Method and computer program product for operating a casting-rolling system

Abstract

The invention relates to a method and to a computer program product for operating a casting-rolling system (100) and to the corresponding casting-rolling system itself. The casting-rolling system (100) consists of a casting system (110) and a rolling system (120) arranged downstream in the casting direction (G). In a continuous operating mode, the casting system and the rolling system are coupled to one another via a continuously cast strand (20). In the casting system (110) or at least before the first roll stand (122), driver roll pairs are provided to convey the cast strand through the casting-rolling system. To at least reduce, advantageously to prevent, undesired disruptions in the casting process and / or the slipping through of the drive rolls, according to the present invention only one of these driver roll pairs (118) acts as the master driver roll pair to control the casting speed of the cast strand (20). In addition to this master drive roll pair (118), at least one slave drive roll pair (116) is provided in the casting system (110) or before the first roll stand (122), said slave roll drive pair having to follow the master drive roll pair (118) with regard to the casting speed. According to the invention, the slave drive roll pair (116) is torque-controlled.

Description

[0001] Method and computer program product for operating a casting and rolling plant

[0002] The invention relates to a method and a computer program product for operating a casting-rolling plant comprising a casting plant and a rolling plant arranged downstream of the casting plant in the casting direction. The casting plant and the rolling plant are coupled to each other in a continuous operating mode via a cast endless cast strand. Furthermore, the invention relates to a corresponding casting-rolling plant.

[0003] Such coupled casting and rolling mills and methods for their operation are generally known in the prior art. For example, Japanese patent application JP 2010253450 A discloses a method for controlling the speed of a first rolling stand downstream of the casting plant. For this purpose, the speed control is adjusted using an additional control unit until the control deviation lies within a predetermined range. All drivers in the casting plant are each speed-controlled and are all given the same target value. This method keeps the speed of the first rolling stand within a defined interval, but does not take into account the torques of the drivers in the casting machine. Since, as mentioned, the drivers in the casting plant are all speed-controlled and run at the same target value, slippage of the driver rollers can occur.

[0004] A similar statement applies to Japanese patent application JPS 58218304 A. This patent application describes a speed control in a coupled casting and rolling mill. A first driver upstream of a first rolling stand serves as an actuator for a speed control to regulate the actual casting speed to a predetermined target casting speed. A casting ring and the other drivers in the casting plant are also operated with speed control and have the current speed of the first driver as the target value. A rolling stand downstream of the casting plant is also speed-controlled, with the target speed value being adjusted so that the torque of the first driver remains constant. According to the disclosure of this patent application, although a driver torque is used to control the first rolling stand, all other drives are speed-controlled with the same target value specified.This can also cause driver rollers to slip.

[0005] International patent application WO 2021 / 140531 and European patent application EP 3 000 539 A each also disclose a method for operating a casting-rolling plant in continuous operation. These methods provide for the first rolling stand downstream of the casting machine to be used as a "speed master" and controlled to a desired target casting speed. However, due to changing boundary conditions during the casting process, thickness fluctuations regularly occur along the length of the cast strand, leading to undesirable mass flow fluctuations. If rolling then takes place in the first rolling stand at a casting speed controlled to a constant target value and the exit thickness is controlled very precisely, the casting speed in the upstream casting plant often has to be adjusted accordingly. This disrupts the casting process.

[0006] The invention is therefore based on the object of developing a known method and computer program product for operating a coupled casting-rolling plant and a corresponding known coupled casting-rolling plant in such a way that the described undesirable disturbances of the casting process and / or slippage of the drive rollers are reduced, preferably prevented.

[0007] This object is achieved by the method claimed in patent claim 1. This method is characterized in that the driver roller pair is a master driver roller pair that functions as the sole actuator for regulating the casting speed of the cast strand in the strand guide or at its exit upstream of the first rolling stand; that upstream of the first rolling stand, in particular in the strand guide, at least one slave driver roller pair is provided in addition to the master driver roller pair; and that the actual torque of the rollers of the slave driver roller pair is regulated to a predetermined target torque.

[0008] The target casting speed is specified before and during the casting-rolling process by the operators of the casting-rolling plant or by a responsible production planning facility.

