EP2813299A1 - Method and device for aligning metal strips by stretch bending - Google Patents

Abstract

It is a method for stretch bend straightening of metal straps, especially high strength steel straps, wherein the strap (B) passes through an infeed tensioning pulley set (E) for tensioning and a pullout tensioning pulley set (A) for draft removal, the strip (B) being arranged between the infeed tensioning pulley set (E) and Outlet tensioning roller set (A) initially mutually bent around individually supported stretch rollers (1-5) and thereby the degree of stretching is increased and wherein the band (B) then one of the last stretch rollers (5) downstream multi-roller straightening (V) with a plurality of straightening rollers ( 6-11), around which the tape (B) is alternately bent to reduce tape warpage and / or residual stress. The degree of plastic stretching is produced both with the stretch rollers (1-5) and proportionally with the multiroll straightening set (V).

Description

The invention relates to a method for stretch bend straightening of metal strips, wherein the strip passes through an infeed tensioning roller set for train construction and outfeed tensioning roller set for train removal,
wherein the band between Einlaufspannrollenensatz and Auslaufspannrollenensatz initially mutually bent around individually supported (that is, not frictionally interconnected) stretching rollers and thereby the degree of stretching is increased and
the belt then passes through a multi-roll straightener with a plurality of straightening rollers arranged downstream of the last draw roll around which the belt is alternately bent to reduce belt bends and / or residual stresses. The degree to which the band is stretched plastically (in total) and thus elongated is called the degree of stretching.

With such a stretch bending method, unplane metal bands can be straightened out and consequently eliminate blemishes. Unplanarity means z. B. Bandwelligkeit and / or Bandsäbeligkeit, which arise due to differences in length of the ribbon fibers in the band level. But unevenness also means band curvatures in longitudinal and / or transverse directions, which arise due to bending moments in the band, eg. B. when the band was elastically-plastically bent around pulleys or by elastic-plastic deformation during winding of the tape. Longitudinal curvatures are also referred to as coil set, transverse curvatures as cross-bow. In the course of the stretch-bending, the unplane band under a tensile stress, which is below the elastic limit R _E or their technical elastic limit R _p 0.01 of the strip material, to rolls of sufficiently small diameter (mutually) bent, so that the superimposition of the tension with the bend produces an elastic / plastic deformation in the band. The strip is elongated plastically, the height of the plastic elongation being called the degree of stretching. During plastic elongation, the originally short ribbon fibers are elongated relatively more strongly. Ideally, all strapping fibers have the same length after straightening, so that basically in ideally straightened band should be free of ripples or band saber.

In the case of the stretch bending methods known from practice, residual bending moments can remain in the band after bending due to the mutual bending in the elastic-plastic area, which can be visible as transverse curvature in the band treatment line and in the case of a cut-out panel to a plastic residual curvature in the longitudinal and / or Can lead transverse direction. The residual bending moments arise when the individual bends are not optimally matched in their intensity. The bending radii depend on the band data (thickness, modulus of elasticity, cyclic strength behavior, transverse contraction number), the strip tension, the roll diameters and the geometry of the strip run around the rolls. In a first approximation, the latter can be described by the angle of wrap of the band around the rollers. If the wrap angle or tension is sufficient, the tape will take on the radius of the roll. Then the band curvature reaches its maximum and remains constant as the wrap angle or tension increases. In general, however, the wrap angles are set so that the tape does not follow the roll radius.

Even with an optimal setting of a given stretch bending stand, residual bending moments result from fluctuations in the process parameters. Because in practice both the tension and consequently the Degree of stretching and the strength values and the strip thickness of the strip in principle subject to certain fluctuations.

The simple stretch bending process with only three bends is relatively sensitive to variations in the parameters mentioned. Therefore, depending on the application, excessive residual curvatures remain in the belt.

A significant improvement brings a stretch bending process with four individually adjustable stretch rollers (see. WO 2011/032890 A1 ).

