WO2019244192A1 - Installation et procédé de fabrication d'une bande métallique laminée à chaud - Google Patents

Installation et procédé de fabrication d'une bande métallique laminée à chaud Download PDF

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Publication number
WO2019244192A1
WO2019244192A1 PCT/IT2019/050151 IT2019050151W WO2019244192A1 WO 2019244192 A1 WO2019244192 A1 WO 2019244192A1 IT 2019050151 W IT2019050151 W IT 2019050151W WO 2019244192 A1 WO2019244192 A1 WO 2019244192A1
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WO
WIPO (PCT)
Prior art keywords
slab
rolling
thickness
comprised
plant
Prior art date
Application number
PCT/IT2019/050151
Other languages
English (en)
Inventor
Giampietro Benedetti
Paolo Bobig
Andrea Carboni
Original Assignee
Danieli & C. Officine Meccaniche S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Danieli & C. Officine Meccaniche S.P.A. filed Critical Danieli & C. Officine Meccaniche S.P.A.
Publication of WO2019244192A1 publication Critical patent/WO2019244192A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/14—Plants for continuous casting
    • B22D11/142—Plants for continuous casting for curved casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting

Definitions

  • the field of application of the present invention is the steel industry and the production of semifinished metal products, more particularly the production of metal strip, for example made of steel, hot-rolled by means of a rolling line located downstream of a continuous casting machine.
  • Document US-B-5.307.864 describes a steel strip production plant comprising a hot-rolling line located downstream of a continuous casting machine provided, in turn, with a mold equipped with a crystallizer.
  • the casting machine of the vertical-curved type, also comprises guide devices to divert the metal product from the vertical direction, at exit from the crystallizer, to the horizontal direction following a curved path, with high radii of curvature.
  • This casting plant comprises, downstream of the guide devices, a roughing stand to roll the cast metal product, a shear to shear the cast slab and a heating device to heat the cast slab before it is wound into a winding/unwinding device from which it is then unwound to be fed to the hot-rolling line provided downstream.
  • a further heating unit is interposed between the finishing rolling stands of the hot-rolling line, to restore the temperature of the slab being rolled. After which a winding device, or winding reel, is provided.
  • Also known from document US-B-7.025.118 is a vertical casting machine and method provided to maintain the position of the kissing point, that is, the point of complete solidification of the metal product, always in a same position along the containing devices, as the casting speed, the type of steel and the secondary cooling modes vary. This allows, as now consolidated in the state of the art, to maintain the thickness of the cast product constant at exit from the continuous casting machine.
  • the thickness of the slab is varied so as to maintain the growth of solidification skin constant over time.
  • This casting machine is rigid since it is not able to cast slabs of the ultra-thin type and, above all, it is not able to regulate, with a high degree of variability, the final thickness of the cast slabs and therefore regulate as a consequence the productivity of the plant.
  • One purpose of the present invention is to provide a plant and to perfect the corresponding method for the production of a hot-rolled metal strip which, by overcoming the disadvantages of the plants and methods of prior state of the art, are very flexible and particularly suitable for medium-low productions, that is, up to a maximum of 1.1 Mton/year, preferably to obtain an annual production of less than 800,000 ton/year, and easily variable, for example between about 400,000 ton/year and about 800,000 ton/year.
  • Another purpose of the present invention is to provide a plant for producing a hot-rolled metal strip which has very small overall sizes, for example with a length of less than 130m, consequently reducing the investment and maintenance costs of the buildings connected thereto.
  • Another purpose of the present invention is to provide a plant and to perfect the corresponding method for the production of a hot-rolled metal strip which can easily vary the thickness of the cast slab in relation to the final thickness of the strip and optimize the productivity of the plant with the lowest possible number of stands, maintaining the maximum casting speed in relation to the steel grade.
  • the Applicant has devised, tested and embodied the apparatus and perfected the method according to present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.
  • a plant for the production of a hot- rolled metal strip according to the present invention comprises:
  • a continuous casting machine having a substantially vertical casting axis and having a containing length less than or equal to 6m, the continuous casting machine being configured to cast a metal product with a casting speed comprised between about 3.6 m/min and about 6 m/min, and comprising a mold, with a corresponding crystallizer and a roll-type pre-rolling device configured to obtain a liquid core pre-rolling and to supply at exit an ultra-thin slab having first thicknesses selectively settable.
