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一、工艺分析一般情况下,铸件上的小孔是很难直接铸出的,而用机加工成孔。但有的铸件因形状结构的关系,若不铸出小孔,这对铸造工艺的制订、铸件内在质量、生产效率、成本率等都受到影响,如我厂生产的安全阀阀盖(见图),其材质为球铁,一端是直通的大孔,另一端为小孔,且d与d_1都为螺纹,均处于受压状态,且两端肥大中间薄,其铸造难度大。原采用不铸出小孔,废品率一直很高,后用覆砂芯
First, the process analysis Under normal circumstances, the casting hole is difficult to cast directly, and machined into holes. However, some castings due to the shape and structure of the relationship, if not cast holes, which the casting process, the inherent quality of castings, production efficiency, cost rates are affected, as I plant the safety valve cover (see Figure ), The material is ductile iron, one end is straight through the large hole, the other end is a small hole, and d and d_1 are threads, are in compression, and both ends of the middle fat hypertrophy, the casting difficulty. The original does not cast a small hole, the rejection rate has been high, after the core coated with sand