Experimental Study on the Vibration Response of a Jackleg Hammer Drill

Abstract

This thesis presents an experimental investigation into the response of mechanical vibration in jackleg hammer drills during underground rock drilling operations. While previous studies have primarily focused on vibration exposure at the handle or operator interface, this work analyzes vibration transmission through the full structure of the drill to better understand internal component behavior under realistic working conditions. Vibration data were collected using uniaxial accelerometers mounted on four key components-the fronthead, main cylinder, backhead, and handle, with measurements recorded along three spatial axes. Testing was conducted in operational environments, capturing variations across distinct drilling phases, including collaring, sustained drilling, and retraction. The acquired data were processed using time and frequency domain methods, including Fast Fourier Transform (FFT) and Root Mean Square (RMS) analysis. Results revealed significant directional dependence of vibration, with the axial (X-axis) component exhibiting the highest amplitudes during drilling. During collaring, when the drill bit lacks a guiding groove, vibration increased across all axes. A resonance condition was observed at approximately 142 Hz in the handle assembly, suggesting localized amplification potentially due to dynamic interaction between structural components. By characterizing dominant frequencies, directional behavior, and phase-specific amplification trends, this study provides a system-level understanding of vibration response in jackleg drills. The findings establish a foundation for future research aimed at developing targeted design improvements and vibration mitigation strategies to enhance operator safety and tool performance.