EP0738546B1 - Rolling mill with large opening - Google Patents

Description

The subject of the invention is a rolling mill in which the opening of the working cylinders can be adjusted to a large amplitude which can, for example, exceed 300mm for laminating product with very thick varied and applies in particular to roughing cages and to the rolling of aluminum or other metals not ferrous.

A rolling mill generally includes a cage fixed having two uprights spread between which are at least two working cylinders with axes substantially parallel and placed substantially in a clamping plane transverse to the direction of travel of the product and which generally constitutes a median plane from the cage. The so-called quarto rolling mills include four superimposed cylinders, respectively two working rolls extending on either side of a passage plan of the product to be laminated and associated, respectively, with two support cylinders. In the sexto rolling mills, intermediate cylinders are interposed between each working cylinder and the corresponding support cylinder.

Other types of rolling mills, including a plus or fewer cylinders are known and used in industry.

In some cases, each working cylinder may be associated with several support cylinders arranged symmetrically on either side of the clamping plane.

Each cylinder is rotatably mounted around its axis, on bearings carried by two support chocks strung respectively in two windows arranged in the two amounts of the cage.

Clamping means such as screws or jacks, bearing on the cage, exert a vertical force of tightening of cylinders for rolling the product passing between the working cylinders. That is why the chocks of each cylinder are mounted sliding, parallel to the clamping plane, each between two flat guide faces provided respectively on either side of said clamping plane on both sides of the corresponding window of the cage. As the support cylinders have a large diameter, the corresponding guide faces are generally provided directly on the corresponding amount of the cage. On the other hand, the working cylinders having a smaller diameter, their chocks are smaller and the corresponding guide faces, which are more tightened, are generally arranged on two blocks side fixed on both sides of the window and which extend inwardly projecting therefrom.

Such an arrangement is described, for example, in document EP-A-059.417 which applies to a rolling mill type sexto and includes, on each amount, two blocks blocks for guiding chocks of the two cylinders of work and, for each of the intermediate cylinders, two chocks guide blocks in which are housed hydraulic cylinders for bending said intermediate cylinders.

Indeed, to correct flatness defects of the product, it is useful to modify the distribution of stresses along the working cylinders by exerting cambering efforts either directly on the chocks from working rolls, i.e., in a rolling mill sexto, on the chocks of the intermediate cylinders, so as to cause controlled flexions of these.

Generally, cylinders are used for this purpose. hydraulics placed on either side of each chock and leaning in one direction on a lateral part forming a support ear for the chock and in the other, on the guide block resting on the fixed cage and in which are the camber cylinders with their hydraulic circuit, the guide blocks being called, for this reason, hydraulic blocks.

In such an arrangement, the clamping cylinders maintain working cylinder spacing corresponding to the thickness to be given to the product and the bending cylinders which act on the positions respective chocks are used simply to correct flatness defects.

Often the cylinders placed on the blocks hydraulics determine a so-called cambering effect positive, corresponding to a spacing of the chocks of the two working cylinders and other cylinders, taking support on the fixed cage or on the chocks of the cylinders of support determine a so-called negative cambering effect of working cylinders, corresponding to an approximation of their chocks.

But we can also use double cylinders effects like, for example, in the layout of the document EP-A-059.417.

Furthermore, it is necessary to replace or periodically check the working cylinders and these must therefore be able to be removed from the cage, this removal by sliding the whole of a cylinder and its chocks parallel to its axis. he therefore, the means for guiding the chocks allow the removal of these with the cylinder corresponding.

To facilitate and accelerate the replacement of working cylinders, these are usually operated in pairs, the chocks from the cylinder superior work resting on those of the cylinder of lower work during replacement operations.

Such a possibility of axial sliding is also useful for adjusting the distribution of effort rolling to the width of the product by axial displacement relative working cylinders or cylinders intermediates, in the case of a sexto rolling mill such as described, for example, by document EP-A-059.417, already cited. In this case, the camber cylinders housed in the fixed hydraulic blocks rest on parts intermediates mounted vertically and on which support the chocks, with a possibility of horizontal sliding to allow axial displacement of the cylinder.

