Set of tensioning rollers for straightening a strip, straightening plant, skinpass frame assembly and method for operating a straightening plant

Abstract

Tensioning roller set (3, 4) for a straightening machine (1) for straightening a strip (2) or for a finishing rolling stand for re-rolling a strip, wherein the tensioning roller set (3, 4) comprises: • a first tensioning roller (8) with a first roller axis and • at least one second tensioning roller (9) with a second roller axis, wherein the first tensioning roller (8) is a flatness measuring roller having a force sensor for measuring a radial force exerted on the circumferential surface of the flatness measuring roller, and a drive is provided for the second tensioning roller (9) with which a torque about the second roller axis can be applied to the second tensioning roller (9), wherein: • either the first tensioning roller (8) is designed without a drive; • or an auxiliary drive is provided for the first tensioning roller with which a torque about the first roller axis can be applied to the first tensioning roller, wherein the auxiliary drive for the first tensioning roller is designed to be less powerful than the drive for the second tensioning roller.

Description

[0001] The invention relates to a tension roller set for a straightening system for straightening a strip. Furthermore, the invention relates to a straightening system for straightening a strip. Furthermore, the invention relates to a temper rolling stand for temper rolling a strip. Furthermore, the invention relates to a method for operating a straightening system or a temper rolling stand.

[0002] Increasingly stringent demands are being placed on the quality of products and semi-finished products made from sheet and strip material. Various customers require sheet products that are subject to very tight tolerances for both aesthetic and process-related reasons. A key quality feature of sheet products is their flatness. Due to various influences, this flatness requirement is very often not met during rolling. To eliminate this non-flatness, strip straightening processes are therefore used subsequently. Length compensation is achieved by plastically stretching the shorter strip sections. This can eliminate, for example, center or edge waves. The strip sections, which were of different lengths and therefore partially wavy before the straightening process, are plastically stretched to different degrees.

[0003] Continuously operating straightening processes are regularly used for strip straightening, which are differentiated according to their mode of operation into stretch-bend straightening, tensile stretching, or a combination of tensile stretching and stretch-bend straightening. All three have in common that they an inlet tension roller set in which the strip tension is increased compared to the strip tension in the line, a stretching zone or a stretch-bending stand and an outlet tension roller set in which the strip tension is reduced back to the level of the line, have.

[0004] In order to optimally adjust the stretching zone and / or the bending frame, it is necessary to continuously measure the flatness of the strip.

[0005] In the stretching zone, or before or after the bending stand, very cramped installation conditions typically prevail. Likewise, cramped installation conditions prevail between the discharge tension roller set and, for example, a take-up reel.

[0006] From EP 1 789 211 B1 a strip treatment system with a pair of tensioning rollers is known, in which the strip is guided over a tensioning roller of the pair of tensioning rollers and the strip tension is increased or reduced by the tensioning roller between the inlet onto the tensioning roller and the outlet from the tensioning roller, wherein the tensioning roller has at least one measuring sensor arranged on the circumference of the tensioning roller for detecting the tension distribution in the strip.

[0007] DE 10 2018 111 627 A1 discloses a stretch-bend-leveling system with a feed means for feeding a strip-shaped material along a running direction into a high-tension zone and a low-tension zone, wherein the low-tension zone is arranged downstream of the high-tension zone in the running direction. The known stretch-bend-leveling system includes a bend-straightening unit arranged in the high-tension zone. Furthermore, at least one measuring system for determining a first measured value in the high-tension zone is known. It is also provided that at least one measuring system for determining a second measured value is additionally provided in the low-tension zone.

[0008] GB 1 409 025 discloses a tension roller set for straightening a belt with two upper rollers and two lower rollers.

[0009] Against this background, the object of the invention was to propose a tension roller set for a straightening system for straightening a strip or for a tempering stand for tempering a strip, the use of which in a straightening system enables straightening of the strip or the use of which in a tempering stand enables tempering to be carried out more effectively.

[0010] This object is achieved by the tension roller set according to claim 1, by the straightening system according to claim 8, the tempering stand system according to claim 10 and the methods according to claim 11, 12 or 13. Advantageous embodiments are provided in the subclaims and the description below.

[0011] The invention is based on the basic idea of ​​designing a tensioning roller of the tensioning roller set, as proposed in EP 1 789 211 B1, as a flatness measuring roller, wherein the tensioning roller set is further developed according to the invention in such a way that a drive is provided for the second tensioning roller with which a torque about the second roller axis can be applied to the second tensioning roller, but according to the invention the first tensioning roller is designed without a drive.

[0012] It has been shown that in tension rollers equipped with drives, the drive often delivers the required torque only one-sidedly via the tension roller's bearing journal. When the strip tension is applied, the torque applied to the tension roller via the drive counteracts the strip retraction, resulting in the tension roller body and any coating material present being deformed or twisted in the elastic range. Such deformation of the tension roller body and any coating material present can falsify the force sensor's measurement.

[0013] By designing the first tension roller, which is designed as a flatness measuring roller, without a drive, this measurement error can be avoided or reduced. As a result, when such a tension roller set is used in a leveling system, the strip can be leveled more effectively because the measurement results of the flatness measuring roller are better. Likewise, when such a tension roller set is used in a tempering stand, the strip can be tempered more effectively because the measurement results of the flatness measuring roller are better.

[0014] The invention is directed to a tension roller set for a straightening system for straightening a strip. It is expected that the advantages of the invention will already be achieved with a roller set comprising only a first tension roller and a second tension roller. However, according to the invention, the tension roller set preferably comprises a first tension roller, a second tension roller, and a third tension roller, particularly preferably further comprising a fourth tension roller, even more preferably further comprising a fifth tension roller, and most preferably further comprising a sixth tension roller.

[0015] As also proposed in EP 1 789 221 B1, the first tension roller is a flatness measuring roller having a force sensor for measuring a radial force exerted on the circumferential surface of the flatness measuring roller.

[0016] Embodiments are conceivable in which the tension roller set comprises multiple flatness measuring rollers, as described, for example, in DE 10 2019 006 788. In a preferred embodiment, however, the tension roller set comprises only a single flatness measuring roller. By limiting the number of flatness measuring rollers within the tension roller set, the complexity of the tension roller set can be reduced.

[0017] The flatness measuring roller can be designed in the manner of the measuring roller described in DE 42 36 657 A1, or in the manner of the measuring roller described in DE 196 16 980 A1, or in the manner of the measuring roller described in DE 102 07 501 C1, or in the manner of the measuring roller described in DE 20 2007 001 066 U1, or in the manner of the measuring roller described in EP 1 469 955 B1. Furthermore, the measuring roller can be designed in the manner of the measuring roller described in WO2020 / 120328 A1 or in the manner of the measuring roller described in WO2020 / 120329 A1.

