Loading...
Evaluation and optimization of the performance of radial cutting tools on borer miners in evaporitic rocks
Ishaq, Muhammad
Ishaq, Muhammad
Citations
Altmetric:
Advisor
Editor
Date
Date Issued
2024
Date Submitted
Collections
Files
Research Projects
Organizational Units
Journal Issue
Embargo Expires
2025-11-26
Abstract
Mechanical excavation is the dominant mode of operation in underground mining and tunneling in low- to medium-strength rock types. Drag-type cutting tools used on related machines vary from radial tools for very soft and non-abrasive rocks to point attack or conical tools, also known as pick cutters, in medium-strength and more abrasive rocks. Tool wear and maintenance are important parts of the operation, as they may impact production rates due to excessive wear and inefficient cutting processes, as well as negatively impact machine utilization, resulting in reduced production per shift or per day.
This study investigates the performance of radial rock cutting tools used on borer miners, focusing on the cutterhead profiles typical to gage regions of borer miner rotors, as well as the rate of wear and resulting cutting forces. Analysis of field data was used to assess the impact of tool wear on machine performance and to establish testing criteria for full-scale linear cutting machine (LCM) tests to simulate the cutting conditions experienced on the rotors. Beyond a standard LCM test, this study introduced a tilted-bit LCM test procedure to simulate the gage area of the cutterhead, where bits are installed at high tilt angles, as a means to develop a realistic understanding of cutter-rock interaction in the gage region. A 3D scanner is utilized to create point cloud data of the rock surface to evaluate the surface characteristics of the rock and enable assessment of the ridge buildup area between the cuts. Through a combination of analyses and computer modeling techniques, a comprehensive methodology is established to facilitate a detailed quantification of operational parameters influencing cutter-rock interaction, affecting performance and cutting tool lifespan.
The study reveals that the standard LCM testing method oversimplifies the complex dynamics at variable axial spacing at higher tilt angles. The side force component is significant at higher tilt angles and is expected to contribute to frequent tip failures and even exceed radial bit design limits. Findings show cutting forces vary substantially when alternating sequences due to changes in rock exposure and relief timing.
Integrating 3D scanning in rock cutting helps surface characterization with improved precision and quantifies supplemental factors like overbreak volumes, ridge heights, and breakout angles, complementing traditional measurement and analysis of cutting forces and product grain size distribution assessments. Integrating these additional metrics with standardized specific energy and particle size distribution evaluations, as well as simulated wear levels of cutting tools, provides better insights into cutter-rock interaction. These capabilities provide the means to develop proper strategies for optimizing operation and cutterhead design.
A validated corner-cutting evaluation methodology has been introduced to facilitate accounting for operational factors in addition to typical cutting geometry. To incorporate operational parameters, input variables are carefully chosen to accurately reflect the cutting scenario, representing the rock encountered by the bit either directly or indirectly. These geometric factors dynamically adjust in response to variations in the rate of machine advance. Various modeling techniques were considered, each utilizing a different set of input parameters. The selection of the models presented in this study was determined by their ability to accurately capture the variability across all three orthogonal components of the cutting force.
The machine performance prediction model introduced at the EMI of CSM is based on the cumulative cutting force consumption by the individual cutting tool on the cutterhead with respect to its position and orientation. The model allows for estimation of the cutting forces for a given bit based on the measured values through full-scale LCM tests. This allows the model to incorporate full-scale testing results into the performance estimation and predict the machine's instantaneous performance, considering the specific wear level of the cutting tools on the cutterhead. A key update to the EMI-CSM modeling concept allows performance prediction with progressive wear and its corresponding effects on machine performance parameters. This can be seen as a step forward in cutterhead wear modeling, particularly when assessing machine performance in constant geological conditions. This improvement ultimately refines the modeling process, where, through simulation of the cutting process, one can develop optimal operational parameters and bit/cutter management strategies and address related scheduling issues.
Associated Publications
Rights
Copyright of the original work is retained by the author.