Patent Publication Number: US-2004051328-A1

Title: Unit for handling a product comprising at least one ream of sheets

Description:
[0001] The present invention relates to a unit for handling a product comprising at least one ream of sheets.  
       [0002] More specifically, the present invention relates to a unit for handling reams of sheets in a ream palletizing system, to which the following description refers purely by way of example.  
       BACKGROUND OF THE INVENTION  
       [0003] Reams of sheets are known to be palletized using a system comprising a feed device for feeding a substantially orderly succession of reams to an input station of a palletizing device, which feeds each ream to a palletizing station where the reams are stacked on a supporting pallet.  
       [0004] The palletizing device normally comprises a conveyor, in turn comprising two chains lying in parallel planes to define an endless path, and having a number of supporting members extending between the chains to define conveying surfaces. The conveying surfaces are equally spaced along the path with a spacing approximately equal to but no less than the length of the reams measured parallel to the path, and are fed continuously through the input station in time with respective reams.  
       [0005] At the palletizing station, each ream engages a stop member across the path, and is gradually released from the relative conveying surface and deposited onto the underlying reams or, in the case of the first ream, onto the underlying pallet.  
       [0006] Known palletizing devices of the above type are therefore relatively bulky and expensive.  
       [0007] Moreover, on account of the reams being arrested against the stop member, the palletizing device is either inaccurate, by being unable to establish a precise position of the reams at the palletizing station, or is accurate but relatively slow.  
       SUMMARY OF THE INVENTION  
       [0008] It is an object of the present invention to provide a unit for handling a product comprising at least one ream of sheets, designed to eliminate the aforementioned drawbacks.  
       [0009] According to the present invention, there is provided a unit for handling at least one product comprising at least one ream of sheets, the unit being characterized by comprising at least two gripping members; and actuating means for moving the gripping members to and from a gripping position wherein the gripping members engage the product on opposite sides of the product in a given first direction.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0010] A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:  
     [0011]FIGS. 1 and 2 show two schematic views in perspective of a preferred embodiment of the unit according to the present invention in two different operating positions;  
     [0012]FIG. 3 shows a schematic view in perspective of a detail in FIGS. 1 and 2;  
     [0013]FIGS. 4 and 5 show two schematic views in perspective of a further embodiment of the unit according to the present invention in a first operating position;  
     [0014]FIG. 6 shows a front view of the FIG. 4 and  5  unit;  
     [0015]FIG. 7 shows a schematic view in perspective of the FIG. 4 and  5  unit in a second operating position;  
     [0016]FIG. 8 shows a schematic plan view of an operating mode of the FIG. 4 and  5  unit. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0017] With reference to FIGS. 1 and 2, number  1  indicates as a whole a unit for handling a product  2  defined, in the example shown, by a ream  2   a  of sheets (not shown) comprising a number of sheets (not shown) superimposed in a substantially vertical direction  2  and normally wrapped in a sheet of wrapping material (not shown).  
     [0018] Obviously, in alternative embodiments not shown, product  2  is defined by a stack of reams  2   a  superimposed in direction  3 .  
     [0019] Unit  1  comprises a supporting frame  4  connectable to a robot assembly (not shown) for moving unit  1  in space; and two gripping members  5  movable, with respect to frame  4  and by an actuating assembly  6 , to and from a gripping position wherein members  5  engage ream  2   a  on opposite sides of ream  2   a  in a substantially horizontal direction  7  crosswise to direction  3 .  
     [0020] With reference to FIG. 3, each member  5  comprises two metal sections  8 , which extend parallel to each other and to a direction  9  perpendicular to directions  3  and  7 , are connected to each other by a number of uprights  10  parallel to one another and to direction  3 , and are located one (hereinafter indicated  8   a ) over the other (hereinafter indicated  8   b ). Section  8   b  is defined laterally by a flat surface  11  positioned facing ream  2   a , and has a flat plate  12  projecting from surface  11  towards ream  2   a  to define a fixed bottom jaw  12   a  of member  5 .  
     [0021] Member  5  also comprises a top jaw  13  defined by a section  14 , which is fitted in sliding manner to two cylindrical guides  15  extending parallel to direction  3  and fitted between sections  8   a  and  8   b , and is also fitted to a screw  16  by a screw-nut screw coupling  17  of a relative actuating device  18 , a motor  19  of which rotates screw  16  to move section  14  linearly along guides  15  in direction  3 .  
     [0022] Device  18  forms part of actuating assembly  6 , and also comprises two racks  20  fitted to respective uprights  10  and parallel to direction  3 ; a shaft  21  fitted in rotary manner to section  14  to rotate, with respect to section  14 , about an axis  22  substantially parallel to direction  9 ; and two sprockets  23  fitted to the free ends of shaft  21  to mesh with racks  20  as section  14  moves along guides  15 .  
     [0023] Actuating assembly  6  also comprises, for each gripping member  5 , two actuating devices  24 , each of which in turn comprises a crank mechanism  25  having a crank  26  hinged to frame  4  to oscillate, with respect to frame  4 , about a hinge axis  27  substantially parallel to direction  3 , and a connecting rod  28 , an intermediate point of which is hinged to a free end of crank  26 , a first free end of which is connected in rotary manner to one of guides  15 , and a second free end of which is hinged to a slide  29  shared with one of crank mechanisms  25  of the other gripping member  5 . Connecting rod  28  therefore oscillates, with respect to crank  26 , to slide  29 , and to relative guide  15 , about respective hinge axes  30 ,  31 ,  32  substantially parallel to one another and to axis  27 .  