[0018] The measuring roller has a measuring roller body. The measuring roller body preferably has a closed circumferential surface. In a preferred embodiment, the measuring roller body is a solid roller that extends along a longitudinal axis. A solid roller is understood to be a measuring roller body that is one-piece and whose shape was either produced using a primary forming process, for example casting, and / or whose geometric shape is produced from a one-piece semi-finished product by separating processes, in particular by machining, in particular by turning, drilling, milling or grinding. In a preferred embodiment, in such a measuring roller body designed as a solid roller, the measuring roller journals arranged on the front side of the measuring roller for rotatably supporting the measuring roller, for example in ball bearings, are also part of the one-piece body. However, designs such as those described, for example, Fig. 2DE 20 2014 006 820 U1, in which the main part of the measuring roller body is designed as a cylindrical solid roller, which has covers arranged on the front side, on which the measuring roller pins are formed. Furthermore, the measuring roller body can, for example, be like the one shown in Fig. 3 The measuring roller body can be designed as described in DE 20 2014 006 820 U1, in which the measuring roller body is formed with integrally formed pins and a casing tube is pushed over the measuring roller body. In a particularly preferred embodiment, however, the measuring roller does not have a casing tube, but is designed as a solid roller. Embodiments are conceivable in which the measuring roller body is formed from individual discs arranged side by side, as shown, for example, in DE 26 30 410 C2.

[0019] The measuring roller body of the measuring roller preferably has a closed circumferential surface. This can be achieved, for example, by designing the measuring roller body as a solid roller and forming all recesses provided in the measuring roller body such that no recess leads from the recess to the circumferential surface. In such an embodiment, the recesses are particularly preferably guided axially and have an opening on an end face of the measuring roller body, or transverse channels are provided within the measuring roller body, which lead radially from the recess further into the interior of the measuring roller body, for example, to a collecting channel in the center of the measuring roller body.A closed circumferential surface of the measuring roller body can also be achieved by closing the respective recess with a closure element in embodiments in which the recess extends toward the circumferential surface. Such a closure element can be a casing tube that completely surrounds a base body of the measuring roller body, as shown, for example, in the . Fig. 3and 4 of DE 10 2014 012 426 A1. However, the closure element can also be designed in the manner of the cover shown in DE 197 47 655 A1. In a preferred embodiment, however, the measuring roller does not have a casing tube, but is designed as a solid roller, either as one in which no recess leads from the recess to the circumferential surface, or as one in which the respective recess is a recess leading in the direction of the circumferential surface, but which is closed by a closure element, such as a cover. In addition, coatings, for example of the circumferential surface of a solid roller or the circumferential surface of a casing tube, are conceivable, for example to reduce friction or to protect the strip-shaped material to be guided over the measuring roller.

[0020] At least one recess is provided in the measuring roller body of the measuring roller. It has been shown that the advantages of the invention can be achieved with just a single recess in the measuring roller body. Thus, for flatness measurements, it is conceivable to provide information about the flatness of the strip-shaped material guided over the measuring roller once per revolution of the measuring roller.

[0021] In a preferred embodiment, the measuring roller body has a plurality of recesses. In a preferred embodiment, the recesses are designed at the same radial distance from the longitudinal axis of the measuring roller body. In a preferred embodiment, all recesses are arranged equidistant from one another in the circumferential direction. However, embodiments are also conceivable in which a first group of recesses is provided, which are particularly preferably arranged at the same radial distance from the longitudinal axis and equidistantly distributed in the circumferential direction, and in which, in addition to this first group of recesses, at least one further recess is provided, which is either designed differently than the recesses in the first group with regard to its radial distance from the longitudinal axis and / or does not have the same distance in the circumferential direction from the other recesses as the other recesses have from one another.For example, it is conceivable to design a measuring roller with regard to flatness measurement in the same way as a prior art measuring roller, for example like the solid roller known from DE 102 07 501 or the measuring rollers known from DE 10 2014 012 426 A1, but then to provide these prior art measuring rollers with an additional recess outside the grid for further equipment, with which, for example, a different measurement is carried out. The recesses mentioned in this paragraph are preferably those that run in the axial direction of the measuring roller body. Embodiments are also conceivable in which the measuring roller has a single recess and all force sensors of the measuring roller are arranged in a single recess, for example in a single axially running recess.

[0022] In a preferred embodiment, the measuring roller body has a closed circumferential surface and is closed off at each end by a front face. In a preferred embodiment, the front faces are arranged at an angle of 90° to the circumferential surface.

[0023] In a preferred embodiment, the measuring roller has bearing journals. In a preferred embodiment, in embodiments of the measuring roller with end faces, the bearing journals are formed on the end faces.

[0024] In a preferred embodiment, the measuring roller body is cylindrical.

[0025] In a preferred embodiment, the measuring roller is designed with at least one recess in the measuring roller body, which is arranged at a distance from the circumferential surface, wherein the recess does not open towards the circumferential surface, or no further recess leading from the recess, for example no bore, leads to the circumferential surface. In an alternative preferred embodiment, the recess leads from the circumferential surface into the interior of the measuring roller body, but is closed by a closure element. In a preferred embodiment, in the embodiments in which the measuring roller is designed with several recesses in the measuring roller body, which are arranged at a distance from the circumferential surfaces, either all recesses are designed in such a way that no recess, e.g.no bore leads from the recess to the peripheral surface (and the recess itself does not open into the peripheral surface either), or some recesses are designed such that no recess leads from the respective recess to the peripheral surface, while other recesses have a recess leading toward the peripheral surface, but which is closed by a closure element. The closure element is - as explained above - a cover or, for example, a casing pipe.

[0026] In a preferred embodiment, a recess in the measuring roller body extends in a direction parallel to the longitudinal axis of the measuring roller body. If, according to a preferred embodiment, several recesses are provided in the measuring roller body, it is preferred that all recesses of the measuring roller body each extend in a direction parallel to the longitudinal axis of the measuring roller body. In a preferred embodiment, the respective recess opens at least at one of its ends, preferably at both of its ends, onto an end face of the measuring roller body. A recess ending at an end face of a measuring roller body can be closed by an end cap, wherein this end cap only closes this recess. Embodiments are also conceivable in which the end face of the measuring roller body is completely closed by a cover, as for example in Fig. 1 and 2 , or Fig. 4 of DE 10 2014 012 426 A1.