Higher requirements are z. B. when the yield strength and the required degree of stretching are very high, z. B. in high-strength steel strips. More bends may then be required to keep the residual curvature values within small values, e.g. B. less than 10 ^-1 (1 / m).

The classic mechanical engineering solution, with which a large number of bends can be realized, is a multi-roller straightening set with z. B. a lower fixed or an upper adjustable cassette with straightening rollers and support rollers. The upper cassette is usually vertically positionally adjustable and adjustable in inclination. So you can linearly from roll to roll decreasing wrap angle, the first and the last straightening roll each have only half the wrap angle and primarily the function of Passline roles. The disadvantage of such a classic solution is that the straightening rollers are frictionally coupled to each other within a cassette by the support rollers, that is, that all straightening rollers run at the same speed. Due to the elongation generated in the strip during stretch bending (that is, the degree of stretching), the strip runs correspondingly faster from roll to roll. This leads to slippage in the multi-roll set and, as a result, to vibrations that lead to unwanted chatter marks on the belt can. The risk of chatter marks increases with the degree of stretching, so that this type is used in practice, especially at low levels of stretch.

For these reasons, it has already been proposed to combine conventional stretch bender stands with multi-roll straightening units. Such a stretch bending method of the type described above is z. B. from the EP 0 665 069 B1 or the DE 695 14 010 T2 known. The role settings are set with a control system that works with a mathematical model. In this case, the degree of stretching is produced by paired stretch rollers. In the multi-roll set is then carried out without substantial increase in the degree of stretching only the correction of Längswölbungsfehlern.

The advantages of combining a stretch bending jig with a multi-roll leveling unit are also already described in the article " Advances in Levelling Machines "by Keiji Yamamoto and Keizo Abe in" Journal of the Research Group Flattened Metal Technology 31 (1992), 24-31 Here, too, the degree of stretching is produced by means of stretch rollers which can be set in pairs with respect to one another and the correction of buckling errors then takes place in the multi-roll set.

Based on the known prior art, the invention, the technical problem of providing a stretch bending method, which ensures optimum flatness results with low equipment outlay, especially in high-strength tapes and high degrees of elongation required.

To solve this problem, the invention teaches in a generic method of the type described above that the plastic degree of yield generated both with the stretch rollers and proportionately with the multi-roller straightening becomes. The invention is based on the recognition that the straightening results can be significantly improved if the degree of stretching is not exclusively or substantially exclusively produced with the stretch rollers, but if the multi-roller straightening very specifically in the generation of a significant proportion of the degree of stretching is included. Thus, it is within the scope of the invention that at least 5% of the plastic degree of stretching, preferably at least 10% of the plastic degree of stretching, be generated with the downstream multi-roller straightening. It is particularly useful when a significant proportion of this degree of stretching is generated with the first straightening roller or with the first two straightening rollers of the multi-roller straightening. Then it is preferably provided that at least 5% of the plastic degree of stretching, preferably at least 10% of the plastic degree of stretching are generated with the first straightening roller of the multiroll straightening set. The invention has recognized that, in particular, the first roller of the multiroll straightening set can be used to a considerable extent to produce the degree of stretching. The fact that a considerable elongation of the strip then takes place in the region of this first roller of the multiroll straightening guide does not lead to the problem of possible chatter marks since the second straightening roller following the first straightening roller is not frictionally connected to the first straightening roller. Only the third straightening roller of the multiroll straightening set is part of the same cassette as the first straightening roller, so that a considerable degree of stretching in the region of the first straightening roller does not lead to undesirable chatter marks.

