EP3575008A1 - Method for avoiding band sticking to flexible rolled strip material - Google Patents

Abstract

The invention relates to a method for avoiding tape adhesives on flexibly rolled metal strip, a metal strip (2) being wound into a coil (3) after flexible rolling (S10) and being subjected to a heat treatment (S40), the flexibly rolled metal strip (2) before the heat treatment (S40) at least in a radially outer ring section (13) of the coil (3) with a winding tension (F13) of less than 40 N / mm ² based on a cross-sectional area (A) of the metal strip (2) is wound up.

Description

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

From the DE 197 50 780 A1 For example, a method of working to apply a defined surface roughness to a metal strip is known to avoid tape adhesive during a subsequent annealing process.

From the EP 0 760 396 A1 For example, there is known a method of avoiding cold strip annealing adhesives, wherein the strip surface is oxidized during the hold time above 600 ° C.

From the WO 03/000438 A1 For example, there is known a method and a tape processing system for avoiding tape adhesives during reeling, in which the axial pressure is measured over the fire width on the coiler mandrel in order to regulate the control values of the strip rolling line 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 formation 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 leads to a coil structure with a variable radius over the circumference and thus possibly also variable tension properties over the circumference.

The present invention is therefore based on the object to propose a method with which the occurrence of tape adhesives, in particular of flexibly rolled metal strip, can be effectively reduced or avoided.

One solution lies in a method for avoiding tape adhesives on flexibly 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 radially outer portion of the coil with a take-up of less than 40 N / mm ² based on a cross-sectional area of the metal strip is wound.

By winding the strip material with relatively low tensile forces of less than 40 N / mm ² (= 40 MPa), the stresses acting in the coiled coil in the circumferential direction are relatively low, so that the mutually superimposed band surfaces are pressed together less strongly. In the course of the heat treatment, there are thus less adhesive effects, so that tape adhesive can be avoided when rewinding the coil. At least one outer section of the coil, for example at least one outer third, in particular at least one outer half, preferably the entire coil, is 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 geometric mean value of the thickness profile over the length of the strip material or one or more strip sections according to a first possibility. Alternatively, the average may also be determined as the absolute average between a maximum thickness and a minimum thickness of a tape section or a total length of the tape. For the calculation of the winding tension, the mean value can be multiplied by a code corresponding to the belt consolidation. Further, from the average of the strip thickness multiplied by the bandwidth, an average cross-sectional area can be calculated that can be used to determine the windings over the length of the strip material.

In flexible rolling, strip material of substantially uniform sheet thickness is rolled out over the length by varying the roll gap during the process into strip material of 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 carried out, for example, such that a first section has a thinner first thickness than a thicker second section, the ratio of the first thickness to the second thickness being less than 0.8, in particular less than 0.7, in particular less than 0, 6 can be. 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. As an alternative, it is also possible for the strip material to be initially wound up with higher strip tension after the 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, when the coil is transferred into the oven.

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, which terms are to be understood in the meaning of the jargon for different bandwidth ranges. 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 referred to as flat steel, the last reduction in thickness of which takes place by rolling without prior heating. For example, IF steels (Interstitial Free), dual-phase steels, multiphase steels, TRANS (Induced Plasticity) steels, and microalloyed steels may 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 relatively large bandwidths, the contact surface of the superposed band layers in relation to the total width is relatively large. 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 layers of tape is 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 for example be greater than 500 mm and / or less than 700 mm.

According to one embodiment, the flexibly rolled metal strip may be wound with a variable winding pull 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, for example, into lengths, or the coil into ring sections, which are wound in stages with different tensile forces. Alternatively, it is also possible to wind the coil as a function of the length of the strip, or of the increasing diameter of the coil during winding, continuously with changing tensile forces, 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 within an inner third of the coil, or 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. The outer third of the coil means the annular section between the outer diameter and an intermediate diameter of the coil, 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 material. For example, the metal strip in the radially inner section may have a winding pull of at least 5 N / mm ² , in particular at least 10 N / mm ² , 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. 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, for example, at least 10%, in particular at least 20%, less than the winding tension in the inner coil section in the outer section of the coil, for example by at least 30%, depending on the material.

