Abstract:
A folding unit for producing packages of pourable food products from sealed packs comprises a movable conveying member and a folding device arranged for folding at least one end portion of the packs, whilst the packs are conveyed by the conveying member, to obtain the packages, the conveying member carrying a plurality of plates, each plate being configured to receive a pack and to deliver a package to a transferring and up-ending unit arranged downstream of the folding unit, the folding unit further comprising a retention device arranged for keeping said packages on the plates.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a folding unit for packaging machines for continuously producing sealed packages of pourable food products from a tube of packaging material. 
       BACKGROUND OF INVENTION 
       [0002]    As is known, many food products, such as fruit juice, pasteurized or UHT (ultra-high-temperature treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material. 
         [0003]    A typical example of this type of package is the parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is made by folding and sealing laminated strip packaging material. 
         [0004]    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 of 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. 
         [0005]    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), 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. 
         [0006]    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; the web of packaging material is sterilized on the packaging machine, e.g. by applying a chemical sterilizing agent, such as a hydrogen peroxide solution, which, once sterilization is completed, is removed from the surfaces of the packaging material, e.g. evaporated by heating; and the web of packaging material so sterilized is maintained in a closed, sterile environment, and is folded and sealed longitudinally to form a vertical tube. 
         [0007]    The tube is filled continuously downwards with the sterilized or sterile-processed food product, and is sealed and then cut along equally spaced cross sections to form pillow packs, which are then fed to a folding unit to form the finished packages, e.g. substantially parallelepiped-shaped packages. 
         [0008]    More specifically, the pillow packs substantially comprise a parallelepiped-shaped main portion; and opposite top and bottom end portions projecting laterally on opposite sides of the main portion and defining respective triangular end flaps to be folded onto the main portion. 
         [0009]    A longitudinal sealing strip, formed when sealing the packaging material to form the vertical tube, extends along the pillow packs; and the end portions of each pillow pack have respective transverse sealing seams perpendicular to the relative longitudinal sealing strip and defining respective end tabs projecting from the top and bottom of the pack. 
         [0010]    The end portions of each pillow pack taper towards the main portion from the respective end tabs, and are pressed towards each other by the folding unit to form flat opposite end walls of the pack, while at the same time folding the end flaps onto respective walls of the main portion. 
         [0011]    Packaging machines of the above type are known which comprises;
       a folding unit where pillow packs are turned into folded packages by folding means; and   a transferring and up-ending unit for tipping the folded packages.       
 
         [0014]    The folding unit substantially comprises:
       a chain conveyor feeding the pillow packs along a forming path from a supply station to an output station;   a fixed elongated guide member, which is positioned facing and at a distance from the chain conveyor and cooperates cyclically with each pillow pack to flatten a first end portion of the pillow pack and so fold respective tab onto such first end portion; and   folding elements cooperating cyclically with each pillow pack to flatten a second end portion of the pillow pack and so fold respective tab onto such second end portion.       
 
         [0018]    The transferring and up-ending unit is arranged downstream from the folding unit. 
         [0019]    The transferring and up-ending unit transfers the packages successively along a conveying path from an in-feed station to an out-feed station, and simultaneously up-ends the packages from an in-feed position, in which the packages are positioned with their axis tilted to the horizontal, into an out-feed position, in which the packages are positioned with their axis substantially vertical. 
         [0020]    The transferring and up-ending unit receives the packages at the in-feed station from the chain conveyor of the folding unit, and feeds them to a further conveyor at the out-feed station. 
         [0021]    More specifically, the chain conveyor supplies the unit with packages in the in-feed position, and the further conveyor withdraws the packages from the unit in the out-feed position. 
         [0022]    The transferring and up-ending unit substantially comprises a rotary member having a number of push arms which cooperate with respective packages to remove the packages from the folding unit and push the packages along the conveying path. The transferring and up-ending unit further comprises a fixed guide extending substantially along the conveying path and cooperating with the packages to ease them from the tilted in-feed position to the out-feed position. 
         [0023]    More specifically, the conveying path along which the packages are fed is substantially in the form of an arc of circumference, at the end of which, the packages are fed to the further conveyor. 