According to a further proposal of the invention with particular importance is provided that the wrap angle decreases at least on the stretch rollers and the first straightening roller, but preferably on all straightening rollers, from roll to roll. So it may be z. B. be provided that the wrap angle to the stretch rollers and optionally at least the first straightening roll from roll to roll by at least 5% (based on the Wrap angle of each preceding role) decreases. In this case, the invention has recognized that it is disadvantageous in prior art embodiments when working with stretched roller pairs, in which there are approximately the same wrap angles at each stretch roll of such a pair of drawrolls. In fact, it is favorable for the equilibrium of the residual stresses, if the wrap angles and thus the ribbon curvatures, decrease from roll to roll. It is particularly advantageous if the wrap angle in the first bends, which produce the degree of stretch, decrease more from roll to roll and only weak in the further bends. A device that operates according to such a method is particularly insensitive to residual curvatures. In terms of machine technology, this is realized particularly economically, because it is not necessary to work with a large number of individual cassettes, but because in the described manner firstly individual stretch rollers and then the multiroll straightening set are provided which operate in the manner according to the invention.

It is advantageous if the wrap on the stretch rollers and straightening rollers from roll to roll initially decrease by higher and then small differences. This can be z. B. be realized in that the wrap from the first stretch roll to the first straightening roll from roll to roll by a first constant difference and from the second straightening roll to the last straightening roll from roll to roll by a second constant difference, preferably a smaller difference , Alternatively, it is within the scope of the invention that the wrap angles decrease from the first stretch roll to the first straightening roll by differences which become smaller from one roll to the next.

The embodiment of the method with decreasing angles of wrap leads to an insensitivity of the method with respect to residual curvatures.

Furthermore, the invention has recognized that it is z. B. with respect to residual ripples is low, if the roller distances between the individual stretch rollers and between the last stretch roller and the first straightening roll not decrease, but are either approximately identical or even increase in the direction of belt travel. It is particularly advantageous if the roller spacings are relatively large. Preferably, they are each at least 300 mm. So it is within the scope of the invention that between two successive stretch rollers and between the last stretch roller and the first straightening roller, the distances each amount to at least a third, preferably at least half the width of the belt or maximum width of the belt. In any case, the tendency to center ripple is avoided or minimized by sufficiently large horizontal distances (or in the strip running direction) from roll to roll in the draw rolls.

The invention also relates to a device for stretch bending of metal strips by a method of the type described. This device has at least one Einlaufspannollensatz for building the strip tension and a Auslaufspannrollensatz for reducing the strip tension and several arranged between Einlaufspannrollensatz and Auslaufspannrollensatz, individually supported stretch rollers on which The tape is bent alternately increasing the degree of stretching. Further, between Einlaufspannrollenensatz and Auslaufspannollensatz a last stretch roller downstream multi-roll straightener is provided with a plurality of straightening rollers around which the band is bent to reduce band bends and / or residual stress alternately. The multiroll straightener kit includes an upper straightening cartridge with upper straightening rollers and a lower straightening cartridge lower straightening rollers, wherein at least one of the straightening cassettes, z. B. the upper straightening cassette in height and tilt is adjustable, preferably position-adjustable. The multiroll straightening set is immediately downstream of the last stretch roll, ie no further set of tension rolls (brake roll set and / or pull roll set) is arranged between the last stretch roll and the multiroll straightening set.

Furthermore, it is expedient that at least the last stretch roller is adjustable, preferably position adjustable adjusted. Particularly preferred are (all) upper stretch rollers and / or (all) lower stretch rollers individually adjustable, preferably adjustable position adjustable. But of particular importance is the fact that the individual stretch rollers - unlike a multi-roller set - are not frictionally connected together. Also, the first straightening roller of the multiroll straightening set is not frictionally connected to the preceding stretch roller and also not frictionally connected to the second straightening roller. As already described, this solution avoids the risk of chatter marks. For different tapes, the optimum wrap angle combinations can be set flexibly.

Optimal results can be achieved when working with relatively many roles. The solution according to the invention with stretch rollers on the one hand and a multi-roller straightening set on the other hand is distinguished by an economical construction and a limitation of the required overall length. It is advantageous if at least four stretch rollers, preferably five stretch rollers, are provided. Optionally, even more stretch rollers may be provided. The multiroll straightening set has at least eight straightening rollers, preferably at least ten straightening rollers.