[0027] In a preferred embodiment, the recess is elongated, where "elongated" means that the recess is larger in a first direction (the longitudinal direction of the recess) than in any direction perpendicular to this direction. In a preferred embodiment, the extension of the elongated recess in the longitudinal direction is twice, or particularly preferably more than twice, larger than in any direction perpendicular to this direction. In a preferred embodiment, the longitudinal direction of the recess forms an angle with the longitudinal direction of the measuring roller body that is less than 75°, particularly preferably <45°, particularly preferably <30°, particularly preferably <10°, particularly preferably <5°. In a preferred embodiment, the longitudinal direction of the recess is not perpendicular to the longitudinal axis of the measuring roller body.Should the longitudinal axis of the recess and the longitudinal axis of the measuring roller body not intersect—which would be conceivable in one embodiment—the aforementioned design rule applies to the projection of the longitudinal axis of the recess onto the plane containing the longitudinal axis of the measuring roller body. In these embodiments, the projection of the longitudinal axis of the recess onto a plane containing the longitudinal axis of the measuring roller body is accordingly designed such that the projection of the longitudinal direction of the recess encloses an angle with the longitudinal direction of the measuring roller body that is less than 75°, particularly preferably <45°, particularly preferably <30°, particularly preferably <10°, particularly preferably <5°.In the preferred embodiments in which the recess extends parallel to the longitudinal axis of the measuring roller body, the longitudinal axis of the recess obviously does not intersect the longitudinal axis of the measuring roller body, just as a projection of the longitudinal axis onto a plane containing the longitudinal axis of the measuring roller body does not intersect the longitudinal axis of the measuring roller body. For example, DE 20 2007 001 066 U1 shows a measuring roller with elongated recesses.

[0028] In a preferred embodiment, the flatness measuring roller has an axial bore running parallel to the first roller axis, with the force sensor arranged in the axial bore. According to the invention, the flatness measuring roller is no longer influenced, or only slightly influenced, by torsional forces. This also allows roller designs to be used in which the sensors are installed not only in radial bores, but also in axial bores, as described, for example, in EP 1 469 955 A1.

[0029] In a preferred embodiment, the flatness measuring roller has a surface coating. Particularly preferably, the flatness measuring roller has a coating of tungsten carbide or chromium. The surface coating can also be implemented as a rubber or polyurethane coating.

[0030] This description refers to a first tension pulley and a second tension pulley, and in the context of preferred embodiments, to a third tension pulley, a fourth tension pulley, and sometimes even a fifth and sixth tension pulley of a tension pulley set. The use of the ordinal numbers "first," "second," "third," "fourth," "fifth," and "sixth" does not necessarily mean, but only in a preferred embodiment, that the belt passing through the tension pulley set is guided over the existing tension pulleys in the order of their ordinal numbers, i.e., first over the first tension pulley and then over the second tension pulley, etc.The invention is initially based on the recognition that within a tension roller set, a tension roller with a drive is provided (the so-called "second tension roller") and, in addition, a flatness measuring roller referred to as the "first tension roller," which is either driveless or equipped with an auxiliary drive. The invention does not initially specify the spatial position of the first tension roller and the second tension roller relative to one another. To achieve the advantages of the invention, it is not absolutely necessary for the flatness measuring roller (the "first tension roller") to be the first tension roller over which the belt runs when the belt enters the tension roller set. To achieve the advantages of the invention, it is also not absolutely necessary for the "second tension roller" to be the tension roller immediately downstream of the flatness measuring roller (the "first tension roller") in the belt travel direction.Thus, embodiments are also conceivable in which the flatness measuring roller (the "first tension roller") is the last tension roller of a tension roller set or a tension roller arranged between the frontmost tension roller and the last tension roller of a tension roller set. Likewise, embodiments are conceivable in which additional tension rollers, possibly driven but also possibly non-driven, are provided between the flatness measuring roller (the "first tension roller") and the driven, second tension roller.

[0031] In a preferred embodiment, however, the second tensioning roller is the tensioning roller of the tensioning roller set over which the strip is guided after it leaves the first tensioning roller designed as a flatness measuring roller. In a very particularly preferred embodiment, the first tensioning roller designed as a flatness measuring roller is the tensioning roller of the tensioning roller set onto which the strip first runs when it enters the tensioning roller set. In a preferred embodiment in which a third tensioning roller is provided, this third tensioning roller is arranged downstream of the second tensioning roller in the strip running direction, particularly preferably directly downstream. In a preferred embodiment in which a fourth tensioning roller is provided, this fourth tensioning roller is arranged downstream of the third tensioning roller in the strip running direction, particularly preferably directly downstream.In a preferred embodiment in which a fifth tensioning roller is provided, this fifth tensioning roller is arranged downstream of the fourth tensioning roller in the belt travel direction, particularly preferably directly downstream. In a preferred embodiment in which a sixth tensioning roller is provided, this sixth tensioning roller is arranged downstream of the fifth tensioning roller in the belt travel direction, particularly preferably directly downstream.

[0032] The preferred arrangement of the individual tension rollers described in the previous paragraph is particularly well suited for embodiments in which the tension roller set according to the invention is to be arranged downstream of a stretching zone or a bending stand, and there is a desire to document the flatness quality with which the strip leaves the stretching zone or bending stand. This preferred arrangement is also suitable for a tension roller set arranged downstream of a decoiler, and there is a desire to document the flatness quality with which the strip leaves the coiler.

[0033] In a preferred, alternative embodiment, however, the first tensioning roller designed as a flatness measuring roller is the tensioning roller of the tensioning roller set over which the strip is guided after it leaves the second tensioning roller. In a particularly preferred embodiment, the first tensioning roller designed as a flatness measuring roller is the tensioning roller of the tensioning roller set from which the strip runs last when it runs out of the tensioning roller set. In this preferred embodiment, the first tensioning roller designed as a flatness measuring roller is therefore the last tensioning roller of the tensioning roller set. In a preferred embodiment in which a third tensioning roller is provided, this third tensioning roller is arranged upstream of the second tensioning roller in the direction of strip travel, particularly preferably directly upstream.In a preferred embodiment in which a fourth tensioning roller is provided, this fourth tensioning roller is arranged upstream of the third tensioning roller in the belt travel direction, particularly preferably directly upstream thereof. In a preferred embodiment in which a fifth tensioning roller is provided, this fifth tensioning roller is arranged upstream of the fourth tensioning roller in the belt travel direction, particularly preferably directly upstream thereof. In a preferred embodiment in which a sixth tensioning roller is provided, this sixth tensioning roller is arranged upstream of the fifth tensioning roller in the belt travel direction, particularly preferably directly upstream thereof.

[0034] The preferred arrangement of the individual tension rollers described in the previous paragraph is particularly well suited for embodiments in which the tension roller set according to the invention is to be arranged in front of a winding reel and there is a desire to document the flatness quality with which the strip is wound onto the winding reel. This preferred arrangement is also suitable for a tension roller set that is to be arranged in front of a stretching zone or a bending stand and there is a desire to document the flatness quality with which the strip enters the stretching zone or the bending stand.

[0035] The invention provides a drive for the second tensioning pulley, with which a torque about the second pulley axis can be applied to the second tensioning pulley. Such a drive is particularly preferably equipped with an electric motor and a gear with which adjustable torques can be generated. The drive applies the torque, particularly preferably unilaterally, to one of the bearing journals of the tensioning pulley. In a preferred embodiment, the drive is designed to apply a maximum torque in the range of 1-100 kNm to the tensioning pulley.

