GB829133A - Improvements in or relating to pumping machines for the manufacture of electric lamps and like devices - Google Patents

Abstract

829,133. Making electric lamps and like devices. GENERAL ELECTRIC CO. Ltd. June 20, 1958 [March 22, 1957], No. 9504/57. Class 39(2) A machine for exhausting and filling with gas, sealed envelopes, especially electric filament lamps, through a tubulation, comprises a series of heads each supporting a lamp and including a valve biased to closed position from which it is displaced by the insertion of the exhaust tube in the head, means for detecting a lamp with a leaky envelope and means controlled by the detecting means for ejecting such a lamp from the head, whereupon the valve closes, preferably by gravity. The heads may be carried by a continuously moving machine or may be indexed to successive positions. The exhaust tube 13 of the lamp 14 is inserted in a gland 11 carried by an externally threaded body member 7 on which is mounted a threaded cylindrical cap 12 having a thrust bearing 15 so that screwing up of the cap 12 compresses the gland 11 and causes it to grip the tube 13. Insertion of the tube 13 into the gland 11 raises a valve stem 23 sliding in a tube 21 connected to a vacuum pump, upward movement of the stem 23 being limited by a stop 26. A rotatable table carries a series of heads each provided with a gland so that the lamps are successively connected to a vacuum pump via the tubes 21. A leak detector is provided consisting of a closed container divided by a flexible diaphragm into two chambers connected respectively to the vacuum pump and, in turn as the table rotates, to each of the tubes 21. Imbalance between the two sides of the diaphragm operates a micro switch to interpose an arm 31 in the path of an arm 20 on the cap so that rotation of the table causes unscrewing of the cap and release of the tube 11, the valve automatically dropping to close the aperture in the gland 11. To prevent overheating of the exhaust tube during pumping, a cooling chamber 33 is arranged around the tube through which passes a draught of cooling air. On further rotation of the table, the pumping heads are connected to one or more sources of nitrogen for flushing the bulbs. In a modification in which the exhaust tubes are supported with the bulb uppermost, the valve stems are positively biased to closing position and means are provided for releasing the exhaust tube of a leaky bulb from the gland and removing the bulb from the pumping head.