Design and fabrication of a novel vibration-assisted drilling tool using a torsional magnetostrictive transducer.

In this paper, a vibrational drilling tool using a magnetostrictive torsional transducer is designed and fabricated. The torsional transducer is a hollow cylinder, which is made up of "2 V permendur." Passing an alternating current through the material creates a variable circular magnetic field and exciting a coaxial coil with a direct current generates a constant axial field in the material. According to the Wiedemann effect, the magnetic domains of the material rotate helically in the direction of the external field and cause a shear strain in the material. To utilize the maximum torque and amplitude of the transducer as well as to maintain the transducer's resonance conditions, a wave transmitter is designed to connect the transducer to a drill bit. The dimensions of the vibrating tool are calculated theoretically and verified by the finite element software of COMSOL. Friction couplings are designed to connect the transducer, wave transmitter, and the drill bit. This torsional drilling tool is used for drilling of aluminum workpieces. The tests show that torsional vibrations reduce the required drilling torque by 60% in comparison to conventional drilling. In addition, usage of the torsional vibrations has the effect of the chip breaking, improving the accuracy of the hole size by 55.4%, and reducing the drilling surface roughness by the percent of 25.3% in comparison to conventional drilling. [ABSTRACT FROM AUTHOR]