[0036] In a preferred embodiment, the first tensioning pulley is designed to be driveless, and all other tensioning pulleys are designed to be driven. In a preferred embodiment, the first tensioning pulley has an auxiliary drive, and all other tensioning pulleys are also designed to be driven.

[0037] In the tension pulley set according to the invention, according to a first embodiment, the first tension pulley, designed as a flatness measuring pulley, is designed without a drive. In this embodiment of the tension pulley set according to the invention, no drive is provided for the first tension pulley, with which a torque about the first roller axis can be applied to the first tension pulley. The first tension pulley is thus designed as a drag pulley.

[0038] In one proposed alternative, an auxiliary drive is provided for the first tension roller, with which a torque can be applied to the first tension roller around the first roller axis. However, this auxiliary drive for the first tension roller is weaker than the drive for the second tension roller. While the drive for the second tension roller is designed in such a way that it can be used to increase or decrease the strip tension in line with the basic idea of ​​a tension roller set, an auxiliary drive for the first tension roller may be necessary in order to rotate the first tension roller when the straightening system is started up, thus enabling the strip to be threaded in, and if necessary to accelerate and decelerate the roller.However, such an auxiliary drive is not necessary for the actual operation of the straightening system and, in a preferred embodiment of the method according to the invention, is switched off after a start-up phase or regulated to a torque of 0 Nm.

[0039] In a preferred embodiment, the auxiliary drive is designed to be one order of magnitude weaker than the drive for the second tensioning pulley. In a preferred embodiment, the auxiliary drive can generate a maximum torque in the range of 0.03 to 0.3 kNm.

[0040] In a preferred embodiment, a third tensioning roller with a third roller axis is provided. In particular, a drive for the third tensioning roller is provided, with which a torque about the third roller axis can be applied to the third tensioning roller. In a preferred embodiment, the drive for the third tensioning roller can generate a maximum torque that is at least twice the maximum torque that the drive for the second tensioning roller can generate. This applies in particular to applications in which, in the order in which the strip runs over the tensioning rollers, the third tensioning roller is closer to a stretching zone, a bending stand or a temper rolling stand than the second tensioning roller.In a preferred embodiment, the drive for the third tensioning roller can generate a maximum torque that is at least half the maximum torque that the drive for the second tensioning roller can generate. This is especially true for applications where, in the order in which the strip passes over the tensioning rollers, the second tensioning roller is closer to a stretching zone, a bending stand, or a temper rolling stand than the third tensioning roller.

[0041] In a preferred embodiment, a fourth tensioning roller with a fourth roller axis is provided. In particular, a drive for the fourth tensioning roller is provided, with which a torque about the fourth roller axis can be applied to the fourth tensioning roller. In a preferred embodiment, the drive for the fourth tensioning roller can generate a maximum torque that is at least twice the maximum torque that the drive for the third tensioning roller can generate. This applies in particular to applications in which, in the order in which the strip runs over the tensioning rollers, the fourth tensioning roller is closer to a stretching zone, a bending stand or a tempering stand than the third tensioning roller.In a preferred embodiment, the drive for the fourth tensioning roller can generate a maximum torque that is at least half the maximum torque that the drive for the third tensioning roller can generate. This is especially true for applications where, in the order in which the strip passes over the tensioning rollers, the third tensioning roller is closer to a stretching zone, a bending stand, or a temper rolling stand than the fourth tensioning roller.

[0042] In a preferred embodiment, a fifth tensioning roller with a fifth roller axis is provided. Particularly preferably, a drive is provided for the fifth tensioning roller, with which a torque about the fifth roller axis can be applied to the fifth tensioning roller. In a preferred embodiment, the drive for the fifth tensioning roller can generate a maximum torque that is at least twice the maximum torque that the drive for the fourth tensioning roller can generate. This applies in particular to applications in which, in the order in which the strip runs over the tensioning rollers, the fifth tensioning roller is closer to a stretching zone, a bending stand, or a temper rolling stand than the fourth tensioning roller.In a preferred embodiment, the drive for the fifth tensioning roller can generate a maximum torque that is at least half the maximum torque that the drive for the fourth tensioning roller can generate. This is especially true for applications where, in the order in which the strip passes over the tensioning rollers, the fourth tensioning roller is closer to a stretching zone, a bending stand, or a temper rolling stand than the fifth tensioning roller.

[0043] In a preferred embodiment, a sixth tensioning roller with a sixth roller axis is provided. Particularly preferably, a drive is provided for the sixth tensioning roller, with which a torque about the sixth roller axis can be applied to the sixth tensioning roller. In a preferred embodiment, the drive for the sixth tensioning roller can generate a maximum torque that is at least twice the maximum torque that the drive for the fifth tensioning roller can generate. This applies in particular to applications in which, in the order in which the strip runs over the tensioning rollers, the sixth tensioning roller is closer to a stretching zone, a bending stand, or a temper rolling stand than the fifth tensioning roller.In a preferred embodiment, the drive for the sixth tensioning roller can generate a maximum torque that is at least half the maximum torque that the drive for the fifth tensioning roller can generate. This is especially true for applications where, in the order in which the strip passes over the tensioning rollers, the fifth tensioning roller is closer to a stretching zone, a bending stand, or a temper rolling stand than the sixth tensioning roller.

[0044] In a preferred embodiment, the drive for the second tensioning roller can apply a maximum torque T2 about the second roller axis to the second tensioning roller, and the auxiliary drive for the first tensioning roller can apply a maximum torque T1 about the first roller axis to the first tensioning roller, where T1 is equal to or less than 7 / 8 of T2, particularly preferably equal to or less than 3 / 4 of T2, very particularly preferably equal to or less than half of T2, very particularly preferably equal to or less than 1 / 8 of T2, very particularly preferably equal to or less than 1 / 10 of T2.

[0045] In a preferred embodiment, the second tensioning roller is arranged relative to the first tensioning roller in such a way that the plane which is perpendicular to the horizontal and which contains the second roller axis lies in front of the plane, as seen in the direction of a run-up direction in which the belt is to run onto the tensioning roller set according to the invention. is perpendicular to the horizontal, is arranged in the run-up direction after the first roller axis of the first tensioning roller and runs tangentially to the surface of the first tensioning roller.

[0046] In a preferred embodiment, the second roller axis is arranged in a horizontal plane which lies below a horizontal plane in which the first roller axis is arranged.

[0047] In a preferred embodiment including a third tensioning pulley, the second tensioning pulley and the third tensioning pulley are arranged relative to the first tensioning pulley such that the plane perpendicular to the horizontal and containing the second roller axis lies on one side of a plane perpendicular to the horizontal and tangent to the surface of the first tensioning roller, and the plane perpendicular to the horizontal and containing the third roller axis lies on the other side of the plane perpendicular to the horizontal and tangent to the surface of the first tensioning roller.

[0048] In this embodiment, a fourth tensioning roller is particularly preferably additionally provided, wherein the fourth roller axis is particularly preferably arranged between the first roller axis and the third roller axis, viewed in the horizontal direction.

