System and method for producing a rolled metal strip in continuous operation

Abstract

The invention relates to a system (1) for producing a rolled metal strip (2) in continuous operation, preferably a coupled casting and rolling system, wherein the system (1) has: at least one casting machine (10) which is designed to produce a metal strand and to transport the metal strand in a transport line; at least one roll stand group (17) which is designed to shape the metal strand into a corresponding metal strip (2) by rolling during transport along the transport line; a cooling device (18) which is arranged downstream of the last roll stand group (17) and is designed to cool the metal strip (2); and a flatness measuring roller (31) for measuring the flatness of the metal strip (2), said flatness measuring roller being arranged downstream of the cooling device (18).

Description

[0001] Hemmerich & Colleagues

[0002] Plant for the continuous production of a rolled metal strip

[0003] Technical field

[0004] The invention relates to a plant, in particular a coupled casting and rolling plant, and a method for producing a rolled metal strip in continuous operation.

[0005] Background of the invention

[0006] Combined casting and rolling plants are known for the production of metal strips, in which a cast strand is subjected to a single- or multi-stage rolling process using the casting heat.

[0007] A further development of such systems has become known as "Compact Strip Production" (CSP). The aim was to develop conventional continuous casting into "near-net-shape" casting, i.e., to cast the slabs so thin that only the minimum deformations necessary for material and forming reasons need to be applied in the rolling mill, thus reducing the size of the rolling stage(s). Typical dimensions of strips produced with a CSP system range from 0.8 to 25 mm in thickness and up to 2,200 mm in width.

[0008] Coupled casting and rolling mills can be designed for batch operation, semi-continuous operation, continuous operation, or for performing different operating modes. Batch operation refers to a mode of operation in which the strand exiting the casting machine is cut to a length corresponding to a specific future coil size. In batch operation, exactly one coil is produced from each individual slab.

[0009] Page 1 Hemmerich & Colleagues

[0010] Semi-continuous operation refers to a plant operating mode in which the strand, after leaving the casting machine, is cut to create a so-called jumbo slab, the length of which typically corresponds to an integer multiple of a slab produced in batch operation. In continuous operation, the production of slabs or multiples thereof during the casting / rolling process is omitted; that is, rolling is coupled with the casting machine.

[0011] One optimization goal for combined casting and rolling is to maximize the flatness of the metal strip to ensure trouble-free further processing and the desired product quality. For this purpose, the cooling of the rolled products following a hot rolling mill can be specifically controlled, thereby influencing, for example, the tendency of the metal strip to curl and / or warp.

[0012] In coupled casting and rolling mills without continuous production, an optical flatness measuring device can be used to measure the flatness of the metal strip when it is in a tension-free state. In continuous operation, such flatness measurement is not available, and achieving good flatness of the metal strip while simultaneously maintaining high strength is difficult.

[0013] Description of the invention

[0014] One object of the invention is to provide an improved system and an improved method for the production of a rolled metal strip in continuous operation, in particular to improve the quality of the produced metal strips.

[0015] The problem is solved by a system with the features of claim 1 and a method with the features of the dependent method claim. Advantageous further developments follow from the dependent claims, the following description of the invention, and the description of preferred embodiments.

[0016] Page 2 Hemmerich & Colleagues

[0017] The plant according to the invention is used for the production of rolled, in particular hot-rolled, metal strips, which is capable of continuous operation, i.e., is designed exclusively or additionally for continuous operation. Products made of a metal alloy, preferably steel, are cast and processed in this process. The plant is particularly preferably a CSP plant for the production and further processing of, in particular, thin strips.

[0018] The plant has at least one casting machine set up to produce a metal strand and transport it in a transport line.

[0019] The casting machine is preferably implemented as a vertical bending unit or as a sheet caster. However, it can also be implemented in other ways, as long as it provides a casting strand that can be subsequently processed without interruption, in particular rolled.

[0020] The plant has at least one rolling stand group which is set up to transform the cast metal strand into a corresponding metal strip by rolling during transport along the transport line.

