EP2777833B1 - Device for rotating the working rolls of a rolling mill and method for changing said rolls - Google Patents

Description

The present invention relates to a device for rotating work rolls of a rolling mill according to the preamble of claim 1, as well as a method of changing work rolls according to the preamble of claim 10.

In a rolling mill of flat product in metal strip such as moving strips, the rolling operation requires firstly, for reasons of maintenance, a frequent change, in particular of the working cylinders in permanent contact under effort with the other cylinders. associated support and rolling tape in rolling, following their wear in contact with the strip which cause damage to their outer periphery such as crimping, cracking and surface condition. This is particularly the case for rolling strips of stainless steel and / or steel and other high tensile metal materials or for rolling metal materials of very thin thicknesses, the frequency of change being all the greater as the material is hard and the diameter of the working rolls used is relatively small especially when using multiple cylinders 18-cylinder cylinders commonly called "18 High" (see also document WO2011 / 107165A1 : figure 5 and pages 28 to 33) or type 20 cylinders commonly referred to as "20 High". On the other hand, the work roll change operation requires a slowdown and then stop the rolling operation which therefore decreases the productivity of the rolling mill and particularly important when the changes are frequent for the reasons mentioned above.

This state of affairs has already led to the development of so-called on-the-fly cylinder change methods which are described in WO2009153415A1 as well as in EP2135690 A1 . These methods have optimized methods for opening and closing a plurality of tandem rolling mill stands successively arranged in the tape running direction, the said cages comprising at least working rolls capable of rolling the strip in the closed cage position. As soon as there is evidence of wear or other obvious deterioration of working rolls in one of the stands, the said stand is then placed in an open position (its working rolls are separated from the band). During this opening operation, at least one other cage or additional cage compensates for the rolling effect decreased by the opening of the cage to worn cylinders. In this way, the web continues to scroll and the rolling characteristics as well as the thickness of the desired strip at the output of the rolling mill are guaranteed within the required tolerances.
Also, in the case of such a change of cylinders on the fly, while one or more cages are open or closed, the laminated or not rolled local strip thickness and effects of slowing and re-acceleration of tape the passage of cages downstream of the open cage are present and require control measures to best achieve the clamping force, speed and strip tension required by a targeted rolling. In particular, risks of slippage between the working roll and an intermediate roll causing said working roll for multi-roll rolling mill stands appear not only during rolling, but also and especially during the change of cylinder on the fly. .

For multi-roll mill stands, a minimum roll configuration includes sets of rolls said lower and upper to the band (here in horizontal scrolling), each of the sets comprising an intermediate roll rotating in surface contact and friction a working roll for rolling the band, particularly when using small diameters of cylinders which are not able to withstand rolling torques sufficiently high compared to the rolling conditions given.

For multi-roll mill stands such as type 18 Hi, when the roll stand is open and without rolling clamping force, the working rolls are then set back off contact with the strip, after which the contacting of the rolls is prevented. Work rolls are made by docking on each side of the band and a clamping force for rolling is finally applied. In the open-cage condition described above, the lower intermediate cylinder in particular (part of the lower set of cylinders arranged under the belt) being the only motorized cylinder, the associated lower working cylinder rests only by its own weight. on the lower intermediate cylinder ,. During this phase, if it is desired to rotate said lower work roll for adaptation of the angular speed of the work roll to the running speed of the web before the start of rolling (docking) or just when one removes the contact with the web (de-docking), it is difficult to ensure the acceleration and / or deceleration of the ideally free sliding rotation between the intermediate cylinder and the working cylinder and between the working cylinder and the band.

An object of the present invention is to propose a device for rotating a working roll of a rolling strip rolling mill capable of ensuring a docking better dynamically mastered of at least one lower work roll on the scrolling tape. Such a docking therefore provides to ensure a rotation of the working cylinder without sliding with the intermediate cylinder causing said rotation. Also, slippage effects between the work roll and the web should be minimized or even eliminated. The device according to the invention should be advantageously extended for optimal rotation of all the lower and upper work rolls.

