GB559806A - Improvements relating to metal-to-glass or like material seals - Google Patents

Abstract

559,806. Uniting vitreous material to metal ; metal articles, producing. STANDARD TELEPHONES & CABLES, Ltd. Jan. 29, 1943, Nos: 1534 and 1535. Convention date, Jan. 31, 1942. [Class 36] [Also in Group XXII] The metal member of a glass-to-metal seal which is especially applicable for making connections to electrodes, such as grids, in a vacuum tube is constructed of a metal collar 4, preferably of copper, with tapering sleeves 5, 5' having a relatively large thickness at the collar and having relatively thin or feather edges from f to g. At the junction with the glass tube the feather edge from f to g may be completely embedded in the glass, but the glass extends further inside the sleeve to form a strong attachment to the sleeve, and the whole joint is adapted to stand up against heat variations. The thickness of the metal preferably increases rapidly at a point 8. The copper is preferably rolled so as to reduce the size of the crystals of its structure, in order to prevent seepage. The outer edges of the tapered sleeves are cut so as to meet at an angle of about 45 degrees. The seal is produced from an annular copper member 21, Fig. 5, which is mounted between mandrels 27, 26 in a lathe, the member 21 fitting exactly on a cylindrical extension of mandrel 26. By means of inclined shearing members 42 the member 21 is cut along lines 23, 24 and the annular portions thus severed are bent over the outer surfaces of the mandrels to form cylindrical sleeves which are finally rolled by means of inclined rollers 45, 46, Fig. 8, to form tapered sleeves of the required shape, the ends being cut to form a meeting edge including an angle of 45 degrees.