中文摘要：

针对真空低压消失模壳型铸造工艺中采用的薄壳在失模中易于开裂现象,对失模工艺进行系统研究,考察失模方式、温度对薄壳失模的影响,并结合EPS泡沫材料热失重分析和泡沫模温度场分布规律,分析薄壳开裂机制。结果表明：随炉升温失模过程中,型壳失水收缩缓慢,强度逐渐提高,型壳不易开裂;高温400℃以上直接放入失模,型壳放入不久均开裂,主要由于型壳急速失水收缩受阻所致,而经长时间预烘型壳高温直接放入失模,型壳不开裂;低温250~300℃直接放入失模,型壳收缩相对较慢,主要受到泡沫模的膨胀力作用,膨胀力与失模温度,时间及泡沫模有关。得到低温直接放入时模样厚度与失模温度关系式,模样越厚,所需失模温度越低。

英文摘要：

Considering the thin-shell cracking phenomenon of removing pattern process during the expendable pattern shell casting with vacuum and low pressure,some systemic studies were carried out.The influence of removing method and temperature on removing pattern of thin shell was investigated,and the mechanism of shell cracking was analyzed using the thermogravimetric analysis（TGA） and temperature field of the expanded polystyrene（EPS） foam pattern.The results indicated that shell was not easy to crack due to slow shrinkage of shell dehydration and shell strength gradually increased during removing process with furnace temperature.Because rapid shrinkage of thin shell was hindered,shell rapidly was destroyed during high temperature above 400℃ directly entering furnace,however,the shell preheated for long time did not crack when suffered above removing process.For low temperature 250-300℃ directly entering furnace,the shell shrinkage was relatively slow,and shell was suffered from expansion force of foam pattern.The expansion force is related to removing temperature,time and foam pattern.The relation formula of pattern thickness and removing temperature was deduced for low temperature directly entering furnace,and the more thick foam thickness is,the more low removing temperature is.