EP1365869B1 - Roll stand for producing plane roll strips having a desired strip profile superelevation - Google Patents

Abstract

The aim of the invention is to improve known roll stands ( 10 ) which are characterized by working rolls ( 1,2 ) of various diameters, in such a way that a strip is obtained which is largely free of tensions and undulations, has a desired strip profile superelevation, and can be used approximately universally. To this end, the support rolls ( 3,4 ) and the working rolls ( 1,2 ) are arranged in an axially displaceable manner in the roll stand ( 10,11 ), the position of at least one of the working rolls ( 1,2 ) can be adjusted in the discharge direction ( 7 ) of the roll strip ( 6 ), and that the support rolls ( 3,4 ) and the working rolls ( 1,2 ) are provided with a curved contour (continuously variable crown which is determined by an at least second order polynomial) which extends essentially over the whole surface length of the roll, said contours being staggered by 180° in relation to each other and respectively embodied in such a way that both contours of the working rolls ( 1,2 ) complete each other to form a symmetrical contour of the roll gap.

Description

The invention relates to a roll stand for the production of flat rolled strips with the desired Belt profile elevation, with supported on at least one support roller Work rolls, the work rolls having different diameters have, the thicker work roll is connected to a drive and the runs thinner work roll than "drag roller".

Rolling mills with different diameters of the work rolls are known. A rolling mill is described in US Pat. No. 2,139,872, in which, in order the most effective possible reduction of the rolled strip during rolling reach, two work rolls supported on backup rolls with different Diameter are arranged. It has proven advantageous here only to drive the larger work roll and the smaller roll as a drag roll to let it run. Such known rolling mills are advantageously used in the rear stands of a rolling mill used with the aim of reducing the rolling force and the drive power as well as a lower edge drop, especially with high-carbon steef.

When hot rolling strip material are subject to a rolling program the thermal crowning and wear of the work rolls as well whose elastic deformations are relatively large changes. Without correction actuators change with increasing continuous material flow the band contour. This effect varies from frame to frame or from Stitch to stitch different. In addition to the band contour, this also changes the specified hot strip flatness and subsequently also the cold strip flatness.

The object of the invention is the known rolling mill with its different Work roll diameters continue to be modified so that a strip is higher Quality is generated and these scaffolds can be used universally.

• dass die Stützwalzen und die Arbeitswalzen im Walzgerüst axial verschiebbar angeordnet sind,
• dass mindestens eine der Arbeitswalzen in Auslaufrichtung einstellbar ausgeführt ist und
• dass die Stützwalzen und die Arbeitswalzen mit einer im wesentlichen über die gesamte Ballenlänge verlaufenden gekrümmten und durch ein Polynom mindestens zweiter Ordnung festgelten Kontur, versehen sind, die relativ zueinander um 180° versetzt angeordnet und die jeweils so ausgebildet ist, dass die beiden Ballenkonturen der Arbeitswalzen sich zu einer symmetrischen Kontur des Walzenspaltes komplementär ergänzen.

The object is achieved in a roll stand of the type mentioned with the characterizing features of claim 1,

• that the support rolls and the work rolls are arranged axially displaceably in the roll stand,
• that at least one of the work rolls is adjustable in the outlet direction and
• that the back-up rolls and the work rolls are provided with a curved contour running essentially over the entire bale length and defined by a polynomial of at least second order, which are arranged offset by 180 ° relative to one another and which are each designed such that the two bale contours of the work rolls complement each other to form a symmetrical contour of the nip.

Through the combination according to the invention, the known different sizes Work rolls with a CVC cut (known among other things from DE 37 120 43 C2; the CVC cut or the roller contour follows a polynomial second or higher order) and the work and back-up rolls to be arranged both axially and in the outlet direction received a completely new scaffolding concept that is different from the known ones Roll stands can be used more universally and the rolled strips produce with high flatness and desired belt profile elevation.