It is also expedient that an inlet-side deflection roller is provided between the inlet tensioning roller set and the outlet tensioning roller set in front of the first stretching roller, so that the wrap angle and thus the belt curvature are already flexibly adjustable in the region of the first stretching roller.

Such a deflection roller can also be designed as a strip tension measuring device. Because it is optionally useful if a Bandzugmessvorrichtung is provided between Einlaufspannrollensatz and Auslaufspannrollensatz.

In addition, the system is equipped with a control device which is connected to the various system components. Thus, the control device may first be connected to the drives of the Einlaufspannrollensatzes and the Auslaufspannrollensatzes. Alternatively or additionally, the control device can be connected to the adjusting devices of the stretch rollers and the adjusting devices of the multiroll straightening set. Consequently, a positionally exact adjustment of the rollers and thus an exact adjustment of the desired wrap angle can be realized via the control device.

It is within the scope of the invention to determine the roller adjustments from a mathematical model, which at least the material properties (ie modulus, transverse contraction number, elastic limit and / or solidification module) and the machine geometry, the strip thickness, the bandwidth, the tension and the Degree of yield taken into account. In particular, the positions of the rollers and the distances are included in the machine geometry. However, the invention provides that the jobs are not calculated using a mathematical model within the control device, but according to the invention are predetermined in the control device Values entered for the role settings. These setpoints for the role settings can be calculated in advance using the described mathematical model and then transferred as value tables to the controller, so that then only the default settings must be realized within the control.

The invention can be particularly preferably implemented in high-strength steel strips, z. B. a thickness of 0.15 mm to 2 mm, z. B. may have 0.5 mm to 2 mm. However, the advantages described can also be realized with tapes of different thickness and also with tapes made of other material.

Fig. 1

eine Anlage zum Streckbiegerichten von Metallbändern in einer vereinfachten Seitenansicht,

Fig. 2

eine graphische Darstellung der Entwicklung des (relativen) Streckgrades von Rolle zu Rolle bei einer Vorrichtung nach Fig. 1, und

Fig. 3a, 3b

beispielhaft zwei verschiedene Einstellungen für die Umschlingungswinkel an den Rollen.

In the following the invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment. Show it:

Fig. 1

a system for stretch bending of metal strips in a simplified side view,

Fig. 2

a graphic representation of the development of the (relative) degree of stretch from roll to roll in a device according to Fig. 1 , and

Fig. 3a, 3b

For example, two different settings for the wrap angle on the rollers.

In Fig. 1 a system for stretch bending of metal strips B is shown. The system has in its basic structure a Einlaufspannrollenensatz A for the construction of the strip tension and a Auslaufspannrollensatz E for the reduction of the strip tension. Between inlet tensioning roller set A and Outlet tensioning roller set E are a guide roller U and then five individually supported stretch rollers 1, 2, 3, 4, 5 arranged around which the band B is bent alternately increasing the degree of stretching.

The last stretch roller 5 is then followed by a multi-roller straightening set V, which has a plurality of straightening rollers 6 to 16, around which the band is bent alternately to reduce band bends and / or residual stresses. It can be seen in the figures that the VielrollenRichtsatz V of the last stretch roller 5 is immediately downstream, without further tension roller sets are arranged between the last stretch roller 5 and the multi-roller straightening. The multitool straightening set V consists essentially of an upper straightening cassette K1 and a lower straightening cassette K2, wherein the upper straightening cassette K1 can be adjusted in height and in a position-controlled manner. Each of the straightening rollers 6 to 16 of the multirolling scaffold V is supported via support rollers or between rollers and support rollers, wherein the individual rollers of the upper straightening cassette K1 on the one hand and the individual rollers of the lower straightening cassette K2 via these support rollers or intermediate circuit as a 1: 1 gear frictionally engaged connected to each other. This is not shown in the figures.

Of the individual stretch rollers 1 to 5 are in the embodiment, the three upper stretch rollers 1, 3 and 5 individually positionally adjusted. Incidentally, it is indicated that the distances between two directly successive stretch rollers and between the last stretch roller and the first straightening roller increase in the direction of belt travel.