By extension, this device according to the invention should be suitable for changing cylinders on the fly in a multi-stand mill, in particular of 18-High type, without limitation to other types such as 4-High, 6-High, etc. For this case, it is thus desired to propose a method of changing cylinders on the fly using the device according to the invention and ensuring a speed setting operation and rolling conditions actually better controlled.

Such a device for rotating a work roll is proposed through the features of claim 1 as well as a method of changing at least said roll through the features of claim 10.

A set of subclaims also has advantages of the invention.

Figure 1

Arrangement des ensembles de cylindres sur une cage fermée de type 18 High adaptée à l'invention,

Figure 2

Dispositif selon l'invention dans une cage ouverte de laminoir en vue latérale selon le défilement de bande,

Figure 3

Dispositif selon l'invention dans une cage fermée de laminoir en vue latérale selon le défilement de bande,

Figure 4

Dispositif selon l'invention dans une cage fermée de laminoir en vue face au défilement de bande,

Figure 5A, 5B

Etapes schématiques principales de changement d'un cylindre de travail à la volée sur des cages de laminoir en tandem

Figure 6

Dispositif selon l'invention avec un moyen de poussée alternatif.

Examples of implementation and application are provided using the figures described:

Figure 1

Arrangement of sets of cylinders on a closed cage type 18 High adapted to the invention,

Figure 2

Device according to the invention in an open mill stand in side view according to the tape running,

Figure 3

Device according to the invention in a closed rolling mill cage in lateral view according to the tape running,

Figure 4

Device according to the invention in a closed rolling mill cage with a view of the tape running,

Figure 5A, 5B

Main schematic steps of changing a working cylinder on the fly on tandem rolling mill cages

Figure 6

Device according to the invention with an alternative thrust means.

• les cylindres d'appui (BURI, BURS) pour poussée verticale de force de laminage ;
• les cylindres intermédiaires (IRI, IRS) ;
• les cylindres de travail (WRI, WRS) ;
• les cylindres de soutien latéraux (SSRI, SSRS) sous forme de quatre grappes de trois cylindres.

Figure 1 represents an arrangement of the sets of cylinders on a closed type 18 high rolling mill adapted to implant a device according to the invention. This figure 1 and its description were mainly incorporated by reference on the document WO2011 / 107165A1 ( figure 5 and pages 28 to 33) by changing the designations of reference signs. Such a high-18-type multi-roll mill stand comprises a plurality of rolls 18 forming two sets smaller and larger than the roll band (B) disposed between holding bases (CL, CR). Thus we will distinguish the following categories of cylinders for each of the lower and upper sets:

• the support cylinders (BURI, BURS) for vertical thrust of rolling force;
• intermediate cylinders (IRI, IRS);
• work rolls (WRI, WRS);
• the lateral support cylinders (SSRI, SSRS) in the form of four clusters of three cylinders.

The arrangement of these elements is well known to those skilled in the art of rolling with such cages and this provision will not be developed further in this document. See WO2011 / 107165A1 ( figure 5 and pages 28 to 33) if necessary.

For the sake of clarity in the following figures, not all the cylinders are shown, in particular the four clusters of three lateral support cylinders (SSRS, SSRI). The device according to the invention as well as the method of changing the cylinder are not limited to high type 18 rolling mill cages, but can be extended to any other cage configuration such as High type.

Figure 2 presents an embodiment of a device according to the invention in a rolling mill stand type 18-High (although it appears as a cage type 6-High without the four clusters of three lateral support rollers), said cage being open in side view according to the tape scroll.

