US Patent 7832411 Cigarette manufacturing method

A cigarette manufacturing method and machine, whereby a shredded tobacco stream is fed along a channel extending through at least one carding unit and having at least one output portion closed by a suction conveyor belt and for feeding a mat of tobacco onto the suction conveyor belt; and the shredded tobacco stream is cleaned, upstream from the carding unit, to remove relatively heavy parts, such as lumps of tobacco and/or woody tobacco parts and/or any foreign bodies, from the shredded tobacco stream.