DESCRIPTION

Field of the invention

The present invention relates to an apparatus for splitting and spreading a continuous web, particularly but not exclusively a web of plastic material.

According to a further aspect, the present invention further relates to a method for splitting and spreading a continuous web.

In the context of the present invention, the term continuous web is used to distinguish a flat web, as well as a flattened tubular web or a flat web having continuous longitudinal portions folded transversely on themselves.

Furthermore, the web can be a web of thermoplastic material, as well as of other materials, such as cellulose, material of plant origin, fabrics, non-woven fabrics, aluminium and still others.

Furthermore, the aforesaid web can comprise a structure formed by several layers adhered or otherwise integrally joined together.

For ease of presentation, the present disclosure is made, by way of non-limiting example, with particular reference to a continuous web of plastic material, a so-called film.

Background of the invention

Continuous webs of plastic material, whether they are a flat web or a flattened tubular, are transited in a web path defined by respective turning bars and the like immediately after their formation, so as to have time to cool, until they are wound in reels at appropriate winding rollers.

In particular, the web is wound on specific support tubes, otherwise called support cores, which laterally extend beyond the sides of the web.

The winding step is a critical operation as it is necessary to avoid the formation of wrinkles or folds and at the same time it is necessary to ensure the correct winding tension of the continuous web as the diameter of the reel increases.

Often there is a need to perform processing or treatments on the continuous web of a reel, for example rewinding operations in order to obtain reels of webs of shorter length. For this purpose, unwinding and rewinding lines of the continuous web are used.

It should be noted that there is very frequently a need to split a continuous web of a predetermined transverse width into two separate webs of smaller width, with each of the two webs wound around a respective support tube. Such a need can arise both for continuous webs already wound on a reel and for continuous webs just produced and not yet wound on a reel.

As stressed above, it is good for the support tube to protrude laterally from the continuous web wound thereon, so that if it is necessary to split a reel of continuous web of a predetermined transverse width into two reels of continuous web of smaller transverse width, it is not a viable solution to only cut the starting reel into the two narrower reels, making it necessary to cut and remove a strip of reel between the two reels to be obtained.

Obviously, such a solution inevitably involves the waste of a strip of material, a strip which has a length equal to the length of each reel, which is why this solution involves a considerable waste of continuous web. Alternatively, it is possible to include specific means for cutting and spreading the continuous web, capable of acting on a section of continuous web unwound from a reel to split it into two webs of smaller width to be subsequently rewound on two separate support tubes. In this case, before the first winding occurs in a reel or in a subsequent step during a process of unwinding and rewinding a continuous web, a special blade cuts a continuous web at a predetermined point of its transverse width. However, the problem lies in achieving a correct spreading, thus a transverse distancing, of the two webs separated from each other without affecting the winding mode, in particular without creating folds, wrinkles and the like in each web. Nowadays, to overcome such a problem, the use of independent spindles is envisaged with which to ensure the support and independent dragging in rotation of the two support tubes on which the reels of continuous web of smaller width will be formed, obviously in the face of an obvious complication in structural, operational and adjustment terms of the machine necessary to perform the winding on the aforesaid independent support tubes.

However, it should be noted that despite the use of two independent spindles, the transverse spreading of the two webs downstream of the cutting means operated by appropriate turning bars still imposes deformations on the two continuous webs even if the support tubes on which the two separate continuous webs are wound are moved by independent spindles, which is why the distance between the two webs is achieved not with an effective spreading, or not only with an effective spreading, but by removing an intermediate continuous strip of web between the two separate webs.

Summary of the invention

In view of the above, it is therefore evident that nowadays it is very felt the need to be able to transversely split a continuous web into two webs of a smaller width without having to discard a strip of continuous web material to be split, while ensuring a correct winding of the two separate webs with the correct winding tension envisaged and without ruining the flatness thereof.

The problem of the present invention is that of devising an apparatus for splitting and spreading a continuous web which has structural and functional features such as to meet the aforesaid needs, while remedying the problems referred to with reference to the background art.

Such a problem is solved by an apparatus for splitting and spreading a continuous web in accordance with claim 1.

According to a further aspect, such a problem is also solved by a method for splitting and spreading a continuous web in accordance with claim 12.

