System for continuous casting and method for replacing submerged nozzles

Abstract

The present disclosure relates to a casting system for continuous casting comprising a tundish, a mould, a first and a second tundish nozzle configured for supplying liquid metal through a bottom side of the tundish, a first stopper for controlling liquid metal flow through the first tundish nozzle, a second stopper for controlling liquid metal flow through the second tundish nozzle, a first submerged nozzle removably coupled to the first tundish nozzle, and a second submerged nozzle removably coupled to the second tundish nozzle. The system further comprises two nozzle replacement systems configured for decoupling each one of the submerged nozzles from its tundish nozzle and replacing it while the other submerged nozzle is supplying liquid metal into the mould.

Description

System for continuous casting and method for replacing submerged nozzlesField of the disclosure

[0001] The present disclosure relates to a system for continuous casting, more specifically a system that comprises a replacement system for replacing submerged nozzles. The present disclosure also relates to a method for replacing submerged nozzles.Background

[0002] Continuous casting processes are widely utilized in the steel manufacturing industry to produce high-quality metal products efficiently and economically. During continuous casting, molten metal is continuously poured from a tundish into a mould, where it solidifies into a semi-finished product such as slabs, billets, beams or blooms.

[0003] The moulds may typically have a rectangular or square cross-sectional geometry, reflecting the desired shape of for instance the slabs to be casted.

[0004] For slab casting, depending on the applications, the slabs may for example have a width between 80 mm and 300 mm. Slabs having a width in the upper range, for example slabs having a width of 200 mm to 300 mm are generally named conventional slabs, or thick slabs.

[0005] In more recent years, the direct thin slab casting and rolling process is gaining interest among steel makers to produce hot-rolled coils, thanks to its efficiency, competitiveness, and sustainability over conventional thick slab casting process.

[0006] Continuous casting of slabs, especially thin slabs, not only requires a mould having a smaller top opening, but also a specific entry nozzle is required to supply the molten metal from the tundish into the mould.

[0007] The entry nozzle is a nozzle that is submerged or at least partly submerged into the liquid metal in the mould in order to prevent re-oxidation of the metal.2

[0008] In the domain of continuous casting, the entry nozzle may also be named submerged nozzle, submerged entry nozzle, abbreviated as SEN, or submerged entry shroud, abbreviated as SES, or the entry nozzle may simply be named tube or shroud.

[0009] The geometry of the submerged nozzle and the number and geometry of the outlet openings of the submerged nozzle are specifically designed to optimize the flow of the liquid metal injected into the mould.

[0010] Generally, the submerged nozzle couples at its top side with a tundish nozzle which is a conduit allowing the liquid metal to cross through the bottom side of the tundish. The tundish nozzle may also be named upper nozzle.

[0011] In combination with a stopper or a sliding gate system, the flow rate of molten metal from the tundish into the submerged nozzle can be regulated during the continuous casting processes.

[0012] To cover the majority of the market requirements, the slab casters, for instance thin slab casters, have a high flexibility and can produce a wide range of steel grades, including high quality alumina killed steel, for example for automobile applications.

[0013] However, the use of alumina to deoxidize these steel grades leads to clogging of the casting channel, mainly in the submerged nozzle, which significantly reduces the tundish sequence length.

[0014] Hence, when the submerged nozzle is clogged, replacement with a new submerged nozzle is required.

[0015] Devices for replacing nozzles for conventional slab casters are known in the art. For example, US2014 / 0203051 A1 discloses a device for replacing a submerged nozzle wherein the replacement device is coupled to a bottom side of a casting vessel and wherein reserve submerged nozzles are moveable on a guiding rail by using a pushing arm. When the submerged nozzle is to be replaced, the reserve submerged nozzle pushes the submerged nozzle that starts moving along the rail to a waiting position, while the reserve submerged nozzle takes the position of the previous submerged nozzle. In these systems, the new replacement submerged nozzle enters from one side of the mould and the old submerged nozzle exits the mould from another side of the mould.3

[0016] Although replacement devices, also known as tube changers or linear tube changers, have demonstrated to be a well-known and well controlled process for many years, the tube changers currently used for conventional slab continuous casting may not be suitable for high throughput thin slab continuous casting.

[0017] A first challenge is related to the casting speed. High throughput endless casters generally have a minimum casting speed usually above 3m / min, which is necessary to achieve the high mass flow required to operate in full endless production mode to produce for instance ultra-thin gauge products. Ensuring casting tube immersion during the tube change process while maintaining the casting speed becomes challenging.

[0018] A second challenge is related to the geometry of the mould and submerged nozzle. Thin slabs require a narrow mould width, for example between 80 and 200 mm. Due to the narrow mould width the access to the submerged nozzle becomes more difficult and installation of mechanical replacement devices becomes more cumbersome.

[0019] Generally, the submerged nozzles for high throughput slab continuous casting also imply a specific design of the casting tube. Also the precise and foolproof positioning of the submerged nozzle with respect to the mould becomes critical.

[0020] A third challenge, especially in combination with the narrow mould geometry, is related to the avoidance of mould level perturbations during the change of the submerged nozzle, for instance avoiding the occurrence of waves.

[0021] CN1448234A describes a slab casting system wherein two submerged nozzles are provided within a same mould to increase casting speed. However, no solution is provided for handling clogging of any of the two submerged nozzles.

[0022] Document US2011 / 204103A1 describes a tundish nozzle exchanging device and a tundish nozzle for use in the device, reducing a distance between holes of the tundish nozzles, juxtaposed at a bottom of a tundish, compared to the conventional model. The device includes a pair of first arms pressing and supporting a first lower nozzle, the first lower nozzle located at an undersurface of a first upper nozzle placed at the bottom of the tundish; and a pair of second arms pressing and supporting a second lower nozzle, the second lower nozzle4 located at an undersurface of a second upper nozzle placed at the bottom of the tundish and adjacent to the first upper nozzle.

[0023] Document US5688425A describes a submerged nozzle changing apparatus. This apparatus comprises a slide valve device for controlling the rate of discharge of a molten metal from a molten metal container; a nozzle holding cylinder actuator supported in a vertical position under the slide valve device; and a guide arm unit supported on the piston rod of the nozzle holding cylinder actuator in a horizontal position.

[0024] Document US10183326B2 describes a slab continuous casting apparatus configured to supply molten metal from a tundish to a slab water-cooled mold through at least an upper nozzle, a stopper, and an immersion nozzle. The apparatus is provided with an immersion nozzle quick replacement mechanism.

[0025] Document US2001 / 035438A1 describes an exchangeable continuous casting nozzle.

[0026] Hence, in view of these challenges outlined above, there is room for improving casting systems having replacement devices for replacing submerged nozzles, especially nozzle replacement devices adapted for use with thin slab high throughput continuous casting systems.Summary

[0027] It is an object of the present disclosure to provide a casting system for continuous casting wherein the submerged nozzles are replaceable in a foolproof way.

[0028] The present invention is defined in the appended independent claim. The dependent claims define advantageous embodiments.

[0029] According to a first aspect of the invention, a casting system for continuous casting of metallic products, such as for example billets, beams, blooms and slabs, is provided.

[0030] The casting system comprises a tundish, a mould, a first and a second tundish nozzle configured for supplying liquid metal through a bottom side of the tundish, a first stopper for controlling liquid metal flow through the first tundish nozzle, a second stopper for controlling liquid metal flow through the second tundish nozzle, a first submerged nozzle coupled to the first tundish nozzle, anda second submerged nozzle coupled to the second tundish nozzle, and wherein the first and second submerged nozzle are removably coupled to respectively the first and second tundish nozzle. The casting system further comprises a first nozzle replacement system configured for decoupling the first submerged nozzle from the first tundish nozzle and replacing the first submerged nozzle while the second submerged nozzle is supplying liquid metal into the mould, and a second nozzle replacement system configured for decoupling the second submerged nozzle from the second tundish nozzle and replacing the second submerged nozzle while the first submerged nozzle is supplying liquid metal into the mould.

[0031] Advantageously, by providing two submerged nozzles for supplying liquid metal to the same mould, a high-throughput can be guaranteed for continuous casting, as liquid metal can be provided simultaneously through the two nozzles.