[0021] The rolling stand group comprises one or more rolling stands in the usual manner, preferably each in a quarto configuration with two work rolls and two backup rolls. Particularly preferably, the rolling stand group is part of a hot rolling mill in which the forming of the metal strip takes place at least partially from the casting heat; that is, in this case, the metal strip does not cool completely after casting on its way to the rolling mill. The entire rolling mill can comprise several rolling stand groups, such as a roughing mill and a finishing mill.

[0022] Page 3 Hemmerich & Colleagues

[0023] The plant has a cooling device which is arranged and set up behind the last rolling stand group to cool the metal strip, in particular to cool it quickly.

[0024] Terms used to describe spatial relations, such as "in front", "behind", "between", "upstream", "downstream", "first", "last", etc., refer here to the direction of transport of the metal strip through the plant and are therefore unambiguous.

[0025] The system further includes a flatness measuring roller for measuring the flatness of the metal strip, which is arranged behind the cooling device (18). For this purpose, the flatness measuring roller is preferably configured to measure a force exerted on the flatness measuring roller by the at least slightly bent metal strip. The flatness measurement using the flatness measuring roller is carried out under tension of the metal strip in continuous operation.

[0026] After the final forming process by the rolling stand, the metal strip is cooled by the cooling device, in particular by rapid cooling, which results in high strength of the metal strip. The inventive combination of cooling and flatness measurement by the flatness measuring roller in continuous operation enables the production of a particularly high-quality metal strip.

[0027] Preferably, a temperature control device is arranged downstream of the casting machine, implemented, for example, as a roller hearth furnace and / or tunnel furnace and / or rapid heating device. The temperature control device is designed to increase and / or homogenize the temperature of the metal strip. In this way, the effect of the existing alloying elements on strength, toughness, and the control of microstructure formation processes (recrystallization, grain growth, and precipitation) can be optimized, and the rolling temperature of the continuous slab can be adjusted. These measures improve the mechanical properties of the rolled metal strip and thus its quality.

[0028] Page 4 Hemmerich & Colleagues

[0029] Preferably, the system comprises two rolling stands, i.e., a roughing and a finishing mill, wherein a further temperature control device, preferably a rapid heating unit, and particularly preferably an induction heater, is arranged between the two rolling stands, thereby further optimizing the temperature control of the metal strip and thus its properties. In particular, cooling effects from the slow process speed can be compensated for, and the metal strip can be fed to the second rolling stand at an advantageous rolling temperature.

[0030] Preferably, the system includes a cooling device, wherein the cooling device is designed and configured as a rapid cooling section to apply a coolant to both the top and bottom surfaces of the metal strip. The coolant ratio between the top and bottom surfaces of the metal strip is preferably adjustable, for example, by means of a flow control system. The cooling device, in particular the rapid cooling section, following the final forming process, influences the flatness of the metal strip, making the cooling device applicable in-line for optimizing flatness. Furthermore, by allowing adjustment of the coolant application across the width of the metal strip, unevenness that occurs, for example, only at the edge of the metal strip, can be minimized. Preferably, the coolant is water.

[0031] The rapid cooling section also plays a crucial role in determining the grain size of the finished rolled metal strip. Both flatness and grain size influence subsequent manufacturing steps, such as cold rolling and heat treatment. Therefore, the interaction and adjustment of the rapid cooling system, including its dimensions, positioning, and control, significantly impacts the setting of quality parameters.

[0032] Preferably, the end of the cooling system is located a maximum of 9 m behind the last forming operation by the last rolling stand group. Alternatively or additionally, the

[0033] Page 5 Hemmerich & Colleagues

[0034] The cooling system should preferably begin no more than 2 m behind the last forming operation by the last rolling stand group.

[0035] Preferably, the cooling device is configured such that the cooling rate is greater than 500 K / s, preferably greater than 700 K / s, and particularly preferably greater than 1,000 K / s, in order to achieve particularly rapid cooling, especially for thin metal strips with a thickness of, for example, approximately 2 mm. Preferably, a control device as described below is provided to control the cooling device accordingly, i.e., in accordance with the parameters above.

