Abstract: A method for manufacturing a hollow part with a branch, including a resin filling step of filling a mold, the mold having a main cavity in which a hollowing piece is placed, and a branch cavity to communicate with the main cavity, in which a slide shaft is inserted to advance and withdraw, and that forms a branch pipe portion in an annular space between the branch cavity and the slide shaft, a step of forming a hollow main pipe portion by moving the hollowing piece to force excess resin out of the main cavity, and a shaft removing step of withdrawing the slide shaft to form a branch hollow portion, the hollow part with a branch being made of a resin and having the branch pipe portion integrally connected to the main pipe portion such that the main hollow portion and the branch hollow portion communicate with each other.

Abstract: A hollow body molding device forming a hollow molded body in a main cavity of a mold having in its one end a pressure port including a floating core by injecting molten resin through an injection gate into the main cavity having an outlet, and then pressure-injecting pressurized fluid through the pressure port into the main cavity to move the core toward the outlet through the resin injected into the main cavity to extrude the resin through the outlet and discharge it into a waste cavity, the device having: a floating core accommodating portion located between the outlet and a communication passage leading to the waste cavity and adjoins the main cavity and accommodates the core moved to the outlet by the fluid, in the device, a floating core accommodating portion inside diameter is smaller than a main cavity outlet diameter and is larger than a floating core outside diameter.

Abstract: A hollow body molding device forming a hollow molded body in a main cavity of a mold having in its one end a pressure port including a floating core by injecting molten resin through an injection gate into the main cavity having an outlet, and then pressure-injecting pressurized fluid through the pressure port into the main cavity to move the core toward the outlet through the resin injected into the main cavity to extrude the resin through the outlet and discharge it into a waste cavity, the device having: a floating core accommodating portion located between the outlet and a communication passage leading to the waste cavity and adjoins the main cavity and accommodates the core moved to the outlet by the fluid, in the device, a floating core accommodating portion inside diameter is smaller than a main cavity outlet diameter and is larger than a floating core outside diameter.

Abstract: A method for manufacturing a hollow part with a branch, including a resin filling step of filling a mold, the mold having a main cavity in which a hollowing piece is placed, and a branch cavity to communicate with the main cavity, in which a slide shaft is inserted to advance and withdraw, and that forms a branch pipe portion in an annular space between the branch cavity and the slide shaft, a step of forming a hollow main pipe portion by moving the hollowing piece to force excess resin out of the main cavity, and a shaft removing step of withdrawing the slide shaft to form a branch hollow portion, the hollow part with a branch being made of a resin and having the branch pipe portion integrally connected to the main pipe portion such that the main hollow portion and the branch hollow portion communicate with each other.