Method for operating a rolling mill and rolling mill

Abstract

The present invention relates to a method for operating a rolling mill, particularly for hot and cold rolling of flat metal products, wherein the method comprises the following steps: measuring the actual specifications of the metal strip at the exit of the cold rolling mill (2) and / or immediately after a process step following cold rolling; comparing the actual specifications of the metal strip with the target specifications of the metal strip; and comparing at least one selected process parameter of the cold rolling mill (2) and / or upstream equipment, wherein the process parameter is selected from a group of process parameters including: strip tension, in particular between the mill stands (33, 34, 35), roll rise of the mill stands (33, 34, 35), reduction distribution between the mill stands (33, 34, 35), and specification setting of the hot-rolled strip.

Description

Technical Field

[0001] The present invention relates to a method for operating a rolling mill, particularly for hot and cold rolling of flat metal products.

[0002] This invention relates particularly to cross-process control of hot rolling and downstream cold rolling processes. Background Technology

[0003] The strip width of metal products is primarily determined in process steps preceding cold rolling, such as casting and hot rolling. In particular, the initial rolling stage of the hot rolling process is responsible for the final width of the produced metal strip.

[0004] Since the width of the metal strip cannot be set particularly precisely during casting and subsequent hot rolling, it is common and known to trim the strip width using at least one trimming machine or at least one edge trimming machine.

[0005] However, in downstream cold rolling mills, an undesirable shrinkage of a few millimeters in the width direction of the strip often occurs. This is especially true in equipment with high strip tension, such as in tandem cold rolling mills.

[0006] To date, the approach has been to determine the excess width of the metal strip empirically and trim it to the target width if necessary. Since widths below the tolerance limits result in scrap or downgrading, a safety margin is typically added to the empirically determined excess width. This leads to increased scrap, which is undesirable for cost reasons.

[0007] Document CN110202010A discloses a method and system for evaluating the width of stainless steel strips based on the MES line determination method. Summary of the Invention

[0008] The object of the present invention is to provide a method for operating a rolling mill, particularly for hot and cold rolling of flat metal products, and having multiple mill stands, wherein the target width or other target specifications of the finished product, more precisely the finished metal sheet, can be optimized through targeted control of the rolling process.

[0009] Another object of the present invention is to provide a rolling mill that can be controlled by the method according to the invention.

[0010] This objective is achieved by a method having the features of claim 1 and a rolling mill having the features of claim 12.

[0011] Advantageous design options for the method are derived from the dependent claims.

[0012] Basically, by means of the method according to the invention, the process parameters in the upstream process or at the upstream unit are set such that the target specifications, particularly the target width of the metal strip or sheet to be wound into a coil, can be achieved with high precision after cold rolling. For this purpose, measurement data is obtained, including at least the width of the metal strip to be wound into a coil after cold rolling.

[0013] Therefore, according to the present invention, for example, it is specified that the exit width of the metal strip from the cold rolling process is detected by automatic or manual measurement, and the detected measurement value is used to optimize the operation of upstream process steps.

[0014] The method according to the invention includes: measuring at least one actual specification of the metal strip, for example, at or within the outlet of a cooling device and / or at or within the outlet of a strip coating device, in particular in the form of an actual width at the outlet of a cold rolling mill and / or immediately before or after a process step following cold rolling; comparing the actual specification of the metal strip with a target specification of the metal strip, for example, comparing it with a target width of the metal strip; and comparing at least one selected process parameter of a preset cold rolling mill and / or upstream equipment, wherein the process parameter is selected from a group of process parameters including: in particular strip tension between mill stands, roll rise (Walzenaufgang) of the mill stands, reduction distribution between mill stands, and specification settings of hot-rolled strip.

[0015] In a preferred variant of the method according to the invention, the method step of presetting at least one selected process parameter includes adjusting and intervening in the first-level system of process control and / or presetting process parameters for the second-level automation system to set the target specifications of the metal strip at the exit of the cold rolling mill.

