A cold roll stand for cold rolling cold strips, a method for manufacturing cold strips, a method for changing the roll configuration in a cold roll stand, and a roll unit used in the said method.

Abstract

The present invention relates to a cold roll stand (2) for cold rolling cold strips, wherein the cold roll stand (2) has upper and lower work rolls (4, 6), and the upper and lower work rolls (4, 6) have different diameters. The present invention further relates to a method for manufacturing cold strips (7) using the cold roll stand (2), and further relates to a method for changing the roll configuration in the cold roll stand (2).

Description

Technical Field

[0001] The present invention relates to a cold rolling stand for cold rolling a cold strip, and a method for manufacturing a cold strip with such a cold rolling stand. The present invention further relates to a method for changing the roll configuration in a cold rolling stand, and a roll unit as an exchange set for implementing the method for changing the roll configuration.

Background Art

[0002] In the field of cold rolling, thinner materials and / or higher-strength materials or materials with overall improved mechanical properties are increasingly being processed. In particular, in the DCR method (double cold rolling) in the tinplate industry, this means manufacturing with a quality of DR9.5 (AISI / ASTM 623) or higher, and further, the final thickness of the strip to be rolled is about 0.1 mm, and the thickness reduction during rolling is reduced to 50% in a single operation.

[0003] In the production of packaging steel, it is generally known to provide tin-plated or electrolytic chromium-plated steel with a thickness of 0.100 to 0.499 mm, with or without an organic coating (lacquer, polymer). For example, after the first cold rolling of a pickled steel sheet, the strip is electrolytically cleaned in a tandem line, put into a furnace for recrystallization annealing, and then carried to one of three two-stage annealing rolling mills to adjust the surface and mechanical properties. In this case, it can be either a low-elongation dry rolling mill or a wet rolling mill with a greater reduction in strip thickness in the first cold rolling stand, a so-called DCR line (double cold rolling). Finally, an electrolytic tin-plating or chromium-plating process follows.

[0004] DCR strips are attractive as packaging materials because they are thin and strong, for example, saving transportation costs and reducing carbon dioxide emissions. Typical applications include screw caps and DRD cans (shallow drawing and redrawing).

[0005] Since alloy steel cannot be used for food and beverage containers, cold work hardening with greater reduction is a preferred method to achieve higher strength. Furthermore, in softer grades, a large reduction in strip thickness by the DCR method is advantageous for forming tabs when stretched. [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide a cold roll stand that enables a significant reduction in thickness, particularly in the manufacture of steel strips with a thickness of up to 0.1 mm.

[0007] A further challenge of the present invention is to achieve such thickness reduction under relatively small rolling forces. [Means for solving the problem]

[0008] This problem is solved by providing a cold roll stand having the features described in claim 1.

[0009] Furthermore, this problem is solved by providing a method for manufacturing cold strips using a cold roll stand according to the present invention.

[0010] Another aspect of the present invention (which is self-protectable) relates to a method for changing the roll configuration in a cold roll stand having a conventional work roll configuration.

[0011] The fundamental problem of the present invention is ultimately solved by providing a roll unit as an interchangeable set for implementing configuration changes.

[0012] Advantageously, the features of the present invention are derived from the dependent claims, respectively.

[0013] A first aspect of the present invention relates to a cold roll stand for cold rolling a cold strip, wherein the cold roll stand has at least an upper and a lower work roll, the upper and lower work rolls having different diameters. The configuration according to the present invention has the advantage that, in particular, in an asymmetrical work roll configuration, by reducing the diameter of one of the work rolls, the thickness of the strip can be reduced by up to 50%, and a relatively thin strip can be achieved. According to the present invention, the strip thickness can be significantly reduced with substantially the same rolling force compared to a symmetrical roll configuration. Preferably, the upper work roll has a smaller diameter than the lower work roll.

[0014] Preferably, formula

number

[0015] This calculation allows for the easy determination of a theoretically symmetrical roll diameter, which can be used as the basis for calculating rolling force and reductions in path scheduling calculations. The operating parameters determined from the path scheduling calculation can then be used to adjust the operating parameters.

[0016] From the perspective of roll gap behavior, the 5-high configuration combines a large, driven lower work roll with numerous much smaller, undriven upper work rolls. The different work roll diameters (approximately 300 mm) and the driving of one of the rolls result in asymmetric rolling conditions. These asymmetric rolling conditions introduce internal shear stress, which accelerates deformation.

