高强度大通孔钻杆接头圆锥梯形螺纹的有限元分析及改进设计

结合钻杆的受力特点，对其螺纹参数展开研究，建立了接头圆锥梯形螺纹的三维模型，应用有限元法分析了接头螺纹在多种工况下的等效应力与接触应力分布规律；依据分析结果，提出了复合锥度设计与柱面结构密封的改进方案。研究结果表明，新设计有效地改善了内、外螺纹最后啮合处的应力集中，提高了螺纹密封性能。试验结果显示该接头的承载与密封性能达到了设计目标，完全满足煤矿井下定向钻进施工的需要。

Joint Thread design and research for drilling rod with high strength and large through hole

The design of joint thread is the key to high-strength drilling rod with big hole, which is the main drilling tool for horizontal directional drilling in underground coal mine. Firstly, the parameter of joint thread was studied considering the load of drilling rod. Then the 3D model of the joint thread was built and its equivalent stress and contact stress under several working conditions were obtained through finite element method. Based on the analysis, an improved design of dual taper and cylinder seal were subsequently presented. The research results show that the stress concentration and sealing capability of joint are improved. Finally, some filed experiments were given to demonstrate the improved design. The conclusions from the research work have provided a reference for the thread design of other drilling tools.