WO1998031489A1

WO1998031489A1 - Roll for a continuous metal rolling or casting plant

Info

Publication number: WO1998031489A1
Application number: PCT/FR1998/000015
Authority: WO
Inventors: François Mazodier; Robert Vatant
Original assignee: Kvaerner Metals Clecim
Priority date: 1997-01-16
Filing date: 1998-01-07
Publication date: 1998-07-23
Also published as: FR2758282A1; CA2249626A1; FR2758282B1; AU5868998A; AU721453B2; EP0898502A1; KR20000064619A; JP2000508588A

Abstract

The invention concerns a roll comprising a hub (2), an external ferrule (3) coaxial with the hub, and, between the hub and the external ferrule, a ductile ferrule (4) comprising a plurality of ring-shaped cells (43) axially juxtaposed and supplied with a pressurised liquid, each cell being delimited by an internal cylindrical wall (41) in contact with the hub and an external cylindrical wall (42) in contact with the external hoop, linked by two lateral ductile walls (44, 44') having, in radial cross section, convex surfaces arranged opposite each other. The invention is applicable to casting rolls of a plant for continuous casting between rolls and to laminating rolls.

Description

Cylinder for a rolling or continuous metal casting installation.

The present invention relates to a cylinder for an installation for rolling or continuously casting metals. More specifically, it relates to a new cylinder structure which can be used both for supporting or working rolls of hot or cold rolling mills, as well as for rolls used in continuous casting installations between rolls of flat metallic products, rolled products or castings which may be ferrous or non-ferrous. Cylinders are already known which are used in such installations comprising a ferrule coaxially surrounding a core or hub, itself possibly mounted on a shaft. Depending on the uses, these cylinders are rotated or simply rotatably mounted in bearings. The mechanical and thermal characteristics of the materials used respectively for the shell and for the core are chosen according to the constraints to which these elements are subjected. The core is conventionally made of steel and essentially has mechanical strength characteristics adapted to withstand the forces generated by the product worked and possibly the rotational drive torque. The ferrule must withstand on the one hand mechanical stresses due to the pressure of the rolled or cast product, and on the other hand, especially for hot rolling working rolls or casting rolls, thermal stresses. It is commonly cooled, either by an external sprinkler, or, in particular for casting rolls, by a circulation of a cooling fluid in channels arranged in the thickness of the shell.

We know that, under the effect of various constraints, the cylinders, and more particularly their ferrules, distort. In rolling installations, it is well known to compensate for deformations, which are essentially bending deformations of the entire cylinder, by adjusting the bending and balancing of the rolling stands.

In continuous casting installations between cylinders, where the deformations of the ferrule are largely of thermal origin, it is already known to link the ferrule to the hub only locally, for example only in an axially middle part of the cylinder, so as to allow a certain freedom of deformation of the ferrule relative to the hub and thus limit the stresses in the ferrule. Furthermore, it is known to adapt the cooling to compensate or at least partially control the deformations of the shell, in order to obtain a desired profile of the outer surface of the shell and thus the desired profile of the cast product.

The present invention aims to provide a cylinder allowing better control of the outer profile of the ferrule, that is to say of the shape of its generator, by acting directly on the ferrule to compensate for the deformations of the cylinder and any geometric defects. of the resulting product, in order to obtain the desired profile for the said product. The invention also aims to limit the effect of local or temporary overpressures which can be caused, in the case of casting between rolls, by variations in the solidification state of the cast strip or other parasitic phenomena which could lead, as is known to do in such circumstances, to vary 1 spacing of the bearings supporting the cylinders to limit these overpressures.

With these objectives in view, the invention relates to a cylinder for a rolling mill or a continuous casting installation between two such cylinders, comprising a hub and an outer ferrule coaxial with the hub, characterized in that it comprises, between the hub and the outer ferrule, a deformable ferrule comprising a plurality of annular cells axially juxtaposed and supplied with a liquid under pressure, each cell being delimited by an inner cylindrical wall in contact with the hub and an outer cylindrical wall in contact with the outer shell, connected by two deformable side walls having, in section along a radial plane, convex faces arranged opposite one another.

As will be better understood later, the pressure exerted in each cell on the convex faces of the side walls tends to straighten them and, by the resulting toggle effect (that is to say the bridging effect of the side walls between the internal and external cylindrical walls), generates at the level of the cell considered a force for separating said cylindrical walls from one another. Due to the rigidity of the hub, the inner cylindrical wall is not likely to deform substantially and said force spacing ¹ therefore results in large radial forces on the outer cylindrical wall, which lead to an increase in its radius , and therefore to the deformation of the outer shell. As will be easily understood, these efforts are all the more important as the convexity of the side walls is low, while of course remaining beyond a practical minimum necessary to avoid reversing the convexity of the walls, this is ie a bulge, under the effect of the internal pressure of the cell.

