EP1879706B1 - Method of rolling a metal strip - Google Patents

Abstract

The invention relates to a rolling stand, a rolling train and a method of rolling a metal strip preprofiled in a stepped manner. In order to ensure that the metal strip is free from corrugations in the longitudinal direction of the metal strip even after a thickness reduction with respect to individual steps, it is proposed according to the invention that the thickness reduction be carried out with respect to specific steps while taking into account the following mathematical interrelationship: Δhj/hj = Δhi+i/hi+1 = ε = constant, where Δhj represents the amount of thickness reduction in the region of the ith step and hι represents the size of the resulting thickness of the metal strip 200 after the rolling in the region of the ith step.

Description

The invention relates to a method for using a roll stand for the stepped rolling of a metal strip, in particular of steel, aluminum, copper or a copper alloy. The invention further relates to a method of using a rolling train with at least one such rolling stand.

Roll stands and methods for producing step-shaped thickness profiles across the width of a band-shaped metal strip are in the prior art, for example from the German Offenlegungsschrift DE 198 31 882 A1 or the German patent DE 101 13 610 C2 basically known. In order to produce the desired thickness profile, eg step profile, the two documents recommend that the metal strip, which originally has a rectangular cross-section, be rolled longitudinally with a plurality of pressure rolls offset in the rolling direction. The offset in the transport direction of the metal strip or juxtaposed pressure rollers each press into the supported by a support means metal strip and deform it in this way as desired in the width direction.

The pressure rollers proposed for use in said publications allow only a locally very limited processing of the metal strip in a narrow range in the width direction; It is therefore, as I said, a plurality of such pressure rollers in a staggered arrangement required, for. to roll wider steps into the metal band. Due to the large number of required pressure rollers and their staggered arrangement, the structure of such known rolling stands for realizing step profiles in metal bands is quite expensive.

Based on this state of the art, the invention is based on the object as simple as possible, a step-shaped pre-profiled metal strip in the To further reduce the height of its stages by rolling, without thereby forming waves on the metal strip in its longitudinal direction.

This object is achieved by the method claimed in claim 1. This method is characterized in that the at least two adjacent sub-rollers are each cylindrical in shape and together with the support means each adjacent Teilwalzspalte with different sizes h _i , h _{i + 1} with h _i ≠ h _{i + 1} and i = 1, 2,. .., I span, wherein the adjacent partial roll gaps together define the Gesamttwalzspaltquerschnitt, which is step-shaped and that the sizes of each adjacent Teilwalzspalten are individually chosen so that it is geometrically in terms of rolling into the Gesamttalzspalt metal strip, which before rolling similar to the Gesamttwalzspaltquerschnitt stepwise pre-profiled, but in each case greater step heights of h _i + Δh _i and h _{i + 1} + Δh _{i + 1} with h _i + Δh _i ≠ h _{i + 1} + Δh _{i + 1} and Δh _i > 0 and Ah _{i + 1} > 0 than the partial rolling gap (i), satisfy the following law: $${\mathrm{.delta.h}}_{\mathrm{l}}\mathrm{/}{\mathrm{H}}_{\mathrm{i}}\mathrm{=}{\mathrm{.delta.h}}_{\mathrm{i}\mathrm{+}\mathrm{1}}\mathrm{/}{\mathrm{H}}_{\mathrm{l}\mathrm{+}\mathrm{1}}\mathrm{=}\mathrm{\epsilon }\mathrm{=}\mathrm{constant}\mathrm{,}$$

In a reduction in thickness of the step-shaped pre-profiled metal strip according to the claimed law, the material rolled off from the height of the metal strip or the material flow resulting therefrom is evenly distributed in the longitudinal direction of the metal strip, advantageously without corrugation.

The inventively used for this mill stand is structurally simple and space-saving, because it has only transversely to the direction of the metal strip juxtaposed part rollers, but not a plurality of staggered in the direction of running part rollers.

The term that the sub-rollers are arranged "at the same height" next to each other, means that the side rollers arranged side by side on one side the metal strip are not offset in the transport direction of the metal strip to each other.

