Abstract:
A method of transferring wrappings, wherein each wrapping is defined by a sheet of wrapping material and has at least one flat wall, provides for feeding a wrapping along a curved path by means of a pocket of a conveyor; for guiding the wrapping along the curved path by means of a guide contacting the wrapping; and for moving a plate of the guide with respect to the pocket, so that a flat face of the plate is maintained contacting the entire flat wall of the wrapping along a portion of the curved path.

Description:
The present invention relates to a method of transferring articles hereafter referred to as wrappings. 
   The present invention may be used to advantage for transferring articles or so-called wrappings consisting of groups of cigarettes, each partly or fully enclosed in a sheet of wrapping material, to which the following description refers purely by way of example. 
   BACKGROUND OF THE INVENTION 
   A sheet of wrapping material wrapped about a group of cigarettes comprises a flat wall defined by a portion of the sheet of wrapping material contacting the group. 
   One known method of transferring wrappings of the above type comprises feeding the wrappings along a path by means of a pocket conveyor, each pocket of which houses a wrapping having a flat wall substantially free of the pocket; and guiding the wrappings by means of a guide facing the pockets and contacting the wrappings along said path. 
   When the pockets travel along a straight path, the guide is defined by a fixed plate having a flat sliding face, along which the wrapping slides in use. Automatic machine manufacturers, however, prefer to transfer packets of cigarettes on wheel conveyors, which are more reliable than chain or belt conveyors, so that the path of the pockets and relative fixed guide is curved as opposed to straight. Though performing the same functions as a straight guide, such as retaining the wrappings inside the pockets, a curved guide has disadvantages caused by the flat wall of the wrapping sliding along a curved sliding surface of the guide, so that the wrapping contacts the guide at edges on opposite sides of the flat wall. Just some of the disadvantages of the wrapping contacting the guide in this way are wear of the wrapping along the edges, deformation of the edges, and deformation of the flat wall, which tends to reproduce the curve of the guide under the centrifugal force of the group of cigarettes. 
   Deformation of the flat wall is further compounded when the wrapping, as it travels along the curved path, is subjected to folding, e.g. finish folding, operations which may induce deformation along the flat wall. In particular, folding portions of the wrapping directly connected to the flat wall induce deformation of the flat wall, unless the whole of the flat wall is supported. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a method of transferring wrappings with flat walls along paths having a curved portion, and designed to eliminate the drawbacks of the known state of the art. 
   According to the present invention, there is provided a method of transferring wrappings, wherein each wrapping is defined by at least one sheet of wrapping material and comprises at least one flat wall; the method comprising the steps of feeding a wrapping along a curved path by means of a pocket of a conveyor, and guiding the wrapping along said curved path by means of a guide contacting said wrapping; and the method being characterized by moving a plate of said guide with respect to said pocket, so that a flat face of said plate contacts the entire flat wall of said wrapping along a portion of said curved path. 
   The present invention also relates to a unit for transferring wrappings. 
