汽车发动机下缸体低压铸造工艺及模具设计

针对AC4B铝合金下缸体的结构特征和工艺特点,以GM-L850型发动机下缸体为例,介绍了低压铸造工艺及模具设计。其工艺参数,充型压力为0.02MPa,充型速度为0.5m/s左右,充型时间为25s,结晶压力为0.051MPa,保压时间为90s,浇注温度为(720±10)℃,模具预热温度为220℃,浇注槽温度为(600±50)℃。在模具设计过程中,采用多分型面分型保证顺利开模,合理设计模具壁厚并在铸件厚大部位采用局部冷却,以达到控制模具热平衡,同时采用多种排气方式实现完全充型。生产实践表明,该铸造工艺方案的铸造工艺参数及模具结构合理,产品合格率高,对其他类似产品有参考意义。

Low Pressure Casting Crankcase-lower Bedplate for Automobile Engine and its Mould Design

According to the structural feature and technological characteristics of AC4B aluminum alloy crankcase-lower bedplate,low pressure casting GM-L850 automobile engine crankcase-lower bedplate and its mould design were described.The processing parameters were adopted as follows:filling pressure of 0.02 MPa,approximately 0.5 m/s filling velocity and 5 s filling time,holding pressure of 0.051 MPa for 90s,pouring at(720±10) ℃,and pre-heating mould at 220 ℃ as well as pouring basin temperature of(600±50) ℃.Multi-parting face was adopted in the mould design to ensure the mould-opened smoothly.Mould wall thickness should be rationally considered,in which local cooling was employed at the thick location to realize the heat balance of the mould,meanwhile,various exhausting ways were adopted in the mould design to fill completely.The production shows that the process scheme,parameters and mould structure were feasible,and high qualified production rate was realized.