[0036] Preferably, the cooling device includes adjustment means for controlling the flow rate and / or pressure and / or pump output. These adjustment means allow for particularly quick and / or precise setting of the cooling rates. The adjustment means enable precise and individual setting of the cooling rates for the top and bottom surfaces of the metal strip over a specific section and duration.

[0037] Preferably, a squeezing roller is arranged between the cooling device and the flatness measuring roller, which is designed to remove any remaining coolant from the metal strip so that no coolant can run into the subsequent units.

[0038] Preferably, the flatness measuring roller is part of a measuring section that includes one or more other measuring devices, for example, for measuring the thickness and / or profile and / or temperature of the metal strip. The measuring position for the thickness measurement and / or profile measurement is preferably located a maximum of 10 m downstream of the last forming operation by the last rolling stand group and a maximum of 2 m downstream of the rapid cooling by the cooling device.

[0039] Preferably, the flatness measuring roller is installed in such a way that the flatness measurement can be carried out within a maximum of 14 m after the last forming operation.

[0040] Page 6 Hemmerich & Colleagues

[0041] Rolling stand group and / or a maximum of 8 m after cooling by the cooling device.

[0042] Preferably, a further cooling device, in particular a laminar cooling section, is arranged behind the flatness measuring roller. This cooling device is configured to apply a coolant to the top and / or bottom of the metal strip. It serves to cool the metal strip to the coil temperature. Preferably, the coolant is water.

[0043] Transverse spray nozzles can be arranged in front of the further cooling device, which in turn ensure that no coolant can run into the measuring section.

[0044] Temperature measuring devices can be installed along the process line in addition to the measuring section to monitor the temperature of the metal strip at different stages of production. For example, temperature measurements on the top and bottom of the metal strip after rapid cooling by the cooling unit can ensure that cooling is uniform on both sides of the metal strip.

[0045] Preferably, the system includes a control device that is set up to control and / or regulate the process operation of the system depending on process parameters.

[0046] The control device is preferably configured to determine the flatness of the metal strip based on sensor data from the flatness measuring roller and, depending on this, to regulate and / or control the cooling device, i.e., in particular to regulate the amount of coolant in the cooling device to improve the flatness of the metal strip.

[0047] By continuously measuring the flatness using the flatness measuring roller, the adjustment of the rapid cooling adjustment devices can be controlled.

[0048] Page 7 Hemmerich & Colleagues

[0049] Actuators are used to continuously regulate the flatness values ​​of the metal strip.

[0050] Uneven pressure distribution from the top to the bottom of the belt has proven to be very advantageous for achieving a flat belt surface.

[0051] The control unit may include or have access to models that, for example, calculate the flatness of the metal strip from the sensor data of the flatness measuring roller, calculate the temperature and / or adjust the coolant distribution in the cooling equipment.

[0052] In conjunction with at least two models, preferably a flatness model and / or a thermal and / or a metallurgical model, the control unit can compare quality specifications for microstructure adjustment with those for flatness adjustment. This allows potentially conflicting control parameters to be weighted and / or interpolated to optimize coolant distribution.

[0053] The aforementioned problem is further solved by a method for producing a rolled metal strip in continuous operation, preferably in a coupled casting and rolling plant, wherein the method comprises: generating a metal strand by means of a casting machine and transporting the metal strand along a transport line; during the transport of the metal strand along the transport line, forming the metal strand by rolling it into a corresponding metal strip by means of at least one rolling stand group; cooling the metal strip by means of a cooling device arranged behind the last rolling stand group; and measuring the flatness of the metal strip by means of a flatness measuring roller arranged behind the cooling device.

[0054] The features, technical effects, advantages and examples of implementation described in relation to the plant apply analogously to the process.

[0055] Page 8 Hemmerich & Colleagues

[0056] 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 drawing.

[0057] Brief description of the character

[0058] Preferred further embodiments of the invention are explained in more detail by the following description of the figure. This shows:

[0059] Figure 1 schematically shows a plant for the production of metal strips, which can be operated in continuous operation.

[0060] Detailed description of preferred embodiments

[0061] Preferred embodiments are described below with reference to Figure 1, which schematically shows a plant 1 for the production of metal strips, preferably steel strips. Plant 1 is a hot strip mill, preferably a CSP mill, which is also designed for continuous operation.

