Influences of high-frequency vibration on tool wear in rotary ultrasonic machining of glass BK7

摘要

This investigation represented a fundamental research on the potential effects of the ultrasonic on the tool wear involved in rotary ultrasonic machining (RUM) of glass BK7 process. Comparative examinations of the profile deviations and abrasive morphologies of the two diamond tools produced with and without ultrasonic were conducted with optical microscopy, 3-D optical profiler, and scanning electron microscopy (SEM), and their resultant effects on the dimension accuracy and the surface quality of the machined component were also explored. Giving consideration to the strain rate effects of the material provoked by the ultrasonic superposition, the split Hopkinson pressure bar (SHPB) experiments were employed to validate their effects on the dynamic mechanical properties of glass BK7. Afterward, the active mechanisms of abrasive splitting were investigated theoretically. It was found that the ultrasonic superposition by means of suppressing the abrasive dislodgments reduced the profile deviation of the diamond tool, hereby improving the dimensional accuracy of the component. Furthermore, superimposing an ultrasonic vibration would prolong the service life of the abrasives, and this wear-resistant capacity would increase the amount of the working abrasives, thus improving the specimen surface quality. The morphological observations of the abrasives revealed that ultrasonic superposition led to the splitting characteristics converted from transgranular cracking (macrosplintering) to conchoidal fracture (microsplintering). The dynamic mechanical properties of glass BK7 would increase its Young's modulus, which would reduce the crack nucleation depth in the abrasive, leading the conversion of the splitting appearances.