EP4650063A1 - Finishing temperature adjustment in endless belt production - Google Patents

Abstract

The present invention relates to a method for setting a final rolling temperature during the continuous rolling of a cast metal strand (14) into hot-rolled strip (12) in a casting and rolling mill (10) with a single rolling stand group (50), as well as to a casting and rolling mill (10) for the continuous production of hot-rolled strip (12). Starting from a current operating state (B) of the casting and rolling mill (10) with a casting machine (20) and the single rolling stand group (50), the final rolling temperature is set such that it lies within a predetermined final rolling temperature window. For this purpose, at least one of the following casting machine parameters is selectively adjusted: i) a casting thickness; ii) a casting speed; iii) a secondary cooling capacity. Alternatively or additionally, a rolling stand (51, 52, 53, 54, 55, 56) of the rolling stand group (50) is selectively opened or closed.

Description

field of technology

The present invention relates to a method for setting a final rolling temperature during the continuous rolling of a cast metal strand to hot strip in a casting and rolling plant with a single rolling stand group, and to a casting and rolling plant for the continuous production of hot strip.

State of the art

In so-called casting and rolling mills, the casting machine is coupled with one or more rolling mills, i.e., one or more groups of rolling stands, which allows the heat inherent in the freshly cast strand to be used for the rolling process. With such casting and rolling mills, it is particularly possible to roll very thin metal strips, so-called hot strips, in continuous operation, which cannot be produced by conventional hot rolling due to the batch nature of the process.

In hot rolling, the so-called final rolling temperature, i.e. the temperature after the last active rolling stand of the rolling mill(s), is an important - if not the most important - factor for the formation of the microstructure in the finished hot-rolled strip and thus the (desired) mechanical properties.

In continuous strip production in a casting and rolling mill, the mass flow is largely constant along the entire length of the mill. Therefore, the resulting rolled strip can only be conveyed through the mill at a speed dependent on the mass flow from the casting machine. In particular, the cast metal strand cannot be arbitrarily accelerated or decelerated to influence the time between exiting the casting machine and reaching the rolling stand(s), and thus the associated heat loss—and consequently, the final rolling temperature. Therefore, conventional casting and rolling mills typically incorporate heating and cooling units to precisely control the final rolling temperature.

A particular disadvantage of such heating units is their high energy consumption, which negatively impacts the energy balance of the finished hot-rolled strip. Furthermore, such heating units increase the overall length of the plant.

Summary of the invention

It is an object of the present invention to improve the setting of the final rolling temperature in the continuous production of hot strip, in particular to enable an energy-efficient setting of the final rolling temperature.

This problem is solved by a method for setting a final rolling temperature during the continuous rolling of a cast metal strand to hot strip in a casting and rolling plant with a single rolling stand group and a casting and rolling plant for the continuous production of hot strip according to the independent claims.

Preferred embodiments are the subject of the dependent claims and the following description.

According to a first aspect of the invention, in the method for setting a final rolling temperature during the continuous rolling of a cast metal strand into hot strip in a casting mill with a single rolling stand group, the final rolling temperature is adjusted, in particular increased, from a current operating state of the casting mill with a casting machine and the single rolling stand group such that the final rolling temperature lies within a predetermined final rolling temperature window. For this purpose, at least one of the following casting machine parameters is selectively adjusted: i) a casting thickness; ii) a casting speed; iii) a secondary cooling capacity. Alternatively or additionally, a rolling stand of the rolling stand group is selectively opened or closed.

A casting thickness in the sense of the invention is preferably a thickness of the metal strand cast by means of the casting machine, i.e. exiting the casting machine.

A casting speed within the meaning of the invention is preferably a speed of the metal strand cast by means of the casting machine, i.e. exiting the casting machine.

A secondary cooling capacity within the meaning of the invention is preferably a cooling capacity with which a strand, which may not yet be completely solidified, is cooled in the area of the casting arc of the casting machine and, if applicable, in the horizontal section of the casting machine, in particular until it has completely solidified.

Opening or closing a rolling mill stand according to the invention preferably involves engaging the rolls of the rolling mill stand with the metal strand or strip, or disengaging them. Thus, the metal strand or strip can pass through an open rolling mill stand without thickness reduction, whereas the metal strand or strip undergoes a thickness reduction when passing through a closed rolling mill stand.

A targeted adjustment of a casting machine parameter and/or a targeted opening or closing of the rolling stand, as described in the invention, preferably involves adjusting and/or opening or closing with the purpose of influencing the final rolling temperature. In targeted opening or closing, the rolling stand is opened or closed with the intention of increasing or decreasing the final rolling temperature. Similarly, in targeted adjustment, a casting machine parameter is changed with the intention of increasing or decreasing the final rolling temperature.

