Heating of flat rolled stock made of metal
By detecting and adjusting the position and strength of the heating device, the problem of temperature asymmetry during the heating process of flat rolled parts is solved, automatic symmetric heating is realized, and heating accuracy and consistency are improved.
Patent Information
- Application Number
- CN202380091621.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-01-18
- Filing Date
- 2023-12-07
- Publication Date
- 2025-08-22
AI Technical Summary
In the prior art, the two edges of the flat rolled piece are prone to temperature asymmetric distribution during the heating process, resulting in positioning deviation of the heating device and cannot be automatically adjusted to achieve a symmetric temperature distribution.
The control device is used to detect the characteristic parameters during the heating process in real time. By adjusting the position and heating strength of the heating device, the temperature ratio or difference value of the edges of the two rolled parts is automatically adjusted to achieve the target ratio or difference value, and symmetric heating is achieved.
It realizes automatic adjustment of the position and strength of the heating device during the heating process, ensures the symmetrical temperature distribution of the two edges of the flat rolled piece, improves the accuracy and consistency of heating, and reduces manual intervention and quality problems.
Smart Images
Figure CN120529976A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for heating a flat rolled piece made of metal, which extends transversely to the longitudinal direction from a left rolled piece edge to a right rolled piece edge.
[0002] wherein the left rolling stock edge is heated more intensely than the right rolling stock edge by means of a first inductive heating device, and the right rolling stock edge is heated more intensely than the left rolling stock edge by means of a second inductive heating device,
[0003] wherein, during the heating of the two rolling stock edges, characteristic variables characterizing the heating of the respective rolling stock edges are detected,
[0004] wherein the characteristic variables are fed to a control device, which determines a control command based on the ratio or difference of the two characteristic variables, according to which the lateral positioning of at least one of the two heating devices relative to the edge of the rolled stock heated more intensely by the respective heating device is tracked,
[0005] The control device ascertains the control command in such a way that the ratio of the two characteristic variables approaches a target ratio or the difference of the two characteristic variables approaches a target difference.
[0006] Furthermore, the invention relates to a heating device for a flat rolled product made of metal, which extends transversely to the longitudinal direction from a left rolled product edge to a right rolled product edge.
[0007] wherein the heating device comprises a first inductive heating device, by means of which the left-hand rolling stock edge is heated more intensely than the right-hand rolling stock edge,
[0008] wherein the heating device comprises a second inductive heating device, by means of which the right-hand rolling stock edge is heated more intensely than the left-hand rolling stock edge,
[0009] the heating device comprises a detection device, by means of which a characteristic variable characterizing the heating of the respective rolling stock edge can be detected during the heating of the two rolling stock edges;
[0010] the heating device comprises a control device which is connected to the detection device in order to receive a characteristic variable and which can determine a control command as a function of a ratio or a difference between the two characteristic variables, according to which a lateral positioning of at least one of the two heating devices relative to the rolled stock edge which is heated more intensely by the respective heating device can be tracked,
[0011] The control device determines the control command in such a way that the ratio of the two characteristic variables approaches a target ratio or the difference of the two characteristic variables approaches a target difference. Background Art
[0012] Such a heating method and an associated heating device are known from JP H11172325A. Summary of the Invention
[0013] Hot metal workpieces to be rolled, such as slabs, should have a temperature that is as uniform as possible immediately before rolling. This applies not only in the longitudinal direction of the flat workpiece but also transversely to it. However, the two edges of the flat workpiece cool faster than the intermediate region between them. Therefore, before rolling the flat workpiece, induction heating devices are often used to heat the two edges. The heating devices induce eddy currents in the region of the respective edges. The resulting heating depends not only on the power of the respective heating device but also on its position, in particular, on the distance between the respective heating device and the respective workpiece edge. It generally applies that the electrical energy introduced into the flat workpiece in the region of the respective workpiece edge decreases sharply as the distance between the respective heating device and the respective workpiece edge increases.
[0014] Typically, a flat rolled stock has a symmetrical temperature distribution before being heated by a heating device. Thus, the left and right rolled stock edges, while cooler than the center region of the flat rolled stock between the two rolled stock edges, are equally hot relative to one another. Therefore, the two rolled stock edges should be heated to the same degree to achieve a symmetrical temperature distribution. If the two edges have different temperatures, the temperature difference should generally be compensated for.
