Method for cross-cutting a metal strip and rolling equipment having a shear for cross-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 cross-cutting a metal strip using at least one shear in a rolling mill. [Background technology]

[0002] The invention further relates to a rolling installation comprising means for cutting and rolling metal strips in at least one rolling line having at least one rolling mill, at least one shear adapted to separate the metal strip into portions of predetermined length, and at least one superordinate process control for automating the installation.

[0003] The rolling plant is configured in particular 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 method 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, optionally warmed, and subsequently rolled in a hot rolling line. The shears, which cut the individual slabs from the strip continuously exiting the machine, are designed to be able to separate the hot strip even under demanding process conditions, i.e., at low temperature levels, when processing high-strength materials, and with large cutting widths. 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] A method for improving the wear properties of equipment components during the further processing of high-alloy steels and an equipment for processing high-alloy steels is known, for example, from German Patent Application No. DE 10 2016 109 489 A1. The method known from this document provides for controlling the cooling of the cast product so that the maximum temperature in the cross section of the cast product is at least temporarily below the indestructible transition temperature at the end of the casting machine and upstream of the first deformation step, but at least upstream of the mechanical cutting of the cast product to length by shears, for each processing step. In particular, the secondary cooling of the metal strip is precisely controlled so that the strip does not fall within the indestructible transition temperature range during shear cutting. 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 ends of the metal strip before cross-cutting the strip.

[0008] German Patent Application Publication No. 102019217839 discloses a method for transversely cutting a metal strip using at least one separating device. The method described in this document is configured to calculate, for a metal product to be produced, an actual value of a characteristic value over a relatively long portion of the metal product, where the characteristic value represents 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 below 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] German Patent Application Publication No. 102016109489 [Patent Document 2] European Patent No. 3177412 [Patent Document 3] German Patent Application Publication No. 102019217839 Summary of the Invention [Problem to be solved by the invention]

[0010] The object underlying the present 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 mill that is configured to ensure low wear shear operation. [Means for solving the problem]

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

[0013] One aspect of the present invention relates to a method for cross-cutting a metal strip using at least one shear in a rolling mill, comprising the steps of: A) At least one target cut is made at the cutting position of the rolling equipment according to the target length of the metal strip. Cut off Find the time, B) Determine the shear strength of the metal strip at the cut position 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 given the 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 comprises 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, metal strip is understood to mean a flat metal product that is fed continuously or discontinuously to a rolling plant as a semi-finished product in the form of slabs, blocks or bars and that is to be cut in the rolling plant before and / or during processing. The term "metal strip" also includes intermediate products and primary products, such as hot strip or cast strip, that leave the outlet of a continuous casting machine connected to the rolling plant and are cut into slabs in the rolling plant and further rolled into strip.

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

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

[0018] A key 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 critical shear strength, according to the invention, the cutting of the shears is blocked, in particular preferably until the shear strength of the metal strip falls below the critical shear strength given for the shears.

[0019] The method may be performed based on models and rules: unlike in 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, where the shear strength is a function of the temperature, material composition, thickness and width of the metal strip.

[0020] The method according to the invention is provided for determining a new target cutting time when the cutting is blocked because the limiting shear strength of the metal strip is exceeded.

[0021] The shear strength of the metal strip at the cutting position at the target cutting time can be determined according to the temperature of the metal strip at the cutting position at the target cutting time.

[0022] For this purpose, the cutting time is determined based on the measured temperature and / or calculated temperature profile over at least one partial length of the metal strip. Cut off The temperature at the location may be set to be determined continuously.

[0023] The target cut time is calculated according to the invention using at least one computer-implemented algorithm for optimizing the cut length, which 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 point is preferably determined as a function of the temperature of the metal strip and the thickness and / or width of the metal strip as well as the material composition of the metal strip. An online process model can calculate the temperature profile of the metal strip. In a CSP® system, the online process model can calculate, for example, the temperature profile 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 unit.

[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 unfavorable process conditions lead to high hot shear strength in the metal strip, automation of the critical range of the rolling process, or possibly other upstream process steps, can lock the shears so they are not damaged. This critical range can also be visualized by Level 1 or Level 2 automation, and appropriate warnings can be output to the operator. Through 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 present invention, there is provided a rolling installation, comprising means for cutting and rolling a metal strip in at least one rolling line having at least one rolling mill, wherein at least one shear is preferably arranged immediately downstream of the continuous casting installation, wherein shears for separating the metal strip into portions of predetermined length are formed, 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 immediately downstream of the continuous casting facility and upstream of a furnace located upstream of the at least one rolling unit, which 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 the 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 depending on 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 strength exceeds the shear-specific limit shear strength of the metal strip.