[0016] A typical automation department with an automated system comprises an automation pyramid with different levels (grades), used to categorize technologies and systems in control technology and represent different levels of industrial production. A typical automation system in rolling mill equipment includes, for example, pre-setting customer order data via a Level 3 system and pre-calculating mill stand operating parameters, such as rolling force, rolling speed, and work roll bending, using a Level 2 system. These presets are sent to a rapid automation system, i.e., a Level 1 system. The Level 1 system first adjusts and controls the parameters sent by the Level 2 presets, achieving the desired result—a metal strip with stable tension and within flatness and thickness tolerances—through system adjustments, pre-controls, and manual intervention by the operator.

[0017] The process parameters of a cold rolling mill can be, for example:

[0018] - Tension strategies in cold rolling mills, especially in the interstand area;

[0019] - The reduction distribution in the first few racks; and

[0020] - Setting the cutting width of the upstream trimming machine.

[0021] The method according to the invention includes operating rolling mill equipment, wherein the equipment upstream of the exit side of the cold rolling mill is selected from the group of equipment including: hot rolling mill, casting machine, welding equipment and / or pickling and / or annealing equipment.

[0022] Preferably, the cold rolling mill is connected downstream of the hot rolling mill, and at least one trimming machine or side trimming machine is preferably provided on the exit side of the hot rolling mill. The trimming machine trims or cuts the hot-rolled strip from the hot rolling mill to the target width for entry into the cold rolling mill. The hot rolling mill and the cold rolling mill are preferably arranged close together, one after the other.

[0023] A cold rolling mill train can be constructed, for example, as a tandem rolling mill train with multiple mill stands.

[0024] A tandem cold rolling mill typically consists of three to six mill stands arranged in series, which gradually reduce the thickness of the cold-rolled strip during a single pass.

[0025] The influence of process parameters can be achieved by changing the adjustment parameters in at least one adjustment loop of the Level 1 system. The adjustment loop may, for example, use strip width and / or strip tension and / or strip thickness and / or the roll gap of the mill stands in a cold rolling mill train as adjustment parameters. Here, for example, the aforementioned process parameters can be changed online using width information detected at the exit of the cold rolling mill train.

[0026] The method according to the invention also includes cross-process optimization, such that the aforementioned regulatory interventions also include influencing strip width and / or strip tension and / or strip thickness and / or the roll gap of the mill stands in the hot rolling mill series. It is based on the idea that the regulation according to the invention first affects the trimming of the hot-rolled strip and / or the cold rolling mill stands, but also includes feedback with the hot rolling mill series, such that the strip specifications have been affected by corresponding regulatory interventions in the hot rolling process.

[0027] In a preferred variant of the method according to the invention, measurements of the actual specifications of the metal strip (e.g., width and / or thickness) are fed to a software-based prediction module that predicts possible deviations between the actual and target specifications of the metal strip and, based on the predicted deviations, triggers pre-set changes to process parameters and / or adjustments to the cold rolling mill and / or the immediately upstream hot rolling mill.

[0028] Prediction is appropriately accomplished by utilizing machine learning and / or artificial intelligence and / or dataset-based statistical evaluation methods. Machine learning methods or artificial intelligence-based methods include those selected from the group consisting of: physical mathematical models, neural networks, decision gates, if-then queries, statistical models, and state queries and adaptive models.

[0029] Preferably, the strip width is measured as the actual specification of the metal strip, and the target strip width is preset as the target specification. Instead of width, the thickness of the finished product or other quality-determining parameters can also be preset as the actual specification of the metal strip.

[0030] The intervention in the Level 1 system may also include adjusting at least one unit in the upstream hot rolling mill, preferably a shearing machine, and / or controlling at least one vertical mill stand in the hot rolling mill and / or changing other process parameters of the hot rolling mill to set the strip width in the hot rolling mill.

