| 摘要 |
PURPOSE:To mold a hollow body whose pinch-off part of the bottom has been eliminated, by a method wherein the tip of parison is placed between a mandrel and compression member and the parison is arranged on an external circumferential surface of the mandrel while molten resin is being extruded. CONSTITUTION:The lower end part of an extrusion head 1 is closed by parison 11 extruded through an extrusion port 7. A closing part of the parison 11 is compressed by raising a compression member 8. A mandrel 6 and the compression member 8 are lowered in a body. A thickness of the parison 11 to be formed after the external circumference of the mandrel 6 is controlled by extruding molten resin according to a lowering speed. Blow molding is performed by clamping split molds 9, 10 and blowing a pressure fluid within the parison 11. Pinch-off of the parison 11 at the bottom of a molded body is eliminated and then the pinch-off part is not generated on this part by abutting edges of the split molds 9, 10 against the external circumferential surface of the fringe of the upper end of the compression member 8 to make the bottoms of cavities 9a, 10a almost coincide with the upper end of the compression member 8.
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