   According to the present invention, there is provided a unit for transferring wrappings, wherein each wrapping is defined by at least one sheet of wrapping material and comprises at least one flat wall; the unit comprising a conveyor, in turn comprising at least one pocket for feeding a wrapping along a curved path, and a guide for guiding the wrapping along said curved path; and the unit being characterized in that said guide comprises at least one plate having a flat face and movable with respect to the conveyor to keep said flat face in contact with the entire flat wall of said wrapping along a portion of said curved path. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A number of non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which: 
       FIG. 1  shows a schematic side view, with parts in section and parts removed for clarity, of a unit for implementing the method according to the present invention; 
       FIGS. 2  to  5  show side views of a detail of the  FIG. 1  unit at different operating stages; 
       FIGS. 6 and 7  show side views, with parts in section and parts removed for clarity, of two operating stages of a variation of the  FIG. 1  unit; 
       FIGS. 8  to  12  show views in perspective of a wrapping at successive finishing stages. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Number  1  in  FIG. 1  indicates as a whole a unit for transferring wrappings  2  along a curved path P; each wrapping  2  comprising an orderly group  3  of cigarettes  4  wrapped in a sheet  5  of wrapping material. With reference to  FIGS. 8  to  12 , sheet  5  is wrapped gradually about group  3  in a number of folding operations. In  FIG. 8 , sheet  5  of wrapping material is folded partly into a tube about group  3 , and defines, among other things, a flat wall  6  contacting group  3 , and a free portion  7  adjacent to flat wall  6 . In  FIG. 9 , portion  7  is folded squarely with respect to wall  6 , so that wrapping  2  is in the form of a tube having four walls  6 ,  8 ,  9  and  10  in parallel pairs, and two tubular end portions  11  projecting with respect to group  3 . In  FIG. 10 , two tabs  12  and  13  of each tubular portion  11  are folded onto group  3  so that each tubular portion  11  has opposite tabs  14  and  15 . In  FIG. 11 , each tab  14  is folded onto group  3  and overlaps tabs  12  and  13 . And in  FIG. 12 , tabs  15  are folded onto group  3  and overlap tabs  14 . 
   With reference to  FIG. 1 , the various configurations of wrapping  2  described with reference to  FIGS. 8  to  12  are achieved as wrapping  2  is fed along path P by unit  1 . Unit  1  comprises a frame  16 , and a wheel  17  rotating about an axis  18  perpendicular to the  FIG. 1  plane, and supports a succession of pockets  19  equally spaced about axis  18  and for retaining respective wrappings  2 . Each pocket  19  comprises a supporting frame  20  rotating about an axis  21  parallel to axis  18 ; two lateral walls  22  rotating with respect to frame  20  about respective axes (not shown) parallel to axis  18 ; and a jaw  23  for retaining free portion  7  against a blade-shaped wall  22 . Each pocket  19  retains a respective wrapping  2  so that wall  6  of each wrapping faces outwards of wheel  17 . 
   Unit  1  also comprises, in succession along path P, four folding devices  24 ,  25 ,  26  and  27 , which cooperate with a guide  28  and provide for folding portion  7  and tabs  12 ,  13 ,  14  and  15  of each wrapping  2  as wrapping  2  travels in contact with guide  28 , which comprises two fixed bars  29 , three movable plates  30 ,  31  and  32 , and a fixed channel  33 . 
   Folding device  24  comprises a wheel  34  rotating about an axis  35  parallel to axis  18 ; and three folding blades  36  equally spaced about axis  35 . Plate  30  extends between wheel  17  and folding device  24 , rotates about an axis  37  parallel to axis  18 , is comb-shaped for engagement by blades  36 , and has a flat sliding face  38  facing the periphery of wheel  17 . 
   Folding device  25  comprises a wheel  39  rotating about an axis  40 ; and three articulated arms  41  equally spaced about axis  40 , and which open in the form of a fork, each supporting two folding members  42 . Plate  31  extends between folding device  25  and wheel  17 , rotates about an axis  43 , and comprises a toothed end  44  and a flat sliding face  45 . 
   Plate  32  has a flat sliding face  46  facing wheel  17 , and supports folding device  26 , which comprises two blades  47 , each extending perpendicularly to face  46  and supported over plate  32  by a flange integral with plate  32 . Plate  32  is connected to frame  16  by a beam  48 , which is fixed with respect to frame  16  and forms, with plate  32  and two arms  49  and  50  of different lengths, an articulated linkage assembly of quadrilateral form for varying the orientation of plate  32 . Arm  49  rotates about an axis  49   a  parallel to axis  18 , and is connected to a known actuator (not shown) to move plate  32  with respect to wheel  17 . Plate  32  also comprises two toothed ends  51 . 
