GB536755A - Improvements in electric lamp making machines - Google Patents

Abstract

536,755. Sealing gas filled electric lamps and discharge devices. BRITISH THOMSONHOUSTON CO., Ltd. May 27, 1940, No. 9275. Convention date, May 26, 1939. [Class 39 (ii)] [Also in Group XXIII] A turret machine for exhausting, gas filling, above atmospheric pressure, and sealing envelopes having vitreous exhaust tubes, has a number of heads each of which comprises an exhausting and gas filling port and mechanical means to pinch and seal the tube. Current is supplied to the pinching means to heat part of the tube during a portion of the rotation of the turret. The pinching means are actuated to seal the tube whilst hot and disengaged therefrom after subsequent cooling. At station A, a lamp 10 is inserted in a holder with its stem in the exhaust port. The holder 27 is secured to an arm 28 which at station is depressed against a spring 32 by a fixed roller 36 engaging a stud 35 and an arm 42 is rotated to compress a rubber seal 45 about the exhaust tube 19 which, with the lamp, is now in its lowest position. The turret carries round the upper portion 46 of a valve which, at station B, admits vacuum to the exhaust port and in subsequent stations flushes the lamp with nitrogen and repeats these processes finally flushing with argon, exhausting and filling with argon, preferably above atmospheric pressure. Between stations B and C tipping jaws 21, 22 are permitted to close upon the exhaust tube, a spring 72 maintaining the pressure. Each jaw comprises a thin ribbon of metal, such as nickel-chromium alloy, backed by a lava block 107 and secured to fingers mounted on an insulating block 67 pivoted at 68 on one of a pair of arms 69, 70 which may be separated by toggle linkage against the action of the spring 72. A fixed commutator 82 cooperates with brushes carried around by the turret to supply current at station C to a transformer 96, the primary circuit comprising a switch 99 and a rheostat 95 and the secondary circuit the jaws 21, 22. Heating proceeds until, at station F, the tube has softened and the jaws under the spring pressure have made the seal. Current is cut off by switch 99 actuated by a plunger with which a bolt on the arm 70 engages as the jaws close. At the same time the lamp and its support rise, the jaws rocking about the pivot to improve the seal, and reduce to a thin neck a lower portion of the exhaust tube. At station G the commutator disconnects the transformer and cooling takes place. At station H the exhaust port is opened by the arm 108. In moving to station J a cam causes the tipping jaws to open and the lamp is removed by hand.