         [0024]    A drawback of the known packaging machines is that it may be difficult to control the transfer of the packages from the folding unit to the transferring and up-ending unit, especially at high output rates of the packaging machines, i.e. when the packages are advanced at high speed. 
         [0025]    If the packages carried by the chain conveyor of the folding unit are not in the right position when the push arms of the transferring and up-ending unit interact with them, the push arms are not able to remove the packages from the folding unit in the proper way. In this case, package jams may occur that lead to packaging machine stops, and so to a reduction of the packaging machine efficiency. 
       DISCLOSURE OF INVENTION 
       [0026]    An object of the invention is to improve the known packaging machines. 
         [0027]    Another object of the invention is to improve the way in which packages are transferred from the folding unit to the transferring and up-ending unit in a packaging machine. 
         [0028]    A further object of the invention is to provide a folding unit for a packaging machine which allows the position of the packages to be properly controlled, before and during transferring of the packages to the transferring and up-ending unit. 
         [0029]    According to the invention, there is provided a folding unit for producing packages of pourable food products from sealed packs, comprising a movable conveying member and folding means arranged for folding at least one end portion of said packs, whilst said packs are advanced by said conveying member, to obtain said packages, said conveying member carrying a plurality of plates, each plate being configured to receive a pack and to deliver a package to a transferring and up-ending unit arranged downstream of the folding unit, characterized in that the folding unit further comprises retention means arranged for keeping said packages on said plates. 
         [0030]    Owing to the inventions, the packages are prevented from falling down from the plates before, and during, transferring from the folding unit to the transferring and up-ending unit. The packages, even in case the folding unit is driven at a very high production speed, i.e. at high output rate of the packaging machine, are prevented from sliding downwards along the plates and causing jams in the region interposed between the folding unit and the transferring and up-ending unit. 
         [0031]    In addition, since the packages are kept on the plates and therefore do not fall down from the plates by gravity, the transferring and up-ending unit may be arranged in a lower position with respect to the folding unit, when compared with the known packaging machines. In this case, the packages are removed from the folding unit by the push arms of the transferring and up-ending unit when such packages have their axes in a position closer to the vertical direction if compared to the known filling machines. This allows having a better control during the transferring and up-ending phase. The packages, in fact, have to undergo a limited tilting, in order to be tipped from the withdrawal position, in which they are released from the folding unit, to the final position, in which their axes are arranged along a vertical direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: 
           [0033]      FIG. 1  shows a partial perspective view, with parts removed for clarity, of a folding unit in accordance with the present invention for producing packages of pourable food products from sealed pillow packs and of a transferring and up-ending unit; 
           [0034]      FIG. 2  shows a partial side view of the folding unit and of the transferring and up-ending unit of  FIG. 1 , with parts removed for clarity; 
           [0035]      FIG. 3  shows a larger-scale detail of a plate of the folding unit provided with a retention element; and 
           [0036]      FIG. 4  shows side view of the folding unit and of the transferring and up-ending unit of  FIG. 1 , with parts removed for clarity. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0037]    Number  1  in  FIG. 1  indicates as a whole a folding unit of a packaging machine (not shown) for continuously producing parallelepiped-shaped sealed packages  2  of a pourable food product, such as pasteurized or UHT milk, fruit juice, wine, etc., from a known tube of packaging material (not shown). 
         [0038]    The tube is formed in known manner upstream from unit  1  by longitudinally folding and sealing a known web (not shown) of heat-seal sheet material, which comprises a layer of paper material covered on both sides with layers of heat-seal plastic material, e.g. polyethylene. In the case of an aseptic package  2  for long-storage products, such as UHT milk, the packaging material comprises a layer of oxygen-barrier material, e.g. aluminium foil, which is superimposed on one or more layers of heat-seal plastic material eventually forming the inner face of the package contacting the food product. 
         [0039]    The tube of packaging material is then 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  ( FIG. 4 ), which are then transferred to unit  1  where they are folded mechanically to form respective packages  2 . 
