Production line for producing and / or processing metal workpieces

Abstract

The invention relates to a production line (1) for producing and / or processing metal workpieces (2) conveyed in a conveying direction (R1), said production line (1) having at least one first forming device (4), a second forming device (5) connected to the first forming device (4) by means of a first transport device (60), and at least one induction heating device (3) for heating a metal workpiece (2) conveyed in the conveying direction (R1). The induction heating device (3) has a first coil (10) which is mounted so as to be positionally adjustable in a first direction (R2) in such a way that a first normal distance between the first coil (10) and a workpiece (2) located in the induction heating device (3) can be changed, and the induction heating device (3) has a second coil (20) which is mounted so as to be positionally adjustable in the first direction (R2) in such a way that a second normal distance between the second coil (20) and a workpiece (2) located in the induction heating device (3) can be changed. The induction heating device (3) has at least one energy supply device (50) which is electrically connected to the first coil (10) and / or the second coil (20) and which is designed to supply the first coil (10) and the second coil (20) with an alternating current and / or an alternating voltage in such a way that the penetration depth δ of current-carrying layers of the conveyed metal workpiece (2) is less than or equal to 0.7 times the thickness extension (t) of the conveyed metal workpiece (2).

Description

[0001] Production line for the manufacture and / or processing of metallic workpieces

[0002] The present invention relates to a production line for the manufacture and / or processing of metallic workpieces.

[0003] In production lines for the manufacture and / or processing of metallic workpieces, such as hot rolling mills, continuous metallic workpieces are subjected to both thermal and mechanical treatment. This often occurs in close conjunction, so that a metallic workpiece is heated to a temperature specifically required for an immediately subsequent mechanical processing step, such as forming. The thermal treatment takes place in conventional heating devices such as furnaces, or by means of induction heating devices, or by means of a combination of both.

[0004] Known induction heating devices for heating continuous metallic workpieces have coils which are fixed relative to the metallic workpieces and / or are adjustable in position vertically and / or horizontally relative to a conveying direction of the metallic workpieces, wherein the metallic workpieces are guided past the respective coil in a conveying direction.

[0005] The coils of such induction heating devices are supplied with electrical energy from an electrical energy source by means of power electronic components such as transformers, inverters, rectifiers, and capacitors. This allows induction heating devices to be configured for transverse field induction or longitudinal field induction, whereby more homogeneous heating of metallic workpieces can be achieved by longitudinal field induction. Known longitudinal field induction devices typically have coils that are stationary relative to the metallic workpieces. Furthermore, known longitudinal field induction devices have coils that wrap around the metallic workpieces.

[0006] In such induction heating devices with fixed coils, the distance between the fixed coils and the metallic workpieces is always designed such that even metallic workpieces with the largest possible dimensions, viewed transversely to the conveying plane of the respective induction heating device, do not collide with the fixed coils. This means that the coils must always be spaced at the greatest possible safety distance from the metallic workpieces. However, this intended safety distance has the consequence that the achievable electrical efficiency of the respective induction heating device is considerably reduced. This represents a considerable disadvantage, particularly in production lines for the processing and / or manufacture of metallic workpieces of different dimensions.In the case of induction heating devices with coils wrapping around the metallic workpieces, it is also not possible to move the device out of a production line while metallic workpieces are still in the line. This severely limits the flexibility of production lines with regard to the manufacture and / or processing of metallic workpieces of different dimensions. Furthermore, it is not possible to react quickly to any fluctuations in heating homogeneity, since, for example, it is not possible to add or remove an additional induction heating device to specifically increase or reduce the thermal energy introduced into the metallic workpiece during ongoing production.

[0007] The object of the present invention is to provide a production line by which the electrical efficiency between the coils and the metallic workpieces is improved and the flexibility for producing metallic workpieces of different dimensions is increased.

[0008] This object underlying the present invention is achieved by a production line having the features of claim 1. Advantageous embodiments of the production line are described in the dependent claims.

[0009] More specifically, the object underlying the present invention is achieved by a production line for producing and / or processing metallic workpieces conveyed in a conveying direction, wherein the production line has at least a first forming device and a second forming device connected to the first forming device by means of a first transport device.The production line has at least one induction heating device for heating a metallic workpiece conveyed in the conveying direction, wherein the induction heating device has a first coil which is mounted so as to be positionally adjustable in a first direction such that a first normal distance between the first coil and a workpiece located in the induction heating device can be changed, and wherein the induction heating device has a second coil which is mounted so as to be positionally adjustable in the first direction such that a second normal distance between the second coil and a workpiece located in the induction heating device can be changed, wherein the first coil and / or the second coil is / are electrically connected to a first capacitor device.The induction heating device has at least one energy supply device electrically connected to the first coil and / or the second coil, wherein the energy supply device is designed to supply the first coil and the second coil with alternating current and / or alternating voltage in such a way that a penetration depth 5 of current induced by means of the first coil and / or the second coil into current-carrying layers of the conveyed metallic workpiece is less than or equal to 0.7 times a thickness extension of the conveyed metallic workpiece.

[0010] The current density of a current induced by the alternating magnetic fields of the first and / or second coil in a metallic workpiece located in the induction heating device decreases from the respective surface of the metallic workpiece over a thickness extension of the metallic workpiece. The penetration depth 5 of the current induced by the first coil and the second coil into current-carrying layers is defined, starting from the surface of the metallic workpiece, as the penetration depth at which the current density of the induced current has decreased to the e-th part of the current density of the induced current at the surface of the metallic workpiece, where e is Euler's number. The penetration depth 5 is determined according to the following formula (1):

[0011] Where the following applies: p = specific electrical resistance, in Qm, n = number of circles,

[0012] Po =magnetic field constant, in N / A 2 , p r = relative permeability , dimensionless , and f = frequency , in 1 / s .

[0013] The penetration depth 5 increases with decreasing frequency of the induced current. Consequently, the current density of the induced current decreases more slowly across the thickness of the metallic workpiece, starting from the surface of the metallic workpiece, as the frequency of the induced current decreases. As a result, deeper layers of the metallic workpiece, as seen from the surface of the metallic workpiece, are also heated, so that increased heating homogeneity is achieved along the thickness of the metallic workpiece.

