Abstract:
A method and device for producing a rigid container, having two end walls and a lateral wall, from a flat blank having two flat first portions, each of which has a relative panel defining a relative end wall of the container, and a drawn rim integral with the panel, extending along at least one portion of an outer edge of the panel, and square with respect to the panel; and three flat second portions alternating with the two panels; each panel being folded squarely with respect to the flat second portions adjacent to it; the second portions being wrapped about and onto the rims to form the lateral wall; and each panel being stiffened by means of an external stiffening member, at least when forming the lateral wall.

Description:
BACKGROUND OF THE INVENTION 
   More specifically, the present invention relates to a method and device for producing a rigid container, comprising two end walls and a lateral wall, from a flat blank comprising two flat first portions, each of which comprises a panel defining a relative said end wall of the container, and a drawn rim integral with the panel and extending, squarely with respect to the panel, along at least one portion of an outer edge of the panel; and three flat second portions alternating with said two panels; each said panel being folded squarely with respect to the flat second portions adjacent to it, and said second portions being wrapped about and onto said rims to form said lateral wall. 
   Though suitable for producing any type of container, the present invention is particularly advantageous for use in the tobacco industry, for producing, on a packing machine, containers defined by hinged-lid cigarette packets, and particularly hinged-lid packets having a substantially oval cross section, as described and illustrated in the Applicant&#39;s International Patent Application N. WO-A-03/080474, to which the following description refers purely by way of example. 
   Particularly when working with high-speed packing machines operating at an output speed in the region of 7–10 packets a second, producing packets of the above type poses various difficulties, due to possible inward flexing of the rims when said second portions are wrapped about and onto the rims of said first portions, thus resulting, in view of the relatively small transverse dimensions of the rims, in failure to close the packets. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a method of producing a container of the type described above, designed to provide a straightforward, low-cost solution to the above problems. 
   According to the present invention, there is provided a method of producing a rigid container for a product, the container comprising two end walls and a lateral wall, and being formed from a flat blank comprising two first portions, each of which comprises a relative panel defining a relative said end wall of the container, and a drawn rim integral with the panel, extending along at least one portion of an outer edge of the panel, and square with respect to the panel; and three second portions alternating with said two panels, one of said second portions being an intermediate second portion with respect to said two panels; the method comprising the steps of folding each said panel squarely with respect to the second portions adjacent to it, and wrapping said second portions about and onto said rims to form said lateral wall; and being characterized by comprising the further step of stiffening each said panel at least during said step of forming said lateral wall. 
   According to the present invention, there is also provided a device for producing a rigid container for a product, the container comprising two end walls and a lateral wall, and being formed from a flat blank comprising two first portions, each of which comprises a relative panel defining a relative said end wall of the container, and a drawn rim integral with the panel, extending along at least one portion of an outer edge of the panel, and square with respect to the panel; and three second portions alternating with the two panels, one of said second portions being an intermediate second portion with respect to said two panels; the device comprising first folding means for folding said panels into respective square positions with respect to the second portions adjacent to them; and second folding means for wrapping said second portions about and onto the rims to form said lateral wall; the device being characterized by comprising, for each said panel, stiffening means for stiffening each panel at least when the panel, in use, is in the relative said square 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, schematically and partly in section, a preferred embodiment of the device according to the present invention; 
       FIG. 2  shows a section of a detail in  FIG. 1  in two distinct operating positions; 
       FIG. 3  is similar to  FIG. 1 , and shows the  FIG. 1  device in a further operating position; 
       FIG. 4  shows a larger-scale view in perspective of a packet produced by the  FIG. 1  device; 
       FIG. 5  shows a plan view of a blank which is folded by the  FIG. 1  device to produce the  FIG. 4  packet; 
       FIG. 6  shows a larger-scale plan view of a detail in  FIG. 1 ; 
       FIG. 7  shows a larger-scale, exploded view in perspective of a detail in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Number  1  in  FIG. 1  indicates as a whole a folding device for producing a rigid packet  2  of cigarettes from a blank  3 . 
   As shown in  FIG. 4 , packet  2  has a longitudinal axis  4 , and comprises two substantially oval end walls  5  and  6 ; and a tubular lateral wall  7 , on which a cut line  8  defines a lid  9 , incorporating end wall  5 , and a body  10 , incorporating end wall  6 , connected to each other by a hinge  11  aligned with cut line  8 . 
