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

Abstract

This paper presents a novel pneumatic Down-The-Hole (DTH) hammer with self-rotation bit used for rock drilling, and the mechanical structure and working principle are mainly covered. A unique mechanism with ratchet and pawl incorporated in pneumatic DTH hammer is proposed for percussion-rotation drilling to break rock. The drill bit can rotate while the drill pipe stays still because of the structure design and reduces the friction between the drill pipe and borehole. Firstly, the rationality of mechanical invention is verified via the finite-element software ANSYS and the numerical simulation of impact dynamics. Moreover, the energy transfer regulation is revealed in the impact process under differential final impact velocity, which can help practical experience in mechanical design. Finally, based on the experimental study on the novel hammer, we found that its function can satisfy the requirement, as well as overall performance, was improved.

Identification of Impact Frequency for Down-the-Hole Drills Using Motor Current Signature Analysis

“…A pneumatic DTH hammer is driven by pressured air coming from an air compressor that provides the energy (by axial pressure) to move the percussion piston that hits the drill bit with a specific impact frequency and energy for rock breaking [5]. As seen in Figure 1, the compressed air also flows through the drill bit, performing hole cleaning by removing the detritus outside the drilled hole.…”

“…Among percussion drilling methods, Down-the-Hole (DTH) drilling is widely used in industrial applications such as mining, blast hole, tunneling, construction, geological exploration, and oil and gas production, among others [2][3][4]. Besides high RoP, DTH drilling provides operational and economic advantages, such as low power losses, accurate hole geometry, and reduced drill string stress [5].…”