Method for pretreating a metal strip and / or for cold-rolling the metal strip, preheating device, and cold-rolling mill or system for pretreating a metal strip by means of a preheating device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SMS GROUP GMBH
- Filing Date
- 2026-01-14
- Publication Date
- 2026-07-30
Smart Images
Figure EP2026050760_30072026_PF_FP_ABST
Abstract
Description
[0001] Method for pretreating a metal strip and / or for cold rolling the metal strip, preheating device and cold rolling mill or plant for pretreating a metal strip with a preheating device
[0002] The invention relates to a method for pretreating a metal strip and / or for cold rolling the metal strip in at least one rolling stand with at least one rolling pass, comprising heating the metal strip to a predetermined or predefined strip temperature below a recrystallization temperature of the metal strip prior to the pretreatment and / or the cold rolling, wherein the heating of the metal strip takes place in a coiled state prior to the pretreatment and / or prior to an unwinding process preceding the at least one rolling pass.
[0003] The invention further relates to a preheating device, in particular for use with the method according to the invention.
[0004] The invention further relates to a cold rolling mill comprising at least one unwinding device for at least one metal strip wound into a coil, preferably in the form of a steel strip, at least one rolling stand for carrying out at least one rolling pass for rolling the metal strip to a predetermined target thickness, and means for winding the metal strip rolled to the target thickness.
[0005] Finally, the invention relates to a system for the pretreatment of a metal strip comprising means for pickling and annealing the metal strip in the form of an annealing-pickling line or a pickling-annealing line.
[0006] It is generally known in the art to heat steel strips before the cold rolling process. Heating is particularly necessary in the production of electrical steel sheets with high silicon content, due to the high silicon content.
[0007] Page 1: The brittleness of these electrical steel sheets leads to frequent strip cracks during cold forming.
[0008] EP 3791 971 A1 describes a method for cold rolling a rolled material in which the heating of the rolled material to a run-in temperature for the first rolling stand is provided before the first rolling pass.
[0009] The rolling mill according to EP 3791 971 A1 includes a heating device which is arranged in line with and immediately in front of the first rolling stand.
[0010] Heating the metal strip during unwinding, immediately before the first cold rolling pass, is limited to the time it takes for the strip section to pass through, due to the spatially confined heating of the strip during the unwinding process. The strip cross-section, material density, specific heat capacity, temperature difference, and throughput time determine the heating capacity required. This means either designing the heating capacity to meet the maximum power demand or, if the installed heating capacity is limited, limiting the unwinding speed, which negatively impacts the productivity of the cold rolling mill.
[0011] Furthermore, it is known in the prior art to preheat coils before unwinding using a heated water bath or emulsion bath, or using a gas-heated oven. This method has the disadvantage that the heating must take place from the outer surfaces of the coil inwards. This means either a long heating time in the bath until the strip temperature is uniform throughout the coil, or, if the coil is removed from the bath too early, an uneven strip temperature both across the strip width and along the strip length.
[0012] Page 2. Continuous heating, particularly of the unwound metal strip, especially so-called inline heating, i.e., in a process path or process line with the rolling process, is limited in time to the throughput time of the strip section through the spatially limited strip heating during the unwinding time of the first pass. In contrast, a larger time buffer for heating and equalization can be provided with so-called offline heating.
[0013] Heating coils using a water bath or emulsion bath, a common method for offline heating, has the disadvantage of requiring a relatively high level of handling effort, as a crane is needed to lower the coils into and remove them from an open bath. Furthermore, hot residual liquid that leaks out between the layers of the coil after removal from the heating bath poses a safety risk and can increase the risk of slipping on the floor. Finally, the maximum preheating temperature is limited to below the boiling point of the heat transfer medium.
[0014] The invention is based on the objective of providing a method of the type mentioned above with which it is possible to effectively heat the coil to a relatively high temperature in a homogeneous manner offline.
