FIELD OF THE INVENTION

The present invention concerns an apparatus, a plant and a method for rolling long metal products, which can be applied, for example but not restrictively, in the field of production of wire rod, coils, bars, wires and other types of similar products, both smooth and ribbed.

BACKGROUND OF THE INVENTION

In the field of production of long metal products, such as wire rod, coils, bars or wires, it is known to use a rolling plant consisting of a succession of rolling stands, each of which comprises a pair of opposite rollers which define a rolling channel between them. In particular, for the finishing rolling of a long metal product, fast rolling blocks, called “BGV”, are known and used, consisting of rolling stands or cassettes disposed alternately to each other at 45°, which give the product an alternating configuration between each oval-round pass, reducing the section pass after pass.

More specifically, a long metal product, which can be obtained, for example, from a billet in the case of billet-to-billet rolling, or from a continuous element in the case of endless or semi-endless rolling, in the final or finishing step of rolling, passes through the rolling channel defined by each pair of rollers of the BGV and is progressively worked until it reaches a desired cross section and surface finish, and is then normally wound in a coil-forming head.

One disadvantage of known solutions is that, in order to pass from the production of one type of metal product to another, for example from coil to wire rod, from smooth to ribbed, from one type of rib to another, or in the case of excessive wear of the rolling rollers that does not guarantee compliance with the tolerances, etc., it is necessary to stop production and replace and/or reposition at least the rollers of the finishing stand concerned. This entails an increase in the direct production costs of the metal product, a lowering of the plant’s productivity and an increase in the maintenance costs of the plant, especially in the case of a continuous process.

This disadvantage occurs even more evidently in the case of the production of ribbed metal wire, for which a specific type of rib may be required, different on each occasion depending on the final destination of the metal wire itself: in fact, different countries may request ribs of different types. In this case too, in order to switch from one type of rib to another, it is necessary to stop production and replace and/or reposition the rollers of the finishing stand.

Documents WO2015/160526 Al, JPH05123705, DE 33 12 078 Cl and DE 23 37 313 Al describe generic solutions of guide elements associated with pairs of rolling rollers to guide the product being rolled into different channels provided on the rollers.

For example, JP’705 concerns a reversible stand in which the product being rolled moves first in one direction and then in the other, and the rolling rollers translate in a direction orthogonal to the direction of feed in order to align channels that are progressively smaller in section, provided on the rollers. In the other documents too, it is provided that the rolling channels provided on the rollers align themselves with the axis of feed of the product being rolled, which does not change during the rolling process, after a certain amount of rolled products, so as to have channels that are not worn.

There is therefore a need to perfect a rolling apparatus that can overcome the disadvantages of the state of the art.

The purpose of the invention is therefore to reduce the time required to change the type of metal product produced by the rolling plant.

Another purpose of the present invention is to provide an apparatus for rolling long metal products that allows to quickly change the characteristics of size and shape and surface finish that are to be given to the metal product.

Another purpose of the present invention is to provide an apparatus, and to perfect a method, for rolling long metal products, which increase the productivity of the rolling plant, reducing the maintenance times and costs thereof.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea. In accordance with the above purposes, a rolling apparatus according to the present invention is used in a block of fast stands for the finishing rolling of long metal products.

In particular, the rolling apparatus is used in the last one, or in the last few, rolling passes in which the section and the final finish in tolerance of the product are defined.

The rolling apparatus according to the invention is provided with rolling means comprising a rolling stand having a first roller rotatable around a first axis of rotation and a second roller, opposite the first roller, rotatable around a second axis of rotation substantially parallel to the first axis of rotation.

In accordance with one aspect of the present invention, the first roller comprises at least two first grooves and the second roller comprises at least two second grooves, opposite the first grooves and defining with them at least two rolling channels. The rolling channels each define their own axis of exit of the metal product being rolled, at least one of which is misaligned with the axis of arrival of the product being rolled from the previous rolling stand.