[0017] One of the initial technical benefits is a significant reduction in rolling force in 5-high mode compared to 4-high mode. With the same rolling force, a more substantial reduction in strip thickness can be achieved. In successful tests by the applicant, a 50% reduction was achieved. Multiple coils were rolled with a 40-42% reduction, and the maximum strip speed at the exit was 2000 m / min. Flatness control was performed during normal operation, and the quality of strip flatness was within known limits. The thickness control parameters were adjusted based on the low ratio of the difference in rolling force to the difference in reduction.

[0018] To better understand the roll gap behavior in a 5-high configuration with asymmetrical work rolls, it is useful to imagine a hypothetical symmetrical configuration with the same sum of work roll curvatures (reciprocal of work roll radius) as the asymmetrical case. Then, the common work roll diameter, the so-called effective work roll diameter, is given by the following equation

number

[0019] Compared to a 4-high work roll configuration including two work rolls, each with a diameter of 512 mm, the effective work roll diameter of an asymmetrical work roll configuration, where the upper work roll has a diameter of 240 mm and the lower work roll has a diameter of 512 mm, is 327 mm.

[0020] This method allows for the effective rolling of particularly thin strips, which cannot be achieved with 4-high mode. Furthermore, the significant reduction in rolling force results in a substantial reduction in thickness and greater tensile stress, and consequently, energy consumption is also lower with such a work roll configuration.

[0021] The advantages of the present invention can also be achieved in cold roll stands having an asymmetrical work roll configuration in which the lower work roll has a smaller diameter than the upper work roll. Therefore, the embodiments described above are also applicable to such configurations.

[0022] The small work roll is understood to be a work roll having a diameter considerably smaller than that of the large work roll, and even when the large work roll is polished to the maximum extent, the diameter of the small work roll is smaller than that of the large work roll.

[0023] Preferably, the diameter of the small work roll is 120 mm to 380 mm, preferably 180 to 320 mm, and more preferably 200 to 250 mm.

[0024] Preferably, the diameter of the upper work roll is 180 to 320 mm. Further, preferably, the cold roll stand according to the present invention has a 5-high configuration.

[0025] The support roller preferably configured as an intermediate roll supports the small work roll, preferably the upper work roll, and the support roller preferably has a diameter of 180 mm to 520 mm, preferably 250 mm to 450 mm, and more preferably 280 to 300 mm.

[0026] Preferably, the sum of the diameters of the small work roll and the support roller is approximately equal to the diameter of the large work roll.

[0027] Preferably, the small work roll and the intermediate roll are attached to roller bearings and lubricated by an oil-air lubrication method. Oil-air lubrication is particularly advantageous in the case of high strip speeds.

[0028] In the case of a preferred embodiment of the cold roll stand according to the present invention, the work roll may be contemplated to be provided with a hard coating, preferably a chromium coating, as an anti-wear layer and / or a corrosion prevention layer. The chromium-plated roll particularly has wear resistance and enables rolling with a small surface roughness.

[0029] Preferably, at least one intermediate roll is cylindrical in shape, and at least one work roll has a preferably positive and / or preferably centrally located curvature. The preferred positive curvature of the work roll allows adjustment to a target deflection curve and contributes to improving the flatness of the strip as an actuator for controlling flatness.

[0030] In the five-high configuration of the cold roll stand according to the present invention, preferably, the smaller work rolls, preferably the upper work rolls, and the associated intermediate rolls, preferably the upper intermediate rolls, are configured not to be driven. The terms "upper" and "lower" basically refer to the mounting positions.

[0031] In a preferred modification of the cold roll stand according to the present invention, one strip tension adjuster can be placed on both the inlet and outlet sides of the roll.

[0032] The strip tension adjustment device may be a winding and / or unwinding reel and / or a special pulley or spreading device. The strip tension adjustment device allows for target adjustment of the strip feed and retraction, as well as the strip speed deviating from the roll's peripheral speed. This is important for adjusting the roll gap geometry and can yield advantageous effects within the scope of the invention.

[0033] Another aspect of the present invention relates to a method for producing a cold strip equipped with a cold roll stand of the type described above, having one or more of the features described above. The method includes an asymmetrical work roll configuration or a reduction in the thickness of the cold-rolled strip between two work rolls having different diameters.

[0034] Advantageous modifications of the method according to the present invention are intended to reduce the thickness of the cold strip by 30% or more, preferably 35% or more, preferably 40% or more, and particularly preferably 45% or more, in a single rolling pass or single strip pass.