[0009] The term "upstream of the first rolling stand" or "before the first rolling stand" includes all locations or positions that - in relation to the casting direction - are located in the casting-rolling plant before the first rolling stand and where the cast strand already exists. This means the area between the mold exit and the first rolling stand, including the strand guide area, and including the area between the strand guide exit and the first rolling stand, excluding the first rolling stand.

[0010] A driver or driver device is a driven pair of power-adjusted rollers for transmitting torque to the cast strand passed through the driver. If the driver device is located in the strand guide, the rollers are strand guide rollers. Alternatively or in addition to a strand guide roller pair, any other driven pair of rollers can also function as a slave driver device upstream of the first rolling stand. If the driver device is located in the rolling mill, the rollers are, for example, the work rolls of a rolling stand. Alternatively or in addition to a work roll pair, any other driven pair of rollers can also function as a slave driver device in the rolling mill. An electric motor typically acts as the rotary drive for the rollers.

[0011] The continuous operation of a casting and rolling mill is characterized by the fact that all plant components, from the casting plant through the rolling mill to a coiler area downstream of the rolling mill for winding the rolled metal strip, are coupled to one another by the cast strand or the rolled metal strip. In this coupled operation, only one pair of driver rollers in front of the first rolling stand can be the "speed master" and specify the casting speed, while all other drivers in the casting plant and / or in the rolling mill are slave drivers that must follow the casting speed specified by the "speed master" or adjust their speed accordingly, as claimed by the present invention. This means, in particular, that no slave driver roller pair, neither in the casting plant nor in the rolling mill, may be operated with casting speed control.

[0012] The claimed arrangement of the master driver roller pair in the casting plant, or at least upstream of the first rolling stand, ensures that the casting plant is operated as consistently as possible. Disturbances in the casting process that occur during real operation, such as fluctuations in the thickness of the cast strand, measurement errors, or roller wear, can be at least largely reduced or even eliminated by the claimed arrangement of the "Speed ​​Master" upstream of the first rolling stand in the casting direction.

[0013] The above-mentioned object of the invention is further achieved by the computer program product according to claim 12 and the casting-rolling plant according to claim 13. The advantages of these solutions correspond to the advantages previously mentioned with reference to the claimed method. Advantageous embodiments of the claimed method and the claimed casting-rolling plant are the subject of the dependent claims.

[0014] Two figures are attached to the description, where

[0015] Fig. 1 the rolling mill according to the invention with a

[0016] Casting speed controller according to a first embodiment; and

[0017] Fig. 2 the casting-rolling plant according to the invention with the

[0018] Casting speed controller according to a second embodiment.

[0019] The invention is described in detail below with reference to the figures mentioned in the form of exemplary embodiments. In both figures, identical technical elements are designated by identical reference numerals.

[0020] Fig. 1 shows the casting-rolling plant 100 according to the invention. It comprises a casting plant 110, which in turn consists of a mold 112 for casting a cast strand 20 and a strand guide device 114 arranged downstream of the mold in the casting direction G, with strand guide rollers for guiding the cast strand 20. Both in the curved bending area of ​​the strand guide device 114 and in its horizontal exit area, two opposing strand guide rollers can form a driver roller pair. According to the present invention, exactly one of these roller pairs, or a roller pair at the exit of the strand guide 114 upstream of the first rolling stand 122, is provided as a master driver roller pair 118 as an actuator for regulating the casting speed of the cast strand 20 with the aid of a casting speed controller 142.The casting speed controller 142 is designed to control the actual casting speed to a predetermined target casting speed by appropriately varying the power or current of the drive of the master roller pair 118. In this respect, the casting speed controller 142 is the "speed master" or the master controller in the sense of the present invention.

[0021] A rolling mill 120 with at least the first rolling stand 122 for rolling the cast strand 20 is arranged downstream of the casting plant 110 in the casting direction G, wherein the casting plant 110 and the rolling mill 120 are operated in particular in an endless operating mode in which they are coupled to one another via the endless cast strand 20.

[0022] In addition to the said master driver roller pair 118, at least one slave driver roller pair 116 is provided in the casting plant 110 and in particular in its strand guide device 114, which is controlled to a predetermined target torque by means of a torque controller 144.

