Abstract:
A covering machine for applying a covering sheet on packing boxes, includes a covering cavity for receiving a box joined to a respective covering sheet, and presser elements which can be associated with the box and are able to move between a first, active position in which they apply the respective sheet to the box and a second, extracted position away from the box.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a covering machine for packing boxes, in particular for covering boxes with a covering sheet on which glue has already been applied. 
         [0002]    There are prior art so called “covering machines” for joining an erected box and a covering sheet to which glue was previously applied. 
         [0003]    Examples of such machines were the subject matter of patents IT1224973 and IT1269105 by the same Applicant. 
         [0004]    Such machines have a movement system with which the box is transported to a covering unit which applies the sheet on which glue has already been applied to the walls of the box to complete box covering. 
         [0005]    The boxes are brought to the covering unit already joined to the respective covering sheet. In this situation, the box rests on the central portion of the inner surface of the covering sheet on which glue has already been applied, and with the respective opening facing upwards. 
         [0006]    Covering machines have a mould, supported by respective movement elements which move the mould vertically. In this way, when the box joined to the respective covering sheet is brought to the covering unit, the mould is moved downwards and inserted in the box to push it into a forming cavity in which the covering sheet is applied to the walls of the box. 
         [0007]    Covering machines also have rollers or brushes on the edges which form the forming cavity, designed to make contact with the outer surface of the covering sheet which is in contact with the corresponding walls of the box. 
         [0008]    During the mould return stroke, the covered box is stopped by extractors which engage the box, allowing it to be removed from the mould. The covering machine then moves the box towards other processing stations. 
         [0009]    However, prior art covering machines have the important disadvantage of not being suitable for covering “narrow” boxes, that is to say, boxes with small transversal dimensions. 
         [0010]    Said disadvantage is mainly due to the dimensions of the mould movement and supporting elements, which must at least partly enter the forming cavity so that the box can be covered completely. 
         [0011]    In this situation it should be noticed that the brushes or rollers which form the inlet edge of the forming cavity must be suitably spaced to allow said movement elements to pass between them. 
         [0012]    Consequently, boxes with dimensions less than the minimum distance between the brushes, corresponding to the minimum dimensions of the movement elements, cannot be covered. 
       SUMMARY OF THE INVENTION 
       [0013]    The aim of the present invention is therefore to overcome the above-mentioned disadvantage by providing a covering machine for packing boxes which is highly flexible for use with boxes even having extremely limited transversal dimensions. 
         [0014]    Accordingly, the present invention achieves this aim with a covering machine as described in the claims herein. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The technical features of the invention, in accordance with the afore-mentioned aims, are clearly indicated in the claims herein and the advantages of the invention are more apparent in the detailed description which follows, with reference to the accompanying drawings, which illustrate a preferred embodiment by way of example only and without limiting the scope of the invention, in which: 
           [0016]      FIG. 1  is a plan view of a box production line including the covering machine in accordance with the present invention; 
           [0017]      FIG. 2  is a schematic perspective view of the covering machine for packing boxes in accordance with the present invention; 
           [0018]      FIG. 3  is a perspective view of the covering machine of  FIG. 2  during a first step of covering a box; and 
           [0019]      FIG. 4  is a perspective view of the covering machine of  FIG. 2  during a second step of covering a box. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    With reference to the accompanying drawings, the numeral  1  denotes as a whole a covering machine for packing boxes. 
         [0021]    The covering machine can be used in a covering line of the type illustrated in  FIG. 1 , which schematically indicates a unit  2  for gluing covering sheets “F” and a unit  3  for erecting the boxes “S” to be covered. 
         [0022]    The sheets “F” and the boxes “S” are conveyed by respective belts  4 ,  5  which converge in a joining station  6  from which a succession of boxes “S” positioned on top of sheets “F” on which glue has already been applied are moved to the covering unit  1 . 
         [0023]    The movement of the box “S” and the sheet “F” is of the conventional type and therefore is not described in further detail. 
         [0024]      FIG. 2  schematically illustrates the functional components of a covering unit  1  in accordance with the invention. 
         [0025]    The covering machine  1  has a cavity for receiving a box “S” joined to the respective covering sheet “F”, as illustrated in  FIGS. 3 and 4 . 
         [0026]    It should be noticed that the accompanying drawings illustrate a box “S” having the shape of a parallelepiped placed in a central position on the sheet which is schematically indicated with “F”. However, the present invention may be used for boxes “S” and sheets “F” having any suitable shape and size. 
         [0027]    For example, if the box “S” and the sheet F have four lateral walls/faces, the cavity  7  will have four edges  8 , each of which may be associated with a respective wall of the box “S”, to form an access opening  9  below which the cavity  7  extends. 
         [0028]    In this situation, widely used, a first pair of edges  8  is positioned above a second pair of edges  8  extending perpendicularly to the first pair. 
         [0029]    In more detail, with reference to  FIG. 3 , the forming cavity  7  has two outer edges  8  opposite one another and able to be associated with an outer surface of the sheet “F” to make the sheet “F” adhere to the respective opposite walls of the box “S”. 
