Abstract:
Packaging material configured to be folded and sealed to produce a gable-top package for pourable food products comprises a web of material provided with a crease pattern along which the web of material is foldable. The crease pattern includes first and second transverse fold lines extending transversely across the material web, and a plurality of longitudinal fold lines extending longitudinally away from the first transverse fold line toward the opposite longitudinal end of the web of material, with adjacent pairs of the longitudinal fold lines defining respective walls of the gable-top package when the packaging material is folded and sealed. The crease pattern also includes a pair of oblique fold lines extending obliquely from the first transverse fold line to the second transverse fold line such that an area enclosing triangular panels is bounded by the oblique lines and portions of the first and second transverse fold lines.

Description:
[0001]    This application is a continuation of U.S. application Ser. No. 12/162,564 filed on Jul. 29, 2008 which is a U.S. national stage application based on International Application No. PCT/EP2007/051817 filed on Feb. 26, 2007 and which claims priority to European Application No. 06110477.4 filed on Feb. 29, 2006, the entire content of all three of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a folding assembly and method for producing a gable portion of a sealed package of a pourable food product. The folding assembly can be integrated in a folding unit of packaging machines for continuously producing sealed packages of pourable food products from a tube of packaging material. 
       BACKGROUND DISCUSSION 
       [0003]    Many pourable food products, such as beverages, fruit juice, pasteurized or UHT (ultra-high-temperature treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material. 
         [0004]    One example of this type of package is the gable-top package for liquid or pourable food products, as described in European Patent EP1440010 and in published Patent Application EP1584563, and known by the trade name Tetra Gemina™ Aseptic. 
         [0005]    More specifically, the above package comprises a parallelepiped-shaped main portion; and a gable top portion defined by two sloping walls joined along a sealing strip. 
         [0006]    More specifically, the walls of the gable portion are trapezoidal in shape, project from the main portion of the package at their respective major bases, and are joined by the sealing strip at their respective minor bases. 
         [0007]    The gable portion comprises two lateral flaps folded outside the volume of the package available for the food product. 
         [0008]    The flaps each project from a respective oblique side of a first wall, and are folded towards the second wall and superimposed, at the sealing strip, on respective oblique sides of the second wall. 
         [0009]    The above package is produced by folding and sealing laminated strip packaging material. 
         [0010]    The packaging material has a multilayer structure substantially comprising a base layer for stiffness and strength, which may comprise a layer of fibrous material, e.g. paper, or mineral-filled polypropylene material; and a number of layers of heat-seal plastic material, e.g. polyethylene film, covering both sides of the base layer. 
         [0011]    In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of gas- and light-barrier material, e.g. aluminium foil or ethyl vinyl alcohol (EVOH) film, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of the package eventually contacting the food product. 
         [0012]    As is known, packages of this sort are produced on fully automatic packaging machines, on which a continuous tube is formed from the web-fed packaging material. More specifically, the web of packaging material is unwound off a reel and fed through an aseptic chamber on the packaging machine, where it is sterilized, e.g. by applying a sterilizing agent, such as hydrogen peroxide, which is subsequently evaporated by heating and/or by subjecting the packaging material to radiation of appropriate wavelength and intensity; and the web so sterilized is maintained in a closed, sterile environment, is folded into a cylinder, and is sealed longitudinally to form a continuous tube in known manner. 
         [0013]    The tube of packaging material, actually forming an extension of the aseptic chamber, is fed continuously in a vertical direction, is filled with the sterilized or sterile-processed food product, and is fed through a forming unit for producing the individual packages. That is, inside the forming unit, the tube is sealed along a number of equally spaced cross sections to form a continuous strip of pillow packs connected to one another by respective transverse sealing strips, i.e. extending perpendicular to the travelling direction of the tube. And the pillow packs are separated by cutting the relative transverse sealing strips, and are then folded further to form respective finished gable-top packages. 