[0035] Thickness reduction or thickness reduction can be carried out at a strip pass speed of 1200 m / min or more, preferably 2000 m / min or more.

[0036] Preferably, during rolling, the strip tension adjustment device adjusts the strip feed rate to be higher than the strip retraction rate.

[0037] In a preferred modification of the method according to the present invention, the rolling force is adjusted to a value at least about 30%, preferably at least about 40%, or preferably particularly at least about 50%, lower than the rolling force required when using a symmetrical roll set comprising only large rolls (4-high configuration).

[0038] Particularly preferable is the ability to reduce a cold-rolled strap, initially with a thickness of 0.13 mm to 0.2 mm, to a final thickness of 0.1 mm or more in a single pass, using a cold-rolled stand. This is primarily due to the fact that, compared to the aforementioned asymmetrical work roll configuration, a thickness reduction of up to 50% can be achieved with the same rolling force. In this configuration, each work roll has a diameter corresponding to the diameter of the largest work roll in the asymmetrical work roll configuration according to the present invention.

[0039] Preferably, the thickness reduction by the method according to the present invention is carried out at an exit stripping speed of 1200 m / min or more, preferably 2000 m / min or more.

[0040] Another (self-protectable) aspect of the present invention is a method for changing the roll configuration from a 4-high configuration having symmetrical work roll diameters to a 5-high configuration having asymmetrical work roll diameters in a cold roll stand, preferably a cassette type, configured to carry out a method according to the present invention, wherein in the case of configuration change, at least one of the work rolls of the cold roll stand is replaced by a roll unit as a replacement set, wherein the replacement set comprises at least two replacement rolls supported on a common cassette, wherein the upper and lower work rolls have different diameters after the configuration change. This method makes it possible to replace a conventional 4-high configuration in a particularly advantageous and simple manner, so that a significant reduction in the thickness of the cold strip can be achieved with substantially the same rolling force.

[0041] Preferably, the sum of the work roll curvatures in the asymmetrical work roll configuration is equal to the sum of the work roll curvatures in the symmetrical roll configuration.

[0042] In an advantageous modification of the method, the diameters of the upper and lower work rolls are given by the formula

number

[0043] Preferably, a method for changing the roll configuration includes using a roll quick change device to replace the replacement set during a stop of less than 15 minutes, preferably less than 12 minutes, more preferably less than 7 minutes, and most preferably less than 5 minutes.

[0044] Preferably, roll changes are performed in 4-high mode using the same quick change device as in 5-high mode. Finally, another viewpoint relates to a roll unit as an exchange set for carrying out the above method for changing the roll configuration, comprising work rolls and intermediate rolls supported on a common cassette, wherein the cassette includes mounting pieces for the intermediate rolls, and the mounting dimensions of the intermediate roll mounting pieces substantially coincide with the mounting dimensions of the work roll mounting pieces of the cold roll stand in the 4-high configuration.

[0045] In such a modified 5-high configuration, in order to ensure that the upper work roll and the upper support roll are not driven, a drive journal dummy may be provided on the work roll mounting piece on the drive side, and the drive journal dummy may be configured so that the work roll of the replacement set is not driven in the mounting position.

[0046] The present invention will be described below with respect to embodiments specifically shown in the drawings. [Brief explanation of the drawing]

[0047] [Figure 1] Figure 1 shows a schematic diagram of a cold rolling mill equipped with a cold roll stand according to the present invention. [Figure 2] As an exploded view of the individual components of the change cassette, a schematic diagram of the configuration of the roll unit according to the present invention in the form of a change cassette is shown. [Figure 3] This shows a schematic comparison between a conventional 4-high configuration and a 5-high configuration according to the present invention. [Figure 4] This graph shows the distributed load of rolled material in cold rolling with a 5-high configuration compared to coils rolled with a conventional 4-high configuration. [Figure 5] This graph shows steady-state FEM solutions for asymmetric and equivalent symmetric work roll configurations, based on measurement data for steel grade DR8 and strip geometry of 960mm × 0.244 -> 0.142mm. [Figure 6]This example shows a calculation of the reduction in rolling force and energy consumption of the main drive unit of the cold roll stand in 5-high mode according to the present invention, compared to the conventional 4-high mode, based on the measured rolling force of steel grade DR8 and strip geometry of 960 mm x 0.244 mm -> 0.142 mm. [Figure 7] This graph shows the height measurements of the 3D profile of the work roll surface before and after rolling four coils using the 5-high configuration according to the present invention, using a confocal microscope. [Figure 7a] A diagram corresponding to Figure 7 is shown. [Modes for carrying out the invention]

[0048] The cold rolling mill 1 shown in Figure 1 consists of first and second cold roll stands 2 and 3, each with four high work rolls with a work roll diameter of 563 / 505 mm. The reason one of the two work rolls 4 has a smaller diameter is that the work roll 4 has reached the end of its service life due to wear.

