WO2019228985A1

WO2019228985A1 - Method for avoiding strips sticking on flexibly rolled strip material

Info

Publication number: WO2019228985A1
Application number: PCT/EP2019/063658
Authority: WO
Inventors: Jürgen Butzkamm; Alexander EICK; Christian Reuter; Sven SCHARZ
Original assignee: Muhr Und Bender Kg
Priority date: 2018-05-30
Filing date: 2019-05-27
Publication date: 2019-12-05
Also published as: EP3575008B1; EP3575008A1; CN112203783A

Abstract

The invention relates to a method for avoiding strips sticking on flexibly rolled metal strip, wherein after flexible rolling (S10), a metal strip (2) is wound to form a coil (3) and is subject to thermal treatment (S40), wherein before thermal treatment (S40), the flexibly rolled metal strip (2) is wound at least in an annular section (13) of the coil (3) with a winding tension (F13) of less than 40 N/mm² in relation to a cross-section area (A) of the metal strip (2).

Description

Method for avoiding tape adhesives on flexibly rolled strip material

description

The invention relates to a method for avoiding tape adhesives, in particular flexibly rolled metal strip.

From DE 197 50 780 A1 discloses a working method for applying a defined surface roughness on a metal strip is known to avoid tape adhesive during a nachgela sieve annealing process. EP 0 760 396 A1 discloses a method for avoiding the annealing of cold-rolled strips, in which the strip surface is oxidized above 600 ° C. during the holding time.

From WO 03/000438 A1 a method and a belt treatment plant for avoiding tape adhesives during reel is known, in which the axial pressure over the fire width on the coiler mandrel is measured in order to control the control values of the strip rolling mill with the measured values.

The above methods each relate to the treatment of constant thickness strip material over the length. However, they are not sufficiently suitable to avoid the emergence of tape adhesives on flexibly rolled strip. Flexibly rolled strip material has a variable thickness over the length, which, when wound up or wound up, results in a coil structure with a variable radius over the circumference and thus possibly also variable stress properties over the circumference. The present invention is therefore based on the object, vorzu a method with which the occurrence of tape adhesives, especially of flexible ge rolled metal strip, can be effectively reduced or avoided. One solution lies in a method for avoiding tape adhesives on flexibly ge rolled metal strip, wherein the metal strip is wound into a coil after the flexible rolling and subjected to a heat treatment, wherein the flexible rolled metal strip before the heat treatment at least in a particular ra dial outside Part of the coil is wound with a take-up of less than 40 N / mm ² based on a cross-sectional area of the metal strip.

By winding the strip material with relatively low tensile forces of less than 40 N / mm ² (= 40 MPa), the coiled coil acting in the circumferential direction of the stresses are relatively low, so that the mutually superimposed band surfaces are pressed together less strongly , As part of the heat treatment thus leads to lower adhesion effects, so that tape adhesive can be avoided when rewinding the coil Abwi. Preferably, at least one radially outer portion of the coil is wound with a take-up tension of less than 40 N / mm ² with respect to a cross-sectional area of the metal strip. This includes in the context of the present disclosure, in particular, that at least one ring section in within an outer third of the wound coil, or at least an outer third, in particular at least one outer half, preferably the entire coil are wound with less than 40 N / mm ² , According to a possible embodiment of the take-up is adjusted depending on an average thickness of the metal strip over the length. The average thickness of the band or band sections can in principle be arbitrary. For example, the mean value can be determined based on the geo metric mean value of the thickness profile over the length of the strip material or one or more band sections according to a first possibility. Alternatively, the average value can also be determined as the absolute average value between a maximum thickness and a smallest thickness of a band section or a total length of the band. For the calculation of the winding tension, the mean value of the belt thickness can be determined with one of the Strip hardening corresponding code multiplied. Furthermore, from the mean value of the strip thickness multiplied by the strip width, an average cross-sectional area can be calculated, which can be used to determine the winding over the length of the strip material.