[0015] The problem is solved by providing a method with the features of claim 1. Advantageous embodiments of the method according to the invention are set out in the dependent claims.
[0016] A first aspect of the invention relates to a method for pretreating a metal strip and / or for cold rolling the metal strip in at least one rolling stand with at least one rolling pass, comprising the heating of the strip prior to the pretreatment and / or cold rolling.
[0017] Page 3 Metal strips to a predetermined or predefined strip temperature below a recrystallization temperature of the metal strip, wherein the heating of the metal strip takes place in a coiled state before pretreatment and / or before an unwinding process preceding at least one rolling pass.
[0018] The method according to the invention is characterized in particular by the fact that heating is carried out by applying heat to the end faces of the coil by means of at least one preheating device, and that the heating and / or at least an initial waiting period immediately after at least one initial heating application, during which no heat is introduced into the coil, or between two heating applications, is carried out by controlling or regulating the at least one preheating device for as long and / or as often as necessary until the coil has reached the predetermined strip temperature over its entire width and length. With the method according to the invention, it cannot be ruled out that the predetermined strip temperature may be exceeded locally for a short period of time. Therefore, the term "predetermined strip temperature" should be understood to mean that this can also be a temperature range or target range.
[0019] The method according to the invention can comprise various variants of the processing of the metal strip. A first variant of the method comprises heating the coil with the preheating device described above prior to a pretreatment of the metal strip, for example by annealing and pickling or by pickling and annealing followed immediately by a cold rolling process.
[0020] In another variant of the process, the heating of the coil step can be directly preceding the cold rolling.
[0021] Page 4 In a third variant of the method according to the invention, it may finally be provided not to carry out the cold rolling process, but rather to complete the method by winding up a pretreated metal strip.
[0022] The method according to the invention has the particular advantage that the strip can be heated homogeneously across its entire width and length. This also reduces the risk of strip cracking during any subsequent cold rolling process.
[0023] The heating of the metal strip need not be performed immediately before pretreatment or before unwinding for rolling; rather, according to the invention, the heating process step can be carried out offline, either campaign-wise or batch-wise. "Offline" in the context of the present invention means that the heating can take place outside of a process line of the cold rolling mill and / or be decoupled in time from a process step such as pickling, annealing, and / or rolling.
[0024] The heating process can be followed by a heated intermediate storage area for heated coils, from which the heated coils can be transferred to a cold rolling mill as needed.
[0025] The method according to the invention can be carried out using, for example, a cold rolling mill that has several process paths or with which several process paths can be implemented. Several process paths can be provided, for example, by designing the cold rolling mill to process both unheated and preheated coils.
[0026] Furthermore, the cold rolling mill can be designed for operation in one direction as well as for reversing operation and can include any number of rolling stands.
[0027] Page 5 The method according to the invention comprises, in one variant, continuous heating of the coil at its end face.
[0028] Alternatively, the heating of the coil ends can be intermittent, alternating between both ends, or intermittent from both ends. Intermittent means that heat is introduced into the coil at certain times, with each heating phase followed by a waiting period during which no heating is applied. This also includes a variant where only a single heating phase and a single waiting period are used before the heated coil is unwound and subjected to a further process step, or before the heated coil is transferred to intermediate storage.
[0029] Intermittent alternating heating means that one end and the opposite end of the coil are heated alternately. This can be useful, for example, in inductive heating to reduce the load on the electrical grid.
[0030] Intermittent heating from both ends of the coil means that one or more heating phases are provided simultaneously at both ends of the coil, but at different times.
[0031] Preferably, the heat application is regulated according to intensity and duration so that an upper limit temperature of the winding edges of the metal strip is not exceeded.
[0032] In the method according to the invention, the metal strip is a steel strip, preferably a steel strip for use as electrical steel with a high silicon content.
[0033] Page 6. The method according to the invention comprises, as described above, the rolling of surface-treated, for example, pickled and unpickled steel strips, or the pretreatment of untreated, scaled strips before pickling and annealing or annealing and pickling. The upper limit temperature of the metal strip selected according to the invention depends, among other things, on whether the wound metal strip is to undergo pickling or another process for removing scale and / or an oxide layer.