  • the roll-type pre-rolling device has a length, measured in a direction parallel to the casting axis, less than or equal to 5m, and is configured to determine the complete solidification of the cast product at a solidification point contained in the roll-type pre-rolling device and selectively located in a zone comprised between the exit end of the latter and a distance from the exit end of at least 80% of the length of the roll-type pre-rolling device, toward the entrance end of the latter.
  • the containing length is defined as the distance between the entrance end of the crystallizer and the exit end of the roller unit.
  • the plant also comprises downstream of the roll-type pre-rolling device a drawing unit configured to draw the slab and send it downstream.
  • the plant After a curved segment of the continuous casting machine, the plant also comprises, disposed along a substantially horizontal rolling plane:
  • - at least one roughing stand configured to transform the slab into a roughed slab, also called X-bar, or transfer bar, having a second thickness
  • - first shearing means configured to shear the roughed slab to size
  • - induction heating means configured to heat the roughed slab to a determinate rolling temperature, or to keep it at a determinate rolling temperature
  • a winding/unwinding device configured to selectively wind/unwind the roughed slab and to keep it at the rolling temperature
  • a winding reel configured to wind the metal strip.
  • the roll-type pre-rolling device is configured to be adjustable so that the first thicknesses of the slab are comprised between about 28mm and about 48mm.
  • the roughing stand and the continuous finishing rolling train are configured to be adjustable so that the final thickness of the metal strip is comprised between about 0.8mm and about 12mm.
  • an hourly production of the casting machine comprised between about 80 ton/h and about 160 ton/h, corresponding to about 400,000 ton/year and, respectively, to about 800,000 ton/year.
  • the cast product exiting the crystallizer has a determinate thickness comprised between 48mm and 56mm, preferably comprised between 50mm and 54mm and still has a liquid core inside it.
  • the crystallizer is defined by at least two plates facing each other and distanced from each other, by a distance, at least in the terminal segment, equal to the thickness of the cast product.
  • the size of the crystallizer can be substantially the same for each production condition set, for example linked to the thickness of the strip to be obtained, to the casting speed and to productivity.
  • a first descaling device is disposed immediately before the roughing stand that has the function of removing the scale from the surface of the slab.
  • a second descaling device is disposed between the second shearing means and the continuous finishing rolling train.
  • the continuous finishing rolling train comprises a number of finishing stands comprised between two and five.
  • the roughing stand is directly connected to the casting machine, the term“directly connected” meaning that there is no break in continuity between the cast product exiting the crystallizer and the ultra-thin slab that enters the roughing stand.
  • the slab is not cut between the casting machine and the roughing stand, so these two machines work in endless mode with each other.
  • the roughing stand is configured so that the second thickness of the roughed slab is comprised between about 8mm and about 25mm.
  • the size of the thickness of the roughed slab allows to wind the rough slab in the winding/unwinding device.
  • Embodiments of the present invention also concern a method for the production of a hot-rolled metal strip, which comprises:
  • the pre-rolling step providing the complete solidification of the cast product at a solidification point contained in the roll-type pre-rolling device and selectively located in a zone comprised between the exit end of the latter and a distance from the exit end of roll-type pre-rolling device of at least 80% of the length of the roll-type pre-rolling device.
  • the method for the production of a hot-rolled metal strip comprises:
  • a step of drawing the slab with a drawing unit that can also comprise a step of reducing the thickness of the solidified slab
  • a heating/temperature maintenance step to heat the roughed slab to a determinate rolling temperature, or to keep it at a determinate rolling temperature
  • the drawing unit can consist of a number of pairs of drawing rolls comprised between one and three, in which the rolls of each pair are configured to perform a liquid core reduction of the slab with a decrease in the thickness comprised between 2mm and 7mm.
  • the liquid core pre-rolling step reduces the thickness of the cast product exiting the crystallizer so that the first thicknesses are selectively settable and comprised between about 28mm and about 48mm.
  • the roughing step and the continuous finishing rolling step occur so that the final thickness of the metal strip is comprised between about 0.8mm and about 12mm.