The claimed step-shaped pre-profiling of the metal strip in approximation to the step-shaped Cesamtwafzspaltquerschnitt the inventive βen rolling stand is imperative because otherwise no different size step heights transversely to the transport direction in the incoming metal strip could be distinguished and the metal strip then transverse to its transport direction only a uniform thickness h _i = h _{i + 1} = constant. According to the claimed law, then Δh _i = Δh _{i + 1} ; this would then be the case of a uniform thickness reduction over the entire width of the metal strip, which is not the subject of the invention. In contrast, the invention relates only to the reduction in thickness of vorprofilierlen step profiles, the beneficial effect that the resulting metal strip is wave-free, only occurs when the thickness reductions for the individual steps are calculated and carried out transversely to the transport direction of the metal strip in compliance with the claimed legality.

According to a first exemplary embodiment, it is advantageous if the setting of the sizes of the partial rolling gaps is carried out automatically with the aid of a setting device with knowledge of the step heights of the incoming stepped pre-profiled metal strip. When changing the step heights of the incoming metal strip can then be done very quickly an adjustment of the sizes of Teilwalzspalte using the Anstelleinrichtung.

Advantageous embodiments of the rolling process are specified in the subclaims.

Advantageously, the rolling stand used is designed for hot rolling or cold rolling of the metal strip,

The above object of the invention is further achieved by a method for using a rolling train, in particular a tandem system. This rolling train then comprises a first roll stand with profile or caliber rolls for the step-shaped pre-profiling of the metal strip. The first rolling stand or roughing stand is then followed by at least one second rolling stand in the running direction of the metal strip. In the at least one downstream roll stand then takes place a reduction in thickness of the stepped metal strip, wherein the heights of the individual adjacent stages are individually reduced according to the claimed law. The second rolling mill can be followed by further rolling mills. The upstream rolling stands then take over the necessary provision of a stepped pre-profiling of the metal strip for the downstream rolling stands. A plurality of successively arranged rolling stands is required in particular if the metal strip is to be reduced very greatly in its thickness. Alternatively, a large reduction in thickness can also be realized by a single reversing stand.

The above object is further achieved by a method according to claim 7.

Figur 1

ein erstes Ausführungsbeispiel für das efindungsgemäße Verfahren zur Verwendung eines Walzgerüstes;

Figur 2

einen Querschnitt für das erste Ausführungsbeispiel gemäß Figur 1;

Figur 3a

einen Querschnitt des Metallbandes nach Verlassen des Walzgerüstes gemäß dem ersten Ausführungsbeispiel;

Figur 3b

einen alternativen Querschnitt des Metallbandes nach Verlassen des Walzgerüstes;

Figur 4

ein zweites Ausführungsbeispiel für das erfindungsgemäße Verfahren zur Verwendung eines Walzgerüstes;

Figur 5

einen Querschnitt des Walzgerüstes gemäß dem zweiten Ausführungsbeispiel; und

Figur 6

einen Querschnitt durch das Metallband nach Verlassen des Walzgerüstes gemäß dem zweiten Ausführungsbeispiel

zeigt.The invention is a total of 6 figures attached, wherein

FIG. 1

a first embodiment of the efindungsgemäße method for using a rolling mill;

FIG. 2

a cross section for the first embodiment according to FIG. 1 ;

FIG. 3a

a cross section of the metal strip after leaving the rolling stand according to the first embodiment;

FIG. 3b

an alternative cross section of the metal strip after leaving the mill stand;

FIG. 4

A second embodiment of the inventive method for using a rolling mill;

FIG. 5

a cross section of the rolling stand according to the second embodiment; and

FIG. 6

a cross section through the metal strip after leaving the mill stand according to the second embodiment

shows.

