EP0283342B2 - Rolling mill having axially shifting rolls, and roll profile control method - Google Patents

Description

The invention relates to a rolling mill with axially displaceable rollers and also covers a process for adjusting the profile and distributing wear of the rolls in such a rolling mill.

In general, a rolling mill comprises, inside a support cage, at least two working rolls resting, in a clamping plane, on at least two support rolls. The cylinders are carried at their two ends by means of bearings, in chocks mounted mobile, parallel to the clamping plane, in windows provided on each upright of the support cage, each chock being provided with two lateral guide faces. sliding along corresponding sliding faces formed on the amount of the cage on either side of the chock.

Usually called "quarto" rolling mills comprising two working rolls each leaning on a support cylinder and so-called "sexto" rolling mills in which intermediate rolls are interposed between the support rolls and the working rolls. In both cases, the axes of the cylinders are placed in the clamping plane, generally vertical, but it is also possible to support each working cylinder on a larger number of intermediate and / or support cylinders placed symmetrically on either side. other from the clamping plane.

To control the thickness of the rolled product and in particular to obtain a thickness equal in the direction transverse to the rolling direction, a working or bending of the working rolls and possibly of the intermediate rolls is carried out by means of bending devices acting on the chocks of the corresponding cylinder. Generally, the bending device consists, for each chock, of two sets of jacks placed symmetrically on either side of the chock. In addition, each support part of the chock rests on two cylinders spaced in the axial direction symmetrically on either side of the median plane of the chock bearings so that the bending force is well distributed on the bearings.

The rolling mill stand is symmetrical with respect to a median plane perpendicular to the clamping plane and which corresponds to the median plane of the rolled product. Normally the cylinders are therefore centered on this plane with respect to which the chocks are arranged symmetrically.

However, it may be advantageous to carry out a displacement of certain cylinders parallel to their axis and in the opposite direction or not, in order to satisfy various objectives such as the regularity of the wear of the cylinders or the control of the flatness or of the profit of the rolled product. .

It is understood that the axial displacement of the cylinders presents difficulties when these are subjected to a bending effort. This is why generally, the two operations are carried out separately, the bending effort being eliminated when an axial movement is carried out.

However, it is advantageous, during rolling, to combine the effects of axial displacement and of the bending of the rolls and consequently of being able to carry out the axial displacement of the rolls while maintaining the bending. In addition, the torque is generally applied to a single pair of cylinders, and the camber of the working cylinders, corresponding by friction. However, it is necessary that all the cylinders remain driven at the same peripheral speed.

Moreover, the bending of the working rolls also ensures a balancing effect between the rolls which it is useful to maintain during the axial adjustment even when the rolling force is eliminated.

The subject of the invention is a device allowing axial displacement of the cylinders without ceasing to exert the bending effort.

To this end, it has already been proposed to associate with each displaceable cylinder and its chocks a frame consisting of two beams slidably mounted axially on the stand of the rolling mill and on which the cambering devices which thus move are supported. together with the cylinders, their chocks and the frame (EP-A-067.040).

Document DE-A-3.331.055 describes a rolling mill according to the preamble of claim 1 in its version for the states DE, BE, GB and IT. in which each cambering cylinder bearing on an ear of the chock is housed in a drawer-shaped part, slidingly mounted, parallel to the axis of the cylinder, inside the support block, and secured to the chock so as to follow the axial displacements thereof. Therefore, the cylinder always remains well centered relative to the chock.

Such arrangements, however, complicate the production of the rolling mill.

In document EP-A-0 233 460, which conforms to article 54 (3) EPC, is shown a rolling mill with axially displaceable rollers comprising, inside a support cage, at least two working rolls based on a clamping plane P1, on at least two support cylinders and the ends of which are carried, by means of bearings, in chocks slidably mounted in the support cage, parallel to the clamping plane P1, at least one of the working rolls being associated, on the one hand, with means for moving said cylinder along its axis on either side of a position for centering the working rolls on the median plane P2 of the cage and on the other hand means for bending said cylinder comprising, for each chock and on each side of the clamping plane, at at least one cambering cylinder placed inside a support block secured to the cage and acting on a corresponding support part of the chock by means of a sliding part comprising at least one part of support extending above each cylinder and at least one foot-shaped guide portion, sliding vertically in a machining operation carried out inside the support block and on which is formed, on the side opposite to the camber cylinders, a flat and smooth face parallel to the axis of the cylinder, on which is supported with the possibility of sliding, the corresponding support part of the chock.