  • the method provides that as a function of the casting speed, correlated to the first selectively set thicknesses of the slab, it is possible to obtain an hourly production of the casting machine comprised between about 80 ton/h and about 160 ton/h, corresponding to about 400,000 ton/year and, respectively, to about 800,000 ton/year.
  • the productivity of the casting machine can reach a maximum of 1.1 Mton/year.
  • the method provides that the cast product exiting the crystallizer has a thickness comprised between 48mm and 56mm, preferably comprised between 50mm and 54mm.
  • the method provides that before the roughing step, a step of drawing the slab is performed. This allows to facilitate the introduction and the feed of the slab through the subsequent roughing stand.
  • the method provides that immediately before the roughing step, a first descaling step is performed to remove the layer of scale on the slab.
  • the method provides that between the second shearing step and the continuous finishing rolling step, a second descaling step is performed on the roughed slab.
  • the method provides that the roughing step reduces the thickness of the slab so that the second thickness of the roughed slab is comprised between about 8mm and about 25mm.
  • - fig. 1 is a schematic lateral view of a plant for the production of a hot-rolled metal strip according to the present invention
  • - fig. 2 is a schematic section of a continuous casting machine of the plant of fig. 1 , on an enlarged scale, in a first example of the functioning thereof;
  • - fig. 3 is a schematic section of the continuous casting machine of fig. 2 in a second example of the functioning thereof;
  • - fig. 4 is a schematic section of the continuous casting machine of fig. 2 in a third example of the functioning thereof;
  • - fig. 5 is a schematic section of the continuous casting machine of fig. 2 in a fourth example of the functioning thereof;
  • a plant 10 for the production of a hot-rolled metal strip 11 for example made of steel, according to the present invention, comprises a continuous casting machine 12, which in turn comprises a mold 13 provided with a crystallizer 14 (figs. 2-5), and a roll-type pre-rolling device, also referred to hereafter as containing roller unit or, more simply, roller unit 15 (figs. 1-5), disposed along a substantially vertical casting axis X.
  • a continuous casting machine 12 which in turn comprises a mold 13 provided with a crystallizer 14 (figs. 2-5), and a roll-type pre-rolling device, also referred to hereafter as containing roller unit or, more simply, roller unit 15 (figs. 1-5), disposed along a substantially vertical casting axis X.
  • the roll-type pre-rolling device 15 is configured to perform a liquid core reduction in the thickness of the metal product exiting the mold 13, to provide a selectively set first thickness Sb of the slab B.
  • a curved segment 16 of the casting machine is provided downstream of the roller unit 15 in which the cast product is diverted, along a curved path, from its substantially vertical condition to its substantially horizontal condition.
  • the height of the mold 13 is, for example, comprised between 1000mm and 1200mm.
  • the liquid metal is cast into the crystallizer 14 to maintain a filling level in the latter, also called meniscus M, which is substantially constant during casting.
  • the level of the meniscus M is located lower than the entrance end of the crystallizer 14 at a distance comprised between 50mm andlOO mm, preferably between 80mm and 85mm.
  • the roller unit 15 can have a length LR, measured in a direction parallel to the casting axis X, less than or equal to 5m, preferably less than or equal to 4.2m.
  • the roller unit 15 can comprise a plurality of pairs of segments 30a, 30b, 30c, 30d, 31a, 31b, 31c, 3 Id as described below, disposed on opposite sides with respect to the casting axis X and each of which is provided with a plurality of rolls 32 to contain and/or compress the metal product being cast.
  • Each pair provides that a segment 30a, 30b, 30c, 30d, faces a corresponding segment 31a, 31b, 31c, 3 Id.
  • the number of pairs of segments 30a, 30b, 30c, 3 Od, 31a, 31b, 31c, 3 Id is comprised between four and eight.
  • the cast product has a solidified external shell having the function of containing the liquid metal still present therein.
  • the roller unit 15 is configured to perform a compression on the cast product (fig. 2) exiting the crystallizer 14, that is, to reduce the thickness of the cast product, while its internal core is still liquid, and to give it the thickness Sb, as will be described in detail below.
  • the roller unit 15 can be associated with cooling devices, not shown, also called secondary cooling, and configured to cool the external surfaces of the slab and to determine its further solidification.
