GB1381214A - Method of manufacturing a tubular lamp envelope - Google Patents

Abstract

1381214 Bending glass tubes PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 22 June 1973 [27 June 1972] 29773/73 Heading C1M In the manufacture of a tubular lamp envelope of which the glass tube 1 or 13 is curved in a flat plane over at least a part of its length; an initially straight tube 1 or 13 is softened by heating and then curved around a bending jig 5, 6 or 16 by co-operation with one or more bending members 2, 3 or 14, 15; is inflated as by puffs p, p to a substantially circular crosssection and then cooled, the curved tube being in, or being given, a horizontal position during at least the greater part of the period of cooling to a temperature at which deformation due to gravity does not occur and the bending members 2, 3 or 14, 15 being removed as soon as the inflation operation has been carried out and the tube is horizontal. Preferably curving is effected with the tube horizontal. In both constructions disclosed, the bending jig 4 or 16 is divisible into two parts 5, 6 and (21, 22) in the plane of the tube and according to Fig. 2, the jig 4 and curved tube 1 are supported in the horizontal position by a plate 7 with an aperture 8, very slightly larger than the jig, so that both parts 5 and 6 of the jig 4 can be removed, as well as the bending members 2, 3, for re-use in further operations, while the tube 1 on the plate 7 continues for further treatment. According to Fig. 3, one part (21) of the jig acts as a supporting plate so that only one part (22) can be reused immediately. In both cases, the support plate 7 or jig part (21) is provided with pivoted holding members 11, 12 which can be hooked over the ends 9, 10 of the tube 1. The bending members may be tongs 2, 3 or rollers 14, 15.