Abstract:
A folding unit for a cardboard packer is disclosed, which is adapted to close and seal a lid of a cardboard box. The folding unit comprises a conveyor for transporting the cardboard box to the folding unit, a transport device for moving the box and/or a folding device into contact with each other, and further also a catch that is arranged adjacent the conveyor for stopping the box at a folding position, wherein the folding unit further comprises a sensor for detecting when the catch has stopped a box, for activating the transport device such that the box can be final folded.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a unit for final folding a cardboard blank in a cardboard packer. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the following description, the term package is used in its widest sense to indicate any container for packaging liquid or pourable food products, and therefore includes not only packages made of multilayer sheet material and similar, to which reference is made hereinafter purely, by way of example, but also glass or plastic bottles, tins etc. 
         [0003]    As is known, many pourable food products, such as fruit juice, UHT (Ultra High Temperature treatment) milk, wine, tomato sauce, etc., are sold in packages made of sterilized sheet packaging material. 
         [0004]    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. The packaging material has a multilayer structure comprising a layer of base material, e.g. paper, covered on both sides with layers of heat-seal plastic material, e.g. polyethylene. In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of oxygen-barrier material e.g. aluminium foil, which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material eventually forming the inner face of the package contacting the food product. 
         [0005]    As is known, packages of this sort are produced on fully automatic packaging lines, on which a continuous tube is formed from the web-fed packaging material; the web of packaging material is sterilized, e.g. by applying a chemical sterilizing agent such as hydrogen peroxide solution, which is subsequently 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. 
         [0006]    The tube is filled with the sterilized or sterile-processed food product, and is sealed and subsequently cut along equally spaced cross sections to form pillow packs, which are folded mechanically to form respective finished, e.g. substantially parallelepiped-shaped, packages. 
         [0007]    If the packages are not folded at all, a pillow-shaped package with the trademark Tetra Fino is produced, and if only one end wall is folded, a package known by the trademark Tetra Wedge is produced. It is also possible to create tetrahedral-shaped packages, by transversally sealing the vertical Lube in alternating, orthogonal directions, producing packages with the Tetra Classic trademark. 
         [0008]    Alternatively, the packaging material may be cut into blanks, which are formed into packages on forming spindles, and the packages are filled with the food product and sealed. One example of this type of package is the so-called “gable-top” package known by the trademark Tetra Rex (registered trademark). 
         [0009]    In all of the above cases, the finished packages can be transported successively to a distribution unit, such as a cardboard packer, for protecting the packages during transport from the filling site to the point of sale of the packages. The cardboard packer typically comprises several units, such as an in-feed of blanks, a carton riser, where the blanks are formed to an open box, a pick-and-place station, where packages are taken from a conveyor and are placed inside the open box, and finally a final fold and out-feed of finished boxes. In this last station, the lid of the cardboard box is typically closed and the flaps of the lid are supplied with adhesive and are pressed against the sides of the box, effectively shutting the box in a secure way. The present invention relates to the final fold and out-feed station, and especially to the final fold unit. 
         [0010]    Various kinds of devices have been presented for final folding an open box, and feeding the boxes to the out-feed. Those devices normally involve a lot of motors and sensors, and are consequently costly. 
         [0011]    It is hence an object of the present invention to present a low-cost and robust solution, at least partly solving the above problems of the prior art. 
       SUMMARY OF THE INVENTION 
       [0012]    According to the present invention, there is provided a folding unit for final folding a cardboard box, as claimed in claim  1 . 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: 
           [0014]      FIG. 1  shows a side view of a final fold and out-feed station according to the invention, 
           [0015]      FIG. 2  shows an enlarged view of the final fold station of  FIG. 1 , 
           [0016]      FIG. 3  shows an enlarged view of a catch of the final fold station of the present invention, 
           [0017]      FIGS. 4 and 5  show an enlarged view of a flap presser of the present invention, in a deactivated and an operative position, 
           [0018]      FIG. 6  shows a simplified cross-section of conveyor and box lifting means according to the invention, and 
           [0019]      FIGS. 7   a - 7   d  show a side view of the final fold and out-feed station, in which a cardboard box is taken through the different steps in the final fold and out-feed station. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    A final fold and out-feed station of a cardboard packer is denoted in general with  1 , as can be seen in  FIG. 1 . This station comprises an endless conveyor  10 , preferably continuously running, a hot-glue applicator  11 , potentially having several hot-glue nozzles, a guide  12 , a folding bar  13 , a body  14 , and a conveyor drive  15 . The conveyor drive  15  propels the conveyor  10 , such that a flow of boxes (shown in  FIGS. 7   a - 7   d ) can be created from the inlet end, to the left in  FIG. 1 , towards the outlet end, to the right in  FIG. 1 , according to arrow A. 
