WO2014188397A1

WO2014188397A1 - A packing method and packing machine for producing a sealed package

Info

Publication number: WO2014188397A1
Application number: PCT/IB2014/061678
Authority: WO
Inventors: Fulvio Boldrini
Original assignee: G.D Societa' Per Azioni
Priority date: 2013-05-24
Filing date: 2014-05-23
Publication date: 2014-11-27
Also published as: ITBO20130255A1

Abstract

Packing method and packing machine (18) for producing a sealed package (3); is envisaged to: wrap a sheet (7) of packing material longitudinally into a tube shape about a product to form a tubular package; heat seal the tubular package longitudinally, by means of a longitudinal heat seal device (48), to stabilize the shape of the tubular package; heat seal the tubular package transversely, by means of a transverse heat-seal device (49), to form two transverse heat seals (10) closing opposite ends of the tubular package at lateral walls of the product; interrupt the formation of at least one transverse heat seal (10), the transverse heat seal (10) itself over a limited portion of the tubular package, to leave a vent channel (67) extending astride the transverse heat seal (10) that connects the inside of the sealed package (3) to the outside; and close the vent channel (67) after the transverse heat seals (10) are formed.

Description

"A PACKING ME THOD AND PACKING MACHINE FOR PRODUCING A SEALED PACKAGE "

TECHNICAL FIELD

The present invention relates to a packing method and to a packing machine for producing a sealed package.

The present invention finds advantageous application to a sealed package of cigarettes and provided with a reclosable extraction opening, to which the following description will make explicit reference without loss of generality.

PRIOR ART

Normally, a rigid package of cigarettes with a hinged lid comprises an inner package which encloses a group of cigarettes and a rigid outer casing which houses the inner package in the inside thereof.

Recently, in order to better preserve the organoleptic characteristics of the cigarette tobacco has been proposed the use of a sealed inner package, which is formed by folding and heat-sealing a sheet of waterproof packing material. To allow the extraction of the cigarettes, the inner package is provided with a sealed extraction opening which is normally covered by an adhesive panel of the type "open and close"; in particular, the adhesive panel is provided with non-dry, re- stick adhesive which allows to fix several times the adhesive panel in a closing position of the cigarette extraction opening .

Normally, the sealed inner package is internally provided with a rigid stiffener which has essentially the function of giving greater stiffness and greater shape stability to the sealed inner package so as to prevent the sealed inner package from collapsing on itself after removing a part of the cigarettes enclosed in the inside thereof complicating the extraction of the remaining cigarettes and, in particular, making extremely complicated the opening and the subsequent closing of the adhesive panel. A further function of the stiffener is to maintain the group of cigarettes in the correct conformation, as well as provide adequate mechanical protection to the group of cigarettes, during the formation of the sealed inner package (i.e. during the folding/heat sealing of the sheet of packing material) .

The patent application WO2013053408A1 describes a sealed inner package wherein the sheet of packing material has through vent openings that are used to better evacuate (fully or partially) the air enclosed in the sealed package 3 before the airtight sealing of the sealed package 3 itself. During the formation of the transverse seals of the sealed package, the vent openings are closed, making the sealed package itself airtight sealed. However, it was observed that the through vent openings described in patent application WO2013053408A1 do not always allow a correct evacuation of the air enclosed in the sealed package before the airtight sealed closing of the sealed package itself.

DESCRIPTION OF THE INVENTION

Purpose of the present invention is to provide a packing method and a packing machine for producing a sealed package, which packing method and packing machine are devoid of the drawbacks described above and are, at the same time, easy and economical to produce.

According to the present invention a packing method and a packing machine for producing a sealed package are provided, as claimed in the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

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

Figure 1 is a front perspective view and in a closed configuration of a package of cigarettes provided with a sealed package obtained according to the present invention;

Figure 2 is a front perspective view of the package of cigarettes of Figure 1 in a partially open configuration;

Figure 3 is a front perspective view of the package of cigarettes of Figure 1 in a fully open configuration;

- Figure 4 is a front perspective view of a sealed package of the package of Figure 1;

- Figure 5 is a rear perspective view of the sealed package of Figure 4;

Figure 6 is a front perspective view of a group of cigarettes contained in the inner package of Figure 4;

- Figure 7 is a front perspective view of the sealed package of Figure 4 prior to an end folding of the two fin shaped lateral welds;

- Figure 8 is a plan view of a heat-sealable sheet of packing material used to obtain the sealed package of Figure 4;

- Figure 9 is a front perspective view of a stiffener enclosed in the inner package of Figure 4;

- Figure 10 is a rear perspective view of the stiffener of Figure 8;

- Figure 11 is a front perspective view of the stiffener of Figure 8 prior to an end folding of a central stabilizing tab;

- Figure 12 is a view of a blank used to obtain the stiffener of Figure 8;

- Figure 13 is a plan schematic view of an initial packing unit of a packing machine which obtains the package of cigarettes of Figure 1;

- Figure 14 is a schematic side view of the initial packing unit of Figure 13;

- Figure 15 is a schematic perspective view of part of the initial packing unit of Figure 13;

- Figure 16 is a schematic perspective view of an application station of the initial packing unit of Figure 13; - Figure 17 is a schematic view of a feeding device of the application station of Figure 16;

- Figures 18 and 19 are two schematic views and in lateral section of part of the application station of Figure 16 in two different operating configurations;

- Figures 20 and 21 are two schematic front views of part of the application station of Figure 16 in two different operating configurations;

- Figure 22 is a schematic plan view of a transferring device of the initial packing unit of Figure 13;

- Figure 23 is a schematic front view of a transverse heat seal device and a folding wheel of the initial packing unit of Figure 13;

Figures 24 and 25 are two schematic front views, and in enlarged scale of the transverse heat seal device of Figure 13;

- Figure 26 is a front perspective view of the sealed package of Figure 4 prior to an end folding of the two fin shaped lateral welds and in the presence of an air vent channel; and

- Figure 27 is a schematic view of a heated surface of a heat seal head which performs a transversal heat seal of the sealed package of Figure 26.