[0049] The first cold roll stand 2 reduces the thickness of the cold strip 7 (typically by 8-32%) through thickness control (thickness reduction), while the second cold roll stand 3 is configured as a dressing machine that improves the strip surface (with almost no elongation) through force control. The first cold roll stand 2 is driven by the work roll drive of the comb roll, while in the second cold roll stand 3 only the lower work roll 4 is driven. The maximum strip discharge speed is 2000 m / min or more.

[0050] The cold rolling mill is equipped with a strip tensioning device that allows for precise adjustment of the strip's feed-out and retraction.

[0051] If the conditions for roll gap lubrication and strip tension are already adequate or at maximum operational levels, reducing the work roll diameter is the most efficient way to achieve significant reductions (up to 50%) and thinner strips (minimum final strip thickness of 0.1 mm) in such rolling mills. For existing rolling mills, this usually means a major overhaul.

[0052] One aspect of the present invention relates to modifying the cold roll stand 2 so that an asymmetrical work roll configuration can be realized. For this purpose, the invention aims to provide a modification cassette 5, for example, as schematically shown in Figure 2.

[0053] The modification cassette 5 according to the present invention is configured to at least temporarily replace the upper work roll 4 of the first cold roll stand 2 in order to change from a 4-high configuration to a 5-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 larger work roll 4 that is normally used, and as a result no additional means for height adjustment are required. The geometry of the outer mounting piece of the modification cassette 5 precisely corresponds to the dimensions of the larger work roll 4, and as a result, the operation of changing from 4-high mode to 5-high mode and vice versa is as quick and easy as a normal work roll change.

[0054] The mounting piece 9 of the intermediate roll has an effective surface so that the bending force is transmitted to the intermediate roll 8. Positive and negative bending forces can be used, but in tests conducted by the applicant, the value was limited to half in order to avoid overloading the bearing of the intermediate roll 8. Because the diameter of the intermediate roll 8 is small compared to the larger (lower) work roll 4, the bending is still effective.

[0055] The mounting piece of the upper, smaller work roll 6 is integrated within the mounting piece 9 of the intermediate roll 8 (mounting piece in the mounting piece structure) and can slide freely in the vertical direction. Therefore, only horizontal forces are transmitted to the work roll 6, and bending forces are not transmitted to the work roll 6.

[0056] In the above embodiment, the intermediate roll 8 of the change cassette 5 is cylindrical, while the work roll 6 has a positive curvature calculated to satisfy the flatness target within the range of bending force. The flatness adjuster for the first cold roll stand 2 functions without modification, using a flatness measuring roller that detects flatness across the stand.

[0057] On the drive side of the second cold roll stand 2, a drive journal dummy 10 for housing the upper drive spindle is attached to the mounting piece 9 of the change cassette 5. The drive journal dummy 10 includes a free-traveling double ball bearing that is not further connected to the roll. That is, all the main drive torque is transmitted to the original lower work roll 4, while the upper intermediate roll 8 and the upper work roll 6 are not driven. This configuration has the advantage that there is no need to change the gear ratio or direction of rotation.

[0058] The 5-high configuration according to the present invention combines a large, driven lower work roll 4 with a much smaller, undriven work roll 6. The different work roll diameters (approximately 300 mm) and individual drives result in asymmetrical rolling conditions.

[0059] Figure 4 shows the reduction in rolling force in 5-high mode compared to 4-high mode. With the same rolling force, the strip thickness can be significantly reduced compared to the 4-high configuration.

[0060] Figure 5 shows the roll gap behavior in 5-high operation (left configuration) compared to a hypothetical symmetrical configuration (right configuration) having the same sum of work roll curvatures (reciprocal of work roll radius) as in the asymmetric case. Next, the common work roll diameter, the so-called effective work roll diameter, is given by the following equation

number

[0061] For example, in several tests conducted by the applicant, when a new, smaller upper work roll 6 (diameter Dtop = 240 mm) is connected to the larger lower work roll 4 (diameter Dbot = 512 mm) that is in use, this formula shows that the effective diameter is approximately 327 mm.