One aspect of the invention is based on the approach of adjusting, and in particular increasing, the final rolling temperature of a rolling stand assembly, especially exclusively, by skillfully varying a selected number of production parameters. In some cases, it is even possible to achieve a desired final rolling temperature by adjusting only one of these production parameters. Otherwise, the desired final rolling temperature can be achieved by a combination of adjustments to these parameters.

It has been shown that, for the production of hot-rolled strip with desired properties, particularly mechanical ones, and a target strip thickness, it is sufficient to maintain a certain temperature range during rolling with the last active rolling stand of the rolling stand group – possibly taking into account, for example, a coiler temperature, a chemical strip composition, pass counts, and/or the like. This final rolling temperature range can therefore be predetermined by production planning for the hot-rolled strip. The final rolling temperature range can be derived from such production planning, for example, from the targeted product dimensions, especially the target strip thickness, the targeted quality, and/or the production steps to be carried out, especially a pass schedule, or it can even be explicitly specified in the production plan.

It has further been shown that, at least in a casting mill with only a single rolling stand group, such a predetermined final rolling temperature window can, in most cases, be achieved simply by opening or closing at least one of the rolling stands, particularly the last rolling stand, the rolling stand group, and/or by adjusting at least one casting machine parameter. The following have proven particularly effective in influencing, and especially increasing, the final rolling temperature through a casting machine parameter: i) adjusting the casting thickness, i.e., the thickness of the metal strand to be rolled; ii) adjusting the casting speed, i.e., the exit speed of the metal strand from the casting machine; and/or iii) adjusting the secondary cooling capacity, i.e., the intensity of cooling the partially solidified strand after it exits a casting machine mold until it exits the casting machine.

Opening the last stand in the rolling mill moves the finishing rolling operation to the next stand further upstream. This can cause a sudden increase in the final rolling temperature. Conversely, closing the last stand in the rolling mill can cause a sudden decrease in the final rolling temperature.

Increasing the casting thickness or casting speed shifts the area of complete solidification of the metal strand in the casting machine towards the end of the machine, i.e., towards the end of the strand guide. Consequently, the strand temperature at the exit of the casting machine, and therefore also the final rolling temperature, can be increased. Furthermore, to achieve a predetermined target strip thickness with an increased casting thickness, a greater reduction in the rolling stand group is necessary. The associated higher forming energies can also contribute to an increased final rolling temperature. Additionally, increasing the casting speed reduces the heat losses of the metal strand until it reaches the rolling stand group, particularly the last stand. This also increases the final rolling temperature. A reduction in casting thickness or casting speed has the opposite effect.

Reducing the secondary cooling capacity in the casting machine increases the temperature of the metal strand and/or the amount of heat contained within it. This can lead to an increase in the final rolling temperature. Conversely, increasing the secondary cooling capacity can lower the final rolling temperature.

In particular, the combination of adjusting at least one of the aforementioned casting machine parameters and opening or closing at least one rolling stand can reliably achieve the predetermined final rolling temperature range. While opening at least one rolling stand, for example, allows for a sudden increase in the final rolling temperature, additionally adjusting at least one of the aforementioned casting machine parameters can provide some flexibility in setting the final rolling temperature. Starting from the sudden temperature increase, the final rolling temperature can then be reduced somewhat or, if the temperature increase is still insufficient to reach the final rolling temperature range, increased further.

The extent to which at least one casting machine parameter needs to be adjusted, or whether and, if so, how many rolling stands need to be opened or closed, depends not only on the predetermined final rolling temperature window but also on the current operating state of the casting rolling mill. This operating state is expediently characterized by operating data, for example, current values of the mill's operating parameters. Therefore, preferably, the opening or closing of at least one rolling stand and/or the adjustment of at least one casting machine parameter is based on this operating data.

Preferred embodiments of the invention and their further developments are described below. These embodiments can be combined with each other and with the aspects of the invention described below, unless expressly excluded.

Typically, achieving a predetermined target strip thickness has top priority. If necessary, even the quality of the produced hot-rolled strip, for example, its surface finish, may be subordinated to achieving the target strip thickness. To ensure that the target strip thickness is achieved, a rolling schedule for the hot-rolled strip to be produced is preferably determined and checked to determine how many rolling stands in the rolling stand group are required to achieve the predetermined target strip thickness. Advantageously, the final rolling temperature is then adjusted based on this check by opening or closing the rolling stand in the rolling stand group. Furthermore, it is preferred that the adjustment of at least one die-casting machine parameter is also based on this check. For example, the stand is only opened or closed if the target strip thickness can still be achieved and the permissible rolling forces and moments in the active stands are maintained. Thus, if the final rolling temperature needs to be increased, but the target strip thickness cannot be achieved when opening one rolling stand while adhering to the permissible rolling forces and moments in the other rolling stands, the final rolling temperature is expediently increased by a measure other than opening the rolling stand, for example by increasing the casting thickness, increasing the casting speed and/or reducing the secondary cooling capacity.

