Method for modifying a plant for producing flat rolled products - Patent Application 20070122997

Abstract

A method for modifying a starting rolling plant (10, 100) for producing a final strip (P) having a specified starting thickness from a slab (50), the rolling plant (100) comprising at least one heating furnace (16) configured to heat at least the slab (50) to a specified starting temperature, at least one reversible rough forming stand (23) configured to perform one or more rolling passes on the slab (50) to obtain an intermediate rolled product (51), and a rolling mill train (25) operatively arranged alongside the rough forming stand (23), the rolling mill train (25) comprising at least one preliminary finishing stand (26) and a plurality of finishing stands (31), the rolling mill train (25) configured to reduce the thickness of the intermediate rolled product (51) until a final strip (P) having a specified final thickness is obtained.

Description

[Technical Field]

[0001] The present invention relates to a method for revamping a rolling plant to produce flat rolled products, such as, but not limited to, steel strip wound into rolls or coils. [Background technology]

[0002] Rolling plants, also known as hot strip mills, or simply abbreviated as "HSM" in the following, are intended for the hot production of metal strip from slabs, typically having a thickness of between about 150 mm and about 350 mm.

[0003] Examples of plants of this type are disclosed in EP-A-919296, US-A-2007 / 051153, US-A-4308739 and EP-A-3025799.

[0004] Two other examples of such plants are shown diagrammatically in FIGS.

[0005] These example plants include a "walking beam" type furnace 16 for heating the slabs, and one or two reversible roughing stands 23 in line. If the plant has one roughing stand 23 (FIG. 1), the stand will typically perform 5 to 7 rolling passes to obtain an intermediate bar having a thickness of about 35 mm to about 45 mm, whereas if the plant has two roughing stands 23 (FIG. 2), the first roughing stand 23 will perform 3 rolling passes and the second roughing stand 23 will perform 3 to 5 additional rolling passes.

[0006] A transfer table is usually provided downstream of the reversible stand 23, and this transfer table is usually provided with a passive insulating hood 99, i.e., an insulating hood 99 without a heating burner, to reduce heat loss from the bar.

[0007] A shear 27, typically a drum shear type shear 27, is provided downstream of the transfer table and is sized to cut rolled products typically having a thickness of about 35 mm to about 45 mm.

[0008] Immediately downstream of the shear 27 are a water descaler 24, a continuous rolling mill train or small finisher train 25 having six or seven finishing stands arranged side by side and closely adjacent to one another, and an exit table 34, also called a "runout table," which is provided with a cooling shower 33 and two or more take-up reels 36, 38 (down coilers) for winding the finished strip into a roll or coil.

[0009] In order for the rolling in the small finisher train 25 to be carried out in the austenitic range, i.e. without causing a phase transformation in the steel structure, the strip must leave the last stand of the finisher train 25 at a temperature not lower than 830°C.

[0010] Therefore, it is necessary to set the rolling mass flow rate in the small finisher train 25 to achieve an optimum temperature of at least 830°C at the exit of the last finishing stand.

[0011] Furthermore, the rolling mass flow rate is calculated as the product of the thickness of the strip and the rolling speed of the strip. Therefore, when a specific rolling mass flow rate is set, the rolling speed of the strip is determined only by the final thickness of the strip.

[0012] A first drawback of known plants is that the heating of thick or conventional slabs is carried out in a furnace, which uses gas burners to raise the temperature of the product to approximately 1200-1250°C. This temperature is necessary to take into account all the temperature losses along the line and ensure that the strip leaves the last rolling stand at a temperature of at least 830°C.

[0013] However, the slab heating operation takes a long time, for example 4 to 7 hours, and requires a very large amount of gas consumption by the burner, which affects environmental emissions and production costs.

[0014] Furthermore, when heating certain steels, the thermal targets can be even higher, increasing both gas consumption and emissions. Also, varying the heating depending on the type of steel and the desired final quality means waiting for the furnace to heat up to the desired temperature, which limits production flexibility and forces manufacturers to arrange production to heat thermally similar products to optimize the time required to reach the furnace target temperature. This leads to longer delivery times for finished products and an increasing demand for smaller batches.

