Method and apparatus for producing flat rolled products

Abstract

The invention relates to a method and a plant for obtaining a strip, wherein the plant has at least three casting lines (11, 12, 13) arranged in parallel and at least two rolling lines (14, 15), wherein of the at least three casting lines two are side casting lines (11, 13) and one is a central casting line (12), the at least two rolling lines being aligned with two of the at least three side casting lines (11, 12, 13).

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for producing flat rolled products, such as strips, and to a corresponding production plant. In particular, the present invention relates to a method and a plant which allow to obtain a final product both in a continuous mode, in which casting is directly connected to rolling, and in a non-continuous mode, in which, before rolling, the product starts from a step-cast. BACKGROUND

[0002] Rolling plants arranged according to a continuous casting machine, which produces slabs, so-called "thin slab continuous casting machines", are known.

[0003] These rolling plants generally comprise a single rolling train positioned downstream of the continuous casting machine. It is known that the maximum casting speed which can be reached by the casting machine is significantly lower than the rolling speed of the rolling train, which must be fed without interruptions in order to operate with high productivity.

[0004] Therefore, in order to increase the productivity of the rolling line, two or even three casting machines are provided, which work in parallel to feed the single rolling train downstream.

[0005] Between the one or more casting machines and the single rolling line, it is known to provide respective equalization, heating and / or maintenance furnaces, for example of the tunnel type, which also act as accumulation buffers of the cast product when it is necessary to overcome interruptions of the rolling process due to accidents or rolling changes, thus avoiding losses of material and energy, and in particular avoiding interruptions of the casting itself.

[0006] These plants can be designed for a substantially continuous or so-called "endless" rolling process, in which the cast product is continuously rolled from the rolling train aligned with the casting machine, or for a non-continuous "roll-to-roll" rolling process, if the length of the slab corresponds to the material forming a roll, or for a "semi-endless" rolling process, if the length corresponds to a multiple of the length required to form a roll.

[0007] In the prior art documents US 6,332,255, US 5,943,753 and US 2005 / 0039320, examples of plants with two continuous casting lines which serve a single rolling train are shown. In these solutions, the rolling train is aligned with the casting axis of one of the two casting machines, which are followed by respective tunnel furnaces, as in Figure 1The document US 5,467,518 shows an installation with two casting lines, with a corresponding tunnel furnace and with a regenerator arranged centrally, the regenerator being followed by a rolling train.

[0008] The prior art documents US 2012 / 0006502, US 5,305,515, US 5,115,547 and WO 00 / 12235 show examples of installations with three casting lines and in which the rolling train is aligned with the axis of the casting machines arranged centrally, as from Figure 2 It is evident that, in addition to the two first casting lines 111, 112, a third casting line 113 is installed, followed by a corresponding tunnel furnace 124, and in which the central casting line 112 is followed by a rolling train 114 fed in a combined manner by all three casting lines 111, 112, 113.

[0009] In the described configuration, the tunnel furnaces not only act as heating devices, but also as equipment for the feeding / conveying of the slabs and comprise one or more fixed sections and at least one mobile section, which can be moved transversely with respect to the casting axis or can be moved rotationally with respect to the fixed section of the furnace, so that the two mobile sections of adjacent furnaces can cooperate to define a conveying path along which the slabs are transmitted towards the rolling train.

[0010] In the case of a semi-endless or roll-to-roll rolling process, these installations that provide several casting lines allow to increase the productivity of the rolling mill, since the rolling train can be fed at the desired frequency, but they do not allow to pass to the endless mode without causing any reduction in the production rate of the installation.

[0011] In fact, in this type of installation, if it is necessary to perform an endless rolling process, the other casting machines must be stopped or used only for the production of slabs to be stored for later use.

[0012] Furthermore, in the case of a long interruption of the rolling train due to maintenance, an accident or other event, it is still necessary to interrupt the casting process sooner or later, since the tunnel furnaces, although they also act as accumulation buffers, have only a limited containment capacity.

[0013] Therefore, there is a need to perfect a method and an installation for the production of flat rolled products, capable of overcoming at least one of the drawbacks of the prior art. SUMMARY

[0014] An object of the present application is to perfect a highly flexible method for producing flat rolled products, which is able to operate in each of the endless, semi-endless and roll-to-roll modes, and which allows a quick pass between one rolling mode and another, thus ensuring high plant productivity even in the event of interruptions in the casting or rolling process.

