EP1425116B1 - Rolling stand for the production of rolled strip - Google Patents

Description

The invention relates to a rolling stand for the production of rolled strip with work rolls, which optionally supported on backup rolls or backup rolls and intermediate rolls, the work rolls and / or back-up rolls and / or intermediate rolls are arranged axially displaceable against each other in the rolling stand and each roll at least one of these pairs of rolls over has the entire effective bale length extending, curved contour and complement these two bale contours complementary only in a certain relative axial position of the rollers of the pair of rollers in the unloaded state (see, eg EP-A-0 401 685 ).

In order to produce a flat rolled strip with a defined cross-sectional profile, it is necessary to use contour-influencing measures, such as the use of roll bending devices, with which the rolling force application to the strip and the outlet thickness distribution over the strip width can be influenced in a targeted manner.

From the EP-B 0 049 798 A rolling stand of the generic type is already known in which the shape of the roll gap and thus the surface contour of the rolled strip is influenced exclusively by the axial displacement of the rollers formed with curved contours. The two cooperating rollers of a pair of rollers have identical shape, are installed rotated by 180 ° and complement each other in a certain axial displacement position complementary. This special roll grinding makes it possible to compensate for the parabolic roller ball deflection dependent on the respective load conditions under load, so that it no longer requires a necessary roll change with a significant change in the load conditions, which is quite common in rolls with parabolic roller burnishing. In the EP-B 294 544 It is pointed out that the parabolic deflection determined essentially by quadratic parts can be compensated by axially displaceable rollers with the roller contour described, but excessive stretching in the edge regions or in the quarter sections of the rolled strip can lead to edge or quarter wave formation. Although these disadvantages would be manageable with additional roll bending devices, expediently in combination with zone cooling, essential advantages of the rolls contoured in this way would then be lost again.

After EP-B 294 544 In order to avoid this edge or quarter wave formation on the rolled strip, it is proposed that the roll bale contours, which complement each other in an axial displacement position, are formed by a 5th order curve, the respective curves being arranged on the rolls so that they rest in Neutral roll position in both sides of the middle located longitudinal areas each have a maximum and a minimum of the slope of the curves.

The object of the present invention is to provide a further advantageous solution for a roll stand in which the shape of the roll gap, that is to say by axial displacement of the rolls equipped with a roll barrel contour, lies opposite one another. the thickness profile of the roll gap over the active roll barrel length, can be varied such that a top quality fulfilling, flat and wave-free belt is achieved.

This object is achieved according to the invention by a roll stand having the features of claim 1 or 2.

mit

R

Radius der Walze

x

Axialposition bezüglich der Walzenmitte (= Abstand von der Walzenmitte)

R₀

Walzenradiusoffset (=Radius der Walze im Konturwendepunkt)

A

Konturkoeffizient

ϕ

Konturwinkel

c

Konturverschiebung

L_REF

Schliffreferenzlänge

According to the invention, the trigonometric function of the bale contour is formed by a sine function and the nip contour is formed by a cosine function derived therefrom. The bale contour follows the general equation $$R\left(x\right)=R_0+A*\mathit{<figure-callout\; id="2"\; label="sin"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">sin</figure-callout>}\left(\frac{2*\phi *\left(x+c\right)}{L_{\mathit{REF}}}\right)$$

With

R

Radius of the roller

x

Axial position with respect to the roll center (= distance from the roll center)

R ₀

Roll radius offset (= radius of the roll in the contour turning point)

A

contour coefficient

φ

contour angle

c

contour shift

L _REF

Cut reference length

mit

s

Verschiebung der oberen Walze aus der Mittenlage

G₀

Walzspaltoffset

und ergibt sich aus den Konturgleichungen der beiden Walzenballen unter Einbeziehung des Verschiebeweges (s) einer der Walzen aus der Mittenlage.The roll gap contour follows the general equation $$G\left(x,s\right)=G_0+2*A*\cos \left(\frac{2*\phi *x}{L_{\mathit{REF}}}\right)*\sin \left(\frac{2*\phi *\left(s-c\right)}{L_{\mathit{REF}}}\right)$$

With

s

Shifting the upper roller from the center position

G ₀

Nip offset

and results from the contour equations of the two roll bales, including the displacement path (s) of one of the rolls from the center layer.