The process of determining the number of rolling stands required to achieve the predetermined target strip thickness within the rolling stand group, and the resulting decision to open or close a rolling stand, can be prioritized. This means that before taking other measures to adjust the final rolling temperature, it is preferable to first check whether a rolling stand can be opened or closed.

Alternatively or additionally, the final rolling temperature is only adjusted by adjusting the secondary cooling capacity and/or the cooling capacity of an intermediate stand cooling system and/or the cooling capacity of a dedicated cooling unit upstream of the rolling stand group if the final rolling temperature cannot be adjusted, preferably within a predetermined period, solely by opening or closing a rolling stand and/or adjusting the casting thickness and/or adjusting the casting speed, so that it lies within the predetermined final rolling temperature window. By adjusting the secondary cooling capacity and/or the cooling capacity of the intermediate stand cooling system and/or the cooling capacity of the dedicated cooling unit, the final rolling temperature can, for example, be raised or lowered into the desired temperature range, starting from a temperature jump caused by opening or closing a rolling stand. This is because the adjustment of the secondary cooling capacity and, in particular, the cooling capacity of the dedicated cooling unit allows for the precise control of the final rolling temperature. The cooling capacity of the intermediate stand cooling system and/or the dedicated cooling unit allows for fine adjustment of the final rolling temperature. At the same time, adjusting the cooling capacity of the intermediate stand cooling system and/or the dedicated cooling unit can be advantageous when the final rolling temperature needs to be set quickly, since the final rolling temperature reacts essentially immediately, i.e., without significant time loss, to adjustments of these cooling capacities.

To ensure a reliable casting process and to account for side effects resulting from changes in the casting machine parameters, it is preferably verified whether a casting stability criterion is still met when adjusting the casting thickness, casting speed, and/or secondary cooling capacity to set the final rolling temperature. Advantageously, the final rolling temperature is then adjusted based on this verification by modifying the casting thickness, casting speed, and/or secondary cooling capacity.

A casting stability criterion within the meaning of the invention is preferably a criterion whose fulfillment allows the casting operation to be maintained essentially without disruption. The casting stability criterion can, for example, include limiting fluctuations in the casting level in the mold or maintaining a predetermined casting level stability, limiting breakthroughs, maintaining a predetermined temperature distribution in the mold, and/or maintaining a predetermined solidification length or requiring complete solidification of the metal strand within the casting machine, i.e., before exiting the strand guide of the casting machine.

For example, to increase the final rolling temperature, the casting speed and casting thickness can only be increased and the secondary cooling capacity reduced only to the extent possible while maintaining the predetermined casting surface stability and the predetermined solidification length.

Advantageously, increasing the casting speed and casting thickness is prioritized over reducing the secondary cooling capacity. In other words, to increase the final rolling temperature, the casting speed and casting thickness are preferably maximized, if possible, before the secondary cooling capacity is reduced. This is because increasing the casting speed and casting thickness increases the productivity of the casting mill. Therefore, the final rolling temperature is preferably set with consideration for mill productivity.

To take into account such previously mentioned side effects as changes in production volume, changes in casting level fluctuations and/or changes in solidification length, as well as the associated changes in the surface quality of the produced hot-rolled strip Furthermore, it is preferred that the adjustment of the aforementioned selected production parameters of the casting mill be based on an evaluation of operating data characterizing the current operating state of the casting mill and product data characterizing the production plan for the hot-rolled strip to be produced. The opening or closing of the rolling stand and/or the adjustment of the casting thickness, casting speed, and/or secondary cooling capacity can, for example, be based on a current or present final rolling temperature, casting speed, casting thickness, the amount of water used in the secondary cooling system, the casting level stability, the number of rolling stands engaged, and/or the like, taking into account desired product dimensions, in particular the target strip thickness, the desired quality of the hot-rolled strip produced, the production schedule, and/or the like.

As mentioned above, the temperature of the metal strand upon exiting the casting machine, or the amount of heat contained within the metal strand upon exiting the casting machine, significantly influences the final rolling temperature. To achieve particularly precise and reliable control of the final rolling temperature, it is therefore preferable to determine the strand temperature as the cast metal strand exits the casting machine. Advantageously, the opening or closing of a rolling stand and/or the adjustment of the casting thickness, casting speed, and/or secondary cooling capacity are then based on the determined strand temperature. The strand temperature can be measured and/or simulated for this purpose. Alternatively or additionally, the strand temperature upon entering and/or exiting the rolling stand group can also be determined, for example, by sensor detection or simulation, and used as the basis for opening or closing and/or adjusting at least one casting machine parameter.

