Method for changing the rolls on a rolling mill

Abstract

Disclosed is a method for changing the rolls on a rolling mill for rolling a metal strip, carried out using a Quarto rolling mill, including lower and upper working and support rolls. The installation includes a system for extracting the working rolls and the support rolls, including: an actuator pushing the rolls out of the roll stand extraction; a coupling head, secured to the actuator, situated in a position of opening of the roll stand, including: a first coupler driving the chock or the end of the lower working roll, on the rolling-mill drive side; a second coupler driving the chock of the lower support roll, on the rolling-mill drive side. The first and second coupler allow successive extractions of the working rolls and then of the support rolls from the roll stand using the actuator of the extraction system. Also disclosed is a related rolling mill installation.

Claims

1. A method for changing rolls, the method being carried out in an installation having: a rolling mill configured to roll a metal strip, the rolling mill including: a roll stand, a set of the rolls having substantially parallel axes, the set of rolls being superimposed thereon one another, the set of superimposed rolls including a lower work roll and an upper work roll, the lower and upper work rolls defining a nip through which the metal strip passes, and a lower backup roll and an upper backup roll configured to respectively bear against the lower and upper work rolls on an opposite side to a side of the nip, each of the lower and upper work rolls and the lower and upper backup rolls having two ends mounted such that the ends rotate, each of the ends being on a bearing supported by a chock comprising a protruding portion, a guide between the chocks of the lower and upper work rolls and the lower and upper backup rolls and the roll stand along a clamping plane of the rolling mill, a force applicator configured to apply a clamping force between the chocks of the backup rolls, the force applicator comprising hydraulic cylinders, locking members and grooves configured to clamp the chocks of the lower and upper work rolls and the lower and upper backup rolls, locking the chocks in position relative to the roll stand along an axis of the respective roll of the lower and upper work rolls and the lower and upper backup rolls, and allowing the chocks to slide along the guide, along the clamping plane, a motor configured to drive the backup rolls, on a drive side of the roll stand of the rolling mill at which the motor is disposed, and a bracket; and an extraction system configured to extract the lower and upper work rolls and the lower and upper backup rolls provided on the drive side of the rolling mill, the extraction system comprising: an actuator configured to push the lower and upper work rolls and the lower and upper backup rolls out of the roll stand of the rolling mill when the lower and upper work rolls and the lower and upper backup rolls are extracted, or conversely to pull the lower and upper work rolls and the lower and upper backup rolls into the roll stand when the lower and upper work rolls and the lower and upper backup rolls are inserted, and a coupling head secured to the actuator, the coupling head being situated at an intermediate height between the lower work roll and the lower backup roll when the roll stand is in an open condition in which the upper and lower work rolls and the upper and lower backup rolls are distanced from each other, the coupling head being configured to move in a direction parallel to the lower and upper work rolls and the lower and upper backup rolls, from a first retracted position in which the coupling head is located on the drive side, to a second deployed position in which the coupling head passes through the roll stand and is located on an operator side opposite to the drive side relative to the roll stand, the coupling head comprising: a rigid hook configured to drive the chock or one of the ends of the lower work roll on the drive side of the rolling mill, and at least one coupling hook configured to drive the chock of the lower backup roll on the drive side of the rolling mill, the at least one coupling hook having a retracted state in which the at least one coupling hook does not drive the chock of the lower backup roll and a deployed state in which the at least one coupling hook drives, by a pushing action, the chock of the lower backup roll, the chocks of the upper and lower work rolls having at least one connector on the operator side creating a mechanical connection between the chocks on the operator side, the method according to the following successive steps when the roll stand of the rolling mill is in the open condition: extracting, in a first extraction step, the upper work roll and the lower work roll by the pushing action from the actuator on the chock of the lower work roll, on the drive side, the coupling head passing from the first retracted position to the second deployed position, the upper work roll being driven together with the lower work roll via the created mechanical connection, on the operator side, between the chocks of the lower and upper work rolls, the at least one coupling hook of the coupling head being in the retracted state, in which the at least one coupling hook does not drive the chocks of the backup rolls during the pushing action; passing the at least one coupling hook from the retracted state by manual action on the at least one coupling hook, the coupling head in the first deployed position being accessible on the operator side of the rolling mill; returning, in a return step, the coupling head back from the second deployed position towards the drive side into the first retracted position; extracting, in a second extraction step, the lower backup roll from the roll stand by the pushing action from the actuator on the chock of the lower backup roll on the drive side, the coupling head passing from the first retracted position to the second deployed position, the at least one coupling hook being in the deployed state driving the pushing of the chock of the lower backup roll; positioning, in a positioning step, the bracket on the lower backup roll, the bottom portion of a bracket bearing against the chocks of the lower backup roll, a top portion of the bracket being configured to support the chocks of the upper backup roll, the bracket being configured to be inserted into the roll stand; inserting, in an inserting step, the lower backup roll and the bracket into the roll stand, by a pulling force exerted by returning the coupling head towards the drive side, from the second deployed position into the first retracted position, the bracket having a clearance through which the metal strip passes when the metal strip is inserted into the roll stand; depositing, in a depositing step, the upper backup roll on the top portion of the bracket, by an action of lowering the upper backup roll; and extracting, in a third extraction step, the lower backup roll, the bracket, and the upper backup roll by the pushing action from the actuator on the chock of the lower backup roll, on the drive side, wherein the lower work roll and the lower backup roll are distanced from the upper work roll and from the upper backup roll when the metal strip is present along a through feed plane of the rolling mill.

2. The method according to claim 1, wherein: the roll stand of the rolling mill comprises roll stand support rails on which the chocks of the lower and upper work rolls rest, in the open condition of the roll stand, the method further comprises guiding, by the roll stand support rails, the lower and upper work rolls and the chock thereof during the first extraction step, the second extraction step, and the third extraction step, and the rolling mill further comprises a support car comprising support car support rails, and the method further comprises supporting and guiding the chocks of the lower and upper work rolls, by rollers of the chocks rolling along the roll stand support rails, in a position of the car relative to the rolling mill, and loading the lower and upper work rolls onto the support car when the coupling head reaches the second deployed position during the first extraction step.

3. The method according to claim 2, wherein the rigid hook is rigidly connected to the coupling head, and the method further comprises engaging the rigid hook with a corresponding hook secured to one of the ends of the lower work roll on the drive side by: exerting the pushing force on the lower work roll during the first extraction step and the passing of the coupling head from the first retracted position to the second deployed position, and exerting the pulling force on the lower work roll during the passing of the coupling head from the second deployed position to the first retracted position.