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 . In the case of metal materials with a tensile strength of less than 400 MPa of the unrolled raw material, the winding tensile force can lie radially inwardly, for example, between 10 and 25 N / mm ² and radially outside between 5 and 15 N / mm ² .

After a further process, lubricant, in particular oil can be applied to the flexibly rolled metal strip prior to winding to avoid tape adhesive 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 a hard-rolling condition. For example, a microalloyed fine grain structural 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 bell 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 heating, holding and cooling phases. For the avoidance of tape adhesives, it is particularly advantageous if the coil during the 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 of at most 1.8 ° C. / min, in particular with an average heating rate of 0.80 ° C / min to 1.40 ° C / min. It is particularly advantageous if the coil, at least in a first temperature range after leaving the holding time, is cooled at a cooling rate of less than 0.35 ° C / min. 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 adhere it is favorable if the average amount of inert gas during the heating time in a temperature range from 200 ° C. to 600 ° C. is at most 0.5 m ³ / h per ton of the strip material located in the furnace, 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 a maximum of 10m ³ / h.

Figur 1

ein erfindungsgemäßes Verfahren zur Vermeidung von Bandklebern von gewalztem Bandmaterial als schematisches Ablaufdiagramm in einer ersten Ausführungsform;

Figur 2

ein erfindungsgemäßes Verfahren zur Vermeidung von Bandklebern von gewalztem Bandmaterial als schematisches Ablaufdiagramm in einer abgewandelten Ausführungsform;

Figur 3

ein Coil aus flexibel gewalztem Bandmaterial in dreidimensionaler Darstellung hergestellt nach dem erfindungsgemäßen Verfahren;

Figur 4

ein Detail des Coils aus Figur 3 in Axialansicht in vergrößerter Darstellung;

Figur 5

das Coil aus Figur 3 in Axialansicht mit eingezeichneten Dimensionen;

Figur 6

zwei Lagen von aufeinander liegenden Windungen des Coils aus Figur 3 im Längsschnitt durch das Coil in schematischer Darstellung;

Figur 7

beispielhaft ein Dickenprofil eines Bandabschnitts beziehungsweise einer aus dem Metallband geschnittener Platine;

Figur 8

den Temperaturverlauf über der Zeit während der Wärmebehandlung eines Coils in einem Ofen mit den Phasen Aufheizen, Halten und Abkühlen; und

Figur 9

den Temperaturverlauf über der Zeit gemäß Figur 7 mit weiteren Details über die Schutzgasbehandlung.

Preferred embodiments will be explained below with reference to the drawing figures. Hereby shows:

FIG. 1

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

a method according to the invention for the prevention of tape adhesives of rolled strip material as a schematic flow diagram in a modified embodiment;

FIG. 3

a coil of flexible rolled strip material produced in three-dimensional representation by the method according to the invention;

FIG. 4

a detail of the coil FIG. 3 in axial view in an enlarged view;

FIG. 5

the coil out FIG. 3 in axial view with drawn dimensions;

FIG. 6

two layers of superposed turns of the coil FIG. 3 in a longitudinal section through the coil in a schematic representation;

FIG. 7

an example of a thickness profile of a band section or a cut from the metal strip board;

FIG. 8

the temperature over time during the heat treatment of a coil in an oven with the phases heating, holding and cooling; and

FIG. 9

according to the temperature over time FIG. 7 with further details about the inert gas treatment.

The FIGS. 1 to 9 will be described together below.

FIG. 1 shows a method according to the invention for the prevention of tape adhesives of rolled strip material, in particular flexible rolled strip material 2. In step S10, the strip material 2, which is also generally referred to as a substrate and wound on a coil 3 in the initial state, rolled, preferably by means of flexible rolling. For this purpose, the strip material 2, which has a largely constant sheet thickness over the length prior to flexible rolling, is rolled by means of rollers 4, 4 'in such a way that it receives a variable sheet thickness d2 along the rolling direction. 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 material, 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 out. 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 accordingly has thickness-reduced thicker and thinner strip sections, which are produced according to a predetermined nominal thickness profile.

