Investigation of the longitudinal-flexural resonating spindle in ultrasound-assisted grinding of SiCp/Al composites

Abstract

Rotary ultrasonic machining is a cost-effective and precise machining method for hard and brittle materials. Aiming at processing SiCp/Al composites, a rotary ultrasonic grinding spindle is proposed in the present study. Expressions were established to calculate the displacement, rotation angle, bending moment, and shear force of the vibrating elements based on the Mindlin moderately thick plate theory. Combining continuous and boundary conditions of vibrating elements with the proposed expressions, the vibration model and frequency equation of a longitudinal-flexural resonating transformer with a large load were established. Then two transformers were designed according to the frequency equation. The resonant characteristics of the transformers were studied using finite element analysis, impedance analysis, and ultrasonic resonance experiments. The obtained results show that the maximum deviation between the resonant frequency and the design frequency of the transformers was 4.95%. Moreover, the maximum deviation of the positions of the pitch circles was 6.51%. It is concluded that the proposed designs have high accuracy. Finally, the orthogonal single-factor experiments of SiCp/Al composites were performed with and without ultrasound. The obtained results show that introducing ultrasonic vibrations significantly reduces the grinding force and the surface roughness while improving the surface quality of the SiCp/Al workpiece. The present study is expected to provide experimental fundamentals to further improve the structure of the grinding spindle, optimize process variables of ultrasound-assisted grinding, and improve the processing efficiency.