A spiral seal method in the lunar regolith for chang'E-5 drill: Seal design and experiment

In the Chang'E-5 mission of the lunar regolith drilling, the gap between the rotary drill bit and the sheath is required to be sealed. In view of the particularity of the lunar subsurface operation, a spiral seal method is proposed based on the analysis of the particles flow state in the clearance, which is made up of the spiral ribs on the inner surface of the drill bit and the friction interface on the outer surface of the sheath. The drilling and sampling simulation is carried out using discrete element method, which verifies the feasibility of the spiral seal in principle. For the test of sealing performance, a test system was developed and drilling and sampling experiments were carried out with several groups of sealing components that have different structure parameters. The test results show that the proposed spiral seal method solves the problem of regolith leakage well in the drilling and sampling process, and it will contribute to the design of the Chang'E-5 drill.