PREFERRED EMBODIMENTS OF THE INVENTION

In Figures 1, 2 and 3 number 1 indicates as a whole a rigid package of cigarettes. The package 1 of cigarettes comprises an outer container 2 made of cardboard or rigid paperboard and cup-shaped and a sealed package 3 (better illustrated in Figures 4 and 5) housed inside the container 2.

The outer container 2 has an open top end and is provided with a lid, which is cup-shaped and is hinged to the outer container 2 along a hinge (shown in Figure 3) to rotate, with respect to the outer container 2, itself, between an opening position (illustrated in Figure 2) and a closing position (shown in Figures 1 and 3) of the open top end. The lid, when in its closing position, gives the outer container 2 a rectangular parallelepiped shape having a top wall and a bottom wall opposite and parallel one with respect to the other, a front wall and a rear wall (wherein the hinge is formed) opposite and parallel one with respect to the other, and two lateral walls opposite and parallel one with respect to the other. Between the lateral walls and the front and rear walls four longitudinal edges are defined, while between the top and bottom walls and the front, rear and lateral walls eight transverse edges are defined.

As illustrated in Figures 4 and 5, the sealed package 3 encloses a group 4 of cigarettes (shown in Figure 6) of parallelepiped shape and has a top and a front cigarettes extraction opening 5 (shown in dashed lines in Figure 4); the cigarette extraction opening 5 is arranged centrally, is closed by an adhesive panel 6 of the type "open & close" and affects a portion of a front wall of the sealed package 3 and a portion of a top wall of the sealed package 3. The adhesive panel 6 normally adheres to the part of the sealed package 3 arranged about the extraction opening 5 to close (seal) the extraction opening 5 itself and may be temporarily lifted to free the extraction opening 5, and then allows the extraction of a cigarette through the extraction opening 5 itself.

The sealed package 3 is obtained by wrapping a sheet 7 of waterproof and heat-sealable packing material (shown in Figure 8), which has a rectangular shape and has an incision which is "U" shaped and defines the extraction opening 5. To the sheet 7 of packing material an adhesive panel 6 is glued, which has a rectangular shape and completely covers the incision (i.e. the extraction opening 5) ; between the adhesive panel 6 and the sheet 7 of packing material a non-dry, re-stick adhesive is interposed (i.e. which always remains sticky), i.e. an adhesive which allows even after a long time to separate the adhesive panel 6 from the sheet 7 of packing material and then ^

- 6 - to assemble again the adhesive panel 6 to the sheet 7 of packing material for a greater number of times. According to a preferred embodiment, the non-dry, re-stick adhesive is previously applied to an inner face of the adhesive panel 6 before fitting the adhesive panel 6 to the sheet 7 of packing material .

The presence of the re-stick adhesive between the panel 6 and the sheet 7 of packing material determines the permanent gluing (i.e. that also in use is never separated) of the portion of the sheet 7 of packing material enclosed within the incision (i.e. in correspondence with the extraction opening 5) to the adhesive panel 6; therefore, when the adhesive panel 6 is lifted from the sheet 7 of packing material the portion of the adhesive panel 6 enclosed within the incision (i.e. in correspondence of the extraction opening 5) is lifted together with the adhesive panel 6 freeing the extraction opening 5. Moreover, the presence of the re-stick adhesive between the adhesive panel 6 and the sheet 7 of packing material determines a temporary gluing (i.e. that in use is separated) between the portion of the sheet 7 of packing material surrounding the incision (i.e. that surrounds the extraction opening 5) and the adhesive panel 6 so as to normally maintain the adhesive panel 6 into contact with the sheet 7 of packing material to close (seal) the extraction opening 5.

The adhesive panel 6 is provided with a graspable tab 8, which is free of re-stick adhesive on the side facing the sheet 7 of packing material (i.e., the surface facing the sheet 7 of packing material) and is arranged in the vicinity of the extraction opening 5 and below the extraction opening 5 itself. The graspable tab 8 is likely to facilitate the gripping of the adhesive panel 6 at the time of lifting the adhesive panel 6 itself; in other words, to lift the adhesive panel 6, a user can easily grab a graspable tab 8, which is in no way fixed to the sheet 7 of packing material in contrast to the rest of the adhesive panel 6.

As illustrated in Figures 4 and 5, the sealed package 3 is stabilized, or is maintained in the folded configuration, by a fin shaped central heat seal 9 (or longitudinal heat seal 9) arranged at a front wall and lateral walls of the sealed package 3 and by means of two fin shaped lateral welds 10 (or transverse welds 10) that are arranged at the lateral walls of the sealed package 3. The fin shaped central heat seal 9 determines the formation of a tubular package having two open ends at the lateral walls of the sealed package 3 and is initially perpendicular to the front wall of the sealed package 3; subsequent to its formation, the fin shaped central heat seal 9 is folded 90° onto the front wall of the sealed package 3 (as illustrated in Figures 4 and 7) . The two fin shaped lateral welds 10 determine the lateral closure of the tubular package and are initially perpendicular to the corresponding lateral walls of the sealed package 3 (as shown in Figure 7); subsequently to the formation thereof, the two fin shaped lateral welds 10 are folded 90° onto the corresponding lateral walls of the sealed package 3 (as illustrated in Figures 4 and 5) .

