Longitudinal-torsional complex-mode ultrasonic actuator for vibration-assisted drilling of CFRP

Abstract

Carbon-fiber-reinforced plastic (CFRP) composites are inten-sively used in aircraft and aerospace industry thanks to their superior properties. Comparing to the conventional drilling (CD), vibrationassisted drilling (VAD) is a novel machining technique suitable for drilling CFRP. Still, multi-mode excita-tions with elliptical locus and low vibration performance limit the applications of current VAD schemes for CFRP. To over-come these limitations and improve the overall performance, an innovative longitudinal-torsional complexmode ultrasonic vibration-assisted actuator with single excitation and an ellip-tical locus is presented employing a piezoelectric transducer and a stepped horn with spiral grooves. The proposed actu-ator is specially designed to deliver elliptical vibration and assure high vibration performance of a tool tip. Analysis of the actuation mechanism for the longitudinal-torsional com-posite vibration mode is discussed, and its simplified model is developed. A detailed design process of this actuator is given. Its vibration characteristics are verified with both finite-elem-ent simulation and experimental modal analysis using a swept sine test. It is demonstrated the developed prototype achieved longitudinal-torsional elliptical vibration. To validate the machining performance of the actuator, two groups of drilling experiments were performed. These indicate that the proposed actuator is capable of drilling CFRP with improved machining performance.

Investigation on cutting temperature of CFRP in robotic rotary ultrasonic drilling with minimum quantity lubrication

“…[1][2][3][4][5][6] In the assembly process of CFRP parts, millions of connection holes need to be drilled on body materials. [7][8][9] Carbon fibers of CFRP may cause poor machinability because of its high hardness and abrasiveness, resin matrix of CFRP is easy to exceed the glass transition temperature and *Corresponding author. E-mail address: zhengkan@njust.edu.cn(Kan ZHENG)…”