Improved operation of an induction furnace
Patent Information
- Application Number
- EP2023808792
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-12-19
- Filing Date
- 2023-11-17
- Publication Date
- 2025-10-29
AI Technical Summary
In induction furnaces used for heating flat metal rolling stock, the failure of individual induction modules leads to asymmetrical heating and reduced energy input, causing disruptions in the rolling mill operation, as existing methods often require switching off or reducing other modules to maintain symmetry, resulting in significant energy loss.
A control program and heating method that dynamically adjust the target variables of remaining induction modules to compensate for reduced performance of faulty modules, allowing continued operation with minimal load on second modules and potentially moving them to counteract temperature asymmetries, ensuring symmetrical heating and maintaining energy input.
This approach minimizes the impact of module failures by compensating for reduced heating through adaptive adjustments, ensuring uniform heating and maintaining energy input, thereby enhancing operational reliability and flexibility of the induction furnace.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Title of the invention
[0003] Improved operation of an induction furnace
[0004] field of technology
[0005] The present invention is based on a heating method for a flat rolled metal product in an induction furnace,
[0006] - wherein the rolling stock passes through the induction furnace in a longitudinal direction and extends in a transverse direction transverse to the longitudinal direction from a first to a second rolling stock edge,
[0007] - wherein the induction furnace comprises a plurality of module pairs,
[0008] - wherein the module pairs follow one another sequentially in the longitudinal direction and each have a first and a second induction module,
[0009] - wherein the induction modules are positioned at a respective initial position in the transverse direction,
[0010] - wherein the initial positions are determined such that the first induction modules are arranged offset towards the first rolling stock edge and the second induction modules are arranged offset towards the second rolling stock edge,
[0011] - whereby the induction modules are each supplied with electrical energy via a separate energy supply device that is proprietary to the respective induction module,
[0012] - whereby a respective electrical target value is specified for the induction modules,
[0013] - monitoring whether the actual electrical values used to operate the induction modules correspond to their respective target values,
[0014] The present invention is further based on a control program for a control device of an induction furnace in which a flat rolled metal product is to be heated,
[0015] - wherein the rolling stock passes through the induction furnace in a longitudinal direction and extends in a transverse direction transverse to the longitudinal direction from a first to a second rolling stock edge,
[0016] - wherein the induction furnace comprises a plurality of module pairs,
[0017] - wherein the module pairs follow one another sequentially in the longitudinal direction and each have a first and a second induction module,
[0018] - wherein the induction modules are positioned at a respective initial position as seen in the transverse direction, - wherein the initial positions are determined such that the first induction modules are arranged offset towards the first rolling stock edge and the second induction modules are arranged offset towards the second rolling stock edge,
[0019] - whereby the induction modules are each supplied with electrical energy via a separate energy supply device that is proprietary to the respective induction module,
[0020] - wherein a respective electrical target value is defined for the induction modules, wherein the control program comprises machine code which can be processed by the control device, wherein the processing of the machine code by the control device causes the control device to monitor whether electrical actual values with which the induction modules are operated correspond to their respective target values.
[0021] The present invention further relates to a control device of an induction furnace in which a flat rolled metal stock is to be heated, wherein the control device is programmed with such a control program, so that the control device operates the induction furnace according to such a heating method.
[0022] The present invention further relates to an induction furnace for heating a flat rolled metal stock which passes through the induction furnace in a longitudinal direction and extends in a transverse direction transverse to the longitudinal direction from a first to a second rolled stock edge,
[0023] - wherein the induction furnace comprises a plurality of module pairs,
[0024] - wherein the module pairs follow one another sequentially in the longitudinal direction and each have a first and a second induction module,
[0025] - wherein the induction modules are positioned at a respective initial position in the transverse direction,
[0026] - wherein the initial positions are determined such that the first induction modules are arranged offset towards the first rolling stock edge and the second induction modules are arranged offset towards the second rolling stock edge,
[0027] - whereby the induction modules are each supplied with electrical energy via a separate energy supply device that is proprietary to the respective induction module,
[0028] - wherein the induction furnace comprises such a control device which controls the induction furnace according to such a heating method.
[0029] State of the art
[0030] The aforementioned subject matters are generally known to those skilled in the art. Reference can be made purely by way of example to WO 2011 / 009 819 A1. WO 2004 / 000 476 A1 discloses a heating method for flat rolled metal stock in an induction furnace, in which the rolled stock passes through the induction furnace in a longitudinal direction and extends in a transverse direction perpendicular to the longitudinal direction from a first to a second rolled stock edge. The induction furnace has a plurality of module pairs that follow one another sequentially in the longitudinal direction and each have a first and a second induction module. The induction modules are positioned at a respective initial position in the transverse direction. The initial positions are determined such that the first induction modules are offset toward the first rolled stock edge and the second induction modules are offset toward the second rolled stock edge.This is intended to influence the temperature profile of the rolling stock in the transverse direction.
[0031] Summary of the invention
[0032] Before hot rolling a flat metal product, especially steel, the product must be heated to the temperature required for hot rolling. Furthermore, temperature differences that occur within the product must be compensated as much as possible. Heating such a flat product and compensating for temperature differences takes place in a furnace.
