Cold rolling stand for cold rolling a cold rolled strip, method for producing a cold rolled strip, method for changing a roller configuration in a cold rolling stand, and roller assembly for use during the method

Abstract

The invention relates to a cold rolling stand (2) for cold rolling a cold rolled strip. The cold rolling stand (2) has an upper and a lower working roller (4, 6), and the upper and lower working rollers (4, 6) have different diameters. The invention additionally relates to a method for producing a cold rolled strip (7) using a cold rolling stand (2) and also to a method for changing a roller configuration in a cold rolling stand (2).

Description

[0001] Cold rolling stand for cold rolling a cold strip, method for producing a cold strip, method for changing a roll configuration in a cold rolling stand and roll arrangement for use in the method

[0002] The invention relates to a cold rolling stand for cold rolling a cold strip and a method for producing a cold strip using such a cold rolling stand. The invention further relates to a method for changing a roll configuration in a cold rolling stand and a roll assembly as a replacement set for carrying out the method for changing the roll configuration.

[0003] In the field of cold rolling, increasingly thinner materials and / or materials with higher strength or generally improved mechanical properties are being processed. Especially for the DCR (Double Cold Reduction) process in the tinplate industry, this means the production of grades of DR9.5 (AISI / ASTM 623) or higher, a final thickness of the rolled strips approaching 0.1 mm, and a thickness reduction during rolling with a reduction of up to 50% in a single operation.

[0004] In the production of packaging steel, it is generally known to provide tinned or electrolytically chrome-plated steel in thicknesses from 0.100 to 0.499 mm – optionally with or without organic coatings (paint, polymer). After an initial cold reduction of the pickled steel strip, the strips are electrolytically cleaned in a tandem mill, for example, placed in a furnace for recrystallization annealing, and then transferred to one of three two-stand tempering mills to adjust the surface and mechanical properties. This can be either a dry skin-pass mill with low elongation or a wet rolling mill with a greater strip thickness reduction in a first cold rolling stand, the so-called DCR mill (Double Cold Reduction). Finally, an electrolytic tinning or chrome-plating process follows.

[0005] DCR tapes are thin and strong, making them attractive as a packaging material, as they reduce transportation costs and carbon emissions, for example. Typical applications include screw caps and DRD (drawn and redrawn) cans.

[0006] Since alloyed steel cannot be used for food and beverage containers, work hardening through higher reductions is the preferred method for achieving higher strength. Furthermore, for soft grades, a high strip thickness reduction in the DCR process is beneficial for ear formation during drawing.

[0007] The invention is based on the object of providing a cold rolling mill which enables a high thickness reduction in the production of particularly thin strips, in particular steel strips in the order of magnitude of up to a thickness of 0.1 mm.

[0008] The invention is further based on the object of achieving such a thickness reduction using relatively low rolling forces.

[0009] The object is achieved by providing a cold rolling stand with the features of claim 1.

[0010] The object is further achieved by providing a method for producing a cold strip using a cold rolling stand according to the invention.

[0011] Another aspect of the invention, which is protectable in itself, relates to a method for changing a roll configuration in a cold rolling mill with a conventional work roll configuration. The object underlying the invention is finally achieved by providing a roll assembly as a replacement set for carrying out the configuration change.

[0012] Advantageous features of the invention emerge from the respective subclaims.

[0013] A first aspect of the invention relates to a cold rolling stand for cold rolling a cold strip, wherein the cold rolling stand has at least one upper and one lower work roll, and the upper and lower work rolls have different diameters. The configuration according to the invention has the advantage that, in particular, a reduction in the diameter of a work roll in an asymmetrical work roll configuration results in a significant reduction in the strip thickness of up to 50% in combination with a relatively low achievable strip thickness. With approximately the same rolling force compared to a symmetrical roll configuration, the strip thickness can be reduced significantly more according to the invention. The upper work roll preferably has a smaller diameter than the lower work roll.