The guidance of chocks must therefore be ensured, not only in the vertical direction, parallel to the plane of tightening, for adjusting the air gap, but also in the horizontal direction, parallel to the axes of the cylinders, to allow removal and placement, by axial sliding of the pair of working cylinders.

For all these reasons, the chocks of the two working cylinders must be kept between the guide faces provided on the two blocks hydraulic.

The adjustment possibilities of the air gap between the working cylinders are therefore limited because it is necessary that, even in the fully open position, the chock remains guided over a certain height to maintain the axis of the corresponding cylinder in the clamping plane without generate parasitic friction against the faces of guidance.

This is why the known devices used so far for the positive or negative arching of cylinders with chock guide were suitable only to rolling mills with an adjustment stroke relatively limited.

However, for some applications, it is necessary to adjust the spacing of the cylinders work on a large opening stroke so as to laminate products of very varied thickness. It's the in particular, roughing cages and cages used for rolling non-ferrous metals such as aluminum in which a very significant reduction in thickness.

In this case, it is difficult to realize a system chock arching compatible with guidance correct, without unduly complicating the mounting of cylinders in the cage and circuit connections high pressure hydraulics.

The object of the invention is to solve these problems thanks to a new assembly of chocks which allows to guide them over a long race without complicating the arrangement of the cambering means and hydraulic circuits.

In addition, the arrangement according to the invention makes it possible to limit parasitic friction and keep a simple window geometry with reduced width and, therefore, without weighing down the columns of the cage.

The invention therefore generally applies to any rolling mill of known type including, inside of a cage having two uprights apart, at least two working cylinders with substantially parallel axes, defining an air gap for the product to be laminated along a substantially horizontal passage plane and rotatably mounted around their axis, each in two chocks strung in windows respectively corresponding in the two amounts of the cage, said chocks being slidably mounted each between two plane guide faces parallel to a clamping plane passing substantially through the axes of the working cylinders, and arranged on both sides of the corresponding window.

Such a rolling mill is also associated with means for bending at least one of the cylinders of work including, for each chock, at least two hydraulic cylinders placed on either side and each other of the chock, each in a support piece attached to the corresponding side of the window and forming a hydraulic block, each hydraulic cylinder having a body formed in said support piece and a piston associated with a rod, slidably mounted in the body, parallel to the clamping plane and supported by a lateral support part of the chock.

According to the invention, on each side of the plane the support piece of at least one cylinder bending of at least one of the working cylinders includes a portion for holding the rod of said cylinder which engages in a corresponding recess provided on the side of the chock of said cylinder to a bottom forming the support part of the jack, and said side of the slab is limited, on either side of said recess, by two plane sliding faces capable of slide along two mating guide faces formed on the corresponding side of the window, on either side of said part holding part of support.

In this way, each side of the chock is provided with a U-shaped sliding face open on the plane side passage of the product and comprising a central part spanning the width of the chock at the bottom of the recess, and two lateral branches between which engage the rod holding part of the cylinder.

In the event that the level of one of the cylinders work is substantially constant, the level of the other cylinder can vary for the adjustment of the air gap, the rod of each adjustable cylinder camber cylinder is sliding mounted in the support piece on a height at least equal to the adjustment amplitude of the air gap and said support piece comprises a part sliding support of the cylinder rod, engaging, on the adjustment height, in a chock recess of the adjustable cylinder and a part forming the body of the cylinder, placed at the level of the chock of the fixed cylinder.

For this purpose, each support piece of at least one bending cylinder advantageously comprises two parts extending respectively on either side of the plane of passage of the product, respectively a narrow part of sliding support of the rod or cylinders cambering, which engages in a recess of the chock corresponding to a first working cylinder and a large part in which the body of the bending cylinders and which is laterally limited by a sliding guide face of the chock second working cylinder, the latter being associated with camber cylinders housed in said wide part of the support piece.

In a preferred embodiment, the two working cylinders are associated with cylinders positive camber determining the spacing of their chocks and arranged in pairs of two opposite cylinders, the inside of two support pieces placed respectively on either side of the clamping plane passing substantially through the axes of the cylinders.

