FR2776949A1 - Device for axial support of a roll of a rolling mill - Google Patents

Abstract

Axial support device gives improved regulation of strip thickness. A device for the axial support of a roll in a rolling mill incorporates at least one first stock (4a), mounted to slide in a first column (11a) of the rolling mill cage, connected to the second column (11b) by at least one linking rod (50) extending on at least one side of the roll (3) and having two ends connected by a linking element (51, 52), respectively to at least one side of the first stock (4a) and to the second column (11b) with a possibility of angular play allowing the linking rod (50) to oppose a displacement of the stock (4a) and the roll (3) parallel to the axis of these, without opposing a sliding of the stock (4a) along its guidance faces (14) over the whole of the necessary regulation height.

Description

i The subject of the invention is a device for axially holding a cylinder.

  in a rolling mill, and applies more

  especially for rolling metal strips.

  A rolling mill generally comprises at least two superimposed rolls mounted in a fixed cage and between which the product to be rolled passes, a clamping force being applied between the rolls to carry out rolling. Each cylinder is rotatably mounted around its axis and, generally, provided at its ends with two journals rotating in bearings mounted in a support block

called chock.

  To carry out rolling, it is preferable that the diameter of the working rolls between which the product passes is fairly small, and this is why, most often, these are held by larger diameter support rolls between which is applied the clamping force. For example, in the so-called quarto arrangement, commonly used, the rolling mill comprises two small-diameter working rolls each bearing on a support roll, on the side opposite the air gap for the passage of the product; the axes of the cylinders are placed

  substantially in the same vertical clamping plane.

  The spacing of the rolls obviously depends on the thickness of the product to be laminated and the reduction in thickness to be carried out during a pass and this is why it is necessary to adjust the relative levels.

  cylinders relative to each other.

  For this purpose, the chocks of the cylinders are threaded in two windows provided respectively on the two columns of the cage and each provided with two guide faces parallel to the clamping plane, along which can slide corresponding flat faces, formed on the two sides of the chock. The adjustment height depends on the maximum spacing of the cylinders which corresponds to the maximum thickness of the product to be laminated plus the clearances to be left between the cylinders to allow their disassembly. It is necessary to leave a minimum clearance between the lateral faces of a chock and the corresponding guide faces of the window and it is therefore not possible to guarantee perfect perpendicularity of the axis of the working rolls with respect to the direction of travel of the strip to be laminated. This results in the appearance of axial thrust forces between the cylinders which tend to move.

  parallel to themselves. It is therefore necessary to maintain each cylinder axially to prevent it from tending to come out of the cage.

  To this end, at least one of the chocks of the cylinder to be maintained is provided, on its sides with two projecting parts forming ears perpendicular to the axis which partially cover the two uprights of the column framing the chock and engage each in a hooking portion in the form of a yoke having a first branch constituted by the upright itself of the column and a second branch constituted by a clamp fixed on the upright in a removable manner. Thus, when the cylinder is subjected to axial thrust forces, the chock is held in position by its ears which each bear in one direction on the column itself and in the other direction on the clamp. The two clamps can be disassembled or separated to allow disassembly of the cylinder with these chocks. Of course the withdrawal of the cylinder is carried out on the side opposite to the column since, in the other direction, the ears are blocked by the column. As is known, the rolling mill rolls must normally be rotated by a drive group placed on one side of the cage called "drive side", the other side called "operator" remaining free to allow movement along the cage, in particular to approach the latter, a device for dismantling the cylinders which must, periodically be replaced and can be removed from the cage by passing through the window of the column placed on the operator side. The clamping devices are therefore disposed, generally, on the column of the cage and the chock of each cylinder to be maintained placed on the operator side. It is sufficient, in fact, to maintain the cylinder by one of its chocks when these are equipped with bearings which axially secure the cylinder with its chocks. But it is also possible to place clamp devices on the two columns of the cage to block the two chocks, for example, when bearings are used, in particular with oil film, not ensuring the axial connection. Of course, the clamps must not oppose the sliding movements of the chocks for adjusting the level of the cylinders. The axial retaining lug must therefore also slide, with minimal play, inside the yoke formed by the upright of the column and the clamp. However, the axial thrust exerted on the cylinder, in one direction or the other, generates a friction force between each ear of the chock and the column

  of the cage or the clamp, depending on the direction of the push.

