Rolling mill for rod-shaped bodies

Abstract

A rolling mill for rolling rod-shaped bodies, defining a rolling axis, and comprising a rolling mill assembly having at least two rolling stands (1, 2), each rolling stand (1, 2) including three work rolls (3, 3') arranged at 120° to each other to define a passage (5) for the rod-shaped body; wherein the rolling mill is provided with a frame (4) for receiving the rolling stands (1, 2) along the rolling axis, the frame (4) being designed such that odd-numbered rolling stands (1) can be specifically inserted into the frame (4) in a direction transverse to the rolling axis and specifically withdrawn from the frame (4) from a first side of the rolling mill, while even-numbered rolling stands (2) can be specifically inserted into the frame (4) and specifically withdrawn from the frame (4) from a second side of the rolling mill in a direction transverse to the rolling axis.

Description

Technical Field

[0001] This invention belongs to the technical field of producing rod-shaped products by rolling, such as rods, bars, or similar products, but also including hollow tubular products, and therefore especially tubes. In particular, the invention relates to a rolling mill for producing the above-mentioned products, and to a method for changing at least one rolling stand in the rolling mill. Background Technology

[0002] Various types of rolling mills are known. These include, for example, sizing mills, tension reducing mills, and extraction sizing mills.

[0003] In some rolling mills, rolling can be performed via a rolling stand with three electrically driven rolls, each roll rotating about a pivot axis and tilted 120° relative to the others. Traditionally, one roll has a horizontal pivot axis driven by a horizontal axis adapter. The other two rolls are driven by corresponding adapters, one of which is operatively mounted below the support surface of the rolling stand.

[0004] There are also known rolling mill stands with three rolls, one of which has a horizontal rotating shaft driven by a horizontal shaft adapter, while the other two rolls are driven by internal bevel gears that connect the horizontal rotating shaft of the first roll to each of the two inclined rotating shafts of the other two rolls.

[0005] For this type of rolling mill stand, each pair of successive and adjacent stands includes an "even-number" stand and an "odd-number" stand, wherein when rotated 180° about a horizontal axis passing through the center of rolling, the roll arrangement of the odd-number stand corresponds to the roll arrangement of the even-number stand.

[0006] The downside is that the structure of the traditionally used three-roll stands has shown that changing stands is particularly complex. In fact, using horizontal shaft rolls driven by horizontal adapters makes it difficult to change stands off the rolling line. Furthermore, with individually controlled rolls, the arrangement of other rolls and associated actuation adapters requires complex support structures and an equally complex foundation system located below the support surface of the stand to accommodate the motorization of one of the adapters.

[0007] To simplify stand changes, the rolling mill is designed with a stand featuring three electrically driven rolls, each rotating about a rotation axis and tilted 120° relative to the others. The first roll has a vertical rotation axis driven by a vertical axis adapter located above the stand. The second roll is operatively positioned above a horizontal reference plane containing the rolling axis, while the third roll is operatively positioned below the horizontal reference plane. Adapters for the second and third rolls are operatively mounted below the support surface of the rolling mill stand.

[0008] For this type of rolling mill stand, each pair of subsequent and adjacent stands includes an "even-number" stand and an "odd-number" stand, wherein when rotated 180° about a vertical axis passing through the center of rolling, the roll arrangement of the odd-number stand corresponds to the roll arrangement of the even-number stand.

[0009] However, even the last type of rolling mill stand has some disadvantages related to stand replacement.

[0010] The first drawback is that all rolling stands can only be inserted into and removed from the rolling mill from one side of the mill itself, in a direction transverse to the rolling axis. This means that, for half of the rolling stands, the removal occurs on the side opposite to the corresponding vertical axis adapter, resulting in a rather long release stroke relative to the vertically inclined adapter. In particular, the adapter on the removal side of the stand requires a universal joint to ensure the rotational range required to reach the non-interfering position.

[0011] The second drawback is that, because the insertion and removal of the rolling mill stands are performed only from the same side, a longitudinal platform for stand replacement is required. This platform is located laterally outside and parallel to the mill, and its length is at least twice the length of the mill unit. This is because the first part of the platform (containing the housing or station for supporting the new rolling mill stand to be inserted) longitudinally follows the second empty part (containing the housing or station for accommodating the corresponding rolling mill stand to be replaced). Therefore, the large stand replacement area requires significant engineering work and results in high investment and operating costs for the production line.

[0012] The third drawback is that, although some known rolling mills have overcome the stand locking problem through axial compression (along the rolling axis), they require excessive time for product changes because the stands cannot be unlocked and / or replaced individually, and this is a constant need even when rolling requires a limited number of stands.

[0013] Filling the entire rolling mill may also require transporting the stands. In alternative solutions that allow for individual stand replacement, there is a risk that once the axial locking has been released, the removal of a single rolling mill stand could cause friction with adjacent, preceding, and / or following stands, resulting in their displacement.

[0014] The fourth drawback is that the known solution for lateral locking of the rolling stands inside the rolling mill, i.e., locking along the direction perpendicular to the rolling axis, cannot ensure that the rolling position is always repeated and is not affected by wear of the slides or wheels used to pull out and insert the stands during the changeover process.

[0015] Based on the above considerations, it is necessary to create an innovative rolling mill to overcome the aforementioned shortcomings. Summary of the Invention

[0016] The main objective of this invention is to provide a rolling mill with a three-roll stand, which has a work roll with a vertical axis of rotation, minimizing the release stroke of the adapter and limiting the downward rotation of the adapter on the exit side of the stand to a few degrees, thus allowing the use of the adapter even without a universal joint.

[0017] Another object of the present invention is to provide a rolling mill with a very compact stand change area, which is substantially the same size as the rolling mill unit, thus requiring less engineering work and resulting in lower investment and operating costs for the production line.

[0018] Another object of the present invention is to provide a rolling mill in which, once the axial locking of the rolling mill stand has been released, the withdrawal of a single rolling mill stand does not cause friction with adjacent, front and / or rear stands, and thus does not cause displacement of the latter.

[0019] Another object of the present invention is to provide a rolling mill having a more efficient side-locking system for the rolling stand, which ensures that the rolling position is always repeated and is not affected by wear on the slides or wheels used to pull out and insert the stand during the changeover process.

[0020] Another object of the present invention is to provide a more efficient method for changing rolling mill stands.

[0021] The present invention achieves at least one of these objectives, as well as other objectives that will become apparent from this specification, by means of a rolling mill for rolling rod-shaped bodies, the rolling mill defining a rolling axis and comprising a rolling mill assembly having at least two rolling stands, each rolling stand comprising three work rolls arranged at 120° to each other, thereby defining a passage for said rod-shaped body;

[0022] The rolling mill stands are arranged sequentially along the rolling axis, such that the corresponding channels are aligned to define the rolling path along the rolling axis.

[0023] In each of the rolling mill stands, the rotation axes X and X' of the work rolls are vertical.

[0024] The rolling mill stands are arranged adjacent to each other along the rolling axis, and the positions of the work rolls in the odd-numbered rolling mill stands correspond to the work rolls in the adjacent even-numbered rolling mill stands that have rotated 180° around a vertical axis passing through the center of the channel.

