Patent GB-727044-A (GB)
Title: Improvements relating to apparatus for tipping-off sealed envelopes of electric lamps and the like
IPC: H01J9/40
Filed: 1952-05-05
Abstract: 727,044. Sealing electric lamps and like devices. BRITISH THOMSON-HOUSTON CO., Ltd. May 5, 1952 [May 5, 1951], No. 11296/52. Class 39 (2). Apparatus for sealing or tipping off the exhaust tubes of electric lamps, radio tubes &c. while connected to an exhausting pump associated with a turret machine, is provided with burners 7, 8, Fig. 3, for directing heating flames against a portion of the exhaust tube 1 and means movable in a direction away from the exhaust port 3 of the pump to effect stretching of the heated portion of the exhaust tube by displacement of the envelope 2 of the lamp, the burners being mounted for movement along the exhaust tube and also for rotation about axes normal to that direction, means being provided for rotating the burners and causing them to be re-directed towards the exhaust port 3. The burners 7, 8 are mounted upon connectors 28, Fig. 2, arranged eccentrically at the ends of a pair of hollow shafts 12, 13 rotatably mounted in a saddle 11 which is hinged at 24, Fig. 1, on a slide 14 located within guideways on a bracket 19 at the upper end of a vertical shaft 20. The slide 14 is connected by links 16 to an operating arm 15 controlled by the actuating mechanism of a turret which advances the lamps to a succession of work stations, and the vertical shaft 20 is raised and lowered at predetermined intervals by a similar control means, the bracket 19 being held against rotary movement by a guide post 22 extending down from it and through an aperture in a fixed collar 23. The saddle 11 carries a pair of horizontal baffle plates 4, 5 pivoted in a scissors-like manner on a screw 9 on a forwardly extending lip 10, and normally biased to a closed position by a spring 27 so that adjacent oblique portions at the outer ends of the plates 4, 5 cooperate to form a V-notch 4a. The notch facilitates the separation of the baffle plates when the slide 14 is moved towards the lamp 2, the exhaust tube 1 of the lamp being engaged within the V-notch so that the baffle plates are wedged apart until the exhaust tube is within a circular opening 6 formed by the combination of two adjacent notches in the edges of the baffle plates. The parts that provide the opening 6 are also cupped downwardly, as shown at 4b, Fig. 3, so that they can enter within the re-entrant end of the lamp and provide a heat shield for that part of the glass; this arrangement necessitates the slide 14 and bracket 19 being raised prior to the movement of the slide 14 and saddle 11 towards the lamp. The bracket 19 is next lowered slightly by downward movement of the rod 20, bringing the underside of the baffle plates 4, 5 to bear upon the end of the lamp 2 and thereby tensioning the exhaust tube 1 while being heated by the burner flames which are directed against a portion of the tube 1 located as far as possible 'within the re-entrant end of the lamp. The requisite initial angular direction of the burners 7, 8 is obtained by providing the rearward end of each of their rotatable hollow mounting shafts 12, 13 with an upstanding finger and connecting the two fingers by a tensioned spring 30. Since the baffle plates 4, 5 are carried by the saddle 11, which is hinged upon the slide 14, upward tilting of the saddle is restrained by a tensioned spring 25 connected between the forward ends of the saddle and bracket respectively, a stud 26 on the slide 14 forming a normal stop for positioning the saddle. The glass walls of the heated portion of the exhaust tube are drawn in under the downward pull applied by the baffle plates 4, 5 and by the pressure of the flames, and the rod 20 continues to lower the bracket 19 and saddle 11 until a laterally extending arm 36 clamped on the rear end of the hollow shaft 12 comes against a roller 37 on a post 38 upstanding from the fixed collar 23, whereupon the shaft 12 is turned about its axis, and a lateral tooth 31 clamped thereon in engagement with a similar tooth clamped on the shaft 13 imparts an opposite rotation to that shaft, with the result that the burner flames are re-directed higher up the exhaust tube which is thereby severed and sealed off. Due to the eccentricity of the burners 7, 8 relative to the axes of the hollow shafts 12, 13 the partial rotation of the two shafts brings the burner flames closer to the exhaust tube to effect the final severing and sealing of the latter. A pair of fixed arms 39, 40 extending from the saddle 11 and above the outer edges of the baffle plate 4, 5 prevent displacement of the plates when the apparatus is moved downwardly to stretch the exhaust tube. Specifications 543,079, [Group XL], and 679,795 are referred to.