In recent years, the manufacturers of steel strips have been looking for a way of hot-rolling extremely thin strips down to a thickness of 0.7 mm, with the aim of reducing or avoiding costly cold-rolling operations. With the development of new casting and rolling processes, this aim has become feasible, although technical problems have arisen at the end of the rolling train with regard to the winding-up of very thin strips.

At the same time another requirement which has arisen is that of maintaining constant temperature conditions on successive hot-rolled strips, in particular on the wound coils after the last rolling pass and/or after they have passed through a cooling section.

In order to wind up the strips, in continuous processes coilers of the carousel type are often used; this type of coiler may be controlled with a high degree of operational reliability. In fact, the introduction of the leading ends of the strips onto the winding spindles may be achieved without problems and the winding operations start in the same position for all of the strips; then, during the winding step, the coiler and the coil are transferred from the initial winding position into the coil unloading position.

Carousel coilers, however, have a complex, complicated and unfavourable design with regard to repairs, in particular since stoppage of a coiler of this type due to any cause results in stoppage of the entire rolling train.

In plants with a high production output, in order to achieve a high capacity, arrangements involving a large number of coilers which can be used in an interchangeable manner are adopted; in particular, in plants of the endless or semi- endless type with high rolling speeds (up to 20 m/s), the time interval which lapses between two successive strips is minimal.

The traditional arrangement in which two winding coilers are located underneath the rolling plane and operate alternately as-well as in succession at a distance of about 8-9 m is correct from the point of view of installation of the plant, but does not allow winding of two or more consecutive strips under constant temperature conditions. This is due above all to the unfavourable cooling conditions for very thin strip, whereby the lack of uniformity in temperature between strips which are wound in different positions increases as the strip thickness decreases.

The different temperature at the coiler which is a consequence of this arrangement results in different qualities of strip in the case where the strips follow one another directly during endless or semi-endless rolling. This fact in particular is critical in the case of rolled carbon steels in the ferritic range where the temperature at the coiler greatly influences the material properties of the cooled strip.

The problem may be overcome in the case of the coilers of the carousel type, as described in the introduction, which are able to wind two strips directly in succession into the same position. The disadvantage of this configuration, however, is that the availability of the entire plant is greatly dependent on that of the coiler.

By overcoming the problems described and the disadvantages of the state of the art, the object of the invention is that of creating an arrangement of coilers which can be used independently of one another for the winding of thin strip, in particular a strip obtained from thin cast slabs, whereby the strips rolled at high speed may be wound onto different spindles of the coilers and where, for metallurgical and physical reasons, the winding temperature on all the spindles of the coilers used has the same values.

In order to achieve this object, the invention proposes that at least two coilers should be provided, separate from one another, said coilers being able to be operated in an interchangeable manner for winding of strips and positioned so that the associated spindles are situated substantially at the same distance from a reference point located along the travel path of the strip.

As will emerge more clearly below, this distance may be calculated as the distance between the plan-view projection of the reference position and that of the coilers or on the basis of the length of the path followed by the strip. between the reference point and the coilers.

Advantageously the reference point may consist of the strip cooling section, in the case where one is present in the plant, or the last rolling stand; in fact, if the coilers are arranged at the same distances from the cooling section or from the last rolling stand, it is ensured that the each coil or reel of strip material is wound at the same temperatures.

This is extremely important for very thin strips since cooling thereof as a result of convection or irradiation is mainly dependent upon the spatial distance which the strip has yet to cover from the exit point of the rolling train or from that of the cooling section to the coiler.

With the same distances between the cooling section and the coiler or between the latter and the last rolling stand, the same conditions may be created so that winding of the strips is performed at a predefined temperature when the strips which follow each other are wound onto different spindles.

In a particularly advantageous embodiment of the invention it is envisaged that one coiler is located underneath the rolling plane and another coiler above this plane. In the case of an arrangement involving two coilers they are positioned above one another, i. e. the first one above and the second one underneath the plane of the rollerway on which the strip is guided.

In the case of three coilers, the third coiler is aligned with the rollerway; more generally, should the number of coilers be greater than two, they are arranged preferably in a symmetrical manner with respect to the plane along which the continuous strip advances and in the case of an odd number one of them is positioned along an extension of this plane.

