制造汽车发动机关键紧固件的要点

Essential Points of Manufacturing Key Fasteners for Automobile Engine

为了提高汽车发动机关键紧固件及材料的制造水平,总结了关键紧固件制造过程的控制要点及常见缺陷和原因,其中包括:冶炼过程采用LF+RH/VD工艺确保原材料的纯净度;通过大方坯连铸及“两火”工艺,结合轧制工艺控制组织均匀性、尺寸精度、表面质量及减少脱碳层等以保证原材料的性能和质量;通过合理选择毛坯尺寸及球化工艺等改制工艺以控制脱碳、磷化皮膜及表面质量,提高线材的冷镦成形性;借助CAE进行成形工艺设计以保证获得良好的紧固件流线;对模具、设备、作业规范、检测能力、热处理、搓丝及表面处理等的管控以确保紧固件性能的稳定;采用合理的拧紧工艺并进行装配验证以保证关键紧固件的使用寿命。

In order to improve the manufacturing level of key fasteners and materials for automobile engine,the key control points,common defects and their cause in the process of manufacturing the key fasteners were summarized,among which were:the use of LF+RH/VD process during the smelting to ensure the purity of raw materials;the controlling of microstructure uniformity,dimensional accuracy,surface quality and reducing decarburization by continuous casting of blooms then"two fire"process in conjunction with the rolling process to ensure performance and quality of raw materials;the controlling of decarburization,phosphating skin film and surface quality by reasonable selections of the blank size and reforming procedure such as spheroidizing,thus improving cold heading performance of wire;the design of forming process by the aid of CAE to ensure a reasonable flow line of fasteners;the managing and controlling of die,equipment,operation specification,testing capacity,heat treatment,thread rolling and surface treatment to ensure the stable performance of fastener;and the use of reasonable tightening process and assembly verification to ensure service life of the key fasteners.