[0015] Because the efficiency of the respective heating device depends on the distance from the respective rolling stock edge, it is very important for a symmetrical temperature distribution to adjust the two heating devices symmetrically relative to the rolling stock, that is, to adjust them so that the first induction heating device is at the same distance from the left rolling stock edge as the second induction heating device is from the right rolling stock edge. Although the flat rolling stock can be centered using conventional lateral guidance for the flat rolling stock, slight deviations may occur, for example, due to environmental influences, tolerances, and other inaccuracies.
[0016] In the prior art, the heating device is manually positioned before heating and is not readjusted during the heating process. Consequently, any errors in the positioning of the heating device are not corrected during the heating process. Correction is only performed later when another flat rolled piece is heated.
[0017] Furthermore, it may happen that the temperature distribution of the rolled stock already has an asymmetrical temperature distribution before heating by means of the heating device. In this case, the asymmetry should be compensated as much as possible.
[0018] The object of the present invention is to provide a possibility by means of which, even during the heating of a flat rolled stock, a heating device can be positioned in an automated manner such that heating of the two rolled stock edges is achieved in a defined manner.
[0019] This object is achieved by a heating method having the features of claim 1. Advantageous embodiments of the heating method are the subject matter of dependent claims 2 to 7.
[0020] According to the invention, the heating method of the type mentioned at the outset is designed in such a way that the target ratio or target difference can be re-specified for the control device directly or indirectly at any time. This allows the operator to intervene in the heating process at any time if necessary.
[0021] Typically, the target ratio will have the value 1 or the target difference will have the value 0. However, in individual cases, a target ratio different from 1 or a target difference different from 0 can also be specified. For example, the temperature of the two rolling stock edges can be detected before heating. In particular, a model, function, characteristic curve, or set of characteristic curves can be stored in the control device, allowing the control device to determine the corresponding target variable (ratio or difference) from the temperature detected before heating.
[0022] In the case of indirect pre-determination, for example, a conversion device can be arranged upstream of the control device, which predetermines a temperature ratio or temperature difference. In this case, the conversion device determines a target ratio or target difference based on the temperature ratio or temperature difference and predetermines this target ratio or target difference for the control device. The conversion device can, for example, have an internal characteristic curve or model. In any case, however, the conversion device performs the conversion. In the simplest case, the temperature ratio is 1 or the temperature difference is 0. In this case, the conversion is conventional (target ratio = 1 or target difference = 0).
[0023] This ensures that the desired heating of the two rolling stock edges is also ensured while the flat rolling stock is being heated—that is, during the continuous operation of the associated heating system. If the target ratio has a value of 1 or the target difference has a value of 0, the two rolling stock edges are heated to the same extent by the two heating devices. If the target ratio has a value other than 1 or the target difference has a value other than 0, the two rolling stock edges are heated to different extents by the two heating devices.
[0024] The degree to which the first or second heating device more strongly influences the respective workpiece edge can be adjusted as required. In an extreme case, the two heating devices each influence only the left or right workpiece edge. However, it is also possible that the first heating device more strongly influences the first workpiece edge but also influences the second workpiece edge to a certain extent, and conversely, the second heating device more strongly influences the second workpiece edge but also influences the first workpiece edge to a certain extent.
[0025] The corresponding characteristic variable can be the temperature itself or characterize this temperature.In this case, the temperatures of the two rolling stock edges can be coordinated with each other in a targeted manner, for example adapted to each other.
[0026] However, the corresponding characteristic variable can first characterize the degree to which the corresponding rolling stock edge is heated. In this case, the temperature profiles of the two rolling stock edges can be specifically coordinated with each other, for example, adjusted to the same value. For example, the proportion of electrical energy introduced into the flat rolling stock in the region of the corresponding rolling stock edge by means of the corresponding heating device during a specific time period can be determined absolutely or relatively. This also corresponds to the regulation of the electrical power.
[0027] Preferably, the lateral positioning of the two heating devices is tracked in the same direction, in particular to the same extent, according to the control command. This design has proven to be particularly effective in practice.
[0028] Tracking both heating devices in the same direction means, for example, that if the first heating device is moved to the left by a certain distance, the second heating device is also moved to the left. Thus, if, for example, the first heating device moves away from the left edge of the rolled stock, the second heating device simultaneously approaches the right edge of the rolled stock. If they are moved by the same distance, they are also moved to the left by the same amount, for example.
