GB772608A - Improvements in and relating to powder spray devices - Google Patents

Abstract

772,608. Printing. AEROSTYLE, Ltd. July 22, 1955 [May 3, 1954; Aug. 18, 1954; April 5, 1955], Nos. 12837/54, 24106/54 and 9996/55. Class 100(2) [Also in Group XVIII] Set-off, preventing. In a powder spray device a powder extractor is aranged alternately to extract a powder charge from a powder container and to expose the charge to the interior of a mixing chamber in which it is entrained by and disseminated in a jet of air, and passes therewith through a discharge opening. The admission of compressed air to a bore 10, Fig. 1, may be synchronized with the sheet delivery mechanism of a printing machine. When the air builds up a certain pressure it raises a disc 25 of a pilot valve 9 and so passes to bores 11, 14, 20 whence it produces a jet out of a nozzle 13 in a powdermixing chamber 12, passes through a tube 14a to a space 16 so as to raise a diaphragm 3 and jolt the powder in a container 1, and raises a piston 18. The container is preferably transparent. The piston carries a needle 19, at the end of which is a powder extractor having a bore 24. The extractor takes up a charge of powder of a given fixed volume and raises it when the piston is raised so as to bring it in front of the nozzle 13, when the air jet therefrom disseminates the powder and carries it through a discharge opening 29 to apply to a printed sheet. The extractor is interchangeable according to the volume of powder required and its fineness for others of different size or shape, thus extractors may be screw-threaded or annularly grooved, or have a vertical depression communicating with the transverse bore. The piston descends for the next operation by gravity. In another form, the needle moves upwards into the container, and the chamber 12, valve 9, and piston 18 are below the container, the piston being raised by a spring, and lowered by the air. In another form, Fig. 3, six extractors are carried on a hub 34, which by means of a piston 39 and a rod 41 having a forked end 43 engaging studs 44, is rotated in steps of a little less than 60 degrees, the full 60 degrees being completed by a blade spring 46 engaging two of the studs. The uppermost extractor is located in front of the air nozzle. In another form, Fig. 5, the extractor 19 is stationary, and the diaphragm 3 is alternately lowered by a spring 67 and raised by air from the nozzle 13 so that the bore 24 is brought into communication with the container 1 and the mixing chamber 12a respectively. In another form, Fig. 6, the diaphragm 3 is loaded downwards by a spring 83 and vibrates when air is introduced through tubes 14a and ducts 79. A tube 70 rests on the diaphragm by means of springs 73, and as the diaphragm vibrates, powder enters the tube from the bottom and rises to a higher level than outside the tube, even overflowing when the powder outside the tube is as shallow as 1/16 inch. The extractors may be operated by mechanical linkage or electromagnetically under control of the press.