| 摘要 |
A molten plastic material is extruded to form a parison, and the amount of material extruded is increased to increase the extruded wall thickness of the parison and the gas pressure inside the parison is increased, corresponding to a larger diameter (D') portion of the article to be blow moulded in a blow mould (12), and the extruded wall thickness of the parison is decreased and the gas pressure inside the parison is decreased, corresponding to a smaller diameter portion (D) of the article to be blow moulded. Thus, there is obtained a parison which is uniform in thickness and whose cross-sectional area or diameter varies generally in compliance with the shape of the article to be blow moulded. The apparatus is provided with means for automatically varying both the extruded wall thickness and gas pressure, in the same required sense. <IMAGE> |
