Apparatus and method for producing flat-rolled products

Abstract

The invention relates to an apparatus (1) and to a method for producing flat-rolled products from metal slabs, preferably thick slabs having a thickness of at least 140 mm, wherein the apparatus (1) comprises: at least one casting machine (10) which is designed to cast a strand from a metal, preferably steel; a transport device (30) which is designed to transport the strand in a transport direction along a transport line (T); a separating device (14) which is arranged downstream of the casting machine (10) in the transport line (T) and is designed to separate the strand into individual slabs; a rolling device (50) which is arranged downstream of the separating device (14) in the transport line (T) and is designed to roll each slab into a flat-rolled product; a temperature setting system (20) comprising an induction heating device (22) which is arranged between the separating device (14) and the rolling device (50) and is designed to heat the slabs to a hot-rolling temperature; and a control device (100) which is in communication with the induction heating device (22) and is designed to actuate the induction heating device (22) such that each slab is heated in a non-uniform manner along its longitudinal extent.

Description

[0001] Apparatus and method for the production of flat rolled products

[0002] Technical field

[0003] The invention relates to a device and a method for producing flat rolled products from metal slabs, preferably thick slabs with a thickness of at least 140 mm.

[0004] Background of the invention

[0005] Combined casting and rolling plants are known for the production of metal strips, in which a cast strand is subsequently subjected to a single- or multi-stage rolling process. The rolling process can take place immediately after casting, partially utilizing the casting heat, or after intermediate storage in a slab storage area.

[0006] When casting and further processing slabs with a thickness of at least 140 mm, also referred to here as "thick slabs," conventional walking beam furnaces or other gas-fired furnaces are used to bring the thick slabs to the temperature required for forming in the rolling mill. The slabs are placed in the furnace either at a temperature elevated from the casting process ("hot loading"), for example, approximately 600°C, or at ambient or room temperature ("cold loading"). Both hot and cold loading require additional energy. It is important to note that the rolling temperature should generally not fall below 900°C, as otherwise the microstructure transformation begins and the risk of cracking in the metal strips increases.

[0007] It is known to use induction heaters instead of or in addition to gas-fired furnaces to heat the slabs before forming.

[0008] to heat up page 1. WO 2023 / 052500 A1 describes a plant for the production of flat rolled products from thick cast steel and / or non-ferrous metal slabs, comprising an electric / inductive heating device arranged upstream of a hot rolling mill.

[0009] It is possible for the slabs to be transported at different speeds on the system. For example, a higher speed can be used on the roller conveyor following the heating unit to reduce heat loss. The higher the transport speed, the shorter the transport time and the less thermal energy is lost. A slightly slower speed can be used in the induction heating unit to supply more energy to the slabs.

[0010] However, such a flexible driving style can lead to the slabs exhibiting an inhomogeneous temperature distribution along their length before entering the rolling mill. For example, when the slab head enters the induction heater and is heated, the slab end is still outside the heater and cools down. Conversely, when the slab head leaves the front end of the induction heater, it cools down while the rear part of the slab continues to heat up.

[0011] Description of the invention

[0012] One object of the present invention is to provide an improved apparatus and an improved method for producing flat rolled products from metal slabs.

[0013] The problem is solved by a device with the features of claim 1 and a method with the features of the dependent method claim. Advantageous further developments follow from the

[0014] Page 2 contains the dependent claims, the following description of the invention and the description of preferred embodiments.

[0015] The device according to the invention is used for the production of flat rolled products from slabs, i.e., rolled, in particular hot-rolled, slabs. The products cast and processed are made of a metal or a metal alloy, preferably steel. The device is particularly preferably designed for processing thick slabs with a thickness of at least 140 mm, in particular at least 150 mm or at least 160 mm.

[0016] The device comprises at least one casting machine configured to cast a continuous material, preferably continuously. The casting machine can be implemented as a vertical bending machine, a sheet caster, or in another manner, as long as it provides a continuous material that can subsequently be further processed, in particular divided into slabs and rolled.

[0017] During processing, the stranded material, as well as the slabs and flat-rolled products produced from it, are transported in one direction along a transport line by means of a transport device. For this purpose, the transport device typically includes a roller conveyor.

