| 摘要 |
PURPOSE:To reduce the degree of ununiform thickness by a method wherein the members of a plug consisting of a plurality of layers of cylindrical members, which are provided around a bar-like center member and slidable each other, are projected in order starting from the center member into a vacuum forming mold so as to bring a sheet close to the inner surface of the vacuum forming mold in order to vacuum-form the sheet. CONSTITUTION:A thermoplastic resin sheet 7 having an oxygen barrier layer is attached to the opening of a mold 1 with a fixture 8. The sheet is heated up to the predetermined temperature and, after that, a center member 3 is projected. In this case, the portion contacting with the upper edge of the mold of the sheet is pushed up by means of air in the interior of the mold and stretched more than its portion fixed to the fixture 8. Next, cylindrical members 4 and 5 are projected in order, resulting in uniformly stretching the sheet 7 in order with the respective members 3, 4 and 5 of a plug 6 so as to bring the sheet to the state close to the inner surface of the mold 1. When the mold is vaccumized through a pipe 2 at this time point, the sheet 7 is brought into close contact with the inner surface. A vacuum- formed vessel 9 is obtained by being released from the mold. Since the vessel 9 is stretched gradually with the respective members 3, 4 and 5 so as to be brought close to the inner wall of the mold 1 for the final vacuum forming, the degree of ununiform thickness of the vessel becomes small. |
