双耳托板螺钉断裂原因分析及改进措施

双耳托板螺钉装配过程中在托板与杆部结合处发生断裂。对断裂螺钉进行断口形貌分析,确定断裂性质为过载断裂;对同批次螺钉进行了金相、硬度、拉力试验、楔负载试验以及模拟安装试验,结果表明,螺钉断裂原因主要与断裂位置流线密集有关,同时热处理制度不匹配和流线被切断对断裂有促进作用。针对螺钉断裂有关原因提出了改进冷镦工艺、调整热处理制度和优化头(托板)杆加工工艺等改进措施,并对改进效果进行了验证,结果表明改进有效,新工艺加工的螺钉装配过程未再发生相同断裂现象。

Fracture reason analysis and improvement measures of binaural plate screw

Fracture occurred at the joint between the bracket and the rod during assembly of the binaural plate screw. The fracture morphologies and characteristics of the broken screw were analyzed and identified as overload fracture. According to the metallographical analysis, hardness test, tensile test, wedge load test, and simulated installation test performed on the same batch of the screws, the results show that the cause of the screw fracture is mainly related to the intensive streamline at the fracture position, while the mismatch of heat treatment system and the being cut off of the metal streamline promote the fracture. Improvement measures such as improving the cold heading process, adjusting the heat treatment process and optimizing the processing of the head (supporting plate) rod were put forward for the screw fracture reasons. The improvement has been verified as effective, and no same fracture occurs during the screw assembly manufactured by the new process.