METHOD FOR BLOW MOLDING OF RESIN MOLDED ITEM

摘要

PURPOSE:To provide surely a specified thickness ratio to a molded item by setting moving speed of an expander member which makes a part except a specified part thin in accordance with the set thickness ratio of the specified part of a parison to the part except the specified part after molding. CONSTITUTION:Each expander panel 5 is brought into contact with the inner peripheral face of each specified part 7a of a parison and the expander panels 5 and 5 are driven toward the outside of the parison by a specified amt. at a specified speed to draw parts 7b and 7b except specified parts 7a and 7a of the parison 7 to make them thin. Then, after a mold 3 is closed together, compressed air is blown into the parison 7 by means of a blowing apparatus 4 to perform blow molding. In this case, to provide surely a specified thickness ratio to the molded item, the moving speed of the expander panel 5 is set larger with increase in the set thickness ratio in accordance with the set thickness ratio of the specified part 7a of the parison 7 to the part 7b except it after molding.