GB918865A - Spray guns having a fixed electrostatic head - Google Patents

Abstract

918,865. Spray-producers. MACHINES ELECTROSTATIQUES S.A. DE. April 26, 1960 [April 27, 1959], No. 14596/60. Class 69 (3). In an electrostatically operated spray gun, e.g. for paint, a high D.C. potential is applied to a non-rotatable spray head having small spraying orifices and a rotating scraper, the scraper ensuring a uniform distribution of the material to be sprayed and preventing clogging of the orifices. As shown, a gun comprises a metal butt 1, an insulating body 2 and a head 10 containing a scraper 12. In the gun shown in Fig. 1, spray holes 11 are arranged radially in the head and the scraper is driven through an insulating shaft 13 by an electric motor 5 supplied by an L.T. cable 4. Material is sprayed under pressure through the holes 11 and then divided and directed to the object to be coated by the electric field. To regulate the spray, a trigger operated sleeve 14 is slid over the holes, the trigger also operating a switch 9 in the scraper motor circuit. An H.T. electrode 16 prevents dispersion of the electric field and a protection resistance may be inserted between the cable 6 and head 10. In the gun shown in Fig. 3, the spray holes are in the end wall of the head 10. The scraper 12 is driven by the spray material under pressure acting on a helical rotor 18 and the H.T. cable is in communication with the head through a protection resistance 17 and the rotor. Spray material is supplied by the duct 3 and excess is removed by a duct 20, the ducts having valves 21 and 22 under trigger control. In a further embodiment, Fig. 6, similar to that shown in Fig. 3, the H.T. cable is connected through resistance 17 directly to the head and the rotor is of insulating material. The end wall of the head may be provided with forwardly projecting spikes or an electrode having a thin edge 23.