The invention will now be described in detail in the form of embodiments with reference to said figures. In all figures, identical components are designated by the same reference numerals.

wobei

Δh_i:

die Dickenreduktion des Metallbandes durch das Walzgerüst im Bereich der i'ten Teilwalze bzw. Stufe; und

h_i:

die Größe des i'ten Teilwalzspaltes bzw. die Dicke des aus dem Walzgerüst auslaufenden Metallbandes im Bereich der i'ten Stufe.

FIG. 1 shows a first embodiment of the rolling process according to the invention. The rolling stand 100 here comprises, by way of example, three sub-rollers 110-i, which are arranged transversely to the transport direction (perpendicular to the plane of the paper) of the metal strip 200, where i = 1, 2 and 3. The sub-rollers are arranged side by side at the same height, ie they are not offset in the transport direction of the metal strip , The three sub-rollers 110-i span together with one opposite arranged support means 120, for example in the form of a support roller, respectively adjacent Teilwalzenspalte i = 1, i = 2 and i = 3 with the sizes h _i with i = 1, 2 and 3. It is important here that at least two respectively adjacent partial salt gaps i, i + 1 each have different sizes h _i , h _{i + 1} with h _i not equal to h _{i + 1} . The two outer sub-rollers 110-1, 110-3 are in FIG. 1 For example, they are mounted on a common axis A and, if appropriate, are therefore also positioned in each case in the same way and to the same extent relative to the support device 120. The employment of the individual sub-rollers 110-i with respect to the support device 120 is advantageously carried out automatically with the aid of a Anstelleinrichtung 130, but always in compliance with the claimed law: $${\mathrm{.delta.h}}_{\mathrm{i}}\mathrm{/}{\mathrm{H}}_{\mathrm{l}}\mathrm{=}{\mathrm{.delta.h}}_{\mathrm{i}\mathrm{+}\mathrm{1}}\mathrm{/}{\mathrm{H}}_{\mathrm{l}\mathrm{+}\mathrm{1}}\mathrm{=}\mathrm{\epsilon }\mathrm{=}\mathrm{constant}\mathrm{.}\mathrm{m}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{=}\mathrm{1}\mathrm{.}\mathrm{2}\mathrm{...}\mathrm{I}$$

in which

Δh _i :

the reduction in thickness of the metal strip through the roll stand in the region of the first part roll or step; and

_hi :

the size of the i'ten Teilwalzspaltes or the thickness of the expiring from the rolling mill metal strip in the region of i'ten stage.

FIG. 2 shows a side view of the in FIG. 1 shown first embodiment of the mill stand 100. As already in FIG. 1 As can be seen, the middle sub-roller 110-2 is not supported on the axle 112-5. Instead, she is as in FIG. 2 shown rotatably mounted in a separate roller cage 112. In addition, with the aid of the adjusting device 130, it can also be adjusted individually relative to the supporting device 120 independently of the two outer partial rollers 110-1 and 110-3. In FIG. 2 the transport direction of the metal strip is indicated with an arrow to the right and au-βerdem is the resulting reduction in thickness, especially in the region of the middle part roller 110-2, clearly visible.

The FIGS. 3a and 3b show possible profiles of the metal strip 200 after leaving the roll stand 100. These profiles correspond to the Gesamtwalzspaitquerschnittquerschnitt of the roll stand 100 formed by the adjacent partial roll gaps i = 1, 2, 3 respectively.

FIG. 4 shows a second embodiment of the rolling process according to the invention. It differs from the first embodiment only in that the support means 120 is no longer in the form of a single cylinder, but is formed in mirror image to the sub-rollers on the opposite side of the metal strip. The sub-rollers 120-1, 120-2 and 120-3 each have the same bale length as the mirror-opposing sub-rollers 110-1, 110-2 and 110-3. The partial rollers 120-i with i = 1, 2... I are also all individually adjustable with respect to the metal strip 200. By way of example only, the two outer sub-rollers 120-1 and 120-3 are employed via a common axis 120-5 opposite the metal belt 200 and opposite the opposed metal rollers, respectively. The from the opposite arrangement of the sub-rollers 110-1, 120-1; 110-2, 120-2; 110-3, 120-3 resulting Teilwalzspalte have heights of h ₁ , h ₂ and h ₃ .