[0015] Another object of the present application is to provide a plant for producing flat rolled products, which has a high productivity, between about 3 million tons / year and about 80 million tons / year.

[0016] Another object of the present application is to provide a plant which allows the simultaneous rolling of cast products in both endless and semi-endless or roll-to-roll mode, thus guaranteeing high plant productivity even in the event of a stoppage of the casting or rolling train due to a fault or maintenance.

[0017] The Applicant has designed, tested and implemented the present application to overcome the drawbacks of the prior art and to achieve these and other objects and advantages.

[0018] The application is set forth and characterized in the independent claims. The dependent claims describe other characteristics or variants of the main inventive concept.

[0019] According to the present application, a method is provided for producing flat rolled products to obtain a strip in a plant having at least three casting lines arranged parallel to each other and at least two rolling lines aligned with two of the casting lines therein, so that the at least two rolling lines are directly joined with the respective casting lines, so as to also be able to operate selectively in endless mode.

[0020] In a configuration with three casting lines, two side casting lines are identified which are aligned with the at least two rolling lines, and one casting line which is arranged centrally with respect to the two side casting lines.

[0021] The method provides for:

[0022] - a casting step in which at least two of the three casting lines simultaneously produce respective continuous cast products,

[0023] - a first cutting step, which is performed downstream of the casting when one or more of the lines is operated in semi-endless or roll-to-roll mode, in which the cast products are cut into slabs of suitable length by means of first shearing members,

[0024] - a moving step, in which the slabs or cast products coming from the at least two casting lines are moved downstream by and / or by means of the respective tunnel furnaces, each of which is provided with one or more respective stationary modules and at least one respective mobile module, said at least one respective mobile module being adapted to selectively cooperate, in an alternating manner, with at least one mobile module of an adjacent tunnel furnace, so as to selectively define a conveying path along which the slabs can be transferred in a desired manner into the adjacent tunnel furnace and then towards the one or two rolling lines, depending on the specific needs of the process, and

[0025] - a second cutting step, which is performed downstream of the rolling when the one or more casting lines operate in a semi-endless or endless mode, in which the strip of the rolling is cut by means of a second cutting member as soon as the desired length of the coil to be manufactured has been reached.

[0026] According to the present application, at least one mobile module of the centrally arranged tunnel furnace cooperates in an alternating manner with at least one mobile module of the laterally arranged tunnel furnaces.

[0027] According to a first operating mode of the method, the casting step occurs simultaneously in the three casting lines. The slabs produced in the central casting line are transferred within the respective tunnel furnace and then alternately transferred towards the rolling lines located downstream of the laterally casting lines operating in a semi-endless or coil-to-coil mode.

[0028] According to a second operating mode of the method, the casting step occurs simultaneously in the lateral casting lines, which are directly joined to the respective rolling lines in an endless mode, while the central casting line is stopped.

[0029] However, in a third operating mode, the central tunnel furnace can be used to heat previously produced and stored slabs.

[0030] According to a fourth and a fifth operating mode of the method, the casting step occurs in one of the two lateral casting lines directly joined to the respective rolling line in an endless mode, while the other lateral casting line and the central casting line feed the other rolling line in a semi-endless or coil-to-coil mode.

[0031] According to a sixth and a seventh operating mode of the method, if it is necessary to interrupt the casting in one of the lateral casting lines, the casting step occurs in the other lateral casting line still in operation in an endless mode, directly joined to the respective rolling line, while the slabs produced in the central casting line are transferred towards the rolling line located downstream of the lateral casting line not in operation, which operates in a coil-to-coil mode.

[0032] According to the eighth and ninth operating modes of the method, if it is necessary to interrupt the casting of the central casting line and to stop one of the rolling lines, the casting step occurs simultaneously in the other side casting lines and the slabs produced in the side casting line which is stopped downstream of the rolling line are transferred towards the rolling line in operation in semi-endless or roll-to-roll mode.