4. The method according to claim 2, wherein the at least one coupling hook comprises at least one movable hook articulated on a chassis of the coupling head, the at least one movable hook being configured to engage, under a pushing force, with the chock of the lower backup roll, the at least one movable hook being configured to be raised and locked in a retracted position in which the at least one movable hook does not engage with the chock of the lower backup roll on the drive side in the retracted state of the at least one coupling hook, the at least one movable hook being configured to project downwards in a deployed position under the effect of gravity in which the at least one movable hook engages with the protruding portion on a top surface of the chock of the lower backup roll on the drive side in the deployed state of the at least one coupling hook, and wherein: during the return step, engaging the protruding portion of the chock of the lower backup roll against the at least one movable hook, pivoting the at least one movable hook about the chassis in order for the at least one movable hook to escape from the protruding portion of the chock of the lower backup roll, returning the at least one movable hook to the deployed position on a side of the protruding portion of the chock of the lower backup roll under the effect of gravity, and during the second extraction step, abutting the at least one movable hook against the protruding portion of the chock of the lower backup roll under the effect of the pushing action from the actuator on the side of the protruding portion of the chock of the lower backup roll.

5. The method according to claim 2, wherein the at least one coupling hook comprises at least one folding hook configured to engage, under a hook pulling force, with the chock of the lower backup roll, and the method further comprises: in a deployed position of the at least one folding hook, abutting the at least the folding hook with the chock on the drive side of the lower backup roll in order to exert the hook pulling force, such that the lower backup roll and the bracket are inserted during the inserting step, and after the third extraction step, in a folded position of the at least one folding hook, uncoupling the coupling head from the lower backup roll extracted from the roll stand, during a return movement of the coupling head from the second deployed position to the first retracted position.

6. The method according to claim 3, wherein the engaging the rigid hook of the coupling head and the corresponding hook of the lower work roll occurs during movements of the car, in a direction perpendicular to the support car support rails.

7. The method according to claim 3, wherein the at least one coupling hook comprises at least one movable hook articulated on a chassis of the coupling head, the at least one movable hook being configured to engage, under a pushing force, with the chock of the lower backup roll, the at least one movable hook being configured to be raised and locked in a retracted position in which the at least one movable hook does not engage with the chock of the lower backup roll on the drive side in the retracted state of the at least one coupling hook, the at least one movable hook being configured to project downwards in a deployed position under the effect of gravity in which the at least one movable hook engages with the protruding portion on a top surface of the chock of the lower backup roll on the drive side in the deployed state of the at least one coupling hook, and wherein: during the return step, engaging the protruding portion of the chock of the lower backup roll against the at least one movable hook, pivoting the at least one movable hook about the chassis in order for the at least one movable hook to escape from the protruding portion of the chock of the lower backup roll, returning the at least one movable hook to the deployed position on a side of the protruding portion of the chock of the lower backup roll under the effect of gravity, and during the second extraction step, abutting the at least one movable hook against the protruding portion of the chock of the lower backup roll under the effect of the pushing action from the actuator on the side of the protruding portion of the chock of the lower backup roll.

8. The method according to claim 3, wherein the at least one coupling hook comprises at least one folding hook configured to engage, under a hook pulling force, with the chock of the lower backup roll, and the method further comprises: in a deployed position of the at least one folding hook, abutting the at least the folding hook with the chock on the drive side of the lower backup roll in order to exert the hook pulling force, such that the lower backup roll and the bracket are inserted during the inserting step, and after the third extraction step, in a folded position of the at least one folding hook, uncoupling the coupling head from the lower backup roll extracted from the roll stand, during a return movement of the coupling head from the second deployed position to the first retracted position.

9. The method according to claim 6, wherein the at least one coupling hook comprises at least one movable hook articulated on a chassis of the coupling head, the at least one movable hook being configured to engage, under a pushing force, with the chock of the lower backup roll, the at least one movable hook being configured to be raised and locked in a retracted position in which the at least one movable hook does not engage with the chock of the lower backup roll on the drive side in the retracted state of the at least one coupling hook, the at least one movable hook being configured to project downwards in a deployed position under the effect of gravity in which the at least one movable hook engages with the protruding portion on a top surface of the chock of the lower backup roll on the drive side in the deployed state of the at least one coupling hook, and wherein: during the return step, engaging the protruding portion of the chock of the lower backup roll against the at least one movable hook, pivoting the at least one movable hook about the chassis in order for the at least one movable hook to escape from the protruding portion of the chock of the lower backup roll, returning the at least one movable hook to the deployed position on a side of the protruding portion of the chock of the lower backup roll under the effect of gravity, and during the second extraction step, abutting the at least one movable hook against the protruding portion of the chock of the lower backup roll under the effect of the pushing action from the actuator on the side of the protruding portion of the chock of the lower backup roll.

10. The method according to claim 1, wherein the at least one coupling hook comprises at least one movable hook articulated on a chassis of the coupling head, the at least one movable hook being configured to engage, under a pushing force, with the chock of the lower backup roll, the at least one movable hook being configured to be raised and locked in a retracted position in which the at least one movable hook does not engage with the chock of the lower backup roll on the drive side in the retracted state of the at least one coupling hook, the at least one movable hook being configured to project downwards in a deployed position under the effect of gravity in which the at least one movable hook engages with the protruding portion on a top surface of the chock of the lower backup roll on the drive side in the deployed state of the at least one coupling hook, and wherein: during the return step engaging the protruding portion of the chock of the lower backup roll against the at least one movable hook, pivoting the at least one movable hook about the chassis in order for the at least one movable hook to escape from the protruding portion of the chock of the lower backup roll, returning the at least one movable hook to the deployed position on a side of the protruding portion of the chock of the lower backup roll under the effect of gravity, and during the second extraction step, abutting the at least one movable hook against the protruding portion of the chock of the lower backup roll under the effect of the pushing action from the actuator on the side of the protruding portion of the chock of the lower backup roll.

11. The method according to claim 1, wherein the at least one coupling hook comprises at least one folding hook configured to engage, under a hook pulling force, with the chock of the lower backup roll, and the method further comprises: in a deployed position of the at least one folding hook, abutting the at least the folding hook with the chock on the drive side of the lower backup roll in order to exert the hook pulling force, such that the lower backup roll and the bracket are inserted during the inserting step, and after the third extraction step, in a folded position of the at least one folding hook, uncoupling the coupling head from the lower backup roll extracted from the roll stand, during a return movement of the coupling head from the second deployed position to the first retracted position.

