Abstract:
A folding method and device, whereby a tubular wrapping is formed about a product by inserting the product inside a U-shaped pocket together with a sheet of wrapping material, a first lateral portion of which is interposed between the product and a first lateral wall of the pocket, and a second lateral portion of which, opposite the first, is folded outside and beyond the pocket and crosswise to the first lateral portion; the tubular wrapping being closed by moving the first lateral wall of the pocket outwards, simultaneously moving a contrast member onto the first lateral portion, and then folding the second lateral portion, by means of an external folding member, onto the product and so as to overlap the first lateral portion; and the tubular wrapping being fixed inside the pocket by withdrawing the external folding member, simultaneously closing the first lateral wall onto the product, and withdrawing the contrast member ( 34 ) from the pocket.

Description:
The present invention relates to a folding method and device for forming a tubular wrapping about a product, whereby the product, together with a sheet of wrapping material, is inserted inside a U-shaped pocket having a longitudinal axis and comprising a first and a second lateral wall parallel to said longitudinal axis, to fold the sheet of wrapping material so that a first lateral portion of the sheet of wrapping material is interposed between the product and the first lateral wall of the pocket, and a second lateral portion of the sheet of wrapping material, opposite the first, is folded outside and beyond the pocket and crosswise to the first lateral portion. 
   BACKGROUND OF THE INVENTION 
   Though suitable for wrapping any type of product, in particular substantially parallelepiped-shaped products, the present invention may be used to advantage in the tobacco industry for wrapping groups of cigarettes to form inner packets and/or for wrapping inner packets to form so-called “soft” packets, to which the following description refers purely by way of example. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a folding method as described above, for producing a tubular wrapping, which is easy to implement, is particularly suitable for use on continuous machines, i.e. in which said pocket is fed continuously along an endless path, and ensures closure of the tubular wrapping without subjecting the sheet of wrapping material to inevitably harmful shock against fixed folding members. 
   According to the present invention, there is provided a folding method for forming a tubular wrapping about a substantially parallelepiped-shaped product, the method comprising the steps of inserting the product, together with a sheet of wrapping material, inside a U-shaped pocket having a longitudinal axis and comprising a first and a second lateral wall parallel to said longitudinal axis, so as to fold said sheet of wrapping material so that a first lateral portion of the sheet of wrapping material is interposed between the product and said first lateral wall, and a second lateral portion of the sheet of wrapping material, opposite the first, is folded outside and beyond the pocket and crosswise to the first lateral portion; the method being characterized by comprising the further steps of moving said first lateral wall from a closed position contacting the product, to an open position opening said pocket, while at the same time holding said first lateral portion folded down on the product by moving a contrast member from a rest position outside said pocket, to a work position contacting the first lateral portion; subsequently folding said second lateral portion onto the product, and so as to overlap the first lateral portion, by inserting an external folding member into the pocket; returning said first lateral wall to the closed position, and said contrast member to said rest position; and withdrawing said external folding member from the pocket. 
   According to the present invention, there is also provided a device for laterally closing a tubular wrapping about a substantially parallelepiped-shaped product, the device comprising a U-shaped pocket having a longitudinal axis and in turn comprising a first and a second lateral wall parallel to said longitudinal axis, said pocket receiving a product with the interposition of a sheet of wrapping material comprising a first lateral portion interposed between the product and said first lateral wall, and a second lateral portion opposite the first and extending outside and beyond the pocket and crosswise to the first lateral portion; the device being characterized in that said first lateral wall is movable between a closed position and an open position respectively closing and opening said pocket; and by comprising an external folding member for engaging and inserting said second lateral portion inside said pocket and into a position overlapping said first lateral portion when said first lateral wall is in the open position; and a contrast member movable between a rest position outside said pocket, and a work position inside said pocket to hold said first portion folded down on said product when said first lateral wall is in the open position. 

   
     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 section of a preferred embodiment of the folding device according to the present invention in one operating position; 
       FIGS. 2 to 6  are similar to  FIG. 1 , and show the  FIG. 1  folding device in further different operating positions; 
       FIG. 7  shows a larger-scale view in perspective of a detail in  FIGS. 1 to 6 ; 
       FIG. 8  shows a larger-scale view of a detail in  FIG. 4 ; 
       FIG. 9  shows a larger-scale view of a detail in  FIG. 5 ; 
       FIG. 10  shows a larger-scale view of a detail in  FIG. 6 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Number  1  in  FIGS. 1 to 6  indicates as a whole a folding device fitted to a wrapping machine  2  to form a tubular wrapping  3  ( FIG. 9 ), defined by a sheet of wrapping material  4 , about a substantially parallelepiped-shaped product—in the example shown, a group  5  of cigarettes  6 . 