       SUMMARY 
       [0014]    A packaging material is configured to be folded and sealed to produce a gable-top package for pourable food products which possesses top and bottom portions. The packaging material comprises a web of material provided with a crease pattern along which the web of material is foldable to form the gable-top package. The crease pattern comprises: a first transverse fold line extending transversely across the web of material between one longitudinally extending side edge of the web of material and an opposite longitudinally extending side edge of the web of material; and a second transverse fold line extending transversely across the web of material between the one longitudinally extending side edge of the web of material and the opposite longitudinally extending side edge of the web of material. The second transverse fold line is positioned at one longitudinal end of the web of material and defines a top sealing area at which the web of material is sealed when the packaging material is folded and sealed to form the top portion of the gable-top package, while the first transverse fold line is spaced from the second transverse fold line in a direction toward an opposite longitudinal end of the web of material. A plurality of longitudinal fold lines extends longitudinally away from the first transverse fold line toward the opposite longitudinal end of the web of material, with adjacent pairs of the longitudinal fold lines defining respective walls of the gable-top package when the packaging material is folded and sealed. A pair of oblique fold lines each extend obliquely from the first transverse fold line to the second transverse fold line such that an area is bounded by the pair of oblique lines, by a portion of the second transverse fold line extending between the pair of oblique fold lines and by a portion of the first transverse fold line extending between the pair of oblique fold lines, and such area encloses six, and no more than six, triangular panels, each of the triangular panels being outlined by three fold lines forming a part of the crease pattern. 
         [0015]    Another aspect involves packaging material configured to be folded and sealed to produce a gable-top package for pourable food products which possesses top and bottom portions, wherein the packaging material includes a web of material provided with a crease pattern along which the web of material is foldable to form the gable-top package. The crease pattern on the web of packaging material comprises: a pair of transverse fold lines extending transversely across the web of material between longitudinally extending opposite side edges of the web of material, wherein the pair of transverse fold lines includes a first transverse fold line and a second transverse fold line, and wherein the second transverse fold line is positioned at one longitudinal end of the web of material and defines a top sealing area at which the web of material is sealed when the packaging material is folded and sealed to form the top portion of the gable-top package, and wherein the first transverse fold line is spaced from the second transverse fold line in a direction toward an opposite longitudinal end of the web of material. Four longitudinal fold lines each intersect the first transverse fold line at a respective first intersection point and extending longitudinally away from the first transverse fold line toward the opposite longitudinal end of the web of material, with adjacent pairs of the longitudinal fold lines defining respective walls of the gable-top package when the packaging material is folded and sealed. A pair of first oblique fold lines each extend obliquely between the first and second transverse fold lines so that each first oblique fold line intersects the first transverse fold line at a respective one of the first intersection points and intersects the second transverse fold line at a respective second intersection point, with each first oblique fold line intersecting the second transverse fold line so that one portion of the second transverse fold line is located between the second intersection points, and each first oblique fold line intersecting the first transverse fold line so that one portion of the first transverse fold line is located between the first intersection points. The pair of first oblique fold lines, in combination with the one portion of the first transverse fold line and the one portion of the second transverse fold line, defines a first area possessing an isosceles trapezoid shape, wherein the first area encloses six, and no more than six, triangular panels which are each outlined by three fold lines forming a part of the crease pattern. A pair of second oblique fold lines each extend obliquely between the first and second transverse fold lines so that each second oblique fold line intersects the first transverse fold line at a respective third intersection point and intersects the second transverse fold line at a respective fourth intersection point, wherein each second oblique fold line intersects the second transverse fold line so that a portion of the second transverse fold line is located between the fourth intersection points, and wherein each second oblique fold line intersects the first transverse fold line so that a portion of the first transverse fold line is located between the third intersection points. The pair of second oblique fold lines, in combination with the portion of the first transverse fold line located between the third intersection points and the portion of the second transverse fold line located between the fourth intersection points, define a second area possessing an isosceles trapezoid shape. The second area encloses six, and no more than six, triangular panels which are each outlined by three fold lines forming a part of the crease pattern. 