[0033] The associated furnaces can be designed in various ways. They are often induction furnaces through which the rolled stock passes in a longitudinal direction. This procedure is particularly common in continuous rolling mills, where the rolled stock is fed into the rolling train directly from the casting heat. The rolled stock can be divided into individual slabs or similar sections before rolling, as required, or it can remain undivided.
[0034] To generate the eddy currents in the flat rolled stock, which cause the corresponding heating via the intrinsic ohmic resistance of the flat rolled stock, longitudinal field modules or transverse field modules can be used as induction modules. In practice, for relatively thick rolled stock, heating is usually achieved using longitudinal field modules. Longitudinal field modules are positioned centrally to the rolled stock. Their position is not changed afterward. For relatively thin rolled stock, heating is usually achieved using transverse field modules.
[0035] Transverse field modules are usually positioned off-center relative to the rolled stock. A single transverse field module therefore generally results in asymmetrical heating of the rolled stock in the transverse direction of the rolled stock. In particular, one of the two rolled stock edges is heated more intensely than the other. To avoid asymmetrical heating of the rolled stock, the transverse field modules are combined into module pairs, with each of the two modules heating one or the other more intensely. The combination of the two transverse field modules of the respective module pair results in - at least essentially - symmetrical heating of the rolled stock.
[0036] During operation of the induction furnace, it can happen that a single induction module fails completely or partially. In this case, the current technology involves shutting down the other induction module of the corresponding module pair or reducing its operation to ensure continued symmetrical heating of the rolled stock. This alone significantly reduces the total energy that can be introduced into the flat rolled stock by the induction furnace. If another induction module of another module pair also fails completely or partially, the same procedure is taken for the other induction module of this module pair. This further exacerbates the situation. The result can be disruptions in the operation of the rolling mill downstream of the induction furnace.
[0037] The object of the present invention is to create possibilities by means of which the effects of the - complete or partial - failure of a single induction module or even several induction modules are kept as low as possible.
[0038] The object is achieved by a heating method having the features of claim 1. Advantageous embodiments of the heating method are the subject of dependent claims 2 to 6.
[0039] According to the invention, a heating method of the type mentioned at the outset is designed in such a way that, in the event that only one actual variable with which one of the first induction modules is operated has a reduced value compared to its corresponding target variable, while maintaining the operation of all second induction modules, both the target variables for the first induction modules which are arranged upstream of the first induction module whose actual variable has a reduced value compared to its corresponding target variable, and the target variables for the first induction modules which are arranged downstream of the first induction module whose actual variable has a reduced value compared to its corresponding target variable are increased, so that a reduced heating of the rolling stock caused by the reduced actual variable is compensated as far as possible.
[0040] This keeps the load on the second induction modules as low as possible. Often, the target values for the second induction modules can be kept unchanged. However, even if the target values of the second induction modules are varied, the second induction modules continue to operate.
[0041] If compensation for the reduced heating of the rolled stock is not possible, the second target values of several of the second induction modules are generally reduced. This ensures, on the one hand, that the rolling stock is heated uniformly or at least symmetrically across the width of the rolled stock, while, on the other hand, the change in heating is distributed across the affected areas of several second induction modules.
[0042] Often, in the event of a complete or partial failure of only a first induction module, no further measures are required. However, if necessary, the second induction modules can also be moved from their respective initial positions. This can counteract asymmetries in the temperature profile of the rolled stock.
[0043] Preferably, furthermore, in the case that both an actual variable with which one of the first induction modules is operated and an actual variable with which one of the second induction modules is operated have a reduced value compared to their corresponding target variable, the target variables for the first induction modules which are arranged upstream of the first induction module whose actual variable has a reduced value compared to its corresponding target variable, the target variables for the first induction modules which are arranged downstream of the first induction module whose actual variable has a reduced value compared to its corresponding target variable, the target variables for the second induction modules which are arranged upstream of the second induction module whose actual variable has a reduced value compared to its corresponding target variable, and the target variables for the second induction modules which are arranged downstream of the second induction module,whose actual value has a reduced value compared to its corresponding target value, are increased so that any reduced heating of the rolling stock caused by the reduced actual values is compensated as far as possible. This allows the effects of the complete or partial simultaneous failure of a first and a second induction module to be kept as low as possible.
[0044] Even in the event of a complete or partial simultaneous failure of both a first induction module and a second induction module, no further measures are often required. However, if necessary, the first and second induction modules can also be moved from their respective starting positions. This can also counteract one-sided heating of one rolling stock edge compared to the other.
[0045] Additional values by which the target values for the first and second induction modules are increased or reduced can be determined as required. In the simplest case, an even distribution is made among the remaining induction modules - separately for the first and second induction modules. Better results, however, are achieved if the additional values are determined as a function of an initial temperature profile of the flat rolled stock before being fed into the induction furnace, operating parameters of the induction furnace (for example, a transport speed at which the rolled stock is conveyed through the induction furnace or a throughput time required for the rolled stock to pass through the induction furnace), and a desired final temperature profile of the flat rolled stock after leaving the induction furnace. The same applies, if necessary, to position changes by which the induction modules are moved.
[0046] The problem is further solved by a control program having the features of claim 7. An advantageous embodiment of the control program is the subject of dependent claim 8.