[0025] The odd-numbered rolling mill stands have work rolls located on the first side of the rolling mill, and the work rolls have a vertical rotation axis X, which is parallel to the rolling axis. Meanwhile, the even-numbered rolling mill stands have work rolls located on the second side of the rolling mill, and the work rolls have a vertical rotation axis X', which is parallel to the rolling axis. The second side is opposite to the first side.

[0026] The rolling mill is provided with a frame for accommodating rolling stands along the rolling axis. The frame is designed such that odd-numbered rolling stands can be specifically inserted into the frame in a direction transverse to the rolling axis and withdrawn from the frame from the first side of the rolling mill, while even-numbered rolling stands can be specifically inserted into the frame and withdrawn from the frame from the second side of the rolling mill in a direction transverse to the rolling axis.

[0027] Another aspect of the invention relates to a method for replacing at least one rolling stand in the aforementioned rolling mill, wherein an odd-numbered rolling stand 1 is inserted into a frame and withdrawn from the frame only from the first side of the rolling mill, the odd-numbered rolling stand 1 having a work roll having a vertical rotation axis X parallel to the rolling axis located on the first side of the rolling mill; while an even-numbered rolling stand 2 is inserted into the frame and withdrawn from the frame only from the second side of the rolling mill (opposite to the first side), the even-numbered rolling stand 2 having a work roll located on the second side of the rolling mill, the work roll having a vertical rotation axis X' parallel to the rolling axis.

[0028] Further features and advantages of the invention will become more apparent from the detailed description of exemplary, but not exclusive, embodiments.

[0029] The dependent claims describe specific embodiments of the invention. Attached Figure Description

[0030] In the description of this invention, reference is made to accompanying drawings, which are provided in an interpretive rather than limiting manner, wherein:

[0031] Figure 1 A perspective view of a rolling mill according to the present invention is shown;

[0032] Figure 2 It shows Figure 1 A partial cross-sectional side view of the rolling mill;

[0033] Figure 3 A top view is shown of a schematic diagram for extracting a rolling mill stand in a first variant of the rolling mill according to the invention;

[0034] Figure 3aA top view of the rolling mill stand in a second variant of the rolling mill according to the invention is shown;

[0035] Figure 4 It shows Figure 1 A partial cross-sectional side view of the first variant of the rolling stand inside the rolling mill;

[0036] Figure 5 It shows Figure 4 Enlarged view at the bottom;

[0037] Figure 6 It shows Figure 4 Enlarged view at the top;

[0038] Figure 7 It shows Figure 1 A partial cross-sectional side view of the second variant of the rolling stand inside the rolling mill;

[0039] Figure 8 A partially enlarged view of another variation of the rolling mill stand is shown;

[0040] Figure 9 A side view of a portion of a system for translating a rolling mill stand transversely to the rolling axis is shown;

[0041] Figure 10 A partial top view of the rolling mill according to the present invention is shown;

[0042] Figure 11 and 12 The following are side views of the rolling mill stand compartments, one showing the adapter in the extended position, i.e., connected to the corresponding roll, and the other showing the adapter in the retracted position to allow the rolling mill stand to be withdrawn.

[0043] The same reference numerals in the figure indicate the same elements or parts. Detailed Implementation

[0044] Referring to the accompanying drawings, some examples of rolling mills for rod-shaped bodies are shown, such as rods, bars, or similar products, but also including hollow tubular products, and thus especially tubes. The rolling mill of the present invention is a rolling mill having at least two rolling stands.

[0045] For illustrative purposes only, the rolling mill according to the present invention can be a sizing mill, a tension reducing mill, or an extraction sizing mill.

[0046] In all embodiments of the invention, the rolling mill defines the rolling axis and includes a rolling mill assembly with at least two rolling stands 1, 2, each rolling stand 1, 2 including three work rolls 3, 3' arranged at 120° to each other, thereby defining a channel 5 for the rod-shaped body. Figure 4 ).

[0047] Each rolling mill stand 1, 2 has a work roll 3' with vertical rotation axes X, X', while the rotation axes of the other two work rolls 3 are inclined at +30° and -30° respectively relative to the horizontal reference perpendicular to the vertical axis passing through the center of the channel 5.

[0048] Rolling stands 1 and 2 are types capable of withstanding the separation forces they bear, i.e., the forces generated by rolling, without the need for external actuators such as hydraulic bladders or pressing devices. Therefore, they are rolling stands without roll frames.

[0049] Rolling stands 1 and 2 are arranged sequentially along the rolling axis, such that the corresponding channels 5 are aligned to define the rolling path along the rolling axis.

[0050] Specifically, rolling mill stands 1 and 2 are arranged adjacent to each other along the rolling axis, and the positions of the work rolls 3 and 3' of the odd-numbered rolling mill stands 1 correspond to the work rolls 3 and 3' of the adjacent even-numbered rolling mill stands 2, which are rotated 180° around the vertical axis V passing through the center of the channel 5.

[0051] Therefore, the odd-numbered rolling mill stand 1 of the rolling mill 1 and 2 has a work roll 3' with a vertical rotation axis X on the first side of the rolling mill, which is parallel to the rolling axis, while the even-numbered rolling mill stand 2 of the rolling mill 1 and 2 has a work roll 3' with a vertical rotation axis X' on the second side of the rolling mill, which is parallel to the rolling axis and opposite to the first side.

[0052] Advantageously, the rolling mill is provided with a frame 4, preferably a single frame, to accommodate rolling stands 1 and 2 along the rolling axis. This frame is designed such that odd-numbered rolling stands 1 can be specifically inserted into frame 4 in a direction transverse to the rolling axis and withdrawn from frame 4 only from the first side of the rolling mill, while even-numbered rolling stands 2 can be inserted into frame 4 and withdrawn from frame 4 specifically in a direction transverse to the rolling axis from the second side of the rolling mill. In a preferred variant, these transverse directions coincide.

[0053] In stand 4, odd-numbered compartments are provided for odd-numbered rolling stands 1 and even-numbered compartments are provided for even-numbered rolling stands 2.

[0054] For all racks, the above-described construction of the frame and rolling mill rack allows for minimizing the release stroke of adapters 34, 35, and 36 and restricts the downward rotation of adapter 36 on the rack exit side to a few degrees, thereby ensuring that the adapter can be used even without a universal joint. Figure 11 and 12The diagram shows a frame compartment without a stand, with adapters 34, 35, and 36 in the extended position, i.e., connected to the corresponding work rolls, and adapters 34, 35, and 36 in the retracted position, allowing the rolling mill stand to be withdrawn.

[0055] Preferably, for example Figure 3 As schematically shown, along the first side of the rolling mill, the frame 4 includes a first side opening 6 for inserting and withdrawing odd-numbered rolling mill stands 1, the first side opening 6 being alternately arranged with a first vertical post 7, the first vertical post 7 laterally enclosing the compartments of the corresponding even-numbered rolling mill stands 2.

[0056] Similarly, along the second side of the rolling mill, the frame 4 includes a second side opening 8 for inserting and withdrawing even-numbered rolling mill stands 2, the second side opening 8 being alternately arranged with second vertical columns 9, the second vertical columns 9 laterally closing the compartments of the corresponding odd-numbered rolling mill stands 1.

