The Processes Research On Large Complicated Stainless Steel Impeller By Melting Modules-Sand Mould Composite Casting

Casting impeller is a key component which is used for many large equipments, such as ship building, electricity, pharmaceuticals, pump and valves and transportation, etc. And it will play a decisive role in the whole equipment's integrated performance. A certain difficulty for the complicated impeller's casting craft still exists in the current production. So on this aspect research has always been a hot topic in the casting Industry. Based on the analysis and research for the large complicated impeller's casting craft, the present study aims at exploring a kind of melting modules-sand mould composite casting process which is economical and practical, in order to meet specification under the current equipment condition.Based on the structure feature of impeller casting, the impeller is divided into two parts: the complex shape leaves and simple shape spoke and wheel hub. On the one hand, for the shape complex leaves, melting modules of single leaves was pressed by pressure type, and the single leaves group then was melted the melting module of the whole leaves by the aid of design. Silicone alternate - silicate glass compounded type shell was made by the paints. After the shell with silicate on the edge of the lamina was made, the whole blade's melting was moduled by the dewaxing and roasting. On the other hand, for the simple shape's spoke and hub, the wooden appearance and core box was made according to hub and spoke's lower and upper end surface including outline size of leaves shell. The simple shape spoke and wheel hub was obtained by silicate glass sand core and riser system design, and the sand mould of composite casting's riser system was used a same process. Based on the above research, the melting modules-sand mould composite casting was combined by melting modules shell and sand mould casting type. A set of modular sodium silicate sand is made as a benchmark. The ZG1Cr18Ni9Ti stainless steel impeller casting was gotten by batching, induction furnace melting, pouring, oxyacetylene flame shock OFC, and chemical cleaning.Through the appearance examination and size measure, the results showed that the sizeaccuracy of casting impeller achieved CT4~CT5, and the roughness achieved Ra3.2~1.6. The study by the key spots coloration seepage and the supersonic crack detection also showed the impeller had no defections such as crack, shrink hole, shrink and mixture. Moreover, the components check and the performance testing indicated this kind of impeller could satisfy the specification in chemical composition and mechanical performance.As a conclusion, this kind of impeller's quality not only meets technical and production need, but also had a stable process and lower production cost.