Transient Start-up Dynamics Model and Sealing Performance of Single Metal Seals in Cone Bits

The reliability and service lifes of the single metal seals were directly affected by the frequent start-up and vibrations of the cone bits during operations. The transient start-up dynamics model of single metal seals under complex working conditions was established based on the thermal-fluid-solid-dynamic coupling field. The lubrication equation and dynamics equation were solved by finite difference method and Newmark method. The effects of the bit speed and axial excitation on the dynamic sealing performance of single metal seals were investigated. The results show that as the bit starts up to constant speed, the liquid film on the end faces of single metal seals always presents a divergent distribution in the radial direction under high pressure condition(p0=30 MPa). The interface temperature rise increases oscillatingly and reach a stable fluctuation under the axial excitation. The instantaneous leakage rate fluctuates alternately between positive and negative, and the amplitude is much larger than that of the steady leakage rate. Especially when the leakage rate is negative, the mud on the outer diameter side of sealing rings may easily invade the sealing gap. With the increase of bit speed and axial excitation load, the dynamic performance of single metal seals is further deteriorated. © 2022, China Mechanical Engineering Magazine Office. All right reserved.