Development of Simulation Model to Predict Percussive Drilling Performance of DTH Hammer

Abstract

This paper presents the simulation model to predict the percussive drilling performance of the DTH (Down-the-Hole) hammer. First, the pneumatic dynamic model of the DTH hammer is developed in the consideration of mass flow relations representing orifice opening areas of the air tube, the piston and the bit flushing channel. Next, the bit-rock Interaction model is presented in terms of the rock penetration resistance coefficient and unloading constant as well as the piston impact stress wave propagation. Finally, the above models are combined for evaluate the percussive drilling efficiency of the DTH hammer and the combined simulation model is proved through a series of the laboratory tests. As a result, the proposed simulation model can be effectively used for optimizing the design parameters of the DTH hammer considering the rock breaking mechanism.