消除制动蹄铸造缺陷的工艺改进

Casting Method Improvement to Eliminate Casting Defects of Rear Brake Shoes

介绍了重型卡车车桥用STR后制动蹄的铸件结构及技术要求,并详细阐述了原铸造工艺及存在的问题。为解决铸件出现的夹渣、缩孔问题,进行了分析和对比试验,得出以下结论:(1)制动蹄属于壁厚相对均匀的球墨铸铁件,采用无冒口、分散内浇道进铁液工艺能防止缩孔缺陷;(2)在挡渣效果不良的浇注系统内设置Si C陶瓷过滤器能较好地解决STR后制动蹄夹渣缺陷问题;(3)在保证不出现其它缺陷的前提下,严格控制浇注温度和化学成分对铸件的稳定生产很重要。

The casting configuration and technical requirements of STR brake shoes used for heavy truck were introduced and the original casting method and existing problems were described in detail. In order to solve the problems with slag inclusion and shrinkage defect,analysis and comparable tests were conducted,and the following conclusions were obtained： （ 1 ）Since the brake shoes were the nodular iron casting having relatively uniform wall thickness,it＇s possible to prevent shrinkage defect by using the riser-less casting method with metal entering into mold through separated ingates.（2）Setting SiC ceramic filter in the gating system having not good slag skimming effect could solve the problem with slag-inclusion of the STR brake shoes. （3） Strictly controlling pouring temperature and chemical composition under the precondition without other defects occurring was very important to stable production of the casting.