Assembled mandrel and method for producing hollow structure

A core box for forming a hollow structure having a shape similar to that of the core box, by layering a prepreg on the surface of the longitudinally oriented core box, covering the core box with a vacuum bag, heating while vacuuming the inside of the vacuum bag, and heat-curing the prepreg while pressing the prepreg against the core box, the core box comprising:

• a first box member that extends in a longitudinal direction;
• a second box member that extends in the longitudinal direction, is adjacent to the first box member, and is separated from the first box member and withdrawn in the longitudinal direction after the forming of the hollow structure;
• and
• a planar detachable member that is disposed to cover at least one surface of facing contact surfaces between the first box member and the second box member.

A core box for forming a hollow structure having a shape similar to that of the core box, by layering a prepreg on the surface of the longitudinally oriented core box, covering the core box with a vacuum bag, heating while vacuuming the inside of the vacuum bag, and heat-curing the prepreg while pressing the prepreg against the core box, the core box comprising:

• a first box member that extends in a longitudinal direction;
• a second box member that extends in the longitudinal direction, is adjacent to the first box member, and is separated from the first box member and withdrawn in the longitudinal direction after the forming of the hollow structure;
• and
• a resin strip that is sandwiched between the first box member and the second box member via a box-releasing agent, extends in the longitudinal direction, and is made of the same kind of resin material as the prepreg.

A method for producing a hollow structure having a shape similar to that of the core box, by layering a prepreg on the surface of a longitudinally oriented core box, covering the core box with a vacuum bag, heating while vacuuming the inside of the vacuum bag, and heat-curing the prepreg while pressing the prepreg against the core box, the method comprising:

• a detachable member covering step of covering at least one surface of facing contact surfaces between a first box member that constitutes the core box and extends in a longitudinal direction and a second box member that extends in the longitudinal direction and is adjacent to the first box member, with a planar detachable member;
• a core box assembling step of overlapping the first box member and the second box member on each other, thereby assembling the core box;
• a prepreg layering step of layering the prepreg on the surface of the core box;
• a forming step of covering the core box, on which the prepreg has been layered, with the vacuum bag, and heating while vacuuming the inside of the vacuum bag;
• and
• a core box withdrawing step of separating the second box member of the core box from the first box member to detach the second box member in the longitudinal direction, and then, detaching the first box member from the hollow structure.