[0014] Preferably, the diameter of the upper and lower working rolls is 2 g a according to the formula De7 f 7 f = - l / Dtop + l / Dbot, where De 7 f 7 f the effective

[0015] Diameter of the work rolls, Dtop is the diameter of the upper work roll, and Dbot is the diameter of the lower work roll. The effective diameter of the work rolls is called the combined work roll diameter. The sum of the work roll curvature is the inverse of the work roll radii.

[0016] This calculation makes it easy to determine a theoretical symmetrical roll diameter, which can be used as a basis for rolling force and reduction calculations in pass schedule calculations. The operating parameters determined from the pass schedule calculation can be used to adjust the operating parameters.

[0017] From a roll gap behavior perspective, a 5-high configuration combines a large, driven lower work roll with a much smaller, non-driven upper work roll. The different work roll diameters (approximately 300 mm) and the individual drive lead to asymmetric rolling conditions. These asymmetric rolling conditions result in internal shear stresses that support forming.

[0018] A first resulting technical effect is a significant reduction in roll force in 5-high mode compared to 4-high mode. With the same roll force, the strip thickness can be reduced significantly. In a successful test by the applicant, a reduction of 50% was achieved. Several coils were rolled with a reduction of 40-42%, and the maximum strip speed at the exit was 2000 m / min. Flatness control was in normal operation, and the strip flatness quality was within the known range. The thickness control parameters were adjusted due to the lower ratio of rolling force difference to reduction difference.

[0019] To better understand the roll gap behavior in a 5-high configuration with asymmetric work rolls, it is helpful to imagine a hypothetically symmetric configuration with the same sum of work roll curvatures (inverse of the work roll radii) as in the asymmetric case. Then, the combined work roll diameter, the so-called effective work roll diameter, is calculated as follows:

[0020] 2

[0021] Def =

[0022] Dtop Dbot Compared to a 4-high work roll configuration with two work rolls each with a diameter of 512 mm, the effective work roll diameter of an asymmetric work roll configuration with the upper work roll having a diameter of 240 mm and the lower work roll having a diameter of 512 mm is 327 mm.

[0023] This method allows for the effective rolling of particularly thin strips, which would be unattainable with the 4-hi mode. Furthermore, a significant reduction in rolling force is achieved while simultaneously achieving a significant reduction in thickness and a higher yield stress, thus also reducing energy consumption with this type of work roll configuration.

[0024] The advantages of the invention can also be achieved with a cold rolling mill with an asymmetric work roll configuration, in which the lower work roll has a smaller diameter than the upper work roll. Accordingly, the above statements also apply to such a configuration.

[0025] A small work roll is a work roll with a diameter that is significantly smaller than the diameter of the large work roll; even when the large work roll is fully ground, the small work roll has a smaller diameter.

[0026] Preferably, the diameter of the smaller work roll is between 120 mm and 380 mm, preferably between 180 and 320 mm, further preferably between 200 and 250 mm.

[0027] The diameter of the upper work roll is preferably between 180 and 320 mm. Furthermore, the cold rolling mill according to the invention preferably has a 5-high configuration. It is expediently provided that a support roll, preferably designed as an intermediate roll, supports the smaller work roll, preferably the upper work roll, and the support roll preferably has a diameter between 180 mm and 520 mm, preferably between 250 mm and 450 mm, and furthermore preferably between 280 and 300 mm.

[0028] Preferably, the sum of the diameters of the smaller work roll and the diameter of the support roll corresponds approximately to the diameter of the larger work roll.

[0029] Preferably, the small work roll and the intermediate roll are mounted in roller bearings and lubricated with an oil-air lubrication system. Oil-air lubrication is particularly advantageous at high strip speeds.

[0030] In a preferred embodiment of the cold rolling mill according to the invention, the work rolls can be provided with a hard coating as a wear and corrosion protection coating, preferably a chrome coating. Chrome-plated rolls are particularly wear-resistant and enable rolling with low surface roughness.