Advantageously, each support piece can be provided with at least one common bore forming the body two opposite cylinders whose rods are supported respectively, in opposite directions, on the chocks of the two working cylinders.

In this case, a single room can be placed between the two pistons of the two opposite cylinders and supplied with oil for the simultaneous actuation of said cylinders.

However, the bore common to the two cylinders can also be separated by a partition into two supplied chambers separately for the individual actuation of each of the two opposite cylinders.

Thanks to such provisions, the opening of working cylinders can be adjusted to a large race for the passage of very thick products different, the holding part of the support piece extending over a height at least equal to the stroke maximum opening to ensure sliding support in any position the working cylinders of the bending cylinders over the entire opening stroke.

So the working cylinder associated with the part of holding the support piece can advantageously be away from the product passage plane to a position maximum lift for which the recesses side of the chocks are entirely clear of corresponding holding parts of the two pieces of support, said working cylinder being removable from the cage by displacement parallel to its axis in said maximum lifting position.

For this purpose, the chocks from the working cylinder can rest on the chocks of the lower working cylinder, for simultaneous removal of the two cylinders by axial sliding, for example, by means of two support pads placed on the side and on the other side of the clamping plane and projecting towards the bottom in the space between the chocks, each chock of the lower working cylinder being provided with two conjugate studs extending upwards. The studs upper and lower are also offset axially relative to each other by a certain distance, in the working position of the cylinders and everyone commits, in this position, to accommodation formed on the opposite side of the other chock to allow the approximation of chocks during adjustment of the opening stroke while in the position maximum opening, said pads are likely to lean on each other after axial shift of one of the cylinders relative to the other by the distance between the studs, to allow simultaneous removal of two cylinders resting on each other.

La figure 1 est une demi-vue de côté d'un laminoir de type quarto, en position de laminage d'un produit mince.

La figure 2 est une demi-vue de côté du même laminoir en position de retrait des cylindres.

La figure 3 est une vue en coupe partielle selon la ligne III-III de la figure 2.

La figure 4 est une vue en coupe par un plan passant par l'axe du cylindre de travail inférieur, selon la ligne IV-IV de la figure 3.

La figure 5 est une vue en coupe par un plan horizontal passant par l'axe du cylindre de travail supérieur, selon la ligne V-V de la figure 1.

La figure 6 est une vue schématique de côté selon la flèche F de la figure 2.

However, the invention will be better understood from the following description of a particular embodiment, given by way of example, and shown in the accompanying drawings.

Figure 1 is a half side view of a quarto type rolling mill, in the rolling position of a thin product.

FIG. 2 is a half side view of the same rolling mill in the position for withdrawing the rolls.

FIG. 3 is a partial sectional view along line III-III of FIG. 2.

FIG. 4 is a view in section through a plane passing through the axis of the lower working cylinder, along the line IV-IV of FIG. 3.

FIG. 5 is a view in section through a horizontal plane passing through the axis of the upper working cylinder, along the line VV of FIG. 1.

FIG. 6 is a schematic side view along the arrow F in FIG. 2.

Figure 1, which is a partial side view, shows the cylinder arrangement of a rolling mill type quarto comprising, inside a cage 1, two working rolls 2, 2 'placed on either side of a horizontal plane P1 of passage of a product to be laminated A and taking support respectively, on the side opposite the product, each on a support cylinder 3, 3 '.

As is well known, each cylinder is provided, at its ends, of journals 21, 31 mounted to rotate, of as shown in Figures 4 and 5, in bearings 22 housed in support chocks, respectively 4, 4 'of the working cylinders 2, 2' and 5, 5 'of the support cylinders 3, 3'. These are mounted sliding inside windows 10 provided respectively in the two uprights 1 of the cage.

Cylinders 12, mechanical or hydraulic, are mounted at the top of the two uprights 1 of the cage and bear, respectively, on the chocks 5 of the upper support cylinder 3, to apply a clamping force which determines the rolling of the product between the working rolls 2, 2 ', the chocks 5' of the lower support cylinder 3 bearing, in the direction opposite, on fixed shims of adjustable height, not shown in Figure 1.

