| 摘要 |
PROBLEM TO BE SOLVED: To manufacture, by injection molding, a thermoplastic resinous hollow body having a uniform inner diameter and wall thickness and having an inner surface with good smoothness, particularly, a pipe-shaped hollow body having a bend. SOLUTION: The hollow body manufacturing method includes a step in which a molten resin 8 is injected into a molding cavity 2 of a mold 1 equipped with the molding cavity 2 having at one end thereof a pressurizing port 4 provided with a floating core 6 and at the other end thereof a discharge opening 5, and then a pressurized fluid is forced into the molding cavity from the pressurizing port 4 to move the floating core 6 to the discharge opening 5 side and extrude the molten resin 8 from the discharge opening 5, wherein the floating core 6 comprises a circular column section and a top section which connects to one surface of the circular column section and is shaped in such a manner that the area of a cross-section perpendicular to the center axis of the circular column section is gradually reduced from one surface side of the circular column section, and the floating core 6 is dimensioned in such a manner that, if the diameter of the circular column section is A, the height of the circular column section is in the range of 0.1A-1A and the height of the top section is in the range of 0.3A-1.6A. COPYRIGHT: (C)2011,JPO&INPIT |