In accordance with one aspect of the present invention, the rolling apparatus also comprises guide means configured to selectively guide the metal product toward one or the other of the at least two rolling channels, thus modifying the axis of exit of the metal product from the stand.

In accordance with some embodiments of the present invention, the grooves can have identical work surfaces and sizes, thus defining at least two smooth rolling channels.

In this case, the modification of the exit channel can occur, for example between one rolled billet and the next one, when a first channel has reached a condition of wear that would take the final product out of tolerance, thus allowing to also work the next billet without having to stop the line in order to replace the entire roller.

In accordance with other embodiments of the present invention, the grooves can have surfaces, work finishes and sizes that are different from each other, thus defining at least two rolling channels configured to give a metal product different types of surface finishes or working.

Also in this case, if one wishes to modify, between one billet and another, the surface finish, for example the rib, to be applied, at the end of the first billet the guide means are activated in order to guide the new billet toward another channel, thus modifying the finish applied to the next billet without having to replace the rolling rollers.

In the case of endless or semi-endless working, the channel change can be obtained by cutting, upstream of the fast block, the continuous or semi-continuous product, and scrapping a head segment thereof for a few seconds, thus giving the guide means time to orient or position themselves in order to guide the product to be rolled toward the new rolling channel.

In all these cases, as stated, modifying the channel, or in any case alternately sending the product on several rolling channels provided on the same rollers, involves the axial misalignment between the axis of arrival of the product and the axis of exit from the respective rolling pass.

It goes without saying that this can be achieved without particular problems when working small sections, as is typically the case with the last rolling passes in a fast rolling block for long products.

In accordance with one aspect of the present invention, the guide means comprise a fixed structure on which there is disposed a mobile structure to which two opposite guide rollers are attached, which define a guide channel lying on the same plane on which the at least two rolling channels lie. The mobile structure is configured to selectively direct the guide channel toward one, the other, or the others, of the rolling channels.

In accordance with one aspect of the present invention, the fixed structure comprises a sliding guide on which the mobile structure is slidably mounted.

In accordance with one aspect of the present invention, the mobile structure is pivoted to the fixed structure in order to rotate with respect to the latter around an axis of rotation.

In accordance with one aspect of the present invention, the guide means also comprise a mobile diverter with a substantially tubular shape, configured so that a metal product can pass through it and having both a first end associated with the mobile structure upstream of the guide rollers, and also a second end pivoted to the fixed structure.

The present invention also concerns a rolling plant comprising a rolling line having a plurality of rolling stands disposed in succession and a rolling apparatus according to the present invention, defining the last or one of the last rolling passes of the line.

The present invention also concerns a rolling method comprising the following steps:

- making available rolling means having a first roller rotatable around a first axis of rotation and a second roller, opposite the first roller, rotatable around a second axis of rotation substantially parallel to the first axis of rotation, wherein the first roller comprises at least two first grooves and the second roller comprises at least two second grooves, opposite the first grooves and defining with them at least two rolling channels;

- feeding a metal product toward the rolling means;

- guiding the metal product toward a first rolling channel;

- temporarily interrupting the feed of the metal product toward the rolling means;

- guiding the metal product toward a second rolling channel that is different and misaligned with respect to the first rolling channel, thus modifying the axis of exit of the product with respect to the axis of exit of the first rolling channel;

- feeding the metal product toward the rolling means.

DESCRIPTION OF THE DRAWINGS

These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a top view of an embodiment of the rolling apparatus according to the present invention, in a first work position;

- fig. 2 is a section view along the plane II-II of a rolling apparatus according to the present invention;

- figs. 3 and 4 are top views of the apparatus of fig. 1 in respective work positions;

- figs, from 5 to 7 are top views of a second embodiment of the rolling apparatus according to the present invention in three different work positions;

- fig. 8 is a schematic lateral view of a rolling plant in accordance with the present invention comprising the apparatus of fig. 1.

