Method for transversely cutting a metal strip and rolling installation having a shear for transversely cutting a metal strip

Abstract

The invention relates to a method for transversely cutting a metal strip by means of at least one shear in a rolling plant (1), comprising the following method steps: A) determining at least one target cutting time point at a cutting position of the rolling plant depending on a target length of the metal strip, B) determining a shear strength of the metal strip at the cutting position at the target cutting time point, C) activating cutting at the target cutting time point if the shear strength of the metal strip at the cutting position at the target cutting time point is less than or equal to a limit shear strength of the metal strip given for the shear, or D) blocking cutting at the target cutting time point if the shear strength of the metal strip at the cutting position at the target cutting time point is greater than the limit shear strength.

Description

[Technical field]

[0001] The present invention relates to a method for transversely cutting a metal strip in a rolling plant with at least one shear. [Background technology]

[0002] The invention further relates to a rolling installation comprising means for cutting and rolling a metal strip in at least one rolling line having at least one rolling device, at least one shear configured for separating the metal strip into portions of a predetermined length, and at least one higher-level process control for automating the installation.

[0003] The rolling plant is in particular configured as a so-called CSP® plant (Compact Strip Production) for the nearly continuous casting and rolling of slabs.

[0004] The CSP® process developed by the applicant is a process in which liquid steel is cast into so-called slabs in a continuous caster. The cast strip is separated into slabs by shears, homogenized to the rolling temperature in a furnace, possibly warmed and subsequently rolled in a hot rolling line. The shears, which cut the individual slabs from the continuously machine-leaving strip, are designed to be able to separate the hot strip even under demanding process conditions, i.e. when low temperature levels, when processing high-strength materials and when the cutting widths are large. Depending on the cutting conditions, the shears can be subjected to high wear. Under the most unfavourable conditions, they can be damaged, leading to failure.

[0005] It is known in the prior art to achieve improved wear characteristics of equipment components by guiding methods.

[0006] Such a method for improving the wear properties of plant components during the further processing of high-alloy steels and plants for processing high-alloy steels are known, for example, from DE 10 2016 109 489 A1. The method known from this document provides for controlling the cooling of the cast product in such a way that the maximum temperature in the cross section of the cast product is at least temporarily below the inductile transition temperature at the end of the casting machine and upstream of the first deformation step, but at least upstream of the mechanical cut-to-length cutting of the cast product by the shears, for the respective processing step. In particular, it is provided that the secondary cooling of the metal strip is precisely controlled so that the strip is not in the range of the inductile transition temperature during cutting by the shears. This in particular protects the shears from premature wear.

[0007] A method for cross-cutting a metal strip is known, for example, from EP 3177412. This method also relates to the adjustment of a correct temperature profile at the leading and trailing strip ends before cross-cutting the metal strip.

[0008] DE 10 2019 217 839 A1 discloses a method for cross-cutting a metal strip with at least one separating device. In the method described therein, provision is made for calculating actual values ​​of characteristic values ​​over a relatively long section of the metal product to be produced, the characteristic values ​​representing the resistance of the metal product to the separating or deforming process. When the actual value of the characteristic value of the metal product is smaller than a threshold value, i.e. when the performance of the device is sufficient to separate or deform the metal product, the actual separating or deforming also takes place. This makes it possible to avoid an immediate overload or damage to the separating or deforming device. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] DE 102016109489 [Patent Document 2] European Patent Publication No. 3177412 [Patent Document 3] DE 102019217839 Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the invention is to provide a method for cross-cutting metal strips of the type mentioned at the outset, which also contributes to improving the wear properties of the shears.

[0011] A further object of the present invention is to provide a rolling installation which is configured in such a way that operation of the shears with reduced wear is guaranteed. [Means for solving the problem]

[0012] The problem is to provide a method having the features of claim 1 and to 5 The problem is solved by providing a rolling installation having the following features. Advantageous configurations of the invention are evident from the dependent claims.

[0013] One aspect of the invention relates to a method for transversely cutting a metal strip using at least one shear in a rolling plant, comprising the steps of: A) determining at least one target cutting time point at a cutting location of the rolling equipment depending on the target length of the metal strip, B) Determine the shear strength of the metal strip at the cut location at the target cut point; C) activating the cut at the target cut point when the shear strength of the metal strip at the cut location at the target cut point is less than or equal to the critical shear strength of the metal strip for a given shear; or D) When the shear strength of the metal strip at the cutting position at the target cutting point is greater than the critical shear strength, the cutting is blocked at the target cutting point. The method includes steps.

