型腔中气体对薄壁铝合金铸件充型能力的影响

采用一体化反重力铸造机在不同的试验参数下,浇注高300 mm,宽60 mm,壁厚分别为2mm、3mm和4mm的D357铝合金试样.分别从浇注过程中铸型的发气量、型腔中预有气体、排气条件三个方面研究了型腔中气体对薄壁铝合金铸件充型能力的影响.结果表明:在调压铸造条件下,当砂型发气量较大时,铸件最后充填位置容易产生浇不足缺陷,铸件内部容易产生大量气孔缺陷.在排气较弱的条件下,调压铸造充型能力最好,低压铸造次之,差压铸造的充型能力最差.调压铸造时,型腔中气体较少,采取不同的排气措施对薄壁铸件的充型能力影响不大,低压铸造时,当排气能力较弱时,薄壁铸件的充型能力显著下降,同时容易出现裹气现象.

Influence of Gas in Mold Cavity on Mold-Filling Capacity for Thin-Walled Aluminum Alloy Castings

D357 aluminum alloy sheet samples with height 300 mm,width 60 mm and thickness respectively 2 mm,3 mm and 4 mm were poured by integrated anti-gravity casting machine under different test parameters.The influence of gas in cavity on the mold-filling capacity was studied on the three aspects such as gas evolution,gas in the cavity prior to pouring and exhaust condition.The results show that under the condition of adjusted pressure casting,when the gas evolution of sand mold was larger,misrun easily occurred at the final filling position and there were many blowholes in the casting.Under the weaker exhaust condition,adjusted pressure casting has the best mold-filling capacity,followed by low pressure casting,and counter pressure casting was the worst.Under the condition of adjusted pressure casting,the gas in the cavity was fewer and different exhaust condition had little effect on the thin-walled casting.However,under the condition of low pressure casting,when the exhaust capacity was weaker,filling capacity decreased significantly and gas trapping phenomenon easily occurred in the thin-walled castings.