Design of a piezo-actuated disassembly tool for seized threaded fasteners

Disassembly is the first and thus crucial step in remanufacturing, maintaining and repairing products. Due to varying product conditions, disassembly requires manual tools. An example of this is the loosening of threaded fasteners used in aircraft engines. These fasteners, connecting its parts, seize during the usage, i.e., the harsh thermal and mechanical conditions to an unknown extend. Inappropriate loosening strategies can cause these to break off, leading to further unplanned tasks, wasting time, labor and capital. In this article, we present a piezo-actuated hand-held tool which enables an adaptable and non-destructive disassembly of seized threaded fasteners. Monitoring the actual torque during disassembly ensures that material limits are maintained. Based on the measured torque, vibrations are actively applied to the bolted joint, adapted to the joint’s condition. The use of multivariate vibrations breaks up seizure and reduces friction during unscrewing. This prevents damage, such as screws breaking off, saving valuable resources such as materials and labor time. This article outlines the developed design and control of the handheld vibration assisted disassembly tool.