Ultrasonic rock drilling devices using longitudinal-torsional compound vibration

Nasa funded studies have proven that ultrasonics is a viable technology for extraterrestrial drilling. Previous research by the authors has indicated that ultrasonic longitudinal-torsional coupled vibrations may improve rock excavation. In this study, two approaches to the development of torsional output from a Langevin transducer are pursued: coupling the longitudinal mode with a torsional mode and degenerating the longitudinal mode to output torsional motion at the tip using helical flutes cut into the sides of the horn. The amplitude of the output motion and the electrical properties of the horn whilst these modes are being driven are investigated and the findings are validated experimentally.