The invention relates to a new device making it possible to carry out at the same time the bending and the axial displacement of the working rolls or the intermediate rolls without appreciably modifying the constitution of the rolling mill.

The invention makes it possible, in fact, to use fixed cambering cylinders housed, in a conventional manner, inside the support blocks while avoiding high friction between guide surfaces liable to disturb the vertical adjustment movements of the chocks .

The invention therefore applies to a rolling mill with axially displaceable rollers comprising, inside a support cage at least two working rolls resting on a clamping plane, on at least two support rolls and the ends of which are carried, by means of bearings, in chocks slidably mounted in the support cage, at least one of the working cylinders being associated, on the one hand, with means for moving said cylinder along of its axis on either side of a position for centering the working rolls on the median plane of the cage, and on the other hand, to means for bending said roll comprising, for each chock and on each side of the clamping plane, at least one cambering cylinder placed inside a support block secured to the cage and acting on a corresponding support part of the chock.

In the arrangement according to the invention, on each side of the clamping plane, the cambering cylinder or cylinders bear on the corresponding part of the chock by means of a sliding part comprising at least one bearing part extending above each cylinder and at least one foot-shaped guide part, slidingly mounted vertically in a machining carried out inside the support block and on which is formed, on the side opposite to the camber cylinders, a flat and smooth face parallel to the axis of the cylinder, on which is supported, with the possibility of sliding, the corresponding support part of the chock.

In this way, the cambering effort is exerted by means of fixed jacks bearing at each end, on one side on the support block secured to the cage and the other on a part allowing the sliding of the chock during axial displacements, this part being slidably mounted on the support block in the direction of application of the bending effort and provided with embedding means to resist the effects of overturning in the direction of axial displacement of the cylinders.

Such a sliding part had already been provided in document EP-A-233,460 benefiting from an earlier date, but published after the priority date of this patent.

In this previous arrangement, the sliding part interposed between the camber or cylinders and on which the chock can slide, is also provided with at least one guide foot sliding in a bore of the support block. However, this bore has a circular section, the guide foot being a simple round rod.

The present invention allows, on the other hand, to make a distinction between two guide planes, the sliding part being guided between two pairs of guide faces, respectively parallel and perpendicular to the clamping plane.

The guidance thus produced makes it possible to resist the overturning forces resulting from the misalignment of the support parts of the chock with respect to the sliding part during axial displacements and, having regard to the length of the guide foot, the latter takes place with low friction and not penalizing vertical movements.

According to a particularly advantageous characteristic, the two guide faces perpendicular to the clamping plane constitute two opposite faces of the machining between which the guide foot of the sliding part can slide and the two guide faces parallel to the clamping plane constitute two opposite faces of a transverse recess formed in the support block, between which a part of the sliding part can slide.

Preferably these two guide faces parallel to the clamping plane are symmetrically spaced on either side of the plane passing through the axes of the cambering cylinders and the support part of the chock is itself centered in the same plane in which thus pass all the forces applied by the bending.

In this way, in the case where each support part of the chock is associated with a bending assembly comprising two jacks spaced from one another, the machining carried out in the support block comprises an enlarged external part passing over the two camber cylinders in which the external part of the T-shaped sliding part is guided, on which the chock rests on one side and, on the other, the camber cylinders and a internal part forming a central well in which the guide foot of the sliding part is guided.

In most cases, the embedding effect of the guide foot makes it possible at the same time to carry out the axial displacement and the bending of the working rolls by opposing the overturning moment which results from the offset of the median plane of the bearing with respect to the plane of symmetry of the two pairs of bending cylinders. However, if this offset becomes too large, it results in friction which can oppose the sliding of the sliding part.

