel may extend along the axis of the roller. The channel may also extend downward from the outer surface of the roller at a distance of 0.5 mm to 20 mm, preferably 1 mm to 10 mm. The notch or channel is machined, for example, drilled, within the roller. A cylindrical sheath may be additionally placed around the roller to protect the sensor. In another embodiment, the roller is manufactured by placing a sensor on the outer surface of the roller and placing a cylindrical sheath around the roller and sensor. In this way, the sensor is protected from wear and damage by the sheath.

[0034] The temperature sensor may be positioned or placed on one or more lines along such notches or channels. In the case of rectangular slabs, blooms, or billets, the temperature sensor is positioned, in particular, along one or more lines extending axially along the roller. In the case of round billets, since the roller is not cylindrical, the lines extend axially and also follow the outer shape of the roller. Depending on the type of temperature sensor used, the lines may be formed by optical fibers, for example, in the case of fiber Bragg gratings, or by electrical cables when connecting thermocouples. If the temperature sensor is a thermocouple, the lines may also be formed by a thin-film temperature sensor, as disclosed in "A thin-film temperature sensor based on a flexible electrode and substrate" by Z. Liu et al., Nature Microsystems & Nanoengineering (2021) 7:42, doi.org / 10.1038 / s41378-021-00271-0, which is incorporated herein by reference. The temperature sensors may be arranged at approximately equal intervals along the line. The temperature sensors may also be arranged at approximately equal intervals along the axial direction of the roller, where "approximately" in this specification means within ±15%, preferably within ±10%.

[0035] According to one embodiment, the lines may extend only in the axial direction, in which case the temperature sensors are arranged on one or more lines extending on or parallel to the roller axis. In the case of a round billet, the lines further follow the concave outer shape of the roller. According to one embodiment, the temperature sensors are arranged on a plurality of parallel lines distributed circumferentially around the roller, preferably on 2 to 12 lines, more preferably on 4 to 8 lines.

[0036] According to another embodiment, the temperature sensors are arranged on lines extending both axially and circumferentially from the roller, particularly on helical lines. The temperature sensors may be distributed on one or more lines extending circumferentially from the roller, for example, on two to four helical lines.

[0037] In a further embodiment, the temperature sensor is located within a plurality of rings that extend in close proximity to or on the roller surface and have the roller axis at their center. The rings may be arranged at least at substantially equal intervals along the axial direction of the roller and may be formed by notches or channels housing the temperature sensor.

[0038] By distributing sensors along the axial direction of the roller, it becomes possible to measure the temperature across the entire width of the strand. If a single line of temperature sensors extends axially, measurements are taken once per roller rotation, resulting in relatively large intervals along the direction of strand transport. For example, on the slab surface, only 2 to 10 measurements are taken per minute, or, depending on the roller diameter, only one measurement is taken every 0.3 to 1.2 meters along the length of the strand. Therefore, it is advantageous to distribute the temperature sensors along the circumferential direction of the roller, particularly in a helical arrangement. This allows the temperature to be measured by proximity measurement on or near the surface of the strand, on the side of the strand where the roller is located. By placing such rollers on both sides of the strand, a temperature map can be obtained from both sides of the strand with unprecedentedly high temporal and spatial resolution. For example, the spatial resolution is 1 cm across the strand surface. 2 ~1000cm 2 Preferably 10 cm 2 ~100cm 2 One sample per person is sufficient.

[0039] By providing the support roller with two or more temperature sensors spaced apart from each other in the radial direction of the roller, i.e., spaced apart from each other toward the inside of the roller, it becomes possible to calculate heat transfer from the temperature difference and spacing between the sensors. In one embodiment, the support roller is provided with two lines of temperature sensors at two different depths (radial distances) from the roller surface, for example, one line at a depth of 1 mm to 3 mm and the other line at a depth of 4 mm to 6 mm.

[0040] According to one embodiment, the temperature sensor is a fiber Bragg grating, and more specifically, multiple fiber Bragg gratings (FBGs) are arranged on a single optical fiber. In this embodiment, a roller is provided with one or more optical fibers, each optical fiber having up to several hundred FBGs. The fiber Bragg grating is part of the optical fiber, and within the optical fiber, a periodic refractive index variation is encoded in the core. By modulating the refractive index, the FBG acts like a mirror, reflecting certain wavelengths and transmitting other wavelengths. The wavelengths reflected by the FBG depend on the distance between high-refractive-index and low-refractive-index regions within the fiber. The distance between two high-refractive-index regions within the fiber is called the period of the FBG. Since the distance between the high-refractive-index regions changes when the optical fiber is compressed or stretched along its length, FBGs can be used as sensors for detecting strain, temperature, and pressure. FBGs have the advantage that measurements are performed non-electrically and that they can withstand high temperatures and humidity in a secondary cooling zone because the measurement signal is transmitted along the optical fiber. In addition, multiple FBGs can be incorporated into a single optical fiber, and in particular, they can be distributed along its length, making it possible to measure temperature at multiple locations distributed along the axial direction of the roller. For example, 2 to 500, preferably 10 to 100 FBGs, may be arranged axially or helically on a single optical fiber extending along the roller, for example, within a notch or channel near the outer surface of the roller. The optical fiber may include a core having a high refractive index, in which the FBGs are written, and the core is surrounded by a cladding having a higher refractive index, thereby confining light within the core. The FBGs can be configured to measure temperature. According to one embodiment, FBGs may also be provided that are configured to measure the compressed or extended state of the optical fiber, thereby allowing the deformation state of the roller to be measured.