From a device for rotating rolling work rolls synchronized with the speed of a moving strip (B) (here horizontal in the X direction) under the rolling operation of a plurality of rolling mill stands arranged in tandem (here only one cage is shown), each of the cages comprising a set of rollers lower than the strip and a set of rolling rolls greater than the strip, the said set of lower rolling rolls comprising at least one roll lower intermediate (IRI) driving in rotation by surface contact and friction a lower working cylinder (WRI), said set of upper rolling rolls comprising at least one upper intermediate roll (IRS) driving in rotation by surface contact and friction an upper work roll (WRS), said lower and upper working rolls being adapted to being brought into contact with respectively one of the lower and upper faces of the strip to be rolled, said intermediate and working rolls having axes of rotation aligned in at least one vertical plane (here in the Z direction) or a close vicinity of said plan, the clusters of lateral guide cylinders (respectively SSRI, SSRS) of the lower and upper work rolls represented on the figure 1 being associated with the sets of cylinders but not shown for the sake of clarity figures 2 and 3 .
Said device according to the invention is characterized in that, before contacting the lower working cylinder on the strip for active rolling positions, a vertical thrust means (R1i, R2i, EI, EI ') (or P1I, P2I, EI, EI ': see figure 6 ) exerts a first downward force on the lower working cylinder (WRI).

Analogously, the device according to the invention also provides that, before contacting the upper working cylinder on the strip for active rolling positions, the vertical thrust means (R1s, R2s, ES, ES ') (or P1S , P2S, ES, ES ': see figure 6 ) exerts a second force upward on the upper working cylinder (WRS).

• Un entrainement mieux maitrisé en rotation par couple de friction sans glissement entre les cylindres de travail et intermédiaires, de type inférieurs et, si besoin supérieurs en pré-phase d'accostage ou dé-accostage.
• Une synchronisation mieux maitrisée de vitesses entre le cylindre de travail inférieur et la surface de bande en défilement à accoster ou dé-accostage.

Thus, the invention consists in applying (by means of the thrust means such as for example two simple arms at controlled altitude according to a required pressure) a force on both ends of at least the lower work roll in order to ensure:

• A drive better controlled in rotation by friction torque without sliding between the work rolls and intermediate, of the lower type and, if necessary, higher in the pre-landing or landing phase.
• A better controlled synchronization of speeds between the lower work roll and the moving web surface to dock or dé-docking.

In other words, the main characteristic of the thrust means is to produce a controlled clamping effect between each working roll and its associated intermediate roll in order to better control the non-slip spinning relative to each other as well as between the working cylinder and the belt approached or un-docked. For this purpose, the vertical biasing means exerts the first and second forces under intensity values avoiding any sliding which in any way penalizes the points of surface contact between each intermediate roll and its associated working roll. This tightening criterion is major in order to better control the friction required between the working and intermediate rolls and a fortiori the conditions of optimal docking speeds of the working roll on the moving strip.

The Applicant also states that this device according to the invention is perfectly feasible for rolling mill stands as presented by the well-known references. WO2009153415A1 and EP2135690 A1 . The so-called transient phases on the fly during a change or replacement of the working cylinder are thus better mastered, or even shorter. The thicknesses at the output of the rolling mill are better respected under stricter tolerances. Possible surface defects in transient phases of the cycle are also more limited and acceptable. The lengths of the rolled strip possibly out of tolerances are very limited which improves the productivity of the rolling mill and the quality of the rolled out product.

In contrast to known rolling mills, for which frequent rolling stops for changes of rolling mill rolls occur, as well as for which lengths of rolled strip out of tolerances and therefore lost add to high economic losses especially when the rolled metal is expensive as for a stainless steel and / or other metal composed of high cost elements, the device according to the invention advantageously not only not to stop rolling in progress due to a change of cylinders of work, but also guarantees rolling continuity under a required tolerance.

The device according to the invention provides that the vertical thrust means comprises a first and a second module (EI, EI 'ES, ES') of elevator type (here in the Z direction), the said first module being able to push , and spreading or approaching each lower and upper working cylinder out of or towards the band. In addition to the relative elevation and descent function between the pedestals (EI ', ES') and their arm (EI, ES), these elements make it possible to exert a precise thrust force from the working cylinder to the adjoined intermediate cylinder, avoiding thus advantageously sliding effects. This is a simple configuration that can be easily arranged on CL, CR bases attached to columns of the rolling mill stand. Other configurations of thrust means could be more complexly realized such as chocks guiding work rolls, but they would singularly complicate the plans of the cage and increase its cost. Finally, such configurations can not universally adapt to any roll stand, such as for example that type 18-High for which such chocks and support by bending are unsuitable.

