Distribution characteristics of rock chips under relieved and unrelieved cutting conditions

Abstract

This study attempts to identify the rock cutting efficiency by several descriptor methods of chip size distribution such as coarseness index, Rossin-Rammler function, and fractal function by sieve analysis. In this context, the characteristic of rock chips produced during relieved and unrelieved cutting tests was examined. The cutting tests were performed by using a conical pick on five sandstones with uniaxial compressive strength varying from 17.91 to 85.98 MPa. Different levels of cutting depth and line spacing were applied in the course of the tests. The specific energy was also calculated. Based on sieve analysis of the chips collected after the cutting tests, the relationships between the distribution parameters of rock chips and cutting parameters including depth of cut, line spacing, and specific energy were investigated. In this context, we aimed to determine the capability of each chip size distribution method and to associate with the rock cutting efficiency, in which some of the major parameters in consideration of the rock cutting process are included. Based on the statistical analyses, several regression equations were proposed according to relieved and unrelieved cutting modes. In conclusion, we found that there are significant relationships between depth of cut and coarseness index, size parameter and distribution parameter. The coarseness index is found to be very reliable to evaluate the cutting efficiency and Rosin-Rammler function is an alternative practical method to be utilized. The rock chips conform to the fractal distribution law. However, the relationship between the fractal dimension and specific energy is weaker compared to the relationship between specific energy and coarseness index in this study.