[0033] According to the tenth and eleventh operating modes of the method, if one of the rolling lines is stopped, in any case the casting step can occur simultaneously in all the casting lines and the slabs produced in the central casting line and in the side casting line which is stopped downstream of the rolling line are transferred towards the rolling line in operation in semi-endless or roll-to-roll mode.

[0034] The present application also provides that, if the rolling step occurs in endless or semi-endless mode, once the length corresponding to the desired weight of the coil to be produced has been reached, the continuous strip is cut transversely by a second flying shear shear arranged in front of the end of the rolling line and of the coiler.

[0035] It is therefore evident that the device configuration provided allows high production flexibility in all three possible rolling modes, i.e. endless, semi-endless and roll-to-roll. Moreover, if one of the lines works in endless mode, the device still maintains a high production rate. Furthermore, the production method allows to produce a very wide range of products without having to reduce or interrupt the overall production.

[0036] Some embodiments described herein also relate to a device for producing flat rolled products, in order to obtain a strip from a continuous cast product which can be divided into slabs. The device comprises:

[0037] - at least three casting lines arranged in parallel, of which two side casting lines and at least one central casting line,

[0038] - at least three respective tunnel furnaces arranged downstream of the respective casting lines and comprising one or more respective stationary modules and at least one respective mobile module configured to cooperate in an alternating manner with at least one other mobile module of an adjacent tunnel furnace in order to selectively define a transport path of the slabs towards one or two tunnel furnaces associated with an adjacent casting line,

[0039] - at least two rolling lines aligned with the two side casting lines and comprising respective roughing and finishing rolling groups between which a respective temperature recovery system is arranged,

[0040] - at least one respective first oscillating shear arranged between the casting lines and the tunnel furnaces configured to allow the device to operate in semi-endless or roll-to-roll mode, and

[0041] at least one respective second flying shear, arranged at the end of the rolling line and configured to allow the plant to operate in endless or semi-endless mode.

[0042] Advantageously, a common workshop can be provided between the at least two rolling lines for the rotation of the worn-out rolling rolls and therefore their repair. BRIEF DESCRIPTION OF DRAWINGS

[0043] These and other aspects, features and advantages of the present application will become apparent from the following description of some embodiments, given by way of non-limiting example, with reference to the enclosed drawings, in which:

[0044] - Figures 1-2 Two different layouts of a rolling plant according to the prior art are shown;

[0045] - Figure 3 and Figure 4 a layout of a rolling plant is shown in side view and plan view respectively, to which the production method according to the present application is applicable;

[0046] - Figures 5 to 15 a feasible operating mode of the production method according to the present application is shown.

[0047] For the sake of clarity, the same reference numbers have been used to identify the same common elements in the drawings, where possible. It should be understood that the elements and features of one embodiment can be readily combined with those of another embodiment without further elaboration. DETAILED DESCRIPTION

[0048] With reference to Figure 3 and Figure 4 , an example of a co-rolling plant 10 according to the present application for the production of a strip S is shown, in which two casting machines (or casting lines) 11, 13 are aligned with respective rolling lines 14, 15, while a further casting line 12 is arranged centrally between the first two casting lines 11, 13.

[0049] We wish to clarify that the described example should in no way be considered limiting for the applicability of the present application, since the concepts set out will be applied in many other plant configurations, and in any case in all those cases in which the aim is to perform endless or semi-endless or roll-to-roll rolling in a plant 10 having at least three casting lines and two rolling lines, thus maximizing overall production in all operating modes, based on production and maintenance needs or unexpected stoppages.

[0050] Even the thickness dimension of the strip S produced in the plant 10 (which can comprise between about 0.6 mm and about 25 mm, and is obtained from slabs having a thickness of about 90 mm to about 160 mm) should in any case not be considered as limiting the applicability of the present application.

[0051] In this specific example, the plant 10 comprises three casting machines or casting lines 11, 12, 13 arranged in parallel and side by side, having respective casting axes X1, X2, X3 parallel to each other.

[0052] As first and second casting lines 11, 13, which are outermost (i.e. arranged laterally), hereinafter also referred to as lateral casting lines 11, 13, downstream of them there follow respectively first and second rolling lines 14, 15, which extend along respective rolling axes Y1, Y2 parallel to each other and aligned respectively with the casting axes X1, X3 of the lateral casting lines 11, 13.

