Numerical and experimental investigation of the impact fragmentation of bluestone using multi-type bits

•Orthogonal experiment was utilized to analysis impact fragmentation.•Some experiments were developed to study the performance of various types of drills.•This paper obtained the optimal combination of working parameters.

In this work, a numerical model of impact fragmentation was established based on the finite element method to investigate the problem of low efficiency and high power consumption associated with an impact fragmentation apparatus. First, the main parts of the impact fragmentation apparatus were simplified and a numerical model of the piston-bit-rock system was constructed. The orthogonal experimental design method was used, and the results were analyzed using range and variance analyses. Finally, the numerical model was verified and an optimal combination of the working parameters was obtained from experimentation. The results show that the order of factors influencing the impact fragmentation apparatus's working parameters are impact energy, rotational speed, feed pressure, impact frequency and bit type. Moreover, impact energy has a significant effect on the drilling velocity, rotational speed and feed pressure has a moderate effect on the drilling velocity; the influence of the impact frequency and bit type on the drilling velocity is not obvious. Furthermore, the optimal combination of working parameters for the impact fragmentation apparatus in this study includes an impact energy, impact frequency, rotation speed, feed pressure and bit type of 100 J, 50 Hz, 270 rpm, 3500 N and 7-button bit, respectively. It is effective to increase the impact frequency and rotary torque to improve the rock-breaking efficiency of the impact fragmentation apparatus.