Design and flow performance analysis of sediment core drilling tools for seafloor drill

Submarine sediment serves as a crucial archive for documenting deep-sea geology, biotic processes, and environmental transformations. In this article, a wire-line coring technology scheme is proposed to meet the requirements of the split suction drilling principle for seafloor drill. Mathematical models are established to predict the internal pressure changes of the drilling tools during press-in coring and rotary drilling. The influence of drilling parameters and drilling tools structural parameters on flow performance is analysed. The drilling performance of this scheme is tested through engineering applications. The following results can be obtained: During suction press-in coring at speeds of 20 mm/s-50 mm/s, the water pressure difference ΔP1 stabilizes when the single key way area S2 exceeds 30 mm2. For rotary drilling with flushing fluid flow rates ranging from 80 L/min to 160 L/min, the water pressure difference ΔP2 stabilizes when S2 exceeds 120 mm2 and the drill bit water hole diameter d10 exceeds 6 mm. Under conditions of high pump capacity 160 L/min and rotational speed 700 rpm, the pressure difference stabilizes when S2 values of 180 mm2. The average collection rate of sample in submarine sediment layers exceeds 87%.