Process of injection stretch blow molding hollow article having thick-walled bottom

A process of injection stretch blow molding a hollow article having a thick-walled bottom region, comprising the steps of:

• injection molding a preform in the form of a closed-end cylinder in an injection molding station;
• moving said preform to a blow molding station wherein said preform is placed within a blow cavity mold while said preform still retains heat provided thereto by the injection molding step;
• thereafter, inserting a stretching rod into said preform and moving said stretching rod so that a distal bulged end portion of said rod reaches and contacts the inner bottom wall and side wall portions of said preform corresponding to the thick walled bottom region of said hollow article;
• regulating the temperature of the distal bulged end portion of the stretching rod inserted into said preform and, prior to initiation of blow molding, maintaining said distal bulged end portion in contact with said inner bottom wall and side wall portions of said preform corresponding to the thick-walled bottom region of said hollow article thereby regulating the temperature at the inner bottom and side wall portions of the preform contacting with said distal bulged end portion to a temperature which is lower than the temperature of another portion of said preform;
• and
• biaxially stretch blow molding said preform into said hollow article by blowing a pressurized fluid into said preform and also by driving said stretching rod.