As illustrated in Figure 7, each fin shaped lateral heat seal 10 is obtained by determining the formation of two triangular end tabs 11 which protrude from opposite sides from the corresponding lateral wall of the sealed package 3; after folding each fin shaped lateral heat seal 10 by 90° onto the corresponding side wall of the sealed package 3, the two triangular end tabs 11 are folded 180° onto the corresponding side wall of the sealed package 3 and over the previously folded fin shaped lateral heat seal 10. According to a possible embodiment, each triangular end tabs 11 is heat- sealed to the corresponding side wall of the sealed package 3 to remain in the desired position illustrated in Figures 4 and 5; alternatively, each triangular end tabs 11 may be maintained in the desired position illustrated in Figures 4 and 5 only by the presence of the outer container 2 which surrounds the sealed package 3.

As illustrated in Figures 9 and 10, the sealed package 3 comprises a stiffener 12, which is made of cardboard or rigid paperboard (entirely similar to the cardboard or rigid paperboard forming the outer container 2), is "U" shaped and is arranged within the sealed package 3 contacting the group 4 of cigarettes.

The stiffener 12 comprises a front wall 13 of rectangular shape arranged into contact with a front wall of the group 4 of cigarettes, two lateral walls 14, which are connected to opposite sides of the front wall 13 and are arranged into contact with the lateral walls of the group 4 of cigarettes, and a bottom wall 15 arranged into contact with the bottom wall of the group 4 of cigarettes. The front wall 13 which has a top, U-shaped window, and facilitates the extraction of the cigarettes from the group 4 of cigarettes as it leaves exposed a top area of the front wall of the group 4 of cigarettes at the extraction opening 5. Moreover, the stiffener 12 comprises two lateral stabilizing tabs 16 which are connected to the lateral walls 14 and are folded 90° onto an outer surface of the bottom wall 15 (or from the opposite side with respect to the group 4 of cigarettes) , and a central stabilizing tab 17 which is connected to the bottom wall 15 and is folded 180° onto the outer surface of the bottom wall 15 (or from the opposite side with respect to the group 4 of cigarettes) and over the two lateral stabilizing tabs 16 previously folded. To better highlight the folding of the stabilizing tabs 16 and 17, in Figure 11 is illustrated the stiffener 12 before the final folding of the central stabilizing tab 17, or before placing the central stabilizing tab 17 onto the outer surface of the bottom wall 15 (or from the opposite side with respect to the group 4 of cigarettes) and over the two lateral stabilizing tabs 16 previously folded.

As best shown in Figure 12, the two lateral stabilizing tabs 16 are connected to the corresponding lateral walls 14 of the stiffener 12 along two transverse fold lines and the central stabilizing tab 17 is connected to the bottom wall 15 of the stiffener 12 along a further transverse fold line which is initially parallel to the other two transverse fold lines.

During the handling of the whole constituted by the group 4 of cigarettes and by the stiffener 12, it is possible to stabilize the stiffener 12 (i.e. to prevent that the stiffener 12 abandons the desired folded configuration) simply by pushing from the outside (i.e. on the opposite side with respect to group 4 of cigarettes) on the bottom wall 15 (or better on the stabilizing tabs 16 and 17 that cover the outside of the bottom wall 15) by way of a pressure pad (described in detail below) ; in fact, pushing from the outside (i.e., from the opposite side with respect to the group 4 of cigarettes) on the bottom wall 15 by means of a pressure pad the stabilizing tabs 16 and 17 will be kept in the correct position onto the bottom wall 15. In other words, pushing from the outside (i.e., from the opposite side with respect to the group 4 of cigarettes) on the bottom wall 15 will maintain the stabilizing tabs 16 and 17 pinched between the pressure pad and the bottom wall 15 "freezing" the desired folded configuration of the stiffener 12.

When the sealed package 3 is completed, i.e. at the end of the formation of the sealed package 3, the function of the stiffener 12 is to give greater stiffness and greater shape stability to the sealed package 3 so as to prevent the sealed package 3 from collapsing on itself after removing a part of the cigarettes enclosed in the sealed package 3 itself making the extraction of the remaining cigarettes complicated and, in particular, making the opening and the subsequent closing of the adhesive panel 6 extremely complicated. During the formation of the sealed package 3, the functions of the stiffener 12 are to provide adequate mechanical protection to cigarettes and to simpli fy/ improve the handling of the group 4 of cigarettes (i.e. to prevent the group 4 of cigarettes from coming apart) .

In Figure 13, with the number 18 is indicated as a whole a packing machine which obtains the package 1 of cigarettes described above.

The packing machine 18 comprises a packing unit 19 which provides the initial sealed package 3 by forming the group 4 of cigarettes and wrapping and heat sealing the sheet 7 of packing material about the group 4 of cigarettes and an end packing unit 20 (known and illustrated in a very schematic way) which forms the outer container 2 by wrapping one after the other a collar and a blank about the sealed package 3.

The initial packing unit 19 comprises a group-forming station 21 wherein the group 4 of cigarettes is formed, an application station 22 wherein the group 4 of cigarettes is fitted with a stiffener 12, and a packing station 23 wherein the sheet 7 of packing material is wrapped about the group 4 of cigarettes to form the sealed package 3.