[0041] In other embodiments, the temperature sensor may be a thermocouple. The thermocouple may be connected to an electrical cable extending within a notch or channel along a roller. For example, a thin-film thermocouple may be used, in which case multiple thermocouples may be housed within the notch or channel. Other types of temperature sensors, particularly other types of sensors embedded in optical fibers, may also be used.

[0042] According to one embodiment, the temperature measurement system comprises a plurality of support rollers, each support roller being provided with a plurality of temperature sensors, as described herein or in the claims, for example, FBGs provided on one or more optical fibers. In one embodiment, two instrumentation rollers, particularly two support rollers, may be provided on both sides of the strand. According to another embodiment, each segment of the support roller comprises at least one support roller provided with a temperature sensor. For example, the drive roller may be an instrumentation roller. By providing a plurality of support rollers with temperature sensors, a higher-resolution temperature map of the strand surface can be obtained. In addition, temperature measurements performed by sensors on the support rollers provide useful information about the mechanical condition of the rollers, particularly useful information relating to alignment, wear, and deformation. Information about rollers adjacent to rollers equipped with temperature sensors can also be provided. Therefore, it is advantageous to provide temperature sensors on a plurality of support rollers, thereby deriving better information about the mechanical condition. In one embodiment, instrumentation rollers comprise more than 20% and less than or equal to 100% of the support rollers in the secondary cooling system, preferably more than 40% and less than or equal to 100%, and most preferably more than 60% and less than or equal to 100%.

[0043] In a preferred embodiment, at least one of the support rollers is further provided with at least one deformation sensor. This allows for the determination of forces related to the interaction between the support roller and the strand. This makes it possible to detect defects in the strand, such as cracks that may occur due to deformation of the support roller. The deformation sensors may provide measurements of the deformation of at least one support roller continuously or at a predetermined sampling rate during the continuous casting process. Thus, the deformation of the support roller can be measured in real time (online). By using these measurements, the condition and integrity of the support roller or support roller segment equipped with the deformation sensor can be monitored while the continuous casting machine is in operation, thereby providing useful information regarding maintenance needs and, consequently, useful information regarding the machine's condition. At least one deformation sensor may be a fiber optic gauge (FBG). In addition to the temperature sensor, an additional optical fiber dedicated to measuring deformation may be provided. In another embodiment, both an FBG for measuring temperature and an FBG for measuring deformation are integrated in one or more optical fibers extending along the axial direction of the roller, for example, in a notch or channel. The optical fiber may extend spirally around the roller, or it may extend parallel to the axis of the roller. In one embodiment, all non-driven rollers in the secondary cooling section are provided with temperature sensors, and all driven support rollers are provided with deformation sensors.

[0044] In other embodiments, the deformation sensor is formed by a resistance sensor. For example, the sensor may be as disclosed by Z. Liu et al., “A thin-film temperature sensor based on a flexible electrode and substrate,” Nature Microsystems & Nano-engineering (2021) 7:42, doi.org / 10.1038 / s41378-021-00271-0, which is incorporated herein by reference.

[0045] According to one embodiment, the temperature measurement system further comprises a thermal imaging camera (TIC) configured to image at least one of a portion of the strand and / or a support roller. Thermal imaging is an additional way of obtaining a temperature map of the strand surface, either on one or both sides of the strand. The TIC is preferably positioned at a distance sufficient to take a thermal image of at least a substantial portion (>50%) of the strand width from the strand surface. Thereby, high-resolution temperature measurement can be performed directly from the strand surface. The TIC is preferably configured to take thermal images at a predetermined sampling rate of 10 seconds -1 ~1000 seconds -1 and thus a very high-resolution temperature map can be obtained. Additionally or alternatively, the TIC can be configured to take thermal images of one or more support rollers. Thus, the temperature may be imaged at a position of the support roller where the support roller is not in direct contact with the strand, for example, on the opposite side. In addition to one or more instrumentation rollers, it is preferable to have a thermal imaging camera.

[0046] According to one embodiment, the continuous casting machine further comprises a control unit for controlling the continuous casting machine, configured to adjust at least one casting parameter of the continuous casting machine in response to temperatures measured at multiple locations along the width of the strand within the secondary cooling zone. The control unit may be a computing device such as a central processing unit. The control unit may be connected to user input / output devices such as a screen, mouse, and keyboard. The control unit may be embodied as a computer, laptop, mobile device, etc. Prior art control systems use models to predict cooling within the secondary cooling zone, because in the prior art, there is no real-time temperature measurement with respect to the secondary cooling zone. In contrast, the present invention provides real-time temperature measurement between the primary cooling zone of the mold and the casting machine exit where the slab is cut. This allows, for example, the use of an optimal cooling strategy at any point during casting, thereby reducing the amount of defects in the product, particularly the casting slab. This helps to avoid cracks that occur during solidification and cooling due to uneven or suboptimal cooling. The casting parameters, which are adjusted in response to the measured temperature, include one or more of the following: the cooling parameters of the secondary cooling system, the cooling parameters of the primary cooling system, the strand exit rate from the mold (casting rate), and the mold width. The cooling parameters of the secondary cooling system include the amount of cooling medium sprayed per unit time over the entire support rollers or in each segment within the secondary cooling zone. It may also include the rate of the cooling medium flowing through the internally cooled support rollers. The cooling parameters of the primary cooling system may include the amount of cooling medium sprayed onto the mold.