[0053] The third casting line 12, hereinafter also referred to as central casting line 12, is arranged centrally with respect to the first two, and is configured to supply the produced slabs B to the rolling lines 14, 15, as will be explained in greater detail hereinafter.

[0054] The two rolling lines 14, 15 are therefore able, in use, to receive and roll cast products coming from all three casting lines 11, 12, 13. This configuration guarantees high flexibility of the plant, which can operate in combined endless, semi-endless or roll-to-roll mode, as will be described below.

[0055] In this specific example, the rolling lines 14, 15 comprise respective rough rolling groups 16, 17, which in this specific example have three stands 16a-16c, 17a-17c, and finishing rolling groups 18, 19, which in this specific example comprise five stands 18a-18e, 19a-19e.

[0056] Between the rough rolling groups 16, 17 and the finishing rolling groups 18, 19 there are temperature recovery systems, for example induction furnaces 20, 21, which bring the strips exiting from the rough rolling groups 16, 17 back to the correct rolling temperature.

[0057] Downstream of the casting machines 11, 12, 13, there are respective tunnel furnaces 22, 23, 24 having a length sufficient to contain a number of slabs of at least between 2 and 5.

[0058] The tunnel furnaces 22, 23, 24 allow, in a known manner, to act both as buffers in case of even one or more rolling lines 14, 15 momentary interruptions, and to operate in semi-endless mode.

[0059] In particular, the tunnel furnace 23 of the central casting line 12 (hereinafter also referred to as central tunnel furnace 23) can act as an accumulation buffer for the entire plant 10, since, as will be better explained hereinafter, it allows the passage of the slabs B from / to the tunnel furnaces 22, 24 of the side casting lines 11, 13 (hereinafter also referred to as side tunnel furnaces 22, 24) and, therefore, towards the rolling lines 14, 15.

[0060] In particular, the side tunnel furnaces 22, 24 are arranged in alignment between the respective side casting lines 11, 13 and the corresponding rolling lines 14, 15 located downstream.

[0061] Upstream of the tunnel furnaces 22, 23, 24, there are respective first oscillating shears 25, 26, 27 which cut the cast product into the size of the slabs B when the respective casting lines 11, 12, 13 operate in a semi-endless or roll-to-roll mode.

[0062] Downstream of the finishing rolling mills 18, 19, there are respective second flying shear shears 28, 29 which intervene, if the rolling is in an endless or semi-endless mode, in order to cut the strip S obtained transversely into winding sizes, so as to feed the lower coilers 32a-32c, 33a-33c alternately after the cut-to-size parts have passed through the respective cooling units 30, 31. The second flying shear shears 28, 29 are therefore arranged respectively between the cooling units 30, 31 and the lower coilers 32a-32c, 33a-33c.

[0063] The strip S can be longitudinally subdivided so that the width of the strip obtained is a fraction of the starting cast product width. To this end, the strip S can be rolled with double or multiple crowns so that the subsequent half- strips or multiple strips obtained from the strip S each have the correct crown as if they were rolled individually.

[0064] We wish to clarify that the longitudinal subdivision of the strip S can occur immediately downstream of the finishing rolling unit 18, 19, or directly in the process of winding of the lower coilers 32a-32c, 33a-33c, using dedicated devices, or in a step subsequent to the removal of the coils, for example in a different plant using the strip S.

[0065] The method for producing strip S thus provides a casting step in which at least two casting lines 11, 12, 13 simultaneously produce corresponding continuous casting products, which, if supplied to two rolling lines 14, 15 in a semi-endless or roll-to-roll mode, can be divided into slabs B of suitable length by means of first oscillating shears 25, 26, 27, or, if supplied to two rolling lines 14, 15 in an endless mode, remain in the form of continuous slabs.

[0066] The casting step is followed by a moving step, in which the slab B is moved downstream by means of and by means of tunnel furnaces 22, 23, 24 located downstream of the respective casting lines 11, 12, 13.