[0032] Advantageously, by providing two submerged nozzles and two respective nozzle replacement systems, each of the submerged nozzles can be replaced independently from each other, for instance while one submerged nozzle is being replaced the other submerged nozzle may continue to supply liquid metal to the mould. Additionally, as the continuous casting process continues during the replacement procedure of the submerged nozzle, the time period required to perform the replacement becomes less critical.

[0033] Advantageously, by providing a nozzle coupling mechanism for each of the submerged nozzles, coupling and decoupling of the submerged nozzles may be performed independently of each other and one submerged nozzle may remain coupled and the other submerged nozzle may be decoupled and replaced by using a gripper arm.

[0034] Preferably, the first nozzle replacement system is configured for insertion and extraction of the first submerged nozzle into and from the mould through a first spacing between a bottom side of the tundish and an upper portion of the first short side of the mould, and the second nozzle replacement system is configured for insertion and extraction of the second submerged nozzle into and from the mould through a second spacing between the bottom side of the tundish and an upper portion of the second short side of the mould. The first and the1814_26 second tundish nozzle are typically located between the first and the second spacing.

[0035] Preferably, each of the nozzle replacement systems comprises a coupling mechanism configured for coupling the submerged nozzle to the corresponding tundish nozzle and a gripper arm configured for gripping the submerged nozzle and moving it out of the mould and / or for introducing a replacement submerged nozzle into the mould.

[0036] Advantageously, by providing a nozzle replacement system having a gripper arm for gripping the submerged nozzle combined with a coupling mechanism for automatically coupling and decoupling the submerged nozzle with the tundish nozzle, the coupling of the submerged nozzle with the tundish nozzle is performed in a vertical direction, in contrast with prior systems wherein the coupling process is an horizontal sliding. Indeed with the present casting system, after decoupling the submerged nozzle from the tundish nozzle with the coupling mechanism, the gripper arm is holding the submerged nozzle and initially moves the submerged nozzle in a vertical direction to separate the submerged nozzle from the tundish nozzle, and thereafter a rotation and translation of the submerged nozzle towards a short side of the mould allows to extract the submerged nozzle from the mould through the spacing between the mould and the bottom side of the tundish. Such a vertical coupling of the submerged nozzle to the tundish nozzle minimizes the wearing of the tundish nozzle. Moreover, it reduces the creation of waves in the mould.

[0037] Preferably, each nozzle replacement system is configured such that when the coupling mechanism is in the holding position HP and the two gripper fingers of the gripper arm are inserted into the corresponding finger receiving locations of the respective submerged nozzle, the two support fingers of the coupling mechanism are parallel with the two gripper fingers of the gripper arm, and preferably lower than the two gripper fingers. More preferably, the two support fingers and the two gripper arms are oriented parallel with a first and second short side of the mould The two support fingers and the two gripper fingers may be pointing in an opposite direction. In this way an optimum geometry is obtained for extracting a submerged nozzle from or inserting a submerged nozzle in the mould1814_27 above one of the short sides of the mould by performing a movement of the submerged nozzle in a plane parallel with the long sides of the mould.

[0038] Advantageously, by changing the submerged nozzle above one of the short sides of the mould, the replacement of the first submerged nozzle does not perturbate the operation of the second submerged nozzle located closer to the other short side of the mould. Moreover, having the gripper fingers above the support fingers makes possible for the retractable support to move to the retracted position while the submerged nozzle is held by the gripper fingers.

[0039] Preferably, insertion and extraction of a submerged nozzle comprises a rotational movement of the submerged nozzle. For instance, when removing the submerged nozzle, by performing a rotation of the submerged nozzle towards the short side of the mould, the movement of the submerged nozzle while the submerged nozzle or a portion of the submerged nozzle is still submerged in the liquid metal can be reduced and therefore perturbations of the liquid metal during the replacement process are minimized. For instance, a long translation movement of the submerged nozzle while the submerged nozzle is being submerged in the liquid metal, as is the case for the known prior art linear replacement systems and which causes disturbances of the liquid metal, is avoided.

[0040] According to a second aspect of the invention, a method for replacing submerged nozzles during continuous casting is provided. The method comprises steps of decoupling a first submerged nozzle from a first tundish nozzle and removing the first submerged nozzle from the mould and replacing the first submerged nozzle with a first replacement submerged nozzle while continuing supplying liquid metal to the mould with a second submerged nozzle.Short description of the drawings

[0041] These and further aspects of the present disclosure will be explained in greater detail by way of example and with reference to the accompanying drawings in which:Fig.1 schematically illustrates a schematic cross-sectional view of a part of an embodiment of a casting system according the present disclosure comprising a8 first and a second submerged nozzle for providing liquid metal from a tundish to a mould,Fig.2a and Fig.2b show a schematic top view of two embodiments of a casting system according to the present disclosure, illustrating two different relative positions of the mould with respect to the tundish,Fig.3a to Fig.3f schematically illustrate sequential movement steps of the submerged nozzle when applying the method for removing the submerged nozzle from the mould according to the present disclosure,Fig.4a is a cross-sectional view of an embodiment of a nozzle coupling mechanism and a nozzle assembly comprising a tundish nozzle and a submerged nozzle, wherein the cross-section is taken in a plane Z-Y parallel with the short side of the mould,Fig.4b is a cross-sectional of the same embodiment as shown in Fig.4a wherein the cross-section is taken in a plane Z-X parallel with the long side of the mould, perpendicular to the plane Z-Y,Fig.5a and Fig.5b are cross-sectional views of an example of an embodiment of a tundish nozzle and a submerged nozzle,Fig.6 is showing various cross-sectional views, taken with respect to orthogonal planes X-Y, X-Z, Y-Z, of an embodiment of a nozzle replacement system which includes a coupling mechanism and a gripper arm,Fig.7 is showing views of an embodiment of a coupling mechanism for coupling the submerged nozzle with the tundish nozzle,Fig.8a is a schematic top view of an embodiment of a submerged nozzle flange, Fig.8b is a schematic side view of a further embodiment of a submerged nozzle flange,Fig.9a and Fig.9b are cross-sectional views of an embodiment of a coupling mechanism that is configured for moving the submerged nozzle from a casting position to a shut off position, wherein Fig.9a and Fig.9b illustrate respectively the casting and the shut off position,Fig.10a and Fig.10b are showing a top view of the coupling mechanism shown on Fig.9a and Fig.9b, illustrating the casting and shut off position when viewed from the top,9Fig.11 a and Fig.11 b are schematically illustrating relative positions of sensors for measuring a liquid level in the mould with respect to the location of the two submerged nozzles.

[0042] The drawings of the figures are neither drawn to scale nor proportioned. Generally, identical components are denoted by the same reference numerals in the figures.Detailed description of embodimentsCasting system, general

[0043] With reference to Fig.1 , a cross-sectional view is shown of parts of an embodiment of a casting system 600 for continuous casting of metallic products, especially semi-finished casting products, according to the present disclosure. The casting system 600 comprises a tundish 200 and a mould 300 and the casting system is further provided with two separate nozzle assemblies 100 for supplying liquid metal to the same mould 300. A nozzle assembly 100 is here defined as a combination of a tundish nozzle 20a, 20b and a submerged nozzle 10a, 10b coupled to form a fluidic channel.

[0044] As illustrated on Fig.2a and Fig.2b, a mould 300 for slab casting typically comprises a first long side 303 opposite a second long side 304, and a first short side 301 opposite a second short side 302. In embodiments, the first and second long side are parallel and / or the first and second short side are parallel. In embodiments, the mould 300 may have a rectangular or a bulged cross-sectional shape.

[0045] For slab casting, the mould generally has a width MW smaller than 300 mm and / or a mould length ML smaller than 3500 mm. For thin slab casting, the mould has a mould width MW smaller than 200 mm, preferably smaller than 160 mm, more preferably smallerthan 140 mm and / ora mould length ML smaller than 2500 mm, preferably smaller than 1500 mm, more preferably smaller than 1000 mm. The mould length ML is a distance measured between the short sides 301 , 302 of the mould 300 and the mould width MW is a distance measured between the long sides 303,304 of the mould 300, as schematically illustrated on Fig.2a, Fig.2b and Fig.11 a.1814_210

[0046] The cross-sectional view of the casting system 600 shown in Fig.1 , is a cross-section taken in a plane X-Z of an X,Y,Z orthogonal coordinate system. The plane X-Z is a plane transverse, preferably perpendicular, to the two short sides 301 , 302 of the mould and the plane Y-Z is a plane transverse, preferably perpendicular, to the long sides 303,304 of the mould.