  However, it is necessary, during rolling, to ensure thickness regulation by slightly modifying the relative levels of the working rolls. This adjustment is carried out, normally, for all the cylinders by the clamping cylinders which are controlled, for this purpose, by

  a thickness control system.

  When each cylinder is held axially by clamps, the regulation system may be disturbed by the friction which occurs between the ears of the chock and the column or the clamp, depending on the direction of the axial thrust, and which create a relatively large hysteresis effect.35 For example, for a rolling force of 2,000 tonnes, the frictional force resulting from the axial thrust may be 20 tonnes. The clamping device, by

  hydraulic example, must therefore overcome this force before being able to cause the movement of the chock necessary for the thickness regulation during rolling. However, we know5 that the clamping force applied to the cage determines a certain yielding of the latter.

  For example, in a cold rolling mill, a value of the order of 500 T per millimeter of yield is assumed. Under these conditions, the need to overcome a friction force of 20 tonnes represents a hysteresis of 40 microns on the thickness regulation, which is not negligible, given the precision that it is necessary to achieve in modern facilities. The subject of the invention is therefore a new device for axially holding the rolls in a rolling mill making it possible to avoid or, in any case, to considerably reduce the friction due to axial thrusts and, consequently,

  improve thickness regulation.

  To solve this problem, in accordance with the invention, at least one first chock of the cylinder, slidably mounted in a first column, is connected to the second column by at least one connecting rod extending on at least one side of the cylinder and having two ends each connected by a connecting member, respectively, to said first chock and to the second column with a possibility of angular play allowing said connecting rod to oppose a displacement of the chock and of the cylinder parallel to the axis thereof, without opposing the sliding of the chock along its faces

  guide, over the entire required adjustment height.

  In addition, at least the connecting member of the connecting rod with the chock is removable so as to release the chock

for dismantling the cylinder.

  For example, this removable connecting member of the connecting rod with the chock can advantageously comprise a yoke mounted at the corresponding end of the connecting rod and having two branches between which extends a rod substantially parallel to the guide faces of the window and capable of engaging in a removable manner in a fastening piece carried by the chock and limiting a hole for passage of the rod. In a particularly advantageous manner, the orifice for passage of the rod has a tightened central part, placed in a substantially horizontal plane and of diameter substantially equal to that of the rod and two parts which widen, respectively upwards and towards the bottom from the central part, to allow changes of orientation of the rod when adjusting the height of the chock. Preferably, the attachment part of the chock has the shape of a hook having a slit open towards the outside and centered in a plane substantially perpendicular to the axis of the cylinder, to allow the engagement of the rod in the hook by rotation of the connecting rod around its connecting member on the second column. This rotation of the connecting rod for engagement or disengagement of the connecting rod can advantageously be controlled by a jack having an element articulated on the rod and another element articulated on the first column at a point spaced from the face of

chock guide.

  According to another advantageous characteristic, the connecting rod is connected to the second column by a swiveling connection around at least two axes, respectively vertical for the orientation of the connecting rod between an engagement position on the chock and a released position, and

  horizontal for level adjustment of the cylinder.

  Preferably, the connecting members of the connecting rod can be equipped with friction linings substantially

  null, of the type known under the brand TEFLON.

  To ensure that the cylinder remains in position, even in the event of significant axial thrust forces, it is preferable to use two connecting rods placed respectively on each side of the cylinder and provided with removable connecting members, each with the one of the two

sides of the chock.

