EP0298852B1 - Method and apparatus for levelling a metal band - Google Patents

Description

The subject of the invention is an installation for leveling a metal strip which can be used especially for obtaining flat products without edge defects, in particular those which are induced by the fact that the properties, in particular mechanical or metallurgical, on a certain width at the edge of the strip, are very markedly different from that of the central part of the strip.

In installations for the production of strip metal products such as rolled thin sheets, the product is subjected, after rolling, galvanizing, tinning or other process, to a certain number of finishing operations, in particular to remove certain defects. In particular, the strip is passed through a leveling cage intended to eliminate warping due to the fact that the metal fibers do not have a regular length over the width of the sheet. For this purpose, the sheet is made to travel on rollers defining a corrugated path and subjecting it to a tension so as to produce elongations by traction-bending.

In general, a leveler therefore consists of a leveling cage disposed between two tension blocks, respectively input and output and within which are mounted a plurality of glider rollers whose axes are arranged one compared to the others staggered on different levels so as to define a wavy path.

The leveling cage can also be associated with other equipment which precedes it and which has a different function such as, for example, a rolling mill cage called "Skin-Pass" performing a low elongation.

By way of example, a common type of leveler is shown diagrammatically in FIG. 1. The leveler conventionally comprises two input and output tensioner blocks 12 between which a leveling cage 10 is disposed.

Each tensioning unit 11 or 12 comprises a number of rollers 13 and 17, intended to keep the strip 3 in tension which is made to run and to impose an elongation thereon by appropriate means. The leveling cage proper 10, disposed between the tensioning blocks is generally made up of two or four active leveling cylinders 2 on which the strip 3 which travels in directions perpendicular to the axes of the cylinders is subjected to deformations of traction-bending in the elastoplastic field.

For this purpose, the active cylinders preferably have a very small diameter in relation to their length and this is why each of the active cylinders 2 is generally placed either on two rollers 21 called intermediate needles which rest on three rows 22 of support rollers, either directly on two rows of support rollers 22, all combinations being possible depending on the specificity of the machine. Special stops are fitted to the ends of the cylinders to enable them to operate in good conditions. The assembly consisting of an active cylinder and its support rollers is called "leveling equipment".

The leveling device (s) may be followed by devices intended to correct a transverse camber of the so-called "tile" strip or a longitudinal camber; the active cylinders of these crews are said to be: anti-tile cylinder 15 and defogger cylinder 16, the latter two functions being sometimes confused.

Deflector rollers 18, the number of which depends on the arrangement of the machine, can be located at different places to force the strip 3 to follow a particular path during its passage through the machine or to perform other functions.

The tangential speed of the rollers 17 of the outlet block 12 is greater than that of the rollers 13 of the inlet block 11 so as to subject the strip to an adjustable tensile force. Furthermore, the positions of the leveling rolls 2, anti-tile 15 and countersink 16 are adjustable in height relative to the mean plane of travel of the strip which thus follows a zig-zag path, the amplitude of which can be adjusted. The strip, which is subjected to a significant tensile force, lengthens during its passage over each active cylinder of small diameter and the height adjustment of the active cylinders makes it possible to modify the deformation force applied to the strip. The latter is thus deformed in the plastic area on each active cylinder whose shape it follows over an angular sector, undergoing an elongation which gives it the form of a developable surface, each of the active cylinders 14, 15 and 16 ensuring its own role.

In such installations, all of the longitudinal fibers are brought to the same length in the plastic field and, for common materials, all flatness defects such as "long edges", "long centered", "pockets" etc. can be corrected.

To improve the flatness correction effect, it has already been proposed to provide thinned portions at the ends of certain cylinders on which the strip passes, the diameter of which gradually decreases relative to that of the central portion of the cylinder so that the distance covered is longer in the central area than at the edges.

By thus making traverse paths of different lengths in the central zone and on the edges of the strip subjected at the same time to a deformation in the elastoplastic field, one increases the elongations on the central zone of the strip during the operation of planing, so that, after leaving the leveler, the fibers all have substantially the same length.

