Optimization and Test ofMetallic Seal Structure for High-Speed Bit

Liu Yang1.²Li Wenqi1She Yang Zhou1

（1.SchoolofMechanicalEnginering，Yangtze University;2.SichuanProvincialKeyLabofProcessEquipmentandControl）

Abstract：The influence of bit protective gasket on seal structure has been less studied，and there is a lack of structural optimization and experimental study results of gasket.In this paper，test and finite element methods were combined to analyze the influences of parameters such as press-fit force and specific pressure of end face on the mechanical behaviors and sealing performance of metalic seal system as well as the defects of the existing gasket structure. Then，a new type of gasket was designed，and the original structure was improved. The results showthat compared with the original gasket structure，thenew one has an increased effctive contact area withthe energy supply ring and the end face of metallic seal ring，relatively uniform stress distribution with less stress concentration，and smooth deformation.Moreover，the contact pressure meets the requirements for sealing function at the maximum displacement，and wear can also be effectively reduced.The mechanical performance testand unit leakage testresults showthat the new gasket structure isqualified forthe sealing ofhigh-speed rollercone bit.The studyresults provide theoretical and testsupport for improving thesealing performanceand service lifeof highspeed bits.

Keywords： high-speed bit;single metallc seal structure；energy supply ring;sealing protection pad; material test；finite element analysis;performance test

0 引言

随着石油天然气开采朝着深海和深部地层发展，需要大量使用高速长寿命钻头。单金属密封具有密封性能稳定、耐高温高压和耐磨损的特点，可有效防止钻头密封系统泄漏，还可承受极端环境下的压力和温度变化。为了延长单金属密封钻头的工作寿命，亟需推动单金属密封性能理论研究和试验研究进程[1-2]。

目前，国内外学者针对金属密封已开展相关理论和试验研究。王伟等[3-4研究出适用于柔性钻杆球面密封的异形密封圈，且能够实现良好的密封效果。ZHANGY.等[5基于ANSYS的结构-热耦合数值模型研究SEMS2在高温高压条件下的密封性能。张毅等[利用有限元法分析第二代单金属密封端面接触应力分布和磨损形貌，针对高压工况进行了结构参数优化设计。ZHANGJ.等和马艺等[8研究了双金属密封（DMES）中橡胶圈的应力分布及磨损规律，研究结果表明，钻头密封结构处存在应力集中和压力分布不均匀现象。ZHANGY.等[9-I]分析了单、双金属密封系统在流体压力、压缩比、金属密封环角度和热载荷影响下的密封性能。张敏佳等[12]建立了单金属密封间隙液膜计算模型，研究动态工况下环境压力对单金属密封性能的影响，提出密封圈磨损预测方法。ZHAOY.等3通过将金属橡胶（MR）材料与轴向开口C形夹套相结合，提出了一种金属橡胶密封方案，研究了不同工况时橡胶圈的密封特性及密封失效位置，提出增强橡胶圈密封性能的思路。

现有文献较少研究钻头密封保护垫对密封结构的影响，缺乏密封垫的结构优化和试验研究成果。……