As illustrated in Figure 15, the group-forming station 21 comprises a vertical hopper 24 provided with a plurality of lower outlet mouths, and a group-forming conveyor belt 25 which supports a plurality of group-forming pockets 26 and travels with continuous motion for moving the group-forming pockets 26 themselves along a group-forming path PI (shown in figure 16) which extends in front of the outlet mouths of the hopper 24. As illustrated in Figure 16, the group-forming conveyor 25 comprises a belt which is closed as a ring and wraps about two motorized end pulleys; accordingly, the group- forming path PI is "U" shaped and has a lower rectilinear branch which extends horizontally and is arranged in front of the outlet mouths of the hopper 24, and a top rectilinear branch which passes through the application station 22 and ends at a transferring device 36 which transfers each group 4 of cigarettes enclosed in a group-forming pocket 26 in a wrapping seat 27 of a packing conveyor 28 which travels with continuous motion in parallel and in synchronism with the group-forming conveyor 25 for moving the seats 27 of packing material along a rectilinear and horizontal packing path P2.

According to a preferred embodiment, the two motorized end pulleys, about which the group-forming conveyor belt 25 wraps, are movable with a reciprocating linear motion parallel to the rectilinear sections of the group-forming path PI; at the same time, the rotation speed of the two motorized end pulleys is variable in time, in synchronism with their reciprocating linear motion. The combination of the pulleys reciprocating linear motion with the variation of the rotation speed of the pulleys themselves allows to temporarily stop the group- forming pockets 26 that are arranged in front of the outlet mouths of the hopper 24 (i.e. the group-forming pockets 26 that are arranged in the lower rectilinear branch of the group-forming path PI) to allow transferring the groups 4 of cigarettes from the outlets mouths of the hopper 24 to the group-forming pockets 26; at the same time, the combination of the reciprocating linear motion of the pulleys with the variation of the rotation speed of the pulleys themselves allows to keep constant the feeding speed of the group-forming pockets 26 in the top branch of the rectilinear group-forming path PI, so that the group-forming pockets 26 which are arranged in the top rectilinear branch of the group-forming path PI are always in phase and synchronized with the packing seats 27 of the packing conveyor 28 (fed with continuous motion along the packing path P2) . The application station 22 comprises an application belt conveyor 29 that is arranged next to the group-forming conveyor 25 so as to feed the stiffener 12 in parallel to the top rectilinear branch of the group-forming path PI. According to a preferred embodiment, the application conveyor 29 is provided with suction and holds the stiffener 12 by suction into contact with a lower surface of the conveyor belt; in other words, and as clearly shown in figure 18 and 19, the application conveyor 29 is arranged over the group-forming conveyor 25 and the stiffener 12 is hung by suction below the application conveyor 29.

As illustrated in Figure 17, a feeding device 30 is provided which unwinds from a reel 31, a continuous strip of packing material that is fed along a rectilinear and horizontal feeding path P3 which extends perpendicularly to the application conveyor 29. In particular, the continuous strip of packing material is passed through an embossing and cutting device 32 to form the pre-weakened fold lines in each stiffener 12, and then to separate from the continuous belt itself individual stiffeners 12. At the end of the feeding path P3 a lifter 33 is arranged which is movable vertically (i.e. perpendicular to the feeding path P3 and to the application conveyor 29) with reciprocating motion; the lifter 33 pushes the stiffener 12 of the final portion of feeding path P3 to the application conveyor 29 to which the stiffener 12 adheres by suction.

As illustrated in Figures 18 and 19, the application conveyor 29 of the application station 22 cooperates with the group- forming conveyor 25 for resting the stiffener 12 on the group- forming pocket 26 along the top rectilinear branch of the group-forming path PI. While the stiffener 12 rests on the group-forming pocket 26 (i.e. along the top rectilinear branch of the group-forming path PI) a pair of folding devices 34 and 35 (illustrated schematically in Figure 16) arranged in succession fold (as described previously and as illustrated in Figures 9 and 10) the stiffener 12 partially about the group- forming pocket 26, and then partially about the group 4 of cigarettes enclosed in the group-forming pocket 26. Finally, at the end of the group-forming path PI, a transferring device 36 (illustrated schematically in Figure 16) extracts together and simultaneously the stiffener 12 and the group 4 of cigarettes from the group-forming pocket 26 to insert the stiffener 12 and the group 4 of cigarettes in the corresponding packing pocket 27 of the packing conveyor 28.

As illustrated in Figures 18 and 19, the group-forming pocket 26 comprises an initial part 37 arranged at an inlet opening of the group 4 of cigarettes (i.e. in correspondence of the opening through which the group 4 of cigarettes enters the group-forming pocket 26), and an end part 38 arranged at an outlet opening of the group 4 of cigarettes (i.e. in correspondence of the opening through which the group 4 of cigarettes exit the group-forming pocket 26) . The stiffener 12 is supported only on the end part 38 of the group-forming pocket 26 so that initially the stiffener 12 is longitudinally misaligned with respect to the group 4 of cigarettes and is longitudinally aligned with the group 4 of cigarettes only when extracted from the group-forming pocket 26 along with the group 4 of cigarettes. According to a preferred embodiment, the group-forming pocket 26 is tubular shaped with a rectangular section and comprises a bottom wall and a top wall opposite and parallel one with respect to the other (visible in Figures 18 and 19) and two lateral walls opposite and parallel one with respect to the other (not visible in Figures 18 and 19) ; the top and lateral wall thickness of the end part 38 is less than the thickness of the top and lateral walls of the initial portion 37 so that the stiffener 12 resting on the final part 38 of the group-forming pocket 26 is arranged in close proximity to the group 4 of cigarettes. As illustrated in Figures 18 and 19, a first end of the front wall 13 of the stiffener 12 is placed on the group- forming pocket 26 and a second end of the front wall 13 of the stiffener 12 opposite to the first end is retained by suction by the application conveyor 29 which travels parallel to the group-forming conveyor 25. A lower surface of the front wall 13 of the stiffener 12 rests on the group-forming pocket 26 (in particular on the top wall of the group-forming pocket 26), while a top surface opposite the lower surface of the front wall 13 of the stiffener 12 is in contact with the application conveyor 29 that holds the latter by suction.