[0014] According to formula ( 1 ) it can be seen that the penetration depth 5 depends on the frequency of the alternating currents flowing through the first coil and the second coil as well as on the material of the conveyed metallic workpiece by the relative permeability p r depends. A power supply device which is designed to supply the first coil and the second coil with alternating current and alternating voltage so that a defined penetration depth 5 is achieved is consequently designed to supply the first coil and the second coil with alternating current and alternating voltage of a suitable frequency. With the known relative permeability p r of the conveyed metallic workpiece, the penetration depth 5 can therefore be set according to formula ( 1 ).

[0015] The energy supply device can be configured to supply the first coil and the second coil with alternating current and / or alternating voltage, such that the penetration depth 5 of current induced by means of the first coil and / or the second coil into current-carrying layers of the conveyed metallic workpiece is <0.6 times, <0.5 times, <0.45 times, <0.4 times, <0.35 times or <0.3 times the thickness of the conveyed metallic workpiece. It has been shown that a production line designed in this way has the advantage that during the inductive heating of the metallic workpiece, a high electrical efficiency is achieved between the coils and the metallic workpiece and, at the same time, an increased heating homogeneity of the metallic workpiece, in particular an increased heating homogeneity in the thickness of the metallic workpiece, is achieved.

[0016] According to a preferred embodiment, the energy supply device can be configured to supply the first coil and the second coil with alternating current and / or alternating voltage, so that the penetration depth 5 of current induced by means of the first coil and / or the second coil into current-carrying layers of the conveyed metallic workpiece is in a range of <0.6 times and >0.3 times, <0.5 times and >0.3 times, <0.6 times and >0.4 times, <0.5 times and >0.4 times, <0.45 times and >0.3 times, or <0.4 times and >0.3 times the thickness extension of the metallic workpiece.According to a particularly preferred embodiment, the energy supply device can be configured to supply the first coil and the second coil with alternating current and / or alternating voltage, so that the penetration depth 5 of current induced by means of the first coil and / or the second coil into current-carrying layers of the conveyed metallic workpiece lies in a range of < 0.45 times and > 0.4 times the thickness extension of the metallic workpiece.

[0017] It was shown that a production line designed in this way has the advantage that, during the inductive heating of the metallic workpiece, a further increased electrical efficiency between the coils and the metallic workpiece and, at the same time, a further increased heating homogeneity of the metallic workpiece, in particular a further increased heating homogeneity in the thickness extension of the metallic workpiece, is achieved.

[0018] According to a particularly preferred embodiment, the energy supply device can be configured to supply the first coil and the second coil with alternating current and / or alternating voltage, so that the penetration depth 5 of current induced by means of the first coil and / or the second coil into current-carrying layers of the conveyed metallic workpiece is equal to 0.45 times the thickness extension of the conveyed metallic workpiece.

[0019] It was shown that a production line designed in this way has the advantage that, during the inductive heating of the metallic workpiece, a particularly high electrical efficiency between the coils and the metallic workpiece is achieved, while at the same time a particularly increased heating homogeneity of the metallic workpiece is achieved, in particular a particularly increased heating homogeneity in the thickness extension of the metallic workpiece.

[0020] The electrical efficiency in the sense of the invention is defined by the ratio between the electrical energy applied to the coils and the heat input generated thereby in the metallic workpiece.

[0021] The electrical efficiency is preferably adjustable depending on the first normal distance and / or the second normal distance. The smaller the first normal distance and / or the second normal distance, the better the electrical efficiency can be.

[0022] Preferably, the first normal distance and / or the second normal distance are set to a minimum value during operation of the production line and / or the induction heating device. In other words, a minimum distance between the first coil and a surface of the metallic workpiece corresponding to the first coil and / or a minimum distance between the second coil and a surface of the metallic workpiece corresponding to the second coil is set, without direct contact occurring between the coils and the metallic workpiece.

[0023] A power supply device is designed to provide electrical energy for operating at least one coil, in particular electrical energy with an electrical current of suitable current intensity, suitable voltage and / or suitable frequency. The present power supply device can be designed to provide electrical energy for a plurality of coils, in particular for at least two coils, preferably for three, four, five, six or more coils. The power supply device can have at least one power converter, in particular an inverter, or can be designed as such.

[0024] A metallic workpiece can be designed as a substantially flat workpiece. The workpiece can be designed, for example, as a metal slab, a metal strip, or a shaped blank.

[0025] A substantially flat workpiece within the scope of the invention has a thickness extension which is substantially smaller than a width extension and a length extension.

[0026] The length of a metallic workpiece is the length of the metallic workpiece in the conveying direction. The thickness of the metallic workpiece is the length of the metallic workpiece in the first direction.

[0027] The width extension of the metallic workpieces is the extension of the metallic workpieces in the direction of a second direction .

[0028] The conveying direction, the first direction, and the second direction form an orthogonal coordinate system. The conveying direction and the second direction define a conveying plane. A plane defined by the length and width of a metallic workpiece conveyed in the conveying direction is preferably aligned parallel to the conveying plane.

[0029] A metallic workpiece has a first outer edge and a second outer edge opposite the first outer edge. The first outer edge and the second outer edge delimit the metallic workpiece in the widthwise extent of the metallic workpiece.

[0030] The first forming device and / or the second forming device can have one or more forming devices. The forming devices can be designed as a rolling device, a pressing device, a deep-drawing device, an embossing device, a punching device, or a combination of the aforementioned devices. In other words, the first forming device and / or the second forming device can each be designed as a single forming stand or as a multi-stand forming device.

[0031] The first transport device can be designed as a conveyor belt or a roller conveyor. The first capacitor device can have a single capacitor or a plurality of capacitors. The plurality of capacitors can be connected in parallel.

[0032] The first coil preferably has at least one turn formed by at least two first conductor profiles connected by a first connecting web. The second coil preferably has at least one turn formed by at least two second conductor profiles connected by a second connecting web.

[0033] The first connecting web can be connected to the two first conductor profiles such that the first coil has a U-shape. The second connecting web can be connected to the two second conductor profiles such that the second coil has a U-shape.

[0034] The two first conductor profiles are preferably welded to the first connecting web and further preferably connected monolithically. The two second conductor profiles are preferably welded to the second connecting web and further preferably connected monolithically.

[0035] The conductor profiles of the first coil and / or the second coil can have a rectangular profile cross-section in a cross-sectional plane spanned by the conveying direction and the first direction. The connecting web of the first coil and / or the second coil can have a rectangular profile cross-section in a cross-sectional plane spanned by the first direction and the second direction.