[0047] According to the invention, the processing of the control program by the control device has the effect that, in addition to the measures already mentioned, in the event that only one actual variable with which one of the first induction modules is operated has a reduced value compared to its corresponding target variable, the control device, while maintaining the operation of all second induction modules, increases both the target variables for the first induction modules which are arranged upstream of the first induction module whose actual variable has a reduced value compared to its corresponding target variable, and the target variables for the first induction modules which are arranged downstream of the first induction module whose actual variable has a reduced value compared to its corresponding target variable, so that a reduced heating of the rolling stock caused by the reduced actual variable is compensated as far as possible.
[0048] Preferably, the processing of the machine code by the control device additionally causes the control device to also implement the additional measures of the advantageous embodiments of the heating method.
[0049] The object is further achieved by a control device having the features of claim 9. According to the invention, the control device is programmed with a control program according to the invention, so that the control device operates the induction furnace according to a heating method according to the invention.
[0050] The object is further achieved by an induction furnace having the features of claim 10. According to the invention, in an induction furnace of the type mentioned at the outset, the control device of the induction furnace is designed as a control device according to the invention.
[0051] Short description of the drawings
[0052] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of an embodiment, which is explained in more detail in conjunction with the drawings.
[0053] FIG 1 an induction furnace and a rolling stock from the side,
[0054] FIG 2 the induction furnace and the rolling stock of FIG 1 from above,
[0055] FIG 3 a flow chart,
[0056] FIG 4 another flow chart,
[0057] FIG 5 another flow chart,
[0058] FIG 6 another flow chart and
[0059] FIG 7 shows another flow chart.
[0060] Description of the embodiments
[0061] According to FIG 1, a flat rolled stock 2 is to be heated in an induction furnace 1. The rolled stock 2 consists of metal, often steel. The rolled stock 2 passes through the induction furnace 1 in a longitudinal direction x. According to FIG 2, it extends in a transverse direction y, which runs transversely to the longitudinal direction x, from a first rolled stock edge 3 to a second rolled stock edge 4. Upon entering the induction furnace 1, the rolled stock 2 has an initial temperature profile T1. Upon leaving the induction furnace 1, the rolled stock 2 has a final temperature profile T2. The temperature profiles T1, T2 are spatially resolved at least in the transverse direction y. The temperature profiles T1, T2 can also vary in the longitudinal direction x.
[0062] Such an induction furnace 1 is often used in a rolling line. It is used to heat the rolled stock 2 prior to rolling and / or to even out the final temperature profile T2 in the transverse direction y. In particular, the final temperature profile T2 should generally be symmetrical in the transverse direction y. In many cases, the temperature of the rolled stock 2 is already relatively high upon entering the induction furnace 1. This is especially true when the induction furnace 1 is located between a continuous casting plant and a rolling mill or between a roughing mill and a finishing mill.
[0063] The induction furnace 1 has a plurality of module pairs 5. In FIGS. 1 and 2, the module pairs are each supplemented by a further number, i.e., designated as module pair 51, 52, etc. Unless a very specific module pair 5 is important below, only the abbreviated reference number 5 is used below. Where reference is made to a very specific module pair 51 to 55, the complete reference number 51, 52, etc. is used. Purely by way of example, it is further assumed below that five module pairs 5 are present. The present invention is explained below in connection with this number of module pairs 5. However, the number of module pairs 5 could also be greater, for example six, seven, or eight. Likewise, the number of module pairs 5 could also be smaller, for example three or four. However, a minimum of two module pairs 5 are present.
[0064] The module pairs 5 follow one another sequentially in the longitudinal direction x. They each have a first and a second induction module 6, 7. The induction modules 6, 7 are each assigned their own proprietary power supply device 8. The respective power supply device 8 is only shown for the two frontmost induction modules 6, 7. It can, for example, be designed as a converter that is fed via a DC voltage circuit. The respective power supply device 8 supplies the respective induction module 6, 7 with electrical energy. Analogous to the module pairs 5, the induction modules 6, 7 are supplemented below with an additional number for individualization if necessary, i.e. as induction module 61, 62, etc. Unless a very specific induction module 6, 7 is required below, only the abbreviated reference symbol 6 or 7 is used below.
[0065] The induction furnace 1 further comprises - see FIG. 1 - a control device 9. The control device 9 is programmed with a control program 10. The control program 10 comprises machine code 11. The machine code 11 can be processed by the control device 9. Based on the programming of the control device 9 with the control program 10 or the processing of the machine code 11 by the control device 9, the control device 9 operates the induction furnace 1 according to a heating method for the rolling stock 2. This heating method is explained in more detail below - initially in conjunction with FIG. 3, later also with reference to FIGS. 4 and 5.
[0066] According to FIG 3, in a step S1, the control device 9 defines respective first starting positions p1* for the first induction modules 6 and respective second starting positions p2* for the second induction modules 7. The first and second starting positions p1*, p2* are determined by the control device 9 as a function of the width b of the rolling stock 2. The first and second starting positions p1*, p2* are determined by the control device 9 such that - assuming appropriate positioning of the induction modules 6, 7 - the first induction modules 6 are arranged offset towards the first rolling stock edge 3 and the second induction modules 7 are arranged offset towards the second rolling stock edge 4. This is particularly evident from FIG 2. The first starting positions p1* are generally uniform for the first induction modules 6. In principle, however, they can also be determined individually.Likewise, the second initial positions p2* are usually uniform for the second induction modules 7. In principle, however, they can also be determined individually.