Brief description of the figures

Further features and advantages of the present invention will emerge from the description given below of some of its preferred embodiments, given by way of nonlimiting example, with reference to the accompanying figures, in which:

- figure 1 depicts a schematic plan view of an apparatus for splitting and spreading a continuous web in a configuration in which said apparatus does not act on the continuous web to split and spread it;

- figure 2 depicts the apparatus of figure 1 in a configuration in which it acts on the continuous web, cause it to split and spread;

- figure 3 depicts a sectional view according to the line of section III- III of figure 1;

- figure 4 depicts a sectional view according to the line of section IV-IV of figure

1; - figures 5 and 6 show a perspective view of figure 2, in which the apparatus acts on the continuous web causing it to split and spread, according to two different points of view and

- figure 7 depicts an enlarged detail of figure 5 to better show the action of the accessory on one of the two parts in which the starting web is split.

Detailed description of the invention

With reference to the accompanying figures, 1 globally denotes an apparatus according to the invention for splitting and spreading a portion of continuous web.

In particular, the apparatus 1 comprises:

- supporting and guiding means for defining a web path P extending along a predetermined longitudinal direction X-X between an input zone and an output zone, in which said web path P is designed to be travelled by a continuous stretched web running in a predetermined feed direction A from said input zone toward said output zone and

- cutting means 2 located in a predetermined transverse position of said web path P to determine a cutting line L extending along said longitudinal direction X-X in a continuous web running along said path P.

A path section upstream of said cutting means 2 and a path section downstream of said cutting means 2 are defined in said web path P, said upstream and downstream sections being defined with reference to the feed direction A of a web along said web path.

The aforesaid cutting line L splits the aforesaid path section downstream of the cutting means 2 into two distinct longitudinal portions, in particular a first longitudinal portion I and a second longitudinal portion n.

The aforesaid supporting and guiding means comprise two respective pairs 3,4 of turning bars located at the downstream path section of the cutting means 2, in particular:

- a first pair of turning bars 3 extending transversely to said first longitudinal portion I of the web path P and starting from said cutting line L and

- a second pair of turning bars 4 extending transversely to said second longitudinal portion II of the web path P and starting from said cutting line L, so that said first pair of turning bars 3 and said second pair of turning bars 4 extend on opposite sides of said cutting line L.

The aforesaid two respective pairs 3,4 of turning bars extend transverse to the aforesaid cutting line L according to an angle a other than 90°, preferably according to an angle a comprised between 25° and 65.

It should be noted that the aforesaid first pair of turning bars 3 and the aforesaid second pair of turning bars 4 are inclined with respect to the cutting line L so as to diverge from each other when running along the aforesaid feed direction A along the longitudinal direction X-X.

Each respective pair 3,4 of turning bars comprises a first turning bar 5 and a second turning bar 6 which are designed to contact, with a respective contact portion 7,8, a first side and, respectively, an opposite second side of a web running along the web path P, so that said web path P will pass between the first turning bar 5 and the second turning bar 6 of each pair 3,4 of turning bars.

Advantageously:

- the first turning bar 5 and the second turning bar 6 of each respective pair 3,4 of turning bars are offset in said longitudinal direction X-X so as not to overlap each other along an orthogonal direction Z-Z perpendicular to the plane passing through said web path P, said first turning bar 5 being closer to the aforesaid cutting means 2 than the second turning bar 6 and - the first turning bar 5 and the second turning bar 6 of each respective pair 3,4 of turning bars are supported so as to be reversibly adjusted relative to each other in said orthogonal direction Z-Z until said second turning bar 6 is moved past said first turning bar 5 to pass:

• from a coplanar configuration in which said contact portion 8 of said second turning bar 6 is substantially coplanar with said contact portion 7 of said first turning bar 5 and said web path P passing between said first turning bar 5 and said second turning bar 6 extends straight between the first turning bar 5 and the second turning bar 6 of each respective pair 3,4 to

• an offset configuration in which said contact portion 8 of said second turning bar

6 extends in said orthogonal direction Z-Z beyond said contact portion 7 of said first turning bar 5 and said web path P has a section at the exit of each respective pair 3,4 of turning bars offset in said orthogonal direction Z-Z from the section of said web path P at the entry of each respective pair 3,4 of turning bars.

Preferably, in the aforesaid offset configuration in which the contact portion 8 of the second turning bar 6, i.e., the one farthest back from the cutting means 2, extends in the orthogonal direction Z-Z beyond the contact portion 7 of said first turning bar 5, the web path P, when crossing each pair of turning bars 3,4, follows a substantially "S- shaped" offset trajectory in said orthogonal direction Z-Z.

