| 摘要 |
PURPOSE:To carry out the blow molding such that the thickness or corners is made the same as that of the other part, by controlling the temperature of a cylindrical parison from the inside so that the temperature difference occurs from part to part of the parison, and carry out the blow molding of the parison in such a way that the low temperature part of the parison is positioned on the side where the blow ratio of the blow cavity is high. CONSTITUTION:A bottomed parison 1 of a polyethylene terephthalate having a circular barrel section and a uniform wall thickness if injection molded. The parison 1 is released at a temperature of about 100 deg.C, and is transferred to a temperature controlling apparatus 6, where its temperature is controlled from the outside as a whole, and a temperature controlling core 2 is inserted in the parison 1 to cool the parison wall section 1a. The diameter of the temperature controlling core 2 is equal to or a little large than the inner diameter of the parison, and the opposite sides of the temperature controlling core 2 are scraped into flat noncontact sections 2a. Since the noncontact sections 2a are controlled to 50-60 deg.C, if only the temperature controlling core 2 is inserted into the parison 1, the parison wall section 1a will be cooled from inside. A difference in melt elasticity can occur in the parison 1 that has been pressurised from inside due to the temperature difference therein, and the parison is extended uniformly, so that a product 5, that is, a flat rectangular bottle having a uniform wall thickness distribution can be molded. |
