PURPOSE: To seal a metal stem and a glass tube with each other by a structure wherein a groove, in which the end of the glass tube is embedded and around the periphery of which a bendable small piece is attached, is provided on the metal stem.
CONSTITUTION: Fritted glass 2 in the form of powder with 100 mesh is mixed with isoamyl acetate (binder) containing nitrocellulose. The stem 3 coated with said fritted glass 2 and the glass tube 1 are mounted on a horizontal type lathe in order to be rotated synchronously. When high frequency wave is applied to a high frequency coil 6 installed along the groove 4 of the stem 3, the groove 4 portion is heated and then, after being heated further, the frit 2 is softened and melted and turned into liquid state, even under which the small piece 5 prevents the frit 2 from flying off outwards. At this instant, the glass tube 1 is pressed against the groove 4 in order to seal the tube 1 and the stem with each other.
NAKAYAMA TAKAFUMI
KOSAKA HARUHISA
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