[0034] One variant of the method is characterized by the fact that the temperature of the coil ends is continuously measured or monitored during preheating to ensure that a permissible upper limit temperature of the metal strip is not exceeded, for example by using at least one pyrometer or a computational model based in particular on physical input variables.
[0035] In principle, the invention allows for the introduction of heat into the coil using any radiant heating source. However, it is particularly preferred that the coil be preheated inductively. Induction coils have the advantage over other heating methods that they are relatively easy to control and regulate. This allows, in particular, the power drawn from the electrical network to be controlled, thus preventing peak loads in the electrical network of the factory or cold rolling mill.
[0036] In state-of-the-art online operation, the heating unit must be designed for the mass flow of the strip in the processing line. If strip preheating is not required, the heating unit is switched off. This results in an operating mode with intermittently very high power consumption and intermittent idle operation of the heating unit. This online operating mode can lead to costly peak loads in the electrical network, especially if the heating unit is electrically operated.
[0037] Page 7: The compensation times or waiting times after the actual heating can last several hours; this could also be used to specifically utilize the time when the network is not
[0038] is burdened.
[0039] If the heating device is operated offline, as preferably provided according to the invention, a larger proportion of the production time can be used for strip preheating. As a result, this leads to a smaller heating device and reduced peak loads in the electrical network.
[0040] Advantageously, a preferably calculated core temperature of the coil is used as a reference to ensure that the coil has reached at least the specified or lower strip temperature across its entire width.
[0041] A core temperature within the meaning of the invention is understood to be the temperature approximately in the middle of the winding height of the coil with respect to the first winding layer and approximately in the middle of the strip with respect to its width.
[0042] Advantageously, the lower strip temperature is chosen to be between 60 °C and 200 °C, preferably between 80 °C and 200 °C, more preferably between 120 °C and 200 °C and particularly preferably between 140 °C and 200 °C.
[0043] The core temperature of the coil is calculated, preferably by an automation system, taking into account the heat input into the coil, the mass of the coil, the thermophysical properties of the metal strip, and a temperature preferably measured at the ends of the coil, and is supplied to a control and regulating device of a preheating device.
[0044] Page 8. The method can, for example, include placing an unheated coil in a preheating station in which an alternating magnetic field is axially coupled into the end faces of the coil by means of at least two induction fields. Surprisingly, it has been found that, in particular, the end-face coupling of an alternating magnetic field into a wound coil results in a particularly uniform and homogeneous heating of the coil across its entire width. By appropriately controlling at least one induction field, preferably several induction fields, or at least one induction coil forming an induction field, maximum heat penetration of the coil can be achieved with a relatively low current requirement from the electrical grid through favorable intermittent control of at least one induction coil.
[0045] In a particularly favorable and advantageous variant of the method according to the invention, it is provided that the size of at least one induction field is adapted to the outer diameter of the coils to be heated.
[0046] The method according to the invention further preferably includes varying the axial distance between the induction fields relative to the coil in order to achieve adaptation to different coil widths.
[0047] In a suitable embodiment of the method according to the invention, an upper limit temperature of less than or equal to 450 °C is selected, particularly for the winding edges of the strip. This is especially advantageous when unpickled metal strip is pretreated in an annealing-pickling line or pickling-annealing line.
[0048] If the metal strip is to be cold-rolled in an immediately subsequent process step, it is advantageous to specify a temperature as the upper limit temperature.
[0049] Page 9: The temperature is chosen to be less than 250 °C in order to avoid the formation of disturbing surface discolorations by oxide layers.
[0050] Within the scope of the invention, alternating one-sided heating of the coil using a single induction coil or a single induction field can be provided. For this purpose, it can be provided that, after heating one side, the coil is rotated 180 degrees in the preheating stand, with the preheating stand, or with a coil support.