  • the cooling devices can comprise nozzles to deliver nebulized water or air- mist.
  • the closing of the two half-skins which form in the crystallizer occurs inside the roller unit 15 and their point of union, which determines the complete solidification of the cast product, is referred to as the Kissing Point (KP).
  • KP Kissing Point
  • the KP can also be seen as the terminal vertex of the liquid cone which originates from the meniscus M in the crystallizer 14.
  • the roller unit 15 is configured to determine the complete solidification of the cast product in a solidification point contained in the roller unit 15 and selectively located in a zone comprised between the exit end of the latter and a distance from the exit end of at least 80% of the length LR of the roller unit 15, that is, toward and in direct proximity to the entrance end of the roller unit 15.
  • This solidification point defines the kissing point KP as above.
  • the invention makes it possible to use at least 80% of the length LR of the roller unit 15 to close the liquid cone and obtain corresponding slab thicknesses at exit from the roller unit.
  • This aspect can be explained in another way using a quantity that is characteristic of the casting machine which is the solidification length.
  • the solidification length LS is defined as the distance between the level of the meniscus M of the molten material present in the crystallizer 14 and the position of the kissing point KP, that is, of the solidification point, inside the roller unit 15.
  • the casting machine 12 is configured to have a solidification length LS selectively settable to a value chosen between about 1.3m and about 5.9m, preferably between about 1.3m and 5.1m.
  • the setting of the positioning of the kissing point inside the roller unit 15 is performed by intervening on at least one of the following parameters: casting speed, secondary cooling intensity, and intensity of the reduction of the liquid core thickness by adjusting the segments of the roller unit 15, as described below.
  • the casting machine 12 has a containing length LC, which is defined as the distance between the entrance end of the crystallizer 14, that is, the end through which the molten material is introduced, and the exit end of the roller unit 15, that is, the end from which the ultra-thin slab B exits.
  • the containing length LC is less than or equal to about 6m, preferably less than or equal to about 5.2m.
  • the containing length LC is much smaller than known embodiments.
  • the containing length LC is a fixed value of the casting machine 12, set for example in the design step of the casting machine itself.
  • a small containing length LC allows to reduce the height, and therefore the bulk, of the casting machine 12, thus also reducing the size of the production plant.
  • the cast product exiting the crystallizer 14 has a determinate initial thickness Sc (fig. 2) which is comprised between 48mm and 56mm, preferably between 50mm and 54mm, in this case, of about 52mm.
  • the crystallizer 14 is defined by at least two plates facing each other and distanced, at least in the terminal segment, by the determinate initial thickness Sc as above.
  • the same crystallizer 14 can be used for the entire range of strip thicknesses and productivity defined in the introduction thanks to the flexibility of the containing roller unit, thus allowing to simplify the management of the plant.
  • the slab B exiting the roller unit 15, due to a reduction in the thickness obtained by means of the liquid core pre-rolling, can have first thicknesses Sb comprised between about 28mm and about 48mm, so that the slab B is of the ultra-thin type and is completely solidified at exit from the roller unit 15.
  • the radius of curvature R can be comprised between about 1.5m and 2.5m, even more preferably 1.7m and 2.2m.
  • a drawing unit 17 is provided downstream of the roller unit 15 configured to draw the slab B downstream, that is, toward the roughing stand 19.
  • the drawing unit 17 comprises a number of pairs of drawing rolls, comprised between one and six.
  • the rolls of each pair are disposed on opposite sides of the slab to be drawn.
  • the rolls of each pair, or at least one of them, can be associated with movement devices, for example hydraulic cylinders of the known type (not shown), to move the rolls closer to/away from each other and also to determine a predefined compression action on the completely solidified slab B, as described below.
  • the drawing unit 17 can comprise a first drawing device 16a located directly downstream of the roller unit 15, that is, in the vertical segment of the casting machine 12, and a second drawing device 16b located directly downstream of the curved segment 16 of the casting machine 12.
  • the first drawing device l6a and the second drawing device 16b can comprise a number of pairs of rolls comprised between 1 and 3.
  • each single pair of drawing rolls can obtain, when necessary, a compression of an amount comprised between 0.5mm and 1.5mm so as to obtain, overall, a decrease in the thickness comprised between about 2mm and about 7mm.