In this case, according to another embodiment of the invention, it is advantageous to apply different pressures on the two jacks of each pair, taking into account the axial offset of the cylinder so as to cancel the sum of the overturning moments exerted on the sliding part and thus reducing to the minimum the guide friction of this part.

For this purpose, the offset of the working cylinder with respect to the centering position on the median plane of the product is measured at all times and the individual pressure exerted by each cylinder is permanently adjusted for each offset. measured so that, for each sliding part, the moment resulting from the sum of the moments of each cambering cylinder and that of the reaction of the chock is zero.

Advantageously, the two chocks of each movable cylinder being each associated with two symmetrical sets of camber cylinders, arranged on either side of the rolling plane, the jacks placed respectively, in each of the assemblies, in the same relative positions relative to the median plane of their respective bearings are connected in parallel to the same branch of a common circuit for supplying pressurized fluid comprising as many branches as there are jacks in each assembly, each branch being provided with an adjustment means individual fluid pressure with equal flow maintenance in all branches.

The means for individual adjustment of the pressures in the jacks comprise, on each branch of the supply circuit, a servo-valve controlled by a means of calculating the corrections to be made to the pressures as a function of the offset measured and displayed on the calculation means and respective positions of the cylinders supplied by the branch in question.

According to another particularly advantageous characteristic of the invention, each chock can be associated with positive bending means each comprising at least two jacks. These sets of cylinders are formed in hydraulic blocks placed on either side of the clamping plane, in the windows of the cage; each block consists of a massive support piece comprising a central part machined to receive the T-shaped pieces on which the support ears of the chock rest, these being each provided with a face of continuous sliding parallel to the sliding axis.

Other features and other advantages of the invention will appear in the following description of a particular embodiment, given by way of example and shown in the accompanying drawings.

Figure 1 shows schematically, in perspective, the arrangement of a quarto rolling mill with movable cylinders.

Figure 2 is a partial top view of a working cylinder and its displacement means.

Figure 3 is a partial view of the rolling mill cage showing the two working rolls and the bending devices, in section through a plane parallel to the rolling plane and passing through the axes of a set of bending cylinders in one embodiment using continuous beams passing through the cage and having T-shaped ends

Figure 4 is a partial view of the bending devices, in section through a plane parallel to the rolling plane and passing through the axes of a set of bending cylinders in the embodiment using separate intermediate parts in the shape of a T.

Figure 5 shows the particular section of these parts in section through a transverse plane, the chocks being spaced from one another.

FIG. 6 is a view of the chocks of the two working rolls and of the bending devices in section through a plane perpendicular to the rolling plane and passing through the axes of the bending cylinders.

FIG. 7 gives a hydraulic diagram of the balancing device in a more improved embodiment.

There is shown schematically in a quarto rolling mill comprising two working rolls (1) and (1 ') and two support rolls (2) and (2'). The axes of the rolls are parallel and arranged along a clamping plane P1 passing through the contact generators

The rolled product 20 passes between the working rolls (1) and (1 ') and its median plane corresponds substantially to the transverse plane of symmetry P2 of the whole of the rolling mill stand and in particular of the supporting rolls (2) and (2 '). Normally, the cylinders are all aligned and centered on the same median plane P2. However, for the reasons indicated above, the working rolls (1) and (1 ') can be displaced axially relative to the centering position so that their respective transverse plane of symmetry is shifted to one side or the other with respect to the median plane P2. To this end, an axial displacement force F1 is applied in one direction or the other to the working cylinders (1) and (1 ′).

On the other hand, according to another known arrangement, cambering forces F2 are applied to the ends of the shafts of the working rolls (1) and (1 '), by means of their chocks so as to camber the corresponding cylinder.

Thanks to the arrangements according to the invention, the working rolls (1) and (1 ') can be subjected at the same time to an axial displacement force F1 and to the bending forces F2.

