Patent GB-693416-A (GB)
Title: Improvements in and relating to methods of and apparatus for coating hollow glassware
IPC: H01J9/20
Filed: 1951-12-05
Abstract: 693,416. Coating electric lamp bulbs internally: burners modified for special purposes. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 5, 1951 [Dec. 12, 1950], No. 28521/51. Class 39 (ii) and 75 (i) In order to, prevent the deposit and collection of ash upon a burner that is employed in the burning of a fume producing material such as ethyl silicate, in the presence of air or oxygen within an electric lamp bulb or other glass article to produce a layer of minute light-diffusing particles on the interior surface thereof, a jet 27 of ethyl silicate issuing from a central nozzle 26 is atomized by directing opposed jets 29 of oxygen or other suitable combustion-supporting gas upon it from nozzles 28 at opposite sides, whereupon it assumes the form of a flat fan-shaped spray 25 which is ignited and burned in a free space at a point removed from the nozzles 26, 28, by burning gas jets 30, 30 issuing from a pair of opposed burner nozzles 31, 31. Further, in order to prevent the deposition of a non-adherent layer of soft silica particles on the ends of the liquid fuel nozzle 26 and the oxygen jet nozzles 28, a low velocity cleaning, and preferably also cooling, jet 45 of a substantially inert gas such as air or nitrogen is directed upwardly along the exterior of the liquid fuel nozzle 26, the velocity of the jet 45 being such that it does not interfere with or disrupt the directional character and atomizing effect of the oxygen jets 29 from the nozzles 28. The aforesaid nozzles are respectively located at the extremities of nozzle tubes or pipes 32-34 which are mounted and supported in a block 35, the oxygen tubes being interconnected within the block by a passage 36 and the two gas-fire nozzle tubes 34 by a passage 37. These passages are connected by pipes 38, 39 respectively to passages 40 and 41 which extend longitudinally within a burner support 14, Fig. 1, and are connected at their lower ends to supply pipes 42 and 43. The cleaning jet 45 is discharged from a short tube 46 concentrically surrounding the centre nozzle pipe 32 and connected at its lower end, within block 35, to a series of passages or apertures 50 and an air supply pipe 49. The air supply is at a pressure of about one to two pounds per square inch: The burner support is reciprocated vertically relative to the bulb 6, the neck of which is fitted over a metal or refractory collar 5 on a sleeve 4 formed with a flange 11 and supported in a rotatable manner by a stationary bracket 3. Rotation is imparted to the sleeve 4 by a belt-driven pulley 8, and the burner support is reciprocated by a cam-operated lever 16 connected by a link 18 to a collar 19 on its lower end. As shown in Fig. 1 the burner head 13 with its supporting block 35 is mounted in a tilted position, being inclined downwardly at an angle of about 45 degrees to the supporting tube 14, so that the main stream of the fume of silica particles. from the burner is directed on to the side wall of the bulb and only the spill is deposited on the inner top surface of the bulb. Such differential effect is enhanced by heating the top of the bulb by a gas fire 54 while the side wall is cooled externally by a high-pressure aircooling jet 55. Specification 653.370 is referred to.