  • Performing the rolling already during casting entails a further reduction of the thickness of the slab B thus allowing the roughing stand 19 located downstream to reach thinner second thicknesses Sz of the roughed slab Z.
  • the drawing unit 17 is an integral part of the casting machine 12 which, thanks to the rolling action performed by its rolls, can be defined as a“Rolling Caster”.
  • Rolling Caster we mean a casting machine 12 able to perform both the casting of the product and also its rolling, partly with a liquid core and partly with a solid core.
  • first shearing means 20 for example comprising a shear for shearing to size
  • induction heating means or inductor 21, preferably of the modular type
  • - second shearing means 24 for example comprising a shear, to crop the head/tail ends and possibly scrap the roughed slab Z in case of emergency,
  • - cooling means 28 configured to cool the metal strip 11, preferably of the modular type
  • winding reel 29 configured to wind the metal strip 11 into a coil.
  • the roughing stand 19 is configured to reduce the thickness of the slab B in relation to the winding and containing capacity of the winding/unwinding device.
  • the roughed slab Z, or transfer bar, at exit from the roughing stand 19 has a thickness comprised between 8mm and 25mm, preferably between 10mm and 25mm.
  • the first shearing means 20 are configured to shear the roughed slab Z to size to a length equivalent to the weight of a complete coil of metal strip 11 which is wound around the winding reel 29.
  • the induction heating means 21, positioned upstream of the winding/unwinding device 22, are configured to heat the roughed slab Z to a temperature comprised between about 1000°C and about 1200°C, that is, a temperature suitable for the subsequent rolling of the roughed slab, and therefore they allow to restore the temperature of the roughed slab Z which has been dissipated in the roughing stand 19.
  • the winding/unwinding device 22 comprises a first unit 22a and a second unit 22b which alternate with each other in the winding function of the roughed slab Z received from the roughing stand 19, and in the unwinding function of the roughed slab Z, previously wound, to feed it to the continuous finishing rolling train 26.
  • the winding/unwinding device 22 also allows to define a temporary accumulation buffer to compensate for possible slowdowns and non-synchronization between the continuous casting machine 12 and the continuous finishing rolling train 26.
  • the winding/unwinding device 22 allows to absorb the shutdown times of the rolling mill for small maintenance operations or for the programmed change of the cylinders or for small accidents/stoppages, without the need to interrupt the casting process, and therefore without loss of production and without penalizing the steelworks upstream.
  • the above mentioned winding/unwinding device 22 can comprise one or more heating devices, such as burners, which can be selectively activated to maintain the roughed slab Z at temperature.
  • the winding/unwinding device 22 can also comprise devices for the entrance and exit of the roughed slab Z, for example devices to guide the entrance and the exit of the roughed slab Z.
  • the continuous finishing laminating train 26 can comprise a plurality of rolling stands 27, for example in a number comprised between two and five, for example four, as shown in fig. 1.
  • the cooling means 28 can comprise cooling devices of the laminar type.
  • the plant 10 is advantageously very compact and has an overall length LT less than or equal to 130m.
  • the roller unit 15 can comprise intrados segments 30a, 30b, 30c and 30d, in this case four segments which in the drawings are on the right with respect to the casting axis X, and respective and opposite extrados segments 31a, 31b, 31c and 3 Id, which in the drawings are to the left with respect to the casting axis X.
  • the intrados segments 30a, 30b, 30c, 30d are disposed on the same side of the intrados side of the curved segment 16, while the extrados segments 31a, 31b, 31c, 3 Id are located on the same side of the extrados side of the curved segment 16.
  • each segment 30a, 30b, 30c, 30d, 31a, 31b, 31c and 3 Id can be provided with a plurality of rolls, in this case five rolls 32.
  • the extrados segments 31a, 31b, 31c and 3 Id are configured to remain in a fixed position, normally aligned parallel to the casting axis X.
  • the intrados segments 30a, 30b, 30c and 30d are instead configured so that they can be individually and selectively inclined by a certain angle a with respect to the casting axis X by means of actuators, such as hydraulic cylinders, not shown in the drawings.
  • the actuators can be controlled by position transducers, also not shown in the drawings.