In flexible rolling, strip material having a substantially uniform sheet thickness is rolled over the length by changing the roll gap during the process into strip material having a particularly variable sheet thickness. The sections of different thickness produced by the flexible rolling extend transversely to the longitudinal direction or to the rolling direction of the strip material. In this case, the flexible rolling can be performed in example so that a first portion has a thinner first Di bridge, as a thicker second section, wherein the ratio of first thickness to second thickness less than 0.8, in particular less than 0.7, in particular smaller Can be 0.6. The absolute thickness of the strip material may, for example, be between 0.7 mm in thin areas and 4.0 mm in thick areas.

The strip material can be wound up immediately after the flexible rolling, that is, from the coiler of the rolling mill in the manner mentioned with low strip tension. Alternatively, it is also possible for the strip material to be initially wound up with higher strip tension after flexible rolling, and then wound up in the course of a separate wrapping process with the said low tensile forces, before it is subsequently annealed. In any case, it is important that the small tractions of less than 40 N / mm ² with respect to the cross-sectional area are applied when the coil is transferred to the kiln.

The strip material may in principle be made of any metal or metal alloys, for example of iron-containing metals, in particular steel, or light metals, in particular aluminum, magnesium or alloys containing light metals. As steel hot strip or cold strip can be used, these terms in the meaning of the jargon for different Bandbreitenberei be understood. By hot strip is meant a rolled steel finished product (steel strip) produced by rolling after preheating. By cold strip is meant a cold-rolled steel strip (flat steel). Cold rolled is flat steel designated, the last reduction in thickness by rolling without previous He warming takes place. For example, IF steels (Interstitial Free), dual phase steels, multiphase steels, TRANSformation Induced Plasticity (TRIP) steels, and microalloyed steels can be used without being limited thereto.

According to a preferred embodiment, a strip material having a width of at least 400 mm is used, in particular of at least 500 mm. By ver relatively large bandwidths, the contact surface of the superposed band were relatively large in relation to the total width. The wider the strip material, the larger are the load-bearing parts when applying the winding pulls. It follows that the absolute surface pressure between the superimposed band was reduced, which also contributes to a reduction of tape adhesives. The intended for flexible rolling metal strip may have a maximum width of up to 2500 mm, in particular of up to 1300 mm, without being limited thereto.

The coil of wound strip material may have an outer diameter of less than 2500 mm, in particular less than 2200 mm. Preferably, the outer diameter is greater than 1500 mm. The inner diameter of the coil may be greater than 500 mm and / or less than 700 mm, for example.

According to one embodiment, the flexibly rolled metal strip can be wound with a variab len Aufwickelzug over the length of the metal strip. In the context of the present disclosure, variable take-up tension means that the coil is wound up with a different winding force at least in a first coil section than in a second coil section spaced radially or circumferentially therefrom. The metal strip can be divided into ring sections, for example, in lengths, be relationship as the coil, which are gradually wound under different tensile forces. Alternatively, it is also possible, the coil as a function of the length of the belt, or of the coiling zuneh ing diameter of the coil, continuously wi with varying tensile forces to wi, for example, as a linear function. Preferably, the flexibly rolled metal strip is wound in a radially inner portion of the coil with a larger Aufwickelzug, as in a radially outer portion. The inner portion may be a portion inner half of an inner third of the coil, or extend over the entire inner third of the coil. By inner third of the coil is meant the annular portion between the inner diameter and an intermediate diameter of the coil, wherein the intermediate diameter is one third of the difference between the outer diameter and the inner diameter. Alternatively or in addition, the radially outer portion may be a portion within an outer third of the coil, or extend over the entire outer third of the coil. As the outer third of the coil, the ring portion between the outer diameter and a Zwi diameter of the coil is meant, wherein the intermediate diameter is two-thirds of the difference between the outer diameter and the inner diameter. The winding tension can be adjusted depending on the sheet thickness and the strength of the mate rials. For example, the metal strip in the radially inner lie ing section a Aufwickelzug of at least 5 N / mm ² , in particular at least 10 N / mm ² min, optionally also at least 15 N / mm ² and / or up to 40 N / mm ² , in particular up to 35 N / mm ² , optionally up to 30 N / mm ² , in each case based on the cross section of the strip material. The cross section of the strip material may refer to a smallest, largest or a middle cross section of the strip material. It is understood that the values given are exemplary and that each of the above-mentioned upper values can be combined with each of the lower values mentioned. The winding pulls can be at least 10%, in particular at least 20%, depending on the material also at least 30% less than the winding tension in the inner coil section in the outer portion of the coil, for example.