[0047] The control unit may be configured to perform a data analysis process with respect to the measured temperature, i.e., the acquired temperature data. For example, when using FBGs on a support roller as described herein, a two-dimensional temperature map of the strand portion in contact with the roller may be reconstructed by considering the roller diameter, the position of each FBG in the axial and circumferential directions of the roller, and the casting speed, and consequently the roller's rotational speed. Such a two-dimensional map can be reconstructed from a single optical fiber having multiple FBGs. The control unit may also consider that the temperature of each temperature sensor changes periodically with the rotation of the roller and reaches its highest temperature at the position in contact with the strand. This periodic fluctuation may have an approximately sawtooth shape.

[0048] According to one embodiment, the control unit is configured to reconstruct a two-dimensional temperature map of at least a portion of the strand in the width direction. This may be, in particular, one side or portion of the strand on which the temperature measurement is performed, especially one side or portion of the strand on which the temperature measurement is performed by a roller in contact with the portion of the strand. Such a two-dimensional temperature map may have already been obtained from temperature measurements on a single roller equipped with temperature sensors distributed along the axial direction. The more temperature sensors placed on the roller, the better the spatial resolution of the temperature map. In particular, if the temperature is measured with sufficiently high spatial resolution for a portion of the strand, for example, by providing a roller equipped with one or more optical fibers having a large number of fiberglass gauges, e.g., 20 to 500 fiberglass gauges, the temperature map may be used to detect surface defects such as cracks or dents. For example, cracks may be visualized by rapid temperature changes on the 2D temperature map. This information is extremely valuable. This is because, for example, casting conditions can be adjusted immediately by reducing the casting speed, and surface defects can be identified and located within the casting slab, allowing the affected portion to be discarded.

[0049] According to one embodiment, the control unit is configured to determine the state of at least one of the support rollers of the secondary cooling system, particularly the alignment and / or deformation state of at least one support roller, thereby providing useful information regarding the need for maintenance of the support roller, and consequently, useful information regarding the mechanical condition. The support roller is preferably an instrumentation roller. In particular, the condition of the roller can be evaluated when a two-dimensional temperature map of a portion of the strand in contact with the support roller is reconstructed. This is because if the roller is deformed, bent, broken, or misaligned, a uniform force is not applied to the strand along its length (axial direction). Rather, at the position where the support roller is deformed, the support roller is instead pressed strongly against the solidified strand, and after half a rotation, it rotates away from the strand and ceases to contact it. At the position and time when the roller is pressed against the strand, the measured temperature is higher compared to the position and time when the roller is away from the strand. As a result, an alternating pattern, referred to herein as a "chess pattern," is formed on the 2D temperature map. This chess pattern provides both information about the type of deformation based on an analysis of the distribution of the chess pattern, and information about its severity, i.e., information about the severity of deformation based on the temperature fluctuations between the high-temperature and low-temperature areas within the pattern. If the support rollers are not perfectly aligned, the temperature profiles may differ between adjacent rollers because one of the adjacent rollers may experience greater forces on the strand than the other. If the support rollers being measured are inclined, especially if one side is positioned closer to the strand than the other, the temperature pattern obtained from these support rollers will also be inclined, with the temperature on one side being higher than the other. This information about the mechanical condition of the support rollers is extremely useful for enabling timely replacement of the support rollers as needed. This ensures that optimal slab quality is always achieved and reduces the cost of predictive maintenance.

[0050] In another embodiment, the present invention relates to a roller, preferably a support roller, configured to be positioned in contact with a metal strand, billet, bloom, or slab, wherein the roller is equipped with a plurality of temperature sensors distributed along the axial direction of the roller and preferably also distributed circumferentially. Thus, the roller is an instrumentation roller. The roller is configured to guide, transport, or support a semi-finished steel material, particularly in any industrial process of steelworking where the temperature of the steel material is critical. Preferably, the roller is a support roller in a continuous casting machine, and may be configured to be positioned in contact with a strand within the secondary cooling zone of the continuous casting machine. In another embodiment, the roller is a table roller on the runout table of a rolling mill in a thin slab casting machine. A runout table is a table on which a slab is guided before and after passing through a rolling mill, which may be a hot rolling mill or a cold rolling mill. In either process, the temperature of the slab is closely monitored because it is related to the outcome of the rolling procedure. Such a table roller is configured to be positioned in contact with a metal slab during hot rolling or cold rolling. In such a process, considering the high rotational speed of the rollers during the process and the shorter contact time between the rollers and the slab, it is preferable to place the temperature sensor near the surface of the rollers.