In this way, the lower working cylinder 2 'has a substantially constant level corresponding to the plane of passage of product A, the jacks 12 acting in the two directions on the upper support chocks 5 for adjust the width of the air gap between the cylinders work 2, 2 'depending on the thickness of product A and the desired thickness reduction.

Furthermore, the chocks 4, 4 ′ of the two cylinders are associated with positive camber cylinders 61 placed in hydraulic blocks 6 and susceptible to determine a relative spacing of each pair chocks 4, 4 'for bending the cylinders of work 2, 2 '.

As usual, each hydraulic block is consisting of a support piece 6 fixed on the two sides 11, 11 'of window 10 and in which are formed bores 60 with vertical axis constituting the body of positive cambering cylinders 61. The part also includes supply and return circuits oil, not shown in the figure.

In this exemplary embodiment, the jacks 6 are at single effect, the negative cambering being ensured, so also known, by cylinders 52, 52 'housed in bores 53 arranged in the support chocks 5, 5 'and bearing respectively on chocks 4, 4 'of working cylinders in the negative direction of approximation of said chocks.

The lower working cylinder 2 ', whose level does not vary, generally, only slightly, rose from the usual way, its 4 'chocks having faces side 44 'which can slide along faces of guide 63 provided on the lower part of the parts support 6, 6 'and parallel to the clamping plane P2 passing through the axes of the cylinders.

Below the sliding lateral faces 44 ′, each lower chock 4 'is provided with parts widened 45 'forming support ears which extend below the hydraulic blocks 6 and 6 'and on which are supported, in the direction of the spacing of the plane P1, cylinders 62 for positive cambering of the lower cylinder 2 ', respectively housed at the bottom of each bore 60, opposite cylinders 61.

In a known manner, to achieve positive cambering or negative, we can use either a single cylinder bending in each direction, preferably pairs of two cylinders parallel and symmetrical with respect to the median plane P3 of the bearings as shown in Figures 3, 4, 5.

The level of the lower working cylinder 2 'being substantially constant with respect to the passage plane P1 of the product, the lower cylinders 62 are used only to the camber and must therefore have only the stroke necessary.

On the other hand, according to one of the characteristics essential of the invention, the camber cylinders upper 61 have a very large stroke allowing adapt to a large air gap width, so that the thickness of product A can vary over a large amplitude.

This is why the cylinders 61 for cambering the cylinder upper working 2 are adjustable on a large race, inside the upper part 6b of the support piece 6, and this extends above the plane P1 of the passage of the product over a height at least equal to the adjustment stroke.

Preferably, as shown in the figures, the bore 60 b which constitutes the body of the jack 61 upper camber extends over a longer length large than the top 6b so that in retracted position, the piston 61a of the cylinder 61 is placed at the below the P1 plane, that is to say inside the lower part 6a of the hydraulic block 6, for example substantially at the axis of the working cylinder lower 2 '.

In addition, it is advantageous to communicate the two bores 60a of the lower jack 62 and 60b of the upper cylinder 61 so as to provide space between the pistons 62a and 61a a single chamber 65 into which opens a single oil supply line for exercising equal efforts in opposite directions, on chocks 4, 4 'of the two working cylinders 2, 2'.

Thanks to this arrangement, the rod 61b of the actuator upper arch 61 can have a great length, much greater than the adjustment range of the air gap, and it is perfectly guided at its bottom by piston 61a and at its upper part by a seal annular 64b which seals the end bore 60b.

As we have seen, the guide faces 63 of the 4 'lower working chocks are provided, classic way on the lower parts 6a of the blocks hydraulic 6. On the other hand, the chocks 4 of the cylinder working top 2 are slidably mounted along guide faces 13, 13 ′ formed directly on the lateral sides 11, 11 'of the corresponding window 10 of the amount 1 of the cage.

For this, the upper part 6b of the piece of support 6 used to hold the rod 61b of each cylinder 61 can engage in a recess 41 formed on each lateral side of the chock 4 and extending up to a bottom 42 placed at a certain distance from the face upper 43 of the chock.

