Apparatus for feeding sheets

Claim 1

An apparatus for feeding a single sheet from the bottom of a stack of sheets comprising: a magazine to receive a stack of sheets having a bottom support and upstanding walls, the bottom support being provided with an opening therein through which the lowermost sheet can be removed, wherein the opening is along one edge of the stack of sheets; at least one suction nozzle below the magazine opening which retracts downward when engaging the sheet; a means for blowing compressed air along a portion of the edge and bottom of the stack of sheets to separate the edge of the lowermost sheets from the stack prior to contact with the suction nozzle; at least one curved vacuum surface below the magazine and the suction nozzle; a first pivot arm attached to the suction nozzle; a second pivot arm attached to the vacuum surface; a sheet receiving and feeding means adjacent and below the magazine for receiving and feeding the sheet to a station for performing subsequent operations thereon; a first activation means for pivoting the first pivot arm to (i) raise the suction nozzle to engage the bottom surface of the lowermost sheet and subsequently (ii) lowering the suction nozzle to engage the bottom surface of the sheet with the vacuum surface; a second activation means for pivoting the second pivot arm to (i) move the vacuum surface towards the receiving and feeding means for receipt of the sheet, and (ii) return the vacuum surface to the position below the suction nozzle and magazine; a first vacuum means for applying vacuum to the suction nozzle; a second vacuum means for applying vacuum to the vacuum surface; wherein the suction nozzle comprises: a hollow elongated member having an open upper end and a closed lower end, the member being mounted near the end of the first pivot arm; a piston member slidably and sealingly mounted within the chamber of the member; a spring retaining means below the piston member for retaining the piston member at the upper end of the chamber; a sucker attached to the piston member, the center of which is in fluid communication with the chamber below the piston member; and wherein the first vacuum means applies vacuum to the chamber below the piston member; whereby when the sheet engages the sucker a vacuum forms in the chamber below the piston member causing the sucker to retract downward.

Claim 2

An apparatus for feeding a single sheet from the bottom of a stack of sheets comprising: a magazine to receive a stack of sheets having a bottom support and upstanding walls, the bottom support being provided with an opening therein through which the lowermost sheet can be removed, wherein the opening is along one edge of the stack of sheets; at least one suction nozzle below the magazine opening which retracts downward when engaging the sheet; a means for blowing compressed air along a portion of the edge and bottom of the stack of sheets to separate the edge of the lowermost sheets from the stack prior to contact with the suction nozzle; at least one curved vacuum surface below the magazine and the suction nozzle; a first pivot arm attached to the suction nozzle; a second pivot arm attached to the vacuum surface; a sheet receiving and feeding means adjacent and below the magazine for receiving and feeding the sheet to a station for performing subsequent operations thereon; a first activation means for pivoting the first pivot arm to (i) raise the suction nozzle to engage the bottom surface of the lowermost sheet and subsequently (ii) lowering the suction nozzle to engage the bottom surface of the sheet with the vacuum surface; a second activation means for pivoting the second pivot arm to (i) move the vacuum surface towards the receiving and feeding means for receipt of the sheet, and (ii) return the vacuum surface to the position below the suction nozzle and magazine; a first vacuum means for applying vacuum to the suction nozzle; a second vacuum means for applying vacuum to the vacuum surface; wherein the suction nozzle comprises: a hollow elongated member having an open upper end and a closed lower end, the member being mounted near the end of the first pivot arm; a piston member slidably and sealingly mounted within the chamber of the member; a spring retaining means below the piston member for retaining the piston member at the upper end of the chamber; a sucker attached to the piston member, the center of which is in fluid communication with the chamber below the piston member; and wherein the first vacuum means applies vacuum to the chamber below the piston member; whereby when the sheet engages the sucker a vacuum forms in the chamber below the piston member causing the sucker to retract downward.