The winding tensile forces can be greater, the thicker the strip material and the higher the strength of the strip material. In the case of metal materials with a tensile strength of more than 400 MPa in the unrolled raw material, the winding tensile force can be radially inward, for example between 20 and 30 N / mm ² and radially outside between 10 and 25 N / mm ² . For metal materials with a tensile strength of less than 400 MPa of Unrolled raw material, the winding tension radially inward, for example, between 10 and 25 N / mm ² and radially outside between 5 and 15 N / mm ² are.

After a further process, lubricant, in particular oil, can be applied to the flexibly rolled metal strip prior to winding in order to avoid tape adhesion after annealing. The amount of lubricant applied is in particular at least 0.5 g / m ² and / or up to 3 g / m ² , in each case based on the surface of the strip material. By rolling the strip material undergoes a hardness increase, which is also referred to as rolling hard state. For example, a micro-alloyed fine grain steel called S550MC as a raw material has a yield strength of 550 MPa and a tensile strength of 620 MPa. After rolling, the tensile strength can be over 900 MPa. In order to make the material easier to process for subsequent machining processes, the rolled and coil-wound strip material is annealed in a crucible annealing furnace. As a result, a recrystallization annealing takes place in which the hardness is reduced again and the formability is restored.

A heat treatment of the coil in a hood furnace comprises the phases of heating, holding and cooling. For the avoidance of tape adhesives, it is particularly advantageous if the coil during heating in a temperature range of 100 ° C to 600 ° C with an average heating rate of at least 0.50 ° C / min and / or a maximum of 1, 8 ° C / min is heated, in particular with an average heating rate of 0.80 ° C / min to 1, 40 ° C / min. It is particularly advantageous if the coil is cooled at a cooling rate of less than 0.35 ° C./min, at least in a first temperature range after leaving the holding time. As a result, the forces acting radially inward by the cooling of the material or compressive stresses are kept low during cooling, which has a favorable effect on the tendency to stick. The temperatures given refer in particular to the temperatures measured at the control element of the furnace.

During the heat treatment, in particular during the heating, a protective gas can be introduced into the hood furnace. For a low tendency to stick it is advantageous if the average amount of inert gas during the heating time in a Tem temperature range of 200 ° C to 600 ° C maximum 0.5 m ³ / h per ton of befindli chen in the furnace strip material, in particular not more than 0.25 m ³ / h. In a furnace filling with coils with a total weight of 40 tons, this results in a corresponding to the total weight of inert gas of not more than 20 m ³ / h, in particular special maximum 10m ³ / h.

Preferred embodiments will be explained below with reference to Zeichnungsfigu ren. Hereby shows:

FIG. 1 shows a method according to the invention for avoiding tape adhesives of rolled strip material as a schematic flow diagram in a first embodiment;

FIG. 2 shows a method according to the invention for avoiding tape adhesives of rolled strip material as a schematic flow diagram in a modified embodiment;

Figure 3 shows a coil made of flexible rolled strip material in three-dimensional presen- tation prepared by the method according to the invention;

Figure 4 shows a detail of the coil of Figure 3 in axial view in an enlarged view;

Figure 5 shows the coil of Figure 3 in axial view with drawn dimensions;

Figure 6 shows two layers of superposed turns of the coil of Figure 3 in

Longitudinal section through the coil in a schematic representation;

FIG. 7 shows, by way of example, a thickness profile of a strip section or a board cut from the metal strip;

FIG. 8 shows the temperature course over time during the heat treatment of a

Coils in a furnace with the phases heating, holding and cooling; and 9 shows the temperature profile over time according to FIG. 7 with further details about the protective gas treatment. FIGS. 1 to 9 will be described together below.