[0047] The present disclosure is not limited to a specific relative geometry of the mould with respect to the tundish. The orientation and relative position of the mould with respect to the tundish may be different from embodiment to embodiment. For example, in Fig.2a and Fig.2b a top view is shown of two embodiments of a casting system 600 according to the present disclosure, illustrating two different relative positions of the mould 300 with respect to the tundish 200.

[0048] An example an embodiment of the tundish nozzle 20a and the submerged nozzle 10a of a nozzle assembly 100 is shown on Fig.5a and Fig.5b wherein various cross-sections of the tundish nozzle 20a and the submerged nozzle 10a are shown with respect to the X,Y,Z coordinate system. As illustrated on Fig.2a and Fig.2b, the X-axis and the Y-axis are axes parallel with respectively the long sides 303,304 and the short sides 301 , 302 of the mould 300.

[0049] As shown on Fig.1 , a first nozzle assembly 100 comprises a first submerged nozzle 10a removably coupled to a first tundish 20a nozzle and a second nozzle assembly 100 comprises a second submerged nozzle 10b removably coupled to a second tundish nozzle 20b. The first and second tundish nozzle are configured for supplying liquid metal through a bottom side 201 of the tundish 200, and, as for example schematically illustrated on Fig.3a, the casting system 600 further comprise a first stopper 400a for controlling liquid metal flow through the first tundish nozzle 20a and a second stopper 400b for controlling liquid metal flow through the second tundish nozzle 20b.

[0050] The submerged nozzles 10a, 10b are typically manufactured from a refractory material, e.g. ceramic.

[0051] In embodiments, as schematically illustrated on Fig.1 , the second submerged nozzle 10b is a mirror image of the first submerged nozzle 10a with respect to a mirror plane P3. The mirror plane P3 is a plane transverse to the long sides 303, 304 of the mould 300, preferably the mirror plane P3 is1814_211 perpendicular to the long sides 303, 304 of the mould 300. In Fig.1 , the mirror plane P3 is shown as a plane perpendicular to the Z-X plane. In this example, the mirror plane P3 divides the mould 300 into two halves, for instance equal halves.

[0052] In embodiments, the mirror plane P3 may not only be a plane of mirror symmetry for the two submerged nozzles 10a, 10b, it may also be a plane of mirror symmetry for the two tundish nozzles 20a, 20b and / or the two stoppers 400a, 400b.

[0053] Due to for instance clogging of the submerged nozzles 10a, 10b, the life time of the submerged nozzles 10a, 10b may be shorter than a casting period. Therefore, when clogging is suspected or as part of preventive maintenance procedures, the submerged nozzles 10a, 10b are to be replaced with replacement nozzles during the casting period.

[0054] The casting system 600 according to the present disclosure comprises a first and a second nozzle replacement system, not shown on Fig.1. The first nozzle replacement system is configured for decoupling the first submerged nozzle 10a from the first tundish nozzle 20a and replacing the first submerged nozzle 10a while the second submerged nozzle 10b is supplying liquid metal into the mould 300. The second nozzle replacement system is configured for decoupling the second submerged nozzle 10b from the second tundish nozzle 20b and replacing the second submerged nozzle 10b while the first submerged nozzle 10a is supplying liquid metal into the mould 300.

[0055] In embodiments, the plane P3 may be a plane of mirror symmetry for the first and second nozzle replacement system.

[0056] In embodiments, the casting system 600 typically comprises a controller for controlling the liquid flow through the two nozzle assemblies 100 by controlling the positions of the two stoppers 400a, 400b with respect to an entrance side of the tundish nozzles 20a, 20b.

[0057] I n embodiments, the controller is configured for operating the first stopper 400a for blocking liquid metal to flow through the first tundish nozzle 20a and for operating the second stopper 400b for controlling a flow of liquid metal through the second tundish nozzle 20b during decoupling and replacement of the first submerged nozzle 10a. Similarly, the controller is further configured for1814_212 operating the second stopper 400b for blocking liquid metal to flow through the second tundish nozzle 20b and for operating the first stopper 400a for controlling a flow of liquid metal through the first tundish nozzle 20a during decoupling and replacement of the second submerged nozzle 10b. In this way, during the replacement of one of the submerged nozzles 10a, 10b, casting may be continued with the other submerged nozzle 10b, 10a.

[0058] The controller may be coupled to one or more level sensors 50a, 50b, 50c (Fig. 11a, b) for receiving signals comprising information related to the liquid metal level in the mould 300. In embodiments, the level sensors 50a, 50b, 50c may be ledge-type of sensors which are mounted to the side of the mould 300 or the sensors 50a, 50b, 50c may be suspended-type of sensors which are suspended over the mould 300 with a sensor support arm. In further embodiments, the level sensor may be a radioactive gamma beam-type sensor installed perpendicular to the mould 300, for example inside cooling jackets.

[0059] In Fig.11 a and Fig.11 b, a top view of two embodiments of a mould 300 are shown wherein three level sensors 50a, 50b, 50c are positioned for measuring the liquid level in the mould 300. In these examples, a first sensor 50a is placed between the first 10 and the second 10b submerged nozzle and a second 50b and third 50c sensor are positioned such that the first 10a and the second 10b submerged nozzle are located between the second 50b and third 50c sensor.

[0060] By providing a three-sensor geometry as illustrated on Fig.11a and Fig.11 b, the distances S1 N1 , S2N1 between the first nozzle 10a and the first 50a and second 50b sensor, and the distances S1 N2, S3N2 between the second nozzle 10b and the first 50a and third 50c sensor may be maximized.

[0061] For embodiments comprising three sensors, depending on the geometry of the mould, these distances S1 N1 , S2N1 S1 N2 and S3N2 between sensors 50a, 50b, 50c and submerged nozzles 10a, 10b, as illustrated on Fig.11 a and Fig.11 b, are preferably between 200 mm and 400 mm. The distances between sensors 50a, 50b, 50c and submerged nozzles 10a, 10b are measured along the long side 303, 304 of the mould 300 between a central axis C1 , C2 of the submerged nozzle 10a, 10b and a centre point of the sensor 50a, 50b, 50c.1814_213

[0062] In some embodiments, during nominal operation of the continuous casting system, the two stoppers 400a, 400b may be actively controlled, i.e. both their positions depend on one or more signals received from the sensors 50a, 50b, 50c. The signal received by the two stoppers 400a, 400b may be a same signal based on information obtained from all three sensors 50a, 50b, 50c, i.e. the signal reflects an average level in the mould 300. Alternatively, the two stoppers 400a, 400b may be controlled differently from each other and each receive a different control signal, for example one stopper 400a receives a signal based on information from the first and second sensor 50a, 50b and the second stopper 400b receives a signal based on the first and third sensor 50b, 50c.

[0063] In other embodiments, the first stopper 400a may be actively controlled and the second stopper 400b may be set to a fixed pre-defined position, and hence the position of the second stopper 400b does not depend on the information received from the sensors 50a, 50b, 50c.

[0064] In embodiments, before replacing a submerged nozzle 10a, 10b, the nominal casting speed may be reduced. Especially, if the nominal casting speed is higher than the supply rate of a single submerged nozzle 10a, 10b, the casting speed is to be reduced. The reduced casting speed may for example be between 25% and 75% of the nominal casting speed, preferably between 35% and 60% of the nominal casting speed. For high-throughput continuous casting systems, the nominal casting speed may for example be larger than 7 meter per minute. Such a high nominal casting speed may be achieved by simultaneously supplying liquid metal through the two submerged nozzles 10a, 10b. The two submerged nozzles 10a, 10bmay be identical and hence be capable of supplying half of the casting speed. Therefore, when replacing one of the submerged nozzles 10a, 10b, the installation downstream of the mould 300 is generally slowed down to allow for a casting speed that is about half of the nominal casting speed, and which can be supplied by a single submerged nozzle.

[0065] The nozzle replacement systems comprise two main components, namely a nozzle coupling mechanism 30 and gripper arm 38 that cooperate for removing a submerged nozzle and inserting a replacement nozzle. The components of the nozzle replacement system are further discussed in more detail here below.14Coupling mechanism

[0066] In embodiments, for each of the submerged nozzles 10a, 10b a coupling mechanism 30 is provided. The coupling mechanisms may be attached to a bottom side of the tundish.

