The Research On Ablation Of Bronze-bonded Diamond Grinding Wheels By Acoustic-optic Q-switched Nd:YAG Pulsed Laser

With excellent grinding performance, super-abrasive (diamond and CBN) wheels have a wide application prospect in the field of precision, ultra-precision, high efficiency grinding, grinding automation and difficult processing material forming. Because of the ultrahigh hardness of super-abrasive wheels, the conventional mechanical truing and dressing methods based on force interaction are nearly impossible to meet the requirement for grinding process, which really affects the grinding performance of super-abrasive wheels. A new method which called laser truing and dressing based on thermal interaction, has attracted much attention all over the world.With high peak power, low duty ratio, short pulse duration, high repetition frequency and controllable feature, the acoustic-optic Q-switched pulsed laser is considered to be suitable for truing and dressing super-abrasive wheels. Because laser truing and dressing is virtually based on the mechanism of laser ablation, it's essential to do some research on acoustic-optic Q-switched pulsed laser ablation on super-abrasive wheels.To perform the experiment of pulsed laser ablation on a bronze bonded diamond wheel, an acoustic-optic Q-switched Nd:YAG laser has been developed and tested. Its average power, pulse duration and focal spot are measured. The results show that the maximum average power is 100W, the pulse duration is from 170ns to560ns which depends on the repetition frequency, and the diameter of focal spot is 0.26mm.The absorptivity of bronze to YAG laser with a wavelength of 1.06μm is determined experimentally. The experiment of a single pulse ablation on a bronze-bonded diamond wheel has been carried out. The relationship between the ablated depth and some different laser ablating parameters such as laser intensity, average power, repetition frequency and focal position, has been analyzed. Based on the ablated topographies of the SEM and the theory of laser-matter interaction, the ablation mechanism, that the vapor pressure will cause melt ejection and materials are removed from the target both in vapor and liquid forms, is presented.On the basis of the mechanism, Semak's one-dimensional ablation model has been introduced and the ablated velocity and depth have been calculated. The...