[0031] Preferably, at least one intermediate roll is cylindrical, and at least one work roll has a preferably positive and / or preferably centrally arranged crown. The preferably positive crown of the work roll allows for the targeted adjustment of bending lines, which, as actuators of a flatness control system, contribute to improving strip flatness.

[0032] In the 5-high configuration of the cold rolling stand according to the invention, it is preferably provided that the smaller, preferably the upper, work roll and the associated, preferably upper, intermediate roll are not driven. The terms "top" and "bottom" generally refer to the installation position. In a preferred variant of the cold rolling stand according to the invention, one strip tension adjustment device can be arranged on the inlet side and one on the outlet side of the rolls.

[0033] The strip tension adjustment devices can be the winding and / or unwinding reel and / or special deflection or sizing devices. With the strip tension adjustment devices, the strip advance and retraction, as well as strip speeds that deviate from the roll circumferential speed, can be specifically adjusted. This is important for adjusting the roll gap geometry and can produce advantageous effects within the scope of the invention.

[0034] A further aspect of the invention relates to a method for producing a cold strip using a cold rolling mill of the type described above, having one or more of the features described above. The method comprises reducing the thickness of the cold strip between two work rolls with an asymmetrical work roll configuration or with different diameters.

[0035] In an advantageous variant of the method according to the invention, it is provided that the thickness of the cold strip is reduced, preferably in one rolling pass or a single strip pass, by more than 30%, preferably by more than 35%, preferably more than 40%, particularly preferably by more than 45%.

[0036] The thickness reduction or thickness decrease can be carried out with a strip throughput speed > 1200 m / min, preferably > 2000 m / min.

[0037] During rolling, the strip advance is preferably set higher than the strip retraction by the strip tension adjustment devices. In an expedient variant of the method according to the invention, the rolling force is set to a value that is at least 30%, preferably at least 40%, and most preferably at least 50% lower than the required rolling force when using a symmetrical roll set with exclusively large rolls (4-high configuration).

[0038] Particularly preferably, the cold strip is reduced in the cold rolling stand in a single pass from an initial thickness of 0.13 mm to 0.2 mm to a final thickness of > 0.1 mm, which is particularly due to the fact that with the asymmetrical work roll configuration described above, a thickness reduction of up to 50% can be achieved with the same rolling force compared to a symmetrical work roll configuration in which each of the work rolls has a diameter which corresponds to the diameter of the largest work roll in the asymmetrical work roll configuration according to the invention.

[0039] Preferably, the thickness reduction in the method according to the invention is carried out with a strip throughput speed in the outlet > 1200 m / min, preferably > 2000 m / min.

[0040] A further aspect of the invention, which is protectable in itself, relates to a method for changing a roll configuration in a cold rolling stand, preferably in cassette construction, from a 4-high configuration with symmetrical work roll diameters to a 5-high configuration with asymmetrical work roll diameters, which is designed to carry out the method according to the invention, wherein during a configuration change at least one of the work rolls of the cold rolling stand is replaced by a roll arrangement as a replacement set, wherein the replacement set comprises at least two replacement rolls which are mounted in a common cassette, wherein the upper and lower work rolls have a different diameter after the configuration change.In this way, an existing 4-high configuration can be converted in a particularly advantageous and simple manner so that a significantly higher thickness reduction of the cold strip can be achieved with approximately the same rolling force.

[0041] Preferably, the sum of the work roll curvatures of the asymmetric work roll configuration corresponds to the sum of the work roll curvatures of the symmetric roll configuration.

[0042] In an advantageous variant of the method, the diameter of the upper and lower working rolls is determined according to the formula where De ff is the effective diameter of the work rolls, Dtop is the diameter of the upper work roll and Dbot is the diameter of the lower work roll.

[0043] Preferably, the method for changing a roller configuration comprises carrying out the exchange set via a quick-change roller device in less than 15 minutes of downtime, preferably less than 12 minutes of downtime, most preferably in less than 7 minutes of downtime and most preferably in less than 5 minutes of downtime.