[0036] The conductor profiles of the first coil and / or the second coil can have a hollow profile cross-section, preferably a rectangular hollow profile cross-section, in a cross-sectional plane spanned by the conveying direction and the first direction.

[0037] The connecting web of the first coil and / or the second coil can have a hollow profile cross-section, preferably a rectangular hollow profile cross-section, in a cross-sectional plane spanned by the first direction and the second direction.

[0038] The free cross-sections of the conductor profiles and the connecting web of the first coil can form a first cooling fluid channel. The free cross-sections of the conductor profiles and the connecting web of the second coil can form a second cooling fluid channel of the second coil.

[0039] The production line may comprise a cooling device for cooling the coils of the induction heating device, wherein the cooling device comprises at least one first cooling circuit having a first inlet and a first outlet fluidly connected to the first inlet via the first cooling fluid channel. In other words, the first cooling circuit may extend at least partially through the first cooling fluid channel inside the first coil.

[0040] The first cooling circuit can further comprise a second inlet and a second outlet fluidly connected to the second inlet through the second cooling fluid channel. In other words, the first cooling circuit can extend at least partially through the second cooling fluid channel inside the second coil.

[0041] The cooling device can have at least one second cooling circuit, which has a second inlet and a second outlet fluidly connected to the second inlet through the second cooling fluid channel. In other words, the cooling circuit runs at least partially through the second cooling fluid channel inside the second coil.

[0042] The cooling device can be configured to provide a cooling capacity of > 500 kW or > 750 kW or > 1000 kW for a period of at least one hour, preferably for a period of 23 hours per day. The cooling device can be configured to provide a cooling capacity of greater than or equal to 20%, preferably greater than or equal to 30%, of the electrical power provided by the energy supply device for the first and / or second coil.

[0043] The conductor profiles and the connecting web of the first coil and / or the second coil can have a substantially constant wall thickness. The wall thickness can be designed as a function of the electrical penetration depth of the current flowing through the conductor profiles and the connecting webs of the first coil and / or the second coil. The wall thickness can have an amount greater than or equal to 2 times the electrical penetration depth, preferably greater than or equal to 3 times the electrical penetration depth, and particularly preferably greater than or equal to 4 times the electrical penetration depth.

[0044] A production line designed in this way has the advantage that the induction heating device can heat the metal workpieces with increased efficiency. By selecting the wall thickness of the conductor profiles and the connecting web of the coils depending on the electrical penetration depth of the current flowing through the coils, both the power loss within the coils is reduced and a smaller amount of material is required for their manufacture.

[0045] The conductor profiles and the connecting web of the first coil and / or second coil can have an extension in the first direction of less than or equal to 40 mm, preferably less than or equal to 35 mm and particularly preferably less than or equal to 30 mm.

[0046] The conductor profiles of the first coil and / or second coil can have an extension in the conveying direction of less than or equal to 60 mm, preferably less than or equal to 55 mm and particularly preferably less than or equal to 50 mm.

[0047] The connecting web of the first coil and / or second coil can have an extension in the second direction of less than or equal to 60 mm, preferably of less than or equal to 55 mm and particularly preferably of less than or equal to 50 mm.

[0048] The production line preferably has an adjusting device for adjusting a position of the first coil and / or the second coil in the first direction and / or in the second direction.

[0049] The adjusting device can be configured to adjust a position of the first coil and / or the second coil in the first direction such that a first normal distance between the first coil and a metallic workpiece located in the induction heating device and / or a second normal distance between the second coil and the metallic workpiece located in the induction heating device of < 100 mm or < 50 mm or < 40 mm or < 30 mm or < 20 mm is established.

[0050] The adjustment device can comprise one or more hydraulic cylinders, rack and pinion drives, or toggle levers for adjusting a position of the first coil and / or the second coil in the first direction. The adjustment device can comprise one or more travel units, trolleys, wheel-rail systems, and / or sliding systems for adjusting a position of the first coil and / or the second coil in the second direction.

[0051] The adjusting device can be configured to adjust a position of the first coil in the first direction independently of a position of the first coil in the second direction. For example, the adjusting device can adjust a position of the first coil in the first direction and simultaneously in the second direction. Furthermore, for example, the adjusting device can first adjust a position of the first coil in the first direction and, after completing the adjustment in the first direction, adjust a position of the first coil in the second direction.

[0052] The adjusting device can be configured to adjust a position of the second coil in the first direction independently of a position of the second coil in the second direction.

[0053] The adjusting device can be configured to adjust a position of the first coil and a position of the second coil independently of one another.

[0054] The adjusting device can be configured to adjust a position of the first coil and / or the second coil in the second direction such that the first connecting web of the first coil has a first edge distance from a first outer edge of the conveyed metallic workpiece of less than or equal to 5 times the extension of an air gap d between the first coil and the second coil, and / or that the second connecting web of the second coil has a second edge distance from the first outer edge of the conveyed metallic workpiece of less than or equal to 5 times the extension of the air gap d between the first coil and the second coil.An induction heating device designed in this way has the advantage that an increased heating homogeneity , in particular an increased heating homogeneity in the width extension of the metallic workpiece , is achieved during the inductive heating of a metallic workpiece .

[0055] In the case of longitudinal field induction, the currents induced by the first coil in the metallic workpiece run in the opposite direction to the currents induced by the second coil. The currents induced by the first coil in the metallic workpiece run on the first side of the metallic workpiece in the direction of the width and join the currents induced by the second coil in the metallic workpiece via the first outer edge of the metallic workpiece. The currents induced by the second coil in the metallic workpiece run on the second side of the metallic workpiece in the opposite direction to the currents induced by the first coil along the width of the metallic workpiece and in turn join the currents induced by the first coil via a second outer edge of the metallic workpiece.As a result, the induced currents of the first and second coils form a closed circuit in a plane orthogonal to the conveying direction of the metallic workpiece. Thus, in particular, no current is induced that runs in the first outer edge and / or the second outer edge in the direction of the conveying direction. This prevents overheating of the outer edges, so that the metallic workpiece experiences increased heating homogeneity across its width during inductive heating.

[0056] The first edge distance is the normal distance in the second direction between the first connecting web of the first coil and the first outer edge of a metallic workpiece located in the induction heating device. The second edge distance is the normal distance in the second direction between the second connecting web of the second coil and the first outer edge of a metallic workpiece located in the induction heating device.

