Fastening method and fastening apparatus

A fastening apparatus for fastening a plurality of workpieces, each having a through hole formed therein, using a fastener formed from a shaft body, which is made of a thermoplastic polymer reinforced with carbon fibers and extends in an axial direction, the fastening apparatus comprising:

• a shaft body heater comprising a high-frequency induction coil configured to inductively heat the shaft body without the shaft body heater contacting the shaft body by generating magnetic field lines that induce eddy currents in the carbon fibers while the shaft body is not inserted through the through holes of each of the workpieces;
• a press configured to apply pressure to one axial end of the heated shaft body while the heated shaft body is not inserted through the through holes of each of the workpieces;
• an intermediate-forming die configured to plastically deform the heated shaft body to form an intermediate piece comprising a shaft part formed integrally with a first head part and extending in the axial direction;
• a shaft part heater comprising a high-frequency induction coil configured to inductively heat the shaft part of the intermediate piece without the shaft part heater contacting the shaft part by generating magnetic field lines that induce eddy currents in the carbon fibers while the shaft part is inserted through each of the through holes;
• a press configured to apply pressure to the heated shaft part while the heated shaft part is inserted through each of the through holes of each of the workpieces;
• and
• a fastener-forming die configured to plastically deform the heated shaft part to form a second head part on an axial end of the shaft part that is opposite of the first head part and thereby form the fastener that fastens the workpieces;
• wherein:
• the shaft body heater is configured such that the shaft body heater does not contact the heated shaft body while the intermediate piece is being formed;
• and
• the shaft part heater is configured such that the shaft part heater does not contact the heated shaft part while the second head part is being formed.

A fastening apparatus for fastening a plurality of workpieces, each having a through hole formed therein, using a fastener formed from a shaft body, which is made of a thermoplastic polymer reinforced with carbon fibers and extends in an axial direction, the fastening apparatus comprising:

• a shaft body heater comprising a high-frequency induction coil configured to inductively heat the shaft body without the shaft body heater contacting the shaft body by generating magnetic field lines that induce eddy currents in the carbon fibers while the shaft body is inserted through each of the through holes;
• a press configured to apply pressure to one axial end of the heated shaft body while the shaft body is inserted through each of the through holes of each of the workpieces;
• an intermediate-forming die configured to plastically deform the heated shaft body to form an intermediate piece comprising a shaft part formed integrally with a first head part and extending in the axial direction;
• a shaft part heater comprising a high-frequency induction coil configured to inductively heat the shaft part of the intermediate piece without the shaft part heater contacting the shaft part by generating magnetic field lines that induce eddy currents in the carbon fibers while the shaft part is inserted through each of the through holes;
• a press configured to apply pressure to the heated shaft part while the heated shaft part is inserted through each of the through holes of each of the workpieces;
• and
• a fastener-forming die configured to plastically deform the heated shaft part to form a second head part on an axial end of the shaft part that is opposite of the first head part and thereby form the fastener that fastens the workpieces;
• wherein:
• the shaft body heater is configured such that the shaft body heater does not contact the heated shaft body while the intermediate piece is being formed;
• and
• the shaft part heater is configured such that the shaft part heater does not contact the heated shaft part while the second head part is being formed.

A fastening apparatus for fastening a plurality of workpieces, each having a through hole formed therein, using a fastener formed from a shaft body, which is made of a thermoplastic polymer reinforced with carbon fibers and extends in an axial direction, the fastening apparatus comprising:

• a shaft body heater comprising a high-frequency induction coil configured to inductively heat the shaft body without the shaft body heater contacting the shaft body by generating magnetic field lines that induce eddy currents in the carbon fibers while the shaft body is inserted through each of the through holes of each of the workpieces;
• a press configured to apply pressure to both axial ends of the heated shaft body while the heated shaft body is inserted through each of the through holes;
• and
• a fastener-forming die configured to plastically deform the heated shaft body into a first head part, a shaft part formed integrally with the first head part and extending in the axial direction, and a second head part on an axial end of the shaft part that is opposite of the first head part, and thereby form the fastener that fastens the workpieces;
• wherein the shaft body heater is configured such that the shaft body heater does not contact the heated shaft body while the first head part, the second head part and the shaft part are being formed.