Abstract: 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. 

Key words: cone bit, single metal seal, dynamics model, numerical simulation, sealing performance

摘要： 牙轮钻头的频繁启动以及振动工况直接影响单金属密封的可靠性和工作寿命。基于热-流-固-动耦合场，建立了复杂工况下单金属密封瞬态启动动力学模型，采用有限差分法和Newmark法联合求解润滑方程和动力学方程，考察钻头转速和轴向激励对单金属密封动态密封性能的影响，结果表明：随着钻头不断启动至恒转速阶段，高压（p0=30 MPa）下单金属密封端面液膜沿径向始终呈发散型分布，端面温升在轴向激励下振荡增加至稳定波动，瞬时泄漏率呈正负交替波动状态，幅值远大于稳态泄漏率幅值，特别是当泄漏率为负值时，外径侧泥浆极易侵入密封间隙；单金属密封动态性能随钻头转速和轴向激励载荷增大而进一步恶化。

关键词: 牙轮钻头, 单金属密封, 动力学模型, 数值模拟, 密封性能