Method for producing a metal product

Abstract

The invention relates to a method for producing a metal product in a plurality of successive process steps, each with an assigned set of manipulated variables, the method having the following steps: measuring an actual property of the metal product at a measurement site, at the beginning, during or at the end of one of the process steps, except for the last process step in which the metal product is finished; comparing the actual property of the metal product at the measurement site with a predefined target property of the metal product; determining an adjustment deviation for the property; and adjusting the actual property to the target property by suitably varying at least one of the manipulated variables. In order to make it possible to set the desired target property of the metal strip at the output of the last process stage within narrower tolerances than has been possible in the prior art, according to the invention the target property for the metal product at the output of the last of the successive process steps is predefined, and the at least one manipulated variable for adjusting the actual property of the metal product is selected from a set of manipulated variables which is assigned to at least one process step which comes after the process step to which the measurement site is assigned.

Description

[0001] Method for producing a metal product

[0002] The invention relates to a method for manufacturing a metal product in a plurality of successive process stages in a steelworks. Known process stages in such a manufacturing process include, for example, a blast furnace, a casting machine, a hot rolling mill, etc. Each individual process stage is assigned a set of control variables that can be used to influence the process in each stage.

[0003] The process aims to achieve a specified target property for the metal product at the end of the last of the consecutive process steps. The final process step depends on the desired metal product to be manufactured.

[0004] The use of process models for the (pre-)control or regulation of individual process stages, or of a plurality of successive process stages, has been known for many years in the state of the art. Examples include a pass schedule computer for roughing and finishing rolling mills or process models for controlling a cooling section. For optimal process control, the process models used in the manufacturing process of a rolled end product can be linked to one another, for example, via a process control system. This makes it possible to exchange relevant process variables between the individual models and thus, for example, increase the prediction accuracy of the individual process models.

[0005] An important mechanical property of a metal product is, for example, the grain size, because it influences both the forming behavior of the metal product during rolling, especially during hot rolling, and the transformation behavior of the metal product in a subsequent cooling section. The exact determination of the grain size is of great importance.

[0006] Page 1 is of particular importance. A well-known method for accurately measuring grain size in a metal strip is the so-called laser ultrasound (LUS) method. It is used at various positions within successive process stages to observe the microstructure or microstructure development.

[0007] The property "microstructure" is only an example of a multitude of properties of the metal strip that are traditionally measured in one process stage of the manufacturing process, but which then have no influence on upstream and / or downstream process stages in the manufacturing process to achieve a predetermined target property at the output of a final process stage. The final process stage is the process stage at whose output the metal product is output as desired. In particular, in the event of a deviation of an actual property from an assigned target property, especially in the case of a deviation of the actual microstructure from a target microstructure, no corrections are traditionally made to the settings of the individual process stages during the metal strip's passage.

[0008] The invention is based on the object of developing a known method for producing a metal product in such a way that the adjustment of desired target properties of the metal strip at the exit of the last process stage is made possible within narrower tolerances than was previously possible in the prior art.

[0009] This object is achieved by the method claimed in claim 1. This method is characterized in that the target property for the metal product is specified at the output of the last of the successive process stages and that the at least one control variable for controlling the actual property of the metal product is selected from a set of control variables

[0010] Page 2 is followed by at least one process stage to which the measuring location is assigned.

[0011] The final process step is the one at which the metal product with the desired properties is output. The process according to the invention requires at least two consecutive process steps.

[0012] The term "process stage" refers to a separate facility and is explicitly distinguished from sub-processes within a facility. For example, the hot rolling process stage can be followed by the pickling process stage. The hot rolling process stage can be divided into various sub-processes such as heating and cooling steps, cutting steps, forming steps, etc.

[0013] The term "metal strip" is used consistently throughout the entire manufacturing process, including all process stages. This means that the term does not distinguish between the process stages the metal strip is currently undergoing and how the metal strip is treated at each stage.

[0014] The terms “before” and “behind” or “following” mean upstream and downstream in the direction of production with respect to the respective process stage.

[0015] With the aid of the present invention, it is advantageously possible to expand previously known setting models, which are traditionally used to determine the setting of control variables in individual process stages, so that the control variables can now also be determined with regard to new target properties of the metal product. This provides plant operators with an additional option for optimizing process control with regard to increased production reliability and increased reliability in setting the target properties.