FIG. 2 shows an end of a working cylinder with a chock, and an axial displacement device. The working cylinder (1) is provided at its two ends with centered trunnions, by means of bearings , inside chocks (3) forming a bearing body and sliding mounted, parallel to the clamping plane P1, in windows (40) formed in the two uprights (4) of the rolling stand.

To this end, as shown in FIG. 5, each chock (3) of the working cylinder 1 is provided with sliding faces (31) parallel to the clamping plane P1 and which can slide along corresponding faces ( 51) arranged inwards on support blocks (5) fixed in the windows (40) of the stand (4) of the rolling mill.

In this way, each chock (3) guided between the two vertical faces (51) can move in two directions, on the one hand vertically under the action of the bending device and on the other hand parallel to the axis (10 ) of the cylinder under the action of the axial adjustment device.

Various devices are known for axial displacement of the cylinders which do not constitute the subject of the invention and which it is therefore not useful to describe in detail.

In general, the axial displacement force which is applied to one of the chocks must be exerted exactly in the axis of the cylinder and, for this purpose, one can use, for example, a single jack supported on a lifting beam making it possible to apply the axial displacement force on the two sides of the chock.

However, if the displaced cylinder is a driving cylinder, it is also possible, as shown in FIG. 2, to use displacement cylinders (42) supplied in synchronism and placed symmetrically on either side of the means (43 ) for driving the cylinder in rotation (1), the chock (3) being provided, on each side of the axis (10), with hooking lugs (35) which engage in hooking heads corresponding to the rod of each cylinder (42). This attachment can advantageously be carried out in a removable manner by lateral displacement of the displacement cylinder (42) as shown in FIG. 2 for the right cylinder.

On the other hand, each chock (3) of a cylinder (1) is secured to the latter in the axial direction by means of a cap (13) for closing the bearing cage, the latter being made of so as to be able to withstand axial forces, for example tapered bearings In this way, the axial displacement force applied by the jacks (42) on one of the chocks (3) is transmitted to the working cylinder and to the second chock placed at the other end of the latter.

Each chock (3) is on the other hand associated with a cambering assembly which, as shown diagrammatically in FIG. 6, generally consists of two pairs of jacks (6 a , 66 a ) and (6 b , B ) placed respectively on either side of the clamping plane P1 on which the axis of the cylinder 1 is centered.

We know that we can achieve either a so-called "positive" bending in which the opposite chocks of the two working rolls deviate from each other, or a "negative" bending for which the opposite chocks are close together . However, it is generally necessary to oppose the approximation of the chocks which results in crushing of the edges of the sheet relative to the central part and that is why, in the most common case shown in the figures, only positive bending is carried out c that is to say in the direction of spacing of the chocks with respect to the plane of passage of the sheet, according to the arrows F ₂ in FIG. 1.

To this end, as can be seen in FIG. 6, each chock 3 is extended beyond the sliding faces (31) by bearing parts (32) in the form of ears which extend above the block. support (5) in which are housed the camber cylinders (6). However, the bending force is not applied directly to the chocks (3), but to intermediate pieces (7) which are interposed between the bending cylinders (6) and the corresponding support parts (32).

Each support block (5) is common for the two working cylinders (1) and (1 ') and comprises, at each end, at the top and at the bottom, a transverse recess (52) limited by two spaced faces (54) parallel to the clamping plane Each intermediate piece (7) is provided with an external horizontal part (70) housed in the recess (52) and guided in translation along corresponding sliding faces on the two opposite faces (54) of the housing (52).

Preferably, each intermediate part (7) has the shape of a T, the external part (70) forming two horizontal wings (75) which extend symmetrically on either side of a vertical central part (73) centered in the median plane P3 of the support block (5) perpendicular to the clamping plane P1, that is to say the vertical plane of symmetry of the two pairs of camber cylinders in which the chock (3) of each is centered two working cylinders (1 and 1 ') when the latter are themselves aligned and centered on the median plane P2 of the cage.

