Structural-body molding method and joined structural body

A structural-body molding method comprising:

• preparing a first pre-preg, which comprises a plurality of first carbon fibers that extend in only one direction within a first matrix composed of a first thermoplastic resin;
• a first mold;
• a second pre-preg, which comprises a plurality of second carbon fibers that extend in only one direction within a second matrix composed of a second thermoplastic resin;
• a second mold that, together with the first mold, forms a cavity;
• a needle that has a pointed tip portion;
• and an injection material that contains a third thermoplastic resin and is injected into the cavity;
• setting the first pre-preg and the second pre-preg within the cavity such that the first carbon fibers extend in a first direction, the second carbon fibers extend in a second direction, and the first pre-preg and second pre-preg cross within a specific area and thereby overlap in a third direction that is orthogonal to the first direction and the second direction;
• thereafter, clamping the first mold and the second mold together;
• forming a hole by causing the needle, starting from the tip portion thereof, to penetrate into the specific area of the first pre-preg and second pre-preg in the third direction and thereby form a connecting hole using the needle;
• and
• injecting the injection material into the cavity during the hole-forming step or after the hole-forming step while the needle remains in the connecting hole;
• wherein the third thermoplastic resin has a higher melting point than the first thermoplastic resin and the second thermoplastic resin.

A method, comprising:

• placing a first pre-preg, which comprises a plurality of first carbon fibers that extend in only one direction within a first matrix composed of a first thermoplastic polymer, in a first mold such that the first carbon fibers extend in a first direction;
• placing a second pre-preg, which comprises a plurality of second carbon fibers that extend in only one direction within a second matrix composed of a second thermoplastic polymer, in the first mold such that the second carbon fibers extend in a second direction, and the first pre-preg and second pre-preg overlap in a third direction that is orthogonal to the first direction and the second direction;
• thereafter, clamping the first mold and a second mold together to form a cavity therein,
• while the first and second pre-pregs are clamped in the first and second molds, perforating an overlapping portion of the first and second pre-pregs in the third direction using a needle to form a connecting hole that extends through the first and second pre-pregs, and
• while the needle is penetrating into, or is stationary in, the connecting hole, injecting a third thermoplastic polymer into the cavity such that the third thermoplastic polymer contacts the needle and at least one of the first and second pre-pregs, thereby forming a structural body;
• wherein the third thermoplastic polymer has a higher melting point than the first thermoplastic polymer and the second thermoplastic polymer.