[0067] A first coupling mechanism 30 is configured for coupling the first submerged nozzle 10a to the first tundish nozzle 20a so as to keep the entrance side 13 of the first submerged nozzle 10a sealingly coupled to the output side 24 of the first tundish nozzle 20a while supplying liquid metal to the mould 300. Similarly, a second coupling mechanism 30 is configured for coupling the second submerged nozzle 10b to the second tundish nozzle 20b so as to keep the entrance side 13 of the second submerged nozzle 10b sealingly coupled to the output side of the second tundish nozzle 20b while supplying liquid metal to the mould 300.

[0068] In embodiments, the output side 24 of the tundish nozzle 20a, 20b comprises a tundish flange 25 which is for example schematically shown on Fig.5a and Fig.5b, which are cross-sectional views of an embodiment of the elements of a nozzle assembly 100 comprising a tundish nozzle 20a and a submerged nozzle 10a. The submerged nozzle 10a, 10b, at its entrance side 13 also comprises a flange, named a nozzle flange 15, which is also illustrated on Fig.5a and Fig.5b. By pushing the surface of the nozzle flange 15 against the surface of the tundish flange 25, a sealed coupling between the tundish nozzle and the submerged nozzle 10a, 10b is obtained.

[0069] The coupling mechanism 30 comprises a means for applying a force to maintain the nozzle flange 15 coupled with the tundish flange 25 during casting and a means for releasing or decoupling the nozzle flange 15 from the tundish flange 25 during a maintenance operation when the submerged nozzle 10a, 10b needs to be replaced.

[0070] In embodiments, the coupling mechanisms 30 comprises a retractable support 35 moveable between a holding position HP and a retracted position RP, and wherein when in the holding position HP the retractable support 35 is holding and pushing the submerged nozzle 10a, 10b against the corresponding tundish nozzle 20a, 20b so as to maintain a sealed coupling between the submerged nozzle 10a, 10b and tundish nozzle 20a, 20b, and15 wherein when in the retracted position RP the retractable support 35 is removed from the submerged nozzle 10a, 10b and the submerged nozzle 10a, 10b may decouple from the tundish nozzle 20a, 20b.

[0071] In embodiments, the first and the second coupling mechanisms 30 are on the same side of a centre plane CP (visible on Fig. 2a and 2b). The centre plane CP is plane transverse, preferably perpendicular, to the first 301 and second 302 short sides of the mould 300. The coupling mechanisms 30 are preferably partly above and partly along one of the long sides 303, 304 of the mould 300.

[0072] In exemplary embodiments, as illustrated for example on Fig.4a, Fig.4b and Fig.6, illustrating a cross-sectional view of parts of a coupling mechanism 30 according to the present disclosure, the retractable support 35 may be rotatable around a rotation axis R for rotating the retractable support 35 between the holding position HP and the retracted position RP. In addition of a rotation, or instead of a rotation, the motion of the retractable support 35 between the holding position HP and the retracted position RP may involve a translation.

[0073] In embodiments, the rotation axis R may be transverse to a first 301 and a second 302 short side of the mould 300, or preferably the rotation axis may be perpendicular to a first and a second short side of the mould. In this way, the space below the tundish 200 located between the submerged nozzles 10a, 10b and the short sides 301 , 302 of the mould 300 may be preserved for moving the submerged nozzles 10a, 10b from and into the mould 300, as further discussed below.

[0074] In embodiments, as further illustrated on Fig.6 and Fig.7, the retractable support 35 may have a fork shape and comprises for example two support fingers 35a, 35b.

[0075] As further illustrated on Fig.6, when the retractable support 35 is in the holding position, the support fingers 35a, 35b are supporting the nozzle flange 15 and thereby support the entire submerged nozzle 10a, 10b. With reference to Fig.6, when the support fingers 35a, 35b are in the holding position HP, the support fingers 35a, 35b are parallel with the Y axis, i.e. the support fingers 35a, 35b are parallel with the short sides 301 , 302 of the mould 300.

[0076] In embodiments, as illustrated in more detail on Fig.7, the coupling mechanism 30 may comprise a toggle mechanism 36 coupled on one end to the1814_216 retractable support 35 and on another end to a cylinder 37. The cylinder 37 may be pneumatically or hydraulically driven for moving the retractable support 35 between the holding and retracted position. In some embodiments, the toggle mechanism 36 is configured such that even if the cylinder does not work anymore, e.g. due to a drop of hydraulic pressure or a power loss in the nozzle replacement system, the retractable support 35 remains in the holding position HP.

[0077] In embodiments, as further illustrated on Fig.7, the coupling mechanism 30 comprises a resilient element 39 configured for spring-loading the retractable support 35 when in the holding position HP. The resilient element 39 may be a torsion bar along the rotation axis R. The resilient element 39 may couple the retractable support 35 to the toggle mechanism 36. Advantageously, this spring-loading allows to accommodate size variation and / or thermal expansion in the coupling between the tundish nozzle 20a, 20b and the submerged nozzle 10a, 10b.

[0078] In embodiments, the coupling mechanism is configured such that when the retractable support 35 is in the holding position HP, the retractable support 35 is maintained in the holding position in case of power loss in the nozzle replacement system. This can for example be realized by stroking the toggle mechanism 36 below its alignment, against a mechanical stop, making the coupling mechanism 36 inversible without activation.Gripper arm

[0079] Each of the nozzle replacement systems further comprises a gripper arm 38 that cooperates with the coupling mechanism 30 for replacing a submerged nozzle 10a, 10b. A first gripper arm is configured for cooperating with the first coupling mechanism and a second gripper arm is configured for cooperating with the second coupling mechanism.

[0080] In embodiments, the first and second gripper arm 38 are not identical but are for instance mirror images from each other. Indeed, as mentioned above, in embodiments as illustrated on Fig.1 , the first 10a and second 10b submerged nozzle, when positioned in the mould 300, may be mirror images from each other, e.g. with respect to a mirror plane P3. Hence, the first gripper arm 38 is adapted1814_217 to grip the first submerged nozzle 10a and the second gripper arm 38 is adapted the grip the second submerged nozzle 10b. In other words, the first gripper arm cannot grip the second submerged nozzle 10b and the second gripper arm cannot grip the first submerged nozzle 10a. This ensures that each of the submerged nozzles 10a, 10b is placed in the right orientation with respect to the mould.

[0081] In embodiments, the gripper arms 38 are operated by a robot. In other embodiments the gripper arms 38 may be operated by a human.

[0082] In embodiments, the first and the second gripper arms are on the same side of the center plane CP. They are preferably partly above and partly along one of the long sides 303, 304. In a preferred embodiment, the first and the second gripper arms are on one side of the center plane CP (for example partly above the first long side 303) and the first and the second coupling mechanisms are on the other side of the center plane CP (for example partly above the second long side 304).

[0083] The gripper arm 38 is configured for gripping the respective submerged nozzle 10a, 10b and for moving the submerged nozzle 10a, 10b out of the mould 300. The gripper arm 38 is also used for introducing a replacement nozzle into the mold.

[0084] In embodiments, an end portion of the gripper arm 38 comprises two gripper fingers 38a, 38b, as schematically illustrated on Fig.6. As further shown on Fig.5a, each of the submerged nozzles comprises two finger receiving locations 34a, 34b configured for receiving the two gripper fingers 38a, 38b of the gripper arm such that the gripper arm may grip the submerged nozzle 10a, 10b by inserting the gripper fingers 38a, 38b into the finger receiving locations 34a, 34b.

[0085] Preferably, the two gripper fingers 38a, 38b are different and are adapted for cooperating with corresponding finger locations 34a, 34b. In embodiments, the two gripper fingers 38a, 38b may for example have a different cross-sectional shape, a different cross-sectional diameter or a different length.

[0086] In embodiments, one of the two receiving locations 34a, 34b may be a hook element for receiving a first gripper finger 38a. For these embodiments, the first gripper finger 38a may also be named axis finger as this gripper finger18 may be used as an axis to rotate the submerged nozzle 10a, 10b. The axis finger preferably has a circular shape. When the first receiving location 34a is a hook element, the second receiving location 34b may for example be a flange portion of the nozzle flange 15 of the submerged nozzle that is adapted for receiving the second gripper finger 38b.