   Device  1  comprises a wrapping wheel  7  fitted to wrapping machine  2  to rotate continuously clockwise, in  FIGS. 1 to 6 , about an axis (not shown) perpendicular to the  FIG. 1  plane. Wrapping wheel  7  supports a number of folding heads  8  (only one shown) equally spaced about the axis (not shown) of wrapping wheel  7 , and each comprising a cylindrical base  9  fitted to wrapping wheel  7  to oscillate, under the control of a known control device not shown, about a respective axis  10  parallel to the axis (not shown) of wrapping wheel  7 . Each folding head  8  also comprises a radial tubular arm  11 , which has an axis  12 , extends outwards of wrapping wheel  7  from relative base  9 , and oscillates in known manner with relative base  9  about relative axis  10 . Tubular arm  11  houses a rod  13 , coaxial with axis  12 , of a pusher  14 , which also comprises a plate fitted to the free end of rod  13  and defining the end wall  15  of a U-shaped pocket  16 , which is positioned with its concavity facing outwards of wrapping wheel  7 , has a longitudinal axis  17  ( FIG. 2 ) parallel to relative axis  10 , and houses a respective group  5  with relative cigarettes  6  extending parallel to longitudinal axis  17 . 
   End wall  15  is crosswise to respective axis  12 , and relative pocket  16  also comprises a lateral wall  18  downstream in the travelling direction of pocket  16 ; and a lateral wall  19 , which is upstream in the travelling direction of pocket  16 , faces and is substantially parallel, at least in a closed work position, to lateral wall  18 , and is crosswise to end wall  15 . 
   Lateral wall  18  is defined by one arm of a rocker arm  20 , which is hinged to the end of tubular arm  11  to oscillate, with respect to tubular arm  11 , about an axis  21  parallel to relative axis  10 , and comprises a further arm, which extends inside tubular arm  11 , alongside rod  13 , and defines a tappet  22 , which is pushed by a spring  23  into contact with a cam  24  fitted to rod  13  and movable with rod  13  to set lateral wall  18  to a normal closed position ( FIG. 2 ) when end wall  15  is withdrawn to the back of pocket  16 , and to an open position when end wall  15  is in an extracted position ( FIG. 1 ) outside lateral walls  18  and  19 . 
   Lateral wall  19 , which is similar in form to lateral wall  18 , is defined by the free end of one arm  25  of a rocker arm  26  fitted to a powered shaft  27 , which is parallel to relative axis  10  and oscillates about a respective axis to move relative lateral wall  19  between said closed work position ( FIG. 6 ) and an open position ( FIG. 3 ). Lateral wall  19  is also provided, on a front surface  28 , with a heating device  29 . 
   Rocker arm  26  comprises a further arm  30 , which extends substantially perpendicularly to relative arm  25  towards relative axis  12 , and is fitted on its free end with a pin  31  parallel to relative axis  10  and sliding transversely inside an axial slot  32  of a link  33  fitted to tubular arm  11  to oscillate about axis  21 . Link  33  extends from axis  21  towards rocker arm  26 , and is fitted on its free end with a contrast member defined by a plate  34 , which is substantially perpendicular to link  33  and oscillates with link  33  between a withdrawn rest position ( FIG. 6 ), in which plate  34  is positioned radially inwards of relative pocket  16 , and a forward work position ( FIG. 4 ), in which plate  34  is positioned partly inside relative pocket  16 , with a front lateral surface  35  of plate  34  positioned coplanar with the position occupied by front surface  28  of relative lateral wall  19  when lateral wall  19  is in the closed work position. 
   Link  33  and rocker arm  26  are connected, by relative pin  31  engaging relative slot  32 , so that, when relative lateral wall  19  moves to and from the closed work position, plate  34  moves to and from the withdrawn rest position. 
   With reference in particular to  FIGS. 3 to 6 , wrapping wheel  7  feeds pockets  16  continuously along an endless, in particular, circular path P extending through a folding station  36 , through which pockets  16  travel successively, and which comprises a disk  37  fitted to wrapping machine  2  to rotate continuously anticlockwise, in  FIGS. 3 to 6 , about an axis  38  parallel to axis  10 . Folding station  36  also comprises a shaft  39  fitted through disk  37 , parallel to and eccentric with respect to axis  38 , to oscillate about a respective axis under the control of a known cam device (not shown); and a folding member  40  defined by a blade fitted to shaft  39  and extending outwards of disk  37  from shaft  39 . 