It will be noted that the radial deformation of the external walls of the cells necessarily leads to a circumferential elongation of these walls. This elongation, as well as the deformation of the side walls of the cells is possible, remaining within the elastic limits of the materials which constitute them, owing to the fact that their amplitudes remain low, the dimensional variations sought to correct the profile of the cylinder in accordance with the aim of the invention being of the order of a micron to a tenth of a millimeter over the radius of the cylinder, which is conventionally of the order of several decimeters.

Those skilled in the art will readily understand that the internal pressure of the cell naturally has a direct effect of spacing the cylindrical walls, due to the force generated by the pressure on said cylindrical walls. However, the radial force on the external cylindrical wall and on the external shell, due to the toggle effect mentioned above, is added to it, and predominantly, as soon as the convexity of the side walls is sufficiently low. and that the width of the cell (in the axial direction of the cylinder) is limited relative to its thickness (in the radial direction). These two aspects also go hand in hand with the fact that, for a given thickness, or height, of the cell, its width can be all the more reduced the lower the convexity. In addition, the smaller the width of each cell, the greater the number of juxtaposed cells can be for a given axial distance, and therefore the greater the effort of spacing the cylindrical walls exerted overall on said axial distance, since the force due to the said toggle effect generated by each cell is multiplied by the number of cells, while the overall force resulting from the pressure exerted directly on the cylindrical walls depends essentially only on the axial length of the zone of cylindrical wall subjected to this pressure and not the number of cells juxtaposed over this length. Furthermore, it will be readily understood that, in addition to the increase in overall effort, the use of a The multiplicity of juxtaposed cells makes it possible, as will be seen more clearly below, to more effectively control the local deformations of the cylinder by independently adjusting the pressure per cell or per group of juxtaposed cells.

To this end, according to a particular arrangement of the invention, all of the cells can be divided into several groups of cells juxtaposed, the cells of the same group being connected and supplied under the same pressure, the supply pressures of two separate groups that can be set independently.

The cells may be distributed over the entire axial length of the outer shell, or alternatively over only part of this length, for example only towards its two ends or, conversely, only in its middle part, in order to be able to act more particularly on the deformation of the outer shell in the corresponding zones, the outer shell can then be secured directly to the hub, in a manner known per se, in the axial zone or zones devoid of cells.

The deformable ferrule may consist of separate cells each having its specific internal and external cylindrical walls, these cells then being juxtaposed by stacking in the axial direction between the external ferrule and the hub. Alternatively, the internal and external cylindrical walls may: respectively be made up of a single piece for a set of juxtaposed cells, on which the side walls of each cell are secured.

Other characteristics and advantages will appear in the description which will be given of a cylinder in accordance with the invention for a continuous casting installation between two cylinders and from some examples of application of the invention to rolling mill rolls. Reference is made to the appended drawings in which:

- Figure 1 is a sectional view along a radial plane of a cylinder according to the invention, for a continuous casting installation between cylinders; - Figures 2 and 3 schematically illustrate two possible applications of a cylinder according to one invention in rolling mill stands;

- Figures 4 and 5 show two alternative embodiments in which the cells are used only over part of the axial length of the shell; FIG. 6 illustrates yet another embodiment in which the deformable shell is formed of a plurality of independent cells juxtaposed axially.

The cylinder shown in Figure 1 is particularly intended for a continuous casting installation between two cylinders, the principle of which is well known. It is simply recalled here that such an installation comprises two cylinders whose walls are energetically cooled by an internal circulation of a cooling liquid. In the casting installation, these cylinders have their parallel axes, located in a horizontal plane, and are rotated in opposite directions. Reference may in particular be made to documents EP-A-0 499 562 and EP-A-0428464 for more information on the arrangement of these cylinders and the known means for cooling their walls.

The cylinder of FIG. 1 comprises a shaft 1, a hub 2, "an outer ferrule 3 and a deformable intermediate ferrule 4, located between the hub 1 and the outer ferrule 3, and coaxially with them.