Once the stiffener 12 rests on the group-forming pocket 26, the folding device 34 folds the stiffener 12 about the group- forming pocket 26 while the front wall 13 of the stiffener 12 is retained by the application conveyor 29. The folding device 34 comprises a folding device 39 that travels vertically (i.e. transversely to the group-forming path PI) between a resting position (shown in Figures 18 and 20) wherein the folding device 39 is away from the stiffener 12 and a working position (shown in Figures 19 and 21) wherein the folding device 39 spans over the stiffener 12 itself. As previously mentioned, the group-forming pocket 26 is fed continuously along the top branch of the group-forming path PI; accordingly, the folding device 39 is also movable parallel to group-forming path PI to follow the group-forming pocket 26 along a portion of group- forming path PI itself.

According to a preferred embodiment shown in Figures 18-21, the folding device 39 comprises four "legs" 40 (i.e., four folding elements 40) oriented vertically spanning over the front and the rear of the application conveyor 29 and embracing laterally the stiffener 12; when the folding device 39 moves from the resting position (shown in Figures 18 and 20) to the working position (shown in Figures 19 and 21), the four folding elements 40 fold 90° the lateral walls 14 of the stiffener 12 with respect to the front wall 12 of the stiffener 12. Moreover, the folding device 39 comprises a further folding element 41 (shown in Figures 20 and 21) which is arranged transversely to two rear folding elements 40; when the folding device 39 moves from the resting position (shown in Figures 18 and 20) to the working position (shown in Figures 19 and 21), the further folding element 41 folds 90° the rear wall 15 of the stiffener 12 with respect to the front wall of the stiffener 12.

According to a preferred embodiment shown in Figures 18-21, the folding device 39 cooperates with a counter-folding device 42 that is "U" shaped and, when the folding device 39 moves towards the working position (shown in Figures 19 and 21), it rests against an inner surface of the front wall 13 of the stiffener 12 from the opposite side with respect to the same folding device 39. In this way, the stiffener 12 is folded between the folding device 39 and the counter-folding device 42 to improve the folding quality. Obviously, also the counter-folding device 42 is movable parallel to the group- forming path PI to follow, together and in a synchronized manner with the folding device 39, the group-forming pocket 26 along a section of the group-forming path PI itself.

Summarizing the above described, the lower wall 15 of the stiffener 12 is folded at the same time with the two lateral walls 14 of the stiffener 12 reinforced by way of the only folding device 39 that is movable both transversely to the group- forming path PI (to perform the folding) , and parallel to the group-forming path PI (to follow the group-forming pocket 26 during folding) .

As illustrated in Figure 16, the folding device 35 is arranged along the top branch of the group-forming path PI downstream of the folding device 34 and performs the folding of the two lateral stabilizing tabs 16 of the stiffener 12 onto an outer surface of the bottom wall 15 of the stiffener 12 to be arranged on the opposite side with respect to group 4 of cigarettes; subsequently, the folding device 35 performs the folding of the central stabilizing tab 17 of the stiffener 12 onto the outer surface of the bottom wall 15 to be arranged on the opposite side with respect to the group 4 of cigarettes and over the two lateral stabilizing tabs 16 previously folded. Preferably, the folding device 35 comprises a movable finger (of known type and not illustrated in detail) which folds a stabilizing tab 16 of the stiffener 12 against the feeding direction of the group-forming pocket 26, and comprises folding blades (i.e. fixed folding devices of known type and not illustrated in detail) which fold the other lateral stabilizing tab 16 of the stiffener 12 and the central stabilizing tab 17 of the stiffener 12.

After completing the folding of the central stabilizing tab 17 of the stiffener 12 (i.e. after completing the folding of the stiffener 12), onto the central stabilizing tab 17 pressure is applied continuously so as to maintain the central stabilizing tab 17 pressed against the bottom wall 15 of the sealed package 3 with the interposition of the lateral stabilizing tabs 16. In particular, the pressure on the central stabilizing tab 17 of the stiffener 12 is maintained from when the central stabilizing tab 17 is folded until the sheet 7 of packing material is wrapped about the group 4 of cigarettes enclosed in the stiffener 12. According to a preferred embodiment, the pressure on the central stabilizing tab 17 is generated by bringing the pressure pads 43 and 44 (illustrated in figures 16 and 22) into contact with the central stabilizing tab 17 of the stiffener 12; in particular, an initial pressure pad 43 is provided which is arranged along the top branch of the group-forming path PI immediately downstream (uninterrupted) of the folding device 35, and a subsequent final pressure pad 44 that is arranged along the packing path P2. In other words, the pads 43 and 44 constitute a presser device which is arranged downstream of the folding device 35 and applies pressure onto the central stabilizing tab 17 of the stiffener 12 in order to keep the central stabilizing tab 17 pressed against the bottom wall 15 of the stiffener 12 with the interposition of the lateral stabilizing tabs 16.