The contour coefficient A is determined here by the axial displacement region and the corresponding equivalent roll crowns in the extreme positions of the rolls. Equivalent crowning is understood to mean the crowning of conventional, cosinusoidal-ground rolls, which together generate exactly the same idle-gap profile.

By varying the contour angle φ, which refers to half the Schliffreferenzlänge, the current roll contour and thus the course of the roll gap can be influenced without changing the equivalent crowning of the rolls. The positive effect of avoiding quarter wave formation occurs because increasing the contour angle results in a reduction of the roll bale diameter in the area between the roll edge and the roll center, ultimately resulting in less roll deformation in this quarter wave forming critical area.

mit

B

Kippkoeffizient

und die Walzspaltkontur von einer sich davon ableitenden Kosinusfunktion entsprechend der allgemeinen Gleichung $$G\left(x,s\right)=G_0+2*A*\cos \left(\frac{2*\varphi *x}{L_{\mathit{REF}}}\right)*\sin \left(\frac{2*\varphi *\left(s-c\right)}{L_{\mathit{REF}}}\right)+2*B*\left(s-c\right)$$

mit

s

Verschiebung der oberen Walze aus der Mittenlage

G₀

Walzspaltoffset

gebildet.Further, according to the invention, the trigonometric function of the bale contour is a tilted sine function according to the general equation $$R\left(x\right)=R_0+A*\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">sin</figure-callout>}\left(\frac{2*\phi *\left(x+c\right)}{L_{\mathit{REF}}}\right)+B*\left(x+c\right)$$

With

B

tilt coefficient

and the nip contour from a cosine function derived therefrom according to the general equation $$G\left(x,s\right)={\mathrm{<figure-callout\; id="0"\; label="G"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">G</figure-callout>}}_0+2*A*\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">cos</figure-callout>}\left(\frac{2*\phi *x}{L_{\mathit{REF}}}\right)*\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">sin</figure-callout>}\left(\frac{2*\phi *\left(s-c\right)}{L_{\mathit{REF}}}\right)+2*B*\left(s-c\right)$$

With

s

Shifting the upper roller from the center position

G ₀

Nip offset

educated.

By inserting the linear member B * (x + c) in the equation of the bale contour, a tilting of the sine function is made possible and by a suitable choice of the coefficient (B) a minimization of the diameter differences along the bale contour is achieved. The minimization of the diameter differences along the effective roll barrel length achieved by the tilted sine function simultaneously leads to a reduction of the axial forces derived during the rolling process into the roll support bearings. For rolling stands equipped with backup rolls in addition to the bale-shaped work rolls, the optimization of the tilt coefficient leads to a reduction of the maximum local contact pressure on the backup rolls, or more generally to a more even distribution of forces on the adjacent rolls. The tilt coefficient (B) thus causes a smoothing of the contour on the roll barrel and the distribution of forces. Although the introduction of a tilt coefficient into the contour equalization of the roll bales thus influences the loads of the rolls and bearings of the roll stand low, but shows no fundamental influence on the roll gap geometry, as the comparison of the two nip equations on the basis of a sine function and a tilted sine function for the roll bale contour shows.

As can be seen from the above formula for G (x, s), the complementary complement of the two bale contours occurs when the displacement of the upper work roll corresponds to the contour shift c and at the same time a counterparallel displacement of the lower work roll by s = -c. This position can lie both inside and outside the working range of the axial displacement.

An advantageous embodiment of the curved bale contour is obtained if, for a given grinding reference length (L _REF ), a contour angle (φ) corresponding to the condition 0 ° <φ ≦ 180 °, preferably 50 ° ≦ φ ≦ 80 °, is selected for the curved bale contour of the roller , This ensures that, depending on the selected displacement direction, the roll gap steadily decreases or increases starting from a central maximum or minimum value towards the roll edges. At a contour angle φ> 180 ° there is a reversal in the steady decrease or increase of the roll gap in the edge region of the grinding reference length and thus to undesirable influences on the quality of the Rolled strip. As the contour angle approaches the value φ = 0, asymptotically, a parabolic roll gap contour is formed.

