Powder dispensing apparatus

Claim 1

In an apparatus for dispensing a powder-like material by gravity on a workpiece with a minimum contamination of the immediate environment; said apparatus comprising a substantially horizontally disposed tubular body having a single elongate slot through a bottom portion thereof; said slot extending through said tubular body substantially perpendicular to its central longitudinal axis; conveying means movable within said body for moving said powder-like material over said slot enabling gravity flow therethrough; said conveying means comprising a flexible conveying device which is movable through said tubular body and a plurality of flights fastened in spaced relation on said device for engaging and moving said powder-like material along said tubular body and over said slot enabling said dispensing therethrough with substantial uniformity; said slot having an elongate dimension disposed substantially parallel to said central longitudinal axis and having a substantially rectangular effective discharge area; the improvement in which said tubular body is defined as a pipe made of a resilient material and has said slot extending through said bottom portion thereof and further comprising means for changing said discharge area enabling controlled dispensing of said powder-like material through said slot; said means for changing said discharge area comprising, a pair of slits extending through the lower portion of said pipe in spaced parallel relation perpendicular to said axis, said slits coinciding with opposite ends of said slot and extending approximately to a diametral plane through said pipe, said slot and slits defining a pair of substantially quarter-cylindrical portions of said pipe on opposite sides of said slot, and means for urging at least one of said quarter-cylindrical portions relative to the other by applying urging forces thereagainst within the elastic limit of said pipe and thus provide temporary distortion thereof to enable changing said effective discharge area and thereby enable controlled dispensing of said powder-like material through said slot.