As previously mentioned, between the group-forming path PI and the application path P2 the transferring device 36 is arranged (shown schematically in Figure 16) that extracts together and simultaneously the stiffener 12 and the group 4 of cigarettes from the group-forming pocket 26 of the conveyor 25 for inserting the stiffener 12 and the group 4 of cigarettes in the corresponding packing pocket 27 of the packing conveyor that travels in parallel and in synchronism with the group- forming conveyor 25. As said earlier, the stiffener 12 is supported only on the end part 38 of the group-forming pocket 26 so that initially the stiffener 12 is longitudinally misaligned with respect to the group 4 of cigarettes and is longitudinally aligned with the group 4 of cigarettes when extracted from the group-forming pocket 26 along with the group 4 of cigarettes; in other words, when the transferring device 36 pulls together the stiffener 12 and the group 4 of cigarettes from the group-forming pocket 26 of the group- forming conveyor 25, also imparts a relative movement between the stiffener 12 and the group 4 of cigarettes to obtain at a longitudinal alignment of one with respect to the other.

It is important to note that thanks to the fact that the group 4 of cigarettes is already partially inserted inside the stiffener 12, when the group 4 of cigarettes is fully inserted inside the stiffener 12 by the transferring device 36 no jamming between the tips of the cigarettes of the group 4 of cigarettes and the edge of the stiffener 12 occurs; consequently, the transfer performed by the transferring device 36 can be performed in speed without any risk of jamming that would lead to the destruction of the group 4 of cigarettes and the consequent arrest of the packing machine 18. In other words, folding the group 4 of cigarettes about the group-forming pocket 26 allows to avoid jamming between the tips of the cigarettes of the group 4 of cigarettes and the edge of the stiffener 12 at the time of fitting the group 4 of cigarettes in the stiffener 12.

The transferring device 36 is arranged at the end of the group-forming path PI and transfers the stiffener 12 and the group 4 of cigarettes from the group-forming pocket 26 of the group-forming conveyor 25 to the packing seat 27 of the packing conveyor. As illustrated in Figure 22, the transferring device 36 comprises a pusher 45 which rests at one end of the group 4 of cigarettes and pushes the group 4 of cigarettes out of the group-forming pocket 26 and a counter- pusher 46 which rests on the opposite end of the group 4 of cigarettes with the interposition of the bottom wall 15 (and of the tabs 16 and 17) of the stiffener 12.

As illustrated in Figure 15, along the packing path P2 a packing station 47 is arranged of the flow-pack type (shown schematically in Figure 15) wherein the sheet 7 of packing material is wrapped longitudinally in a tube shape about the group 4 of cigarettes to form a tubular package. In the packing station 47 a longitudinal heat seal device 48 is arranged (of known type) that performs the longitudinal heat seal 9 on the tubular package to stabilize the tubular shape of the tubular package itself; to the longitudinal heat seal device 48 a folding device is coupled (not shown) that, immediately after its formation, folds the fin shaped longitudinal heat seal 9 by 90° onto a corresponding wall of the group 4 of cigarettes (with the interposition of the front wall 13 of the stiffener 12) . In the packing station 47 the sheet 7 of packing material is fed from the bottom to provide the fin shaped longitudinal heat seal 9 in correspondence of the front wall of the group 4 of cigarettes (as shown in Figures 4 and 5) .

Arranged downstream of the longitudinal heat seal device 48 a transverse heat seal device 49 is arranged that creates cyclically on the tubular packing a succession of transverse welds 10, each of which is arranged between two successive groups of four cigarettes; in addition, the transverse heat seal device 49 achieves a transverse cross-cut at the center of each transverse heat seal 10 to separate the two sealed packages 3 who share the same transverse heat seal 10.

As illustrated in Figure 23, downstream of the transverse heat seal device 49 a folding wheel 50 is arranged which is mounted to rotate about a horizontal rotation axis 51 and is provided with a series of folding pockets 52, each of which is adapted to receive a corresponding sealed package 3. The folding wheel 50 is provided with a folding device 53 which is preferably provided with fixed folding blades (i.e. fixed folding devices) and initially folds 90° each fin shaped transverse heat seal 10 onto a corresponding side wall of the group 4 of cigarettes (with the interposition of a side wall 14 of the stiffener 12); subsequently, i.e. after folding each fin shaped lateral heat seal 10 by 90° onto the corresponding side wall of the sealed package 3 the device 53 folds 180° the triangular end flaps 11, onto the corresponding side wall of the sealed package 3 and over the fin shaped lateral heat seal

10 previously folded (as illustrated in Figures 4 and 5) . Furthermore, the folding wheel 50 is provided with a heat seal device 54 that heat-seals each triangular end flap 11 to the corresponding lateral wall of the sealed package 3 to remain in the desired position illustrated in Figures 4 and 5; according to a different embodiment, each triangular end flap

11 may be maintained in the desired position illustrated in Figures 4 and 5 only by the presence of the outer container 2 which surrounds the sealed package 3 and in this case the heat seal device 54 would be absent. It is important to note that the welds performed by the heat seal device 54 fix both ends of the triangular end flap 11, and each fin shaped lateral heat seal 10 to the corresponding lateral wall of the sealed package 3 so as to lock a folded configuration of the end flaps 11 and lock a folded configuration of the transverse fin shaped lateral heat seal 10.

As illustrated in Figure 23, between the transverse heat seal device 49 and the folding wheel 50 a conveyor belt 55 is interposed which travels with continuous motion for successively transferring the sealed packages 3 from the transverse heat seal device 49 to the folding wheel 50. The folding wheel 50 is rotatably mounted with intermittent motion, i.e. by steps, about the rotation axis 51; consequently, the folding wheel 50 is provided with an input pusher 56 that inserts the sealed package 3 inside a corresponding folding pocket 52 and an output pusher 56 which extracts the sealed package 3 from the inside of a corresponding folding pocket 52.