   As shown in  FIG. 5 , blank  3  comprises three substantially rectangular panels  12 ,  13 ,  14  aligned along a longitudinal axis  15 , and of which panel  13  is divided into two parts by cut line  8  and hinge  11 ; and two substantially oval panels  16 ,  17 . Panel  16  is interposed between panels  12  and  13 , and is connected to panels  12  and  13  along respective preformed fold lines  18  and  19 , both crosswise to longitudinal axis  15 ; and panel  17  is interposed between panels  13  and  14 , and is connected to panels  13  and  14  along respective preformed fold lines  20  and  21  parallel to preformed fold lines  18  and  19 . 
   Panels  16  and  17  are used to form end walls  5  and  6  of packet  2 , and panels  12 ,  13  and  14  for forming lateral wall  7  of packet  2 . 
   Along two curved outer peripheral portions  22  located specularly with respect to longitudinal axis  15 , each panel  16 ,  17  has two curved strips  23 , each of which projects outwards from relative portion  22 , and is subsequently drawn, prior to any further folding of blank  3 , to form a relative rim  24  ( FIG. 4 ) projecting squarely from relative panel  16 ,  17  and which provides for supporting and connecting the relative-axial end of lateral wall  7  of packet  2 . 
   As shown more clearly in  FIG. 7 , the drawing operation referred to above forms, along each rim  24 , pleats  25  projecting inwards with respect to relative rim  24  and for receiving glue, which performs the dual function of ensuring firm connection of lateral wall  7  to relative end wall  5 ,  6 , and, when dried, of strengthening relative rim  24 . 
   As shown in  FIGS. 1 to 3 , folding device  1  has a longitudinal axis  26 , and comprises a frame  27  bounded at the front by a plate  28  having, at the front, a flat surface  29  perpendicular to longitudinal axis  26 . Surface  29  is a substantially rectangular surface similar in size to panel  13 , is positioned with its own longitudinal axis perpendicular to longitudinal axis  26 , and has a central cavity  30  which communicates centrally with a funnel  31  defining the output member of a suction circuit  32 . 
   Folding device  1  also comprises two folding members  33  and  34  located on opposite sides of plate  28 , and each of which comprises a front plate  35  fitted at the rear with a respective appendix  36  bounded laterally by a respective pair of surfaces  37  parallel to each other and to the  FIG. 1-3  planes. Each plate  35  is bounded at the front by a surface  38 , in which is formed, as shown in  FIG. 6 , a central star-shaped cavity  39  surrounded by an annular groove  40  housing a seal  41  and having an outer edge  42  of substantially the same shape and size as panels  16  and  17 . 
   The two folding members  33  and  34  are supported by frame  27  with the interposition of respective actuating devices  43  which are located on opposite sides of, and specularly with respect to, longitudinal axis  26 , and which provide for moving respective plates  35  between a rest position ( FIG. 1 ), in which surfaces  38  of plates  35  are coplanar with surface  29  of plate  28 , and a work position ( FIG. 3 ), in which surfaces  38  of plates  35  are perpendicular to surface  29  of plate  28 , by being rotated  900 , in opposite directions as of the rest position, about respective axes  44  and  45  perpendicular to the  FIG. 1-3  planes and each coincident with an edge of respective plate  35  facing plate  28 . More specifically, actuating devices  43  support the two folding members  33  and  34  so that the two axes  44  and  45  are parallel, are separated by a distance equal to the distance between lines  19  and  20  on blank  3 , and are parallel to and face respective minor sides of plate  28 . 
   As shown more clearly in  FIG. 2 , each cavity  39  communicates centrally with a respective conduit  46  formed through relative plate  35  and relative appendix  36 , and in turn communicating with a curved pipe  47 , which engages in axially sliding manner a respective curved conduit  48  formed through frame  27  and plate  28  about relative axis  44 ,  45  and terminating inside cavity  30 . 
   As shown in  FIGS. 1 and 3 , each actuating device  43  comprises an articulated parallelogram transmission  49 , which comprises two connecting rods  50  and  51  located on opposite sides of relative appendix  36 , and hinged to appendix  36  by two pins  52  and  53  parallel to, and defining a through plane for, relative axis  44 ,  45 . The two connecting rods  50  and  51  are supported by frame  27  with the interposition of two crank members  54  and  55 , each of which comprises two superimposed arms  56  and  57 , which are located on the same side as connecting rod  50  and  51  respectively, and are connected to each other by two pins  58  and  59  parallel to relative axis  44 ,  45  and separated by the same distance as between pin  52  and relative axis  44 ,  45 . Pin  58  extends through frame  27 , and pin  59  extends through connecting rod  50 . More specifically, pin  58  of crank member  54  is a powered pin. 