         [0016]    In accordance with another aspect, a packaging material configured to be folded and sealed to produce a gable-top package for pourable food products which possesses top and bottom portions comprises: a web of material provided with a crease pattern along which the web of material is foldable to form the gable-top package. The crease pattern on the packaging material web comprises: a first transverse fold line extending transversely across the web of material between one longitudinally extending side edge of the web of material and an opposite longitudinally extending side edge of the web of material; and a second transverse fold line extending transversely across the web of material between the one longitudinally extending side edge of the web of material and the opposite longitudinally extending side edge of the web of material. The second transverse fold line is positioned at one longitudinal end of the web of material and defines a top sealing area at which the web of material is sealed when the packaging material is folded and sealed to form the top portion of the gable-top package, and the first transverse fold line is spaced from the second transverse fold line in a direction toward an opposite longitudinal end of the web of material. A plurality of longitudinal fold lines extends longitudinally away from the first transverse fold line toward the opposite longitudinal end of the web of material, with adjacent pairs of the longitudinal fold lines defining respective walls of the gable-top package when the packaging material is folded and sealed. A pair of oblique fold lines each extend obliquely from the first transverse fold line to the second transverse fold line such that a trapezoidal area is bounded by the pair of oblique lines, by a portion of the second transverse fold line extending between the pair of oblique fold lines and by a portion of the first transverse fold line extending between the pair of oblique fold lines, and a plurality of additional fold lines are located within the trapezoidal area and form an isosceles triangle within the trapezoidal area, wherein the isosceles triangle encloses a plurality of further fold lines forming a part of the crease pattern, and the further fold lines forming three, and only three, triangular panels within the isosceles triangle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: 
           [0018]      FIG. 1  shows a side view of a folding unit comprising a folding assembly in accordance with the present invention; 
           [0019]      FIGS. 2 and 3  show views in perspective of various component parts of the  FIG. 1  folding assembly; 
           [0020]      FIGS. 4 and 5  show a further component part of the  FIG. 1  folding assembly in two different operating configurations; 
           [0021]      FIG. 6  shows a further component part of the  FIG. 2-5  folding assembly, as it interacts with a pillow pack during formation of the gable portion; 
           [0022]      FIG. 7  shows a package produced by the  FIG. 1  unit; 
           [0023]      FIG. 8  shows a web of packaging material having a number of fold lines (crease pattern). 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    Number  1  in  FIG. 1  indicates as a whole a folding unit of a packaging machine (not shown) for continuously producing sealed gable-top packages  2  ( FIG. 7 ) of a pourable food product, such as pasteurized or UHT milk, fruit juice, wine, etc., from a known tube (not shown) of packaging material. 
         [0025]    The tube is formed in known manner upstream from unit  1  by longitudinally folding and sealing a web of heat-seal sheet material. 
         [0026]    The packaging material has a multilayer structure substantially comprising a base layer for stiffness and strength, which may comprise a layer of fibrous material, e.g. paper, or mineral-filled polypropylene material; and a number of layers of heat-seal plastic material, e.g. polyethylene film, covering both sides of the base layer. 
         [0027]    In the case of aseptic packages  2  for long-storage products, such as UHT milk, the packaging material also comprises a layer of gas- and light-barrier material, e.g. aluminium foil or ethyl vinyl alcohol (EVOH) film, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of package  2  eventually contacting the food product. 
         [0028]    With particular reference to  FIG. 8 , the web of packaging material comprises a crease pattern  10 , i.e. a number of fold lines, along which the material is folded, during the folding operation, to form a pillow pack  3  first, and then package  2 . 
         [0029]    Crease pattern  10  comprises four transverse fold lines  11 ,  12 ,  13 ,  14 . Lines  11 ,  12  are located close to the ends of the packaging material, and define respective top and bottom sealing areas  11   a ,  12   a.    
         [0030]    Crease pattern  10  comprises, in known manner, four longitudinal fold lines  15 ,  16 ,  17 ,  18  extending between transverse fold lines  13 ,  14 . 
         [0031]    Crease pattern  10  also comprises a number of further fold lines  20  located in the area between line  14  and sealing area  12   a , and which form lateral flaps (not shown) which are subsequently folded to form a bottom wall  62  of package  2 . 
         [0032]    The pattern of fold lines  20  is known and therefore not described in detail. 
         [0033]    Lines  15 ,  18  are located close to lateral edges  19  of the packaging material, and lines  16 ,  17  are interposed between lines  15  and  18 . 
         [0034]    Crease pattern  10  also comprises a number of additional fold lines in the area between lines  11  and  13 . 
         [0035]    The additional lines comprise two fold lines  22 ,  23  extending obliquely between lines  11 ,  13  and converging from line  11  to line  13 ; and two fold lines  24 ,  25  extending between lines  11 ,  13  and converging from line  13  to line  11 . 
         [0036]    Lines  22 ,  23 ,  24 ,  25  originate at respective intersection points  15   a ,  18   a ,  16   a ,  17   a  of respective lines  15 ,  18 ,  16 ,  17  and line  13 , and, in the embodiment shown, slope slightly in the longitudinal direction. 
         [0037]    Lines  22  and  24 , the portion of line  13  between points  15   a  and  16   a , and the portion of line  11  between the intersection point of lines  11  and  24  and an intersection point  11   e  of lines  22  and  11 , define an area  26 . Similarly, lines  23  and  25 , the portion of line  13  between points  17   a  and  18   a , and the portion of line  11  between an intersection point  11   f  of lines  11  and  23  and the intersection point of lines  11  and  25 , define an area  27 . 
