螺栓副连接的主要技术指标是拧紧力,但在装配中不能直接显示。旧标准采用额定扭矩(N·m)表示,故大都用扭矩扳手(扭矩法)来控制。其拧紧力误差相当大,实验资料表明,离散度达20～30％,严重影响螺栓连接质量.尤其对大直径螺栓连接,许多情况下常用扳手加套管,拧到拧不动为止。 The main technical specifications of the bolt connection is tightening force, but can not be directly displayed in the assembly. The old standard using rated torque (N · m) said, so most of the torque wrench (torque method) to control. The tightening force error is quite large, the experimental data show that the degree of dispersion of 20 to 30%, seriously affecting the quality of the bolt connection, especially for large diameter bolt connection, in many cases commonly used wrench plus casing, screwed to the rest so far.