[0029] The movement of the two heating devices can be carried out, depending on requirements, by means of a common positioning device or by means of two separate positioning devices, the actuation of which is coordinated accordingly.
[0030] Typically, the flat rolled stock is conveyed in the longitudinal direction while being heated. In this case, the detection device for detecting the characteristic variable can be arranged offset in the longitudinal direction relative to the heating device, so that a section of the flat rolled stock first passes through the heating device and only then the detection device. In this way, the characteristic variable can, in particular, characterize the temperature of the corresponding rolled stock edge of the corresponding section after heating. The associated detection device can therefore be designed as a temperature measuring device, for example, as a pyrometer.
[0031] The design of the detection device as a temperature measuring device has the advantage that the temperatures at the left and right edges of the rolled piece can be adjusted to a predetermined ratio or a predetermined difference by heating, and more precisely, this is independent of the values of the temperatures at the left and right edges of the rolled piece before heating.
[0032] Alternatively, it is possible for the characteristic variable to characterize the temperature change of the corresponding section of the flat rolled stock. This embodiment can be implemented independently of whether the flat rolled stock is conveyed in the longitudinal direction during heating. Detecting such a characteristic variable is often easier and less complex to implement.
[0033] For example, characteristic variables can be electrical operating variables of the heating device that occur during operation of the respective heating device, or variables derived from these electrical operating variables. Operating variables can be, in particular, the voltage dropped across the respective heating device and / or the current flowing through the respective heating device. Derived variables can be, in particular, the phase shift between current and voltage, and variables derived therefrom, such as the power introduced into the rolled stock by means of the respective heating device, the inductance of the respective heating device, and / or the resonant frequency of an oscillating circuit formed by a capacitor and the effective inductance of the respective heating device. These values are therefore representative because they are generated dynamically in conjunction with the flat rolled stock and thus allow conclusions to be drawn about the positioning of the respective heating device relative to the respective rolled stock edge.
[0034] In a preferred embodiment, the two heating devices are identically designed, connected in series, and fed by a common energy supply. The corresponding characteristic variable in this case can be the voltage drop across the respective heating device. This embodiment is easy to implement and operates very robustly.
[0035] In another simple embodiment, the two heating devices are designed identically and are each fed by a dedicated energy supply.
[0036] This object is also achieved by a heating device having the features of claim 8. Advantageous embodiments of the heating device are the subject matter of dependent claims 9 to 13.
[0037] According to the invention, a heating system of the type mentioned at the outset is designed in such a way that the control device has an input via which an operator can directly or indirectly re-specify a target ratio or a target difference for the control device at any time.
[0038] The resulting advantages correspond to those of the heating method described.
[0039] Advantageous embodiments of the heating device are also possible. The advantageous embodiments and the resulting advantages correspond to the advantageous embodiments and advantages of the heating method. BRIEF DESCRIPTION OF THE DRAWINGS
[0040] The above-described characteristics, features, and advantages of the present invention and the manner and method of achieving these characteristics, features, and advantages will become more clearly understood in conjunction with the following description of an embodiment, which is explained in detail in conjunction with the accompanying drawings.
[0041] Figure 1 The heating device is shown from above,
[0042] Figure 2 Shown from above Figure 1 A modification of the heating device,
[0043] Figure 3 shows the construction of the heating device,
[0044] Figure 4 A flow chart is shown,
[0045] Figure 5 Another flow chart is shown,
[0046] Figure 6 shows a block diagram of the heating device,
[0047] Figure 7 Shown Figure 6The first modification of the block diagram is
[0048] Figure 8 Shown Figure 6 The second modification of the block diagram of
[0049] Figure 9 A block diagram of another heating device is shown and
[0050] Figure 10 A block diagram of another heating device is shown. DETAILED DESCRIPTION
[0051] Figure 1 A schematic top view of a heating system 1 is shown. In the heating system 1, a flat rolled stock 2 made of metal, particularly steel, is to be heated at least partially. The rolled stock 2 extends along a longitudinal direction x. The rolled stock 2 is subsequently rolled along the longitudinal direction x. The rolled stock 2 extends transversely to the longitudinal direction x along a transverse direction y from a left rolled stock edge 3 to a right rolled stock edge 4.