[0016] Page 3 properties of the metal product. This represents a direct competitive advantage given the ever-increasing demands placed on the products manufactured in a steelworks in the individual process stages, for example, by the automotive industry.

[0017] According to the invention, the determined actual properties of the metal product or its preliminary products are used in a process model for the control and / or regulation of, for example, the entire manufacturing process, from the melting and casting process to hot rolling and final cooling in a cooling section and beyond. In particular, the measured actual properties are used by the process model to derive the optimal control variables for the individual process stages with regard to the desired target properties. The optimized control variables determined in this way advantageously lead to an improved adjustment of the final target properties of the hot-rolled metal product, i.e. to an adjustment of its target properties within narrower tolerances than was possible in the prior art.

[0018] The variation of control variables in process stages that follow the process stage with the measuring location claimed here offers the advantage that a metal product that has already been manufactured and does not yet have the desired target properties at the measuring location can possibly still be saved by varying the control variables in the subsequent process stages with a view to achieving the target properties behind the last production stage.

[0019] According to a first embodiment, the term "actual property of the metal strip" is defined. It is clarified that, within the meaning of the invention, this can be either an actual material property, an actual strength parameter, or an actual geometric property of the metal strip.

[0020] Page 4 The examples listed in claim 2 for individual actual properties do not claim to be complete.

[0021] The terms "actual property" and "target property" can each refer to the same property. However, this is by no means mandatory; rather, the terms "actual property" and "target property" can also refer to different properties. This applies in particular when a target property can be derived or calculated from another actual property; and vice versa. In these cases, the present invention assumes that modules are present in the respective control loops, in particular in the process models used, to convert one property into the other. For example, a certain measured grain size as an actual material property allows a conclusion to be drawn about a resulting strength as a target property.

[0022] According to one embodiment, the method according to the invention for producing the metal product comprises at least, for example, some of the following process steps:

[0023] Melting, casting (preferably including strand guiding), hot rolling, pickling, cold rolling, heat treatment, surface coating, temper rolling, and stretch leveling. These process steps are preferably carried out consecutively in the specified order, if required in the individual case.

[0024] Figures 1 and 2 each show examples of different process routes, in which various of the mentioned process stages are carried out one after the other to produce different metal products. Example A shows a complete steel process route in individual steps, in which all of the mentioned process stages follow one another. Example B shows a coupled steel production route for the manufacture of thin strip as a metal product. In this process route, the process stages of casting and rolling are carried out in a CSP®

[0025] Page 5 plant (Compact Strip Production) and the process steps of pickling, heat treatment, surface coating, and skin-passing are combined in a PGL plant (Pickling and Galvanizing Line). A third embodiment shows a coupled steel process route in which the process steps of casting and rolling in a CSP® plant, the process steps of pickling and cold rolling in a PLTCM plant (Coupled Pickling Line and Tandem Coldrolling Mill), and the process steps of heat treatment and skin-passing in a CAL plant (Continuous Annealing Line) are each combined. The claimed method can also be applied accordingly to process routes not shown here for the manufacture of a metal product.

[0026] Figure 2 shows two further embodiments of possible process routes, such as process route D for the production of electrical steel strip, so-called silicon strip, as a metal product and, as embodiment E, an aluminum process route for the production of aluminum strip as a metal product.

[0027] Below, various possible measurement locations for measuring or determining the actual properties of the metal strip are presented. Depending on the measurement location, possible process stages are listed in which specific control variables can be appropriately varied with regard to the desired target properties. This also allows for optimization of the process parameters for at least one of the plant components involved in the manufacturing process for a hot-rolled product.

[0028] If the measuring location for one of the actual properties is in the melting process stage, the control variable for controlling the actual property of the metal product can be selected from the set of control variables that is assigned to one of the process stages that follows the melting process stage, such as one of the casting process stages, optionally including strand guiding, hot rolling, pickling,

[0029] Page 6 Cold rolling, heat treatment, surface coating, skin passing or stretch leveling.