[0051] One variant of the method according to the invention is characterized by the use of at least two spiral induction coils arranged on either side of a coil support in the preheating unit, preferably at a variable distance from each other. The coil support can be, for example, at least one support saddle on which a coil can be placed lying on its circumferential surface. The distance between the induction coils can be variable to accommodate coils of different widths.
[0052] Furthermore, it is advantageous if the size of the induction fields or the alternating magnetic fields generated by the induction coils are adapted to the diameter of the coil to be heated. For this purpose, for example, the size of the induction fields can be adjusted by means of variable taps on the induction coils.
[0053] According to an advantageous embodiment of the method according to the invention, the heat input to be introduced into the coil and / or the duration and / or the number of heat applications and / or at least a waiting period during which no heat input is introduced into the coil are calculated by an automation system. This calculation can be performed taking into account the mass of the coil, the thermophysical properties of the material, the width and diameter of the coil, and the measured and monitored temperature of the coil winding edges, for example, using the following methods:
[0054] Page 10: This will be carried out using a computer-implemented model-based algorithm.
[0055] The problem underlying the invention is further solved by providing a preheating device with the features of claim 16.
[0056] The preheating device according to the invention is preferably designed and configured for use with the method described above.
[0057] A preheating device according to the invention comprises at least one preheating stand with at least one coil support for a wound coil and at least one induction field with at least one induction coil, preferably with two induction fields arranged at a distance from each other, each with at least one induction coil, which are designed to couple an alternating magnetic field into an end face of the wound coil.
[0058] Within the scope of the invention, the device can comprise a single induction field with one or more induction coils arranged on one side. The induction field can be adjustable with respect to the coil support. The coil support can be rotatable about a vertical axis so that the end faces of the coil can be heated alternately.
[0059] If two induction fields arranged at a distance from each other, each with at least one induction coil, are provided, it is advantageous to vary the distance between the induction fields according to the width of the coil.
[0060] Furthermore, according to the invention, the magnitude of the alternating magnetic fields to be introduced into the coil can be varied according to the diameter of the coil. For this purpose, the induction coils can, for example, each have variable taps.
[0061] Page 11The induction coils can, for example, each be spiral-shaped and extend in the preheating device in a plane that is aligned parallel to the plane of the winding edge of the coil.
[0062] The problem underlying the invention is ultimately solved by providing a cold rolling mill which is specifically designed to carry out the method described above.
[0063] The cold rolling mill according to the invention comprises at least one unwinding device for at least one metal strip wound into a coil, preferably in the form of a steel strip, at least one rolling stand for carrying out at least one rolling pass for rolling the metal strip to a predetermined target thickness, means for winding the metal strip rolled to the target thickness, and at least one preheating device or a preheating stand with a preheating device for preheating the coil in a preheating stand upstream of the unwinding process, wherein the preheating device is configured and designed to heat the coil to a predetermined core temperature by applying heat to the end face across its entire width.
[0064] The preheating device or preheating stand does not need to be directly upstream of the unwinding device, for example in the form of a reel, and a rolling stand, nor do they need to be arranged in the same process line. The preheating device or preheating stand can be located offline, allowing coils to be preheated campaign by campaign or batch by batch. The cold rolling mill can, for example, include an intermediate storage area in the form of an insulated box or similar structure, from which the previously heated coils are transferred to the cold rolling mill.
[0065] The invention is explained below with reference to and with the aid of the accompanying drawings, which show various embodiments of the
[0066] Page 12 illustrates the inventive operating process and the inventive cold rolling process.
[0067] They show:
[0068] Figure 1 shows a schematic representation of a device for the pretreatment of steel strips as a first embodiment comprising an annealing pickling line,
[0069] Figure 2 shows a schematic representation of a second embodiment of the invention comprising a pickling and annealing line.