[0057] Therefore, each first side opening 6 on the first side corresponds to a second vertical post 9 on the second side, and each second side opening 8 on the second side corresponds to a first vertical post 7 on the first side.

[0058] In one variant, frame 4 is unique to the entire rolling mill and also includes an upper beam system 10 and a lower beam system 11, which are arranged parallel to each other, perpendicular to the first vertical column 7 and the second vertical column 9, and connect the upper and lower parts of the first vertical column 7 to the second vertical column 9.

[0059] In other words, the frame 4 for accommodating the rolling mill stand includes a first vertical column 7 and a second column 99 arranged alternately between one stand and another along the rolling axis, and an upper longitudinal beam 10 and a lower longitudinal beam 11 connecting the columns 97 and 9 together, such that the inlet / outlet slots of the stand are open on both sides, and the slots are also arranged alternately along the rolling axis. This type of structure is also lightened by the holes for adapter passage, and does not bear high bending loads, for example, in a conventional rolling mill with one horizontal adapter and two other adapters tilted at +30° and -30° relative to the horizontal reference, respectively, because there are no protruding or suspended parts.

[0060] The frame 4 also includes a first end wall 42 and a second end wall 43. The first end wall 42 is transverse to (e.g., orthogonal to) the rolling axis and is configured for the entry of the object or product to be rolled. The second end wall 43 is opposite to, for example, parallel to, the first end wall 42 and is configured for the exit of the rolled object or product. The two end walls may be arranged perpendicular to the rolling axis, the upper beam system 10, and the lower beam system 11.

[0061] The upper beam 10 and the lower beam 11 are arranged longitudinally, parallel to each other and parallel to the rolling axis, and connect the upper and lower parts of the first end wall 42 to the second end wall 43, and also connect the first vertical column 7 to the second vertical column 9.

[0062] In another variant, not shown, frame 4 is unique for the entire rolling mill, but it does not have vertical columns 7, 9 alternately arranged between one stand and another along the rolling axis.

[0063] In this configuration, the frame 4 for accommodating the rolling mill stands includes: a first end wall 42, which is transverse (e.g., orthogonal to) the rolling axis and configured to allow the object to be rolled to enter; a second end wall 43, which is opposite to the first end wall 42, for example, parallel to it, and configured to allow the rolled object to exit; an upper beam system 10 and a lower beam system 11, parallel to the rolling axis and connecting the upper and lower sides of the first end wall 42 to the second end wall 43; a single first side opening on the first side of the rolling mill, located between the first end wall 42 and the second end wall 43, for inserting and withdrawing odd-numbered rolling mill stands 1 transverse to the rolling axis; and a single second side opening on the second side of the rolling mill, located between the first end wall 42 and the second end wall 43, for inserting and withdrawing even-numbered rolling mill stands 2 transverse to the rolling axis.

[0064] In a preferred embodiment of the rolling mill of the present invention ( Figure 1-3a To replace one or more rolling mill stands, the following features are provided:

[0065] - A first side platform 12 located on the first side of the rolling mill, which is laterally arranged outside and parallel to the frame 4, is adapted to accommodate at least one odd-numbered rolling mill stand 1 withdrawn from the frame 4 and to support at least one new odd-numbered rolling mill stand 1' to be inserted into the frame 4.

[0066] - A second side platform 13 located on the second side of the rolling mill, which is laterally arranged outside and parallel to the frame 4, is adapted to accommodate at least one even-numbered rolling mill stand 2 withdrawn from the frame 4 and to support at least one new even-numbered rolling mill stand 2' to be inserted into the frame 4.

[0067] exist Figure 3 In the first variant schematically shown, the first side platform 12 can slide parallel to the rolling axis and is provided with a first empty shell 14, which is configured to accommodate the corresponding odd-numbered rolling mill stand 1 of the rolling mill unit to be replaced, and is alternately arranged with a second shell 15 along the rolling direction, which supports the new odd-numbered rolling mill stand 1′ to be inserted into the frame 4.

[0068] Each first housing 14 is adjacent to a second housing 15, thereby the first side platform 12 is configured to move from a withdrawn position to an inserted position. In the withdrawn position, the first empty housing 14 is located at the corresponding odd-numbered rolling mill stand 1 to be replaced. In the inserted position, the second housing 15 supporting the new odd-numbered rolling mill stand 1' is located at the corresponding odd-numbered compartment of the rolling mill unit, which is empty due to the corresponding odd-numbered rolling mill stand 1 that has just been withdrawn.

[0069] Similarly, the second side platform 13 can slide parallel to the rolling axis and is provided with a third housing 16, which is configured to accommodate the corresponding even-numbered rolling mill stand 2 of the rolling mill unit to be replaced, and is arranged alternately with the fourth housing 17 along the rolling direction to support the new even-numbered rolling mill stand 2′ to be inserted into the frame 4.

[0070] Each third housing 16 is adjacent to a fourth housing 17, thereby the second side platform 13 is configured to move from a withdrawn position to an inserted position. In the withdrawn position, the empty third housing 16 is located at the corresponding even-numbered rolling mill stand 2 to be replaced. In the inserted position, the fourth housing 17 supporting the new even-numbered rolling mill stand 2' is located at the corresponding even-numbered compartment of the rolling mill unit, which is vacated by the corresponding even-numbered rolling mill stand 2 that has just been withdrawn.

[0071] Advantageously, to move from the withdrawn position to the insert position, or vice versa, each side platform 12, 13 requires only a single stand sliding step, i.e., sliding the distance between the centerline planes of two adjacent rolling stands located inside frame 4, which are transverse to the rolling axis. This allows for the creation of a very compact stand changeover area, essentially the same size as the rolling mill unit, thus requiring less engineering work and lower production line investment and operating costs.

[0072] Specifically, the first side platform 12 has multiple housings or workstations 14 and 15 for odd-numbered rolling mill stands 1 and 1', the number of which is equal to the total number of rolling mill stands 1 and 2 in the entire rolling mill unit; while the second side platform 13 has multiple housings or workstations 16 and 17 for even-numbered rolling mill stands 2 and 2', the number of which is equal to the total number of rolling mill stands 1 and 2 in the rolling mill unit.

[0073] When it is necessary to replace one or more odd-numbered rolling mill stands 1 of a rolling mill unit, one or more new spare odd-numbered rolling mill stands 1' are arranged on the first side platform 12 such that when each first station 14 is laterally arranged on the corresponding odd-numbered rolling mill stand 1 of the unit, the one or more new odd-numbered rolling mill stands 1' are located in the second station 15 of the corresponding even-numbered rolling mill stand 2 adjacent to the odd-numbered rolling mill stand 1 to be replaced, and the first station 14 remains vacant at the corresponding odd-numbered rolling mill stand 1 to be replaced.

