空调压缩机铸铁曲轴的半固态挤压铸造过程模拟

Numerical simulation of thixotropic extrusion casting for cast iron crankshaft in compressor of air condition

采用Procast软件基于PLCO粘度模型建立了半固态挤压铸造工艺成形空调压缩机铸铁曲轴的数值模拟模型,并获得其合理工艺参数为：坯料浇注温度1165-1185℃、模具预热温度300-400℃、冲头充填速度0.05-0.25 m·s-1。模拟结果表明,浇注温度过低或冲头速度过低时,不能完整填充型腔;冲头速度过大,充填型腔中浆料发生湍流现象,容易卷气;铸件凝固时间随着模具温度的升高而升高,但是过高的浇注温度或模具温度容易使零件产生缩松缩孔缺陷;对半固态挤压铸造工艺和液态挤压铸造工艺进行分析比较,发现半固态挤压铸造成形可以避免液态挤压铸造成形工艺中存在的卷气严重、不能实现顺序充填和热节较大等缺陷。

Based on PLCO viscosity model, a 3D numerical simulation model of cast iron crankshaft in the compressor of air condition manufactured by semi-solid squeeze casting process was established by Procast software. Reasonable process parameters were obtained, namely the casting temperature of 1165 - 1185 ℃ for billet, the preheating temperature of 300 - 400 ℃ for die, the filling speed of 0. 05 - 0.25 m · s - 1 for punch. The results show that the cavity cannot be completely filled when the pouring temperature is too low or the punch speed is too slow. When the punch velocity is too high, and turbulence occurs during the mould filling, air will entrap easily. The solidification time of the casting increases with the rising of die preheating temperature, but extreme high pouring temperature and mould temperature can cause shrinkage porosity defect in the casting process. A comparative analysis between the semi-solid squeeze casting process and the liquid squeeze casting process shows that the former can avoid the defects caused by the latter such as serious entrapped air, non-sequence filling and big hot spot.