[0062] The system 1 comprises one or more casting machines 10 and is equipped to further process the metal strands cast via the casting machine(s) 10 in continuous operation into metal strips 2, preferably thin strips, with a desired final thickness.

[0063] Behind the two exemplary parallel casting machines 10, shears 11 for dividing the metal strip 2 into slabs can be installed, provided that the

[0064] Page 9 Hemmerich & Colleagues

[0065] In addition to continuous operation, system 1 can also be operated in batch mode and / or semi-continuous mode.

[0066] The system 1 comprises at least one temperature control device 12, preferably implemented as a roller hearth furnace and / or tunnel furnace and / or rapid heating device, which is designed for reheating and equalizing the strip temperature. A second temperature control device 12 can also serve as a buffer for the upper casting machine 10 via a suitable diverter device.

[0067] Downstream of the temperature control device(s) 12 and upstream of a first rolling stand group 14, a scale remover 13 can be installed to remove surface scale, thereby positively influencing the rolling process in the first group of rolling stands 14, in particular keeping it free from scale-related surface damage. Downstream of the first rolling stand group 14, a shear 15 can be arranged to scoop the strip heads and strip ends of the intermediate strip pre-rolled in the first rolling stand group 14, provided that the plant 1 is configured for batch and / or semi-continuous operation in addition to continuous operation, in order to facilitate threading the strip into a second rolling stand group 17.Furthermore, the shear 15 can serve to separate the rolling process within the first rolling stand group 14 from the rolling process in the second rolling stand group 17, particularly with regard to the entry speed of the intermediate strip into the second rolling stand group 17 after exiting the first rolling stand group 14.

[0068] Between the first rolling stand group 14 and the second rolling stand group 17, a further temperature control device, preferably in the form of a rapid heating device 16, for example an induction heater, can be arranged, which can preferably be removed from the rolling line when the further temperature control device is not required for carrying out the rolling process. This is regularly the case when the plant is operating in batch mode.

[0069] Page 10 Hemmerich & Kollegen is used, or when strips with comparatively large thicknesses of 2 to 2.5 mm are to be produced in semi-endless operation.

[0070] Downstream of the second rolling stand group 17, a cooling device 18, preferably implemented as a rapid cooling section, is arranged for setting the desired coiling temperature for the metal strip 2. The cooling device 18 is preferably provided with adjustable means for cooling the metal strip 2, preferably for applying water to the metal strip 2.

[0071] Between the cooling device 18 and one or more reels 20 a shear 19, preferably designed as a high-speed shear, is arranged for cutting the finished rolled metal strip 2 to the desired coil lengths.

[0072] Following the final forming of the metal strip 2 by the second rolling stand 17, rapid cooling is carried out by the cooling device 18. The cooling device 18 is configured to apply coolant to both the top and bottom surfaces of the metal strip 2, with the coolant ratio between the top and bottom surfaces being adjustable, for example, by means of flow control. The flow control can be implemented by using control valves, flow meters, pressure meters, frequency-controlled pump drives, etc. The end of the cooling device 18, i.e., the end of the rapid cooling, is preferably located a maximum of 9 m downstream of the final forming by the second rolling stand 17. The start of the rapid cooling is preferably located a maximum of 2 m downstream of the final forming by the second rolling stand 17. The cooling rates are preferably greater than 500 K / s, particularly for a thin metal strip 2 with a thickness of, for example, 2 mm.Preferably, the following applies: Cooling rate * thickness greater than 1000 K / s * mm. By allowing the coolant application across the width of the metal strip 2, unevenness, which may only occur at the edge of the metal strip 2, for example, can be minimized.

[0073] Page 11 Hemmerich & Colleagues

[0074] Following rapid cooling by the cooling device 18, a squeezing roller 21 preferably follows, which is designed to remove any remaining coolant from the metal strip 2 so that no coolant can run into the subsequent units.

[0075] The squeezing roller 21 is followed by a measuring section 30. ?in which one or more measuring devices 32 are installed, for example for measuring the thickness of the metal strip 2 and / or the profile and / or the temperature. The measuring position for the thickness measurement and / or profile measurement is preferably located a maximum of 10 m downstream of the last forming operation by the second rolling stand group 17 and preferably a maximum of 2 m downstream of the rapid cooling by the cooling device 18.