[0067] In a step S2, the control device 9 outputs the initial positions p1*, p2* (more precisely: the corresponding values) to corresponding positioning devices 12 (see FIG. 2). This positions the first and second induction modules 6, 7 at their respective initial positions p1*, p2*. The positioning devices 12 are also shown in FIG. 2 only for the two frontmost induction modules 6, 7. The positioning devices 12 can be designed, for example, as hydraulic cylinder units.
[0068] Furthermore, in a step S3, the control device 9 defines first electrical target values 11* for the first induction modules 6 and second electrical target values I2* for the second induction modules 6. Generally, the first target values 11* are uniform for the first induction modules 6. Likewise, the second target values I2* are also generally uniform for the second induction modules 7. In principle, however, the target values 11*, I2* can also be determined individually. For example, the target values 11*, I2* can increase or decrease linearly in the longitudinal direction x, or can increase or decrease more or less than linearly.
[0069] The control device 9 outputs the determined target values I1*, I2* (more precisely: the corresponding values) to the corresponding energy supply devices 8 in a step S4. Based on this specification, the energy supply devices 8 apply the corresponding power to the induction modules 6, 7. The induction modules 6, 7 are thus operated with actual values I1, I2 that correspond to the target values I1*, I2*.
[0070] The target values I1*, I2* and thus also the actual values I1, I2 can be determined as required. These can be voltages, currents, or power.
[0071] Analogous to the induction modules 6, 7, the target values 11*, I2* and the actual values 11, I2 are supplemented below with an additional number for individualization if necessary, for example, referred to as target value 112* or actual value 111. Unless a very specific target value 11*, I2* or actual value 11, I2 is required below, only the abbreviated reference symbol 11*, I2* or 11, I2 is used below.
[0072] In a step S5, the control device 9 receives the actual variables I1, I2 (more precisely: the corresponding values) - for example from the energy supply devices 8.
[0073] In step S6, the control device 9 checks whether the first actual variables 11 match the first target variables 11*. If this is the case, the control device 9 proceeds to step S7. In step S7, the control device 9 checks whether the second actual variables I2 match the second target variables I2*. If this is also the case, both the first and second induction modules 6, 7 are functioning properly, so no further action is required. Instead, the process can return directly to step S5.
[0074] If the test in step S7 is negative, (at least) one of the second actual variables 12 is reduced (compared to the corresponding second target variable 12*). In this case, the first induction modules 6 are functioning properly, but the second induction modules 7 are not. Therefore, the control device 9 proceeds to step S8, where it performs appropriate error handling.
[0075] If the test in step S6 is negative, the control device 9 proceeds to step S9. In this case, at least one of the first induction modules 6 is not functioning properly. In step S9, the control device 9 checks whether the second actual values I2 match the second target values I2*. If this is the case, the second induction modules 7 are functioning properly. In this case, the control device 9 proceeds to step S10, where it performs appropriate error handling.
[0076] If the test in step S9 also fails, both the first and second induction modules 6, 7 are not functioning properly. In this case, the control device 9 proceeds to step S11, where it performs appropriate error handling.
[0077] A possible implementation of step S10 is explained below in conjunction with FIG 4, i.e. the situation in which the second induction modules 7 are operating properly, but not the first induction modules 6. Without limiting the generality, it is assumed for the purposes of the following explanations that the first induction module 61 of the first module pair 51 is not operating properly, i.e. the actual value 111 is smaller than the associated target value 111*. If another of the first induction modules 6 were not operating properly, analogous embodiments would result. If several of the first induction modules 6 were not operating properly, the properly operating first induction modules 6 and the improperly operating first induction modules 6 would form two mutually complementary groups. Analogous embodiments would then also result.
[0078] To implement step S10, the control device 9 can, for example, first calculate the difference ÖI1 between the target variable 111* and the actual variable 111 in a step S21. Then, in a step S22, the control device 9 can determine first additional values ÖI12* to ÖI15* for the remaining first induction modules 62 to 65 based on the difference ÖI1. In the simplest case, the control device 9 can, for example, attempt to distribute the difference ÖI1 evenly among the remaining (i.e., the properly functioning) first induction modules 62 to 65, while taking into account the corresponding maximum permissible electrical variables I12max to I15max of the induction modules 62 to 65.The division of the oil 1 difference into quarters is specifically determined in this case by assuming that a total of five module pairs 5 are present, of which, according to the prerequisite, the first induction module 6 of one of the module pairs 5 has failed, and consequently the oil 1 difference can only be divided between the first induction modules 6 of the other four module pairs 5. In a step S23, the first target values 112* to 115* are then increased by the first additional values 112* to 115*. Furthermore, in a step S24, the control device 9 determines the now remaining oil 1 difference.
[0079] If necessary, steps S22 to S24 can be executed multiple times. In this case, however, the distribution of the remaining difference oil 1 varies from iteration to iteration, namely from a quarter to a third to half and finally to the entire difference oil 1 .
