Preloading for lockbolt installation

摘要

A process and apparatus for installation of a lockbolt to fasten together an assembly of at least two parts having a viscous fluid such as adhesive or sealant in the interface between the two parts, inserts a lockbolt into aligned holes through the two parts and exerts a pulling force of a predetermined intermediate magnitude on the lockbolt while reacting the pulling force against opposite sides of the assembly to exert a compressive force on the assembly to squeeze the fluid out of the interface. The intermediate pulling force is maintained for a precisely timed dwell period based on an optimal period for that fluid and that temperature. After the dwell period, the pulling force is increased in magnitude while simultaneously swaging a collar into threads on the lockbolt to secure the collar on the lockbolt and secure the lockbolt in a state of tension in the hole in the assembly. The pulling force magnitude continues to increase said until the pintail breaks off the lockbolt.