Experimental study on vibration stability in rotary ultrasonic machining of ceramic matrix composites: Cutting force variation at hole entrance

摘要

Rotary ultrasonic machining (RUM) is a superior hole-manufacturing method for ceramic matrix composites (CMC) with reduced cutting force and improved hole quality. Among various processing parameters, sufficient and stable ultrasonic vibration is crucial to guaranteeing RUM effectiveness in terms of cutting force reduction. This study was devoted to investigating the effect of material characteristics on vibration stability in RUM of CMC. The variations of cutting force and ultrasonic power at hole entrance in RUM of C/SiC CMC, quartz glass and sapphire were evaluated. Experimental results on these three materials were all in good consistency with the predicted results of theoretical model, which describes the cutting force effect on ultrasonic power variation without considering whether the machined material was composite or not. Ultrasonic power variation was also used to help identify the effect of thermo-mechanical loading on resonant frequency during RUM of C/SiC CMC. It was revealed that the composite characteristic of CMC didn't affect the effect mechanism of thermo-mechanical load on the stability of ultrasonic vibration. By pre-adjustment of tuning frequency, the indispensable effect of tool wear on cutting force increase in RUM of CMC can be weakened.