FIG. 5 shows the storage of the two middle sub-rollers 110-2 and 120-2 respectively in suitable roller cages 112.

FIG. 6 finally shows the expiring from the roll stand according to the second embodiment of metal strip 200 in a cross-sectional view.

The method according to the invention for rolling a metal strip with the aid of the above-described rolling stands will be described below:

According to this method, in a first step, the originally typically rectangular-shaped, non-profiled metal strip is first pre-profiled stepwise in a roughing stand. This pre-profiling takes place in geometric approximation to the total rolling cross-section of the downstream rolling stand 100. In particular, the steps are formed in the metal strip 200 with a step width, which at least approximately the bale length of the individual sub-rollers 110-1, 110-2 and 110-3 of the downstream rolling stand equivalent. However, the heights h _i + Δh _i with i = 1, 2, 3 ... of the steps of the metal strip after the pre-profiling are still greater than the sizes h _i , h _{l + 1 of} the adjacent partial roll gaps i, i + 1 in the downstream one Rolling stand 100. The step-shaped pre-profiled metal strip then enters the mill stand 100 and is reduced in thickness in the region of each individual part-roll 110-i in accordance with equation (1). The reduction in thickness in accordance with the equation (1) offers the advantage that the metal strip does not have any waves in the longitudinal direction after leaving the rolling stand.

The application of the formula according to the invention is illustrated below by way of example: It is assumed that the metal strip is a rolling stand according to FIG. 1 should pass through and accordingly has three stages transverse to its transport direction. The heights of the individual steps of the metal strip after leaving the pre-profiling are given with H1 = Δh ₁ + h ₁ = 10 mm for the area of the first outer sub-roller 110-1, with H2 = Δh ₂ + h ₂ = 7 mm for the area of the middle sub-roller 110 -2 and with H3 = Δh ₃ + h ₃ = 10mm for the area of the second outer sub-roller 110-3.

For the application of the method according to the invention it is now assumed that the desired thickness h _{1 of} the metal strip 200 for the area of a sub-roller 110-i or a stage after passing through the rolling stand is fixed. By way of example, it is assumed here that the thickness of the metal strip in the area of the first outer dividing roller 110-1 after passing through the rolling stand is only h ₁ = 7 mm should. In regard to the step height of H1 = 10mm of the incoming metal strip in this area takes place inevitably therefrom by simple subtraction of the required thickness reduction in the size of .DELTA.h ₁ = H1-h ₁ = 10-7 = 3 mm.

The knowledge of Δh ₁ and h ₁ enables the calculation of the quantity ε according to the formula (1) to: $$\mathrm{\epsilon }={\mathrm{.<figure-callout\; id="1"\; label="delta.h"\; filenames="imgf0001.png"\; state="\{\{state\}\}">delta.h</figure-callout>}}_1\mathrm{/}{\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="imgf0001.png"\; state="\{\{state\}\}">H</figure-callout>}}_1=3/\mathrm{7th}$$

$$\wedge {\mathrm{\Delta h}}_2/{\mathrm{h}}_2=\mathrm{\epsilon }$$

The thickness reduction Δh ₂ in the adjacent Teitwalzspaft i = 2 or in the region of the adjacent part roller 110-2 is now according to the invention by no means arbitrary, but according to the said formula (1) defined exactly. Specifically, the following equation system with equations (3) and (4) is available for the calculation of the required thickness reduction Δh ₂ in this range or for the inevitably resulting step height h _{2 of} the metal strip 200 in this region: $$\mathrm{H}\mathrm{2}={\mathrm{.<figure-callout\; id="2"\; label="delta.h"\; filenames="imgf0001.png"\; state="\{\{state\}\}">delta.h</figure-callout>}}_2+{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="imgf0001.png"\; state="\{\{state\}\}">H</figure-callout>}}_2$$

$$\wedge {\mathrm{.<figure-callout\; id="2"\; label="delta.h"\; filenames="imgf0001.png"\; state="\{\{state\}\}">delta.h</figure-callout>}}_2/{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="imgf0001.png"\; state="\{\{state\}\}">H</figure-callout>}}_2=\mathrm{\epsilon }$$

und $${\mathrm{\Delta h}}_{\mathrm{2}}\mathrm{=}\mathrm{H}\mathrm{2}\mathrm{-}{\mathrm{h}}_{\mathrm{2}}$$