12. The installation according to claim 1, wherein, the chocks on the operator side of the lower and upper work rolls have parallel sliding plates distributed on either side of the axis of the respective roll, the parallel sliding plates being configured to engage with sliding plates secured to two uprights on the operator side of the rolling mill, the at least one connector comprises at least one tab, a proximal end of the at least one tab being secured to one of the lower or upper chocks, the proximal end of the at least one tab being received in a lateral groove made in a body of the respective chock at a back of one of the sliding plates, a distal end of the at least one tab penetrating a groove of the other of the lower or upper chock, at least in a deployed position of the tab, in the open condition of the roll stand.

13. The method according to claim 1, wherein the rigid hook is rigidly connected to the coupling head, and the method further comprises engaging the rigid hook with a corresponding hook secured to one of the ends of the lower work roll on the drive side by: exerting the pushing force on the lower work roll during the first extraction step and the passing of the coupling head from the first retracted position to the second deployed position, and exerting the pulling force on the lower work roll during the passing of the coupling head from the second deployed position to the first retracted position.

14. The method according to claim 1, wherein in the open condition, the chocks of the upper and lower upper rolls are automatically unclamped.

15. A rolling mill installation comprising: a rolling mill configured to roll a metal strip, the rolling mill comprising: a roll stand, a set of superimposed rolls having substantially parallel axes, the set of superimposed rolls comprising a lower work roll and an upper work roll, the lower and upper work rolls defining a nip through which the metal strip passes, and a lower backup roll and an upper backup roll configured to respectively bear against the lower and upper work rolls on an opposite side to a side of the nip, each of the lower and upper work rolls and the lower and upper backup rolls having two ends mounted such that the ends rotate, each of the ends being on a bearing supported by a chock comprising a protruding portion, a guide between the chocks of the lower and upper work rolls and the lower and upper backup rolls and the roll stand along a clamping plane of the rolling mill, a force applicator configured to apply a clamping force between the chocks of the backup rolls, the force applicator comprising hydraulic cylinders, locking members and grooves configured to clamp the chocks of the lower and upper work rolls and the lower and upper backup rolls, locking the chocks in position relative to the roll stand along an axis of the respective roll of the lower and upper work rolls and the lower and upper backup rolls, and allowing the chocks to slide along the guide, along the clamping plane, a motor configured to drive the backup rolls, on a drive side of the roll stand of the rolling mill at which the motor is disposed, and a bracket; and an extraction system configured to extract the lower and upper work rolls and the lower and upper backup rolls provided on the drive side of the rolling mill, the extraction system comprising: an actuator configured to push the lower and upper work rolls and the lower and upper backup rolls out of the roll stand of the rolling mill when the lower and upper work rolls and the lower and upper backup rolls are extracted, or conversely to pull the lower and upper work rolls and the lower and upper backup rolls into the roll stand when the lower and upper work rolls and the lower and upper backup rolls are inserted, and a coupling head secured to the actuator, the coupling head being situated at an intermediate height between the lower work roll and the lower backup roll when the roll stand is in an open condition in which the upper and lower work rolls and the upper and lower backup rolls are distanced from each other, the coupling head being configured to move in a direction parallel to the lower and upper work rolls and the lower and upper backup rolls, from a first retracted position in which the coupling head is located on the drive side, to a second deployed position in which the coupling head, passes through the roll stand and is located on an operator side opposite to the drive side relative to the roll stand, the coupling head comprising: a rigid hook configured to drive the chock or one of the ends of the lower work roll on the drive side of the rolling mill, and at least one coupling hook configured to drive the chock of the lower backup roll on the drive side of the rolling mill, the at least one coupling hook having a retracted state in which the at least one coupling hook does not drive the chock of the lower backup roll and a deployed state in which the at least one coupling hook drives, by a pushing action, the chock of the lower backup roll, wherein the chocks of the upper and lower work rolls have at least one connector on the operator side creating a mechanical connection between the chocks on the operator side, wherein the rigid hook and the at least one coupling hook of the extraction system are configured to allow: successive extractions of the lower and upper work rolls and then successive extractions of the lower and upper backup rolls from the roll stand, and successive insertions of the lower and upper backup rolls and then successive insertions of the lower and upper work rolls into the roll stand, and wherein the at least one coupling hook comprises at least one movable hook articulated on a chassis of the coupling head, the at least one movable hook being configured to engage, under a pushing force, with the chock of the lower backup roll, the at least one movable hook being configured to be raised and locked in a retracted position in which the at least one movable hook does not engage with the chock of the lower backup roll on the drive side of the rolling mill in the retracted state of the at least one coupling hook, the at least one coupling hook being in a deployed state in which the at least one movable hook being configured to project downwards in a deployed position under the effect of gravity the at least one movable hook being manually actuatable to pass from the retracted position to the deployed position, or from the deployed position to the retracted position, the at least one movable hook being configured in the deployed state to engage with the protruding portion on a top surface of the chock of the lower backup roll on the drive side the roll stand; wherein passing the coupling head from the second deployed position to the first retracted position causes engaging of the protruding portion against the at least one movable hook that pivots about the chassis, in order to escape from the protruding portion, returning the at least one movable hook to the deployed position on a side of the protruding portion of the chock of the lower backup roll under the effect of gravity, and the at least one movable hook, in the position on the other side of the protruding portion, abuts against the protruding portion under the effect of the pushing action from the actuator such that the lower backup roll is extracted.

16. The installation according to claim 15, wherein: the roll stand of the rolling mill comprises roll stand support rails on which the chocks of the lower and upper work rolls are supported, in the open condition of the roll stand, the support rails being used to guide the lower and upper work rolls and the chock thereof during extracting the rolls inside the roll stand, and the rolling mill comprises a support car having support car support rails configured to support and guide the chocks of the lower and upper work rolls, the chocks of the lower and upper work rolls rolling along the roll stand support rails in a position of the support car relative to the rolling mill, the lower and upper work rolls being configured to be loaded onto the car when the pushing force is exerted by the actuator on the lower and upper work rolls.

17. The installation according to claim 16, wherein the rigid hook is rigidly connected to the coupling head, the rigid hook being configured to engage with a corresponding hook secured to one of the ends of the lower work roll, the rigid hook being configured to: exert a pushing force on the lower work roll during pushing of the coupling head from the first retracted position to the second deployed position, and exert a pulling force on the lower work roll during passage of the coupling head from the second deployed position to the first retracted position.

18. The installation according to claim 17, wherein the engaging of the rigid hook of the coupling head and the corresponding hook of the lower work roll occurs during movements of the car, in a direction perpendicular to the support car support rails.

