Molding method and cooling apparatus for pressure resisting bottles of synthetic resin

A molding method for forming a pressure resisting biaxially stretch blow molded bottle, the bottle having a big foot type petaloid bottom made of synthetic resin, said method comprising:

• biaxially stretch blow molding said bottle including blowing said bottle in a blow mold for about 1.5 seconds to about 3.0 seconds of blowing time to form said big foot petaloid bottom having a projecting deformation at a center part of the bottom with a predetermined height;
• releasing the bottle from the blow mold while the bottom of the bottle is warm and deformable and allowing the height of the projecting deformation to decrease;
• then
• forcing the projecting deformation of the center part of the bottom of said bottle onto a reform jig comprising a mold surface having a projecting central portion, said forcing commencing within about 15 seconds after said bottle is released from said blow mold, said projecting central portion thereby pushing said projecting deformation back to at most said predetermined height while an inside of said bottle is pressurized;
• and
• directing a cooling medium through a cooling medium passage within said reform jig while directing a cooling medium through a cooling nozzle extended into said bottle so that said cooling medium is directed toward the center of the bottom of said bottle from both the nozzle and the reform jig thereby cooling said center part below about 70.degree. C.

A molding method for pressure resisting biaxially stretch blow molded bottles, each of the bottles having a big foot type petaloid bottom made of synthetic resin, said method comprising:

• biaxially stretch blow molding said bottles including blowing said bottles in a blow mold for about 1.5 seconds to about 3.0 seconds of blowing time;
• releasing the bottles from the blow mold while the bottom of each bottle is warm and deformable;
• then
• forcing a center part of the bottom of each of said bottles onto a double-form jig comprising a mold surface having a projecting central portion to raise a height of the center part while an inside of each of said bottles is pressurized, said forcing occurring within about 15 seconds after said bottles are released from said blow mold;
• and
• directing a cooling medium through a cooling medium passage within said reform jig while directing a cooling medium through a cooling nozzle extended into said bottle so that said cooling medium is directed toward the center of the bottom of said bottle from both the nozzle and the reform jig thereby cooling said center part of each of said bottles below about 70.degree. C.