We must clarify that in the present description the phraseology and terminology used, as well as the figures in the attached drawings also as described, have the sole function of better illustrating and explaining the present invention, their function being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications. DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

With reference to fig. 1, an apparatus 10 for rolling metal products P, preferably long ones, according to the present invention, is provided with rolling means comprising a rolling stand 11 having a support structure 12.

The support structure 12 in turn comprises an upright 13 to which two rolling rollers 16, 17 are rotatably pivoted (fig. 2).

With reference to fig. 8, the rolling stand 11 represents the last rolling or finishing pass in a rolling line for long products, such as billets, wire rods or suchlike.

A first rolling roller 16 rotates around a first axis of rotation X and a second rolling roller 17 rotates around a second axis of rotation Y, substantially parallel to the first axis of rotation X.

In the example given here, three upper grooves 19, 20, 21 are made on the first rolling roller 16, parallel to each other, which develop along the circumference thereof and, in a similar way, another three lower grooves 22, 23 24 are made on the second rolling roller 17, parallel to each other and which develop along the circumference thereof.

The two rolling rollers 16, 17 are disposed opposite each other in such a way as to define three rolling channels 25, 26, 27, each of which consists of the gap between two facing grooves 19 and 22, 20 and 23, 21 and 24.

Preferably, the rolling channels 25, 26, 27 have a substantially identical section. Their surface can be completely smooth or rough, so as to define a respective type of rib, or other surface finish, on the metal product.

For example, with reference to fig. 2, the gap between a first upper groove 19 and a first lower groove 22 defines a first rolling channel 25 having a corresponding first axis of rolling A, or axis of exit, the gap between a second upper groove 20 and a second lower groove 23 defines a second rolling channel 26 having a corresponding second axis of rolling B, or axis of exit, and the gap between a third upper groove 21 and a third lower groove 24 defines a third rolling channel 27 having a corresponding third axis of rolling C, or axis of exit.

Each groove 19, 20, 21, 22, 23 has a respective work surface configured to act on the metal product P which transits in the respective rolling channel 25, 26, 27.

According to one aspect of the present invention, the work surface of the two grooves that define a specific rolling channel is different from the work surface of two other grooves that define another rolling channel, and it is created as a function of the characteristics of size and surface finish to be given to the metal product P that transits in that specific rolling channel.

This allows to use a single pair of rolling rollers 16, 17 to perform two or more different types of surface working on a metal product P, without needing to replace them.

For example, always referring to the embodiment shown in fig. 1, the grooves 19, 22 (fig. 2) that define the first rolling channel 25 have a smooth work surface, the grooves 20, 23 that define the second rolling channel 26 have a work surface configured to give a metal product P a first type of rib, and the grooves 21 , 24 that define the third rolling channel 27 have a work surface configured to give a metal product P a second type of rib, different from the first type of rib.

In other embodiments not shown in the drawings, the work surface of the grooves 19, 20, 21, 22, 23, 24 of each of the rolling rollers 16, 17 can be substantially the same for each groove 19, 20, 21, 22, 23, 24 so that the surface finish given to the metal product P is the same for each rolling channel 25, 26, 27.

This allows to change the rolling channel in which the metal product P transits, for example in the event that a rolling channel is excessively worn, without needing to replace and/or reposition the rolling rollers 16, 17.

An expert in the field easily understands that the work surface of the various grooves 19, 20, 21, 22, 23, 24 of a rolling device 11 in accordance with the present invention can be created in such a way as to produce any combination whatsoever of smooth rolling channels and/or rolling channels configured to give the metal product a specific rib.

