GB1498183A - Vacuum envelopes - Google Patents

Abstract

1498183 Moulding glass GENERAL ELECTRIC CO 17 Dec 1974 [26 Dec 1973] 54376/74 Heading C1M A centrifugally cast hollow glass vacuum envelope 10 has a metal ring 14 with outer part 20 embedded within the wall of the envelope but not extending to the exterior wall, the ring 14 having an inner part 6 with a welding flange 18 in the hollow centre of the envelope. To aid embedding of the ring 14, an outer flange 24 and a plurality of holes 25 may be provided on and in the outer part 20. Alternatively notches in a flat ring may be provided. The method of embedding the ring 14 in the envelope 10 comprises a centrifugal mould 26 having a cap 34, with central bore 42 through which the mould is charged with molten glass, the cap 34 having ring holding means 38 for supporting ring 14 in the required position in the mould 26 and then rotating the mould 26 as by mounting on the shaft 28 of a motor 30. Preferably the mould 26 has grooves 36 for holding an upper end flange 22 and a lower end flange 22 is held against the mould 26 by a block 32. The mould 26 may have inner corrugations to provide exterior rings 12 on the envelope 10. As shown in Fig. 10, the holding means 38 comprises a plurality of magnetic devices 40 to attract the flange 18. Alternatively, spring mounted fingers may be pushed through the opening in ring 14 and under flange 18. In a further embodiment, a disk member secured at the lower end of holding means 38 has spaced slots in the outer edge which can be positioned, by slight rotation, under inwardly directed flanges on the inner flange 18, which may be ground off at a later stage.