A solution of this equation system leads to the result: $${\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="imgf0001.png"\; state="\{\{state\}\}">H</figure-callout>}}_{\mathrm{2}}\mathrm{=}\mathrm{H}\mathrm{2}\mathrm{/}\left(\mathrm{<figure-callout\; id="1"\; label="\epsilon \; +"\; filenames="imgf0001.png"\; state="\{\{state\}\}">\epsilon \; </figure-callout>}\mathrm{+}\mathrm{}\mathrm{1}\right)$$

and $${\mathrm{.<figure-callout\; id="2"\; label="delta.h"\; filenames="imgf0001.png"\; state="\{\{state\}\}">delta.h</figure-callout>}}_{\mathrm{2}}\mathrm{=}\mathrm{H}\mathrm{2}\mathrm{-}{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="imgf0001.png"\; state="\{\{state\}\}">H</figure-callout>}}_{\mathrm{2}}$$

und bei Einsetzen von h₂ in Gleichung (6) ergibt sich: $${\mathrm{\Delta h}}_2=7-4,9=2,1\mathrm{mm}\mathrm{.}$$

When inserting the value H2 = 7 given for the above example and the value ε = 3/7 calculated as an intermediate result in equation (5), the result is: $${\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="imgf0001.png"\; state="\{\{state\}\}">H</figure-callout>}}_{\mathrm{2}}\mathrm{=}\mathrm{7}\mathrm{/}\left(\mathrm{3}\mathrm{/}\mathrm{7}\mathrm{+}\mathrm{1}\right)\mathrm{=}\mathrm{4}\mathrm{.}\mathrm{9}\mathrm{mm}$$

and when h _{2 is} substituted in equation (6): $${\mathrm{.<figure-callout\; id="2"\; label="delta.h"\; filenames="imgf0001.png"\; state="\{\{state\}\}">delta.h</figure-callout>}}_2=7-4.9=2.1\mathrm{mm}\mathrm{,}$$

In order for the metal strip 200 to leave the rolling mill 100 without shafts, it is necessary for the metal strip in the region of the middle part roll 110-2 to be reduced by 2.1 mm to 4.9 mm in its thickness from its preformed starting thickness of H2 = 7 mm, if it should be reduced in the range of the first part roller 110-1 of H1 = 10mm to h ₁ = 7mm.
With a plurality of juxtaposed sub-rollers transverse to the transport direction of the metal strip, this just performed exemplary calculation of the relative Walzspaftgrößen for each pair of adjacent Teilwalzspalten performed separately.

The invention finds a particularly advantageous use with thin metal bands having an original thickness of less than 10mm. The method according to the invention can be used both during hot rolling and during cold rolling of metal strips. However, the application of this method according to the invention is particularly advantageous during hot rolling, because then a wave-free step profiling of the metal strip can already be realized in a very early production stage. A field of application is e.g. the production of motor base frames for the automotive industry. When cold rolling strip geometries can be realized, which can replace the flexible strip rolling in the presently known form with low production costs. An exemplary area of application here too is the automobile industry, especially the production of underbody panels for automobiles.