[0062] The pressure distribution within the roll gap, calculated using a proprietary fixed (viscoplastic) finite element algorithm, is nearly identical for both the symmetric and actual asymmetric cases (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 lengths are the same, and only in the region of maximum pressure is the so-called pressure peak flattened in the asymmetric solution compared to the symmetric case, which results in a slightly lower rolling force. Because the difference is small and the effective work roll diameter is used, the calculation of the pass schedule using the standard program yields good results with respect to the rolling force.

[0063] Regarding forward slip, the solutions differ. Since only the lower work roll 4 is driven, its peripheral speed is faster than that of the upper work roll 6, which is not driven (Figure 5, right side). The strip output speed, compared to the peripheral speed of the lower work roll 4, which is directly related to the forward slip value registered and displayed by the automated system, is smaller in the asymmetric solution than in the symmetric solution.

[0064] The measured lead (5.7%) is quite close to the asymmetrically calculated lead (5.2%). In general, care must be taken to ensure that the driven rolls do not slip on the strip. The measurements and calculations show that, for thin strips, the height is sufficient to reliably ensure the strip feed. This situation is further improved if the feed of a particular strip is higher than the retraction of the strip. This is typically the case for the first cold roll stand of a DCR rolling mill.

[0065] The reduction in rolling force achieved in the 5-high mode compared to the 4-high mode according to the present invention is advantageous when rolling thin strips where the thickness reduction is large and therefore the tensile stress is high. However, when considering energy saving, it should be noted that the rolling force itself does not consume any energy. However, this has two related effects. On the one hand, the bearing friction loss of the upper support roll is reduced, and on the other hand, the roll gap length is shortened, and therefore the driving torque is reduced due to the reduced friction loss from the relative motion between the strip and the work roll 6.

[0066] Figure 6 shows the potential for energy savings in the main drive unit of the cold roll stand 2 in the embodiment described above. The following assumptions were made: a constant (extremely low) support roll bearing friction coefficient μ = 0.001, a constant roll gap friction coefficient, no roll contact at the strip edge, and a constant strip discharge speed (same productivity). Overall, a saving of approximately 10% of the main drive power is realistic.

[0067] The difference in diameter between the smaller work roll 6 in the 5-high mode modified cassette 5 and the normal work roll 4 in the 4-high mode is 2.1 to 2.56 times. This ratio increases the number of rotations per strip length on the smaller work roll 6, which results in higher wear. On the other hand, the rolling force is significantly lower, which is associated with less wear. To grasp the scale, in the embodiment described in the previous paragraph, the maximum pressure in the roll gap is reduced from approximately 2100 MPa in the 4-high mode to approximately 1100 MPa in the 5-high mode (Figure 5, center).

[0068] Another aspect is the difference between the upper and lower work rolls and the change in strip surface roughness in the 5 high mode itself. With respect to wear, the larger lower work roll 4 is expected to benefit in two ways: firstly, its larger diameter and therefore larger surface area; and secondly, its lower Hertz pressure in contact with the support roll compared to the smaller upper work roll 6 in contact with the intermediate roll 8.

[0069] For the final test campaign using four coils in 5 high mode, both work rolls 4 and 6 were newly polished and chrome-plated. The 3D surface roughness before and after rolling showed only slight differences for both rolls (Figure 7). The Ra value (arithmetic mean roughness) remained similar within the statistical limits. Clearly, the roll gap pressure and the resulting rolling force were very small, so there was no significant wear effect on the chrome-plated rolls. The Rp value (peak height of the maximum profile in the roughness profile) decreased simultaneously on both rolls, reflecting the known flattening of surface irregularities caused by the initial contact between the strip and the other rolls. No statistically significant difference was found in strip roughness between the upper and lower sides. [Explanation of symbols]

[0070] 1. Cold rolling mill 2. First cold roll stand 3. Second cold roll stand 4 Work Roles 5. Change Cassette 6. Small upper work roll with 5 high configuration 7 Cold strip 8. Upper intermediate roll in a 5-high configuration. 9. Mounting piece for the replacement cassette 10 Drive Journal Dummy

Claims

1. A cold roll stand (2) for cold rolling cold strips, The cold roll stand (2) has upper and lower work rolls (4, 6), The upper and lower work rolls (4, 6) have different diameters. Cold rolling stand (2).

2. The diameters of the upper and lower work rolls are given by the formula: [Math 1] The dimensions are determined by Def is the effective diameter of the work roll, Dtop is the diameter of the upper work roll, and Dbot is the diameter of the lower work roll. The cold roll stand (2) according to feature 1.