[0070] Figure 3 shows a schematic representation of a third embodiment of the invention, comprising a tandem cold rolling mill designed as a cold rolling mill,
[0071] Figure 4 shows a schematic representation of a fourth embodiment according to the invention comprising a reversing cold rolling mill designed as a cold rolling mill,
[0072] Figure 5 shows a side view of a preheating stand according to the invention and
[0073] Figure 6 shows a top view of the preheating stand shown in Figure 5.
[0074] The inventive method is explained below with reference to various plant configurations. All plant configurations according to the invention have in common that a steel strip wound into a coil 1 is heated by applying heat to the end faces of the coil 1 using at least one preheating device 2 prior to pretreatment and / or a
[0075] Page 13: Cold rolling of the steel strip is provided. The method according to the invention can comprise only a pretreatment of the steel strip and storage or other use of the correspondingly pretreated steel strip, or only a cold rolling of the steel strip. The method according to the invention can also comprise a pretreatment and a cold rolling process downstream of the pretreatment.
[0076] The embodiments described below are therefore to be understood as meaning that a cold rolling mill, either in the form of a tandem cold rolling mill 5 or in the form of a reversing cold rolling mill 6, can be connected downstream of the annealing pickling line 3 and pickling annealing line 4 shown in Figures 1 and 2.
[0077] Therefore, in the following, reference is first made to the preheating stand 7 shown in Figures 5 and 6, comprising the preheating device 2 according to the invention.
[0078] The preheating station 7 according to the invention comprises a storage saddle 8 for a wound coil 1, which is formed by two bearing blocks 9, each arranged on a slide 10. A spirally shaped induction coil 11 is arranged on each of the movable slides 10, extending perpendicular to a displacement direction of the slide 10 and parallel to an end face 12 of the coil 1 placed between the induction coils 11 on the bearing blocks 9.
[0079] By relocating the slides 10 on unspecified means for guiding the slides 10, an axial distance between the induction coils 11 and the bearing blocks 9 can be adjusted and thus adapted to different coil widths. The induction coils 11 can be supplied with electric current via a voltage source and are designed such that they each couple an alternating magnetic field into the end faces or end surfaces 12 of the coil 1. The diameter of the respective generated
[0080] Page 14: The magnetic alternating field can be varied via variable taps on the induction coils 11. A coil 1 to be heated in the preheating station 7 can, for example, have an inner diameter of 500 mm and an outer diameter of up to 1950 mm. The coil 1 can, for example, have a width of approximately 3000 mm.
[0081] As described at the beginning, the coil 1 is to be heated across its entire width. To prevent overheating of the end faces of the coil 1, the induction coils 11 can be operated intermittently, with heating pauses between individual activations or heat inputs by the induction coils 11, during which no heat is introduced into the coil 1.
[0082] The heat input into the coil 1 is regulated by a control device (not shown). The outside temperature at the end faces 12 is continuously measured and monitored.
[0083] The following section discusses the various plant configurations shown in Figures 1 to 4, with which different variants of the method according to the invention can be carried out.
[0084] Figure 1 shows an annealing pickling line 3, upstream of which is a preheating station 7 according to Figures 5 and 6 with a preheating device 2 according to the invention. In the preheating station 7, the coil 1 is preheated over its entire width by means of the preheating device 2 described above in the manner according to the invention and from there passes into equalization and intermediate storage areas, hereinafter referred to as intermediate storage 13. The intermediate storage 13 can, for example, be designed as an insulated box or the like, in which both temperature equalization over the entire thickness and width of the coil 1 and storage of a plurality of coils 1 can be provided. The coil 1 is unwound via a reel 14.
[0085] Page 15 is unwound. In an infeed shear 15, the leading strip edge is prepared for welding in the downstream welding machine 16. The strip is then trimmed at the edges in the trimming shear 17 and enters an annealing furnace 19 via an infeed belt accumulator 18. The annealing furnace 19 comprises an annealing section 19 A and a cooling section 19 B immediately downstream. Annealing and subsequent cooling take place in an oxygen-containing atmosphere. After descaling in a downstream descaler 20, the strip is freed of scale and then treated in the pickling bath 21. Through an outfeed belt accumulator 22, the strip is fed to an outfeed shear 23, cut there, and wound into a pre-treated coil 1 by a reel 24. A cold rolling line can be connected directly to the annealing pickling line 3 or behind an intermediate storage area, which is not provided for in the process variant according to Figure 1, but is also not excluded.