[0049] In a preferred embodiment, the first roller axis and the second roller axis are aligned parallel to one another. In a preferred embodiment, all roller axes of the tensioning rollers of the tensioning roller set are parallel to one another. In a preferred embodiment, viewed in a horizontal direction, the second roller axis is arranged in front of the first roller axis, the fourth roller axis is arranged after the first roller axis, and the third roller axis is arranged after the fourth roller axis. In a particularly preferred embodiment, the fifth roller axis is arranged after the third roller axis. In a particularly preferred embodiment, a sixth roller axis is arranged between the fifth roller axis and the third roller axis.

[0050] The straightening system according to the invention for straightening a strip comprises a front tensioning roller set and a rear tensioning roller set. A stretching zone can be provided between the front tensioning roller set and the rear tensioning roller set. A bending stand can be provided between the front tensioning roller set and the rear tensioning roller set. A stretching zone and a bending stand can be provided between the front tensioning roller set and the rear tensioning roller set.

[0051] According to the invention, the front tensioning pulley set can be designed as a tensioning pulley set according to the invention, or the rear tensioning pulley set can be designed as a tensioning pulley set according to the invention. Likewise, according to the invention, both the front tensioning pulley set and the rear tensioning pulley set can be designed as a tensioning pulley set according to the invention.

[0052] In a preferred embodiment, a further flatness measuring roller is provided upstream of the front tensioning roller set and / or downstream of the front tensioning roller set and / or upstream of the rear tensioning roller set and / or downstream of the rear tensioning roller set. In a particularly preferred alternative, no further flatness measuring roller is provided upstream of the front tensioning roller set and / or downstream of the front tensioning roller set and / or upstream of the rear tensioning roller set and / or downstream of the rear tensioning roller set.

[0053] If the first tension roller, designed as a flatness measuring roller, is the first tension roller of the rear tension roller set onto which the strip runs when it leaves the stretching zone or the bending stand, the flatness of the strip can be determined immediately after leaving the stretching zone or after leaving the bending stand. If the first tension roller, designed as a flatness measuring roller according to the invention, is designed as the last tension roller of the front tension roller set, over which the strip runs before leaving the front tension roller set, this arrangement can determine the flatness of the strip immediately before the strip enters the stretching zone or immediately before the strip enters the bending stand.

[0054] However, embodiments are also conceivable in which there is an interest in the flatness with which the strip enters the straightening system according to the invention or with which flatness leaves the straightening system according to the invention. Therefore, embodiments are also expedient in which the first tensioning roller designed as a flatness measuring roller is the first tensioning roller of the front tensioning roller set, onto which the strip runs when it enters the front tensioning roller set. In such an embodiment, the flatness measuring roller according to the invention can be used to determine the flatness of the strip as it leaves the reel. Likewise, an embodiment can be expedient in which the first tensioning roller designed as a flatness measuring roller is the last tensioning roller of the rear tensioning roller set, over which the strip runs before it leaves the rear tensioning roller set.With such an arrangement of the flatness measuring roller, the flatness of the strip can be determined before it runs onto the reel.