FIG. 1 shows a method according to the invention for preventing tape adhesives from rolled strip material, in particular from flexibly rolled strip material 2. In method step S10, the strip material 2, which is also generally referred to as a substrate and is wound on a coil 3 in the initial state, is rolling works, preferably by means of flexible rolling. For this purpose, the Bandma is material 2, which has a largely constant sheet thickness over the length before the flexible rolling, by means of rollers 4, 4 'so rolled that it receives along the rolling direction a variable sheet thickness d2. The work rolls 4, 4 'are supported by means of support rollers 5, 5'. During rolling, the process is monitored and controlled using the data obtained from a sheet thickness measurement 6 as input to control the rolls 4, 4 '. After the flexible rolling, the strip material 2 has different thicknesses in the rolling direction. In this case, the strip mate rial, starting from the substrate with a uniform thickness, with degrees of rolling of 3% to over 40%, in particular in sections also over 50%, are rolled. The starting thickness of the substrate may be, for example, between 0.7 mm and 4.0 mm, without being limited thereto. The flexibly rolled material has accordingly thicker and thinner thicker tape sections, which are made according to a pre-specified nominal thickness profile.

The substrate may in principle be made of any rollable metal or Metalllegie tion, for example, iron-containing metals, in particular steel, or light metals, in particular aluminum, magnesium or alloying alloys containing light metals.

The strip material 2, for example, have a width B2 of at least 400 mm, in particular of at least 500 mm. By relatively wide band width is the contact surface 14, 15 of the superimposed band layers in proportion to the overall width B2 relatively large, as can be seen in particular in Figure 6. The metal strip used for flexible rolling may have a maximum width B2 of up to 2500 mm, in particular of up to 1300 mm, without being limited thereto. The length L2 of the strip material then results from the predetermined diameter D3 of the coil 2 wound to the coil 3 and the thickness profile d2 over the length L2 of the strip. With an average thickness of 1, 5 mm, the band material, for example, have a length of about 2000 m.

The coil 3 of wound strip material 2 may, for example, have an outer diameter D3o of approximately 2000 mm. The inner diameter D3i of the coil 3 may be, for example, greater than 500 mm and / or less than 700 mm.

After rolling, in a step S20 optionally a lubricant 22, preferably oil or an oil-containing agent by means of a corresponding applicator 21 are applied to the flexible rolled metal strip 2. The amount of oil applied is in particular between 0.5 g / m ² and 3 g / m ² , based in each case on the surface 23 of the strip material 2. For example, the lubricant can be sprayed onto the strip material 2 in the form of a spray. After the flexible rolling, or after the optional applications of lubricant, the metal strip 2, at least in a radially outer section 13 of the coil 3 wound with a Aufwickelzug F13 of less than 40 N / mm ² based on a cross-sectional area A2 of the metal strip 2. The flexibly rolled metal strip 2 can be wound up with different winding trains over the length L2 of the metal strip 2. In particular, the metal band 2 can be aufgewi in a radially inner portion 1 1 with larger features F1 1, for example, at least 10% larger than the winding trains F13 of the radially outer portion 13. By winding the strip material with relative low tensile forces F1 1, F13 of less than 40 N / mm ² (= 40 MPa) are the forces acting in the wound coil 3 in the circumferential direction stresses are relatively low, so that in the coil 3 superposed belt surfaces 14, 15 are pressed against each other less strong , As can be seen from FIG. 5, the inner section 11, which may also be referred to as the core, in this embodiment is an inner third of the coil 3. As the inner third of the coil 3, the annular section is between the inner diameter D3i and an intermediate diameter D1 1 meaning the coil, wherein the intermediate diameter D1 1 is one third of the difference between the outer diameter D3o and the inner diameter D3i, that is, D1 1 = 1/3 x (D3o - D3i). This inner lie ing section 1 1 of the coil 3 can in a steel material with a Ausgangsfes activity of more than 400 MPa in the unrolled raw state, for example with a tensile force F1 1 of less than 30 N / mm ² , in particular from 10 to 25 N / mm ² , based on the average cross-sectional area (Am = B2 x dm) of the tape 2 are wound. The middle portion 12 and the outer portion 13 of the coil 3 are preferential, wound with smaller Wickelzügen F12, F13. The outer ring portion 13 can be wound in the said steel material, for example, with a tensile force F13 of 20 to 30 N / mm ² based on the average cross-sectional area. The winding tension F12 for the middle ring portion 12 of the coil 3 extending between the diameters D1 1 and D13 may be identical to the winding tension F13 for the outer coil portion 13 or may be selected in size between the inner winding tension F1 1 and the outer winding tension F13 ,