[0023] Basically, the casting-rolling plant 100 is designed to carry out the method according to the invention. This method is explained below:

[0024] In the continuous operating mode, the cast strand 20 cast in the mold is guided by the strand guide rollers of the strand guide device 114 and conveyed in the casting direction through the casting-rolling system 100. With the aid of the master casting speed controller 142, the actual casting speed of the cast strand 20 is regulated to a predetermined target casting speed by appropriately varying the power or current of the drive of the master roller pair 118.

[0025] Fig. 1 shows a first embodiment of the inventive casting speed control. In this embodiment, the speed of the drive of the master drive roller pair 118 is defined as the controlled variable, and the target casting speed is specified in the form of a target speed for the drive of the master drive roller pair 118. In this control, the actual casting speed, represented by the actual speed of the drive of the master drive roller pair 118, is controlled to the target casting speed, represented by the specified target speed of the drive of the master drive roller pair 118.

[0026] Fig. 2 shows an alternative embodiment of the casting speed control according to the invention. In this second embodiment, the speed of the cast strand 20 or the speed of its surface is defined as the controlled variable. This means that the actual casting speed, represented by the actual speed of the cast strand 20 or by the actual speed of the surface of the cast strand 20, is controlled to the predetermined target casting speed, represented by a predetermined target speed for the cast strand or for the surface of the cast strand, with the master drive roller pair 118 acting as the actuator.

[0027] The following statements apply equally to both embodiments of the inventive control of the casting speed:

[0028] In addition to the master drive roller pair, at least one additional roller pair 116 is provided in the casting system 110 as a so-called slave drive roller pair. Only the said master drive roller pair 118 is speed-controlled according to the method according to the invention. The at least one slave drive roller pair 116, on the other hand, is torque-controlled with the aid of the slave torque controller 144. This means that the actual torque of its rollers is controlled to a predetermined target torque.

[0029] If a plurality of slave drive roller pairs 116 are present in the casting plant 110 or upstream of the first rolling stand 122 in the casting direction, these are, as mentioned, all torque-controlled. The target torques for these slave drive roller pairs 116 then preferably correspond to a predetermined distribution of the drive torques for these slave drive roller pairs. The casting-rolling plant 100 can be operated not only in the aforementioned endless operating mode, in which the cast strand 20 has entered at least a first rolling stand 122 of the rolling plant 120 and is being rolled by the rolling stand 122. Prior to this endless operating mode, the casting-rolling plant can be operated in a start-up mode, in which the cast strand 20 is cast in the casting plant 110 and conveyed upstream of the first rolling stand 122 of the rolling plant.In both operating modes, the casting speed can be controlled according to the two embodiments described above with reference to Figures 1 and 2. Preferably, the target casting speed for the master drive roller pair 118 is then specified to be equal in magnitude and constant over time in the start-up mode and in the continuous operating mode.

[0030] At least one pair of slave drive rollers can be provided not only in the casting plant 110, but also in the rolling mill 120. In the rolling mill, such a pair of slave drive rollers is typically formed by the work rolls 124 of the rolling stand 122, in particular by the work rolls of the first rolling stand 122 provided in the casting direction G. These slave drive roller pairs in the rolling mill may also not be controlled to the casting speed according to the method according to the invention. Rather, they are torque-controlled during the continuous operating mode, i.e., the actual torque of the rollers of the slave drive roller pair 124 in the rolling stand is adjusted or controlled to a predetermined target torque.

[0031] The torques of the rollers of the slave driver roller pairs 116 in the strand guide 14 and / or the rollers of the slave driver roller pairs 124 in the rolling mill 120 are preferably controlled by appropriately varying the current in the roller drives. The current, as a control variable for the drives, is then varied such that the actual torque is adjusted or controlled to the desired or specified target torque.

[0032] Alternatively, the torque control of the rollers of the slave drive roller pairs of the strand guide 114 and / or in the rolling mill 120 can also be achieved by appropriately varying the speed of these rollers as a manipulated variable. This means that the respective responsible torque controller 144, 146 specifies a suitable variation of the speed as a manipulated variable for the rollers of the respective slave drive roller pair, and the current in the drives is then adjusted accordingly to implement the required variation of the speed. According to a further exemplary embodiment, the speed varied as a manipulated variable can be maintained at the speed specified during the variation in at least one of the torque controllers 144, 146 with the aid of a subordinate speed controller 148.

