等强度多级抽油杆参数和有效冲程计算

Calcultion of parameters of uniform-strength multistage sucker rod string and effective stroke of pumping unit

针对多级抽油杆在抽油机实际工况下的运动情况及受力状态，推导出多级抽油杆的拉伸变形及应力计算公式。在此基础上进一步推导出满足等强度条件的各级杆径、伸长量、最大载荷及抽油机有效冲程的计算公式，并编出相应的电算程序。最后给出实例电算数据和分析结果，认为多级杆中各级杆所受的最大载荷和杆径随级数n的增加而减小，但一般级数以小于7为宜。

In the light of the motion and force status of the multistage sucker rod string under the actual woring conditions of the pumping unit, the equations for calculating the stretcher strain and stress on the rod string are derived. Thereby the equations for calculating the diameter and length of each stage rod the maximum load on the rods, and the effective stroke of the pumping unit are derived, and relevant computer program is generated. An example of calculation and analysis is given, and it is indicated that the maximum load on each stage rod and the rod diameter decrease with the increase of the stage n, and n is generally less than 7.