[0051] In a further embodiment, the roller, preferably the support roller, further comprises at least one deformation sensor. This allows for the determination of forces related to the interaction between the support roller and the strand. This makes it possible to detect defects in the strand, such as cracks, that may occur due to the deformation of the support roller. The deformation sensor may provide measurements of the deformation of the support roller. By using these measurements, the condition and integrity of the support roller or support roller segment equipped with the deformation sensor can be monitored during the operation of the continuous casting machine, thereby providing useful information regarding maintenance needs and, consequently, useful information regarding the machine's condition. The at least one deformation sensor may be a fiberglass backing (FBG).

[0052] All the features and advantages mentioned for the continuous casting machine also apply to the rollers, and vice versa. In particular, the temperature sensor is preferably a plurality of fiber Bragg gratings exposed on at least one optical fiber. The roller is preferably provided with one or more optical fibers extending axially and, optionally, circumferentially to give a helical configuration. One or more such optical fibers may be provided. Other types of sensors may also be used.

[0053] According to one embodiment, the temperature sensor is embedded within the roller, particularly within a channel extending below the outer surface of the roller. This protects the temperature sensor from the harsh environment of the secondary cooling zone. However, since the roller is positioned in direct contact with the strand or slab, the temperature measurement is still sufficiently accurate. The channel is, for example, a duct completely embedded within the roller, or alternatively, a notch opening on the outer surface side of the roller. The notch or channel may extend parallel to the axial direction, or it may have a helical configuration.

[0054] According to one embodiment, the roller comprises a converter box positioned at the head of the roller and configured to rotate with the roller, the converter box comprising a media converter that converts an optical signal from at least one optical fiber into an electrical or electromagnetic signal. This embodiment is preferably combined with an embodiment in which a temperature sensor is an FBG positioned on at least one optical fiber. Since optical fibers cannot be twisted, it is preferable that the optical signal is converted on the roller itself into another type of signal, particularly an electromagnetic signal that can be transmitted wirelessly. Therefore, the converter box may be positioned at one axial end of the roller. The energy required to transmit the signal may be obtained from a Peltier generator. The wireless signal is preferably transmitted using a low-range protocol such as Wi-Fi. In another embodiment, the optical fiber, particularly a glass fiber, must be guided to the head of the roller, precisely at the position of its axis of rotation, and aligned with a fixed optical fiber that is in direct contact with the end of the optical fiber rotating on the roller. This also allows for the transmission of optical signals.

[0055] In another embodiment, the roller may comprise a stationary shaft and a rotatable shell surrounding the shaft, in which case the temperature sensor is positioned in a fixed position relative to the stationary shaft, and in particular, embedded within the stationary shaft. The rotatable shell is attached to the shaft, for example, by ball bearings. The space between the stationary shaft and the rotatable shell may contain a lubricant. Alternatively, there may be no bearings, and only a lubricant is present between the stationary shaft and the rotatable shell. In this embodiment, the temperature sensor is positioned in the space between the shaft and the shell, or alternatively, embedded within the shaft. The temperature sensor may be positioned on a notch or channel extending along the axis of the stationary shaft, or below the surface of the stationary shaft. The stationary configuration of the temperature sensor in this embodiment facilitates the transmission of an optical signal from the roller to a control unit. In this case, an optical fiber may extend from the roller to a converter, which is mounted in a stationary configuration. The signal is transmitted from the converter to the control unit wirelessly or via cable. In another embodiment, the temperature sensor may be positioned on a rotatable shell.

[0056] In a further embodiment, the present invention relates to a method for controlling a continuous casting machine as described herein and claimed. The method includes the steps of: receiving temperature measurements from a temperature measuring system, continuously or in a continuous manner, preferably also with respect to deformation via one or more deformation sensors; adjusting at least one casting parameter of the continuous casting machine in response to the temperature measurements; and / or determining the state of at least one of the support rollers of a secondary cooling system, in particular the alignment state and / or deformation state of at least one support roller, based on the temperature measurements and optionally also on the deformation measurements. All features and advantages described with respect to the continuous casting machine and rollers also apply to the method of the present invention, and vice versa. In particular, the method may be carried out by a control unit of the continuous casting machine as described herein and claimed. In particular, the method may further include process steps for analyzing temperature measurements and deformation measurements, for example, a process step for reconstructing a 2D temperature map from them; and a process step for analyzing such a 2D temperature map.

[0057] In a further embodiment, the present invention relates to a computer program including program code, which, when executed by a control unit of a continuous casting machine, causes the control unit to perform the method described herein and claimed. The computer program may be embodied as a computer program product. All features and advantages described with respect to the continuous casting machine, rollers and method also apply to the computer program and computer program product, and vice versa. The present invention also relates to a non-temporary digital storage medium on which the computer program or computer program product is stored. The storage medium may be an optical, magnetic, or solid-state storage medium, such as an SD card, SSD card, hard disk, or CD-ROM. The computer program may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0058] The present invention will be described below with reference to the attached drawings, according to embodiments. The drawings are as follows. [Brief explanation of the drawing]

