Which part of a lockbolt is referred to as the rings that the collar swages to during installation?

The correct answer identifies the specific component of a lockbolt known as the locking grooves. During the installation of a lockbolt, the collar is swaged, or deformed, around these locking grooves to create a secure connection. This swaging action ensures that the collar tightly grips the locking grooves, thus providing a strong and stable joint.

Understanding the function of the locking grooves is crucial for appreciating how lockbolts achieve their effectiveness in aerospace applications. They serve as critical areas for ensuring that the fastener remains locked in place even under the stresses encountered in flight. The mechanical interlocking created by the swaging of the collar onto these grooves contributes significantly to the fastener's reliability and integrity.

In contrast, while the shank is the long part of the bolt that extends from the head to the tip and the head is the enlarged portion at the end of the bolt providing a means for applying torque, they do not specifically describe the rings that connect with the collar. Similarly, the collar itself is the component that is swaged during installation but does not refer to the grooves on the bolt where the locking mechanism occurs. Thus, the locking grooves represent the specific part where the critical interaction happens during the installation process.