Reverse lip blow molding

A method for blow molding a deep recessed lip onto a molded part comprising the steps of:

• providing a mold apparatus having two mold sections forming opposite sides of the mold, each mold section comprising a center member, a first member on either side of said center member, each first member being reciprocally movable toward and away from said center member and having a channel therein, and a second member reciprocally movable within said channel of each first member, each second member adapted for slidable engagement with said center member;
• extruding a parison into said mold apparatus;
• sealing said parison airtight in said apparatus;
• pressurizing said parison in said apparatus and thereby forcing a portion of said parison into engagement with the mold sections including said center member, each said first member and each said second member;
• moving each said first member toward its corresponding center member so as to form a hollow recessed lip against said center member, said first member and said second member;
• depressurizing the portion of the parison within the apparatus;
• moving said mold sections laterally away from one another while initially moving the first and second members of each mold section vertically until the first member has cleared the lip formed in the molded article;
• and removing said molded parison from said mold apparatus.

A method for blow molding a deep recessed lip onto two molded parts comprising the steps of:

• providing a mold apparatus having two mold sections forming opposite sides of the mold, each mold section comprising a center member, a first member on either side of said center member, each first member being reciprocally movable toward and away from said center member and having a channel therein, and a second member reciprocally movable within said channel of each first member, each second member adapted for slidable engagement with said center member;
• extruding a parison into said mold apparatus;
• sealing said parison airtight in said apparatus;
• pressurizing said parison in said apparatus and thereby forcing a portion of said parison into engagement with the mold sections including said center member, each said first member and each said second member;
• moving each said first member toward its corresponding center member so as to form a hollow recessed lip against said center member on each side thereof;
• depressurizing the portion of the parison within the apparatus;
• moving said mold sections laterally away from one another while initially moving the first and second members of each mold section vertically until the first member has cleared the lips formed in the molded article;
• removing said molded article from said mold apparatus;
• and separating said article between said recessed lips, thereby forming two symmetrical parts each having a substantially U-shaped recessed lip.

A method for blow molding a deep recessed lip onto molded article comprising the steps of:

• providing a mold apparatus having two mold sections forming opposite sides of the mold, each mold section comprising a fixed member, a first member adjacent said fixed member, said first member being reciprocally movable toward and away from said fixed member and having a channel therein, and a second member reciprocally movable within said channel of said first member, said second member adapted for slidable engagement with said fixed member;
• extruding a parison into said mold apparatus;
• sealing said parison airtight in said apparatus;
• pressurizing said parison in said apparatus and thereby forcing a portion of said parison into engagement with the mold sections including said fixed member, said first member and said second member;
• moving said first member toward its corresponding fixed member so as to form a hollow recessed lip against said fixed member;
• depressurizing the portion of the parison within the apparatus;
• moving said mold sections laterally away from one another while initially moving the first and second members of each mold section vertically until the first member has cleared in contact with the lip formed in the molded article;
• and removing said molded article from said mold apparatus, thereby forming a molded article having a substantially U-shaped recessed lip.