Air floatation bottom feeder

Claim 1

A sheet feeding device adapted for feeding sheets individually from the bottom of the stack of sheets comprising: means forming an air plenum adapted for connection to a source of pressurized air, a sheet support plate associated with said plenum, said sheet support plate having a plurality of fine bores formed therein adapted for communication with the interior of said air plenum for passage of air from said air plenum through said bores, said bores terminating at the sheet support surface of said plate in sharp edged orifices, passage of air from said plenum through said bores producing jets of air adapted for penetration through the bottom sheet in the stack, passage of air through the bottom sheet in the stack causing the air jets to be diffused to provide an air cushion between the bottom sheet in the stack and the sheets immediately thereabove; sheet feeding means mounted adjacent said sheet support plate adapted for contact with the bottom sheet in the stack for feeding the bottom sheet therefrom; a front edge abutment plate associated with said sheet support plate, said abutment plate being spaced from said sheet support plate to allow passage of sheets separated from the stack to pass beneath said abutment plate; adjustable side guides adapted for cooperation with said abutment plate and said sheet support plate, said side guides being adjustable to a plurality of positions to accommodate a plurality of sheet stack sizes, said side guides having outwardly projecting flanges thereon overlying said sheet support plate, the outer periphery of the lower surface of said flanges having sealing material attached thereto to provide fluid tight engagement between said flanges and said perforated plate, said side guides being formed to provide a space between the lower edge of the side guides and said sheet support plate, air passing through the bores in said sheet support plate beneath said flanges escaping from beneath said side guides into the sheet stack on said sheet support plate for riffling the lower sheets in the stack to increase the air cushion effect between the lower sheets in the stack.