PURPOSE: To seal extremely easily a billet in vacuum by putting the billet in a vessel having an opening and welding an evacuationg pipe having a neck part to the opening, and inserting a plug into the neck part after evacuating the inside of the vessel into vacuum to join it to the neck part by welding.
CONSTITUTION: A billet 3 is put in a vessel 1 provided with a diaphragm such as a wire net at its opening, and an evacuating pipe 5 provided with a neck part 6 is welded to the opening of vessel 1. An exhausting pipe 7 having a plug 8 used for the neck part 6 is connected to the other end of the pipe 5, then the vessel 1 is heated by a heater 10 and evacuated into vacuum by an evacuating device. Next, the plug 8 is falled and inserted into the neck part 6, and the plug 8 is welded to the pipe 5 from the outside of the neck part 6 by TIG welding, etc. to seal the pipe 5, then the billet 3 is vacuum sealed in the vessel 1 by cutting finally the welded part.
MATSUDA TADAHARU
UOZU YOSHIO
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