Powder feeding apparatus and method

摘要

A powder-feeding method and apparatus according to which it is possible to provide one or a plurality of powder-feeding flows in which the powder is fed at a substantially constant rate which is of relatively small magnitude. A cone of powder is maintained substantially centrally of a disc which is rotated at a constant speed. A coarse scraper blade extends inwardly across the periphery of the disc into the cone of powder thereon substantially radially with respect to the disc so that the coarse scraper blade removes some powder on one side of the blade while leaving on the disc on the other side of the blade a layer of powder the depth of which is determined by the distance between the bottom edge of the coarse scraper blade and the top surface of the disc. Into this layer there projects a precision scraper blade the bottom edge of which is closely adjacent to the upper surface of the disc, so that by way of this precision scraper blade it is possible to remove from the layer of predetermined depth powder which drops from the edge of the disc at a substantially constant rate capable of providing a precision powder feeding rate of relatively small magnitude.