[0055] The invention is particularly preferably carried out according to one of the embodiments listed below: In the table below, the following means: None = No flatness measuring roller is provided at this location One = One flatness measuring roller is provided at this location (1) = a first tension roller of this tension roller set is designed as a flatness measuring roller, the first tension roller is arranged at any location in the tension roller set (2) = a first tension roller of this tension roller set is designed as a flatness measuring roller, the first tension roller is the tension roller onto which the belt first runs (3) = a first tension roller of this tension roller set is designed as a flatness measuring roller, the first tension roller is the last tension roller of the tension roller set from which the belt runs (4) = the tension roller set has two tension rollers designed as flatness measuring rollers In front of front tensioner pulley set In the front tensioner pulley set After the front tension roller set, but before the stretching zone or before the bending stand Before the rear tension roller set, but after the stretching zone or after the bending stand In the rear tensioner pulley set After rear tensioner pulley set No No No No (1) No No No No No (2) No No No No No (3) No No No No No (4) No No No No One (1) No No No No One (2) No No No No One (3) No No No No One (4) No No No No No (1) One No No No No (2) One No No No No (3) One No No No No (4) One No No No One (1) One No No No One (2) One No No No One (3) One No No No One (4) One No (1) No No (1) No No (1) No No (2) No No (1) No No (3) No No (1) No No (4) No No (1) No One (1) No No (1) No One (2) No No (1) No One (3) No No (1) No One (4) No No (1) No No (1) One No (1) No No (2) One No (1) No No (3) One No (1) No No (4) One No (1) No One (1) One No (1) No One (2) One No (1) No One (3) One No (1) No One (4) One No (2) No No (1) No No (2) No No (2) No No (2) No No (3) No No (2) No No (4) No No (2) No One (1) No No (2) No One (2) No No (2) No One (3) No No (2) No One (4) No No (2) No No (1) One No (2) No No (2) One No (2) No No (3) One No (2) No No (4) One No (2) No One (1) One No (2) No One (2) One No (2) No One (3) One No (2) No One (4) One No (3) No No (1) No No (3) No No (2) No No (3) No No (3) No No (3) No No (4) No No (3) No One (1) No No (3) No One (2) No No (3) No One (3) No No (3) No One (4) No No (3) No No (1) One No (3) No No (2) One No (3) No No (3) One No (3) No No (4) One No (3) No One (1) One No (3) No One (2) One No (3) No One (3) One No (3) No One (4) One No (4) No No (1) No No (4) No No (2) No No (4) No No (3) No No (4) No No (4) No No (4) No One (1) No No (4) No One (2) No No (4) No One (3) No No (4) No One (4) No No (4) No No (1) One No (4) No No (2) One No (4) No No (3) One No (4) No No (4) One No (4) No One (1) One No (4) No One (2) One No (4) No One (3) One No (4) No One (4) One One No No No (1) No One No No No (2) No One No No No (3) No One No No No (4) No One No No One (1) No One No No One (2) No One No No One (3) No One No No One (4) No One No No No (1) One One No No No (2) One One No No No (3) One One No No No (4) One One No No One (1) One One No No One (2) One One No No One (3) One One No No One (4) One One (1) No No (1) No One (1) No No (2) No One (1) No No (3) No One (1) No No (4) No One (1) No One (1) No One (1) No One (2) No One (1) No One (3) No One (1) No One (4) No One (1) No No (1) One One (1) No No (2) One One (1) No No (3) One One (1) No No (4) One One (1) No One (1) One One (1) No One (2) One One (1) No One (3) One One (1) No One (4) One One (2) No No (1) No One (2) No No (2) No One (2) No No (3) No One (2) No No (4) No One (2) No One (1) No One (2) No One (2) No One (2) No One (3) No One (2) No One (4) No One (2) No No (1) One One (2) No No (2) One One (2) No No (3) One One (2) No No (4) One One (2) No One (1) One One (2) No One (2) One One (2) No One (3) One One (2) No One (4) One One (3) No No (1) No One (3) No No (2) No One (3) No No (3) No One (3) No No (4) No One (3) No One (1) No One (3) No One (2) No One (3) No One (3) No One (3) No One (4) No One (3) No No (1) One One (3) No No (2) One One (3) No No (3) One One (3) No No (4) One One (3) No One (1) One One (3) No One (2) One One (3) No One (3) One One (3) No One (4) One One (4) No No (1) No One (4) No No (2) No One (4) No No (3) No One (4) No No (4) No One (4) No One (1) No One (4) No One (2) No One (4) No One (3) No One (4) No One (4) No One (4) No No (1) One One (4) No No (2) One One (4) No No (3) One One (4) No No (4) One One (4) No One (1) One One (4) No One (2) One One (4) No One (3) One One (4) No One (4) One No No One No (1) No No No One No (2) No No No One No (3) No No No One No (4) No No No One One (1) No No No One One (2) No No No One One (3) No No No One One (4) No No No One No (1) One No No One No (2) One No No One No (3) One No No One No (4) One No No One One (1) One No No One One (2) One No No One One (3) One No No One One (4) One No (1) One No (1) No No (1) One No (2) No No (1) One No (3) No No (1) One No (4) No No (1) One One (1) No No (1) One One (2) No No (1) One One (3) No No (1) One One (4) No No (1) One No (1) One No (1) One No (2) One No (1) One No (3) One No (1) One No (4) One No (1) One One (1) One No (1) One One (2) One No (1) One One (3) One No (1) One One (4) One No (2) One No (1) No No (2) One No (2) No No (2) One No (3) No No (2) One No (4) No No (2) One One (1) No No (2) One One (2) No No (2) One One (3) No No (2) One One (4) No No (2) One No (1) One No (2) One No (2) One No (2) One No (3) One No (2) One No (4) One No (2) One One (1) One No (2) One One (2) One No (2) One One (3) One No (2) One One (4) One No (3) One No (1) No No (3) One No (2) No No (3) One No (3) No No (3) One No (4) No No (3) One One (1) No No (3) One One (2) No No (3) One One (3) No No (3) One One (4) No No (3) One No (1) One No (3) One No (2) One No (3) One No (3) One No (3) One No (4) One No (3) One One (1) One No (3) One One (2) One No (3) One One (3) One No (3) One One (4) One No (4) One No (1) No No (4) One No (2) No No (4) One No (3) No No (4) One No (4) No No (4) One One (1) No No (4) One One (2) No No (4) One One (3) No No (4) One One (4) No No (4) One No (1) One No (4) One No (2) One No (4) One No (3) One No (4) One No (4) One No (4) One One (1) One No (4) One One (2) One No (4) One One (3) One No (4) One One (4) One One No One No (1) No One No One No (2) No One No One No (3) No One No One No (4) No One No One One (1) No One No One One (2) No One No One One (3) No One No One One (4) No One No One No (1) One One No One No (2) One One No One No (3) One One No One No (4) One One No One One (1) One One No One One (2) One One No One One (3) One One No One One (4) One One (1) One No (1) No One (1) One No (2) No One (1) One No (3) No One (1) One No (4) No One (1) One One (1) No One (1) One One (2) No One (1) One One (3) No One (1) One One (4) No One (1) One No (1) One One (1) One No (2) One One (1) One No (3) One One (1) One No (4) One One (1) One One (1) One One (1) One One (2) One One (1) One One (3) One One (1) One One (4) One One (2) One No (1) No One (2) One No (2) No One (2) One No (3) No One (2) One No (4) No One (2) One One (1) No One (2) One One (2) No One (2) One One (3) No One (2) One One (4) No One (2) One No (1) One One (2) One No (2) One One (2) One No (3) One One (2) One No (4) One One (2) One One (1) One One (2) One One (2) One One (2) One One (3) One One (2) One One (4) One One (3) One No (1) No One (3) One No (2) No One (3) One No (3) No One (3) One No (4) No One (3) One One (1) No One (3) One One (2) No One (3) One One (3) No One (3) One One (4) No One (3) One No (1) One One (3) One No (2) One One (3) One No (3) One One (3) One No (4) One One (3) One One (1) One One (3) One One (2) One One (3) One One (3) One One (3) One One (4) One One (4) One No (1) No One (4) One No (2) No One (4) One No (3) No One (4) One No (4) No One (4) One One (1) No One (4) One One (2) No One (4) One One (3) No One (4) One One (4) No One (4) One No (1) One One (4) One No (2) One One (4) One No (3) One One (4) One No (4) One One (4) One One (1) One One (4) One One (2) One One (4) One One (3) One One (4) One One (4) One

[0056] The combination of a flatness measuring roller provided in the tension roller set with a flatness measuring roller upstream and / or downstream of the tension roller set has the disadvantage that more installation space is required for such an embodiment; however, the provision of a separate tension roller in addition to the tension roller provided in the tension roller set can offer the advantage of being able to calibrate the flatness measuring roller in the tension roller set.

[0057] In a preferred embodiment, a belt is guided over the first tensioning roller and over the second tensioning roller, wherein the belt wraps around the first tensioning roller with a wrap angle of at least 90°, particularly preferably at least 125°, particularly preferably at least 130°, particularly preferably at least 145°, particularly preferably at least 180°; and / or the belt wraps around the second tensioning roller with a wrap angle of at least 90°, particularly preferably at least 125°, particularly preferably at least 130°, particularly preferably at least 145°, particularly preferably at least 180°.

[0058] In a preferred embodiment of the straightening system according to the invention, the front tensioning roller set contains just as many driven tensioning rollers as the rear tensioning roller set. In a preferred embodiment, the front and rear tensioning roller sets have the same number of tensioning rollers, wherein the first tensioning roller designed as a flatness measuring roller is designed without a drive and is arranged either in the front or rear tensioning roller set, wherein the other tensioning roller set has no flatness measuring roller but instead has a drag roller, and the remaining tensioning rollers of the respective tensioning roller set are driven, so that the front tensioning roller set contains just as many driven tensioning rollers as the rear tensioning roller set.

[0059] In a preferred embodiment, the rear tensioning roller set of the straightening system is a tensioning roller set according to the invention, wherein the first tensioning roller is the tensioning roller of the tensioning roller set onto which the strip runs after leaving the stretching zone and / or the bending stand. Additionally or alternatively, the front tensioning roller set of the straightening system is a tensioning roller set according to the invention, wherein the first tensioning roller is the tensioning roller of the tensioning roller set from which the strip runs into the stretching zone and / or the bending stand. Alternatively, in a further preferred embodiment, the front tensioning roller set of the straightening system is a tensioning roller set according to the invention, wherein the first tensioning roller is the tensioning roller of the tensioning roller set onto which the strip runs from a decoiler.