It is understood that the values mentioned are only examples. For metal materials with a tensile strength of less than 400 MPa of the unrolled raw material or light metal, the winding tensile force radially inward, for example less than 25 N / mm ² , in particular between 10 and 20 N / mm ² , and radially outside less than 15 N / mm ² , in particular 5 and 10 N / mm ² lie.

The take-up pull can be adjusted as a function of a mean thickness dm of the metal strip 2 over the length L2. The calculation of the mean thickness dm of the band or band sections can for example be based on the geometric mean of the thickness profile d2 over the length L2 of the tape or the tape sections, or as an absolute average between a maximum thickness and a smallest thickness of each considered band section and / or the total length of the tape. FIG. 7 shows a It can be seen that the board 7 has a variable thickness D7 over the length L7 of the board, it being understood that the thickness profile of the tape or the boards to be produced therefrom can have any other regular or irregular, symmetrical or unsymmetrical shape. The present board 7 is designed symmetrically and has, starting from the first end, different sections 8a, 8b, 8c, 8d, 8e with different thicknesses d8a, d8b, d8c, d8d, d8e, the first section 8a and the last section 8e on the second Have the same thickness (d8a = d8e) at the end. Between each two sections 8a, 8b, 8c, 8d constant thickness, which can also be referred to as plateaus, each having a transition portion 9a, 9b, 9c is formed with a variable thickness, which can also be referred to as ramps. As described above, the average thickness dm of the band portion 2 for manufacturing the present board 7 can be determined, for example, by the average between the largest thickness d8b and the smallest thickness d8. The thickness dm, and in particular also the width B2 of the band section or band, are then used to determine the band tensile forces F for the winding, wherein the calculated mean value dm can be multiplied by a characteristic number of the material corresponding to the band consolidation.

After the flexible rolling S10 and winding S30 to the coil 30, the wound coil 30 is subjected to a heat treatment in the process of step S40 to soften the material rolled by rolling into a hard-rolled state. This form of heat treatment is also referred to as recrystallization annealing. In the present case, the heat treatment is carried out in a crucible annealing furnace 41, without being limited thereto.

In FIGS. 8 and 9, an exemplary heating curve in the heat treatment S40 of the coil material 2 wound to the coil 3 is shown. It can be seen that the phases heat up S42, hold S43 and cool down S44. The average heating rate R42 during heating S42 in a temperature range of 100 ° C to 600 ° C for steel materials is preferably between 0.50 ° C / min and 1, 8 ° C / min, in particular between 0.80 ° C / min and 1.40 ° C / min. It may also be provided the material is cooled in a first temperature range T44 after leaving the holding time S43, with a cooling rate R44 of less than 0.35 ° C / min. In this case, the specified temperatures relate in particular to the rule according to Regelele from the furnace temperatures.