   Arm  57  is longer than arm  56 , extends beyond connecting rod  50 , and is connected at its free end to connecting rod  51  by a pin  60  parallel to pins  58  and  59  and separated from pin  59  by the same distance as between pin  53  and pin  52 . Crank members  54  and  55  are parallel to each other and to the plane defined by the respective pair of pins  52  and  53 , so that the relative folding member  33 ,  34  defines, for the relative actuating device  43 , a further crank which, when relative crank members  54  and  55  are rotated about the axes of relative pins  58  by pin  58  of crank member  54 , rotates with respect to frame  27  and plate  28  about a virtual hinge whose axis coincides with respective axis  44 ,  45 . 
   In actual use, folding device  1  is initially set to the rest position ( FIG. 1 ) with surfaces  38  coplanar with surface  29 , and blank  3  is fed onto folding device  1  so that panel  13  contacts surface  29 , lines  19  and  20  are located at respective axes  44  and  45 , and panels  16  and  17  contact surfaces  38  of plates  35  of respective folding members  33  and  34 . At this point, blank  3  is clamped in position ( FIG. 2 ) by feeding onto panel  13 , by means of a pusher  61 , a product  62  defined, in the example shown ( FIG. 4 ), by a group  63  of cigarettes enclosed in a foil wrapping  64 . 
   In connection with the above, it should be pointed out that panel  13  cuts off outside communication of cavity  30 , while each panel  16 ,  17  is positioned with its periphery contacting relative seal  41 , thus cutting off outside communication of relative cavity  39 . 
   When suction circuit  32  is activated, panel  13  is clamped firmly to plate  28 , and, by means of suction along conduits  48 , pipes  47  and conduits  46 , panels  16  and  17  are clamped firmly to respective folding members  33  and  34 . In other words, the two panels  16  and  17 , being sucked onto respective surfaces  38 , are stiffened completely by contact with respective external elements defined by folding members  33  and  34 . 
   At this point, pins  58  of crank members  54  of actuating devices  43  are activated to rotate folding members  33  and  34  ( FIG. 2 ) about respective axes  44  and  45  into the work position, and so simultaneously fold panels  16  and  17  squarely about relative lines  19  and  20 . Over a final portion of their rotation, folding members  33  and  34  fit rims  24  onto the respective ends of product  62  to retain product  62  transversely on plate  28 . 
   Pusher  61  is then withdrawn and, following operation of known external folders  65  ( FIG. 2 ) which fold panels  12  and  14  squarely about relative lines  18  and  21 , is replaced by a known folding head  66  ( FIG. 3 ) which folds the lateral portions of panels  12 ,  13  and  14  onto rims  24  to form lateral wall  7  and so complete packet  2 . 
   In connection with the above, it should be pointed out that, if panels  16  and  17  were not stiffened externally, the pressure applied by panels  12 ,  13  and  14  on rims  24  when forming lateral wall  7  would be transmitted as a bending moment through the right-angle—which remains substantially undeformed—defined by each rim  24  and relative panel  16 ,  17 , and could result in flexing of panels  16  and  17 , and in poor connection of lateral wall  7  to rims  24 . In the case of folding device  1 , this is prevented by preventing panels  16  and  17  from flexing, by clamping them by suction on relative folding members  33  and  34  throughout the formation of packet  2 . 
   Folding members  33  and  34  of folding device  1  may be replaced by straightforward walls similar to plates  35 , but hinged directly to opposite edges of plate  28  by hinges whose axes, for practical reasons, cannot be located in the surface  29  plane. In this case, as opposed to being fixed like axes  44  and  45 , the lines of intersection between surfaces  38  of plates  35  and surface  29  of plate  28  move towards each other along surface  29  up to lines  19  and  20 , so that, as plates  35  rotate, the two panels  16  and  17  slide on relative surfaces  38  until plates  35  reach the work position. Consequently, when using hinged plates  35 , panels  16  and  17  cannot be clamped from the outset to relative plates  35 , and can only be stiffened by suction after being folded squarely; and panel  13 , as opposed to also being clamped to plate  28  by suction, is only clamped by feeding product  62  onto plate  28 .