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据报道(见参考资料),英国专家研究出一种用螺栓自身结构保证预紧力的装置——测力螺栓,它可以随时判断正在拧紧的螺栓是否达到了设计预紧力的要求,相对误差可控制在±5％之内。 测力螺栓的测力原理很简单: 在标准螺栓的头部打一个直径为d_0的中心孔(见图),孔中旋入测力销钉。标准螺栓头部的外侧与测力销钉套环的内侧端面之间,保留有精确的预留间隙δ,δ值与标准螺栓的最佳预紧力相对应。δ的大小由本文后面推荐的公式计算。 安装螺栓时,随着螺帽拧紧,轴向拉力增加,螺杆受力伸长,带动测力销钉使预留间隙δ逐渐缩小,直到轴向拉力等于设计预紧力时,间隙完全消除。以用手不能拧动销钉套环作为判定间隙完全消
It has been reported (see references) that British experts have developed a device that uses a bolt’s own structure to ensure a pre-tightening force-a force-measuring bolt that can at any time determine whether the bolt being tightened has reached the design preload requirement, the relative error Can be controlled within ± 5%. Force measuring bolt principle is very simple: the standard bolt in the head hit a diameter d_0 center hole (see photo), the hole into the force measuring pin. Between the outer side of the standard bolt head and the inner end face of the force-measuring pin collar, a precise reserve of clearance δ remains, corresponding to the optimum preload of the standard bolt. The size of δ is calculated from the formula recommended later in this article. When the bolt is installed, as the nut is tightened, the axial tensile force increases and the screw is forced to expand, driving the force pin to gradually reduce the reserved gap δ until the axial tensile force is equal to the design pre-tension, and the clearance is completely eliminated. With hands can not screw the pin collar as a complete decision to eliminate the gap