In this way, the two lateral faces 44, 44 'of each top chock 4, which slides along the guide faces 13, 13 ′ of the window have each an inverted U shape, open on the plane side passage P1 and comprising a central part 44a (figure 3) extending over the entire width of the chock above from the bottom 42 of the recess 41, and two lateral branches 44b limiting the two sides of the recess 41 and between which engage the upper part 6b of the part support 6 used to hold the rod of each cylinder 61.

Note that the oil pressure required for cambering takes place only in room 65 placed between pistons 61a, 62a, i.e. in the part bottom 6a of the support piece 6.

In this way, the upper part 6b of the same part 6 should only show resistance simply sufficient for sliding support of the rods cylinders 61. Consequently, the width a of the part upper support 6b, depends only on the number and the section of the camber cylinders and the thickness of metal required and can therefore be substantially less than the width b of the chock 4 so that the two branches 44b of the sliding face 44 cover sufficient area to guide pestle it without undue hardship.

The upper part 45 of the chore 4 passing to the above the bottom 42 of the recess 41 therefore constitutes a support lug for positive camber cylinders 61 on which can lean in the opposite direction, the negative cambering cylinders 52 housed in the chock upper support 5.

We can thus adjust with precision and known the position of each working chock 4 in adjusting the pressures in the camber cylinders positive 61 and negative 52, so as to obtain the effect of desired camber for flatness correction.

We see that the provisions which have just been described allow the bending in excellent conditions even for a very large air gap, the rods 61b of the cylinders 61 being perfectly guided by the part 6b of each holding part 6, despite their great length, and the upper chocks can slide without risk of jamming, between the guide faces 13, 13 'of window 10.

It should be noted that normally the width of the recess 41 is a little greater than the width a of the upper part 6b of the hydraulic block 6, so that leave a slight clearance between the side faces of it and the internal faces of the two branches 44b. However, this nesting can usefully be used to keep the working cylinder 2 centered in the clamping plane P2.

According to another important advantage of the invention, the provision which has just been described does not provide any discomfort when removing working cylinders for maintenance or replacement.

Indeed, as shown in Figure 1, the chocks 4 'of the working cylinder 2' are, in service, supported by 52 'camber cylinders negative.

By acting on these, we can known to bring down the lower chocks 4 'which, by means of side rollers 14, come to rest on two horizontal rails 15 extending between the two uprights from the cage. We can thus remove the working cylinder lower 2 'by axial movement by sliding horizontally its chocks 4 'between the faces of guide 63 provided on the lower parts of the blocks hydraulics 6.

To be able to simultaneously withdraw or the replacement of a pair of working cylinders 2, 2 ', superimposed, the rolling mill comprises means 7 for maintenance of the relative spacing of the chocks of the working rolls 2, 2 'in a position of maximum lifting of the upper cylinder 2 for which the chocks 4 of it pass over the parts holding the hydraulic blocks 6b 6.

In the embodiment shown in the figures, each top working chock 4 of the movable cylinder 2 is provided with two pads 70, 70 'placed on either side of the clamping plane P2 and which extend down into the space between the two cylinders, over a distance substantially equal to the half the maximum spacing. Matching studs 71, 71 'placed on the lower working chocks 4 ', extend in the opposite direction, over the distance complementary.

In the working position of the cylinders 2, 2 ', the upper studs 70 and lower studs 71 are offset axially and can penetrate into recesses correspondents 46 ', 46 arranged respectively, in the opposite chocks 4 ', 4. In this way, as shown in the Figure 1, the pads 70, 71 do not interfere, in service, the adjustment of the air gap and the camber of the cylinders in one way or the other.

When you want to remove the working cylinders first go up the upper cylinders 2, 3 in their highest position, by means of the cylinders positive cambering 61 whose stem has a length greater than the adjustment range of the air gap.

In this upper position of withdrawal, shown in Figure 2, the lower ends 44c of the two branches 44b of the sliding face 44 lie slightly above the upper ends of the support piece 6 and of the rods 61b of the jacks 61. The holding part 60b is therefore entirely free from the recess 41 and is not opposed to the axial displacement of the upper cylinder 2.