[0052] The heating device 1 has a first heating device 5 and a second heating device 6. The flat rolled stock 2 can be heated by means of the two heating devices 5, 6. However, the heating of the flat rolled stock 2 by the respective heating devices 5, 6 is not uniform when viewed in the transverse direction y. In particular, the left rolled stock edge 3 is heated more strongly by means of the first inductive heating device 5 than the right rolled stock edge 4. The opposite is true for the second inductive heating device 6. Often, only the respective rolled stock edges 3, 4 are heated by means of the respective heating devices 5, 6. In this case, the heating devices 5, 6 are designed as edge heating devices. The heating devices 5, 6 are designed as inductive heating devices. This is shown by the schematic diagram of the coils surrounding the heating devices 5, 6 and in Figure 1 The corresponding voltages U1, U2 and currents I1, I2 are drawn in FIG.
[0053] In many cases, the rolled stock 2 is conveyed in the longitudinal direction x during heating. Figure 1 This is outlined by corresponding arrows 7 .
[0054] Figure 1 A minimum configuration is shown in which there is only one pair of heating devices 5, 6. However, the heating device 1 according to Figure 2 The diagram in may also have multiple such pairs.
[0055] Figure 3 The design according to the invention of a heating device 1 is shown schematically. Figure 4 The associated operating method is shown in the form of a flow chart.
[0056] according to Figure 4 , the control device 8 starts in step S1 by controlling the heating devices 5 and 6. The heating devices 5 and 6 are thereby activated so that they heat the workpiece 2 (or a section of the flat workpiece 2 that extends within a partial area of the workpiece 2 along the longitudinal direction x). During the heating of the two workpiece edges 3 and 4, the characteristic variables K1 and K2 are detected by means of the detection devices 9 and 10. The characteristic variables K1 and K2 characterize the heating of the corresponding workpiece edges 3 and 4 by the corresponding heating devices 5 and 6. Possible specific characteristic variables K1 and K2 will be explained later. The detection devices 9 and 10 supply the detected characteristic variables K1 and K2 to the control device 8. The control device 8 receives the characteristic variables K1 and K2 in step S2. In step S3, the control device 8 then determines the ratio k=K1 / K2 of the two characteristic variables K1 and K2. In step S4, the control device 8 determines (at least) one adjustment instruction P1, P2 based on the ratio k. Based on Figure 4 , the control device 8 determines the control command or commands P1, P2 such that the ratio k approaches the target ratio k*. Based on the determined control commands P1, P2, the lateral positioning of at least one of the two heating devices 5, 6 relative to the rolled stock edge 3, 4 heated more intensely by the respective heating device 5, 6 is to be tracked. In step S5, the control device 8 then outputs the determined control commands P1, P2 to the respective positioning devices 11, 12.
[0057] In step S6, the control device 8 checks whether the heating of the rolled stock 2 has ended or should end. If and as long as this is not the case, the control device 8 returns to step S2. Otherwise, the control device 8 proceeds to step S7. In step S7, the control device 8 terminates the control of the heating devices 5 and 8. The heating devices 5 and 6 are thus deactivated so that they no longer heat the rolled stock 2.
[0058] It is possible that within the scope of step S5 only the position of one or the other heating device 5, 6 is tracked. However, usually the position of both heating devices 5, 6 is tracked. This can be done on the one hand by: as in Figure 3As depicted in FIG, the two heating devices 5 and 6 are each adjusted by their own positioning device 11 and 12, and their own adjustment commands P1 and P2 are determined for each positioning device 11 and 12. Alternatively, the heating devices 5 and 6 can also be tracked by a common positioning device. For example, the two heating devices 5 and 6 can be arranged on a single crossbeam, and the crossbeam can be moved laterally, so that the lateral movement of the crossbeam also automatically causes the two heating devices 5 and 6 to move laterally.
[0059] Typically, the lateral positioning of the two heating devices 5, 6 is tracked according to the control instructions P1, P2. Figure 3 The diagram in FIG shows tracking in the same direction and to the same extent. Thus, for example, if the first heating device 5 is moved 1 cm to the left, as indicated by arrow 13 on the first heating device 5 , the second heating device 6 is simultaneously moved 1 cm to the left, as indicated by arrow 13 on the second heating device 6 . As a result, the first heating device 5 is simultaneously moved away from the left-hand rolled stock edge 3 , while the second heating device 6 is simultaneously moved closer to the right-hand rolled stock edge 4 . Similar explanations apply to other degrees of movement, as well as to movements in opposite directions. However, it is also possible to track the lateral positioning of only one of the two heating devices 5 , 6 , or to track different degrees of lateral positioning of the two heating devices 5 , 6 .