19. The installation according to claim 15, wherein the at least one coupling hook comprises at least one folding hook configured to engage, under a pulling force, with the chock of the lower backup roll, on the drive side, such that: in a deployed position of the at least one folding hook, the chock on the drive side abuts the lower backup roll in order to exert an additional pulling force, allowing the lower backup roll to be inserted into the stand of the rolling mill, and in a folded position of the at least one folding hook, the coupling head is uncoupled from the lower backup roll extracted from the roll stand, during return movement of the coupling head from the second deployed position to the first retracted position.

20. The installation according to claim 19, wherein the at least one folding hook is a member that is manually actuated for the passing from the deployed position of the at least one folding hook to the folded position of the at least one folding hook, or from the folded position to the deployed position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood upon reading the following description, given with reference to the accompanying figures, in which: FIG. 1 is a perspective overview showing the Quarto type rolling mill, including the roll stand, in which are present the backup and work rolls, the system for driving the backup rolls of the rolling mill, and the single-actuator extraction system, of the rack and pinion type, situated on the drive side of the rolling mill, the perspective view further showing, on the operator side of the roll stand (opposite that of the drive system), the support car for supporting the work rolls, U-shaped support equipment (removable), capable of being inserted into the roll stand, intended to withdraw the two backup rolls together, as well as handling members intended for lifting the backup and work rolls, or the said support equipment, FIG. 2 is a sectional view along a plane passing through the clamping plane of the rolling mill, more particularly showing the extraction system, in the said first retracted position of the coupling head, FIG. 3 is a detailed view of FIG. 2 more particularly showing the hook of the first coupling means of the coupling head, in contact with a corresponding hook secured to the end (on the drive side) of the lower work roll, in the first retracted position of the coupling head, FIG. 4 is a sectional view of the rolling mill, along a vertical plane perpendicular to the rolls, FIG. 5 is an exposed view of the roll stand of the rolling mill, FIGS. 6 and 7 are views of the work and backup rolls, respectively in the closed and open position of the roll stand, FIGS. 8 and 9 are partial views of the rolling mill installation, on the operator side, showing the support car for the work rolls, respectively in a retracted position of the extraction area, and in a position of the car allowing the work rolls to be received during the extraction thereof, FIG. 10 is a detailed view of the chocks (on the operator side) of the work rolls, and more particularly of the members allowing for the creation of a mechanical connection for withdrawing the two work rolls together when the actuator of the extraction system solely exerts a pushing force (on the drive side) on the lower work roll, FIG. 11 is a view, on the drive side of the rolling mill, in the first retracted position of the coupling head, the said first coupling means thus being in contact with the end of the lower backup roll, the said second coupling means in the retracted state wherein they are not pushing the lower backup roll, FIG. 12 is a view successive to that of FIG. 11, showing the first extraction step wherein the actuator drives the coupling head by a pushing action, thus in contact with the lower work roll, thus causing the lower work roll to be extracted together with the upper work roll thanks to the mechanical connection shown in FIG. 10, whereby the upper and lower work rolls are thus loaded on the support rails of the support car, and whereby the backup rolls, which are not driven, remain inside the roll stand, FIG. 13 is a view consecutive to that of FIG. 12, whereby the upper and lower work rolls are thus extracted from the roll stand and entirely supported by the car when the said coupling head is in the second deployed position thereof, FIG. 14 is a view consecutive to that of FIG. 13, wherein the support car is displaced laterally, freeing the extraction area, on the operator side of the roll stand, FIGS. 15 and 16 are respectively two views of the coupling head thus located, on the operator side, in the said second deployed position, the said movable element articulated on the chassis of the coupling head along a horizontal pivot axis, being manually shifted from a retracted position shown in FIG. 15 for which the said movable element is not capable of interacting with the chock of the lower backup roll, to a deployed position, shown in FIG. 16, allowing abutment with the chock (on the drive side) of the lower backup roll, during the return of the coupling head towards the drive side, FIGS. 17 and 18 are two detailed views showing the passage of the backup roll chock clamping system from a locked chock position to an unlocked position, making the axial displacement of the backup rolls possible, FIG. 19 is a view showing the step of returning the coupling head to the first retracted position, FIGS. 20 to 23 are respectively successive, detailed views of the return of the coupling head from the second deployed position to the first retracted position, whereby the figures respectively show the engagement of a protruding portion on the top surface of the chock against the movable element, freely articulated, which, during the return of the coupling head, pivots about its articulation under the effect of the protruding portion in order to escape the said protruding portion, before returning, under the effect of gravity, to the position wherein the said movable element projects downwards, on the other side of the protruding portion of the chock, in the said first position of the coupling head; FIG. 24 is a view consecutive to that of FIG. 23, showing the second extraction step wherein the lower backup roll is extracted under the pushing action of the coupling head, thanks to the movable member of the second coupling means which abuts against the protruding portion of the chock on the drive side, FIG. 25 is a view consecutive to that of FIG. 24, wherein the backup roll is fully extracted in the said second deployed position of the coupling head, FIG. 26 is a view consecutive to that of FIG. 25 showing the positioning of a support element, capable of being inserted into the roll stand, the bottom portion whereof is at rest on the chocks of the lower backup roll, and the top portion whereof is provided such that it supports the chocks of the upper backup roll, FIG. 27 is a detailed view of the coupling head, more particularly showing two folding elements in the deployed position thereof, allowing abutment with the chock (on the drive side) of the lower backup roll in order to exert a pulling force, and thus allow for the insertion of the lower backup roll into the stand of the rolling mill, FIG. 28 is a view showing the insertion step wherein the lower backup roll and the said support equipment are inserted together into the roll stand, under the pulling action caused by the return of the coupling head towards the drive side, whereby the metal strip is thus received inside an intermediary clearance of the support equipment, FIGS. 29 and 30 are consecutive views showing the depositing step wherein the upper backup roll is deposited on the top portion of the support equipment by an action of lowering the said upper backup roll, FIG. 31 is a view showing the third extraction step wherein the coupling head jointly extracts, during the pushing action by the actuator, the lower backup roll, the support equipment and the upper backup roll, FIG. 32 is a detailed view of the coupling head, more particularly showing the folding elements in the folded position thereof, subsequent to a manual action performed on the operator side, allowing the coupling head to be uncoupled from the said lower backup roll during the return movement of the coupling head towards the drive side, FIG. 33 is a view successive to that of FIG. 32 showing the step of uncoupling the coupling head from the said lower backup roll.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(2) Thus, the invention relates to a rolling mill 1, in particular of the Quarto type, for rolling a metal strip comprising a roll stand 2, comprising two pairs of uprights, at the two ends of the stand between which a set of superimposed rolls are provided, the said rolls having substantially parallel axes, comprising two work rolls 3, 4, one lower and one upper, defining the nip through which passes the strip, and two backup rolls 5, 6, one upper and one lower respectively, intended to bear respectively against the work rolls on the opposite side to the side of the passage nip.

