Feed unit for feeding sheets to a packing line

Abstract

A feed unit for feeding sheets to a packing line, wherein a pickup device engages a withdrawal opening of a hopper, housing a stack of sheets, to withdraw one sheet from the stack and feed the sheet to the packing line; at least one supporting member is located at the withdrawal opening of the hopper to reduce the passage section of the withdrawal opening and retain the sheets in the stack inside the hopper, and is movable in an adjustment direction; and an adjusting member is connected to the supporting member to adjust, in use, the position of the supporting member in the adjustment direction as a function of the size, measured in the adjustment direction, of the sheets located close to the withdrawal opening.

1 ) A feed unit for feeding sheets to a packing line; the feed unit ( 1 ) comprising: 
 a hopper ( 3 ) having a withdrawal opening ( 5 ) and housing a stack ( 4 ) of sheets ( 2 ) extending in a feed direction (D 1 ); and    a pickup device ( 6 ), which engages the withdrawal opening ( 5 ) of the hopper ( 3 ) to withdraw a single sheet ( 2 ) from the stack ( 4 ) through the withdrawal opening ( 5 ), and feed the sheet ( 2 ) to the packing line;    the feed unit ( 1 ) being characterized by comprising:    at least one first supporting member ( 16 ), which is located at the withdrawal opening ( 5 ) and perpendicular to the feed direction (D 1 ) to reduce the passage section of the withdrawal opening ( 5 ) and retain the sheets ( 2 ) in the stack ( 4 ) inside the hopper ( 3 ), and is movable in an adjustment direction (D 2 ) perpendicular to the feed direction (D 1 ); and    an adjusting member ( 17 ) for adjusting, in use, the position of the first supporting member ( 16 ) in the adjustment direction (D 2 ) as a function of the size, measured in the adjustment direction (D 2 ), of the sheets ( 2 ) located close to the withdrawal opening ( 5 ).    
   
   
       2 ) A feed unit as claimed in  claim 1 , wherein the adjusting member ( 17 ) is elastic, and pushes the first supporting member ( 16 ) elastically with a given force towards the stack ( 4 ) in the adjustment direction (D 2 ).  
   
   
       3 ) A feed unit as claimed in  claim 2 , and comprising a deformable elastic body ( 18 ), which has a first portion ( 19 ) defining the first supporting member ( 16 ), and a second portion ( 20 ) defining the elastic adjusting member ( 17 ).  
   
   
       4 ) A feed unit as claimed in  claim 3 , wherein the first portion ( 19 ) of the elastic body ( 18 ) is perpendicular to the feed direction (D 1 ) and forms an angle of over 90° with the second portion ( 20 ).  
   
   
       5 ) A feed unit as claimed in  claim 4 , wherein the first portion ( 19 ) of the elastic body ( 18 ) forms an obtuse angle of 95° to 110° with the second portion ( 20 ).  
   
   
       6 ) A feed unit as claimed in  claim 3 , wherein the second portion ( 20 ) of the elastic body ( 18 ) is L-shaped.  
   
   
       7 ) A feed unit as claimed in  claim 3 , wherein the second portion ( 20 ) of the elastic body ( 18 ) is fixed rigidly in an adjustable position to a fixed frame ( 15 ) of the hopper ( 3 ).  
   
   
       8 ) A feed unit as claimed in  claim 3 , wherein the deformable elastic body ( 18 ) is made of elastic spring steel.  
   
   
       9 ) A feed unit as claimed in  claim 2 , wherein the elastic adjusting member ( 17 ) pushes in the adjustment direction (D 2 ) the sheets ( 2 ) located close to the withdrawal opening ( 5 ).  
   
   
       10 ) A feed unit as claimed in  claim 1 , and comprising at least one nozzle ( 23 ) connected to a compressed-air source ( 24 ) and located close to the withdrawal opening ( 5 ) to blow a jet of compressed air onto the stack ( 4 ) in a blow direction (D 3 ) parallel to the sheets ( 2 ).  
   
   
       11 ) A feed unit as claimed in  claim 10 , wherein the first supporting member ( 16 ) is located at a first lateral wall ( 12 ) of the stack ( 4 ), and the nozzle ( 23 ) is positioned facing a second lateral wall ( 25 ) of the stack ( 4 ) perpendicular to the first lateral wall ( 12 ).  
   
   
       12 ) A feed unit as claimed in  claim 11 , wherein the adjustment direction (D 2 ) is perpendicular to the first lateral wall ( 12 ) of the stack ( 4 ), and the blow direction (D 3 ) is perpendicular to the adjustment direction (D 2 ) and to the second lateral wall ( 25 ) of the stack ( 4 ).  
   
   
       13 ) A feed unit as claimed in  claim 1 , and comprising a stop member positioned contacting a third lateral wall ( 13 ) of the stack ( 4 ) on the opposite side to the first supporting member ( 16 ).  
   
   
       14 ) A feed unit as claimed in  claim 1 , and comprising a number of second supporting members ( 11 ) located in a fixed position at the withdrawal opening ( 5 ) and perpendicular to the feed direction (D 1 ) to reduce the passage section of the withdrawal opening ( 5 ) and retain the sheets ( 2 ) in the stack ( 4 ) inside the hopper ( 3 ).  
   
   
       15 ) A feed unit as claimed in  claim 14 , and comprising three second supporting members ( 11 ) equally spaced along the third lateral wall ( 13 ) of the stack ( 4 ); and two second supporting members ( 11 ) located along the first lateral wall ( 12 ) of the stack ( 4 ) parallel to and opposite a third lateral wall ( 13 ); a first supporting member ( 16 ) being located at the first lateral wall ( 12 ) of the stack ( 4 ) and between the two second supporting members ( 11 ).  
   
   
       16 ) A feed unit as claimed in  claim 1 , wherein the position of the second supporting members ( 11 ) is adjustable.  
   
   
       17 ) A feed unit as claimed in  claim 1 , wherein the adjusting member ( 17 ) comprises a motor to move the first supporting member ( 16 ) in the adjustment direction (D 2 ).  
   
   
       18 ) A feed unit as claimed in  claim 17 , wherein the adjusting member ( 17 ) comprises a sensor, which controls the motor and determines the actual size and/or arrangement of the sheets ( 2 ) located close to the withdrawal opening ( 5 ).  
   
   
       19 ) A feed unit as claimed in  claim 1 , wherein the pickup device ( 6 ) comprises a wheel ( 8 ) rotating about a respective central axis ( 9 ); and at least one suction pickup head ( 10 ) fitted to the wheel ( 8 ) to move cyclically along an endless path and through a loading station, where the pickup head ( 10 ) engages the withdrawal opening ( 5 ) of the hopper ( 3 ) to withdraw a respective sheet ( 2 ), and through a follow-up unloading station, where the pickup head ( 10 ) feeds the sheet ( 2 ) to the packing line.