   Operation of device  1  will be described below with reference to one pocket  16  and one group  5 , which, on reaching, in known manner, a position facing pocket  16  together with a respective sheet of wrapping material  4 , is fed, in known manner, along path P at the same speed as pocket  16 , and is gripped between a pusher  41  ( FIG. 1 ) external to pocket  16 , and end wall  15  moved by pusher  14  into an extracted position ( FIG. 1 ) radially outwards of lateral walls  18  and  19 , which are both in the open position, lateral wall  18  by tappet  22  contacting cam  24  fitted to rod  13 , and lateral wall  19  by operation of shaft  27 . 
   Subsequent movement of end wall  15  and external pusher  41  inwards of wrapping wheel  7 , together with a simultaneous movement of lateral wall  18  and a subsequent movement of lateral wall  19  into their closed positions ( FIG. 2 ), forms pocket  16  and causes insertion inside pocket  16  of group  5  and relative sheet of wrapping material  4 , which, as it is being inserted inside pocket  16 , is folded about group  5  to define a narrow portion  42  contacting front surface  28  of lateral wall  19  and of a transverse dimension smaller than half the width of lateral wall  19 ; an inner portion  43  extending along end wall  15 ; and a lateral portion  44  extending along lateral wall  18 . A portion, integral with lateral portion  44 , of the sheet of wrapping material  4  projects from pocket  16 , and comprises an outer portion  45 , which, as pocket  16  travels along path P, is folded ( FIG. 2 ) in known manner, e.g. by encountering an outer plate  46 , onto group  5  into a position parallel to and facing inner portion  43 ; and a portion  47  projecting rearwards, in the form of an extension of portion  45 , outwards of and beyond pocket  16  in a direction crosswise to portion  42 . Portion  47  is of a transverse dimension greater than the transverse dimension of portion  42 , and greater than the width of front surface  28  of lateral wall  19  minus the width of portion  42 . 
   Pocket  16 , together with relative group  5  and relative sheet of wrapping material  4 , is then fed by wrapping wheel  7  through folding station  36 , prior to reaching which, lateral wall  19  is moved, by oscillation of powered shaft  27  and in the opposite direction to the travelling direction of pocket  16 , from the closed work position shown in  FIG. 2 , to the open position shown in  FIGS. 3 to 5 . 
   At the same time, the coupling between pin  31  and slot  32  causes relative plate  34  to move from the withdrawn rest position to the forward work position, in which plate  34  is positioned parallel to axis  12 , with its lateral surface  35  contacting portion  42  ( FIGS. 4 and 8 ) to hold portion  42  folded down on group  5  throughout the time lateral wall  19  remains in the open position. 
   Pocket  16 , still with lateral wall  19  in the open position, eventually reaches folding station  36  ( FIG. 4 ) where, by continuous rotation of disk  37  about axis  38  and oscillation of shaft  39 , folding member  40  accompanies pocket  16  rotating about the axis (not shown) of wrapping wheel  7 , and, at the same time, is inserted radially through plate  46  into pocket  16 , between group  5  and lateral wall  19  in the open position, to fold portion  47  ( FIG. 4 ) inside pocket  16 , onto group  5 , and into a position at least overlapping portion  42  ( FIGS. 5 and 9 ). 
   As shown in  FIG. 7 , to enable passage of folding member  40  through plate  46 , plate  46  is defined, at least at folding station  36 , by a number of parallel strips  48 , and the blade defining folding member  40  is comb-shaped, and comprises a succession of teeth  49 , each of which engages a relative gap defined between two adjacent strips  48 . 
   After smoothing portion  47  onto group  5  ( FIGS. 5 and 9 ), folding member  40  withdraws from pocket  16 , while still remaining substantially parallel to lateral wall  18  ( FIGS. 6 and 10 ). Just before folding member  40  withdraws, lateral wall  19  is returned to the closed work position, thus moving plate  34  into the withdrawn rest position. As shown in  FIG. 7 , for it to close fully despite the presence of folding member  40 , lateral wall  19  comprises an end portion defined by a row of teeth  50 , which, when lateral wall  19  is in the closed work position, engage teeth  49  of folding member  40  comb-fashion. 
   As front surface  28  of lateral wall  19  contacts lateral portion  47 , the heating device  29  on lateral wall  19  glues portion  47  to portion  42 , at the overlap between portions  42  and  47 , by melting hot-melt glue (not shown) deposited beforehand on at least one of portions  42  and  47 . Alternatively, if the sheet of wrapping material  4  is made of heat-seal material, heating device  29  simply seals portions  42  and  47  to each other.