The device according to the invention provides that the first and second modules (EI, EI 'ES, ES') of elevator type respectively comprise a first and a second set of at least one roller or contact support roll (R1s , R2s; R1i, R2i), each of said sets being disposed at least at one end and ideally at the right of each of the trunnions arranged at the ends of each lower and upper working cylinder (WRI, WRS), said rollers or rollers of the first set of rollers (R1i, R2i) exerting the first downward force on the lower work roll (WRI) and said rollers or rollers of the second set of rollers (R1s, R2s) exerting the second force to the high on the upper working cylinder (WRS). An advantageously simple alternative of the thrust means and the rollers or support roll is presented in figure 6 wherein the device according to the invention provides that the first and second modules (EI, EI 'ES, ES') of elevator type respectively comprise a first and a second set of at least one support pad (P1I, P2I; P1S , P2S) allowing contact (and support / guidance) with at least one bearing type ring (B1I, B2I; B1S, B2S) assembled at the right of each end and ideally at the right of each of the journals (Twri, Twrs) disposed at the ends of each lower and upper work roll (WRI, WRS), said first set of shoes (P1I, P2I) exerting the first force down on the lower work roll (WRI) and said second set of pads (P1S, P2S) exerting the second force upward on the upper work roll (WRS). The sets of pads finally allow by vertical translation (Z direction) to push the rings to exert the required thrust force, but can also be translated horizontally (X direction) to generate a relative lateral displacement of the work rolls.

The figure 4 also presents for this purpose a complementary view (in front of the tape running) of the device according to the invention in a closed rolling mill cage. This very simple system of rollers, or rollers, or skids associated with bearing-type rings (B1I, B2I, B1S, B2S) allows a precise balancing of the force exerted on the working cylinders of the thrust means and a free rolling and without relative sliding with the intermediate cylinder associated in rotation at the top, for example of the lower working cylinder.

Additionnement, the lateral position of the working cylinders in disassembly / reassembly of cylinders may require a position different from that required in the rolling phase, the device according to the invention provides that at least one of the vertical thrust means (R1i, R2i; R1s, R2s) can exert a thrust component via the roller (s) or rollers or pads (P1i, P2i; P1s, P2s: see figure 6 ) associated with bearing rings (B1I, B2I, B1S, B2S) on the working cylinder (lower or / and upper) so that said cylinder is laterally displaceable in a horizontal direction (X) relative to the intermediate cylinder associated. In practice, this relative lateral displacement between the working roll and the intermediate roll is variable under an interval for example of value [-10mm; + 10mm]. This relative lateral displacement (known as "offset") lateral is necessary during rolling operation to wedge the sets of cylinders relative to their bearing points inside the roll stand and also for optimize the balance of forces and torques exerted on the cylinders between them. This function can then be easily achieved by introducing a pivot (Roff) between two rollers or rollers (R1i, R2i; R1s, R2s) or pads (P1i, P2i; P1s, P2s: see figure 6 ). Alternatives means for exerting a thrust component inducing a small horizontal offset between a cylinder of work and its associated intermediate cylinder can also be performed, such as for example by means of an additional horizontal translation cylinder to the roller support (EI, ES). Here again, it should be noted that the presented thrust means including a pivot is perfectly integrable to the device according to the invention and to any type of multi-roll mill stands such as 18-High, 20-High etc., the device according to the invention itself being particularly suitable for a rolling mill comprising high 18 type cages.

