| The mirror efficient machining of brittle materials is an important branch of ultra-precision machining technology, which has great significance for development on the aerospace, defense industry, information, microelectronics and optoelectronics. An efficient mirror machining technology which combines precision efficient ultrasonic vibration assisted grinding and ultra-precision ELID grinding is proposed in this paper. Taking ZTA nanocomposite ceramics as research object and based on indentation fracture mechanics and electrolysis principle, the theoretical and experimental studies of efficient removal mechanism and surface quality are conducted for ultrasonic vibration and ELID combined grinding which is funded by the National Natural Science Foundation of China. The studies include the following aspects:(1) The internal grinding device of ultrasonic vibration and ELID combined grinding is developed through the transformation of existing laboratory equipment. Experimental studies of acoustic system characteristics are conducted, which show that loads have some impact on acoustic system parameters such as resonant frequency, quality factor, dynamic resistance and dynamic inductive. However, the test will not be affected by that due to the small grinding force of the test. Electro-discharge precision truing and dressing tests are conducted. The results showed that wheel’s runout can reach 2μm and the oxide film growth well during dressing. That meets the ultra-precision test requirements.(2) Based on ceramic material removal mechanism of ultrasonic vibration and ELID combined grinding, the materials removal rate mathematical model is established and the verification experiments were conducted. The results show that the material removal rate of ultrasonic vibration and ELID combined grinding is higher than ELID grinding.(3) Based on indentation fracture mechanics and electrolysis principle, the mathematical model of grinding force for ultrasonic vibration and ELID combined grinding was proposed with the kinematics analysis for single abrasive grit with ultrasonic vibration. The effects of grinding parameters, ELID electrical parameters and acoustic parameters on the grinding force were explained, which also explains the reason ultrasonic vibration and ELID combined grinding force is less than ELID grinding force.(4) The surface quality of ultrasonic vibration and ELID combined grinding was studied from the aspects of surface roughness, and the effect of different machining parameters on the surface quality is obtained. The results show that the surface quality of ultrasonic vibration and ELID combined grinding is better than ELID grinding.The results of this study is beneficial to reveal efficient mirror machining mechanism for ultrasonic vibration and ELID combined grinding, and improves the efficient mirror machining theory of hard and brittle materials. That has great theoretical significance for the development of high-tech sophisticated technology such as national defense. |
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