| 摘要 |
PURPOSE:To simplify the sealing work in a vacuum by inserting vacuum packings having a thermal expansion coefficient larger than that of the constituting materials of a cylinder body and covers and kept in a solid state at the extruding temperature of a billet between them and fastening them. CONSTITUTION:Vacuum packings 4 having a thermal expansion coefficient larger than the constituting materials of a cylinder body and covers and kept in a solid state at the extruding temperature of a billet are prepared and inserted between the cylinder body 1 and the covers 2, 3 in a vacuum after the interior of the cylinder body is vacuumed, and the cylinder body and the covers are fastened mechanically. An aluminum packing is suitable for the vacuum packing 4. Accordingly, when the vacuum packings are used, even if the cylinder body and the covers are thermally expanded during the hot working of the superconductive billet, the thermal expansion quantity of the vacuum packings becomes larger than it, thus no gap is generated at junctions regardless of mechanical fastening.
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