As a profile actuator for the CVC grinding of the work rolls, it is advantageous in these roll stands to calculate the grinding according to a third or higher order polynomial, for example also a fifth order, and to carry it out accordingly. A 5th order polynomial of the general form: R (x) = a 5 • x 5 + a 4 • x 4 + a 3 • x 3 + a 2 • x 2 + a 1 • x + a 0

• für ein Koordinatensystem R(x) an der Walzenkante
  a₀ = 0,349712 • 10³ mm (Radius der Arbeitswalze)
  a₁ = 0,733199 • 10^-3
  a₂ = 0,198038 •10^-3mm^-1
  a₃ = - 0,536180 • 10^-3 mm^-2
  a₄ = 0,368442 •10^-11 mm^-3
  a₅ = - 0,775668 •10^-15 mm^-4
• für ein Koordinatensystem R(x) in der Walzenmitte
  a₀ = 0,350000 • 10³ mm (Radius der Arbeitswalze)
  a₁ = - 0,544375 • 10^-3
  a₂ = 0,000000 mm^-1
  a₃ = 0,163860 • 10^-8 mm^-2
  a₄ = - 0,590250 • 10^-28 mm^-3
  a₅ = - 0,775668 • 10^-15 mm^-4

Would then have the following parameters for a 1900 mm long roller, for example

• for a coordinate system R (x) at the roll edge
  a ₀ = 0.349712 • 10 ³ mm (radius of the work roll)
  a ₁ = 0.733199 • 10 ^-3
  a ₂ = 0.198038 • 10 ^-3 mm ^-1
  a ₃ = - 0.536180 • 10 ^-3 mm ^-2
  a ₄ = 0.368442 • 10 ^-11 mm ^-3
  a ₅ = - 0.775668 • 10 ^-15 mm ^-4
• for a coordinate system R (x) in the middle of the roll
  a ₀ = 0.350000 • 10 ³ mm (radius of the work roll)
  a ₁ = - 0.544375 • 10 ^-3
  a ₂ = 0.000000 mm ^-1
  a ₃ = 0.163860 • 10 ^-8 mm ^-2
  a ₄ = - 0.590250 • 10 ^-28 mm ^-3
  a ₅ = - 0.775668 • 10 ^-15 mm ^-4

Since the work roll diameters are different, the work rolls have also a different deflection and flattening behavior. specially the effects between the backup rolls and the work rolls are different. This applies in particular to a 3-roll stand, in which only the thinner one Work roll is supported by a backup roll because the thicker work roll any support is missing. The contours of the work rolls were therefore designed differently according to the invention to compensate for these effects. The required contour is calculated offline with the goal of creating a symmetrical roll gap under load.

The new roll stand concept is special in such a case 3-roll stand applicable. These scaffolds can be advantageous, for example for not so high loads then also used for the front scaffolding become. Even with this 3-roll stand, only the thicker work roll is used driven and the thinner work roll runs as a drag roller. The thicker Work roll acts as a work roll that transmits a high moment can and which also serves as a backup roller. The combination with the other, thinner work roll supported by a separate backup roll then results in controllable rolling forces.

Because with the given boundary conditions when using work rolls with different diameters, especially when rolling thick strips Ski formation (bending of the belt leading edges) is to be avoided in order to avoid this this ski formation according to the invention one of the work rolls in the outlet direction adjustable. The setting of this skew offset is u. a. depending on the inlet and outlet thickness, the material strength of the rolled strip, controlled the current diameter combination of the work rolls etc.

For a roll stand that contains a non-driven smaller work roll and that is not pretensioned (the nip corresponds to the tapping roughly the strip inlet thickness), it is also advantageous for the non-driven work roll to be provided with an auxiliary drive, which then uncouples after tapping and / or is switched off. Through this measure the vibrations that frequently occur in the front stands during rolling (Swinging of the work rolls against each other) avoided because then the work rolls are decoupled in terms of drive during rolling. With The auxiliary drive also provides a benefit that may be necessary allows axial movement of the work rolls during the breaks.

To the resulting from the different work roll diameters Compensating boundary conditions, it is still according to the invention possible, depending on each of the work rolls as well as on each of their sides to set different work roll bending forces for the respective sliding position. To the higher surface pressure between the thin work roll counter with their backup roller can also be provided to extend these rollers accordingly.

To the different wear of the work rolls due to their different To counter diameters, the work rolls are out in their Wear behavior of different materials or made of highly wear-resistant Materials manufactured, for example after a powder metallurgical Process, preferably the HIP process (hot isostatic pressing). With the HIP process, as it is in the special print from "Stahi" (1998), volume 6, pages 38-40 is described, the material to be treated in special autoclave (HIP systems) at all-sided pressure (up to 200 Mpa) and higher Temperature (depending on the material up to 2000 ° C) warmed up above its yield point and condensed at the same time.

Further details of the invention are shown below in schematic Exemplary embodiments illustrated in the drawings are explained in more detail.

Fig. 1

ein Quarto-Gerüst in schematischer Seitenansicht,

Fig. 2

ein 3-Walzengerüst in schematischer Seitenansicht.

Show it:

Fig. 1

a four-high stand in schematic side view,

Fig. 2

a 3-roll stand in a schematic side view.