During the heat treatment S40, particularly during the heating, a shielding gas may be introduced into the hood furnace 41. For a low adhesive tendency, it is favorable if the average amount of protective gas G42 during the heating phase S42, here for example between approximately 2.0 and 8.0 hours, in a temperature range from 200 ° C. to 600 ° C., is 20 m ^{3 at most.} h is, in particular a maximum of 10m ³ / h. The specified amounts of inert gas G42 relate to the total tonnage of the coils in the furnace, which may in particular be between 40 and 60 tons of strip material. In the heat treatment of several coils 3 with a total weight of 40 tons in an oven 41, a specific protective gas quantity of up to 0.5 m ³ / h, in particular of up to 0.25 m ³ / h per ton of strip material 2, would accordingly result result.

After the heat treatment S40, the strip material 2 is unwound in the next method step S50 by means of an unwinding device 50 from the coil 30 and the further processing, in this case a separation S60 of the strip material 2 to individual sheet metal blanks 7. The singulation of the strip material 2 sheet metal blanks 7 takes place For example, by means of a punching or cutting tool 61. Depending on the shape of the sheet metal blanks 7 to be produced this can be punched out of the strip material 2 as a shaped cut, with an edge stops on the strip material, which is not used further, or the strip material 2 can easily in Tail pieces are cut to length.

After the production of boards 7 from the strip material 2 takes place in the process step S70, a forming of the board 7 to the desired end product. The forming takes place in a suitable molding tool 71, in particular by means of cold forming, whereby hot forming is likewise possible.

FIG. 2 shows a method according to the invention for avoiding tape adhesives or for producing a product from a strip material 2 in one modified process management. This corresponds largely to the method of Figure 1, so that reference is made to the above description in terms of similarities. The same or modified Einzelhei th are provided with the same reference numerals, as in Figure 1.

In the method according to Figure 1, we are the strip material 2 immediately after the Fle xible rolls S10, that is wound from the coiler 31 of the rolling mill in the manner mentioned with low band pulls. In other words, the Fle xible rolling and winding done with low band moves in the same system.

On the other hand, in the method according to FIG. 2, the strip material 2 is wound after the flexible rolling S10 in a separate step S30 with the small winding turns of less than 40 N / mm ² relative to the cross-sectional area, the winding optionally being sprayed with lubricant in step S20 22 can be switched on. This process is also called a wrapping process. At closing done the heat treatment S40, as described above, the Ver individually S50 and forming S60 can be downstream.

The abovementioned methods according to the invention or the coils 3 wound in accordance with the invention have the advantage that the stresses acting in the circumferential direction are relatively low, so that the strip surfaces lying on one another in the coil are pressed against one another to a lesser extent. The special heat treatment can additionally have a favorable effect on the stresses acting in the circumferential direction, so that tape adhesives are avoided when rewinding the coil.

LIST OF REFERENCE NUMBERS

2 band material

3 coil

4 roller

5 support roller

6 measuring device

7 board

8 section

9 transition section

1 1 section

12 section

13 section

14 band surface

15 band surface

21 application device

22 lubricants

23 surface

30 coil

31 coiler

41 oven

44 inert gas

51 unwinding device

61 cutting tool

71 mold A area

B width

D diameter d thickness

F power / take-up train

G gas quantity

L length

R rate

S step

T temperature t time

Claims

claims

A method for avoiding tape adhesives on flexibly rolled metal strip, wherein a metal strip (2) after the flexible rolling (S10) wound up to the coil (3) and subjected to a heat treatment (S40), characterized in that the flexibly rolled metal strip ( 2) is wound prior to the heat treatment (S40) at least in a ring portion (13) of the coil (3) with a take-up tension (F13) of less than 40 N / mm ² relative to a cross-sectional area (A2) of the metal strip (2).

2. The method according to claim 1,

characterized,

in that at least one radially outer ring section (13) is wound with a winding pull (F13) of less than 40 N / mm ² , the radially outer ring section (12) lying in an outer third of the coil (3).

3. The method according to claim 1 or 2,

characterized,

in that the flexibly rolled metal strip (2) is wound up with a variable take-up pull (F1 1, F12, F13) over the length (L2) of the metal strip.

4. The method according to any one of claims 1 to 3,

characterized, the take-up pull (F1 1, F12, F13) of the flexibly rolled metal strip is adjusted as a function of an average thickness (dm) of the metal strip over the length (L2).

