曾亮1,2，李文广1,2，张志伟1,2，李雷1,2
1.内燃机可靠性国家重点实验室，山东潍坊261061;2.潍柴动力股份有限公司，山东潍坊261061
摘要：为解决某拖拉机用发动机飞轮壳螺栓断裂故障，通过宏观断口和受力分析、加工质量和材料检验等手段对螺栓进行失效分析，结果表明:螺栓失效原因为低周疲劳断裂，疲劳源位于螺纹牙底，M12螺栓孔附近表面被压溃，螺栓轴力松弛，周围的M10螺栓承受较大的拉压交变应力，产生疲劳，发生断裂。将螺栓承压面改为法兰面，增大接触面积。经计算，优化后螺栓接触区域的面压符合要求。飞轮壳更换新螺栓后市场上未反馈相同故障，改进措施有效。
关键词：飞轮壳；螺栓；断裂
Abstract:In order to solve the problem of bolt fracture of flywheel housing for a tractor used diesel, the failure analysis is carried out by means of macro fracture, machining quality, material inspection and force analysis. The results show that the lowcycle fatigue fracture of the bolt occurs, and the fatigue originate from the outer circle of the bolt. Due to the crushing of the surface near the bolt hole of connector M12, the axial force of the bolt is relaxed, and the bolt is easy to loosen. Then the surrounding M10 bolts bear a large alternating stress, resulting in fatigue and fracture. Accordingly, the bolt bearing face is modified to be flange face, and the contact area is increased, the tightening process is also reformulated. The stress is lower after the refinement, and no feedback fault reported from the market.
Keywords: flywheel housing; bolt; fracture
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