The two camber cylinders (6 a , 66 a ) symmetrical with respect to the plane P3, each consist of a piston (62) mounted to slide vertically in a bore (67) formed in the support block (5).

The vertical central part (73) of the intermediate piece (7) extends vertically between the two cylinders (6 a, 66 a) and engages in a machining (53) forming a central well formed in the support block (5) between the bores (67) of the two cylinders (6 a, 66 a) which extends the transverse recess (52) wherein the two wings extend (75) of the intermediate piece (7) to pass over the two jacks (6 a, 66 a) .

The central part (73) constitutes a guide foot for the intermediate part (7) mounted to slide vertically between two guide faces (55) parallel to the plane P3 and symmetrically spaced apart on either side of it and which constitute the two opposite faces of the central machining (53).

The same arrangement is adopted for the cylinders (6 ′ a , 66 ′ a ) for bending the lower cylinder (1 ′). The support block (5) which is common for the two working cylinders (1 and 1 ') is therefore symmetrical, on the one hand, with respect to the vertical plane P3 and on the other hand, with respect to a horizontal plane.

To make the cambering assemblies (6 and 6 ') associated with the two cylinders, there are therefore housed in the block (5), on each side of the plane of symmetry P3, two bores (67 and 67') separated by a central partition ( 68) and opening in the transverse recesses (52, 52 ') formed on the two faces, respectively upper and lower, of the block (5) and in which engage the upper parts (70, 70') of the two parts intermediate (7, 7 ') on which the chocks (3 and 3') of the two working cylinders (1 and 1 ') are supported respectively. Each bore (67) is sealed by a partition (63) which constitutes the bottom of the transverse recess (52) and limits the chamber of the jack (6) closed, on the opposite side, by the partition 68 and inside which slides the piston (61) extended by a rod (62) which passes through the partition (63) to rest on the corresponding wing (75) of the intermediate piece (7).

The two pairs of jacks (6 a , 66 a ) (6 ′ a , 66 ′ a ) thus formed on the two faces of the support block (5) can be supplied by hydraulic circuits as shown in FIG. 7, the support piece (5) thus constituting a real fixed hydraulic block.

Furthermore, the support lug (32) of the chock (3) is supported, by means of a grain of thrusts (33) on a smooth face (76) formed on the external part (70) of the intermediate piece (7) and along which the thrust grain (33) can therefore slide continuously following the axial displacements of the cylinder 1.

The thrust grain (33) is placed in the transverse plane of symmetry of the chock (3) and is therefore centered in the plane P3 in the position shown in FIG. 4 for which the working rolls (1) and (1 ') are aligned and centered in the median plane P2 of the cage.

Because the support block (5) is common for the two bending systems (6 and 6 ') of the two working rollers (1 and 1'), the central parts forming the guide foot (73, 73 ') of the two intermediate parts (7, 7') engage in the same machining (53) which completely crosses the support block (5), in the axis thereof, connecting between them the transverse recesses (52 and 52 ') and passing between the chambers of the four cylinders arching.

As shown in FIG. 5, the guide foot (73) of each intermediate piece (7, 7 ′) is provided, at its end opposite to the external part (70), with a notch in the form of L which provides a thinned part (74) offset laterally so that the two guide feet (73, 73 ') can overlap in the middle part of the central machining (53). In this way, each guide foot (73, 73 ') can be guided practically all along the guide faces (55) formed over the entire height of the central machining (53).

Furthermore, in the axial direction, the two support parts (33) of each chock are also centered in thrust planes P4 parallel to the clamping plane P1 and passing through the axes of the two corresponding camber cylinders.

As can be seen in FIG. 5, the thrust planes P4, P'4 of the two cambering assemblies associated with the chocks (3 and 3 ') and placed in the same support block 5 are offset on either side of the plane of symmetry of the support block 5 on which the machining is centered (53).