Even more flexible temperature control, and in particular a greater range for temperature adjustment, can be achieved through intelligent control of a descaling device in the casting mill and/or an intermediate stand cooling system in the rolling mill group. Accordingly, the final rolling temperature is preferably set by additionally adjusting the cooling capacity in the descaling device and/or the cooling capacity of the intermediate stand cooling system. This allows for even greater control over the final rolling temperature, for example, if temperature control solely through opening or closing a rolling stand and adjusting the aforementioned casting machine parameters is insufficient. For instance, the final rolling temperature can be lowered by increasing the amount of water applied per unit of time to the metal strand for descaling or strip cooling in the rolling mill group, or by increasing the water pressure for descaling. Conversely, the final rolling temperature can be raised by reducing this amount of water or the water pressure.

Since the amount of water used in the descaling unit, the water pressure, and the cooling capacity of the intermediate stand cooling system—albeit a relatively small one—affect the subsequent surface quality of the hot-rolled strip, it is advisable to balance the achievable final rolling temperature with product quality when considering the cooling capacity of the descaling unit and/or the intermediate stand cooling system to influence the final rolling temperature. For this purpose, a surface of the hot-rolled strip is preferably measured using sensors, e.g., a camera, and the surface quality of the hot-rolled strip is determined based on the sensor data generated. It can then be verified whether the determined surface quality meets a predetermined quality criterion. Based on this verification, the cooling capacity of the descaling unit and/or the intermediate stand cooling system is expediently adjusted. This prevents the production of unusable hot-rolled strip. If, for example, switching off the descaling device allows the final rolling temperature to be reached within the predetermined final rolling temperature window and minimum requirements for the strip surface to be met, but not the desired requirements, the hot-rolled strip can still be used. For example, it can be sold as a lower grade.

A quality criterion within the meaning of the invention is preferably defined by at least one predetermined property of the hot-rolled strip. Preferably, the quality criterion is a desired or (for sale) acceptable surface quality, e.g., a predetermined maximum surface defect density. The quality criterion is expediently predetermined by the production planning for the hot-rolled strip, for example, directly specified or derivable from the production plan.

As already mentioned at the outset, adjusting the final rolling temperature solely by opening or closing a rolling stand and/or adjusting at least one of the aforementioned casting machine parameters, and optionally also the cooling capacity of the descaling device and/or the intermediate stand cooling, enables particularly efficient hot strip production. In other words, the final rolling temperature is preferably set without reheating the cast metal strand after it exits the casting machine.

The above-described method is expediently carried out with the casting and rolling plant for the continuous production of hot strip according to a second aspect of the invention.

According to the second aspect of the invention, the casting and rolling plant for continuous production of hot-rolled strip comprises: i) a casting machine for casting a metal strand; ii) a single rolling stand group for continuously rolling the cast metal strand into a hot-rolled strip; and iii) a control device for setting a final rolling temperature such that the final rolling temperature within a predetermined final rolling temperature window. The control device for setting the final rolling temperature is configured to i) cause the casting machine to adjust at least one of the following casting machine parameters: a casting thickness; a casting speed; a secondary cooling capacity; and/or ii) cause the rolling stand assembly to open or close a rolling stand.

Advantageously, the casting and rolling mill does not include a heating unit, such as a tunnel furnace, for reheating the cast metal strand before it enters the rolling stand group. This allows the overall length of the mill to be reduced. Likewise, the transport distance between the casting machine and the last rolling stand of the mill group is shortened, thus reducing the heat loss of a metal strand transported along the route until it reaches the last rolling stand. This is advantageous with regard to the maximum achievable final rolling temperature.

The rolling stand group expediently includes a control unit that allows the opening and closing of individual rolling stands, especially the last rolling stand, in continuous operation. For example, the rolling stand group can incorporate so-called rolling mill automation.

The casting machine is appropriately set up to adjust the casting thickness, for example by so-called "liquid core reduction".

Furthermore, the casting machine is expediently equipped to adjust the casting speed, for example by increasing or decreasing the mass flow from or into the mold.

Furthermore, the casting machine is expediently equipped to adjust the secondary cooling capacity, for example, by influencing the amount of cooling water discharged per unit of time or the cooling water pressure. The secondary cooling capacity can be controlled, for example, by a cooling model of the casting machine. It is preferred that the secondary cooling has a wide control range in order to provide a correspondingly wide range for setting the final rolling temperature. In this context, it can be advantageous if the casting and rolling mill is capable of dry casting, at least in sections. For this purpose, the casting and rolling mill can have a strand guide with so-called drying segments. The drying segments expediently include internally cooled support rollers that can guide the solidified metal strand even without (secondary) cooling.

Optionally, the casting and rolling mill can have a dedicated cooling unit upstream of the rolling stand group. This significantly increases the permissible range for reducing the final rolling temperature.

Preferably, the casting and rolling mill includes a descaling device arranged upstream of the rolling stand assembly. Since the descaling device is generally in operation during normal operation of the casting and rolling mill to achieve higher surface qualities, it offers a further possibility (namely by switching it off or reducing the cooling capacity) to increase the final rolling temperature if required.

Fig 1

ein Beispiel einer Gießwalzanlage zur Endlosproduktion von Warmband, und

Fig 2

ein Beispiel eines Verfahrens zum Einstellen einer Endwalztemperatur.