The thinned parts can be arranged at the two ends of the same cylinder, the central part of which, which forms the useful table and normally has a constant diameter, covers the central zone of the strip over a constant width, the zones of the two edges passing over both ends thinned.

As a result, a cylinder of determined profile can only be suitable for leveling strips whose width varies only to a small extent. Each cylinder is therefore assigned a width range and, when a strip of width larger or smaller than the limits is to be treated, it is necessary to change the cylinder to replace it with another whose thinned parts are spaced from each other by the desired distance.

We are thus led to have different planing rollers having central cylindrical parts of different lengths so as to each correspond to a range of width and which we exchange as required, which can have drawbacks due in particular to the time required to this exchange.

To overcome this drawback, it has already been proposed to use cylinders provided with a thinned part at one end, two successive cylinders being provided with thinned parts placed at opposite ends so that one edge of the strip passes over the thinned part of one of the cylinders, the other edge passing over the thinned part of the other cylinder. By moving the two cylinders parallel to their axis and in opposite directions, on either side of the longitudinal median plane of the strip, the spacing of the two thinned parts can be adjusted as a function of the width of the strip. -A-55 122 629, JP-A-55 153622, EP-A-0 199 017).

Such an arrangement, attractive in principle, however poses problems of practical implementation. Indeed, even if such an arrangement makes it possible to adjust the positioning of the thinned parts as a function of the width of the strip, the possibility of easily replacing the working rolls must be retained, for example in the event of wear. However, an intervention on the machine results in a stop or in any case a braking of the production and must therefore be able to be carried out as quickly as possible given the productivity of current installations which make it possible to reach running speeds of the strip of the order of 800 m / min.

On the other hand, the possibility of adjusting the relative sizes of the working rolls must be kept.

This is why it is generally preferred to separate the functions and to provide thinned ends not on the active leveling cylinders but on other cylinders, for example the deflection rollers which are changed less often and whose positions are easier to adjust. axial.

Thus the document JP-A-58 86933, which represents the closest prior art, shows an installation in which rolls for planing and spreading the strip have ends, respectively thinned or widened , and can be adjusted axially.

However, the passage over the thinned parts is more effective when the latter are formed on small diameter cylinders such as active cylinders, on which the strip is subjected to deformation in the plastic field.

However, it then comes up against difficulties in implementation and installation, all the more so since one generally has a reduced space and one is often led to perfect existing installations.

The object of the invention is to solve such a problem by means of special provisions. making it possible to provide thinned parts on the active leveling cylinders themselves, while retaining possibilities for adjusting the latter both in height and in the axial direction, without significantly increasing the size of the leveling cage thus improved.

According to the invention, the thinned parts are therefore formed respectively at opposite ends of two active leveling cylinders and, each active cylinder resting, in a manner known per se, on at least two support rollers, each leveling unit formed by an active cylinder, respectively upper or lower, and the supporting rollers which are associated with it, is mounted on a support, respectively upper or lower, guided in a sliding manner, inside the uprights of the cage frame, according to two orthogonal directions, respectively, a vertical direction and an axial direction parallel to the axes of the cylinders, and that the installation comprises means for controlling, respectively, the axial sliding and the vertical sliding, of each leveling unit with its support at the inside said frame, respectively, for adjusting the level of each active cylinder and for adjusting the axial position of its part thinned.

In a first embodiment of the invention, the support of each leveling unit comprising an asymmetrical cylinder and its support rollers, consists of a chassis forming a cassette mounted to slide in the axial direction on a guided support beam slidingly, vertically, on the uprights of the cage, the means for adjusting the axial position of each cylinder are constituted by jacks bearing in the axial direction, respectively, on the cassette and on the corresponding beam and the level adjustment means of each active cylinder are constituted by jacks bearing in the vertical direction, respectively, on the corresponding beam and on the cage .