[0015] Another drawback of conventional HSM plants is the need to limit the maximum speed of the strip exiting the finisher train to prevent the leading edge of the strip from dangerously rising due to aerodynamic effects of speed on its path from the last stand to the take-up reels 36, 38. Typically, the maximum speed allowed for the leading edge of the strip on the run-out table is about 11-12 m / s, and this speed can increase after winding on the take-up reels begins.

[0016] The leading edge of the strip usually means the leading end of the strip that contacts the first stand of the finishing rolling line in the direction of travel.

[0017] The term trailing edge of the strip similarly refers to the trailing end of the strip which, in the direction of travel, is the last to enter the first stand of the finishing rolling line.

[0018] The portion of the band contained between the leading edge and the trailing edge is referred to as the body of the band.

[0019] Due to this speed limitation, it is not possible to reach an optimum temperature of at least 830°C at the exit of the last finishing stand, especially for thin strips, for example those with a thickness of 1.2 mm or less.

[0020] Such a solution, when applied to the production of rolled products with a final thickness of, for example, 1.2 mm, requires an acceleration of the trailing edge of about 40%, as shown diagrammatically in the graph of Figure 3, in order to guarantee a minimum temperature of 830°C at the exit of the last stand, since the furnace upstream of the line is the only active heat source.

[0021] However, despite using a speed-up of 60%, which typically reaches the speed limit of 19-20 m / s, if one wishes to obtain a rolled product with a rolled thickness of less than 1.2 mm, conventional HSM plants are unable to maintain the required minimum temperature of 830°C at the exit of the last stand, because the temperature loss of the rolled product is excessive and the resulting undesired phase changes in the steel affect the quality of the final product.

[0022] As shown in the graph in Figure 4, in a conventional HSM plant, to produce a 1.0 mm thick strip and achieve the speed limit mentioned above, the exit temperature of the last rolling stand would be approximately 780°C not only at the leading edge but also at the trailing edge, making it virtually impossible to produce quality strip of such a limited thickness.

[0023] To overcome these limitations, a solution has been proposed in which induction heating is performed immediately before the small finishing train, and the bar is introduced at a higher temperature. However, since the heating is performed before the first stand, which is the slowest, more scale will form due to the higher temperature if the bar rolled in the first stand has the same exposure time to air.

[0024] Furthermore, the small finisher trains of conventional HSM plants do not allow for the further high pressure descaling step to be carried out within the train itself prior to winding of the ribbon.

[0025] This means that scale that forms following exposure of the bar to hot air during the first pass cannot be removed and is therefore imprinted into the strip during the final pass, reducing the quality of the finished product.

[0026] Currently, there is an increasing need in HSM plants to produce high quality strips with thicknesses of less than 1.8 mm, with minimum values ​​of 0.9 mm to 1.2 mm, overcoming the drawbacks of the prior art. Quality should be understood both in terms of the surface quality of the strip and in terms of the final mechanical properties required by the market.

[0027] It is therefore an object of the present invention to complete a method for modifying a hot strip mill plant so that it is capable of producing high quality thin gauge strip, which can reach more than 6 million tons per year, without adversely affecting the productivity of the existing plant.

[0028] Another object of the present invention is to perform the retrofit with reduced economic and operational impact compared to existing plants.

[0029] Another object of the present invention is to provide an existing hot strip mill plant with uniform mechanical and geometric properties throughout the entire length of the manufactured coil.

[0030] Applicant has conceived, tested and embodied the present invention to overcome the shortcomings of the prior art and to achieve these and other objects and advantages. Summary of the Invention

[0031] The invention is defined and characterized in the independent claims. The dependent claims define refinements and implementations of the independent claims.