[0080] In a step S25, the control device 9 checks whether the remaining difference oil 1 has the value 0, i.e., whether the difference oil 1 originally determined in step S21 could be fully distributed among the remaining first induction modules 62 to 65. If this is the case, the procedure of FIG. 4 can be terminated. If this is not the case, the control device 9 can proceed to a step S26 and subsequently to a step S27. Alternatively, steps S25 to S27 can be omitted, or measures other than those explained below can be taken in steps S26 and S27.
[0081] In step S26, the control device 9 determines second additional values ÖI21* to ÖI25* for the second induction modules 71 to 75. This determination is made based on the remaining difference ÖI1, i.e., the difference öl1 determined during the (possibly last) execution of step S24. In the simplest case, the control device 9 can, for example, distribute the remaining difference öl1 evenly among the second induction modules 71 to 75. In a step S27, the second target variables 121* to 125* are then reduced or decreased by the second additional values ÖI21* to ÖI25*.
[0082] Here is a numerical example:
[0083] If, for example, the first and second induction modules 6, 7 are each intended to apply 2 MW (megawatts) to the rolling stock 2, i.e. the first and second target values I1*, I2* are set accordingly, and the first induction module 61 fails completely (I11 = 0), the priority is given to compensating for this failure by correspondingly increasing the power applied to the rolling stock 2 by the remaining first induction modules 62 to 65. Compensation is performed as far as possible. This means that the first target values I12* to 115* are increased by the first additional values ÖI12* to ÖI15*, but not more than up to their maximum permissible values I12max to I15max. If the maximum permissible power of the induction modules 6, 7 is 2.5 MW or higher, this allocation can be made. However, if the maximum permissible power of the induction modules 6, 7 is, for example, 2.25 MW, it is only possible to go up to this value.In this case, 1 MW remains, which cannot be compensated by the remaining first induction modules 6. If such compensation is not possible, the output of the second induction modules 71 to 75 is generally reduced. This is achieved by reducing the second target values 121* to 125* by the second additional values ÖI21* to ÖI25*. According to the numerical example, the second target values 121* to 125* would thus be reduced such that the second induction modules 7 would each only introduce 1.8 MW into the rolling stock 2. This is because 4 x 2.25 MW = 9 MW = 5 x 1.8 MW applies.
[0084] Alternatively, an asymmetry in the heating of the rolling stock 2 can be accepted, provided that this is acceptable or is associated with minor disadvantages than the reduction of the power introduced into the rolling stock 2.
[0085] A possible implementation of step S8 is self-evident from the implementation of step S10. This is because steps S8 and S10 can be considered mirror images of each other. Therefore, only step S11 will be explained in more detail below, i.e., the situation in which both the first and second induction modules 6, 7 are not functioning properly.
[0086] A possible implementation of step S11 is explained below in conjunction with FIG 5, i.e. the situation in which both the first induction modules 6 and the second induction modules 7 are not working properly. Without limiting the generality, it is assumed for the purposes of the following explanations that the first induction module 61 of the first module pair 51 and the second induction module 75 of the fifth module pair 55 are not working properly, i.e. the actual variable 111 is smaller than the associated target variable 111* and the actual variable I25 is smaller than the associated target variable I25*. If other of the first and second induction modules 6, 7 were not working properly, analogous embodiments would result. Analogous embodiments would also result if several of the first induction modules 6 and / or several of the second induction modules 7 were not working properly.In this case, four groups might have to be formed, namely one group each for the properly operating first induction modules 6, the improperly operating first induction modules 6, the properly operating second induction modules 7 and the improperly operating second induction modules 7.
[0087] To implement step S11, the control device 9 can, for example, first calculate the difference öl 1 between the target value 111* and the actual value 111 in a step S31 and then, in a step S32, determine the first additional values ÖI12* to ÖI15* for the remaining first induction modules 62 to 65 based on the difference öl 1. In a step S33, the first target values 112* to 115* are then increased by the first additional values ÖI12* to ÖI15*. Furthermore, the control device 9 determines the now remaining difference öl 1 in a step S34.
[0088] To implement step S11, the control device 9 can then further calculate the difference ÖI2 between the target variable I25* and the actual variable I25 in a step S35 and, in a step S36, determine second additional values ÖI21* to ÖI24* for the remaining second induction modules 71 to 74 based on the difference ÖI2. In a step S37, the second target variables I21* to I24* are increased by the second additional values ÖI21* to ÖI24*. Furthermore, the control device 9 determines the now remaining difference ÖI2 in a step S38.
[0089] The steps S31 to S34 correspond in content to the steps S21 to S24 of FIG 4. The steps S35 to S38 also correspond in content to the steps S21 to S24 of FIG 4, but with the difference that they are not carried out with respect to the first induction modules 62 to 65, but with respect to the second induction modules 71 to 74. In both cases, however, reference can be made to the above explanations for FIG 4 for details.
[0090] In step S39, control device 9 checks whether the differences between oil 1 and oil 2 determined in steps S34 and S38 have the same value. If so, control device 9 proceeds to step S40. Often, no further action is required in step S40. However, this may be necessary in individual cases. This may be particularly true if the differences between oil 1 and oil 2 have the same value but are different from 0.
[0091] Otherwise, the control device 9 can check in a step S41 whether the difference oil 1 is greater than the difference oil 2. If this is the case, the control device 9 proceeds to a step S42. Otherwise, the control device 9 proceeds to a step S43. Figures 6 and 7 show possible implementations of steps S42 and S43.