         [0021]    The station  1  also comprises a final fold unit, denoted in general with  20  and shown in more detail in  FIG. 2 , and the unit  20  is mounted on the body  14 , straddling the conveyor  10 . The folding bar  13  is in the shown embodiment mounted on the folding unit  20 , but can just as well be mounted on the body  14 . The folding bar  13  is angled horizontally, as is shown in  FIG. 1 , but is also angled sideways, from the left side (as seen from the inlet end) to the right side. This enables the folding bar  13  to catch the open, vertical lid and gradually bring it to the horizontal position as shown in  FIG. 7   c.    
         [0022]    The folding unit  20  comprises a catch  21 , shown with phantom lines in  FIG. 2  and in more detail in  FIG. 3 . The catch  21  may be mounted on the body  14 . The catch  21  protrudes slightly above the level of the conveyor  10 , and a box lifting arrangement  22 , adjacent to the conveyor  10 . The unit  20  further comprises several flap folders  23 . The flap folders may be mounted at a top bar  24  of a frame  25  of the folding unit  20 . Further, a general box B is shown with phantom lines in  FIG. 2 . 
         [0023]    The catch  21  is shown in more detail in  FIG. 3 , in three different positions. The central position, denoted  21 ′, represents the rest position of the catch  21 , and a spring (not shown) can be arranged to automatically bring the catch  21  back to this rest position. The position  21 ″ represents an operative position, in which the catch  21  has been moved from the rest position  21 ′ by a box B moving on the conveyor  10 . The catch  21  is in this position caught by a stop  26 . The stop  26  may comprise a sensor  27 , indicated generally with phantom lines in  FIG. 3 . The presence of a box B against the catch  21  is now sensed by the sensor  27 , and the box is held stationary against the one, two or more catches, on the continuously running conveyor  10 . 
         [0024]    In an embodiment, the sensor  27  may be arranged at a distance from the catch  21 , however configured to detect when the catch is in the operative position  21 ″. The conveyor  10  can e.g. be made of a relatively slick material, which does not damage the box B when it is held stationary on top the moving conveyor surface. The deactivated position  21 ′″ of the catch  21  shows the position the catch  21  assumes when a box B has been lifted up, for final folding, and then is placed back on the conveyor  10 . After having stopped the box B, the box is lifted upwards, releasing the catch to again assume the rest position  21 ′. The box is then placed on the catch  21 , which now pivots the other way, counter-clockwise in  FIG. 3 , such that the box B can transported further downstream by the conveyor  10 . To this end, when the box B is lowered down onto the conveyor  10 , the bottom of the box B will push the catch  21  into the deactivated position  21 ′″, overcoming the spring force of the spring (not shown) seeking to bring the catch into the rest position  21 ′. To facilitate the operation of pushing the catch  21  into the deactivated position  21 ′″, the catch  21  has a horizontally slanted top surface in its rest position  21 ′. In this way, the sliding action of the bottom of the box B on the catch  21  is facilitated, whereby movement of the catch  21  into the deactivated position  21 ′″ is assured. 
         [0025]      FIG. 4  shows a flap folder  23  in a first rest position, in which it is ready to accept a box B for final folding of the lid and of the flaps of the lid. This position corresponds to the natural position the flap folder  23  assumes due to mass balance, and it does not need any further actuator. If needed, a spring or similar (not shown) can be fitted to more directly bring the flap folders to this position. 
         [0026]    The flap folder  23  may have a general L-shape. Also, the flap folder  23  may have substantially equally long legs. On the substantially vertically extending leg the flap folder may comprise a first pressure pad  23   a , for pressing a flap against the side of the box B. On the substantially horizontally extending leg the flap folder may comprise a second pressure pad  23   b , for pressing on the top of the lid of the box B. The final folder  23  is supported by pivot  23   c , about which the final folder  23  is freely pivotable (depending on the presence or not of a potential spring). 
         [0027]      FIG. 5  shows the flap folder  23  in a work position, in which the first  23   a  and second pressure pad  23   b  press on the side and top of the lid of box, shown partly with phantom lines, such that one leg of the flap folder  23  extends vertically and the other leg extends horizontally. 
         [0028]      FIG. 6  shows a cross-section of a generalized structure of the conveyor  10  and box lifting arrangement  22 . In the shown embodiment, there is a central conveyor  10 , and a box lifting table  22   a . A reinforcing frame  22   b  is mounted to the box lifting table  22   a . A hydraulic or pneumatic actuator  22   c  is further mounted to the under-side of the box lifting table  22   a , and is also connected to the body  14 . The actuator  22   c  can be fed with a working fluid, such as hydraulic oil or pressurized air, through a hose  22   d . When a box B is conveyed into the final folding unit  20 , the box lifting table  22   a  is preferably slightly below the level of the conveyor  10 . As soon as the box has pressed the catch  21  into activation of the sensor  27 , the lifting arrangement  22  pushes upwards and lifts the box B into the folding means  23 . It is also possible to have an arrangement in which the folding means  23  is driven down onto the box B, upon signal from the sensor  27 . The lifting arrangement and/or the means for transporting the folding means  23  downwards are generally referred to as transport means and is denoted as  22 . 
         [0029]    The operation and function of the final fold and out-feed station  1  will now be described in more detail. 