As illustrated in Figures 24 and 25, the transverse heat seal device 49 comprises two heat seal drums 58 that are rotatably mounted about respective central rotation axes 59 parallel one with respect to the other, are arranged on opposite sides of the packing path P2 along which the tubular package is fed, and bring respective heat seal heads 60 cooperating one with the other to clamp between them the tubular package during the performing of the transverse heat seal 10. The heat seal heads 60 are internally provided with cutting members 61 to obtain, during the performing of the transverse welds 10, a transverse cut of the tubular package so as to separate a sealed package 3 from the tubular package itself. The lateral surface of each heat seal drum 58 is covered by a compression element 62 that is elastically deformed to impart a compression on the tubular package in order to stretch the tubular package, and then remove the air trapped inside the tubular package during the execution of the transverse welds 10; normally, the compression element 62 is formed by brushes.

Each heat seal head 60 of a heat seal drum 58 is coupled to a corresponding support element 63 that is carried by a corresponding heat seal drum 58, is arranged downstream of the corresponding heat seal head 60 with respect to the feeding direction of the tubular package along the packing path P2, and comes in contact with a bottom or top wall of the tubular package itself. In the embodiment illustrated in the attached figures, both heat seal drums 58 are provided with support elements 63 and then, during the execution of a transverse heat seal 10, two cooperating support elements 63 are arranged to contact opposite walls of the tubular package for clamping between them the tubular package itself downstream of the heat seal heads 60. According to a different embodiment not shown, only the lower heat seal drum 60 is provided with support elements 63 (i.e. the top heat seal drum 60 is devoid of the support elements 63) .

Upon execution of the transverse heat seal 10, each support element 63 advances for a certain distance with a linear movement parallel to the packing path P2 to accompany the sealed package 3 which has just been separated from the continuous tubular package. For this purpose, each support element 63 is mounted movable with respect to the corresponding heat seal drum 58 to perform a relative movement with respect to the heat seal drum 58 itself; in particular, each support element 63 is rotatably mounted with respect to the corresponding heat seal drum 58 to rotate about a peripheral rotation axis 64 parallel to the central rotation axis 59. According to a preferred embodiment, each heat seal drum 58 comprises a camshaft implementing system 65 for controlling the relative movement (i.e. the relative rotation) between each support element 63 and the heat seal drum 58 itself. In particular, each support element 63 is connected to the corresponding heat seal drum 58 by a linking arm 66 that is hinged to the heat seal drum 58 itself at the peripheral rotation axis 64; one end of each linking arm 66 opposite, with respect to the peripheral rotation axis 64, to the support element 63 is connected with a follower roller that engages a fixed cam arranged within the corresponding heat seal drum 58.

Immediately downstream of the transverse heat seal device 49 the conveyor belt 55 starts, towards which the sealed packages 3 are pushed coming from the same transverse heat seal device 49; the support elements 63 guide each sealed package 3 towards the conveyor belt 55 to ensure a correct introduction of the sealed package 3 in the conveyor belt 55 itself, or to prevent the sealed package 3 from jamming against the conveyor belt 55 itself due to unwanted movements that can take place after the execution of the transverse heat seal 10.

As shown more clearly in Figure 24, in correspondence with an input of the conveyor belt 55 a pressure drum is arranged that is covered by an element that is elastically deformed (typically brushes) and that pushes the sealed package 3 against the conveyor belt 55.

According to the embodiment shown in Figure 26, during the execution of each transverse heat seal 10, the transverse heat seal 10 itself is interrupted in a limited portion of the tubular package so as to leave, astride of the transverse heat seal 10, at least one vent channel 67 that connects the inside of the sealed package 3 with the outside environment. The vent channel 67 is closed after the execution of the transverse welds 10 to make the sealed package 3 airproof. According to a preferred embodiment, the vent channel 67 is closed by a sealing that is performed after performing the transverse welds 10 and which coincides with the heat seal performed by the heat seal device 54 for heat sealing the fin shaped transverse welds 10 and/or the triangular end flaps to the underlying part of the sheet 7 of packing material. In other words the same heat sealing performed by the heat seal device 54 has both the function to close the vent channel 67 and the function of fixing the fin shaped transverse welds 10 and/or the triangular end flaps to the underlying part of the sheet 7 of packing material.

As illustrated in Figure 27, each heat seal head 60 has a heated surface 68, which is centrally interrupted by the presence of cutting member 61 and is pressed against the overlapping portions of the sheet 7 of packing material in order to achieve a corresponding transverse heat seal 10. In each heat seal head 60, the heated surface 68 has at least one recess 69 in correspondence of which the transverse heat seal 10 is interrupted to leave the vent channel 67.

The vent channel 67 allows to evacuate (fully or partially) the air inside the sealed package 3 before airproof closing the sealed package 3 itself. In other words, during the execution of the transverse welds 10 the sealed package 3 remains open towards the outer environment for the presence of the vent channel 67 (or of the vent channels, as there could be even more vent channels); in this way, the air inside the sealed package 3 can be evacuated (fully or partially) after performing the transverse welds 10. Immediately after the evacuation (complete or partial) of the air inside the sealed package 3 through the vent channel 67, the vent channel 67 itself is closed to make the sealed package 3 airproof by using the same heat sealing with which the fin shaped transverse welds 10 and/or the triangular end flaps are fixed to the underlying part of the sheet 7 of packing material.

