EP2026916A1 - Rolling stand for producing rolled strip or sheet - Google Patents

Abstract

A rolling mill stand for the production of rolled strip or sheet metal includes working rolls which are supported on respective supporting rolls or on intermediate rolls which are supported on supporting rolls. At least one of the rolls having a barrel contour which runs over the entire effective barrel length and can be described by a non-linear function. The barrel contour of this at least one roll having chamfers in at least one of the marginal regions of its longitudinal extent and the chamfers forming a corrected barrel contour in these marginal regions, so that inhomogeneities in the load distribution along the contact line of two adjacent rolls, and in particular in the region of the edges of the strip, are minimized. The corrected barrel contour is obtained by subtracting any non-linear mathematical chamfer function from the contour function described by the non-linear function, so that the pitch of the barrel contour and the pitch of the corrected barrel contour at a transition point from the barrel contour to the corrected barrel contour are identical.

Description

Roll mill for the production of rolled strip or sheet metal

The invention relates to a rolling stand for the production of rolled strip or sheet metal with work rolls, which are supported on support rolls or intermediate rolls and backup rolls, wherein the work rolls and / or intermediate rolls are arranged axially displaceable against each other in the rolling stand and each working and / or intermediate roll over the entire having effective bale length, curved, describable by a trigonometric function bale contour and complement these two bale contours complementary only in a certain relative axial position of the rollers of the roller pair in the unloaded state.

In the case of four-high rolling stands or six-high rolling stands, it is common practice to equip at least the two work rolls or the two intermediate rolls with a special bale contour and to provide axially acting adjusting devices for these work rolls or backup rolls in order to be able to set the roll gap contour as a function of the current rolled strip profile.

A roll stand of the generic type is already known from AT 410765 B. The roll bale contour of these rollers known in the art under the name SmartCrown® is mathematically describable by a modified sine function. By a suitable choice of the contour parameters, this results in a cosinusoidal idling gap, which can be influenced in its amplitude by axial displacement of the rollers.

When using work rolls or intermediate rolls with this special bale contour and cylindrically shaped back-up rolls in four-high or six-high rolling stands, as is usual in the normal case, it is unavoidable that during continuous rolling operation inhomogeneous load distributions between the back-up rolls and the immediately adjacent rolls. Since the crown area to be covered with the aid of the contoured rolls is always determined by the requirements of the rolling process, for example by different process parameters, dimensions and deformation properties of the rolling stock, the displacement stroke of the contoured rolls is the only one Influence variable with which the expressiveness of the inhomogeneity of the load distribution can be influenced.

The object of the present invention is therefore to avoid the disadvantages of the prior art described above and to propose a rolling stand, in which to minimize inhomogeneities in the load distribution along the line of contact of the support rollers and their adjacent rollers, and in particular to reduce local load peaks in the load distribution curve and thus the duration of use To increase the rollers and the necessary regrinding intervals.

This object is achieved in a rolling stand of the type described above in that the support rollers have a complementary bale contour and in the unloaded state, a partial or complete complement of the bale contours of the support rollers and the immediately adjacent work rolls or intermediate rolls occurs.

In a quartz scaffolding, this partial or complete complement of the bale contours refers to the two back-up rolls and the respective adjacent work rolls. In a sexto scaffolding, this partial or complete complement of the bale contours refers to the two back-up rolls and the respective adjacent intermediate rolls.

From a process engineering point of view, the shortest possible displacement stroke of the work rolls is advantageous, since both the displacement time and the plant technology to be provided for sliding guides can be kept short. However, a short displacement stroke leads to larger diameter differences over the bale length occurring with a given profile adjustment range of the work rolls than with a longer displacement stroke. These disadvantages of a short displacement stroke can be significantly reduced by the complementary complement of the bale contours of backup rolls and adjacent rolls.

The rolls in the roll stand are aligned according to a possible embodiment of the invention so that a complete complement of the bale contours of the backing rolls and the immediately adjacent work rolls or intermediate rolls occurs in the unshifted state of the immediately adjacent work rolls or intermediate rolls.

Since the maximum displacement stroke is, however, usually much smaller than the roll barrel length, occur in a shifted state of the rolls in unloaded state between the rollers much smaller gap than in cylindrical support rollers, whereby it comes in any operating condition to an approximately homogeneous load distribution between the rollers.

According to another possible embodiment of the invention, the underlying

Problem solved even if an incomplete complement of the bale contours of the

Back-up rolls and the immediately adjacent work rolls or intermediate rolls in the unmoved state of the immediately adjacent work rolls or

Intermediate rolling occurs under the condition that at a support roller radius R _B (X) according to the formula R _B (x) = R ₀ + kr _B (x) with

R _B (X) support roller radius at the point x of the axial support roller extension,

R ₀ radius offset, r _B (x) contour at the point x of the axial support roll extension and k correction factor, the correction factor k is set in the interval 0 <k ≤ 2 excluding the value k = 1.

