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The objective of this study is to systematically examine the drilling efficiency and performance of various core drill bits in lunar rock formation using the discrete element method (DEM) and drilling experiments conducted in a lunar vacuum environment. This research aims to establish a scientific foundation for selecting core drill bits for lunar deep drilling operations. To achieve this, four distinct core drill bits were designed. Subsequently, a numerical model of lunar rock was constructed and the load characteristics and drilling efficiency of each bit during the drilling process were analyzed using DEM. Drilling and coring tests were then performed in both atmospheric and lunar vacuum environments, thereby validating the numerical simulation results and providing a comprehensive evaluation of the actual performance of the core drill bits. The study revealed that the carbide-tipped core drill bit with octagonal prisms design resulted in the core disking due to a significant rise in temperature, underscoring the critical importance of temperature control in maintaining core integrity. While the carbide-tipped core drill bit with cutting edges demonstrates exceptional drilling efficiency and coring quality, its inherent fragility and rapid wear of the cutting edges present considerable challenges for practical application. The diamond-impregnated core drill bit is unsuitable for drilling operations under lunar loads and power limitations due to its high weight-on-bit (WOB) requirements. In contrast, the PDC core drill bit exhibits excellent drilling stability, low rotary torque requirements, minimal temperature-rise effects, and significantly enhanced penetrating speed in the lunar vacuum environment, making it a recommended choice for lunar rock drilling. This study provides substantial theoretical and experimental support for the development of lunar drilling equipment and the formulation of effective drilling strategies.
Highlights
An improved HMB contact model was used in the numerical simulation calculations.
Simulated lunar rock drilling tests were conducted in both atmospheric and vacuum environments, and a comparative analysis was performed with the numerical simulation results.
Among the four self-designed drill bits, the PDC bit was identified as the most suitable for lunar rock drilling through comparative selection.
Details
Mechanical properties;
Lunar rocks;
Drilling machines (tools);
Diamond drills;
Performance evaluation;
Drills;
Rock;
Diamond tools;
Drilling equipment;
Efficiency;
Temperature control;
Rocks;
Prisms;
Fragility;
Discrete element method;
Cutting tools;
Diamonds;
Coring bits;
Cutting wear;
Diamond machining;
Geology;
Comparative analysis;
Tensile strength;
Drill bits;
Core drilling;
Moon;
Numerical models;
Core sampling;
Mathematical models;
Torque;
Design;
Physical properties;
Drilling;
Cutting
1 Shenzhen University, State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, Shenzhen, China (GRID:grid.263488.3) (ISNI:0000 0001 0472 9649); Shenzhen University, Institute of Deep Earth Sciences and Green Energy, College of Civil and Transportation Engineering, Shenzhen, China (GRID:grid.263488.3) (ISNI:0000 0001 0472 9649); Shenzhen University, Shenzhen Key Laboratory of Deep Underground Engineering Sciences and Green Energy, Shenzhen, China (GRID:grid.263488.3) (ISNI:0000 0001 0472 9649)