         [0038]    Lines  24  and  25 , the portion of line  11  between the intersection points of lines  24 ,  25  and line  11 , and the portion of line  13  between points  16   a  and  17   a , define a panel A interposed between areas  26  and  27  and in the form of an isosceles trapezium with the oblique sides converging from line  13  to line  11 . 
         [0039]    Lines  22  and  23 , the portion of line  11  extending between points  11   e  and  11   f , on the opposite side to panel A, and the portion of line  13  extending between points  15   a  and  18   a , on the opposite side to panel A, define a panel B interposed between areas  26  and  27  and in the form of an isosceles trapezium with the oblique sides converging from line  13  to line  11 . 
         [0040]    Crease pattern  10  comprises, in area  26 , two fold lines  30 ,  31  originating respectively at points  15   a ,  16   a  and joined at a point  11   b  along line  11  to define an isosceles triangle with the portion of line  13  extending between points  15   a  and  16   a . Similarly, crease pattern  10  comprises, in area  27 , a further two fold lines  32 ,  33  originating respectively at points  17   a  and  18   a  and joined at a point  11   c  along line  11  to define an isosceles triangle with the portion of line  13  extending between points  17   a  and  18   a.    
         [0041]    Lines  31 ,  24  and the portion of line  11  extending between point  11   b  and the intersection point of lines  24  and  11 , define the outer boundaries of a triangular panel C adjacent to panel A. And, similarly, lines  32 ,  25  and the portion of line  11  extending between point  11   c  and the intersection point of lines  25  and  11 , define the outer boundaries of a triangular panel D adjacent to panel A and on the opposite side to panel C. 
         [0042]    Crease pattern  10  comprises three lines  34 ,  35 ,  36  in area  26 , and three lines  37 ,  38 ,  39  in area  27 ; lines  34 ,  35 ,  36  extend respectively from points  15   a ,  16   a ,  11   b  to a point  45  within the isosceles triangle in area  26 ; and lines  37 ,  38 ,  39  extend respectively from points  17   a ,  18   a ,  11   c  to a point  46  within the isosceles triangle in area  27 . 
         [0043]    Lines  34 ,  35  extend symmetrically on opposite sides of an extension of line  36 ; and lines  37 ,  38  extend symmetrically on opposite sides of an extension of line  39 . 
         [0044]    There are therefore defined, in area  26 , a panel E in the form of an isosceles triangle and bounded by lines  34 ,  35  and the portion of line  13  extending between points  15   a ,  16   a ; a triangular panel F bounded by lines  30 ,  34 ,  36 ; and a triangular panel G bounded by lines  31 ,  35 ,  36 . 
         [0045]    Similarly, there are defined, in area  27 , a panel H in the form of an isosceles triangle and bounded by lines  37 ,  38  and the portion of line  13  extending between points  17   a ,  18   a ; a triangular panel L bounded by lines  32 ,  37 ,  39 ; and a triangular panel M bounded by lines  33 ,  39 ,  38 . 
         [0046]    Crease pattern  10  also comprises, in area  26 , a line  40  extending between intersection point  11   e  of lines  11  and  22 , and a point  47  located substantially at the mid-point of line  30 . And, in the same way, crease pattern  10  comprises, in area  27 , a line  41  extending between the intersection point  11   f  of lines  11  and  23 , and a point  48  located substantially at the mid-point of line  33 . 
         [0047]    There are therefore defined, in area  26 , a triangular panel N bounded by lines  22 ,  40  and the portion of line  30  extending between points  15   a  and  47 ; and a triangular panel O bounded by line  40 , the portion of line  11  extending between points  11   e  and  11   b , and the portion of line  30  extending between points  11   b  and  47 . 
         [0048]    Similarly, there are defined, in area  27 , a triangular panel Q bounded by lines  23 ,  41  and the portion of line  33  extending between points  18   a  and  48 ; and a triangular panel P bounded by line  41 , the portion of line  33  extending between points  11   c  and  48 , and the portion of line  11  extending between points  11   c  and  11   f.    
         [0049]    Once formed, the tube of packaging material is filled with the food product for packaging, and is sealed and cut along equally spaced cross sections to form a number of pillow packs  3  (shown in  FIG. 1 ). 
         [0050]      FIG. 6  shows a partial view of pack  3  at the start of forming a gable portion  61  ( FIG. 7 ) of corresponding package  2 . 
         [0051]    More specifically, packs  3  extend along an axis R, and each comprise in known manner a parallelepiped-shaped main portion  49 , and opposite end portions  50   a ,  50   b  (only one shown in  FIG. 6 ) tapering from portion  49  towards respective transverse sealing strips  53  of pack  3 . 