According to a different embodiment not illustrated, the vent channel 67 itself is closed to make the sealed package 3 airproof by a further heat sealing that is different (i.e. performed at different times and by different members) from the heat seal performed by the heat seal device 54.

As illustrated in Figure 13, the initial packing unit 19 of the packing machine 18 is "L" shaped and has a front side

(shown in Figure 15) wherein the members that perform the various packing operations are arranged and a lateral side

(shown in Figure 14) wherein all the feeding of the packing materials are arranged (i.e. of the sheets 7 of packing material and of the stiffeners 12) . In particular, in Figure 14 can be recognized the two coils 31 (one as a reserve to the other) from which the continuous strip of packing material is unwrapped for the formation of the stiffeners 12 and the two coils 70 (one as a reserve to the other) from which the continuous strip of packing material for the formation of the sheets 7 of packing material is unwrapped.

The packing machine 18 described above has numerous advantages .

In the first place, in the packing machine 18 described above a correct and optimal evacuation (complete or partial) of the air enclosed in the sealed package 3 is always guaranteed before the airtight closure of the sealed package 3 itself; This result is obtained thanks to the presence of vent channels 67 that are created during the formation of the transversal heat seals 10 and subsequently closed by a further seal-off heat seal.

Moreover, the packing machine 18 as described above is easy and economical to produce, since the creation of the vent channels 67 is obtained very simply by means of a trivial mechanical machining of the heated surfaces 68 of the heat seal heads 60 to create the recesses 69; moreover, the further seal-off heat seal with which the vent channels 67 are closed does not involve any disadvantages since the same heat seal with which the fin shaped transverse heat seals 10 and/or the triangular end tabs 11 are fixed to the underlying part of the sheet 7 of packing material is exploited.

In the non-limiting embodiment illustrated in the attached figures, the sealed package 3 of the present invention contains a group 4 of cigarettes; thanks to numerous advantages of the sealed package 3 of the present invention, said sealed package 3 can be also used to contain articles other than cigarettes, such as food (candies, chocolates or other sweets) .

Claims

1) A packing method for producing a sealed package (3) ; the packing method comprising the steps of:

wrapping a sheet (7) of packing material longitudinally into a tube shape about a product to form a tubular package;

heat sealing the tubular package longitudinally, by means of a longitudinal heat seal device (48), to stabilize the shape of the tubular package itself;

heat sealing the tubular package transversely, by means of a transverse heat-seal device (49), to form two transverse heat seals (10) closing opposite ends of the tubular package at the corresponding lateral walls of the product;

the packing method being characterized by comprising the further steps of:

interrupting the formation of at least one transverse heat seal (10) over a limited portion of the tubular package, to leave a vent channel (67) extending astride the transverse heat seal (10) and connecting the inside of the sealed package (3) to the outside; and

closing the vent channel (67) after the transverse heat seals (10) are formed.

2) The packing method according to claim 1, wherein the vent channel (67) is closed by a seal-off heat seal after the transverse heat seals (10) are formed.

3) The packing method according to claim 2, wherein each transverse heat seal (10) is fin shaped and, once formed, is folded 90° onto a corresponding lateral wall of the product.

4) The packing method according to claim 3, and comprising the further step of heat sealing the fin shaped transverse heat seal (10) to the underlying part of the sheet (7) of packing material, to secure the fin-shaped transverse heat seal (10) in a folded configuration. 5) The packing method according to claim 4, wherein the fin shaped transverse heat seal (10) is heat sealed to the underlying part of the sheet (7) of packing material by the seal-off heat seal.

6) The packing method according to claim 3, 4 or 5 and comprising the further step of folding, at least one projecting end flap (11) of each fin-shaped transverse heat seal (10) onto a corresponding lateral wall of the product and onto the rest of the fin shaped transverse heat seal (10) .

7) The packing method according to claim 6 and comprising the further step of heat sealing the end flap (11) to the underlying part of the sheet (7) of packing material, to secure the end flap (11) in a folded configuration.

8) The packing method according to claim 7, wherein the end flap (11) is heat sealed to the underlying part of the sheet (7) of packing material by the seal-off heat seal.

9) The packing method according to one of claims 1 to 8, wherein the longitudinal heat seal (9) is fin shaped and, once formed, is folded 90° onto a corresponding wall of the product .

10) The packing method according to one of claims 1 to 9, wherein the transverse heat seal device (49) comprises at least a heat seal head (60) having a heated surface (68), which is pressed against the superimposed portions of the sheet (7) of packing material to form a corresponding transverse heat seal (10) and has at least one recess (69) where the transverse heat seal (10) is interrupted to form the vent channel (67) .

11) A packing machine (18) for producing a sealed package (3); the packing machine (18) comprising:

a packing station (47) wherein a sheet (7) of packing material is wound longitudinally into a tube shape about a product to form a tubular package;

a longitudinal heat-seal device (48), which forms a longitudinal heat seal (9) on the tubular package to stabilize the shape of the tubular package; and

a transverse heat seal device (49) arranged downstream from the longitudinal heat seal device (48), and which forms two transverse heat seals (10) closing opposite ends of the tubular package at lateral walls of the product;

the packing machine (18) being characterized in that the transverse heat-seal device (49) is designed to interrupt the formation of at least one transverse heat seal (10) over a limited portion of the tubular package, to leave a vent channel (67) extending astride the transverse heat seal (10) and connecting the inside of the sealed package (3) to the outside; and

a sealing device closes the vent channel (67) after the transverse heat seals (10) are formed.