井底压力下牙轮钻头浮动套轴承性能分析

为了探究井底压力下215.9 mm牙轮钻头浮动套轴承的平衡转速比、摩擦学性能、油膜压力分布随内外间隙比的变化规律,修正了考虑浮动套轴承实际井下环境压力和牙轮钻头密封压差的Reynolds边界条件，利用MATLAB中的PDE Toolbox对浮动套轴承Reynolds方程进行数值求解，分析内外间隙比对浮动套轴承平衡转速比、油膜压力及摩擦因数的影响规律，结果表明：当环境压力为60 MPa、密封压差为20 MPa时，随内外间隙比增加，浮动套平衡转速比呈现先增大后减小的趋势；以轴承的摩擦因数和油膜压力作为综合评价指标，钻头浮动套轴承内外间隙比为2.0时，轴承的摩擦因数较小，油膜压力较高，其轴承综合性能较优；而当浮动套轴承内外间隙比为2.0时，随着环境压力的升高，浮动套轴承的摩擦扭矩和摩擦因数增加，从而加剧轴承的磨损。该研究为牙轮钻头浮动套轴承的结构参数优化及性能提升提供了基础理论支撑。

Analysis of Floating Ring Bearing Performance under Bottom Pressure of Well

In order to investigate the rotational speed ratio at equilibrium,tribological properties,and oil film pressure distribution of the floating ring bearing of an 215.9 mm cone bit with an inner and outer gap ratio under bottom pressure of well,Reynolds boundary conditions were modified by considering the actual downhole environmental pressure of the floating ring bearings and the seal pressure difference of the cone bit.The Reynolds equation of floating ring bearings was numerically solved by using the PDE Toolbox in MATLAB,and the influence of the internal and external gap ratios on the rotational speed ratio at equilibrium,oil film pressure,and friction coefficient of floating ring bearings was analyzed.The results show that when the ambient pressure is 60 MPa and the seal pressure difference is 20 MPa,the equilibrium rotational speed ratio of the floating ring increases first and then decreases with the increase of the inner and outer clearance ratios.Taking the bearing′s friction coefficient and oil film pressure as a comprehensive evaluation index,when the internal and external gap ratio of floating ring bearings is 2.0,the friction coefficient of the bearing is smaller,the pressure of the oil film is higher,and the overall performance of the bearing is better.When the internal and external gap ratio is 2.0,with the rise of environmental pressure,the torque and friction coefficient of the floating ring bearing increase,thereby accelerating the wear of the bearing.This study provides basic theoretical support for structural parameter optimization and performance improvement of cone-bit floating ring bearings under special boundary conditions.