油井管特殊扣产品管拧曲线拐点识别方法

Identification method of shoulder torque of screw-on curve for premium products of oil pipe

介绍了管拧曲线各部分的含义、拐点的定义和常见特征,常用的曲线曲率半径拐点识别方法的原理和缺点。基于拐点识别要求,提出了密封面变形法识别方法,阐述了PW值的计算方法和原理,并总结了这种方法的优点。密封面变形法既考虑了拧紧扭矩差异值,也计算了密封面弹性变形量,真实反映了螺纹脂的状态,密封面受压后的扭矩变化和弹性变形的相关性。

This paper introduces the meaning of each part of screw-on curve,the definition of shoulder torque and common characteristics.This paper introduces the principle and shortcomings of the commonly used method of curvature radius method.Based on the requirements of shoulder torque recognition,a new method of seal-surface deformation method is proposed creatively.This paper expounds the calculation method and principle of PW value,and summarizes the advantages of this method.This method not only considers the difference value of tightening torque,but also calculates the elastic deformation of seal-surface,which truly reflects the state of thread grease and the correlation between torque change and elastic deformation of seal-surface after compression.