GB447720A - Improvements in and relating to the manufacture of electric lamps and similar devices - Google Patents

Abstract

447,720. Thermionic valves. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London. Sept. 27, 1935, No. 26782. Convention date, Sept. 28, 1934. [Class 39 (i)] [See also Group XI] In a method of sealing together the bulb and stem tube of a radio tube, the bulb 10 is held in a fixed position with the stem tube 13 supported therein, and the neck of the bulb and end of the stem tube are heated until they are fused together, whereupon the sealed parts are surrounded by a mould which has its bottom portion separated from the bottom of the seal, the support 12 next being removed from the stem tube and air blown through the exhausting tube 14 into the bulb so that the seal is forced against the bottom of the mould, moving the stem tube longitudinally. The bulb 10 is supported by a holder 11 which engages it at three points and is pressed downwardly by a weight 68 on a sliding rod 69. The mount support 12 is secured to a hollow spindle 50 which receives the exhausting tube 14 and leading-in wires and is lifted into position by a cam 51 and held raised by a horizontal sliding plate 47 engaging a flange 48. The mould is in two half-portions 19, 20 respectively, at the lower ends of arms 17, 18 which are pivoted at 21, 22 and connected to a link system actuated by a slotted cam 38 and lever 37 so that they close upon the fused and still soft seal. The mount support 12 is then dropped by the withdrawal of the sliding plate 47 which is connected to a lever 57, 61 and actuated by the vertical movement of a bolt 59 at the upper end of a piston 60 connected to a camoperated lever 55. The piston 60 is provided with a transverse passage 66 which, at the end of the upward movement of the piston, establishes connection between a pipe 64 from a compressed air supply and a pipe 65 terminating in an aperture in the cam surface 51 in alignment with the hollow interior of the spindle 50. The soft glass around the seal is thus forced against the bottom portions of the parts 19, 20 comprising the mould. The link system controlling the movement of the arms 17, 18 carrying the parts of the mould is provided with a helical spring 39 connecting two rods 31, 34 to take up excess movement of the actuating lever 37 and rod 34 after the moulding parts have come together. The apparatus is preferably used in conjunction with a sealing machine of the type described in Specification 232,953, [Class 39 (ii)], the gas burners 45<1>, 46<1>, Fig. 1, being mounted either on the sealing machine or on the apparatus described.