GB683191A - Improvements in and relating to tipping-off devices for tubular electric lamps - Google Patents

Abstract

683,191. Sealing tubular electric lamps. BRITISH THOMSON-HOUSTON CO., Ltd. April 9, 1951 [July 12, 1950], No. 8184/51. Class 39(ii) In a device for sealing or tipping- off vitreous tubes extending from electric lamps and like devices, more particularly tubular fluorescent lamps, and comprising a floating bearing member which supports the heating means and is movable laterally in order to compensate for misalignment between the heating means and the vitreous tube upon which it is to operate, as claimed in Specification 634,119 means are provided for automatically recentring the floating bearing member, and the heating means mounted thereon, with respect to the housing within which the floating bearing member is located. As shown in Fig. 1 a tubular rod 20 which is slidable vertically within a sleeve 22 is provided at its lower end with a transverse pin 41 to which the lower end of a tensioned helical spring 40 is connected, the upper end of the spring being connected by a wire 42 to a pin 43 at the centre of the floating disc 17, which is supported upon two concentric rings of ball bearings 18, 18<SP>1</SP> mounted in a single retaining ring. Lateral displacement of the disc 17 with respect to the housing 19 is limited by a vertical pin 47 which is attached to a mounting plate 48 secured to the disc 17 and is confined within a locking ring 49 formed on a projection from the housing 19, so that the edge of the disc cannot strike the housing. The tension in the spring 40 is adjusted so that the disc 17 is returned automatically to the central position within its housing 19 when the device is lowered out of engagement with the end of a lamp. The raising and lowering of the sealing device is effected by a piston 24 which is guided vertically within the lower end of the fixed sleeve 22 and acts upon the lower end of the 'rod 20 through an interposed spring 23. The centring device that engages the lower end of the lamp tube when the sealing device is lifted comprises a series of fingers 14<SP>1</SP> each provided with a small heating-jet 44 located below it to raise its temperature to approximately that of the tubular envelope when the latter emerges from an annular oven, the jets being supplied through a ring 45 mounted below a centrally apertured plate 31 and fed through an inlet tube 46. The central portion of the plate 31 is in the form of an inverted funnel to guide the sealing-flames from burners 11, 12 on to the lower end of the exhausting tube. In some instances, e.g. for work of less refinement, the ball bearings may be dispensed with and the kind of operation described obtained by using two flat discs, one bearing against the other.