[0076] The measuring section 30 comprises a flatness measuring roller 31, which is configured to measure the force exerted on the flatness measuring roller 31 by the bent metal strip 2. The flatness of the metal strip 2 can then be determined from this measurement. The flatness measurement using the flatness measuring roller 31 is performed under tension in continuous operation. The metal strip 2 is wrapped or wound around a section of the flatness measuring roller 31, whereby the contact area between the metal strip 2 and the flatness measuring roller 31 can be quite small. The flatness measurement using the flatness measuring roller 31 is preferably performed within a maximum of 14 m after the last forming operation by the second rolling stand group 17 and within a maximum of 8 m after cooling by the cooling device 18.

[0077] Following the measuring section 30, a further cooling device 22, preferably implemented as laminar cooling, can be installed to cool the metal strip 2 to the coil temperature. Transverse spray nozzles (not shown in Figure 1) can be arranged upstream of the further cooling device 22, which in turn ensure that no coolant can flow into the measuring section 30.

[0078] Temperature measuring devices can be added to measuring section 30 along the

[0079] The process line must be installed to control the temperature of the metal strip 2.

[0080] Page 12 Hemmerich & Colleagues to monitor different stages of production. For example, temperature measurements on the top and bottom of the metal strip 2 after rapid cooling by the cooling device 18 can ensure that the cooling is uniform on both sides of the metal strip 2.

[0081] The system 1 includes a control unit 50, which communicates with the various components, actuators, measuring devices and the like, and is set up to control and / or regulate the process depending on process parameters.

[0082] The control unit 50 is connected via signal technology to the components of plant 1 to be controlled, regulated, and / or read out, specifically to the casting machine 10, the temperature control unit 12, the rolling stand groups 14 and 17, the rapid heating unit 16, the cooling units 18 and 22, the reel 20, and the measuring section 30. Communication between the control unit 50 and the plant components to be controlled, regulated, and / or read out can be wired or wireless, digital or analog. The control unit 50 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.The control unit 50 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. The control unit 50 can also communicate with lower-level plant control systems, i.e., control systems assigned to the respective facilities.

[0083] The control unit 50 includes or has access to models that, for example, calculate the flatness of the metal strip 2 from the sensor data of the flatness measuring roller 31, as well as models that control the metallurgical processes via the

[0084] Page 13 Hemmerich & Colleagues

[0085] Model the manufacturing process, as well as models that calculate the temperature and adjust the coolant distribution in the cooling devices 18, 22.

[0086] In particular, the control device 50 is designed to change the amount of coolant in the cooling device 18 (top / bottom) to improve the flatness of the metal strip 2.

[0087] The combination of rapid cooling by the cooling device 18 with flatness measurement by the flatness measuring roller 31 in continuous operation allows the production of a high-quality hot strip.

[0088] Where applicable, all individual features shown in the exemplary embodiments can be combined and / or exchanged without leaving the scope of the invention.

[0089] Page 14 Hemmerich & Colleagues

[0090] Reference symbol list

[0091] 1 Plant for the production of a metal strip

[0092] 2 metal bands

[0093] 10 Casting machine

[0094] 11 Scissors

[0095] 12 Temperature control device

[0096] 13 Tinderwashers

[0097] 14 First rolling stand group

[0098] 15 Scissors

[0099] 16 Rapid heating device Temperature control device

[0100] 17 Second rolling stand group

[0101] 18 Cooling unit

[0102] 19 Scissors

[0103] 20 reels

[0104] 21 Squeeze roller

[0105] 22 Cooling unit

[0106] 30 Measurement section

[0107] 31 Flatness measuring roller

[0108] 32 Measuring device

[0109] 50 Control unit

[0110] Page 15

Claims

Hemmerich & Colleagues Patent claims 1. Plant (1) for producing a rolled metal strip (2) in continuous operation, preferably a coupled casting and rolling plant, wherein the plant (1) comprises: at least one casting machine (10) configured to produce a metal strand and transport it in a transport line; at least one rolling stand group (17) configured to transform the metal strand into a corresponding metal strip (2) by rolling during transport along the transport line; a cooling device (18) arranged downstream of the last rolling stand group (17) and configured to cool the metal strip (2); and a flatness measuring roller (31) for measuring the flatness of the metal strip (2), arranged downstream of the cooling device (18).

