输电铁塔螺栓紧固特性影响因素试验研究

Experimental study on factors of bolt fastening characteristics for transmission line tower

为了保障输电铁塔螺栓连接的可靠性,基于试验方法对影响输电铁塔螺栓紧固特性的关键因素进行研究,以典型的输电铁塔用M16和M20规格6.8强度等级螺栓为研究对象,通过开展不同参数条件下螺栓的静态预紧力和振动条件下螺栓松动特性测试,确定影响螺栓静、动态紧固特性的主要因素。首先基于螺栓静态预紧力测试系统,研究了不同扭矩、表面粗糙度、表面镀锌以及润滑等因素对螺栓连接轴向静态预紧力的影响规律,结果表明,施工扭矩与螺栓静态预紧力近似呈线性关系,在相同施工扭矩下,表面镀锌会导致静态预紧力减小,而表面润滑可大幅提升预紧力;进而研究了螺栓连接在振动下的松动特性,基于横向振动试验机,研究振动幅值、频率以及初始预紧力等因素对螺栓松动特性的影响规律,明确不同条件下螺栓松动机制。试验研究结果表明,随着振动幅值增大,螺栓残余预紧力显著下降,但振动频率对螺栓动态特性影响微弱;对螺栓表面进行润滑会造成残余紧固力降低;此外,螺栓的松动概率和数据离散性随初始预紧力的增加而降低,这对预防输电铁塔用螺栓松动有着积极意义。

In order to ensure the reliability of the bolt connection of the transmission line tower,the key factors that affect the bolt fastening characteristics of the transmission line tower based on the test method were studied.Taking the typical M16 and M20 bolt with grade 6.8 as the research object,the static and dynamic fastening characteristics of the bolt were determined under different parameters by testing the static pre-tightening force and the dynamic loosening performance,respectively.Firstly,based on the bolt static pre-tightening forcetest system,the influences of different torque,surface roughness,surface galvanizing and lubrication on the axial static pre-tightening force were studied.The results show that the construction torque and bolt static pre-tightening force are approximately linear.The static pre-tightening force decreases when the surface is galvanized,but increase greatly with surface lubrication under the same construction torque.Based on the transverse vibration testing machine,the influences of vibration amplitude,frequency and initial pre-tightening force on bolt loosening characteristics were studied,and the bolt loosening mechanism under different conditions was accordingly clarified.The results show that with the increase of vibration amplitude,the residual tightening force of bolts decreases significantly,but the vibration frequency has little effect on the dynamic characteristics of bolts;surface lubrication will reduce the residual tightening force;in addition,the loosening probability and data discreteness of bolts decrease with the increase of initial preload,which has positive significance for preventing bolt looseness of transmission line tower.