[0031] Furthermore, the process control unit has 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 explanation of the drawings]

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

[0034] 1 shows a schematic representation of part of a rolling plant according to the invention, configured as a casting and rolling plant. The casting and rolling plant 1 comprises a continuous casting plant 2, a shear in the form of a pendulum shear 3 arranged downstream of the continuous casting plant 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 includes a ladle and a mold 5 (not shown). The cast strip 6 exiting the mold 5 is redirected via a strip guide 7 and, downstream of the strip guide 7, is cut to length by a pendulum shear 3 upstream of the tunnel furnace 4. The slab or cast strip 6 may have a thickness of 40 to 180 mm and a width of 800 to 2500 mm upstream of the pendulum shear 3. The average temperature of the cast strip 6 at the entrance to the pendulum shear 3 should be approximately 1000°C, i.e., approximately 900°C on the outside and approximately 1200°C in the center. The cast strip 6 is fed to the pendulum shear 3 at a speed of preferably 2 to 7 m / s. The pendulum shear 3 is controlled by an open-loop or closed-loop control device 8. The open-loop or closed-loop control device 8 activates the cutoff at a target cut point depending on the target slab length.

[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 crucial for the shear or cutting force that the pendulum shears 3 must exert parallel to the cutting plane. In particular, if the temperature of the cast strip 6 drops below a certain level in the region of the inlet to the pendulum shears 3, the hot shear strength may increase. Since the pendulum shears 3 are designed for a specific shear or cutting force, exceeding the critical shear strength of the cast strip 6 can lead to damage or high wear of the pendulum shears 3. The method according to the present invention is configured to continuously calculate the shear strength of the cast strip 6 based on the temperature profile of the cast strip 6 up to the inlet to the tunnel furnace 4. This method includes determining a target cutting time for the pendulum shears 3 according to a predetermined target length of the cast strip 6. The target length of the metal strip or slab to be separated is set by the process control unit 9. Furthermore, the open-loop and closed-loop control devices 8 obtain control impulses from monitoring the hot shear strength of the cast strip 6. The control impulse is derived from a comparison of a predetermined critical shear strength with the shear strength difference of the cast strip 6. If the shear strength of the cast strip 6 in the region of the inlet to the pendulum shears 3 is currently greater than the critical shear strength, the pendulum shears 3 will be locked or blocked. Based on a model that optimizes 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. A continuous casting plant 2 does not necessarily have to be provided upstream of this hot rolling plant 10. In this embodiment, identical components are given the same reference numerals. The hot rolling plant 10, to which hot strip 12 is fed continuously or discontinuously, comprises several heating devices, namely induction heating devices 13 and two tunnel furnaces 4, two rolling lines with rolling stands 12, and several shears 14 designed for various 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 positions within the plant may also vary.

[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 point.

[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, material composition and 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 plane. Based on this, the hot shear strength increases when the temperature of the hot strip 12 falls below a certain level, especially in the area of ​​the entry to the shear. Since shears are designed for a certain shear or cutting force, it can be assumed that if the limiting shear strength of the hot strip 12 is exceeded, the corresponding shear will be damaged or exposed to high wear.

