GB1189634A - Flame Spray Gun having a Powder Feed Device. - Google Patents

Abstract

1,189,634. Pneumatic conveyers. METCO Inc. 21 Sept., 1967 [29 Dec., 1966], No. 42922/67. Heading B8A. [Also in Division B2] A flame spray gun includes a powder feed device in which powder is introduced into a stream of carrier gas flowing at a substantially constant rate through a conduit, and a pressuresensitive gauge responsive to the change of pressure along the conduit past the point of powder introduction. The powder may be introduced into the carrier gas stream in a mixing chamber 39, the powder being fed to a feed chamber 33 from hoppers 1, 20 and from the feed chamber to the mixing chamber through an intermediate chamber 35 by a rotatable cylinder 36 formed with peripheral recesses 37. The angle to the horizontal of a line joining the highest point 38 of intersection of the feed chamber 33 and the intermediate chamber 35, and the lowest point 40 of intersection of the intermediate chamber 35 and the mixing chamber 39 is less than the angle of repose of the powder. The carrier gas enters the mixing chamber at 42, entrains the powder, and carries it out through a tapering passage 50 to a flame spray gun (61), Fig. 7 (not shown). The pressure throughout the apparatus is equalized by gas passing through a line 45, a tube 48, passages 18, 17, a hollow rod 4 and apertures 19. A pressure-sensitive gauge 52 may be connected into the carrier gas inlet passage 41, or a differential gauge such as a manometer may be connected to the carrier gas conduit downstream of the passage 50. The pressure drop in a conduit may automatically control the rate of rotation of the cylinder 36 by means of a diaphragm (57, Fig. 7) acted on at each side by the pressure at a different point in the carrier gas flow path, and having fixed thereto a contact (62) of a rheostat (63) connected in the circuit of an electric motor 53 driving the cylinder 36. In a modification (Fig. 8, not shown), the cylinder 36 is dispensed with, a nozzle (66) being located beneath the surface of a pile of powder within the intermediate chamber (35) and gas issuing from the nozzle blows powder into the mixing chamber (39) at a rate of flow regulated by the back pressure in the conduit (60) leading to the spray gun. The hoppers 1, 20 supplying powder to the feed chamber 33 include valves 26, 13, the valve 13 closing automatically when an air tight cap 7 is removed for replenishing the supply of powder in the hopper 1.