Self-locking nut or bolt - has local section reduction formed by groove pre-shortened axially to prestress

摘要

The locking bolt uses a localised step reduction of the bolt cross-section. During fabrication, the bolt is subjected to an axial compression giving a definite axial reduction in length within the reduced zone. The result is an axially prestressed bolt of which the threads bind with those of a nut or tapped bore into which it is screwed. In the case of nuts, the reduction is effected by rectangular section circumferential bore (2) or barrel (3) grooves used singly or in combination (2, 3). There may be a stepped reduction (14) in a barrel dia. in association with a groove (13). The bolt may have a shaft barrel groove with a blind axial bore in the tip. The prestressing or predeformation is effected by rollers.