Method and device for producing a cigarette packet

Abstract

A method and device for producing a cigarette packet having an inner wrapping, which is defined by a sheet of heat-seal material folded about a group of cigarettes, and has an opening closed by an adhesive patch; the correct position of the patch is determined after the patch is applied to the sheet of heat-seal material.

Description

The present invention relates to a method and device for producing a cigarette packet.

More specifically, the present invention relates to a device for producing a cigarette packet comprising an inner wrapping, in turn comprising a sheet of heat-seal material folded about a group of cigarettes to form a wrapped group of cigarettes; and an outer container, preferably made of thin cardboard, folded about the wrapped group of cigarettes. The device comprises a conveyor for feeding a strip of heat-seal material to a cutting station. The device also comprises an operating unit located at a slitting station to form a slit in the strip; an application unit located at a application station to apply a patch; a cutting assembly located at the cutting station to cut the sheet, complete with the slit, off the strip; a folding assembly for folding the sheet about the group of cigarettes to form the wrapped group of cigarettes; a sealing assembly for sealing superimposed portions of the sheet folded about the group of cigarettes; and a packing assembly for inserting the wrapped group of cigarettes inside the outer container.

BACKGROUND OF THE INVENTION

One example of a packet produced using devices of the above type is described in Patent Application WO98/22367.

Known devices of the above type have several drawbacks, including: relatively slow production of the sheet complete with the patch; and production of poor-quality packets, due to incorrect location or absence of the patch and/or slit on the sheet.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a device and method designed to at least partly eliminate the aforementioned drawbacks, and which at the same time are cheap and easy to implement.

According to the present invention, there are provided a method and device as claimed in the attached Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic partial front view of a device in accordance with the present invention;

FIG. 2 shows a schematic of part of the FIG. 1 device;

FIG. 3 shows a side view of a detail of the FIG. 2 part;

FIG. 4 shows an underside view of part of the FIG. 3 detail;

FIGS. 5 and 6 show a further detail of the FIG. 1 device in two successive positions;

FIG. 7 shows a view in perspective of a further detail of the FIG. 1 device;

FIG. 8 shows a packet produced using the FIG. 1 device;

FIG. 9 shows a sheet by which to produce the FIG. 8 packet;

FIG. 10 shows a topside view of a further detail of the FIG. 2 part.

DETAILED DESCRIPTION OF THE INVENTION

Number 1 in FIG. 1 indicates as a whole a device for producing a cigarette packet 2 (FIG. 8) comprising an inner wrapping 3, in turn comprising a sheet 3′ (FIG. 9) of heat-seal material folded about a group G of cigarettes to define a wrapped group 4 of cigarettes; and an outer container 5, preferably made of thin cardboard, folded about wrapped group 4 of cigarettes.

More specifically, sheet 3′ is made of multilayer laminated material, in which one or more layers comprise metal material, and other layers comprise plastic material. Sheet 3′ (FIG. 9) has a substantially U-shaped slit 6 defining an opening in wrapping 3; and a patch 7 having an adhesive face and applied over slit 6 to close inner wrapping 3

Packet 2 is substantially identical to the packet described in WO98/22367, which is included herein by way of reference.

Device 1 comprises a conveyor 8 (FIG. 2) for feeding a strip 9 of heat-seal material to a cutting station 10 (FIG. 1) along a feed path P and via a slitting station 11, two application stations 12 and 13 (FIG. 2) and a control station 14 (FIG. 7). Application station 13 is located downstream from application station 12, which in turn is located downstream from slitting station 11; and control station 14 is located downstream from application station 13.

Device 1 (FIG. 2) also comprises an operating unit 15 located at slitting station 11 to form slit 6 in strip 9; an application unit 16 located at application station 12 to apply patch 7 onto slit 6; an application unit 17 located at application station 13; and a detecting unit 18 located between application stations 12 and 13 to determine the presence of patch 7 on strip 9.