The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings. These drawings show:

Fig 1

an example of a casting and rolling mill for the continuous production of hot-rolled strip, and

Fig 2

An example of a method for setting a final rolling temperature.

Where appropriate, the same reference numerals are used in the figures for the same or corresponding elements of the invention.

Description of the embodiments

FIG 1 Figure 1 shows an example of a casting and rolling mill 10 for the continuous production of hot-rolled strip 12. The casting and rolling mill 10 has a casting machine 20, a first cutting device 30, a descaling device 40, a single rolling stand group 50 with several, in this example six, rolling stands 51, 52, 53, 54, 55, 56 and an intermediate stand cooling unit 58, a cooling section 60, a second cutting device 70 and at least, in this example exactly, two reels 80, 82. The casting machine 20 comprises a mold 22, a strand guide 24 formed from a multitude of support rollers (not shown here), and a secondary cooling system 26. For setting a final rolling temperature at the last active rolling stand of the rolling stand group 50, the casting and rolling plant 10 also has a control device 16, which is connected to the casting machine 20, the rolling stand group 50, and the descaling device 40 via signals or data.

In addition, the casting and rolling mill 10 includes a flame-treating device 90 upstream of the first cutting device 30 in a transport direction R, and a removal system 100 in the area of the first cutting device 30. An inductive heating arrangement 110 is arranged immediately upstream of the descaling device 40. Furthermore, the casting and rolling mill 10 includes a third cutting device 120, which is arranged in the area of the second cutting device 70, i.e., between the cooling section 60 and the two reels 80, 82, as well as temperature sensors 130. The temperature sensors 130 are arranged and/or configured to measure at least the surface temperature. The surface temperature of the metal strand 14 as it exits the casting machine 20, the surface temperature of the metal strand 14 as it enters the rolling stand group 50, and the surface temperature of the hot strip 12 as it exits the rolling stand group 50, particularly as it exits the last active rolling stand of the rolling stand group 50, are to be determined. The determined surface temperature(s) can be used, if necessary, to calculate the strand's internal temperature.

The casting machine 20 can cast liquid metal into a metal strand 14 at a rate preferably of more than 3.5 t per minute per meter of width, preferably more than 4 t per minute per meter of width, and particularly up to 5 t per minute per meter of width. Such a metal strand 14 expediently has a thickness between 80 mm and 240 mm and a width between 500 mm and 2500 mm. With the aforementioned specific mass flows and a short transport distance S defined between the casting machine 20 and the rolling mill group 50, in particular the first rolling stand 51 of the rolling mill group 50, the casting heat still contained in the cast metal strand 14 upon exiting the casting machine 20 can be retained, at least to a large extent, until it reaches the rolling mill group 50, in particular the first rolling stand 51. Because only a single rolling stand 50 is used, the heat from the casting process, still contained in the metal strand 14, can then be used for forming the finished hot-rolled strip 12. In normal operation, therefore, reheating of the metal strand 14 by the inductive heating arrangement 110 is unnecessary. In principle, the casting and rolling mill 10 is thus also conceivable without the heating arrangement 110.

The transport distance S can be shortened, in particular, because it is free of a slab discharge system and a heating unit in the form of a tunnel kiln. This allows the transport distance S to be reduced to, for example, 15 m or less.

This configuration of the casting and rolling mill 10 already allows a comparatively high final rolling temperature to be achieved at the last active rolling stand of the rolling stand group 50 without reheating the cast metal strand 14. However, due to the continuous mass flow in the casting machine 20 and the rolling stand group 50 during the continuous production of hot strip 12—i.e., the coupling of the casting machine 20 with the rolling stand group 50—the final rolling temperature cannot be influenced, for example, by regulating the transport speed along the transport path S, nor can it be further increased. The metal strand 14 cannot, for example, be accelerated after exiting the casting machine 20 to reduce the time and thus the heat losses until it reaches the rolling stand group 50, especially the last active rolling stand, and consequently increase the final rolling temperature. While it is generally possible to use the heating arrangement 110 to increase the final rolling temperature during normal operation, However, due to the energy expenditure required and the associated decrease in production efficiency, this is not a preferred solution.

Rather, the control device 16 is configured to adjust the final rolling temperature (solely) by appropriately controlling the casting machine 20, the rolling stand group 50, and/or the descaling device 40 such that the final rolling temperature lies within a predetermined final rolling temperature range. For this purpose, the control device 16 is configured to cause the casting machine 20 to selectively adjust at least one of the following casting machine parameters: a casting thickness; a casting speed; a secondary cooling capacity. Furthermore, the control device 16 is configured to cause the rolling stand group 50 to selectively open or close a rolling stand 51-56, in particular to open the last active rolling stand or to close the first inactive rolling stand. Optionally, the control device 16 can also be configured to cause the descaling device 40 and/or the intermediate stand cooling 58 to selectively adjust a cooling capacity.

