Wrapping Method and Unit for Folding a Sheet of Wrapping Material about a Group of Cigarettes

The present invention relates to a wrapping method and unit for folding a sheet of wrapping material about a group of cigarettes.

A packet of cigarettes normally comprises an inner package defined by a group of cigarettes wrapped in a sheet of inner packing material; and an outer package enclosing the inner package, and which may be cup-shaped and made from a sheet of outer packing material folded about the inner package (soft packet of cigarettes), or may be defined by a rigid hinged-lid box formed by folding a rigid blank about the inner package (rigid packet of cigarettes).

In a conventional packet of cigarettes, the group of cigarettes is wrapped internally in a rectangular sheet of foil inner wrapping material with no glue, and is packed externally in a rectangular sheet of outer packing material that is stabilized using glue.

Tobacco is highly sensitive to environment. That is, in contact with the atmosphere, its organic characteristics tend to vary alongside variations in humidity (by losing or absorbing too much moisture) or due to evaporation of the volatile substances with which the tobacco is impregnated (especially in the case of aromatic cigarettes treated with spices such as cloves). To preserve the tobacco, packets of cigarettes are therefore cellophane-wrapped, i.e. wrapped in a heat-sealed overwrapping of airtight plastic material. This, however, may not always be sufficient to fully preserve the tobacco in the packet, especially if the packet is consumed some time after manufacture. Moreover, when the packet is unsealed, the overwrapping is removed, thus exposing the tobacco to the atmosphere, and, if the cigarettes are not consumed soon after the packet is unsealed, the organic characteristics of the remaining cigarettes may deteriorate.

In an attempt to eliminate this drawback, patent U.S. Pat. No. 4,300,676A1 proposes a rigid packet of cigarettes, in which the inner package is airtight, and comprises a sheet of airtight heat-seal wrapping material having a cigarette extraction opening closed by a reusable cover flap.

It has been observed that folding the sheet of inner wrapping material about the group of cigarettes may damage the ends of the cigarettes and result in localized deformation (of both the filter-tipped and plain ends, i.e. where the tobacco is exposed), and/or tobacco spill (i.e. tobacco fallout, obviously only from the plain ends). This applies in particular to the corner cigarettes in the group, though damage is also evident in all the outermost cigarettes, i.e. located along the fold lines of the sheet of inner wrapping material. Folding a sheet of airtight inner wrapping material is particularly harmful, by being thicker (and therefore stiffer) than conventional sheets of foil wrapping material. Heat sealing the superimposed portions of the sheet of inner wrapping material may also damage the cigarettes underneath, in that, to achieve a good-quality (i.e. airtight) seal quickly (modern packing machines operate at a rate of 500 packets a minute, which means heat sealing must be completed in a fraction of a second), the superimposed portions must be subjected to considerable pressure—which is inevitably transmitted to and may cause permanent deformation of the cigarettes underneath—and must be heated to a high temperature, with the obvious danger of possibly overheating the tobacco in the cigarettes underneath (thus resulting in local drying and alteration of the organic characteristics of the tobacco).

It is an object of the present invention to provide a wrapping method and unit for folding a sheet of wrapping material about a group of cigarettes, which method and unit are cheap and easy to implement and designed to eliminate the above drawbacks.

According to the present invention, there are provided a wrapping method and unit for folding a sheet of wrapping material about a group of cigarettes, as claimed in the accompanying Claims.

Number 1 in FIG. 1 indicates as a whole a package of cigarettes, e.g. of the type described in patent U.S. Pat. No. 4,300,676A1. Package 1 of cigarettes encloses a parallelepiped-shaped group 2 of cigarettes (shown schematically in FIGS. 2-6), and has at the top and front a cigarette extraction opening 3 bounded by a tear line 4 and extending over a portion of a front wall of package 1 and a portion of a top wall of package 1. To unseal package 1, the user tears the package along tear line 4 to eliminate the package at extraction opening 3 and so access the cigarettes in group 2 through extraction opening 3.

As described in atent U.S. Pat. No. 4,300,676A1, package 1 of cigarettes as described above may be inserted inside a known rigid, hinged-lid cigarette packet, and extraction opening 3 may be closed by a reusable open-close cover flap fixed to package 1 using non-dry, re-stick adhesive.

Package 1 is formed by folding a sheet 5 of wrapping material (shown schematically in FIGS. 2-6), which is rectangular, is made of airtight, heat-seal plastic material (or composite multilayer material with at least one layer of plastic material), and is folded directly about and in direct contact with group 2 of cigarettes. Once sheet 5 of wrapping material is folded about group 2 of cigarettes to form package 1, the shape of package 1 is stabilized by heat sealing the superimposed portions of sheet 5 of wrapping material.

Before being folded about group 2 of cigarettes, sheet 5 of wrapping material is cut to define extraction opening 3, and is then fitted, if necessary, with the cover flap gummed on the underside, i.e. the underside surface of the cover flap is coated with re-stick adhesive, which glues the portion of sheet 5′of wrapping material inside extraction opening 3 permanently to the cover flap, and, outside extraction opening 3, glues sheet 5 of wrapping material detachably to the cover flap.

