Patent GB-742565-A (GB)
Title: Improvements in or relating to methods of sealing a metal contact element into a glass wall
IPC: H01J29/92
Filed: 1953-11-24
Abstract: 742,565. Glass-metal seals. GENERAL ELECTRIC CO., Ltd., BREADNER, R. L., and SIMMS, C. H. Nov. 24, 1954 [Nov. 24, 1953], No. 32614/53. Class 36. To seal the periphery of a cup- or disc-shaped metal contact element 1 into an aperture in a glass wall 5, the element 1 is shaped to support a temporary sealing member 6 which is of smaller diameter than the element 1 and extends coaxially outwardly therefrom on the side which is to be sealed to the glass wall, the sealing zone of the glass is softened by heat, the element 1 is pushed into the softened glass making contact with the inner surface of the bulge formed by the member 6, the heating is continued until the gas pressure in the bulge causes the glass to break, when the softened glass surrounding the element 1 flows over the surface thereof to form the seal and the member 6 is removed. The element 1 may comprise a hollow cylindrical stem 2 opening into a frusto-conical head 3 having an inturned flange to hold an annular disc 4. The member 6 may comprise a mushroom-headed rivet, the stem 19 of which extends into the stem 2. The element 1 is mounted in a cylindrical holder 8 with stem 2 resting in hole 10. The holder 8 is mounted on a rod 9 provided with a collar 14, a helical spring 15 biasing the holder 8 away from the rod 9, cap 16 on the end of the holder serving as a stop. The rod 9 is mounted within a glass envelope so that head 20 of member 6 abuts the inner surface of the glass, which is formed with an indentation at this point. A gas burner 18 is arranged outside the envelope to rotate about the axis of the element 1 and heat an annular zone of the glass around the head 20. The spring 15 causes the head 20 to push the softened glass outwards and flow over bead 3 of element 1. When cap 16 abuts collar 14, outward movement of holder 8 ceases, continued heating causing the air trapped in the bulge to expand and burst the bulge. The sealing process may be effected simultaneously with the formation of a cylindrical glass neck 42 (Fig. 7) in the envelope 21, as described in Specification 738,203, [Group XXIII], the forming tool 26 arranged to push out the glass neck being linked with rod 9 so that on completion of the two operations, withdrawal of the forming tool caused withdrawal of the holder 8. The envelope 21 is carried on a rotatable plate 22 which also carries the holder 8 and through which shaft 24 carrying the forming tool 26 passes. Beneath plate 22 is a stationary gear wheel 40 which engages wheel 39 on shaft 38 which extends through the plate. Mounted on plate 22 is support 37 to which is pivoted a mounting 43. Burner 18 is secured in cylinder 45, rotatable in mounting 43 by means of a helical gear which engages gear wheel 63 on cylinder 45. This helical gear is driven by shaft 38 through three bevel gears (Fig. 9, not shown) so that the burner may be rotated when set at different angles. Secured to the mounting 43 is a plate 51 which is adjustably secured to a movable arm 52 which is held in the operating position against an adjustable stop 54 by a spring 53. When the arm is swung into the inoperative position, as shown, it is held against stop 55 by spring 53.