ES293557A1 - Coating apparatus - Google Patents

Abstract

An apparatus, suitable for spraying liquid or powdered coating materials, e.g. paint, on to an article such as a chair 1, comprises a rotatable cup-shaped member 28, a paint nozzle 43 for introducing the coating material to the member, a shroud 27 at least partially surrounding the member 28, a high voltage supply to the member 28 to provide an electrostatic field between the member and the chair, which is at earth potential, and a plurality of air jets 53, 54 for directing a convergent stream of compressed air 55, 56 from the shroud 27 towards the chair 1. The member 28 is of ebonite and includes a metal insert 63, and a flat disc 64 joined to an outer cup-shaped portion 65 by three webs 66. The mouth of the cup is tapered to provide a sharp edge at 67. The shroud 27 comprises a rear portion 46 formed with an annular channel 50 into which air is fed from a connector 30, and an elongated slot 51 through which the nozzle 43 projects, and a front portion 47 provided with rings 61 and 58 each containing a plurality of holes, and formed with a generally annular passage 52 and the holes 53, 54 which are inclined in sequence at angles of 5, 8, and 11 to the axis of the revolution of the member 28. Conductive or semi-conductive material is painted on or incorporated in the members 27 and 28 to provide them with a very high electrical resistance and the high voltage supply passes from a cable 36, through a resistor, and through the air motor for rotating the member 28 to the said member itself. The air jets avoid the pattern effect usually associated with electrostatic spray apparatus. The apparatus includes a trigger 24 controlling a microswitch 25 connected by a cable 6 to control equipment 18a mounted on a high voltage radio frequency generator 7, Fig. 7. A cable 9 connects the equipment 18a to valves 19, 20 and 8 which control respectively the paint line 4, the air line 3 for the motor for rotating the member 28, and the air line 29 for the shroud 27.