[0014] The shears used in this method may be configured as pendulum shears, crank shears, drum shears or the like.

[0015] In the context of the present invention, a metal strip is understood to mean a flat metal product which is fed continuously or discontinuously to a rolling installation as a semi-finished product in the form of slabs, blocks, bars and which is to be cut in the rolling installation before and / or during processing. The term "metal strip" also includes intermediate and primary products, such as, for example, hot strip or cast strip, which leave the outlet of a continuous caster connected to the rolling installation and are cut in the rolling installation into slabs and further rolled into strip.

[0016] The method particularly relates to transverse cutting of metal strips at temperatures above 300°C.

[0017] The rolling plant according to the invention is preferably a rolling plant for producing strip with a final thickness of 0.6 mm to 25.4 mm, for example from cast slabs which may have a thickness of 40 mm to 180 mm, preferably 50 mm to 150 mm, and a width of 800 mm to 2500 mm.

[0018] A main aspect of the invention is the mechanical protection of the shears by preferably continuously calculating the hot shear strength of the metal strip at the cutting position. If the shear strength of the metal strip at the cutting position at the target cutting time is greater than a determined limit shear strength, according to the invention the cutting of the shears is blocked, in particular until the shear strength of the metal strip falls below the limit shear strength given for the shears.

[0019] The method may be performed based on models and rules: unlike in the methods known in the prior art, the temperature profile is not affected before cross-cutting the metal strip, but the shear strength of the metal strip is continuously calculated, the shear strength being a function of the temperature, material composition, thickness and width of the metal strip.

[0020] Method according to the invention is set to determine a new target cutting time when the cutting is blocked because the limit shear strength of the metal strip is exceeded.

[0021] The shear strength of the metal strip at the cut location at the time of the target cut can be determined as a function of the temperature of the metal strip at the cut location at the time of the target cut.

[0022] For this purpose, provision can be made for the temperature at the cutting position to be determined continuously at the set cutting time on the basis of the measured temperature and / or calculated temperature profile over at least one partial length of the metal strip.

[0023] The target cutoff time is According to the present invention,Calculating using at least one computer implemented algorithm for optimizing the cut length. Be The computer implemented algorithm is, for example, part of a higher level process control.

[0024] The shear strength of the metal strip at the cut position at the target cut time is preferably determined as a function of the temperature of the metal strip and the thickness and / or width of the metal strip and the material composition of the metal strip. An online process model can calculate the temperature course of the metal strip. In a CSP® plant, the online process model can calculate, for example, the temperature course from the caster to the inlet to a downstream furnace or a downstream heating device. The material composition can be obtained from an analysis of the rolled product and stored in the process control or process automation.

[0025] Shear strength is the shear strength (kN / mm 2 ) where shear strength is understood to mean the resistance of a solid to shear forces, especially in the tangential direction.

[0026] If unfavourable process conditions lead to high hot shear strength of the metal strip, the automation of the critical range of the rolling process or possibly other upstream process steps locks the shears so that they are not damaged. This critical range can also be visualized in the Level 1 or Level 2 automation and an appropriate warning can be output to the operator. Via model-based calculations for optimizing the cut length, the originally planned target cut can be redefined so that the resulting process disturbance is as small as possible.

[0027] According to one aspect of the invention, a rolling installation is provided, comprising means for cutting and rolling a metal strip in at least one rolling line with at least one rolling unit, wherein at least one shear is preferably arranged immediately downstream of a continuous casting installation, wherein shears are formed for separating the metal strip into portions of predetermined length, wherein the rolling installation comprises a higher-level process control for automation, wherein the process control comprises means for controlling the at least one shear according to the method described above.

[0028] The shear may be arranged upstream of a furnace located immediately downstream of the continuous casting facility and upstream of the at least one rolling unit. The furnace may be configured, for example, as a tunnel furnace.

[0029] The rolling plant according to the invention may in particular comprise a process control unit, which comprises means for calculating the temperature profile and / or the temperature course of the metal strip between the continuous casting plant and a heating device arranged upstream of the first rolling device.

[0030] The process control unit has means for at least approximately determining the shear strength of the metal strip as a function of the temperature, thickness and / or width of the metal strip at the entrance of the metal strip to the cutting area of ​​the shear, and / or the material composition of the metal strip, and means for blocking the shear when the shear exceeds a shear-specific limit shear strength of the metal strip. do .

