GB486872A - Improvements in or relating to electric incandescent lamps and discharge apparatus - Google Patents

Abstract

486,872. Sealing leading-in wires into glass. ARCTURUS RADIO TUBE CO. Dec. 10, 1936, No. 33957. Convention date, Dec. 11, 1935. [Class 36] A stem assembly for electric incandescent lamps and discharge apparatus, comprises a tubular glass stem, a vitreous mass providing a wall forming a closure at one end of the stem and shaped by pressure normal to the wall, an exhaust tube connected to the wall and forming an opening therethrough, and one or more electric conductors sealed in the wall area between the exhaust tube and stem. The formation of the wall may be effected by supporting the electric conductors 10, Fig. 20, in apertures arranged in a circle in a member 9, and locating the stem tube 13 and exhausting tube 12 coaxially therewith, heat then being directed upon the lower end of the stem tube from adjacent gas burners, so that the stem tube collapses inwardly and the bottom of the exhausting tube is softened, whereupon a plunger 20, Fig. 22, within the member 9 is moved to press upwardly upon the softened glass while a downward pressure is exerted simultaneously upon the exhausting tube 12 by a compression head 44 on a lever 43. Subsequently a reduced heat is applied to the glass wall and a current of air blown down the exhausting tube to clear its lower end and depress the glass around its outlet aperture. The amount of glass forming the seal may be increased by forming a bead of glass upon some or all of the leading-in conductors, these beads being interfused by the application of heat accompanied by pressure from upwardly and downwardly moving compression members to form a fused wall, the surface of which is scalloped and thus increases the surface distance between the wires, as shown in Fig. 11. Alternatively, the mass of glass may be increased by making the exhausting tube of greater diameter, or providing a button of glass on its lower end. The operations may be carried out on a rotary machine around the circumference of which are mounted a series of rotary heads each provided with a pair of resiliently mounted jaws for engaging the flare of a stem tube, together with cam-actuated compression-members.