In another embodiment, not shown, package 1 comprises a U-shaped cardboard stiffener inserted inside package 1, contacting group 2 of cigarettes, and which comprises a rectangular central panel positioned contacting a bottom wall of group 2 defined by the ends of the cigarettes (or positioned contacting a front wall of group 2 defined by the cylindrical lateral walls of the cigarettes); and two lateral wings connected to the central panel along two fold lines and positioned contacting the minor lateral walls of group 2 defined by the cylindrical lateral walls of the cigarettes. FIGS. 2-6 show steps in the folding of sheet 5 of wrapping material about group 2 of cigarettes, which has two opposite lateral walls 6a, 6b defined by the cylindrical lateral walls of the cigarettes, and two opposite end walls 7a, 7b defined by the ends of the cigarettes.

To begin with, end wall 7b of group 2 of cigarettes is brought into contact with the flat sheet 5 of wrapping material (FIG. 2) so that the sheet of wrapping material folds into a U about group 2 of cigarettes (FIG. 3). It is important to note that sheet 5 of wrapping material is fed asymmetrically in front of group 2 of cigarettes, so as to form two differently arranged portions 8 and 9 of different lengths. As shown in FIG. 3, once folded into a U about group 2 of cigarettes, sheet 5 of wrapping material has an outer portion 8 projecting from group 2 of cigarettes; and an inner portion 9 resting on lateral wall 6a of group 2. As shown in FIG. 4, inner portion 9 is folded 90° with respect to lateral wall 6a of group 2, so as to be perpendicular to lateral wall 6a. As shown in FIG. 5, outer portion 8 is folded 90° onto end wall 7a of group 2. As shown in FIG. 6, outer portion 8 is folded into an L onto lateral wall 6a of group 2 and onto inner portion 9 perpendicular to lateral wall 6a, so as to superimpose outer portion 8 and inner portion 9 and impart a tubular shape to sheet of wrapping material. The superimposed portions of outer portion 8 and inner portion 9 are heat sealed to stabilize the tubular shape of sheet 5 of wrapping material; and, finally, the heat-sealed, superimposed portions 8 and 9 are folded 90° onto lateral wall 6a of group 2 (as shown partly in FIG. 1).

Number 10 in FIG. 7 indicates as a whole a packing machine for producing the FIG. 1 package 1 of cigarettes as shown in FIGS. 2-6.

Packing machine 10 comprises a group-forming unit (not shown in FIG. 7) for successively forming groups 2 of cigarettes; and a wrapping unit 11 (shown in FIG. 7) for wrapping and heat sealing a respective sheet 5 of wrapping material about each group 2 of cigarettes. It is important to note that packing machine 10 could simply comprise the group-forming unit (not shown in FIG. 7) and wrapping unit 11; in which case, package 1 as described above would be a marketable finished product. Alternatively, packing machine 10 could comprise a further known packing station for packing each package 1 in a respective outer package, which may be cup-shaped and comprise a sheet of outer packing material folded about package 1 (soft packet of cigarettes), or may comprise a rigid, hinged-lid box formed by folding a rigid blank about package 1 (rigid packet of cigarettes).

Wrapping unit 11 in FIG. 7 comprises a wrapping wheel 12 which receives groups 2 of cigarettes from the group-forming unit (not shown), rotates in steps (clockwise in FIG. 7) about a horizontal axis of rotation 13 perpendicular to the FIG. 7 plane, and supports a number of peripheral pockets 14, each for housing a group 2 of cigarettes.

Each pocket 14 on wrapping wheel 12 receives a group 2 of cigarettes together with a corresponding sheet 5 of wrapping material at an input station 15. More specifically, sheet 5 of wrapping material is fed to input station 15 by a feed device 16, so as to be positioned in front of the inlet of pocket 14 and perpendicular to the travelling direction of group 2 of cigarettes; and, as group 2 is pushed inside pocket 14, sheet 5 of wrapping material is intercepted by group 2 and folds gradually into a U about group 2 as this is inserted inside pocket 14. As stated, each sheet 5 of wrapping material is fed to input station 15 so as to be positioned asymmetrically in front of the inlet of pocket 14 of wrapping unit 12. In other words, the centreline of sheet 5 of wrapping material is offset with respect to the centreline of pocket 14 of wrapping unit 12 at input station 15, so that, when folded into a U about group 2, sheet 5 of wrapping material has an outer portion 8 projecting from pocket 14, and an inner portion 9 opposite outer portion 8 and resting on lateral wall 6a of group 2 inside pocket 14.