But in a preferred embodiment of the invention, the support of each leveling unit comprising an asymmetrical cylinder and its support rollers, consists of a beam, respectively upper or lower, mounted sliding, respectively, in the direction vertical and in the axial direction, on the uprights of the cage, and resting on fixed rails, respectively upper or lower, parallel to the axes of the cylinders, by means of rollers and in a way allowing the displacement of said beam between the amounts of the cage, on the one hand, vertically, under the action of the means for adjusting the level of the corresponding active cylinder and on the other hand, axially, by rolling on said support rails, under the action of the means of adjustment of the axial position of the thinned part of the corresponding active cylinder, said vertical adjustment means bearing on the corresponding beam in a manner allowing dep axial lacing thereof.

In a particularly advantageous manner, the support rollers of the upper beam are mounted in pairs at each end of the beam on arms articulated around horizontal axes and allowing the lowering of the beam with the leveling crew in the working position under the action of jacks and the return of the beam to the high disassembly position.

In addition, each support beam of a leveling equipment with asymmetrical cylinders is associated with an axial adjustment device comprising a centering plate mounted to slide perpendicularly to the beam on a slide mounted sliding on slides extending between the two uprights. of the frame 6 parallel to the beam, the end of the plate being able to engage in a guide groove formed on the beam in a vertical direction.

Thanks to these arrangements and to other characteristics described in detail below, the various members necessary for the height adjustment and the axial adjustment of the active cylinders form a particularly compact assembly which can be housed in a limited space, this characteristic being particularly advantageous in the case of small machines sizes and for adapting existing lines.

Furthermore, it is necessary to treat on planing machines metal strips having not only flatness defects but also different properties on the edges relative to the central part of the strip (for example appreciably different elastic limits ) this is the case, in particular, in so-called "full hard" steels.

With such products having a behavior different from current products it can result on the final product a slight residual edge defect induced by these differences in properties, although all the longitudinal fibers have been brought to the same length in the leveler.

Such faults can also be corrected by virtue of the arrangements according to the invention which make it possible to carry out an axial adjustment of a fairly large amplitude and also to provide thinned parts over a relatively large length at the end of each active cylinder so that each thinned part covers a lateral zone of the strip of width determined according to the defects to be corrected.

It is thus possible to remedy the defects of homogeneity of the strip over its width and particularly to those which may be induced by the existence of properties clearly different from the edges of the strip relative to the central part. The invention also makes it possible to correct a defect induced by such a difference in properties, if necessary on a single edge.

However, the invention can also be useful in the case where the strip before planing has long edges such that it is not possible to correct them entirely. In what follows we will therefore use the term "defect" both for excessive long edges of the strip before planing and for defects induced by different mechanical properties at the edges over a certain width relative to the entire central part of the strip. it being understood that it is the correction of the effects of this latter type of fault which is particularly sought after.

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

Figure 1 is a schematic overview of a conventional leveling installation.

FIG. 2 schematically represents a conventional arrangement of the cylinders of a leveling unit.

FIG. 3 schematically illustrates, in perspective, the principle of the invention.

Figure 4 is a partial view of the end of an active leveling cylinder.

FIG. 5 schematically represents a first embodiment of a leveling cage according to the invention.

Figure 6 shows in more detail another embodiment seen from the operator side for example, with partial sections.

Figure 7 is a cross-sectional view parallel to the axes of the cylinders.

FIG. 8 is a partial top view, according to the arrow F in FIG. 6.

We have already described above, with reference to Figures 1 and 2, the conventional arrangements of a leveling installation.

Figure 3 shows schematically in perspective, the passage of the strip 3 on two cylinders 23, 24 kept centered on their axes by end pieces 27 and defining a wavy path.

