Patent GB-390266-A (GB)
Title: Improvements in apparatus for sealing vitreous envelopes
IPC: H01J9/32
Filed: 1931-12-18
Abstract: 390,266. Discharge apparatus. M-0 VALVE CO., Ltd., Marconi House, Strand, London, EDEN, C. G. and SMITHELLS, C. J., c/o General Electric Co., Wembley, Middlesex. Dec. 18, 1931, No. 35120. [Class 39 (i).] In a machine for making vitreous envelopes for discharge tubes, provided with portions sealed together by the method described in Specification 369,349, the open lower end of a tubular vitreous member 1, Fig. 1, and the flared upper end 4 of an exhaust tube are soitened and compressed together upon an annular former provided with a hollow centre adapted to receive the main portion of the exhaust tube. The leading-in wires 3 are arranged between the members 1, 4 and sealed in that position. The tubular envelope 1 is received in a chuck 2 at the end of an arm 8 which projects from a sleeve 8a slidably mounted on a spindle 9 and guide spindle 10, the exhausting tube 4 being supported on a sleeve 5 provided with a rounded lip over which the flare of the tube fits loosely. Adjacent to the chuck 2 and sleeve 5 is pivoted a U-shaped frame 38 carrying burners 6 which can be directed upon the interfitting members 1, 4 prior to their being compressed together by a series of four jaws 7 mounted on pivots 28' spaced around a sleeve 24 which is slidable upon a vertical rod 21. Oppositely pivoted jaws 7 are connected at their upper ends by springs 30 which tend to hold their lower ends apart, this being prevented, as shown in Fig. 1, by bell cranks 27 which carry the jaws 7 and engage the upper ends of screws 23 on the lower end 22 of the rod 21. Pivoted to the opposite sides of the sleeve 24 are arms 33 which are pivoted to one end of a rocking lever 34 controlled by a tensioned spring 36 and a chain 37 adapted to be drawn down and released at intervals by the machine drive. The chuck 2 and sleeve 5 form part of a series of such members mounted around the periphery of an intermittently rotating spider which carries them through a series of operative positions. At the loading position an empty chuck 2 is moved upwardly on the slides 9, 10 to allow a tubular member 1 to be inserted, and at the same time an exhaust tube 4 is inserted in the sleeve 5. The chuck is then lowered so that the lower, end of the tube 1 surrounds the flared end of the tube 4, the leading-in wires 3 being arranged around the edge of the flare. The members are then moved into a preheating position and upon the next step of the operating shaft the members reach the operative sealing position shown. While the assembly is moving into this position the burner frame 38 is swung downwardly out of the way, and the rod 21 is held raised by the arm 34, the jaws 7 then being open. The burners then move into working position and oscillate around the members 1, 5 until the glass becomes plastic, whereupon the chain 37 is released automatically and the arm 34 is pulled down by the spring 36, causing the cranks 27 on the slide 24 to engage the fixed screws 23 on rod 21 and close the jaws 7. The degree of pinch imparted is determined by the setting of the screws 23. In an alternative arrangement the members may be heated separately before being moved axially to bring them into the position for pinching, or pressure may be applied by a roller upon a pivoted arm carried by the machine.