Abstract:
In a device for conveying stacks of sheets of paper or the like, each stack is caused to advance along a pre-set path inside a pocket, which has a resting surface for supporting the stack and is provided with at least one pressure member designed to grip the stack on the resting surface during at least part of the displacement of the pocket along the path.

Description:
[0001]    The present invention relates to a device for conveying stacks of sheets of paper or the like.  
           [0002]    In particular, the present invention relates to a device for conveying stacks of sheets of paper or the like of the type comprising a pocket conveyor, which extends from an input station to an output station and is provided with a plurality of pockets, each of which has a resting surface for a respective stack and is designed to feed the stack itself to the aforementioned output station and against a sheet of wrapping paper, which is subsequently folded over the stack in a substantially U-shaped configuration.  
         BACKGROUND OF THE INVENTION  
         [0003]    Known conveyor devices of the type described above present some drawbacks, the main one of which derives from the fact that, when the operating speed exceeds a pre-determined value, the contact of each stack against the corresponding sheet of wrapping paper can jeopardize correct positioning of the sheets with respect to one another and, consequently, of the sheets with respect to the sheet of wrapping paper.  
         SUMMARY OF THE INVENTION  
         [0004]    The purpose of the present invention is to provide a device for conveying stacks of sheets of paper or the like which is free from the drawbacks outlined above.  
           [0005]    According to the present invention, a device is provided for conveying stacks of sheets of paper or the like, the device comprising a pocket conveyor equipped with a plurality of pockets, each of which has a resting surface for a respective said stack and is designed to cause the stack to advance along a path that is substantially parallel to said resting surface, and being characterized in that it comprises pressure means set along said path in order to grip each of said stacks on said resting surface during at least part of the displacement of the stack along the path. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The invention will now be described with reference to the annexed drawings, which illustrate a non-limiting example of embodiment thereof and in which:  
         [0007]    [0007]FIG. 1 is a schematic perspective view of a preferred embodiment of the conveyor device according to the present invention; and  
         [0008]    [0008]FIG. 2 is a schematic perspective view of a detail of FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0009]    With reference to FIG. 1, number  1  designates, as a whole, a device for conveying stacks  2  of sheets (not illustrated), each of which comprises a plurality of sheets set on top of one another in a pre-determined direction  4 , and has two larger side faces  2   a  parallel to one another and perpendicular to the direction  4 , two smaller side faces  2   b  parallel to one another and perpendicular to the faces  2   a,  and two smaller side faces  2   c  parallel to one another and perpendicular to the faces  2   a  and  2   b.    
         [0010]    The device  1  comprises a pocket conveyor  5 , which extends from an input station  6  to an output station  7  and is designed to cause the stacks  2  to advance in succession in a predetermined direction  8  and along a pre-determined path P.  
         [0011]    The conveyor  5  comprises a bottom belt conveyor  9 , which comprises, in turn, a plurality of belts  10 , each of which is designed to move in a vertical plane parallel to that of the other belts  10  and is wound in a loop around a pair of pulleys (not illustrated), one of which is driven in a continuous way. The said pulleys are mounted on a frame  11  of the device  1 , so that they can turn about respective axes  12  transverse to the direction  8 .  
         [0012]    Each belt  10  has a top conveying branch  13 , which is substantially co-planar to the branches  13  of the other belts  10  so as to define a conveying surface P 1  that is substantially horizontal, on which each stack  2  is caused to advance “lying flat”, i.e., with one of the faces  2   a  set on the surface P 1 , with the faces  2   b  set perpendicular to the direction  8 , and with the faces  2   c  set parallel to said direction.  
         [0013]    The conveyor  5  further comprises two side belt conveyors  14 , which extend parallel to the direction  8 , are set on opposite sides of the path P, each of which comprises a respective plurality of belts  15 , each of said belts being able to move on a horizontal plane parallel to that of the other belts  15 , and is wound in a loop around a pair of pulleys  16 , one of which is motor driven in an intermittent way. The pulleys  16  are mounted on the frame  11 , so that they can turn about respective axes  17  parallel to the direction  4 .  