         [0040]    With reference to  FIGS. 1 ,  2  and  4 , unit  1  substantially comprises a conveyor  20  for feeding packs  3  continuously along a predominantly straight horizontal forming path B from a supply station  21  to an output station  22  (both shown only schematically) and folding means for folding packs  3 , in particular at least one end portion of packs  3 , whilst packs  3  are carried by the conveyor  20 , to obtain packages  2 . The folding means are known from prior art and, therefore, they are not shown and disclosed in detail. For example, the folding means may comprise a fixed elongated guide member and folding elements as explained above. 
         [0041]    Conveyor  20  comprises at least one gear and, in the example shown, a drive gear  25  and a driven gear  26 ; and an articulated chain  27  looped about and meshing with gears  25 ,  26 , and supporting a number of plates  28 , for example flat rectangular plates, each of which projects from chain  27  and cooperates with and pushes a pack  3  to feed it along path B. 
         [0042]    Chain  27  comprises a straight horizontal top branch  30 ; a bottom branch  31  substantially parallel to branch  30 ; and two curved C-shaped portions  32 ,  33 , which are positioned with their concavities facing, connect branches  30  and  31 , and the middle portions of which define supply station  21  and output station  22  respectively. 
         [0043]    Path B comprises a straight main portion B 1  defined by branch  30  of chain  27 ; and two, respectively supply and output, curved end portions B 2 , B 3  defined by respective top portions  32   a ,  33   a  of portions  32 ,  33  of chain  27  extending between corresponding stations  21 ,  22  and branch  30 . Branch  30  and portions  32   a ,  33   a  of portions  32 ,  33  therefore define a conveying portion of chain  27  to convey packs  3  from station  21  to station  22 , while branch and the remaining portions of portions  32 ,  33  define a return portion of chain  27  to feed plates  28  from station  22  to station  21 . 
         [0044]    Chain  27  comprises a number of articulated links  35  defined by substantially flat rectangular bodies, from which respective plates  28  project perpendicularly. 
         [0045]    Given the structure of conveyor  20 , plates  28  are positioned vertically along portion B 1  of path B. 
         [0046]    At supply station  21 , each pack  3  is fed onto conveyor  20  in a feed direction C, coaxial with an axis A of pack  3 . 
         [0047]    Number  100  in  FIGS. 1 and 2  indicates as a whole a transferring and up-ending unit for tipping the packages  2 . 
         [0048]    Transferring and up-ending unit  100  is known and, therefore, it will be described only to the extent that is necessary for the understanding of the invention. 
         [0049]    Transferring and up-ending unit  100  feeds a succession of packages  2  continuously along a path P extending from an in-feed station  104  to an out-feed station  105 , and simultaneously up-ends packages  2  continuously from an in-feed position, in which they are positioned with axes A oriented in a direction K, into an out-feed position, in which they are positioned with respective axes A oriented in a direction L crosswise to direction K. With reference to the embodiment shown, direction K is sloped relative to a horizontal plane and direction L is vertical. 
         [0050]    Transferring and up-ending unit  100  receives packages  2  continuously and successively at in-feed station  104  from conveyor  20 , and feeds them, in the out-feed position, to an output conveyor  108  at out-feed station  105 . Output conveyor  108  moves the packages  2  along a substantially straight path R tangent to an end portion of path P. 
         [0051]    Transferring and up-ending unit  1  comprises a number of push arms  115  for removing respective packages  2  from conveyor  20  at in-feed station  104  and feeding them along path P to out-feed station  105 ; and a guide  117  which cooperates with packages  2  along path P to up-end them from the in-feed position to the out-feed position. 
         [0052]    Path P is arc-shaped about an axis E and extends along an angle of about 90° from in-feed station  104  to out-feed station  105 . 
         [0053]    Transferring and up-ending unit  100  also comprises:
       a drive shaft  111  rotating continuously about axis E and powered by an electric motor of the packaging machine in known manner not shown; and   a wheel  114  of axis E, fitted to shaft  111  rotatably about axis E, and supporting the push members  115 , which are hinged to wheel  114 .       
 
         [0056]    Push arms  115  rotates together with wheel  114  around axis E and oscillate with respect to wheel  114  between a first operating position, in which they remove the packages  2  from folding unit  1 , to a second operating position, in which—after delivering the packages  2  to the conveyor  108 —are received into slots  116 , obtained in the wheel  114 . 