[0018] Terms used to describe spatial relations, such as "in front", "behind", "between", "upstream", "downstream", etc., refer here to the direction of transport of the stranded material or slabs through the device during its intended use and are therefore unambiguous.

[0019] The device comprises a separating device, which is arranged and set up in the transport line downstream of the casting machine to separate the strand material into individual slabs, and a rolling device, which is arranged and set up in the transport line downstream of the separating device to roll the slabs into flat rolled products.

[0020] Page 3 The rolling mill comprises one or more rolling stands in the usual manner, preferably each in a quarto configuration with two work rolls and two backup rolls, and can be operated in reverse and / or tandem mode. The rolling mill is particularly preferably designed for hot rolling of the slabs. The entire rolling mill can comprise several rolling stand groups, such as a roughing mill and a finishing mill.

[0021] The device further comprises a temperature control system with an induction heating device arranged and configured between the cutting device and the rolling device to heat the slabs to a hot-rolling temperature, preferably 950 to 1,250°C, more preferably 1,000 to 1,200°C, and more preferably 1,050 to 1,150°C, and a control device communicating with the induction heating device and configured to control the induction heating device so that the respective slab is heated inhomogeneously along its length. In other words, the heating of the slab by the induction heating device is carried out in such a way that, after the heating process is complete, a temperature variation, in particular a temperature gradient, is present along the length of the slab.

[0022] Various optimization goals can be pursued through the inhomogeneous heating of the slab by the induction heating system. For example, the temperature distribution of the slab can be adjusted / optimized, and in particular homogenized, for a later processing stage, such as for forming by the rolling mill. Alternatively or additionally, the inhomogeneous temperature control by the induction heating system can contribute to a reduction in energy consumption and / or increased plant availability.

[0023] Page 4 Preferably, the control device is configured to control the induction heating device in such a way that the inhomogeneous heating of the slab by the induction heating device leads to a homogenization of the temperature distribution (along the longitudinal extent of the slab), in particular to a substantially homogeneous temperature distribution, in the rolling mill. In this way, a consistently high quality of the flat rolled products produced in this way can be ensured.

[0024] Preferably, the rolling mill comprises a roughing mill, in particular designed as a reversing rolling stand, and a finishing mill, which in particular has several rolling stands operated in tandem.

[0025] In this case, the control device is preferably configured to control the induction heating device in such a way that the inhomogeneous heating of the slab by the induction heating device leads to a homogenization of the temperature distribution, preferably to a substantially homogeneous temperature distribution, at the inlet of the finishing line.

[0026] Preferably, the transport device is configured to transport the slabs along the transport line in sections at different speeds. For example, the slabs can be transported from the cutting device to the induction heating device at a speed greater than 10 m / min, preferably greater than 20 m / min, and more preferably greater than 30 m / min. Alternatively or additionally, the slabs can be transported at a speed of less than 30 m / min, preferably less than 20 m / min, and more preferably less than 10 m / min, as they pass through the induction heating device. Alternatively or additionally, the slabs can be transported after the induction heating device at a speed greater than 20 m / min, preferably more than 40 m / min, and more preferably more than 60 m / min, for example, to minimize thermal loss up to the rolling mill and during the

[0027] Page 5 To reduce forming. In order to compensate for the resulting different cooling times along the longitudinal extent of the slab, the induction heating device can be controlled according to the description above, thereby allowing for more flexible transport speeds, for example to increase throughput and / or to reduce thermal losses, without compromising production quality.

[0028] Preferably, the temperature control system comprises one or more thermal insulation hoods arranged and configured in front of and / or behind the induction heating device to reduce the thermal losses of the slabs.

[0029] Preferably, the control device is configured to control the induction heating device in such a way that the front section of the slab, i.e. the slab head, viewed in the transport direction along the transport line, is heated more than the rear section of the slab, i.e. the slab end, thereby achieving a homogenization of the temperature distribution along the longitudinal extent of the slab for rolling in the rolling mill, in particular the finishing mill.