When, by means of the jacks (42), an axial displacement of one of the cylinders is controlled, for example the working cylinder (1), the corresponding thrust grain (33) slides on the smooth face (76) of the intermediate piece (7) on one side or the other of the plane of symmetry P3. If, at the same time, a cambering force is exerted on the cylinder, each sliding part (7) moves vertically thanks to its guide foot (73) which opposes the moment of overturning resulting from the shifting of the thrust grain (33) relative to the plane of symmetry of the forces exerted by the jacks.

The invention therefore makes it possible to carry out at the same time the axial adjustment and the bending of a working cylinder and if the axial displacements remain reduced, as is most often the case, the moment of overturning of the intermediate piece (7 ) which results can be easily collected by the embedding effect of the guide foot (7).

This avoids increasing the pressures on the vertical guide surfaces which could increase friction and penalize the performance of the thickness regulation.

However, if it is desired to make greater axial displacements, the resulting overturning moment may result in excessive friction forces liable to disturb the movement of the chock. It is then preferable to add to the embedding effect of the guide foot other provisions making it possible to reduce friction by balancing the applied forces.

Various means can be used for this purpose.

Thus, in the embodiment shown in Figure 3, the intermediate pieces (7) and (7a) corresponding to the two chocks (3) and (3a) of each cylinder (1) and which are placed at the same level with respect to the axis of the cylinder, are integral with a beam (77) extending along the cylinder, parallel to its axis. This beam (77) can be dimensioned so as to absorb the moments of overturning of the parts (7) and (7a) due to the movement of the chocks (3) and (3a).

This simple arrangement can however have a drawback insofar as the four beams (77) extend between the two uprights of the cage, near the working rolls, that is to say in a space which is has an interest in clearing.

This is why, in a preferred embodiment, a balancing of the forces applied by the bending cylinders is carried out as a function of the position of the corresponding chock.

According to one of the essential characteristics of the invention, the offset of the displaced cylinder (1) is measured relative to the median plane P2 of the cage by means of a displacement sensor (44) consisting of two sliding parts, one relative to each other, fixed, for example on the two parts of one of the jacks (42) and providing an analog or digital signal proportional to the offset of the working cylinder relative to the centering position in the median plane P2 and of sign corresponding to the direction of the shift. This signal is used for balancing the pressures in the camber cylinders by means of a device (8) shown diagrammatically in FIG. 7.

In this figure, there is shown by way of example a displaceable cylinder (1) and its two bending devices each consisting of two sets of jacks placed in hydraulic blocks (5a, 5b, 5'c, 5'd) each assembly comprising two cylinders (6a, 66 a), (6b, 66b), (6'a, 66'a) (6'b, 66'b).

By convention, the reference 6 is assigned to the camber cylinders, placed on the side of the cylinder, that is to say towards the inside of the cage and the reference 66 to the cylinders placed towards the outside.

The four jacks associated with each chock are arranged in the manner described above and are centered in two transverse planes R3 and R4 spaced from each other by a distance e.

The hydraulic blocks (5a, 5b) and (5c, 5d) of the two chocks are connected by a single supply circuit (80) to a source of pressurized fluid not shown but the circuit (80) is divided into two branches ( 81) and (82) making it possible to supply the jacks placed on the same side of the same pressure chock in the direction of axial movement. The branch (81) therefore supplies in parallel the jacks (6 a , 6 b ,) and (66 c , 66 d ) of the two rows R3 and R'4 placed on the right in FIG. 7 while the branch 82 supplies parallel the jacks (66 a , 66 b ,) and (6 c , 6 d ) of the two rows R4 and R'3 placed on the left.

The hydraulic circuit is designed so that, whatever the pressures, all the cylinders are supplied with the same flow rate so as to determine equal displacements at the same speed.

Each branch (81), (82) of the supply circuit (8) is provided with a pressure regulator (83) which, depending on the signals received on its input (84) regulates the pressure in the corresponding circuit but in maintaining a constant flow.

Each cylinder (1) is associated with an axial displacement sensor (44) providing an analog or digital signal proportional to the displacement and which is applied to a calculation unit (85).