[0042] The method according to the present invention is provided for continuously calculating the shear strength of the hot strip 12 based on the temperature profile of the hot strip 12. This can be limited to a specific region of the hot rolling plant 10 or can be comprehensive across the entire hot rolling plant 10. The method includes determining a target cutting time for each shear according to a predetermined target length of the hot strip 12. The target length of the hot strip 12 to be separated is set by the process control unit 9. Furthermore, the open-loop and closed-loop control device 8 obtains a control impulse from monitoring 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 predetermined 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 cutting time is greater than the limit shear strength, the shear is locked or blocked. Cut Based on the cut length optimization model, the process control 9 instructs the open and closed loop controllers 8 to make new cuts. The present application relates to the invention described in the claims, but also includes the following as other aspects. 1. A method for cross-cutting a metal strip with at least one shear in a rolling plant (1), comprising the following method steps: A) Cutting of rolling equipment according to the target length of metal strip Cut off At least one target switch at the position Cut off Find the time, B) Determine the shear strength of the metal strip at the cut position 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 given the 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, blocking the cutting at the target cutting point; A method having method steps. 2. E) determining a new target cutting time if cutting is blocked according to method step D); 10. The method of claim 1, further comprising the method step: 3. 3. The method according to claim 1 or 2, characterized in that the shear strength of the metal strip material at the cutting position at the target cutting time is determined in accordance with the temperature of the metal strip material at the cutting position at the target cutting time. 4. 4. The method according to any one of claims 1 to 3, characterized in that the temperature at the cutting position at the target cutting time is continuously determined based on the measured temperatures and / or the calculated temperature profile over at least one partial length of the metal strip. 5. 5. The method of any one of claims 1 to 4, wherein the target cut time is calculated by at least one computer-implemented algorithm that optimizes the cut length. 6. 6. The method according to any one of claims 1 to 5, characterized in that the shear strength of the metal strip at the cutting position at the target cutting time is determined as a function of the temperature of the metal strip and the thickness and / or width of the metal strip, as well as as a function of the material composition of the metal 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 device; rolling Device at least one shear arranged upstream and / or downstream of the shear and configured to separate the metal strip into portions of predetermined length; At least one upper process control unit (9) for automating the rolling equipment; Equipped with A rolling facility (1), wherein the process control unit (9) has means for controlling at least one shear according to any one of the methods 1 to 5 above. 8. The rolling equipment (1) according to claim 7, characterized in that the shear is located immediately downstream of the continuous casting equipment (2) and immediately upstream of a heating device located upstream of at least one rolling device. 8. The rolling facility (1) according to claim 8, characterized in that the process control unit (9) comprises means for calculating the temperature profile and / or temperature progression of the metal strip between the continuous casting facility (2) and a heating device located upstream of the first rolling device. 10. 10. The rolling equipment (1) according to any one of claims 7 to 9, wherein the process control unit (9) has means for at least approximately determining the shear strength of the metal strip depending on the temperature, thickness and / or width of the metal strip at the entrance of the metal strip to the cutting area of ​​the shears and / or depending on the material composition of the metal strip, and means for blocking the shears when the shear strength exceeds the shear-specific limit shear strength of the metal strip. 11. 11. The rolling equipment (1) according to any one of claims 7 to 10, wherein the process control unit (9) comprises a device for optimizing the cutting length of the metal strip, configured to determine a changed target cutting time point for the shear when the cutting operation is blocked. [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. 1. A method for cross-cutting a metal strip with at least one shear in a rolling mill (1) using at least one process control unit for automating the rolling mill, the method comprising the steps of: A) determining at least one target cutting time point at a cutting location of a rolling mill 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 given the 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; E) If the cut is blocked according to method step D), a new target cut point is determined at which the shear strength of the metal strip falls below the given limit shear strength for the shear, and a new cut is made. A method having the method steps further comprising the method steps.

2. 2. The method of claim 1, further comprising determining the shear strength of the metal strip at the cutting location at the target cutting time as a function of the temperature of the metal strip at the cutting location at the target cutting time.

3. 2. The method according to claim 1, wherein the temperature at the cutting position at the target cutting time is determined continuously based on measured temperatures and / or calculated temperature profiles over at least one partial length of the metal strip.

4. 2. The method according to claim 1, characterized in that the shear strength of the metal strip at the cutting position at the target cutting time is determined as a function of the temperature of the metal strip and the thickness and / or width of the metal strip and as a function of the material composition of the metal strip.

5. In the rolling equipment (1), at least one rolling mill; at least one shear arranged upstream and / or downstream of the rolling mill and configured to separate the metal strip into portions of predetermined length; At least one process control unit (9) for automating the rolling equipment; means for cutting and rolling the metal strip in at least one rolling line having Equipped with 5. A rolling installation (1) comprising a process control unit (9) having means for controlling at least one shear according to the method of any one of claims 1 to 4, means for at least approximately determining the shear strength of the metal strip depending on the temperature, thickness and / or width of the metal strip at the entrance of the metal strip to the cutting area of ​​the shears and / or depending on the material composition of the metal strip, and means for blocking the shears when a shear-specific limit shear strength of the metal strip is exceeded, and the process control unit (9) has a device for optimizing the cutting length of the metal strip, configured to determine a changed target cutting time for the shears when the cutting operation is blocked.

6. 6. The rolling installation (1) according to claim 5, characterized in that the shear is arranged immediately downstream of the continuous casting installation (2) and immediately upstream of a heating device placed upstream of at least one rolling unit.

7. 7. The rolling plant (1) according to claim 6, characterized in that the process control (9) comprises means for calculating the temperature profile and / or temperature course of the metal strip between the continuous casting plant (2) and a heating device arranged upstream of the first rolling device.

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