In actual use, strip 9 is cut at cutting station 10 to detach sheet 3′, complete with patch 7 and slit 6, from strip 9.

Device 1 also comprises a central control unit 19 connected to a sensor 20 of detecting unit 18 to activate application unit 17 when sensor 20 detects no patch 7 on slit 6.

Providing application unit 17 downstream from application unit 16 enables high-speed operation of device 1. In this connection, it is important to note that applying patch 7 to strip 9 is a relatively slow job, and only one application unit 16 or 17 would not guarantee correct application of patches 7 to successive slits 6 when strip 9 is fed through at high speed. Moreover, providing application unit 17 downstream from application unit 16 allows the operator to stop either one of the application units temporarily for maintenance purposes (cleaning the application unit, changing the reel of strip 39 removably supporting patch 7) without interrupting production of cigarette packets 2.

Operating unit 15 comprises a roller 21 rotating about a respective axis 22 and having a known peripheral blade (not shown) which rotates about axis 22 and into contact with strip 9 to form slit 6.

With reference to FIG. 7, control station 14 has a control unit 23 for determining correct placement of patch 7 on slit 6.

Control unit 23 comprises a detector 24; and a lighting system for illuminating a top surface 25 of strip 9 with diffused light, and which in turn comprises two light sources 26 located on opposite sides of path P and alongside strip 9, and a cover 27 (shown by a dash line in FIG. 7). Cover 27 is positioned over path P, and has a downwardly-concave surface 28 facing path P and surface 25. Light sources 26 direct inclined light onto concave surface 28, which reflects it to illuminate surface 25.

Detector 24 is located over path P and housed in a seat in cover 27.

It is important to note that, using diffused light, detector 24 is able to detect the edges of patch 7, even when patch 7 is substantially the same colour as strip 9.

Control unit 23 also comprises a lighting device 29 underneath path P to direct light onto slit 6; and the light through slit 6 is detected by detector 24 to determine the presence of slit 6 on the strip. A supporting surface S, on which strip 9 runs at control station 14, has a slot F through which the light from lighting device 29 passes. Detector 24, lighting device 29, and slot F are preferably aligned vertically.

Cover 27 is movable to allow the operator free access to control unit 23.

Control unit 23 also comprises a sensor 30 for detecting a reference element 31 printed on strip 9.

Operation of control unit 23 will now be described as of the instant in which element 31 is detected by sensor 30. Light sources 26 emit a flash of light, and an image is acquired by detector 24 and processed by central control unit 19, to which detector 24 is connected (the connection between detector 24 and central control unit 19 is not shown). Central control unit 19 compares detected values with reference values, and, in the event the detected values are incompatible with the reference values, emits an error signal. More specifically, central control unit 19 compares the position of an edge 32 of strip 9 with the position—determined in two areas L1 and L2—of a longitudinal edge 33 of patch 7, and compares the position of a transverse edge 34 of patch 7 with the position (detected by sensor 30) of element 31.

In this way, control unit 23 is able to determine accurately whether patch 7 is correctly oriented and positioned longitudinally and transversely with respect to strip 9.

The absence of slit 6 is indicated when detector 24 fails to receive sufficient light through slot F.

Conveyor 8 (FIG. 2) comprises a suction belt 35 for feeding strip 9 through application stations 12 and 13, and beneath which is located a suction device 36 (shown by the dash line in FIG. 2). Suction belt 35 prevents strip 9 from moving crosswise to path P, and, at the same time, ensures slit 6, formed beforehand in strip 9, is held down as application unit 16 or 17 deposits patch 7 on strip 9, thus ensuring extremely precise application of patch 7 on strip 9.

The precision with which patch 7 is applied to strip 9 is further improved by the particular structure and operation of application units 16 and 17.

Application unit 16 (FIG. 3) comprises an applicator head 37; and a conveyor 38 for feeding a strip 39, removably supporting patch 7, to applicator head 37 in a direction crosswise to path P.