Two different active cylinders, respectively 23 and 24, of the cage are provided with an asymmetrical profile, each cylinder being provided with a thinned part 20 at only one of its ends and having a substantially constant diameter on the normal part 26 covering the most of its length, to the other end. The thinned parts 25, 25 ′ are placed respectively at two opposite ends of the two cylinders 23 and 24, on either side of the longitudinal axis 30 of the strip and the two cylinders 23 and 24 can be moved in opposite directions , parallel to their axis along the arrows (f) so as to adjust their axial positions so that each thinned part, respectively, 25, 25 ′ is placed directly above one of the two edges, respectively 31, 31 ′ of the strip 3. As shown in detail in FIG. 4, each thinned part 25, 25 ′ having a length a , it is possible to adjust the positions of the two cylinders axially so that the diameter D of the cylinder decreases progressively from a line placed at a distance L from the edge 31 of the strip 3. The latter therefore comprises two lateral zones 32, 32 ′ of width L and L ′ passing over the thinned parts 25 of the cylinders 23 and 24 and framing a central area 33 passing over the cylindrical parts 26 of the two cylinders and it is possible, by acting individually on each of the cylinders, to adjust the widths, respectively, L and L ′ of the two lateral zones 32, 32 ′.

In FIG. 3, the thinned parts 25 have a conical shape connecting to the cylindrical part 26 by a rounded shape, but a different profile could also be provided, for example parabolic or similar.

FIG. 5 schematically represents, by way of simple example, a first possible embodiment of the invention.

Each leveling cylinder 23, 24 can be placed, with the corresponding equipment, in a chassis 35 forming a cassette mounted to slide axially on a support beam 36 on which is supported a means for controlling the axial movement of the cassette, such as '' a cylinder 37.

At least one of the two beams, respectively upper 36 and lower 36 ′, can be slidably mounted vertically in a frame 38 under the action of jacks 39 making it possible to adjust the height level of the roller and to move the cassettes apart. and on the other side of the plane of the strip 3, in the disassembly and reassembly position.

The invention thus makes it possible not only to adapt exactly to the width of the strip without proceeding with the exchange of the leveling cylinders, but also to adjust the position of each edge of the strip on the thinned part of the corresponding cylinder and by therefore impose a variation in the length of the routes traversed on the lateral zones of the strip with respect to the central part, by adjusting the relative positions of the thinned parts 25 with respect to the longitudinal axis of travel 30.

It should be noted that the axial displacements of the two leveling rollers 23, 24 are not necessarily equal and it is therefore possible, if necessary, to vary the widths L and L ′ of the lateral zones whose path lengths are modified .

Furthermore, one can also act on the profile of the cylinders, for example by modifying the ratio of the respective lengths of the thinned part 25 relative to the cylindrical part 26 or even by giving the rollers a domed shape over their entire length.

It can therefore be seen that it is possible to adapt very flexibly to requirements, in particular to correct defects due to differences in properties in the different zones of the metal strip 3.

In Figures 6, 7, 8, there is shown in more detail, by way of example, a preferred embodiment of the improved installation according to the invention.

The asymmetrical cylinders 23 and 24 are part of two planing equipments 4 and 5 fixed respectively on an upper beam 41 and a lower beam 51 which are slidably mounted transversely to the axis of travel in a frame 6 comprising as seen on the FIG. 6, two uprights 61 inside which windows 62 are provided for the passage of the beams 41 and 51.

In the working position, the two beams 41 and 51 can also slide vertically along guide faces 63 formed on the uprights 61 of the frame 6. Cylinders 64 and 65 control the vertical displacements, respectively, of the upper beam 41 and the lower beam 51. In the example shown, the cylinders 64 and 65 are of the hydraulic and electromechanical type but they could be of any other nature.

The upper beam 41 is carried by rollers 42 which roll on rails 66 extending horizontally to the upper part of the frame 6.

The connection between the beam 41 and the support rails 66 is made so as to allow the vertical sliding of the beam 41 in the working position, under the action of the jacks 64 and its return to the level of the rails 66 in the disassembly position.

For example, the rollers 42 can be mounted on sliding frames or on articulated arms of sufficient length to allow the lowering of the leveling cylinder 24 in the working position shown in dotted lines in FIG. 6.

Such a mobile mounting of the rollers relative to the beam is not essential for the beam 51 which can be simply lifted by mechanical jacks 65, the main role of which is the correct positioning of the beam, the weight of the assembly of the crew ensuring the return to the low position of the beam 51 which comes to rest on horizontal rails 67 by means of rollers allowing the axial movement of the beam 51.

The lower beam can, sometimes, also be actuated by a hydraulic cylinder which is added to the mechanical cylinders 65 to allow rapid opening of the cage from below.

