我厂生产的自吸式离心油泵进出口弯管,材质为HT20-40,其结构如图1所示。过去,在铸造时,我们按常规工艺采用铸铁芯骨。这种铸铁芯骨一般只能使用一次(因断裂而无法再次使用),因而要花费较多的人工和材料来铸造芯骨。针对这种情况,笔者设计了一种新型、实用、由无缝钢管为材料的芯骨 I plant self-priming centrifugal pump import and export of elbow, made of HT20-40, the structure shown in Figure 1. In the past, when casting, we used cast iron mandrel according to the conventional process. Such cast iron core bones can only be used once (due to the fracture can not be used again), so it takes more labor and materials to cast the bones. In response to this situation, I designed a new, practical, seamless steel tube as the material of the core