This formalism can be seen starting from a consideration of the geometric relationships in a complete complement of the roll bale contours of a back-up roll and its adjacent roll.

In a complete complement of the roll bale contour of the backup roll and the adjacent roll (intermediate roll or work roll) are the axes of the two

Rollers in unloaded condition parallel. For the radii of the rollers this means: A with

R _N (x) radius of neighbor roll at location x

R _B (X) radius of the support roller at the position x

A center distance

By defining the contour of the working or intermediate roller so that the contour of the support roller is completely determined in this case. The radius is composed of an offset value R ₀ and the actual contour r _B , which represents a modified sine function: R _B (X) = A - R _N (X) = R ₀ + r _B (x) With

R ₀ radius offset r _B (x) contour at position x

An incomplete complement therefore occurs when the contour function r _B by a

Correction factor k is modified. It follows:

R _B (x) = R ₀ + kr _B (x) with k contour factor (k ≠ 1)

For the case k = 1, the complete complement of the roll bale contours results. In the case of a deviation of the contour factor k from the value k = 1, a complete completion of the roll bale contours is no longer possible. The contour factor may be greater or less than 1. The position of the extreme points and the turning points of the roll bale contour remain unchanged. If the contour factor k assumes the value 0, the backup roll bale contour becomes cylindrical. A sufficient minimization of the inhomogeneities in the load distribution along the roll bale contour is achieved with correction factors in the selected range 0 <k ≦ 2, excluding the value k = 1.

To avoid inadmissibly high edge pressures between work rolls and back-up rolls or between intermediate rolls and back-up rolls, bale ends of the rolls are usually chamfered and thus have an exemption in these edge regions. Exemptions of this type are already known from EP 0 258 482 A1 or EP 1 228 818 A2. These exemptions are formed in contoured roll bales in marginal areas with increasing towards the edge bale radius by a cylindrical bale end, as shown in EP 0 258 482 A1 or may be formed in rolls with cylindrical roll bale contour by a cone-shaped edge region, as for example in the EP 1 228 818 A2 is shown and described. In any case, these known exemptions only result in a shift of the critical pressure from the bale ends (edges) to the transitional area between the remaining bale contour and the contour of the chamfer, since in this embodiment the chamfering again occurs in the contour of the roll bale.

In order to further equalize the load on the end areas of the roll bales and thus reduce peak loads by pressing, the bale contour of the work rolls or of the intermediate rolls or of the support rolls in at least one of Edge regions of their longitudinal extent chamfers, which form in this border areas corrected bale contours, which result by subtracting any mathematical chamfering function of the contour function, the slope of the bale contour and the slope of the corrected bale contour in the transition point from the bale contour to the corrected bale contour are the same.

Very good results in terms of minimization and equalization of the load distribution are achieved when the chamfering function is formed by a circular function. Similarly good results are achieved if the chamfering function is formed by a sine function or a second-order function, for example a parabolic function.

Further advantages and features of the present invention will become apparent from the following description of non-limiting embodiments, reference being made to the attached figures, which show:

1 is a schematic representation of a four-high stand with contoured work rolls and cylindrical support rolls according to the prior art,

2 shows the typical load distribution between work rolls and support rolls in a four-high stand according to FIG. 1, FIG.

Fig. 3 is a schematic representation of a four-high stand with contoured work rolls and complementary back-up rolls according to the invention.

4 shows the typical load distribution between work rolls and support rolls in a four-high stand with the roll formation according to the invention according to FIG. 3, FIG.

5 is a schematic representation of a six-high stand with contoured backup rolls and complementary intermediate rolls according to the invention,

6 is a schematic representation of a four-high stand with contoured work rolls and complementary back-up rolls according to the invention with a correction factor k = 0.75. Fig. 7 shows the inventive contour of the upper support roller with a circular chamfer compared with a bale contour according to the prior art.

In FIGS. 1 to 4, the load distribution between back-up rolls and work rolls in a roll bale contour according to the prior art is compared with the load distribution between back-up rolls and work rolls in a roll bale contour according to the invention using the example of a four-high stand.

1 shows a schematic representation of the roll arrangement in a four-high stand for rolling a metal strip B, in particular a steel strip with work rolls 1 and back-up rolls 2. The axially displaceable work rolls 1 each have a bale contour 3 that can be described by a modified sine function. These bale contours 3 complement each other in a certain relative axial position of the rolls of the pair of work rolls complementary. The work rolls 1 are supported by support rollers 2, which have a cylindrical bale contour 4 and are supported on the work rolls acting rolling forces. The load distribution between the upper work roll 1 and the upper support roll 2 is shown in Figure 2 for this case of roll barrel design, where the specific force between the rolls is plotted over the bale length and on the one hand load peaks in the edge region and, on the other hand, maximum and minimum values corresponding to the sinusoidal Contouring occur. For four selected values of the maximum relative axial displacement (displacement stroke) of the work rolls relative to each other, load distribution curves are shown.