[0032] With the above objectives in mind, the method of the present invention is adapted to retrofit an existing hot strip mill plant for producing finished steel strip of a specified starting thickness from a slab, said retrofitted plant comprising: at least one furnace configured to heat at least the slab to a defined starting temperature, for example to a temperature of about 1100-1150 ° C to 1200 ° C; at least one reversible rough forming stand configured to perform one or more rolling passes on the slab to obtain an intermediate rolled product, the thickness of the intermediate rolled product being, for example, between about 45 mm and about 80 mm; a rolling mill train operatively arranged alongside said rough forming stand; It is equipped with the rolling mill train includes at least one group of pre-finishing stands and at least one group of finishing stands; The rolling mill train is configured to reduce the thickness of the intermediate rolled product until the final strip is obtained having a minimum final thickness, the minimum final thickness being less than 1.2 mm.

[0033] Thus, the existing plants to be converted are generally configured as traditional hot strip mill rolling plants operating in the coil-to-coil mode, i.e., as intermittent hot strip mill rolling plants, in which the rolled product is obtained from individual slabs having a thickness of, for example, about 150 mm to about 350 mm, and all of the operational, dimensional and production characteristics of the above rolling plants are possessed by plants of the above type.

[0034] Existing plants typically include, from upstream to downstream, three heating furnaces, a first water descaling device, and a vertical or edging stand for processing the edges, which is combined with at least one reversible rough forming stand that reduces the thickness of the slab by rolling a specified number of passes on the slab until an intermediate rolled product (or bar) is obtained, usually having a thickness of about 35 mm to about 45 mm, followed by a transfer table, which is provided with, for example, a passively insulated hood, i.e., an insulated hood without heating burners, to limit heat loss from the bar.

[0035] In some hot strip mill plants, the transfer table terminates in a coil box in which the intermediate rolled product is wound onto rolls that are subsequently unrolled.

[0036] Downstream from the transfer table or coil box is a shear, usually in the form of a drum shear, which is sized to cut the intermediate rolled product.

[0037] Immediately downstream of the shear 27 is a second water descaling unit, a continuous rolling mill train or a small finishing mill train with six or seven finishing stands arranged side by side and closely adjacent to one another, and an exit table, also called a "runout table," which is provided with a cooling shower and two or more take-up reels (downcoilers) for winding the finished strip into rolls or coils.

[0038] In one aspect of the invention, the method includes at least one step of modifying the existing compact finisher train to obtain the desired converted plant by moving at least a first stand closer to the reversible rough forming stand and away from the remaining stands downstream from the first stand at a minimum distance "D" from the reversible rough forming stand, such that the intermediate product is not simultaneously operatively engaged with both stands.

[0039] Such movement positions a first group of stands, referred to as "pre-finishing units," at a predetermined distance "d" from a second group of stands, referred to as "finishing units."

[0040] In the present invention, the change step is carried out so that the number of pre-finishing stands in the pre-finishing unit becomes 1 to 2 and the number of finishing stands in the finishing unit becomes 5 to 6.

[0041] Depending on the initial configuration of the existing plant and the final division of the finishing train to be achieved, it may be necessary to include new stands in the pre-finishing unit in addition to those taken from the existing train.

[0042] For example, if an existing train has seven stands, move the first two stands to the pre-finishing unit to create a 2+5 configuration.

[0043] On the other hand, if the existing train has six stands, the first stand is moved to the pre-finishing unit and a new stand is added to the pre-finishing unit to create a 2+5 configuration.

[0044] In the space between the reversible stand and the pre-finishing unit, the existing passive insulating hood shall be left for the amount required to cover a portion of the distance "D" above.

[0045] Where an existing plant has a coil box, the present invention preferably removes the coil box in the retrofitted plant and replaces it with a passive insulating hood.

[0046] Advantageously, at least one step is provided of installing a novel high-rate heating device, such as an inductor consisting of selectively operable modules, interposed between the pre-finishing unit and the finishing unit for heating the pre-finished rolled product.

[0047] In another aspect of the invention, the method includes removing an existing drum shear, after possible modification, and placing it between the pre-finishing unit and the high velocity heating device.

[0048] In another aspect of the invention, the method includes locating the second existing descaling means prior to the pre-finishing unit.

[0049] Advantageously, the method includes a novel third water descaling means between the high-velocity heating device and the first stand of the finishing unit, which has the function of further cleaning the surface of the prefinished rolled product of scale before the prefinished rolled product enters the finishing unit. This configuration removes scale formed on the surface of the prefinished product and avoids quality defects in the rolled strip, such as scale indentations.