Preferably, in each respective pair 3,4 of turning bars, said second turning bar 6, i.e., the one farthest back from the cutting means 2, is movable and adjustable in positioning in said orthogonal direction Z-Z with respect to said first turning bar 5 which is fixed in said orthogonal direction Z-Z.

Preferably, the apparatus 1 comprises actuating means for causing displacement/adjustment in said orthogonal direction Z-Z of the second turning bar 6 with respect to the respective first turning bar 5 of each respective pair 3,4 of turning bars.

Preferably, the aforesaid first pair of turning bars 3 and the aforesaid second pair of turning bars 4 are offset from each other in the longitudinal direction X-X to avoid any mutual interference thereof at said cutting line L, this allows, for example, to have an arrangement in which both the first turning bar 5 and the second turning bar 6 of each respective pair of turning bars 3,4 extend beyond the cutting line L by a predetermined limited amount (see figures 1 and 2).

Preferably, the aforesaid turning bars have a low friction surface so as not to obstruct the sliding of a continuous web in contact therewith. For example, according to a non-exhau stive list, the aforesaid turning bars can be turning bars with air cushions, turning bars with a lapped surface and/or turning bars coated with low-adhesion material.

Preferably, the aforesaid supporting and guiding means for defining a web path P further comprise at least one reversing roller 9:

- having a high-friction surface and

- located downstream of said pairs 3,4 of turning bars to contact an extended web running in said predetermined feed direction A along said web path P, preferably to contact the two distinct longitudinal web portions downstream of the cutting means 2 and running along the first longitudinal portion I and the second longitudinal portion n.

Such at least one reversing roller 9 has the function of fixing the transverse displacement of the longitudinal portions of continuous web which are spread/moved apart as they move past said respective pairs 3,4 of turning bars in their offset configuration, so as to prevent the two aforesaid longitudinal portions of spread/moved apart continuous web from approaching each other again in juxtaposition.

In addition to what has been described above, the apparatus 1 can comprise further turning bars known per se and arranged for guiding and supporting a continuous web or two continuous webs spread out along said web path P.

With regard to the aforesaid cutting means 2, it should be noted that, in accordance with the illustrated embodiment, they are movable and adjustable to reversibly move:

- from a position away from said web path P, to avoid interference thereof with a continuous web running in said web path P (see figures 1 and 3)

- to a working position in which they interfere with said web path P to form a longitudinal cut in a continuous web running along said web path P (see Figures 2, 4, 5, 6 and 7).

Preferably, in accordance with the embodiment illustrated:

- the aforesaid turning bars extend along horizontal planes;

- in each pair 3, 4 of turning bars, said first turning bar 5 and said second turning bar 6 are designed to contact, by a respective contact portion 7,8, a top side and, respectively, an opposed top side of a web running along said web path P and

- in said offset configuration, said contact portion 8 of said second turning bar 6 vertically extends upwards in said orthogonal direction Z-Z (by a distance "D" as shown in figure 7) beyond said contact portion 7 of said first turning bar 5, so that said web path P will have a section at the exit of each respective pair 3,4 of turning bars upwardly offset in said orthogonal direction Z-Z from the section of said web path P at the entry of each respective pair 3,4 of turning bars.

According to the invention, the method for splitting and spreading a continuous web into two continuous longitudinal portions, comprises the steps of:

- arranging a web path P extending along a predetermined longitudinal direction X-

X between an input zone and an output zone in which an extended continuous web will be supported and guided by supporting and guiding means; - running a continuous web along said web path P with a feed direction A from an input zone to an output zone;

- arranging cutting means 2 located in a predetermined transverse position of said web path P to form a cutting line L extending along said longitudinal direction X-X;

- cutting said continuous web running in the feed direction along said path P by said cutting means 2 to split, downstream of said cutting means 2, said continuous web into a first longitudinal portion I and a second longitudinal portion II;

- arranging a first pair of turning bars 3 and a second pair of turning bars 4 positioned:

• downstream of said cutting means 2 with reference to the feed direction A of said web and