[0074] Similarly, when it is necessary to replace one or more even-numbered rolling mill stands 2 of the rolling mill unit, one or more new spare even-numbered rolling mill stands 2' are arranged on the second side platform 13 such that when each third station 16 is laterally arranged on the corresponding even-numbered rolling mill stand 2 of the unit, the one or more new even-numbered rolling mill stands 2' are located in the fourth station 17 of the corresponding odd-numbered rolling mill stand 1 adjacent to the even-numbered rolling mill stand 2 to be replaced, and the third station 16 remains vacant at the corresponding even-numbered rolling mill stand 2 to be replaced.

[0075] The first workstation 14 and the third workstation 16 are located on two side platforms 12 and 13. Figure 3 The available space on the crane also allows for convenient removal and placement of supports on the relevant platform via a straddle crane, while also protecting operator safety. Depending on the crane's capacity and required productivity, lifting equipment can be provided to lift supports individually or in groups.

[0076] exist Figure 3a In the second variant schematically shown, the first side platform 12 is fixed and provided with a first housing 18, each first housing 18 being placed at a corresponding odd-numbered rolling mill stand 1 of the rolling mill unit and adapted to accommodate the odd-numbered rolling mill stand 1 once it is pulled out from the frame 4, and to receive a corresponding new odd-numbered rolling mill stand 1' to be inserted into the frame 4 once the pulled-out odd-numbered rolling mill stand 1 has been removed from the first housing 18.

[0077] Similarly, the second side platform 13 is fixed and provided with a second housing 19, each second housing 19 being placed at the corresponding even-numbered rolling mill stand 2 of the rolling mill unit and adapted to accommodate the even-numbered rolling mill stand 2 once it is pulled out from the frame 4, and to receive the corresponding new even-numbered rolling mill stand 2' to be inserted into the frame 4 once the pulled-out even-numbered rolling mill stand 2 has been removed from the second housing 19.

[0078] Preferably, at least one crane, such as a straddle crane, is provided for use.

[0079] - Remove the odd-numbered rolling mill stand 1 from the first housing 18, the odd-numbered rolling mill stand 1 having previously been removed from the corresponding odd-numbered compartment of the rolling mill, and position the new odd-numbered rolling mill stand 1' in the first housing 18.

[0080] - Remove even-numbered rolling mill stands 2 from the second housing 19, which have previously been removed from the corresponding even-numbered compartments of the rolling mill, and position new even-numbered rolling mill stands 2' in the second housing 18.

[0081] In order to extract and insert the rolling mill stand in the frame 4 of the rolling mill of the present invention, the following device may be provided, for example:

[0082] - The first actuator 20 is located in the odd-numbered compartments of frame 4, and thus, when the vertical column 7 is installed, it is located at the first side opening 6 for inserting and withdrawing the odd-numbered rolling mill stand, and

[0083] - The second actuator 21 is located in the even-numbered compartment of the frame 4, and thus, when the vertical column 9 is installed, it is located at the second side opening 8 for inserting and withdrawing the even-numbered rolling mill stand.

[0084] These actuators 20, 21 can be, for example, hydraulic actuators or electromechanical actuators.

[0085] The first actuator 20 and the second actuator 21 are preferably configured to individually or in groups hook the respective rolling mill stands 1, 2 to be withdrawn from the frame 4 and move them toward the relevant side platforms 12, 13, and are configured to subsequently individually or in groups hook the new rolling mill stands 1', 2' to be inserted into the frame 4 and move them from the relevant side platforms 12, 13 toward the frame 4.

[0086] More specifically, considering the aforementioned first variation in the stand replacement sequence, one or more stands 1, 2 to be replaced are hooked and automatically pulled out of the rolling mill by actuators 20, 21 associated with the stand itself, and positioned on the corresponding side platform 12, 13 in one of the corresponding empty stations 14, 16. Once extraction is complete, the side platform translates a single stand step to position one or more new stands 1', 2' at stations 15, 17 at the corresponding empty rolling compartment to be loaded. Actuators 20, 21 hook and automatically push the new stand into the corresponding frame compartment.

[0087] Conversely, considering the aforementioned second variation in the stand replacement sequence, one or more stands 1, 2 to be replaced are hooked and automatically pulled out of the rolling mill by actuators 20, 21 associated with the stand itself, and positioned on the corresponding side platform 12, 13 in one of the corresponding empty stations 18, 19. Once the extraction is complete, the extracted one or more stands are removed from stations 18, 19, and one or more new stands 1', 2' are repositioned on the corresponding stations 18, 19, and actuators 20, 21 hook and automatically push the new stands into the corresponding frame compartment.

[0088] As examples of actuators 20 and 21 used to pull out and insert the rolling mill stand into frame 4, Figure 9 A bracket 37 is shown, which is adapted to translate from a first position to a second position in a direction transverse to the rolling axis. The first position is distal to the frame 4 and located outside the associated platforms 12, 13 (with the rolling axis as a reference). The second position is proximal to the side openings 6, 8 of the corresponding compartments of the frame 4.

[0089] In its variant, the bracket 37 is provided with a hook 38 configured to hook onto a protrusion 39 located on the vertical side of each rolling mill stand, the protrusion 39 being close to the work roll 3′ having a vertical axis of rotation.

[0090] The tracks, rails, or guides along which the rolling mill stand and associated bracket 37 slide are not described here, as they are known types.

[0091] In the rolling mill of the present invention, a side locking device for the rolling mill stand can be provided in the frame 4, that is, a device for locking the rolling mill stand transversely to the rolling axis.

[0092] Preferably, each compartment of the frame 4 is provided with at least one central support 22, which is adapted to define the end of the stroke for the corresponding rolling mill stand during the insertion of the frame 4.

[0093] The at least one central abutment 22 is positioned along a vertical plane close to the rolling axis, preferably at a distance from the rolling axis that is shorter than the distance between the vertical plane containing the rolling axis and the vertical plane containing the vertical rotation axes X, X' of one of the work rolls.

[0094] exist Figure 4-7 In the example, only one central abutment block 22 can be seen on both the upper and lower inner surfaces of the frame compartment.

[0095] It is not excluded that two or more center blocks 22 may be set on the upper inner surface and the lower inner surface of the compartment.

[0096] For example, the structure of each rolling mill stand has a shoulder 41 at the top. Figure 6 The recess 40 is defined to allow the frame to advance within the compartment until the shoulder 41 abuts against the central abutment 22.

[0097] In a first variation of the side locking device, in order to achieve the side locking of the bracket, each compartment of the frame 4 is further provided with ( Figure 4-6 ):

[0098] - At least one lifting and locking actuator 23 is arranged on the lower inner surface of the compartment for lifting the corresponding rolling stand after the at least one center stop 22 has been reached;

[0099] - and at least one upper abutment block 24, which is arranged on the upper surface of the compartment and adapted to define the end of the lifting stroke of the rolling mill stand.

[0100] Therefore, the rolling mill stand is raised and abutted against the at least one upper abutment block 24, so that the rolling position is always repeated and is not affected by wear of the rails, wheels or slides used to pull out and insert the stand during the changeover process.

[0101] For example, two lifting and locking actuators 23 and two upper abutment blocks 24 can be provided, which are arranged on both sides relative to the vertical plane containing the rolling axis. Figure 4 Optionally, four lifting and locking actuators 23 and four upper abutment blocks 24 may be provided.