         [0052]    Portion  49  corresponds to the area of the web extending between lines  13  and  14 . More specifically, said area is folded along lines  15 ,  16 ,  17  and  18  to form two parallel walls  49   a  (only one shown in  FIG. 6 ), and two parallel walls  49   b  (only one shown in  FIG. 6 ) perpendicular to walls  49   a.    
         [0053]    Walls  49   a  correspond to the areas between lines  16  and  17  and between lines  15  and  18 ; and walls  49   b  correspond to the areas between lines  15  and  16  and between lines  17  and  18 . 
         [0054]    Portions  50   a ,  50   b  correspond to the areas of the web extending between lines  11  and  13  and between lines  12  and  14  respectively; and strips  53  correspond to areas  11   a ,  12   a  of the web of packaging material. 
         [0055]    Each portion  50   a ,  50   b  is defined by a respective pair of walls  51   a ,  51   b , which are substantially in the form of an isosceles trapezium, slope slightly towards each other with respect to a plane perpendicular to the longitudinal axis R of pack  3 , and have major edges defined by respective end edges of opposite walls  49   a , and minor edges joined to each other by relative strip  53 . 
         [0056]    More specifically, walls  51   a ,  51   b  of portion  50   a  correspond respectively to panels A, B of the web of packaging material. 
         [0057]    Each pack  3  comprises, on wall  51   a , two substantially triangular portions  52   a  projecting laterally on opposite sides of wall  51   a  and defined by end portions of wall  51   a.    
         [0058]    Similarly, each pack  3  comprises, on wall  51   b  of portion  50   a , two substantially triangular portions  52   b  projecting laterally on opposite sides of wall  51   b  and defined by end portions of wall  51   b.    
         [0059]    Portions  52   a  of wall  51   a  correspond respectively to panels C and D, and portions  52   b  of wall  51   b  correspond respectively to panels N, O and Q, P of the web of packaging material. 
         [0060]    Each portion  52   a  of wall  51   a  is connected to a corresponding portion  52   b  of wall  51   b  by a respective lateral face  55 . Each face  55  comprises a respective surface  56  in the form of an isosceles triangle and extending upwards from respective wall  49   b ; and a respective pair of triangular surfaces  57 ,  58  having a first side in common. Each surface  57 ,  58  also has a second side in common with surface  56 , and a third side in common with a relative portion  52   a ,  52   b.    
         [0061]    Faces  55  correspond respectively to the isosceles triangle defined by points  11   b ,  16   a ,  15   a  of the packaging material, and to the isosceles triangle defined by points  17   a ,  18   a ,  11   c.    
         [0062]    Surfaces  56  correspond respectively to panels E, H of the web of packaging material; surfaces  57  and  58  of a first face  55  correspond respectively to panels G, F of the web of packaging material; and surfaces  57 ,  58  of a second face  55  correspond respectively to panels L, M. 
         [0063]    Packs  3  are then sent to unit  1 , where they are folded mechanically to form respective packages  2 . 
         [0064]    With particular reference to  FIG. 7 , packages  2  each substantially comprise a parallelepiped-shaped main portion  60  corresponding to portion  49  of pack  3 ; and gable portion  61 , which defines the top of portion  60  and is formed by folding portion  50   a  of pack  3  on unit  1 , as described in detail below. 
         [0065]    Package  2  also comprises bottom wall  62  defining the bottom of portion  60  and formed by folding portion  50   b  of pack  3  on unit  1  in a manner not described, by not being essential to a clear understanding of the present invention; two parallel walls  63 ,  64 ; and two parallel walls  65 ,  66  extending perpendicularly between walls  63 ,  64  of package  2 . 
         [0066]    More specifically, walls  63 ,  64 ,  65 ,  66  extend perpendicularly to the plane of wall  62 . 
         [0067]    Walls  63  and  64  correspond respectively to the areas of the web extending between lines  16  and  17  and between lines  15  and  18 ; and walls  65  and  66  correspond respectively to the areas of the web extending between lines  15  and  16  and between lines  17  and  18 . 
         [0068]    Portion  61  comprises a wall  67  having an opening device  68 ; and a wall  69  joined to wall  68  at top sealing strip  53 . 
         [0069]    More specifically, walls  67  and  69  are each in the form of an isosceles trapezium, slope with respect to walls  63 ,  64 ,  65  and  66 , converge towards top strip  53 , extend at their respective major bases from respective walls  63  and  64 , and are joined at their respective minor bases adjacent to top strip  53 . 
         [0070]    Walls  67  and  69  correspond respectively to panels A and B of the web of packaging material. 