Purely by way of example, another embodiment of the rolling device 11 can comprise two smooth rolling channels and one rolling channel configured to give the metal product a specific type of rib. Alternatively, the rolling device 11 can comprise two rolling channels configured to give the metal product the same type of rib and another smooth rolling channel. It is also possible for the rolling device 11 to comprise two or more smooth rolling channels, or two or more rolling channels configured to give the metal product the same type of rib, or different types of rib. It is also clear that the number of grooves 19, 20, 21, 22, 23, 24 made on each rolling roller 16, 17, and consequently the number of rolling channels 25, 26, 27, can be different from three, for example it can be two, four or more, for example as a function of the ratio between the section of the metal product to be worked and the width of the table of the rolling rollers 16, 17.

Moreover, an expert in the field easily understands that the disposition of the rolling rollers 16, 17 and of the respective axes of rotation X, Y can be different from the horizontal one, for example the rolling rollers 16, 17 can be disposed inclined or vertical.

The apparatus 10 also comprises a guide device 40 configured to selectively guide and orient a metal product P toward a specific rolling channel 25, 26, 27 of the rolling device 11.

In this way, between a first billet and the next, if it is necessary to modify the rolling channel of the rolling rollers 16, 17, either because the channel is excessively worn and out of tolerance, or in order to change the rib or finish in general to be applied, or for another reason, the guide device 40 is used to divert the product into a new channel with respect to the previous one, thus modifying the respective axis of exit between the axes A, B or C.

The guide device 40 comprises a fixed structure 41 on which there is mounted a mobile structure 42 which supports a guide body 43 having at a first end two support arms 45, 46 (figs. 1 and 5) to each of which a respective guide roller 47, 49 is pivoted. The two guide rollers 47, 49 are opposite each other and define a guide channel 50 lying on the same plane in which the rolling channels 25, 26, 27 lie. In particular, the guide device 40 is configured to selectively direct the guide channel 50 toward one or the other rolling channel 25, 26, 27.

At a second end of the guide body 43, opposite the first end, there is disposed a reception cone 51 configured to receive the metal product P and to guide it toward the guide channel 50. In the embodiment of figs. 1, 3 and 4, the fixed structure 41 comprises a sliding guide 44 on which the mobile structure 42 is slidably mounted.

In this case, the translation of the mobile structure 42 with respect to the fixed structure 41 is commanded by an actuator of a known type (not shown), and occurs in a horizontal direction D substantially parallel to the axes of rotation X, Y of the rollers 16, 17.

On the other hand, in the embodiment of figs, from 5 to 7, the mobile structure 42 is pivoted to the fixed structure 41 in order to rotate angularly with respect thereto around an axis of rotation Z substantially orthogonal to the axes of rolling A, B, C. In this case, the rotation of the mobile structure 42 around the axis of rotation Z is commanded by an actuator of a known type (not shown).

In both the embodiments shown in the attached drawings, the guide device 40 can assume a first work position in which the guide channel 50 substantially faces the first rolling channel 25 (figs. 3 and 6), a second work position in which the guide channel 50 substantially faces the second rolling channel 26 (figs. 1 and 5) and a third work position in which the guide channel 50 substantially faces the third rolling channel 27 (figs. 4 and 7). Since the guide device 40 selectively orients and guides the metal product P toward one of the rolling channels 25, 26, 27, while the rolling rollers 16, 17 keep their position fixed, it follows that with each change of rolling channel, the exit channel A, B or C of the metal product P from the rolling stand 11 changes.

The guide device 40 also comprises a mobile diverter 52 configured to receive a metal product P from a rolling stand 103 upstream thereof and to guide it toward the reception cone 51. In particular, the mobile diverter 52 has a substantially tubular shape and has a fixed end 54, associated with the fixed structure 41, from which the metal product P enters and a mobile end 53, associated with the mobile structure 42 upstream of the reception cone 51 , from which the metal product P exits.

The mobile end 53 and the fixed end 54 of the mobile diverter 52 are attached to the mobile structure 42 and to the fixed structure 41, respectively, by means of respective joints 55, 56 which allow the rotation of the mobile diverter 52 around its fixed end 54 by a few degrees, during the displacement of the mobile structure 42. In the embodiment shown in the figs, from 5 to 7, the rotation of the mobile diverter 52 preferably occurs around the axis of rotation Z of the mobile structure 42.

