Reaction Washers to Improve Work Safety and Preload Accuracy with Powered Torque Tools
Bolted joints in wind turbines are subjected to extreme loads due to high forces in axial and transversal directions, for example in rotor blades, turbines and flange connections in the towers. Because the loads are dynamic, the bolted joints are endangered by fatigue failure and self-loosening throughout their entire service life. Consequently, correct bolt dimensioning analysis results in bolted joints with high preloads and large diameters. But even if the preload is accurately calculated it must be reliably and safely applied during assembly using high tightening torques. High preload bolts with diameters of M24 and larger can no longer be tightened manually with a handheld torque wrench. Instead, they require powered torque tools (hydraulic, electric or battery-operated) along with reaction arm support structures to manage the high reaction forces. Finally, the required preload must be maintained during operation where alternating loads, especially in the transversal direction caused by wind loads, vibrations from the rotor, etc., can lead to self-loosening.
By Tobias Hübing, Head of Laboratory, Heico Group, Germany
With the new Heico-Lock Reaction Washers, Heico has found a solution that not only promises excellent locking against self-loosening but also allows reaction-free tightening, which leads to a more accurate, faster, more ergonomic, and significantly safer assembly.