[0092] To implement step S42, the control device 9 according to FIG. 6 can first determine the difference between the differences öl 1 and ÖI2 as the resulting difference öl 1 in a step S51. Furthermore, the control device 9 can again determine second additional values ÖI21* to ÖI24* for the second induction modules 71 to 74 in a step S52. In a step S53, the second target variables 121* to 124* can be decreased or reduced by the second additional values ÖI21* to ÖI24*. The content of steps S52 and S53 essentially corresponds to steps S26 and S27 of FIG. 4. For details, reference can therefore be made to the above explanations regarding FIG. 4.The only difference is that steps S26 and S27 are carried out for all second induction modules 71 to 75, while steps S51 and S52 are only carried out for the second induction modules 71 to 74 (i.e. without the second induction module 75) and furthermore the difference oil 1 still to be divided, i.e. the difference oil 1 determined in step S51, is not divided by 5, but only by 4, because only four second induction modules 7 are still available.
[0093] In an analogous manner, the control device 9 according to FIG. 7 can, in order to implement step S43, determine the difference between the differences ÖI2 and öl1 as the resulting difference ÖI2 in a step S61. Furthermore, the control device 9 can again determine first additional values ÖI12* to ÖI15* for the first induction modules 62 to 65 in a step S62. In step S63, the first target variables 112* to 115* can be decreased or reduced by the first additional values öl12* to öl15*. Steps S61 to S63 correspond in content to steps S51 to S53, except that they are not performed with respect to the second induction modules 71 to 74, but with respect to the first induction modules 62 to 65.
[0094] Here is another numerical example:
[0095] If, for example, the first and second induction modules 6, 7 are each intended to apply 2 MW (megawatts) to the rolling stock 2, i.e., the first and second target values I1*, I2* are set accordingly, and the first induction module 61 and the second induction module 75 fail completely (I11 = I25 = 0), the priority is to compensate for these two failures by a correspondingly increased application of the rolling stock 2 by the remaining first and second induction modules 62 to 65, 71 to 74, i.e., to operate the remaining first and second induction modules 62 to 65, 71 to 74 with 2.5 MW each. Compensation is performed as far as possible. This means that the first target values 112* to 115* and the second target values 121* to I24* are increased, but not more than up to their maximum permissible values I12max to I15max, I21max to I24max.If such compensation leads to asymmetrical results, the control of the first or second induction modules 62 to 65, 71 to 74 can be reduced. This is achieved in steps S53 and S63, which are executed alternatively, by the corresponding reduction of the respective target variables 112* to 115*, 121* to 124* by the respective additional values ÖI12* to ÖI15*, ÖI21* to ÖI24*.
[0096] If necessary, an asymmetry in the heating of the rolling stock 2 can also be accepted in conjunction with the procedure according to FIG 5 (and based on this, FIGS 6 and 7), provided that this is acceptable or is associated with smaller disadvantages than the reduction of the power introduced into the rolling stock 2.
[0097] 3 to 7 thus ensures that measures are taken in every case to compensate as far as possible for a reduced heating of the rolling stock 2 caused by a reduced actual variable I11, I25. However, if a specific induction module 6, 7 fails, the same measure is not always taken rigidly; rather, an individual response is made that is adapted to the respective situation. In particular, the behavior of the other induction modules 6, 7 is taken into account across all modules. This is in particular in contrast to the prior art. In the prior art, if a first induction module 6 of a specific module pair 5 fails, the second induction module 7 of this module pair 5 is always switched off as well. The reverse is also true. Only the first and second induction modules 6, 7 of the remaining module pairs 5 continue to operate.
[0098] The difference in the procedure according to the invention is most clearly evident in the procedure explained above in connection with FIG 5. In the prior art, the failure of the induction module 61 would also cause the induction module 71 to be switched off. Furthermore, in the prior art, the failure of the induction module 75 would also cause the induction module 65 to be switched off. This means that the 20 MW with which the rolling stock 2 was previously supplied by a total of 10 induction modules 6, 7 according to the numerical example would have to be supplied by the remaining six induction modules 62 to 64, 72 to 74 in the prior art. Each remaining induction module 6, 7 would therefore have to supply the rolling stock 2 with around 3.3 MW. If - for example - a single induction module 6, 7 could supply the rolling stock 2 with a maximum of 3.0 MW, this value could no longer be achieved. Only a maximum load of 6 x 3.0 MW = 18 MW would be possible.In the inventive procedure, however, a total of eight induction modules 62 to 65, 71 to 74 remain in operation. Thus, to apply a total of 20 MW to the rolling stock 2, each remaining induction module 62 to 65, 71 to 74 only needs to apply 2.5 MW to the rolling stock 2, which, according to the numerical example, is within the permissible load limits.
[0099] In many cases, no further measures are required beyond the procedures in FIGS. 3 to 7. In the case of FIG. 5, however, it is possible, within the scope of steps S40, S42, and S43, to additionally move the first induction modules 6 or at least the remaining first induction modules 62 to 65 by position changes öp1, starting from their respective initial positions p1*. Conversely, it is also possible to move the second induction modules 7 or at least the remaining second induction modules 71 to 74 by position changes öp2, starting from their respective initial positions p2*. The corresponding travel movements are indicated in FIG. 2 for the two foremost induction modules 6, 7 by arrows 13. In the case of FIG. 4, the movement only occurs for the second induction modules 7 or at least the remaining second induction modules 71 to 74.