With the illustrated system, metal strips and in particular high-strength metal strips can be stretch bent straightening according to a method of the type described. For this purpose, the plant is operated so that the plastic degree of stretching not exclusively with the stretch rollers 1 to 5, but proportionally with the multi-roller straightening V and in particular with the first straightening roller 6 is generated.

This can be exemplified by Fig. 2 detect. There, the (relative) degree of stretching according to the respective role are shown graphically. The degree of stretching develops from roll to roll in the following manner, with the proportion of the total degree of stretching according to each roll being given in each case: Roll no. Proportion of the degree of stretching according to the respective roll 1 0.27 2 0.47 3 0.64 4 0.78 5 0.89 6 0.97 7 0.99 8th 1.00 9 1.00 10 1.00 11 1.00 12 1.00 13 1.00 14 1.00 15 1.00 16 1.00

A proportion of the degree of stretch after roll 1 of 0.27 thus corresponds to a degree of stretching of 27% of the total degree of draw after this roll. After the roll 8 in this embodiment, consequently, a proportion of the degree of stretching of 1.0 and consequently the total degree of stretching is achieved. The same applies to the information in Fig. 2 , Also there, the respective proportion of the total degree of stretching is given according to the respective role.

From the table or from Fig. 2 It becomes clear that, in particular with the first straightening roller of the multi-roller straightening set V, a considerable proportion of the degree of stretch of more than 10% is still generated. This is possible because this first straightening roller 6 is frictionally engaged neither with the preceding stretch roller 5 nor with the subsequent straightening roller 7.

Moreover, according to the invention it is important that the wrap angles are flexibly adjustable by the individual position adjustment. According to the invention results in a "slow" drop in the wrap angle. For that there are different possibilities.

Fig. 3a shows a first variant in which the wrap angle of the first stretch roller 1 to the first straightening roller 6 from roll to roll decrease by a first constant difference, so that the points connected to the rollers 1 to 6 substantially by a straight line with a first slope are. Then, the wrap angles from the second straightening roller 7 to the last straightening roller 16 decrease by a second constant difference amount, which is less than the first difference amount. In this way, the points can be connected to the rollers 7 to 16 substantially by a second straight line with a second pitch, which is lower in magnitude.

Fig. 3b shows a modified mode of operation in which decrease the wrap angle of the first stretch roller 1 to the first straightening roller 6 by decreasing difference amounts. From the second straightening roller 7 to the last straightening roller 16, substantially constant differences are again set.

In any case, such operations are characterized by a uniformly degrading bending effect, since the wrap from roll to roll as it were "flowing" decrease.

Claims (20)