Minimizing the axial forces to be dissipated into the roll support bearings occurs approximately when the tilt coefficient (B) in the equation for the bale contour of each roll is selected such that the maximum diameter difference of the bale contours within the slip reference length or bale length is a minimum.

A band quality improving influencing of the rolls can be achieved if in addition further bale contour at least partially influencing actuators in operative position in operative connection with the work rolls and / or back-up rolls and / or intermediate rolls are positioned, such as a work roll cooling or a zone cooling. Corresponding effects can also be realized by roll bending devices or zone-wise connectable heating devices.

In order to ensure continuous control and influencing of the strip quality, an integration of the rolling stand into a profile or flatness control loop is provided. This is achieved in that the work rolls and / or backup rolls and / or intermediate rolls are connected by their associated displacement devices, and optionally necessary measuring devices for detecting the state of the incoming and outgoing tape and optionally additional actuators with a control device for profile or planarity control in that the control device is assigned a computing unit which generates control signals for the tracking of the work rolls and / or back-up rolls and / or intermediate rolls and optionally additional actuators using mathematical models, if necessary using a neural network, and with the work rolls and / or back-up rolls and / or intermediate rollers and possibly additional actuators associated actuators the control signals corresponding positions are approached. The measuring equipment collects band-specific data, such as profile progression, stress conditions, temperature profiles and rolling forces.

Fig. 1

die schematische Darstellung eines Duo-Walzgerüstes mit Arbeitswalzen entsprechend der Erfindung,

Fig. 2

eine schematische Darstellung eines Quarto-Walzgerüstes mit Stützwalzen entsprechend der Erfindung,

Fig. 3

eine schematische Darstellung eines Sexto-Walzgerüstes mit Zwischenwalzen entsprechend der Erfindung,

Fig. 4

die erfindungsgemäße Walzenballenkontur auf der Grundlage einer Sinusfunktion,

Fig. 5

die erfindungsgemäße Walzenballenkontur auf der Grundlage einer gekippten Sinusfunktion,

Fig. 6

eine geometrische Definition des Konturwinkels,

Fig. 7

die Leerwalzspaltkontur in Abhängigkeit vom Konturwinkel,

Fig. 8

die Walzspaltkontur in Abhängigkeit von der Walzenverschiebung s

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

the schematic representation of a duo-mill stand with work rolls according to the invention,

Fig. 2

a schematic representation of a four-high rolling mill with back-up rolls according to the invention,

Fig. 3

a schematic representation of a six-high rolling mill with intermediate rolls according to the invention,

Fig. 4

the roller bale contour according to the invention on the basis of a sine function,

Fig. 5

the roll bale contour according to the invention on the basis of a tilted sine function,

Fig. 6

a geometric definition of the contour angle,

Fig. 7

the empty roll gap contour as a function of the contour angle,

Fig. 8

the roll gap contour as a function of the roll displacement s

In the Fig.1 to 3 various types of rolling stands are shown schematically, which come for the application of the invention in question and from the prior art, for example EP-B 0 049 798 , are known in their basic structure.

Fig. 1 shows a duo-rolling stand 1 with a stand 2 and a pair of work rolls 3, 4, which are rotatably supported in the two frame stands 2 in chocks 5, 6. Adjustment devices 7 allow the employment of the two work rolls 3, 4 against the current through the nip 8 rolled strip 9. The two work rolls 3, 4 are on the roll pins 10, 11 in the chocks 5, 6, which also include displacement devices 12, 13, axially slidably supported. The roll bales 14 of both work rolls 3, 4 are equipped over their entire effective bale length with a curved bale contour 15, with these bale contours 15 complement each other in a certain relative axial position of the work rolls in the unloaded state. This is possible either inside or outside the axial displacement range of the work rolls 3, 4.