(3) Each work roll or backup roll has two ends, generally referred to as roll necks, mounted such that they rotate, each on a bearing supported by a chock 30, 40, 50, 60.

(4) The rolling mill further comprises guide means between the chocks 30, 40, 50, 60 of the rolls and the roll stand 2 along the clamping plane. The said guide means can comprise sliding surfaces between the chocks and the frame (in particular the uprights) of the roll stand 2.

(5) For example: each chock 30 of the upper work roll 3 has two sliding plates 31, parallel to and opposite one another, distributed on either side of the rotational axis of the work roll 3, engaging with two sliding plates 27, respectively rigidly secured to the uprights of the same pair at one end of the roll stand, each chock 40 of the lower work roll 4 has two sliding plates 41, parallel to and opposite one another, distributed on either side of the rotational axis of the work roll 4, engaging with the sliding plates 27, respectively rigidly secured to the uprights of the same pair at one end of the roll stand.

(6) For example, the two sliding plates 27 are respectively secured on the inner walls of two bending cylinder units Vc3, Vc4, themselves respectively secured, via the outer wall thereof, to the two inner walls of the uprights of the same pair of uprights of the stand.

(7) Similarly: each chock 50 of the upper backup roll 5 can have two sliding plates 51, parallel to and opposite one another, distributed on either side of the rotational axis of the backup roll 5, engaging with sliding plates 25, rigidly secured to the uprights of the same pair at one end of the roll stand, and each chock 60 of the lower backup roll 6 can have two sliding plates 61, parallel to and opposite one another, distributed on either side of the rotational axis of the backup roll 6, engaging with sliding plates 26, rigidly secured to the uprights of the same pair at one end of the roll stand.

(8) The rolling mill further comprises means for applying a clamping force between the chocks of the backup rolls, generally comprising hydraulic cylinders V.sub.S. The said hydraulic cylinders V.sub.S, two of which are present, can be arranged in the lower portion of the roll stand and can respectively bear against the two chocks 60 of the lower backup roll 6. According to one embodiment, not shown, the said hydraulic cylinders V.sub.S can also be provided in the upper portion of the roll stand 2 and can respectively bear against the chocks of the upper backup roll.

(9) The rolling mill further comprises a clamping system for clamping the chocks 30, 40 of the work rolls 3 and 4, and a clamping system 9 for clamping the chocks 50, 60 of the backup rolls 5, 6.

(10) The clamping system for clamping the work rolls shown in the examples is that disclosed by the Applicant of the French patent application FR 1652265 of 17 Mar. 2016, which allows the chocks of the work rolls to be locked, or conversely allows the work rolls to be axially displaced under the opening and closing actions of the roll stand. The description of this system for clamping the work rolls is not explicitly repeated herein. However, one of ordinary skill in the art can refer to the said document for the execution thereof. Within the scope of this application, other systems for clamping the work rolls can be considered, and in particular a system with dedicated cylinders disclosed in the prior art in the patent application FR 1652265.

(11) The clamping system 9 for clamping the chocks of the backup rolls for passing from a retracted state, allowing the backup rolls to be withdrawn, along the axis thereof, from the roll stand, to a locking state locking the chocks in position relative to the stand, along the axis of the roll, while allowing the chocks to slide along the guide means, along the clamping plane.

(12) The said clamping system 9 can comprise vertical grooves in the chocks 50, 60 of the upper backup roll 5 and of the lower backup roll 6, as well as locking members 90, mounted such that they slide horizontally. Each locking member can pass from a position wherein it penetrates the vertical groove of the chocks 50 or 60, preventing the axial displacement of the backup roll, to a retracted position wherein axial displacement is made possible. Given the frequency of maintenance operations for the backup rolls, the clamping system can be manual, whereby the passage from the retracted position to the locking position is manual and obtained by actuating a handle 91.

(13) The rolling mill further comprises drive means 10 for driving the backup rolls, on one side of the roll stand of the rolling mill, referred to as the drive side hereinbelow.

(14) In a conventional manner for one of ordinary skill in the art, an electric motor M is used to drive the lower and upper backup rolls via a transmission connecting the motor output to the ends of the backup rolls, on the drive side.

(15) The invention disclosed here more particularly concerns the system for extracting work rolls and backup rolls, and which is situated on the drive side of the said rolling mill.

(16) The said extraction system allows, as will be described hereafter, the extraction of worn rolls from the roll stand of the rolling mill, in particular with a view to the re-turning thereof, as well as the insertion of freshly turned (or new) rolls into the roll stand.

(17) For this purpose, the extraction system comprises: an actuator 70 configured to push the rolls out of the roll stand 2 of the rolling mill when the rolls are being extracted, or conversely to pull the rolls into the roll stand 2 when the rolls are being inserted, a coupling head 8 secured to the said actuator 70, situated in an open position of the roll stand 2 at an intermediate height between the lower work roll 4 and the lower backup roll 6, capable of moving in a direction parallel to the rolls 3, 4, 5, 6.

(18) The actuator can comprise a motorised rack 71 and pinion 72 pair, whereby the chassis of the coupling head 8 is rigidly secured to the distal end of the rack 71. The rotation of the pinion 72 in a first direction allows for the translational movement of the rack along the axis thereof, as well as for the translational movement of the coupling head 8.

(19) The coupling head 8 is capable of moving from a first retracted position P1 wherein the coupling head is located on the drive side, to a second deployed position P2 wherein the coupling head 8, having passed through the roll stand 2, is located on the operator side and accessible to operators.

(20) Moreover, said coupling head 8 comprises first coupling means configured to drive the chock 40 or the end of the lower work roll 4, on the drive side of the rolling mill, second coupling means configured to drive the chock 60 of the lower backup roll 6, on the drive side of the rolling mill: the second coupling means having a retracted state wherein they do not drive the chock of the lower backup roll 6 and a deployed state wherein they drive, by a pushing action, the chock 60 of the said lower backup roll 6.

(21) In a noteworthy manner, the chocks 30, 40 of the upper and lower work rolls have connection means 11, on the operator side, opposite the drive means, creating a mechanical connection 12 between the said chocks on the operator side.

