Patent Publication Number: US-7900424-B2

Title: Method and wrapping unit for folding a sheet of wrapping about a group of cigarettes

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Italian patent application No. BO2008A 000094, filed Feb. 13, 2008. 
     TECHNICAL FIELD 
     The present invention relates to a method and wrapping unit for folding a sheet of wrapping about a group of cigarettes. 
     BACKGROUND ART 
     A packet of cigarettes normally comprises an inner package comprising a group of cigarettes wrapped in a sheet of inner wrapping; and an outer package enclosing the inner package, and which may be cup-shaped and comprise a sheet of outer wrapping folded about the inner package (soft packet of cigarettes), or may comprise a rigid, hinged-lid box formed by folding a rigid blank about the inner package (rigid packet of cigarettes). 
     Folding the sheet of inner wrapping about the group of cigarettes has been found to damage the ends of the cigarettes by producing local deformation (at both the filter-tipped end and the plain end) and/or tobacco fallout (i.e. loss of tobacco, obviously only from the plain tips at the opposite end to the filters). Damage by folding the sheet of inner wrapping about the group of cigarettes mostly applies to the cigarettes at the corners of the group, but is nevertheless evident in all the outer cigarettes, i.e. located along the fold lines of the sheet of inner wrapping. Moreover, the stiffness of the sheet of inner wrapping deforms the ends of the cigarettes, thus resulting in an inner package with rounded as opposed to square edges. This is particularly undesirable by producing an overall look of the exposed portion of the inner package that is not very popular with consumers, who tend to opt for inner packages with sharp, well pronounced edges. 
     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, a rigid packet of cigarettes has been proposed, in which the inner package is airtight and comprises a sheet of airtight, heat-seal wrapping. Folding a sheet of airtight inner wrapping, however, is particularly damaging to the cigarettes, by being thicker (and therefore stiffer) than conventional sheets of foil inner wrapping. 
     DISCLOSURE OF THE INVENTION 
     It is an object of the present invention to provide a method and wrapping unit for folding a sheet of wrapping about a group of cigarettes, which method and wrapping unit are cheap and easy to implement, and provide for eliminating the above drawbacks. 
     According to the present invention, there are provided a method and wrapping unit for folding a sheet of wrapping about a group of cigarettes, 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 front view in perspective of a package of cigarettes; 
         FIG. 2  shows a schematic view in perspective, with parts removed for clarity, of a cigarette packing machine wrapping unit for producing the  FIG. 1  package of cigarettes and in accordance with the present invention; 
         FIG. 3  shows a larger-scale plan view of a folding spindle of the  FIG. 2  wrapping unit; 
         FIGS. 4-7  show a sequence of wrapping operations performed by the  FIG. 3  folding spindle; 
         FIG. 8  shows a plan view of a different embodiment of the  FIG. 3  folding spindle; 
         FIGS. 9-11  show a sequence of wrapping operations performed by the  FIG. 8  folding spindle; 
         FIG. 12  shows a plan view of a further embodiment of the  FIG. 8  folding spindle; 
         FIGS. 13-16  show a sequence of wrapping operations performed by the  FIG. 12  folding spindle; 
         FIGS. 17 and 18  show two views in perspective of the  FIG. 12  folding spindle; 
         FIG. 19  shows a variation of the  FIG. 12  folding spindle. 
     
    
    
     PREFERRED EMBODIMENTS OF THE INVENTION 
     Number  1  in  FIG. 1  indicates as a whole a package of cigarettes enclosing a parallelepiped-shaped group  2  of cigarettes, and which can be inserted inside a known rigid, hinged-lid cigarette packet. 
     Package  1  is formed by folding a rectangular sheet  6  of wrapping (shown flat in  FIG. 2 ) made of airtight, heat-seal plastic material directly about group  2  of cigarettes, so that it directly contacts the cigarettes. Once sheet  6  of wrapping 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  6  of wrapping. Number  10  in  FIG. 2  indicates as a whole a packing machine for producing package  1  as described above. 
     Packing machine  10  comprises a group-forming unit (not shown in  FIG. 2 ) for successively forming groups  2  of cigarettes; and a wrapping unit  12  ( FIG. 2 ) on which a sheet  6  of wrapping is wrapped and heat sealed about each group  2  of cigarettes. It is important to bear in mind that packing machine  10  may comprise only the group-forming unit (not shown in  FIG. 2 ) and wrapping unit  12 ; in which case, each package  1  described above is a finished marketable product. Alternatively, packing machine  10  may comprise a known further packing station to enclose each package  1  in an outer package, which may be cup-shaped and comprise a sheet of outer wrapping 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). 