  • the inclination of one or more intrados segments 30a, 30b, 30c and 30d is performed to reduce the thickness of the cast product when the latter is not yet completely solidified and therefore contains a liquid core.
  • the angle a of inclination of the segments 30a, 30b, 30c and 30d can be comprised between about 15 degrees (fig. 2) and zero degrees (fig. 5), and can be different for each segment 30a, 30b, 30c and 30d as a function of its position in the roller unit 15, the casting speed and the final desired thickness of the slab B.
  • the first three segments 30a, 30b, 30c are inclined in order to compress, and therefore reduce the thickness, so that the kissing point is substantially located in the transition zone between one segment and the other, more specifically in the zone comprised between the last roll of one of the segments and the first roll of the following segment.
  • the segments that are inclined always compress in the presence of a liquid core.
  • the KP is positioned not only in the transition zone between the segments 30a, 30b, 30c, 30d, 31a, 31b, 31c, 3 Id but also in any position whatsoever along the extension of the roller unit 15 comprised between the last roll of the first segment 30a and the last roll of the last segment 30d. In this way, it is possible to obtain, in a desired manner, the closure of the liquid cone in any position whatsoever along the entire length LR of the roller unit 15, with the exception of the first segment 30a.
  • the intrados segments 30b, 30c and 30d which come to be below the KP, that is, inside which the KP is positioned, are maintained substantially parallel to the casting axis X since the slab is already completely or partially solidified and therefore they cannot perform any compression since there is no longer a liquid core, or a completely liquid core.
  • the segments are in any case brought closer to the casting axis X in parallel, to maintain them in contact with the surface of the slab obtained from the reduction in thickness performed by the segments above.
  • the position of the kissing point KP can also be adjusted as a function of the casting speed and the degree of secondary cooling that is performed along the roller unit 15.
  • the fourth intrados segment 30d (fig. 5) is not inclined since, being the last segment, the KP falls inside it. In fact, the KP cannot be positioned below the last segment since there is no longer any containing and cooling, therefore the presence of a liquid core would swell the slab with the risk of the skin breaking and the steel contained inside it leaking, determining the so-called breakout.
  • the lower limit position of the KP which determines the maximum solidification length LS that can be reached, is in correspondence with the last roll 32 of the last segment 30d: in this case the fourth segment 30d can also assume a slightly inclined position.
  • the extrados segments 31a, 31b, 31c and 3 Id are fixed and parallel to the casting axis X, while the intrados segments 30a, 30b, 30c, 30d are configured to work in this manner: the segments that“see” liquid steel in all their height are inclined so as to compress and reduce the thickness of the cast product containing the liquid core. Instead, all the segments underneath the KP, or inside which the KP is positioned, are not inclined and are maintained parallel to the casting axis X, so as not to perform any compression on the cast product.
  • the roller unit 15 thanks to the fact that it is divided, or subdivided, into several segments, although in a reduced space, allows to increase the degree of freedom of the compressions operated by the rolls 32 in the formation of the slab B, being also able to close the liquid cone immediately underneath the crystallizer 14.
  • the range of variability of the solidification length LS which can be used on the casting machine 12, to which corresponds a range of variability in the thickness of the slab B exiting the roller unit 15, is advantageously increased by increasing the operating capacity of the casting itself.
  • a roller unit 15 has been considered having four pairs of segments of equal length.
  • the number of pairs of segments, given the same containing length LC can be increased up to 8.
  • the segments of the roller unit 15 can be of different lengths from one another.
  • the first pair of segments 30a, 31a, located at the entrance end of the roller unit 15 has a shorter length than the length of the segments 30b, 30c, 30d, 31b, 31c, 3 Id located downstream.
  • the first pair of segments allows to compress the metal product in a zone even closer to the exit end of the crystallizer 14 and therefore to move the upper limit position of the KP upward. Therefore, the minimum value of the solidification length LS is further reduced, that is, the range of use of the solidification length LS is further extended.
  • each segment 30a, 30b, 30c, 30d, 31a, 31b, 31c, 3 Id can have a length comprised between 0.4m and 1.5m, preferably between 0.5m and lm.
  • the casting machine 12 according to the invention is therefore characterized by a so-called“two-dimensional flexibility” since, with a given crystallizer 14 it is possible to choose a wide range, with respect to the state of the art, both of casting speed and also of thicknesses of the slab B.