[0057] The air gap d between the first coil and the second coil is the absolute distance between the first coil and the second coil in the first direction. In other words, the extent of the air gap d corresponds to the absolute sum of the first normal distance between the first coil and a metallic workpiece located in the induction heating device, the thickness extent of the metallic workpiece, and the second normal distance between the second coil and the metallic workpiece.

[0058] The air gap d between the first coil and the second coil can have an extension in the first direction depending on the conveyed metallic workpieces. For example, the air gap d between the first coil and the second coil can have an extension in the first direction of < 350 mm, < 300 mm, < 250 mm, < 200 mm, < 150 mm or < 100 mm. The air gap d between the first coil and the second coil can have an extension in the first direction of > 350 mm, > 300 mm, > 250 mm, > 200 mm, > 150 mm or > 100 mm. The air gap d between the first coil and the second coil can have an extension in the first direction of < 350 mm and > 100 mm, < 300 mm and > 150 mm, < 250 mm and > 150 mm or < 250 mm and > 200 mm.

[0059] The adjusting device can be designed to adjust a position of the first coil and / or the second coil in the second direction such that the first connecting web of the first coil has a first edge distance from the first outer edge of the conveyed metallic workpiece of < 4 times, < 3 times, < 2 times or < 1.5 times the extension of the air gap d between the first coil and the second coil, and / or that the second connecting web of the second coil has a second edge distance from the first outer edge of the conveyed metallic workpiece of < 4 times, < 3 times, < 2 times or < 1.5 times the extension of the air gap d between the first coil and the second coil.

[0060] The adjusting device can be designed to adjust a position of the first coil and / or the second coil in the second direction such that the first connecting web of the first coil has a first edge distance from the first outer edge of the conveyed metallic workpiece of > 0 times, > 0.5 times, > 1 time or > 1.5 times the extension of the air gap d between the first coil and the second coil, and / or that the second connecting web of the second coil has a second edge distance from the first outer edge of the conveyed metallic workpiece of > 0 times, > 0.5 times, > 1 time or > 1.5 times the extension of the air gap d between the first coil and the second coil.

[0061] An induction heating device designed in this way has the advantage that during the inductive heating of the metallic workpiece, a high electrical efficiency between the coils and the metallic workpiece and, at the same time, an increased heating homogeneity of the metallic workpiece, in particular an increased heating homogeneity in the width extension of the metallic workpiece, is achieved.

[0062] According to a particularly preferred embodiment, the adjusting device can be configured to adjust a position of the first coil and / or the second coil in the second direction such that the first connecting web of the first coil has a first edge distance from the first outer edge of the conveyed metallic workpiece in a range of > 0.5 times and < 3 times, > 1 time and < 3 times, > 1 time and < 2 times the extent of the air gap d between the first coil and the second coil, and / or that the second connecting web of the second coil has a second edge distance from the first outer edge of the conveyed metallic workpiece in a range of > 0.5 times and < 3 times, > 1 time and < 3 times, > 1 time and < 2 times the extent of the air gap d between the first coil and the second coil.

[0063] An induction heating device designed in this way has the advantage that during the inductive heating of the metallic workpiece, a particularly high electrical efficiency between the coils and the metallic workpiece and, at the same time, a particularly increased heating homogeneity of the metallic workpiece, in particular a particularly increased heating homogeneity in the width extension of the metallic workpiece, is achieved.

[0064] The production line is preferably designed such that the at least one induction heating device is arranged upstream of the first forming device with respect to the conveying direction.

[0065] A production line designed in this way has the advantage that, prior to mechanical treatment by the first forming device, passing metallic workpieces can be heated by the induction heating device to a treatment temperature specific to the mechanical treatment. This improves the desired result of the mechanical treatment, for example, with regard to the microstructure of the metallic workpiece.

[0066] The production line is preferably designed such that the at least one induction heating device is arranged between the first forming device and the second forming device with respect to the conveying direction.

[0067] A production line designed in this way has the advantage that, after a first mechanical treatment by the first forming device and before a second mechanical treatment by the second forming device, passing metallic workpieces can be heated by the induction heating device to a treatment temperature specific for the second mechanical treatment. This improves the desired result of the entire mechanical treatment, for example, with regard to the microstructure of the metallic workpiece.

[0068] The production line can be designed such that the at least one induction heating device is arranged behind the second forming device with respect to the conveying direction.

[0069] A production line designed in this way has the advantage that, after mechanical treatment by the first forming device and the second forming device, passing metallic workpieces are heated to a specific temperature by the induction heating device. This improves a desired result of the entire mechanical treatment, for example, with regard to the microstructure of the metallic workpiece.

[0070] The production line is preferably designed such that the at least one induction heating device is arranged directly adjacent to the first forming device or to the second forming device with respect to the conveying direction. An induction heating device arranged directly adjacent to a forming device with respect to the conveying direction is arranged directly in front of or directly behind the forming device with respect to the conveying direction. In particular, there is no distance or only a negligible distance in the conveying direction between the forming device and the immediately adjacent induction heating device, so that a passing metallic workpiece is conveyed directly from the induction heating device into the forming device or from the forming device into the induction heating device.

[0071] A production line designed in this way has the advantage that, prior to mechanical treatment by the first forming device or the second forming device, passing metallic workpieces can be heated more effectively by the induction heating device to a treatment temperature specific for the mechanical treatment. In particular, the specific treatment temperature can be set more precisely because the metallic workpiece is conveyed directly into the forming device. This further improves the desired result of the mechanical treatment, for example, with regard to the microstructure of the metallic workpiece.

[0072] The production line is preferably designed such that the induction heating device has an inductive heating section in the conveying direction of less than or equal to 10,000 mm.

[0073] The inductive heating section of the induction heating device is the section in the direction of conveyance in which passing metallic workpieces are inductively heated by the induction heating device. The production line is preferably designed such that the production line has at least one temperature conditioning device, and the induction heating device is arranged directly adjacent to the temperature conditioning device with respect to the conveyance direction, or the induction heating device is arranged at a distance from the temperature conditioning device with respect to the conveyance direction.

[0074] An induction heating device arranged directly adjacent to the temperature conditioning device forms, together with the temperature conditioning device, a temperature conditioning group. With a temperature conditioning group, passing metallic workpieces along a conveyor line in the direction of conveyance can be subjected to variable heating profiles. For example, a passing metallic workpiece can be subjected to a heating profile for the continuous, linear heating of the metallic workpiece in a first part of the temperature conditioning group formed by the temperature conditioning device. In a second part of the temperature conditioning group formed by the induction heating device, the metallic workpiece can be subjected to a heating profile for the targeted heating of the outer edges of the metallic workpiece.As a result, a desired result of a mechanical treatment in a subsequent forming device, for example with regard to the microstructure or with regard to the achievable degree of forming of the metallic workpiece, is further improved.