Note, however, that Figure 2 shows the cylinders in withdrawal position, the camber cylinders upper tucked in and upper chocks 4 bearing on the lower chocks 4 'by through the superimposed studs 70, 71. From preferably, to maintain the two studs one on the other, the lower stud 70 is provided with a stud 72 which enters a corresponding blind hole in the end of the upper stud 70. This is why the cylinders 61 must lift the working cylinder higher 2 to a level slightly higher than the one indicated in figure 2 and for which it is possible to move the lower cylinder axially 2 'by a distance c corresponding to the offset of the studs 70, 71. In this position of the lower cylinder 2 ' each lower stud 71 is exactly in the extension of a corresponding upper stud 70. At medium of the cylinders 61 then slightly lower the chock upper 4 so that the upper studs 70 come rest on the lower studs 71.

The upper camber cylinders 61 can then have returned and we are in the position shown in Figures 2 and 6.

Of course, each chock 4 of the cylinders of upper work 2 is provided with two studs 70, 70 ' placed symmetrically on either side of the plane of P2 clamping and which come to bear on the studs corresponding 71, 71 'of the working chocks 4'.

The upper working cylinder 2 thus rests on the lower working cylinder 2 'and can therefore be removed with it by axial displacement, the assembly resting on the rollers 14 which roll on the rails 15.

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

In particular, in the example shown, the positive camber cylinders are operated in reverse from a single pressure chamber 65 placed between the two pistons 61a, 62a. It would however be possible to place in the bore 60 a partition allowing limit two chambers supplied under pressure different so as to adjust asymmetrically the bending of the two working cylinders 2, 2 '.

On the other hand, the figures show an example of usual embodiment in which two jacks are used placed side by side for positive or negative bending but we could also use more cylinders by increasing the width a of the part of holding 6b or, on the contrary, a single cylinder centered in a median plan of the chock.

The reference signs, inserted after the technical characteristics mentioned in the claims are intended only to facilitate the understanding and limiting them in no way the scope.

Claims (12)