2. Plant (1) according to claim 1 , characterized in that a temperature control device (12), preferably implemented as a roller hearth furnace and / or tunnel furnace and / or rapid heating device, is arranged and set up behind the casting machine (10) to increase and / or equalize the temperature of the metal strip (2).

3. Plant (1) according to claim 1 or 2, characterized in that two rolling stand groups (14, 17) are provided, wherein a further temperature control device, preferably a rapid heating device (16), particularly preferably an induction heater, is arranged between the two rolling stand groups (14, 17). Page 16 Hemmerich & Colleagues 4. Plant (1) according to one of the preceding claims, characterized in that the cooling device (18) is designed and configured as a rapid cooling section to apply a coolant to both the top and bottom of the metal strip (2), wherein the coolant ratio between the top and bottom of the metal strip (2) is preferably adjustable.

5. Plant (1) according to one of the preceding claims, characterized in that the end of the cooling device (18) is located a maximum of 9 m behind the last forming operation by the last rolling stand group (17) and / or the beginning of the cooling device (18) is located a maximum of 2 m behind the last forming operation by the last rolling stand group (17).

6. Plant (1) according to one of the preceding claims, characterized in that the cooling device (18) is configured such that the cooling rate is greater than 500 K / s, preferably greater than 700 K / s, most preferably greater than 1,000 K / s.

7. System according to claim 6, characterized in that the cooling device (18) has adjusting means for adjusting the flow rate and / or the pressure and / or the pump power.

8. Plant (1) according to one of the preceding claims, characterized in that a squeezing roller (21) is arranged between the cooling device (18) and the flatness measuring roller (31), which is designed to remove any remaining coolant from the metal strip (2).

9. Plant (1) according to one of the preceding claims, characterized in that the flatness measuring roller (31) is part of a measuring section (30) which has one or more further measuring devices (32), preferably for measuring the thickness and / or the profile and / or the temperature of the metal strip (2). Page 17 Hemmerich & Colleagues 10. Plant (1) according to one of the preceding claims, characterized in that the flatness measuring roller (31) is installed such that the flatness measurement is carried out within a maximum of 14 m after the last forming by the last rolling stand group (17) and / or a maximum of 8 m after cooling by the cooling device (18).

11. Plant (1) according to one of the preceding claims, characterized in that a further cooling device (22) is arranged behind the flatness measuring roller (31), which is preferably designed and configured as a laminar cooling section to apply a coolant to the top and / or the bottom of the metal strip (2).

12. Plant (1) according to one of the preceding claims, characterized by a control device (50) which is configured to determine the flatness of the metal strip (2) on the basis of sensor data from the flatness measuring roller (31) and, depending on this, to regulate and / or control the cooling device (18), preferably to regulate the coolant quantity in the cooling device (18) and / or in the further cooling device (22).

13. Method for producing a rolled metal strip (2) in continuous operation, preferably in a coupled casting and rolling plant, wherein the method comprises: Producing a metal strand using a casting machine (10) and transporting the metal strand along a transport line; during the transport of the metal strand along the transport line, forming the metal strand by rolling it into a corresponding metal strip (2) using at least one rolling stand group (17); Page 18 Hemmerich & Colleagues Cooling of the metal strip (2) by means of a cooling device (18) which is arranged behind the last rolling stand group (17); and Measuring the flatness of the metal strip (2) using a flatness measuring roller (31) which is arranged behind the cooling device (18).

14. Method according to claim 13, characterized in that the flatness of the metal strip (2) is determined on the basis of sensor data from the flatness measuring roller (31) and the cooling device (18) is regulated and / or controlled depending on this.

15. Method according to claim 13 or 14, characterized in that the method is carried out with a system according to one of claims 2 to 12. Page 19

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