Device for manufacturing bent pipe and method for manufacturing bent pipe

A device for manufacturing a bent pipe, the device comprising:

• an inner core metal configured to be arranged inside a first pipe;
• and
• a bending mold configured to bend the first pipe containing the inner core metal;
• the inner core metal comprising:
• an inner core metal body having a hollow cylindrical shape or a solid cylindrical shape;
• a first inner movable portion having a hollow cylindrical shape or a solid cylindrical shape, the first inner movable portion being coupled to an end in an axial direction of the inner core metal body, the first inner movable portion being swingable relative to the inner core metal body around a first rocking shaft orthogonal to a central axis of the inner core metal body;
• and
• a second inner movable portion having a hollow cylindrical shape or a solid cylindrical shape, the second inner movable portion being coupled to the first inner movable portion on an opposite side of the inner core metal body with the first inner movable portion interposed between the inner core metal body and the second inner movable portion, the second inner movable portion being swingable relative to the first inner movable portion around a second rocking shaft parallel to the first rocking shaft,
• the first inner movable portion having an enlarging diameter portion enlarged in diameter toward the second inner movable portion, a first end located near the second inner movable portion in an axial direction of the first inner movable portion, and a second end located on an opposite side of the first end,
• the first end having a first outer diameter larger than a second outer diameter that is an outer diameter of the second end and a third outer diameter in an intermediate location between the first end and the second end,
• an outer diameter of the first end being equal to a maximum outer diameter of the second inner movable portion,
• the enlarging diameter portion being smoothly enlarged in diameter so that an amount of change in an outer diameter per unit length in an axial direction increases toward the second inner movable portion,
• the bending mold being configured to cause an inner surface of the first pipe to press the first inner movable portion and the second inner movable portion.