[0087] As illustrated on Fig.6, when the submerged nozzle 10a, 10bis coupled to the corresponding tundish nozzle and the gripper fingers 38a, 38b of the gripper arm 38 are received in the corresponding finger receiving locations 34a, 34b, the gripper arm 38 is located above the retractable support 35 to permit the retractable support 35 to move down. In other words, each nozzle replacement system is configured such that the retractable support 35 of the coupling mechanism 30 is moveable from the holding position HP to the retracted position RP while the gripper arm 38 grips the submerged nozzle. In embodiments, for instance the finger receiving locations 34a, 34b for receiving the gripper fingers 38a, 38b of the gripper arm 38 are configured such that the retractable support 35 of the coupling mechanism is moveable from the holding position HP to the retracted position RP while the two gripper fingers 38a, 38b of the gripper arm are inserted in the corresponding receiving locations 34a, 34b of the submerged nozzle 10a, 10b.

[0088] In embodiments, when the gripper fingers 38a, 38b of the gripper arm are inserted in the corresponding finger receiving locations 34a, 34b, the arm portion 38c of the gripper arm 38 is oriented transverse with respect to the long sides 303, 304 of the mould 300, i.e. transverse to the X-axis. In Fig.6, the arm portion 38c is shown to be parallel with the Y axis, i.e. perpendicular to the X axis.

[0089] As shown on Fig. 6, the retractable support 35 of the coupling system 30 is configured such that when in the holding position, the two support fingers 35a, 35b are parallel with the Y-axis, i.e. parallel with the first 301 and second 302 short side of the mould 300. Further, the gripper arm 38 is configured such that when the two gripper fingers 38a, 38b are inserted into the corresponding finger receiving locations 34a, 34b, the two gripper fingers are also parallel with the first and second short side of the mould. Hence gripper fingers and support fingers are parallel. Such a geometry facilitates the removal and insertion of a19 submerged nozzle from the short sides of the mould by moving the submerged nozzle in a plane parallel with the long sides of the mould.

[0090] In the embodiment shown on Fig.6, the two support fingers 35a, 35b and the two gripper fingers 38a, 38b are pointing in an opposite direction. In other words, the gripper arm 38 is gripping the submerged nozzle from the first long side of the nozzle and the retractable support is holding the nozzle from the second long side of the nozzle.Movement of the gripper arm

[0091] As discussed above, the first gripper arm 38 of the first nozzle replacement system and the second gripper arm 38 of the second nozzle replacement system are configured for respectively gripping the first 10a and gripping the second 10b submerged nozzle and for respectively moving the first and moving the second submerged nozzle out of the mould 300. The gripper arms may also be used for introducing replacement nozzles into the mold.

[0092] Fig.3a to Fig.3f show sequential movement steps of the submerged nozzle 10a when applying the method for removing the submerged nozzle 10a from the mould 300 according to the present disclosure.

[0093] In embodiments, as schematically illustrated on Fig.3a to Fig.3f, the first nozzle replacement system is configured for insertion and extraction of the first submerged nozzle 10a into and from the mould 300 through a first spacing S1 between a bottom side 201 of the tundish and an upper portion 301a of the first short side 301 of the mould 300. Similarly, the second nozzle replacement system is configured for insertion and extraction of the second submerged nozzle 10b into and from the mould 300 through a second spacing S2 between the bottom side 201 of the tundish and an upper portion 302a of the second short side 302 of the mould 300. In other words, insertion and extraction of a submerged nozzle is performed from the same short side of the mould. In Fig .1 , the arrows 11 and I2 schematically indicate a direction for inserting respectively the first and second submerged nozzle and the arrows E1 and E2 schematically indicate a direction of extraction of respectively the first and second submerged nozzle.1814_220

[0094] The gripper arm 38 is either held by a human and manually controlled by the human or the gripper arm 38 is held by a robot and controlled by the robot.

[0095] During replacement of the first submerged nozzle 10a, the first stopper 400a closes the first tundish nozzle 20a.

[0096] As illustrated on Fig.1 and Fig.3a, each of the first 10a and second 10b submerged nozzle is extending along a central axis C1 , C2 from an entrance side to a bottom side of the submerged nozzle, and when coupled to the corresponding tundish nozzle 20a, 20b, each of the nozzle central axes C1 , C2 is parallel with the vertical axis Z transverse to the bottom side 201 of the tundish 200, preferably perpendicular to the bottom side of the tundish. As will be explained below, during the removal procedure of a submerged nozzle, the nozzle will make a rotational movement such that its central axis is rotated towards the closest short side of the mould.

[0097] When a submerged nozzle needs replacement, the gripper fingers 38a, 38b of the gripper arm are first placed in the finger receiving locations 34a, 34b of the submerged nozzle that needs replacement and thereafter, the retractable support 35 is moved from the holding position to the retracted position. When the retractable support 35 is in the retracted position, the robot that holds the gripper arm 38 can start removing the submerged nozzle from the mould.

[0098] For embodiments wherein the gripper arm is held by a robot, the robot is configured to removing the first submerged nozzle from the mould by moving the first submerged nozzle towards the first short side of the mould. Preferably, during this movement of the submerged nozzle towards the first short side of the mould, the first submerged nozzle is rotated such that the central axis C1 of the first submerged nozzle is rotated towards the first short side 301 of the mould and the entrance side 13 of the first submerged nozzle is facing towards a first spacing S1 between the bottom side 201 of the tundish and the mould. More precisely, as illustrated on Fig.1 , the spacing S1 is a spacing between a bottom side 201 of the tundish and an upper portion 301 a of the first short side 301 of the mould 300.

[0099] In embodiments, the movement of the submerged nozzle towards the short side of the mould is performed along the centre plane CP or parallel with the centre plane CP.1814_221

[0100] These movement steps of the submerged nozzle for removing the submerged nozzle out of the mould, are schematically shown on Fig.3a to Fig ,3f . In Fig.3b, the submerged nozzle after being decoupled from the tundish nozzle makes a vertical motion along the vertical axis Z. Thereafter, as shown on Fig.3c and Fig.3d, the submerged nozzle is rotated such that the central axis C1 is moving towards the first short side of the mould 301 . As illustrated on Fig.3e, by further performing a combination of a translation and a rotation of the submerged nozzle, the submerged nozzle is entering the first spacing S1 , from where the submerged nozzle can be removed, as shown in Fig.3f.

[0101] The steps performed for removing the second submerged nozzle from the mould are similar, or more precisely are a mirror image, as those performed for removing the first submerged nozzle. Thereto, the robot is configured for moving the second submerged nozzle towards the second short side of the mould. Preferably, during this movement, the second submerged nozzle is rotated such that the central axis C2 of the second submerged nozzle is rotated towards the second short side 302 of the mould and the entrance side 13 of the second submerged nozzle is facing towards a second spacing S2 between the bottom side 201 of the tundish and the mould. More precisely, as illustrated on Fig.1 , the spacing S2 is a spacing between a bottom side 201 of the tundish and an upper portion 302a of the second short side 302 of the mould 300

[0102] The movement steps to be performed for inserting a replacement nozzle are similar to the steps performed for removing the submerged nozzle, but performed in the reversed order.

[0103] In embodiments, the robot that his holding the gripper arm is configured for coupling a replacement submerged nozzle to the corresponding tundish nozzle by moving the replacement submerged nozzle through respectively the first S1 and second S2 spacings, and by further moving the replacement submerged nozzle in the mould, preferably moving in or parallel with the centre plane CP, and rotating the replacement submerged nozzle until a central axis of the replacement submerged nozzle is aligned with a central axis of the corresponding tundish nozzle and an entrance side of the replacement nozzle is facing the output side 24 of the tundish nozzle. Preferably during a final movement step, a translation motion of the replacement submerged nozzle1814_222 is made along an axis parallel with the vertical axis Z until the entrance side of the replacement nozzle contacts the output side 24 of the tundish nozzle. Thereafter, using the coupling mechanism the replacement nozzle may be coupled to the tundish nozzle by moving the retractable support 35 from the retracted to the holding position.Submerged nozzles, geometry

[0104] The submerged nozzle 10a, 10b for use with the casting system according to the present disclosure, comprises a neck portion 11 and an outlet portion 12 as for example illustrated on Fig.5a and Fig.5b. The outlet portion 12 is the portion of the submerged nozzle that is submerged or at least partly submerged into the liquid metal in the mould.

