Method of molding large containers by the process of stretch blow molding

A method of molding a large container by the process of stretch blow molding, said method comprising the steps of:

• injection molding a closed-end parison having a thick-walled portion to be stretched and having a length shorter than a length of the large container to be formed, said parison being injection molded within a cavity defined by an injection mold, a core mold and a lip die;
• releasing said closed-end parison from the injection mold and the core mold after a skin layer is formed on a surface of said closed-end parison having a high inner temperature, a solidified neck of said closed-end parison is held by the lip die;
• shifting said released closed-end parison with said lip dies to mold halves of a preform mold heated to a predetermined temperature;
• receiving said closed-end parison between said mold halves of said preform mold, and closing said mold halves of said preform mold to position said closed-end parison in a center of a preform cavity, which is defined by mating surfaces of said preform mold halves;
• inserting a blow core and a stretch rod downward through said lip die into said closed-end parison after closing said preform mold, so as to allow said closed-end parison to be stretched in an axial direction by said stretch rod and expanded by application of air pressure while said closed-end parison still has a high inner temperature;
• repeatedly blowing in and releasing an application of low-pressure air into said closed-end parison, while implementing the stretching of the closed-end parison in the axial direction only during a first low pressure air application, a final low-pressure air application being applied for a period longer than that of the other repeated low-pressure air applications, thereby expanding said closed-end parison to fill said preform cavity to mold a predetermined preform having an intermediate size between that of said closed-end parison and said large container;
• placing said preform in a blow mold;
• and
• manufacturing said large container having a thin-wall body as a final product by the process of stretch blow molding;
• said preform is supported by a support member, which is withdrawn into a bottom mold by application of air pressure in the step of stretch blow molding, and support provided by said support member preventing a draw-down of said preform because of heat held in said preform.