         [0071]    Portion  61  also comprises two lateral flaps  70 ,  71  folded outside the volume of package  2  available for the food product, and extending along extensions of, and obliquely with respect to, respective walls  65 ,  66 . 
         [0072]    More specifically, each flap  70 ,  71  is triangular and defined by a respective oblique side of wall  67 , by a relative end  53   a ,  53   b  of strip  53  folded onto a relative oblique side of wall  69 , and by a relative edge  72  parallel, when folded, to relative wall  65 ,  66 . 
         [0073]    More specifically, flaps  70 ,  71  correspond respectively to panels D, C of the web of packaging material, and are folded to superimpose lines  32 ,  31  on respective lines  23 ,  22 . 
         [0074]    With particular reference to  FIG. 1 , unit  1  comprises a station  80  supplied with pillow packs  3  and for folding portion  50   a  to form portion  61  of each package  2 ; a station  81  supplied with packs  3  complete with respective portions  61 , and for forming wall  62  of package  2  corresponding to each said pack  3 ; and a transfer carriage  82  for transferring pack  3 , complete with portion  61 , from station  80  to station  81 . 
         [0075]    In a manner not shown, station  81  also heats portion  61  and wall  62 , seals flaps  70 ,  71  to the oblique sides of wall  69 , and seals wall  62  to portion  60  to form the complete package  2 . 
         [0076]    Carriage  82  moves back and forth between stations  80  and  81 , and performs a forward movement to transfer pack  3 , complete with portion  61 , from station  80  to station  81 , and a return movement in which it is empty. 
         [0077]    Station  81  is not described in detail, by not being essential to a clear understanding of the present invention. 
         [0078]    More specifically, each station  80 ,  81  comprises a respective hub  84 ,  85  powered by a respective motor not shown; and a respective number of conveying devices  86 —four in the example shown—angularly integral with relative hub  84 ,  85 . 
         [0079]    Station  80  also comprises a folding assembly  90  which interacts with portion  50   a  of each pack  3  to form portion  61  of a corresponding package  2 . 
         [0080]    More specifically, devices  86  are fixed, equally spaced angularly, to relative hub  84 ,  85 , and each comprise a groove  87  facing relative hub  84 ,  85  and which engages strip  53  of relative portion  50   b ,  50   a ; and two paddles  88  which cooperate respectively with walls  49   a  of pack  3  corresponding to walls  63 ,  64  of package  2 . 
         [0081]    Each device  86  at station  80  receives a pack  3  in a first angular position, in which pack  3  is inclined slightly with respect to a horizontal plane; feeds it clockwise along a roughly ninety-degree arc to a second angular position, in which assembly  90  folds portion  50   a  to form portion  61 ; and then feeds pack  3 , complete with portion  61 , along a further roughly ninety-degree clockwise arc to a third angular position, where pack  3 , complete with portion  61 , is picked up by carriage  82  and transferred to station  81 . 
         [0082]    Each paddle  88  comprises, on its outer end, an edge  89  bent towards the other paddle  88  of the same device  86  to prevent pack  3  from spinning off as hubs  84 ,  85  rotate. 
         [0083]    Along the arc between the first and third angular position, devices  86  are set to a closed configuration in which paddles  88  cooperate with walls  49   a  of pack  3 . 
         [0084]    In the first and third angular position, on the other hand, devices  86  are set to an open configuration in which paddles  88  are parted to supply station  80  with pack  3  with relative portions  50   a ,  50   b  to be folded, and, respectively, to supply carriage  82  with pack  3  complete with portion  61 . 
         [0085]    Assembly  90  advantageously interacts, on opposite sides of axis R of each pack  3 , with portions  52   a ,  52   b  of pack  3 , to fold each portion  52   b  onto relative surface  56 , and each portion  52   a  onto relative portion  52   b  to form a relative flap  70 ,  71  of package  2 . 
         [0086]    With reference to  FIGS. 2 to 5 , assembly  90  comprises two tools  91 ,  92  for folding each portion  52   b  onto relative surface  56 , and each portion  52   a  onto relative portion  52   b  respectively. More specifically, each portion  52   b  is folded onto relative surface  56  after first being folded onto relative line  40 ,  41 . 
         [0087]    Tools  91 ,  92  are hinged to respective output members of respective motors  105  about respective axes T parallel to the axes of rotation of hubs  84 ,  85 , and are hinged to each other about a common axis S parallel to axes T. 
         [0088]    More specifically, tool  91  comprises a supporting surface  100  and two folding surfaces  101 , which cooperate respectively with wall  51   b  to control the volume of portion  61  being formed, and with portions  52   b  to fold them onto relative surfaces  56 . 