  Furthermore, the rolling mill comprising a drive side on which are placed control means and an operator side, it is preferable that the connecting rod is connected, at one end, to the chock placed on the operator side and, at the other end, to the column placed

on the drive side.

  Generally, it will be sufficient to maintain each support cylinder with a single chock. However, in the case where the bearing interposed between the chock and the journal of the cylinder cannot correctly ensure the axial securing, in both directions, of the cylinder and its two chocks, the latter can be maintained, each, by at

  minus a connecting rod connected to the opposite column.

  In the case where the rolling mill must allow level variations of fairly large amplitude of the rolls to ensure a wide range of adjustment of the opening, the chock to be maintained can advantageously be provided with several attachment pieces placed at several levels superimposed, each attachment piece being placed at an average level on either side of which the connecting rod allows variations in cylinder level over the height necessary for

thickness regulation.

  In this case, the connecting rod remains articulated at the same point on the opposite column and engages on the attachment piece which, after adjusting the opening of the cylinders, is placed at the level of the connecting rod. The actuator for controlling the rotation of the connecting rod therefore also remains attached to the column. But the invention will be better understood by the

  following description of a particular embodiment,

  given as an example and shown in the drawings

attached.

  Figure 1 is a schematic overview, in

  elevation, of a rolling mill stand.

  Figure 2 is a partial side view of the

  cylinder holding device.

  Figure 3 is a top view of the device. Figures 4 and 5 are detail views showing

  two positions of the holding device.

  In Figure 1, there is shown, in elevation, a rolling mill comprising a cage 1 having two spaced apart columns 11a, 11b between which are placed four rolls, respectively two working rolls 2, 2 'and two

support cylinders 3, 3 '.

  Each support cylinder 3 is provided, at its two ends, with two pins 31 which rotate in bearings 32 housed in chocks 4a, 4b. These are threaded into windows 12a, 12b provided respectively

  on the two columns lla, llb of cage 1.

  As shown in Figure 3 which is a horizontal sectional view, each column 11a, 11b thus consists of two uprights 13 framing the window 12 and along which are provided guide faces 14 parallel to the plane

  vertical clamping P passing through the axes of the cylinders.

  Each chock 4 is thus guided by two lateral flat faces 41 along the guide faces 14 of the window and can slide vertically, in particular under the action of clamping means constituted by screws or hydraulic jacks 15a, 15b mounted on each column 11a, 11b of the cage, at the upper part thereof and bearing on the chocks 4a, 4b of the upper support cylinder 3. It is thus possible to exert a clamping force between the cylinders, chocks 4 ' a, 4'b of the lower support cylinder 3 'being kept at a constant level

  by wedges 16 placed at the base of the columns 11a, 11b.

  In FIG. 1, the cylinders have been shown in the maximum clamping position, but the upper support cylinder 3 can be raised to determine the thickness of the air gap between the working cylinders 2, 2 '. As indicated, a regulation system makes it possible to act, at each rolling pass, on the clamping means 15a, 15b to ensure the thickness adjustment and the result is that the chocks 4a, 4b can move the

  along the guide faces 14, over an adjustment height.

  According to the invention, each support cylinder 3, 3 'is associated with at least one axial holding device 5 which is

  shown in detail in Figures 2 and 3.

  In FIG. 2 which is a partial view, in elevation, of the upper support cylinder 3, it can be seen that the axial holding device 5 comprises at least one connecting rod provided at its two ends with articulated connecting members, respectively 51 with one of the chocks 4a, and 52

  with column llb placed on the side opposite this chock.

  In the example shown, the connecting rod 50 is connected with the chock 4a placed on the operator side and with the column 11b placed on the drive side. This allows the operator in particular to easily check the engagement of the device on the chock and to intervene if necessary, but a reverse arrangement is possible. Similarly, as shown in FIG. 3, the cylinder 3 can be associated with two connecting rods 50, 50 ′, placed respectively on each side of the cylinder and each connected

  to one of the sides of the chock 4a and to the upright 13, 13 ′ placed on the same side on the opposite column 11b.

