杆头加工偏差对抽油杆强度的影响

Influence of machining deviation of sucker rod head on rod strength

以CYG－22B抽油杆为研究对象，当杆头螺纹轴线和杆身轴线有加工偏差（偏心、偏斜或二者同时存在）时，对其应力集中系数进行了较系统的三维有限元分析和试验验证。结果表明，由偏心和偏斜所产生的应力集中位于接近过渡区的一个不大的范围内。在不考虑加工偏差的理想联接状态下，抽油杆杆头各部位的应力集中系数均小于1，杆头上应力集中最严重的部位在扳手平面上下两端面，其数值分别为0．811和0．747。本计算所得结果为抽油杆失效分析和制定允许加工偏差及验收标准提供了依据。

By taking Model CYG-22B sucker rod as an example, when there exists deviation(eccentricity, deflection or both)between the rod head thread axis and the rod body axis, the stress concentration coefficient is analyzed by the three-di-mensional finite element method and examined by test. The result shows that the stress concentration caused by eccentric-ity and deflection located in a smail part near the transition region. Under the condition of an ideal connection ignoringthe machining deviation, the stress concentration coefficient of every part of the sucker rod is less than 1, and the mostserious stress concentration on the rod head located on the top and lower end surfaces of the mench squarei the corre-sponding stress concentration coefficients are 0. 811 and 0. 747- The result of the calculation provides a basis for thesucker rod failure analysis and allowable deviation stipulation and check standard formulation.