[0050] The at least one reversible pre-forming stand is provided with descaling means which are an integral and inseparable part of the stand, the descaling means being arranged on both the inlet and outlet sides of the stand.

[0051] A plant modified in accordance with the above method operates as follows:

[0052] The exit temperature of the slabs upon leaving the furnace is about 1100-1150°C to about 1200°C, which results in an exit temperature that is about 50-150°C lower than the original temperature, thereby reducing permanence time in the furnace and providing benefits in terms of gas consumption and corresponding costs, air emissions and scale formation.

[0053] If the existing plant is equipped with only one reversible rough forming stand and this is kept unchanged in the modified plant, the number of rolling passes will be reduced from 7 to 5.

[0054] If the existing plant is provided with two reversible rough forming stands and these are kept unchanged in the modified plant, the number of rolling passes is reduced from three in the first stand and 3-5 to 1-3 in the second stand.

[0055] In either case, the thickness of the intermediate rolled product obtained at the exit of the rough forming stand is about 45 mm to about 80 mm. By way of example only, the temperature of the intermediate rolled product at the end of the required rough forming passes is in the range of about 1020°C to about 1120°C.

[0056] The pre-finishing unit can reduce the thickness of the intermediate rolled product to obtain a pre-finished rolled product, the thickness of which is, for example, about 10 mm to about 50 mm.

[0057] Thus, in the modified version of the plant, the leading and trailing edges of the shear trim the pre-finished product to a thinner thickness in the same trimming section, resulting in a lower weight of rejected material, which has a positive impact on the plant yield.

[0058] In the high rate heating device, heating can advantageously be carried out to an exit temperature of about 1000°C to about 1100°C of the high rate heating device, or in any case, depending on the operating and product parameters, to a temperature in the final zone at least above 830°C upon exiting the final finishing stand.

[0059] This advantageous aspect of the solution of the invention allows the steel to remain substantially in the austenite range during rolling in the finishing unit, so that rolling can be carried out without phase transformation before leaving the final finishing stand.

[0060] In this way, it is possible to provide for the production of a rolled product having substantially uniform mechanical and geometric properties over the entire length of the produced coil.

[0061] Furthermore, by installing an induction heating device between the pre-finishing stand and the finishing stand, it is possible to relieve the upstream gas-fired furnace from a portion of its heat contribution to provide to the slab, thereby reducing gas consumption and emissions compared to the same plant before the modification of the present invention.

[0062] The finishing stand is configured to reduce the thickness of the pre-finished rolled product to obtain a final strip, the thickness of which is, for example, about 1 mm to about 26 mm.

[0063] By modifying each step of the method of the present invention in an existing conventional hot strip mill plant, the plant can be modified to produce thin, flat rolled products with thicknesses of 1.8 mm or less, with a minimum value of 0.9 to 1.2 mm, thereby eliminating the quality, productivity, and yield problems that conventional plants have when reducing thickness as described above.

[0064] Thus, by essentially splitting the existing rolling train into two macro pre-finishing and finishing rolling units, and sandwiching a high-speed heating device between them, the starting HSM plant is retrofitted to achieve high-quality thin gauges without adversely affecting the productivity of the plant, which can reach 3-5 million tons per year.

[0065] These and other aspects, features and advantages of the present invention will become apparent from the following description of some embodiments thereof, given as non-limiting examples, with reference to the accompanying drawings. [Brief explanation of the drawings]