Each pocket 14 has a U-shaped longitudinal section, and comprises an end wall, and two opposite parallel lateral walls. One lateral wall of each pocket 14, contacting lateral wall 6a of corresponding group 2 of cigarettes, is shorter than the opposite lateral wall, so as to leave inner portion 9 of sheet 5 of wrapping material exposed, and terminates with a transverse suction support 17 perpendicular to the lateral wall and designed to lift and retain the inner portion 9 of sheet 5 of wrapping material by suction. More specifically, a conduit 18 (shown more clearly in FIGS. 8 and 9) terminates at transverse support 17 and is connectable to a suction source. At input station 15, once sheet 5 of wrapping material is folded into a U about group 2, inner portion 9 of sheet 5 of wrapping material is folded 90° with respect to lateral wall 6a of group 2, so that inner portion 9 is perpendicular to lateral wall 6a, and is retained by suction in this position by and resting against transverse support 17. In other words, folding inner portion 9 ninety degrees with respect to lateral wall 6a of group 2 also comprises drawing inner portion 9 by suction onto transverse suction support 17 of pocket 14. It is important to note that inner portion 9 may be folded 90° with respect to lateral wall 6a of group 2 solely by suction by transverse support 17, or by combining suction by transverse support 17 with the action of a radially-moving folding device (not shown).

A circular folding rail 19 immediately downstream from input station 15 provides for folding outer portion 8 ninety degrees onto end wall 7a of group 2, as shown in FIG. 5. More specifically, as pocket 14 rotates out of input station 15, outer portion 8 strikes folding rail 19 and is thus folded.

At a folding and heat seal station 20 downstream from input station 15, the tubular shape of sheet 5 of wrapping material is completed and stabilized by heat sealing.

Folding and heat seal station 20 comprises a movable folding device 21, which is movable radially (i.e. perpendicular to axis of rotation 13) between a rest position (FIG. 7), in which movable folding device 21 is positioned outwards of the rotation path of pockets 14, and a folding position (FIGS. 8 and 9), in which movable folding device 21 engages the group 2 of cigarettes inside pocket 14. Movable folding device 21 is L-shaped, and comprises a tangent pad 22 which, in the folding position (FIGS. 8 and 9), rests against end wall 7a of group 2; and a radial blade 23 for folding outer portion 8 of sheet 5 of wrapping material. In other words, in the folding position (FIGS. 8 and 9), movable folding device 21 is positioned contacting lateral wall 6a of group 2, with outer portion 8 of sheet 5 of wrapping material in between, and grips inner portion 9 and outer portion 8 against transverse support 17.

As shown in FIG. 8, movable folding device 21 folds outer portion 8 into an L onto lateral wall 6a of group 2 and against inner portion 9 perpendicular to lateral wall 6a and resting against transverse support 17, so as to superimpose outer portion 8 and inner portion 9 and impart a tubular shape to sheet 5 of wrapping material. The purpose of pad 22 is to press sheet 5 of wrapping material against end wall 7a of group 2, and so prevent creasing of sheet 5 at end wall 7a when folding outer portion 8.

Folding and heat seal station 20 also comprises a movable sealing device 24 which rotates between a rest position (FIG. 7), in which movable sealing device 24 is located outwards of the rotation path of pockets 14, and a sealing position (FIG. 9), in which movable sealing device 24 grips the superimposed portions of outer portion 8 and inner portion 9 against transverse support 17, and heat seals them by applying heat and pressure.

The FIG. 10-12 embodiment differs from the one in FIGS. 7-9 as regards the design of movable folding device 21. In the FIG. 7-9 embodiment, movable folding device 21 combines pad 22 and blade 23, and translates radially between the rest position (FIG. 7) and the folding position (FIGS. 8 and 9); whereas, in the FIG. 10-12 embodiment, movable folding device 21 only comprises blade 23, and rotates between the rest position (FIG. 10) and the folding position (FIGS. 11 and 12), and pad 22 is separate from and independent of movable folding device 21, and translates radially between the rest position (FIG. 10) and the folding position (FIGS. 11 and 12).

At an output station 25 downstream from folding and heat seal station 20, group 2 of cigarettes, together with the tubular sheet 5 of wrapping material, is expelled from pocket 14 of wrapping wheel 12 and fed to further known folding devices (not shown), which finish folding sheet 5 of wrapping material about group 2 of cigarettes to form package 1, the finished form of which is stabilized by heat sealing. The further known folding devices (not shown) may, for example, be of the type described in Patent Application EP2008935A1.

In wrapping unit 11 as described above, folding sheet 5 of wrapping material (particularly outer portion against inner portion 9) produces very little mechanical stress on, and therefore no damage to, the cigarettes in group 2. Moreover, when heat sealing the superimposed portions of portions 8 and 9, sheet 5 of wrapping material, as opposed to being pressed against group 2 of cigarettes, is gripped between two metal parts (transverse support 17 and sealing device 24). Which means the superimposed portions of portions 8 and 9 can be heat sealed by applying considerable pressure and at high temperature, with no damage to the cigarettes in group 2, thus ensuring a high-quality, fast seal (compatible with the demands of modern, fast-operating packing machines).