[0060] The straightening system according to the invention makes it possible to perform the flatness measurement as close as possible behind the stretching zone or bending stand. This minimizes the dead zone. The invention enables the flatness measuring roller to be used in the high-tension area without interference from the roller drive. Flatness measurement can be performed in the tension area of ​​the straightening system with just one measuring roller. The straightening system according to the invention allows flatness measuring rollers to be designed with the same diameter as the other tension rollers in the tension roller set. This minimizes bending stresses when the strip is deflected around the roller body.

[0061] The tension roller set according to the invention can also be used in a tempering stand for tempering a strip. The tempering stand has a. a front tensioning roller set, b. a rear tensioning roller set, c. a finishing rolling stand provided between the front tensioning roller set and the rear tensioning roller set, where the front tensioning pulley set is designed as a tensioning pulley set according to the invention and / or the rear tensioning pulley set is designed as a tensioning pulley set according to the invention.

[0062] The above disclosure of embodiments of the straightening plant according to the invention is also intended to serve as a disclosure of embodiments of the post-salt stand plant according to the invention, wherein the disclosure of the tempering stand plant is formed by replacing the term "straightening plant" with "tempering stand plant", the term "stretching zone" with rolling stand, and the term "bending stand" with rolling stand.

[0063] A method according to the invention for operating a straightening system according to the invention, which has a bending stand with an adjustable bending roller and a control device, provides that the control device carries out control interventions on at least one actuator of the straightening system, for example the adjustable bending roller or the tensioning roller sets, based on measurement results of the force sensor.

[0064] A method according to the invention for operating a tempering stand system according to the invention, which has an adjustable roll and a control device, provides that the control device carries out control interventions on at least one actuator of the tempering stand system, for example the adjustable roll or the tensioning roller sets, based on measurement results of the force sensor.

[0065] A supplementary or alternative method for operating a straightening system according to the invention or a tempering rolling stand system according to the invention, which is designed in such a way that an auxiliary drive is provided for the first tensioning roller, with which a torque about the first roller axis can be applied to the first tensioning roller, wherein the auxiliary drive for the first tensioning roller is designed to be weaker than the drive for the second tensioning roller, provides that after a start-up phase and / or after the strip tension has been built up, the auxiliary drive for the first tensioning roller is switched off or is regulated to a drive torque of 0 Nm.

[0066] The start-up phase includes, in particular, threading the belt and accelerating the system to operating speed.

[0067] The method according to DE 10 2019 006 788 can be carried out with the tension pulley set according to the invention.

[0068] The invention is particularly preferably used in the straightening and / or re-rolling of strip material, preferably metal strips or sheets.

[0069] The invention is explained in more detail below with reference to drawings illustrating only embodiments of the invention. In these drawings: Fig. 1 a schematic side view of a straightening system according to the invention; Fig. 2 a schematic side view of another straightening system according to the invention and Fig. 3 a schematic representation of the forces acting on a measuring roller.

[0070] The Fig. 1The straightening system 1 shown for straightening a strip 2 has a front tension roller set 3 and a rear tension roller set 4. A bending stand 5 is provided between the front tension roller set 3 and the rear tension roller set 4. A reel 6 is provided in front of the front tension roller set 3. A reel 7 is provided behind the rear tension roller set 4.

[0071] Strip 2 is unwound from reel 6, passes through front tension pulley set 3, passes through bending stand 5, passes through rear tension pulley set 4, and is wound up by reel 7. In front tension pulley set 3, the strip tension acting on strip 2 is increased, while in rear tension pulley set 4, the strip tension acting on strip 2 is reduced, so that the strip tension acting on strip 2 in the area of ​​bending stand 5 is higher than before front tension pulley set 3 and after rear tension pulley set 4.

[0072] The rear tension pulley set 4 has a first tensioning roller 8 with a first roller axis, a second tensioning roller 9 with a second roller axis, a third tensioning roller 10 with a third roller axis, a fourth tensioning roller 11 with a fourth roller axis, wherein the first tension roller 8 is a flatness measuring roller having a force sensor for measuring a radial force (FR,1) exerted on the circumferential surface of the flatness measuring roller.

[0073] A drive (not shown in detail) is provided for the second tensioning pulley 9, with which a torque about the second pulley axis can be applied to the second tensioning pulley 9. Furthermore, a drive (also not shown in detail) is provided for the third tensioning pulley 10, with which a torque about the third pulley axis can be applied to the third tensioning pulley 10. Furthermore, a drive (also not shown in detail) is provided for the fourth tensioning pulley 11, with which a torque about the fourth pulley axis can be applied to the fourth tensioning pulley 11.

[0074] The first tension pulley 8 is designed without a drive.

[0075] The front tension pulley set 3 has a first tensioning roller 14 with a first roller axis, a second tensioning roller 15 with a second roller axis, a third tensioning roller 16 with a third roller axis, a fourth tensioning roller 17 with a fourth roller axis, A drive (not shown in detail) is provided for the second tensioning pulley 15, with which a torque about the second pulley axis can be applied to the second tensioning pulley 15. Furthermore, a drive (likewise not shown in detail) is provided for the third tensioning pulley 16, with which a torque about the third pulley axis can be applied to the third tensioning pulley 16. Furthermore, a drive (likewise not shown in detail) is provided for the fourth tensioning pulley 17, with which a torque about the fourth pulley axis can be applied to the fourth tensioning pulley 17.

[0076] The first tensioning roller 14 is designed without a drive.

[0077] The Fig. 2 The straightening system 1 shown differs from the one in Fig. 1illustrated straightening system 1 by the structure of the rear tensioning roller set 4 and the structure of the front tensioning roller set 3. In addition to the first tensioning roller 8, the second tensioning roller 9, the third tensioning roller 10 and the fourth tensioning roller 11, this has a fifth tensioning roller 12 and a sixth tensioning roller 13.

[0078] A drive (not shown in detail) is provided for the second tensioning pulley 9, with which a torque about the second roller axis can be applied to the second tensioning pulley 9. Furthermore, a drive (likewise not shown in detail) is provided for the third tensioning pulley 10, with which a torque about the third roller axis can be applied to the third tensioning pulley 10. Furthermore, a drive (likewise not shown in detail) is provided for the fourth tensioning pulley 11, with which a torque about the fourth roller axis can be applied to the fourth tensioning pulley 11. Furthermore, a drive (likewise not shown in detail) is provided for the fifth tensioning pulley 12, with which a torque about the fifth roller axis can be applied to the fifth tensioning pulley 12.

[0079] The first tension pulley 8 and the sixth tension pulley 13 are designed without drive.

