变螺距套管螺纹在轴向拉力作用扣牙力分布及计算

理想等螺距管螺纹接头在轴向拉力作用下，扣牙力分布呈抛物线状，制约了管螺纹接头的承载能力。采用适当的变螺距工艺可使扣牙力分布得以改善，从而提高套管柱承载能力。本文用解析法求出了变螺距管螺纹接头扣牙力分布曲线，探讨了变距方式、变距量和变距点等问题。

Distribution and Calculation of Detention Force of Casing Thread with Variable Thread Pitch under Axial Tention

Distributions of detention forces of ideal equal thread pitch casing connections presents parablic shape under axial tention, which kills the load bearing capability of casing connections. Proper variate thread pitch techniques can be adopted to improve the distributions of detention forces, so as to strengthen casing strings'loadsupporting capability.The authorfigures out distribution carves of detention forces of casing screw thread with variable thread pitch by use of analyticlemethod,and approaches thread- pith-changing way.