Fastening method and fastening device

A fastening device that fastens a part to be fastened using a fastener including a fastener pin and a collar,

• in which the fastener pin includes a head provided on one side in an axial direction, a shank portion provided on the other side in the axial direction with respect to the head, and a lock portion provided with a lock groove that is provided on the other side in the axial direction to be further away from the shank portion,
• in a state where the head of the fastener pin is located on one side of the part to be fastened through which the fastener pin is inserted, and the lock portion of the fastener pin is located on the other side of the part to be fastened, the collar is mounted to the lock groove, and the collar is crimped to the lock groove of the lock portion, so that the part to be fastened is fastened, and
• a length of a portion of the collar in the axial direction, which is not crimped to the lock groove, is defined as an uncrimped portion height,
• the device comprising:
• a measurement unit that measures a thickness of the part to be fastened;
• and
• a control unit that sets the uncrimped portion height based on a measured value of the thickness of the part to be fastened, and causes the collar to be crimped to the lock groove of the lock portion based on the uncrimped portion height which is set, and
• wherein when the uncrimped portion height to be set is H2,
• a central value of the thickness of the part to be fastened, which corresponds to the fastener pin is T1,
• the measured value of the thickness of the part to be fastened is T2, and
• an optimal value of the uncrimped portion height for the central value T1 is H1,
• the control unit sets the uncrimped portion height H2 to be set based on the measured value T2 of the thickness of the part to be fastened from a calculation equation of “H2=T1−T2+H1”.