(22) The said mechanical connection 12 ensures the joint withdrawal of the two work rolls 3, 4 when the actuator 70 of the extraction system solely exerts a pushing force (on the drive side) on the lower work roll, and as explained hereafter.

(23) For example, and as shown in FIG. 10, whereby the chocks on the operator side of the work rolls have the said parallel sliding plates 31, 41 (not shown) distributed on either side of the axis of the roll, intended to engage with the sliding plates 27 secured to two uprights on the operator side of the rolling mill, the connection means 11 can comprise at least one tab 15 (or two tabs 15), the proximal end whereof is secured to a marked chock of either the lower or upper chocks, received in a lateral groove, made in the body of the chock, at the back of a sliding plate 31 or 41, and the distal end 16 whereof penetrates a groove of the other chock, at the back of the sliding plate, at least in a deployed position of the said tab, in the said open position of the roll stand.

(24) It should be noted that the (or each) tab 15 is substantially parallel to the sliding plates 31 or 41, whereby the distal end 16 of the tab can have a rounded contour so as to allow for a slight pivoting of the distal end in the groove, which will in particular occur during the bending action on the work rolls.

(25) The tab 15 can furthermore be provided such that it retracts into a retracted position inside the chock 30 (position not shown), the chock 30 having means for locking said tab 15 in the deployed position. The said means can comprise a ball and spring system. An oblong aperture 17 in the tab through which a stud 18 is intended to pass, the said stud being secured to the chock, can also be provided in order to prevent dismantling of the tab.

(26) Advantageously, the first coupling means and the second coupling means of the said extraction system are configured in such a way as to allow: successive extractions of the work rolls and then of the backup rolls from the roll stand. successive insertions of the backup rolls and then of the work rolls into the roll stand.

(27) In other words, the invention advantageously allows: all rolls of the rolling mill to be extracted (i.e. work rolls then backup rolls) by means of a single actuator, as opposed to the prior art known by the Applicant, all rolls of the rolling mill to be inserted (i.e. backup rolls then work rolls) by means of a single actuator, as opposed to the prior art known by the Applicant.

(28) As shall be understood from the following description, the extraction system allows for the possibility of extracting the work rolls only, then of inserting new work rolls (new or freshly turned rolls) into said roll stand (whereby the backup rolls remain in the roll stand).

(29) The description hereafter will describe the method for changing the rolls implemented in such a rolling mill installation, and more particularly the different steps implemented in order to extract the set of work rolls and backup rolls using the single-actuator extraction system. These different steps are shown in detail in FIGS. 6 to 33.

(30) One of ordinary skill in the art understands that the steps of the method allowing the backup rolls, then the work rolls to be inserted are essentially the same, but performed by reversing the order of the steps allowing for the rolls to be extracted.

(31) Moreover, the work rolls 3, 4 and the backup rolls 5, 6 are extracted, after opening the roll stand of the said rolling mill, during which step the lower work roll 4 and the lower backup roll 6 are distanced from the upper work roll 4 and from the upper backup roll 5, when the metal strip B is present along the through feed plane of the said rolling mill.

(32) This step of opening the rolling mill stand is shown in FIGS. 6 and 7, caused by the retraction of the hydraulic cylinders V.sub.S. If necessary, and according to one embodiment, said opening automatically results in the unclamping of the chocks 30, 40 of the work rolls 3, 4.

(33) Moreover, the work rolls 3, 4 and the backup rolls 5, 6 are extracted by implementing the following successive steps: a first extraction step E1 (see FIGS. 11 to 13) wherein the upper work roll 3 and the lower work roll 4 are extracted, by a pushing action from the said actuator 70 on the chock 40 of the lower work roll 4, on the drive side, the coupling head 8 passing from the first retracted position P1 to the second deployed position P2, the said upper work roll 3 being driven together with the lower work roll 4 via the mechanical connection 12 created, on the operator side, between the chocks 30, 40 of the lower and upper work rolls, the said second coupling means of the coupling head 8 being in the said retracted state, in which they do not drive the chocks of the backup rolls during the said pushing action, a return step E2 (see FIGS. 19 to 24) wherein the coupling head 8 is brought back from the second deployed position P2 towards the drive side into the first retracted position P1, a second extraction step E3 (see FIGS. 24 and 25) wherein the lower backup roll 6 is extracted from the roll stand 2 by a pushing action from the said actuator on the chock 60 of the lower backup roll 6 on the drive side, the coupling head 8 passing from the first retracted position P1 to the deployed position P2, the said second coupling means being in the said deployed state driving the pushing of the chock 60 of the said lower backup roll 6, a positioning step E4 (see FIGS. 26 and 27) wherein support equipment 13 is positioned on the lower backup roll 6, the bottom portion whereof bears against the chocks 60 of the lower backup roll 6, and the top portion whereof is intended to be used to support the chocks 50 of the upper backup roll, the said support equipment 13 being capable of being inserted into the roll stand 2, an insertion step E5 (see FIG. 28) wherein the lower backup roll 6 and the said support equipment 13 are inserted into the roll stand 2, by the pulling force exerted by the return of the coupling head 8 towards the drive side, from the deployed position P2 into the retracted position P1, the said support equipment 13 having a clearance 14 through which passes the metal strip B when inserted into the roll stand 2, a depositing step E6 (see FIGS. 29 and 30) wherein the upper backup roll 5 is deposited on the top portion of the support equipment 13, by an action of lowering the said upper backup roll 5, a third extraction step E7 (see FIG. 31) wherein the group constituted from the lower backup roll 6, the support equipment 13 and the said upper backup roll 5 is extracted by a pushing action from the said actuator 70 on the chock 60 of the lower backup roll 6, on the drive side.

(34) The roll stand 2 of the rolling mill generally comprises support rails R3, R4 on which rest the chocks 30, 40 of the upper and lower work rolls 3, 4, in the open position of the roll stand 2, the said support rails R3, R4 being used to guide the work rolls 3, 4 and the chock 30, 40 thereof during the extraction of the work rolls from the said roll stand or during the insertion of the work rolls into the roll stand.

(35) The roll stand further comprises support rails R6 on which the chocks 60 of the said lower backup roll 6 are at rest in the open position of the roll stand 2, whereby the chocks 60 have rollers 63 intended to roll along the rails R6, and whereby other rails extend from the rails R6 at the level of the extraction area on the operator side.