Under such conditions the distance of the various coilers from the abovementioned reference point will be calculated on the basis of the length of the strip section between the reference point and the coiler.

In accordance with the invention it is advantageous if the coilers rotate in an opposite manner with respect to each other, i. e. if they are made to rotate in opposite directions (clockwise and anti-clockwise). This allows verification of both the upper side of the strip and the bottom side, because in one coil its bottom side is situated on the outside of the winding spiral, while in the next coil it is situated on the inside and vice versa for the upper side.

Preferably, moreover, each coiler is provided with its own truck for transportation of the wound coils, which is moved underneath or above the coiler on an associated guide track arranged transversely with respect to the coiler.

The availability of the coilers is in this way clearly increased since they are used independently of one another and transportation of the wound coils may be performed during winding of a new coil.

In order to achieve better movement of the thin strips, devices or units for driving the strip are provided between the cooling section or the last rolling stand and the winding coilers; each of these units is composed of two rollers which act on the two surfaces of the strip.

High-speed shears for dividing up the continuous strip into sections of predetermined length are provided between these drive units and the rolling mill (semi-endless operation).

Positioning of the high-speed shears in front of the coilers is particularly recommended in the case of endless or semi-endless processes since the shears separate the front end of the advancing continuous strip from the tail end of a strip cut beforehand and already wound downstream thereof ; the front end of the continuous strip being supplied must then be wound onto a coiler which is different from that on which the previous coil was completed.

The distribution of the strips downstream of the shears towards the different coilers is performed by an apparatus according to the invention, the characteristic features of which are described in the claims accompanying this description.

The invention in its entirety, together with its characteristic features and the advantages arising therefrom, will be understood more clearly in the light of the explanation which follows of a preferred and non-exclusive example of embodiment thereof, illustrated schematically in the accompanying drawings, in which: Fig. 1 shows a simplified illustration of a rolling plant according to the invention; Fig. 2 shows the arrangement of coilers according to the invention during winding of a strip onto the upper coiler; Fig. 3 shows the arrangement of coilers according to the invention during winding of a strip onto the lower coiler; Figs. 4 and 5 show in detail some features of an apparatus for distribution of the strips according to the invention, in respective operating conditions.

In the Figures mentioned above, 1 denotes a finishing train of a thin-slab casting and rolling plant through which a thin rolled hot strip 2 passes before reaching a cooling section 3.

Upon leaving the latter the strip 2, which is continuous, i. e. not yet cut into sections of given length, is conveyed along a rollerway 10 by means of a first drive unit 5, which is known per se, as far as high-speed shears 7; downstream of the shears 7 the strip 2 which is cut, and therefore no longer continuous, is distributed to two winding coilers 8a, 8b, one of which is located above and the other below the horizontal rolling plane of the strip 2.

Each coiler 8a, 8b comprises a respective spindle 11,12 onto which the strip is wound as a result of the action of a series of pressure rollers 9, in a known manner.

The distribution of the cut strip by the shears 7 to the upper and lower coilers 8a, 8b is performed by means of an apparatus which also comprises a second drive unit 6 which will be considered in more detail below.

Upon leaving the cooling section 3, the strip, which is still continuous, passes through a section indicated by 4 until it reaches the coilers 8.

According to the invention, in order to obtain temperatures at the coiler which are substantially the same during winding, the distances of both the coilers 8a, 8b from a reference point situated along the rolling plant must be the same; in the example of the rolling plant illustrated here, this reference point may consist of the cooling section 3 and its distance from the coilers is indicated by the segments "a"in Fig. 1. This distance therefore in practice is-equivalent to the distance between the plan-view projections of the reference point and the coilers.

However, should there be no cooling section in the rolling plant, the last strip rolling stand may be taken as the reference point.

It must also be pointed out that, in the case of three or more coilers, it is no longer convenient to measure the distance of said coilers from the aforementioned reference point in terms of the plan-view projection because this could result in the risk of errors; under such circumstances it is more appropriate to measure this distance on the basis of the length of the length of the path followed by the strip and extending between the reference point and each coiler. It is in fact obvious that the distance thus measured may differ considerably from one coiler to another in the case where they are aligned along the same vertical, in order to obtain the same distance calculated in a plan-view direction from the reference point considered.

