Dynamic analysis and design of a ultrasonic/sonic drilling device

This paper presents a dynamic analysis of a piezoelectrically driven vibro-impact drilling device with low down force and power consumption. The drilling device consists of an ultrasonic transducer with a piezoelectric stack, a free flying mass and a drill stem. Excited by the high-frequency vibration of the transducer the free mass oscillates between the horn tip of the transducer and the drill stem. The shock waves in the drill stem caused by the impacts with the free mass affect hard and brittle materials so effectively that small holes can be performed. Based on the sound wave/drilling working characteristics, this system is abstracted to a spring-mass-damping system. Piezoelectrically driven ultrasonic and acoustic energy coupled dynamic behavior is analyzed. The finite element model of the system was established. Through the modal analysis and harmonic response analysis of the system, the design of the system can be carried out. Experiments show that the proposed device can be used to drill a 3 mm diameter and 1.5 mm deep holes for more than 20 seconds. But it is not effective for granite and marble, which have a high rigidity and meticulous texture.