For large products, there are two key molding technologies.
1. It is required to quickly provide the amount of melt required for the product, and reduce the drop and caliber of the parison caused by the large volume and dead weight;
2. The cooling of large products can be long, and the extruder cannot be continuously performed, so the head with a storage cylinder is developed. Hollow blister products with a volume exceeding 20L are called large hollow blow molded containers.
Firstly, the melt plasticized by extruder is stored in a charging cylinder, that is, after the melt in the charging cylinder reaches a predetermined amount, it is molded out through the annular gap at a high speed with a pressurized plug to form a certain length of tube. In order to further improve the wall thickness uniformity of large blow molding products, the variable annular gap die and program controller have been used in this kind of extrusion blow molding machine with charging cylinder, In order to realize the automatic control of the axial wall thickness distribution of the parison according to the preset program, so as to further improve the uniformity of the wall thickness of large blow molding products.