     Groups  2  of cigarettes are transferred from the group-forming unit to wrapping unit  12  at a transfer station  24  defined between the group-forming unit (not shown) and wrapping unit  12 . More specifically, transfer station  24  comprises a transfer device  25  in turn comprising two pushers  26  for transferring two groups  2  of cigarettes simultaneously from the group-forming unit to wrapping unit  12 . 
     Wrapping unit  12  comprises two coaxial, superimposed input wheels  27 , which receive and convey two groups  2  of cigarettes simultaneously. Each input wheel  27  is horizontal, rotates in steps about a common vertical axis  28  of rotation, and supports two peripheral pockets  29 , each for housing a group  2  of cigarettes. 
     Wrapping unit  12  also comprises two coaxial, superimposed wrapping wheels  30 , which simultaneously receive two groups  2  of cigarettes wrapped partly in respective sheets  6  of wrapping, each folded into a U. Each wrapping wheel  30  is horizontal, rotates in steps about a common vertical axis  31  of rotation, and supports two peripheral pockets  32 , each for housing a group  2  of cigarettes wrapped partly in a respective sheet  6  of wrapping. 
     At a feed station  33  between the two input wheels  27  and the two wrapping wheels  30 , two sheets  6  of wrapping are fed simultaneously along a vertical feed path to engage two groups  2  of cigarettes as they are transferred from the two input wheels  27  to the two wrapping wheels  30 . 
     Each wrapping wheel  30  has known fixed and movable folding members (not shown) for folding the ends of each sheet  6  of wrapping about respective group  2  of cigarettes to form a package  1 ; and a sealing device  34  for heat sealing the superimposed end portions of each sheet  6  of wrapping. 
     Finally, wrapping unit  12  comprises two straight folding devices  35 , each of which receives an unfinished package  1  from a respective wrapping wheel  30 , and folds the sides of respective sheet  6  of wrapping about respective group  2  of cigarettes to complete package  1 . Each folding device  35  preferably comprises fixed folding screws. Immediately downstream from each folding device  35 , two sealing devices  36  heat seal the superimposed lateral portions of each sheet  6  of wrapping. 
       FIG. 3  shows a larger-scale plan view of feed station  33  of wrapping unit  12  in  FIG. 2 . As shown in  FIG. 3 , wrapping unit  12  comprises two tubular spindles  49  (only one shown in  FIG. 3 ) located upstream from feed station  33 , and through which are fed two respective groups  2  of cigarettes from the two input wheels  27 . Each peripheral pocket  32  of each wrapping wheel  30  has an inlet/outlet opening defining a seat  50  for a convex outlet end  51  of respective tubular spindle  49 ; and each tubular spindle  49  is moved, by known actuating means (not shown) and back and forth in the travelling direction of groups  2  of cigarettes, to and from a position in which outlet end  51  engages the inlet/outlet opening of corresponding pocket  32 . In other words, each tubular spindle  49  performs a reciprocating movement comprising a forward movement, in the travelling direction of group  2  of cigarettes, which causes tubular spindle  49  to intercept sheet  6  of wrapping (as described in detail below), and a return movement in the opposition direction to the travelling direction of group  2  of cigarettes. 
     The surface of outlet end  51  of each tubular spindle  49  that contacts sheets  6  of wrapping preferably has a number of suction holes (not shown) connected to a suction source not shown, and which serve to hold sheet  6  of wrapping in the correct position on outlet end  51  of tubular spindle  49  and prevent it from slipping with respect to tubular spindle  49 . 
     It is important to note that outlet end  51  of each tubular spindle  49  is preferably truncated-cone-shaped, tapering in the travelling direction of group  2  of cigarettes, and the inlet end of seat  50  is also truncated-cone-shaped and complementary with the truncated-cone shape of outlet end  51  of tubular spindle  49 . 
     A movable pusher  52 , moving back and forth in the travelling direction of groups  2  of cigarettes, is connected to each input wheel  27  to expel a group  2  of cigarettes from a pocket  29  of input wheel  27  and through a respective tubular spindle  49  into a pocket  32  of respective wrapping wheel  30 . 
     In a preferred embodiment, each pocket  32  of each wrapping wheel  30  has folding members  53  located on opposite sides of the inlet/outlet opening of pocket  32 , and movable between a rest position ( FIGS. 3 ,  4 ,  5 ,  7 ) in which folding members  53  are withdrawn inside wrapping wheel  30 , and a work position ( FIG. 6 ) in which folding members  53  project perpendicularly from wrapping wheel  30 . 
     As shown in  FIGS. 3-7 , folding members  53  of each pocket  32  comprise two folders  54  hinged to wrapping wheel  30  and rotated about respective axes  55  of rotation, parallel to the axis  31  of rotation of wrapping wheel  30 , by a cam actuating system not shown. In a different embodiment not shown, folding members  53  of each pocket  32  comprise two folders  54  fitted to wrapping wheel  30  and slid radially with respect to wrapping wheel  30  by a cam actuating system. 