• extending transverse to said web path P at an angle a other than 90°, preferably at an angle a comprised between 25° and 65 from said cutting line L, so that said first pair of turning bars 3 and said second pair of turning bars 4 will extend on opposite sides from said cutting line L, such that said first pair of turning bars 3 and said second pair of turning bars 4 will only be run along by said first longitudinal portion and, respectively, only by said second longitudinal portion n; in which each respective pair 3,4 of turning bars comprises a first turning bar 5 and a second turning bar 6 which are designed to contact, with a respective contact portion 7,8, a first side and, respectively, an opposite second side of a web running along said web path P, so that said web path P will pass between the first turning bar 5 and the second turning bar 6 of each pair 3,4 of turning bars; in which:

- the first turning bar 5 and the second turning bar 6 of each respective pair 3,4 of turning bars are offset in said longitudinal direction X-X so as not to overlap each other along an orthogonal direction Z-Z perpendicular to the plane passing through said web path P, said first turning bar 5 being closer to cutting means 2 with respect to said second turning bar;

- the first turning bar 5 and the second turning bar 6 of each respective pair 3,4 of turning bars can be offset in said orthogonal direction Z-Z so as to assume an offset configuration in which said contact portion 8 of said second turning bar 6 extends beyond said contact portion 7 of said first turning bar 5 in said orthogonal direction Z-Z and said web path P has a section at the exit of each respective pair 3,4 of turning bars offset in said orthogonal direction Z-Z from the section of said web path P at the entry of each respective pair 3,4 of turning bars and

- said method comprises the step of causing said first longitudinal portion of the cut web to run along said first pair 3 of turning bars and of causing said second longitudinal portion of said cut web to run along said second pair 3 of turning bars, whereas the second turning bar 6 of each respective pair 3,4 of turning bars is offset in said orthogonal direction Z-Z beyond the first turning bar 5, so as to cause said web path P and said longitudinal portions of cut web to assume a pattern having a section at the exit of each respective pair 3,4 of turning bars which is offset in said orthogonal direction Z-Z with respect to the section of said web path P at the entry of each respective pair 3,4 of turning bars.

Such a method therefore makes it possible to interrupt the longitudinal continuity of the initially continuous web, dividing it into two continuous webs of smaller width, the sum of the widths of the two continuous longitudinal webs of smaller width being equal to the transverse width of the starting web.

When the second turning bar 6 of each pair 3, 4 of turning bars is positioned to overlap the first turning bar 5 closest to the cutting means in the aforesaid orthogonal direction Z-Z, an offset is obtained in the orthogonal direction Z-Z of the section of the two longitudinal webs in output from each pair 3, 4 of turning bars with respect to the inlet section, which, combined with the aforesaid transverse inclination referred to above of the turning bars 5,6 of the aforesaid pairs 3, 4 of turning bars, also causes a simultaneous movement therebetween and away from said cutting line L of the first longitudinal portion and the second longitudinal portion of the continuous webs obtained in passing through the respective pair 3,4 of turning bars.

Subsequently, the aforesaid transverse movement of the first longitudinal portion and the second longitudinal portion of the continuous webs away from each other and from said cutting line L is fixed by causing the two aforesaid longitudinal portions of the web to run on a reversing roller (9) having a high friction surface.

Preferably, the aforesaid method is performed by means of an apparatus 1 as described above.

As can be appreciated from what has been described, the apparatus according to the present invention for splitting and spreading a continuous web, as well as the method according to the present invention for splitting and spreading a continuous web, make it possible to meet the aforesaid needs and at the same time to overcome the drawbacks referred to in the introductory part of the present description with reference to the prior art. In fact, the aforesaid pairs of turning webs allow the two longitudinal portions cut from the starting continuous web to be moved away from each other without having to remove any portion of the initial continuous web.

Advantageously, it is possible to adjust the distance between the two longitudinal portions cut from the starting continuous web by varying:

- the inclination with respect to the cutting line of the first turning bar and the second turning bar of each of the aforesaid pairs of turning bars and/or

- how much the second turning bar of each of the aforesaid pairs of turning bars exceeds beyond the first turning bar.

Indicatively, for an inclination of the turning bars of about 45° with respect to the longitudinal cutting line L, the distance between the two longitudinal portions cut from the starting continuous web varies substantially proportionally to the increase of the offset of the second turning bar with respect to the first turning bar.

Obviously, a person skilled in the art can make numerous modifications and variations to what is described above so as to satisfy contingent and specific requirements, all of which are contained in the scope of protection of the invention as defined by the following claims.