Patent ID: 8827690

Claim:
A hollow body molding device in which a molten resin is injected into a main cavity having on its one end a pressure port including a floating core and on its other end an outlet, a pressurized fluid is pressure-injected through the pressure port after the injection of the molten resin, the floating core is moved to the outlet side, the molten resin is extruded from the outlet simultaneously with the movement of the floating core, and the hollow molded body is molded, comprising: a floating core storage portion which is connected to the main cavity and stores the floating core moved by the pressurized fluid; an auxiliary cavity which stores a molten resin discharged from the main cavity and the floating core storage portion; a communication passage which communicates the floating core storage portion and the auxiliary cavity with each other; and an opening and closing means that opens and closes the communication passage by sliding movement, wherein the communication passage includes a discharge passage connecting the floating core storage portion and a runner communicating the discharge passage and the auxiliary cavity with each other, the opening and closing means slides in the discharge passage, and an inlet cross-sectional area B of the communication passage is B<πA 2 /4 (A is the maximum diameter of the floating core).