[0033] By varying the speed as a control variable and the optionally subordinate speed control with the superimposed torque control, it is advantageously achieved that the cast strand 20 between the casting system 110 and the first rolling stand 122 does not bulge. It is also advantageously prevented that too much tension is built up in the cast strand 20 between the casting system 110 and the first rolling stand 122 and that one of the drives of the slave driver roller pairs 116, 124 slips. If the

[0034] If the drive torques of the slave driver roller pairs 116 in the casting system 110 decrease, the first rolling stand 122 must rotate faster, i.e., be given a higher speed as the control variable. Conversely, if the drive torques of the driver roller pairs 116 in the casting system 110 decrease, the first rolling stand 122 must rotate correspondingly slower, i.e., be given a lower speed as the control variable.

[0035] The target torque for the work rolls 124 of the preferably first rolling stand 122 of the rolling mill 120 can be specified, for example, as the actual torque of one of the slave drive roller pairs 116 in the strand guide device 114. Alternatively, the target torque for the work rolls 124 can also be specified as the total torque of at least two, preferably all, slave drive roller pairs 116 in the strand guide device 114.

[0036] The total torque is determined by measuring the torques of at least two, preferably all, pairs of drive rollers 116 in front of the first rolling stand 122 during the start-up mode, storing them and adding them to the total torque before the cast strand has entered the first rolling stand.

[0037] List of reference symbols

[0038] 100 casting and rolling mill

[0039] 110 Casting plant

[0040] 112 mold

[0041] 114 Strand guiding device

[0042] 116 Slave driver roller pair in front of the first rolling stand

[0043] 118 Master drive roller pair in front of the first rolling stand

[0044] 120 rolling mill

[0045] 122 rolling stand

[0046] 124 Slave driver roller pair in the form of the work rolls of a

[0047] Rolling stand

[0048] 142 Master casting speed controller for master drive roller pair

[0049] 144 Slave torque controller for casting machine

[0050] 146 Slave torque controller for rolling mill

[0051] 148 Subordinate speed controller

[0052] 20 casting strands

[0053] G Pouring direction

Claims

Patent claims:

1. A method for operating a casting-rolling plant (100) with a casting plant (110) comprising a mold (112) for casting a continuous cast strand (20) and a strand guide device (114) arranged downstream of the mold (112) in the casting direction (G) for guiding the cast strand (20), and with a rolling plant (120) arranged downstream of the casting plant (110) in the casting direction (G) and having at least one rolling stand (122) for rolling the cast strand (20), wherein the casting plant (110) and the rolling plant (120) are operated in an endless operating mode in which they are coupled to one another via the continuous cast strand (20), comprising the following steps: Regulating the actual casting speed of the cast strand (20) to a predetermined target casting speed by suitably varying the power of the drive of a pair of driver rollers (118) within the strand guide device (114) of the casting plant (110) or at its output upstream of the first rolling stand (122) of the rolling plant (120), wherein the cast strand (20) is guided between the rollers of the pair of driver rollers (118) and is conveyed by the rollers in the casting direction (G) through the casting-rolling plant (100); characterized in that the pair of driver rollers (118) is a master pair of driver rollers which functions as the sole actuator for regulating the casting speed of the cast strand (20); that upstream of the first rolling stand (122), in addition to the master pair of driver rollers (118), at least one pair of slave driver rollers (116) is provided; and that the actual torque of the rollers of the slave driver roller pair (116) is regulated to a predetermined target torque.

2. Method according to claim 1, characterized in that the casting-rolling plant (100) is operated in a start-up mode in time before the endless operating mode in which the cast strand (20) has run into at least a first rolling stand (122) of the rolling plant (120) and is rolled by the rolling stand (122), in which the cast strand (20) is cast in the casting plant (110) and is conveyed up to the first rolling stand (122) of the rolling plant (120).

3. Method according to claim 2, characterized in that the target casting speed for the master drive roller pair (118) in the start-up mode and in the endless operating mode is specified to be equal in amount and constant over time.

