| 摘要 |
PURPOSE:To obtain a cylindrical molded body whose surface is smooth and that has properties suitable as a recording medium, by vacuum forming a tensed thermoplastic resin sheet using a male mold that has vacuum means and heating and cooling means and whose head section is made of a heat insulating material. CONSTITUTION:After a sheet 1 is heated to the molding temperature, it is moved to a zone (C) while being clamped by clamps 2, and is secured around male molds by a knock plate 4 and a clamp plate 5. Then the sheet 1 is pushed up by the male molds 9 and at the same time or after several seconds, the sheet 1 is sucked via piping 10 of the male molds 9 by a vacuum pump to be formed in conformity with the shape of the male molds 9. The head 11 of the male mold is made of a heat insulating material, and only the head 11 is kept at a relatively low temperature so that when the heated sheet 1 is pushed up, the part of the sheet 1 in contact with the heat is cooled and fixed simultaneoulsy when it is brought in contact. Therefore the contacted part would not be stretched excessively, and the roughness of the inner surface of the molded body can be prevented from increasing. |
