Patent GB-428532-A (GB)
Title: Improvements in or relating to the coating of wire or other metallic filamentary material with a viscous liquid like varnish
IPC: B05C3/15
Filed: 1933-11-09
Abstract: 428,532. Enamelling wire &c. PARFITT, A. W., Stafford House, Norfolk Street, Strand, London.-(Adams, A. H. ; 420, Lexing- ton Avenue, New York, U.S.A.) Nov. 9, 1933, No. 31212. [Class 140] In enamelling wire &c. the coating material is continuously delivered at a constant rate per unit length of the wire which is less than the amount which would adhere naturally to the wire if emerging vertically from a bath of compound, is supplied to the wire by a bushing or nozzle through which the wire passes at constant speed, and is finally baked on the wire. The rate of coating may be restricted also at the bushing or nozzle by a restricted orifice, or by applying the compound initially in a stripe to a portion only of the periphery of the wire. Wire from a reel R, Fig. 1, passes under a pulley 3 immersed in a prewetting bath of diluted compound or thinner, through a wiper 18, a coating nozzle 8, and through a restricted opening 15 into a baking oven 4 heated by heating elements 5. The nozzle may consist of a bushing 20, Fig. 5, having a spiral flute 21 cut therein, the compound being applied in stripes through orifices 22 and thereafter wiped around the wire. The spiral flute may have a flat or a curved surface in contact with the wire. A wire spreading brush 30 may be mounted on the nozzle-holder 25 to equalize the coating, and may be of horseshoe shape to facilitate introduction of the wire. Such a brush may be used as the nozzle itself, the compound being introduced into a channel at the roots of the bristles or wires. Alternatively the nozzle may be a bushing or sleeve 40, Fig. 7, completely surrounding the wire, the entrance clearance 41 being just sufficient to allow the wire to pass, and the circular or star-shaped exit clearance 43 being restricted so that the compound introduced at 44 will not pass, even at the restricted rate as delivered, until a definite head of the compound has accumulated in stand-pipe 17, Fig. 1, or until a definite pressure has built up in a pneumatic device. The bushing is provided with washers 46 of wool, felt, &c. separated by oil-resistant cellulose hydrate or rubber washers 47 for the purpose of removing prewetting liquid from the wire. The bushing 40 may also be used in conjunction with a wire-spreading brush. Several such nozzles may be mounted in sockets in a block or plate, or each of the several nozzles may be split into halves which are mounted in two blocks which can be separated to allow knots to pass. The block or plate may form a seal for the oven above. The compound is supplied by a pump to a nozzle rotating above a number of funnels or receptacles arranged in a circle, from each of which the compound may be supplied to a wirecoating nozzle, or to a second nozzle also rotating above a number of funnels or receptacles from which it is supplied to the coating- nozzles. The pump, wire-feeding device, and rotating nozzles are driven at definite relative speeds, e.g. by synchronous electric motors, or by gearing. The proportion of compound delivered to adjacent receptacles or funnels may be varied by providing an adjustable interceptor between them. The wire, between the prewetting bath and the oven may pass through a chamber which is sealed from the outer atmosphere by a rib 13, Fig. 1, dipping into the prewetting liquid. Alternatively the chamber may be sealed by arranging that the rib 13 and the side walls of the trough fit closely around the pulley 3. The coating nozzles, or the supply pipe leading thereto may be heated, e.g. by heat radiated or conducted from the oven. The wiper 18, Fig. 1, may be of spring wire covered with cotton sleeving. Specification 428,595 is referred to.