Prediction of undeformed chip thickness distribution and surface roughness in ultrasonic vibration grinding of inner hole of bearings

Ultrasonic vibration grinding differs from traditional grinding in terms of its material removal mechanism. The randomness of grain-workpiece interaction in ultrasonic vibration grinding can produce variable chips and impact the surface roughness of workpiece. However, previous studies used iterative method to calculate the unformed chip thickness (UCT), which has low computational efficiency. In this study, a symbolic difference method is proposed to calculate the UCT. The UCT distributions are obtained to describe the stochastic interaction characteristics of ultrasonic grinding process. Meanwhile, the UCT distribution characteristics under different machining parameters are analyzed. Then, a surface roughness prediction model is established based on the UCT distribution. Finally, the correctness of the model is verified by experiments. This study provides a quick and accurate method for predicting surface roughness in longitudinal ultrasonic vibration grinding.