[0100] Furthermore, the temperature profile T2 can be recorded on the outlet side of the induction furnace 1 and compared with a desired outlet-side temperature profile T2* (i.e. a setpoint or target value for the final temperature profile T2), so that a control loop is formed as a result.
[0101] A very simple procedure was explained above, by means of which the target values 112* to 115* and / or 121* to 124* for the remaining first and / or second induction modules 62 to 65, 71 to 74 can be determined. Likewise, a progressive or degressive gradation is also possible, so that the additional values öl 11* to öl 15*, ÖI21* to ÖI25* are larger (degressive case) or smaller (progressive case), the closer an induction module 6, 7 under consideration is arranged to a failed induction module 6, 7.
[0102] This procedure alone often leads to significant improvements over the prior art. It is even better if the control device 9, as shown in FIG. 1, knows various additional variables and the control device 9 determines the additional values ÖI12* to ÖI15*, ÖI21* to ÖI25* as a function of these variables. The same applies, if necessary, to the determination of the position changes öp1, öp2. The aforementioned variables can include, in particular, the initial temperature profile T1, the desired final temperature profile T2* and operating parameters of the induction furnace 1. Possible operating parameters of the induction furnace 1 are, in particular, the thickness and speed v of the rolling stock 2 and / or the time period t that a specific section of the rolling stock 2 requires to pass through the induction furnace 1. In this case, the control device 9 can, for example, implement a model of the induction furnace 1 and the rolling stock 2.For example, radiation losses can be calculated and thus taken into account in the model.
[0103] The present invention offers many advantages. In particular, it ensures reliable operation of the induction furnace 1. This is especially true when multiple induction modules 6, 7 belonging to different module pairs 5 fail. In this case, in particular, the operation of the induction furnace 1 is guaranteed for longer than if—as in the prior art—the failure of one induction module 6, 7 of a specific module pair 5 would always also shut down the other induction module 7, 6 of this module pair 5. This results in significantly greater flexibility and process stability.
[0104] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.
[0105] 1 induction furnace
[0106] 2 Rolled goods
[0107] 3, 4 rolled stock edges
[0108] 5, 51 to 55 module pairs
[0109] 6, 61 to 66 induction modules
[0110] 7, 71 to 75 induction modules
[0111] 8 Energy supply facilities
[0112] 9 Control device
[0113] 10 Control program
[0114] 11 Machine code
[0115] 12 positioning devices
[0116] 13 arrows b width
[0117] 11 , 111 to 115 Actual sizes 11*, 111* to 115* Target sizes I12max to I15max maximum permissible sizes 121 max to I24max maximum permissible sizes
[0118] 12, 121 to I25 Istg roßen
[0119] I2*, 121* to I25* Target values p1* Initial positions p2* Initial positions
[0120] S1 to S62 steps t time span
[0121] T1 , T2, T2* Temperature profiles v Speed
[0122] X longitudinal direction y transverse direction
[0123] ÖI1, ÖI2 differences
[0124] ÖI12* to ÖI15* Additional values
[0125] ÖI21* to ÖI25* Additional values öp1, öp2 Position changes
Claims
Claims 1. Heating process for a flat rolled metal product (2) in an induction furnace (1), - wherein the rolling stock (2) passes through the induction furnace (1) in a longitudinal direction (x) and extends in a transverse direction (y) running transversely to the longitudinal direction (x) from a first to a second rolling stock edge (3, 4), - wherein the induction furnace (1) has a plurality of module pairs (5), - wherein the module pairs (5) follow one another sequentially in the longitudinal direction (x) and each have a first and a second induction module (6, 7), - wherein the induction modules (6, 7) are positioned at a respective initial position (p1*, p2*) as seen in the transverse direction (y), - wherein the initial positions (p1*, p2*) are determined such that the first induction modules (6) are arranged offset towards the first rolling stock edge (3) and the second induction modules (7) are arranged offset towards the second rolling stock edge (4), - wherein the induction modules (6, 7) are each supplied with electrical energy via a separate energy supply device (8) which is proprietary to the respective induction module (6, 7), - wherein a respective electrical target value (I1*, I2*) is defined for the induction modules (6, 7), - wherein it is monitored whether electrical actual variables (I1, I2) with which the induction modules (6, 7) are operated correspond to their respective target variables (I1*, I2*), characterized in that in the case that only one actual variable (I11) with which one of the first induction modules (61) is operated has a reduced value compared to its corresponding target variable (I11*), while maintaining the operation of all second induction modules (71 to 75), the target variables (I12* to I15*) are both the target variables for the first induction modules which are arranged upstream of that first induction module (61) whose actual variable (I11) has a reduced value compared to its corresponding target variable (I11*), and the target variables (I12* to I15*) for the first induction modules (62 to 65) which are arranged upstream of that first induction module (61) whose Actual value (111) has a reduced value compared to its corresponding target value (111*),are arranged downstream, so that a reduced heating of the rolling stock (2) caused by the reduced actual size (111) is compensated as far as possible., 2. Heating method according to claim 1, characterized in that, if compensation for the reduced heating of the rolling stock (2) is not possible, the second target values (121* to 125*) of several of the second induction modules (71 to 75) are reduced.