Owing to the same conditions mentioned according to the invention, the same temperature conditions are in fact created for each wound coil.

The abovementioned apparatus for distribution of the cut strips towards the winding coilers is now described on the basis of Figures 2 to 5.

In Figures 2 and 3 the arrangement of coilers according to the invention is shown in respective operating conditions where the upper coiler 8a and the lower coiler 8b are operative. These figures show the spindle of the upper coiler 8a and the spindle of the lower coiler 8b, which are denoted by 11 and 12, while the strip 2 cut by the shears 7 is distributed downstream of the latter towards either of said coilers.

More particularly, Figure 2 shows the end stage of winding of a strip onto the upper coiler 8a.

It should be noted how in this situation the drive unit 6 is oriented so that the travel plane of the strip emerging from it is oriented towards the spindle 12 of the lower coiler 8b, although the preceding strip is still being wound onto the upper coiler 8a.

During this end stage the strip 2 is deflected by means of an upper deviator roller 24 as it moves towards the coil wound onto the spindle 11 of the upper coiler 8a.

Vice versa, the front end of the strip following the strip which is being wound onto the upper coiler 8a is directed by the drive unit 6 in the direction of the spindle 12 of the lower coiler 8b, where various guides stabilise its feeding movement as will be clarified in more detail below: this occurs because the drive unit 6 is already oriented in such a way as to push the front end of the aforementioned strip towards the lower coiler.

Figure 3, on the other hand, shows the end stage of winding of a strip cut by the shears onto the spindle 12 of the lower coiler 8b.

Contrary to that which has just been seen in the case of the upper coiler, in Figure 3 the drive unit 6 is oriented so that the travel plane 18 of the strip 2 leaving the unit 6 is directed towards the spindle 11 of the upper coiler 8a.

Consequently, the strip which is still being wound onto the spindle 12 of the lower coiler 8b is deflected by a second lower deviator roller 25 situated opposite the first one.

At the same time, on the other hand, the front end of the strip following the one being wound onto the lower coiler 8b is directed towards the spindle 11 of the upper coiler 8a, since the drive unit 6 is already positioned correspondingly oriented towards this coiler.

Figure 4 shows in more detail the apparatus for distribution of the strips towards the coilers 8a, 8b.

As can be seen, this apparatus consists essentially of the drive unit 6 and means for guiding the strip, which are shown in schematic form.

The drive unit 6 comprises two rollers 15 and 16 which are actuated and have parallel axes of rotation and are active on the opposite sides of the advancing strip; the plane passing through the axes of rotation of the rollers is defined in the drawings by its line intersecting with the plane of the figures and is denoted by 17.

The travel plane of the strip 2 leaving the feed rollers 15 and 16, which is perpendicular to the plane 17, has been indicated instead by 18.

As can be seen in Figures 4 and 5, the drive unit 6 may be adjusted so that the plane 17 can be oriented on both sides relative to a vertical reference direction; by means of this adjustment the plane 18, i. e. the travel plane of the strip, is adjusted in two separate directions.

Depending on these two different possibilities for orientation of the drive unit 6, it is possible to direct the strip emerging from it respectively towards an entry guide 19 for the spindle 11 of the upper coiler 8b or towards an entry guide 20 for the spindle 12 of the lower coiler 8b.

The entry guides 19 and 20 are defined by flat surfaces 19a, 20a on the outside and on the inside by another V-shaped surface 21, towards which the strip 2 is conveyed.

Further guides are arranged at the exit point of the drive unit 6 and are also composed of flat upper and lower surfaces 22 and 23 at the downstream ends of which with respect to the direction of feeding of the strip the associated deviator rollers 24,25 are located, respectively.

The guides 22,23 together with the deviator rollers 24,25 are integral with the drive rollers 15 and 16 so that the variation in position of the latter obtained by orienting the drive unit 6 as explained above also allows the guides 22,23 together with the deviator rollers 24,25 to be oriented at the same time.