[0030] The aforementioned problem is further solved by a method for producing flat rolled products from metal slabs, preferably thick slabs with a thickness of at least 140 mm, in particular at least 150 mm or at least 160 mm, wherein the method comprises: casting a continuous stock from a metal, preferably steel, by means of a casting machine and transporting the continuous stock in one transport direction along a transport line by means of a transport device; separating the continuous stock downstream of the casting machine into individual slabs by means of a separating device; rolling the slabs downstream of the separating device into one flat rolled product each by means of a rolling device; before rolling, heating the slabs to a hot rolling temperature by means of an induction heating device

[0031] Page 6 Temperature control system; wherein the respective slab is heated inhomogeneously along its longitudinal extent by the induction heating device.

[0032] The features, technical effects, advantages and embodiments described in relation to the device apply analogously to the method.

[0033] For the reasons mentioned above, the inhomogeneous heating of the slab by the induction heating device is preferably carried out in such a way that it leads to a homogenization of the temperature distribution, preferably to a substantially homogeneous temperature distribution, in the rolling mill.

[0034] Preferably, the slabs are pre-rolled in a roughing mill of the rolling mill, in particular reversing, and finished-rolled in a finishing mill of the rolling mill, in particular by means of several rolling stands operated in tandem.

[0035] Preferably, for the reasons mentioned above, the inhomogeneous heating of the slab by the induction heating device is carried out in such a way that it leads to a homogenization of the temperature distribution, in particular to a substantially homogeneous temperature distribution, at the inlet of the finishing line.

[0036] Preferably, for the reasons mentioned above, the slabs are transported section by section at different speeds along the transport line by the transport device. For example, the slabs can be transported from the cutting device to the induction heating device at a transport speed greater than 10 m / min, preferably greater than 20 m / min, and more preferably greater than 30 m / min. Alternatively or additionally, the slabs can be transported at a different speed at the

[0037] Page 7. The slabs are transported through the induction heating device at a speed of less than 30 m / min, preferably less than 20 m / min, and more preferably less than 10 m / min. Alternatively or additionally, the slabs can be transported after the induction heating device at a speed of more than 20 m / min, preferably more than 40 m / min, and more preferably more than 60 m / min.

[0038] Preferably, the slabs are heated by the induction heating device to a temperature of 950 to 1,250°C, preferably 1,000 to 1,200°C, more preferably 1,050 to 1,150°C.

[0039] Preferably, for the reasons mentioned above, the front section of the slab, viewed in the direction of transport along the transport line, is heated more strongly by the induction heating device than the rear section of the slab.

[0040] Further advantages and features of the present invention will become apparent from the following description of preferred embodiments. The features described therein can be implemented individually or in combination with one or more of the features set out above, provided that the features do not contradict each other. The following description of preferred embodiments is given with reference to the accompanying drawings.

[0041] Brief description of the characters

[0042] Preferred further embodiments of the invention are explained in more detail by the following description of the figures. These show:

[0043] Figure 1 schematically shows a plant for the production of metal strips, comprising a casting machine, a temperature control system and a rolling device;

[0044] Page 8 Figure 2 is a graphical representation of a simulated process flow, where the x-axis denotes the position in the plant along the transport line, starting from the casting machine, and the y-axis denotes the transport speed as a function of the plant position; and

[0045] Figure 3 is a graphical representation of a simulated process flow, where the x-axis represents the position in the plant along the transport line, starting from the casting machine, and the y-axis represents the slab temperature as a function of the plant position.

[0046] Detailed description of preferred embodiments

[0047] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the figures are designated with identical reference numerals, and repeated descriptions of these elements are sometimes omitted to avoid redundancy.

[0048] Figure 1 schematically shows a device 1 for producing flat rolled products from metal slabs, comprising steel and / or non-ferrous metal slabs. The device 1 is particularly preferably configured for processing thick slabs with a thickness of at least 140 mm, and especially at least 150 mm or 160 mm. The "slab thickness" is defined as the dimension of the slab that is perpendicular to both its longitudinal extent and its width.

[0049] The device 1 comprises at least one casting machine 10 configured to cast a continuous material. The casting machine 10 is preferably implemented as a vertical bending machine or as a sheet caster. However, the casting machine 10 can also be implemented in another way, as long as it

[0050] Page 9 provides a strand material that can subsequently be cut into slabs and further processed.