Fig. 2 shows in a further schematic representation of a four-high rolling stand 17 with work rolls 3, 4 and support rollers 18, 19. In this embodiment, the support rollers 18, 19 equipped with a curved bale contour 15 and supported axially displaceable. Analog shows Fig. 3 a six-high rolling mill 20 with work rolls 3, 4, Support rollers 18, 19 and intermediate rollers 21, 22. In this embodiment, the intermediate rollers 21, 22 are equipped with a curved bale contour 15 and supported axially displaceable. While the bale contour acts directly on the rolled strip of the duo rolling stand, the rolling stands are followed by the Fig. 2 and Fig. 3 to a change of the roll gap contour generated by the substantially cylindrical work rolls by the action of the provided with a curved bale contour support or intermediate rolls.

The course of the bale contour of the rolls of a pair of rolls is formed by a trigonometric function, preferably a sine function, with particular advantages being achieved with a bale contour produced by a tilted sine function, which lie in a possible minimization of the diameter differences along the bale contour. Fig. 4 shows the curved contour of the roll barrel of the upper and lower work rolls of a duo stand on the basis of a sine function with a roll barrel length of 1540 mm and a contour angle of 72 °. With a work roll displacement of about ± 60 mm, there are already marked differences in diameter across the length of the bale.

In contrast, shows Fig. 5 the curved contour of the roll barrel based on a tilted sine function. The differences in diameter over the roll barrel length are much smaller here and illustrate the described smoothing effect. Experiments have shown that can be produced with such a contoured roll bales a highest quality requirements fulfilling, flat and wave-free rolled strip.

There are advantages in terms of the immediately clear input variables and the easier transferability to other framework configurations. Input variables are the grinding reference length or the bale length, the displacement range, the equivalent roll crowns in the extreme displacement positions as well as the contour angle.

In Fig. 6 is the example of a contour angle of 70 ° illustrates the importance of this size for a given normalized roll gap profile. The contour angle defines that section of the cosine curve that corresponds to half the loop reference length on the bale.

The bale contour can be influenced by varying the contour angle. The choice of a larger contour angle leads to a smaller diameter of the roll bale in an area between the roll center and roll edge, thus in this area to a lower local reduction in rolling stock thickness and ultimately minimizing quarter wave formation. The influence of the contour angle on the empty roll gap contour is in Fig. 7 shown and clearly shows the diameter variation in the quarter range.

In order to use the rollers equipped with the described bale contour for a dynamic flatness control, the nip contour must be determined by the displacement position of the rollers to each other and be continuously variable over the displacement range. These relationships are in Fig. 8 for three exemplary values of the roller displacements of the top roller (s) of -60 mm, 0 mm (no displacement) and +60 mm shown and show the usable range of action of the rolling stand.

Claims (9)

1. Rolling stand for production of rolled strip, with work rolls (3, 4), which are supported if necessary on support rolls (18, 19) or support rolls and intermediate rolls (21, 22), wherein the work rolls (3, 4) and/or support rolls (18, 19) and/or intermediate rolls (21, 22) in the rolling stand (1) are disposed able to be axially displaced in relation to one another and each roll of at least one of these pairs of rolls has a curved contour running over the entire effective barrel length and these two barrel contours (15), exclusively in a specific relative axial position of the rolls of the pair of rolls, complement each other in an unloaded state, characterised in that the course of the barrel contour of the rolls of a pair of rolls is formed by a trigonometrical function and also the roll gap contour is formed as a function of the course of the barrel contour (15) and the position of the rolls within the axial displacement area by a trigonometrical function, wherein the trigonometrical function of the barrel contour is formed by a sine function in accordance with the general equation $$R\left(x\right)=R_0+A*\mathit{sin}\left(\frac{2*\varphi *\left(x+c\right)}{L_{\mathit{REF}}}\right)$$

   

   
   with

   R radius of the roll

   x axial position in relation to the centre of the roll (= distance from the centre of the roll)

   R₀ roll radius offset (= radius of the roll at the contour turning point)

   A contour coefficient

   ϕ contour angle

   c contour displacement

   L_REF camber reference length

   and the roll gap contour is formed by a cosine function deriving therefrom in accordance with the general equation $$G\left(x,s\right)=G_0+2*A*\cos \left(\frac{2*\varphi *x}{L_{\mathit{REF}}}\right)*\mathit{sin}\left(\frac{2*\varphi *\left(s-c\right)}{L_{\mathit{REF}}}\right)$$

