Blow molding device and blow molding method

A blow molding method for forming a blow molded article having a built-in part in an interior space thereof, wherein said blow molding method uses a blow mold adapted to form an outer wall of the blow molded article, a parison holding unit adapted to hold a lower end of a parison, and a built-in part holding unit adapted to hold the built-in part prior to blow molding, wherein

• said blow mold includes two mold members split along a parting line thereof, said two mold members define a cavity adapted to form the outer wall of the blow molded article in split faces thereof, slide cores are provided in an inner surface of said blow mold so as to be slid inwardly and outwardly of said cavity such that the built-in part and the parison are held between said slide cores, and the outer wall of the blow molded article is molded with said cavity,
• said parison holding unit is located on the lower side of said blow mold, and includes a plurality of parison expanders adapted to be inserted in an interior space of a lower end of the parison, and a parison outer holding plate adapted to hold an outer surface of the lower end of the parison, each of said parison expanders is attached so as to slide outwardly from a center of the parison,
• said built-in part holding unit includes an airtight guide tube adapted to hold the built-in part therein, a holding rod adapted to hold the built-in part in said airtight guide tube so as to slide the built-in part upwardly and downwardly, and a lower guide plate having a hole through which said holding rod is slidable, and
• said blow mold is opened along said parting line, the parison is dropped in said cavity that is opened, after the lower end of the parison is expanded with said plurality of parison expanders, said airtight guide tube is inserted in the lower end of said parison, the lower end of the parison is held between said airtight guide tube and said parison outer holding plate, and gas is inserted in the interior space of the parison to inflate the same, thereby carrying out preblowing, and the built-in part is positioned in the interior space of the parison from said airtight guide tube while holding the built-in part with said holding rod, and is held in a position facing said cavity, when said blow mold is closed, and the parison and the built-in part are held between said slide cores, said holding rod is removed from said blow mold, said blow mold is closed completely and gas is blown in the interior space of said parison, thereby forming said blow molded article.