铝合金曲轴后端盖压铸模浇注与排溢系统优化设计

为满足某发动机曲轴后端盖铸件高质量的外观与密封要求，针对该铝合金零件进行了高压铸造模具的浇注与排溢系统优化设计。首先根据铸件形貌和尺寸特征进行浇道、内浇口和排溢槽的理论设计，随后采用ProCAST软件模拟高压铸造充型、凝固过程，对铸件的卷气、缩松、缩孔及组织进行预测分析。研究发现，方案1的平直型横浇道浇注方案，金属液冲击型芯容易产生紊流和飞溅，且设置在铸件中间和下部的排溢系统不能减少紊流，易形成裹气和大的缩孔缺陷；而方案2为钳形浇道，去除方案1铸件中部的溢流槽并将下部连通溢流槽改为两个，明显改善铸件内裹气和缩孔现象，确定方案2为最终方案。试模铸件外观质量良好，经X射线探伤发现铸件无裂纹，厚大缩孔位置与缺陷仿真预测良好吻合；金相显微镜(OM)、扫描电镜(SEM)和电子背散射衍射(EBSD)观察组织发现，铸件晶粒细小、组织致密，晶粒取向差小，内部应力小，与组织和应力仿真结果一致；能谱分析(EDS)、X射线衍射(XRD)分析表明，铸件成分均匀，组织内部无杂质。本研究可为端盖类铝合金压铸件模具及工艺开发提供参考。

Optimization design of die casting mold pouring and overflow discharge system for an aluminum alloy crankshaft rear end cap

Considering the requirements of high-quality appearance and sealing of an engine crankshaft rear end cap casting, an optimization design of pouring and overflow discharge system of high-pressure casting mold was conducted for the aluminum alloy part. First, the theoretical design of the sprue, internal gate, and spillway was carried out based on the morphological and dimensional characteristics of the casting. Then ProCAST software was used to simulate the filling and solidification processes of high-pressure casting, and predict the air roll, shrinkage, shrinkage hole, and microstructure of the casting. Results show that under flat runner pouring scheme (Scheme 1), the metal liquid impacting the core was easy to produce turbulence and spattering, and the overflow system set at the middle and lower parts of the casting could not reduce the turbulence, which was easy to form gas trapping and large shrinkage defects. For a pincer sprue (Scheme 2), the overflow groove in the middle of the casting was removed and the lower part of the overflow groove was changed to two, which obviously improved the gas trapping and shrinkage in the casting, so Scheme 2 was determined as the final option. The appearance quality of the test casting was good, the casting was found to be crack-free by X-ray flaw detection, and the location of the thick shrinkage hole was in excellent agreement with the prediction of the defect simulation. Optical microscope (OM), scanning electron microscope (SEM), and electron backscattered diffraction (EBSD) observation of the microstructure showed that the casting had fine grains, dense microstructure, small grain orientation difference, and small internal stress, which were highly consistent with the results of stress and microstructure simulation. The energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis showed that the casting had uniform composition and no impurity inside the microstructure. The study can provide reference for design and process development of aluminum alloy end cap die castings.