| 摘要 |
PURPOSE:To prevent the leakage of air, and to obtain a hollow annular body having high airtightness by putting an aqueous solution into an annular recessed groove body before thermal welding and obviating the temperature rise of internal air due to a hot plate. CONSTITUTION:A proper quantity of an aqueous solution 5 is injected into an annular recessed groove body 4, an upper surface thereof is opened. A hot plate 6 is applied to an opening section in the annular recessed groove body 4 while an opening edge in an annular recessed groove body 7, an opening section thereof is directed downward, is pressure-welded to the upper surface of the hot plate 6. Heat energy from the hot plate 6 entering air in the annular recessed groove body 4 is absorbed to the aqueous solution 5, and the temperature of air is not elevated so much. The temperature of internal air is elevated in the annular recessed groove body 7. In the worst case, one part of the annular recessed groove body 7 is spread and internal air escapes to the outside, and the temperature of a synthetic resin at a position where internal air leaks drops, but the reverse side opposite to one part of the groove body 7 sufficiently compensates the temperature. The opening edges of the annular recessed groove body 4 and the annular recessed groove body 7 are butted, and the annular recessed groove bodies are pressed down, thus obtaining a hollow annular body 8 having airtightness. |