3. The cold roll stand (2) according to claim 1 or 2, characterized in that the diameter of the small work roll (6) is 120 mm to 380 mm, preferably 180 to 320 mm, and more preferably 200 to 250 mm.

4. The cold roll stand (2) according to any one of claims 1 to 3, characterized in that the cold roll stand (2) is configured with five high sections.

5. Preferably, at least one support roller configured as an intermediate roll (8) supports a small work roll (6), The support roller has a diameter of 180 mm to 520 mm, preferably 250 mm to 450 mm, and more preferably 280 mm to 300 mm. A cold roll stand (2) according to any one of claims 1 to 4.

6. A cold roll stand (2) according to any one of claims 1 to 5, characterized in that the sum of the diameter of the small work roll (6) and the diameter of the intermediate roll (8) is approximately equal to the diameter of the large work roll (4).

7. The cold roll stand (2) according to any one of claims 1 to 6, characterized in that the work rolls (4, 6) have an abrasion-preventing layer and / or a corrosion-preventing layer, preferably a chrome coating.

8. A cold roll stand (2) according to any 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 curvature preferably positive and / or centrally positioned.

9. A cold roll stand (2) according to any one of claims 1 to 8, characterized in that a small work roll (6) and the support roller acting together with the small work roll (6) are not driven.

10. A cold roll stand (2) according to any one of claims 1 to 9, characterized by two strip tensioning devices, at least one of which is preferably provided on the inlet side and the other on the outlet side.

11. A method for manufacturing a cold strip (7) using a cold roll stand (2) according to any one of claims 1 to 8, The cold strip undergoes thickness reduction between two work rolls (4, 6), and work rolls having different diameters are used. method.

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

13. The method according to claim 11 or 12, characterized in that the thickness reduction is carried out at a strap discharge rate of 1200 m / min or more, preferably 2000 m / min or more.

14. The method according to any one of claims 11 to 13, characterized in that, in the cold roll stand (2), the cold strip (7), which has an initial thickness of 0.13 mm to 0.2 mm, is reduced to a final thickness of 0.1 mm or more in a single process.

15. The method according to any one of claims 11 to 14, characterized in that, during rolling, the feed rate of the strip is adjusted to be higher than the pull-in rate of the strip.

16. The method according to any one of claims 11 to 15, characterized in that the rolling force is adjusted to a value at least about 30%, preferably at least about 40%, or particularly preferably about 50%, lower than the rolling force required when using a symmetrical roll set having exclusively large rolls (four-high configuration).

17. A method for changing the roll configuration from a 4-high configuration having symmetrical work roll diameters to a 5-high configuration having asymmetrical work roll diameters in a cold roll stand (2) (2) configured to carry out the method according to any one of claims 10 to 13, In the event of a configuration change, at least one of the work rolls (4) of the cold roll stand is replaced by a roll unit as part of a replacement set. The aforementioned replacement set comprises at least two replacement rolls supported by a common cassette, The upper and lower work rolls (4, 6) have different diameters after the configuration change. A method characterized by the following:

18. The method according to claim 17, characterized in that the sum of the work roll curvatures of an asymmetrical work roll configuration is equal to the sum of the work roll curvatures of a symmetrical roll configuration.

19. The diameters of the upper and lower work rolls are given by the formula: [Math 2] The dimensions are determined by Def is the effective diameter of the work roll, Dtop is the diameter of the upper work roll, and Dbot is the diameter of the lower work roll. The method according to 17 or 18, characterized by the features described herein.

20. The method according to any one of claims 17 to 19, characterized in that a drive journal dummy of the replacement set is connected to the drive device of the cold roll stand in order to change the roll configuration to a 5-high configuration.

21. A roll unit as an interchangeable set for carrying out the method of any one of claims 17 to 20, comprising a work roll (6) and an intermediate roll (8) supported by a common cassette, The cassette is provided with an intermediate roll mounting piece (9), and the mounting dimensions of the intermediate roll mounting piece (9) substantially match those of the work roll mounting piece of the cold roll stand in the 4-high configuration. A roll unit characterized by the following features.

22. A drive journal dummy (10) is provided on the work roll mounting piece (9) on the drive side, and the drive journal dummy (10) is configured so that the work roll (6) of the replacement set is not driven in the mounting position. The roll unit according to feature 21.

23. The roll unit according to claim 21 or 22, characterized by the features described in any one of claims 3 to 8.

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