[0075] A temperature conditioning device can be designed as a heating device, for example, as a continuous furnace. A temperature conditioning device can be designed as a cooling device, for example, as an interbelt cooling device, rapid cooling, or as a laminar cooling section.

[0076] The production line is preferably designed such that the at least one temperature conditioning device is arranged in front of the first forming device and / or behind the second forming device and / or between the first forming device and the second forming device with respect to the conveying direction.

[0077] The production line is preferably designed in such a way that the production line has at least one primary forming device for producing metallic workpieces, wherein the primary forming device is arranged upstream of the first forming device with respect to the conveying direction.

[0078] The production line is preferably designed such that the primary forming device is connected to the first forming device by means of a second transport device.

[0079] The second transport device can be designed as a conveyor belt or as a roller conveyor.

[0080] The production line can have one or more further treatment devices. A treatment device can be designed as a joining device, for example as a friction welding device, or as a cutting device, for example as a mechanical cutting device or flame cutting device, or as a surface treatment device, for example as a cleaning device or as a scale washing device, or as a cooling device, for example as an inter-strip cooling device, rapid cooling or as a laminar cooling section. The further treatment device can be arranged upstream of the first forming device and / or downstream of the second forming device and / or between the first forming device and the second forming device with respect to the conveying direction.

[0081] The production line is preferably designed such that the second coil is electrically connected to a second capacitor device.

[0082] The second capacitor device may comprise a single capacitor or a plurality of capacitors. The plurality of capacitors may be connected in parallel.

[0083] The first capacitor device and the second capacitor device can form a structural unit. In other words, the first capacitor device and the second capacitor device can be immovable relative to one another. The structural unit can be formed such that the first capacitor device and the second capacitor device are arranged in a common capacitor cabinet.

[0084] The first coil may be detachably electrically connected to the first capacitor device and / or the second coil may be detachably electrically connected to the first capacitor device and / or to the second capacitor device.

[0085] A production line designed in this way has the advantage that the first coil and / or the second coil can be replaced more quickly in the event of maintenance or repair.

[0086] The production line is preferably designed such that the first coil and / or the second coil is / are mounted so as to be adjustable in position in a second direction.

[0087] A production line designed in this way has the advantage that the first coil and / or the second coil can be moved out of a conveyor section of the production line and / or into a conveyor section of the production line, while metallic workpieces are conveyed in the production line in the conveying direction. This reduces downtimes and therefore production losses on the production line. Furthermore, if required, an additional induction heating device for heating passing metallic workpieces can be positioned in the production line. This allows the flexibility of the production line with regard to the available heating power to be flexibly adapted to the application.

[0088] The production line is preferably designed such that the first capacitor device is mounted so as to be adjustable in position in the second direction.

[0089] A production line designed in this way has the advantage that the first capacitor device can follow a movement of the first coil and / or the second coil in the first direction and / or in the second direction. This allows the electrical connection between the first capacitor device and the first coil and / or the second coil to be shortened. This allows the losses in the electrical power transmission between the first capacitor device and the first coil and / or the second coil to be reduced.

[0090] The second capacitor device is preferably mounted so as to be adjustable in position in the second direction.

[0091] The production line may comprise a capacitor adjustment device for adjusting a position of the first capacitor device and / or the second capacitor device. In particular, the capacitor adjustment device may be designed to adjust a position of the first capacitor device independently of a position of the second capacitor device.

[0092] A production line designed in this way has the advantage that a distance between the first capacitor device and the first coil and / or the second coil and / or a distance between the second capacitor device and the second coil does not reach or exceed a critical maximum value. As a result, the length of an energy transmission device, in particular a cable, between the capacitor devices and the coils can be significantly reduced again, so that the power transmission losses between the capacitor devices and the coils can be further reduced.

[0093] The production line is preferably designed such that the first coil and / or the second coil is / are mounted so as to be positionally adjustable in the first direction relative to the first capacitor device.

[0094] A production line designed in this way has the advantage that the separation of the first capacitor device from the first coil and / or the second coil reduces the mass to be moved for moving the first coil and / or the second coil, particularly since the first coil and / or the second coil would otherwise be rigidly connected to the first capacitor device. As a result, the entire system can act considerably more dynamically with regard to the adjustment mechanism for adjusting the first coil and / or the second coil relative to the metallic workpiece and can therefore respond better to dynamic operating requirements. Furthermore, the reduction in the mass to be moved means that considerably less auxiliary energy is required to move the first coil and / or the second coil.The first coil may be electrically connected to the first capacitor device by means of a flexible energy transmission device and / or the second coil may be electrically connected to the first capacitor device and / or the second capacitor device by means of a flexible energy transmission device.

[0095] The power transmission device may comprise a cable or be designed as such. Alternatively or additionally, the power transmission device may comprise a telescopically extendable busbar or be designed as such.

[0096] The production line is preferably designed such that the first coil and / or the second coil is / are mounted so as to be positionally adjustable in the second direction relative to the first capacitor device.

[0097] A production line designed in this way has the advantage that the entire system, with its adjustment mechanism for adjusting the first coil and / or the second coil relative to the metallic workpiece, can operate significantly more dynamically and thus respond even more effectively to dynamic operating requirements. Furthermore, the further reduction in the mass to be moved means that significantly less auxiliary energy is required to move the first coil and / or the second coil.

[0098] The first coil and / or the second coil is / are preferably mounted so as to be positionally adjustable in the second direction relative to the second capacitor device.

[0099] The production line is preferably designed such that the first coil and the second coil are arranged to heat metallic workpieces conveyed in the conveying direction by means of transverse field induction and / or longitudinal field induction.

[0100] A production line designed in this way has the advantage that the induction heating device is configured both for the uniform heating of continuous metal workpieces by means of longitudinal field induction and for the targeted heating of the outer edges of continuous metal workpieces by means of transverse field induction. This increases the flexibility for the production of metal workpieces of different dimensions.

[0101] The production line is preferably designed such that the induction heating device has at least a third coil, wherein the third coil is designed to heat metallic workpieces conveyed in the conveying direction by means of transverse field induction.

[0102] The third coil can be arranged behind the first coil and / or behind the second coil with respect to the conveying direction.