[0051] Following casting, the extruded material is transported along a transport line T by a transport device 30. The transport device 30 typically includes a roller conveyor on which the extruded material, as well as the slabs and flat-rolled products produced from it, are transported along the transport line T.

[0052] The device 1 further comprises a cutting device 14, which is arranged in the transport line T downstream of the casting machine 10. The cutting device 14 serves to cut or divide the strand material into slabs. The cut is made along the slab thickness. The cutting device 14 is configured to cut the strand material during its conveyance along the transport line. The cutting device 14 is preferably designed as a pendulum shear.

[0053] A temperature control system 20 is connected to the separating device 14 of the device 1. In this embodiment, the system comprises thermal insulation hoods 21 and an induction heating device 22. The induction heating device 22 is mandatory, while the thermal insulation hoods 21 can be installed in front of and / or behind the induction heating device 22 as needed to reduce the thermal loss of the slabs during transport.

[0054] The device 1 further comprises a rolling mill 50, which is in particular a hot rolling mill. The rolling mill 50 has one or more rolling stands 51, preferably each in a quarto configuration with two work rolls forming the roll gap and two backup rolls, and can be operated in reverse and / or in tandem.

[0055] Page 10 The rolling mill 50 can comprise a roughing mill 55 and a finishing mill 56, as shown in the embodiment of Figures 2 and 3. The roughing mill can be designed as a reversing rolling stand, while the finishing mill comprises several rolling stands 51 operated in tandem.

[0056] During the rolling process in the rolling mill 50, the temperatures of the slabs decrease through radiation and cooling. The rolled material then enters a cooling section or cooling unit 60, the cooling parameters of which are set such that the rolled material is rapidly cooled to temperatures within an interval of, for example, 400 to 750°C, preferably in the range of 550 to 650°C. The cooling unit 60 can include cooling beams 61 with water cooling, although other cooling concepts are also possible.

[0057] The rolled and heat-treated slabs are then wound onto reels in a reeling device 70.

[0058] The device 1 further comprises a control unit 100 which communicates with the various assemblies, actuators, sensors and the like and is set up to control and / or regulate the process depending on process parameters.

[0059] The control unit 100 is connected via signal technology to the components of the device 1 to be controlled, regulated, and / or read out, and thus in particular to the casting machine 10, the temperature control system 20, the rolling mill 50, the cooling unit 60, and the reeling unit 70. Communication between the control unit 100 and the system components to be controlled, regulated, and / or read out can be wired or wireless, digital or analog. The control unit 100 can accordingly receive and / or send signals (control signals, data, etc.), whereby both unidirectional and bidirectional signal transmission falls under the term "communication" in this context.

[0060] Page 11 Control unit 100 does not necessarily have to be implemented by a central computer or electronic control system; rather, it includes decentralized and / or multi-stage systems, control networks, cloud systems, and the like. The control unit can also be an integral part of a higher-level plant control system or communicate with one. Control unit 100 can also communicate with lower-level plant control systems, i.e., control systems assigned to the respective facilities.

[0061] The thermal insulation hoods 21 minimize energy and temperature losses of the slabs on the transport line T to the rolling mill 50. Nevertheless, the slabs still cool down to a certain extent despite the thermal shielding. The temperature control system 20 therefore includes the induction heating device 22, which heats the slabs to a desired target temperature of, for example, 950 to 1,250°C, preferably 1,000 to 1,200°C, and more preferably 1,050 to 1,150°C, within a short time. The induction heating device 22 is preferably designed as a longitudinal field inductor.

[0062] The transport device 30 is preferably configured such that the slabs can be transported at different speeds in sections along the transport line T. For example, the slabs can be transported from the separating device 14 to the induction heating device 22 at a transport speed greater than 10 m / min, preferably greater than 20 m / min, and more preferably greater than 30 m / min. Alternatively or additionally, the slabs can be transported at a transport speed of less than 30 m / min, preferably less than 20 m / min, and more preferably less than 10 m / min, as they pass through the induction heating device 22. Alternatively or additionally, the slabs can be transported at a transport speed of more than 20 m / min, preferably more than 40 m / min, and more preferably more than 60 m / min, following the

[0063] Page 12 Induction heating device 22 are transported to reduce thermal loss up to the rolling device 50 and during forming.

