| 摘要 |
PURPOSE:To make it possible to easily mold a hollow body having ribs protruded upwards from its bottom by a method wherein molten resin is filled in cavities for forming rib, which are provided on the lower end face of a mandrel, by pressurizing the molten resin, which is extruded in a space made up of the lower end face of the mandrel and the inner side of an extruder head. CONSTITUTION:Molten resin is extruded from an extrusion orifice 7 under the state that the lower end part of a mandrel 6 is located higher than the extrusion orifice 7. The enclosed portion of an extruded parison 12 is pressurized by being surrounded by the top surface of a bottom mold 9, a die 3 and the undersurface of the mandrel 6. Accordingly, the molten resin is filled under pressure in cavities 6a for forming rib. Next, the mandrel 6 integral with the bottom mold 9 is lowered to the predetermined position between split molds 10 and 11 opposing to each other. Only the mandrel 6 is raised under the state that a positioning rod 8 is left as it is so as to position the tip part of the parison 12 to the bottom mold 9. Next, the split molds are clamped together and at the same time pressure fluid is blowed from the positioning rod 8 into the parison for blow molding. |