[0086] Figure 2 shows a pickling and annealing line 4, where, in the embodiment according to Figure 2, identical components are provided with the same reference numerals. For the sake of simplicity, only the differences between the second embodiment and the first will be discussed below. The essential difference between these two embodiments is that the strip first passes through the pickling solution 21 and is then completely annealed under a protective gas atmosphere in an annealing furnace 25 with an annealing section 25A and a cooling section 25B. Naturally, subsequent descaling is not necessary.
[0087] The embodiment shown in Figure 3 comprises, like the plant configuration described above, a preheating station 7 for preheating the coils 1 in the manner described above, and optionally an intermediate storage area 13. The preheated coils are first unwound from a reel 14, cut, welded, and trimmed in a similar manner to the pretreatment of the steel strip. Then
[0088] Page 16: The steel strip is fed via the inlet belt storage 18 to a multitude of tandem rolling stands 27 and rolled to a target thickness, cut, and rewound in the tandem cold rolling mill 5. A continuous induction heating unit 26 is provided before the first rolling pass to bring the steel strip to the intended rolling temperature (below the control crystallization temperature of the metal strip) if the strip has lost too much heat on its way there.
[0089] The plant configuration shown schematically in Figure 4 provides for the cold rolling of the steel strip, which is first preheated and then unwound, in a reversing cold rolling mill 6. This differs essentially in that a reversing reel 28 is connected upstream and downstream of each reversing rolling stand 29.
[0090] Page 17 Reference Mark List
[0091] 1 Coil
[0092] 2 Preheating device
[0093] 3 annealing pickling line
[0094] 4 Pickling annealing line
[0095] 5 Tandem cold rolling mill 6 Reversing cold rolling mill 7 Preheating stand
[0096] 8 storage saddles
[0097] 9 bearing blocks
[0098] 10 sleds
[0099] 11 induction coils
[0100] 12 end faces
[0101] 13 interim storage facilities
[0102] 14 reels
[0103] 15 Enema scissors
[0104] 16 Welding machine 17 Trimming shears
[0105] 18 Infeed belt storage 19 Annealing furnace
[0106] 19 A Glowing part
[0107] 19 B Refrigerator compartment
[0108] 20 descalers
[0109] 21 stain
[0110] 22 Discharge belt storage 23 Discharge shear
[0111] 24 reel
[0112] 25 annealing furnace
[0113] 25A glow plug
[0114] 25B Refrigerator compartment
[0115] Page 18 Continuous induction heating system Tandem rolling stands Reversing reel
[0116] Reversing rolling mill
[0117] Page 19
Claims
Patent claims 1. A method for pretreating a metal strip and / or for cold rolling the metal strip in at least one rolling stand (27, 29) with at least one rolling pass, comprising heating the metal strip to a predetermined or predefined strip temperature below a recrystallization temperature of the metal strip prior to the pretreatment and / or cold rolling, wherein the heating of the metal strip takes place in a coiled state (1) before the pretreatment and / or before an unwinding process preceding the at least one rolling pass, characterized in that the heating is carried out by applying heat to the ends of the coil (1) by means of at least one preheating device (2) and that the heat application and / or at least a first waiting period immediately after at least a first heat application, during which no heat is introduced into the coil (1),or between two heating applications, the preheating process is carried out by controlling or regulating the at least one preheating device (2) for so long and / or so often until the coil (1) has reached at least the specified lower strip temperature across its entire width.
2. Method according to claim 1, characterized in that the heat application is regulated according to intensity and duration such that an upper limit temperature of the winding edges of the metal strip is not exceeded.
