EP2026916B1 - 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

The invention relates to a rolling stand for the production of rolled strip or sheet metal with work rolls, which are supported on backup 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 rolling stand of the generic type is already out of EP-A 0258482 known. The roll bale contour of the in the professional world under the name SmartCrown® from eg the AT 410765B known rollers can be mathematically described 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 quarto or six-high rolling stands, as is usual in the normal case, it is unavoidable that during continuous rolling operation inhomogeneous load distributions occur 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.

Object of the present invention is therefore to avoid the disadvantages of the prior art described above and to propose a rolling mill, to minimize the inhomogeneities in the load distribution along the contact line of the support rollers and their adjacent rollers and in particular 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 by a rolling mill with the features of claim 1 in combination.

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 rollers in the rolling stand are aligned according to a possible embodiment of the invention so that a complete complement of the bale contours of the back-up rolls and the immediately adjacent work rolls or intermediate rolls in the unshifted state of the immediately adjacent work rolls or intermediate rolls occurs.

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 object is also achieved when an incomplete complement of the bale contours of the backing rolls 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) 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.

mit

R_N(x)

Radius der Nachbarwalze an der Stelle x

R_B(x)

Radius der Stützwalze an der Stelle x

A

Achsabstand

In a complete complement of the roll bale contour of the backing roll and the adjacent roll (intermediate roll or work roll) are the axes of the two rolls in the unloaded state parallel. For the radii of the rollers this means: $${\mathrm{R}}_{\mathrm{N}}\left(\mathrm{x}\right)\mathrm{+}{\mathrm{R}}_{\mathrm{B}}\left(\mathrm{x}\right)\mathrm{=}\mathrm{A}$$

With

R _N (x)

Radius of the neighbor roller at the point x

R _B (x)

Radius of the support roller at the point x

A

Wheelbase

mit

R₀

Radiusoffset

r_B(x)

Kontur an der Stelle x

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: $${\mathrm{R}}_{\mathrm{B}}\left(\mathrm{x}\right)\mathrm{=}\mathrm{A}\mathrm{-}{\mathrm{R}}_{\mathrm{N}}\left(\mathrm{x}\right)\mathrm{=}{\mathrm{R}}_{\mathrm{0}}\mathrm{+}{\mathrm{r}}_{\mathrm{B}}\left(\mathrm{x}\right)$$

With

R ₀

radius offset

r _B (x)

Contour at the point x

mit

k

Konturfaktor (k ≠ 1)

An incomplete complement therefore occurs when the contour function r _B is modified by a correction factor k. It follows: $${\mathrm{R}}_{\mathrm{B}}\left(\mathrm{x}\right)\mathrm{=}{\mathrm{R}}_{\mathrm{0}}\mathrm{+}\mathrm{k}\mathrm{,}{\mathrm{r}}_{\mathrm{B}}\left(\mathrm{x}\right)$$

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 kind are from the EP 0 258 482 A1 or the EP 1 228 818 A2 already known. These exemptions are formed in contoured roll bales in marginal areas with increasing towards the edge bale radius by a cylindrical bale end, as in the EP 0 258 482 A1 is shown 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, it comes with these known exemptions only to a Vorlagerung the critical pressure from the bale ends (edges) to the transition region between the remaining bale contour and the contour of the chamfer, since in this embodiment of chamfering again occurs a kink in the contour of the roll bale.

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.

Fig. 1

die schematische Darstellung eines Quarto-Gerüstes mit konturierten Arbeitswalzen und zylindrischen Stützwalzen gemäß dem Stand der Technik,

Fig. 2

die typische Lastverteilung zwischen Arbeitswalzen und Stützwalzen in einem Quarto-Gerüst gemäß Figur 1,

Fig. 3

die schematische Darstellung eines Quarto-Gerüstes mit konturierten Arbeitswalzen und komplementären Stützwalzen.

Fig. 4

die typische Lastverteilung zwischen Arbeitswalzen und Stützwalzen in einem Quarto-Gerüst gemäß Figur 3,

Fig. 5

die schematische Darstellung eines Sexto-Gerüstes mit konturierten Stützwalzen und komplementären Zwischenwalzen,

Fig. 6

die schematische Darstellung eines Quarto-Gerüstes mit konturierten Arbeitswalzen und komplementären Stützwalzen mit einem Korrekturfaktor k=0,75,

Fig. 7

die erfindungsgemäße Kontur der oberen Stützwalze mit einer kreisförmigen Anfasung im Vergleich mit einer Ballenkontur gemäß Stand der Technik.

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:

Fig. 1

1 is a schematic representation of a quarto stand with contoured work rolls and cylindrical support rolls according to the prior art;

Fig. 2

the typical load distribution between work rolls and back-up rolls in a four-high stand according to FIG. 1 .

