A grinding force model and surface formation mechanism of cup wheels considering crystallographic orientation

Abstract

As typical two-phase materials, tungsten heavy alloys (WHAs) are widely used in industry owing to their excellent mechanical properties, which also challenge high-quality machining. Grinding can lead to a better machining quality. Prediction and evaluation of grinding forces are essential for grinding quality control and process optimization. This study proposes a flow stress model for the WHA considering the strain hardening, strain rate hardening, and thermal softening effects. The difference between the two phases of WHA was confirmed by calculating the Taylor factors, where the average Taylor factor of the W phase was 3.011 and that of the matrix phase was 3.414. Therefore, dislocations are more likely to be generated and aggregated in the matrix phase during grinding process. The mechanism of subsurface formation during the grinding of WHA was analyzed by transmission electron microscopy. The results show that the plastic deformation layer consists of the fine grain layer, the high density dislocation zone and the substrate. A grinding force model for cup wheels in the vertical-spindle face grinding of WHA considering the grain orientation was developed, and the error between the model and experimental value was within 10%. This model can provide an in-depth understanding of the effects caused by the difference between the two phases during the grinding process, thus provide a theoretical basis for the realization of efficient and low-damage grinding of WHA and other composite materials.