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

The strip material 2 may, for example, have a width B2 of at least 400 mm, in particular of at least 500 mm. By relatively large bandwidths, the contact surface 14, 15 of the superposed band layers in relation to the total width B2 is relatively large, in particular in FIG. 6 recognizable. 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 up to the coil 2 and the thickness profile d2 over the length L2 of the band. For example, with a mean thickness of 1.5 mm, the strip material may have a length of about 2000 meters.

The coil 3 of wound strip material 2 may for example have an outer diameter D3o of about 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 can be applied to the flexibly rolled metal strip 2 by means of a corresponding application device 21. The amount of oil applied is in particular between 0.5 g / m ² and 3 g / m ² , in each case based 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 application of lubricant, the metal strip 2 is wound at least in a radially outer portion 13 of the coil 3 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 strip 2 can be wound up in a radially inner section 11 with larger creases F11, which can be, for example, at least 10% larger than the winding cords F13 of the radially outer section 13. By winding the strip material with relatively low tensile forces F11, F13 of less than 40 N / mm ² (= 40 MPa), the circumferentially acting in the wound coil 3 voltages are relatively low, so that the superimposed in the coil 3 band surfaces 14, 15 are pressed against each other less.

How out FIG. 5 As can be seen, the inner portion 11, which may also be referred to as a core, in this embodiment, an inner third of the coil 3. As the inner third of the coil 3, the ring portion between the inner diameter D3i and an intermediate diameter D11 of the coil, wherein the intermediate diameter D11 is one third of the difference between the outside diameter D3o and the inside diameter D3i, that is, D11 = 1/3 x (D3o-D3i). This inner portion 11 of the coil 3, in a steel material having an initial strength of about 400 MPa in the unrolled raw state, for example, with a tensile force F11 of less than 30 N / mm ² , in particular from 10 to 25 N / mm ² , based on the middle Cross-sectional area (Am = B2 x dm) of the belt 2 are wound. The middle section 12 and the outer section 13 of the coil 3 are preferably wound up with smaller winding trains 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 diameter D11 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 tension coil F11 and the outer tension coil 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 average thickness dm of the strip or strip sections can be carried out, for example, based on the geometric mean value of the thickness profile d2 over the length L2 of the strip material or the strip sections, or as an absolute average value between a maximum thickness and a minimum thickness of the respective strip section considered and / or the total length of the tape. FIG. 7 It can be seen that the board 7 has a variable thickness profile D7 over the length L7 of the board, it being understood that the thickness profile of the tape or of the boards to be produced therefrom each any other regular or irregular, symmetric or asymmetrical shape may have. The present board 7 is symmetrical in shape and has, starting from the first end, various sections 8a, 8b, 8c, 8d, 8e with different thicknesses d8a, d8b, d8c, d8d, d8e, the first section 8a and the last section 8e at the second end have the same thickness (d8a = d8e). 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 the FIGS. 8 and 9 an exemplary heating curve in the heat treatment S40 of the coil 3 wound strip material 2 is shown. It can be seen that the heating up phases S42, hold S43 and cooling S44 are run through. 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 further be provided that the material is cooled in a first temperature range T44 after leaving the hold time S43, with a cooling rate R44 of less than 0.35 ° C / min. In this case, the indicated temperatures relate in particular to the temperature applied to the control element by the furnace.

During the heat treatment S40, particularly during the heating, a shielding gas may be introduced into the hood furnace 41. For a low tendency to adhere, it is favorable if the average amount of protective gas G42 during the heating phase S42, here by way of example between about 2.0 and 8.0 hours, in a temperature range from 200 ° C. to 600 ° C. is a maximum of 20m ³ / h, in particular maximum 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 plates to be manufactured 7 this can be punched out of the strip material 2 as a shaped cut, with an edge on the strip material stops, which is not used, or the strip material 2 can be easily cut to pieces.

After producing blanks 7 from the strip material 2, the blanks 7 are formed into the desired end product in method step S70. The forming takes place in a suitable molding tool 71, in particular by means of cold forming, whereby hot forming is likewise possible.

