Patent GB-726811-A (GB)
Title: Improvements in and relating to electric lamps
IPC: H01K3/10
Filed: 1952-11-06
Abstract: 726,811. Making electric incandescent lamps. BRITISH THOMSON-HOUSTON CO. Ltd. Nov. 6, 1952 [Nov. 6, 1951]. No. 27978/52. Class 39 (2). In order to establish a definite pitch in the coiled filament of a completed mount for an electric incandescent lamp having leading-in wires extending longitudinally from.a stem and provided with tie wires which extend laterally from the axis of the stem and are looped about intermediate portions of the leading-in wires, at least one of the leading-in wires is engaged at points on opposite sides of the tie wire and pressure is applied in a direction to effect a spreading apart of the free ends of the leading-in wires, with concomitant stretching of the filament. The mounts 6, Figs. 1 and 2, which are carried around in an inverted position on a conveyer each comprise a stem 5 with leading-in wires 8, 9 extending downwardly therefrom on opposite sides of an arbor 3, which carries lateral supporting wires 10, 11, with their ends looped around the leading-in, wires 8, 9, and a longitudinally extending supporting wire 13 which engages the mid-point of the filament 12. The conveyer is represented by upper and lower pairs of jaws 2 and 1 engaging the exhausting tube 4 and arbor 3 respectively. The stretching operation preferably takes place at a station 7 immediately following that at which the mount 6 is completed, the stretching means comprising a pair of stop or anvil fingers 14, 15 which are retracted initially to one side of the horizontal path of movement of the mount to enable the indexed mount to be halted at the requisite position, while a pair of bending fingers 16, 17 pivotally mounted at the other side of the path of movement of the mount are swung back in a horizontal plane to their wide open position. The stop fingers 14, 15 are secured on a rotatable hub 18, Fig. 4, on a shaft 19 which is clamped to a link 32 having pin-and-slot connection to a lever 31 which is pivoted at 38 and arranged to be rocked by a push bar 30 extending from within the end of a slide 29. A compression spring 33 abuts against the inner end of the push bar 30. The push bar and the slide 29 are connected together by a pin-andslot arrangement 34, 35, Fig. 4, and movement of the slide 29 is effected by rotary movement of a vertical shaft 20 to which is attached a lateral arm 27 arranged to bear against a stop 28 in th top surface of the slide. Rotation of the shaft 20 is effected by the reciprocation of an operating bar 22 pivotally connected to a lateral arm 26 on the lower end of the shaft, thereby causing the stop fingers 14, 15 to swing upwardly to their operative position shown in Fig. 1; an adjustable limiting screw 40 is provided on a rear extension of the hub 18. The bending-finger 16 is pivotally secured within a yoke 44 clamped upon the upper end of the vertical shaft 20 and is located between an adjusting screw 42 and a compressed spring 43, whilst the co-operating bending-finger 17 is similarly located between an adjusting screw 45 and spring 46 in a yoke 47 mounted on the upper end of a shaft 21 arranged parallel with the shaft 20 and rotated in the opposite direction to the latter by interengaging gear wheels 48 and 49, Fig. 5 (not shown), on their lower ends.