GB471099A - Improvements in and relating to the manufacture of electric lamps - Google Patents

Abstract

471,099. Securing bases to electric incandescent lamp bulbs. BRITISH THOMSON-HOUSTON CO., Ltd. March 15, 1937, No. 7546. Convention date, March 13, 1936. [Class 39 (ii)] In connecting an electric lamp bulb 10 containing a filament 16 to a base 20 which has an interna diameter slightly large than that of the bulb neck 11, the base, provided with a ring 26 of cement on the inside thereof, is placec over the neck of the bulb and the bulb is adjustec relatively to the base unti the light source is definitely located with respect to a portion of the base, whereupon the base is heated to bake the cement therein while maintaining the end portion of the base adjacent the bulb relatively cool to harden the cement and prevent its flowing out through the end of the base. In the example, the metal base shell 21 is provided with an outwardly turned integral flange 25 which, during the capping, is located within an annular seating 32 in a massive metal supporting-plate 30 and held in position by one or more radially movable spring members 33. During the baking operation the cement 26 expands and tends to flow down between the base shell 21 and bulb neck 11, but is hardened as it approaches the end of the base shell, which is kept cool by the comparatively heavy metal plate 30 in contact with the flange 25. For accurately locating the base, the bulb 10 is held by vacuum in a movable chuck 28, the internal diameter of the base shell 21 being slightly larger than that of the reduced neck portion of the bulb to permit rocking and shifting of the bulb in the base shell while current is passed through the leading-in wires 14, 15 to project an image or images of the filament 16 upon a screen. After the cement has hardened, the leading-in wires 14, 15 are trimmed and soldered to the base shell 21 and eyelet 24 respectively. One leading-in wire 15 is preferably extended at 18 into a hollow tip 19 at the end of the bulb, as described in Specification 433,033, in order to locate the filament 16 in a predetermined position in the bulb. In a modification, the bulb is of cylindrical form with an enlarged bulbous or spherical neck. Bases not provided with a flanged front end, for example those with bayonet pins, may be cooled at the front end by means of an air jet or by attaching thereto a metal clip of sufficient mass to have the necessary cooling effect.