Finally, it is necessary to specify that the device according to the invention is suitable for a rolling mill comprising working rolls of small diameter such as in the case of rolling stainless steel strip, or high tensile steel and particularly for a low strip thickness close to 0.1 mm at the end of the rolling mill. Indeed, such cylinders wear out quickly which reduces production and involves many changes of working cylinder on the fly not to stop the rolling. Because of the better control of the rotation of the working rolls before docking of the rolling strip, the control of the change of work rolls on the fly is improved and more effective, which makes it possible to avoid stopping always too long during the changes of said cylinders.

The figure 3 is by analogy from the figure 2 and presents the device according to the invention in a closed rolling mill stand and / or under rolling force in lateral view according to the tape running. The lower working cylinder is pressed against the belt and rolls the latter under great external force exerted by means of support rollers (BURS, BURI) coupled to a clamping unit (not shown) generally comprising two hydraulic clamping cylinders. The thrust means (R1i, R2i, E1, EI ') or (P1i, P2i, EI, EI': see figure 6 ) according to the invention in this tightening phase no longer exerts thrust force on the lower working cylinder (WRI) downwards, because in the clamping position, said lower working cylinder is no longer in contact with to a game (GAP) with the thrust means (rollers / rollers or support pads) to leave full part in the rolling and the associated rotation of the cylinders .. Analogously, the upper work roll is pressed against the strip and rolled the latter under great external force exerted by means of the support cylinders (BURS, BURI) coupled to a clamping unit (not shown) generally comprising two hydraulic clamping cylinders. The thrust means (R1s, R2s, ES, ES ') or (P1s, P2S, EI, EI'): see figure 6 ) according to the invention in this tightening phase no longer exerts pushing force on the upper working cylinder (WRS) upwards, because in the clamping position, said upper working cylinder is no longer in contact with a game similar to the previous game (GAP) with the thrust means (rollers / support rollers) to leave full part in the rolling and the associated rotation of the cylinders. It is clear here that the thrust means is not a simple elevator or geometric positioner of cylinders, but it provides an anti-slip between working rolls and intermediate cylinders by pushing when the cage is in the open position, as well as when rotating the work rolls for change on the fly during rolling.

To the figures 2 and 3 , lower and upper additional bearing cylinders (BURI, BURS) (known as "Backup-rolls") are respectively represented below the lower intermediate cylinder (IRI) and above the upper intermediate cylinder (BURS). ). The example thus given is a partial representation of a type 18-High rolling mill cage containing in all 18 cylinders, only 6 cylinders the complement of the other 12 lateral cylinders are shown as said above in Figure 0. These additional cylinders are however not major to describe the invention. In this sense too, the figure 4 is the device (simplified, without additional cylinders) according to figure 2 in an open rolling mill cage, in order to better visualize the working cylinders and the intermediate cylinders - here represented in motorized state by the rotating motor drives (MIRI, MIRS) - as well as the rollers / rolls of the thrust means.

The Figure 5A (de-docking of a working cylinder) and 5B and the Figure 5B (docking of an additional work roll) takes a significant figure from the document WO2009153415A1 in order to be able to describe on the basis of a simple example and to propose a method of on-the-fly change of working rolls by rolling of a metal product in uninterrupted rolling and rolling, arranged in at least a first and a second cage (C2, CA) rolling mill (here consisting of six cages tandem juxtaposed an additional cage (CA) is inactive when the other cages are active in rolling mode) of a metal product such as a strip (B) scrolling (Only a half upper layer thickness is represented, the so-called cages (C1, C2, C3, C4, C5 or C6 = CA) being juxtaposed in tandem in the direction of the scrolling (X) .This method of change on the fly characterized in that the first cage (C2) moves apart (de-docking) its working rolls out of the belt, after the second cage (CA = C1 or C3 or C4 or C5 or C6) dedicated to the change activated a setting device in rotation according to the invention (not shown) to approach and ultimately docking its working rolls to the band.