With reference to fig. 8, the present invention also concerns a rolling plant 100 comprising a rolling line 101, preferably a finishing line of the “BGV” type, essentially consisting of a plurality of rolling stands 103 disposed in succession, downstream of which the last rolling stand 11 is disposed. The rolling plant 100 also comprises a rolling apparatus 10 as described above, associated with the last rolling stand 11. In the example given here, the fixed end 54 of the mobile diverter 52 of the apparatus 10 is advantageously disposed downstream of the rolling stand 103 of the rolling line 101.

Please note that, in other embodiments not shown in the drawings, the apparatus 10 can also be disposed between two rolling stands 103 of the rolling line 101 and not necessarily downstream of the last rolling stand 103.

In general, the apparatus 10 will be disposed in a terminal position, or in proximity to the terminal position, of the rolling line 101.

The operation of the rolling apparatus 10 described heretofore, which corresponds to the method according to the present invention, comprises the following steps.

A metal product P is fed along a rolling line 101 of a rolling plant 100 and, before it reaches the guide device 40, the mobile structure 42 is positioned in such a way as to direct the guide channel 50 toward a first rolling channel 25 (figs. 3 and 6) of the rolling device 11.

For example, in the first embodiment, the actuator commands the translation of the mobile structure 42, with respect to the fixed structure 41, in the horizontal direction D in order to align the guide channel 50 with the first rolling channel 25.

Alternatively, in the second embodiment, the actuator commands the rotation of the mobile structure 42, with respect to the fixed structure 41, around the axis of rotation Z, in order to take the guide channel 50 into a position substantially facing the first rolling channel 25.

In the event that the work surfaces of the grooves 19, 20, 21, 22, 23, 24 are different from each other (figs. 1, 3 and 4), this alignment step is advantageously carried out in relation to the surface working that each rolling channel can give to the metal product P.

Alternatively, if the work surfaces of the grooves 19, 20, 21, 22, 23, 24 are substantially identical to each other, this alignment step is advantageously carried out in relation to the wear of the rolling channels 25, 26, 27, for example choosing to direct the guide channel 50 toward the less worn rolling channel.

After a certain work time, the mobile structure 42 is positioned in such a way as to direct the guide channel 50 toward a new rolling channel, different from the previous rolling channel (for example, passing from fig. 1 to fig. 3, or to fig. 4, or vice versa, or passing from fig. 5 to fig. 6, or to fig. 7, or vice versa).

In the event that the work surfaces of the grooves 19, 20, 21, 22, 23, 24 are different from each other (fig. 1), this changeover step allows to change the characteristics of size and/or shape of the metal product P without needing to replace the rolling rollers 16, 17.

Alternatively, in the event that the work surfaces of the grooves 19, 20, 21, 22, 23, 24 are substantially identical, this changeover step allows to change the rolling channel when the one currently being used has reached a certain level of wear, without needing to replace the rolling rollers 16, 17.

Similarly to the alignment step, also during the changeover step the metal product P does not transit in the guide device 40.

For example, in the case of billet-to-billet type rolling, the changeover step is carried out during the time that elapses between the exit of a first billet from the guide device 40 and the entry of a new billet therein.

Alternatively, in the case of endless or semi-endless type rolling (fig. 5), the time required for the changeover step can be achieved by cutting the metal product P in transit in the guide device 40, for example by means of a shear upstream of the latter, and scrapping a portion of the metal product P itself during the displacement of the mobile structure 42.

It is clear that modifications and/or additions of parts or steps may be made to the rolling apparatus 10, plant 100 and method as described heretofore, without departing from the field and scope of the present invention, as defined by the claims.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of rolling apparatus, plant and method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.