Details regarding the control logic of control device 16 are provided in connection with FIG 2 further described below.

Separating the metal strand 14 by the first separating device 30, preferably designed as a pendulum shear, can be advantageous, for example, in the event of malfunctions, such as in the area of the rolling stand group 50 or the two reels 80, 82. In this case, the casting machine 20 can continue operating, if necessary after only a short interruption, and strand segments separated from the cast metal strand 14 can be removed from the transport section S by means of the removal system 100. This can be continued until the malfunction has been rectified or the casting process has been safely terminated. In addition, the first separating device 30 can also be used during start-up or shutdown, i.e., at the beginning or end of hot strip production, to decouple the casting machine 20 from the rolling stand group 50. In other words, the first separating device 30 can interrupt the mass flow between the casting machine 20 and the rolling stand group 50 if the casting speed is too low and, as a result, the temperature loss until reaching the rolling stand group 50 becomes too high in order to roll the desired hot strip 12.

In addition, a sample of the metal strand 14 can be separated using the first separating device 30 during operation, i.e. during regular hot strip production, and removed from the transport section S using the extraction system 100.

In the rolling stand group 50, the metal strand 14 is rolled into hot strip 12. For this purpose, the metal strand 14 is expediently engaged with all or at least some of the rolling stands 51-56. The rolling stands 51-56 are preferably designed as four-stands. If necessary, however, the first stand 51 can also be designed as a two-stand. Alternatively or additionally, the last or the last two scaffolds 55, 56 can also be designed as sexto scaffold(s).

The hot-rolled strip 12 is cooled in a controlled manner on the cooling section 60 until it reaches a coiling temperature. This allows it to be coiled into a bundle using one of the coilers 80 or 82. Once the bundle has reached a predetermined size or weight, the coiled hot-rolled strip 12 is separated from the subsequent hot-rolled strip 12 by means of the second cutting device 70 or the third cutting device 120. Which of the two cutting devices 70 or 120, which are preferably both designed as drum shears, is used to cut the hot-rolled strip 12 can depend on its thickness and strength. Advantageously, the second cutting device 70 is configured for cutting hot-rolled strips 12 with a thickness of 1 mm to 12 mm, preferably from 2 mm to 12 mm. The third cutting device 120 is then preferably configured for cutting hot-rolled strips 12 with a thickness of 12 mm or more. In order to minimize the risk of the thin strips rising, i.e. the risk of forming a so-called "cobble", the second separating device 70 is preferably arranged behind the third separating device 120.

FIG 2 Figure 200 shows an example of a method for setting a final rolling temperature T during the continuous rolling of a cast metal strand 14 into hot strip 12 in a casting and rolling mill 10 with a single rolling stand group 50 and a casting machine 20. Starting from a current operating state B of the casting and rolling mill 10, the final rolling temperature T is set so that it lies within a predetermined final rolling temperature window F. For this purpose, at least one of the following casting machine parameters is selectively adjusted: a casting thickness D; a casting speed V; a secondary cooling capacity K. Alternatively or additionally, a rolling stand 51-56 of the rolling stand group 50 is selectively opened or closed.

The final rolling temperature T is the temperature of the strip in the area of the last active rolling stand of the rolling stand group 50. In the example shown, the last rolling stand 56 of the rolling stand group 50 is open, i.e., the rolls 56a of the rolling stand 56 are not engaged with the hot strip 12. The final rolling temperature T thus corresponds to the temperature of the hot strip 12 at the preceding rolling stand 55, whose rolls 55a are still engaged with the hot strip 12.

In the present example, to adjust the final rolling temperature T so that it lies within the predetermined final rolling temperature window F, a cooling capacity L of a descaling device 40 of the casting rolling plant 10 is also adjusted.

The current operating state B of the casting and rolling mill 10 is characterized by operating data b. Such operating data b can be defined by current values of operating parameters of the Casting and rolling plant 10, such as the current (actual) final rolling temperature T, casting thickness D, casting speed V, secondary cooling capacity K, cooling capacity L of the descaling device 40, cooling capacity L of an intermediate stand cooling 58 of the rolling stand group 50, number of rolling stands 51-56 engaged with the metal strand 14 or the hot strip 12, casting surface stability in a mold 22 of the casting machine 20, solidification length in the casting machine 20, mass flow from the mold 22 and/or the like. Based on such operating data b, for example a control device 16 of the casting machine 10 can determine to what extent or in what way the casting thickness D, the casting speed V and/or the secondary cooling capacity K and, if applicable, the cooling capacity L of the descaling device 40 and/or the intermediate stand cooling 58 must or can be adjusted, and/or whether a rolling stand 51-56 of the rolling stand group 50 must or can be opened or closed in order to achieve a final rolling temperature T in the predetermined final rolling temperature window F.