[0031] Some regulatory interventions may be carried out, at least partially, in the regulation loop of at least one unit in a cold rolling mill and / or hot rolling mill. Alternatively or additionally, optimized process parameters may be specified to be passed to the secondary system. Within the scope of this invention, the secondary system is generally understood as an automated system that presets target values ​​for the regulation system below the primary system using an online optimization algorithm. This online optimization algorithm itself utilizes an online model of the equipment to be controlled. The online model is typically a mathematical-physical model.

[0032] Particularly preferably, the measured values ​​of the actual specifications of the metal strip are used to calculate the target strip tension required for the target specifications and / or to calculate the target thickness reduction distribution in the upstream hot rolling mill and / or cold rolling mill, and the target thickness reduction distribution and / or target strip tension of the hot rolling mill and / or cold rolling mill are submitted as presets to the Level 2 automation system to calculate the set values ​​for the units of the hot rolling mill and / or cold rolling mill.

[0033] Preferably, the detection and evaluation of the measured values ​​are performed automatically.

[0034] According to the method of the invention, measurement data, particularly regarding the width of the cold-rolled strip, is used to send a preset value to the upstream trimming device. Thus, the width of the metal strip can be set before cold rolling so that it corresponds to a target width after cold rolling or after a subsequent process, or at least leaves sufficient leeway / adjustment range for the aforementioned adjustment methods, such as online adjustment or two-level preset, so that the strip width can ultimately be set.

[0035] The method according to the invention comprises three adjustment strategies: a) strip width adjustment via presets from a Level 1 system; b) Level 2 tension presets and / or reduction distributions for strip width setting; and c) direct control or adjustment of at least one unit upstream of the cold rolling mill train, such as a trimming machine or side trimming machine for strip width setting. These three adjustment strategies can be implemented individually, jointly, or in any combination. For example, the strip width can be adjusted online, and the optimized strip tension can be fed back to the Level 2 system. The Level 2 system learns from this data and optimizes the presets for the next strip. Attached Figure Description

[0036] The present invention will now be described with reference to the embodiments shown in the accompanying drawings.

[0037] The accompanying drawings show a block diagram of the method according to the present invention, wherein, for the sake of simplicity, only the shearing machine 1 of the hot rolling mill train (not shown) and the cold rolling mill train 2 and their control / regulation units are shown in the block diagram. Detailed Implementation

[0038] The trimming mill 1, also commonly referred to as a trimming machine or side trimming machine, is immediately connected downstream of a hot rolling mill, which may include roughing and finishing mill stands, in which metal strip, for example from a continuous casting unit, is continuously or semi-continuously rolled into hot-rolled strip in different mill stands with decreasing thickness. The hot-rolled strip is trimmed or sheared by means of the trimming mill 1 to a width suitable for the entrance width of the downstream cold rolling mill 2.

[0039] In the illustrated embodiment, the cold rolling mill 2 has three mill stands 33, 34, and 35, in which the cold-rolled strip is rolled to the target thickness to be achieved after the third mill stand 35. At least one measuring device 4 for measuring the width of the cold-rolled strip is provided on the exit side of the cold rolling mill 2. This measuring device 4 continuously and automatically detects the exit width of the metal strip exiting the cold rolling process.

[0040] The measured values ​​from the measuring device 4 are input into the prediction module 5 of the process control unit, and are fed back in parallel and directly to the bandwidth optimization device 6. The bandwidth optimization device 6 can be configured, for example, as a physical-mathematical model, which is formed in the process control unit through a corresponding algorithm.

[0041] The width optimization device 6 communicates directly with the Level 1 system 7 and Level 2 system 8 of the process automation department, as well as with the control unit used for the trimming machine 1.

[0042] Three method blocks 91, 92, and 93 are schematically shown in the width optimization device 6, which schematically represent different adjustment strategies according to the invention. The first method block 91 shows different process parameters that affect the rolling process by directly adjusting the loop, which is integrated into the first-level system 7, for example. The second method block 92 shows another adjustment strategy in which the measured values ​​obtained from the measuring device 4 are optimized and communicatively transmitted to the second-level system 8.