In actual use, strip 39 is fed about a blade 40 to detach patch 7 from strip 39. Applicator head 37 has a known suction system (not shown) for holding patch 7 on a perforated bottom surface 41 of applicator head 37; which surface 41 (FIG. 4) is located over path P, is substantially horizontal, and is substantially parallel to surface 25.

Applicator head 37 also emits air jets through surface 41 and in a direction crosswise to path P. More specifically, the air jets are directed downwards in a direction substantially perpendicular to path P and surface 25, so that patch 7 is detached downwards from surface 41 and moves parallel to itself in a substantially vertical direction.

Application unit 17 is substantially identical to application unit 16.

At cutting station 10, a known cutting assembly 42 (shown schematically in FIG. 1) cuts strip 9 to separate sheet 3′, complete with patch 7 and slit 6, from strip 9.

Device 1 also comprises a known folding assembly 43 (shown schematically in FIG. 1) which folds sheet 3′ about group G of cigarettes to form wrapped group 4; and a sealing assembly 44 for sealing superimposed portions T of sheet 3′ folded about group G of cigarettes.

Sealing assembly 44 comprises a wheel 45 (shown by a continuous line in FIG. 1 and by a dash line in FIGS. 5 and 6), in turn comprising a number of known peripheral seats (not shown), each for housing a respective wrapped group 4.

With particular reference to FIGS. 5 and 6, sealing assembly 44 also comprises two sealing units 46 on opposite sides of wheel 45. Each sealing unit 46 comprises an oscillating magnetic field generator 47 (shown schematically); a movable member 48 of nonconducting material; and an actuator 49 for moving movable member 48 into contact with said portions T of sheet 3′ to keep portions T superimposed correctly. Generator 47 is maintained in a substantially fixed position.

The oscillating magnetic fields generated by generator 47 induce heat in certain areas of sheet 3′, by virtue of sheet 3′ containing metal components.

In this way, good-quality seals can be achieved, while at the same time reducing the risk of damage to sheet 3′ and/or the cigarettes (not shown) wrapped in sheet 3′.

This is achieved in an extremely straightforward, low-cost manner by not moving generators 47.

Generators 47 are preferably oil-cooled.

Though the FIG. 5 and 6 embodiment shows two actuators 49, one for each sealing unit 46, it should be pointed out that, alternatively, movable members 48 may be operated by a single mechanical mechanism.

An embodiment not shown of sealing assembly 44 comprises a conventional sealing unit, with a heating element, instead of electromagnetic-induction sealing unit 46.

Device 1 also comprises a packing assembly 50 for inserting wrapped group 4 inside outer container 5.

More specifically, wrapped group 4 may be inserted inside a preformed outer container 5, or outer container 5 may be formed about wrapped group 4. Herein, the expression “insert the wrapped group of cigarettes inside the outer container” includes both the above alternatives.

In preferred embodiments not shown, a suction compensation chamber for strip 9 is provided between application station 13 and control station 14, and is, for example, of the type described in EP 949174, which is included herein by way of reference.

In other preferred embodiments not shown, a number of sensors, each for detecting the presence of element 31, are located along path P; in which case, central control unit 19 regulates operation of the assemblies and units of device 1 as a function of the findings of the sensor.

Operation of device 1 will now be described as a whole, as of the instant in which operating unit 15 forms slit 6. At this point, strip 9 is fed continuously along path P through application stations 12 and 13, where patch 7 is applied to slit 6, and through control station 14 to cutting station 10. Sheet 3′ is formed at cutting station 10 and fed through a reject station 51, where a reject unit 52 eliminates any flawed sheets 3′.

If not rejected, sheet 3′ is fed to folding assembly 43, which folds sheet 3′ about group G of cigarettes to form wrapped group 4. Inner wrapping 3 is then stabilized by sealing assembly 44. And, finally, the wrapped group 4 is inserted inside outer container 5.