Method for stretch bending of metal strips, in particular high-strength steel strips,
the belt passing through an infeed tensioning pulley set (E) for pulling construction and a pullout set tensioning pulley set (A),
wherein the band (B) between Einlaufspannrollenensatz (E) and Auslaufspannrollenensatz (A) initially mutually bent around individually supported stretch rollers (1-5) and thereby the degree of stretching is increased, and
wherein the band (B) then passes through one of the last stretch rollers (5) downstream multiroll straightening set (V) with a plurality of straightening rollers (6-11) around which the band (B) mutually bent to reduce band curvature and / or residual stress becomes,
characterized in that the plastic degree of stretching is produced both with the stretch rollers (1-5) and proportionally with the multiroll straightening set (V). A method according to claim 1, characterized in that at least 5% of the plastic degree of stretching, preferably at least 10% of the degree of stretching, with the multi-roller straightening (V) are produced, more preferably at least 5% of the plastic degree of stretching, z. B. 10% of the plastic degree of stretching, with the first straightening roller (6) of the multi-roller straightening (V) are generated. A method according to claim 1 or 2, characterized in that the wrap angle decreases at least on the draw rolls (1-5) and the first straightening roller (6), preferably on all straightening rollers (6-11) from roll to roll. A method according to claim 3, characterized in that the wrap angle to the stretch rollers (1-5) and optionally at least the first straightening roller (6) from roll to roll by at least 5% decreases. A method according to claim 3 or 4, characterized in that the wrap angle at the stretch rollers (1-5) and straightening rollers (6-11) decreases from roll to roll, first by higher and then by smaller differences. A method according to claim 5, characterized in that the wrap angle of the first stretch roller (1) to the first straightening roller (6) from roll to roll by a first constant difference and from the second straightening roller (7) to the last straightening roller (11) of Role to role by a second constant difference amount, preferably a smaller difference, decrease. A method according to claim 5, characterized in that the wrap angle of the first stretch roller (1) to the first straightening roller (6) decrease by roll to roll smaller difference amounts. Device for stretch bending of metal strips according to a method according to one of claims 1 to 7, comprising at least an inlet tensioning roller set (E) for building up the strip tension, a run-out tensioning roller set (A) for removing the strip tension, a plurality of individually supported draw rolls (1-5) arranged between inlet tensioning roller set (E) and outlet tensioning roller set (A), around which the tape is alternately bent while increasing the degree of stretching, - one of the last stretch roller (5) downstream multi-roller set (V) with a plurality of straightening rollers (6-11) around which the band (B) is bent alternately,
characterized in that the plastic degree of stretching is produced both with the stretch rollers (1-5) and proportionally with the multiroll straightening set (V). Device according to Claim 8, characterized in that the multi-roller set (V) comprises an upper straightening cassette (K1) with upper straightening rollers (7, 9, 11, 13, 15) and a lower straightening cassette (K2) with lower straightening rollers (6, 8, 10 , 12, 14, 16), wherein at least one of the straightening cassettes, z. B. the upper straightening cassette (K1) in height and tilt is adjustable, preferably position-adjustable. Apparatus according to claim 8 or 9, characterized in that at least the last stretch roller (5) is adjustable, preferably position-adjustable is adjustable. Apparatus according to claim 10, characterized in that the upper stretch rollers (1, 3, 5) and / or the lower stretch rollers (2, 4) are individually adjustable, preferably position-adjustable can be adjusted. Device according to one of claims 8 to 11, characterized in that the distances between two directly successive stretch rollers (1-5) and between the last stretch roller (5) and the first straightening roller (6) are approximately identical or increase in the strip running direction. Device according to one of claims 8 to 12, characterized in that the distances between two directly successive stretch rollers (1-5) and between the last stretch roller (5) and the first straightening roller (6) each amount to at least 300 mm. Device according to one of claims 8 to 13, characterized in that the distances between two directly successive stretch rollers (1-5) and between the last stretch roller (1-5) and the first straightening roller (6) each at least one third, preferably at least half the width of the tape or the maximum width of the tape amount. Device according to one of claims 8 to 14, characterized in that at least four, preferably five or more stretch rollers (1-5) are arranged in front of the multi-roller straightening set (V). Device according to one of claims 8 to 15, characterized in that the multi-roller straightening set (V) at least eight, preferably at least ten straightening rollers (6-16). Device according to one of claims 1 to 16, characterized in that the first stretch roller (1) upstream of an inlet-side guide roller (U) is arranged. Device according to one of claims 1 to 17, characterized in that between Einlaufspannrollenensatz (E) and Auslaufspannrollenensatz (A), preferably in front of the first stretch roller (1), a Bandzugmessvorrichtung is arranged, wherein at least one deflection roller (U) is designed as a strip tension measuring device. Device according to one of claims 1 to 18, characterized in that the drives of the Einlaufspannrollenensatzes (E) and the Auslaufspannrollenensatzes (A), the Anstelleinrichtungen the draw rolls (1-5) and the adjusting means of the multiroll straightening set (V) connected to a control device are. Apparatus according to claim 19, characterized in that in the control means predetermined target roller positions are deposited, which are previously determined by calculation and then entered into the control device.

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