[0059] [Figure 1] Figure 1 shows a schematic cross-sectional view of a continuous slab casting machine according to one embodiment of the present invention. [Figure 2] Figure 2 shows schematic perspective views of six different embodiments of a support roller equipped with multiple temperature sensors. [Figure 3] Figure 3 shows schematic diagrams of the fiber Bragg grating, synchrotron radiation spectrum, and reflected light spectrum. [Figure 4] Figure 4 shows a cross-section of a roller segment in a secondary cooling system according to one embodiment of the present invention. [Figure 5] Figure 5 shows a cross-section of a support roller according to one embodiment of the present invention. [Figure 6] Figure 6 shows a cross-section of a roller according to a further embodiment of the present invention. [Figure 7] Figure 7 shows a plan view of the two support rollers (left) and the corresponding 2D temperature map (right). [Figure 8] Figure 8 shows a plan view (right) and a corresponding temperature map (left) of the support roller deformed at two different positions. [Figure 9] Figure 9 shows a schematic cross-sectional view (top) and a schematic perspective view (bottom) of a support roller according to a further embodiment of the present invention. [Modes for carrying out the invention]

[0060] Identical or corresponding features are indicated by the same reference numerals throughout the drawings and claims.

[0061] Figure 1 shows a schematic cross-section of a continuous slab casting machine 1 according to one embodiment of the present invention. In the continuous slab casting machine, molten metal 8, in particular steel, is held in a ladle 7 and transferred from the ladle 7 to a tundish 6. From the tundish 6, the liquid metal is supplied into the mold 2 through a submerged entry nozzle 3. The flow of molten steel may be controlled by a valve or stopper 5. The molten steel forms a liquid pool 12 with a meniscus level 4 within the mold 2. The mold 2 can be cooled by internal cooling, which causes the steel to solidify at the walls of the mold, forming a solidified shell 16. This part of the cooling system is referred to as the primary cooling system 11. The solidified shell 16 is pulled out from the bottom of the mold by motor-driven guide rollers 15 located below the mold. In addition to the motor-driven guide rollers, the strand 10, including the solidified shell 16 and liquid core 17, is supported by a number of closely spaced loose rollers 14. The support rollers 14 and 15 may be internally cooled by a cooling medium. Furthermore, water spray nozzles 18 are typically spaced between the support rollers 14 and 15 to further cool the strand 10 during the ongoing solidification process as the strand moves in the casting direction. This part of the continuous slab casting machine is referred to as the secondary cooling zone 22. The support rollers 14 and 15 further bend the strand 10 into a horizontal path, then straighten the strand 10 to a flattened state, after which the fully solidified strand may be cut, for example, by a torch cutter 25, thereby forming a semi-finished product in the form of a rolled slab 20. The operation of the continuous slab casting machine 1 is controlled by a control unit 28. The control unit 28 controls, among other things, the flow of molten metal 8 from the tundish 6 through the immersion nozzle 3 to the mold 2, and also controls the speed at which the motor-driven guide rollers 15 pull the strand 10 out of the mold 2 (commonly also referred to as the casting speed). Furthermore, the control unit 28 may be configured to control the cooling rate, in particular the flow rate of the cooling medium (e.g., water) supplied by the nozzle 9 in the primary cooling system 11 and by the nozzle 18 in the secondary cooling zone 22.

[0062] According to one embodiment of the present invention, a temperature measuring system 30 is installed in the secondary cooling zone 22 and is configured to measure temperature at multiple locations along the width of the strand, which may be perpendicular to the plane of the paper in Figure 1. Preferably, the temperature measuring system 30 includes at least one support roller, which is configured to be positioned in contact with the strand 10 and has a plurality of temperature sensors 30b. Such a roller may be an additional roller 24 present in addition to the support rollers 14, 15 of the secondary cooling zone, which preferably has a smaller diameter than the support rollers 14, 15 and is positioned between the two normal support rollers. Because this additional roller 24 has a smaller diameter, it may be sufficient to have only one or two lines of temperature sensors along the length of such a roller in order to perform sufficient measurements along the casting direction L of the strand 10. Instead of or in addition to such an additional roller 24, temperature sensors may be provided on one or more of the support rollers 14, 15 necessary to support and guide the strand 10 in the secondary cooling zone. For example, one or more of the support rollers 14 may have one or more lines (e.g., 2 to 8 lines, e.g., 3 lines as shown in Figure 1) of temperature sensors 30b, which are generally arranged along the axial direction of the roller, which is in a direction along the width direction of the strand 10 and perpendicular to the casting direction L of the strand 10. Optionally, the temperature measurement system may further include one or more thermal imaging cameras (TICs) 30a positioned on one or both sides of the strand. Such TICs 30a may acquire thermal images of a portion of the secondary cooling zone, and in particular may record the temperatures of the support rollers 14, 15. This provides useful information regarding the solidification state of the strand 10 or the mechanical condition of the support rollers 14, 15.The temperature measurements taken by the temperature measurement systems 30a and 30b are transmitted to the control unit 28 by wireless transmission, such as WIFI, and are used by the control unit 28 to better control the casting process and monitor the condition of the support rollers. The control unit 28 may execute a computer program stored on a digital storage medium 29, in this example, a CD-ROM. According to a preferred embodiment, the temperature measurement system does not include a thermal imaging camera 30a, but instead, or in addition to it, includes one or more support rollers 14, 15 equipped with a temperature sensor 30b.

[0063] Figure 2 schematically shows several embodiments of support rollers 14a to 14f having different arrangements of temperature sensors. Roller 14 may be a non-driven roller or a driven roller.

