GB474004A - Improvements in and relating to electric lamps or the like - Google Patents

Abstract

474,004. Making stems for electric incandescent lamps. BRITISH THOMSONHOUSTON CO., Ltd. July 9, 1936, No. 19065. Convention date, July 10, 1935. [Class 39 (ii)] In making stems for electric incandescent lamps and similar devices, such as electric discharge devices, a pair of leading-in conductors 13, Fig. 2, are assembled adjacent to the inner wall of a stem tube 10 and on opposite sides thereof, and heat is applied to produce a fused mass of glass closing off the tube and enclosing the leading-in conductors, whereupon the glass mass is clamped about the conductors and the portion 21 between the conductors is compressed to a greater extent than the remainder so as to force the glass thus compressed outward around the conductors. In the example, the lamp stem comprises an exhausting-tube 11 and an arbor 12 which, with the leading-in wires 13, are assembled within the stem tube 10 in an automatic stem machine and carried past a series of fires which fuse together the juxtaposed ends of the stem tube, exhaust tube, and arbor. The assembly is then carried to clamping-jaws which are provided on their inner faces with matrices 17, 18 formed with bosses 19, 20 on their faces. Both sides of the stem press 14 between the leading-in conductors 13 are thereby indented, producing the thin portion 21 and forcing the plastic glass to each side to provide more glass at the parts 30 around the welded joints between the parts 27, 28 of the leading-in conductors. Preferably also the matrix 17 is provided with a projection or lug 22 extending from the upper edge of the boss 19 and arranged to produce an indentation 23, Fig. 2, in line with the exhausting-tube 11. By forcing air into the exhausting-tube a blow-out is produced at the indentation 23 and an exhausting-aperture formed in the stem. In a modification, both matrices are formed with projections, similar to the matrix 17, Fig. 5, and the thin portion of the glass is punched out, so that when air is forced down the exhausting-tube a blow-out occurs at the bottom of the latter. Specification 226,215, [Class 39 (ii)], is referred to.