GB694977A - Rectangularized television tube body - Google Patents

Abstract

694,977. Making television tubes. I-T-E CIRCUIT BREAKER CO. Nov. 28, 1950 [June 9, 1950], No. 29113/50. Classes 83 (ii) and 83 (iv). [Also in Group XL (a)] A rectangular television tube is formed from a frusto-conical metal member with reinforced seating areas and flanges to provide respectively a seating and supporting surface for the glass face of the tube and for the electron gun. The tube body is formed from an ovoid disc, provided with a central hole to facilitate the spinning operation and the positioning of the body with respect to the punch and die. The disc is placed on a frusto-conical die 105, the ring 109, Fig. 10, engaging the disc, and the punch 108 is brought down to form the disc into the pan-shaped structure 110, the original thickness being retained in the area 111 which is to form a reinforcing area. The pan-shaped disc is then spun, Fig. 11, the spin terminating at the area 111 and also retaining an area 30a of the original thickness at the centre. The boundary 38 of the outer opening describes an undulating line, due to the original ovoid shape, this providing for the final rectangular shape of the outer end of the tube. To reform the cone so that the wider end is made rectangular a punch 130 and die 131, Figs. 12 and 13, are used, the die being provided with an ejector 135 operated by springs 136. This operation shapes the thickened area 111 into the seat 32 for the glass screen, the retaining lip 53 and reinforcement 54, Figs. 1 and 2. In order to withstand external atmospheric pressure the glass screen 49 must be slightly curved, the inner boundary 42 of the seating surface 32 being correspondingly formed so that it occupies the surface of a sphere and for this reason also the walls of the tube are made convex. The formed cone is positioned by a pad against a rotatable member shaped to conform to the sealing surface 32, and the lip 53 trimmed to the correct height by means of a cutting tool having an edge with a curvature equal to the desired spherical curvature of the outer end of the retaining lip 53, Fig. 16 (not shown). A circular portion is then removed from the base 30, Fig. 2, leaving a reinforced sealing annulus for the electron gun 60.