Bulk Motion For Ultrasonic-Assisted Microforming Using Terfenol-D

Microforming requires high-precision motion due to scaling issues. A Terfenol-D transducer was considered to provide bulk motion for micro-extrusion. Because Terfenol-D cannot practically produce the necessary 2.5 mm displacement for this micro-extrusion experiment, a lever system was designed to amplify the output displacement. Compliant joints (flexures) were used to replace conventional bearings, resulting in a flexible, solid-state lever mechanism. By eliminating the backlash and static friction associated with conventional bearings, it should be possible to improve displacement precision as required to meet the geometric tolerance demands of microforming. A chief concern when designing flexure joints that see large amounts of axial loading is compliance, which leads to not only loss of motion but also loss of accuracy as the lever system responds differently under different loads. However, because Terfenol-D already has load-dependent response, this loss of accuracy is moot when coupled with a Terfenol-D prime mover, as it already requires load-dependent control. Preliminary FEM analysis has shown this design to have lever ratio losses of approximately 4% from half load to full load, with lower than predicted stress.