  • the solidification length LS is advantageously very reduced, with respect to the plants of the state of the art, and is preferably comprised between about 1.3m, in the operating condition shown in fig. 2, and about 5.9m, in the operating condition shown for example in fig. 5.
  • the plant 10 described heretofore allows to obtain a production of a metal strip 11 having a very thin thickness, for example comprised between about 0.8mm and about 12.0mm, preferably between 1.2mm and 12mm and for example an average width of about 1300mm.
  • the diagram of fig. 6 shows the operating capacity of the casting machine 12 in which the casting speed Vc can vary from about 3.6 m/min to about 6.0 m/min and the first thickness of the slab B after the liquid core pre-rolling action can vary from 28mm to 48mm.
  • the curves a, b, c, d, e, f, g, h, i shown in the diagram of fig. 6 are hourly iso-productivity curves expressed in tons/hour (ton/h), from about 80 ton/h to about 160 ton/h, which correspond to an annual productivity comprised between about 400,000 tons/year and about 800,000 tons/year.
  • the curves refer to an average width of the strip of 1300mm.
  • the outline, or perimeter, of the diagram of fig. 6 defines the limit conditions of use of the casting machine 12 as a function of the grade of cast steel, also called“steel grade”, and of the geometrical and constructive characteristics of the crystallizer 14 and of the containing roller unit 15.
  • the diagram has been drawn considering the casting of a low carbon steel.
  • figs. 2 to 5 read together with the diagram of fig. 6, refer to four different working conditions in terms of range of the casting speed Vc and of the first thicknesses Sb of the slab B obtained after the liquid core pre-rolling action by the roller unit 15.
  • the minimum value of the thickness Sb of 28.0mm (fig. 2) is obtained in a high and narrow range of casting speed Vc, that is, between about 5.2 m/min and about 6.0 m/min (fig. 6). This is the condition in which there is the minimum solidification length LS, and therefore the highest KP position, as well as the maximum angle of inclination, and therefore the maximum compression of the slab B exerted by the first segment 30a.
  • the maximum value of the first thickness Sb of the slab B of 48.0mm (fig. 5) is obtained, instead, at the casting speed Vc of 5.5 m/min. This is the condition in which there is substantially the maximum length of solidification LS, and therefore the lowest KP position, with the minimum angle of inclination of the intrados segments.
  • Figs. 3 and 4 show two intermediate situations in which, respectively, the first two and the first three segments are inclined. Other intermediate situations, not shown, are possible, in which by inclining one or more segments with different compression angles, the KP is selectively located at any point whatsoever between the limit positions in order to obtain, at the various casting speeds shown in fig. 6, the intermediate range of thicknesses between the extreme values.
  • the characteristics of steel strip in rolls that is be produced are established by defining: minimum thickness, width, and steel grade, that is, the type of steel to be cast.
  • the iso-productivity curve for the continuous casting machine is determined on the diagram of fig. 6, that is, on the equivalent diagram relating to the selected steel-grade and strip width.
  • the steel grade also determines the maximum casting speed (VcMAX) that can be used to cast that specific steel grade with the desired quality.
  • VcMAX maximum casting speed
  • the casting parameters are determined on the defined iso-productivity curve based on the configuration of the finishing train.
  • the number of stands 27 required in the finishing train 26 is determined, and therefore the second thickness Sz of the transfer bar Z exiting the roughing stand 19 most suitable to feed the continuous finishing rolling train 26.
  • the first thickness Sb that the slab B exiting the roller unit 15 has to have is established as a function of the second thickness Sz that the transfer bar Z has to have.
  • Table 1 shows the minimum values of the final thicknesses Sf of the metal strip 11 as a function of assigned values of the first thickness Sb of the slab exiting the roller unit 15, of the second thickness Sz of the roughed slab Z, and of the number of finishing stands 27.
  • Table 1 Minimum final thickness Sf of the metal strip as a function of the thickness Sz of the roughed slab Z.
  • the iso-productivity curve “d” which corresponds to the desired productivity is taken into consideration.
  • the iso- productivity curve extends over a range of thicknesses of the cast slab comprised between about 32mm to 48mm.