3. Heating method according to claim 1 or 2, characterized in that in addition the second induction modules (7) are moved starting from their respective initial positions (p2*).
4. Heating method according to claim 1, 2 or 3, characterized in that in the case that both an actual variable (111) with which one of the first induction modules (61) is operated and an actual variable (I25) with which one of the second induction modules (75) is operated have a reduced value compared to their corresponding target variable (I11*, I25*), the target variables for the first induction modules that are arranged upstream of the first induction module (61) whose actual variable (I11) has a reduced value compared to its corresponding target variable (I11*), the target variables (I12* to I15*) for the first induction modules (62 to 65) that are arranged downstream of the first induction module (61) whose actual variable (I11) has a reduced value compared to its corresponding target variable (I11*), the target variables for the second induction modules (71 to 74) which correspond to the second induction module (75),whose actual size (I75) has a reduced value compared to its corresponding target size (I75*), and the target sizes for the second induction modules which are arranged downstream of that second induction module (75) whose actual size (I75) has a reduced value compared to its corresponding target size (I75*), are increased, so that a reduced heating of the rolling stock (2) caused by the reduced actual sizes (I11, I25) is compensated as far as possible.
5. Heating method according to claim 4, characterized in that in addition the remaining first and second induction modules (6) are moved starting from their respective initial positions (p1*, p2*).
6. Heating method according to one of the above claims, characterized in that additional values (ÖI12* to ÖI15*, ÖI21* to ÖI24*) by which the target values (112* to 115*, 121* to I24*) for the first and second induction modules (62 to 65, 71 to 74) are increased or reduced are determined as a function of an initial temperature profile (T1) of the flat rolling stock (2) before feeding to the induction furnace (1), operating parameters of the induction furnace (1) and a desired final temperature profile (T2*) of the flat rolling stock (2) after leaving the induction furnace (1).
7. Control program for a control device (9) of an induction furnace (1) in which a flat rolled metal product (2) is to be heated, - wherein the rolling stock (2) passes through the induction furnace (1) in a longitudinal direction (x) and extends in a transverse direction (y) running transversely to the longitudinal direction (x) from a first to a second rolling stock edge (3, 4), - wherein the induction furnace (1) has a plurality of module pairs (5), - wherein the module pairs (5) follow one another sequentially in the longitudinal direction (x) and each have a first and a second induction module (6, 7), - wherein the induction modules (6, 7) are positioned at a respective initial position (p1*, p2*) as seen in the transverse direction (y), - wherein the initial positions (p1*, p2*) are determined such that the first induction modules (6) are arranged offset towards the first rolling stock edge (3) and the second induction modules (7) are arranged offset towards the second rolling stock edge (4), - wherein the induction modules (6, 7) are each supplied with electrical energy via a separate energy supply device (8) which is proprietary to the respective induction module (6, 7), - wherein a respective electrical target value (11*, I2*) is defined for the induction modules (6, 7), wherein the control program comprises machine code (11) which can be processed by the control device (9), wherein the processing of the machine code (11) by the control device (9) causes the control device (9) - monitors whether the actual electrical values (11, I2) with which the induction modules (6, 7) are operated correspond to their respective target values (11*, I2*), and - in the event that only one actual variable (111) with which one of the first induction modules (61) is operated has a reduced value compared to its corresponding target variable (111*), while maintaining the operation of all second induction modules (71 to 75), both the target variables for the first induction modules which are arranged upstream of the first induction module (61) whose actual variable (111) has a reduced value compared to its corresponding target variable (111*) and the target variables (112* to 115*) for the first induction modules (62 to 65) which are arranged downstream of the first induction module (61) whose actual variable (111) has a reduced value compared to its corresponding target variable (111*) are increased, so that a reduced heating of the rolling stock (2) caused by the reduced actual variable (111) is compensated as far as possible.
8. Control program according to claim 7, characterized in that the processing of the machine code (11) by the control device (9) causes the control device (9) to implement the additional measures of one of claims 2 to 6.
9. Control device of an induction furnace (1) in which a flat rolled product (2) made of metal is to be heated, wherein the control device is provided with a control program (10) according to claim 7 or 8, so that the control device operates the induction furnace (1) according to a heating method according to one of claims 1 to 6.
10. Induction furnace for heating a flat rolled stock (2) made of metal, which passes through the induction furnace in a longitudinal direction and extends in a transverse direction transverse to the longitudinal direction from a first to a second rolled stock edge, - wherein the induction furnace (1) has a plurality of module pairs (5), - wherein the module pairs (5) follow one another sequentially in the longitudinal direction (x) and each have a first and a second induction module (6, 7), - wherein the induction modules (6, 7) are positioned at a respective initial position (p1*, p2*) as seen in the transverse direction (y), - wherein the initial positions (p1*, p2*) are determined such that the first induction modules (6) are arranged offset towards the first rolling stock edge (3) and the second induction modules (7) are arranged offset towards the second rolling stock edge (4), - wherein the induction modules (6, 7) are each supplied with electrical energy via a separate energy supply device (8) which is proprietary to the respective induction module (6, 7), - wherein the induction furnace comprises a control device (9) according to claim 9, which controls the induction furnace according to a heating method according to one of claims 1 to 6.