GB925488A - Improvements relating to the sealing together of glass and other vitreous parts - Google Patents

Abstract

925,488. Heating glass by passage of current. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Feb. 13, 1962 [Feb. 24, 1961], No. 6896/61. Class 39 (3). [Also in Group XXIII] A process for joining together parts of glass and other vitreous materials along a continuous path of restricted width comprises providing an even number (at least four) of approximately equidistant stationary electrical connections to the path, and after preheating to a temperature sufficient to render the material along the path electrically conductive, applying electrical power sequentially to pairs of sections of the path lying between said connections so that virtually no voltage exists across the remainder of the sections. Two glass mirror image pressings 1 are preheated by gas burners 12 and then by operation of a switch 11, current is fed from two equal secondary windings 8 and 9 of a transformer through resistances 10 to the sections lying between tungsten rods 2, 3 and 4, 3 and then 2, 5 and 4, 5, alternately, at for example one second intervals, until the pressings have fused together. The pressings 1, when joined peripherally, constitute an envelope defining a sinuous path for an electric discharge between electrodes 14. The screen and body portions of a cathode-ray tube may be similarly joined. Graphite may be applied to the contiguous parts of the parts to be joined. A furnace may replace the gas burners 12. After sealing, the edges of the pressings 1 may be shaped by dies while still plastic.