Research on the Thermal Features of the Drilling Process Under the Simulated Lunar Surface Environment

Abstract

According to the requirements of the lunar surface sampling task, The lunar regolith sampler need to drill under vacuum conditions, and realize the continuous drilling without aided-cooling medium. It is very easy to cause a rapid temperature rise on bit, which resulted in making effect on the reliability of the sampling task. Thus, in order to study on the thermal characteristics of the bit in drilling process, the cutting and friction mechanism between blade on bit and the lunar soil is analyzed in this paper. A temperature rise model of bit is established, and the main factors that influence the temperature rise of the drill bit are obtained. According to the lunar vacuum environment, the 2 m drilling depth lunar soil simulant is prepared, and its vacuum degree below 10 Pa, simultaneously, the thermal feature drilling tests are performed. The experimental results show that there is a strong positive correlation between the temperature rise and the weight on bit at the front of the drill bit, and the correlation on bit torque is weak. The correlation coefficient of the model of the temperature rise prediction is modified based on the test results. The fitting curve of the temperature rise is obtained, and the comparison of the results between fitting and test has been carried out. The qualitative analysis of the thermal characteristics of the bit in drilling process is acquired.

Keywords

lunar environment / vacuum condition / drilling thermal feature / temperature rise model