The guides 22,23 and the deviator rollers 24,25, in the example of embodiment shown, are located at a suitable distance from the entry guides 19,20, 21 so as to define a through-opening 26 through which the strip 2 may be deviated towards either coiler 8a, 8b depending on the orientation of the rollers 15 and 16 of the feed unit 6. Furthermore, as can be noted from the drawings, the distance 27 between the guides 22 and 23 as well as between the deviator rollers 24 and 25 is less than or equal to that 28 between the surfaces 19a, 20a of the entry guides 19 and 20 and the V-shaped surface 21.

As a result of such a positioning arrangement and the dimensions of these elements, in fact, during the end stage already mentioned of winding of a strip, the drive unit 6 may be pre-set for winding of the front end of the following strip.

In this case, in fact, as shown in Figure 4, a strip 2 being wound onto the spindle 12 of the lower coiler 8b advances along the associated guide 20, while its tail end is guided by the surface 23 and by the deviator roller 25 across the through-opening 26.

Since the drive unit 6 is already oriented during this stage, as can be seen on the left-hand side in Figure 4, together with the plane 18 directed upwards, the front end of the strip following that still being wound is directed immediately towards the entry guide 19 for the spindle 11 of the upper coiler 8a, while the tail end which precedes it is still passing into the entry guide 20.

The opposite situation is shown in Figure 5. Here it is possible to see the tail end of the strip 2 advancing along the entry guide 19, while it is still located on the deviator roller 24 and is guided by the latter across the through-opening 26.

During this end stage of winding of a strip, the front end of the following strip has already passed through the drive rollers 15 and 16 of the associated unit 6, which are oriented downwards, and is directed towards the entry guide 20 along which it advances without difficulty.

The deviator rollers 24 and 25 delimit at the same time, as a result of their deflecting function, the path of the strip between the drive unit 6 and the entry guides 19 and 20 such that, by means of the invention, reliable guiding of the strip 2 both during and at the end of the winding process is ensured.

From what has been stated hitherto it is therefore possible to understand how distribution of the strips to the winding coilers is performed by the associated apparatus of this invention.

What must be underlined here is that this important result is obtained in a simple and reliable manner despite the very high strip feeding speeds (of the order of 20 m/s).

It is in fact obvious that, at these speeds, separating the tail end of a strip from the front end of the following strip so as to direct the latter towards one or other of the winding coilers is not a simple problem.

The distribution apparatus according to the invention is able to perform this operation very reliably using components which are easy to manufacture and low- cost.

The surfaces which form the guides 19,20 and 22,23 are in fact normal metalwork structures which can be obtained from simple metal sheets, while the deviator rollers 24 and 25 also certainly do not pose any problems with regard to manufacture.

As regards the feed unit 6 in which the two rollers 15 and 16 may be oriented, it should be pointed out that such machines are already known in the prior art (for all of them see EP 0 469 483) and, as a result of the teaching provided by this invention, it is not necessary to make any particular modifications to them except, obviously, for the means which guide the strips according to the teaching resulting from that described above.

Furthermore, since the amount of time required to adjust the orientation of the drive unit is not excessively short (despite the high strip feeding speeds) owing to the operating mode of the abovementioned apparatus, control thereof performed using instruments which are known per se therefore also does not pose particular difficulties, with obvious positive repercussions on the design and manufacture thereof.

Obviously variations of the invention with respect to the example which has been described above are also possible.

Firstly it should be pointed out that the deviator rollers 24 and 25 of the strip distribution apparatus, which for the sake of simplicity have been regarded as being idle, may also be motor-driven; in this way it would be possible to obtain the advantage of being able to reduce to a minimum the friction between each roller and a strip advancing on its surface, causing them to rotate with a peripheral speed close to the strip feeding speed.

It is also possible for these deviator rollers to be eliminated, replacing them, if necessary, with rounded surfaces located at the end of the guides 22 and 23.

Such a solution could perhaps prove interesting in the case where the distribution apparatus according to the invention is used for applications other than that of hot- rolled thin strips.

In this connection it is in fact conceivable to use this apparatus in all those industrial sectors where flexible products of predetermined length, fed one after another at high speeds, must be distributed towards different utilities. An example of these applications could be various cables for industrial use, wire rods or paper or plastic strips which are wound in the form of reels.

From what has been stated with regard to the possible various uses of the apparatus, it may also be understood that its application is not limited to the distribution of strips towards winding coilers situated at the same distance from the cooling section of a rolling plant.