乘用车轮毂 90%以上采用铝合金低压铸造工艺实现,轮毂铸造缺陷是影响其机械性能和服役安全性的主要因素之一,因此控制轮毂铸件的缺陷不仅是产品质量问题,也是关乎汽车整体的服役安全性问题.本文系统研究并总结了低压铸造工艺参数对孔洞缺陷的影响.针对低压铸造轮毂中可能产生的缩孔缩松缺陷,研究了浇注温度、模具预热温度、充型速度、保压压力等工艺参数对缩孔缺陷分布规律,发现在一定范围内,浇注温度与模具预热温度的上升,均可使金属液充型能力提高,减少缩孔缺陷;但当浇注温度或模具预热温度过高时,缩孔开始增加.在保证不发生欠充型的前提下,充型加压速度越慢,则充型过程越缓慢平稳,缩孔出现的概率越低.随着保压压力的提高,缩孔缺陷减少.
Over 90%of passenger car wheels are made of aluminum alloys by a low-pressure casting process.Casting defects are among the most important factors influencing the mechanical properties and service safety of automotive wheels.Therefore,controlling casting defects effectively not only is a product quality issue but also impacts the safety of the entire vehicle.The influence of the low-pressure casting process on shrinkage pores is systematically studied and summarized in this paper.To predict the generation of shrinkage porosity defects in low pressure casting hubs,the effects of process parameters such as pouring temperature,mold preheating temperature,filling rate and holding pressure on the formation of shrinkage porosity were studied.The results show that increasing the pouring temperature and mold preheating temperature increases the filling capacity and reduces the shrinkage porosity to a certain extent.However,overheating the mold or a super high pouring temperature will lead to the opposite effects.In addition,slower filling at the laminar stage significantly reduces the shrinkage porosity on the premise of successful filling,and a high holding pressure helps with closing the pores.