In alternative embodiments not shown, reject station 51 is located downstream from sealing assembly 44.

Claims

1) A method of producing a cigarette packet comprising an inner wrapping (3), in turn comprising a sheet (3′) of heat-seal material folded about a group (G) of cigarettes to form a wrapped group (4) of cigarettes; and an outer container (5), preferably of thin cardboard, folded about the wrapped group (4) of cigarettes; the method comprising: a feed step to feed a strip (9) of heat-seal material along a feed path (P); a step of forming a slit (6) in the strip (9); a first application step to apply an adhesive patch (7) onto the slit (6); a cutting step to cut said sheet (3′), complete with the slit (6) and the patch (7), off the strip (9); a folding step to fold the sheet (3′) about the group (G) of cigarettes to form the wrapped group (4) of cigarettes; a sealing step to seal superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; an insertion step to insert the wrapped group (4) of cigarettes inside the outer container (5); the method being characterized by comprising a control step to determine correct positioning of the applied patch (7); the control step preceding the folding step.

2) A method as claimed in claim 1, wherein the control step precedes the cutting step.

3) A method as claimed in claim 1, wherein the control step comprises illuminating an area about the slit (6) with diffused light.

4) A method as claimed in claim 1, wherein the control step comprises comparing the position of a first edge (33) of the patch (7), substantially parallel to the feed path (P), with the position of an edge (32) of the strip (9).

5) A method as claimed in claim 4, wherein the position of the first edge (33) is determined in at least two separate areas (L1, L2) of the first edge (33).

6) A method as claimed in claim 1, wherein the control step comprises comparing the position of a second edge (34) of the patch (7), crosswise to the feed path (P), with an element (31) printed on the strip (9).

7) A method as claimed in claim 1, wherein, at the feed step, the strip (9) is fed along the feed path (P) by a conveyor (8) comprising a suction belt (35); the first application step being performed at a first application station (12), through which the suction belt (35) travels.

8) A method as claimed in claim 1, and comprising a reject step to reject the sheet (3′) in the event the patch (7) is found to be positioned incorrectly at the control step.

9) A method as claimed in claim 8, wherein the reject step precedes the folding step.

10) A method as claimed in claim 8, wherein the reject step precedes the sealing step.

11) A method as claimed in claim 1, and comprising a detecting step, after the first application step, to determine the presence of the patch (7) on the strip (9); and a second application step to apply a patch (7) on the slit (6) in the event no patch (7) is detected on the slit (6) at the detecting step; the second application step preceding the cutting step and following the detecting step.

12) A method as claimed in claim 11, wherein, at the feed step, the strip (9) is fed along the feed path (P) by a conveyor (8) comprising a suction belt (35); the first and second application step being performed respectively at a first and second application station (12, 13) located along the feed path (P) at the suction belt (35).

13) A method as claimed in claim 1, wherein at least one further strip (39), removably supporting at least one patch (7), is fed to the feed path (P) in a direction substantially crosswise to the feed path (P).

14) A method as claimed in claim 1, wherein said superimposed portions (T) are sealed by electromagnetic induction produced by an oscillating electromagnetic field produced by a substantially fixed generator (47); at the sealing step, movable members (48) of nonconducting material being brought into contact with the superimposed portions (T) to keep the superimposed portions (T) correctly superimposed; and the sheet (3′) being made of at least partly conducting material.

15) A method as claimed in claim 1, wherein the patch (7) is applied to the strip (9) by at least one air jet crosswise to the feed path (P) and to a surface (25) of the strip (9).

16) A method as claimed in claim 15, wherein the patch (7) is maintained parallel to the strip (9) by suction immediately prior to being applied to the strip (9).

17) A method as claimed in claim 16, wherein the patch is held over the strip (9) by suction, and the air jet blows the patch (7) downwards onto the slit (6); the air jet being substantially vertical.