Claims (8)

1. Method of using a roll stand (100) for rolling a metal strip (200), wherein the roll stand (100) comprises:

   at least two part rolls (110-i, wherein i = 1, 2 ... I), which are arranged adjacent to one another transversely to the transport direction of the metal strip and at the same height; and a support device (120), which is arranged opposite the at least two part rolls and together therewith defines an overall rolling gap with an overall rolling gap cross-section;

   characterised in that

   the at least two adjacent part rolls (110-i, wherein i = 1, 2 ... I) are each of cylindrical construction and together with the support device define respectively adjacent part rolling gaps (i, i+1) of different sizes h_i, h_i+1, wherein h_i is not equal to h_i+1 and i = 1, 2, ..., I, wherein the adjacent part rolling gaps together define the overall rolling gap cross-section, which is formed to be step-shaped; and

   the sizes h_i and h_i+1 of each two adjacent part rolling gaps (i, i+1) are individually so selected that - with respect to the metal strip (200), which is running into the overall rolling gap and which before rolling is in fact pre-profiled in step-shape with geometric similarity to the overall rolling gap cross-section, but has respectively greater step heights of h₁+Δh₁ and h_i+1+Δh_i+1, wherein h_i+Δh₁ ≠ h_i+1+Δh_i+1 and Δh_i > 0 and Δh_i+1 > 0, than the part rolling gaps (i) - they satisfy the following mathematical relationship: $${\mathrm{\Delta h}}_{\mathrm{i}}\mathrm{/}{\mathrm{h}}_{\mathrm{i}}\mathrm{=}{\mathrm{\Delta h}}_{\mathrm{i}\mathrm{+}\mathrm{1}}\mathrm{/}{\mathrm{h}}_{\mathrm{i}\mathrm{+}\mathrm{1}}\mathrm{=}\mathrm{\epsilon }\mathrm{=}\mathrm{constant}\mathrm{.}$$

   
2. Method according to claim 1, characterised by an adjusting device (130) for flexible adjustment of the part rolls (110-1, 110-2, 110-3) and thus for flexible adaptation of the sizes h_i of the part rolling gaps in accordance with the mathematical relationship to entering metal strip (200) with changed step heights.
3. Method according to one of the preceding claims, characterised in that in total three part rolls in the form of two outer and one middle part rolls (110-1, 110-2, 110-3) are arranged over the width of the metal strip, wherein the two outer part rolls (110-1, 110-3) are preferably connected together by way of a common axle (A).
4. Method according to claim 3, characterised in that the middle part roll (110-2) has a smaller diameter by comparison with the outer part rolls (110-1, 110-3) and is so mounted in a roll cage (112) between the two outer part rolls that the size h₂ of the second part rolling gap i = 2 defined oy the middle part roll (110-2) together with the support device (120) is smaller or larger than the sizes h₁ and h₃ of the two adjacent outer part rolling gaps i = 1 and i = 3.
5. Method according to any one of the preceding claims, characterised in that the support device (120) is similarly constructed in the form of part rolls (120-i, wherein i = 1 ... I), wherein these part rolls (120-i) have the same dimensions as the part rolls (110-i) on the opposite side of the metal strip and are mounted in mirror symmetry with respect to these in relation to the centre plane of the metal strip (200).
6. Method according to any one of the preceding claims, characterised in that the roll stand (100) is constructed for hot-rolling or cold-rolling of the metal strip (200).
7. Method of using a rolling train, particularly a tandem plant, for rolling a metal strip, comprising a plurality of roll stands arranged one after the other in the running direction of the metal strip;
   characterised in that
   a first one of the roll stands is formed with profiling rolls or sizing rolls for step-shaped pre-profiling of the still thicker metal strip;
   at least a second one of the roll stands (100) downstream of the first roll stand is used in accordance with any one of claims 1 to 6; and
   the step-shaped pre-profiling of the metal strip is carried out by the first roll stand in geometric approximation to the step-shaped cross-section of the overall rolling gap of the downstream second roll stand, but with greater step heights of h₁+Δh₁ and h_i+1+Δh_i+1, wherein h_i+Δh₁ ≠ h_i+1+Δh_i+1 and wherein Δh_i > 0 and Δh_i+1 > 0, in the region of the ith and i+1th part rolling gap.
8. Method according to claim 7, characterised by the following step:

   reducing the individual step heights of the pre-profiled metal strip (200) by Δh_i to h_i, wherein i = 1 ... I, by use of the second roll stand (100) in the rolling train.

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