     [0024] Slide  29  is fitted in sliding manner to a guide  33  fitted to frame  4  and parallel to direction  9 , and is also connected to a screw  34 —to which the other slide  29  is also connected—by a screw-nut screw coupling  35  of a relative actuating device  36 , a motor  37  of which rotates screw  34  by means of a belt drive  38  to move slide  29  linearly along guide  33  in direction  9  and in time with the linear movement of the other slide  29 .  
     [0025] In connection with the above, it should be pointed out that:  
     [0026] each axis  30  is located the same distance from each of relative axes  27 ,  31 ,  32 , so that surface  11  of relative member  5  is perpendicular at all times to direction  7  as relative member  5  moves in direction  7 ;  
     [0027] axes  27  and  31  of each crank mechanism  25  are aligned with each other and with axes  27  and  31  of the other crank mechanism in direction  9 ; and  
     [0028] each axis  27  is aligned with relative axis  32  in direction  7  as relative member  5  moves in direction  7 .  
     [0029] In a variation not shown, slides  29  may be moved along guide  33  by cranks  26 , which are powered in time with each other.  
     [0030] Operation of unit  1  will now be described, as of the instant in which:  
     [0031] gripping members  5  have been moved with respect to each other in direction  7 , so that the distance between surfaces  11  is greater than the width of ream  2   a  measured parallel to direction  7 ;  
     [0032] jaws  12   a ,  13  have been moved with respect to each other in direction  3 , so that the distance between jaws  12   a ,  13  is greater than the thickness of ream  2   a  measured parallel to direction  3 ; and  
     [0033] unit  1  has been moved by said robot assembly (not shown), so that members  5  are positioned on opposite sides of ream  2   a  in direction  7 .  
     [0034] At this point, members  5  are moved in direction  7 , so that surfaces  11  engage ream  2   a ; and jaws  12   a  and  13  are moved in direction  3  to grip ream  2   a , which may then be transferred accurately, for example, to a palletizing station (not shown) where reams  2   a  are stacked in direction  3  on a supporting pallet (not shown).  
     [0035] In connection with the above, it should be pointed out that, when the ratio between the dimensions of ream  2   a  measured parallel to directions  7  and  9  is relatively high, members  5  can be parted in direction  7  to enable unit  1  to transfer ream  2   a  in a perfectly horizontal position.  
     [0036] FIGS.  4  to  8  show a unit  39  for handling a number of (in the example shown, four) products  2 , each defined by a substantially parallelepiped-shaped cardboard box  2   b , which contains a stack of reams  2   a  (not shown in FIGS.  4  to  8 ) stacked in a substantially vertical direction  40 , and is defined by two parallel, respectively top and bottom, faces  2   c  perpendicular to direction  40 , and by four lateral faces  2   d  perpendicular to faces  2   c.    
     [0037] Obviously, in alternative embodiments not shown, each product  2  is defined by one ream  2   a  or by a stack of reams  2   a  stacked in direction  40 .  
     [0038] Unit  39  comprises a supporting frame  41  defined at the front by a substantially flat vertical surface  42 , and connectable to a robot assembly (not shown) for moving unit  39  in space; and, in the example shown, two gripping devices  43 , which are fitted to frame  41  side by side in a horizontal direction  44  parallel to surface  42 , and are designed to each handle two products  2 .  
     [0039] Each device  43  is a gripping device comprising two jaws  45 ,  46 , of which jaw  45  is a top jaw defined by a flat plate  47  substantially perpendicular to surface  42 , and jaw  46  is a bottom jaw defined by a flat plate  48  substantially parallel to plate  47 .  
     [0040] Plate  47  is equipped on the underside surface with a number of suction cups (not shown) distributed over plate  47 , is fitted in sliding manner to a guide  49  fitted to frame  41  and parallel to direction  40 , and is also connected to a screw  50  by a screw-nut screw coupling  51  of a relative actuating device  52 , a motor  53  of which rotates screw  50  by means of a belt drive  54  to move plate  47  linearly along guide  49  in direction  40 .  
     [0041] Plate  48  is fitted to the free end of an output shaft (not shown) of a motor  55  to oscillate, with respect to frame  41  and about a hinge axis  56  parallel to direction  40 , between a loading position (FIGS. 4 and 5) wherein plate  48  is located substantially beneath plate  47 , and an unloading position (FIG. 7) wherein plates  47  and  48  are located on opposite sides of surface  42  in a direction  57  perpendicular to directions  40  and  44 .  
     [0042] In a variation not shown, each plate  48  is fitted in sliding manner to frame  41  to move, with respect to frame  41 , between the loading and unloading positions in direction  57 .  
     [0043] Operation of unit  39  will now be described with reference to one device  43  and one box  2   b , and as of the instant in which jaw  46  is set to the loading position, and jaw  45  is positioned along guide  49  so that the distance between jaws  45  and  46  is greater than the height of box  2   b  measured parallel to direction  40 .  
     [0044] Box  2   b  is loaded onto unit  39  by feeding box  2   b  in direction  57  into contact with surface  42  (e.g. by means of a pusher not shown); then moving jaw  45  along guide  49  into a gripping position in which jaws  45 ,  46  grip box  2   b ; and finally activating the suction cups (not shown) to retain box  2   b  firmly.  
     [0045] Box  2   b  is unloaded by moving jaw  46  into the unloading position, and then deactivating the suction cups (not shown).  
     [0046] With reference to FIG. 8, unit  39  has been found to be particularly advantageous. in pallet loading operations, wherein boxes  2   b  are loaded onto a supporting pallet (not shown) for supporting a number of superimposed layers of boxes  2   b , and wherein each layer comprises a number of boxes  2   b.    
     [0047] Unit  39 , in fact, which is designed to leave at least three of the four lateral faces  2   d  of box  2   b  free, provides for accurately positioning box  2   b  in the relative layer, even in the event the box  2   b  being handled is to be positioned contacting two or three boxes  2   b  already in the relative layer.