抽油杆柱在上、下行程状态的中和点位置不一样。其上、下行程状态中和点区间的杆柱，所受到的内力（轴向力）方向总是呈周期性地受拉、压交替变换的。这是直接造成该区间杆柱联接螺纹松动的主要原因。为此，提出适宜的紧扣预紧力、合理的紧扣方法，以及机械防转动结构等措施供思考。 Sucker rod in the upper and lower stroke state of the neutral point position is not the same. In its up and down stroke and the midpoint of the interval between the column, the internal force (axial force) received by the direction of the periodic tension and pressure are always alternating transformation. This is a direct result of the interval rod linkage thread loose the main reason. To this end, put forward the appropriate tight preload, a reasonable method of fastening, and mechanical anti-rotation structure and other measures for consideration.