Apparatus for feeding packaging machines with stacks of sheet material

Apparatus for feeding packaging machines with stacks of substantially flexible sheet material which are arranged mutually side by side on a supporting means in a manner so as to form superimposed layers separated by supporting trays which have, on their upper face, raised portions which define a space between said supporting trays and each of said stacks, said apparatus comprising a unit for the removal and transfer of said stacks of sheet material from said trays which includes a first frame which is provided with a pair of horizontal parallel beams mounted on uprights and a horizontal cross member slidably mounted between said horizontal beams, said first frame defining an area for accommodating said stacks of sheet material above which said cross member is horizontally movable, said unit further comprising a first sleeve slidably mounted on said cross member and a second sleeve connected to said first sleeve in which is slidably mounted a substantially vertical beam, said unit further comprising a head which is connected to said vertical beam at a lower end thereof, said head comprising a grip element for a stack which is constituted by at least one pair of horizontal tines mutually arranged parallel and distanced apart, and a presser element rotatably mounted above said pair of horizontal tines, said tines being positionable in said space defined between said supporting trays and said stacks, and said tines defining free ends which are provided with optical empty space sensors for sensing said space and for providing an enabling signal, upon said sensing, for the insertion of said tines into said space, said presser element being rotatably positionable between a raised upper non-engaging position and a lowered position in which said presser element is adapted to supply a substantially uniform gripping pressure to a stack between said pair of tines and said presser element, said apparatus further comprising means for removing emptied supporting trays which include an oscillating frame rotatably and vertically slidably mounted on an upright column support arranged laterally to said first frame, said oscillating frame being provided with a suction means for gripping said emptied supporting trays.