The outer shell 3, of copper or alloy having good thermal conductivity, comprises a plurality of cooling channels 31, extending in the axial direction and drilled in the thickness of the ferrule. Distribution channels 21 are arranged in the hub 2, to bring a refrigerant liquid into the cooling channels 31, this liquid being supplied there and evacuated by supply channels 22 and return 23 drilled in end rotary joints 24, 25. The embodiment of these various channels together forming a general cooling circuit may be modified without departing from the scope of the invention. Reference may in particular be made to document EP-A-0428464, describing other possible embodiments of the cooling circuit.

The intermediate shell 4 has an internal cylindrical wall 41 in contact with the hub 2 and an external cylindrical wall 42 in contact with the external shell 3.

The internal cylindrical wall 41 is held in an axial position in abutment against a shoulder 26 of the hub, by means of a nut 27.

The internal cylindrical walls 41 and external 42 define therebetween a plurality of annular cells 43 delimited by side walls 44, 44 '. Each cell 43 has the shape of a hollow ring having as its axis the axis of rotation A of the cylinder. Each cell 43 is delimited: - towards the axis of the cylinder, by a portion of the internal cylindrical wall 41,

towards the outside, by a portion of the external cylindrical wall 42,

- And laterally by the side walls 44, 44 '. In section along a radial plane, as can be seen in FIG. 1, the two side walls 44, 44 ′ of any cell 43 are curved with their convex faces arranged opposite one another. Each side wall 44, 44 ′ is secured, for example by welds 45, respectively on the internal cylindrical wall 41, and on the external cylindrical wall 42. The side walls 44, 44 ′ have a small thickness, for example of the order of a few millimeters in order to be able to deform elastically under the effect of an internal pressure applied in each cell. The axial positioning of the outer shell 3 relative to the deformable shell 4 is defined for example by segments 32 placed in a circumferential groove made in the external cylindrical wall 42 and which are pushed during the mounting of the cylinder, by means of rods 33 , in a corresponding groove made in the bore of the outer shell 3. It will easily be understood that in such a case, the outer shell 3 is first placed on the deformable shell 4, then the segments 32 are pushed by the rods 33 , from the inside of the deformable ferrule, to ensure axial locking of the two ferrules one on the other, and only then the assembly of the two ferrules is mounted on the hub 2.

The cells 43 are supplied with pressurized fluid by supply pipes 51, 52, 53 each connected to a source (not shown) of pressurized liquid which is independently adjustable. In the example shown, the pipe 51 directly feeds the first cell, on the left side of FIG. 1, and the three following cells, by the connecting pipes 51 ', which connect two adjacent cells by passing through their respective side walls . Line 52 crosses the first four cells and opens into the fifth, and supplies the following seven cells in series, via the connection lines 52 '. Similarly, the pipe 53 supplies the last four cells, on the right of FIG. 1. It is thus possible to specifically adjust the pressure in each of the groups of cells connected to each other by the intermediate pipes. The various pipes supply cells are preferably formed of metal pipes in rigid tube, welded or brazed on the side walls 44, 44 'at the crossing of these walls, to ensure one seal. They are however sufficiently deformable to accept the deformations of the side walls 44, 44 ′ when the cells are pressurized, these deformations remaining of small amplitude.

It will also be noted that the connection between the cooling channels 31 of the outer shell 3 and the distribution channels 21 of the hub is provided by the spaces 48 located between two adjacent cells of the two groups of cells located towards the axial ends of the cylinders. The respective diameters of the hub 2, of the outer shell 3 and of the deformable shell 4 are determined so as to have an adjustment without play, or even slightly tight, when the cells are not under pressure. In order to facilitate assembly, the compartments between cells can then be pressurized, by means of other pipes which are not shown but which can easily be made by those skilled in the art, so as to slightly reduce the thickness of the deformable shell and thus create a slight radial clearance between the deformable ferrule and the outer ferrule and / or between the deformable ferrule and the hub.

During use, the pressure in each group of cells is adjusted to the desired value so as to create a more or less significant swelling of the cells, that is to say a separation of the two side walls of the same cell, causing a radial deformation of the outer shell. The cell supply pressures may for example be adjusted by servo-valves mounted on the supply lines 51, 52, 53 and controlled by means of measuring the flatness of the cast strip. (such as for example flatness roller or profile gauge) or by sensors measuring the deformations of the outer shell, so as to obtain the required profile of the outer surface of the cylinders, and therefore the desired profile of the strip.