  The two connecting members 51, 52 can pivot slightly, respectively with respect to the chock 4a and to the column 11b, so as to allow a slight angular offset of the connecting rod 50 when the chock 4a moves vertically over a certain height for adjusting the air gap, at least sufficient for thickness regulation. On the other hand, the connecting member 52 of the connecting rod 50 with the column llb can pivot around a vertical axis, between a spaced apart position of the cylinder and a position

  of engagement of the connecting member 51 on the chock 4a.

  To this end, as shown in Figure 2, the connecting member 51 consists essentially of a yoke-shaped body, fixed on the end of the connecting rod 50 and having two spaced apart branches between which extends a rod 53 with a substantially vertical axis. The rod 53 engages in an orifice formed in an attachment part 6 which is fixed to the chock 4 and has, in the example shown, a fork shape limiting a slot 61 placed on a circle centered on the point d 52 of the connecting rod 50 on

  column 11b and in which the rod 53 is placed.

  In this way, as shown in Figures 4 and 5, the rod 53 can be removably engaged in the slot 61 by rotation of the connecting rod 50 around the connecting member 52, under the action of a hydraulic cylinder 7 comprising a piston linked to a rod articulated on the end of the connecting rod 50 or else, directly, on the connecting member 51 and a cylinder body articulated on the upright 13 of the column lla, at a point spaced from the '' chocks, so that the cylinder is substantially

perpendicular to the connecting rod 50.

  To allow the orientation of the connecting rod 50 under the action of the jack 62, the member 52 for connecting the latter with the second column 11b is articulated around a vertical axis. On the other hand, to allow the height adjustments of the chock 4a, the connecting member 52 must also allow a slight rotation about a horizontal axis. Therefore, the link member 52 will

  preferably made up of a ball joint.

  Similarly, the connection 51 between the connecting rod 50 and the chock 4 must have a possibility of tilting relative to the horizontal. Advantageously, the slot 61 of the hook 6 has a narrowed central part 62 of diameter substantially equal to that of the rod 53 and two flared parts, respectively upwards 63 and downwards 63 'which are limited by convex faces, so as to

  allow a kind of rolling of the rod 53 on the slot 61 when the connecting rod 50 is oriented following the vertical movements of the chock.

  Thus, the rod 53 mounted on the connecting member 51 ensures the centering, practically without play, of the chock 4 in a plane Pl perpendicular to the axis of the cylinder, without interfering with the height adjustments thereof in the purpose of varying the width of the air gap and ensuring the

thickness regulation.

  Indeed, the rolling mill is provided for a maximum opening corresponding to the initial thickness of the product and the air gap must be adjusted, at each pass, to allow the engagement of the product coming from the previous pass and

  to carry out the desired thickness reduction.

  Given the spacing between the two columns 11a, 11b, which determines the maximum width of the rolled product, the length of the connecting rod 50 will generally be such that, for the usual openings, the angular offset of the connecting rod resulting from the adjustment in height of the cylinder will not exceed 1.50 to 2 on either side of an average level. The variation in distance between the two

  articulated connections is therefore negligible.

  Consequently, thanks to the arrangement according to the invention, the connecting rod 50 maintains the median plane P1 of the chock 4a in a constant position relative to the column 11a, and ensures, in service, the axial maintenance of the cylinder 3 , without generating friction likely to

  disturb the thickness regulation by hysteresis effect.

  On the other hand, the connecting member 51 can be entirely disengaged from the attachment piece 6 by a rotation of the connecting rod 50 around the ball joint 52, controlled by the jack 7. The chock 4a can then be moved freely, d '' on the one hand vertically to place the cylinder 3 in a disassembly position and on the other hand, horizontally, to remove the cylinder 3 from the cage or put it back in position

by axial displacement.