[0064] The support roller 14a shows one embodiment in which a plurality of optical fibers are arranged on or near the surface of the support roller and extend axially parallel to each other. For example, 4 to 12 optical fibers may be distributed along the circumferential direction φ, preferably at approximately equal intervals, with 3 of them shown on the roller 14a. The plurality of optical fibers 33 can be arranged within notches so that these optical fibers do not directly contact the strand. A plurality of fiber Bragg gratings (FBGs) 32 are arranged at intervals along each optical fiber 33. Each FBG 32 functions as a temperature sensor, thereby providing the roller with a close-spaced mesh of temperature sensors 32 configured to measure the temperature on one side of the strand with high spatial resolution. For example, the temperature sensors may be arranged on the roller surface at distances of 5 mm to 100 mm in both the axial direction z and the circumferential direction φ. According to one embodiment, not all sensors arranged on the optical fibers 33 need to be temperature sensors 32. For example, every other optical fiber may be provided with a deformation sensor 34 instead. Alternatively, every other FBG may be configured to measure elongation instead of temperature. This would also allow for the measurement of the deformation of the support roller 14a, providing important information about the wear condition of the support roller 14a.

[0065] The support roller 14b is also provided with an optical fiber 35, which extends spirally along the circumferential direction of the roller. Similar to the support roller 14a, the temperature sensor 32 and / or deformation sensor 34 are distributed along the length of the optical fiber 35. The advantage of the spiral arrangement is that the sensors can be distributed both axially and circumferentially, while requiring only a single optical fiber.

[0066] As shown in the support roller 14c, the two spirally arranged optical fibers 35a and 35b achieve better spatial coverage of the roller surface.

[0067] Instead of FBG, thermocouples can also be used as temperature sensors, as shown in support rollers 14d, 14e, and 14f. In roller 14d, thermocouples 36 are arranged in multiple lines 38 that are axially aligned and spaced apart along the circumferential direction of the roller. In one embodiment, the thermocouples are inserted into notches extending along the lines 38. Alternatively, channels may be provided below the outer surface of the roller, and thermocouples may be arranged within such channels. In support roller 14e, the lines 39 of the thermocouples 36 are arranged spirally around the surface of the roller, thus requiring only a single line. To improve the spatial coverage of the roller surface, double loops 39a and 39b may be provided, as shown in support roller 14f. Support rollers 14c and 14f use closed-loop and double-spiral configurations, which are advantageous, in particular, in terms of spatial resolution.

[0068] Figure 3 shows a fiber Bragg grating 32 on an optical fiber 33. The optical fiber 33 typically includes a core 41 surrounded by cladding layers 40 made of materials with different refractive indices, allowing light to travel along the core 41. The FBG 32 itself has a structure, for example, a length of 0.3 mm to 5 mm, and has a structure in which multiple regions with different refractive indices are sequentially stacked. This periodic modulation of the refractive index allows the FBG to be tuned to selectively reflect light at a specific temperature f0. This is shown in the two graphs below; the upper graph shows the frequency spectrum of light irradiated by the FBG. The lower graph shows the spectrum of light reflected by the FBG. This frequency is called the Bragg frequency f0 and changes with temperature due to the thermo-optic effect on the refractive index. Thermal expansion may further contribute, and this thermal expansion changes the dimensions of the Bragg grating 32. An advantage of FBGs is that they can be multiplexed; that is, hundreds of FBGs can be housed within a single optical fiber 33. In addition, since each fiber Bragg grating can measure not only temperature but also, for example, elongation, the optical fiber 33 having the FBG can also be used as a sensor for deformation of the support rollers 14, 15. Since each FBG can operate at different frequencies f0 of the optical spectrum, for example, 10 to 500, preferably 50 to 100 FBGs can be arranged on a single optical fiber 33 and may be illuminated by a single light source. In one embodiment, the refraction signal received by the optical sensor is converted into an electromagnetic signal.

[0069] Figure 4 schematically shows cross-sections of two segments of support rollers 14 and 15 within a secondary cooling zone according to one embodiment of the present invention, with one segment positioned on each side of the strand 10. Each segment may be controlled as a single unit. In the illustrated embodiment, each segment has one drive roller 15 and a plurality of loose rollers (five loose rollers 14 in this example). A spray nozzle 18 for cooling the strand is positioned between the support rollers 14 and 15. The amount of cooling medium can be controlled individually for each segment.

[0070] Temperature sensors, such as FBGs or thermocouples, may be arranged as follows: Preferably, rollers with temperature sensors are present on opposing sides of the strand 10, for example, as a pair of rollers on either side of the strand. For example, temperature sensors may be provided on two support rollers 14 located at the lower end. In addition, deformation sensors may be optionally provided on two drive rollers 15. Alternatively, both pairs of rollers may be provided with both temperature sensors and deformation sensors, and both temperature sensors and deformation sensors may be provided on the same optical fiber as needed. In a further embodiment, temperature sensors are present on each roller within these two segments 44. Figure 4 also shows an embodiment in which a thermal imaging camera 30a may be positioned to acquire a thermal image of a portion of the secondary cooling zone 22. The TIC 30a has a field of view 31 positioned to acquire the temperature of three rollers in segment 44. Since the TIC30a measures the temperature of the roller side facing away from the strand 10, the measured temperature is not strictly the temperature of the strand surface, but it is still accurate enough to be used to control the casting process and provides information about the mechanical condition, particularly the deformation or damage state of the roller.

