摩托车链轮螺栓的失效分析和工艺改进

FAILURE ANALYSIS ON MOTORCYCLE CHAIN WHEEL BOLT AND THE IMPROVING MEASURE

摩托车链轮螺栓在装配时及在装配好放置几天后出现断裂。应用扫描电镜、光学显微镜和化学分析等检测手段,对链轮螺栓断裂原因进行了探讨。结果表明,链轮螺栓发生脆性断裂属氢脆特征,电镀前酸洗过度是造成螺栓发生瞬间脆性断裂的主要原因,加上模具成型产生折叠缺陷,除氢不彻底等因素的综合影响,加速了螺栓的断裂。提出了提高链轮固定螺栓综合强度的工艺改进方案。

Motorcycle chain wheel is important bolt which join Rear wheel and Chain wheel.It must endure great shearing force and radial stress. The analysis of binding bolt were made by means of SEM, optical microscope and chemical analysis. It is shown that the failure of binding bolt caused by brittle fracture. This paper introduced characters and main reason of the defect, such as extending acid wash time. In addtion fold defect, insufficiency of getting rid of Hydrogen, etc. also influence binding bolt quality. In the same time, the conditions causing brittle fracture and the measure to prevent the crack are also discussed.