| 摘要 |
<p>PURPOSE: To make necessary reinforcement with a minimum additional material by forming radial ribs at an interval in a plurality of circumferential directions extended across a central bottom so that the bottom is not deflected. CONSTITUTION: A preform 44 is molded by an injection molding, and transferred to a blowing mold 63. A body portion 78 of the preform 44 is reinforced by ribs 75, a bottom forming portion of the preform 44 is cured to resist against an elongation in an axial direction so that the elongation of the preform 44 is stretched at the portion 78. Thus, the ribs 75 advantageously reinforce the bottom forming portion of the preform 44, and substantially reduce the elongation during stretching of the preform 44. As a result, at the time of blowing the preform 44 in a mold 63, a bottom segment of the bottle of a bottle portion under a flash line has a thicker wall, and is very reinforced as compared with an amount of a plastic material required for the ribs 75.</p> |