[0030] If the measuring location for one of the actual properties is in the casting process stage, preferably including strand guide, the control variable for regulating the actual property of the metal product can be selected from the set of control variables assigned to one of the process stages following the casting process stage, such as one of the process stages hot rolling, pickling, cold rolling, heat treatment, surface coating, skin passing or stretch leveling.

[0031] If the measuring location for one of the actual properties is in the hot rolling process stage, the manipulated variable for controlling the actual property of the metal product can be selected from the set of manipulated variables assigned to one of the process stages following the hot rolling process stage, such as one of the process stages pickling, cold rolling, heat treatment, surface coating, skin passing or stretch leveling.

[0032] If the measuring location for one of the actual properties is in the pickling process stage, the manipulated variable for controlling the actual property of the metal product can be selected from the set of manipulated variables assigned to one of the process stages following the pickling process stage, such as one of the process stages cold rolling, heat treatment, surface coating, skin passing or stretch leveling.

[0033] If the measuring location for one of the actual properties is in the cold rolling process stage, the control variable for regulating the actual property of the metal product can be selected from the set of control variables that follows the cold rolling process stage, such as one of the heat treatment, surface coating, skin passing or stretch leveling process stages.

[0034] Page 7 If the measuring location for one of the actual properties is in the heat treatment process stage, the manipulated variable for controlling the actual property of the metal product can be selected from the set of manipulated variables that is assigned to one of the process stages that follows the heat treatment process stage, such as one of the surface coating, skin passing or stretch leveling process stages.

[0035] If the measuring location for one of the actual properties is in the surface coating process stage, the manipulated variable for controlling the actual property of the metal product can be selected from the set of manipulated variables that is assigned to one of the process stages that follows the surface coating process stage, such as one of the skin passing or stretch leveling process stages.

[0036] The control variables preferably assigned to the individual process steps are shown by way of example in the table in Fig. 3, pages 1 and 2, and / or in the dependent claims. However, the claimed method can also be applied accordingly to control variables not shown here for the production of a metal product.

[0037] The invention provides that at least one manipulated variable is suitably varied within the context of controlling the actual property to the desired property of the metal strip. This manipulated variable must be selected from a process stage that follows the process stage in which the measurement location for the actual property is located. Furthermore, further manipulated variables can be varied from any other process stage, i.e., from the process stage that corresponds to the process stage to which the measurement location is assigned, or that is located upstream or downstream of it.

[0038] In particular, a first control variable for controlling the actual properties of the metal product can be selected from a set of control variables that is assigned to a first process stage, which is the process stage to which the measuring location

[0039] Page 8, and a second manipulated variable for controlling the same actual properties of the metal product can be selected from a set of manipulated variables assigned to a second process stage following the first process stage.

[0040] The variation of manipulated variables in a process stage that is upstream of the process stage with the measuring location offers the advantage that metal products that are still to be manufactured in the future can be "saved" with regard to the desired target property, even if the metal products produced so far at the measuring location show a deviation between the actual and the target property.

[0041] If the measuring location is, for example, in the "casting" process stage, the control variable "chemical composition of the melt" for a new product can be changed according to the method according to the invention in such a way that (while maintaining the subsequent process control) the desired properties of the hot-rolled product are established at the target position.

[0042] In another example, the desired mechanical properties could also be achieved if the process parameters for the casting process are modified using the method according to the invention in such a way that a microstructure more favorable for achieving the desired properties is achieved, e.g., by changing the temperature control during solidification in the strand. Here, too, the process control during melting or in the subsequent hot rolling process can be maintained.

[0043] The production stages may at least partly be partial production stages for producing the Meta II product as a

[0044] intermediate product.

[0045] Page 9 The manipulated variables can be calculated using a process model, for example, within the framework of a simulation calculation, preferably in real time as set values ​​for the actuators assigned to the manipulated variables. The adjustment of the process parameters just described for each plant component involved in the production of the hot-rolled product can be carried out in such a way that the remaining process control in the other plant components remains unchanged. The method according to the invention is capable of predicting the effect of the changes made to one process step on the subsequent process steps and making corresponding adjustments to the process parameters of these steps yet to be performed.Accordingly, the method according to the invention can also change the setting parameters for more than one participating plant component and predict the effects on the other plant models using the process models used, so that the desired mechanical properties can be achieved in the final product. The complexity increases accordingly, the more variations of the setting parameters are made.

