Y-ring’s mechanical behavior during sealing cap’s assembly process based on the pressure core sampling for seafloor drill

Abstract

In order to expand the application of seafloor drill in the field of natural gas hydrate exploration, a pressure core sampling technical scheme suitable for seafloor drill operating conditions is proposed. The assembly action principle of sealing cap in the scheme is introduced. The factors affecting the sealing reliability during the assembly of the sealing cap are analyzed. A geometric model of the sealing structure is established. The variation regular of the max von Mises stress is discussed during the assembly process. The relationship between the assembly parameters and the maximum von Mises stress is clarified. The parameters optimization scheme is proposed and verified by experiments. The results show that: the Y-ring’s maximum von Mises stress variation trend has five stages and the maximum von Mises stress produces peak stress in the rising stage, excessive interference and friction factor make the peak appear in the fluctuation stage in advance, the lead angle within 10°–30° has little effect on the maximum von Mises stress peak value, the axial displacement speed affect the growth rate and amplitude of the maximum von Mises stress curve, the drilling tool’s pressure loss ratio is within 8% under the 10–40 MPa after 6 h.