Patent Description:
The present invention relates to a cutting unit and method to remove a strap from a wall of a pack, in particular of smoking articles.

The present invention finds advantageous application in a packing machine (for example a cellophane wrapping machine) for manufacturing a pack of cigarettes known as "book-pack, to which the following disclosure will make explicit reference without thereby losing generality.

A "book-pack" pack of cigarettes comprises (at least) two containers, which house respective wrapped groups of cigarettes, have respective open upper ends, and are hinged to one another so as to rotate between a closed configuration, in which the two containers are overlapping one another, and an open configuration, in which the two containers are separate; furthermore, a lid is provided which is hinged to a rear container and, when in a closed position, embraces the upper part of both containers.

The production of a "book-pack" pack of cigarettes provides for the forming of the two containers by using two corresponding blanks which are folded around the respective wrapped groups of cigarettes, coupling (overlapping) the two containers, and then folding around the two coupled (overlapped) containers a third blank that joins the two containers and forms the common lid.

After folding the third blank, it is necessary to make a cut in the bottom wall of the "book-pack" pack of cigarettes to allow the separation of the two containers (namely to allow the two containers to rotate relative to one another); normally a double cut is made (that is, two close and parallel cuts) to remove a flap (strap) from the bottom wall so as to obtain a clear separation between the two containers. For said purpose a cutting unit is used that is provided with two parallel and adjacent rotary blades, which are partially housed in a collecting chamber subject to suction, which should capture and remove the strap as soon as the strap itself has been separated from the rest of the bottom wall. However, it is not infrequent that even after the cut made by the two rotary blades, the strap remains stuck in the bottom wall and therefore is not removed by the suction; consequently, downstream of the cutting unit some "book-pack" pack of cigarettes still have the strap on the bottom which may be more or less in the original position. This can generate various problems such as the loss of the strap in the machine before applying the transparent plastic overwrap or the wrapping (with the transparent plastic overwrap) of the strap together with the pack in completely random positions giving the final user the impression of a low-quality pack of cigarettes.

<CIT> describes a packing machine for manufacturing a pack of cigarettes and comprising: a first wrapping unit for forming a first wrap containing a group of cigarettes, a second wrapping unit for forming a second wrap containing another group of cigarettes, and a third wrapping unit for joining the two wraps by means of an outer blank provided with a hinge which allows the two wraps to rotate relative to one another.

The object of the present invention is to provide a unit and a cutting method to remove a strap from a wall of a pack, in particular of smoking articles, which allow to ensure the removal of the strap after cutting and, at the same time, are easy and inexpensive to implement.

According to the present invention, a unit and a cutting method are provided to remove a strap from a wall of a pack, in particular of smoking articles, according to what is claimed in the attached claims.

The claims describe embodiments of the present invention forming an integral part of the present description.

The present invention will now be described with reference to the attached drawings, which illustrate a non-limiting embodiment thereof, wherein:.

In <FIG>, number <NUM> denotes as a whole a "book-pack" pack of cigarettes comprising two containers <NUM> and <NUM>, which house respective wrapped groups of cigarettes, which have respective open upper ends, and are hinged to one another so as to rotate between a closed configuration (illustrated in <FIG>), in which the two containers <NUM> and <NUM> overlap one another, and an open configuration (illustrated in <FIG>), in which the two containers <NUM> and <NUM> are separated; moreover, a lid <NUM> is provided which is hinged to a rear container <NUM> and, when in a closed position, embraces the upper part of both containers <NUM> and <NUM>.

According to a preferred embodiment illustrated in the attached figures, the rear container <NUM> is larger and houses a larger wrapped group of cigarettes (for example formed by two layers of seven cigarettes each), whereas the front container <NUM> is smaller and houses a smaller wrapped group of cigarettes (e.g., formed by a single layer of six cigarettes); according to a different embodiment not illustrated, the two containers <NUM> and <NUM> have the same size.

The production of the pack <NUM> of cigarettes provides for the forming of the two containers <NUM> and <NUM> by using two corresponding blanks (not illustrated) which are folded around the respective wrapped groups of cigarettes, coupling (overlapping) the two containers <NUM> and <NUM>, and then folding a third blank <NUM> (illustrated in <FIG>) around the two coupled (overlapped) containers <NUM> and <NUM> which joins the two containers <NUM> and <NUM> and forms the common lid <NUM>.

The pack <NUM> of cigarettes comprises a bottom wall <NUM> (illustrated for example in <FIG>) which is arranged on the outside, is part of the blank <NUM>, and embraces both containers <NUM> and <NUM>; namely, the bottom walls of the two containers <NUM> and <NUM> rest against the bottom wall <NUM> which covers the same.

