在传统浇注系统中，钢水流经砂型易形成冲砂，而液料不稳定时易导致夹砂、表面水纹等缺陷。 传统排气系统中，钻气眼后气道内易形成浮砂，导致铸件夹砂，在铸件本体气眼切割时易切伤铸件形成缺肉缺陷。 为系统改进产品，持续提升铁路货车钩舌铸件内外质量，通过采用双通双注式浇口杯、改进浇注方法、设计一体式拼接耐火材料横浇道、试用网格排气阀、试验多类型砂种、优化专用砂箱工装等多项措施，显著改善钩舌内外质量，铸件质量合格率由 82% 提高到了 96% 以上。

 In traditional pouring systems, molten steel flowing through a sand mold easily undergoes sand washing, which leads to sand inclusions, surface water marks and other defects when the liquid material is unstable. In traditional exhaust systems, floating sand easily forms in the airway after the air hole is drilled, resulting in sand inclusion in the casting. When cutting the air hole of the casting body, it is easy to cut the casting to form a lack material defect. To continuously improve the internal and external quality of knuckle castings for railway freight cars, a number of measures, such as adopting double-pass double-injection pouring cups, improving pouring methods, designing integrated splicing refractory runners, testing grid exhaust valves, testing multiple types of sand, and optimizing special sand box tooling, significantly improves the quality of the knuckle, increasing the qualified rate from 82% to over 96%.