[0102] As an explanation, these lifting and locking actuators 23, such as hydraulic cylinders, can be operated by valves for each rolling stand in order to ensure better synchronous control.

[0103] Preferably, the at least one lifting and locking actuator 23 is a cylinder, such as a hydraulic cylinder, which has a rod with a wedge-shaped end 31.

[0104] Each rolling mill stand is further provided with at least one recess 32 at its base, the shape of which complements the wedge-shaped end 31 of the corresponding rod. The wedge-shaped end 31 of the rod and the corresponding recess 32 are shaped such that the reception of the wedge-shaped end 31 in the recess 32, in addition to lifting, also produces a lateral translation of the rolling mill stand to keep it abutting against at least one central abutment 22. For this purpose, an appropriate gap exists between the width of the wedge-shaped end 31 and the width of the recess 32.

[0105] In a second variation of the side locking device, in order to achieve the side locking of the bracket, each compartment of the frame 4 is further provided with ( Figure 4-8 ):

[0106] At least one first locking actuator 25, such as a hydraulic cylinder, is arranged on the upper surface of the compartment, preferably at a corner of the compartment, and is inclined at an angle of less than 90° and greater than 0° relative to the horizontal plane, such as 45°, to push the corresponding rolling mill stand downward after reaching at least one center stop 22, keeping it in contact with the at least one center stop 22.

[0107] And preferably at least one second locking actuator 26, such as a hydraulic cylinder, is arranged on the closed side surface of the compartment, i.e., the vertical columns 7, 9, and adapted to act as a traction force on the rolling mill stand in the direction of the rolling mill stand insertion frame 4 to keep it in further contact with the at least one central abutment block 22.

[0108] As an explanation, the at least one second locking actuator 26 includes a piston or jack 27 translatable in two opposing translational directions along a direction perpendicular to the rolling axis, and the rolling mill stand includes a seat 28 in which the piston or jack 27 is adapted to engage to pull the rolling mill stand against the at least one central abutment 22. The seat 28 is disposed on the vertical side of each rolling mill stand, which is away from its work roll 3' to the vertical axis of rotation.

[0109] Therefore, in this second variant, the lateral locking of the support occurs without lifting the support by the vertical or tilting thrust applied by the first locking actuator 25, thereby generating a force with at least a downward lateral component, which applies a locking action against the central abutment 22.

[0110] One or two second locking actuators 26, such as one or two cylinders with hammers, can also be provided, which also rotate to engage the bracket in the seat 28 and pull it against the central abutment 22.

[0111] Furthermore, in the rolling mill of the present invention, an axial locking device for locking the rolling mill stand inside the frame 4 can be provided, that is, a device for locking the rolling mill stand along the rolling axis.

[0112] Preferably, such as Figure 10 As shown, at least two thrust actuators 29 are disposed in the frame 4, located on the exit side where the rolled body leaves the rolling mill, i.e., on the second end wall 43. These thrust actuators are adapted to push the rolling mill frames one after another in a direction preferably opposite to the rolling direction (indicated by arrow A) to lock the frame 4 against at least two fixed blocks 33 along the rolling axis. These blocks 33 are disposed on the inlet side of the object to be rolled in the rolling mill, i.e., on the first end wall 42. Specifically, three thrust actuators 29 may be provided, adapted to push the rolling mill frames one onto another, preferably in a direction opposite to the rolling direction, to lock the rolling mill frames in the frame 4 along the rolling axis against three corresponding fixed blocks 33. However, the use of a single fixed block 33 is not excluded.

[0113] Furthermore, in a preferred variant, the elastic device 30 is disposed in the frame 4, arranged between the odd-numbered and even-numbered compartments of the frame 4, and adapted to transmit the thrust generated by the thrust actuator 29 by transferring the thrust from one rolling mill stand to the next rolling mill stand until the entire rolling mill unit is locked against the fixed stop 33.

[0114] This elastic device 30 is designed so that once the thrust actuator 29 fails, the rolling mill stand returns to its initial insertion position in the frame 4, so that no friction is generated between adjacent rolling mill stands 1, 2 during the step of withdrawing the rolling mill stand from the frame 4.

[0115] In particular, the elastic device 30 may include ( Figure 10-12 Systems of resilient plates or abutments, for example, some cantilevered to the upper inner surface of the frame, while others cantilevered to the lower inner surface of the frame. Figure 11 and 12As shown, for example, a group of elastic plates or elastic sheets 30 are arranged transversely to the rolling axis, and especially when they are in a stationary configuration, they are arranged on a vertical plane perpendicular to the vertical plane containing the rolling axis.

[0116] Thrust actuator 29, such as a hydraulic cylinder, stacks the rolling stands 1, 2 from the exit side of the rolling mill toward the inlet side. Each stand pushes the next stand through a system of elastic plates or sheets, and once the axial lock is released, the elastic plates or sheets allow individual stands to be withdrawn without friction, thus preventing displacement of the previous or next stand.

[0117] In all embodiments of the rolling mill of the present invention, for each rolling stand, a motor 44, 45, 46 and an associated drive shaft or adapter 34, 35, 36 are provided for each work roll. Figure 2 Alternatively, a single motor and associated single drive shaft can be provided for the work rolls with vertical rotation axes X and X', while the other two work rolls are driven by gears within the rolling mill stand (solution not shown).

[0118] like Figure 2 As shown, the independent drive structure with an upper vertical adapter 34 and tilt adapters 35, 36 on both sides at a 30° angle relative to the horizontal direction has the advantages of simplified maintenance and controller accessibility, and significantly reduces the exposure of the lower motors 45, 46 to cooling water.

[0119] The single-drive configuration with only the upper vertical adapter significantly reduces installation space, engineering work, and investment and operating costs for the production line.

[0120] Generally, for small and medium-sized rolling mills, the motor can be directly mounted on the gearbox using a flange; in other cases, the motor can be foot-mounted.

[0121] In all embodiments of the rolling mill of the present invention, the rolling mill stands 1, 2 are configured such that the position of the rotation axis of the work rolls 3, 3' can be adjusted a few millimeters in the radial direction (relative to the rolling axis), optionally by means of an eccentric system.

[0122] Preferably, a mechanical actuation device, such as an electric device, for actuating the eccentric system is provided, which is located outside some or each rolling mill stand and, for example, arranged at the top, at the work roll 3' having a vertical axis of rotation.

[0123] Further advantages can be obtained by providing the mechanically actuated device that can be operated remotely, so that the position of the rotation axis of the work roll in the radial direction can be controlled even if the rolling mill stand is inside the frame 4 and not just in the workshop.

[0124] The following describes a method for replacing at least one rolling stand 1, 2 in a rolling mill according to the present invention.

[0125] Advantageously, the odd-numbered rolling mill stand 1 is inserted into the frame 4 and withdrawn from the frame 4 only from the first side of the rolling mill. The odd-numbered rolling mill stand 1 has a work roll 3' with a vertical rotation axis X parallel to the rolling axis located on the first side of the rolling mill. The even-numbered rolling mill stand 2 is inserted into the frame 4 and withdrawn from the frame 4 only from the second side of the rolling mill (opposite to the first side). The even-numbered rolling mill stand 2 has a work roll 3' located on the second side of the rolling mill with a vertical rotation axis X' parallel to the rolling axis.

