油套管特殊螺纹球面对锥面密封性能理论分析

针对油套管特殊螺纹球面对锥面密封结构，基于Hertz接触理论建立了考虑密封面作用扭矩的球面密封接触应力理论模型，研究了球面半径、管体球面弹性模量和密封面作用扭矩对密封面接触宽度和接触应力的影响规律并提出改善球面密封性能的措施，结果表明：随球面半径增加，密封面接触宽度呈抛物线增大，接触应力呈指数减小，且密封面应力分布趋于均匀；随球面弹性模量降低，密封面接触宽度增大，接触应力减小；随密封面作用扭矩增加，密封面接触宽度和接触应力均呈抛物线增大。为提高球面密封性能，建议适当增大球面半径、对球面熔覆合金以降低其弹性模量，同时合理控制密封面作用扭矩，从而增大密封面接触宽度并适当降低密封面接触应力水平。研究结果对优化密封结构、控制上扣扭矩以及提高螺纹密封完整性具有重要理论指导意义。

Theoretical Analysis of Sphere to Cone Sealing Performance for Tubing and Casing Premium Connection

To study the sphere to cone surfaces sealing structure in tubing and casing premium connection,on the basis of Hertz contact mechanics and considering the sealing surface makeup torque, the sealing contact stress model has been established in this paper. The effects of the spherical radius, elastic modulus of sphere and the sealing surface makeup torque on the sealing width and stress were analyzed. And the measures for improving the sealing performance of spherical sealing were proposed. The results show that the contact width increases parabolically,contact stress decreases exponentially and the contact stress tends to be distributed evenly with the increase of spherical radius,the contact width increases and the contact stress decreases with the decrease of the elastic modulus of sphere,both of the contact width and stress increase parabolically with the increase of sealing surface makeup torque. To enhance the sealing performance of spherical sealing structure,we suggest the following measures: a proper larger spherical radius, a lower elastic modulus of cladding alloy sphere and a properly controlled sealing surface makeup torque for sealing width increase and a proper lower sealing contact stress. The obtained results can be of theoretical significance for sealing parameters optimization, makeup torque control and connection sealing integrity improvement.