The drawing of FIG. 2 illustrates a first application of a cylinder according to the invention as a rolling cylinder 100 in a rolling mill stand called "duo". One or both cylinders can be produced in accordance with the invention. It will be noted that in the example presented in this figure, a first group of cells is formed by the cells 430 situated towards the two axial ends which are all supplied from a first distribution pipe 510, and a second group is formed by cells 431 located in the axially middle part of the cylinder and supplied from a second pipe 520. This example shows an alternative embodiment of the supply of cells, which is done here by radial channels 511, 521, drilled in the hub and passing through the internal cylindrical wall 410 of the deformable ferrule 400. Each cell is thus supplied by a radial channel 511, 521, all the radial channels supplying the cells of the same group of cells being connected to the same pipe d feed drilled in the hub 200 in an axial direction. A similar embodiment could of course be adapted to the case of the casting cylinder described above.

FIG. 3 illustrates another application of the cylinder according to the invention as a support cylinder 110 in a rolling stand in quarto mounting.

FIG. 4 illustrates another embodiment of a cylinder according to the invention, in which the hub 210 has a median shoulder 211 of diameter substantially equal to the internal diameter of the outer shell 310. The outer shell 310 can be rigidly linked on the said shoulder 211, the cells 430 then being placed only towards the axial ends, on each side of the shoulder.

Unlike the previous example, Figure 5 shows an embodiment in which the hub 220 has a shoulder 221 located towards an axial end of the cylinder and on which directly bears an edge of the ferrule. The axially opposite edge of the ferrule bears on a ring 222 fitted on the hub. The deformable ferrule is located in the axially middle part of the cylinder, between the shoulder 221 and the ring 222. A nut 223 ensures the axial maintenance of the ring 222.

In the variant of FIG. 6, the deformable shell 404 consists of a juxtaposition, in the axial direction, of several independent cells 414, that is to say that in this case, the internal and external cylindrical walls are not not common to several cells as in the examples described above. Each cell 414 here has its own external cylindrical wall 415 and its own internal cylindrical wall 416 which form with the side walls an element, generally toroidal, independent. The deformable ferrule is then formed during assembly by stacking several of these toric elements over all or part of the axial length of the outer ferrule. This variant allows better ease of maintenance of the installation.

The invention is not limited to the embodiments and applications described above only by way of example. In particular, the various embodiments of the cells and their pressure supply means can be combined with one another in the same cylinder.

Claims

1. Cylinder for a rolling mill or a continuous casting installation between two such cylinders, comprising a hub (2) and an outer ferrule (3) coaxial with the hub, characterized in that it comprises, between the hub (2) and the outer ferrule (3), a deformable ferrule (4) comprising a plurality of annular cells (43) axially juxtaposed and supplied with a liquid under pressure, each cell (43) being delimited by an internal cylindrical wall (41) in contact with the hub and an external cylindrical wall (42) in contact with the external shell, connected by two lateral walls (44, 44 ') deformable having, in section along a radial plane, convex faces arranged opposite one of 1' other.

2. Cylinder according to claim 1, characterized in that the set of cells (43) is divided into several groups of cells juxtaposed, the cells of the same group being connected and supplied under the same pressure, the supply pressures two separate groups that can be set independently.

3. Cylinder according to claim 1, characterized in that the cells (43) are distributed over the entire axial length of the outer shell (3).

4. Cylinder according to claim 1, characterized in that the cells (43) are distributed over only part of the axial length of the outer shell (3).

5. Cylinder according to claim 1, characterized in that the deformable shell (4) consists of separate cells (414) each having its specific internal (416) and external (415) cylindrical walls, these cells being juxtaposed by stacking in the axial direction between the outer shell and the hub.

6. Cylinder according to claim 1, characterized in that the internal cylindrical walls (41) and external (42) consist respectively of a single piece for a set of juxtaposed cells, on which the side walls (44, 44 ') of each cell are joined.

7. Cylinder according to claim 1, characterized in that the cells (430, 431) are supplied under pressure by radial channels (511, 521) produced in the hub and passing through the internal cylindrical wall (410) of the deformable ferrule ( 400).

8. Cylinder according to claim 1, characterized in that two adjacent cells (43) of the same group of cells are connected by deformable pipes (51 ', 52') passing through the side walls (44, 44 ') said cells.

9. Cylinder according to claim 1, characterized in that the outer shell (3) has internal cooling channels (31), the supply of these cooling channels being carried out by passages (48) located between two cells (43 ) adjacent.

10. Continuous casting installation between cylinders characterized in that it comprises two cylinders according to any one of claims 1 to 9.

11. Roll stand characterized in that it comprises at least one cylinder according to one of claims 1 to 7.