[0060] In the foregoing, the ratio k of the two characteristic variables K1, K2 is determined and brought close to the corresponding target ratio k*. As an alternative to the ratio k of the two characteristic variables K1, K2, according to Figure 5 The diagram in can also form the difference δK of the two characteristic variables K1, K2, that is, δK=K1-K2, and make the difference δK close to the target difference δK*. In other respects, Figure 5 and Figure 4 consistent.
[0061] According to the present invention, the control device 8 Figure 3 The illustration in FIG has an entry 14 . Via the entry 14 , a target ratio k* (as an alternative: a target difference δK*) can be newly predefined at any time for the control device 8 by an operator 15 directly or indirectly.
[0062] Different specific design solutions will be explained below in conjunction with other drawings, which can be implemented within the scope of the present invention.
[0063] In many of these embodiments, characteristic variables K1, K2 characterize the temperature profile of the corresponding section of the flat rolled stock 2. This applies in particular when the characteristic variables K1, K2 are electrical operating variables of the heating devices 5, 6 that occur during operation of the respective heating devices 5, 6. The electrical operating variables of the heating devices 5, 6 can in particular be the voltage U1, U2 dropped across the respective heating devices 5, 6 or the current I1, I2 flowing through the respective heating devices 5, 6. Alternatively, the characteristic variables K1, K2 can be variables derived from the electrical operating variables. This derivation is typically performed by the detection devices 9, 10.
[0064] For example, according to Figure 6 As shown in the diagram, the two heating devices 5 and 6 can be identically designed, connected in series, and fed by a common energy supply 16. The energy input into the rolled stock 2 by the respective heating devices 5 and 6 is proportional to the power, and therefore to the product of the respective voltage U1 and U2 and the respective current I1 and I2, regardless of the specific wiring of the heating devices 5 and 6. Since the currents I1 and I2 are necessarily identical due to the series connection, the energy input is therefore proportional to the voltages U1 and U2. This makes it possible to use precisely these voltages U1 and U2 (generally: power) as the respective characteristic variables K1 and K2.
[0065] As long as the basic conditions are maintained, namely that the two heating devices 5, 6 are of identical design, are connected in series and are fed by a common energy supply 16, the following applies: Figure 7 The diagrams in the figure include series circuits of coils or according to Figure 8 In the case of a parallel circuit including coils, the energy input is also proportional to the voltages U1 and U2. This also applies to combinations of series and parallel circuits.
[0066] In accordance with Figure 9 In the embodiment of the present invention, the characteristic variables K1, K2 characterize the temperature change of the corresponding section of the flat rolled stock 2. In addition, the characteristic variables K1, K2 are also electrical operating variables of the heating devices 5, 6 that occur during the operation of the corresponding heating devices 5, 6 or are derived from the electrical operating variables. Finally, in accordance with Figure 9 In the design scheme, the two heating devices 5 and 6 are also constructed in the same manner. Figures 6 to 8 Compared with the design scheme of Figure 9 In the embodiment of FIG, the two heating devices 5, 6 are each fed by a dedicated energy supply device 17, 18.
[0067] In accordance with Figure 9 In the case of the embodiment of , the characteristic variables K1, K2 are in particular:
[0068] - The voltage of the corresponding energy supply device 17, 18; this voltage is in accordance with Figure 9 In the embodiment of , the voltages U1 , U2 dropped across the corresponding heating devices 5 , 6 are identical.
[0069] The current I1 , I2 flows through the respective heating device 5 , 6 .
[0070] The effective inductance of the respective heating device 5 , 6 ; this effective inductance is determined not only by the respective heating device 5 , 6 , but also by its interaction with the rolled stock 2 in the region of the respective rolled stock edge 3 , 4 .
[0071] The power introduced into the rolling stock 2 , which is determined by the respective voltages U1 , U2 , the respective currents I1 , I2 and, if appropriate, the respective phase shift between the respective voltages U1 , U2 and the respective currents I1 , I2 .
[0072] - the resonant frequency of the oscillating circuit formed by the respective heating device 5 , 6 in combination with the respective capacitance.
[0073] In order to determine the resonant frequency, for example, the corresponding circumferential phase shift between the voltage U1, U2 dropped across the respective heating device 5, 6 and the current I1, I2 flowing through the respective heating device 5, 6 can be determined, and the corresponding operating frequency of the respective heating device 5, 6 can be tracked until the circumferential shift is equal to zero.