[0067] Each tunnel furnace 22, 23, 24 is provided with one or more corresponding fixed modules 22a, 23a, 24a and at least one corresponding moving module 22b, 23b, 24b. The at least one corresponding moving module 22b, 23b, 24b can cooperate alternately with at least one other moving module 22b, 23b, 24b of the adjacent tunnel furnace 22, 23, 24 in order to define the conveying path. Depending on the specific needs of the processing, the slab B is conveyed along the conveying path in a desired manner first toward one or both of the side tunnel furnaces 22, 24, and then toward the downstream rolling lines 14, 15.

[0068] In this specific example, the moving module 23b of the central tunnel furnace 23 can cooperate alternately with at least one moving module 22b, 24b of the side tunnel furnaces 22, 24. It is intended to clarify that this configuration is by no means limiting, but rather particularly advantageous, because the central tunnel furnace 23 is equidistant from the two rolling lines 14, 15, thus allowing it to act as a connection between the two outermost lines, thereby ensuring reduced time for moving the slab B.

[0069] exist Figure 4 In the solution shown, the penultimate modules 22b and 24b of the side tunnel furnaces 22 and 24 are rotatably movable at least between a first position and a second position. In the first position, the module is aligned with the corresponding casting axes X1 and X3, thereby allowing the slab B to be transported toward the downstream rolling lines 14 and 15. In the second position, the module is arranged at an angle relative to the corresponding casting axes X1 and X3, and is aligned with the terminal module 23b of the central tunnel furnace 23 if necessary.

[0070] In turn, the terminal modules 23b are rotatably movable at least between a position of alignment with the respective casting axis X2, in order to receive the slabs B produced directly by the central casting line 12 or coming from a warehouse for storing cold slabs, and an angular position of alignment with one of the penultimate mobile modules 22b, 24b of the side casting lines 11, 13.

[0071] A similar solution can be obtained by translating the mobile modules 22b, 23b, 24b in a direction orthogonal to the casting axes X1, X2, X3, like shuttles, sideways and parallel, until the alignments necessary to define the linear path for the transport of the slabs B are obtained.

[0072] In the described solution, the plant 10 also comprises two intermediate connecting furnaces 34, 35 for balancing, which are arranged in a fixed position and are angled so that the mobile modules 22b, 23b, 24b, when they are rotated to cooperate with each other as described above, are also aligned with the respective intermediate furnaces 34, 35 which act as connecting elements and partially as buffers.

[0073] However, it is also possible to provide a configuration in which the mobile modules 22b, 23b, 24b cooperating with each other are able to define the passage line directly without the aid of intermediate components.

[0074] On the side of the tunnel furnaces 22, 23, 24, emergency roller conveyors 36, 37, 38 can be provided, which can receive one or more slabs B if it is necessary to perform maintenance or other. The slabs B are transported directly onto the emergency roller conveyors 36, 37, 38 by means of the mobile modules 22b, 23b, 24b, which can therefore be rotated in order to align with the roller conveyors 36, 37, 38.

[0075] Figures 5-15 An operational mode of the just described plant 10 is shown.

[0076] According to Figure 5 In the first operational mode shown, the casting steps take place simultaneously in the three casting lines 11, 12, 13. The slabs B produced in the central casting line 12 are transported (preferably in an equidistant manner) towards the two rolling lines 14, 15 operating in a semi-endless or roll-to-roll mode. In the case of semi-endless rolling downstream of the finishing rolling units 18, 19, the strip S is cut transversely into one size with the second flying shears 28, 29 before being wound on the lower coilers 32a-32c, 33a-33c. In this first operational mode, the plant 10 can reach a total nominal capacity of about 7.5 Mton / year.

[0077] According to Figure 6In the second operating mode shown, the casting step takes place simultaneously in the side casting lines 11, 13, the side casting line 13 being directly engaged with the corresponding rolling line 14, 15 in the endless mode, while the central casting line 12 is stopped. Similarly to the previous case, also in this case, downstream of the finishing rolling unit 18, 19, the strip S is cut transversally by the second flying shear 28, 29 before being wound on the lower coilers 32a-32c, 33a-33c. In this second operating mode, the plant 10 can reach a total nominal capacity of about 5 Mton / year.

[0078] In the description here and in the following, for the sake of clarity of the explanation of the figures, when one of the casting lines 11, 12, 13 or one of the rolling lines 14, 15 is stopped for any reason, it is identified with the symbol STP.

