Estimation of the Maximum Angular Position for Cutting Roof Rock Material

Abstract

In the mining and construction industry, the picks on an excavation machine often need to cut different rock types within the same drum revolution. If a rock type is much stronger than others, cutting this type of rock will often have a significant impact on the failure rates and performance of the picks and excavation machine. Therefore, it is necessary to understand the maximum angular position for cutting this type of rock, especially when it is hard rock. The accuracy of the maximum angular position for cutting the hard rock in a drum revolution affects the accuracy of the analysis of the maximum depth of cut for cutting the hard rock. It also affects the drum balance. In this paper, a method is developed to accurately calculate the maximum angular position for hard rock cutting based on the roof rock cutting in coal mining. In some cases, a simple but approximate method can be used to estimate the maximum angular position. One such case is when the strength differences between different rock types are not significant. The comparison of the influences of the accurate results on the pick performance analysis with that of the results given by the approximate method is also conducted. It shows that when the ratio of the height of the roof rock being cut to the tip-to-center cutting radius is 0.5, the maximum depth of cut in a drum revolution is less than 73 mm and the tip-to-center cutting radius is greater than 700 mm, the relative analysis error caused by the approximate method is less than 6%.