[0074] The effective inductance of the respective heating device 5 , 6 can be inferred from the resonant frequency. The position of the respective heating device 5 , 6 relative to the respective rolled stock edge 3 , 4 can also be determined from the effective inductance. For precise determination, the temperature of the respective heating device may also be required, since the ohmic resistance is temperature-dependent. The temperature, in turn, can depend on the introduced power. Here, too, a model, function, characteristic curve, or set of characteristic curves can be stored in the control device 8 for determining the position.
[0075] at last, Figure 10 Another design is shown. In this design, the detection devices 9, 10 are arranged offset relative to the heating devices 5, 6 along the longitudinal direction x. Figure 10 It is very important for the proper functioning of the heating device 1 that the flat rolled stock 2 is conveyed in the longitudinal direction x during the heating. This conveying is carried out in such a way that a section of the flat rolled stock 2 first passes through the heating devices 5, 6 and only then through the testing devices 9, 10. Figure 10In the case of an embodiment of , the characteristic variables K1 , K2 can directly characterize the temperature T1 , T2 of the respective rolling stock edge 3 , 4 of the respective section after heating.
[0076] The present invention has many advantages. In particular, during the continuous operation of the heating device 1, it is also possible to regulate the heating of the two workpiece edges 3, 4 according to the desired pre-determined conditions (defined by the target ratio k* or target difference δK* of the characteristic parameters K1, K2) and to track them as long as necessary. Quality problems and instabilities during the subsequent rolling can be avoided. This is particularly suitable for rolling the workpiece 2 into ultra-thin strips (strip thickness 1 mm and less). The burden on the operator 15 is reduced. As long as the heating device 1 is adjusted according to the Figure 2 With a plurality of pairs of heating devices 5 , 6 , the non-parallel positioning of the heating devices 5 , 6 relative to the rolled product edges 3 , 4 can also be seen.
[0077] Although the present invention has been illustrated and described in detail by means of preferred embodiments, the invention is not restricted to the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of protection of the invention.
[0078] List of reference numerals:
[0079] 1 Heating equipment
[0080] 2 Rolled products
[0081] 3, 4 rolled piece edges
[0082] 5.6 Heating device
[0083] 7, 13 arrows
[0084] 8 Control device
[0085] 9.10 Detection device
[0086] 11, 12 positioning device
[0087] 14 Entrance
[0088] 15 Operators
[0089] 16 to 18 Energy supply device
[0090] I1, I2 current
[0091] k, k* ratio
[0092] K1, K2 characteristic parameters
[0093] P1, P2 adjustment instructions
[0094] Steps S1 to S7
[0095] T1, T2 temperature
[0096] U1, U2 voltage
[0097] x vertical direction
[0098] y horizontal direction
[0099] δK, δK* difference
Claims
1. A method for heating a flat rolled piece (2) made of metal, the rolled piece extending transversely to the longitudinal direction (x) from a left rolled piece edge to a right rolled piece edge (3, 4), wherein the left-hand rolled stock edge (3) is heated more intensely than the right-hand rolled stock edge (4) by means of a first inductive heating device (5), and the right-hand rolled stock edge (4) is heated more intensely than the left-hand rolled stock edge (3) by means of a second inductive heating device (6), - during the heating of the two rolling stock edges (3, 4), characteristic variables (K1, K2) characterizing the heating of the respective rolling stock edges (3, 4) are detected, - wherein the characteristic variables (K1, K2) are fed to a control device (8), which determines a control command (P1, P2) based on the ratio (k) or the difference (δK) of the two characteristic variables (K1, K2), according to which the lateral positioning of at least one of the two heating devices (5, 6) relative to the rolled stock edge (3, 4) heated more intensely by the respective heating device (5, 6) is tracked, - wherein the control device (8) determines the control command (P1, P2) in such a way that the ratio (k) of the two characteristic variables (K1, K2) approaches a target ratio (k*) or the difference (δK) of the two characteristic variables (K1, K2) approaches a target difference (δK*), It is characterized in that The target ratio (k*) or the target difference (δK*) can be re-specified at any time by an operator (15) directly or indirectly for the control device (8).
2. The heating method according to claim 1, It is characterized in that The lateral positioning of the two heating devices (5, 6) is tracked in the same direction, in particular to the same extent, according to control commands (P1, P2).