[0044] Preferably, the roll change takes place in a 4-high mode using the same quick-change device as in the 5-high mode. Finally, a further aspect relates to a roll assembly as a replacement set for carrying out the above-described method for changing the roll configuration, comprising a work roll and at least one intermediate roll mounted in a common cassette. The cassette has work roll chocks whose installation dimensions essentially correspond to those of the work roll chocks of the cold rolling stand in the 4-high configuration.

[0045] In order to ensure that the upper work roll and the upper backup roll are not driven in such a converted 5-high configuration, it can be provided that a drive pin dummy is provided in a work roll chock provided on the drive side, which is designed such that the work roll of the replacement set is not driven in the installed position.

[0046] The invention is explained below with reference to an embodiment illustrated in the drawings.

[0047] They show:

[0048] Figure 1 is a schematic representation of a cold rolling mill with a cold rolling stand according to the invention,

[0049] Figure 2 is a schematic representation of the structure of a roller arrangement according to the invention in the form of a removable cassette as an exploded view of the individual components of the removable cassette,

[0050] Figure 3 shows a schematic comparison of a 4-high configuration according to the prior art and a 5-high configuration according to the invention,

[0051] Figure 4 is a graphical representation of the line load of the rolled material during cold rolling with a 5-high configuration compared to coils rolled with a conventional 4-high configuration,

[0052] Figure 5 is a graphical representation of a stationary FEM solution for asymmetric and equivalent symmetric work roll configurations based on measured data for steel grade DR 8, strip geometry 960 mm x 0.244 -> 0.142 mm. Figure 6 is a calculation example for the calculated reduction of the rolling force and the energy consumption of a main drive of the cold rolling mill in the 5-high mode according to the invention compared to a conventional 4-high mode based on the measured rolling force for steel grade DR 8, strip geometry 960 mm x 0.244 -> 0.142 mm.

[0053] Figure 7 is a graphical representation of a 3-D profile height measurement of the work roll surface before and after rolling of four coils with the 5-high configuration according to the invention by confocal microscopy,

[0054] Fig 7a) a representation corresponding to Figure 7

[0055] The cold rolling mill 1 shown in Figure 1 consists of a first and a second cold rolling stand 2, 3, both in a 4-high configuration with work roll diameters of 563 and 505 mm. The smaller diameter of one of the two work rolls 4 is due to the fact that the work roll 4 in question has reached the end of its service life due to wear.

[0056] The first cold rolling stand 2 reduces the thickness of a cold strip 7 (typically 8 to 32%) in a thickness control (thickness reduction), while the second cold rolling stand 3 is designed as a skin-pass mill, which improves the strip surface in force control (virtually no stretching). The first cold rolling stand 2 is driven by a pinion work roll drive; in the second cold rolling stand 3, only the lower work roll 4 is driven. The maximum strip exit speed is over 2000 m / min.

[0057] The cold rolling mill is equipped with strip tensioning devices that allow the strip advance and retraction to be precisely adjusted.

[0058] If the roll gap lubrication conditions and strip tensile stresses are already at an appropriate or maximum capacity level, reducing the work roll diameter for such a mill is the most efficient way to achieve the goal of a high reduction (up to 50%) in combination with thin gauges (minimum final strip thickness 0.1 mm). For an existing mill, this typically requires a major retooling.

[0059] One aspect of the present invention relates to the conversion of a cold rolling mill 2 such that an asymmetrical work roll configuration can be realized. For this purpose, the invention provides for the provision of an exchangeable cassette 5, as schematically illustrated, for example, in Figure 2.

[0060] The change cassette 5 according to the invention is designed to at least temporarily replace the upper work roll 4 of the first cold rolling stand 2 in order to create a 5-high instead of the 4-high configuration. It consists of a small work roll (AR) 6 with a diameter of 240 / 220 mm and an intermediate roll (IMR) 8 with a diameter of 320 / 300 mm. The sum of the two diameters (560 / 520 mm) is selected within the range of the normally used large work roll 4, so that no additional measures for height adjustment are necessary. The outer chock geometry of the change cassette 5 corresponds exactly to the dimensions of the large work roll 4, so that the conversion from a 4-high to a 5-high mode and back is as quick and easy as a normal work roll change.