[0103] The third coil can be arranged at a distance from the first coil and / or the second coil with respect to the conveying direction. Alternatively, the third coil can be arranged directly adjacent to the first coil and / or the second coil with respect to the conveying direction.

[0104] The third coil can be mounted so as to be adjustable in position in the conveying direction, the first direction and / or the second direction.

[0105] The third coil can be mounted so as to be positionally adjustable relative to the first coil and / or the second coil in the conveying direction, the first direction, and / or the second direction. Alternatively, the third coil can be positively coupled to the first coil and / or the second coil with respect to movement in the conveying direction, the first direction, and / or the second direction.

[0106] The adjusting device can be configured to adjust a position of the third coil in the first direction such that a third normal distance of < 100 mm or < 50 mm or < 40 mm or < 30 mm or < 20 mm is established between the third coil and a metallic workpiece located in the induction heating device.

[0107] The adjusting device can be configured to adjust a position of the third coil in the first direction independently of a position of the third coil in the second direction.

[0108] The adjusting device can be configured to adjust a position of the first coil and a position of the second coil and a position of the third coil independently of one another.

[0109] The adjusting device can be configured to adjust a position of the third coil in the second direction such that a third connecting web of the third coil has a third edge distance from a first outer edge of the conveyed metallic workpiece.

[0110] The production line is preferably designed such that a first coil surface of the first coil is designed such that electrical power is passed through the first coil surface at a power density of less than or equal to 500 W / cm 2 is transferable .

[0111] A production line designed in this way has the advantage that the induction heating device can heat the metallic workpieces with increased efficiency. A first coil surface designed in this way reduces both the power loss within the coils and a smaller amount of material is required for their manufacture.

[0112] A first coil surface can be formed by the sides of the first conductor profiles of the first coil facing a first side of the metallic workpiece.

[0113] In other words, the first conductor profiles can have an extension in the conveying direction and an extension in the second direction, so that a first coil surface designed in this way is formed.

[0114] A first coil surface may additionally comprise the side of the first connecting web facing a first side of the metallic workpiece.

[0115] A second coil surface can be formed by the sides of the second conductor profiles of the second coil facing a second side of the metallic workpiece.

[0116] The second coil surface can be designed such that electrical power can be transmitted through the second coil surface at a power density of less than or equal to 500 W / cm 2is transferable. In other words, the second conductor profiles can have an extension in the conveying direction and an extension in the second direction, so that a second coil surface designed in this way is formed.

[0117] A second coil surface may additionally comprise the side of the second connecting web facing a second side of the metallic workpiece.

[0118] In a series of tests to improve a production line, various operating parameters of the production line's induction heating device were examined in more detail in multivariate experiments. The advantages, details, and features of the invention identified in the tests are evident from the further exemplary embodiments explained below.

[0119] Surprisingly, and contrary to the previous assumption that higher penetration depths 5 also lead to a higher electrical efficiency between the coils and the metallic workpiece, it was found that the electrical efficiency between the coils and the metallic workpiece decreases again with a further increase in the penetration depth 5.

[0120] The test series showed that a penetration depth of 5 with a specified maximum penetration depth, or in certain defined areas, is particularly advantageous. The test series produced the results presented in Table 1.

[0121] Tab. 1: Penetration depth 5, electrical efficiency and heating homogeneity in the thickness direction (rating between 0 and 10, where 0 represents the smallest possible value and 10 the largest possible value of the respective property).

[0122] The penetration depth 5 was set in the test series according to the relationship in formula (1). For a metallic workpiece, a temperature-dependent frequency of the alternating currents flowing through the first and second coils can be approximately determined for a specific penetration depth 5.

[0123] By taking a thermographic image of the surface of the metallic workpiece, in particular of the first side and / or the second side of the metallic workpiece, with a thermal imaging camera, the heating homogeneity along the thickness of the metallic workpiece and the electrical efficiency were indirectly determined. The thermal energy generated in the metallic workpiece, and thus the temperature of the metallic workpiece, is determined according to the electric heat law (also called "Joul's first law") and is directly dependent on the electrical current flowing through the metallic workpiece.Starting from the temperature measured on the surface of the metallic workpiece, in particular on the first side and / or the second side of the metallic workpiece, the temperature along the thickness of the metallic workpiece can be approximately calculated via the current density in different layers along the thickness of the metallic workpiece using the relationship described in formula (1). The electrical efficiency between the coils and the metallic workpiece was then determined. The power converted in the metallic workpiece was determined for a defined time period from the thermal energy converted in the metallic workpiece. Finally, the electrical efficiency between the coils and the metallic workpiece could be determined from the electrical power supplied to the first coil and the second coil, which was measured in the same time period.The power loss of the coils could also be determined from the difference between the electrical power provided to the first coil and the second coil and the power converted in the metallic workpiece.

[0124] Alternatively, a direct determination of the temperature distribution in the thickness extension can be carried out in tests using thermocouples embedded in the metallic workpiece.

[0125] If a heating homogeneity of 10 is specified for a parameter combination along the thickness of the metallic workpiece, then the temperature deviation along the thickness of the metallic workpiece is < 1 Kelvin per millimeter. For example, for a metallic workpiece with a thickness of 110 mm, the maximum and minimum temperatures along the thickness of the metallic workpiece are a maximum of 110 Kelvin apart.

[0126] It has also been surprisingly shown that although the electrical efficiency between the coils and the metallic workpiece can be increased by reducing the edge distances, the heating homogeneity along the width of the metallic workpiece decreases again as the edge distance decreases.

[0127] The test series showed that a first edge distance and / or a second edge distance are particularly advantageous in certain defined areas. The test series led to the results presented in Table 2.

[0128] Tab. 2: First edge distance and second edge distance, electrical efficiency and heating homogeneity along the width of the metallic workpiece (each rating between 0 and 10, where 0 represents the smallest possible value and 10 the largest possible value of the respective property).

[0129] In the test series with the results summarized in Table 2, the heating homogeneity along the width of a metallic workpiece was directly determined using a thermographic image taken with a thermal imaging camera of the surface of the metallic workpiece, in particular the first side and / or the second side of the metallic workpiece. The electrical efficiency was determined in a manner analogous to the test series with the results presented in Table 1.

[0130] Further advantages, details and features of the invention will become apparent from the following exemplary embodiments. These show in detail:

[0131] Figure 1: a schematic representation of a production line in a side view according to a first embodiment;

[0132] Figure 2: a schematic representation of a production line in a side view according to a second embodiment; and

[0133] Figure 3: a schematic representation of an induction heating device that can be used in a production line according to the first and second embodiments.

