GB1193252A - Improvements in and relating to Electrostatic Spray Coating Apparatus - Google Patents

Abstract

1,193,252. Spray-producers HENRY W. PEABODY (INDUSTRIAL) Ltd. 6 July, 1967 [6 April, 1966; 12 Aug., 1966], Nos. 15438/66 and 36313/66. Heading B2F. Electrostatic spray coating apparatus comprises a delivery tube 63 having an elongated cavity 64 and having multiple outlet apertures 66 from which the liquid to be sprayed trickles onto an elongated blade 65 of insulating material which is charged to a high electrical potential. The body may be made of polythene. Attachments 71 may be detachably or permanently attached to the tube 63 for spraying into recesses in the article to be coated, the attachmentis comprising a blade with a sharp edge 75 supplied with liquid issuing from apertures 77 in a tube 76 which connects with one of the apertures 66 in the tube 63. The blade 65 comprises an electrically conductive layer of a carbon or graphite loaded synthetic resin 69 between layers of insulating material, the liquid contacting the layer 69 as it flows over the blade. The layer 69 is connected to a source of electrical potential by a similar layer 68 in the body, :a resistor (33) Fig. 1A (not shown) and a lead (31). Alternatively, the spray material may be charged by a wire arranged concentrically or otherwise within the cavity 64, or by a coating of a resistive material on the internal wall of the tube 63. The tube 76 is plugged by a removable plug 78. Longitudinal recesses (not shown) may be formed in the tube 63 to stabilize the flow of the coating liquid; the recesses may be formed at the base of the blade, between the blade and the apertures 66 or the apertures 66 may open into a recess. Some of the apertures 66 may be blocked off for a spray of predetermined width; the blocks may fit or slide over the exterior of the body, surrounding the body except for the blade, or if the apertures 66 open into a recess, the blocks may lodge therein. The blocks may be made of polythene. The tube 63 may be fitted with drain plugs (17, 18), Fig. 1B (not shown). The edge of the blade may be interrupted for coating corrugated or channelled articles. Two blades may be provided on the tube 63. The apertures 66 may be formed as slots. The blade assembly may be oscillated or vibrated to assist distribution and flow of the coating liquid and extend the use of the apparatus to powdered material. The blade may be heated.