Research On Drilling-Sampling Performance Based On Interaction Model Between Drill And Lunar Soil

The research is based on the third state of China lunar exploration,aiming at the design of lightweight, low power, high efficiency and high reliability lunar drilling-sampling mechanism. By analyzing foreign universe drilling-sampling technology, based on Soil Mechanics Theory and Geotechnical Drilling Engineering, and combined with lunar soil mechanical and physical properties, the interaction mechanical model between sampling-drill which is the core implementation component of the mechanism and lunar soil was studied. On this basis, by analyzing the parameters of the drilling process, the drilling-sampling performances of lunar sampling-drill in lunar soil were also studied.According to the interaction mechanism between hollow-external-screw drill rod and lunar soil, this paper proposed a equivalent model of the interaction between lunar soil and hollow-external-screw drill rod, the cylindrical rod mode. This model allows the interaction being equivalently analyzed on the outer envelope of the hollow-external-screw drill rod. By kinematic analysis of the micro-element of cylindrical rod mode, the interaction mechanical model between cylindrical rod mode and lunar soil was established. By analyzing the lunar soil stress variation on the surface of cylindrical rod mode in the depth direction, combined with quasi-static analysis of the micro-element of cylindrical rod mode,the analytical model of resistance torque and supplementary thrust of hollow-external-screw drill rod about parameters of lunar soil, rod, and the process of drilling was established.Considering the technics and needs of lunar sampling-drill, this paper proposed a multi-function lunar soil coring bit, which can be on the role of cutting- crushing, chip-removing and isolating-sampling. Via analyzing the interaction mechanism between coring bit and luna soil, and based on failure mechanism and prediction model of critical depth of soil cut by cutting-tool, the failure mechanism of lunar soil cut by coring bit's cutting-tool was studied. By analyzing the actual rake angle of coring bit's cutting-tool, combined with the failure mechanism of lunar soil cut by cutting-tool, the interaction mechanical model between cutting-tool and lunar soil was established, and the analytical model of cutting-tool's Cutting force was also established. By superimposing cutting resistance torque of cutting-tool, the analytical model of resistance torque of coring bit , which is under a constant thrust, was established.Based on the interaction mechanical model between hollow-external-screw drill rod and lunar soil, the influence of the rod and process of drilling parameters to resistance torque, supplementary thrust, power and rate of penetration(ROP) were analyzed. A prediction model of failure angle was also established, which can search the failure angle of lunar soil cut by coring bit's cutting-tool precisely and rapidly.Based on the interaction mechanical model between coring bit and lunar soil, he influence of the failure distance of lunar soil cut by cutting-tool, structural parameters of coring bit, lunar soil to tool friction angle and thrust to resistance torque of coring bit were analyzed. The analysis gives an mathematical description of the interaction between lunar soil and the drill, which sets a theoretical foundation for the load analysis of lunar drilling-sampling mechanism and optimal design of lunar sampling-drill.