5. The method according to any one of claims 1 to 4,

characterized,

that the flexibly rolled metal strip (2) in a radially inner ring portion (1 1) of the coil (3) with a larger Aufwickelzugs (F1 1) is wound up, as in a radially outer ring portion (13).

6. The method according to claim 5,

characterized,

the radially inner ring section (11) lies in a radially inner third of the coil (3), and / or

that the radially outer ring portion (12) in a radially outer third tel of the coil (3).

7. The method according to any one of claims 1 to 6,

characterized,

in that the metal strip (2) in the radially inner ring section (1 1) has a take-up pull (F1 1) of at least 10 N / mm ² and / or a maximum of 40 N / mm ² relative to a cross-sectional area (Am) of the metal strip ( 2) is wound up.

8. The method according to any one of claims 1 to 7,

characterized,

in that the metal strip (2) in the radially outer ring section (13) has a winding tension (F13) of at least 5 N / mm ² and / or a maximum of 35 N / mm ² relative to a cross-sectional area (Am) of the metal strip (2). is wound up.

9. The method according to any one of claims 1 to 8,

characterized, in that a metal strip (2) having a width (B2) of at least 400 mm is used, in particular of at least 500 mm, and / or

a metal strip (2) having a width (B2) of not more than 2500 mm is used, in particular a maximum of 1300 mm.

10. The method according to any one of claims 1 to 9,

characterized,

the outer diameter (D3o) of the coil (3) is smaller than 2500 mm and greater than 1000 mm, and / or

the inner diameter (D3i) of the coil is greater than 500 mm and less than 700 mm.

1 1. A method according to any one of claims 1 to 10,

characterized,

in that a metal strip (2) with a tensile strength of the raw material prior to the flexible rolling of less than 400 MPa is used, wherein the metal strip (2) at least in the radially outer ring portion (13) with a Aufwi ckelzug (F13) of less than 20 MPa is wound up, and / or

in that a metal strip (2) with a tensile strength of the raw material prior to the flexible rolling of more than 400 MPa is used, the metal strip (2) at least in the radially outer ring section (13) with a Aufwi ckelzug (F13) of less than 30 MPa is wound up.

12. The method according to any one of claims 1 to 11,

characterized,

in that prior to winding (S30) lubricant (22) is applied to the flexibly rolled metal strip (2), in particular at least 0.5 g / m2 and / or up to 3 g / m2.

13. The method according to any one of claims 1 to 12,

characterized,

in that the coil (3) is subjected to a heat treatment (S40) in a bell-type furnace (41) with the phases heating (S42), holding (S43) and cooling (S44).

14. The method according to claim 13,

characterized,

the coil (3) during the heating (S42) in a temperature range (T) of 100 ° C to 600 ° C with an average heating rate (R42) of at least 0.50 ° C / min and / or of at most 1, 8 ° C / min is heated, in particular with an average heating rate (R42) of 0.80 ° C / min to 1, 40 ° C / min.

15. The method according to any one of claims 13 or 14,

characterized,

that during the heating (S42), a protective gas (44) is introduced into the hood furnace (41), wherein in a temperature range (T) of 200 ° C to 600 ° C, a mean protective gas of not more than 0.5 m ³ / h, in particular of not more than 0.25 m ³ / h per ton of metal strip (2).

16. The method according to any one of claims 13 to 15,

characterized,

in that the coil (3), at least in a first temperature range (T44) after leaving the holding time (S43), is cooled at a cooling rate (R44) of less than 0.35 ° C / min.

17. The method according to any one of claims 1 to 16,

characterized,

in that the metal strip (2) is rolled so flexibly that at least two sections (8a, 8b, 8c, 8d, 8e) having different thicknesses (d8a, d8b, d8c, d8d, d8e) are produced, wherein a first thickness (d8c ) is smaller than a second thickness (d8b) and the ratio of the first thickness (d8c) to the second thickness (d8d) is less than 0.8, in particular less than 0.7, in particular less than 0.6.