   Folding device  27  comprises two rocker arms  52 , only one of which is shown in FIG.  1 . Each rocker arm  52  is hinged to beam  48  about an axis  53  parallel to axis  18 , and comprises two folding members  54  and  55 . Fixed channel  33  extends partly between folding device  27  and wheel  17 , and comprises a curved face  56  parallel to the periphery of wheel  17 ; two flat parallel circular faces  57 , only one of which is shown in  FIG. 1 ; and a toothed inlet portion  58  which cooperates with a toothed end  51  of plate  32 . 
   Wheel  17 , pockets  19 , movable plates  30 ,  31 ,  32 , and folding devices  24 ,  25 ,  27  are operated by respective known actuators not shown in the accompanying drawings. 
   In actual use, and with reference to  FIG. 1 , wheel  17  is rotated clockwise about axis  18  to feed wrappings  2  along curved path P, along which guide  28  is located. Along a first portion of path P, a wrapping  2  facing plate  30  is guided by plate  30  itself, which is oriented clockwise about its axis  37 . At the same time, pocket  19  is oriented anticlockwise about axis  21  to keep flat wall  6  of wrapping  2  parallel to and contacting flat face  38  of plate  30 . As wrapping  2  slides along face  38 , a blade  36  of folding device  24  engages plate  30  comb-fashion and folds portion  7  squarely with respect to wall  6  to obtain the wrapping  2  configuration shown in FIG.  9 . Jaw  23  is then closed to hold portion  7  in the folded position. 
   Upon wrapping  2  leaving plate  30 , pocket  19  is rotated clockwise about axis  21  to set wrapping  2  to a suitable position to slide along plate  31 , and plate  30  is rotated anticlockwise about axis  37  into a suitable position to receive the in-coming wrapping  2  of the next pocket  19 . In other words, the wrapping  2  retained by pocket  19  “skips” between successive plates  30  and  31  to allow pocket  19  and plate  30  to “rearm”. 
   Wall  6  of wrapping  2  slides along flat face  45  of plate  31  by virtue of plate  31  and pocket  19  rotating simultaneously as described above with reference to plate  30 . 
   With reference to  FIG. 2 , as wrapping  2  slides along plate  31 , two folding members  42  are moved into position over plate  31  and follow wrapping  2 . At the same time, arm  49  is rotated clockwise with respect to beam  48 , and tilts plate  32  so as to align face  46  of plate  32  with face  45  of plate  31  and intersect ends  44  and  51 .  FIG. 2  shows plates  31  and  32  in the aligned position. Plate  31  is then rotated anticlockwise, and plate  32  takes over from plate  31  in guiding wrapping  2 , as shown in FIG.  3 . Arm  49  is now rotated anticlockwise with respect to beam  48 , while pocket  19  is maintained in a fixed position, so that the articulated linkage assembly of quadrilateral form defined by beam  48 , by plate  32 , and by arms  49  and  50 , keeps face  46  parallel to and in contact with wall  6  of wrapping  2  to allow wall  6  to slide along face  46 . With reference to  FIG. 3 , as it slides along face  46 , wrapping  2  engages blades  47  of folding device  26 , and the two folding members  42  on either side of plate  32  catch up with wrapping  2  to fold respective tabs  13  and  12  and so obtain the configuration of wrapping  2  shown in FIG.  10 . 
   With reference to  FIG. 4 , gradual anticlockwise rotation of arm  49  causes end  51  of plate  32  to engage portion  58  of channel  33 . That is, face  46  is positioned tangent to curved face  56  of channel  33  to transfer wrapping  2  to channel  33 . At this stage, in which wall  6  contacts flat face  46  of plate  32 , wrapping  2  engages bars  29 , which are positioned directly beneath tabs  15 , and rocker arm  52  is swung anticlockwise about axis  53  so that folding members  54  fold tabs  14  into the  FIG. 11  configuration. Once tab  14  is folded, wrapping  2  is transferred to channel  33 , along which tab  15  is folded by member  55  of rocker arm  52  to obtain the  FIG. 12  configuration of wrapping  2 . The completed wrapping  2  is then fed along channel  33 , between opposite circular faces  57  and curved face  56 , and, once wrapping  2  is transferred to channel  33 , plate  32  is again tilted, by arm  49  rotating clockwise, to receive the next wrapping  2  from plate  31 , as shown in FIG.  5 . 