[0134] In the following description, identical reference symbols designate identical components or identical features, so that a description of a component made with reference to one figure also applies to the other figures, thus avoiding repetitive description. Furthermore, individual features described in connection with one embodiment can also be used separately in other embodiments.

[0135] Figure 1 shows a schematic representation of a production line 1 for processing metallic workpieces 2, not shown in Figure 1, which are conveyed in a conveying direction RI. The production line 1 has a first forming device 4 and a second forming device 5 connected to the first forming device 4 by means of a first transport device 60. The production line 1 further has two induction heating devices 3 for heating a metallic workpiece 2, not shown in Figure 1, which is conveyed in the conveying direction RI. An induction heating device 3 is arranged upstream of the first forming device 4 with respect to the conveying direction RI. This induction heating device 3 is arranged directly adjacent to the first forming device 4.The other induction heating device 3 is arranged between the first forming device 4 and the second forming device 5 with respect to the conveying direction RI. This induction heating device 3 is arranged directly adjacent to the second forming device 5.

[0136] The production line 1 has a temperature conditioning device 80 connected to the first forming device 4 by means of a second transport device 70. This temperature conditioning device is designed as a heating device 81. The heating device 81 is arranged upstream of the first forming device 4 with respect to the conveying direction RI.

[0137] The production line 1 has a temperature conditioning device 80 connected to the second forming device 5. This temperature conditioning device 80 is designed as a laminar cooling section 82. The laminar cooling section 82 is arranged downstream of the second forming device 5 with respect to the conveying direction RI.

[0138] The production line 1 further comprises a winding device 110 for winding a metallic workpiece 2, not shown in Figure 1, which is conveyed through the production line 1.

[0139] Figure 2 shows a schematic representation of a production line 1 for the production and processing of metallic workpieces 2, not shown in Figure 2, which are conveyed in a conveying direction RI, in a side view according to a second embodiment. The production line 1 has a primary forming device 6 for the production of metallic workpieces 2, not shown in Figure 2, wherein the primary forming device 6 is arranged upstream of the first forming device 4 with respect to the conveying direction RI. The primary forming device 6 is connected to the first forming device 4 by means of a second transport device 70.

[0140] The production line 1 has a temperature conditioning device 80 and an induction heating device 3 arranged directly adjacent to the temperature conditioning device 80. This temperature conditioning device 80 is designed as a heating device 81. The induction heating device 3 is arranged upstream of the heating device 81 with respect to the conveying direction RI. The heating device 81 and the induction heating device 3 form a first temperature conditioning group 83. The first temperature conditioning group 83 is arranged between the primary forming device 6 and the first forming device 4 with respect to the conveying direction RI. The first temperature conditioning group 83 is arranged directly adjacent to the primary forming device 6 and the first forming device 4.

[0141] The production line 1 has a further temperature conditioning device 80 and a further induction heating device 3 arranged directly adjacent to this temperature conditioning device 80. This temperature conditioning device 80 is designed as a heating device 81. The induction heating device 3 is arranged behind the heating device 81 with respect to the conveying direction RI. The heating device 81 and the induction heating device 3 form a second temperature conditioning group 84. The second temperature conditioning group 84 is arranged between the first forming device 4 and the second forming device 5 with respect to the conveying direction RI. The second temperature conditioning group 84 is arranged directly adjacent to the first forming device 4 and the second forming device 5.

[0142] Alternatively, the heating device 81 can be replaced or supplemented by a cooling device not shown.

[0143] Figure 3 shows a schematic representation of an induction heating device 3 which can be used in a production line 1 according to the first and second embodiments. The induction heating device 3 is shown schematically in a side view. The induction heating device 3 has a first coil 10 which is mounted so as to be positionally adjustable in a first direction R2 such that a first normal distance NI between the first coil 10 and a workpiece 2 located in the induction heating device 3 can be changed. The induction heating device 3 has a second coil 20 which is mounted so as to be positionally adjustable in the first direction R2 such that a second normal distance N2 between the second coil 20 and a workpiece 2 located in the induction heating device 3 can be changed.

[0144] The first coil 10 is electrically connected to a first capacitor device 11, and the second coil 20 is electrically connected to a second capacitor device 21. The first capacitor device 11 and the second capacitor device 21 have a common capacitor cabinet 90 and thus form a structural unit. The first capacitor device 11 and the second capacitor device 21 are mounted so as to be positionally adjustable in a second direction R3. The first capacitor device 11 and the second capacitor device 21 have a common capacitor adjustment device 40.

[0145] The first coil 10 and the second coil 20 are each mounted so as to be positionally adjustable in a first direction R2 and in a second direction R3. The first coil 10 is positionally adjustable relative to the first capacitor device 11 and to the second capacitor device 21 in the first direction R2 and in the second direction R3. The second coil 20 is positionally adjustable relative to the first capacitor device 11 and to the second capacitor device 21 in the first direction R2 and in the second direction R3.

[0146] The first coil 10 is electrically connected to the first capacitor device 11 by means of an energy transmission device 100 designed as a cable 101, and the second coil 20 is electrically connected to the second capacitor device 21 by means of a further energy transmission device 100 designed as a cable 101. The energy transmission devices 100 enable a change in the distance between the first coil 10 and the first and second capacitor devices 11, 21 or between the second coil 20 and the first and second capacitor devices 11, 21 in the first direction R2 and in the second direction R3.

[0147] The induction heating device 1 has an adjusting device 30, wherein the adjusting device 30 has two cylinder devices 31, 32, wherein a first cylinder device 31 is set up to adjust a position of the first coil 10 in the first direction R2, and wherein a second cylinder device 32 is set up to adjust a position of the second coil 20 in the first direction R2. By adjusting a position of the first coil 10 by means of the first cylinder unit 31, the first normal distance NI between the first coil 10 and the metallic workpiece 2 is set in the first direction R2. By adjusting a position of the second coil 20 by means of the second cylinder unit 32, the second normal distance N2 between the second coil 20 and the metallic workpiece 2 is set in the first direction R2.An air gap d that is established between the first coil and the second coil is the sum of the first normal distance NI , the thickness extension t of the metallic workpiece 2 and the second normal distance N2 .