         [0089]    Surfaces  100  and  101  are moved integrally with one another in an approach movement into contact with wall  51   b  and portions  52   b  respectively, and are moved with respect to one another in a folding movement in which surfaces  101  fold portions  52   b  onto relative surfaces  56 . 
         [0090]    More specifically, tool  91  comprises a frame  95  fitted, on one side, with projecting surface  100 , and connected operatively, on the opposite side, to surfaces  101 ; two first levers  93  hinged to frame  95  and to the output member of relative motor  105 ; and a second lever  94  hinged to tool  92  and to frame  95 . 
         [0091]    Frame  95  comprises a first member  96  fitted on one end, and on the opposite side to axis S, with projecting surface  100 ; and a second member  97  which slides with respect to member  96  and is hinged to levers  93  about an axis U parallel to axis S. 
         [0092]    Levers  93  are hinged, at one end, to the output member of motor  105  about axis T, and are hinged, at the opposite end, to frame  95  about axis U. 
         [0093]    Lever  94  is hinged, at one end, to tool  92  about axis S, and is hinged, at the opposite end, to frame  95  about an axis V parallel to axis S. 
         [0094]    Tool  91  also comprises two third levers  99 , each of which is hinged, at one end, to relative lever  93  about axis U, and is connected operatively and movably, at the opposite end, to surface  100  and to a respective surface  101  by means of a respective connecting rod  102 . 
         [0095]    More specifically, each connecting rod  102  is L-shaped, is hinged at opposite ends to surface  100  and to a plate  107  integral with relative surface  101 , and comprises an intermediate portion, between surface  100  and relative plate  107 , which is housed inside a circular through seat formed on the end of relative lever  99  opposite axis U. 
         [0096]    Members  96  and  97  are connected elastically to each other by a spring  98 , which is compressed during the folding movement of surfaces  101 , and expands when surface  100  withdraws from wall  51   b.    
         [0097]    Tool  92  is similar to tool  91 , and is only described insofar as it differs from tool  91 , using the same reference numbers for identical or corresponding parts of tools  91 ,  92 . 
         [0098]    Tool  92  differs from tool  91  by relative surface  100  cooperating with wall  51   a  at the end of the relative approach movement. 
         [0099]    Surfaces  101  are the same triangular shape as portions  52   a , and fold portions  52   a  onto portions  52   b , once surface  100  cooperates with wall  51   a.    
         [0100]    Tool  92  also comprises two levers  94  spaced apart and which are hinged to lever  94  of tool  91  about axis S. 
         [0101]    Folding assembly  90  also comprises two pressure members  110  ( FIGS. 1 and 6 ), each of which exerts pressure on a relative surface  56 , when forming relative flap  70 ,  71 , to facilitate folding of portions  52   a ,  52   b.    
         [0102]    More specifically, pressure members  110  are fitted to an actuating assembly  111  connected operatively to motor  105  of tool  91  in known manner not shown. 
         [0103]    Assembly  111  (shown only partly in  FIG. 6 ) comprises two plates  112 , which cooperate with respective walls  49   b  of pack  3 , and from which respective pressure members  110  project; and two lever mechanisms  115  connected to motor  105  of tool  91  by a cam mechanism not shown. 
         [0104]    Motor  105  and lever mechanisms  115  are so connected that, when surface  100  of tool  91  cooperates with wall  51   b , members  110  cooperate with relative surfaces  56 , and, when surface  100  of tool  91  is detached from wall  51   b , members  110  are detached from relative surfaces  56 . 
         [0105]    More specifically, pressure members  110  are preferably made of deformable plastic material, and are tooth-shaped. More specifically, each pressure member  110  comprises a flat surface  113  which cooperates with relative surface  56 ; and a surface  114 , opposite surface  113 , which tapers from relative plate  112  and cooperates with relative surfaces  57 ,  58  once portions  52   a ,  52   b  are folded. 
         [0106]    Operation of assembly  90  will now be described with reference to one pack  3 , and as of a start instant in which pack  3  is supplied to station  80  of unit  1 . 
         [0107]    More specifically, inside a relative device  86  in the first angular position, pack  3 , positioned with axis R sloping slightly with respect to a horizontal plane, is housed with strip  53  inside groove  87 , and with walls  49   a  gripped by paddles  88 . 
         [0108]    Rotation of hub  84  moves device  86  into the second angular position, in which pack  3  is adjacent to assembly  90 . 
         [0109]    As hub  84  rotates, edges  89  prevent pack  3  from being spun off. 