[0079] According to Figure 7 In the third operating mode shown, the casting step takes place simultaneously in the side casting lines 11, 12, the side casting lines being directly engaged with the corresponding rolling lines 14, 15 in the endless mode, while the central casting line 12 is stopped. In addition, the central tunnel furnace 23 is used to heat the cold slabs B previously produced. These slabs B can also be conveniently surface treated with grinding or scarfing techniques, in order to produce a strip S with high surface quality, for so-called "exposed" use in the automotive field. In this third operating mode, the plant 10 can reach a total nominal capacity of about 5 Mton / year.

[0080] In Figures 8-9 In the fourth and fifth operating modes shown respectively, the casting step takes place in one of the two side casting lines 11, 13 in the endless mode, this one side casting line being directly engaged with the corresponding rolling line 14, 15, while the other side casting line 11, 13 and the central casting line 12 feed the other rolling line 15, 14 in the semi-endless or roll-to-roll mode. The slabs B produced in the central casting line 12 are transferred towards the rolling line 14, 15 operating in the semi-endless or roll-to-roll mode. In this fourth and fifth operating mode, the plant 10 can reach a total nominal capacity of about 7 Mton / year.

[0081] As shown in the sixth and seventh operating modes Figures 10-11 If it is necessary to interrupt the casting in one of the side casting lines 11, 13, these are aligned with the corresponding rolling lines 14, 15, the side casting line 11, 13 still in operation feeding the corresponding rolling line 14, 15 in the endless mode, while the central casting line 12 feeds the other rolling line 14, 15 in the roll-to-roll mode. The slabs B produced in the central casting line 12 are transferred towards the rolling line 14, 15 downstream of the casting line 11, 13 not in operation. In this sixth and seventh operating mode, the plant 10 can reach a total nominal capacity of about 5 Mton / year.

[0082] Figures 12-13 An eighth and ninth operating mode is shown. If it is necessary to interrupt the casting of the central casting line 12 and to stop one of the rolling lines 14, 15, for example for maintenance, the casting step takes place simultaneously in the side casting lines 11, 13 and, by means of the central tunnel furnace 23 acting as an interconnection between these lines, the slabs B produced in the side casting line 11, 13 whose rolling line 14, 15 is stopped are transferred towards the rolling line 14, 15 which is operating. This rolling line 14, 15 will operate in semi-endless or roll-to-roll mode. In this eighth and ninth operating mode, the plant 10 can reach a total nominal capacity of about 4.5 Mton / year.

[0083] Figures 14-15 An additional tenth and eleventh operating mode is shown in the middle. If one of the rolling lines 14, 15 is stopped, for example for maintenance, the casting step can take place simultaneously in all three casting lines 11, 12, 13 in any case. The slabs B produced in the central casting line 12 and in the side casting lines 11, 13, where the rolling line 14, 15 is stopped, are both transferred towards the rolling line 14, 15 which is operating in semi-endless or roll-to-roll mode.

[0084] It is clear that modifications and / or additions of parts or steps can be made to the method and plant for producing flat rolled products as described so far, without departing from the field and scope of the application as defined in the claims.

[0085] In the following claims, the sole purpose of the reference signs placed in brackets is to facilitate reading and they should not be considered as limiting factors with respect to the scope of protection required in the specific claim.