[0080] The front tensioning pulley set 3 in the embodiment of the Fig. 2 indicates a first tensioning roller 14 with a first roller axis, a second tensioning roller 15 with a second roller axis, a third tensioning roller 16 with a third roller axis, a fourth tensioning roller 17 with a fourth roller axis, A drive (not shown in detail) is provided for the second tensioning pulley 15, with which a torque about the second roller axis can be applied to the second tensioning pulley 15. Furthermore, a drive (likewise not shown in detail) is provided for the third tensioning pulley 16, with which a torque about the third roller axis can be applied to the third tensioning pulley 16. Furthermore, a drive (likewise not shown in detail) is provided for the fourth tensioning pulley 17, with which a torque about the fourth roller axis can be applied to the fourth tensioning pulley 17. Furthermore, a drive (likewise not shown in detail) is provided for the first tensioning pulley 14, with which a torque about the first roller axis can be applied to the first tensioning pulley 14.

[0081] Fig. 3shows the forces exerted on the measuring roller by a metal band partially wrapped around the measuring roller and subjected to tension. The quartz force sensors located in recesses in the measuring roller generate an electrical charge. This charge is directly proportional to the force applied to the quartz.

[0082] The strip length deviation, usually measured in I-units and commonly used as a representative of the flatness of the strip, can be calculated using the following relationships: Local tensile stress in strip section i Z,i = FR,ix r_Roll / (A_Sensor xd) where F_R,i = Local radial force in N (sensor force) r_Roll = Radius of the measuring roller A_Sensor = Area of ​​the sensor or the cover on the sensor that is in contact with the belt d = Belt thickness

[0083] Tensile stress deviation of the strip section from the strip section with maximum tensile stress: Δ Z,i = Z,l - Z,max with Z,max = maximum of all local tensile stresses

[0084] Local strip length deviation (flatness): ΔL / Li=-Δ Z,i / E with E = Young's modulus

[0085] Example: FR,i = 500 N r_Roll = 300 mm A_Sensor = 707 mm 2< d = 0.5 mm Z,l = 424.4 MPa Z,max = 430 MPa Δ Z,l = -5.59 MPa E = 206 GPa ΔL / Li = 27.1 µm / m = 2.71 I units

Claims

1. Tensioning pulley set (3, 4) for a straightening line (1) for straightening a strip (2) or for a re-rolling stand for re-rolling a strip, wherein the tensioning pulley set (3, 4) comprises • a first tensioning pulley (8) with a first pulley axle and • at least one second tensioning pulley (9) with a second pulley axis, wherein the first tension pulley (8) is a flatness measuring pulley which has a force sensor for measuring a radial force exerted on the circumferential surface of the flatness measuring pulley, and a drive for the second tensioning pulley (9) is provided, with which a torque about the second pulley axis can be applied to the second tensioning pulley (9), characterized in that • the first tensioning pulley (8) is designed to be non-driven.

2. Tensioning pulley set (3, 4) according to claim 1, characterized by a third tensioning pulley (10) with a third pulley axis and a fourth tensioning pulley (11) with a fourth pulley axis, wherein a. a drive for the third tensioning pulley (10) is provided, with which a torque about the third pulley axis can be applied to the third tensioning pulley (10), and / or b. a drive for the fourth tensioning pulley (11) is provided, with which a torque about the fourth pulley axis can be applied to the fourth tensioning pulley (11).

3. Tensioning pulley set (3, 4) according to claim 2, characterized by a fifth tensioning pulley (12) with a fifth pulley axis, wherein a drive for the fifth tensioning pulley (12) is provided, with which a torque about the fifth pulley axis can be applied to the fifth tensioning pulley (12).

4. Tensioning pulley set (3, 4) according to any one of claims 1 to 3, characterized in that the drive for the second tensioning pulley (9) can apply a maximum torque T2 about the second pulley axis to the second tensioning pulley (9) and in that the auxiliary drive for the first tensioning pulley (8) can apply a maximum torque T1 about the first pulley axis to the first tensioning pulley (8), wherein T1 is equal to or less than half of T2.

5. Tensioning pulley set (3, 4) according to any one of claims 1 to 4, characterized in that the flatness measuring pulley has an axial bore running parallel to the first pulley axis and in that the force sensor is arranged in the axial bore.

6. Tensioning pulley set (3, 4) according to any one of claims 1 to 5, characterized in that the flatness measuring pulley comprises a surface coating.

7. Tensioning pulley set (3, 4) according to any one of claims 1 to 6, characterized in that a strip (2) is guided over the first tensioning pulley (8) and over the second tensioning pulley (9) and the strip (2) wraps around the first tensioning pulley (8) with a wrap angle of at least 90° and / or the strip (2) wraps around the second tensioning pulley (9) with a wrap angle of at least 90°8. Straightening line (1) for straightening a strip (2) with a. a front tensioning pulley set (3), b. a rear tension pulley set (4), c. a stretching zone provided between the front tensioning pulley set (3) and the rear tensioning pulley set (4) and / or a bending stand (5) provided between the front tensioning pulley set (3) and the rear tensioning pulley set (4), characterized in that • the front tensioning pulley set (3) is a tensioning pulley set according to any one of claims 1 to 7 and / or • the rear tensioning pulley set (4) is a tensioning pulley set according to any one of claims 1 to 7.

9. Straightening line (1) according to claim 8, characterized in that a. the rear tensioning pulley set (4) is a tensioning pulley set according to any one of claims 1 to 7 and that the first tensioning pulley (8) is the tensioning pulley of the tensioning pulley set on which the strip (2) runs first and / or b. the front tensioning pulley set (3) is a tensioning pulley set according to any one of claims 1 to 7 and that the first tensioning pulley (8) is the tensioning pulley of the tensioning pulley set from which the strip (2) runs off last.

10. Re-rolling stand line for re-rolling a strip (2) with a. a front tensioning pulley set (3), b. a rear tension pulley set (4), c. a re-rolling stand provided between the front tensioning pulley set (3) and the rear tensioning pulley set (4), characterized in that • the front tensioning pulley set (3) is a tensioning pulley set according to any one of claims 1 to 7 and / or • the rear tensioning pulley set (4) is a tensioning pulley set according to any one of claims 1 to 7.

11. Method for operating a straightening line (1) according to any one of claims 8 or 9, wherein the straightening line (1) comprises a bending stand (5) with adjustable bending rollers and a control device, characterized in that the control device carries out control interventions on at least one actuator of the straightening line on the basis of measurement results from the force sensor.

12. Method for operating a re-rolling stand line according to claim 10, wherein the re-rolling stand has adjustable rollers and a control device, characterized in that the control device carries out control interventions on at least one actuator of the re-rolling stand line on the basis of measurement results from the force sensor.

13. Method for operating a straightening line (1) according to any one of claims 8 or 9 or a re-rolling stand line according to claim 10, in which the tensioning pulley set (3, 4) according to any one of the claims 1 to 7 is designed such that an auxiliary drive for the first tensioning pulley (8) is provided, with which a torque about the first pulley axis can be applied to the first tensioning pulley (8), wherein the auxiliary drive for the first tensioning pulley (8) is designed to be weaker than the drive for the second tensioning pulley (9), characterized in that after a start-up phase or after application of the strip tension, the auxiliary drive for the first tensioning pulley (8) is switched off or is regulated to a torque of 0 Nm.

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