发动机连杆螺栓及其紧固

Engine connecting rod bolt and its tightening

发动机连杆螺栓在工作过程中要承受活塞连杆往复运动惯性力和连杆旋转离心力的交变载荷。螺栓选用材料为40Cr，经调质处理后HRC硬度值达39～44。通过减小螺栓的刚度，改善螺纹载荷分布，减小应力集中，提高螺纹强度和表面质量以及？肖除附加应力等措施，能够提高连杆螺栓的疲劳强度。连杆螺栓容易损伤、断裂的原因：设计时选材不当，未按照使用规定和力矩装配；预防措施：选用强度高、塑性好的材料，加工后进行磁粉探伤，装配时按规定紧固，装配前进行检查，装配后进行锁紧。

Engine connecting rod bolt is undertaken alternative load of piston connecting rod bolt alternating motion inertial force and connecting rod bolt rotating centrifugal force. The selecting material of bolt is 40Cr, its HRC hardness value after quenching and tempering can reach 39 - 44. The fatigue strength of connecting rod bolt can be increased through the following measures such as to improve thread loads distribution, to reduce the stress concentration, to increase thread strength and surface quality, to eliminate additional stress and so on. The reasons of connecting rod bolts easily damaged and fractured are as follows： the selecting material is not proper in design, to install not according to using rules and torque. The prevention measures are as follows： to select material with high strength, good plasticity, to magnetic particle detect after being processed, to fasten according to rule while installation, to check before installation, to lock after installation.