Claims

1. A method for producing flat-rolled products to obtain a strip (S) in a plant (10) configured to operate in endless, semi-endless or roll-to-roll mode, with at least three casting lines (11, 12, 13) and at least two rolling lines (14, 15) arranged in parallel, wherein, In said at least three casting lines, two of them are side casting lines (11, 13) and one is a central casting line (12), said at least two rolling lines being aligned with said side casting lines (11, 13), said method comprising in sequence: - a casting step, in which at least two of said casting lines (11, 12, 13) simultaneously produce respective continuous cast products, - a first cutting step, which is performed downstream of said casting, when one or more of said casting lines (11, 12, 13) operates in a semi-endless or roll-to-roll mode, in which said cast products are cut into slabs (B) of suitable length by first shearing members (25, 26, 27), - a moving step, in which said slabs (B) or said cast products are moved downstream by and / or with the aid of respective tunnel furnaces (22, 23, 24), each tunnel furnace being provided with one or more respective stationary modules (22a, 23a, 24a) and at least one respective mobile module (22b, 23b, 24b), said mobile module being adapted to selectively cooperate in an alternating manner with at least one other of said mobile modules (22b, 23b, 24b) of an adjacent tunnel furnace (22, 23, 24) when one or more of said casting lines (11, 12, 13) operates in a semi-endless or roll-to-roll mode, so as to define a conveying path along which said slabs (B) are transported in a desired manner towards one of the two tunnel furnaces (22, 23) associated with said side casting lines (11, 13) and then towards one or both of said rolling lines (14, 15), depending on the specific needs of the process, - a rolling step, provided in sequence for each of said rolling lines (14, 15) by a respective rough rolling mill group (16, 17) and a respective finishing rolling mill group (18, 19), temperature recovery being able to be provided by a respective induction furnace (20, 21) located between said rough rolling mill group (16, 17) and said finishing rolling mill group (18, 19), and - a second cutting step, which is performed downstream of said rolling when one or more of said casting lines (11, 12, 13) operates in a semi-endless or endless mode, in which said strip (S) just rolled is cut as soon as a length has been reached which determines the desired weight of the coil to be manufactured, by means of second shearing members (28, 29), wherein said casting step occurs in endless mode in one of the two side casting lines (11, 13) which directly engages with a respective rolling line (14, 15), while the other side casting line (13, 11) and the central casting line (12) operate in semi-endless mode or roll-to-roll mode with the other rolling line (14, 15).

2. The method of claim 1, wherein, Said at least one mobile module (23b) of the tunnel furnace (23) associated with the central casting line (12) cooperates in an alternating manner with at least one mobile module (22b, 24b) of the tunnel furnaces (22, 24) associated with the side casting lines (11, 13). Said at least one mobile module (23b) of the tunnel furnace (23) associated with the central casting line (12) cooperates in an alternating manner with at least one mobile module (22b, 24b) of the tunnel furnaces (22, 24) associated with the side casting lines (11, 13).

3. The method of claim 1 or 2, wherein, Said casting steps occur simultaneously in said at least three casting lines (11, 12, 13) and the slabs (B) produced in the central casting line (12) are transferred towards the rolling lines (14, 15) operating in semi-endless or roll-to-roll mode.

4. The method of claim 1 or 2, wherein, Said casting steps occur simultaneously in said side casting lines (11, 13), which, at the stop of the central casting line (13), directly interface with the respective rolling lines (14, 15) in endless mode.

5. The method of claim 4, wherein, During said casting steps, the tunnel furnace (27) associated with the central casting line (12) is used to heat previously produced and stored slabs (B).

6. The method of claim 1 or 2, wherein, If it is necessary to interrupt the casting in one of the side casting lines (11, 13) aligned with a respective rolling line (14, 15), said casting steps take place in endless mode in the side casting lines (11, 13) still in operation, while the slabs (B) produced in the central casting line (12) are transferred towards the rolling lines (14, 15) operating in roll-to-roll mode downstream of the stopped side casting line (11, 13).

7. The method of claim 1 or 2, wherein, If it is necessary to interrupt the casting of the central casting line (12) and one of the rolling lines (14, 15) is stopped, said casting steps occur simultaneously in the other side casting lines (11, 13) and the slabs (B) produced in the side casting line (11, 13) downstream of which the rolling line (14, 15) is stopped are transferred towards the rolling lines (14, 15) operating in semi-endless or roll-to-roll mode in operation.

8. The method of claim 1 or 2, wherein, If one of the rolling lines (14, 15) is stopped, in any case said casting steps can occur simultaneously in all the casting lines (11, 12, 13) and the slabs (B) produced in the side casting line (11, 13) downstream of which the rolling line (14, 15) is stopped and in the central casting line (12) are transferred towards the rolling lines (14, 15) operating in semi-endless or roll-to-roll mode in operation. If one of the rolling lines (14, 15) is stopped, in any case said casting steps can occur simultaneously in all the casting lines (11, 12, 13) and the slabs (B) produced in the side casting line (11, 13) downstream of which the rolling line (14, 15) is stopped and in the central casting line (12) are transferred towards the rolling lines (14, 15) operating in semi-endless or roll-to-roll mode in operation.

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