[0071] Figure 5 shows a cross-section of the support roller 14g and indicates the location of the temperature sensor 30b. This embodiment shows a water-cooled support roller 14g, in which the cooling medium is guided through a central cooling duct 48. In other embodiments of the roller, the cooling ducts 48 may be further arranged radially outward or distributed circumferentially around the roller. To accommodate the temperature sensor 30b, the support roller 14g has a channel 46 extending downward from the outer surface of the roller, in which a TC or FBG may be placed. The channel 46 may be oriented axially, or it may be spirally arranged along the roller. The channel 46 may be located, for example, at a distance of 1 mm to 5 mm downward from the outer surface of the support roller 14g. In another embodiment, the optical fiber may be placed in a notch 47, which has a similar size and orientation to the channel 46 but opens toward the strand surface.

[0072] Figure 6 shows a further embodiment of the support roller 14h, which comprises a stationary shaft 50 and a rotatable shell 51 having a ring-shaped cross-section. An advantage of this roller configuration is that the shaft 50 remains stationary during use and may be positioned to hold a temperature measuring system, thereby simplifying the transmission of the temperature measuring system to a control unit 28 (not shown). A cooling duct 48 may be located within the shaft 50. For example, a TC or FBG may be located within an axial or helical notch 52 machined into the outer surface of the shaft 50. Thus, the temperature sensor 30b is substantially located on the outer surface of the shaft 50 or embedded within the outer surface of the shaft 50 or in the space between the shaft 50 and the outer shell 51.

[0073] Figure 7 shows a 2D temperature map 56 reconstructed from temperature measurements of temperature sensors 30b on support rollers 14, 15. The temperature map 56 may have a width z corresponding to the axial length of the support roller 14, or more precisely, the length z along which the temperature sensors 30b are distributed. The casting direction is indicated as L. Thus, the 2D temperature map 56 can be continuously or sequentially updated in the casting direction L as the continuous casting process progresses and the strand is conveyed along the rollers.

[0074] To reconstruct the temperature map 56, the distribution of individual temperature sensors 30b on the surfaces of the support rollers 14 and 15 must be known. For example, the temperature sensors may be placed at intervals of 1 cm to 5 cm in the axial direction and at intervals of 1 cm to 20 cm in the circumferential direction of the support roller 14. From the individual measurements and the knowledge regarding the spatial distribution of these temperature sensors 30b, the control unit 28 or another computing device can reconstruct the 2D temperature map 56. This may be performed in real time during the casting operation so that the most up-to-date temperature map 56 is always available and so that the possibility of defects in the rollers and / or defects in the strand can be analyzed, in which case at least defects in the strand can be mitigated by adjusting the casting parameters. The upper part of Figure 7 shows the casting of a relatively narrow strand 10a, and accordingly, a narrow 2D temperature map 56 is shown. The width W1 of the map 56 corresponds to the width of the strand 10a and may therefore be measured by the temperature measurement system. The lower part of Figure 7 shows the temperature map 56 obtained when casting a strand 10b with a larger width W2.

[0075] The temperature map 56 also typically shows lower temperatures towards the ends of the support roller 14 and higher temperatures in its center. As shown in Figure 7, if the temperature map 56 is relatively smooth, this indicates that the support roller 14 is in good mechanical condition.

[0076] Figure 8 shows how the temperature map 56 may be affected by the deformation of the roller equipped with the temperature sensor 30b. In this case, the support roller 14i is bent in the center, which means that during the continuous casting process, the support roller 14i alternately presses into the strand in the center (shown on the lower side) and presses into the strand at its outer end in the z direction (shown on the upper side). Higher temperatures are measured at the positions where the support roller 14i is pressed into the strand 10 compared to positions along the width direction z where the support roller 14i is bent away from the strand 10. Thus, the highest temperatures are measured either in the center of the strand or at its outer end in the z direction, resulting in the formation of a "chess pattern" on the temperature map 56. By analyzing the pattern on the temperature map 56 in this way, it is possible to infer the type and severity of the deformation of the support roller 14i. This analysis can be performed by the control unit 28 or by another computing device and can be used to trigger replacement or maintenance of the support roller 14i as needed. Similar useful information may be obtained from the deformation sensor. A similar temperature pattern can be detected even when the temperature sensor 30b is located on an adjacent support roller 14 rather than on the deformed support roller 14i. This is because the strand 10 deforms accordingly, causing the strand 10 to be pressed against the non-deformed roller in various ways along the length of the roller. Therefore, similar information may also be obtained for rollers adjacent to the roller having the temperature sensor.

[0077] Figure 9 shows an embodiment in which temperature measurements can be transmitted to a control unit by an optical fiber 33. Figure 9 shows a support roller 14k that is rotatable around a ball bearing 62. The optical fiber 33 is led over the length of the support roller 14, through the portion on the ball bearing 62, toward a so-called interrogator box 66. For example, four optical fibers 33, each having 16 FBGs, may be used. The interrogator box 60 includes a media converter 64 that converts the optical signal into an electromagnetic signal. This electromagnetic signal may be transmitted via a radio signal 66, for example via a low-band signal, to a receiver 27 which may be connected to a control unit 28 (not shown in Figure 9). The interrogator box 60 is positioned to rotate together with the support roller 14.

