机匣件真空熔模铸造的数值模拟

Numerical Simulation of Vacuum Investment Casting Cartridge Receiver

涡轮发动机机匣整体铸造时,由于型壳直径大,形状复杂,极易出现缩孔缩松缺陷。为了改进其工艺方案,采用商用软件ProCAST建立了该件真空熔模铸造过程的数学模型和物理模型,考虑装炉方式,对充型、凝固过程中的流场、温度场演变及缩孔缩松形成过程进行了仿真,并用实验验证了计算的正确性。对不同工艺方案下铸件缩孔缩松缺陷的形成进行了模拟,计算结果显示,830℃不垫砂预热后浇注产生的缩孔缩松较多,1 100℃垫砂预热浇注产生的缩孔缩松很少。根据计算结果可以预测后者为较优工艺,有利于减少缺陷,提高成品率。

Shrinkage porosity easily happens in integral investment casting of cartridge receiver due to the large diameter of the shell and the complicity of the shape. In order to improve the casting process, the mathematical and physical models including the condition in the furnace are established via the commercial software ProCAST to describe the vacuum investment casting procedure of the casting, and the evolution of the flow field and temperature field as well as the formation of shrinkage porosity are simulated. The result is validated by experiment. The shrinkage porosity by different casting processes is also calculated. The computing result indicates that more shrinkage porosity happens when the preheating temperature is 830 ℃ and no sand cushion is used, while much less shrinkage porosity happens when the preheating temperature is 1 100 ℃ and sand cushion is used. It can be concluded from the result that the latter process is a better one to avoid shrinkage porosity and increase the qualification rate of products.