         [0014]    Each belt  15  has a side conveying branch  18 , which is substantially co-planar to the branches  18  of the other belts  15  of the corresponding conveyor  14 , faces a corresponding branch  18  of the other conveyor  14 , and is set at a distance from the corresponding branch  18 , which is at least equal to the width of a stack  2  measured parallel to a direction  19  orthogonal to the directions  4  and  8 .  
         [0015]    Mounted on the belts  15  of each conveyor  14  is a plurality of pushing-and-accompanying elements  20  (in the case in point, four elements  20 ), which are caused to advanced in phase with the elements  20  of the other conveyor  14  and can be divided into two pairs of elements  20 . The elements  20  of each of the aforementioned pairs define, together with corresponding elements  20  of the other conveyor  14  and the belts  10 , a pocket  21 , which has a length, measured parallel to the direction  8 , at least equal to the length of the stack  2 , which is also measured parallel to the direction  8 .  
         [0016]    Each pocket  21  is, thus, limited at the front in the direction  8  by two elements  20 , designated, in what follows, by  20   a,  and at the rear in the direction  8  by two elements  20 , designated, in what follows, by  20   b.  Each element  20   b  is substantially L-shaped, has a bottom jaw  22  that is substantially plane and co-planar to the surface P 1 , and is provided with a top pressure member  23  comprising a pin  24 , which extends in the direction  4  and above the jaw  22 , is slidably coupled to the element  20   b,  and is normally kept in a raised released position, in which the pin  24  sets itself at a distance from the jaw  22  greater than the thickness of the stack  2  measured parallel to the direction  4  by a spring  25  set between the element  20   b  and the pin  24  itself.  
         [0017]    The pin  24  supports, on one of its top free ends, a tappet roller  26 , which is mounted, so that it can turn, on the pin  24  itself, and engages a cam  27  fixed to the frame  2  parallel to the direction  8 , so as to move from the aforementioned raised released position into a lowered gripping position, in which the pin  24  engages the top face  2   a  of the corresponding stack  2  to grip the stack  2  itself on the surface P 1 .  
         [0018]    In use, each pocket  21  is designed to receive, at the input station  6  and with the corresponding pressure members  23  set in their raised released positions, a corresponding stack  2  from a conveyor device  28  of a known type, which comprises, in the case in point, a plurality of belts  29 , each of which can move on a vertical plane parallel to that of the other belts  29  and is wound in a loop around a pair of pulleys (not illustrated) mounted, so that they can turn, on the frame  11 , and has a top conveying branch  30  substantially co-planar to the surface P 1 .  
         [0019]    Once the elements  20   b  have engaged the stack  2 , the pressure members  23  move into their lowered gripping positions for gripping the stack  2  on the conveying surface P 1 , and the stack  2  is fed along the path P and to the output station  7 .  
         [0020]    At the station  7 , the stack  2  is fed first through a feed channel  31 , which is defined by two bars  32  set parallel to one another and parallel to the direction  19 , and has a height, measured parallel to the direction  4 , that is at least equal to the thickness of a stack  2 , and then against a corresponding sheet of wrapping paper  33 , which is set orthogonal to the direction  8  and is folded over the stack  2  in a substantially U-shaped configuration, following upon contact with the stack  2  and the thrust imparted on the stack  2  by the elements  20   b.    
         [0021]    With reference to the above description, it should be pointed out that:  
         [0022]    the cam  27  is shaped so that, when each stack  2  engages the corresponding sheet of wrapping paper  33 , the pressure members  23  of the corresponding pocket  21  are set in their lowered gripping positions;  
         [0023]    the rate of advance of the belts  10  approximates with a degree of underestimation the rate of advance of the belts  15  so as to enable the elements  20   b  of each pocket  21  to engage the corresponding stack  2  and to remain in contact with the stack  2 ; and  
         [0024]    the positions of the conveyors  14  in the direction  4  are controlled selectively according to the thickness of the stacks  2 .