| 摘要 |
PURPOSE:To control the temperature of a preform accurately and enhance the film thickness distribution, strength distribution and appearance of the molded article by a method wherein a heating process for a preform is composed of a plurality of preheating steps and a temperature equalizing steps. CONSTITUTION:In the injection and stretching blow molding, the preform is molded by injection, heating, stretching, blowing and taking-out. The preform is injection molded in a mold at an adjusted temperature, then it is blow molded through a plurality of preheating steps 12-1, 12-2 and the temperature equalizing step 12-A. The temperature difference between the inside surface and the outside surface of the preform is much redueced with the progress of the plural preheating steps, and it attains almost 0 deg.C at the end of the temperature equalizing step. |