From the signals received, the latter develops the pressure setpoints S1 and S2 applied to the inputs (84) of the pressure regulators (83) of the two branches (81) and (82) according to a law programmed in the advance to ensure a distribution of pressures P1 and p2 such that the sum of the moments resulting from the thrust forces applied by the camber cylinders in the planes P4 and the reaction of the bearing part 32 of the corresponding chock on the T-shaped part is zero. In this way, even in the centering position of the cylinders (1) in the median plane P2 of the cage, the two rows of cylinders R3 and R4 may not be symmetrical with respect to the median plane P5 of the chock roll and this allows the cylinders to be arranged in the most adequate manner inside the hydraulic blocks (5) whose plane of symmetry does not necessarily coincide with that of the bearing.

Of course, the invention is not limited to the details of the embodiment which has just been described, variants which can be imagined by employing in particular equivalent means without departing from the protective framework defined by the claims.

In particular, the various members used for balancing the pressures could be replaced by means fulfilling the same functions, these means being able to be hydraulic, electric or even mechanical (cam, lifting arm, etc.). In general, any technology for measuring displacements, calculating corrections and balancing pressures can be used to obtain the desired result.

It will also be noted that, as indicated on the left side of FIG. 6, the fixed bending devices according to the invention can adapt to different diameters of cylinders and / or adapt to a variation of the diameter due wear, within the limit of the cylinder stroke.

Finally, the invention has been described in the case of a rolling mill with positive bending only but the same arrangements could be used to bend each cylinder in both positive and negative directions.

Without appreciably modifying the embodiment described above, it would suffice, for example, to use double-acting jacks whose rods are fixed to the support ears of the chocks to act in one direction or the other.

But one could also, in another arrangement, use single-acting cylinders placed in pairs on either side of the support part of the chock, each pair of cylinders being associated with a sliding piece in T.

The reference signs inserted after the technical characteristics mentioned in the claims have the sole purpose of facilitating the understanding of the latter, and in no way imitate their scope.

Claims (16)