4. Method according to one of the preceding claims, characterized in that when controlling the casting speed, the speed of the drive of the master drive roller pair (118) is defined as the controlled variable, and the target casting speed is specified in the form of a target speed for the drive of the master drive roller pair (118); or that when controlling the casting speed, the speed of the cast strand or the surface of the cast strand (20) is defined as the controlled variable, and the target casting speed is specified in the form of a target speed of the cast strand or the surface of the cast strand for the drive of the master drive roller pair (118).

5. Method according to one of the preceding claims, characterized in that - if a plurality of slave drive roller pairs (116) are present in the casting plant (110) - the target torques for these Slave drive roller pairs (116) are specified according to a desired drive torque distribution. Method according to one of the preceding claims, characterized in that at least one slave drive roller pair in the form of the work rolls (124) of one of the rolling stands (122) of the rolling mill (120), in particular the first rolling stand (122) in the casting direction (G), is provided in the rolling mill (120); and that - during the endless operating mode - the actual torque of the rollers of the slave drive roller pair (124) in the rolling mill (120) is regulated to a predetermined target torque. Method according to claim 6, characterized in that the torque of the rollers of the slave drive roller pairs (116, 124) upstream of the first rolling stand (122) and / or in the rolling mill (120) is regulated by suitable variation of the current in the drives of the rollers as a manipulated variable.Method according to claim 6, characterized in that the torque of the rollers of the slave drive roller pairs is controlled upstream of the first rolling stand (122) and / or in the rolling mill (120) by suitably varying the rotational speed of the rollers of the slave drive roller pairs (124) as a control variable. Method according to claim 8, characterized in that the rotational speed varied as a control variable is controlled at least in one of the torque controls (144, 146) with the aid of a subordinate control. The speed control (148) is maintained at the speed specified during the variation for the torque control. Method according to one of claims 6 to 9, characterized in that the target torque for the work rolls (124) of the preferably first roll stand (122) of the rolling mill (120) is specified as the torque of a slave driver (116) upstream of the first roll stand (122), in particular in the strand guide device (114), or as the total torque of at least two, preferably all, slave drivers (116) upstream of the first roll stand (122). Method according to claim 10, characterized in that the total torque is determined by measuring the torques of at least two, preferably all, slave driver roller pairs (116) upstream of the first roll stand (122) during the start-up mode, storing them, and adding them to the total torque before the cast strand (20) has reached the first roll stand (122).A computer program product that can be loaded into the internal memory of a digital computer and comprises software code sections with which the steps according to the method according to one of the preceding claims are carried out when the computer program product is running on the computer. A casting and rolling plant (100) comprising a casting plant (110) with a mold (112) for casting a continuous cast strand (20) and with a strand guide device (114) with strand guide rollers arranged downstream of the mold (112) in the casting direction (G). for guiding the cast strand (20); a rolling mill (120) arranged downstream of the casting plant (110) in the casting direction (G), having at least one first rolling stand (122) for rolling the cast strand (20), wherein the casting plant (110) and the rolling mill (120) can be operated in a continuous operating mode coupled to one another via the continuous cast strand (20); and a casting speed controller (142) for controlling the actual casting speed of the cast strand (20) with a pair of drive rollers within the strand guide device (114) of the casting plant (110) or at its output in the casting direction (G) upstream of the first rolling stand (120) of the rolling plant (120) to a predetermined target casting speed by suitably varying the power of the drive of the pair of drive rollers; characterized in that the pair of drive rollers is a master pair of drive rollers (118) and the casting speed controller is a master controller (142);that - with respect to the casting direction (G) - at least one slave drive roller pair (116) is provided upstream of the first roll stand (122) in addition to the single master drive roller pair (118); and that at least one torque controller (144) is provided in the casting system (110) for regulating the actual torque of the rollers of the at least one slave drive roller pair (116) upstream of the first roll stand (122) to a predetermined target torque. The casting and rolling system according to claim 13, characterized in that at least one further slave drive roller pair in the form of the work rolls (124) of one of the roll stands (122) is present in the rolling system (120). Casting-rolling plant according to one of claims 13 or 14, characterized in that the casting-rolling plant (100) is designed to carry out the Method according to one of claims 1 to 11.

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