[0066] [Figure 1] 1 is a schematic diagram of one type of HSM plant for producing prior art flat rolled products. [Figure 2] 1 is a schematic diagram of another type of HSM plant for producing prior art flat rolled products. [Figure 3] 1 is a graph showing the relationship between rolling speed and exit temperature for a prior art rolled product. [Figure 4]4 is a graph showing the relationship between rolling speed and exit temperature for prior art rolled products of different thicknesses from those in FIG. 3. [Figure 5] 2 is a schematic diagram of the corresponding HSM plant of FIG. 1 after the method for modifying a plant for producing flat rolled products of the present invention has been implemented. [Figure 6] 3 is a schematic diagram of the corresponding HSM plant of FIG. 2 after the method for modifying a plant for producing flat rolled products of the present invention has been implemented. [Figure 7] 1 is a graph showing the relationship between rolling speed and exit temperature of the rolled product of a modified HSM plant to produce flat rolled products of the present invention. [Figure 8] 8 is a graph showing the relationship between rolling speed and exit temperature for rolled products of thicknesses different from that of FIG. 7 in a modified HSM plant for producing flat rolled products of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0067] It should be made clear here that the scope of protection is defined by the claims, and therefore the role of the wording and terminology in this specification and the description of each figure in the accompanying drawings is only to facilitate the illustration and explanation of the invention, and its function is to provide a non-limiting example of the invention itself.

[0068] For ease of understanding, wherever possible, the same reference numerals have been used to identify the same common elements in the figures, and it is understood that elements and features of one embodiment may be combined or incorporated into other embodiments as appropriate without further discussion.

[0069] 5 and 6, two types of HSM plants 10 are shown, each of which was obtained by retrofitting a corresponding start-up HSM plant 100 according to the method of the present invention.

[0070] The plant 10 is a modified starting plant 100 for rolling a slab 50 having a starting thickness of between about 150 mm and about 350 mm into a flat rolled product, such as a final strip P, having a thickness of between about 0.9 mm and about 26 mm, which is then wound into a roll or coil.

[0071] Both the starting plant 100 and the modified plant 10 include one or more gas-heated furnaces 16, such as gas-heated furnaces 16 of the type known in the art as "walking beam" furnaces, configured to receive and heat at least one slab 50 to a specified starting temperature, which may be supplied to the gas-heated furnace 16 at room temperature.

[0072] In the configuration using the modified plant 10, the temperature of the slab 50 upon exiting the gas furnace 16 is from about 1100-1150°C to about 1200°C, rather than the original 1200°C-1250°C. Thus, the exit temperature of the slab upon exiting the furnace is 50-150°C lower than the original temperature, which reduces residence time within the furnace, providing benefits in terms of gas consumption and corresponding costs, air emissions, and scale formation.

[0073] A warehouse 40 configured to cooperate with the gas-fired furnace 16 and store slabs 50 may be provided as part of the plant 10, and may be configured to store slabs 50, for example, from other production locations or other production areas within the same plant. The warehouse 40 allows for selective feeding of at least one slab 50 to the gas-fired furnace 16 in a desired feeding sequence and timing.

[0074] In the original type plant 100 shown in FIG. 1 and the corresponding modified plant 10 in FIG. 3, arranged in sequence downstream from the gas heated furnace 16 are a first water descaling unit 20, a vertical or edging stand 21, and a reversible rough forming stand 23, which is configured to reduce the thickness of the slab 50 by making a specified number of passes on the slab 50 until an intermediate rolled product 51 is obtained.

[0075] In the original type plant 100 shown in FIG. 2 and the corresponding modified plant 10 in FIG. 4, in addition to the descaling device 20, two reversible rough-forming stands 23 with corresponding vertical stands 21 are also arranged downstream of the gas furnace 16.

[0076] The reversible pre-forming stands are provided with descaling means which are an integral part of the stands themselves, with descaling means being located both at the inlet and outlet sides of each stand (not shown).

[0077] The above-described corresponding arrangement between the original plant 100 and the corresponding modified plant 10, whether with one or two types of pre-forming stands 23, highlights the advantageous properties of the inventive retrofit method, which leaves the majority of the plant intact in its original configuration, with advantages in terms of cost, timing, and impact of the retrofit intervention.

[0078] With the plant 10 modified in this way, the thickness of the intermediate rolled product 51 obtained at the exit of the rough forming stand 23 will be about 45 mm to about 80 mm instead of the original 35 mm to 45 mm. By way of example only, the temperature of the intermediate rolled product 51 at the end of the required rough forming passes will be in the range of about 1020°C to about 1120°C.

[0079] Now, to carry out the conversion of both types of plants 100 shown in Figures 1 and 2, the drum shears 27 are removed and the descaler 24 and the two stands of the compact rolling mill train 25 are disassembled.

