Sheet delivery arrangement having an air-stream sheet retarder

Claim 1

In a delivery arrangement for a sheet-fed printing press for delivering sheets onto a delivery pile, the combination comprising means for supporting a pile of sheets, a conveyor for conveying sheets by their leading edges longitudinally along a sheet delivery path to a position above the pile, a take-off mechanism at the delivery pile synchronized with the arrival of the sheets for taking the sheets from the conveyor and for decelerating the leading edges thereof for depositing them on the pile, a nozzle assembly including spaced fingers defining a series of nozzles spaced edge to edge in a plane, a source of air under pressure for feeding the nozzle assembly, the nozzle assembly being located adjacent the pile below the level of the approaching sheets and extending along the width of the sheets so that laterally spaced jets of air are directed substantially parallel to the underside of each sheet in a direction upstream of sheet movement, a guide plate spaced under the sheet path and extending from the nozzle assembly in the upstream direction tending to confine the jets of air under an arriving sheet, the surface of the guide plate having formed on the surface thereof a plurality of upraised islands laterally spaced from one another so as to be in respective alinement with the fingers between the jets, the islands presenting plateau surfaces at approximately the same elevation above the guide plate and substantially parallel thereto and extending above the plane of the nozzles so that when the sheet is sucked downwardly by the effect of the jets it is drawn to the plateau surfaces in light frictional engagement to apply frictional drag to the body of the sheet while preventing fluttering thereof.