[0043] Method block 93 represents an adjustment strategy in which the control of the trimmer 1 upstream of the cold rolling mill 2 is directly intervened so that the corresponding width of the metal strip is set before cold rolling so that the width corresponds to the target width after cold rolling, or a corresponding margin / adjustment range is left for the above adjustment so that the strip width can be set by appropriate measures.

[0044] The first adjustment strategy shown in method block 91 can, for example, trigger corresponding adjustments to mill stands 33, 34, and 35 via level 1 system 7 to correspondingly change the process parameters of these mill stands 33, 34, and 35, as well as the tension or winding tension in the inter-stand region. In the figure, the drawing sections between mill stands are indicated by reference numerals 12 and 2n, respectively, wherein drawing section 12 is located between the first mill stand 33 and the second mill stand 34, and drawing section 2n is located between the second mill stand 34 and the third mill stand 35.

[0045] If the strip is too wide at the exit of cold rolling mill 2, the tension in the drawing section 12, i.e., the tension in the first interstand region, can be increased, for example, until the desired strip width is achieved or until the intermediate tension is limited by a limit value. If the intermediate tension is limited by a limit value, the tension 2n between the next stands can be increased, for example, and / or the reduction distribution of different stands can be changed in such a way that any shrinkage of the strip is further reduced. This can also be extended to other mill stands within the range of feasible reduction redistribution. This embodiment relates to a cold rolling mill as a tandem mill with three mill stands. The number of mill stands in cold rolling mill 2 is not critical to the invention. The method according to the invention can be applied to cold rolling mills with any number of stands. This also includes cold rolling mills with only one stand.

[0046] The optimized process parameters are sent to the Level 2 system 8 via the second adjustment strategy shown in method block 92. The Level 2 system accordingly presets adjusted settings for the process parameters of the cold rolling mill line 2, changes these settings online, or adjusts these settings for another pass of the same type of subsequent metal strip.

[0047] As mentioned earlier, the measured values ​​from measuring device 4 can also be input into strip width optimization device 6 via prediction module 5. Prediction module 5 may, for example, have a self-learning data table that uses the measured values ​​to predict the shrinkage of the cold-rolled strip. The predicted shrinkage is used as an additional value in the settings of trimming machine 1 and / or as the optimized tension preset in level 2 system 8.

[0048] Furthermore, it may be optionally specified that a cross-process strategy for optimizing the entire production process—casting, hot rolling, and cold rolling—is implemented using information from the cold rolling process. If the strip width is maintained with sufficient precision and the settings of the trimmer 1 are optimized, casting and hot rolling can be optimally adjusted for the target strip width in the upstream hot rolling mill (not shown) based on this width information.

[0049] Therefore, according to the present invention, it can be specified that the regulation and automation of the hot rolling mill line can be intervened in the same manner as described above for the cold rolling mill line 2.

[0050] List of reference numerals

[0051] 1. Edge trimming machine

[0052] 2 Cold Rolling Mill

[0053] 12 First traction section

[0054] 2n Second traction segment

[0055] 33 First Rolling Mill Stand

[0056] 34 Second Rolling Mill Stand

[0057] 35 Third Rolling Mill Stand

[0058] 36 Measuring devices

[0059] 37 Prediction Module

[0060] 38 Width Optimization Device

[0061] 39 Level 1 System

[0062] 40 Level 2 system

[0063] 91. First adjustment strategy of the prediction module

[0064] 92. The second adjustment strategy of the prediction module

[0065] 93. The third adjustment strategy of the prediction module

Claims

1. A method for operating a rolling mill, particularly for rolling flat metal products, wherein, This method includes the following steps: - Measure the actual specifications of the metal strip at the exit of the cold rolling mill (2) and / or immediately before or after the process step following cold rolling. - Compare the actual specifications of the metal strip with the target specifications of the metal strip. - Based on the comparison preset at least one selected process parameter of the cold rolling mill (2) and / or upstream equipment, wherein the process parameter is selected from a group of process parameters including: in particular the strip tension between the mill stands (33, 34, 35), the roll gap of the mill stands (33, 34, 35), the reduction distribution between the mill stands (33, 34, 35), and the specification setting of the hot-rolled strip.