[0080] The descaler 24 and the two stands are moved toward the reversible stand 23 a predetermined distance D from the reversible stand 23 so that the intermediate product 51 is not operatively engaged with both types of stands simultaneously.

[0081] In this way, the mini-mill train 25 is divided into two macro rolling units, a pre-finishing unit 26 and a finishing unit 31, which are intentionally spaced apart from each other by a predetermined distance "d".

[0082] The stand of the finishing unit 31 remains substantially in its original installed position without affecting the retrofit intervention.

[0083] The modified rolling mill train is configured to gradually reduce the thickness of the intermediate rolled product 51 to obtain a final strip P having a minimum thickness of about 0.9 to 1.2 mm.

[0084] In the solution of the present invention, a pre-finished rolled product 52 having a thickness of about 10 mm to about 50 mm is discharged from the two pre-finishing stands 26.

[0085] In the present invention, an identical drum shear 27, in this example, is positioned downstream of the pre-finishing unit 26 after possible readjustment, and this drum shear 27 trims the leading and trailing edges of the pre-finished rolled product 52 to facilitate entry of the pre-finished rolled product 52 into the stands of the finishing unit 31 and to reduce the chance of kobble formation, particularly when producing a final strip having a thickness of less than 3.0 mm.

[0086] However, in one variant, the shear 94 could be replaced by an alternative cutting machine having different dimensions and functions than the drum shear 27 originally provided in the plant 100, and the present invention does not exclude such variants.

[0087] The method of the present invention also includes locating a high rate heating device 28 between the pre-finishing unit 26 and the finishing unit 31 of the modified rolling mill train.

[0088] Preferably, the rapid heating device 28 includes, for example, an induction furnace located downstream from the flying shear 27 and includes selectively operable elements, which may be operable independently of one another.

[0089] The high rate heater 28 is configured to selectively and adjustably heat the prefinished rolled product 52 before it enters the finishing stand 31 .

[0090] The temperature to which the pre-finished rolled product 52 is heated is selected depending at least in part on the thickness of the pre-finished rolled product 52 and the final thickness of the final strip P so that at the exit of the finishing unit 31, in particular at the exit of the last finishing stand, the final strip P has an optimum temperature of at least 830°C.

[0091] By way of example only, the temperature to which the pre-finished rolled product 52 is heated, i.e., the temperature at which the pre-finished rolled product 52 exits the high-speed heating device 28, advantageously reaches a value of about 1000°C to about 1100°C, or in any case, depending on the operating and product parameters, the temperature of the final zone at the exit of the last finishing stand 31 reaches a temperature of at least 830°C.

[0092] As a result, the rolling mass flow rate MF required to achieve the above-mentioned optimum temperature of at least 830°C, for example, a temperature of 830°C to 900°C, at the outlet of the last stand of the finishing unit 31 is L The value of can be reduced.

[0093] Rolling mass flow rate MF L By reducing the rolling speed V LBy reducing the rolling speed, preferably to less than 12 m / s, it is possible to reach an optimum temperature of at least 830°C at the exit of the rolling mill train 25, even at the trailing edge of the final strip P, thereby eliminating the need for "speeding up" as a tool to reach the target temperature. An example of this embodiment is shown diagrammatically in the graph of Figure 7.

[0094] Advantageously, in the absence of speed-up, the rolling speed V in the finishing stand 31 L is kept substantially constant to maintain a constant temperature between the leading edge and the trailing edge of the final zone P, and the optimum temperature control (e.g., thermochemical treatment) can be selected depending on the steel grade and the use of the final zone P.

[0095] Another advantage of not speeding up is that it allows for both a high degree of control over the final shape of the final band P, for example high degree of control over the crown and flatness of the final band P, and a high degree of control over the mechanical properties of the final band P, the former being advantageously uniform over the entire length of the coil, and the latter being advantageously constant and uniform over the entire length of the coil.

[0096] This last advantage, which was not realized in prior art plants, is very important, especially in the high-quality production of, for example, the final strip P to be moulded.