[0105] The neck portion 11 comprises a nozzle flange 15 for sealingly coupling to a mating tundish flange 25 of a corresponding tundish nozzle so as to form a sealed coupling between the tundish nozzle and the submerged nozzle. The higher surface of the nozzle flange 15 and the lower surface of the tundish flange 25 may have any shape :planar, spherical, oval, conical,...

[0106] The outlet portion 12 comprises an inner bore 14 having a bore entry in fluid connection with the neck portion 11 so as to receive liquid metal supplied through the neck portion, and one or more outlet openings 6a, 6b located on an outer surface 8 of the outlet portion 12 for supplying liquid metal into the mould 300. The inner bore 14 is in fluid connection with the outlet openings such that liquid metal may flow from the neck portion 11 via the inner bore 14 towards the outlet openings 6a, 6b.

[0107] In embodiments, the outlet portion 12 is asymmetric with respect to a crossing plane including the central axis C1 or C2 and parallel to the mirror plane P3. Preferably, the positions of the outlet openings 6a, 6b are different on both sides of this crossing plane. For example, there might be more outlet openings 6a, 6b on one side of the crossing plane than on the other side of the crossing plane.

[0108] With reference to Fig.8a and Fig.8b, two embodiments are shown of a nozzle flange 15. As illustrated with these examples, the nozzle flange 15 preferably has a single-fold rotational symmetry, i.e. the nozzle flange 15 has no1814_223 axis of rotational symmetry. As a consequence, the nozzle flange 15 may only be coupled with the mating tundish flange 25 for one relative orientation of the nozzle flange with respect to the tundish flange and / or the submerged nozzle 10a, 10b may only be handled by the nozzle replacement system in only one direction. Hence, a foolproof connection can be made between the tundish nozzle 20a, 20b and the submerged nozzle 10a, 10b.

[0109] Single-fold rotational symmetry of an object is also commonly named as discrete rotational symmetry of the first order, i.e. for any rotation axis selected, when rotating the object, only after a rotation of 360° the contour shape of the object matches up again with the initial contour shape before starting the rotation. In other words, only after a 360° rotation the contour shape looks the same as at the start of the rotation. Remark that an object of single-fold rotational symmetry may have one or more planes of mirror symmetry.

[0110] Generally, as schematically shown on Fig.5a, Fig.5b and Fig.8a, the nozzle flange 15 has an elongated shape circumferentially delimited by two opposing elongating sides 15a, 15b and two opposing narrow sides 15c, 15d. As illustrated on Fig.5a, a first narrow side is provided with a first finger receiving location 34a, e.g. a hook, and the second narrow side is provided with a second finger receiving location 34b for respectively receiving a first 38a and a second 38b gripper finger of a gripper arm 38. As discussed above, in embodiments, the first finger receiving location 34a is a hook element for receiving the first gripper finger 38a and a second finger receiving location 34b is a flange portion of the nozzle flange 15 adapted for receiving the second gripper finger 38b.

[0111] The global contour shape of the outlet portion 12 of the submerged nozzle and the number, location and shape of the outlet openings is designed to obtain a suitable flow of the liquid metal into the mould. The global contour shape is generally also designed to reduce wave formation during the motion of the submerged nozzle in the mould.Tundish nozzle shutoff

[0112] As discussed above, the liquid metal flow through the nozzle assemblies is controlled by the stoppers 400a, 400b that control the flow through the inlet of the tundish nozzle 20a, 20b.1814_224

[0113] In some embodiments, the casting system is provided with an additional shutoff for stopping liquid metal to flow through the submerged nozzles 10a, 10b, independently of the operation of the stoppers 400a, 400b. This additional shut off may be used as a redundant shut off, as an emergency shut off, and / or to shut off the flow at the end of operation.

[0114] In embodiments, the coupling mechanism 30 is configured to translate the retractable support 35 in a direction parallel to the long sides 303,304 of the mould 300, while maintaining the submerged nozzle 10a, 10b in contact with the tundish nozzle 20a, 20b . To shut off the liquid metal flow, the submerged nozzle 10a, 10b is moved from a casting position (Fig. 10a) to a shut off position (Fig. 10b).

[0115] In Fig.10a and Fig.10b, top views of a coupling mechanism 30 are shown wherein the coupling mechanism 30 is configured for moving the submerged nozzle 10a, 10b from a casting position to a shut off position for shutting of the flow of liquid metal into the mould 300. In this embodiment, the coupling mechanism 30 is provided with a carriage 40 translatable with respect to a fixed frame 45 and configured to translate the retractable support 35, together with the submerged nozzle 10a, 10b, the toggle mechanism 36 and the cylinder 37 driving the toggle mechanism 36, in order to move the submerged nozzle 10a, 10b from the casting position to the shut off position. The casting position corresponds to the position shown on Fig.10a, while the shut off position corresponds to the position shown on Fig.10b. A cylinder 41 may be used to drive the translation motion of the carriage 40. The fixed frame is attached below the tundish.

[0116] The coupling mechanism 30 shown on Fig.10a and Fig.10b, is also shown on Fig.9a and Fig.9b where cross-sectional views in the Z-X plane are illustrating respectively the casting position and the shut off position.

[0117] When the coupling mechanism 30 is moving the the submerged nozzle 10a, 10b to the shut off position, the bottom of the upper nozzle 20a, 20b is closed off by a blind area 16 of the top surface of the nozzle flange 15 of the submerged nozzle 10a, 10b. Indeed, as illustrated on Fig.8, the nozzle flange 15 has a blind area 16 which allows to cover the outlet opening in the output side1814_225Method for replacing a submerged nozzle

[0118] According to a second aspect of the present disclosure, a method for replacing submerged nozzles during continuous casting using a casting system as described above, is provided.

[0119] The method comprises steps of:-deciding to replace the first submerged nozzle 10a,-operating the first stopper 400a for closing off the supply of liquid metal through the first tundish nozzle 20a,-continuing supplying liquid metal through the second tundish nozzle 20b so as to continue supply liquid metal to the mould with the second submerged nozzle 10b,-using a first gripper arm 38 for gripping the first submerged nozzle 10a, -while holding the first submerged nozzle 10a with the first gripper arm 38, decoupling the first submerged nozzle from the first tundish nozzle 20a by moving a retractable support 35 supporting the first submerged nozzle from a holding position HP to a retracted position RP,- using the first gripper arm 38 for removing the first submerged nozzle 10a from the mould 300 by moving the first submerged nozzle towards a first short side 301 of the mould, and extracting the first submerged nozzle from the mould 300 through a first spacing S1 between the bottom side 201 of the tundish and an upper portion 301 a of first short side 301 of the mould,- using the gripper arm 38 for gripping a first replacement submerged nozzle,- bringing the first replacement submerged nozzle into the mould by inserting the first replacement submerged nozzle through the first spacing S1 , and further moving the first replacement submerged nozzle, preferably until a central axis of the first replacement submerged nozzle is aligned with a central axis of the first tundish nozzle and an entrance side 13 of the replacement nozzle is facing the output side 24 of the first tundish nozzle,- coupling the first replacement submerged nozzle to the first tundish nozzle by moving the retractable support 35 from the retracted position to the holding position such that the retractable support is holding and pushing the first replacement submerged nozzle against the first tundish nozzle 20a,1814_226-removing the first gripper arm 38, preferably by extracting the two gripper fingers from the corresponding finger receiving locations, and-operating the first stopper 400a for supplying liquid metal through the first tundish nozzle 20a such that liquid metal is supplied to the mould with the first replacement submerged nozzle.

[0120] In embodiments, the gripper arm is held by a robot and controlled by the robot. In other embodiments, the first gripper arm is held by a human and manually controlled by the human.

[0121] In embodiments, the method further comprises optional steps of: -replacing the second submerged nozzle 10b with a second replacement submerged nozzle by performing steps of: operating the second stopper 400b for closing off the supply of liquid metal through the second tundish nozzle 20b, and using a second gripper arm 38 for replacing the second submerged nozzle using the same steps as for replacing the first submerged nozzle and wherein the second submerged nozzle is moved towards the second short side 302 of the mould and extracted from the mould through a second spacing S2 between the bottom side 201 of the tundish and an upper portion 302a of the second short side 302 of the mould, and wherein the second replacement submerged nozzle is brought into the mould by inserting the second replacement submerged nozzle through the second spacing S2, and when the second replacement submerged nozzle is coupled to the second tundish nozzle 20b then operating the second stopper 400b for supplying liquid metal through the second tundish nozzle 20b such that liquid metal is supplied to the mould with the second replacement submerged nozzle.

