Surface quality and cylindricity of ultrasonic elliptical vibration–assisted centerless grinding of micro-rod YAG single crystals.

Micro-rod YAG single crystals are the preferred laser crystals for laser gain mediums with a high power. However, brittle fracture and crack damages are easy to occur in the grinding process of micro-rod brittle crystals due to their large length-to-diameter ratio, high brittleness, and high hardness. In this work, the modal, frequency, and harmonic response of the transducer under ultrasonic elliptical vibration are analyzed by using finite element simulation. Then, the mechanical structure of ultrasonic elliptical vibration system was designed and optimized based on the ultrasonic elliptical vibration theory and finite element simulation. To verify the reliability of the transducer, ultrasonic vibration experiments were carried out to measure the resonance frequency, amplitude, and impedance characteristics of the transducer. The vibration synthesis experiments under different phase differences and voltages were performed to verify the rationality of the structural design of the ultrasonic elliptical vibration system. An experimental platform of ultrasonic elliptical vibration–assisted centerless grinding (UEVCG) was developed, and UEVCG tests of micro-rod YAG crystals were performed. The influences of the voltage, phase difference, and pallet inclined angle on surface roughness, peak-to-valley value, and cylindricity of the micro-rod YAG crystals were systematically analyzed. The ultrasonic elliptical vibration parameters were optimized based on the range analysis results of the orthogonal test. The results indicated that ultrasonic elliptical vibration effectively improved the surface quality and cylindricity of the micro-rod YAG crystals compared with traditional grinding. This work will not only enhance the understanding of the ultrasonic elliptical vibration principle, but also provide a technical support for precision and high-efficiency machining of micro-rod brittle materials. [ABSTRACT FROM AUTHOR]