     The way in which a group  2  of cigarettes and a respective sheet  6  of wrapping are fed into a pocket  32  of wrapping wheel  30  will now be described with reference to  FIGS. 4-7 . 
     Firstly, group  2  of cigarettes is expelled from pocket  29  of input wheel  27  into tubular spindle  49  by a pusher  52 . As it is inserted inside tubular spindle  49 , group  2  of cigarettes may be compressed laterally by the taper of the inner channel of tubular spindle  49 . When inserting group  2  of cigarettes, tubular spindle  49  is stationary in a withdrawn position ( FIG. 4 ), and defines, with pocket  32  of wrapping wheel  30  and at feed station  33 , a gap through which a sheet  6  of wrapping is fed. 
     Tubular spindle  49  is then moved towards wrapping wheel  30 , so that, before the leading end of group  2  of cigarettes reaches sheet  6  of wrapping, the outlet end  51  of tubular spindle  49  engages seat  50  of pocket  32  ( FIG. 5 ) and folds sheet  6  of wrapping into a U. At this point, folding members  53  of pocket  32  are operated to move from the rest position ( FIG. 5 ) to the work position ( FIG. 6 ) to complete folding sheet  6  of wrapping into a U on tubular spindle  49 . 
     Finally, tubular spindle  49  returns to the withdrawn position in the opposite direction to the travelling direction of groups  2  of cigarettes, while group  2  of cigarettes is kept moving by pusher  52  and inserted inside pocket  32  together with sheet  6  of wrapping, which slides off tubular spindle  49  and wraps onto group  2  of cigarettes ( FIG. 7 ). 
     Each sheet  6  of wrapping is therefore folded into a U, not by the axial thrust exerted on it by the cigarettes in group  2 , but by the thrust exerted by tubular spindle  49 , which acts as a folder. When folding sheet  6  of wrapping into a U, the cigarettes in group  2  therefore undergo absolutely no axial stress and, hence, no deformation. 
     In other words, group  2  of cigarettes is fed along one path, while sheet  6  of wrapping is fed perpendicularly to the path of group  2  of cigarettes. At this point, a tubular spindle  49  is fed along the path of group  2  of cigarettes to intercept and fold sheet  6  of wrapping into a U about tubular spindle  49 ; and, finally, group  2  of cigarettes is fed through tubular spindle  49  (which by then is moving in the opposite direction) to slide the U-folded sheet  6  of wrapping off tubular spindle  49  and onto group  2  of cigarettes. 
     In the  FIG. 3-7  embodiment, each tubular spindle  49  is of limited travel, and folds sheet  6  of wrapping into a U against seat  50  of a pocket  32  of wrapping wheel  30 . 
     In a variation shown in  FIGS. 8-11 , each tubular spindle  49  has a longer travel, and folds sheet  6  of wrapping into a U against fixed folders  56 . 
     The way in which a group  2  of cigarettes and a respective sheet  6  of wrapping are fed into a pocket  32  of wrapping wheel  30  will now be described with reference to  FIGS. 8-11 . 
     To begin with, tubular spindle  49  is stationary in a withdrawn position ( FIG. 8 ), and defines, with pocket  32  of wrapping wheel  30  and at feed station  33 , a gap through which a sheet  6  of wrapping is fed. Tubular spindle  49  is then moved towards wrapping wheel  30 , so that the outlet end  51  of tubular spindle  49  engages and folds sheet  6  of wrapping into a U against fixed folders  56  ( FIG. 9 ). At this point ( FIG. 10 ), group  2  of cigarettes is expelled from pocket  29  of input wheel  27  into tubular spindle  49  by pusher  52 . As it is inserted inside tubular spindle  49 , group  2  of cigarettes may be compressed laterally by the taper of the inner channel of tubular spindle  49 . 
     Finally, tubular spindle  49  returns to the withdrawn position in the opposite direction to the travelling direction of groups  2  of cigarettes, while group  2  of cigarettes is kept moving by pusher  52  and fed completely through tubular spindle  49  into pocket  32  together with sheet  6  of wrapping, which slides off tubular spindle  49  and wraps onto group  2  of cigarettes ( FIG. 11 ). 
     In a variation not shown, group  2  of cigarettes is first expelled from pocket  29  of input wheel  27  into tubular spindle  49  by a pusher  52 . When inserting group  2  of cigarettes inside tubular spindle  49 , tubular spindle  49  is stationary in a withdrawn position, and defines, with pocket  32  of wrapping wheel  30  and at feed station  33 , a gap through which a sheet  6  of wrapping is fed. 