[0126] Consider a variation of a rolling mill with side platforms 12 and 13 sliding parallel to the rolling axis. The first side platform 12 slides a single stand step via the following path.

[0127] -From the extraction position ( Figure 3 In this withdrawn position, the first housing 14 is located in the corresponding odd-numbered compartment of the rolling mill, while the second housing 15 is located in the corresponding even-numbered compartment of the rolling mill.

[0128] -To the insertion position, in which the second housing 15 is located in the corresponding odd-numbered compartment, while the first housing 14 is located in the corresponding even-numbered compartment.

[0129] vice versa.

[0130] In the withdrawn position of the first side platform 12, the empty first housing 14 accommodates the corresponding odd-numbered rolling mill stand 1 to be replaced, which is withdrawn from the corresponding odd-numbered compartment. In the insertion position, the new odd-numbered rolling mill stand 1' supported by the second housing 15 is inserted into the corresponding odd-numbered compartment, and the second housing 15 is left empty due to the previous withdrawal of the corresponding odd-numbered rolling mill stand 1.

[0131] Similarly, the second side platform 13 slides one rack step, through the following path

[0132] - From the withdrawn position, in which the third housing 16 is located in the corresponding even-numbered compartment, and the fourth housing 17 is located in the corresponding odd-numbered compartment.

[0133] -To the insertion position, in which the fourth housing 17 is located in the corresponding even-numbered compartment, and the third housing 16 is located in the corresponding odd-numbered compartment.

[0134] In the withdrawn position of the second side platform, the first housing accommodates the even-numbered rolling mill stand to be replaced, which is withdrawn from the corresponding even-numbered compartment. In the insertion position, the new even-numbered rolling mill stand, supported by the fourth housing, is inserted into the corresponding even-numbered compartment, which is empty due to the withdrawal of the previously corresponding even-numbered rolling mill stand.

[0135] More specifically, in order to replace at least one odd-numbered rolling mill stand 1 of a rolling mill unit, the following steps are provided:

[0136] - Provide a first empty housing 14 and at least some second housings 15 for the first side platform 12 in the withdrawn position, the second housings 15 being provided with a new odd number of rolling mill stands 1';

[0137] - Remove the odd-numbered rolling mill stands 1 to be replaced from the corresponding odd-numbered compartments of frame 4 and house them in the corresponding first housing 14;

[0138] - The first side platform 12 slides a single rack step to move from the withdraw position to the insert position;

[0139] The new odd-numbered rolling mill stand 1', which exists in the second housing 15, is inserted into the corresponding odd-numbered compartment.

[0140] Similarly, in order to replace at least one even-numbered rolling mill stand 2 of a rolling mill unit, the following steps are provided:

[0141] - Provide a third empty shell 16 and at least some fourth shells 17 for the second side platform 13 in the withdrawn position, the fourth shells 17 being provided with a new even number of rolling mill stands 2';

[0142] Remove the even-numbered rolling mill stands 2 to be replaced from the corresponding even-numbered compartments of frame 4 and house them in the corresponding third housing 16;

[0143] - The second side platform 13 slides a single rack step to move from the withdraw position to the insert position;

[0144] The new even-numbered rolling mill stand 2', which exists in the fourth housing 17, is inserted into the corresponding even-numbered compartment.

[0145] Conversely, considering variations of rolling mills with fixed side platforms 12, 13, the following steps are provided to replace at least one odd-numbered rolling stand 1 of the rolling mill unit:

[0146] - Remove the odd-numbered rolling mill stands 1 to be replaced from the corresponding odd-numbered compartments and house them in the corresponding first housing 18;

[0147] Preferably, the odd number of rolling mill stands 1 are removed from the respective first housing 18 by a crane;

[0148] - Preferably, the corresponding new odd-numbered rolling mill stands 1' are housed in the corresponding first housing 18 by means of a crane;

[0149] The new odd-numbered rolling mill stand 1' is inserted into the corresponding odd-numbered compartment.

[0150] Similarly, in order to replace at least one even-numbered rolling mill stand 2 of a rolling mill unit, the following steps are provided:

[0151] Remove the even-numbered rolling mill stands 2 to be replaced from the corresponding even-numbered compartments and house them in the corresponding second housing 19;

[0152] The even-numbered rolling mill stands 2 are preferably removed from the corresponding second housing 19 by a crane;

[0153] - Preferably, the corresponding new even-numbered rolling mill stands 2' are housed in the corresponding second housing 19 by means of a crane;

[0154] Insert the new even-numbered rolling mill stand 2' into the corresponding even-numbered compartment.

Claims

1. A rolling mill for rolling rod-shaped bodies, defining a rolling axis, and comprising a rolling mill assembly having at least two rolling stands (1, 2), each rolling stand (1, 2) including three work rolls (3, 3') arranged at 120° to each other, thereby defining a passage (5) for said rod-shaped body; in, The rolling mill stands (1, 2) are arranged sequentially along the rolling axis such that the corresponding channels (5) are aligned to define the rolling path along the rolling axis. In each of the rolling mill stands (1, 2), the rotation axis (X, X') of the work roll (3') is vertical. The rolling mill stands (1, 2) are arranged adjacent to each other along the rolling axis, and the positions of the work rolls (3, 3') of the odd-numbered rolling mill stands (1) correspond to the positions of the work rolls (3, 3') of the adjacent even-numbered rolling mill stands (2) which rotate 180° around the vertical axis (V) passing through the center of the channel (5). Among them, the odd-numbered rolling mill stand (1) of the rolling mill stand (1, 2) has a work roll (3') located on the first side of the rolling mill. The work roll (3') has a vertical rotation axis (X) that is parallel to the rolling axis. Meanwhile, the even-numbered rolling mill stand (2) of the rolling mill stand (1, 2) has a work roll (3') located on the second side of the rolling mill. The work roll (3') has a vertical rotation axis (X') that is parallel to the rolling axis. The second side is opposite to the first side. The rolling mill is provided with a frame (4) for accommodating rolling stands (1, 2) along the rolling axis. The frame (4) is designed such that odd-numbered rolling stands (1) can be specifically inserted into the frame (4) in a direction transverse to the rolling axis and withdrawn from the frame (4) from the first side of the rolling mill, while even-numbered rolling stands (2) can be specifically inserted into the frame (4) and withdrawn from the frame (4) from the second side of the rolling mill in a direction transverse to the rolling axis.

2. The rolling mill according to claim 1, wherein, The frame (4), along the first side, includes a plurality of first openings (6) for inserting and withdrawing the odd-numbered rolling mill stands (1), the plurality of first side openings (6) being alternately arranged with a plurality of first vertical columns (7), the plurality of first vertical columns (7) laterally enclosing the compartments of the corresponding even-numbered rolling mill stands (2). Furthermore, the frame (4), along the second side, includes a plurality of second openings (8) for inserting and withdrawing the even-numbered rolling mill stands (2), the plurality of second side openings (8) being alternately arranged with a plurality of second vertical columns (9), the plurality of second vertical columns (9) laterally enclosing the compartments of the corresponding odd-numbered rolling mill stands (1). Each first side opening (6) on the first side corresponds to one of the plurality of second vertical columns (9) on the second side, and each second side opening (8) on the second side corresponds to one of the plurality of first vertical columns (7) on the first side.