After folding the blank <NUM> it is necessary to make a cut <NUM> (schematically illustrated in <FIG>) on the bottom wall <NUM> of the pack <NUM> of cigarettes to allow the separation of the two containers <NUM> and <NUM> (namely, to allow the two containers <NUM> and <NUM> to rotate relative to one another). In other words, initially the bottom wall <NUM> is completely intact and therefore free from any division and consequently does not allow any movement between the two containers <NUM> and <NUM>; it is therefore necessary to make the cut <NUM> to divide the bottom wall <NUM> into two parts which can be moved away from one another to allow movement between the two containers <NUM> and <NUM>. In <FIG>, number <NUM> denotes as a whole a cutting unit which, in order to make a clear separation between the two containers <NUM> and <NUM>, makes the cut <NUM> of a pack <NUM> of cigarettes which is fed along a straight path P by a conveyor <NUM>; the cut <NUM> is double (that is, it is formed by two close and parallel cuts) to remove from the bottom wall <NUM> a strap B or strip (illustrated in <FIG>) having a width of about <NUM>; namely the cutting unit <NUM> removes from the bottom wall <NUM> of a pack <NUM> of cigarettes a relatively thin central part (the strap B) to divide the two containers <NUM> and <NUM>.

As illustrated in <FIG>, the cutting unit <NUM> comprises two coaxial and horizontally arranged rotary blades <NUM>, which are mounted so as to rotate around the same vertical rotation axis <NUM> at a given distance from one another and make, in the wall <NUM> of a pack <NUM> of cigarettes that moves along the path P, a double cut <NUM> that separates the strap B from the rest of the wall <NUM> of the pack <NUM> of cigarettes. In other words, the two rotary blades <NUM> having circular shape are parallel and adjacent to one another and are mounted so as to rotate around the same vertical rotation axis <NUM> (namely, the two rotary blades <NUM> are identical and coaxial to one another); in use the two rotary blades <NUM> make, in the bottom wall <NUM> of a pack <NUM> of cigarettes that moves along the path P, two parallel cuts which separate the strap B from the rest of the bottom wall <NUM> of the pack <NUM> of cigarettes.

According to a further embodiment not illustrated, the two rotary blades <NUM> could have a predominantly vertical orientation rather than a predominantly horizontal one as illustrated in the accompanying figures. Furthermore, the two rotary blades <NUM> may also not be perfectly identical to one another (twins) and therefore may be different one from the other. Finally, the two cuts which separate the strap B from the rest of the bottom wall <NUM> and are made by the two rotary blades <NUM> may also not be perfectly parallel to one another (namely, they may be slightly convergent or divergent one from the other).

As illustrated in <FIG>, the cutting unit <NUM> comprises an actuator device <NUM> that comprises an electric motor and sets the rotation of the two rotary blades <NUM> around the rotation axis <NUM>; the two rotary blades <NUM> rotate, for example, at a rotation speed of about <NUM> rpm, which always remains constant.

As illustrated in <FIG>, the cutting unit <NUM> comprises a sucking duct <NUM> (namely, connected to a suction source) arranged to suck the strap B which has just been cut by the two rotary blades <NUM>; namely, the function of the sucking duct <NUM> is to convey by suction the strap B which has been separated from the bottom wall <NUM> by the double cut <NUM> so as to bring the strap B into a suitable collecting area (not illustrated). By way of example, the suction in the sucking duct <NUM> can be made by using an impeller or a flow accelerator. According to a preferred embodiment, an initial end of the sucking duct <NUM> has a conical shape having the minimum size in the area of the rotary blades <NUM> (namely, having a size that progressively widens moving away from the rotary blades <NUM>) so as to have the maximum depression in the area of the rotary blades <NUM>.

As illustrated in <FIG>, the cutting unit <NUM> comprises a fixed containing guide <NUM> against which the bottom wall <NUM> of the pack <NUM> of cigarettes slides and that is provided with a through slot <NUM> through which the two rotary blades <NUM> are arranged (namely, through which the two rotary blades <NUM> come into contact with the bottom wall <NUM> of the pack <NUM> of cigarettes); for said purpose, the through slot <NUM> of the fixed guide <NUM> is slightly wider than the pair of rotary blades <NUM> to allow the insertion thereof beyond the fixed guide <NUM> with minimum clearance.

