| 摘要 |
PURPOSE:To adjust cooling temperature so as to be suitable for stretched blow molding and reduce manufacturing cost by providing a hollow part through which to pass cooling water in an injection molding die, a double wall pipe whose end comes on the bottom part of an injection core and a hole in the neck part of a preform. CONSTITUTION:A hollow injection core 16 is provided therein with a pipe 26 in spaced relation to the core wall. When a molten plastic is poured from a gate 22 into a cavity 20, cooling water is allowed to flow from the upper end of the pipe 26 as shown by the arrow. A part of the cooling water is carried from a hole 34 through the pipe 26 to outside and the remainder is lowered into contact with a bottom part 161 of the injection core. The cooling water running out through the hole 34 and in contact with the bottom part 161 is low in temperature and large in flow amount. Therefore, the parts to be molded into the neck part 4 and bottom part 8 of a preform are cooled to a large extent. On the other hand, the cooling water rising in contact with the inner wall 162 of a body part absorbs the heat from the poured plastic material and becomes somewhat high in temperature and, since its passage is narrowed by a ring 42, the flow amount is small. |