3. The rolling mill according to claim 2, wherein, The frame (4) further includes: a first end wall (42) transverse to the rolling axis, the first end wall (42) being configured to allow the object to be rolled to enter; a second end wall (43), opposite to the first end wall (42), being configured to allow the rolled object to exit; an upper beam system (10) and a lower beam system (11), which are parallel to each other and parallel to the rolling axis, and connect the first end wall (42) to the second end wall (43) above and below and connect the plurality of first vertical columns (7) to the plurality of second vertical columns (9).

4. The rolling mill according to claim 1, wherein, The frame (4) further includes: a first end wall (42) transverse to the rolling axis, the first end wall (42) being configured to allow the object to be rolled to enter; a second end wall (43), opposite to the first end wall (42), being configured to allow the rolled object to exit; an upper beam system (10) and a lower beam system (11), which are parallel to each other and parallel to the rolling axis, and connect the first end wall (42) to the second end wall (43) above and below; wherein a single first side opening is provided on the first side of the rolling mill, between the first end wall (42) and the second end wall (43), for inserting and withdrawing the odd-numbered rolling mill stand (1); and wherein a single second side opening is provided on the second side of the rolling mill, between the first end wall (42) and the second end wall (43), for inserting and withdrawing the even-numbered rolling mill stand (2).

5. The rolling mill according to any one of the preceding claims, wherein, The first side platform (12) is disposed on the first side of the rolling mill, which is laterally arranged outside and parallel to the rolling mill unit, and is adapted to accommodate at least one odd-numbered rolling mill stand (1) withdrawn from the frame (4) and support at least one new odd-numbered rolling mill stand (1') to be inserted into the frame (4). Furthermore, the second side platform (13) is disposed on the second side of the rolling mill, which is laterally arranged outside and parallel to the rolling mill unit, and is adapted to accommodate at least one even-numbered rolling mill stand (2) withdrawn from the frame (4), and to support at least one new even-numbered rolling mill stand (2') to be inserted into the frame (4).

6. The rolling mill according to claim 5, wherein, The first side platform (12) is slidable parallel to the rolling axis and is provided with a plurality of first housings (14), which are configured to accommodate the corresponding odd number of rolling mill stands (1) of the rolling mill unit to be replaced, and are arranged alternately with a plurality of second housings (15) configured to support new odd number of rolling mill stands (1') along the rolling direction; Each of the plurality of first housings (14) is adjacent to one of the plurality of second housings (15); The first side platform (12) is configured to move from the pull-out position to the insertion position. In the pull-out position, the first empty housing (14) is located at the corresponding odd-numbered rolling mill stand (1) to be replaced. In the insertion position, the second housing (15) supporting the new odd-numbered rolling mill stand (1') is located at the corresponding odd-numbered compartment of the rolling mill unit, which is empty due to the corresponding odd-numbered rolling mill stand (1) that has just been pulled out. Furthermore, the second side platform (13) is slidable parallel to the rolling axis and is provided with a third housing (16) configured to accommodate the corresponding even-numbered rolling mill stand (2) of the rolling mill unit to be replaced, which is arranged alternately with the fourth housing (17) along the rolling direction to support the new even-numbered rolling mill stand (2'). Each of the plurality of third housings (16) is adjacent to one of the plurality of fourth housings (17); The second side platform (13) is configured to move from the withdrawn position to the insert position. In the withdrawn position, the third empty shell (16) is located at the corresponding even-numbered rolling mill stand (2) to be replaced. In the insert position, the fourth shell (17) supporting the new even-numbered rolling mill stand (2') is located at the corresponding even-numbered compartment of the rolling mill unit, which is empty due to the corresponding even-numbered rolling mill stand (2) that has just been withdrawn.

7. The rolling mill according to claim 5, wherein, The first side platform (12) is fixed and provided with a plurality of first housings (18), each of the plurality of first housings (18) being placed at a corresponding odd-numbered rolling mill stand (1) of the rolling mill unit and adapted to accommodate the odd-numbered rolling mill stand (1) once it is pulled out of the frame, and to accommodate a corresponding new odd-numbered rolling mill stand (1') ready to be inserted into the frame (4) once the pulled-out odd-numbered rolling mill stand (1) has been removed from the first housing (18); Furthermore, the second side platform (13) is fixed and provided with a plurality of second housings (19), each second housing (19) being placed at a corresponding even-numbered rolling mill stand (2) of the rolling mill unit and adapted to accommodate the even-numbered rolling mill stand (2) once it is pulled out of the frame, and to accommodate a corresponding new even-numbered rolling mill stand (2') to be inserted into the frame once the pulled-out even-numbered rolling mill stand (2) has been removed from the second housing (19); Preferably, at least one crane is provided for removing the odd-numbered rolling mill stand (1) extracted from the first housing (18) and positioning a new odd-numbered rolling mill stand (1') in the first housing (18), and for removing the even-numbered rolling mill stand (2) extracted from the second housing (19) and positioning a new even-numbered rolling mill stand (2') in the second housing (19).

8. The rolling mill according to any one of claims 2 to 7, wherein, The following devices are provided: The first actuator (20), located in the odd-numbered compartments of the frame (4), is used for inserting and withdrawing the odd-numbered rolling mill stands, and The second actuator (21), located in the even-numbered compartment of the frame (4), is used for inserting and withdrawing the even-numbered rolling mill stand.

9. The rolling mill according to claim 8, wherein, The first actuator (20) and the second actuator (21) are actuators, preferably hydraulic or electric actuators, configured to individually or in groups hook the rolling mill stands (1, 2) to be withdrawn from the frame (4) and move the rolling mill stands (1, 2) toward the relevant side platform (12, 13), and configured to subsequently individually or in groups hook the new rolling mill stands (1', 2') to be inserted into the frame (4) and move the new rolling mill stands (1', 2') from the relevant side platform (12, 13) toward the frame (4).

10. The rolling mill according to any one of the preceding claims, wherein, The frame (4) is provided with a plurality of odd-numbered compartments for the odd-numbered rolling mill stands and a plurality of even-numbered compartments for the even-numbered rolling mill stands; Each compartment is provided with at least one center abutment (22), which is adapted to define the end of the stroke of the corresponding rolling mill stand during the insertion of the frame (4); wherein the at least one center abutment (22) is positioned along a vertical plane close to the rolling axis, preferably at a distance from the rolling axis, the distance being shorter than the distance between the vertical plane containing the rolling axis and the vertical plane containing the vertical rotation axis (X, X') of one of the work rolls.

11. The rolling mill according to claim 10, wherein, Each compartment is equipped with: At least one lifting and locking actuator (23) is arranged on the lower inner surface of the compartment for lifting the corresponding rolling stand after the at least one central stop (22) has been reached; And at least one upper abutment block (24), which is arranged on the upper surface of the compartment and adapted to define the end of the lifting stroke of the rolling mill stand.