18) A method of producing a cigarette packet comprising an inner wrapping (3), in turn comprising a sheet (3′) of heat-seal material folded about a group (G) of cigarettes to form a wrapped group (4) of cigarettes; and an outer container (5), preferably of thin cardboard, folded about the wrapped group of cigarettes; the method comprising: a feed step to feed a strip (9) of heat-seal material along a feed path (P); a step of forming a slit (6) in the strip (9); a first application step to apply an adhesive patch (7) onto the slit (6); a cutting step to cut the sheet (3′), complete with the slit (6) and the patch (7), off the strip (9); a folding step to fold the sheet (3′) about the group (G) of cigarettes to form the wrapped group (4) of cigarettes; a sealing step to seal superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; an insertion step to insert the wrapped group (4) of cigarettes inside the outer container (5); the method being characterized by comprising a detecting step, after the first application step, to determine the presence of the patch (7) on the slit (6); and a second application step to apply a patch (7) on the slit (6) in the event no patch (7) is detected on the slit (6) at the detecting step; the second application step preceding the cutting step and following the detecting step.

19) A method of producing a cigarette packet comprising an inner wrapping (3), in turn comprising a sheet (3′) of heat-seal material folded about a group (G) of cigarettes; the method comprising: a feed step to feed a strip (9) of heat-seal material along a feed path (P); a step of forming a slit (6) in the strip (9); an application step to apply an adhesive patch (7) onto the slit (6); a cutting step to cut said sheet (3′), complete with the slit (6) and the patch (7), off the strip (9); a folding step to fold the sheet about the group (G) of cigarettes to form a wrapped group (4) of cigarettes; a sealing step to seal superimposed portions (T) of the sheet folded about the group (G) of cigarettes; the method being characterized in that, at the feed step, the strip is fed along the feed path (P) by a conveyor (8) comprising a suction belt (35); the application step being performed at an application station (12) located along the feed path (P) at the suction belt (35).

20) A method of producing a cigarette packet comprising a wrapping (3) of heat-seal material; the method comprising: a folding step to fold a sheet (3′) of at least partly conductive heat-seal material about an article, in particular a group (G) of cigarettes; a sealing step to seal superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; the method being characterized in that said superimposed portions (T) are sealed by electromagnetic induction produced by a variable electromagnetic field produced by a substantially fixed generator (47); at the sealing step, movable members (48) of nonconducting material being brought into contact with the superimposed portions (T) to keep the superimposed portions (T) correctly superimposed.

21) A method of producing a cigarette packet comprising an inner wrapping (3), in turn comprising a sheet (3′) of heat-seal material folded about a group (G) of cigarettes; the method comprising: a feed step to feed a strip (9) of heat-seal material along a feed path (P); a step of forming a slit (6) in the strip (9); an application step to apply an adhesive patch (7) onto the slit (6); a cutting step to cut said sheet, complete with the slit (6) and the adhesive patch (7), off the strip (9); a folding step to fold the sheet (3′) about the group (G) of cigarettes to form a wrapped group (4) of cigarettes; a sealing step to seal superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; the method being characterized in that the patch (7) is applied to the strip (9) by at least one air jet crosswise to the feed path (P) and to a surface (25) of the strip (9).

