Research On Impact Drilling Of Lunar Surface Drilling And Sampling

Drilling and sampling on lunar surface are facing problems like: low gravity, high vacuum, and unknown mechanical properties of lunar soil. To compensate for the shortage of available drilling pressure, percussion drilling would be used in the lunar surface drilling and sampling process. Limitated to rocket’s launching capability and other factors, the sampling mechanism should meet the requirements of lightweight, low power, high efficiency and high reliability. The reliable operation of the impact drill sampling system is most important in the entire drill sampling task. This article takes the percussive drilling system of the drill sampling mechanism as the reasearch object and carried researches on the percussive drilling process in lunar surface drilling based on engineering considerations.Firstly, the operating characteristics of spring-exciting block of lunar surface drill sampling mechanism has been studied by dynamic simulation and theoretical analysis. The impact energy, impact velocity and impact force during the impact action has been theoretically derivated. The result of theoretical analysis is validated by ADAMS dynamic simulation, it indicate that the exciting drive mechanism can perfectly realize the impact of incentives.Secondly, a model for stress wave transfer characteristics of drill pipe under the action of impact has been built and analyzed by using of one-dimensional wave dynamics method. The incident stress waveform produced by the excitation block has been given by theoretical analysis, which also gives stress wave energy transmissivity and stress wave transmissivity in varying wave-impedance condition. The process of rock drilling has been analysed and the results showed that the rebound of the excitation block will occur in the drilling process; the influence of impact action passing along the core tube was also analyzed, results show that the smaller the core tube wave-impedance, the less disturbed by the impact.Finally, numerical simulation has been conducted for the dynamic process of the lunar surface drilling based on explicit finite element method. B y establishing excitation block-drill pipe finite element model, the stress wave energy transfer property has been studied. The results show that energy transmissivity,transmissivity of stress wave deduced by the one-dimensional stress wave theory agree with what calculated by the finite element method and the rebound of the excitation block will decrease the energy transmissivity of stress wave.