   

   
   with

   s displacement of one of the rolls from the central location

   G₀ roll gap offset.
2. Rolling stand for production of rolled strip, with work rolls (3, 4), which are supported if necessary on support rolls (18, 19) or support rolls and intermediate rolls (21, 22), wherein the work rolls (3, 4) and/or support rolls (18, 19) and/or intermediate rolls (21, 22) in the rolling stand (1) are disposed able to be axially displaced in relation to one another and each roll of the at least one of these pairs of rolls has a curved contour running over the entire effective barrel lengths and these two barrel contours (15), exclusively in a specific relative axial position of the rolls of the pair of rolls complement one another in an unloaded state, characterized in that the course of the barrel contour of the rolls of a pair of rolls is formed by a trigonometrical function and also the roll gap contour is formed as a function of the course of the barrel contour (15) and the position of the rolls within the axial displacement area by a trigonometrical function, wherein the trigonometrical function of the barrel contour (15) is formed by a tilted sine function in accordance with the general equation $$R\left(x\right)=R_0+A*\sin \left(\frac{2*\varphi *\left(x+c\right)}{L_{\mathit{REF}}}\right)+B*\left(x+c\right)$$

   

   
   with

   R radius of the roll

   x axial position in relation to the centre of the roll (= distance from the centre of the roll)

   R₀ roll radius offset

   A contour coefficient contour angle

   c contour displacement

   L_REF camber reference length

   B tilt coefficient

   and the roll gap contour is formed by a cosine function derived therefrom in accordance with the general equation $$G\left(x,s\right)=G_0+2*A*\cos \left(\frac{2*\varphi *x}{L_{\mathit{REF}}}\right)*\mathit{sin}\left(\frac{2*\varphi *\left(s-c\right)}{L_{\mathit{REF}}}\right)+2*B*\left(s-c\right)$$

   

   
   with

   s displacement of the upper roll from the central position

   G₀ roll gap offset.
3. Rolling stand according to one of claims 1 or 2, characterised in that the barrel contour (15) of the two rolls is selected so that the two barrel contours complement one another within the axial displacement area of the rolls.
4. Rolling stand according to one of claims 1 or 2, characterised in that the barrel contour (15) of the two rolls is selected so that the two barrel contours complement one another outside the axial displacement area of the rolls.
5. Rolling stand according to one of claims 2 to 4, characterised in that, for a predetermined camber reference length (L_REF) for the curved barrel contour of the rolls, a contour angle (ϕ) in accordance with the condition 0° < ϕ ≤ 180°, preferably 50° ≤ ϕ ≤ 80°, is selected.
6. Rolling stand according to one of claims 2 to 4, characterised in that the tilt coefficient (B) in the equation for the barrel contour of each roll is selected so that the maximum difference in diameter of the barrel contours within the camber reference length or the barrel length is at a minimum.
7. Rolling stand according to one of the preceding claims, characterised in that further actuators at least influencing the barrel contour (15) in portions are positioned additionally in the rolling stand (1) in effective connection with the working rolls (3, 4) and/or support rolls (18, 19) and/or intermediate rolls (21, 22), such as work roll cooling or zone cooling for example.
8. Rolling stand according to one of the preceding claims, characterised in that the work rolls (3, 4) and/or support rolls (18, 19) and/or intermediate rolls (21,22), are connected by the displacement devices assigned to them as well as possibly measurement devices needed for detecting the state of the strip entering or leaving the rolls and possibly additional actuators to a regulation device for profile or flatness regulation, that the regulation device is assigned a computation unit, which using mathematical models, if necessary using a neural network, generates control signals for the correction of the working rolls (3, 4) and/or support rolls (18, 19) and/or intermediate rolls (21, 22) and if necessary additional actuators and with adjustment elements assigned to the working rolls and/or support rolls and/or intermediate rolls and possibly to additional actuators, positions corresponding to the controls signals are able to be moved to.
9. Rolling stand according to one of the preceding claims characterized in that the rolling stand is embodied as a duo rolling stand or as a quarto rolling stand or as a sexto rolling stand.

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