FIG. 3 shows a schematic representation of the roll arrangement in a four-high stand with work rolls 1 and support rolls 2. The axially displaceable work rolls 1 each have a bale contour 3 which can be described by a modified sine function, these bale contours being complementary in a specific relative axial position of the work rolls complete. The two support rollers 2 also have a complementary complementary bale contour 4, which is also formed by a modified sine function, the bale contours of the adjacent, cooperating work roll 1 and support roller 2 completely complement each other in an unloaded state. The load distribution between the upper work roll 1 and the upper backup roll 2 is shown in FIG. 4 for this case of the roll bale design. Load peaks in the edge area appear differently depending on the axial displacement. Altogether it shows over the rolling ball course at the However, the invention already a basic equalization of the load distribution.

FIG. 5 shows, in a schematic arrangement, the roller arrangement in a six-high stand with work rolls 1, intermediate rolls 5 and support rolls 2, the work rolls being supported on the support rolls via the intermediate rolls. The work rolls 1 are equipped with a cylindrical bale contour 3. According to another possible embodiment, however, the bale contour of the work rolls can also be oriented to the bale contour of the adjacent intermediate rolls. The intermediate rollers 5 have a bale contour 6 that can be described by a modified sine function. Likewise, the support rollers 2 have a bale contour 4 that can be described by a sine function. The bale contours 4 of the support rollers 2 and the bale contour of the intermediate rollers 5 complement each other completely in the unshifted axial position of the axially adjustable intermediate rollers 5 in the unloaded state.

FIG. 6 shows work rolls 1 and support rolls 2 in a four-high stand in a schematic representation, the basic structure of the bale contours 3, 4 following the embodiment according to FIG. However, the contour curve is changed by a contour factor k = 0.75, whereby only a partial completion of the bale contours of the support roller 2 and the immediately adjacent work roll 1 occurs in the unloaded state.

According to an embodiment, not shown, it is equally possible for a sexto-frame analogous to Figure 5, to change the contour of the support rollers and the intermediate rollers by a correction factor k, which in the unloaded state only a partial complement of the bale contours of the support roller and the immediately adjacent Intermediate roller occurs.

FIG. 7 shows the course of the roll bale contour 7 of a back-up roll or intermediate roll or work roll over the length of the bale. With dash-dotted lines 8, 9 known from the prior art possibilities of chamfering a roller in the end regions are shown to avoid high edge pressures. The chamfering according to the dotted line 8 produces a cylindrical end portion and the chamfering corresponding to the dotted line 9 a cone-shaped end portion of the rollers, in both cases a kink 10 in the contour over the bale length occurs, which forms a circumferential edge on the roller. An improvement in the Loading conditions result from a chamfer gradually approaching chamfer, resulting in both sides of a corrected bale contour, which is illustrated by the dotted lines 11 and 12. At the transition point P of the bale contour in the corrected bale contour both curves have the same slope as the tangent t.

Claims

claims: 1. rolling stand for the production of rolled strip or sheet metal with work rolls, which are supported on back-up rolls or intermediate rolls and back-up rolls, wherein the work rolls and / or intermediate rolls in the rolling stand against each other are arranged axially displaceable and each working and / or intermediate roll over the entire effective bale length extending, curved, describable by a trigonometric function bale contour and these two bale contours complement each other exclusively in a specific relative axial position of the rollers of the roller pair in the unloaded state, characterized in that the support rollers have a complementary bale contour and in the unloaded state, a partial or complete Complementing the bale contours of the backup rolls and the immediately adjacent work rolls or intermediate rolls occurs. 2. Roll stand according to claim 1, characterized in that a complete complement of the bale contours of the support rollers and the immediately adjacent work rolls or intermediate rolls in the unshifted state of the immediately adjacent work rolls or intermediate rolls occurs. 3. Roll stand according to claim 1, characterized in that an incomplete complement of the bale contours of the support rollers and the immediately adjacent work rolls or intermediate rolls in the unshifted state of the immediately adjacent work rolls or intermediate rolls under the condition that at a Stützwalzenradius R _B (X) corresponding to formula RB (X) = Ro + kr _B (x) With R _B (x) Support roller radius at the point x of the axial support roller extension R ₀ radius offset r _B (x) contour at the point x of the axial support roller extension k Correction factor the correction factor k in the interval 0 <k <2 with the exclusion of the value k = 1. 4. Rolling mill according to one of the preceding claims, characterized in that the bale contour of the work rolls or the intermediate rolls or the support rollers has chamfers in at least one of the edge regions of their longitudinal extent and form in these edge regions corrected bale contours, which differ by subtracting any mathematical chamfering of the Contour function, wherein the slope of the bale contour and the slope of the corrected bale contour in the transition point from the bale contour to the corrected bale contour are the same. 5. Roll stand according to claim 4, characterized in that the chamfering function is a circular function. 6. rolling stand according to claim 4, characterized in that the Chamfer function is a sine function. Roll stand according to claim 4, characterized in that the chamfering function is a 2nd order function.