[0061] The intermediate roll chocks 9 have effective surfaces so that bending forces are transmitted to the intermediate roll 8. Positive and negative bending forces could be utilized, but were limited to half the value in the tests conducted by the applicant to avoid overloading the bearing of the intermediate roll 8. Due to the smaller diameter of the intermediate roll 8 compared to the larger (lower) work roll 4, the bending is still effective. The chocks of the small upper work roll 6 are integrated into chocks 9 of the intermediate roll 8 (chock within chock construction) and can slide freely in the vertical direction. Thus, only horizontal forces and no bending forces are transmitted to the work roll 6.

[0062] In the described embodiment, the intermediate roll 8 of the interchangeable cassette 5 is cylindrical, while the work roll 6 has a positive crown, which was calculated to correspond to the flatness targets within the bending force range. Flatness control for the first cold rolling stand 2 using cross-stand flatness measuring rolls functions without modification.

[0063] On the drive side of the second cold rolling stand 2, a dummy drive pin 10 for accommodating an upper drive spindle is mounted on the chock 9 of the exchangeable cassette 5. The dummy drive pin 10 comprises a free-running double ball bearing that has no other connection to the rolls. This means that the upper intermediate roll 8 and the upper drive roll 6 are not driven, while the entire main drive torque is transferred to the original lower work roll 4. This configuration has the advantage that no changes to the gear ratio or direction of rotation are necessary.

[0064] The 5-hi configuration according to the invention combines a driven large lower work roll 4 with a much smaller, non-driven work roll 6. The different work roll diameters (approx. 300 mm) and the individual drive lead to asymmetric rolling conditions.

[0065] The reduction in roll force in the 5-hi mode compared to the 4-hi mode is illustrated in Figure 4. With the same roll force, the strip thickness can be reduced significantly more than with a 4-high roll configuration.

[0066] Figure 5 illustrates the roll gap behavior in 5-high operation (left configuration) compared to a hypothetically symmetrical configuration (right configuration), which has the same sum of work roll curvatures (inverse of the work roll radii) as in the asymmetrical case. The joint work roll diameter, the so-called effective work roll diameter, is then calculated as follows:

[0067] For example, if, as in some tests carried out by the applicant, a new small upper work roll 6 (diameter Dtop = 240 mm) is coupled with a used large lower work roll 4 (diameter Dbot = 512 mm), the formula gives approximately 327 mm as the effective diameter.

[0068] The pressure distribution in the roll gap, calculated using a proprietary steady-state (viscoplastic) finite element algorithm, is almost identical for the symmetric and the actual asymmetric case (Figure 5, center). The friction coefficient of the roll gap was precisely adjusted to achieve the measured rolling force for one of the tests. The roll gap length is the same; only in the area of ​​maximum pressure is the peak of the so-called pressure peak flattened in the asymmetric solution compared to the symmetric case, resulting in a slightly lower rolling force. Since the difference is small and the effective work roll diameter is used, the calculations using a standard program for the pass schedule yield good results regarding the rolling force.

[0069] The solutions differ with regard to forward slip. Since only the lower work roll 4 is driven, the peripheral speed is higher than that of the non-driven upper work roll 6 (Figure 5, right). The strip exit speed compared to the peripheral speed of the lower work roll 4, which is directly related to a forward slip value recorded and displayed by an automation system, is lower in the asymmetric solution than in the symmetric solution.

[0070] The measured overfeed (5.7%) is quite close to an asymmetrically calculated overfeed (5.2%). Generally, care must be taken to prevent slippage of the driven roll on the strip. As measurements and calculations show, the strip overfeed is high enough for thin strip to ensure reliable pull-through. The situation improves even further when the specific strip overfeed is higher than the strip retraction, which is typically the case in the first cold rolling stand of a DCR mill.