Fig. 3

the schematic representation of a four-high stand with contoured work rolls and complementary support rollers.

Fig. 4

the typical load distribution between work rolls and back-up rolls in a four-high stand according to FIG. 3,

Fig. 5

the schematic representation of a six-high stand with contoured backup rolls and complementary intermediate rolls,

Fig. 6

the schematic representation of a quarto-framework with contoured work rolls and complementary back-up rolls with a correction factor k = 0.75,

Fig. 7

the inventive contour of the upper support roller with a circular chamfer compared with a bale contour according to the prior art.

In the FIGS. 1 to 4 The load distribution between back-up rolls and work rolls in a prior art roll bale contour is contrasted 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.

FIG. 1 shows a schematic representation of the roller assembly in a four-high stand for rolling a metal strip B, in particular a steel strip with work rolls 1 and support rollers 2. The axially displaceable work rolls 1 each have a writable by a modified sine function bale contour 3. 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 in this case the roll bale design in FIG. 2 shown, wherein the specific force between the rollers over the bale length is applied and on the one hand load peaks in the edge region emerge and on the other hand maximum and minimum values corresponding to the sinusoidal contour curve 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 support roll 2 is in this case the roll bale design in FIG. 4 shown. 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 assembly in a SextoGerüst with work rolls 1, intermediate rolls 5 and back-up rolls 2, wherein the work rolls are supported on the intermediate rolls on the support rollers. 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 back-up rolls 2 in a four-high stand in a schematic representation, the basic structure of the bale contours 3, 4 follows the embodiment of Figure 3. 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 the same for a sexto scaffold analogous to FIG. 5 possible to change the contour of the support rollers and the intermediate rollers by a correction factor k, whereby in the unloaded state only a partial complement of the bale contours of the support roller and the immediately adjacent intermediate roller occurs.

In FIG. 7 the course of the roll bale contour 7 of a back-up roll or intermediate roll or work roll over the bale length is shown. 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 (6)

1. Rolling mill stand for the production of rolled strip or sheet metal, with working rolls which are supported on supporting rolls or intermediate rolls and supporting rolls, the working rolls and/or intermediate rolls being arranged in the rolling mill stand so as to be displaced axially with respect to one another, and each working and/or intermediate roll having a curved barrel contour which runs over the entire effective barrel length and can be described by a trigonometric function, and these two barrel contours completing one another in a complementary way, in the non-loaded state, solely in one specific relative axial position of the rolls of the pair of rolls, the supporting rolls having a complementary barrel contour, and a partial or full completion of the barrel contours of the supporting rolls and of the directly adjacent working rolls or intermediate rolls occurring in the non-loaded state, the barrel contour of the working rolls or the intermediate rolls or the supporting rolls having chamfers in at least one of the marginal regions of its longitudinal extent and in these marginal regions corrected barrel contours form which are obtained by subtracting any mathematical chamfer function from the contour function, characterized in that the pitch of the barrel contour and the pitch of the corrected barrel contour at the transition point from the barrel contour to the corrected barrel contour are identical.
2. Rolling mill stand as claimed in Claim 1, characterized in that a full completion of the barrel contours of the supporting rolls and of the directly adjacent working rolls or intermediate rolls occurs in the nondisplaced state of the directly adjacent working rolls or intermediate rolls.
3. Rolling mill stand as claimed in Claim 1, characterized in that an incomplete completion of the barrel contours of the supporting rolls and of the directly adjacent working rolls or intermediate rolls occurs in the nondisplaced state of the directly adjacent working rolls or intermediate rolls, on the condition that, in the case of a supporting roll radius R_B(x) according to the formula $${\mathrm{R}}_{\mathrm{B}}\left(\mathrm{x}\right)\mathrm{=}{\mathrm{R}}_{\mathrm{0}}\mathrm{+}\mathrm{k}\mathrm{.}{\mathrm{r}}_{\mathrm{B}}\left(\mathrm{x}\right),$$

   

   
   where
   R_B(x) is the supporting roll radius at the point x of the axial supporting roll extent,
   R₀ is the radius offset,
   r_B(x) is the contour at the point x of the axial supporting roll extent,
   k is a correcting factor,
   the correcting factor k being fixed in the interval 0 < k ≤ 2, excluding the value k=1.
4. Rolling mill stand as claimed in Claim 1, characterized in that the chamfer function is a trigonometric function.
5. Rolling mill stand as claimed in Claim 1, characterized in that the chamfer function is a sine function.
6. Rolling mill stand as claimed in Claim 1, characterized in that the chamfer function is a second order function.

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