As illustrated in <FIG>, the cutting unit <NUM> comprises a pneumatic device <NUM> configured to apply, between the two rotary blades <NUM>, suction, which acts upon the strap B that is separate from the bottom wall <NUM> of the pack <NUM> of cigarettes by the double cut <NUM> made by the two rotary blades <NUM>. Namely, the suction generated by the pneumatic device <NUM> tends to make the strap B adhere between the two rotary blades <NUM>, thus "tearing" the strap B from the bottom wall <NUM> of the pack <NUM> of cigarettes as the double cut <NUM> proceeds. In this way, the strap B does not remain stuck in the bottom wall <NUM> of the pack <NUM> of cigarettes, but is removed from the bottom wall <NUM> of the pack <NUM> of cigarettes as the double cut <NUM> proceeds. Furthermore, according to a preferred embodiment, the pneumatic device <NUM> is also configured to apply a jet of air between the two rotary blades <NUM> which acts upon the strap B after performing the double cut <NUM> (namely, once the double cut <NUM> has been completed) to remove the strap B from the rotary blades <NUM> and therefore allows the sucking duct <NUM> to "capture" and therefore definitively remove the strap B. In other words, the pneumatic device <NUM> is configured to alternately apply, between the two rotary blades <NUM>, suction, which acts upon the strap B during the execution of the double cut <NUM> (to remove the strap B from the bottom wall <NUM> of the pack <NUM> of cigarettes) and a jet of air which acts upon the strap B after the execution of the double cut <NUM> (to push the strap B towards the sucking duct <NUM>).

As illustrated in <FIG> and <FIG>, the cutting unit <NUM> comprises a support disc <NUM>, which is coaxial with the two rotary blades <NUM>, is interposed between the two rotary blades <NUM> so as to form a single assembly with the rotary blades <NUM> (namely, it is tightly packed with the two rotary blades <NUM>) and is mounted so as to rotate together with the two rotary blades <NUM> around the rotation axis <NUM>. The support disc <NUM> laterally delimits a plurality of chambers <NUM>, each open towards the outside and in which suction and overpressure (to generate a compressed jet of air) are applied alternately. The chambers <NUM> are evenly distributed around the rotation axis <NUM> and each have a substantially parallelepiped shape. Each chamber <NUM> is laterally delimited by the support disc <NUM> and is delimited, at the top and at the bottom, by the rotary blades <NUM>. In other words, each chamber <NUM> is formed by a through opening which passes through the support disc <NUM> from one wall to the other.

As illustrated in <FIG>, the support disc <NUM> has an outer edge <NUM> which is arranged between the two rotary blades <NUM> and is interrupted by the openings of the chambers <NUM> from which the suction and the jet of air alternately are let out; in use the strap B, separated by the double cut <NUM> from the bottom wall <NUM> of the pack <NUM> of cigarettes and attracted by the suction let out by the openings of the chambers <NUM> rests against the outer edge <NUM> of the support disc <NUM> and remains in contact with the outer edge <NUM> of the support disc <NUM> until a compressed jet is let out from the openings of the chambers <NUM>.

As illustrated in <FIG>, each chamber <NUM> has an inner end <NUM>, which is connected to a pneumatic distributor <NUM> (illustrated in <FIG> and <FIG>) and an outer end <NUM>, which is radially opposite the inner end <NUM> and is open through the outer edge <NUM> of the support disc <NUM>; therefore in use the suction and the overpressure run along each chamber <NUM> from the inner end <NUM> to the outer end <NUM> from which they are let out from the support disc <NUM> thus acting on the strap B separated by the double cut <NUM> from the bottom wall <NUM> of the pack <NUM> of cigarettes.

As illustrated in <FIG>, the two rotary blades <NUM> are perfectly identical to one another for constructive simplicity (so as not to have to make two rotary blades <NUM> slightly different from one another and therefore have a single type of perfectly interchangeable rotary blades <NUM>) and then each rotary blade <NUM> has a series of through holes <NUM>, each axially overlapped by an inner end <NUM> of a corresponding chamber <NUM>. For a single rotary blade <NUM> each through hole <NUM> connects the inner end <NUM> of a corresponding chamber <NUM> with the pneumatic distributor <NUM> arranged beyond the rotary blade <NUM>, whereas for the other rotary blade <NUM> each through hole <NUM> has no function since beyond the rotary blade <NUM> there is nothing (namely, each through hole <NUM> ends against a solid wall which seals the through hole <NUM>). Therefore, for constructive simplicity both the rotary blades <NUM> have through holes <NUM>, but only the through holes <NUM> of a single rotary blade <NUM> have the function of connecting the inner end <NUM> of the chambers <NUM> with the pneumatic distributor <NUM>, whereas the through holes <NUM> of the other rotary blade <NUM> have no function.

