Effect of skew angle on the cutting performance and cutting stability of point-attack type picks

Point-attack picks have been widely used in mechanical excavators, such as roadheaders, long-wall shearers, and trenching cutters. Different parameters (i.e., cutting conditions and mechanical properties of the rock) affect the cutting performance of point-attack picks. Among the parameters, skew angle is an important parameter that affects the cutting performance (i.e., cutter forces and specific energy, SE), cutting stability, and wear of the cutting tool. However, few studies regarding the effect of the skew angle on the cutting performance and cutting stability have been reported, and the results of the previous studies are insufficient to conclude the general effect of the skew angle owing to the differences in their results. This study focuses on the effect of the skew angle of point-attack picks on the cutting performance and cutting stability; linear cutting tests were performed for selected rock type with different skew angles and penetration depths. The changes in the cutter forces, SE, ratios of three-directional cutter forces with the skew angle were evaluated. The results showed that the magnitude of the skew angle affected the pick forces, especially the side force component, their ratios, and SE as well. By contrast, the effect of the skew angle direction did not significantly affect the results. The results indicated that the effect of the skew angle (magnitude and direction) on the cutting performance, cutting efficiency, and wear behavior might vary depending on the rock, cutting tool, and other cutting conditions. The results from this study will be useful for better understanding the effects of the skew angle on the cutting performance and stability, which can be used for optimizing the design parameters of mechanical excavators.