         [0030]    In  FIG. 7   a , a box B filled with packages (packages not shown) is brought to the inlet end of the conveyor  10 , which starts transporting the box to the right in  FIG. 7   a . In  FIG. 7   b , the box has passed the hot-glue station  11 , which has supplied the lid with several applications of hot-glue for gluing the lid to the box B. These applications are indicated in  FIG. 7   b  with lines on the lid, at the top of the box B. In the position shown in  FIG. 7   b , the folding bar  13  has started the initial folding of the lid, towards the open box B. The box B is guided on the conveyor  10  by the guide  12 , against the pushing of the folding bar  13 . 
         [0031]    In  FIG. 7   c , the box B has been brought against the catch  21 , which is then brought from its rest position  21 ′ to its working position  21 ″, where the catch  21  is stopped by the stop  26 , which in turn makes catch  21  stop the box B on the conveyor  10 . The catch  21  further activates sensor  27 , and the system is alerted that a box B is in position inside the final fold unit  20 . 
         [0032]    The box lifting arrangement or transport means  22  is now activated transporting the box upwards, away from the conveyor  10  and towards the flap folders  23  (or the flap folders  23  are transported downwards over the box). In  FIG. 7   c , two of the flap folders  23  have just started folding the side flaps of the lid towards the side of the box B. Further lifting and/or action of the transport means  22  will place the box B in the position shown in  FIG. 7   d . Here, flap folders  23  on all sides of the box B securely press the flaps of the lid against the sides of the box B, such that the adhesive on the flaps can cure and hold the lid in place. During the lifting motion and/or action of the transport means  22  of the box B, the catch  21  has resumed its resting position  21 ′, as shown in  FIG. 3 . The first pressure pad  23   a  presses against the flaps of the lid, whereas the second pressure pad  23   b  of each flap folder  23  presses against the top of the lid. All the force of the flap folders  23  is given by the transport means  22 . 
         [0033]    The box is then lowered towards the conveyor  10 , and the box B now presses the catch  21  to the position  21 ′″, as also shown in  FIG. 3 . In this position, the catch  21  does not hinder the box B from being transported by the conveyor  10 , and the box B is consequently moved towards the outlet by the conveyor  10 , to the right in  FIG. 7   d , where it is handled by further downstream equipment for subsequent delivery at a customer. In the case where the flap folders  23  are lowered onto the box, a separate release of the catch  21  should be installed. Such a release could for example be actuated when the flap folders are lifted from the box B. In this case the stop  26  may be lowered or releasingly pivoted away from its stopping position into a released position, such that the catch  21  no longer is stopped in its vertical position  21 ′″. A further spring (not shown) could then be mounted to return the catch  21  into its resting position, after the box B has passed the catch  21 . Only the further spring (not shown) then pulls the catch towards its resting position, but the weight of the box B overcomes this force. Thus, the box B may be further transported to the right in  FIGS. 7   a  to  7   d . When the box B has passed the catch  21 , the further spring (not shown) returns the catch  21  into its resting position  21 ′. Then the stop  26  is returned from its released position into its stopping position. 
         [0034]    When the box B is lowered from the flap folders  23  or the flap folders  23  are lifted, the flap folders  23  resume their rest position as can be seen in  FIG. 5 , due to the mass balance of said folders  23 . 
         [0035]    The system hence comprises a preferably continuously moving conveyor  10 , which can be driven by a cheap motor in the conveyor drive  15 . No sensors are needed for on-off control. The box lifting arrangement  22  is activated when the catch  21  is moved to position  21 ″, by box B being transported by conveyor  10  and interacting with the catch  21 . Flap folders  23  are then activated by the box lifting arrangement  22 , which only needs to lift the box B into contact with the flap folders  23  and/or lower the flap folders  23  into contact with the box B and with a set force, and release the pressure after a predetermined time period. The catch  21  is then automatically deactivated, as soon as the box B is lifted up towards the flap folders  23 , and the box B can be transported further downstream. 
         [0036]    The sensor  27  is in one embodiment a conductive switch, but any contact or proximity switch is suitable that can detect the movement of the catch  21  to the position  21 ″. 
         [0037]    The flap folders  23  are adjustable inwards or outwards of the centre of the frame  25 , in order to be able to handle boxes of different sizes. This adjustability can be done in several different ways, as is known to a person skilled in the art. Similarly, the folding bar  13  can in one embodiment be adjustable, to be able to adequately fold the lid of boxes with different heights. The adjustment of the flap folders  23  or the folding bar  13  is relatively easy and is typically performed manually, but it is of course obvious to a person skilled in the art that the adjustment for different sizes can be performed automatically. Also the height of the flap folders  23  above the conveyor is adjustable in a way known per se. 
         [0038]    The term flap folder is used together with the term flap folding means (folding means) to refer to the general means  23  for folding the flaps of the lid onto the sides of the box. The term box lifting arrangement is used alternately with the term transport means to refer to the general means  22  for moving the box B and folding means  23  into engagement with each other.