     Next, tubular spindle  49 , together with the group  2  of cigarettes inside it, is moved towards wrapping wheel  30 , so that the outlet end  51  of tubular spindle  49  engages and folds sheet  6  of wrapping into a U against fixed folders  56   
     Finally, tubular spindle  49  returns to the withdrawn position in the opposite direction to the travelling direction of groups  2  of cigarettes, while group  2  of cigarettes is kept moving by pusher  52  and fed completely through tubular spindle  49  into pocket  32  together with sheet  6  of wrapping, which slides off tubular spindle  49  and wraps onto group  2  of cigarettes. 
     In the  FIG. 8-11  embodiment, folders  56  are fixed, and each spindle  49  travels a long way to complete folding sheet  6  of wrapping into a U about spindle  49 . The  FIG. 12-18  embodiment comprises two further movable folders  57 , which move in the opposite direction to each spindle  49  to complete folding sheet  6  of wrapping into a U about spindle  49 . In this case, each spindle  49  travels a short distance to fold sheet  6  of wrapping against fixed folders  56 , and sheet  6  of wrapping is folded into a U about spindle  49  mostly by the action of movable folders  57 . 
     In the  FIG. 12-18  variation, each spindle  49  is truncated-cone-shaped, tapering towards fixed folders  56 . More specifically, the outlet end  51  of each tubular spindle  49  is truncated-cone-shaped, and tapers in the travelling direction of group  2  of cigarettes; and an inlet end of fixed folders  56  is truncated-cone-shaped and complementary to the truncated-cone shape of the outlet end of tubular spindle  49 . 
     The way in which a group  2  of cigarettes and a respective sheet  6  of wrapping are fed into a pocket  32  of wrapping wheel  30  will now be described with reference to  FIGS. 12-18 . 
     Firstly, group  2  of cigarettes is expelled from pocket  29  of input wheel  27  (not shown in  FIGS. 12-18 ) into tubular spindle  49  by a pusher  52 . As it is inserted inside tubular spindle  49 , group  2  of cigarettes may be compressed laterally by the taper of the inner channel of tubular spindle  49 . When inserting group  2  of cigarettes, tubular spindle  49  is stationary in a withdrawn position ( FIG. 12 ), and defines, with pocket  32  of wrapping wheel  30  (not shown in  FIGS. 12-18 ) and at feed station  33 , a gap through which a sheet  6  of wrapping is fed. 
     Next, tubular spindle  49  is moved, together with group  2  of cigarettes, towards wrapping wheel  30 , so that outlet end  51  of tubular spindle  49  engages and folds sheet  6  of wrapping into a U against fixed folders  56  ( FIG. 14 ). At the same time (or even slightly before or after), movable folders  57  move in the opposite direction to each spindle  49  to complete folding sheet  6  of wrapping into a U about spindle  49  ( FIGS. 13 and 14 ). 
     Finally, group  2  of cigarettes is kept moving by pusher  52  and fed completely through spindle  49  into pocket  32  (not shown in  FIGS. 12-18 ) together with sheet  6  of wrapping, which slides off tubular spindle  49  and wraps onto group  2  of cigarettes ( FIG. 15 ). Once group  2  of cigarettes is expelled completely from spindle  49  ( FIG. 15 ), tubular spindle  49  returns to the withdrawn position in the opposite direction to the travelling direction of groups  2  of cigarettes, and, at the same time, a folder  58  folds one of the two flaps of the U-folded sheet  6  of wrapping onto group  2  of cigarettes ( FIG. 16 ). 
       FIG. 19  shows a variation of the  FIG. 12-18  embodiment, in which movable folders  57  are replaced by two nozzles  59  for directing compressed-air jets  60  onto the wings of sheet  6  of wrapping on opposite sides of tubular spindle  49  to complete folding sheet  6  of wrapping into a U about spindle  49 . The  FIG. 19  variation is simpler in design by substituting a fixed component (nozzles  59 ) for a movable component (movable folders  57 ) moving independently of the other components. 
     At feed station  33 , sheet  6  of wrapping is engaged, not by group  2  of cigarettes, but by corresponding spindle  49 , and is therefore folded into a U by spindle  49 , as opposed to group  2  of cigarettes, engaging it. Only after spindle  49  has prefolded sheet  6  of wrapping is group  2  of cigarettes inserted inside the already-folded sheet  6  of wrapping. By so doing, both ends of the cigarettes in group  2  undergo absolutely no mechanical stress when first folding sheet  6  of wrapping, thus preventing undesired deformation of both the filters and the tips of the cigarettes. Moreover, by virtue of spindles  49  cooperating with seats  50  or fixed folders  56 , the edges of inner package  1  are sharp and well defined, thus imparting an attractive square shape to the exposed top portion of inner package  1 .