[0148] The adjustment device 30 further comprises two displacement units 33, 34, wherein a first displacement unit 33 is configured to adjust a position of the first coil 10 in the second direction R3 and a second displacement unit 34 is configured to adjust a position of the second coil 20 in the second direction R3.

[0149] The induction heating device 3 has a power supply device 50 electrically connected to the first coil 10 and the second coil 20, wherein the power supply device 50 is designed to supply the first coil 10 and the second coil 20 with alternating current and / or alternating voltage such that a penetration depth 5 of current induced by means of the first coil 10 and / or the second coil 20 into current-carrying layers of the conveyed metallic workpiece 2 is less than or equal to 0.7 times a thickness extension t of the conveyed metallic workpiece 2.

[0150] List of reference symbols

[0151] 1 production line

[0152] 2 Metallic workpiece

[0153] 3 Induction heating device

[0154] 4 First forming device

[0155] 5 Second forming device

[0156] 6 primary forming device

[0157] 10 First coil

[0158] 11 First capacitor device

[0159] 20 Second coil

[0160] 21 Second capacitor device

[0161] 30 Adjustment device

[0162] 31 First cylinder device

[0163] 32 Second cylinder device

[0164] 33 First travel unit

[0165] 34 Second travel unit

[0166] 40 Capacitor adjustment device

[0167] 50 Energy supply facility

[0168] 60 First transport facility

[0169] 70 Second transport device

[0170] 80 Temperature conditioning device

[0171] 81 Heating device

[0172] 82 Laminar cooling section

[0173] 83 First temperature conditioning group

[0174] 84 Second temperature conditioning group

[0175] 90 condenser cabinet

[0176] 100 Energy transmission device 101 Cable 110 Winding device t Thickness extension of a metallic workpiece d Air gap (between the first coil and the second coil) R1 Conveying direction

[0177] R2 First direction R3 Second direction NI First normal distance

[0178] N2 Second normal distance

Claims

Patent claims 1. A production line (1) for producing and / or processing metallic workpieces (2) conveyed in a conveying direction (RI), the production line (1) having the following features: the production line (1) has at least one first forming device (4) and a second forming device (5) connected to the first forming device (4) by means of a first transport device (60); the production line (1) has at least one induction heating device (3) for heating a metallic workpiece (2) conveyed in the conveying direction (RI); the induction heating device (3) having a first coil (10) which is mounted so as to be positionally adjustable in a first direction (R2) such that a first normal distance between the first coil (10) and a workpiece (2) located in the induction heating device (3) can be changed;wherein the induction heating device (3) has a second coil (20) which is mounted so as to be positionally adjustable in the first direction (R2) such that a second normal distance between the second coil (20) and a workpiece (2) located in the induction heating device (3) can be changed; wherein the first coil (10) and / or the second coil (20) is / are electrically connected to a first capacitor device (11); wherein the induction heating device (3) has at least one energy supply device (50) electrically connected to the first coil (10) and / or the second coil (20); and wherein the energy supply device (50) is configured to supply the first coil (10) and the second coil (20); to be supplied with alternating current and / or alternating voltage in such a way that a penetration depth 5 of current induced by means of the first coil (10) and / or the second coil (20) into current-carrying layers of the conveyed metallic workpiece (2) is less than or equal to 0.7 times a thickness extension (t) of the conveyed metallic workpiece (2).

2. Production line (1) according to claim 1, characterized in that the at least one induction heating device (3) is arranged upstream of the first forming device (4) with respect to the conveying direction (RI).

3. Production line (1) according to claim 1, characterized in that the at least one induction heating device (3) is arranged between the first forming device (4) and the second forming device (5) with respect to the conveying direction (RI).

4. Production line (1) according to one of the preceding claims, characterized in that the at least one induction heating device (3) is arranged directly adjacent to the first forming device (4) or to the second forming device (5) with respect to the conveying direction (RI).

5. Production line (1) according to one of the preceding claims, characterized in that the induction heating device (3) has an inductive heating section in the conveying direction (RI) of less than or equal to 10,000 mm.

6. Production line (1) according to one of the preceding claims, characterized by the following features: the production line (1) has at least one temperature conditioning device (80); the induction heating device (3) is arranged directly adjacent to the temperature conditioning device (80) with respect to the conveying direction (RI); or the induction heating device (3) is arranged at a distance from the temperature conditioning device (80) with respect to the conveying direction (RI).

7. Production line (1) according to claim 6, characterized in that the at least one temperature conditioning device (80) is arranged upstream of the first forming device (4) and / or downstream of the second forming device (5) and / or between the first forming device (4) and the second forming device (5) with respect to the conveying direction (RI).

8. Production line (1) according to one of the preceding claims, characterized in that the production line (1) has at least one primary forming device (6) for producing metallic workpieces (2), wherein the primary forming device (6) is arranged upstream of the first forming device (4) with respect to the conveying direction (RI).

9. Production line (1) according to claim 8, characterized in that the primary forming device (6) is connected to the first forming device (4) by means of a second transport device (70).

10. Production line (1) according to one of the preceding claims, characterized in that the second coil (20) is electrically connected to a second capacitor device (21).

11. Production line (1) according to one of the preceding claims, characterized in that the first coil (10) and / or the second coil (20) is / are mounted so as to be positionally adjustable in a second direction (R3).

12. Production line (1) according to one of the preceding claims, characterized in that the first capacitor device (11) is mounted so as to be positionally adjustable in the second direction (R3).

13. Production line (1) according to one of the preceding claims, characterized in that the first coil (10) and / or the second coil (20) is / are mounted so as to be positionally adjustable in the first direction (R2) relative to the first capacitor device (11).

14. Production line (1) according to one of the preceding claims, characterized in that the first coil (10) and / or the second coil (20) is / are mounted so as to be positionally adjustable in the second direction (R3) relative to the first capacitor device (11).

15. Production line (1) according to one of the preceding claims, characterized in that the first coil (10) and the second coil (20) are arranged for heating metallic workpieces (2) conveyed in the conveying direction (RI) by means of transverse field induction and / or longitudinal field induction.

16. Production line (1) according to one of the preceding claims, characterized in that the induction heating device (3) has at least a third coil, wherein the third coil is designed to heat metallic workpieces (2) conveyed in the conveying direction (RI) by means of transverse field induction.

17. Production line (1) according to one of the preceding claims, characterized in that a first coil surface of the first coil (10) is designed such that electrical power through the first coil area at a power density of less than or equal to 500 W / cm 2 is transferable .

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