  Of course, to allow disassembly, the attachment piece 6 must not protrude over the width of the chock 4, its external face being in the extension of the face of

  slip 12, as shown in Figures 4 and 5.

  To ensure the positioning of the cylinder in the cage during reassembly, the connecting member 51 may advantageously be provided with a lug 54 provided with a face 54 'substantially perpendicular to the axis 30 of the cylinder and against which a face abuts conjugate 64 of the

  attachment piece 6 of the chock 4 (Figure 4).

  The device according to the invention, which has only been shown diagrammatically in the figures, can be produced easily. The connecting rod 50 may consist of a simple tube of desired length provided, at its ends, with threaded bores into which are threaded studs 55, 55 ′, secured, respectively, to the

link 51, 52.

  Furthermore, such a holding device is relatively compact since the connecting rod 50 and its connecting members may have reduced dimensions, the axial displacement forces applied to the cylinders being limited. Of course, the invention is not limited to the details of the embodiment which has just been described by way of simple example and which could be subject to variants without departing from the protective framework defined by

the revendications.

  For example, when the axial displacement forces which can be applied to the cylinder are relatively low, it may be sufficient to maintain the chock on one side only. It is preferable, however, to use two holding devices placed respectively on either side of the clamping plane to

avoid the risk of limping.

  In addition, an installation has been described comprising an axial holding device comprising two connecting rods engaging in a removable manner on the two sides of a single chock 4a of a support cylinder placed on the operator side, that is to say on the left in the figure and connected by the connecting rod to the opposite column 11b placed on the drive side. Such an arrangement is sufficient to ensure the axial maintenance of the cylinder if the chocks are provided with bearings constituting axial stops, for example bearings with tapered bearings, each chock being integral

axially of the cylinder.

  However, if oil film bearings are used allowing a certain displacement of the journal relative to the chock, it may be preferable to use, for each cylinder, two holding devices each engaging on the one of the two chocks and connected,

  by at least one connecting rod, to the column placed on the opposite side.

  Furthermore, the arrangements described for making the connecting members, in particular with the clearances necessary to allow the orientation of the connecting rod, could be modified. For example, the ball joint 52 could be replaced by a joint with two axes, respectively a vertical axis allowing the rotation of the connecting rod 50 between its separated position and its engaged position and a horizontal axis allowing the angular offset of the resulting connecting rod level variations of the

cylinder 3.

  In this regard, as indicated, the arrangements shown allow a generally sufficient level adjustment amplitude, for example of the order of 50 mm on either side of an average position. If it is necessary to admit larger amplitudes, for example for a rolling mill a very large opening allowing a significant variation in the thickness of the product to be laminated, one could consider equipping the chock 4a, on each side, several fastening pieces 6 placed on several superimposed levels so as to cover the wide desired adjustment range. The two connecting rods 50, 50 'can remain fixed at the same level on the opposite column 11b, as can the control jacks 7, 7' on the column 11a. After adjusting the opening of the cylinders, the connecting rod 50 is hooked, by its connecting member 51, on the attachment piece placed substantially at the same level, with a possibility of orientation allowing a limited level variation of the

  cylinder for thickness regulation.

  On the other hand, the invention has been described in its application to a support cylinder but each cylinder of the rolling mill could be associated with a holding device

axial with one or two connecting rods.

  The reference signs inserted after the technical characteristics mentioned in the

  claims are intended only to facilitate the

  understanding of them and in no way limit them

the scope.