(36) The rolling mill installation can comprise a support car 20 comprising support rails R3′, R4′ suitable for supporting and guiding the chocks 30, 40 of the lower and upper work rolls 3, 4 which, in a position of the car relative to the rolling mill, extend the support rails R3, R4 of the rolling mill, and such that the lower and upper work rolls are loaded together onto the car 20 when the pushing force is exerted by the actuator on the work rolls 3, 4 or conversely are unloaded from the car in order to be inserted into the roll stand during the insertion of the rolls.

(37) The said support car 20 is capable of moving along rails perpendicular to the support rails, in order to allow the car to be laterally retracted into a position outside of the extraction area, and as shown in FIG. 8.

(38) A handling chassis M.sub.T is used to withdraw the work rolls 3, 4 from above, thanks to a travelling crane in the workshop.

(39) The said car 20 is maintained in the said retracted position outside of the extraction area, in particular during steps wherein the backup rolls are inserted or withdrawn.

(40) As shown in the figures, the car can have four parallel pairs of support rails, so as to be able to support two pairs of upper and lower work rolls side by side.

(41) If only the work rolls 3, 4 are to be changed, a pair of upper and lower work rolls can thus be withdrawn together onto the support car 20 and another pair of work rolls (new or freshly turned rolls) can be immediately loaded, after being previously positioned on the support car, just after a short lateral displacement of the car so as to align the support rails R3′ and R4′ of the said new rolls with those R3 and R4 of the roll stand 2.

(42) The first coupling means can substantially comprise a hook 81 rigidly connected to the coupling head 8, intended to engage with a corresponding hook 42 secured to the end, on the drive side, of the lower work roll 4, and suitable for: exerting a pushing force on the lower work roll 4 during the action of pushing the coupling head 8 from the first retracted position P1 to the second deployed position P2, exerting a pulling force on the lower work roll 4 during the passage of the coupling head 8 from the second deployed position P2 to the first retracted position P1.

(43) The said hook 81 is initially in contact with the corresponding hook 42 at the end of the lower work roll, in the said first retracted position P1 of the coupling head, and as shown in FIG. 3 or 11.

(44) Advantageously, the two mutually engaging hooks 81 and 82 are configured such that the clamping and unclamping between, on the one hand, the hook 81 of the first coupling means of the coupling head 8, and on the other hand, the corresponding hook 42 of the lower work roll 4, take place under the movements of the car 20, in a direction perpendicular to the support rails R3′, R4′.

(45) The coupling (or uncoupling) of the coupling head 8 with the lower work roll 4 is thus automatic thanks to the motorised displacement of the support car, and does not require a dedicated actuator.

(46) As shown in FIGS. 12 and 13, the support rails R3′ and R4′ of the support car are aligned with the support rails R3 and R4 during the first extraction step E1.

(47) At the end of the extraction step, the car 20 is retracted in a position outside of the extraction area, on the operator side, and as shown in FIG. 14, whereas the coupling head is in the second deployed position P2, accessible from the operator side.

(48) This access to the coupling head 8 advantageously allows, according to the invention, an operator to pass the second coupling means from the retracted state wherein they are not driving the chock of the lower backup roll, to the deployed state wherein they are pushing the chock of the said lower backup roll under a manual action by the operator on said second coupling means. This manual action is successive to the said first extraction step, performed while the coupling head is in the said second deployed position and accessible from the operator side of the said rolling mill, and prior to the said coupling head return step.

(49) For this purpose, the second coupling means can comprise at least one movable element 82, articulated on the chassis of the coupling head, suitable for engaging under a pushing force with the chock 60 of the lower backup roll 6. in the retracted state of the second coupling means, the said at least one movable element 82 is raised and locked in a retracted position P3, shown by way of example in FIG. 15, wherein the said movable element 82 does not engage with the chock 60, of the lower backup roll 6, on the drive side of the rolling mill, in the deployed state of the second coupling means, the said at least one movable element 82 is in a deployed position P4, shown by way of example in FIG. 16, wherein the said movable element 82 projects downwards under the effect of gravity.

(50) The passage from the retracted position P3 to the deployed position is thus made possible by a manual action from the operator, when the coupling head 8 is accessible from the operator side. In the retracted position, the movable member 82 can be locked in position by any suitable means and, for example, by means of a yoke 85, articulated on the chassis, which, in one position, allows the movable member 82 to be maintained in a raised position by engagement with a prong 84 rigidly secured to the movable member. Unlocking takes place by moving the yoke 85 about the pivot thereof, the said displacement causing the movable member to be released, which pivots the head downwards, for example half a turn under the effect of gravity.

(51) The said movable element 82 is configured in the said deployed position P4 in order to engage with a protruding portion 62 on the top surface of the chock 60 of the lower backup roll 6 on the drive side, present in the roll stand.

(52) As shown in FIGS. 20 to 23, the said passage of the coupling head 8 from the second deployed position P2 to the first retracted position P1 causes the engagement of the protruding portion 62 against the movable element 82, which pivots about the articulation thereof under the effect of the protruding portion 62 (see FIGS. 20 to 22), in order to escape from the said protruding portion 62, before returning, under the effect of gravity, to the position (see FIG. 23) wherein the said movable element 82 projects downwards, on the other side of the protruding portion 62. In other words, during the return of the coupling head, the said movable element 82 is configured so as to escape a protruding portion 62 on the top surface of the chock 60 of the lower backup roll 6, thanks to the possible rotation of the said at least one movable element (in the clockwise direction in FIGS. 21 and 22).

(53) As shown in FIG. 24, the said movable element 82, thus in position on the other side of the protruding portion 62, abuts against the said protruding portion 62 under the effect of the pushing action from the actuator 70 and such that it allows the said lower backup roll 6 to be withdrawn during the second extraction step E3. During the extraction E3, it should be noted that the possibility of rotating the said movable element 82 (in the anti-clockwise direction) is prevented by a stop 86, which allows the said movable element 82 to convey the pushing force required to extract the lower backup roll 6 to the chock 60.

(54) Of course, prior to the extraction of the backup rolls, the axial displacement of the rolls must be made possible by unlocking the clamping system 9 for clamping the backup rolls.

(55) The second coupling means can comprise, as shown in the figures, two substantially parallel movable elements 82 rigidly secured, via the same rotating shaft, to the chassis of the head. The rotating shaft is substantially horizontal and perpendicular to the axis of the lower backup roll. The two movable elements are intended to respectively engage with two protruding portions on the top surface of the chock 60 of the lower backup roll 6.

(56) At the end of the second extraction step E3, the lower backup roll 6 is extracted from the roll stand 2, and as shown by way of example in FIG. 25. The next step is the said positioning step E4, wherein support equipment 13 is positioned on the lower backup roll 6 by means of a handling appliance (i.e. a travelling crane).