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

In the method according to FIG. 1 we wound the strip material 2 immediately after the flexible rolling S10, that is, from the coiler 31 of the rolling mill in the manner mentioned with small strip tension. In other words, the flexible rolling and the winding with small band trains done in the same plant.

In contrast, the strip material 2 in the method according to FIG. 2 after the flexible rolling S10 wound in a separate step S30 with the small winding tension of less than 40 N / mm ² based on the cross-sectional area, wherein the winding optionally optionally can be preceded by spraying with lubricant 22 in step S20. This process is also called a wrapping process. Subsequently, the heat treatment S40, as described above, may be followed by the singulation S50 and forming S60.

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 small, 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 may 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

supporting roll

6

measuring device

7

circuit board

8th

section

9

Transition section

11

section

12

section

13

section

14

band surface

15

band surface

21

applicator

22

lubricant

23

surface

30

coil

31

coiler

41

oven

44

protective gas

51

unwinding

61

cutting tool

71

mold

A

surface

B

width

D

diameter

d

thickness

F

Power / Aufwickelzug

G

amount of gas

L

length

R

rate

S

step

T

temperature

t

Time

Claims (15)

Method for avoiding tape adhesives on flexibly rolled metal strip,
wherein a metal strip (2) after the flexible rolling (S10) is wound up to the coil (3) and subjected to a heat treatment (S40),
characterized in that the flexible rolled metal strip (2) before the heat treatment (S40) at least in a radially outer ring portion (13) of the coil (3) with a Aufwickelzugs (F13) of less than 40 N / mm ² based on a cross-sectional area ( A2) of the metal strip (2) is wound up. Method according to claim 1,
characterized,
in that the flexibly rolled metal strip (2) is wound up over the length (L2) of the metal strip with a variable take-up pull (F11, F12, F13). Method according to claim 1 or 2,
characterized,
in that the take-up pull (F11, 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). Method according to one of claims 1 to 3,
characterized,
in that the flexibly rolled metal strip (2) is wound in a radially inner ring section (11) of the coil (3) with a larger winding pull (F11) than in a radially outer ring section (13), wherein the inner ring section (13) 11) extends over a radially inner third of the coil (3), and / or
wherein the outer ring portion (12) extends over a radially outer third of the coil (3). Method according to one of claims 1 to 4,
characterized,
in that the metal strip (2) in the radially inner ring section (11) has a winding pull (F11) of at least 10 N / mm ² and / or a maximum of 40 N / mm ² relative to a mean cross-sectional area (Am) of the metal strip (2 ) is wound up. Method according to one of claims 1 to 5,
characterized,
in that the metal strip (2) in the radially outer annular 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 mean cross-sectional area (Am) of the metal strip (2 ) is wound up. Method according to one of claims 1 to 6,
characterized,
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
that a metal strip (2) is used having a width (B2) of at most 2500 mm, in particular of at most mm 1300th Method according to one of claims 1 to 7,
characterized,
that the outer diameter (D3o) of the coil (3) is less than 2500 mm and greater than 1000 mm, and / or
that the inner diameter (D3i) of the coil is greater than 500 mm and smaller than 700 mm. Method according to one of claims 1 to 8,
characterized,
in that a metal strip (2) with a strength of the raw material before flexible rolling of less than 400 MPa is used, the metal strip (2) being wound with at least the radially outer ring section (13) with a winding pull (F13) of less than 20 MPa is used, and / or that a metal strip (2) is used with a strength of the raw material before flexible rolling of more than 400 MPa, wherein the metal strip (2) at least in the radially outer ring portion (13) with a Aufwickelzug (F13) of less than 30 MPa is wound up. Method according to one of claims 1 to 9,
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. Method according to one of claims 1 to 10,
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). Method according to claim 11,
characterized,
that 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 a maximum of 1.8 ° C / min, in particular with an average heating rate (R42) of 0.80 ° C / min to 1.40 ° C / min. Method according to one of claims 11 or 12,
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). Method according to one of claims 11 to 13,
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. Method according to one of claims 1 to 14,
characterized,
that the metal strip (2) is rolled so flexibly that at least two sections (8a, 8b, 8c, 8d, 8e) with 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.

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