1. A roll mill comprising inside a roll frame fitted with two standards apart (1), at least two working rolls (2, 2') whose axes are substantially parallel, delineating a gap for passing the product to be rolled (A) along a passage plane P1 which is substantially horizontal, whereas the said rolls are mounted to rotate round their axes, each on two chocks (4, 4') arranged respectively in corresponding windows (10) in both standards (1) of the roll frame, where the said chocks (4, 4') are mounted to slide, parallel to a clamping plane P2 substantially going through the axes of the working rolls (2, 2'), each between two plane guiding faces provided respectively, on either side of the said clamping plane P2, on both sides (11, 11') of the corresponding window (10) of the roll frame (1), whereas the roll mill is connected to means for bending at least one working roll, and comprising for each chock (4, 4'), at least two hydraulic jacks (61, 61'), placed respectively on either side of the chock (4), each in a supporting member (6) fixed to the corresponding side (11, 11') of the window (10) and forming a hydraulic block, whereas each jack (61) comprises a body (60) provided in the said supporting member (6) and a piston (61a) with a rod (61b), mounted to slide in the body (60) parallel to the clamping plane and acting on a lateral bearing section (45, 45') of the chock (4, 4'), characterised in that, on each side of the clamping plane P2, the supporting member (6) of at least one bending jack (61) of at least one working roll (2) comprises a part (6b) for maintaining the rod (61b) of the said jack which engages into a corresponding recess (41) provided on the side (44) of the chock (4) of the said working roll (2) down to the bearing section (45) of the said rod and in that the side (44) of the chock is limited on either side of the said recess (41) by two plane sliding faces (44b) capable of sliding along matching guiding faces (13) provided on the corresponding side of the window (10), on either side of the said part (6b) for maintaining the supporting member (6).
2. A roll mill according to claim 1, characterised in that each side (44) of the chock (4) of the working roll (2) connected to the bending jacks (61) is fitted with a U-shaped sliding face which is open towards the passage plane of the product, and which comprises a centre section (44a) extending over the width of the chock (4) at the bearing section (45) and two lateral branches (44b) which delineate the recess (41) into which engages the part (6b) for maintaining the rod (61b) of the jack (61).
3. A roll mill according to one of the claims 1 and 2, characterised in that, as the roll mill comprises a fixed working roll (2') whose level is substantially constant and an adjustable working roll (2) whose level may vary over a certain adjusting height of the gap, the piston (61a) and the rod (61b) of each bending jack (61) of the adjustable roll (2) are mounted to slide in the supporting member (6), over a height which is at least equal to the adjustment amplitude of the gap and whereby the said supporting member (6) comprises a part (6b) for maintaining the sliding motion of the jack rod engaging, onto the adjustment height, into a recess (41) of the chock of the adjustable roll (2) and a part (6a) forming the body of the jack (61), placed at the chock (4') of the fixed roll (2').
4. A roll mill according to claim 3, characterised in that each supporting member (6) of at least one bending roll (61) comprises two parts extending respectively on either side of the passage plane P1 of the product (A), respectively a narrow part (6b) for maintaining the sliding motion of the rod (61b) of the bending jack(s) (61), a section engaging into a recess (41) of the corresponding chock (4) of a first working roll (2) and a wider part (6b) into which has been provided the body of the bending jack(s) (61) and which is limited laterally by a sliding guiding face (63) of the corresponding chock (4') of the second working roll (2'), whereas the latter is connected to bending jacks (62) accommodated in the said wider part (6b) of the supporting member (6).
5. A roll mill according to one of the previous claims, characterised in that both working rolls (2, 2') are connected to positive bending jacks which determine the distance of their chocks (4, 4') and which are arranged in pairs of opposite jacks (61, 62), inside two supporting members (6, 6') placed respectively on either side of the clamping plane P2 substantially going through the axes of the rolls.
6. A roll mill according to claim 5, characterised in that each supporting member (6) is fitted with at least one common bore (60) forming the body of two opposite jacks (61, 62) whose rods (61b, 62b) bear respectively, in opposite directions, on the chocks (4, 4') of both working rolls (2, 2').
7. A roll mill according to claim 6, characterised in that each supporting member (6) comprises a single chamber (65) provided between both pistons (61, 62) of both opposite jacks and oil-supplied for simultaneous actuation of the said jacks (61, 62).
8. A roll mill according to claim 6, characterised in that each common bore (60) is separated by a partition consisting of two chambers which are supplied separately for individual actuation of each of both opposite jacks (61, 62).
9. A roll mill according to one of the previous claims, in which the opening of the working rolls can be adjusted over a long stroke for the passage of products of very different thicknesses, characterised in that the maintaining part (6b) of the supporting member (6) extends over a height at least equal to the maximum opening stroke to ensure sliding support in any position of the working rolls (2, 2') of the bending jack(s) over the whole opening stroke.
10. A roll mill according to one of the previous claims, characterised in that the working roll (2) connected to the part (6b) maintaining the supporting member (6) can be moved away from the passage plane P1 of the product up to a maximum lifting position for which the lateral recesses (41) of the chocks (4) are completely clear of the corresponding maintaining sections (6b) of both supporting members (6, 6'), whereas the said working roll (2) can be withdrawn from the roll frame (1) by moving parallel to its axis in the said maximum lifting position.
11. A roll mill according to claim 10, characterised in that it comprises means (7) for enabling the chocks (4) of the upper working roll (2) to rest on the chocks (4') of the lower working roll (2'), for simultaneous withdrawal of both rolls (2, 2') by an axial sliding motion.
12. A roll mill according to claim 11, characterised in that each chock of the upper working roll (2) is fitted with two supporting studs (70, 70') placed on either side of the clamping plane P2 and protruding downwards in the space between the chocks and in that each chock (4') of the lower working roll (2') is fitted with two matching studs (71, 71') extending upwards, whereas the said upper (70) and lower (70') studs are offset axially in relation to one another by a certain distance (c), in the working position of the rolls, and each engaging, in this position, into a recess (46, 46') provided on the opposite face of the other chock (4, 4') to enable the chocks to come closer to one another when adjusting the opening stroke and that, in the maximum opening position, the said studs are capable of bearing one on top of the other after axial offset of one roll with respect to the other over the distance (c) between the studs (70, 71), to enable simultaneous withdrawal of both rolls, resting one on top of the other.

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