GB834424A - Method of manufacturing electric lamps - Google Patents

Abstract

834,424. Incandescent lamps. PATENTTREUHAND - GESELLSCHAFT FUR ELEKTRISCHE GLUHLAMPEN. June 6, 1956 [June 16, 1955], No. 17505/56. Class 39(2) In the manufacture of electric incandescent lamps, the filament-supporting leading-in wires 1 and a metal exhaust tube 7 are sealed within the neck 9 of a glass bulb 3 by the application of heat and pressure, and the bulb is exhausted and, if necessary gas-filled by way of the tube 7, whereupon the glass sealing-pinch is subjected to a further heating during which the exhausting tube is' removed while at the same time the lamp is sealed by a second pinching. The operations may be carried out in a rotary turret or a chain conveyer machine provided with suction heads 6 each of which holds a bulb 3 and lowers it upon a mount comprising a filament 2 supported by leading-in 'wires 1 which are held by gripping-tongs 5 and a co-operating central blade 10 provided with a hole 12. Downward movement of the suction head 6 brings the neck 9 of the bulb down on to the gripping tongs 5 and is continued until the upper end of the metal exhaust tube 7 (held by means not shown) is pushed upwardly through the hole 12 in the middle blade 10 and into the bulb. The bulb neck is next subjected to heating by jets from a pair of oppositely disposed burners 8 which are also formed as clamping jaws arranged to be closed automatically, the flames being extinguished during this movement and relighted by igniting flames when the jaws again open. The jaws operate to seal the leading-in wires in position and pinch the glass of the bulb neck around the exhaust tube. The lamp bulb is next exhausted by a vacuum pump connected to the tube 7 and may be filled with gas, after which the burners 8 are relighted to heat and soften the glass seal, the burner flames being directed particularly upon the metal exhaust tube, whereupon the tongs 5 are slowly lifted to withdraw the bulb from the tube and the clamping burners are again pinched upon the bulb neck to seal it hermetically. The exhaust tube is preferably made of copper or a heat-resistant steel, with 'an internal diameter of about 2 mm. and a wall thickness of about 0.5 mm. An initial coating of glass, enamel, or borax which has a lower melting-point than the glass of the lamp bulb, may be provided on the exhaust tube to facilitate its subsequent withdrawal. Separate burners and clamping jaws may be used. For gas-filled bulbs the exhaust tube may be provided with two separate channels through one of which the gas can be blown into the bulb while air and surplus gas escapes through the other. In this manner flashlight lamps containing a combustible material may be filled with oxygen without the necessity for a previous evacuation.