3. Method according to one of claims 1 or 2, characterized in that the temperature of the end faces of the coil (1) is continuously measured and / or calculated during preheating. Page 204. Method according to one of claims 1 to 3, characterized in that the preheating of the coil (1) is carried out inductively.
5. Method according to one of claims 1 to 4, characterized in that a core temperature of the coil (1) is calculated taking into account the heat power introduced into the coil (1), the mass of the coil (1), the thermophysical material properties of the metal strip and taking into account a temperature preferably measured at the end faces of the coil (1).
6. Method according to one of claims 1 to 5, comprising placing a non-preheated coil (1) in a preheating stand (7) in which a magnetic alternating field is coupled axially into at least one end face of the coil (1) by means of at least one induction field, preferably by means of at least two induction fields.
7. Method according to one of claims 1 to 6, characterized in that the size of the at least one induction field is adapted to the diameter of the coil (1) to be heated.
8. Method according to one of claims 2 to 7, characterized in that the upper limit temperature is selected to be less than or equal to 450 °C.
9. Method according to claim 8, characterized in that the metal strip is rolled without pretreatment.
10. Method according to one of claims 2 to 7, characterized in that the upper limit temperature is selected to be less than 250 °C. Page 2111. Method according to claim 10, characterized in that the metal strip is pretreated after preheating, preferably by pickling and / or annealing.
12. Method according to one of claims 1 to 11, characterized in that the lower strip temperature is selected to be between 60 °C and 200 °C, preferably between 80 °C and 200 °C, more preferably between 120 °C and 200 °C and particularly preferably between 140 °C and 200 °C.
13. Method according to one of claims 1 to 12, characterized by the use of at least two spiral induction coils (11) which are arranged in the preheating station (7) with a preferably variable distance to each other on both sides of a coil support, preferably in the form of a support saddle (8).
14. Method according to one of claims 6 to 13, characterized by an adjustment of the size of the induction fields by means of variable taps on the induction coils (11).
15. Method according to one of claims 1 to 14, characterized in that the heat power to be introduced into the coil (1) and / or the duration and / or the number of heat effects and / or at least a waiting time are calculated and specified by an automation system.
16. Preheating device, in particular for use with the method according to one of claims 1 to 15, comprising at least one preheating station (7) with a coil support for a wound coil (1) and at least two induction coils arranged at a distance from each other. Page 22(11), which are designed to couple an alternating electromagnetic field into one end face of the wound coil (1).
17. Preheating device according to claim 16, characterized in that the distance between the induction coils (11) is variable according to the width of the coil (1).
18. Preheating device according to one of claims 16 or 17, characterized in that the size of the alternating electromagnetic fields to be introduced into the coil (1) is variable according to the diameter of the coil (1).
19. Cold rolling mill comprising at least one unwinding device for at least one metal strip wound into a coil (1), preferably in the form of a steel strip, at least one rolling stand (27, 29) for carrying out at least one rolling pass for rolling the metal strip to a predetermined target thickness, means for winding the metal strip rolled to the target thickness, and at least one preheating device (2) for preheating the coil (1) in a preheating stand (7) upstream of the unwinding device, wherein the preheating device (2) is configured and designed to heat the coil (1) to a predetermined core temperature by applying heat to the end face across its entire width.
20. Cold rolling mill according to claim 19 comprising at least one preheating device (2) having the features of one of claims 17 or 18.
21. Plant for the pretreatment of a metal strip comprising means for pickling and annealing the metal strip in the form of an annealing-pickling line (3) or a pickling-annealing line (4) and at least one preheating station (7) upstream of the annealing-pickling line (3) or the pickling-annealing line (4) with at least Page 23 of a preheating device (2) wherein the preheating device (2) is designed and configured to heat the coil (1) to a predetermined core temperature by applying heat to the end face across its entire width.
22. System according to claim 21, comprising at least one preheating device (2) having the features of any one of claims 16 to 18. Page 24