         [0110]    In the second angular position of device  86 , motor  105  of tool  91 , by means of the cam mechanism and lever mechanisms  115 , moves each plate  112  onto relative wall  49   b  of pack  3 , and surface  113  of each pressure member  110  onto relative surface  56 . 
         [0111]    Next, motors  105  operate tools  91 ,  92  to perform the respective approach movements of respective surfaces  100 . 
         [0112]    More specifically, surface  100  of tool  91  contacts wall  51   b  of pack  3  before surface  100  of tool  92  contacts wall  51   a  of pack  3 . 
         [0113]    Next, motor  105  of tool  91  is operated further to perform the respective folding movements of surfaces  101  of tool  91 , and so fold portions  52   b  onto relative surfaces  56 . 
         [0114]    More specifically, portions  52   b  are folded with respect to wall  51   b  at respective lines  22 ,  23 , and are folded over along respective lines  40 ,  41  to superimpose respective panels N, Q on respective portions of respective panels E, H. 
         [0115]    At this point, motor  105  of tool  92  is operated to perform the respective folding movements of surfaces  101  of tool  92 , and so fold portions  52   a  onto respective portions  52   b.    
         [0116]    More specifically, portions  52   a  are folded with respect to wall  51   a  at respective lines  24 ,  25 . 
         [0117]    By the end of the folding movements, panels D, C are superimposed respectively on panels P, O, which in turn are superimposed respectively on panels Q, N, which are superimposed respectively on panels H, E. 
         [0118]    Once folded, panels D, C define respective flaps  70 ,  71 , and have respective lines  32 ,  31  superimposed on respective lines  23 ,  22 . 
         [0119]    More specifically, the approach movements commence from a start position in which each member  97  rests against relative member  96  ( FIGS. 2 and 3 ). 
         [0120]    During the approach movements, motors  105 , by means of levers  93 , rotate surfaces  100 ,  101  of tools  91 ,  92 , integrally with one another, about axes U until surfaces  100  come to rest against walls  51   a ,  51   b  of pack  3 . During the approach movements, members  96 ,  97  of frames  95  also move integrally with one another. 
         [0121]    Once the approach movements are completed, motors  105 , by means of levers  93 , rotate levers  99  and members  97  of tools  91 ,  92  further with respect to relative axes U, T, thus compressing springs  98  of tools  91 ,  92 . 
         [0122]    Rotation of levers  99  rotates connecting rods  102  of tools  91 ,  92  with respect to relative surfaces  100 , and so, by means of plates  107 , rotates the pairs of surfaces  101  with respect to relative surfaces  100 . 
         [0123]    By the end of the folding movements, ends  53   a ,  53   b  are detached slightly from the oblique sides of wall  69 , and faces  55  are detached slightly from surfaces  56  to permit heating and sealing at station  81 . 
         [0124]    Once the folding movements are completed, motors  105  are operated in reverse to first withdraw members  110  from surfaces  56 , then surfaces  101  from flaps  70 ,  71 , and finally surfaces  100  from walls  67 ,  69 . 
         [0125]    In the course of the above withdrawal movements, the previously compressed springs  98  expand to restore relative members  97  to the position resting against relative members  96 . 
         [0126]    At this point, pack  3 , complete with portion  61 , is moved by hub  84 , by means of device  86 , a further ninety degrees clockwise into the third angular position, where it is picked up by carriage  82  and transferred to station  81 . 
         [0127]    At station  81 , in known manner not described, by not being essential to a clear understanding of the present invention, wall  62  is formed; ends  53   a ,  53   b  are first heated and then sealed to the oblique sides of wall  69 ; and faces  55  are first heated and then sealed to wall  69 . 
         [0128]    The advantages of assembly  90  and the method according to the present invention will be clear from the foregoing description. 
         [0129]    In particular, assembly  90  provides for fast formation of portion  61 , by operating simultaneously on opposite sides of pack  3 . 
         [0130]    Moreover, formation of portion  61  by assembly  90  is highly repeatable, on account of members  110  being controlled by motor  105  of tool  91  by means of the cam mechanism. 
         [0131]    Finally, assembly  90  provides for a high-quality surface finish of portion  61  by forming portion  61  by successively folding panels of the web of packaging material along relative fold lines. As opposed to being deformed, the panels are therefore simply folded along the fold lines, thus preventing any impairment in the finish of walls  67 ,  69  and flaps  70 ,  71 . 
         [0132]    Clearly, changes may be made to assembly  90  and the method as described herein without, however, departing from the protective scope defined in the accompanying Claims.