[0064] Figure 2 shows an example graphical representation of a simulated process flow, where the x-axis denotes the position in the plant along the transport line T in mm, starting from the casting machine 10, and the y-axis denotes the transport speed in m / s as a function of the plant position. The speeds for the slab head and the slab end are shown. As can be seen from the example in Figure 2, the slab as a whole is accelerated after the induction heating unit 22, and the speeds of the slab head and the slab end diverge during the rolling process due to elongation.

[0065] The diverging transport speeds between the slab head and end mean that the time the slab takes to travel from the induction heating unit 22 to the rolling mill 50 (specifically to the finishing mill 56) varies along the slab's length. In this example, the slab end cools down longer than the slab head before entering the finishing mill 56. In other words, the transport time from the induction heating unit 22 to the forming process in the rolling mill 50 is a function of the coordinates along the slab's longitudinal extent.

[0066] To compensate for the resulting different cooling times along the longitudinal extent of the slab, the induction heating device 22 can be controlled accordingly.

[0067] Figure 3 shows a graphical representation of the slab's temperature profile. The plant position is plotted along the x-axis, while the y-axis represents the slab temperature in °C. Curves for the slab head and slab end are again shown.

[0068] Page 13 In the example shown in Figure 3, the induction heating device 22 is controlled by the control unit 100 such that the slab head is heated more than the slab end. This results in a substantially homogeneous temperature distribution along the longitudinal extent of the slab in the further course of the process, including in particular the finish rolling in the finishing mill 56.

[0069] The induction heating device 22 allows inhomogeneous heating of the slab (along its longitudinal extent), so that a more homogeneous, preferably substantially homogeneous, temperature distribution over the slab length is achieved in the rolling mill 50, in particular at the inlet of the finishing mill 56.

[0070] In addition to homogenizing the temperature distribution at a later processing stage, alternative or additional optimization goals can be pursued through the inhomogeneous heating of the slab by the induction heating unit 22. For example, the inhomogeneous heating of the slab can lead to a reduction in energy consumption and / or higher plant availability.

[0071] Where applicable, all individual features shown in the exemplary embodiments can be combined and / or exchanged without leaving the scope of the invention.

[0072] Page 14 Reference List

[0073] 1 Device for the production of metal strips

[0074] 10 Casting machine

[0075] 14 Separating device

[0076] 20 Temperature setting system

[0077] 21 Thermal insulation hood

[0078] 22 Induction heating device

[0079] 30 T transport equipment

[0080] 50 rolling mill

[0081] 51 Rolling mill

[0082] 55 Vorstraße

[0083] 56 Finishing Road

[0084] 60 Cooling unit

[0085] 61 cooling beams

[0086] 70 reel unit

[0087] 100 Control unit

[0088] T Transport line

[0089] Page 15

Claims

Patent claims 1. Device (1) for producing flat rolled products from metal slabs, preferably thick slabs with a thickness of at least 140 mm, wherein the device (1) comprises: at least one casting machine (10) configured to cast a continuous product from a metal, preferably steel; a transport device (30) configured to transport the continuous product in one transport direction along a transport line (T); a cutting device (14) arranged in the transport line (T) downstream of the casting machine (10) and configured to cut the continuous product into individual slabs; a rolling device (50) arranged in the transport line (T) downstream of the cutting device (14) and configured to roll the slabs into flat rolled products;a temperature control system (20) with an induction heating device (22) arranged and configured between the cutting device (14) and the rolling device (50) to heat the slabs to a hot rolling temperature; and a control device (100) communicating with the induction heating device (22) and configured to control the induction heating device (22) so that the respective slab is heated inhomogeneously along its longitudinal extent. Page 16 2. Device (1) according to claim 1 , characterized in that the control device (100) is configured to control the induction heating device (22) in such a way that the inhomogeneous heating of the slab by the induction heating device (22) leads to a homogenization of the temperature distribution, preferably to a substantially homogeneous temperature distribution, in the rolling device (50).