22) A device for producing a cigarette packet comprising an inner wrapping, in turn comprising a sheet of heat-seal material folded about a group (G) of cigarettes to form a wrapped group (4) of cigarettes; and an outer container (5), preferably of thin cardboard, folded about the wrapped group (4) of cigarettes; the device (1) comprising: a conveyor (8) for feeding a strip (9) of heat-seal material along a feed path (P) through a slitting station (11) and a first application station (12) to a cutting station (10); an operating unit (15) located at the slitting station (11) to form a slit (6) in the strip (9); a first application unit (16) located at the first application station (12) to apply an adhesive patch (7) onto the slit (6); a cutting assembly (42) located at the cutting station (10) to cut said sheet (3′), complete with the slit (6) and the patch (7), off the strip (9); a folding assembly (43) for folding the sheet about the group (G) of cigarettes to form the wrapped group (4) of cigarettes; a sealing assembly (44) for sealing superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; and a packing assembly (50) for inserting the wrapped group (4) of cigarettes inside the outer container (5); the device (1) being characterized by comprising a control unit (23) for determining correct positioning of the patch (7) on the slit (6); the control unit (23) being located upstream from the folding assembly (43).

23) A device as claimed in claim 22, wherein the control unit (23) is located upstream from the cutting assembly (42) along the feed path (P).

24) A device as claimed in claim 22, wherein the control unit (23) comprises a detector (24); and lighting means (26, 27) for illuminating a surface (25) of the strip (9) with diffused light.

25) A device as claimed in claim 24, wherein the lighting means (26, 27) comprise a cover (27), a concave surface (28) of which is positioned facing the feed path (P); and at least two light sources (26) located on opposite sides of the feed path (P), and which direct light onto the concave surface (28), which reflects the light to illuminate, in use, the surface (25) of the strip (9).

26) A device as claimed in claim 25, wherein the cover (27) and the detector (24) are located over the feed path (P).

27) A device as claimed in claim 24, wherein the detector (24) determines the position of edges (33, 34) of the patch (7).

28) A device as claimed in claim 22, wherein the control unit (23) determines the presence of the slit (6).

29) A device as claimed in claim 22, and comprising a lighting device (29) and a detector (24); the lighting device (29) and the detector being located on opposite sides of the feed path (P); and the detector (24) detecting the light travelling through the slit (6).

30) A device as claimed in claim 22, wherein the conveyor (8) comprises a suction belt (35) for feeding the strip (9) through the first application station (12).

31) A device as claimed in claim 22, and comprising a reject unit (52) for rejecting the sheet (3′) on the basis of the findings of the control unit (23).

32) A device as claimed in claim 22, and comprising a second application unit (17) located downstream from the first application unit (16) along the feed path (P), and which applies the patch (7) onto the slit (6) in the event no patch (7) is applied onto the slit (6) by the first application unit (16).

33) A device as claimed in claim 32, and comprising a detecting unit (18) located downstream from the first application station (12) along the feed path (P) to detect the presence of the patch (7) on the strip (9); the second application unit (17) being located downstream from the detecting unit (18) along the feed path (P), and applying a patch (7) onto the slit (6) in the event the detecting unit (18), in use, detects no patch on the slit.

34) A device as claimed in claim 22, wherein the first application unit (16) comprises a feed assembly (38) for feeding a further strip (39), removably supporting at least one patch (7), to the first application station (12) in a direction substantially crosswise to the feed path (P).

35) A device as claimed in claim 22, wherein the sealing assembly (44) comprises at least one oscillating electromagnetic field generator (47); at least one movable member (48) of nonconducting material; and actuating means (49) which move the movable member (48) into contact with said superimposed portions (T) to keep the superimposed portions (T) correctly superimposed; the generator (47) being substantially fixed.

36) A device as claimed in claim 22, wherein the first application unit (16) comprises blow means for blowing the patch (7) onto the strip (9) by emitting at least one air jet crosswise to the feed path (P) and to a surface (25) of the strip (9).

37) A device as claimed in claim 36, wherein the first application unit (16) comprises suction means for maintaining the patch (7) parallel to the strip (9) at the first application station (12).

38) A device as claimed in claim 36, wherein the air jet is substantially vertical.