Claims (12)

  1. Device for axially holding a cylinder in a rolling mill comprising at least two superimposed rolls (2, 3) mounted in a fixed cage (1) having two spaced apart columns (11), the cylinder to be held (3) being rotatably mounted around its axis, on two chocks (4) threaded respectively in windows provided on the two columns (11) of the cage (1), and mounted sliding, each between two parallel guide faces (14) formed on the sides of the corresponding window (12), on a height for adjusting the level of the cylinder (3), characterized in that at least one first chock (4a), slidably mounted in a first column (11a), is connected to the second column (11b) by at least one connecting rod (50) extending over at least one side of the cylinder (3) and having two ends each connected by a connecting member (51, 52), respectively to at least one side of the first chock (4a) and to the second column (11b) av ec a possibility of angular play allowing said connecting rod (50) to oppose a movement of the chock (4a) and the cylinder (3) parallel to the axis thereof, without opposing the sliding of the chock (4a) along its guide faces (14), over the entire height necessary adjustment.   2. Holding device according to claim 1, characterized in that at least the connecting member (51) of the connecting rod (50) with the chock (4a) is removable so as to release the chock (4a ) to allow disassembly of the cylinder. 3. Holding device according to claim 2, characterized in that the removable member (51) connecting the connecting rod (50) with the chock (4a) comprises a yoke (51) mounted at the corresponding end of the connecting rod (50) and having two branches between which extends a rod (13) substantially parallel to the guide faces of the window and capable of engaging in a removable manner in a fastener (6) carried by the chock (4a) limiting an orifice (61) in which the rod (53) can engage. 4. Holding device according to claim 3, characterized in that the orifice (61) for engaging the rod (53) has a tightened central portion (62), placed in a substantially horizontal plane and of substantially equal diameter to that of the rod (53), and two parts (63, 63 ') which widen, respectively, upwards and downwards from the central part (62), to allow the changes of orientation of the connecting rod (50) and the rod (53) when adjusting the height of the chock (4a). 5. Holding device according to one of   Claims 3 and 4, characterized in that the part   of attachment (6) of the chock (4a) in the form of a hook having a slot (61) open to the outside and centered in a plane substantially perpendicular to the axis of the cylinder to allow the engagement of the rod (53) in the hook (6, 61) by rotation of the connecting rod (50) around its member   link (52) on the second column (11b).   6. Holding device according to claim 5, characterized in that the rotation of the connecting rod (50) is controlled by a jack (7) having an articulated element (71) on the connecting rod (50) and an element (72) articulated on the   first column (11a), at a point spaced from the guide face (41) of the chock (4).   7. Holding device according to one of   previous claims, characterized in that the   connecting rod (50) is connected to the second column (11b) by a connecting member (52) capable of pivoting around at least two axes, respectively vertical for orientation   of the connecting rod (50) between an engagement position on the chock (4a) and a disengaged position, and horizontal to allow the level adjustments of the cylinder (3) .35 8. Holding device according to one of the preceding claims, characterized in that,   for each cylinder to be maintained, the cage (1) is equipped with   two connecting rods (50, 50 ') placed on each side of the cylinder and connected respectively to the two sides of a chock (4a) of the cylinder (3) and to the two uprights of the opposite column (llb) 5.   9. Holding device according to one of   previous claims, characterized in that the   connecting members (51, 52) of the connecting rod (50) are equipped with substantially zero friction linings, of the known type under the brand Teflon.   10. Holding device according to one of   previous claims, characterized in that   the chock to be maintained (4a) is provided with several connecting pieces for the connecting rod, placed at several superposed levels, so as to cover a wide range of adjustment of the opening of the cylinders, each fastening piece being placed , after adjusting the opening of the cylinders, at an average level on either side of which the connecting rod (50) allows variations in the level of the cylinder (3) at least on the   height required for thickness regulation.   11. Holding device according to one of   previous claims, in a rolling mill (1) associated with   cylinder drive means placed on one side of the cage, characterized in that the chock (40) held by the connecting rod (50) is placed on the operator side, opposite the drive, the rod ( 50) being connected by its opposite end to the column (11b) placed on the drive side.   12. Holding device according to one of   previous claims, characterized in that the   two chocks (4a, 4b) of the same cylinder (3) are connected, each by a connecting rod, to the column (llb, lia) opposite the pate considered.