(57) The bottom portion of the said equipment bears against the chocks 60 of the lower backup roll 6. The top portion is intended to be used to support the chocks 50 of the upper backup roll 5. The said support equipment 13 is noteworthy in that it can be inserted (once the work rolls have been removed) into the roll stand 2, together with the lower backup roll.

(58) For this purpose, the second coupling means comprise at least one folding element 83 suitable for engaging (only) under a pulling force with the chock 60 of the lower backup roll 6 on the drive side, which in a deployed position P5 of the said folding element 83, allows for the abutment with the chock 60, on the drive side, of the lower backup roll 6 in order to exert a pulling force, allowing the lower backup roll 6 to be inserted into the stand of the rolling mill, in particular during step E5. in a folded position P6 of the said folding element 83, allows for the uncoupling of the coupling head from the said lower backup roll 6 extracted from the roll stand, during the return movement of the coupling head from the second deployed position P2 to the first retracted position P1.

(59) In a noteworthy manner, the said at least one folding movable element 83 can initially be in the deployed position P5 in that it does not allow a pushing force to be exerted on the roll.

(60) Two of the folding elements 83 can be present and can abut against the two protruding portions 62. The passage from the deployed position P5 to the folded position P6 can take place manually, for example by rotating the said element 83 by a limited angle, for example by a quarter turn. For this purpose, the or each element can have a cavity intended to receive a tool such as a key.

(61) The two folding elements in the deployed position P5 thereof allow, during the insertion step E5, for the lower backup roll 6 to be inserted together with the said support equipment 13 supported by the chocks 60 into the roll stand, and as shown in FIG. 28. It should be noted that the metal strip present in the through feed plane of the rolling mill becomes housed in an intermediate clearance 14 of the said support equipment 13.

(62) This then allows the upper backup roll 5 to be deposited onto the said support equipment, by lowering the upper backup roll 5, which action can take place by the deployment of a hydraulic cylinder V.sub.R and until the chocks 50 of the upper backup roll 5 are at rest on the said support equipment 13, whereby the said cylinders V.sub.R are conventionally also used to adjust the pass line.

(63) This is then followed by the third extraction step E7, wherein, via another pushing action from the said actuator 70 on the chock 60, on the drive side, of the lower backup roll 6, the assembly constituted from the lower backup roll 6, the support equipment 13 and the said upper backup roll 5 is extracted, the said coupling head thus being in the second deployed position P2 thereof.

(64) The coupling head 8 is uncoupled by manual action on the folding elements 83, which are passed into the folded position P6 thereof, then by the return of the coupling head to the first retracted position P1.

(65) The upper backup roll 5, the said support equipment 13, then the lower backup roll 6 can thus be withdrawn from the extraction area, from above, using a handling chassis M.sub.A, shown in FIG. 1, lifted by a travelling crane.

(66) Other embodiments could clearly have been considered by one of ordinary skill in the art without exiting the scope of the invention as defined by the claims hereinbelow.

NOMENCLATURE

(67) 1. Rolling mill installation,

(68) 2. Roll stand,

(69) 3, 4. Work rolls, respectively one upper and one lower,

(70) 5, 6. Backup rolls, respectively one upper and one lower,

(71) 30, 40. Work roll chocks, respectively one upper and one lower,

(72) 42. Hook at the end, on the drive side, of the lower work roll,

(73) 50, 60. Backup roll chocks, respectively one upper and one lower,

(74) 31, 41, 51, 61. Chock sliding plates,

(75) 62. Protruding portions on the top surface of the chock 60 of the backup roll (on the drive side),

(76) 63. Rollers (chocks 60),

(77) 25, 26, 27. Sliding plates (frame),

(78) 7. Extraction system,

(79) 70. Actuator (extraction system)

(80) 71, 72. Motorised rack and pinion (extraction system actuator),

(81) 8. Coupling head (extraction system),

(82) 81. First coupling means (hook rigidly secured to the body of the coupling head) suitable for exerting a pushing force and a pulling force (only) on the lower work roll 4,

(83) 82, 83. Second coupling means, including the manually retracting, movable element 82, suitable for exerting a pushing force on the chock 60 of the lower backup roll, and the manually folding elements 83 suitable for exerting a pulling force (only) on the said chock,

(84) 84. Prong,

(85) 85. Yoke,

(86) 86. Stop,

(87) 9. Clamping system for clamping the backup rolls,

(88) 90. Locking member (clamping system 9),

(89) 91. Handle (clamping system),

(90) 10. Drive means (for driving the backup rolls),

(91) 11. Connection means, on the operator side, between the chocks 30, 40 of the work rolls,

(92) 12. Mechanical connection,

(93) 13. Support equipment,

(94) 14. Clearance of the support equipment through which the metal strip is intended to pass,

(95) 15. Tabs,

(96) 16. Distal ends (tabs),

(97) 17. Oblong aperture,

(98) 18. Stud,

(99) 20. Support car (work rolls),

(100) B. Metal strip,

(101) E1. First extraction step (for extracting the lower and upper work rolls 34),

(102) E2. Return step (coupling head),

(103) E3. Second extraction step (for extracting the lower backup roll 6),

(104) E4. Positioning step for positioning the support equipment 13 on the chocks of the lower backup roll thus extracted from the roll stand,

(105) E5. Joint insertion step for inserting the lower backup roll 6 and the support equipment 13 into the roll stand,

(106) E6. Step of depositing the upper backup roll 5 onto the support equipment 13,

(107) E7. Third extraction step for extracting the assembly constituted from the lower backup roll 6, the said support equipment 13 and the upper backup roll 5,

(108) P1, P2. Retracted position (on the drive side) and deployed position (on the operator side) respectively of the coupling head,

(109) P3, P4. Retracted and deployed positions respectively of the said at least one movable element 82, the said deployed position being suitable for exerting a pushing action on the chock of the said backup roll, on the drive side,

(110) R3, R4, R6. Support rails of the roll stand suitable for guiding the upper work rolls, lower work roll and lower backup roll respectively,

(111) R3′, R4′. Support rails of the support car 20,

(112) Vc3, Vc4. Bending cylinders,

(113) V.sub.R. Pass line adjustment cylinder,

(114) V.sub.S. Hydraulic cylinders (means for applying a clamping force between the chocks of the backup rolls),

(115) M.sub.A. Handling chassis (backup rolls),

(116) M.sub.T. Handling chassis (work rolls).