GB676961A - Improvements in and relating to apparatus for sealing-in discharge lamp cathodes - Google Patents

Abstract

676,961. Discharge lamps. BRITISH THOMSON-HOUSTON CO., Ltd. Jan. 22 1948 [Jan. 22, 1947], No. 2012/48. Class 39 (i). [Also in Group XI] A discharge lamp electrode 13 is sealed into the end of a short vitreous tube 23, the pinch being formed directly on the support wires, thus forming an end portion for subsequent attachment to the main portion of the envelope. The operation is carried out in a head 1 of a multi-head machine, the assembly being mounted during indexing through a group of work stations A. The exhaust tube 4 is inserted into a longitudinal opening in a holder 5 and rests on an adjustable hollow stop 6. The lead-in wires 14, 15 of the electrode 13 are then threaded down longitudinal openings on either side of the exhaust tube, resting on adjustable stop rods 18, 19 in the same holder 5, which comprises two halves 5<SP>1</SP>, 5<SP>11</SP> held closed by springs 10, 10<SP>1</SP> extending between one head and the next. Finally, the envelope 23 is placed in position, resting on a stop plate (not shown). Rotation beyond stations A to the next station B releases a shaft 32 from restraint, allowing rotation under the action of springs 41, 42 of double-throw cranks 38, 39 which close successively two pairs of jaws, 26-27 clamping on the envelope 23 and 28-29 clamping on the lead-in wires 14, 15. At this station the first of a set of burners 49 or 49<SP>1</SP> mounted in pairs on manifolds 51 or 51<SP>1</SP> is moved into operation by similar mechanism to that disclosed in Specification 223,204, [Class 39 (ii)], while a centring rod 53 held in an upper position by a spring arrangement 55, 59 is moved downwards by an arm 57 on an actuating rod 64 into engagement with the electrode 13, being held thus by the same spring. A shield 52 protects the mechanism from the heat of the burners. At the following group of stations C more intense heat is applied, whereby the envelope begins to fuse, jets of air being directed upwards through holder 5 whose pressure and cooling effect maintain a passage through exhaust tube 4. At station D a pair of jaws 68, 69, Fig. 8, clamp together to form the pinch, while a mandrel 67 slides upwards to maintain the exhaust tube passage, the pinch being rounded out by a hot-air jet. At the final work station, after several annealing stations, the centring rod 53 is raised out of engagement with the electrode, rollers 84<SP>1</SP> engage a cam causing halves 51 and 5<SP>11</SP> of the holder to separate, and the jaws 26-27 and 28-29 once more constrained to open, permitting removal of the assembly. The centring rod 53 may be swung to one side if necessary.