[0031] moreover, The process controller comprises a device for optimizing the cut length of the metal strip, configured to determine a modified target cut time for the shear when the cutting operation is blocked. The cut length optimization is preferably model-based. The model may be based on machine learning methods, in particular artificial neural networks, etc.

[0032] The invention will now be described with reference to an embodiment shown in the drawings. [Brief description of the drawings]

[0033] [Figure 1] 1 shows a casting and rolling installation according to the present invention. [Diagram 2] 1 shows a hot rolling installation according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] 1 shows a schematic representation of part of a rolling installation according to the invention, configured as a cast-rolling installation. The cast-rolling installation 1 has a continuous casting installation 2, a shear in the form of a pendulum shear 3 arranged downstream of the continuous casting installation 2, a heating device in the form of a tunnel furnace 4 arranged downstream of the pendulum shear 3, and rolling stands (not shown) arranged in at least one rolling line.

[0035] The continuous casting plant 2 comprises a ladle and a mould 5, not shown. The cast strip 6 leaving the mould 5 is deflected via a strip guide 7 and, downstream of the strip guide 7, cut to length upstream of the tunnel furnace 4 by a pendulum shear 3, whereby the slab or cast strip 6 may have a thickness of 40 mm to 180 mm upstream of the pendulum shear 3 and a width of 800 mm to 2500 mm. The average temperature of the cast strip 6 at the inlet to the pendulum shear 3 should be about 1000°C, i.e. about 900°C on the outside and about 1200°C in the centre. The cast strip 6 is fed to the pendulum shear 3 at a speed of preferably 2 m / s to 7 m / s. The pendulum shear 3 is controlled by an open-loop or closed-loop control device 8, which activates the cut at the target cut point depending on the target length of the slab.

[0036] The method according to the invention involves continuously calculating the shear strength of the cast strip 6 or metal strip to be separated as a function of the temperature of the cast strip, the material composition of the cast strip and the thickness and width of the cast strip.

[0037] The shear strength or hot shear strength of the cast strip 6 is decisive for what shear or cutting force the pendulum shears 3 must exert parallel to the cutting surface. In particular, if the temperature of the cast strip 6 in the region of the inlet to the pendulum shears 3 falls below a certain level, the hot shear strength may increase as a result. Since the pendulum shears 3 are designed for a certain shear or cutting force, it can be assumed that if the limit shear strength of the cast strip 6 is exceeded, the pendulum shears 3 will be damaged or exposed to high wear. In the method according to the invention, provisions are made for a continuous calculation of the shear strength of the cast strip 6 based on the temperature course of the cast strip 6 up to the inlet to the tunnel furnace 4. The method comprises determining the target cutting time of the pendulum shears 3 as a function of a predefined target length of the cast strip 6. The target length of the metal strip to be separated or of the slab to be separated is set by the process control 9. Furthermore, the open-loop and closed-loop control device 8 obtains control impulses from the monitoring of the hot shear strength of the cast strip 6. The control impulse is derived from a comparison of the shear strength difference of the cast strip 6 with a predefined critical shear strength. If the shear strength of the cast strip 6 in the area of ​​the inlet to the pendulum shears 3 is now greater than the critical shear strength, the pendulum shears 3 are locked or blocked. Based on the model optimizing the cut length, the process control 9 commands the open and closed loop control devices 8 to perform a new slab cut.

[0038] FIG. 2 shows a schematic representation of part of a hot rolling plant 10 according to a second embodiment of the invention, which does not necessarily have to be provided with a continuous casting plant 2 upstream of said hot rolling plant 10. In this embodiment, identical components are given the same references. The hot rolling plant 10, which is fed continuously or discontinuously with hot strip 12, has several heating devices, i.e. induction heating devices 13 and two tunnel furnaces 4, two rolling lines with rolling stands 12 and several shears 14 designed for different strip thicknesses. For reasons of simplicity, the illustration and listing of other known components has been omitted. A larger or smaller number of shears may be arranged in the rolling plant, and their position within the plant may also be changed.

[0039] The hot strip 12 is fed to one of a number of drum shears 14. The drum shears 14 are controlled by respective open and closed loop controllers 8 that actuate the cuts according to the target length of the strip at the target cut time.

[0040] The method according to the invention involves continuously calculating the shear strength of the hot strip 12 or cast strip 6 (see FIG. 1 ) to be separated as a function of the material temperature, the material composition and the thickness and width of the hot strip 12 or cast strip 6.