The final rolling temperature window F is expediently predetermined by a production plan P. The production plan P expediently includes product data p, such as the anticipated product dimensions, in particular the anticipated strip thickness, the anticipated quality of the hot-rolled strip 12 to be produced, and further details of the hot-rolled strip production to be carried out, for example, a rolling schedule for the rolling stand group 50, the intensity of descaling in the descaling unit 40, and/or the like. The final rolling temperature T can be specified directly in the production plan P or derived from the production plan P, in particular from the product data p.

Based on this, the control device 16 can output control signals or data I to the casting machine 20, the rolling stand group 50, and optionally to the descaling device 40. Advantageously, these control signals or data I cause the casting machine 20 to adjust the casting thickness D, the casting speed V, and/or the secondary cooling capacity K, and/or the rolling stand group 50, in particular a rolling mill automation system, to open or close at least one rolling stand 51-56. In other words, the logic implemented by the control device 16 can evaluate the current operating state B of the casting and rolling mill 10, as well as the pending strips in the production planning P, and accordingly specify target values for the casting machine 20 and the rolling stand group 50 or their components.

The casting thickness D can be adjusted by adjusting support rollers 28, which form a strand guide 24 of the casting machine 20. Depending on the spacing between two opposing support rollers 28, the strand thickness can be reduced, since the core of the strand is still liquid, at least partially, in the area of the strand guide 24 (liquid core reduction or soft reduction). For clarity, only one of the support rollers 28 is labeled with a reference numeral.

The casting speed V can be adjusted by changing the mass flow from or into the mold 22. It must be ensured that the supply of liquid metal is maintained.

The secondary cooling capacity K can be adjusted by changing the amount of water discharged per unit of time by a secondary cooling element 26 of the casting machine 20 in the area of the strand guide 24. For this purpose, a cooling model of the casting machine 20 can be modified accordingly.

Likewise, the control signals or data I can cause the rolling stand group 50 to adjust the cooling capacity L of the intermediate stand cooling 58 and/or the descaling device 40 to adjust its cooling capacity L by changing the descaling intensity.

For example, if, starting from the current operating state B of the casting and rolling mill 10 in a casting sequence, a new hot-rolled strip 12 with the desired strip thickness and quality is to be rolled, and the final rolling temperature T must be increased compared to the current final rolling temperature T, a roll schedule calculation can first be performed to determine the minimum number of rolling stands 51-56 required to achieve the desired strip thickness. If the roll schedule calculation shows that the desired strip thickness can be achieved with one fewer stand than currently used, the rolling mill automation can open the last stand in operation and redistribute the necessary reduction from the casting thickness D to the desired strip thickness among the remaining stands accordingly.

The resulting abrupt increase in the final rolling temperature T will, in the vast majority of cases, not be such that the final rolling temperature T lies within the predetermined final rolling temperature window F. Therefore, it can be further examined whether there is any leeway regarding the casting level stability in the mold 22 and/or regarding the solidification length in the casting machine 20. If this is the case, the casting speed V, the casting thickness D, and/or the secondary cooling capacity K can be adjusted. This is because the fluctuations in the casting level in the mold 22, as well as the solidification length (also referred to as metallurgical length), are, in addition to a material-dependent factor, e.g., The steel grade (K-factor) depends on the casting thickness D and the casting speed V. The solidification length must be shorter than the maximum metallurgical length of the casting machine 20 to ensure complete solidification before the last segment of the strand guide 24 exits the casting machine 20. Similarly, the fluctuations in the pouring level in the mold 22 must not be too large, as this can adversely affect the quality of the cast metal strand 14 – and thus also of the rolled hot strip 12.

If the final rolling temperature T needs to be increased further, but the scope for increasing the casting speed V and the casting thickness D, as well as reducing the secondary cooling capacity K, has already been fully exhausted, it can be checked whether there is still room for improvement regarding the quality of the hot-rolled strip 12. If this is the case, the cooling capacity L of the descaling device 40 can also be reduced.

Conversely, if the final rolling temperature T is to be reduced, the cooling capacity L of the intermediate stand cooling 58 can also be increased - preferably before a previously open rolling stand is closed.

In addition to calculating the production schedule, the control device 16 can use a simulation of the production of the new hot-rolled strip 12 with the casting mill 10 to determine adjustments to the aforementioned casting machine parameters and/or the cooling capacities L of the descaling device 40 and/or the intermediate stand cooling 58. Based on the values determined for the casting machine parameters and/or the cooling capacities L, a plant control system, i.e., a Level 1 or basic automation system, can then make adjustments based on measured values that characterize, for example, the strand temperature at the exit from the casting machine 20, at the entry into the rolling stand group 50 and/or at the exit from the rolling stand group 50, the surface quality of the newly rolled hot-rolled strip 12, and/or the like.

Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention.

