轴法兰螺栓安装失效机理分析

某船在安装过程中发现轴法兰螺栓联接副存在不同程度的咬合。通过现场检查和计算分析,确认螺栓安装失效机理在于加工孔时刀具装夹不正,造成轴法兰沉孔的平面度超差,在对螺栓施加拧紧力矩时,螺栓联接副接触应力超过轴材料屈服强度,从而形成咬合。本文以经典计算和有限元计算作为支撑,揭示了形位公差对螺栓联接的影响,通过控制螺栓联接副的形位公差,同时建议采取适当的防咬合措施,可避免螺栓在安装时发生失效。

Mechanism Analysis of Installation Failure of Flange Bolts

The joint pairs of flange bolts of a certian ship are found in different degree of bites during the installation. The failure reason is found that the tool clamping is not straight when punching through the on-site inspection and the finite element analysis. The flatness of flange holes are more than the tolerance size, and the surface of flange holes are concave. When the tightening torque applying on the bolts, the contact stress between bolts and fittings over shaft material yield strength, thus the bolts bite into the fittings. In order to reveal the influence of geometric tolerance of bolts connection, a method is supported by using classic calculation and finite element technology. The installation failure of flange bolts can be avoided by controlling the geometric tolerance of bolts connection and adopting the appropriate bite-proof measures.