Simulation and experimental study on the influence of bit structure on rock-breaking by high-voltage electro-pulse boring

Abstract

High-voltage electro-pulse boring (EPB) rock-breaking can produce tensile damage, which has significant advantages in deep hard rock drilling. To develop a bit with high drilling efficiency and low energy consumption has become one technical problem in EPB technology. First, based on the electrode structure arrangement and the previous research on EPB mechanism, this paper developed three kinds of electrode bits with a coaxial cylindrical structure, electrode cross structure and multi-electrode pair structure. Second, it established a numerical simulation model of EPB with different-structure bits, and analyzed the influence of different structural arrangements on EPB. Based on the idea of parametric design of electrode bit parts, the influence of the high-voltage electrode shape on EPB was further analyzed. Finally, it built the EPB test units, and carried out the EPB tests of the bits with different structures, and made clear the influence of different structural arrangements on EPB. Compared with EPB experimental results, the bit with a coaxial cylindrical structure had the best drilling effect, followed by the one with a multi-electrode pair structure, and then the one with an electrode cross structure with the same setting of electrical parameters. At the same time, this paper made the EPB experiments on different high-voltage electrode shapes by using a coaxial cylindrical electrode bit. The results showed that the bit with a conical high-voltage electrode had the best drilling effect, followed by the one with a spherical high-voltage electrode, and then the one with a flat bottom high-voltage electrode. Through the simulation analysis and experimental study, this paper concluded the influence law of the bit structure on EPB. The application of the findings was helpful to guide the design of electrode bit structure, reduce energy consumption, and improve drilling efficiency.