Jackbolts for multi jackbolt tensioners

摘要

Jackbolts for multi jackbolt tensioner embody a thread construction which taper from a maximum diameter adjacent to torque receiving end of the jackbolt when threadedly engaged with a threaded opening in the outer peripheral part of a jackbolt body. The threads of the jackbolt have a different thread pitch than the threads in the jackbolt body and the tooth flank of the jackbolt threads for an angle with the tooth flanks of the thread in the jackbolt body. By this thread construction, there is formed a helical volume of ever increasing size along the jackbolts commencing at a metal to metal relation at the torque receiving end. Stressing of the jackbolt closes the helical volume bringing the threads to a metal to metal load transfer relation. The end of the jackbolts has a protruding central end portion that elastically flattens under stress to reduce torque requirements.