[0041] The shear strength or hot shear strength of the metal strip is decisive as to what shear or cutting force, respectively, must be exerted on the shear parallel to the cutting surface. Based on this, the hot shear strength increases if the temperature of the hot strip 12, especially in the area of ​​the inlet to the shear, falls below a certain level. Since the shears are designed for certain shear or cutting forces, it can be assumed that if the limit shear strength of the hot strip 12 is exceeded, the corresponding shear will be damaged or exposed to high wear.

[0042] In the method according to the invention, it is provided that the shear strength of the hot strip 12 is continuously calculated based on the temperature course of the hot strip 12. This can be limited to a partial region of the hot rolling plant 10 or can be comprehensive throughout the entire hot rolling plant 10. The method comprises determining a target cut-off time point for each shear depending on a predefined target length of the hot strip 12. The target length of the hot strip 12 to be separated is set by the process control 9. Furthermore, the open-loop and closed-loop control device 8 obtains a control impulse from the monitoring of the hot shear strength of the hot strip 12. The control impulse is derived from a comparison of the shear strength of the hot strip 12 with a predefined limit shear strength. If the shear strength of the hot strip 12 in the area of ​​the inlet to the respective shear at the target cut-off time is greater than the limit shear strength, the shear is locked or blocked. Based on a model for optimizing the shear length, the process control device 9 instructs the open-loop and closed-loop control device 8 to carry out a new cut. [Explanation of symbols]

[0043] 1 Casting and rolling equipment 2. Continuous casting equipment 3. Pendulum Shah 4. Tunnel furnace 5. Mold 6 Casting strip 7 Strip Guide 8 Open-loop and closed-loop control devices 9 Process Control Section 10. Hot rolling equipment 11 Rolling Stand 12 Hot strip material 13 Induction heating device 14 Shah

Claims

1. A method for transversely cutting a metal strip by means of at least one shear in a rolling plant (1), comprising the following method steps: A) determining at least one target cutting time point at a cutting location of a rolling mill as a function of a target length of the metal strip; B) determining the shear strength of the metal strip at the cut location at the target cut point; C) activating the cut at the target cut point when the shear strength of the metal strip at the cut location at the target cut point is less than or equal to the critical shear strength of the metal strip for a given shear; or D) blocking the cut at the target cut point when the shear strength of the metal strip at the cut position at the target cut point is greater than the critical shear strength; A method having method steps.

2. E) determining a new target cut time point if the cut is blocked according to method step D); The method of claim 1 further comprising the method step:

3. 3. A method according to claim 1, further comprising determining the shear strength of the metal strip at the cut location at the target cut time as a function of the temperature of the metal strip at the cut location at the target cut time.

4. 4. The method according to claim 1, further comprising the step of determining the temperature at the cutting position at the target cutting time on the basis of the measured temperature and / or the calculated temperature profile over at least one partial length of the metal strip.

5. 5. The method according to claim 1, wherein the target cut time is calculated by at least one computer-implemented algorithm for optimizing the cut length.

6. 6. The method according to claim 1 , further comprising determining the shear strength of the strip at the cut location at the target cut time as a function of the strip temperature and the strip thickness and / or strip width and as a function of the material composition of the strip.

7. In the rolling equipment (1), means for cutting and rolling the metal strip in at least one rolling line having at least one rolling unit; at least one shear arranged upstream and / or downstream in the rolling direction and configured to separate the metal strip into portions of predetermined length; At least one process control unit (9) for automating the rolling installation; Equipped with A rolling installation (1), wherein the process control (9) comprises means for controlling at least one shear according to the method according to any one of claims 1 to 5.

8. 8. The rolling plant (1) according to claim 7, characterized in that the shear is arranged immediately downstream of the continuous casting plant (2) and immediately upstream of a heating device which is placed upstream of the at least one rolling plant.

9. 9. The rolling plant (1) according to claim 8, characterized in that the process control (9) comprises means for calculating the temperature profile and / or the temperature course of the metal strip between the continuous casting plant (2) and a heating device arranged upstream of the first rolling device.

10. 10. The rolling installation (1) according to claim 7, wherein the process control (9) comprises means for at least approximately determining the shear strength of the metal strip as a function of the temperature, thickness and / or width of the metal strip at the inlet of the metal strip to the cutting area of ​​the shears and / or as a function of the material composition of the metal strip, and means for blocking the shears if a shear-specific limit shear strength of the metal strip is exceeded.

11. 11. The rolling installation (1) according to any one of claims 7 to 10, characterized in that the process control (9) comprises a device for optimizing the cutting length of the metal strip, which is configured to determine a modified target cutting time point for the shears when the cutting operation is blocked.

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