[0071] The reduction in rolling force achieved according to the invention in 5-hi mode compared to 4-hi mode is an advantage when rolling thin strips with a high thickness reduction and therefore increased tensile stress. When considering the energy savings, however, it must be noted that the rolling force itself does not consume any energy. However, there are two associated effects: One is the lower bearing friction loss of the upper backup roll, and the other is the lower drive torque resulting from the reduced roll gap length and thus lower friction losses due to the relative movement between the strip and work roll 6.

[0072] Figure 6 shows the potential energy savings for a main drive of cold rolling mill 2 for the example discussed above. The following assumptions were made: constant (fairly low) backup roll bearing friction p=0.001, constant roll gap friction coefficient, no roll contact at the strip edges, constant strip exit speed (same productivity). Overall, a saving of almost 10% in main drive power is realistic.

[0073] There is a diameter difference of 2.1 to 2.56 between the small work roll 6 of the interchangeable cassette 5 in 5-hi mode and the normal work roll 4 in 4-hi mode. The number of revolutions per strip length of the small work roll 6 increases by this factor, resulting in greater wear. On the other hand, the roll force is significantly lower, which is associated with less wear. To get an idea of ​​the magnitude, for the example case discussed in the previous sections, the maximum pressure in the roll gap is reduced from approximately 2100 MPa in 4-high mode to approximately 1100 MPa in 5-high mode, Figure 5, center.

[0074] Another aspect is the difference between the upper and lower work rolls and the development of the strip surface roughness in the 5-high mode itself. In terms of wear, the large lower work roll 4 is expected to benefit twice: firstly, through its larger diameter and thus more surface area, and secondly, through a lower Hertzian pressure in contact with the backup roll compared to the small upper work roll 6, which is in contact with the intermediate roll 8.

[0075] For the last test campaign with four coils in 5-high mode, both work rolls 4.6 were freshly ground and chrome-plated. The 3D surface roughness measurements before and after rolling show only minor differences for both rolls (Figure 7). The Ra value (arithmetic mean roughness) remains similar within statistical limits. Apparently, the roll gap pressure and the resulting rolling force are so low that no significant wear effect is visible on the chrome-plated rolls. The Rp value (height of the largest profile peak of the roughness profile) decreases simultaneously for both rolls, reflecting the well-known flattening of surface irregularities caused by the initial contact with the strip and the other rolls. No statistically significant differences in strip roughness were found between the top and bottom surfaces.

[0076] List of reference symbols

[0077] 1 cold rolling mill

[0078] 2 first cold rolling stand 3 second cold rolling stand

[0079] 4 work rolls

[0080] 5 interchangeable cassettes

[0081] 6 smaller upper work roll of the 5-high configuration

[0082] 7 Cold strip 8 upper intermediate roll of the 5-high configuration

[0083] 9 Inserts of the interchangeable cassette

[0084] 10 drive pin dummy

Claims

Patent claims 1 . Cold rolling stand (2) for cold rolling a cold strip, wherein the cold rolling stand (2) has an upper and a lower work roll (4,6) and the upper and lower work rolls (4,6) have a different diameter.

2. Cold rolling stand (2) according to claim 1, characterized in that the diameter of the upper and lower working rolls is determined according to the 2 Formula Deff = -, where Deff is the effective Diameter of the work rolls, Dtop is the diameter of the upper work roll and Dbot is the diameter of the lower work roll.

3. Cold rolling mill (2) according to one of claims 1 or 2, characterized in that the diameter of the smaller working roll (6) is between 120 mm and 380 mm, preferably between 180 and 320 mm, further preferably between 200 and 250 mm.

4. Cold rolling stand (2) according to one of claims 1 to 3, characterized in that the cold rolling stand (2) is designed with a 5-high configuration.

5. Cold rolling stand (2) according to one of claims 1 to 4, characterized in that at least one support roller, preferably designed as an intermediate roll (8), supports the smaller work roll (6); and the support roller has a diameter between 180 mm and 520 mm, preferably between 250 mm and 450 mm, further preferably between 280 and 300 mm.