It is thus possible, when the crews 4 and 5 are in the separated position, to proceed, as usual, to the exchange of a crew by rolling each beam 41, 51 horizontally on the rails 66, 67, passing through the windows 62 of the uprights 61 of the frame 6.

The horizontal displacement of each beam 41, 51, to bring it into the working position, can be achieved by a mechanism of the jack, self-propelled trolley, winch, chain, etc. type, not shown in the drawings.

On the other hand, the adjustment of the axial position of each leveling unit relative to the plane of symmetry P is preferably carried out by centering devices 7 mounted next to each beam 41, 51, between the two uprights 61 of the frame 6.

As can be seen in FIG. 8, each centering device 7 is carried by a shank 8 which slides along slides 81 extending between the two uprights 61 of the frame 6 parallel to the axes of the leveling cylinders. A mechanical or hydraulic cylinder 82 resting on one of the uprights 61 makes it possible to adjust the position of the centering device 7 along the corresponding beam 41.

As seen in FIG. 6, a similar device 7 ′ is associated with the lower beam 51.

The centering device 7 (7 ′) comprises a centering plate 71 slidably mounted on the stretcher 8 perpendicular to the slides 81 and to the axes of the cylinders and the end 74 of which can engage in a groove 47 formed on the beam 41 in a vertical direction. The transverse sliding movement of the plate 71 relative to the beam 41 is controlled by a retraction cylinder 72, the body and the rod of which are articulated respectively on the strut 8 and on a hooking lug 73 secured to the centering plate 71.

When each beam 41 (51) is put in place, the corresponding centering plate 71 (71 ′) is retracted by the jack 72 so as not to hinder the passage of the beam (41) (51).

By means of the jack 82, the plate 71 is put in place in front of the corresponding groove 67 and, by means of the jack 72, the plate is engaged in the groove.

The jack 82 then makes it possible, by means of the plate 71, to precisely adjust the axial position of the beam 41 to precisely position the thinned part of the leveling cylinder relative to the edge of the sheet. The strut 8 is then held in this position by the jack 82 and the end 74 of the plate 71 constitutes a guide for the vertical movement of the beam 41 under the action of the jacks 64.

The adjustment of the lower beam 51 is carried out in the same way by the centering device 7 ′.

The arrangements shown in the figures normally allow horizontal adjustment of the two crews only when the cage is in the "open" position, the two upper and lower beams being respectively in the high position and in the low position so that no load is applied to the rods of the jacks.

However, the axial adjustment could also be carried out in the working position by equipping the clamping cylinders with holding devices and / or allowing the beams to slide.

Of course, the invention is not limited to the details of the embodiments which have just been described other equivalent provisions which can be envisaged without departing from the protective framework defined by the claims.

It would be possible, for example, to make a control of the position of the special cylinders as a function of the width of the strip or that of the lateral defects. The displacement of the cylinders as a function of the width of the strip is in principle symmetrical, but the system could also be fitted so as to produce different displacements of the cylinders.

The order in which the two asymmetrical cylinders will be placed will be chosen according to the construction conveniences and the different desired strip trajectories. One can therefore also choose to apply this correction principle to, for example, two cylinders not located on either side of the strip but on the same side with respect to a face of the strip. They may also not necessarily be directly neighboring.

On the other hand, the position adjustment can be done when the belt is engaged or not in the machine, in motion or stopped.

Claims (5)

