Automatic handling and aeration of a stack of paper sheets

A method of handling and aerating a work stack of rectangular paper sheets in connection with use of the paper sheets in a printing facility, wherein said work stack comprises a top portion of paper sheets of a basic stack of paper sheets, the method comprising the steps of:

• providing an automated device comprising first and second gripping devices each provided with first and second mutually opposed fingers adapted to move towards and away from one another so as to be able to grip and release said work stack between them, each gripping device being adapted for having at least four degrees of freedom;
• inserting said first finger of said first gripping device into said basic stack such that a gap is created between the bottom paper sheet of the thus defined work stack and the top sheet of the rest of the basic stack and placing the first finger of said first gripping device at or near a first corner of said work stack and inserting said first finger of said second gripping device into said gap and moving said first finger of said second gripping device away from the first finger of said first gripping device and toward a second corner of said work stack, said first and second corners being located on the same edge of said work stack such that both said first fingers abut said bottom sheet, wherein said first finger of said first gripping device has a sharp leading edge to allow insertion thereof into said basic stack without damaging the edges of the paper sheets;
• lifting and rotating said first and second corners of said work stack by lifting said first and second gripping devices and rotating said first and second gripping devices in first, mutually generally opposed directions such that the portion of said work stack located between the two gripping devices forms an upwards concave body;
• gripping said work stack by moving said second fingers into contact with the top sheet of said work stack;
• and
• rotating said first and second gripping devices in second directions generally opposed to said first directions such that said top sheet is stretched between said gripping devices to achieve a form that is less upward concave than the form of said bottom sheet and preferably to achieve a generally plane form.