[0046] Page 10

Claims

Patent claims:

1. A method for producing a metal product in a plurality of successive process stages, each with an associated set of control variables, comprising the following steps: Measuring an actual property of the metal product at a measuring point at the beginning, within or at the end of at least one of the process stages, except the last process stage in which the metal product is completed; Comparing the actual property of the metal product at the measuring point with a predetermined target property of the metal product, determining a control deviation for the property and controlling the actual property to the target property by suitable variation of at least one of the manipulated variables; characterized in that the target property for the metal product is predetermined at the output of the last of the successive process stages; and that the at least one manipulated variable for controlling the actual property of the metal product is selected from a set of manipulated variables that is assigned to at least one process stage that follows the process stage to which the measuring point is assigned.

2. Method according to claim 1, characterized in that the actual property of the metal strip is: its actual material property, such as its grain size, its microstructure or its microstructure distribution in the case of mixed microstructures, its actual strength parameters, such as its yield strength, tensile strength, elongation at break, uniform elongation; and / or its actual geometric Page 11 Properties such as flatness, profile, width, and / or thickness. A method according to claim 1 or 2, wherein the process stages are, for example: melting, casting including strand guiding, hot rolling, pickling, cold rolling, heat treatment, surface coating, skin contact, and / or stretch straightening; and wherein the aforementioned process stages, or a selection thereof, are preferably carried out sequentially in the aforementioned order during the manufacture of the metal product. A method according to claim 3, characterized in that the measurement location for one of the actual properties is in the melting process stage; and that the control variable for regulating the actual property of the metal product is selected from the set of control variables that are assigned to at least one of the process stages following the melting process stage, such as one of the process stages casting, hot rolling, pickling, cold rolling, heat treatment, surface coating, skin contact, or stretch straightening.Method according to one of claims 3 or 4, characterized in that the measuring point for one of the actual properties is located in the casting process stage, preferably including strand guidance; and that the control variable for regulating the actual property of the metal product is selected from the set of control variables that is assigned to at least one of the process stages following the casting process stage, such as one of the process stages hot rolling, pickling, cold rolling, heat treatment, surface coating, or skin dressing. Page 12 or stretch straightening. A method according to any one of claims 3 to 5, characterized in that the measurement location for one of the actual properties is located in the hot rolling process stage, optionally including roughing mill, heating and / or cooling devices; and that the manipulated variable for controlling the actual property of the metal product is selected from the set of manipulated variables that is assigned to at least one of the process stages following the hot rolling process stage, such as one of the process stages pickling, cold rolling, heat treatment, surface coating, skin dressing, or stretch straightening. A method according to any one of claims 3 to 6, characterized in that the measurement location for one of the actual properties is located in the pickling process stage; and that the manipulated variable for controlling the actual property of the metal product is selected from the set of manipulated variables that is assigned to at least one of the process stages following the pickling process stage, such asOne of the process stages is cold rolling, heat treatment, surface coating, skin dressing, or stretch straightening. A method according to one of claims 3 to 7, characterized in that the measurement location for one of the actual properties is in the cold rolling process stage; and that the control variable for regulating the actual property is selected from the set of control variables that are available in at least one of the process stages. Page 13 is assigned to the process stage that follows the cold rolling process, such as one of the process stages heat treatment, surface coating, skin dressing or stretch straightening.

9. Method according to one of claims 3 to 8, characterized in that the measurement location for one of the actual properties is in the heat treatment process stage; and that the manipulated variable for controlling the actual property is selected from the set of manipulated variables that is assigned to at least one of the process stages following the heat treatment process stage, such as one of the surface coating, dressing or stretch straightening process stages.

10. Method according to one of claims 3 to 9, characterized in that the measuring point for one of the actual properties is located in the process stage surface layers; and that the manipulated variable for controlling the actual property is selected from the set of manipulated variables that is assigned to at least one of the process stages that follows the process stage surface coating, such as one of the process stages dressing or stretch straightening.

