Analytical dynamic model of the drill bit in rock drilling

Abstract：In order to study the force variation of the drill bit in the dynamic process of rock drilling deeply, systemati- cal dynamics analysis was presented in the paper. Differential equations which described the force fluctuations in the process of rock drilling were established and various factors which affect the force fluctuations of the drill bit were also analyzed. Based on the analysis of the process of movement in rock drilling, analytical method for force computation of the drill bit in the dynamic process was given. Analytical calculation model of penetrating force and cutting force in the dynamic process was derived respectively. Studies show that the force of drill bit is closely related to its motion state ; the average penetrating force and cutting force in the dynamic process increase with the increasing of penetration speed V in the case of the other conditions remain unchanged. Calculation results show that the analytical dynamic model is more precise than the traditional method of static calculation model compared with experimental measurements, and more conducive to be a intuitive and laconic guidance in engineering practice.