6. Cold rolling stand (2) according to one of claims 1 to 5, characterized in that the sum of the diameters of the smaller work roll (6) and the diameter of the intermediate roll (8) corresponds approximately to the diameter of the large work roll (4).

7. Cold rolling stand (2) according to one of claims 1 to 6, characterized in that the working rolls (4, 6) have a wear and / or corrosion protection layer, preferably a chromium coating.

8. Cold rolling mill (2) according to one of claims 1 to 7, characterized in that at least one intermediate roll (8) is cylindrical; and at least one work roll (6) has a crown, which is preferably arranged positively and / or centrally.

9. Cold rolling stand (2) according to one of claims 1 to 8, characterized in that the smaller working roll (6) and the support roll cooperating therewith are not driven.

10. Cold rolling stand (2) according to one of claims 1 to 9, characterized by at least one, preferably two, strip tensioning devices provided on the inlet side and the outlet side.

11. A method for producing a cold strip (7) with a cold rolling stand (2) according to one of claims 1 to 8, wherein the cold strip undergoes a thickness reduction between two work rolls (4, 6) and work rolls with different diameters are used.

12. Method according to claim 11, characterized in that the thickness of the cold strip (7) is reduced, preferably in one rolling pass, by more than 30%, preferably by more than 35%, preferably more than 40%, particularly preferably by more than 45%.

13. Method according to one of claims 11 or 12, characterized in that the thickness reduction is carried out at a strip exit speed > 1200 m / min, preferably > 2000 m / min.

14. Method according to one of claims 11 to 13, characterized in that the cold strip (7) is reduced in the cold rolling stand (2) in one pass from an initial thickness of 0.13 mm to 0.2 mm to a final thickness of > 0.1 mm.

15. Method according to one of claims 11 to 14, characterized in that during rolling a strip advance is set higher than a strip retraction.

16. Method according to one of claims 11 to 15, characterized in that the rolling force is set to a value which is at least 30%, preferably at least 40%, very particularly preferably at least 50% lower than the required rolling force when using a symmetrical set of rolls with exclusively large rolls (4-hi configuration).

17. Method for changing a roll configuration in a cold rolling stand (2), preferably in cassette construction, from a 4-high configuration with symmetrical working roll diameters to a 5-high configuration with asymmetrical working roll diameters, which is designed to carry out the method according to one of claims 10 to 13, wherein during a configuration change at least one of the working rolls (4) of the cold rolling stand is replaced by a roll arrangement as a replacement set is exchanged, wherein the exchange set comprises at least two exchange rolls which are stored in a common cassette, wherein the upper and lower working rolls (4,6) have a different diameter after the configuration change.

18. The method according to claim 17, characterized in that the sum of the work roll curvatures of the asymmetric work roll configuration corresponds to the sum of the work roll curvatures of the symmetric roll configuration.

19. Method according to one of claims 17 or 18, characterized in that the diameter of the upper and lower 2 Working roll is dimensioned according to the formula Deff = -, where Deff is the effective diameter of the work rolls, Dtop is the diameter of the upper work roll and Dbot is the diameter of the lower work roll.

20. Method according to one of claims 17 to 19, characterized in that in order to change the roll configuration into a 5-high configuration, a drive pin dummy of the exchange set is coupled to a drive of the cold rolling stand.

21. Roll arrangement as an exchange set for carrying out the method according to one of claims 17 to 20, comprising a work roll (6) and an intermediate roll (8) which are mounted in a common cassette, wherein the cassette has intermediate roll chocks (9) whose installation dimensions substantially correspond to those of the work roll chocks of the cold rolling stand in the 4-high configuration.

22. Roll arrangement according to claim 21, characterized in that a drive pin dummy (10) is provided on a work roll chock (9) provided on the drive side, which is designed such that the Working roller (6) of the replacement set is not driven in the installed position.

23. Roller arrangement according to one of claims 21 or 22, characterized by the features of one of claims 3 to 8.

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