11. Method according to one of claims 3 to 10, characterized in that the quantity of control variables assigned to the melting production stage preferably comprises the following control variables: charging, alloy composition, process control.

12. Method according to any one of claims 3 to 11, characterized in that, Page 14 that the quantity of control variables assigned to the production stage of casting preferably includes the following control variables: Batch size, casting speed, casting thickness, if necessary, adjustment of the casting thickness during casting, e.g., via Liquid Core Reduction (LCR) or Dynamic Soft Reduction (DSR), casting width, if necessary including adjustment of the casting width during casting, and cooling parameters. A method according to any one of claims 3 to 12, characterized in that the quantity of control variables assigned to the hot rolling production stage, optionally including pre-rolling mill, heating and / or cooling devices, preferably comprises the following control variables: Heating parameters, such as furnace temperatures, furnace atmosphere, holding times, inductor power, and temperature losses over transport sections; rolling temperatures; forming parameters, such as degree of deformation and distribution of the degrees of deformation, including their redistribution if necessary; strip thickness, rolling force, rolling speed, rolling torque, strip width, lubrication, and tension, yield strength, tensile strength, microstructure; cooling parameters, such as the location of coolant application, the quantity of coolant, and the duration of this cooling, also in the cooling section with regard to phase transformation and / or holding times; flatness and profile parameters, such as roll bending, displacement, and / or camber, as well as sabering and trimming width. A method according to one of claims 3 to 13, characterized in that the quantity of control variables assigned to the pickling production stage preferably comprises the following control variables: Pickling duration, pickling bath temperature, composition of the pickling solution, Page 15 Throughput speed of the metal strip, trimming width. Method according to one of claims 3 to 14, characterized in that the quantity of control variables assigned to the cold rolling production stage preferably comprises the following control variables: Strip dryness, rolling temperature, forming parameters such as strip tension, degree of deformation, pass distribution, strip thickness, rolling speed, rolling force, lubrication conditions in the roll gap, strip tension, trimming width. Method according to one of claims 3 to 15, characterized in that the quantity of control variables assigned to the heat treatment production stage preferably comprises the following control variables: Heating parameters, such as heating rate, initial / final temperature, holding times, furnace atmosphere and / or heating rate; strip feed control parameters, such as throughput speed and tension, yield strength, tensile strength, texture, microstructure, annealing temperature; cooling parameters, such as location of coolant application, quantity of coolant, cooling duration, and coolant temperature, also in the cooling section with regard to phase transformation and / or holding times; pretreatment, e.g., strip cleaning. A method according to any one of claims 3 to 16, characterized in that the set of control variables assigned to the surface coating production stage preferably comprises the following control variables: strip temperature, oxidized or reduced strip surface immediately before coating; temperature of the coating agent. Page 16 Layer thickness, coating quality; throughput speed, pretreatment, e.g., belt cleaning. Method according to one of claims 3 to 17, characterized in that the quantity of control variables assigned to the production stage of dressing preferably comprises the following control variable: Degree of dressing, such as angle and strip tension, surface roughness, yield strength, tensile strength, texture, flatness parameters, such as roll bending and displacement. Method according to one of claims 3 to 18, characterized in that the quantity of control variables assigned to the stretch straightening production stage preferably comprises the following control variable: Tense profiles, flatness parameters such as immersion depth and degree of draw. A method according to one of the preceding claims, characterized in that at least one further manipulated variable for controlling the actual property of the metal product is selected from a set of manipulated variables that is assigned to any process stage that corresponds to, or is upstream or downstream of, the process stage to which the measuring point is assigned. A method according to claim 20, characterized in that a first manipulated variable for controlling the actual properties of the metal product is selected from a set of manipulated variables that is assigned to a first process stage that follows the process stage to which the measuring point is assigned; and Page 17 that a second control variable for regulating the same actual properties of the metal product is selected from a set of control variables assigned to a second process stage that follows the first process stage. A method according to one of the preceding claims, characterized in that the production stages are each sub-production stages for manufacturing the metal product as an intermediate product. A method according to one of the preceding claims, characterized in that the control variables are calculated using a process model, for example within the framework of a simulation, preferably in real time, as setpoints for the actuators assigned to each of the control variables. 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