3. The heating method according to claim 1 or 2, It is characterized in that The flat rolled piece (2) is conveyed along a longitudinal direction (x) during heating, and detection devices (9, 10) for detecting the characteristic variables (K1, K2) are arranged offset relative to the heating devices (5, 6) along the longitudinal direction (x), so that sections of the flat rolled piece (2) first pass through the heating devices (5, 6) and only then pass through the detection devices (9, 10), and the characteristic variables (K1, K2) characterize the temperatures (T1, T2) of the corresponding rolled piece edges (3, 4) of the corresponding sections after heating.
4. The heating method according to claim 1 or 2, It is characterized in that The characteristic variables (K1, K2) characterize the temperature profile of the corresponding sections of the flat rolling stock (2).
5. The heating method according to claim 4, It is characterized in that The characteristic variables (K1, K2) are electrical operating variables (U1, U2, I1, I2) of the heating devices (5, 6) which occur when the respective heating devices (5, 6) are in operation, or are variables derived from the electrical operating variables (U1, U2, I1, I2).
6. The heating method according to claim 5, It is characterized by: The two heating devices (5, 6) are identically designed, connected in series and fed by a common energy supply (16), and the respective characteristic variables (K1, K2) are the voltages (U1, U2) dropped across the respective heating devices (5, 6).
7. The heating method according to claim 5, It is characterized by: The two heating devices (5, 6) are of identical design and are each fed by a dedicated energy supply device (17, 18).
8. A heating device for a flat rolled piece (2) made of metal, the flat rolled piece extending transversely to the longitudinal direction (x) from a left rolled piece edge to a right rolled piece edge (3, 4), - the heating device comprises a first inductive heating device (5), by means of which the left-hand rolling stock edge (3) can be heated more intensely than the right-hand rolling stock edge (4), - the heating device comprises a second inductive heating device (6), by means of which the right-hand rolled stock edge (4) can be heated more intensely than the left-hand rolled stock edge (3), - the heating device comprises a detection device (9, 10) by means of which characteristic variables (K1, K2) characterizing the heating of the respective rolling stock edges (3, 4) can be detected during the heating of the two rolling stock edges (3, 4), - the heating device comprises a control device (8) which is connected to a detection device (9, 10) in order to receive characteristic variables (K1, K2) and can determine a control command (P1, P2) based on a ratio (k) or a difference (δK) of the two characteristic variables (K1, K2), according to which a lateral positioning of at least one of the two heating devices (5, 6) relative to the rolled stock edge (3, 4) heated more intensely by the respective heating device (5, 6) can be tracked, - wherein the control device (8) determines the control command (P1, P2) in such a way that the ratio (k) of the two characteristic variables (K1, K2) approaches the target ratio (k*) or the difference (δK) of the two characteristic variables approaches the target difference (δK*), It is characterized by: The control device (8) has an input (14) via which an operator (15) can directly or indirectly re-predefine the target ratio (k*) or target difference (δK*) for the control device (8) at any time.
9. The heating device according to claim 7 or 8, It is characterized by: The two heating devices (5, 6) are tracked in the same direction, in particular to the same extent, by a control device (8) according to control commands (P1, P2).
10. The heating device according to claim 7, 8 or 9, It is characterized by: The flat rolled piece (2) is conveyed along the longitudinal direction (x) during heating, the detection devices (9, 10) are arranged offset relative to the heating devices (5, 6) along the longitudinal direction (x), so that sections of the flat rolled piece (2) first pass through the heating devices (5, 6) and only then pass through the detection devices (9, 10), and the characteristic variables (K1, K2) characterize the temperature (T1, T2) of the corresponding rolled piece edges (3, 4) of the corresponding sections after heating.
11. The heating device according to claim 7, 8 or 9, It is characterized in that The detection devices (9, 10) detect electrical operating parameters (U1, U2, I1, I2) of the heating devices (5, 6) that occur when the corresponding heating devices (5, 6) are in operation as characteristic parameters (K1, K2), or derive the characteristic parameters (K1, K2) from the detected electrical operating parameters (U1, U2, I1, I2).
12. The heating device according to claim 11, It is characterized in that The two heating devices (5, 6) are identically designed, connected in series and fed by a common energy supply (16), and the respective characteristic variables (K1, K2) are the voltages (U1, U2) dropped across the respective heating devices (5, 6).
13. The heating device according to claim 11, It is characterized in that The two heating devices (5, 6) are of identical design and are each fed by a dedicated energy supply device (17, 18).