Soil chip convey of lunar subsurface auger drill

Celestial body subsurface drilling and sampling is a key aspect of near-earth exploration projects. In these sample return missions, the auger drill system is universally used due to the environment and detector load limits. The common failure that the auger faces is chip chocking, which can raise the torque and cause the drill to stick. This paper builds auger drill models describing chip flow in the auger groove to balance geometric parameters, functional capability, and reliability. The features of chip flow are summarized and verified by a series of discrete element method simulations. In contrast to previous auger design, a convey capability factor is defined to indicate the auger’s chip removal capacity, and the role of pitch angle and other parameters is assessed through motion analysis of the lunar soil flow process. The theory is verified by testing the drill penetrating speed limit, which combines drill geometry and motion parameters. This work provides a new method for design and optimization of low speed auger drill systems and research on particle flow with small scale mechanical constraints.