3. Device (1 ) according to claim 1 or 2, characterized in that the rolling mill (50) comprises a roughing mill (55), preferably designed as a reversing rolling stand, and a finishing mill (56), which preferably comprises several rolling stands (51 ) operated in tandem.

4. Device (1) according to claims 2 and 3, characterized in that the control device (100) is configured to control the induction heating device (22) in such a way that the inhomogeneous heating of the slab by the induction heating device (22) leads to a homogenization of the temperature distribution, preferably to a substantially homogeneous temperature distribution, at the inlet of the finishing line (56).

5. Device (1) according to one of the preceding claims, characterized in that the transport device (30) is configured to transport the slabs section by section along the transport line (T) at different speeds, preferably with a transport speed of greater than 10 m / min, more preferably greater than 20 m / min or greater than 30 m / min, from the separating device (14) to the induction heating device (22) and / or with a transport speed when passing through the induction heating device (22) of less than 30 m / min, more preferably less than 20 m / min or less than 10 m / min, and / or with a transport speed of more than 20 m / min, more preferably more than 40 m / min or 60 m / min, following the induction heating device (22). Page 17 6. Device (1) according to one of the preceding claims, characterized in that the temperature control system (20) has one or more thermal insulation hoods (21) which are arranged and configured in front of and / or behind the induction heating device (22) to reduce the thermal losses of the slabs.

7. Device (1) according to one of the preceding claims, characterized in that the induction heating device (22) is configured to heat the slabs to a temperature of 950 to 1,250°C, preferably 1,000 to 1,200°C, more preferably 1,050 to 1,150°C.

8. Device (1) according to one of the preceding claims, characterized in that the control device (100) is configured to control the induction heating device (22) in such a way that the front section of the slab, viewed in the direction of transport along the transport line (T), is heated more than the rear section of the slab.

9. Method (1) for producing flat rolled products from metal slabs, preferably thick slabs with a thickness of at least 140 mm, wherein the method comprises: Casting a stranded material from a metal, preferably steel, using a casting machine (10) and transporting the stranded material in a transport direction along a transport line (T) using a transport device (30); Separating the strand material downstream of the casting machine into individual slabs by means of a separation device (14); Page 18 Rolling the slabs downstream of the cutting device (14) into one flat rolled product each by means of a rolling device (50); prior to rolling, heating the slabs to a hot rolling temperature by means of an induction heating device (22) of a temperature control system (20); wherein the respective slab is heated inhomogeneously along its longitudinal extent by the induction heating device (22).

10. Method according to claim 9, characterized in that the inhomogeneous heating of the slab by the induction heating device (22) is carried out in such a way that it leads to a homogenization of the temperature distribution, preferably to a substantially homogeneous temperature distribution, in the rolling device (50).

11. Method according to claim 9 or 10, characterized in that the slabs are pre-rolled in a roughing mill (55) of the rolling mill (50), preferably reversing, and are finish-rolled in a finishing mill (56) of the rolling mill (50), preferably by means of several rolling stands (51) operated in tandem.

12. Method according to claims 10 and 11, characterized in that the inhomogeneous heating of the slab by the induction heating device (22) is carried out in such a way that it leads to a homogenization of the temperature distribution, preferably to a substantially homogeneous temperature distribution, at the inlet of the finishing line (56).

13. Method according to one of claims 9 to 12 characterized in that the slabs are transported section by section at different speeds by the transport device (30) along the transport line (T). Page 19 are transported, preferably at a transport speed of greater than 10 m / min, more preferably greater than 20 m / min or greater than 30 m / min, from the separating device (14) to the induction heating device (22) and / or at a transport speed when passing through the induction heating device (22) of less than 30 m / min, more preferably less than 20 m / min or less than 10 m / min, and / or at a transport speed of more than 20 m / min, more preferably more than 40 m / min or 60 m / min, following the induction heating device (22).

14. Method according to one of claims 9 to 13, characterized in that the slabs are heated by the induction heating device (22) to a temperature of 950 to 1250°C, preferably 1000 to 1200°C, more preferably 1050 to 1150°C.

15. Method according to one of claims 9 to 14, characterized in that the front section of the slab, viewed in the direction of transport along the transport line (T), is heated more strongly by the induction heating device (22) than the rear section of the slab. Page 20

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