2. The method according to claim 1, characterized in that, The preset includes adjusting and intervening in the Level 1 system (7) of process control and / or presetting process parameters for the Level 2 system (8) and / or presetting the Level 3 system to set the target specifications of the metal strip at the exit of the cold rolling mill (2) and / or at at least one unit downstream of the cold rolling mill.

3. The method according to claim 1 or 2, characterized in that, The equipment upstream of the exit side of the cold rolling mill (2) is selected from the group of equipment including: hot rolling mill, casting machine, welding equipment and / or pickling and / or annealing equipment.

4. The method according to any one of claims 1 to 3, characterized in that, The cold rolling mill train (2) is constructed as a tandem rolling mill train with multiple rolling mill stands (33, 34, 35).

5. The method according to any one of claims 1 to 4, characterized in that, The adjustment intervention on the level 1 system (7) is carried out as an adjustment intervention in at least one adjustment loop, wherein the adjustment loop uses the roll gap with width and / or tension and / or thickness and / or the roll gap of the mill stand (33, 34, 35) in the cold rolling mill row (2) as the adjustment parameter.

6. The method according to any one of claims 1 to 5, characterized in that, The measured value of the actual specification is sent to a software-based prediction module (5), which predicts the possible deviation between the specification of the metal strip and the target specification, and triggers process parameter and / or adjustment interventions to the cold rolling mill (2) and / or the upstream hot rolling mill based on the predicted deviation.

7. The method according to claim 6, characterized in that, The predictions are made using machine learning and / or artificial intelligence methods and / or statistical evaluation methods based on datasets.

8. The method according to any one of claims 1 to 7, characterized in that, The strip width is measured as the actual specification of the metal strip, and the target strip width is preset as the target specification.

9. The method according to any one of claims 1 to 8, characterized in that, The intervention in the Level 1 system (7) includes: adjusting at least one unit, preferably at least one trimming machine (1) or at least one side trimming machine in the upstream hot rolling mill and / or controlling at least one vertical mill stand in the hot rolling mill and / or changing the process parameters of the hot rolling mill to set the strip width of the metal strip in the hot rolling mill.

10. The method according to any one of claims 1 to 9, characterized in that, The measured values ​​of the actual specifications of the metal strip are used to calculate the target strip tension required for the target specifications and / or to calculate the target thickness reduction distribution in the upstream hot rolling mill and / or in the cold rolling mill (2), and the target thickness reduction distribution and / or target strip tension of the hot rolling mill and / or the cold rolling mill (2) are submitted as presets to the Level 2 system (8) to calculate the set values ​​for the units of the hot rolling mill and / or the cold rolling mill (2).

11. The method according to any one of claims 1 to 10, characterized in that, It automatically detects and evaluates measured values.

12. A rolling mill having at least one cold rolling mill line having at least one rolling mill stand, the rolling mill being constructed to operate when using the method according to one or more of claims 1 to 11.

13. The rolling mill according to claim 12, characterized in that, The upstream of the cold rolling mill (2) is connected equipment selected from the group of equipment including: hot rolling mill, casting machine, welding equipment and / or pickling and / or annealing equipment.

14. The rolling mill according to claim 12 or 13, characterized in that, The cold rolling mill (2) is connected downstream of the hot rolling mill, and at least one shearing machine (1) is provided on the exit side of the hot rolling mill or the entrance side of the cold rolling mill (2).

15. The rolling mill according to any one of claims 12 to 13, characterized in that, The cold rolling mill train (2) is constructed as a tandem rolling mill train with multiple rolling mill stands (33, 34, 35).

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