12. The rolling mill according to claim 11, wherein the at least one lifting actuator (23) is a cylinder having a rod having a wedge-shaped end (31), and wherein, The rolling mill stand has at least one recess (32) in its base, the shape of which is complementary to the wedge-shaped end (31) of the corresponding rod to accommodate the wedge-shaped end (31), thereby generating not only lifting but also lateral translation of the rolling mill stand to keep it against the at least one central abutment (22).

13. The rolling mill according to claim 10, wherein, Each compartment is provided with at least one first locking actuator (25), which is arranged on the upper surface of the compartment and preferably tilted at an angle of less than 90° and greater than 0° relative to the horizontal plane, so as to push the corresponding rolling stand downward after reaching at least one center abutment (22) and keep it against the at least one center abutment (22). Preferably, each compartment is further provided with at least one second locking actuator (26), which is arranged at the corresponding vertical column (7, 9) and adapted to apply a traction force to the rolling mill stand in the direction in which the rolling mill stand is inserted into the frame (4) to further hold it against the at least one central abutment (22). Preferably, the at least one second locking actuator (26) includes a piston or jack (27) capable of translating in two opposite translational directions along a direction perpendicular to the rolling axis, and wherein the rolling mill stand includes a seat (28) in which the piston or jack is adapted to engage to pull the rolling mill stand against the at least one central abutment (22).

14. The rolling mill according to any one of the preceding claims, wherein, At least two thrust actuators (29) are disposed in the frame (4) at the exit side of the rolled object leaving the rolling mill. The thrust actuators (29) are adapted to push the rolling mill frame one after another in a direction opposite to the rolling direction to lock the rolling mill frame against at least one fixed stop (33) in the frame (4) along the rolling axis. The fixed stop (33) is arranged on the inlet side of the object to be rolled in the rolling mill. Furthermore, the elastic device (30) is provided in the frame (4), arranged between the odd-numbered compartments and the even-numbered compartments of the frame (4), and adapted to transmit the thrust generated by the thrust actuator (29) by transferring the thrust from one rolling mill stand to the next rolling mill stand until the entire rolling mill unit is locked against the fixed stop (33). Once the thrust actuator (29) is deactivated, the rolling mill stand returns to its initial insertion position in the frame (4).

15. A method for replacing at least one rolling stand (1, 2) of a rolling mill according to any one of the preceding claims, wherein, The odd-numbered rolling mill stand (1) is inserted into the frame (4) and specifically withdrawn from the frame (4) from the first side of the rolling mill. The odd-numbered rolling mill stand (1) has a work roll (3') with a vertical rotation axis (X) parallel to the rolling axis located on the first side of the rolling mill. The even-numbered rolling mill stand (2) is inserted into the frame (4) and specifically withdrawn from the frame (4) from the second side of the rolling mill. The even-numbered rolling mill stand (2) has a work roll (3') located on the second side of the rolling mill with a vertical rotation axis (X') parallel to the rolling axis. The second side is opposite to the first side.

16. The method according to claim 15, wherein, A first side platform (12) is provided, which is arranged on the first side of the rolling mill and located outside the rolling mill unit, and a plurality of first housings (14) are provided along the rolling direction, the plurality of first housings (14) being alternately arranged with a plurality of second housings (15); wherein each first housing (14) is adjacent to one of the second housings (15); The unit includes a second side platform (13) which is arranged on the second side of the rolling mill and located outside the rolling mill unit. It also includes a plurality of third housings (16) arranged along the rolling direction, which are alternately arranged with a plurality of fourth housings (17). Each of the plurality of third housings (16) is adjacent to one of the plurality of fourth housings (17). Wherein, the first side platform (12) slides a single frame step parallel to the rolling axis, moving from the pull-out position to the insertion position. In the pull-out position, the plurality of first housings (14) are located in the corresponding odd-numbered compartments of the rolling mill, while the plurality of second housings (15) are located in the corresponding even-numbered compartments of the rolling mill. In the insertion position, the plurality of second housings (15) are located in the corresponding odd-numbered compartments, while the first housings (14) are located in the corresponding even-numbered compartments. In the withdrawn position of the first side platform (12), the plurality of first housings (14) accommodate the corresponding odd-numbered rolling mill stand (1) to be replaced, which is withdrawn from the corresponding odd-numbered compartment. In the inserted position, a new odd-numbered rolling mill stand (1') supported by the plurality of second housings (15) is inserted into the corresponding odd-numbered compartment, which is vacant due to the previous withdrawal of the corresponding odd-numbered rolling mill stand (1). The second side platform (13) slides a single frame step parallel to the rolling axis, moving from the withdrawing position to the inserting position. In the withdrawing position, the plurality of third housings (16) are located in the corresponding even-numbered compartments of the rolling mill, while the plurality of fourth housings (17) are located in the corresponding odd-numbered compartments of the rolling mill. In the inserting position, the plurality of fourth housings (17) are located in the corresponding even-numbered compartments, while the third housings (16) are located in the corresponding odd-numbered compartments. In the withdrawn position of the second side platform (13), the first housing (16) accommodates the even-numbered rolling mill stand (2) to be replaced, which is withdrawn from the corresponding even-numbered compartment, while in the inserted position, the new even-numbered rolling mill stand (2') supported by the fourth housing (17) is inserted into the corresponding even-numbered compartment, and the fourth housing (15) is left empty due to the withdrawal of the previous corresponding even-numbered rolling mill stand (2).

17. The method according to claim 15, wherein, A first fixed side platform (12) is provided, which is arranged on the first side of the rolling mill, located outside the rolling mill group, and the first fixed side platform (12) is provided with a first housing (18) in the corresponding odd-numbered compartments of the rolling mill group; The mill is provided with a second fixed side platform (13), which is arranged on the second side of the mill and located outside the mill unit. The second fixed side platform (13) is provided with a second housing (19) in the corresponding odd-numbered compartments of the mill unit. In order to replace at least one odd-numbered rolling stand (1) of the rolling mill, the following steps are set: Remove at least one odd-numbered rolling mill stand (1) to be replaced from the corresponding odd-numbered compartment and house it in the corresponding first housing (18); Preferably, the at least one odd-numbered rolling mill stand (1) is removed from the corresponding first housing (18) by a crane; Preferably, at least one corresponding new odd-numbered rolling mill stand (1') is housed in the corresponding first housing (18) by means of a crane; Insert the at least one corresponding new odd-numbered rolling stand (1') into the corresponding odd-numbered compartment; Furthermore, in order to replace at least one even-numbered rolling stand (2) of the rolling mill unit, the following steps are set: Remove at least one even-numbered rolling mill stand (2) ready for replacement from the corresponding even-numbered compartment and house it in the corresponding second housing (19); Preferably, the at least one even-numbered rolling mill stand (2) is removed from the corresponding second housing (19) by a crane; Preferably, at least one corresponding new even-numbered rolling mill stand (2') is housed in a corresponding second housing (19) by means of a crane; Insert the at least one corresponding new even-numbered rolling mill stand (2') into the corresponding even-numbered compartment.

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