         [0030]    Again with reference to the embodiment illustrated in the accompanying drawings, each edge  8  consists of a roller  10 , having a cylindrical surface  10   a  which can be abutted to the outer surface of the covering sheet. 
         [0031]    Alternatively, the edges  8  may consist of two brushes (not illustrated in the accompanying drawings) which can be abutted to the outer surface of the covering sheet “F” and each of which has a main longitudinal extension corresponding to the wall of the sheet to which they are drawn near. 
         [0032]    Both the rollers  10  and the brushes are parallel with one another and supported by guides or shafts  12  sliding in supports  11  parallel with a horizontal direction “A” perpendicular to the longitudinal extension of the brushes and to the axis of rotation of the rollers  10 . 
         [0033]    The covering machine  1  also has vertical stroke means  13  illustrated in  FIGS. 3 and 4 , which can be associated with the box “S” and can move with a first, downward stroke in which they push the box “S” and the respective sheet “F” into the forming cavity  7  and a second, upward stroke out of the cavity  7 . 
         [0034]    The vertical stroke means  13  advantageously consist of a mould  14  having the same profile and internal dimensions as the box “S” and which can be inserted in the box “S”. The mould  14  is supported by an arm  15  extending vertically above the cavity  7  and having a lower end  15   a  associated with the mould  14  and an upper end  15   b  opposite the lower end  15   a  and suitably connected to respective movement means which are known and therefore not described and illustrated in further detail. 
         [0035]    The arm  15  is illustrated as having a rectangular shape to show the relative longitudinal and transversal dimensions, but it shall be understood that the arm may have a different shape, for example cylindrical. 
         [0036]    It should be noticed that the mould  14  may be substituted and mounted on the arm  15  according to the dimensions of the box “S” to be used. In this context, if small boxes “S” must be covered, the cross-section dimensions of the mould  14  are smaller than the cross-section dimensions of the arm  15 . 
         [0037]    In operation, the arm  15  moves the mould  14  along a vertical direction “B” to insert the box “S” in the cavity  7 , perform the downward covering stroke and then the vertical stroke for extracting the covered box from the mould  14 . 
         [0038]    In more detail, with the vertical stroke means  13  in the first position the mould  14  is inserted in the box “S” and it is pushed below the edges  8 . In this situation, the box “S” and consequently also the mould  14  is made to pass through the opening  9  into the cavity until the arm  15  is positioned in the access opening  9  ( FIG. 4 ). During this movement the flaps of the sheet “F” are folded over the walls of the box “S” and made to adhere to them. 
         [0039]    Then, the arm  15  performs an extraction of an upper section of the mould, called the counter-mould, from the box S followed by a limited downward movement of the counter-mould to fold the projecting flaps of the sheet over the edges of the box in combination with sheet flap folding elements  20 , of the known type and not part of the specific subject matter of the present invention. 
         [0040]    Once this folding over is complete, the arm  15  returns to its position above the cavity  7 , returning the mould to its starting position and allowing extraction of the covered box “S”. 
         [0041]    The covering machine  1  also comprises first means  16  for moving the rollers/brushes  10  towards/away from the box “S”. 
         [0042]    In particular, the movement means  16  are associated with the supports  11  and move the edges  8  along the horizontal direction “A” towards one another ( FIG. 3 ) so that they make contact with the outer walls of the box “S”, and away from one another so that they are moved away from the walls of the box “S” ( FIG. 4 ). 
         [0043]    In this way, with the vertical stroke means  13  in the first position in which they push the box “S” into the cavity  7 , the rollers  10  are moved towards one another into a contact position in which they are drawn near the walls of the box when the box is at the access opening  9 , whilst they are moved away from one another into a detached position when covering is complete. 
         [0044]    Advantageously, according to the invention there are second horizontal movement means comprising at least one actuator schematically indicated with  17  and preferably two linear actuators  17 , each associated with a respective shaft  12  to move it along the horizontal direction “A”. 
         [0045]    Each support  11  is preferably joined to two actuators  17  each of which consists of a pneumatic piston for making the shafts  12  slide with a to and fro motion. 
         [0046]    The actuators  17  are also connected to one another by suitable control means, of the known type and therefore not illustrated and described, which move the actuators  17  of each carriage  11  in a synchronized way according to the stroke of the vertical stroke means  13 . 
         [0047]    Advantageously, the presence of the secondary actuators  17  allows the rollers  10  to be rapidly moved backwards as soon as they have covered the respective walls of the box and the mould  14  and the arm  15  must continue the downward stroke to cover the short walls or to fold over the covering sheet. 
         [0048]    Consequently, thanks to the invention it is possible to cover a box which even has a very limited width in automated covering machines, even pre-existing ones, designed for a minimum width equal to the dimensions of the arm  15 . 
         [0049]    Moreover, the covering machine  1  advantageously has an extractor element which can engage the covered box “S” to detach it from the mould  14 . 
         [0050]    The invention described is susceptible of industrial application and may be modified and adapted without thereby departing from the scope of the inventive concept. Moreover, all details of the invention may be substituted by technically equivalent elements.