[0078] The foregoing description is intended merely to illustrate the System and Method, and should not be construed as limiting the appended claims to any particular embodiment or any particular set of embodiments.

[0079] In the claims, the terms “equipment” or “include” are not precluding other elements or processes, and the indefinite articles “an” or “a” are not precluding plural.

[0080] No reference numeral in the claims should be construed as limiting the claims attached.

Claims

1. A continuous casting machine (1) for casting molten metal, particularly molten steel (8), into semi-finished products (20) in the form of blooms, billets, or slabs, A mold (2) configured such that the molten metal (8) is supplied from a tundish (6), and the mold (2) has a primary cooling system (11) for solidifying a solid metal shell (16) adjacent to the wall of the mold during casting, A secondary cooling zone (22) comprising a plurality of support rollers (14, 15) for guiding the strand (10) exiting from the bottom of the mold (2) through the secondary cooling zone (22), and a secondary cooling system (18) for cooling the strand (10), A temperature measuring system (30a, 30b) configured to measure the temperature within the secondary cooling zone (22) at multiple positions along the width of the strand (10) and preferably at multiple positions along the length of the strand (10), The continuous casting machine (1) is equipped with the above.

2. The continuous casting machine (1) according to claim 1, wherein the temperature measuring system (30a, 30b) comprises rollers (14, 24, 15), particularly support rollers, configured to contact the strand (10) within the secondary cooling zone (22) during casting, and the rollers (14, 24, 15) are provided with a plurality of temperature sensors (32, 36) distributed along the axial direction (z) of the rollers (14, 15).

3. The continuous casting machine (1) according to claim 1 or 2, wherein the temperature measuring system (30a, 30b) comprises a plurality of support rollers (14, 15), and each support roller is provided with a plurality of temperature sensors (32, 36) distributed along the axial direction (z) of the roller.

4. The continuous casting machine (1) according to any one of claims 1 to 3, wherein at least one of the support rollers (14, 15) is equipped with at least one deformation sensor (34).

5. The continuous casting machine (1) according to any one of claims 1 to 4, further comprising a thermal imaging camera (30a) configured to image a portion of the strand (10) and / or at least one of the support rollers (14, 15), wherein the temperature measurement system (30a, 30b) further comprises a thermal imaging camera (30a).

6. The continuous casting machine (1) further comprises a control unit (28) for controlling the continuous casting machine (1), wherein the control unit (28) is configured to adjust at least one casting parameter of the continuous casting machine (1) in response to a temperature measured by the temperature measuring system (30a, 30b), according to any one of claims 1 to 5.

7. The continuous casting machine (1) according to claim 6, wherein the control unit (28) is configured to determine at least one state of the support rollers (14, 15) of the secondary cooling system (22), in particular an alignment state and / or deformation state of at least one of the support rollers (14, 15).

8. The continuous casting machine (1) according to claim 6 or 7, wherein the control unit (28) is configured to reconstruct a two-dimensional temperature map (56) of at least a portion of the strand (10).

9. Rollers (14, 15) for supporting a semi-finished product (20) or strand (10) of a metal, particularly steel, in a secondary cooling zone (22) of a continuous casting machine (1) according to any one of claims 1 to 8, wherein the roller (14) is provided with a plurality of temperature sensors (32, 36) distributed along the axial direction (z) of the roller, and preferably in addition to that, distributed in the circumferential direction (φ) of the roller (14).

10. The roller (14, 15) according to claim 9, wherein the temperature sensor is embedded in the roller, particularly in a channel (46) that extends below the outer surface of the roller (14).

11. The roller (14, 15) according to claim 9 or 10, wherein the temperature sensor is a plurality of fiber Bragg gratings (32) arranged on at least one optical fiber (33).

12. The roller (14, 15) according to claim 11, comprising a converter box (60) disposed on the head portion of the roller and configured to rotate together with the roller, wherein the converter box (60) comprises a media converter (64) for converting an optical signal from at least one optical fiber (33) into a wireless signal (66).

13. The roller (14, 15) according to any one of claims 9 to 12 comprises a stationary shaft (50) and a rotatable shell (51) surrounding the shaft, and the temperature sensors (32, 36) are positioned at a fixed position (52) with respect to the stationary shaft, particularly embedded within the stationary shaft (50).

14. The roller (14, 15) according to any one of claims 9 to 13, further comprising at least one deformation sensor (34).

15. A method for controlling a continuous casting machine (1) according to any one of claims 1 to 8, (a) A step of continuously or continuously receiving temperature measurement values ​​from the temperature measurement system (30a, 30b), (b1) A step of adjusting at least one casting parameter of the continuous casting machine (1) in response to the temperature measurement, and / or (b2) A step of determining, based on the temperature measurement, the state of at least one of the support rollers (14, 15) of the secondary cooling system, in particular the alignment state and / or deformation state of at least one of the support rollers (14, 15), Methods that include...

16. A computer program including program code, which, when executed by a control unit (28) of a continuous casting machine (1), causes the control unit (28) to perform the method described in claim 15.

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