Device and method for changing the reel in an unwinder

The present invention concerns a device and a method for changing the reel in an unwinder, which may be used, in particular, for paper reels and other materials in web form.

As is known, the function of unwinders is to unwind a web material from a reel to supply it to one or more machines located downstream in a determined work cycle.

In a possible known conformation, an unwinder comprises a bearing structure on which are arranged two conical supports intended to engage two corresponding mandrels inserted bilaterally in the central tubular nucleus of the paper reel, called also “core”, in such a way that the reel is free to turn around the respective axis and the free unwinding of the respective web is allowed.

A relatively important phase in the use of unwinders is the changing of the reel, that is the operation with which a nearly empty reel is replaced with a new reel. This operation, which must guarantee the continuity of the supply of web to the machines located downstream, is most frequently carried out in an almost exclusively manual way with both the reels stopped. In practice, the first reel, which is nearly empty, is moved away from the support cones, between which an operator, with the aid of a mechanical lifter, then fits a new reel to be unwound; the operator must also manually slacken an end portion of the paper web supplied by the nearly empty reel and connect that portion of web to the portion at the start of the web on the new reel. Besides this, the operator must manually cut the finished web, in a point upstream from said connection.

It is clear that the operation described above is closely linked with the skill of the operator and, in the event of failed, imprecise or faulty connection of the webs of the two reels involved, it leads to interruptions in the production cycle downstream from the unwinder, with economic damages due to the resulting production loss. Examples of mechanical unwinders, in which human intervention is reduced, are given in WO 2004/080869, WO 2004/080867, WO 2004/043827, U.S. Pat. No. 6,679,451 and EP 822912. However, these known unwinders are rather complex, from both the mechanical and the functional point of view.

The main aim of the present invention is to overcome the above-mentioned inconveniences, that is to optimise and simplify the reel changing operation.

This result is achieved, in conformity with the present invention, by adopting the idea of realising a device and a method having the characteristics described in the independent claims. Other characteristics of the invention are the object of the dependent claims.

Thanks to the present invention, it is possible to change the reel automatically, precisely and in complete safety, without having to assign this operation to particularly expert or qualified personnel. Moreover, a device in conformity with the present invention is relatively simple and economic to make, and, in relation to its mechanical and functional simplicity, it is reliable even after a prolonged period of use.

In the enclosed drawings the numerical reference 1 indicates, on the whole, a possible embodiment of an unwinder according to the present invention. In the continuation of this description, the expressions “upstream” and “downstream” refer to the direction of advance of the web (towards the right in the drawings). Moreover, the term “end portion or tail end” defines that portion of the web of a reel that is finishing, obtained by cutting and intended to be joined to the initial portion or “head portion or end” of the web of a reel intended to replace the one that is finishing.

The unwinder 1 is provided with a pair of conical supports, of the same type as those used in conventional unwinders, suited to engage two mandrels 50 inserted from opposite sides in the core 3 of a reel 2 during the unwinding of the latter, so as to define a horizontal axis around which the reel itself is free to rotate. In other words, between said support cones is defined an unwinding station of the web supplied by the reel 2, this station being identified with S1 in the drawings. For simplicity\'s sake, and as they are known to the technicians in the sector, the aforesaid cones are not illustrated in the drawings.