1. Rolling mill with axially shiftable rolls, comprising, inside a supporting stand (4), at least two working rolls (1, 1') which bear on at least two back-up rolls (2, 2') along an adjusting plane P1 and the ends of which are carried, by means of rolling bearings, in chocks (3, 3') mounted so as to slide in the supporting stand (4), parallel to the adjusting plane P1, at least one of the working rolls (1) being associated, on the one hand, with means (42) for shifting the said roll (1) along its axis (10) on either side of a centring position of the working rolls on the mid-plane P2 of the stand (4) and, on the other hand, with means (6) for bending the said roll (1), comprising, for each chock (3) and on each side of the adjusting plane, at least one bending jack (6) arranged inside a supporting block (5) fixed to the stand, and acting on a corresponding bearing part (32) of the chock (3) by means of a sliding piece (7) comprising at least one bearing part (75) extending above each jack (6) and at least one guide part (73) in the shape of a foot, sliding vertically in a machined hole (53) produced inside the supporting block (5) and on which bearing part is formed, on the side opposite the bending jacks (6), a plane and smooth face (76) parallel to the axis of the roll (1) and on which the corresponding bearing part (32) of the chock (3) bears, with the possibility of sliding, the sliding piece (7) being mounted so as to slide between two pairs of guide faces (54) (55), formed inside the supporting block (5) and respectively parallel and perpendicular to the plane.
2. Rolling mill according to Claim 1, characterised in that the two guide faces (55) perpendicular to the adjusting plane P1 constitute two opposite faces of the machined hole (53) between which the guide foot (73) of the sliding piece (7) can slide, and in that the two guide faces (54) parallel to the adjusting plane (P1) constitute two opposite faces of a transverse recess (52) formed in the supporting block (5), between which a part (70) of the sliding piece (7) can slide.
3. Rolling mill according to one of Claims 1 and 2, characterised in that the two guide faces (54) formed in the supporting block (5) parallel to the adjusting plane P1 are set apart from one another symmetrically on either side of a thrust plane P4 which passes through the axes of the bending jacks (6) and in which the bearing part (32) of the chock (3) is likewise centred, all the forces exerted for bending being thus transmitted in the said thrust plane P4.
4. Rolling mill according to one of Claims 1 to 3, in which each bearing part (32) of the chock (3) is associated with a bending assembly (6) comprising two jacks (6, 66) set apart from each other and centred in a plane P4 parallel to the adjusting plane P1, the sliding piece (7) having the shape of a T comprising a central part (73) forming the guide foot and a widened outer part (70) forming two wings (75) extending horizontally on either side of the foot (73), each above one of the said jacks (6) and (66), the machined hole produced in the supporting block (5) comprising a transverse part (52) which extends above the two bending jacks (6) and in which is guided the widened outer part (70) comprising the two wings (75) of the T-shaped sliding piece (7), and a central part (53) forming a well, in which the central part forming the guide foot (73) of the sliding piece (7) is guided.
5. Rolling mill according to Claim 4, characterised in that, in each upright (4) of the stand of the rolling mill, the bending assemblies (6) (6') of the two working rolls (1) (1') are mounted in a single supporting block (5) having, on its two opposite faces, two transverse recesses (52) (52') connected by means of a single central machined hole (53) passing between the bending jacks (6) (6').
6. Rolling mill according to Claim 5, characterised in that the guide foot (73) of each sliding piece (7) forms, on the same side as the corresponding chock (3), an interlocking head of a width sufficient to absorb the tilting effects of the sliding piece (7) during bending, and in that its inner end, on the opposite side to the chock (3), has, in cross-section taken in a plane parallel to the adjusting plane P1, an L-shaped indentation forming a thinned part (74) offset laterally relative to the thrust plane P4, so that the two thinned parts (74, 74') of the two sliding pieces (7) and (7') associated respectively with the two working rolls (1) (1') overlap in the central part of the single machined hole (53) made in the centre of the supporting block (5).
7. Rolling mill according to one of Claims 4 to 6, characterised in that the two thrust planes P4, P'4 of the bending assemblies (6) (6') associated respectively with the two working rolls (1) (1') are offset laterally on either side of the mid-plane of the central machined hole (53) of the supporting block (5).
8. Rolling mill according to one of Claims 4 to 7, characterised in that it possesses a balancing device (10) for the bending jacks (6), comprising a means (44) for measuring the shift of the roll (1) in question in relation to the centring position, and means (83) for the individual adjustment, at any moment, of the pressure exerted on each bending jack (6) as a function of the offset measured and of the position of the jack (6) in question in relation to the mid-plane of the sliding piece (7), in such a way that the sum of the torques arising as a result of the exertion of the bending forces and the reaction torque of the chock on the sliding piece (7) is zero.
9. Rolling mill according to one of the preceding claims, characterised in that the sliding pieces (7, 7a) of the two chocks (3, 3a) of one and the same roll (1) which are located at the same level in relation to the axis of the roll (1) are formed at the two ends of a continuous beam (77) extending parallel to the axis of the roll (1) between the two corresponding uprights of the stand (4).
10. Rolling mill according to Claim 8, characterised in that, with the two chocks (3) (3a) of each roll each associated with two symmetrical sets of bending jacks, arranged on either side of the adjusting plane (P1), the jacks (6a and 6b) (66d and 66c) placed respectively, in each of the sets, in the same relative positions in relation to the mid-plane (P5) of their respective rolling bearings are connected in parallel to one and the same branch (81) (82) of a common pressurised-fluid feed circuit (80) comprising as many branches as there are jacks (6, 66) in each set, each branch being equipped with a means (83) for the individual adjustment of the pressure of the fluid, with equal flow rates being maintained in all the branches.
11. Rolling mill according to Claim 10, characterised in that the means for the individual adjustment of the pressures in the jacks comprise a servovalve (83) on each branch (81) (82) of the feed circuit, the said servo-valves being controlled by a means (85) for calculating, on the basis of a programmed law, corrections to be made to the pressures as a function of the offset measured and displayed by the calculation means and the respective positions of the jacks fed by means of the branch in question, in order to ensure a correct distribution of the pressure force.

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