GB1243521A - Improvements relating to sealing tube ends - Google Patents

Abstract

1,243,521. Pipes and tubes. A. REYROLLE & CO. Ltd. 12 Feb., 1970 [13 Nov., 1968], No. 50265/68. Heading F2P. [Also in Divisions B3 and H1] A method of sealing the end of a tube 10 connected to a vessel 12 comprises inserting a plug 27 in the end of the tube within an enclusure 20 and necking the tube on to the plug by a process controlled from outside the enclosure. The exhaust tube of a vacuum switch, Fig. 1 (not shown), may be sealed or the filling tube of a bottle containing air or other gas under pressure, e.g. a switch bottle containing SF 6 gas. Apparatus for performing the method may have an electromagnetic forming coil for each of the vessels in the enclosure, capacitor banks being discharged simultaneously or in succession through the coils. As shown, the apparatus has a single forming coil 28 and the vessels 12 are indexed beneath the coil on a turntable 21. With the chamber 20 housed in an oven to ensure de-gassing, it is evacuated by a pump. Atop the chamber 20 is an indexable turret 23 containing hydraulic rams 24 which carry the plugs 27. After the forming coil 28 has been lowered, the aligned ram inserts a plug 27 and holds it in position during the necking operation. The ram and forming coil are then retracted and the turntable 21 and turret 23 indexed for sealing the next vessel. Instead of hydraulic rams 24, a solenoid may attract the plugs 27 out of a magazine in the turret and hold them in position. If the switch bottles are to be gas-filled, a lower degree of evacuation is used and a lower temperature for removing moisture. After cooling, SF 6 gas is introduced under pressure. The necking operation may be performed hydraulically or mechanically.