[0122] In embodiments, before starting the replacement of the submerged nozzle, the method comprises an optional step of: - reducing the nominal casting speed of the continuous casting system to a reduced casting speed, wherein the reduced casting speed is between 25% and 75% of the nominal casting speed, preferably between 35% and 60% of the nominal casting speed,

[0123] In embodiments, after having replaced a submerged nozzle with a replacement submerged nozzle, the method further comprises an optional step of increasing the casting speed from the reduced casting speed to the nominal casting speed.1814_227

[0124] In embodiments, deciding to replace the first submerged nozzle 10a may be triggered by detecting a possible clogging in the first submerged nozzle 10a, by a time period elapsed since starting operation of the first submerged nozzle, or by any other suitable reason for replacing the first submerged nozzle.

[0125] In embodiments wherein the first gripper arm 38 comprises two gripper fingers, gripping the first submerged nozzle 10a comprises inserting the two gripper fingers in two corresponding finger receiving locations provided on the submerged nozzle and gripping the first replacement nozzle comprises inserting the two gripper fingers of the gripping arm 38 in two corresponding finger receiving locations provided on the first replacement submerged nozzle.

[0126] In embodiments, the movement of the submerged nozzle during the removal out of the mould is performed in the centre plane CP or parallel with the centre plane. As mentioned above, the centre plane CP is a plane transverse, preferably perpendicular, to the first 301 and second 302 short sides of the mould.

[0127] During the removal of the first submerged nozzle 10a from the mould 300 by moving the first submerged nozzle towards a first short side 301 of the mould, the method comprises a substep of rotating the first submerged nozzle such that a central axis C1 of the first submerged nozzle is rotating towards the first short side 301 of the mould and the entrance side 13 of the first submerged nozzle is facing towards the first spacing S1. Similarly, for the removal of the second submerged nozzle 10b, the method may comprise a substep of rotating the second submerged nozzle such that a central axis C2 of the second submerged nozzle is rotating towards the second short side 302 of the mould and the entrance side 13 of the second submerged nozzle is facing towards the second spacing S2.

[0128] In embodiments, the moving of the first replacement submerged nozzle until a central axis of the first replacement submerged nozzle is aligned with a central axis of the first tundish nozzle and an entrance side 13 of the replacement nozzle is facing the output side 24 of the first tundish nozzle comprises a step of: rotating the first replacement submerged nozzle.

[0129] The present disclosure has been described in terms of specific embodiments, which are illustrative of the disclosure and not to be construed as1814_228 limiting. It will be appreciated by persons skilled in the art that the present disclosure is not limited by what has been particularly shown and / or described and that alternatives or modified embodiments could be developed in the light of the overall teaching of this disclosure. The drawings described are only schematic and are non-limiting.

[0130] Use of the verb "to comprise", as well as the respective conjugations, does not exclude the presence of elements other than those stated. Use of the article "a", "an" or "the" preceding an element does not exclude the presence of a plurality of such elements.

[0131] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner.

[0132] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiments is included in one or more embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one ordinary skill in the art from this disclosure, in one or more embodiments.Reference numbers1814_230

Claims

Claims1. A casting system (600) for continuous casting comprising a tundish (200), a mould (300), a first (20a) and a second (20b) tundish nozzle configured for supplying liquid metal through a bottom side (201) of the tundish, a first stopper (400a) for controlling liquid metal flow through the first tundish nozzle (20a), a second stopper (400b) for controlling liquid metal flow through the second tundish nozzle (20b), a first submerged nozzle (10a) coupled to said first tundish nozzle (20a), and a second submerged nozzle (10b) coupled to said second tundish nozzle (20b), characterized in that the first (10a) and second (10b) submerged nozzle are removably coupled to respectively the first (20a) and the second (20b) tundish nozzle, and in that the casting system (600) further comprises• a first nozzle replacement system configured for decoupling the first submerged nozzle (10a) from the first tundish nozzle (20a) and replacing the first submerged nozzle (10a) while the second submerged nozzle (10b) is supplying liquid metal into the mould (300), and,• a second nozzle replacement system configured for decoupling the second submerged nozzle (10b) from the second tundish nozzle (20b) and replacing the second submerged nozzle (10b) while the first submerged nozzle (10a) is supplying liquid metal into the mould (300).

2. The casting system according to claim 1 , wherein the first nozzle replacement system comprises a first coupling mechanism (30) configured for coupling the first submerged nozzle (10a) to the first tundish nozzle (20a) and the second nozzle replacement system comprises a second coupling mechanism (30) for coupling the second submerged nozzle (10b) to the second tundish nozzle (20b), and wherein each of the first and second coupling mechanisms (30) comprises a retractable support (35) moveable between a holding position (HP) and a retracted position (RP), and wherein when in the holding position (HP), the retractable support (35) is holding the submerged nozzle (10a, 10b) against the corresponding tundish nozzle (20a, 20b) so as to maintain a sealed coupling between thesubmerged nozzle (10a, 10b) and tundish nozzle (20a, 20b) , and wherein when in the retracted position (RP), the retractable support (35) is removed from the submerged nozzle (10a, 10b) and the submerged nozzle (10a, 10b) becomes decoupled from the tundish nozzle (20a, 20b) , preferably wherein said retractable support (35) comprises two support fingers (35a, 35b) configured for supporting the submerged nozzle (10a, 10b) when in the holding position (HP), preferably wherein each of the coupling mechanisms (30) is coupled to the bottom side (201) of the tundish.

3. The casting system according to claim 2, wherein said retractable support (35) is rotatable around a rotation axis (R) for rotating the retractable support (35) between the holding position (HP) and the retracted position (RP), preferably wherein said rotation axis (R) is transverse to a first (301) and a second (302) short side of the mould (300), more preferably wherein said rotation axis is perpendicular to a first and a second short side of the mould.

4. The casting system according to claim 2 or 3, wherein for each of the first and second nozzle replacement system, the coupling mechanism (30) is configured such that when the retractable support (35) is in the holding position, the retractable support (35) is maintained in the holding position in case of power loss in the nozzle replacement system.

5. The casting system according to any of preceding claims, wherein each of the first and second nozzle replacement system comprises a resilient element (39) configured for spring-loading the respective submerged nozzle (10a, 10b) against the respective tundish nozzle (20a, 20b) .

6. The casting system according to any of preceding claims, wherein the first nozzle replacement system comprises a first gripper arm (38) configured for gripping the first submerged nozzle (10a) and moving it out of the mould (300), and / or for introducing a replacement submerged nozzle for the first submerged nozzle (10a) into the mould (300), and wherein the second nozzle replacement system comprises a second gripper arm (38)configured for gripping the second submerged nozzle (10b) and moving it out of the mould (300), and / or for introducing a replacement submerged nozzle for the second submerged nozzle (10b) into the mould (300), preferably wherein each nozzle replacement system is configured such that the retractable support (35) of the coupling mechanism (30) is moveable from the holding position (HP) to the retracted position (RP) while the respective submerged nozzle (10a, 10b) is held by the respective gripper arm (38).

7. The casting system according to claim 6, wherein the gripper arm (38) of each of the nozzle replacement systems comprises an end portion having two gripper fingers (38a, 38b) and wherein each of the submerged nozzles (10a, 10b) comprises two corresponding finger receiving locations (34a, 34b) configured for receiving the two gripper fingers (38a, 38b) of the respective gripper arm (38), preferably wherein a first finger receiving location (34a) is a hook element for receiving a first gripper finger (38a) and a second finger receiving location (34b) is a flange portion of the submerged nozzle adapted for receiving a second gripper finger (38b) of the two gripper fingers (38a, 38b).

8. The casting system according to claim 7, wherein each of the nozzle replacement systems is configured such that when the coupling mechanism is in the holding position and the two gripper fingers (38a, 38b) of the gripper arm (38) are inserted into the corresponding finger receiving locations (34a, 34b) of the respective submerged nozzle, the two support fingers (35a, 35b) of the coupling mechanism (30) are parallel with the two gripper fingers (38a, 38b) of the gripper arm (38), preferably wherein the two support fingers (35a, 35b) and the two gripper fingers (38a, 38b) are pointing in an opposite direction, preferably wherein two support fingers (35a, 35b) and the two gripper fingers (38a, 38b) are oriented parallel with a first (301 ) and second (302) short side of the mould (300).