In Figure 1, a four-high stand 10 is shown with two work rolls 1, 2, the are supported on support rollers 3, 4. Below the rolled strip 6 is one. Stripper 2 with a larger and above the roll belt 6 a work roll 1 arranged with a smaller diameter. The larger work roll 2 is with a Drive 5 provided, while the thinner work roll 1 no drive owns and only through contact with the rolling belt 6 as a "drag roller" starts to rotate. The thinner work roll 1 is horizontally displaceable in the direction of arrow 9 arranged and in the illustrated embodiment in the discharge direction 7 of the rolled strip 6 offset by the amount 8 from its original position.

The contours of the surfaces of the work rolls 1, 2 with their associated Back-up rolls 3, 4 are calculated according to the invention by CVC grinding manufactured according to a polynomial of at least second order (in the illustrated Side view of the roll stand 10, this CVC cut is not visible). The upper work roll 1 can for example have a diameter of 400 mm have lower work roll 2 of 600 mm, while the support rolls 3, 4 one Have a diameter of 1350 mm each.

In Figure 2, a 3-roll stand 11 is shown, in which only the upper supports thinner work roll 1 on a support roll 3. The thicker and driven one Work roll 2, on the other hand, is chosen so large in diameter that the higher moments can be transmitted and therefore this work roll 2 also serves as a backup roller. In this example, too Fig. 2 is the thinner work roll 1 by the amount 8 in the discharge direction 7 staggered from their original position. The upper working salt 1 can a diameter of z. B. 600 mm and the upper backup roller 3rd a diameter between 1400 and 1600 mm. The diameter of the bottom Work roll 2, which is also used here as a backup roll, can, for. B. 1400 mm.

The examples shown in FIGS. 1 and 2 show the application of the invention in two rolling stands. Of course, the invention can also be based on other roll stands with different numbers of Rolls are used, for example in roll stands with intermediate rolls.

LIST OF REFERENCE NUMBERS

1

Stripper

2

Stripper

3

supporting roll

4

supporting roll

5

Drive work roll

6

rolling

7

exit direction

8th

Roll offset

9

displacement direction

10

4 mill

11

3-roll stand

Claims (8)

1. Roll stand for producing planar rolled strips (6) with a desired strip profile excess height, with working rolls (1, 2) supported at at least one backing roll (3, 4), wherein the working rolls (1, 2) have different diameters, the thicker working roll (2) is connected with a drive (5) and the thinner roll (1) co-runs as a 'drag roll', characterised in that

   the backing rolls (3, 4) and the working rolls (1, 2) are arranged in the roll stand (10, 11) to be axially displaceable,

   at least one of the working rolls (1, 2) is constructing to be adjustable in the exit direction (7) of the rolled strip (6) and

   the support rolls (3, 4) and the working rolls (1, 2) are provided with a curved contour which extends substantially over the entire length of the circumferential surface and is established by a polynomial (1) of at least second order, the contours being arranged to be offset relative to one another by 180° and each so formed that the two circumferential surface contours of the working rolls (1, 2) complement one another to form a symmetrical contour of the roll gap.
2. Roll stand according to claim 1, characterised in that the working rolls (1, 2) are formed with mutually different contours to provide compensation for different warping and flattening behaviour, wherein a polynomial of third or higher order, for example a polynomial of fifth order, is used for calculation of the contours.
3. Roll stand (10, 11) according to claim 1 or 2, characterised in that the roll offset (8) in the working rolls (1, 2) is continuously adjustable in exit direction (7).
4. Roll stand (10, 11) according to claim 3, characterised in that the size of the roll offset (8) is controlled in dependence on, inter alia, the entry and exit thickness of the rolled strip (6), its material strength and the actual diameter combination of the working rolls (1, 2).
5. Roll stand (10, 11) according to one of claims 1 to 4, characterised in that different working roll bending forces are settable respectively for each of the working rolls (1, 2) as well as for each of the sides thereof in dependence on their displacement position.
6. Roll stand (10, 11) according to one of claims 1 to 5, characterised in that only the thinner working roll (1) is supported by a backing roll (3).
7. Roll stand (10, 11) according to one of claims 1 to 6, characterised in that the thinner working roll (1) is connected with an auxiliary drive which can be switched off and/or decoupled.
8. Roll stand (10, 11) according to one of claims 1 to 7, characterised in that the working rolls (1, 2) are made of different materials which differ from one another in their wear property and/or of highly wear-resistant materials according to a powder metallurgical method, for example according to the HIP method.

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