  • the plant 10 can easily adapt to the modified situation. For example, the availability of liquid steel could change for a given casting sequence, due to delays in the steelworks upstream due to setbacks during the steel treatment steps in the secondary metallurgy steps. In this case, the choice of the iso-productivity curve is modified and the casting parameters are re-determined.
  • the plant 10 described heretofore is therefore very versatile and easy to control and to set on site.
  • insulating panels can be disposed along the curved segment 16 in order to avoid and/or reduce the cooling of the slab B between the exit of the roller unit 15 and the drawing unit 17.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Metal Rolling (AREA)
  • Wire Processing (AREA)
  • Catalysts (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)

Abstract

L'invention concerne une installation (10) et un procédé de production d'une bande métallique laminée à chaud (11), comprenant une machine de coulée continue verticale (12) et, disposés en séquence le long d'un plan de roulement horizontal (P), une cage de dégrossissage (19), un dispositif de cisaillement (20) pour le cisaillement à la taille, un inducteur (21), un dispositif d'enroulement/déroulement (22), un dispositif de cisaillement pour le recadrage de tête/queue (24), un train de laminage de finition continue (26), un dispositif de refroidissement laminaire (28) et une bobine d'enroulement (29).
PCT/IT2019/050151 2018-06-21 2019-06-21 Installation et procédé de fabrication d'une bande métallique laminée à chaud WO2019244192A1 (fr)

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IT102018000006563 2018-06-21
IT102018000006563A IT201800006563A1 (it) 2018-06-21 2018-06-21 Impianto e procedimento per la produzione di un nastro metallico laminato a caldo

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WO2019244192A1 true WO2019244192A1 (fr) 2019-12-26

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5339887A (en) * 1991-09-19 1994-08-23 Sms Schloemann-Siemag Aktiengesellschaft Process for production of steel strip
US5634257A (en) * 1994-05-17 1997-06-03 Hitachi, Ltd. Hot strip rolling plant and method directly combined with continuous casting
WO1999064189A1 (fr) * 1998-06-05 1999-12-16 Sumitomo Heavy Industries, Ltd. Procede et dispositif de coulee continue
US6129137A (en) * 1997-12-17 2000-10-10 Sms Schloemann-Siemag Aktiengesellschaft Method for producing thin slabs in a continuous casting plant
US6491088B1 (en) * 1998-04-17 2002-12-10 Sms Schloemann-Siemag Aktiengesellschaft Method and device for continuously casting thin metal strips
WO2008113848A1 (fr) * 2007-03-21 2008-09-25 Danieli & C. Officine Meccaniche S.P.A. Procédé et usine pour la production de bandes de métal
US20140034264A1 (en) * 2011-02-03 2014-02-06 Danieli & C. Officine Meccaniche Spa Rolling method for strip and corresponding rolling line
WO2015014865A1 (fr) * 2013-07-30 2015-02-05 Sms Siemag Ag Installation de laminage de coulée continue de bandes métalliques

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5339887A (en) * 1991-09-19 1994-08-23 Sms Schloemann-Siemag Aktiengesellschaft Process for production of steel strip
US5634257A (en) * 1994-05-17 1997-06-03 Hitachi, Ltd. Hot strip rolling plant and method directly combined with continuous casting
US6129137A (en) * 1997-12-17 2000-10-10 Sms Schloemann-Siemag Aktiengesellschaft Method for producing thin slabs in a continuous casting plant
US6491088B1 (en) * 1998-04-17 2002-12-10 Sms Schloemann-Siemag Aktiengesellschaft Method and device for continuously casting thin metal strips
WO1999064189A1 (fr) * 1998-06-05 1999-12-16 Sumitomo Heavy Industries, Ltd. Procede et dispositif de coulee continue
WO2008113848A1 (fr) * 2007-03-21 2008-09-25 Danieli & C. Officine Meccaniche S.P.A. Procédé et usine pour la production de bandes de métal
US20140034264A1 (en) * 2011-02-03 2014-02-06 Danieli & C. Officine Meccaniche Spa Rolling method for strip and corresponding rolling line
WO2015014865A1 (fr) * 2013-07-30 2015-02-05 Sms Siemag Ag Installation de laminage de coulée continue de bandes métalliques

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