As illustrated in <FIG> and <FIG>, the pneumatic distributor <NUM> comprises a cylindrical body <NUM> which is still, namely does not rotate around the rotation axis <NUM>, and is coupled to the rotary blades <NUM>. In other words, an upper rotary blade <NUM> is arranged in contact with the cylindrical body <NUM> and, by rotating around the rotation axis <NUM>, it slides against the cylindrical body <NUM> that instead does not rotate around the rotation axis <NUM>. As illustrated in <FIG>, the cylindrical body <NUM> has a compartment <NUM> which is shaped like an arc of a circle, is coaxial with the rotation axis <NUM>, can be permanently connected to a suction source, and is arranged in the area of the through holes <NUM> of the rotary blades <NUM> and therefore in the area of the inner ends <NUM> of the chambers <NUM> of the support disc <NUM>. Furthermore, the cylindrical body <NUM> has a compartment <NUM> which is shaped like an arc of a circle, is coaxial with the rotation axis <NUM>, can be permanently connected to a source of compressed air, and is arranged next to the compartment <NUM> in the area of the through holes <NUM> of the rotary blades <NUM> and therefore in the area of the inner ends <NUM> of the chambers <NUM> of the support disc <NUM>.

During the rotation of the assembly formed by the rotary blades <NUM> and by the support disc <NUM>, the inner end <NUM> of each chamber <NUM> of the support disc <NUM> is isolated by about <NUM>° from both the compartments <NUM> and <NUM>, it is arranged at approximately <NUM>° in connection (through the corresponding through hole <NUM>) with the compartment <NUM> to receive suction (whereas the rotary blades <NUM> are making the double cut <NUM> which separates the strap B from the bottom wall <NUM> of the pack <NUM> of cigarettes) and it is subsequently connected by about <NUM>° (through the corresponding through hole <NUM>) with the compartment <NUM> so as to receive an overpressure (when the rotary blades <NUM> have completed the double cut <NUM> that separates the strap B from the bottom wall <NUM> of the pack <NUM> of cigarettes and therefore the strap B must be pushed towards the sucking duct <NUM>).

According to a possible embodiment, the cutting unit <NUM> comprises a cleaning device (namely a kind of scraper) which is arranged in a fixed position around the two rotary blades <NUM>, arranged at a small distance from the two rotary blades <NUM>, and has the function of cleaning the two rotary blades <NUM> from any extraneous elements (pieces of cardboard of the bottom wall <NUM>) that have become wedged between the two rotary blades <NUM> or stuck to a rotary blade <NUM>. In other words, the cleaning device separates from the rotary blades <NUM> any extraneous elements (pieces of cardboard from the bottom wall <NUM>) wedged between the two rotary blades <NUM> or stuck to a rotary blade <NUM>.

According to a possible embodiment, a control station is also provided which could be arranged along the path P downstream of the cutting unit <NUM> and is provided with a viewing device which, by acquiring and analysing one or more images of the pack <NUM> of cigarettes, is able to establish whether the strap B produced by the double cut <NUM> has been correctly eliminated. Obviously, any packs <NUM> of cigarettes which do not conform to the desired specifications (namely, in which the strap B produced by the double cut <NUM> has not been correctly eliminated) would be discarded in a discard station arranged downstream of the control station.

The embodiments described herein can be combined with one another without departing from the scope of the present claims. The cutting unit <NUM> described above has numerous advantages.

In the first place, the cutting unit <NUM> described above allows to ensure the removal of the strap B after the double cut <NUM>, avoiding that the strap B (or a piece of the strap B) can remain in contact with the bottom wall <NUM> of the pack <NUM> of cigarettes.

Furthermore, the cutting unit <NUM> described above is simple and inexpensive to implement since, compared to a similar known cutting unit, it requires modifications that are quick to make using commercial pieces or pieces that can be easily obtained with standard machining.

Claim 1:
A cutting unit (<NUM>) to remove a strap (B) from a wall (<NUM>) of a pack (<NUM>), in particular of smoking articles, which is fed along a path (P); the cutting unit (<NUM>) comprises two coaxial rotary blades (<NUM>), which are mounted so as to rotate around a same rotation axis (<NUM>) at a given distance from one another and make, in the wall (<NUM>) of the pack (<NUM>), a double cut (<NUM>), which separates the strap (B) from the rest of the wall (<NUM>) of the pack (<NUM>);
the cutting unit (<NUM>) is characterized in that it comprises a pneumatic device (<NUM>), which is configured to apply, between the two rotary blades (<NUM>), suction, which acts upon the strap (B).