1. Installation for levelling a metal strip (3) with the production of elongations by traction-deflection, by advance of the strip (3) along a longitudinal axis (30) in a levelling stand (10) associated with means (11) (12) for tensioning the strip (3) and comprising, within a housing (6), a plurality of rolls (2, 15, 16, 18, 23, 24) with axes which are parallel to one another and perpendicular to the direction of advance, respectively at least one pair of levelling rolls (23, 24) and anti-crossbow (15) and anti-camber rolls (16), arranged on different levels, some above and the other beneath the strip (3), so as to define an undulating path, at least two of said rolls (23, 24) each having an asymmetrical profile comprising, at one end, a narrowed section (25, 25') the diameter of which progressively decreases, the two narrowed sections (25, 25') being provided at the opposite ends of said asymmetrical rolls (23, 24) respectively, on either side of the axis (30), said rolls (23, 24) with narrowed ends (25, 25') being displaceable parallel to their axes in opposite directions, so as to adapt the transverse spacing of the narrowed sections (25, 25') to the width of the strip (3);
      characterized in that the narrowed sections (25, 25') are provided at opposite ends respectively of two work levelling rolls (23) (24), and in that each work roll (23, 24) resting in a known way on at least two pressure rolls (21, 22), and each levelling unit (4, 5) formed by an work roll, respectively upper (23) or lower (24) and the pressure rolls (21) (22) associated therewith, is mounted on a support, respectively upper (35) (41) or lower (35') (51), guided, in sliding fashion, inside the uprights (38) (61) of the housing (6) of the levelling stand (10), in two orthogonal directions, respectively, a vertical direction and an axial direction parallel to the axes of the rolls (23, 24), and in that the installation comprises means for commanding, respectively, (37, 37') (7, 7') the axial sliding, and (39, 39') (64, 65) the vertical sliding, of each levelling unit (4, 5) with its support (35, 35') (41, 51) inside the said housing (6), respectively, for the adjustment of the level of each live roll (23, 24) and for the adjustment of the axial position of its narrowed section (25, 25').
2. Levelling installation according to claim 1 characterized in that the support of each levelling unit comprising an asymmetrical roll (23, 24) and its pressure rolls (21, 22), is made up of a chassis forming a cassette (35, 35') mounted so as to be axially slidable on a supporting beam (36, 36') guided in sliding fashion, vertically, on the uprights (61) of the stand (10), and in that the adjustment means of the axial position of each roll (23, 24) are made up of jacks (37, 37') bearing in the axial direction, respectively, on the corresponding cassette (35, 35') and on the beam (36, 36') and in that the means for adjusting the level of each live roll (23, 24) are made up of jacks (39, 39') bearing in the vertical direction, respectively, on the corresponding beam (36, 36') and on the housing (6) of the stand (10).
3. Levelling installation according to claim 1, characterized in that,the support of each levelling unit (4, 5) comprising an asymmetrical roll (23, 24) and its pressure rolls (21, 22), is made up of a beam, respectively upper (41) or lower (51) mounted so as to be able to slide, respectively, in the vertical direction and in the axial direction, on uprights (61) of the stand (10), and resting on fixed rails, respectively upper (66) or lower (67), parallel to the axes of the rolls (23, 24), by the intermediary of rollers (42, 52), and in a way allowing the displacement of the said beam (41, 51) between the uprights (61) of the stand (10), on the one hand, in the vertical direction, under the action of the means (64, 65) for adjusting the level of the corresponding live roll (23, 24) and on the other hand, in the axial direction, by rolling on the said support rails (66, 67), under the action of the means (7, 7') for adjusting the axial position of the narrowed section (25, 25') of the corresponding live roll (23, 24), the said vertical adjustment means (63, 64) each bearing on the corresponding beam (41, 51) in a way allowing the axial displacement of the said beam.
4. Levelling installation according to claim 3, characterized in that the supporting rollers (42) of the upper beam (41) are mounted in pairs at each end of the beam (41) on arms (43) articulated about horizontal axes (44) and enabling the beam (41) with the levelling unit (4, 5) to be lowered into the working position under the action of jacks (64), and the return of the beam (41) into a raised position for disassembly.
5. Levelling installation according to claim 3, characterized in that each supporting beam (41) (51) for a levelling unit (4) (5) with an asymmetrical roll (23) (24) is associated with an axial adjustment device (7) comprising a centering plate (71) mounted so that it can slide perpendicularly to the beam on a carriage (8) mounted so as to slide on slides (81) extending between the two uprights (61) of the housing (6) parallel to the beam (41) (51), it being possible for the end (72) of the plate (71) to engage in a guide groove (47) provided on the beam (41) (51) in a vertical direction.

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