9. The casting system according to any of previous claims, wherein said mould (300) comprises a first long side (303), a second long side (304) opposite the first long side (303), a first short side (301) and a second short side (302) opposite the first short side (301), and wherein the first nozzle replacement system is configured for insertion and extraction of the first submerged nozzle (10a) into and from the mould (300) through a first spacing (S1) between the bottom side (201 ) of the tundish (200) and an upper portion (301 a) of the first short side (301 ) of the mould (300), and the second nozzle replacement system is configured for insertion and extraction of the second submerged nozzle (10b) into and from the mould (300) through a second spacing (S2) between the bottom side (201) of the tundish (200) and an upper portion (302a) of the second short side (302) of the mould (300).

10. The casting system according to any of previous claims, wherein the mould (300) has a mould width (MW) smaller than 200 mm, preferably smaller than 160 mm, more preferably smaller than 140 mm and / or a mould length (ML) smaller than 2500 mm, preferably smaller than 1500 mm, more preferably smaller than 1000 mm, preferably wherein said mould width (MW) is measured between a first (303) and second (304) long side of the mould and said mould length (ML) is measured between a first (301 ) and second (302) short side of the mould (300).11 . The casting system according to any of previous claims, comprising a controller for controlling the first (400a) and second (400b) stopper, and wherein the controller is configured for a) operating the first stopper (400a) for blocking liquid metal to flow through the first tundish nozzle (20a) and operating the second stopper (400b) for controlling a flow of liquid metal through the second tundish nozzle (20b) during decoupling and replacement of the first submerged nozzle (10a), and b) operating the second stopper (400b) for blocking liquid metal to flow through the second tundish nozzle (20b) and operating the first stopper(400a) for controlling a flow of liquid metal through the first tundish nozzle (20a) during decoupling and replacement of the second submerged nozzle (10b).

12. The casting system according to any of previous claims, comprising at least three sensors (50a, 50b, 50c) for measuring a level of liquid metal in the mould (300), preferably wherein a first sensor (50a) is located in between the first (10a) and the second (10b) submerged nozzle and wherein a second (50b) and third (50c) sensor are located such that the first and the second submerged nozzle (10a, 10b) are located between said second (50b) and third (50c) sensor.

13. The casting system according to any of previous claims, wherein each submerged nozzle (10a, 10b) comprises a) a neck portion (11 ) comprising a nozzle flange (15) for sealingly coupling to a mating tundish flange (25) of a corresponding tundish nozzle (20a, 20b) so as to form a sealed coupling between the tundish nozzle (20a, 20b) and the submerged nozzle (10a, 10b), and b) an outlet portion (12) comprising an inner bore (14) having a bore entry in fluid connection with the neck portion (11) so as to receive liquid metal supplied through the neck portion (11 ), and one or more outlet openings (6a, 6b) located on an outer surface (8) of the outlet portion (12) for supplying liquid metal into the mould (300), preferably wherein said nozzle flange (15) has a single-fold rotational symmetry such that the nozzle flange (15) can only be coupled with the mating tundish flange (25) for one relative orientation of the nozzle flange (15) with respect to the tundish flange (25).

14. The casting system according to claim 13, wherein said nozzle flange (15) has an elongated shape circumferentially delimited by two opposing elongating sides (15a, 15b) and two opposing narrow sides (15c, 15d), and wherein a first narrow side (15c) is provided with a first finger receiving location (34a) and the second narrow side (15d) is provided with a secondfinger receiving location (34b) for respectively receiving a first (38a) and a second (38b) gripper finger of a gripper arm (38), preferably wherein the first finger receiving location (34a) is a hook element for receiving the first gripper finger (38a) and a second finger receiving location (34b) is a flange portion of the nozzle flange (15) adapted for receiving the second gripper finger (38b).

15. A method for replacing submerged nozzles during continuous casting of a metallic product using a casting system according to any of claims 1 to 14, the method comprising:-deciding to replace the first submerged nozzle (1 Oa), preferably wherein said deciding may be triggered by detecting possible clogging in the first submerged nozzle (10a) or by a time period elapsed since starting operation of the first submerged nozzle (10a),-optionally reducing the nominal casting speed of the continuous casting system to a reduced casting speed, wherein the reduced casting speed is between 25% and 75% of the nominal casting speed, preferably between 35% and 60% of the nominal casting speed,-operating the first stopper (400a) for closing off the supply of liquid metal through the first tundish nozzle (20a),-continuing supplying liquid metal through the second tundish nozzle (20b) so as to continue supply liquid metal to the mould (300) with the second submerged nozzle (10b),-using a first gripper arm (38) for gripping the first submerged nozzle (10a), preferably wherein the first gripper arm (38) comprises two gripper fingers (38a, 38b), and inserting the two gripper fingers (38a, 38b) in two corresponding finger receiving locations (34a, 34b) provided on the first submerged nozzle (10a), preferably wherein the first gripper arm (38) is either held by a human and manually controlled by the human or the gripper arm (38) is held by a robot and controlled by the robot,-while holding the first submerged nozzle (10a) with the first gripper arm (38), decoupling the first submerged nozzle (10a) from the first tundish nozzle (20a) by moving a retractable support (35) supporting the firstsubmerged nozzle (10a) from a holding position (HP) to a retracted position (RP),- using the first gripper arm (38) for removing the first submerged nozzle (10a) from the mould (300) by moving the first submerged nozzle (10a) towards a first short side (301) of the mould (300), and extracting the first submerged nozzle from the mould (300) through a first spacing (S1) between the bottom side (201) of the tundish (200) and an upper portion (301 a) of the first short side (301 ) the mould (300), preferably wherein said moving the first submerged nozzle (10a) towards a first short side (301) of the mould comprises a step of rotating the first submerged nozzle (10a) such that a central axis (C1) of the first submerged nozzle (10a) is rotating towards the first short side (301) of the mould (300) and an entrance side (13) of the first submerged nozzle (10a) is facing towards the first spacing (S1),-using the gripper arm (38) for gripping a first replacement submerged nozzle, preferably inserting the two gripper fingers (38a, 38b) of the gripping arm (38) in two corresponding finger receiving locations (34a, 34b) provided on the first replacement submerged nozzle (10a),-bringing the first replacement submerged nozzle into the mould (300) by inserting the first replacement submerged nozzle through said first spacing (S1 ), and further moving the first replacement submerged nozzle, preferably until an entrance side of the first replacement nozzle is facing an output side (24) of the first tundish nozzle,- coupling the first replacement submerged nozzle to the first tundish nozzle (20a) by moving the retractable support (35) from the retracted position (RP) to the holding position (HP) such that the retractable support (35) is holding and pushing the first replacement submerged nozzle against the first tundish nozzle (20a),-removing the first gripper arm (38), preferably by extracting the two gripper fingers (38a, 38b) from the corresponding finger receiving locations (34a, 34b),-operating the first stopper (400a) for supplying liquid metal through the first tundish nozzle (20a) such that liquid metal is supplied to the mould with the first replacement submerged nozzle,-optionally replacing the second submerged nozzle (10b) with a second replacement submerged nozzle by performing steps of: operating the second stopper (400b) for closing off the supply of liquid metal through the second tundish nozzle (20b), and using a second gripper arm (38) for replacing the second submerged nozzle (10b) using the same steps as for replacing the first submerged nozzle (10a), and wherein the second submerged nozzle (10b) is moved towards the second short side (302) of the mould (300)and extracted from the mould through a second spacing (S2) between the bottom side (201) of the tundish (200) and an upper portion (302a) of the second short side (302) the mould (300), and wherein the second replacement submerged nozzle is brought into the mould (300) by inserting the second replacement submerged nozzle through said second spacing (S2), and when the second replacement submerged nozzle is coupled to the second tundish nozzle (20b), then operating the second stopper (400b) for supplying liquid metal through the second tundish nozzle (20b) such that liquid metal is supplied to the mould (300) with the second replacement submerged nozzle,- optionally increasing the casting speed from the reduced casting speed to the nominal casting speed.

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