         [0057]    Push arms  115  are provided at their ends opposite to the ends which interact with packages  2  with cam followers (not shown) that interact with a fixed cam (not shown), so that the fixed cam drives the push arms  115 . 
         [0058]    Guide  117  is curved, extends substantially along path P, on the outside of wheel  114 , and cooperates with packages  2  to ease them from the in-feed to the out-feed position. 
         [0059]    Furthermore, guide  117  defines a supporting and slide surface T for packages  2 , which extends substantially along path P and slopes gradually from a portion T 1 , parallel to direction B and adjacent to in-feed station  104 , to a substantially flat, vertical out-feed portion T 2  parallel to direction L and adjacent to out-feed station  105 . 
         [0060]    The folding unit  1  further comprises holding means, or retention means  40  arranged for keeping the packages  2  on the plates  28  before and during transferring of the packages  2  from the folding unit  1  to the transferring and up-ending unit  100 . 
         [0061]    Retention means  40  comprises a plurality of holding elements, or retention elements  41 , each associated with a corresponding plate  28 . Each retention element  41  is arranged at an end portion  52  of the corresponding plate  28  opposite to a further end portion  53  at which the plate  28  is connected to the conveyor  20 . Each retention element  41  comprises a body  42  arranged to be received into a seat  43  obtained in an end surface  44  of the plate  28 . The retention element  41  also comprises an appendix  45  arranged for cooperating with a package  2  carried by the plate  28 . The body  42  is provided with a recess  46  adapted for receiving a screw  47  that connects the retention element  41  to the plate  28 . The screw  47  is provided with an elongated threaded portion  48  that passes through an opening  49  obtained in the bottom portion of the recess  46  and mates with a corresponding threaded hole  50  obtained in the bottom portion of the seat  43 . 
         [0062]    When the retention element  41  is fixed to the corresponding plate  28  the body  42  is received into the seat  43  and the appendix  45  is substantially flush with the end surface  44  and projects from the plate  28  in a direction arranged transversally, in particular perpendicularly, with respect to a side surface  51  of the plate  28 . The side surface  51  is arranged to interact with a side wall  11  of package  2 . The appendix  45  is arranged to interact with an end wall  12  of the package  2 . In particular, in the embodiment show, since the packages carried by the conveyor  20  are arranged in an upside down configuration, the appendix  45  interacts with a bottom wall of the packages  2 . 
         [0063]    During operation, packs  3  are fed to conveyor  20  and—as conveyor  20  carries them along path P—the folding means fold packs  3 , in particular end portions thereof, so as to form packages  2 . 
         [0064]    When a package  2  reaches output station  22 , i.e. the region where the folding unit  1  cooperates with the transferring and up-ending unit  100 , a push arm  115  interacts with the package  2  in order to remove the package  2  from the corresponding plate  28 . 
         [0065]    Before and during the removal step, the retention element  41  prevents the package  2  from falling from plate  28  or sliding down along plate  28 , so that the position of the package  2 —at the point in time the push arm  115  contacts it—is uniquely set and constant for each plate  28 , and at every working cycle. At the same time, since the appendix  45  is arranged transversally, in particular substantially perpendicularly, with respect to the side surface  51 , the retention element  41  does not obstruct the removal of the package  2  from the plate  28  by means of the push arm  115 . 
         [0066]    Subsequently, the push arm  115  delivers the package  2  to the output conveyor  108 . 
         [0067]    Since the retention means  40  prevent the packages  2  from sliding downwards along the plates  28 , the transferring and up-ending unit  100  may be arranged in a lower position with respect to the folding unit  1  if compared with the known packaging machines. 
         [0068]    In this case, the angle formed by the direction K with a horizontal plane, i.e. the angle formed by the axes A of the packages  2  with a horizontal plane when the packages  2  are removed from the folding unit  1 , is greater than in the case of the known packaging machines. This allows a better handling of the packages  2  by the push arms  115 . The packages  2 , in fact, in order to reach the final position in which their axes A are arranged vertically must be turned, or tipped, to a lesser extent than in the known packaging machines. In other words, the packages  2  are removed from the folding unit  1  when they are in a withdrawal configuration closer to the final configuration, in which they are delivered to output conveyor  108 .