Prediction Model of Drilling Performance for Percussive Rock Drilling Tool

Abstract

This study suggests a method for quantitatively estimating the drilling performance of the down-the-hole (DTH) hammer during percussive drilling of rock surfaces. A pneumatic dynamic model of the DTH hammer was developed that considers the mass flow rate relations representing the orifice opening areas of the air tube, the piston, and bit flushing channels. A drill bit motion model was developed to represent the dynamics of a drill bit impacted by a dropped piston and explain the impact stress propagation and rock-crushing mechanism. The rock-crushing effect of the drill button bit was measured through a piston drop test. The pneumatic hammer model and drill bit motion model were then combined in a prediction model to determine the impact efficiency according to different rock types (i.e., soft, medium-hard, and very hard). The drilling efficiency was defined as the input value of the prediction model, which was used to simulate the drilling performance of DTH hammers considering the rock type and dynamic effect of the drill bit. Finally, the simulation results were compared with the results of in situ drilling tests for verification.

Simulation and Analysis of a Split Drill Bit for Pneumatic DTH Hammer Percussive Rotary Drilling

“…The fluid flow through the split reverse circulation bit follows the laws of physical conservation, including the laws of mass conservation, momentum conservation, and energy conservation [29,30]. The general governing equations of the above conservation laws are as follows:…”

Nonlinear Dynamics of Vibro-Impacting Indenter

“…Zhabin et al [13] used a set of variational equations and finite difference equations to model the interaction of pistons and tools in the percussive drilling of rocks. Kim et al [14] used a prediction model for estimating the impact efficiency of a percussive rock drilling tool. Song et al [15] considered the energy transmitted from the bit to the rock in percussive drilling, and this was compared to a drop test.…”

Design optimization and feasibility analysis of pneumatic DTH Hammer with self-rotation bit

“…Based on the finite element method, Liu et al analyzed the rock breaking and penetration rate (ROP) rise mechanism of rotary percussive cutting [9]. Kim et al developed a pneumatic dynamic model of DTH hammer to predict drilling performance and validated the model through laboratory tests [10,11]. Meng et al solved the problem of reasonable deviation and improved drilling efficiency by using the KQC series of air hammers [12].…”