39) A device for producing a cigarette packet comprising an inner wrapping (3), in turn comprising a sheet (3′) of heat-seal material folded about a group (G) of cigarettes to form a wrapped group (4) of cigarettes; and an outer container (5), preferably of thin cardboard, folded about the wrapped group (4) of cigarettes; the device (1) comprising: a conveyor (8) for feeding a strip (9) of heat-seal material along a feed path (P) through a slitting station (11) and a first application station (12) to a cutting station (10); an operating unit (15) located at the slitting station (11) to form a slit (6) in the strip (9); a first application unit (16) located at the first application station (12) to apply an adhesive patch (7) onto the slit (6); a cutting assembly (42) located at the cutting station (10) to cut said sheet (3′), complete with the slit (6) and the patch (7), off the strip (9); a folding assembly (43) for folding the sheet (3′) about the group (G) of cigarettes to form the wrapped group (4) of cigarettes; a sealing assembly (44) for sealing superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; and a packing assembly (50) for inserting the wrapped group (4) of cigarettes inside the outer container (5); the device (1) being characterized by comprising a detecting unit (18) located downstream from the first application station (12) along the feed path (P) to detect the presence of the patch (7) on the strip (9); and a second application unit (17) located downstream from the detecting unit (18) along the feed path (P) to apply a patch (7) onto the slit (6) in the event the detecting unit (18), in use, detects no patch (7) on the slit (6).

40) A device for producing a cigarette packet comprising an inner wrapping (3), in turn comprising a sheet (3′) of heat-seal material folded about a group (G) of cigarettes; the device (1) comprising: a conveyor (8) for feeding a strip (9) of heat-seal material along a feed path (P) through a slitting station (11) and an application station (12; 13) to a cutting station (10); an operating unit (15) located at the slitting station (11) to form a slit (6) in the strip (9); an application unit (16; 17) located at the application station (12; 13) to apply an adhesive patch (7) onto the slit (6); a cutting assembly (42) located at the cutting station (10) to cut said sheet (3′), complete with the slit (6) and the patch (7), off the strip (9); a folding assembly (43) for folding the sheet (3′) about the group (G) of cigarettes to form a wrapped group (4) of cigarettes; and a sealing assembly (44) for sealing superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; the device (1) being characterized in that the conveyor (8) comprises a suction belt (35) for feeding the strip (9) through the application station (12; 13).

41) A device for producing a cigarette packet comprising an inner wrapping (3), in turn comprising a sheet (3′) of heat-seal material; the device (1) comprising: a folding assembly (43) for folding the sheet (3′) about a group (G) of cigarettes to form the wrapped group (4) of cigarettes; and a sealing assembly (44) for sealing superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; the device (1) being characterized in that the sealing assembly (44) comprises at least one oscillating electromagnetic field generator (47); at least one movable member (48) of nonconducting material; and actuating means (49) which move the movable member (48) into contact with said superimposed portions (T) to keep the superimposed portions (T) correctly superimposed; the generator (47) being substantially fixed.

42) A device for producing a cigarette packet (2) comprising an inner wrapping (3), in turn comprising a sheet (3′) of heat-seal material folded about a group (G) of cigarettes; the device (1) comprising: a conveyor (8) for feeding a strip (9) of heat-seal material along a feed path (P) through a slitting station (11) and an application station (12; 13) to a cutting station (10); an operating unit (15) located at the slitting station (11) to form a slit (6) in the strip (9); an application unit (16; 17) located at the application station (12; 13) to apply an adhesive patch (7) onto the slit (6); a cutting assembly (42) located at the cutting station (10) to cut said sheet (3′), complete with the slit (6) and the patch (7), off the strip (9); a folding assembly (43) for folding the sheet (3′) about the group (G) of cigarettes to form a wrapped group (4) of cigarettes; and a sealing assembly (44) for sealing superimposed portions (T) of the sheet (3′) folded about the group (G) of cigarettes; the device (1) being characterized in that the application unit (16; 17) comprises blow means for blowing the patch (7) onto the strip (9) by emitting at least one air jet crosswise to the feed path (P) and to a surface (25) of the strip (9).