It is thus deductible, because of the introduction of at least one device according to the invention in the rolling mill stands, that this method of changing the work roll (on the fly or not also) is better controlled in term speed synchronization with the running belt, non-slip between work roll and rotating motorized intermediate cylinder and therefore better control of the quality and finally of rolling productivity and reduction of the strip lengths out of tolerance of thickness output and downstream processing processes.

Claims (10)

1. Device for rotating working rolls of a rolling mill synchronised with the speed of a moving strip (B) undergoing a rolling operation in a plurality of roll stands, comprising a set of rolls below the strip and a set of rolls above the strip, said set of lower rolls comprising at least one lower intermediate roll (IRI) rotating a lower working roll (WRI) by surface contact and friction, said set of upper rolls comprising at least one upper intermediate roll (IRS) rotating an upper working roll (WRS) by surface contact and friction, said lower and upper working rolls being capable of being put into contact with respectively one of the lower and upper faces of the strip to be rolled, said intermediate and working rolls having axes of rotation aligned in at least one vertical plane,
   characterised in that:

   before bringing the lower working rolls into contact with the strip for active rolling positions, a means of vertical thrust (R1i, R2i, P1I, P2I, EI, EI') exerts a first force downward on the lower working roll (WRI).
2. Device according to claim 1, wherein the means of vertical thrust (R1s, R2s, P1s, P2s, ES, ES') exerts a second force upward on the upper working roll (WRS).
3. Device according to claim 2, wherein the means of vertical thrust exerts the first and second forces at intensity values avoiding any slippage which is detrimental in any way at the points of surface contacts between each intermediate roll and its associated working roll.
4. Device according to claim 1 or 2, wherein the means of vertical thrust comprises first and second modules (EI, EI'; ES, ES') of the hoist type, said first module being capable of moving each lower and upper working roll away from or towards the strip.
5. Device according to one of claims 3, wherein the first and second modules of the hoist type comprise respectively a first and a second set of two contact support wheels or rollers (R1s, R2s, R1i, R2i), each of said sets being arranged at least perpendicular to one end and ideally perpendicular to each of the ends of each lower and upper working roll (WRI, WRS), said wheels or rollers of the first set of rollers (R1i, R2i) exerting the first force downward on the lower working roll (WRI) and said wheels or rollers of the second set of rollers (R1s, R2s) exerting the second force upward on the upper working roll (WRS).
6. Device according to one of claims 3, wherein the first and second modules (EI, EI'; ES, ES') of the hoist type comprise respectively a first and a second set of at least one runner (P1I, P2I; P1S, P2S) allowing contact with at least one ring of the bearing type (B1I, B2I; B1S, B2S) assembled perpendicular to each of the ends and ideally perpendicular to each of the pivots (Twri, Twrs) arranged at the ends of each lower and upper working roll (WRI, WRS), said first set of runners (P1I, P2I) exerting the first force downward on the lower working roll (WRI) and said second set of runners (P1S, P2S) exerting the second force upward on the upper working roll (WRS).
7. Device according to one of the preceding claims, wherein at least one of the means of vertical thrust (R1i, R2i; R1s, R2s; P1I, P2I; P1S, P2S) exerts a component of thrust on the working roll so that said roll can be moved in a horizontal direction (X) with respect to the associated intermediate roll.
8. Device according to one of the preceding claims, suitable for a rolling mill comprising stands of the 18-high type, wherein particularly the working rolls are not borne by guide and camber support chocks.
9. Device according to one of the preceding claims, suitable for a rolling mill comprising working rolls of small diameter as in the case of rolling a strip made of stainless steel and/or steel and other metallic materials with high yield strength and/or particularly for a low strip thickness close to 0.1 mm at the output from the rolling mill.
10. Method for changing working rolls arranged in at least a first and a second roll stand (C2, CA) for a moving metallic product (B), said stands being juxtaposed in tandem according to the direction of travel,
    characterised in that
    the first stand (C2) moves its working rolls away from the strip after the second stand (CA=C1, C3, C4, C5 or C6) dedicated to the change has activated a rotating device according to one of the preceding claims in order finally to bring its working rolls towards the strip.

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