   As wrapping  2  is fed along curved path P, guide  28  provides, by virtue of movable plates  30 ,  31 ,  32 , for supporting substantially the whole of wall  6 , with respect to which portion  7  and tabs  12 ,  13 ,  14  are folded, thus preventing wall  6  from being deformed, as it would be with no support at all. 
   In the  FIG. 6  variation, unit  1  has no folding devices  24 ,  25 ,  26 ,  27 , and guide  28  is replaced by a guide  59  for simply guiding wrappings  2  along path P, and which comprises a number of articulated plates  60 . Each plate  60  comprises toothed opposite ends  61  which engage with the toothed ends  61  of the adjacent plates  60 ; a flat sliding face  62 ; and, on the opposite side to face  62 , two arms  63 ,  64  connected rigidly to plate  60 . Arm  63  is shorter than arm  64 , and is hinged to arm  64  of the adjacent plate  60  about an axis  65  parallel to axis  18  of wheel  17 . 
   Guide  59  comprises two transmissions  66  and  67 , which have two respective successions of rocker arms  68  and  69  pivoting about respective axes  70  and  71  and connected in pairs by respective rods  72  and  73 . 
   Rocker arms  68  and  69  alternate about wheel  17 , and are connected to alternate plates  60 . That is, one rocker arm  68  is hinged about an axis  74  to an arm  64  of a given plate  60 , and two rocker arms  69  adjacent to rocker arm  68  are hinged about axes  74  to arms  64  of two plates  60  adjacent to said given plate  60 . In other words, each plate forms part of an articulated linkage assembly of a pentagon form comprising the frame, rocker arm  68 , rocker arm  69 , arm  64  of the adjacent plate  60 , and plate  60  itself. 
   One of rocker arms  68  in succession  66  is connected to a known actuator (not shown), e.g. a cam actuator driven by the rotation of wheel  17 . One of rocker arms  69  is driven in the same way; and connection of rocker arms  68  and  69  by rods  72  and  73  provides for driving all the rocker arms  68  and  69  simultaneously using only two actuators. 
   Pockets  19  are equally spaced along the periphery of wheel  17  with an angular spacing PA, while plates  60  are equally spaced about axis  18  with an angular spacing of PA/2. 
   In actual use, wheel  17  is rotated continuously about axis  18  to feed the wrappings along curved path P, with flat wall  6  of each wrapping  2  facing outwards of wheel  17  and contacting plates  60 . With reference to  FIG. 6 , plates  60  are aligned in pairs, and wrappings  2  are located at ends  61  of two aligned plates  60  so that walls  6  simultaneously contact two adjacent plates  60 . The pairs of aligned plates  60  form an angle A with the adjacent pairs of aligned plates  60 , but the angle A area is not traveled over by wrappings  2 . As wheel  17  rotates clockwise in  FIG. 6 , wrappings  2  are fed along path P, and, at the same time, rocker arms  68  rotate anticlockwise and rocker arms  69  clockwise, so that faces  62  of plates  60  are kept contacting walls  6  with no need to orient pockets  19  about axes  21 , and the adjacent plates  60  forming angle A in the  FIG. 6  configuration are aligned. With reference to  FIG. 7 , rotation of wheel  17  by an angle of PA/2 aligns the plates  60  forming angle A in  FIG. 6 , and forms an angle A between the adjacent plates  60  aligned in FIG.  6 . Further rotation of wheel  17  by an angle PA/2 produces two, respectively clockwise and anticlockwise, rotations of rocker arms  68  and  69  to restore plates  60  to the  FIG. 6  configuration. That is, at each rotation by an angle PA, rocker arms  68  and  69  perform two opposite back and forth movements.