GB1005621A - Improvements in or relating to apparatus for electrostatic spray coating - Google Patents

Abstract

1,005,621. Spray-producers for coating recessed articles. K. M. OESTERLE. July 16, 1963 [July 17, 1962], No. 28171/63. Heading B2F. Spraying apparatus 22, Fig. 10, particularly suitable for coating articles 23 having a large recess with a liqud material such as lacquer, comprises a spraying jet, means for generating an electrostatic field between the apparatus and the article to be coated, and at least one rotatable spray member provided with a receiving surface which defines at its centre an opening on the longitudinal axis of the apparatus and which receives the lacquer from the jet and is formed with a spray edge, means being provided for varying the ratio between the amount of lacquer impinging on the surface and sprayed from the said edge and the amount passing through the opening. In the embodiment of Fig. 1, lacquer is sprayed from a nozzle 2 and part of it passes through a central aperture 4 around a guide cone 5 in a disc 3. The disc 3 is provided wtih openings 7 and together with a cone 6 is rotatably mounted on the supply tube 1 of the nozzle 2. The lacquer collected by the inner receiving surface of the disc 3 passes under centrifugal force through the openings 7 and is driven over a layer 8 of electrically conducting material and away from a spraying edge 9. An electrostatic field is generated between the layer 8 and the article. The ratio of material passing through the opening 4 to that passing through the openings 7 may be altered by axially adjusting the position of the cone 6 and the disc 3 on the tube 1. In the embodiment of Fig. 2 (not shown), the cone and the plate 3 are fixed and a diaphragm having a hole therein is adjustable between the nozzle and the opening 4, and in Fig. 4 (not shown), the cone 6 and plate 3 are rotatable and axially adjustable and the supply tube is parallel to a shaft which supports the cone and the plate. Fig. 5 depicts a similar apparatus in whch lacquer from the receiving surface is sprayed from the edges 9a of blades 14 produced by incisions in the disc 3. The lacquer reaches the blades through openings 7a in the cone 6 and the blades 14 also provide an air draught. The blades may be provided with pointed teeth, Figs. 6, 6a (not shown). A greater volume of liquid may be sprayed using three interconnected discs 4a, 4b and 4c, Fig. 9, which are rotatable and have three different diameters and central openings which also differ in diameter. The amount of coating material supplied to the spray edge may be varied by adjusting the angle of the spray emerging from the nozzle.