Patent Publication Number: US-2004052633-A1

Title: Pickup device for stacks of blanks

Description:
[0001] The present invention relates to a pickup device for stacks of blanks arranged in a group comprising a succession of superimposed layers, each separated from each adjacent layer by a separating sheet.  
       BACKGROUND OF THE INVENTION  
       [0002] Known pickup devices normally comprise a fork, which is fitted to a carriage movable in a pickup direction, and is connected to the carriage by an articulated actuating device for swinging the fork in a vertical plane parallel to the pickup direction. The fork is normally moved towards the group of stacks of blanks with its free end facing downwards, is simultaneously lowered onto the separating sheet beneath the top layer in the group, and is then slid, in the pick up direction and in contact with the separating sheet, underneath the stack to be picked up.  
       [0003] Unfortunately, the stacks in the layers do not normally all comprise exactly the same number of blanks, and therefore differ in height, so that the separating sheet comprises a number of flat portions, each contacting the top blank in a respective stack directly underneath, and a number of sloping portions connecting each flat portion to the surrounding flat portions. There is always a danger, therefore, that the fo rk, as it slides in contact with the separating sheet, encounters and punctures an upward sloping portion crosswise to the pickup direction, thus removing the separating sheet as well and causing all the stacks resting on it to fall off.  
       SUMMARY OF THE INVENTION  
       [0004] It is an object of the present invention to provide a pickup device designed to eliminate the aforementioned drawback.  
       [0005] According to the present invention, there is provided a pickup device for stacks of blanks, as claimed in claim 1 and preferabl y in any one of the following Claims depending directly or indirectly on claim 1. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0006] A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:  
     [0007]FIG. 1 shows a schematic side view of a preferred embodiment of the pickup device according to the present invention;  
     [0008]FIG. 2 shows a larger-scale view in perspective of a detail in FIG. 1;  
     [0009] FIGS.  3  to  5  show larger -scale side views of a FIG. 1 detail in three different operating positions.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0010] Number  1  in FIG. 1 indicates as a whole a pickup device for successively picking up stacks  2  of blanks off a group  3  of stacks  2  arranged in a number of superimposed, substantially vertical layers  4 , each separated from the underlying layer  4  by a separating sheet  5 , normally of cardboard or similar.  
     [0011] The stacks  2  directly beneath each separating sheet  5  do not all comprise exactly the same number of blanks, and therefore differ in height, so that each separating sheet  5  comprises a number of flat portions  6 , each contacting the top blank in a respective stack  2  directly underneath, and a number of sloping portions  7  (sloping at an exaggerated angle in FIG. 1 for t he sake of clarity) connecting each flat portion  6  to the surrounding flat portions  6 .  
     [0012] Pickup device  1  is located over a top layer  4   a  in group  3 , and comprises a fork  8  projecting, in a pickup direction  9  and by a length similar to the length of a stack  2  measured in direction  9 , from one end of a connecting rod  10  of an articulated actuating device  10   a  moving in a plane parallel to direction  9  and comprising, in addition to connecting rod  10 , two cranks  11  and  12  hinged, at one end, to opposite ends of co nnecting rod  10 , and, at the other end, to a powered carriage  13  moved in a direction  14  parallel to direction  9  by a logic unit not shown. Carriage  13  houses a known drive assembly (not shown), which, under the control of said logic unit (not shown), activates cranks  11  and  12  independently to move fork  8  and possibly adjust its inclination with respect to a horizontal plane.  
     [0013] As shown in FIG. 2, fork  8  is defined by a plate or beam  15 , an end portion of which is hinged to the free ends of cranks  11  and  12 , and from the free end of which project axially outwards substantially triangular axial appendixes  16  defined at the top by a surface coplanar with a top surface  17  of beam  15 , and defined at the bottom by an end surface  18  sloping with respect to a bottom surface  19  of beam  15  and forming an angle A with top surface  17 .  
     [0014] A rocking skid  20  is hinged to appendixes  16 , rocks with respect to beam  15  about an intermediate horizontal axis  21  crosswise to a longitudinal axis  22  of beam  15 , and comprises two ar ms  23  and  24  on opposite sides of axis  21 . Rocking skid  20  comprises a base plate  25  located below axis  21  and defined at the bottom by a flat surface  26  common to arms  23  and  24  and having an intermediate transverse recess  27  extending parallel to axis  21 . Arm  23 , located to the front of axis  21  in pickup direction  9 , is substantially triangular in section, and is defined at the top by a surface  28 , which forms, with surface  26 , an angle B smaller than angle A, and intersects surface  26  along a front edge  29 , parallel to axis  21 , of rocking skid  20 . Through surface  28  are formed longitudinal grooves  30 , each of which houses a respective appendix  16 , is defined by a bottom surface  31  parallel to surface  26 , and defines, with each adjacent groove  30 , a longitudinal rib  32  connected, together with the other ribs  32 , to appendixes  16  by a pin  33  coaxial with axis  21 .  
     [0015] Arm  24  is located beneath an end portion of beam  15 , is heavier than arm  23 , and comprises, at the rear end, a transverse rib  34 , which extends u pwards from the rear end of base plate  25 , is parallel to axis  21 , and is defined at the top end by a sloping surface  35  parallel to surface  28 .  
     [0016] Rib  34  constitutes a stop member for limiting oscillation of rocking skid  20 , and is of such a height that, when surface  35  contacts bottom surface  19  of beam  15 , surface  28  of arm  23  is coplanar with top surface  17  of beam  15 . Appendixes  16  as a whole define a further stop member for limiting oscillation of rocking skid  20  about axis  21  due to the greater weight of arm  24  with respect to arm  23 , and, in the absence of other forces on rocking skid  20 , arrest rocking skid  20  with end surfaces  18  of appendixes  16  contacting bottom surfaces  31  of grooves  30 .  
     [0017] In actual use, as shown in FIGS.  3  to  5 , rocking skid  20  enables fork  8  to slide smoothly along separating sheet  5  and overcome any differences in level—actually relatively small—along the top surface of separating sheet  5 .