Reference symbol list

10

Casting and rolling mill

12

Hot belt

14

metal strand

16

Control device

20

Casting machine

22

mold

24

Strand guide

26

Secondary cooling

28

Support rollers

30

first separating device

40

Descaling device

50

Rolling mill group

51-56

Rolling mills

55a, 56a

Rollers

58

Inter-frame cooling

60

Cooling section

70

second separating device

80, 82

reel

90

Flame device

100

extraction system

110

Heating arrangement

120

third separating device

130

temperature sensor

200

Proceedings

S

Transport route

R

Direction of transport

T

Final rolling temperature

F

End rolling temperature window

D

Casting thickness

V

Pouring speed

K

Secondary cooling capacity

L

Cooling capacity

B

Operating state

b

Operational data

P

Production planning

p

Product data

I

Control signal or data

Claims (10)

Method (200) for setting a final rolling temperature (T) during the continuous rolling of a cast metal strand (14) to hot strip (12) in a casting and rolling mill (10) with a single rolling stand group (50), wherein, starting from a present operating state (B) of a casting and rolling mill (10) with a casting machine (20) and a single rolling stand group (50), a final rolling temperature (T) is set such that the final rolling temperature (T) lies within a predetermined final rolling temperature window (F), by - at least one of the following casting machine parameters is specifically adjusted: a casting thickness (D); a casting speed (V); a secondary cooling capacity (K); and/or - a rolling stand (51, 52, 53, 54, 55, 56) of the rolling stand group (50) is specifically opened or closed. Method (200) according to one of the preceding claims, wherein - a cutting plan for a predetermined target strip thickness of hot strip to be rolled (12) is determined, - it is checked how many rolling stands (51, 52, 53, 54, 55, 56) of the rolling stand group (50) are required to achieve the predetermined target strip thickness, and - based on this test, the final rolling temperature (T) is set by opening or closing a rolling stand (51, 52, 53, 54, 55, 56) of the rolling stand group (50). Method (200) according to one of the preceding claims, wherein the final rolling temperature (T) is adjusted by adjusting the secondary cooling capacity (K) only if the final rolling temperature (T) cannot be adjusted within a predetermined period solely by opening or closing a rolling stand (51, 52, 53, 54, 55, 56) and/or adjusting the casting thickness (D) and/or adjusting the casting speed (V) so that it lies within the predetermined final rolling temperature window (F). Method (200) according to one of the preceding claims, wherein it is checked whether a casting stability criterion is still met when adjusting the casting thickness (D), the casting speed (V) and/or the secondary cooling capacity (K) to set the final rolling temperature (T), and on the basis of this check the final rolling temperature (T) is set by adjusting the casting thickness (D) and/or the casting speed (V) and/or the secondary cooling capacity (K). Method (200) according to one of the preceding claims, wherein the opening or closing of a rolling stand (51, 52, 53, 54, 55, 56) and/or the adjustment of the casting thickness (D), the casting speed (V) and/or the secondary cooling capacity (K) is carried out on the basis of an evaluation of operating data (b) that characterize the current operating state (B) of the casting rolling plant (10) and product data (p) that characterize a production plan (P) for the hot strip (12) to be produced. Method (200) according to one of the preceding claims, wherein a strand temperature is determined at the exit of a cast metal strand (14) from the casting machine (20) and the opening or closing of a rolling stand (51, 52, 53, 54, 55, 56) and/or the adjustment of the casting thickness (D), the casting speed (V) and/or the secondary cooling capacity (K) is carried out on the basis of the determined strand temperature. Method (200) according to one of the preceding claims, wherein the final rolling temperature (T) is set by additionally adjusting a cooling capacity (L) in a descaling device (40) of the casting rolling plant (10) and/or a cooling capacity (L) of an intermediate stand cooling (58) of the rolling stand group (50). Method (200) according to claim 7, wherein - a surface of the rolled hot strip (12) is sensorially detected and a surface quality of the hot strip (12) is determined on the basis of the sensor data generated, - it is checked whether the determined surface quality meets a predetermined quality criterion, and - based on this test, the cooling capacity (L) of the descaling device (40) and/or the intermediate frame cooling (58) is adjusted. Method (200) according to one of the preceding claims, wherein the final rolling temperature (T) is set without reheating the cast metal strand (14) after it exits the casting machine (20). Casting and rolling mill (10) for the continuous production of hot strip (12), with - a casting machine (20) for casting a metal strand (14), - a single rolling stand group (50) for continuous rolling of the cast metal strand (14) into a hot strip (12), and - a control device (16) for setting a final rolling temperature (T) such that the final rolling temperature (T) lies within a predetermined final rolling temperature window (F), wherein the control device (16) for setting the final rolling temperature (T) is configured to - to cause the casting machine (20) to adjust at least one of the following casting machine parameters: a casting thickness (D); a casting speed (V); a secondary cooling capacity (K); and/or - to cause the rolling stand group (50) to open or close a rolling stand (51, 52, 53, 54, 55, 56).