[0097] In some embodiments, it may be necessary to utilize speedups to allow for increased productivity of the line when manufacturing at very thin thicknesses, or to allow for very high productivity at other thicknesses, an example of which is shown graphically and schematically in Figure 8.

[0098] In addition to the original plant 100, a third water descaling device 29 is located downstream of the high-speed heater 28 and upstream of the finishing unit 31, and has the function of further cleaning the surface of the pre-finished rolled product of scale before the pre-finished rolled product enters the finishing stand.

[0099] This removes any scale formed on the surface of the pre-finished product and avoids quality defects in the rolled strip, such as scale indentations.

[0100] Downstream from the finishing unit 31, the cooling device 33 and shower 34 of the original plant 100 remain to cool the strip P.

[0101] Furthermore, two take-up reels 36, 38 are left at the exit of the shower 34 for winding up the strip P into coils for subsequent storage and removal.

[0102] It will be apparent that modifications and / or additions of parts may be made to the method for adapting a plant for producing flat rolled products described above without departing from the field and scope of the invention as defined in the appended claims.

[0103] It is also clear that although the invention has been described with reference to some specific examples, a person skilled in the art will certainly be able to achieve many other equivalents of the method for adapting a plant for producing flat rolled products having the features set out in the claims, all of which fall within the scope of protection set out in the claims.

[0104] In the appended claims, the purpose of the symbols in parentheses is only to improve readability and shall not be considered as limiting the scope of protection provided by the claims.

Claims

1. 1. A method for retrofitting an existing rolling plant (100) for producing a final strip (P) of defined starting thickness from a slab (50), comprising: The rolling plant (100) at least one furnace (16) configured to heat at least said slab (50) to a predetermined starting temperature; at least one reversible rough forming stand (23) configured to perform one or more rolling passes on the slab (50) to obtain an intermediate rolled product (51); a compact rolling mill train (25) operatively arranged alongside said at least one rough forming stand (23); It is equipped with The rolling mill train (25) comprises a plurality of finishing stands (31) arranged side by side with one another; the rolling mill train (25) is configured to reduce the thickness of the intermediate rolled product (51) until the final strip (P) having a specified final thickness is obtained; The method comprises the steps of: at least one step of modifying the rolling mill train (25) by moving at least one initial stand of the rolling mill train (25) away from the remaining stands downstream from the initial stand and closer to the rough-forming stand (23), dividing the rolling mill train (25) into a pre-finishing unit (26) located a minimum distance (D) from the rough-forming stand (23) so that the intermediate rolled product is not simultaneously operatively engaged with both stands (23, 26), and a finishing unit (31); at least one step of installing a high-speed heating device (28) consisting of selectively operable elements between the pre-finishing unit (26) and the finishing unit (31) for heating the pre-finished rolled product (51) as it leaves the pre-finishing unit (26) so that the temperature of the final zone (P) corresponding to the exit of the last stand of the finishing unit (31) is at least above 830°C even for a minimum thickness of less than 1.2 mm; operating the existing plant (100) by performing

2. In the changing step, the rolling mill train (25) is divided so that the number of stands in the pre-finishing unit (26) is 1 to 2 and the number of stands in the finishing unit (31) is 5 to 6. The method of claim 1.

3. The number of stands in the pre-finishing unit (26) is 2, and the number of stands in the finishing unit (31) is 5. The method of claim 2.

4. the at least one rough forming stand (23) is configured to define the intermediate rolled product (51) having a thickness of about 45 mm to about 80 mm; the pre-finishing unit (26) is configured to define the pre-finished rolled product (52) having a thickness of about 10 mm to about 50 mm; The finishing unit (31) is configured to define the final zone (P) having a predetermined final thickness of about 1 mm to about 26 mm.

4. The method according to any one of claims 1 to 3.

5. a third descaling means (29) disposed between the high-speed heating device (28) and the finishing unit (31); 5. The method according to any one of claims 1 to 4.

6. A cutting machine (27) is disposed between the pre-finishing unit (26) and the high-speed heating device (28).

6. The method according to any one of claims 1 to 5.

7. The specified start temperature of the slab is 1200°C or less; 7. The method according to any one of claims 1 to 6.

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